Steam Turbine Maintenance Manual-1 [PDF]

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Preface This Maintenance Manual for Steam Turbine Part is based on manufacturer’s maintenance instructions and associated drawings on turbine equipment employed in PACITAN 2×315MW coal fired power plant. It is only suitable for turbine maintenance in this power plant. The manuals will be revised and improved with the project progress development.



Page 2 of 241



3.1 Comprehensive Instruction of Turbine System 3.1.1 Overview of Turbine System 3.1.1.1



Main steam system Live steam from boiler enters main steam valves and control valve assembly on both sides of casing in double flows. Steam from control valve is carried by main steam pipeline to the upper part and lower part of casing, where it is divided into 4 flows that enter 4 high pressure steam chambers separately at the same time. Passing through high pressure single-row governing stage and pressure stage, it flows into the middle part of low pressure casing through 2 connecting pipes with diameter of 900mm, which are on top of the exhaust turbo of HP and IP casing. After that, it flows into double-pass LP casing with 6 stages in each pass to continue to do work. Then, the steam is discharged into condenser where it is condensed into water. The condensate water out from condenser flows into deaerator through 4 low pressure heaters. With increased pressure from feed water pump, it flows into 3 high pressure heaters, and then enters boiler.



3.1.1.2



Extraction System: The unit is with 8-stage non-regulating extraction, namely, 3 stages of high pressure heater, 1 deaerator and 4 stages of low pressure heater. All the extractions are equipped with check valves,which are with pneumatic control(controlled by compressed air). When unit is shut down or with load rejection, compressed air pipeline will close check valve to keep casing from returned steam or water.



3.1.1.3



Compressed Air Pipeline System for Extraction Valve: The extraction valve of this unit is with pneumatic control system. The pressure of working air source is 0.47-0.67Mpa, which should be clean and dry. Make sure the compressed air pipes are clean and with no debris when installing. Compressed air is divided into several loops by pilot valve, which will enter 2-position 3-way solenoid valve and quick exhaust valve after going through air filter and oil atomizer. Finally, it enters the piston cylinder on operation seat. The pneumatic control is that when turbine operation parameters meet the certain requirements, compressed air enters solenoid valve (Normally open) through air pilot valve. Then it enters piston cylinder on operation seat and makes piston open extraction valve against spring force. When main steam valve is closed or with load rejection, air pilot valve is closed to cut off the compressed air. At this time, solenoid valve activates to prevent compressed air from entering piston cylinder. Air in piston cylinder is exhausted into the atmosphere through quick exhaust valve. Under the effect of spring force, the piston on operation seat make extraction check valve closed. Check the flexibility by operating the system regularly.



3.1.1.4



Water Spraying Pipeline System of Low Pressure Casing: When rotary speed is 2600 rpm, water spraying system is put into operation



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automatically, which will be running continuously until the unit is with 15% load. It is mainly controlled by solenoid valve. When the rotary speed of unit drops to 2600rpm, control system will cut off the power supply to solenoid valve, which will make solenoid valve closed and stop spraying. Besides, no matter it is under what condition, when steam exhaust temperature of low pressure casing is higher than 80℃, water spraying is activated. 3.1.1.5



Steam gland system The design purpose of gland system is to keep steam inside turbine from leakage along axial line. For the reason that once the steam is leaked, it will enter bearing seat, which will further cause oil and water mixture. This will influence oil quality and pollute the environment and equipment. To block leakage on both ends of shaft in low pressure casing is a must so as to make it get used to stable and reliable vacuum. This can improve the heat recycling economy. Another important way to improve the economy is to block and collect leaked steam on stem. Gland system can keep the pressure of steam sealing chamber between every casing and stem at 0.095 Mpa by connecting it with gland seal heater to make sure of no sealing steam leakage. To make it easy for gland seal heater to work normally and keep it from undue deviation under variable working condition, connect the second chamber of gland seal with steam supply pipes controlled by gland seal regulating valve and keep its pressure between 0.117 and 0.131Mpa under all working conditions. The pressure of main steam supply pipe is regulated by 3 air-controlled film executive valves, which are called high pressure steam supply control valve, auxiliary steam supply control valve and overflow control valve. Each valve is equipped with 1 pressure control pilot valve (installed on valve) and 1 air pressure-relief valve with integral filter. Compressed air with constant pressure of 0.1378-0.1516Mpa (a) is supplied to control pilot valve from pressure-relief valve, which is used by control pilot valve to generate a variable output that changes along with the variation of pressure transferred by signal tube of main steam pipe of gland seal to pilot valve. Therefore, control regulating valve can maintain seal steam at the pressure set by its set point under all working conditions of turbine.



3.1.1.6



Draining system: Draining system is very important in steam turbine. It prevents water entering high temperature part of turbine, avoid turbine damage. It is one of the important measures to ensure turbine startup and shutdown. The system is equipped with two sets of drain flash tanks which connect with HIP casing and various drainage, such as valves and piping. The characteristics for draining arrangement are the following:In order to prevent drainage backflow, HP drain flash tank and IP drain flash tank are divided by pressure class of each drainage. All drainage piping connects to drainage main pipe in turn according to pressure class. Drainage main pipe connect with flash tank. The drainage is discharged to condenser bottom through the pipe that connects with drain flash tank bottom. The top of drain flash tank connects to condenser throttle through



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pipe. 3.1.1.7



Lubricating oil system: The lubricating oil system in this turbine supplies lube oil to working medium for turbine overspeed trip device, bearing, generator bearing, thrust bearing and turning gear. The system consists of the following components: a Lube oil tank b Main oil tank c Auxiliary tank d Oil ejector e Jacking oil system f Oil cooler g Oil purifying system h Emergency trip system



3.1.1.7.1



Lube oil tank Lube oil tank is a large carbon steel container. Lube oil is stored in this tank. Oil pump supply the various required oil from oil tank. Lube oil system is an enclosed system, all oils flow back into oil tank. Oil pump, oil discharge system, terminal box, electric heater, liquid level alarm and so on driven by auxiliary motor are installed the top of oil tank. Inside the oil tank, each pump outlet is connected to the relevant main oil supply pipe by piping. While unit is in rated rotating speed or close to rated rotating speed, oil ejector which is installed main oil pump outlet piping uses HP oil extracts oil from oil tank. The strainers are equipped at the oil ejector inlet, bearing oil pump inlet and return oil piping is good for eliminating foreign matters in system. No manhole on the top of oil tank, drain outlet is provided at the bottom of oil tank.



3.1.1.7.2



Main oil pump: Main oil pump has the independent shell. It equipped at turbine rotor of the front bearing pedestal. It has a large capacity, steady outlet pressure. While turbine is in rated rotating speed or close to rated rotating speed, main oil pump supply all the required oil for lubrication system. Main oil pump can not absorb oil automatically; continuous supplying pressure oil is a must. During startup and shutdown, oil supplying by auxiliary oil pump. While turbine is in rated rotating speed or close to rated rotating speed, supplying oil to mail oil pump by oil ejector. The piping on main oil pump outlet connect oil tank with oil ejector inlet, and also connect to mechanical overspeed and manual operation trip main oil pipe by orifice.



3.1.1.7.3



Auxiliary oil pump: Bearing oil pump (LP AC electric pump) Bearing oil pump is AC motor-driven vertical oil pump. It is installed on the top of oil Page 5 of 241



tank. The flow rate is 154.8m 3/h, outlet pressure is 0.295MPa (g), rotating speed is 2950r/min, motor power is 30KW. Put this pump into service during startup and shutdown, and also as the reserved pump during accident working condition. During normal operation with rated rotating speed, shut down bearing oil pump. All oils are supplied by main oil pump. Bearing oil pump controlled by oil pressure switch. Put bearing oil pump into service if the bearing oil pressure reaches 0.05MPa, oil pressure is increased the required value. But the pump will not be shut down automatically; manual operated shutdown is a must. Before unit turning during startup, bearing oil pump should be put into service and be shut down until adequate required oil supplied by main oil pump. 3.1.1.7.4



Emergency oil pump (LP DC electric pump) The flow rate is 154.8 m3/h, outlet pressure is 0.295MPa (g), rotating speed is 3000r/min, motor power is 30KW. The structure and operation for emergency oil pump and bearing oil pump are the same. The emergency oil pump is driven by DC motor which is supplied power by plant battery. For the set value of pressure control switch, emergency oil pump is low than bearing oil pump. During startup, control switch of emergency oil pump should be put AUTOMATIC after bearing oil pump achieves the adequate oil pressure. If the bearing oil pressure drops to 0.04MPa, the emergency oil pump will be put into service. Therefore, emergency oil pump as a reserved pump for bearing oil pump.



3.1.1.7.5



Oil ejector: Oil ejector consists of nozzle, mixing chamber, throttle and diffusion tube. Inlet oil pipe of oil ejector connects with main oil pump outlet. The pressure oil from main oil pump flow through nozzle, oil pressure drops, flow rate increases, the oil in oil tank is induced to oil ejector diffusion tube. The flow rate drops and a part of kinetic energy is recovered to pressure energy while oil enters diffusion tube. Therefore, HP oil pressure drops after flowing through oil ejector, flow rate increases. Oil ejector is installed inside of oil tank; oil inlet must be set under the lowest oil level.



3.1.1.7.6



Jacking oil system: Jacking oil system uses main pipe system. It is equipped with two sets of HP piston oil pumps. Open jacking oil pump before turning gear startup. HP oil（8～12MPa）flows through HP oil piping into elliptic pressure oil tank by bearing pad end, that is formed pressure jacking journal away from bearing pad （ 0.02 ～ 0.03mm ） , to eliminate friction and greatly reduce starting torque of turning. As a result, turning motor power is reduced and then turning is put into service successfully. Four bearings for turbine and two bearings for generator are equipped with jacking function.



3.1.1.7.7



Oil cooler: Lube oil temperature is regulated by oil cooler. The unit is equipped with two sets of oil coolers. During normal operation, one is in use, one is standby. Under abnormal circumstance, two oil coolers can be in operation at the same time. Oil cooler Page 6 of 241



connects with bearing oil pump and oil ejector outlet. Therefore, oil flows through oil cooler first then enters into bearing to ensure lube oil outlet temperature keeps the range of 35～45℃. 3.1.1.7.8



Oil purifying system: Oil purifying system is used for removing water content, solid particle and other foreign matters from lube oil. So that oil quality that has been filtered can be meet the operation requirement to ensure unit safety operation and oil service life extension. The oil purifying system consists of setting tank, filter tank, oil tank, ventilator, automatic water pumping device, gear or oil delivery pump, V-shaped separate strainer, bag filter, filter cartridge and interaction piping. Not only small amount oil can be extracted to process and then back to oil tank, but also large amount oil can be extracted to store in oil tank. If the latter method is used, the absent oil should be replenished by purified oil from oil tank to keep the normal oil level. The system should be put into service before turning startup. Oil purifying system should be kept running during lube oil system is in operation. This equipment should not be used before oil circulation. It only can be activated after oil circulation to meet the oil requirement. The main technical indexes are the following: Water content in outlet oil should be less than 0.05%. Sphere diameter for mechanical admixture should be more than 25 microns. The filter precision for mechanical admixture with 5 microns sphere diameter should be 94～98%.



3.1.1.7.9



Emergency trip function: Lube oil also as a control medium for diaphragm valve. Diaphragm valve is installed on front bearing pedestal. It supplies the connector for mechanical overspeed and manual operation trip part in lube oil system with automatic shutdown emergency trip part in HP fire resistant oil. The lube oil from mechanical overspeed and manual operation main pipe is supplied to the top of diaphragm valve to make it overcome spring force to close valve. Therefore, oil drainage passage for HP fire resistant oil in automatic shutdown and emergency trip main pipe is blocked. If the oil pressure in automatic shutdown and emergency trip main pipe drops (for example, caused by manual operated trip or overspeed trip), diaphragm valve will be opened by spring, drain the HP fire resistant oil and shut down turbine.



3.1.2



The summary sheet of equipment parameters, figure and performance chart for turbine system



3.1.3



The summary sheet of equipment drawing for turbine system



3.1.3.1



Equipment overall arrangement drawing and installation diagram



3.1.3.2



Equipment structure diagram



3.2



Turbine Maintenance



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3.2.1



Regulations of Maintenance



3.2.1.1



Purpose and Principle of Maintenance: 1)



Excellent turbine equipment maintenance is crucial to ensure safety and economical operation of turbine generation units, enhance power generation coefficient, and make full use of equipment potentiality. It is one important section during the whole-process management of equipment. Every maintenance personnel have to pay great attention to maintenance work with high-quality sense. Throughout repair & maintenance tasks, the criteria of “Quality First” should be bore in mind. It must follow the policy that required maintenance items must be conducted and maintenance tasks must be with excellent outcomes. Do not leave problems with the equipment unsolved for pursuit of power generation index or avoidance of the outage performance assessment. On the other hand, do not ignore repair quality and neglect some aspects in order to shorten the emergency repair time. Also, try to avoid unnecessary costs and waste of resource and money to disassemble and replace components and equipment without careful consideration.



2) Based on turbine maintenance management level and actual condition of the equipment, the policy of “Preventive Measure and Scheduled Maintenance” should be put into practice. Research and study should be done. The maintenance plan should be practical and applicable. Each maintenance personnel have to treat the maintenance plan and project seriously. The plan cannot be changed at pleasure. If it has to be revised, one official application has to be submitted to the senior department for approval. 3.2.1.2



Basic responsibilities of turbine maintenance include:



3.2.1.2.1



All work has to be completed within stipulated deadline and meets quality standards.



3.2.1.2.2



Advanced technology and new technology as well as new methods have to be adopted. New material and new tools have to be positively popularized. In this way, work efficiency can be enhanced and maintenance period can be shortened.



3.2.1.2.3



Raw material has to be saved and used appropriately. Do not misuse or waste. Repair the old equipment and components that are replaced in time.



3.2.1.2.4



The equipment and system condition have to be familiarized and inspected frequently. Remove the equipment defects in time. Maintenance plan and rush repair in emergency assignment should be completed.



3.2.1.2.5



Safety work has to be done to prevent personnel and equipment damage accidents from happening.



3.2.1.3



Regarding turbine maintenance management, the following basic work has to be done: With reference to turbine maintenance related rules, implementation details, such as



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maintenance quality standards, technical methods, approval system, and equipment defect management system, equipment changing management methods and spare parts and material management methods, has to be drawn up or re-stipulated. 3.2.1.3.1



The management of turbine equipment and system technological information, as well as technology condition has to be done. The original material about the equipment system has to be collected and processed. Level to level administration has to be implemented and responsibilities have to be clarified.



3.2.1.3.2



Management of maintenance tools, machine tools, instrumentations, and measuring tools has to be strengthened. Use them correctly and maintain them in periods. Appropriate development and advancement of tools should be carried out.



3.2.1.3.3



Management of material and spare parts has to be done



3.2.1.3.4



Management of labor cost, material cost and expenditure statistical management system should be established and integrated.



3.2.1.3.5



Equipment condition monitoring system has to be established.



3.2.1.3.6



Closely perform each technological monitoring system. Methods have to be correct while data has to be accurate, and the conclusion has to be clear.



3.2.1.3.7



The turbine maintenance team has to be built up. Professional quality of staff has to be improved. Personnel in this team have to be highly responsible, capable of scientific management, and with practical experience. They have to be skillful and good in manner.



3.2.1.3.8



The maintenance economic contract and responsibility system has to be revised and updated continuously.



3.2.1.3.9



Overall quality management, norm management, management objectives and life management should be carried out on large scale. With methods like operational research and network planning, the turbine maintenance management level should be advanced and updated.



3.2.1.3.10



Maintenance system has to be strictly carried out. Quality management should be strengthened. Acceptance work should follow “Three Stage inspection & acceptance” procedure...



3.2.1.3.11



For turbine maintenance projects that are undertaken from both home and abroad, the turbine maintenance department or plant department is required to access the qualification of the contract company. In addition, a contract including maintenance items, work period, quality, material and expenditure should be signed with contract company according to the economic contract.



3.2.1.3.12



The turbine maintenance personnel should be familiar with: a) system and equipment construction and performance; b) equipment maintenance technology, technical process and quality standard; c) safety work rules. In addition, they should be capable of: a) bench work technology; b) another two skills related to personnel Page 9 of 241



designated specialization; c) reading drawings and drafting drawings of simple components. 3.2.1.4



Equipment maintenance period



3.2.1.4.1



Equipment maintenance period mainly depends on equipment technical condition. Main equipment includes turbine property, speed governing, feed pump and other attached equipment. Auxiliary equipment refers to producing equipment apart from main equipment. In general, the maintenance period for main equipment should be carried out according to stipulation in the following Table 1.



3.2.1.4.2



Cycle of Maintenance



Table 1



Maintenance Period Equipment Name



Steam



3.2.1.4.2.1



Table 2



Overhaul Period



turbine generation 4 years units



Repair Period



4-8 months



When the maintenance period in Table 1 is carried out, equipments should be treated differently depending on conditions. 1)



For equipment with good technical performance, maintenance period can be extended by adoption of measures positively so as to make full use of equipment potentiality and decrease maintenance expenditure. However, the stipulation in Table 1 can only be exceeded after approval from the provincial apartment.



2)



For equipment whose technological state is not good, maintenance period can only be shortened (compared with stipulated period in Table 1) after assessment by technical department and with approval from provincial apartment in order to prevent equipment from being unrepaired, and ensure equipment health.



Reference Conditions for Extended or Shortened Overhaul Periods



The maintenance stipulation in Table 1 can be The maintenance stipulation in Table 1 can be extended only if technical conditions meet all shortened if any of the following condition following conditions happens Can frequently achieve nameplate output and higher efficiency. Main operation parameter is within stipulated scope. Vibration of the units does not exceed standard and the oil quality is in good state.



Main operation parameter frequently exceeds limited value, which possibly causes equipment damage. Serious scaling in steam flowing part has to be removed in an overhaul. Thermal efficiency of the units decreases



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obviously and the vibration of the units exceeds standard. Main bearing and thrust bearing work normally. Serious crack or flaking-off on the bearing No defects like tungsten alloy on surface of bushing and it cannot be repaired. bearing bushing flaking off. Serious air leakage on gland seal. Oil quality in Interface of cylinder is tight. Sliding of sliding pin the turbine become worse and cannot be system is normal without being jammed. solved by repair. There are defects like serious water eroding, deformation, wear, corrosion, and crack on turbine impellers, thrust disc, gland seal bushing, blades, lacing wire, and restoring ring. Frequency of blades meets basic requirements or cannot meet basic requirements but has no influence to safety.



Bedplates become loose and the sliding pin system work abnormally, which influences normal expansion or threatens safety operation of the units.



No crack on cylinders, spraying nozzles and blade carrier. There is no serious defect like eroding or some slight defects, which have been proved to be no influence to safety operation.



If the cylinder interior has been improved to a large extent, or important components have been replace, or eventful defects has been removed, it needs to check and access during overhaul.



The speed governing and protection system as Serious crack on cylinder; steam leakage on well as executor work reliably and the dynamic interface; serious deformation or crack on performance meets the requirements. blade carrier.



No obvious wear on main speed governing device of the turbine.



Serious defects like slag jammed in the big shaft, cracks in impeller key groove, frequency of the impeller cannot meet requirements, occur on the turbine rotor and they need to be monitored and accessed.



Attached equipment has no serious defects that Cooper pipe in the condenser has serious influence safety operation of turbine. Ordinary leakage due to eroding, which needs to be defects can be repaired. repaired in an overhaul. Validity period of key components (like all kinds of high temperature and high pressure fastening pieces) meets requirements to extend maintenance period or can be replaced in regulate repair.



Turbine units cannot meet the output stated on nameplate (or permitted), but this can be restored after an overhaul.



Main I&C measurements and protection devices can be put into normal service, or the slight defects can be repaired.



Main I&C equipment, automatic monitoring device and protection devices cannot ensure normal operation of the units, and these defects cannot be repaired.



Speed governing and protection system cannot work reliably, and this cannot be repaired.



3.2.1.4.2.2 In emergency repair, if other defects on the equipment and system have been removed and proved the continuous safety operation for longer time, an application



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should be reported to main management department for approval, and the planned overhaul and repair dates following this period should be postponed. 3.2.1.4.2.3 For part of the unit, if department manager agrees, two scheduled minor repairs can be conducted once or one scheduled minor repairs can be done by two times. However, accumulated time for repair cannot exceed the total permitted outage days specified for annual minor repair plan. 3.2.1.4.2.4 For auxiliaries in conjunction with main equipment overhaul, the overhaul interval is just same as the main equipment. However, based on operation technical condition, it can be conducted an overhaul during minor repair period of main equipment. 3.2.1.5



Overhaul & minor repair management and maintenance summary



3.2.1.5.1



Preparations before an overhaul or minor repair: Based on turbine system and equipment operation conditions, the existing defects and inspection results from regulate repair, and summary from last overhaul, it is required to do site check. According to check results and annual maintenance plan requirements, the maintenance plan to key items should be decided and measures that are in accordance with practical condition should be drawn up. Also, the related design, test and technical assessment work has to be done. 2) Determine material preparation (including material, spare parts, safety tools and construction tools), and arrange the maintenance construction site. 3) Network graph about implementation of overhaul and regulate repair should be drawn up. 4)



Drawn up Maintenance technical organization measures and safety measures ..



5)



Prepare recorded technical data.



6)



Determine the manufacture drawing for spare parts or components to be plotted or verified.



7) Organize all maintenance personnel to study and discuss the maintenance plan, items, work periods, measures and construction quality requirements. Special work and labor distribution should be done and the maintenance work and assessment personnel should be decided and designated. 8) One month before overhaul, or half month before regulate respire, maintenance personnel are required to organize related staff to check each work. For the preparation, it has to be checked again before the maintenance work is started. The overhaul and regulate repair have to be carried out in planned schedule. 3.2.1.5.2



Conditions before overhaul 1)



The execution of significant and special items and the technical measures have already been approved.



Page 12 of 241



3.2.1.5.3



2)



The maintenance items, work periods, technical measures, safety measures and quality standards have already been studied and commanded by all maintenance personnel.



3)



Working personnel, main material and spare parts as well as production technical items have been prepared.



4)



Work tools and machines, special tools, safety tool and test equipment have been checked and tested. The results meet the requirements.



5)



For the maintenance assignments that are overtaken by central maintenance company, preparation should be done by both the plant and central maintenance company respectively. Both sides should cooperate closely.



Organization work during overhaul and regulate repair periods covers: Organizing all maintenance personnel to study the Safety Code and checking each safety measures to ensure equipment and personnel safety.



3.2.1.5.4



1)



Strictly executing each system and standard technical measure to ensure maintenance quality and check and put the position responsibility into practice.



2)



Familiarizing the work procedure and reinforcing organization and coordination to maintain the work is completed within regulated period.



3)



Being diligent and frugal, taking good care of instruments and machines, and saving raw material.



4)



Pursuing civilization maintenance and culturing practical and meticulous working style.



Items and Contents of Maintenance During maintenance process, the disassembly, repair and reassembly processes should be 1)



Technical documents and testing materials should be collected and prepared before the equipment is disassembled. After being disassembled, the equipment should be carried out a thorough check to find if there are any defects. The technical condition of the equipment should be familiarized. For assessment, it is usually the regular items and technology updated items and the relevant effects that are inspected.



2)



For projects that possibly influence the work period and projects that need further implementation of technical measure, the equipment disassembly inspection should be carried out in early stage.



3)



When disassembling key equipment or the ones with serious problems, the maintenance responsible personnel, related technical staff are required to have fist-hand material and notice the key problems and then guide the maintenance work. Page 13 of 241



3.2.1.5.5



4)



After the equipment is disassembled, if new defects are found, add them into the maintenance items timely. Put the maintenance methods into practice, and modify the network graph. Prepare necessary tools, machines and labors.



5)



For key steps during reassembly process, the quality should be controlled strictly and the assessment should be emphasized.



6)



If maintenance work cannot be finished within scheduled date, necessary postpone procedures should be carried out.



7)



During maintenance process, make detailed records in time. Following listed contents should be included: which are respectively equipment technical condition, repair content, modification of the equipment structure, measured values and test results. All records have to be complete, correct, concise, and practical.



8)



Use the opportunity to measure actual size and check and made graphs of spare parts.



9)



Manage the tools and instruments to prevent tools, fittings or other things being left inside the equipment and pipeline. Emphasize fire prevention work and protection work. After the overhaul and regulate repair are finished, clear the site.



Several basic objectives have to be achieved after maintenance work: 1)



High quality After maintenance, defects on the equipment are repaired. The equipment can meet each quality standard and can be started up successfully within regulated overhaul period. During one overhaul period, it can operate safely, economically, and it can reach full capacity. Reliability and economical performance are enhanced compared with those of before. The utilization of the monitoring device, safety protection device, and main automatic device is improved compared with that of before. Performance of the equipment is reliable and all signal indications are correct.



2)



Short working period All regulated standard items and special items are achieved and shutdown period for maintenance cannot exceed regulation.



3)



Low maintenance cost Cost for material and labor cannot exceed limit value that is approved by main management apartment.



4)



High safety During maintenance process, seriously carry out the Safety Code. Execute the maintenance work seriously and emphasize the safety. Prevent personnel injury and equipment damage. Page 14 of 241



5)



Good maintenance management The maintenance related regulations and rules are closely carried out and the maintenance management is continuously updated. All kinds of maintenance technical documents are complete, correct, and clear. The maintenance work is tidy and clear.



3.2.1.6



Quality assessment 1) To ensure maintenance quality, necessary quality acceptance must be done. For this purpose, self-check by maintenance personnel and inspection by inspectors are both required. For those with simple process, it mainly is checked by maintenance personnel. Inspectors are required to follow the policy that Quality First and in conformity with Inspection Process and Quality Criteria during maintenance. 2) A three-step assessment system (group assessment, maintenance department assessment, and plant department assessment) should be carried out for quality assessment. All assessing personnel should work seriously and responsibly, and this work has to be taken by personnel who are familiar with technology for a relatively long period. 3) For team& group acceptance, it is usually required to be inspect firstly by inspector and then reviewed by team leader. A team leader is required to be familiar with the maintenance quality in his group and make necessary technical records. 4) For key procedures and items or phase-by-phase acceptance & technical inspection item, maintenance department is required to make an overall inspection& acceptance and provide phase records. The records include maintenance items, technical information, quality assessment, and signatures of maintenance and responsible person. Finally, it needs to submit to plant department for further approval. What is needed to point out is that specialized persons are required to join in maintenance inspection& acceptance. 5) After main equipment is repaired after an overhaul, the assessment should be directed by the general engineer. 6) After complete commissioning of the whole unit and thorough inspection onsite, if everything is normal, chief engineer can declare completion of maintenance task.



3.2.1.7



Maintenance sum-up 1) After minor repair or overhaul for main equipment, responsible person should organize related persons to summarize experience carefully. Summary contents may involve overhaul & repair quality, process, safety, costs control and management, as well as pre-operation. Based on responsibility& performance system, give prize to excellent ones and provide necessary proposals for improving the overhaul and repair performance. Page 15 of 241



2) Sort out the documents like technical records after overhaul and repair, test reports, technical system modification documents in time. Keep them in maintenance department and production department as technical records. 3.2.2



Main Specification and Structure of Turbine



3.2.2.1



Equipment main technical specification: Model: N315-16.7/538/538-8 (combined casing) Type: condensing turbine of subcritical, intermediate reheating double-exhausting.



double-casing,



and



Rated power: 315MW (ECR working condition) Maximum power: 325.8MW (VWO working condition) Rated steam parameter New steam



(prior to HP main steam valve)



Reheat steam



(prior to IP combined valve)



Bach pressure



8.0KPa



16.7MPa/538℃



3.181MPa/538℃



Rated new steam flow: 899.6t/h Maximum new steam flow: 1025t Steam distribution mode: total-electrical regulating (valve management) Rotating direction: generator is clockwise viewed from turbine direction. Rotating speed: Combined critical speed First stage(generator rotor fist order)



1345／1394r/min



Second stage(LP rotor first order)



1691／1769r/min



Third stage(HP/IP rotor first order)



1694／1698r/min



Forth stage(Generator rotor second order)



3625／3640r/min



Fifth stage(LP rotor secondary order)



1691／1769r/min



Flowing stage: altogether 27 stages, including HP casing of 1 adjusting stage+8 pressure stages, IP casing of 6 pressure stages, and LP casing of 2×6 pressure stages Feed water regenerative system: 3 HP heater + 1 deaerator + 4 LP heater Feedwater pump driving method: driven by small turbine of 2×50％B-MCR; the motor driven speed governing feedwater pump of 1×30％B-MCR serves as standby. Steam seal system: self sealing system (SSR) Height of last stage rotor blades: 851mm Page 16 of 241



Ring shaped exhausting area of last stage rotor blades: 2×6.69m2 Main equipment weight~630 t (including HP, IP valves and the hangers, HP, IP main steam pipe and main steam pipe hangers and base bracket) Maximum lifting weight~125t (during installation, with LP outer casing lower part composition) Maximum lifting height≈9.68m (during lifting LP outer casing) Operation platform height: 12.6m Connection of turbine and condenser: elasticity Turbine arrangement: it is arranged from left hand side (from electrical side (A column) to boiler side (B column), the head of turbine should be at left hand side). Table of all the parameters and flow volume on each regenerative steam extraction point under rated operating condition(THA).



Extraction section



1



2



3



4



5



6



7



8



Extractor



JG1



JG2



JG3



CY



JD4



JD3



JD2



JD1



Steam extracting point ( stage)



6



9



12



15



16/22



17/23



18/24



19/25



Steam extraction pressure (MPa)



5.95



3.62



1.697



0.816



0.48



0.267



0.14



0.066



Extraction steam pressure loss



5%



Steam extraction temperature (℃)



388.2



322.9



439.9



337.6



275.3



210.5



146.4



88.4



Flow (t/h)



68.28 6



73.41 4



35.891



57.90 7



25.53 2



24.26



24.50 6



42.27 6



3.2.2.2



6%



5%



General description of main equipment structure



Page 17 of 241



Equipment structure



Property structure of the turbine



Shafting and supporting system



Type and structure of the bearing



Bearing box and bed plate



Bearing and shafting safety monitoring



Valves and pipelines



Sliding pin system and expansion difference difference



In this turbine, HP-IP casings are of a whole construction, and HP casing is of double layers while LP casing is of balanced flow distribution type with double layers. HP-IP and LP are all adopt counterflow scheme. Steam admission ports of HP and IP are all arranged at middle of HP and IP casings, where the temperature is the highest. Valves of HP and IP are of floor type, which are installed symmetrically at left and right sides. Total length of the unit is 18m. In this unit, HP-IP and LP rotors are of complete forged components, inwhich HP- IP rotors covers HP section (9-stage impellers with adjsuting stage) and IP section (6stage impeller), LP rotors (altogether 12-stage impeller of both direct and counter directions). The connection between LP rotor and HP/IP rotors, and connection between LP rotor and generator rotor are of rigid coupling connection. There are altogether 6 support bearings along the shafting in the unit, in which 4 are for turbine and 2 for generators. In addition, 1 independent thrust bearing is installed inside the IP and LP bearing box, 1 bearing is installed at back end of the generator for stablization. The maximum lifting weight during maintenance is 62.5T, and the maximum lifting height of the LP rotor including lifting equipmetn is 9.68m (while lifting LP outter casing, from lifting hook, untill contact the lifting equipment, to operation platform HP flowing portion is designed as counter flow. Steam admission ports of HP and IP are located at middle part of the HP and IP casings, and the temperature of this part is the highest part of this unit. The new steam that comes from boiler superheater flows into the HP main steam governing valve through main steam pipeline, and goes into the spraying nozzle chamber of HP inner casing through four HP main steam pipes ofΦ273×40 and four HP steam admission pipes that are located in middle part of the HP and IP outter casing respectively from top and bottom, then it flows into the HP flowing section. After passing through 1 single governing stage and 8 pressure stages and having done work, the steam is exhausted from 2 HP steam exhausting ports at lower part of the HP and IP casings. Then, it enters the boiler reheater through 2 cooling section reheat steam pipes, on which one Dg 600 steam exhausting check valve in located Page 18 of 241



respectively. After the 6th stage, one section regenerative extraction is for 1# HP heater (JG1). After the 9th stage (HP steam exhaustion), 2 sections of steam extraction are located for 2# HP heater (JG2). Through 2 hot reheat steam pipes, the reheat steam goes into the IP intercept valve, and then flows from two sides of lower part of HP and IP casings to the IP flowing part through 2 IP main steam pipes ofΦ610×55. There are altogether 6 pressure stages in IP section. After the 3rd stage, there is a 3-stage extraction port located there for 3# HP heater (JG3). Part of the exhausted steam does extraction at 4-section extraction port at lower part of the HP and IP outter casing for deaerator(CY) and feedwater pump small turbine. Most steam flows into the connection pipe and goes into the LP casing through one IP exhaustion port of Φ1400mm that is located at center of casing upper part. The LP casing is of balanced flow distribution structure. The steam flows to the flowing part through middle part of the LP casing, respectively with forward and backward directions, and is exhausted downards into the condenser through 2×6 pressure stages. After stege 1-4, there are 5-8 section exhaustion ports located, respectively for 4 LP heaters (JD5-JD8). 3.2.2.3



Structure of HP and IP outer casing Inside HP-LP casing, it is the casing stationary components, which include HP inner casing, spraying nozzle chamber, blade carrying, and steam seal. Together with turbine rotor, they constitute the turbine HP- IP flowing assembly. The material is of casting of ZG15Cr1Mo1. There are four flanges for HP admission pipes located in middle part of the outer casings. In HP section, there are convex plate and rim equipped for installation of HP inner casing and # blade carrying. At front lower part there are two HP exhaustion ports. Backwards of the 6 th stage, there is on extraction port for #1 HP heater. Two IP admission ports are located at left and right sides of the middle and lower part of the outer casing. In IP section, there are convex plate and rim for installation of #1 and #2 blade carryings. One exhaustion port for #3 HP heater is located at lower part of 3 rd stage. At lower part of the outer casing there is one IP exhaustion port of Φ1400mm. Two exhaustion ports are located at left and right sides of the lower part for deaerator and feedwater small turbine. The maximum thickness of casing wall especially at places of IP and HP exhaustions is about 108mm. The weight outer casing is -68t (the attached assembly’s like bolts are not included). Permitted working temperature is no more than 566℃. The flange connection bolts uses GH thread type bolts and no need washers. The specifications of the bolts in use are as shown in following table: Size



Material



Quantity



Page 19 of 241



Working Condition



Remark



6″×1318



20Cr1Mo1VNbTiB



36



4″×1216



25Cr2MoVA



10



3 1/2″×1190



25Cr2MoVA



2



3″×1166



25Cr2MoVA



14



Temperature ≦570° Temperature ≦510° Temperature



Special Stud



≦510



bolt



Temperature ≦510



Note: bolts and corresponding nuts should be marked with numbers. During assembly, rubbing should be conducted between nuts and surface area around horizontal flange bolt holes to ensure good sealing on the contact surface. Meanwhile, good tension condition should be ensured. During installation, the bolts need to be tightened by heating them. It is required to use turbine bolt electric heater instead of oxygen and acetylene flame heating. For the hot tightening value, hot tightening sequence and precautions, refer to the Bolt Tightening Instruction during heating condition that is provided by turbine manufacture. (Note: make sure the cold tightening torque of the bolt meet requirements before the hot tightening process.) 3.2.2.4



Outer casing bracket



Page 20 of 241



TOT AL CLE ARA NCE



TOT AL CLE ARA NCE



A DJ U ST IN G G A S K



HORIZONTAL HORIZONTAL KEY KEY FRONT BEARING BOX



Page 21 of 241



BEARING



> 7



1100 1100



LI N E 11 00



7 7



T O C A SI N G C E N



IP/LP BOX



1100 1100



> 8



8 8



A DJ U ST IN G G A S K



T O C A SI N G C E N



LI N E 11 00



Installation drawing of front and back structure of cat claws The outer casing is placed on the horizontal centering surface of the front bearing box and LP baring box by the four cat claws that are extended out on the lower casing centering surface. This is called lower cat claw center surface supporting structure. This structure is of the following advantages: The clearance between rotating and stationary components is not affected by the temperature changes; The force bearing state of the casing centering surface connection bolts and steam casing seal are good. The thrust (pulling)



force between the HP- IP casing and bearing box is transmitted



by the sliding mechanism of “H” type that is located between casing lower and front end and front bearing box. In order to make the casing and front bearing box remain in same center line. The “H” beam and the casing lower end as well as that with the front bearing box are positioned by column pins. Casing sliding equipment installation drawing During installation, cold state level of the motor end of the “H” beam (connected with casing lower part)



should be placed 1mm higher than the turbine head end



(connected with front bearing box). In this way the 1mm pre-deformation helps to reduce the hot deformation during work state. The heat stress with work state is reduced. The advantage of the sliding mechanism lies in the performance “H” beam. a)



In the plane that is parallel to casing jointing surface, the rigidity is quite high. With the help of the guidance key between the front bearing box and front bed frame, the IP and IP casing can still keep good alignment even in influence of unbalanced pushing force from external pipeline and left-right side uneven expansion of itself.



b)



The rigidity of the vertical section surface is relatively low. In this way, the excessive expansion difference that exists between the front bearing box and HP and IP casings along the vertical direction will not apply excessive hot stress to the “H” beam.



c)



Compared with upper cat claw supporting method, the maintenance adjustment is convenient. Do not need to support the lower casing previously.



The thrust (pulling) force between the HP/IP casing and IP/LP bearing box is transmitted by the horizontal keys beneath the cat claws. In order to keep casing and IP/LP bearing box in same centerline, there are vertical keys located at backwards of



Page 22 of 241



casing lower part.



Installation drawing for backwards of HP/IP outer casing and vertical keys of IP/LP bearing box 3.2.2.5



HP admission pipeline There is altogether 4 HP steam admission pipes located (up, down, left, and right) at middle part of the HP/IP outer casing, and the pipes are fixed on the inner casing by bolts. Two ends of the HP admission pipes are connected with outer casing



and



outer casing respectively by sealing rings. The expansion difference between eh inner and outer casings and nozzles can be absorbed. During installation, note the sided



Page 23 of 241



with chamfer angle of the sealing ring should face outer casing side to facilitate the casing installation. There are altogether 4 HP admission pipes equipped on upper part of the HP/IP outer casing, and they are fixed on the outer casing by elastic flange respectively. Place the admission inner bushing into the nozzle chamber of the inner casing. Use piston ring to seal it. The inner bushing can slide within the nozzle chamber to compensate the expansion difference of outer and inner casings. Slight axial and radial movement is permitted. There is shading tube located between the elastic flange and inner bushing. For piston ring, it is required to use the special mouth gag that is provided by the manufacturer. Connection drawing



HP ADMISSION PIPE



HP ADMISSION PIPE OUTER CASING



INNER CASING



NOZZLE



The extraction pipe after HP 6th stage One extraction port is located after lower part of 6th stage. Through one extraction pipe of Φ168×8, the port is connected to the ring shape steam collection chamber after the HP inner casing 6th stage. Two ends of the extraction pipe are connected with inner casing and outer casing respectively by sealing rings. The expansion difference between the inner and outer casing can be absorbed in this way. The extraction pipe is connected with external pipeline by flange that is fixed on the outer casing by bolts.



Page 24 of 241



Connection drawing of extraction pipe 3.2.2.6



HP inner casing: the HP inner casing is of whole casing. There are 4 groups of spraying nozzle chambers installed at steam admission end. The 2-9 stages of HP diaphragms are located in the casing. The selected material is of ZG15Cr1Mo1. The permitted working temperature is no more than 566℃. One positioning ring is located at the 2nd diaphragm that is in relation to outer wall of the inner casing. The groove on its outer edge matches with the rim on relevant position of the outer casing. In this way, the axial position of the inner casing is decided and the axial expansion dead point of the inner casing in relation to the outer casing is composed. Installation position structure drawing of inner casing cat claw One heat insulation ring is equipped at 5th stage of the outer wall, separating the inner and outer casing space into 2 zones. In this way, the temperature difference between the inner and outer wall of the inner casing can be decreased and the outer casing temperature is increased. The expansion difference between the outer casing and rotor is decreased. One steam extraction pipe is located between inner and outer casing after the 6th stage. The inner casing is placed on the relevant convex plate that is located on the centering surface of outer casing lower part by the 4 cat claws that are located at front, backward, left and right sides of the inner casing lower part. The gaskets beneath these places have to be selected and placed appropriately. The center height of the inner casing can be adjusted with appropriately prepared gaskets on it. Certain heat expansion clearance has to be left out between the cat claw and upper part of the outer casing. One longitudinal key is located at two ends as well as top and bottom of the inner casing to maintain the inner casing center as the moisture of the casing varies There are altogether 24 screw bolts located on left and right horizontal flange of the inner casing. The material of bolts is of 20Cr1Mo1VNbTiB while the permitted working temperature is no more than 570℃. The specially-made nuts beneath the bolts have mechanism of prevent moving and falling apart. During disassembly, firstly pick out the falling prevention pin and stop block, and then turn the nuts with certain angle. The nuts can be removed.



Page 25 of 241



LOWER CASING



HANGING BOLTS



STOP BLOCK



(INSTALLATION HEIGHT DECIDED)



STOP PIN



TIGHTEN



SPECIALLY MADE NUTS



Installation drawing for lower nut stop and falling prevention mechanism There are HP and IP steam seals installed at steam admission end of the inner casing, which are located in two sections. All steam seals are of high-low tooth tip oval seal.



LP STEAM SEAL



STEAM SEAL BETWEEN HP AND IP STEAM ADMIS SION SIDE



STEAM ADMIS SION SIDE ROTOR



ROTOR



Page 26 of 241



3.2.2.7



Spraying nozzle chamber and nozzle group The four nozzle chambers in HP section are structured as upper and lower parts. They locate along the HP steam admission center line together with the inner casing axial positioning point. There are guide keys along the upper and lower axial direction to ensure the free expansion and maintain the steam admission pipe center.



GUIDE KEY



Structure drawing of nozzle chamber 3.2.2.8



HP and IP rotor: HP and IP rotors are all of forged structure. Material of them is of 30Cr1Mo1V. Total length of rotors is 7364 (main oil pump shaft and emergency tripper are not included). The total weight is -22.435t (including the blades). There are altogether 9 stages including adjusting stage in HP section. The impeller of the adjusting stage is a section with equal thickness. Big circular arc transmission is adopted between the wheel hub and the adjusting stage. The impeller base is of three groove shape. The 2nd-9th stages of the impeller are of equal thickness with inverse T shape blade base. The 1st stage of the impeller is of pyramid shaped section. The steam admission side of the 2nd stage is of pyramid shaped section. The 3rd-6th stages are of equal thickness. The 1st to 5th stages are of double inverse T shaped blade base. The 6th stage is of mushroom shaped blade base. On the cut circle (Ф750) of the original surface of the 2nd-9th stage impeller, there are 9 balance holes of Ф30 on it. On the cut circle (Ф860) of the original surface of IP 2nd-6th stages, there are 7 balance Page 27 of 241



holes of Ф40 on it. In this way, the rotor axial pushing force that is caused by the two sides pressure difference of the impeller is reduced. The diaphragm steam seal and axial end steam seal between the impellers are of sharp tooth structure. There is a forked tail slot with balance block located at end faces of rotor two ends (9th stage of HP section, and 15th stage of the IP section) that is on the outer impeller. The convex plate at middle section of the rotor, there is a T shape slot for balance block and in further way for dynamic balance. HP-IP rotor is with no center hole in it. The front journal of the rotor is of Ф360, and the main oil pump shaft is placed on the journal end face through the connection bolts. One emergency tripper is located at front section of the main oil pump shaft. The tail journal of the rotor is of Ф360, thrust disc thickness is 100mm. It is used interference-fit of counter lock to connect HP-LP rotor to LP rotors with a rigid coupling. For connection between LP rotor and the coupling, 12 special bolts are used. For the requirements of these bolts for assembly and pre-tighten force (prolong length), please refer to the relevant regulations on Rotor Drawing. On circle face of the coupling (new hydraulic impeller bolt), there is a T shape slot for installation of balance block located there. There are balance bolt holes located on front and rear steam seals, for axial dynamic balance even when the casing is not opened.



CENTERING LINE OF EMERGENCY TRIPPER



CENTE RING LINE OF MAIN OIL PUMP IMPEL LER



PUMP SHAFT



HP-IP ROTOR



Emergency tripper, main oil pump and HP, IP rotor connection drawing



3.2.2.9



Spraying nozzle group and HP/IP diaphragm



Page 28 of 241



3.2.2.9.1



Structural description: Since spraying nozzle groups and diaphragms are main components that convert the steam thermal energy into kinetic energy, they possess the characteristics of high working temperature, big pressure difference (of diaphragm) and small clearance between the rotors. In LP section, there are altogether 9 stages, and the nozzle chamber is connected with upper and lower nozzle group by bolts and fixed at lower inner casing. The 2nd-9th diaphragms are equipped in the HP inner casing. There are altogether 6 stages in the IP section. The 1st to 3rd stages of diaphragms are located in 1# blade carrier while the 4th-6th stages of diaphragm are located in the 2# blade carrier. The stationary blades of the nozzle group are of integral shroud and with slant arrangement. After the guide blades are welded as vane cascades, they were welded into a whole body together with the strengthening ring as well as the steam chamber. The groups of nozzles share one chamber. Each group of nozzle is in relation to one steam admission port. The chamber is isolated by ribbed slabs. The upper and lower parts are connected together by centering surface bolts. Since the working temperature of diaphragms in HP-IP section is above 350℃, the diaphragms of welded structure are used to adapt to the high temperature working condition. The stationary blades for HP 2 nd -5th stages are of flow-diverting structured. For 6-9th stages in HP section and all stages in IP portion, bended blades with shroud are used. Split flow cascade Illustration of Bending guide vane Steam seal for the diaphragm uses ellipse -shaped steam seal, which can ensure the safety and decrease the steam seal leakage amount. The moving blades are of selfcoronal structure, and the top of the blade coronal is set with radial steam seal, and the moving blade root is set with the root steam seal. ALL of the interfaces of the diaphragm are tightened by bolts, which is helpful for improving the whole rigidity of the diaphragm and the sealing of the interfaces.



3.2.2.9.2



HP diaphragm and cascade material stage



2



3



4



Location Diaphrag m material Guide vane material



3.2.2.9.3



5



6



7



8



9



HP inner casing (ZG15Cr1Mo1) ZG20CrMoV



ZG15Cr2Mo1



1Cr11MoV



1Cr13



IP diaphragm and cascade material stage Item



1# blade carrier(ZG15Cr2Mo1)



Page 29 of 241



1# blade carrier(ZG20CrMo)



Diaphragm



ZG20CrMoV



material Guide vane



ZG15Cr2Mo1



1Cr11MoV



material



1Cr13



Diaphragm outer ring Axial seal



gland



Static blade Moving blade Diaphragm Impeller



Radial gland seal and root gland seal



Page 30 of 241



3.2.2.10



LP casing structure Because of the high temperature of the inlet steam, the LP casing uses the welded double-layer casing structure; the bearing pedestal is arranged at the LP outer casing.



Vertical cross- section view for LP casing The LP inlet steam temperature is about 350℃, while the steam between the inner casing for steam exhaust, the design temperature is only about 35.6℃. The LP inlet steam temperature is about 350℃, and the exhaust temperature is only about 35.6℃. In order to reduce the differential value of inner wall and outer wall at the steam admission part, the heat insulation plate is installed on the outer wall in the middle part of inner casing. It is so designed that the steam admission chamber of the LP inner casing is of assembly construction and ring type. The whole chamber is isolated from the other parts in the inner casing. It can expand freely at the axial and radial direction. The relative thermal expansion dead point of the LP steam inlet chamber versus LP inner casing is the crossing point between the LP steam inlet center line and the center line of turbine. Like HP inner casing, the steam admission chamber for LP inner casing is also designed as assembly structure and isolated from the other parts in the inner casing. In addition, clearance is reserved at radial direction and elastic slots are provided in the horizontally arranged flanges for ring-shaped steam chamber on both left and right Page 31 of 241



sides. Due to this arrangement, heat expansion at the portion where temperature difference between inner and outer casing is the maximum is with minimal restriction under the working condition. Thus, possible partial deformation of the casing due to excessive thermal stress caused by expansion limitation can be avoided. The LP steam inlet is so designed that it is consist of welded steel board. This can lower the weight of steam inlet and avoid possible defects in cast pieces. In order to prevent bolts on the connecting interface from being stuck, the GH thread is applied to the bolts in high temperature area surrounding the steam inlet chamber. The guide rings are installed on both ends of inner casing, which provides diffusion section with the outer casing and reduce the exhaust loss. At 4 corners of horizontal flange for lower half inner casing, there are 4 claw supports on outer casing, which are used to support the weight of all the diaphragms. There is side key at the middle part of the horizontal flange corresponding with the steam inlet center, which is taken as the relevant dead point, and it makes the inner casing be located along the axial direction and permits the free expansion in the axial direction. The longitudinal key is at the two ends of the half lower inner casing, and it is set in the axial direction along the radial center line, and it makes the inner casing be located along the transverse direction relative with outer casing and permits the free expansion along the transverse direction. In order to reduce the differential temperature of bolts and flanges in course of starting, the natural flow heating system is adopted for the big bolts. Illustration for showing natural flow of warm-up for large bolts (LP inner casing) On steam inlet part at the top half of the LP outer casing is LP steam inlet bellows pipe which is connected with the steam inlet of the inner casing to compensate the expansion difference between inner and outer casing and ensure the sealing. At the two ends of the top part, there are four air valves with the inner diameter Ф500 as safety measures for the vacuum system. When the condenser cooling water is interrupted suddenly, the pressure inside the casing increases to 0.118 ～ 0.137MPa on the pressure gauge, the asbestos rubber plate, 1mm in thickness, inside the air valves will burst, the steam will emit out to protect the LP casing, final-stage blades and the condenser. One half round concave in the middle of each end of upper half casing is left for hoisting the bearing housing cap. Some reinforcing plates are fixed on the outside of both ends of upper half casing in horizontal and vertical direction to intensify the end plate rigidity and reduce the vibration frequency. LP bearing boxes are provided at both ends of the lower LP outer casing, there is, and the supporting bedplate around it is put at the foundation arranged in rectangle, and it is used to bear the weight of the LP part. The size of the bottom exhaust outlet is 7.5m×6.4m, the exhaust area is 48 ㎡. The flexible connection between exhaust and condenser is adopted. The longitudinal key is installed at the foundation in the front and back part of the LP outer casing, and the transverse key is set 360mm in front of the LP steam inlet center at the right and left side of the foundation in the middle part, which is taken as the dead point of the whole LP part. The whole LP casing can expand in all directions taken this dead point as the center. 3.2.2.11



Connective tube The connecting tube is the passage for the IP exhaust leading to LP casing, the inner diameter isФ1400, it is above the IP exhaust, LP casing and I&LP bearing box, and it



Page 32 of 241



is the highest point of the whole unit. The bending radius of connective tube is comparatively big to reduce the flow loss inside the connective tube. The connecting pipe is composed of two sections: the bending pipe and balanced compensating pipe, during the on-site installation, they are welded together. The bending pipe is connected with the IP exhaust outlet, and in the balanced compensating pipe there is a downward pipe connected with the LP steam inlet pipe. They are connected by rigid flanges. In order to compensate the axial expansion of the connective tube and the unit, the corrugated pipe is provided before the balance tube. The balance chest with corrugated tube is established at the end of balance tube to balance the axial working force of the steam inside the balance tube. The connective drum is arranged outside the balance tube to connect the both ends, the drum, not the corrugated tube, bears the steam axial working force. 3.2.2.12



LP casing sprayer When the unit is running on low load or no load, especially, under the high back pressure, the exhaust steam temperature increase will make the LP casing overheated, the bearing center height will change which will probably cause such failures as the vibration, etc. In order to keep the safety operation, the sprayers are provided inside the LP casing. When the exhaust steam pressure increases, the condensate will spray into the exhaust opening to decrease the casing temperature.



3.2.2.13



LP rotor The LP rotor is integrally-forged with the material 30Cr2Ni4MoV, of which the length total and weight total is 8330mm and 61t respectively. The LP rotor without center holes has 12 stages impeller, of which the section is taper-shaped, the blade root grooves are on the rim, the stage 1-5 blades are of mushroom-shaped roots. The final stage blade root is 丫 -shaped. The diameters of both the front and rear bearing journals areΦ480, The HIP rotor and generator rotor are aligned through rabbet which adopts force fit. The two ends are connected through the rigid coupling, 12 special bolts are arranged on the HIP rotor coupling, and 14 on the generator rotor coupling. 17 Ф40 balance holes are distributed evenly in the middle rounds of the impellers of stage I-III. One balance groove is provided on the outsides of both final stage impellers and between the both stage I impellers for the dynamic balance test by the manufacturer. One balance groove is arranged respectively on the outer circumference surfaces of both end couplings for the shafting dynamic balance test.



3.2.2.14



LP diaphragm Diaphragms are arranged in both directions in LP part. The stage I-IV static blades are self-banded welding structure, the final stage and its previous stage are directly welding structure, and the stage VI diaphragm and its outer ring are steel plate welding structure. the stage I-III static blades are bending type, the stage IV-VI stage blade are distorting type, the edge of stage blade are 0.38mm. LP diaphragms and the gland seal, radial gland seal adopts copper gland, of which the diaphragm is equipped with the slant flat tooth-shaped gland seal. The moisture baffle ring is arranged on the edge of the stage VI diaphragm, the small water droplets in the steam flow will fall into the baffle ring under the function of centrifugal force, thus, the Page 33 of 241



steam can enter the exhaust opening avoiding to go through the final stage moving blade. The moisture baffle ring is able to alleviate effectively the water erosion on the final stage blade. The splits of all diaphragms are connected through the bolts, so the inner casings don’t need to be turned over in the case of maintenance. Table



LP diaphragm material 16/22



Diaphragm material



17/23



ZG230-450(



18/24



19/25



HT28-48CrMo



20/26



21/27



ZG230-450



16Mng



ZG1Cr13 Guide vane material



3.2.2.15



Moving blade



Moisture-proof diaphragm Diaphragm outer ring



Wet steam A series of new technology and design ideas are incorporatedexhaust into the moving blades, which improve significantly the pneumatic, and vibration compensation and intensity levels. To wet ring In order to improve the efficiency and performance under the variable working conditions, the blade with 3-pin integrated band of high degree of reliability and efficiency is provided in the governor stage which are of high parameters, high enthalpy drop and under the poor operating conditions. The stage 2-9 HP moving blades and stage 1-6 IP moving blades areToshiba balance root type with self-banded structure. 5-teeth gland seal is set on the blade tip. The moving blades in LP part adopt the slant band which forms the high effective smooth meridian flow path. The LP final stage adopts the blade 851 of high reliability and efficiency.



The big reliable rigid blades are applied based on the design idea of modern turbine; the relative stress should be tested in intensity design. The dynamic intensity safety rule is introduced to adjustable and unadjustable blades. The axial width of moving blades is big, the blades and blade roots strong rigidity, Axialhasgland the 3-pin blades in governing stage has the Y-shaped blade root, the final stage LP seal blade 851 has 7 Y-shaped roots, the other stage blades in HP part have reverse Tshaped roots, the stage1-5 bladesStatic in IPblade part are of dual inverted T-shaped root, the stage 6 IP blades and stage 1-5 LP blades are of the external 3-mushroom -shaped roots. The stage 4-5 LP blades are long, the centrifugal force on the band is big, and so the double-rivet structure is adopted to meet the requirement on the intensity. The lacing wire goes through the final stage and its previous stage blades to improve the anti-vibration ability. The stage 5-9 HP blades and the stage 1,3,4 LP blades are designed to be unadjustable blades of vibration frequency Ao～Kn、Bo～Zpn、Ao～Zpn, which can be running safely for a long time under the resonance condition. But the resonance should also be avoided in design to meet the requirements that the frequencies are not within the same range, the practical dynamic stress is very weak, so the blades have high safety against the vibration. The other blades are adjustable blades which meet the requirements of frequency inequality and dynamic intensity.



Page 34 of 241



In order to prevent water corrosion, approximately 170mm of the final stage blade tip on the steam admission side is treated with high frequency hardening to improve blade resistance to water corrosion. Table



HP moving blade material



Class



1



Material



C-422



Table Class



2



3



4



Class Material



3.2.2.16



6



7



8



9



1Cr12WMoV



IP moving blade material 10



11



12



Material



Table



5



13



14



15



1Cr12WMoV



LP moving blade material 16/22



17/23



18/24 AISI403



19/25



20/26



21/27 2Cr11NiMo1V



Shafting and supporting system



3.2.2.16.1 Shafting Rigid couplings are use for between turbine HP-IP rotor, LP rotor and generator rotor. All the bolts are so arranged for such considerations: a) for convenient to install and tighten. b) To deal with the problem that the coupling wheels are not enough tightened as required during the unit installation or re-assembly after overhaul. In order to avoid thread failure, the bolt and the matched nut adopts GH (taper) thread. The generator adopts self-excitation type, and the exciter is not used. The whole shafting is supported on the 6 bearings. The rigid connection is used between the main oil pump and H&IP rotor, between the front end of main oil pump rotor and the main shaft of fly ring emergency tripper, and the main oil pump adopts solid shaft, the front end of the main oil pump rotor adopts floating bearing. The coupling between the IP and LP rotor, LP rotor and generator rotor adopts the rabbet alignment, and the convex-concave part of the rabbet is designed to be the interference match to make sure the alignment among the rotors is good and improve the shafting stability. During rotor installation and disassembly, the process bolt and jacking-out bolt are used to tighten and disassemble; the process and jacking-out bolt are supplied with the supply of the machine. There is enough movement clearance set between the generator rotor and stator, so during the disassembly of the coupling of LP and generator, the rotor of the generator moves backwards to make the rabbet remove, and during the tightening, the rotor of the generator moves frontward to return to the original position and make the rabbet table. There are two types for disassemble and tightening of the coupling between the I &L P rotor: a) make the rabbet between I&LP rotor remove away or table by pulling and pushing H&I P rotor, because the clearance between the H&I P flow path is smaller, the H&I P casing must be pulled or pushed when the H&I P rotor is pulled or pushed. So the casing moving tools are designed on the IP&LP bearing box.



Page 35 of 241



The shafting is the clearance system between the moving parts and fixed parts. 3.2.2.16.2



Supporting system: when the unit is in service, the rotor runs on supporting system consisting of the bearing, bearing housing, frame and frame and base. the stability and reliability of the shafting depends not only on the natural characteristics of each rotor and bearing design and manufacturing, but on a series of factor such as installation quality, basic features, operating conditions and load changing, etc..



Emergenc y overspeed governor



1#



2#



LP 3# rotor



4#



危急遮断器



H&IP rotor



高中压转子



低压转子



5#



Generat or rotor



6#



发电机转子



主油泵转子



推力轴承



联轴器



联轴器



(中低压间)



(低电间)



Main oil pump rotor Thrust bearing



Couplin g Coupling



Illustration of Shafting The two ends of the rotor are supported at the bearing pedestal; the middle part bends adown because of the gravity and forms certain deflection. During shafting installation, considering the influence of the difference between the cold state and hot state and the connecting type between condenser and LP outer casing, the relevant measures are used to make sure that the whole shafting forms a gliding transition curve during normal operation. Thus the center of the coupling will be on the same line, the end face is parallel, which can avoid the extra deflection deformation cause by the coupling and journal, and avoid the alternating stress and vibration cause during the operation. During the unit installation, the LP bearing keeps on an even level, the front end of the H&IP rotor and the back end of the generator rotor tilt up, after considering the elevation and corner of each journal and the coupling opening, the influence of the difference between the cold state and hot state and the connecting type between condenser and LP outer casing, carry out the correction(e.g.: leave the height difference before the connection of the coupling) to the rotor static deflection curve, then the shafting installation curve is given. General experience value for pre-leaving height difference: ＃2 bearing pre-leaving height difference 0.25-0.30mm; Approximately 0.10-0.15mm should be reserved for #4 bearing. 3.2.2.17



Bearing type and structure



Page 36 of 241



This unit altogether has 6 supporting bearings, 4 four steam turbine and two for generator. For the shafting location and rotor axial force support, there is also a thrust bearing with the single structure, and it is at the back end of the H&IP rotor. The four supporting bearings of the turbine are tilting-pad bearing and elliptic bearing. The 1# and 2# bearing are tilting-pad bearing, the3# and 4# are elliptic bearing with oil inlet from the single side, and the oil discharging outlet is at another side, the upper pad has cycle slot. #1 supporting bearing (inclinable bearing padΦ360X270) #2 supporting bearing (inclinable bearing pad Φ360X270 ) #3 and #4 elliptical supporting bearing



Page 37 of 241



The thrust bearings in this unit are of independent tilt bearing pad type. In order to reduce the span between two ends of HP and IP rotors, the independent thrust bearings are adopted, which are with spherical surface ensuring the even unloading. There are 11 service thrust pads and 11 retaining thrust pads which are located respectively before and after the thrust disc to bear the thrust force and forms the relative dead point of the shafting. When the unit is in normal operation, the axial thrust force is backward (the generator end). Under the rated working conditions, it is 121.8kN, under the maximum working conditions; it can reach 131.53kN which is bore on the service thrust pads behind the thrust disc (motor side). Under the special condition (the unit trip and reduce the load), the transient reaction thrust force will probably occur which is bore on the retaining thrust pads before the thrust disc (the generator head side). Major parameters of supporting bearing: jacking oil 4 inlet 3 Oil exhaust Elliptical bearing with orifice plate Inclinable bearing oil inlet from one side



Number



1



Type Oil inlet orifice plate



2



Diameter



D



Mm



Length



L



Mm



230



270



336



Ratio of length and diameter



L/D



/



0.64



0.75



0.7



Inlet oil pressure (g)



Po



MPa



0.079～0.098



Inlet oil temperature



to



℃



40～45



Temperature rise



△t



℃



13.35



16.43



14.39



14.58



N



r/min



>4000



>4000



>4000



>4000



Pj



MPa



Limit speed Jacking oil pressure



Φ360



Φ480



7.4～11.76



Note: The temperature rise and stalling speed is calculated under the conditions that the inlet oil pressure is 0.079MPa, the inlet oil temperature =40℃. Table



Major parameters of thrust bearing



Page 38 of 241



Thrust pad number (retaining pads / service pads) Thrust pad diameter (retaining pads / service pads) Total area of service thrust pad Total area of retaining thrust pad Total clearance of thrust pads (g) Inlet oil pressure (g) Inlet oil temperature



Outer diameter Inner diameter



Ft



11 Φ590



mm



cm2



Φ375



1294.7



Fd



/



mm



0.4～0.45



Po



MPa



0.079～0.098



to



℃



40～45



Thrust bearing



3.2.2.18



Piece



Bearing box and frame (steel bedplate)



Page 39 of 241



The #1 bearing, the main oil pump and the hydraulic protection parts are located in the front bearing housing, 2# bearing and thrust bearing are installed in the I&LP bearing box, 3# and 4# bearing are installed in the bearing box at the front and back end of the LP casing. In order to avoid that the turning gear box is separated from the bedplate because of the LP outer casing deformation by the function of the vacuum, which will influence the 4# pad vibration, so the turning gear box is designed to be the single structure type from the LP casing. In the turning gear box, there is coupling and rotor gear ring, and the turning gear device is installed on the box cover. The coupling cover between the I&L P rotor, LP and generator rotor and its oil spraying cooling device are installed in the bearing box at the front end of the LP casing and turning gear box respectively, which covers the coupling between the I&L P rotor, LP and generator rotor respectively. Spraying oil to the outer side for cooling can efficiently avoid the temperature increase of the bearing box caused by the heat generation of the outside bolt and gearing air blast.



Coupling shield



Oil spray pipe



The schematic drawing of the coupling bolts, heat insulation cover and oil sprayer cooling All bearings box is of welded steel board structure, and adaptive modifications have been made to accommodate the whole oil piping. For the sliding block of the front box, self-lubricating sliding block is used to lower sliding friction. All the longitudinal and transverse keys are replaced by round head structure. The thrust device between the H&IP casing and front box is changed to be the “H” typed beam structure. (For more details, see the outer casing support), The front bearing housing , the ILP bearing, and the rear bearing housing and the turning gear case is located on the frame, the All the frames are steel bedplate structure. The frame is supported on the cement pad and foundation bolts and fixed on the foundation, level it for the second time grouting. The connecting area of the bedplate and the foundation is 2-3 times casting frame, so Page 40 of 241



the supporting of the whole unit is more reliable, the strong rigidity of the support can avoid the hollow connection. Due to no adjusting iron pad and no load on the LP casing in the course of installation, the requirements on cement quality is relatively high, the high intensity expansion cement is available. The work for installation and adjusting must be extremely careful to meet the requirements on cement pads and bedplate. As the pedestal frame supports the weight of whole unit, its support rigidity have significant pact on the shafting vibration. Once the installation defect appears, it is difficult to revamp it. Thus, the installation quality must be guaranteed.



Page 41 of 241



Shafting Static static deflect deflect curve degree



Page 42 of 241



3.2.2.19



Bearing and Shafting Safety Monitoring



3.2.2.19.1 Bearing safety monitoring In order to ensure the safety and reliability during the bearing operation, the platinum RTD with Babbit metal temperature is installed in the supporting and thrust bearing. During operation, it will alarm when the Babbit metal temperature of thrust bearing rises to 100℃, shut down 110℃, and it will alarm when the Babbit metal temperature supporting bearing rises to 105℃, shut down 115℃. The bearing abrasion will not be certainly in the Babbit metal temperature measuring area, so monitoring the returning oil temperature is also the means to ensure the safe operation of the bearing. The temperature increase of the retuning oil indicates the abnormal working of the bearing. At this time, it requires an immediate solution. Otherwise, excessive high oil temperature may result in deterioration of oil quality. 3.2.2.19.2 Bearing vibration monitoring The bearing vibration is the integrate check index of the each rotor dynamic balance quality of the shafting, installation quality and operating conditions. In order to monitor the shafting vibration, on the cover of 1# ～ 6# (including generator)bearing box, the vibration pickup is installed along the X and Y directions which are vertical each other. During normal operation or idling with the rated rotating speed, the double amplitude value measured at the bearing box cover is required to be less than 0.03mm, when the amplitude is more than 0.05mm, there will be light signal alarm, and the causes of the high amplitude should be eliminated in time, and do the dynamic test again. Strictly monitor each bearing vibration during speed rising of startup and observe if vibration is less than 0.03mm. During speed increasing, if the vibration amplitude is up to more than 0.05mm, one should decrease speed so as to reduce it below 0.03mm. When the factors that leads to vibration is eliminated, it can be speeded up. Do not stay at violent vibration phase for too long. If the vibration suddenly increases to above 0.08mm, latch off the turbine. When it passes through each critical rotating speed of the shafting, the amplitude cannot be more than 0.10mm. During speed increasing, it is forbidden to stay near the critical rotating speed. 3.2.2.19.3 Shaft vibration monitoring One sensor is installed at the right and left side of the end face of 1# ～ 6# bearing (including generator), and it is 45°above the horizontal plane. The sensor is used to measure the vibration of the rotor relative with the bearing, and the locus of the bearing center can be watched through oscilloscope after the phase discrimination pulse is joined. 3.2.2.19.4 Rotor deflection monitoring The mechanical type rotor bending indicator is installed on the cover of the I&LP bearing box and it is used to monitor the deflection of the H&IP rotor during turning gear. During the new unit installation or casing covering after overhaul, it is used to remeasure the jumpiness of each section of the H&IP rotor, make sure the rotor has no bending and then record the reading on the rotor bending indicator, the reading is taken as the primary value of the indicator. During startup after overhaul and before the later startup and rolling, the difference between the indicator reading and primary reading should be less than 0.03mm. If the difference is too big, the reasons should be analyzed and then eliminated, and the rolling is forbidden to be operated before Page 43 of 244



the deviation is normal. When the above operations are finished, lift the bolt of the indicator to make the probe leave from the rotor. Besides the mechanical type rotor bending indicator of the IP box, the high sensitivity electric vortex sensor is also installed on the front box, and it is used to carry out the non-contacting continuous detection to the eccentricity of the rotor. The output signal is supplied to the recording meter and computer. When the eccentricity is 0.03mm more than the primary value, the light signal alarm is sent out. 3.2.2.19.5 Axial displacement monitoring 2 sensors are provided inside the ILP bearing housing to measure the shaft axial displacement. They output the signal for the instruments display in central control room, recorders and the computers. When the axial displacement is over the limit, the alarm signal will be sent out for emergency shut down. The thrust disc against the service pad tightly is “0”position, the axial displacement toward the generator is defined as “+”, that toward the turbine head is “-” When the axial displacement reaches +0.6mm or -1.05mm, the optical signal will be sent out, when it reaches +1.2mm or -1.65mm, shut down the turbine urgently and record it. Adjust the axial displacement indicator before the unit starts. Push the rotor toward the generator. Define the signal as “0”when the thrust disc against the service pads tightly.



Key phase measuring



rotor eccentricity measuring



Eddy sensor



Rotor eccentricity detection (untouchable type) drawing



Page 44 of 244



#1 bearing central line



3.2.2.20



Turning gear The turning gear is the mechanical device for driving the shafting to turn slowly. The turning gear device of this unit is installed at the turning gear box cover, and the required turning gear speed is at 4.29r/min, the driving motor power is 22kW. It uses conventional worm wheel - rack reducer mechanism and swing gear clutch mechanism. Here, the motor is arranged in transverse direction to reduce the total length of the unit. It is furnished with electric-operated hydraulic mechanism, which is driven by the lubricating oil pressure, and can be operated either remotely or locally. It is so designed that turning gear mechanism can be performed either continuously or intermittently. Also, it can separate from the rotor automatically during rolling. Enough drive capacity margin can meet the requirements for all kinds of conditions. Cautions when the turning gear starts or stops a)



Put the jacking oil pump into service before the turning gear starts to alleviate the frication, which is also favorable to turbine start-up and protects the bearings.



b)



Put the turning gear into service timely after the turbine shut down, continue to run the turning gear until the temperature of the HP inner casing metal wall where the governing stage is reduce to 200℃, switch it over to the intermittent turning, after the temperature drops to 150℃, stop the turning gear.



c)



when shutting down a turbine,turning gear can be put into service only when the rotor speed is up to 0. Otherwise, it will be severely damaged.



Failed turning gear and rotor



Page 45 of 244



Insert Position Open



Oil inlet Rotor packing ring



Turning gear (Fig. 1)



Page 46 of 244



Turning gear (Fig. 2) 3.2.2.21



Valve and pipe



3.2.2.21.1 HP main stop valve This unit has one set of HP main steam governing valve which is arranged under the operating layer in front of the turbine. The HP main steam governing valve is composed of 2 main stop valves and 4 governing valves, and the out let of the two main stop valves are connected with the governing valve cover, the arrangement is compact. The main stop valve diameter isΦ280, the #1 and #3 governor valves are on the right side while the #2 and #4 governor valves are on the left side. In order to decrease the lifting force of the valves, the main stop valve and governing valve are set with pre-inlet valve. The 4 governing valves are used to control the relevant 4 groups of nozzles in the HP inner casing, and the governing valve is controlled by its separated oil actuator to realize the unit steam distribution requirement. The oil actuators for the governor valve are reversely located after the governor valve and control the governor valve opening via the lever. The oil actuators for the main stop valve are under the main stop valve and push its valve stem directly. In order to improve wear on seal surface, The satellite alloy is welded around the stem of the main stop valve The conical sealing surface is set at the main stop valve rod, the main stop valve is at fully open position, and the conical surface of the valve rod is tightly kept close to the sealing surface of the sleeve, which can avoid the valve rod steam leakage. The bolt of the main steam valve cover is of GH thread. The thermocouples are installed at the inlet of the main stop valve to monitor the valve case temperature for reducing the thermal stress. The temporary filer (fine eyes) is installed inside the main stop valve for trial operation. After the trial operation, change it to the permanent filer (coarse eyes). Page 47 of 241



HP main stop valve



steam direction



flow



HP governor valve steam direction



Oil actuator for HP governor valve flow



Oil actuator for HP main stop valve



Structural illustration of HP main stop valve and governor valve 3.2.2.21.2 IP composite steam valve This unit has 2 combined IP steam valve at left and right side; they are arranged at two sides of the IP part of the H&IP casing. In combined steam valve, the main stop valve and governing valve use the same valve cover and valve foundation. The matching surface is at the different cross section of the valve foundation. The diameter of the main stop valve is Φ567.8, which is driven by the oil actuator at the rear part of the composite valve. In order to decrease the lifting force of the valve, the pre-start valve is set at the main stop valve and governing valve. The conical sealing surface is set on the IP main stop valve rod. When the main stop valve is in fully opened position, the conical surface is cohesive to the sleeve sealing



Page 48 of 241



surface to avoid the valve rod leakage.



IP main stop valve



IP governor valve



Exhaust center Steam direction



flow



Oil actuator for IP main stop valve Oil actuator for IP governor valve



Structural Diagram of IP Intercept Valve HP and IP steam valves parameters: Materials of HP& IP valves and travel of valve stems



HP main stop valve



Name Valve shell / bonnet Quantity Bonnet bolts



HP governor valve



ZG15Cr1Mo1



Piece



Thread and



IP stop valve



IP governor valve



ZG15Cr2Mo1



15



10



22



16



3 1/2(GH)



2 3/4(GH)



3 (GH)



1 1/4(GH)



Φ280



Φ170



Φ567.8



Φ510



specification mm



Page 49 of 241



Fitting diameter of valve disk and valve seat



Maximum travel of valve rod



Valve rod



Diameter (thick end/thin end)



Diameter Pre-inlet valve Travel



mm



127.5



49±2



145



210±3



mm



Φ95/Φ76



Φ55



Φ79



Φ111/Φ94



mm



Φ111/Φ94



Φ50



Φ108



Φ231



mm



20



5



5



54



The pipe creepage detector is installed at the outlet nearing the governor valve of HP main steam pipeline connected to the valve to detect the steam pipeline deformation. Record the data when the unit is put into service and measure the pipeline creepage data periodically later. 3.2.2.21.3 The valve support The HP main governor valve is supported rigid frame. On the both side of HP governing valve, rigid hanging rods of Φ90 are used, and constant tension hanger is arranged before the HP main stop valve. Thus, HP main steam governing valve is supported with rigid system from 3 points. One support for oil actuator is on the back of the HP main stop valve. The HP governor valve oil actuator is hung on the support and supported by the separate rigid hangers. IP intercept valve is supported by elastic spring support. The IP intercept valve is seated on the spring support which will move freely along with the heat displacement of IP composite valve. One constant force hanger is arranged on the IP steam pipeline. 3.2.2.22



Sliding Pin System and Differential Expansion Due to the temperature changing, the turbine will expand during the start-up and shutdown. In order to make the moving part and static part expand freely in the preset direction, and keep the unit in safety operation, reasonable sliding pin system is designed. Unit heat expansion drawing The relative dead point of HP inner casing to HP outer casing is 475mm before the steam inlet central line, the convex edge of retaining ring holds the position of HP inner casing. The relative dead point of the LP inner casing against LP outer casing is on the LP steam inlet central line, HP and LP casings expand toward and Page 50 of 241



backward. It provided 2 fixed points for the turbine stator against foundation via a transverse key, one is at 205 mm to the back of the 2# bearing center line on the foundation of the I&LP bearing box, another is 360mm in front of the LP steam inlet center line at the left and right foundation of the LP casing. During unit startup, H&IP casing and front bearing box will expand forward, and the LP casing expand to the front and back direction. The fixed point (known as relative dead point) that the rotor is relative to the stator is at the place of the thrust bearing in I&LP bearing box. During unit startup, the rotor will expand to forward and backward. In order to decrease the friction resistance during the bearing box sliding and make the casing expand freely, the self-lubricating sliding block is installed at the bottom of the front bearing box, and the lubricating film is sprayed on the sliding block at the bottom of the box, which is used to eliminate the dry friction between the box bottom and gasket. In order to ensure the lubricating effect, spray the lubricating film to the sliding block at the bottom of the box again during the overhaul every time. The H&IP casing structure and steam flow direction of this unit are proper, the rigidity of the casing is large, and the limitation of the flow clearance to the expansion difference is small. The LP part adopts inclined flat tooth steam seal, and the self-lubricating sliding block is adopted between the gaskets of the front bearing box. So the expansion difference is small during unit startup or load change, and the flexibility and load adaptability is good. If rotor heat expansion is greater than that of the stator, it is designates as "+", otherwise, it is designated as "-". It is required that alarming signal should be provided from protection system when the differential expansion is beyond the limits. 3.2.3



Turbine maintenance procedure



3.2.3.1



Disassembly procedure In this turbine, HP-IP casings are of a whole construction, and HP casing is of double layers while LP casing is of balanced flow distribution type with double layers. HP-IP and LP are all adopt counterflow scheme. Steam admission ports of HP and IP are all arranged at middle of HP and IP casings, where the temperature is the highest. Valves of HP and IP are of floor type, which are installed symmetrically at left and right sides. Total length of the unit is 18m.



3.2.3.2



Maintenance Method, standard and proceeding of Casing



3.2.3.2.1



Measure the cables and auxiliaries by I & C personnel and remove the heat insulation.



3.2.3.2.2



Remove the bolts on heat insulation board, disassemble the heat insulation plate and hang it out.



3.2.3.2.3



When the temperature of the upper half HP outer casing is lower than 150℃, remove the heat insulation layer by layer.



3.2.3.2.4



Remove the HP and IP steam conduit and IP and LP connective pipeline. The procedure is as follows: a)



After the heat insulation is removed, when the temperature of HP upper inner casing outer wall at governing stage is lower than 100℃, remove the steam Page 51 of 241



conduit and outer casing flanges, the conduit and HP and IP governor valve outlet flange bolts. b)



Remove the IP and LP connective pipeline flange bolts.



c.) The temperature of HP upper inner casing is lower than 80℃, hang out the HP steam conduit and IP and LP connective pipeline by the overhead crane with a chain on its hook. (Pay attention to install the expansion joints before and after the connective pipeline properly before hanging) d)



After hanging out the conduit and IP and LP connective pipeline, plug the flange opening and pipeline outlet with the baffle plate and seal it,



e.) Check the welding seams of steam conduit expansion joints for cracks and sand holes, etc. 3.2.3.2.5



HP, IP and LP casing disassembly procedure a)



Maintain the casing temperature and pressure measuring points.



b)



Remove the seal cap on casing bolt nuts, clean up the heating holes on the bolts.



c)



Casing bolts must be warmed by using the bolt heater supplied by the manufacturer after the temperature of casing wall at the governing stage reduces to less than 80℃ and in the order of nuts disassembly, and make the marks. Pull out the 4 locating pins from the upper and lower casings. After the bolts are detached from the washer, if the nuts are stuck or too tight, tap them on the top and around with a small hammer or the copper rod. Simultaneously, turn the nuts clockwise or anti-clockwise to prevent it damaging the bolt. If the nuts are stuck, stop disassembling. Wait for the temperature to reach room temperature, and then apply lube grease onto the bolt. Use a suitable amount of force to turn the nut, tapping it gently if needed until it loosens. When necessary, heat the nuts properly, but the temperature can not be higher than 300℃, then, remove the nuts. Remove the nuts with the special tools, and hang out the upper nuts and bolts. Number the bolts more than M52, nuts, washer, special washers and bolt holes, and put them on the special support for the bolts, when necessary, reassemble them according to the original number.



d)



Remove the bolts on the connective surface of HP-IP - LP casing end outer shaft, simultaneously, draw out the locating pins on the split of the casing with special drawing tools.



e)



Fit the guiding rod and apply some lube grease on it, check the lifting device. Lifting tools should be safe and reliable with reasonable binding; the central line of the hook should aim at the casing gravity center.



f)



Jack the casing on four corners evenly with the jacking screws for the turbine by 3~5mm. Hoist the casing carefully with the overhead crane. Monitor the jacking value with a stainless steel ruler or a dial gauge (jack up the casing by at least 100mm with the hydraulic jack, then hoist it up). The level error in the process of Page 52 of 241



hoisting can not exceed the limit. The horizontal forward and backward movement should be ≯0. ５ mm/M, that on left and right directional movement should be ≯0.5mm/M. Be sure to measure the movement at the four corners regularly and check whether there is obstructed movement. If it exists, stop lifting and resolve it timely. Observe the upper HP steam inlet pipeline for the blockage. The I&C personnel should oversee the compensation conduit goes out of the outer casing wall successfully in the process of hoisting. The crane man should command the hoisting in the whole process comprehensively. It is forbidden to extend the head and hands to connection surface. Hoist the HP, IP and LP outer casings. g)



The HP outer casing should be put on the designated place after lifting. The support should be reliable and convenient to maintenance.



3.2.3.2.6



Remove the bolts on all the IP upper diaphragm splits. Hang out all the upper diaphragms slowly and inspect them.



3.2.3.2.7



HP, IP and LP inner casing disassembly procedure.



3.2.3.2.8



a)



Remove the joints of the pressure and temperature measuring outgoing line at governing stage, beside the inner casing bolts and temperature measuring element on casing wall.



b)



Remove the pipe plug on the upper half of HP steam chamber（2.5″） install the bolt eyes M39×3. Remove the upper half of steam chamber.



c)



Remove the inner casing bolts (in the same way as outer casing). For the #1 and #2 inner casings, the manhole on the upper half casing should be opened first, remove the bolts on the connective surface and the flanges on LP casing spray pipeline.



d)



Install the guide rods at four corners (or two rods in diagonal direction) and apply the grease on the rods. Jack up the casing on four corners with the special bolts evenly by 3-5mm, then hoist the casing slowly till it is 10mm away from the lower casing surface. Check and confirm the binding of overhead crane and the steel rope is in good condition, continue to hoist the casing slowing. (The other technology requirements are the same as the outer casing.)



e)



Check the inner casing connection surface for leakage and remark it.



f)



It is required that 4 persons are designated to support the 4 corners during lifting. They are also required to pay attention inner casing for round of rubbing. Check the guide arm and make sure there is no stuck.



,



Casing turn over procedure a)



Use the traveling crane to turn over the casing during casing turn-over, the steel rope is suspended on the lifting eyes on casing outer. After alignment of the traveling crane, use big hook to lift up for 100mm and then use the small hook to move casing a little bit away from the support timber. After a complete check for



Page 53 of 241



lifting tools and confirm everything is good, use the big hook to lift up again. Suspension height is so required that casing cannot touch the floor when the small hook is released. Gradually, release the small hook so that the casing weight is fully supported by the big hooks. b)



3.2.3.2.9



Completely loosen the hook, take off the wire rope and turn the casing for 180°, hang the wire rope on the hook and suspend the wire rope tightly, and slowly loosen the hook (lift the hook properly if necessary) until the casing is put at the horizontal level, use the sleeper to underlay it tightly, and then loosen the two lifting hooks after the casing is put safely.



Casing overhaul contents: a)



Clean the casing joint surface by abrasive paper until it is polished.



b)



Measure the level of joint surface of the lower casing. Put the level gauge on the permanent mark made during installation or first overhaul, and make the record.



c)



Clean up the joint surface and perform visual inspection and magnetic particle detection test.



d)



If it is necessary to check the casing outer wall, the insulation should be removed and be cleaned up, and then carry out the detection.



e)



If there is the crack, we should find out how deep it is. For the crack occurred at the casing joint surface, it can be measured by ultrasonic damage detector.



f)



The casing joint surface should be smooth and tidy without continuous perforated trace, the level measuring value should basically accord with the installation record (or the last time overhaul). If there is casing crack, deformation and other faults, report to the relevant department for analysis and handling.



g)



Clean and check the diaphragm(blade carrier), gland seal sleeve groove and casing bolt supporting surface, carry out the visual inspection to the casing diaphragm and gland seal sleeve groove after they are cleaned by abrasive paper.



h ) The surfaces of bolts on the casing should be clean, remove the burrs. Check the connection with a piece of round flat board. If necessary, grind it. i)



Clean up the casing nut and the thread of the bolt by the steel wire brush.



j)



Check the threads carefully. whenever there is damage or burr were found on threads, amend it by triangle oil stone or fine file, and then carry out the inspection with nut, screw the bolt after the a little turbine oil is coated on the nut and continue to do the necessary repair until it can be screwed completely by hand (the inner screw thread should also be screwed to the bolt according to the number for inspection). If the bolt and nut match tightly and there is no burr on the screw thread, use the fine grinding paste to grind it and clean it by the kerosene, and then coat the bolt high temperature lube oil. Page 54 of 241



k)



Measure the hardness of all the steel alloy bolts for the casings.



l)



The ultrasonic detection test should be performed for the bolt more than M56.



m) Check the metallographic structure of some bolts n)



Check whether the sphere washers for the casing bolt has burr or not. If so, perform the necessary repair.



o)



Apply the black carbon powder to the bolts, nuts and washers which are cleaned up, checked and repaired, make all their surfaces have the black color, wipe away the surplus powder and keep it well.



p)



Check whether the flow guiding plate of the LP outer casing, reinforced rib and extraction orifice have crack, if there is crack, weld it for reinforcing.



q)



Check and clean the water spraying pipeline and bracket in LP casing, check that the pipeline has no corrosion, the water spraying orifice has no blockage and break, and the spraying direction is right.



3.2.3.3



Casing re-assembly procedure:



3.2.3.3.1



The following requirements should be satisfied before the casing re-assembly.



3.2.3.3.2



a)



All the work in the casing has been finished, the relevant record materials are complete and have been checked and accepted.



b)



The inner casing has been cleaned up without foreign matters left in it.



c)



All the drainage and steam pipes connected with the casing are clear.



Fitting the inner upper casing a)



Install the guiding rod and apply the turbine oil.



b)



Use the special tool to suspend the casing to leave from the ground, and adjust the longitudinal and transverse level of the split by frame type level to make the inclination of the casing be less than 0.2mm/m.



c)



Clean upper casing with compressed air, and hook up after inspection. Also check the steel rope and traveling crane conditions. After make sure that the casing is on the lower casing, then lift up the casing cover to 200-300mm. Underlay the wood block to the foursquare, and remove the wood block after the paint is coated on the split evenly to make the casing drop, and when it drops to 5-10mm, punch the pin and screw the guiding rod out, and the then the upper inner casing drops to the lower inner casing.



d)



After the pin is tightened, screw in the bolts, and then tighten the casing bolt under cold state according to the order. The bolt of H&IP inner casing must be tightened under hot state.



e)



Remove the bolts for suspension in HP casing and HP steam chamber, and



Page 55 of 241



screw in seal plug and weld them. 3.2.3.3.3



Cover the H&IP outer casing, first tighten the outer casing bolt under cold state and then tighten the outer casing bolt under hot state. The casing covering process is as the same as the process of the inner casing.



3.2.3.3.4



Re-assemble the HP, IP and LP steam guiding pipe.



3.2.3.3.5



Install the blank cover on the outer casing nuts.



3.2.3.3.6



Install the temperature measuring elements.



3.2.3.3.7



Install the HP, IP and LP steam conduits.



3.2.3.4



Casing bolts disassembly and assembly technology a)



Under the principle that the tension force between the upper and the lower flanges which will cause the flange deformation can not fall on the last several bolts, the reasonable disassembly procedure is that remove the bolts with the maximum clearance in middle part first, make the clearance recover gradually.



b)



Usually, electric heater with stainless sleeve is used to warm up the center hole of bolts to make the bolts expand. When the bolt heating is kept for the specified duration, loosen the nut by special wrench, and stop heating when the nut can be screwed lightly, and then screw the nut out after the heating tube is taken out.



c)



When the nuts are loosened or warm-up time finishes, if it is found that the nut is blocked or too tightened, use the small hammer or cooper bar to rap around the nut and rap the top of the nut slightly, at the same time, rotate the nut backwards and forwards to avoid blockage of the bolts threads.



d)



Stop removing the bolts if thread blockage is found while loosening bolts. After the temperature of the bolt drops to the ambient temperature, inject the kerosene and bolt loosening liquid to the screw, and grind the nut with the movement of the proper moment. At the same time rap the top of it with hammer. If necessary, heat the nuts to remove the burr inside the threads gradually, and then remove the nuts. If it is impossible to remove the nuts, cut the nuts off by a skillful welder and keep the bolts.



e)



Restore casing cover and fit the pins. Put the spherical washers as the mark and tight the nuts. The disassembly procedure is same to the procedure for removing casing bolts. Tightening force is recommended at 10.8kgm for every 1cm in the bolt nominal diameter.



f） After cold tightened, the bolts can be performed warm-up tightened. the markings on the nuts. g)



Make



Heat the bolt with the heating bar in the order of cold tightening for 15-30 minutes. When the nuts can be turned by half the hot tightening arc, stop heating. Install the tube plate until the marking line on the nut is aligned with the casing base.



Page 56 of 241



h)



The bolts on the splits of all the casing should be cold tightened before being hot tightened, the cold tightening should be performed with the torque spanner, the hammer is not allowed to be used.



i)



The extension amount error of bolts on splits by hot tightening is ±10%. If adopt the corner turning method, measure the original length with the measuring instrument after the bolts are put in place. Measure the length again after the hot tightened bolts are cooled to the room temperature. Then, the extension amount can be calculated. Check whether the extension meets the requirements or not. If not, adjust the turning corner.



j)



After all the nuts are hot tightened, reassemble the protective caps.



HP and IP casing bolts disassembly drawing Note: It is recommended that cold tightening torque for bolts is 10000N and tightening sequence should follow serial number from high value to the lower one in the drawing. Then follow Bolt Hot Tightening Instruction to perform hot tightening. For disassemble, bolts removing sequence is reverse. Page 57 of 241



LP casing bolts disassembly drawing 3.2.3.5



Casing maintenance quality standard and technology requirements



3.2.3.5.1



Joint surface tightness 1)



Check joint surface for leakage after the HP, IP and LP upper casings are lift out and make the records. After the casing joint surface is cleaned, install some casing bolt according to the demands, suspend the upper casing and punch into the register pin. Measure the inner and outer horizontal split clearance of the casing by filler gauge under the two conditions and make record: under the free state and the casing bolt is tightened with 1/3 degree under cold state. After it is finished, pull out the pin, loosen the bolt and suspend the upper casing. When cover the empty casing for the IP inner and outer casing, under the free state, the joint surface clearance should be less than or equal to 0.05mm, and it should be less than or equal to 0.03mm when the bolt is tightened with 1/3 degree, and the joint surface clearance of the LP inner casing is less than or equal to 0.05mm



Page 58 of 241



when the bolt is tightened with 1/3 degree. It is no need to cover empty casing for LP outer casing because it has no repair. If the joint surface needs to be repaired, the empty casing should be covered and the gland seal clearance should also be checked.



3.2.3.5.2



2)



Measure and adjust the supporting working gasket clearance between the HP, IP and LP inner and outer casing, measure the relative height between the adjusting gasket of outer upper casing and the split of the inner casing by depth gauge or dial gauge.



3)



Measure the level of the lower casing inner and outer connective surface. The deflection should be measured in suspending condition. The casing upward inclination and the required direction is the same. (The deflection in axial direction should be opposite, the front and rear deflection of HP and IP casings should be in the same direction at the turbine head). The adjustable level gauges, of which the precision are 0.01 ／ 1000 or 0.02 ／ 1000 , before and after the LP casing should be put on the markings made in the installation or the first time overhaul. In order to eliminate the errors, turn the level gauge by 1800 and measure again. Take the arithmetic average value as the final result, and compare it with original record, if the difference is too big, find out the reasons and deal with them.



4)



Carried out magnetic detection of defects on the casing jointing surface after cleaning. Remove the heat insulation, clean it up, and check the casing inner and outer walls (especially the cross section). If the crack is found, measure its depth with the ultrasonic destruction detector. The connective surface should be smooth and flat without the grooves. If any, report it the superior and deal with it.



Lifting up H&IP casing a)



Carefully check all the bolts of casing horizontal split and make sure that the pin has been dismantled, and the flange of the steam pipe and the drainage pipe connected with the upper casing is dismantled.



b)



Install the special lifting tool, the traveling crane aligns the center, at the same time install a percentage meter on the rotor to monitor the suspending conditions.



c)



Jack up the casing for 10-15MM by special screwing rod or special foursquare oil pressure jacking device. Note that the foursquare should rise evenly without declination during jacking, and stop working if there is problem at some place. Use the ruler to check that the distance of the jacking joint surface is qualified, and then stop the jacking work and begin to use traveling crane for suspending. The suspending work should be directed by special personnel, and there are should be personnel around the casing for monitoring.



d)



Slowly lift the traveling crane hook, check that the conditions around the casing and that the stress of the wire rope is even.



e)



During hoisting, the four angles is held by monitoring personnel who monitor



Page 59 of 241



whether there is blockage and friction between the bolt and screw, and check whether the lifting height of the foursquare of the casing cover is even or not, if there is any one part does not rise following the traveling crane hook or there is other abnormal condition, stop lifting immediately, and then adjust again for alignment.



3.2.3.5.3



f)



The foursquare height during casing lifting is measured by steel scale, and the difference between the front and back part should not be more than 3mm, and the difference between the right and left one should not be more than 5mm.



g)



After the casing cover is suspended out, it is put at the appointed maintenance site, and underlay the sleeper on the ground.



h)



Check the steam leakage trace on the casing joint surface and make record.



i)



Remove the stud bolts on the casing connective surface (for the inner casing bolts and diaphragm removal). Apply some kerosene to connection plate of the stud bolts and the casing. Tap the top of the screws and unscrew the bolts with the special tools.



Requirements for alloy steel bolt of HP, IP and LP casing. a)



The bolt and nut are clean, the screw thread has no mistaken cover and burr, the matching is good without blockage, and the bolt has no abnormal phenomenon such as crack, damage, bending and so on.



b)



The bolt hardness values within the range of HB240-270, no obvious net structure be seen (the metallographic structure has be identified by metal group).



c)



The stroke toughness should meet the following requirements. M65：ak≥10kgM/cm2，M65-M100：ak≥8kgM/cm2 ，M100：ak≥6kgM/cm2； The bolts lower than M65: ak≥10kgM/cm2 The bolts M65-M100: ak≥8kgM/cm2 The bolts more than M100: ak≥6kgM/cm2



d)



The bolt should be replaced or the recovery heat treatment should be carried out if the bolt hardness value reaches the following condition (the hardness value is more than HB300 or less than HB200)



3.2.3.6



Heat insulation recovery



3.2.3.7



Maintenance contents a)



Check the heat insulation hooks on the casing outer wall are complete.



b)



Install the heat insulation. The heat insulation material should be fixed firmly. When indoor temperature is 25℃, the heat insulation surface temperature should not be higher than 50℃. The heat insulation material can be aluminum silicate.



Page 60 of 241



Pay attention to the heat insulation material seams. Cover the heat insulation material with the iron wire mesh and make it flat. 3.2.4



Maintenance on Turbine Rotor



3.2.4.1



Structure of Rotor: In this unit, HP-IP and LP rotors are of complete forged components, inwhich HP- IP rotors covers HP section (9-stage impellers with adjsuting stage) and IP section (6stage impeller), LP rotors (altogether 12-stage impeller of both direct and counter directions). The connection between LP rotor and HP/IP rotors, and connection between LP rotor and generator rotor are of rigid coupling connection.



3.2.4.2



Maintenance Method, standard and proceeding of Rotor



3.2.4.2.1



Journal deflection measurement:



3.2.4.2.1.1 The deflection of journal should be measured under the following conditions. Check whether the measuring rotor deflection is equal to the record, and record the unit falling condition, which is the reference to the alignment of the rotor.



3.2.4.2.1.2



a)



The journal deflection before maintenance and before and after the coupling bolt is dismantled.



b)



The journal deflection before and after the push-pull gasket is drew out for cleaning.



c)



The journal deflection after maintenance and before and after the coupling bolt is tightened.



Measuring process a)



Loosen the bolts in the couplings between the HIP rotor and LP rotor, LP rotor and the generator rotor, screw on the nuts of bolts which are removed. Arrange them in order. Don’t tap the bolts severely.



b)



Clean the surface of the journal which needs to be measured, and put the water level gauge in the center of the journal to make the transverse blister which is used to adjust the water level stabilize at the middle position.



c)



Adjust the dial of the combined figure level to make the longitudinal blister stabilize at the middle position and record the reading on the dial.



d)



Turn around the level meter by 180° and put it to the original position, use the same way to record the second reading. The arithmetic average of the two measuring values is the journal deflection value.



a b Page 61 of 241



e)



Measure the deflection of other journal by the same method, shown as the above Figure:



3.2.4.2.1.3 Rising inclination measurement Technology requirements and quality criteria



3.2.4.2.2



1)



Rotate the rotor to the first flying ring or the upward fixed position of the second flying ring by the turning gear before measurement.



2)



Clean up the water level gauge before using it, adjust it to the 0 position and put it stably.



3)



The calculation method for measurement: if the twice measurements are opposite, the bigger one is the lifting direction, and the deflection is 1/2 of their difference, that means the journal deflection value is half of the difference between the two readings, that is(a-b)/2.



4)



If the twice measurement directions are the same, the deflection is half of their algebraic sum, the lifting direction is shown by the arrowhead.



5)



If the twice readings of the level meter are equal, but the scale indications are opposite, which means that the level meter is accurate.



Rotor eccentricity and bending degree measuring a)



Polish the measured surface



b)



Divide the circle of the measured part into eight equal parts, and number them by chalk in reverse direction (the first point should be set with the permanent markings).



c)



Rotate the rotor clockwise by turning gear, record the each point reading, and finally return to “1”position. The reading should accord with the primary reading, otherwise find out the reason and measure it again, the difference between the maximum and minimum value is swing degree. The half of the difference between the two ends reading of the same diameter is the bending degree on this cross section, and the maximum value is the maximum bending degree.



d)



Standard eccentricity of HIP rotor and LP rotor, see the drawing.



Page 62 of 241



e)



Illustration of Diagram for Measuring HP Rotor Expansion



f)



standard eccentricity for HIP rotor and LP rotor : ≯0.05㎜ Bending degree: ≯0.03㎜



3.2.4.2.3



Measurement for out-of-round and ellipticity for journal a)



Taper measuring method It is measured by the external micrometer, and the difference between the maximum and minimum value measured in the same vertical section is the taper, and its standard requirement is not more than 0.02mm.



b)



Elliptical degree measuring method There are two methods: first, fix a percentage meter on the horizontal joint surface of the bearing pedestal and make it press at the upper part of the journal, adjust the “0”position, and then slowly rotate the rotor for one circuit by turning gear, the maximum tripping value indicated by the percentage meter is the maximum ellipticity of the journal and its standard requirement is not more than 0.02mm. Second, the difference between the maximum and minimum value measured by the external micrometer in the same cross section is the ellipticity



3.2.4.2.4



Measurement for thrust disk, coupling and deflection of the rotating wheel end face 1)



Install the temporary position limiting device for the rotor and limit the axial movement of the rotor properly. Divide the circle of the measured part into eight equal parts, and number them by chalk in reverse direction, the first point should be set with the fixed mark.



2)



Dial gauges at two points on the surface which has the same distance from the verge and is in symmetry with the rotor center. Aim the measuring rod of the meter at point “1”and“5”, which is vertical with the plate surface, and then adjust the meter pointer.



3)



Rotate the rotor by turning gear clockwise on to make the dial gauge aim at each point and record the reading of the dial gauge, and finally make the meter return to position “1” and “5” (The rotor cannot be rotated in converse direction during measurement.).



4)



The calculation for the deflection of the thrust disk: first calculate the average value of the two dial gauge reading at the same position, and then calculate the difference between the two values of the same diameter, which is the absolute value of the deflection of the thrust disk on this diameter, and the maximum value is the maximum deflection of the thrust disk.



5)



Precautions and quality standard a)



Check that the accuracy of the measuring tools should is not less than 0.01mm. Page 63 of 241



b)



The measuring position is right and the tightness degree is the same.



c)



The journal should be cleaned during measurement.



d)



Avoid the lower half bearing from dropping when the rotor is being turned.



e)



The meter rod of the dial gauge should have 10mm away from the edge of the thrust disk during installation, and try to make the meter rod be vertical with the end face of the thrust disk. Figure. Rotor deflection measuring



6)



7)



f)



The end face of the thrust disk should be smooth without burrs, the dial gauges should be installed firmly and the indication should be accurate.



g)



Calculate the deflection of the thrust disk, and the maximum value should not be more than 0.02mm.



h)



The maximum allowable deflection for the coupling is 0.03mm.



i)



The allowable deflection for the impeller (forged)



is 0.03mm.



Measurement of Rotor Axial Displacement Procedures a)



Assemble the thrust pad, cover inner cover of thrust bearing, stick in inner pins and tighten middle surface bolts and then assemble #2 bearing;



b)



Put the magnetic dial gauge on outer shell of thrust bearing, assemble the dial indicator to make indicator rod tested on thrust bearing bush and be parallel to the shaft, in this way to measure the axial displacement of bearing bush;



c)



Fix another magnetic dial indicator on bearing pedestal combination surface, assemble dial indicator to make indicator rod rest on certain area of rotor and be parallel to the shaft;



d)



Push and pull the rotor to front and rear limit position by jack, and get the maximum and minimum reading of dial indicator;



e)



The difference value of dial gauge is the total axial displacement. This axial displacement minus bearing bush displacement is the thrust clearance;



f)



Thrust clearance standard value for this unit is 0.38 ～ 0.42 ㎜ . Thrust clearance of this unit can also be measured by moving the thrust bearing shell.



Maintenance technical requirements and quality standard of thrust bearing a)Prevent journal bearing turning out with rotor when rotating rotor; b)



Thrust pads should be assembled according to the sequence and be cleaned. Put some turbo oil into thrust pad during assembly.



c)



The dial indicator should be tightened, stable and the pointer should point correctly.



d)



Thrust clearance should be within 0.25-0.50mm, if not, find out the causes and make proper adjustment.



Page 64 of 241



3.2.4.2.5



Measurement of clearance between moving blades and stationary blades The purpose for measuring the moving and stationary clearance is to monitor the minimum clearance at steam inlet side, and it should be no less than original value, and to monitor if there is creeping or if the fixed steam stopping blade(blade tip gland seal)crosswise clearance is too small. After unit starting, if there is any moving and stationary friction, the clearance would be too much and then the unit efficiency would be affected. 1)



2)



Measurement requirements a)



Set rotor zero position upwards (#1 flying hammer upwards);



b)



Push rotor to working surface;



c)



Feeler gauge and wedge type feeler are used to measure the axial clearance between moving blade root and blade tip. During measurement, it is usually suggested to use more than 3 pieces of feelers. If a wedge type feeler is used for measurement, be careful not to push too hard so as to prevent an n extra measuring error. Besides, the minimum one is be the standard value. Write down original value of clearance between the impeller and diaphragm after newly built unit first overhaul or when certain parts are replaced, and make marks at the measurement positions for future re-check. During the measurement, the clearance between impeller, blades and diaphragm should according to the impeller deflection degree, and vertical degree of diaphragm inside the casing and the position deviation to the minimum value. When the deviation between measured value and original data is too much, further check and find out the causes, and carry out corresponding treatment when it is necessary.



d)



After the measurement, rotate the rotor 90°counterclockwise and then carry out the above measurement again (make complete records and carry out the above measurement after disassembly and reassembly).



Measurement Procedures a)



Pull the sliding ruler of wedge feeler to the proper rear position before measurement;



b)



Put wedge feeler tip into the measuring position of rotor;



c)



Push sliding ruler to the front of wedge feeler and casing combination surface position or the stationary blade end face position;



d



Fix the sliding ruler by hands and then take out the feeler slowly;



e)



Measure the thickness at where the wedge feeler points and then make records;



f)



The position for moving and stationary blade clearance is shown as follows: Measurement position for 1st stage (single speed stage) flow path 2-15 Measurement position for flow path clearance



3)



Technical requirements and quality standards a)



Push rotor backward before measurement and then make it contacted with the thrust pads, and make the flying ring upwards to carry out the first measurement;



Page 65 of 241



3.2.4.2.6



b)



Rotate rotor 90°along the rotor rotating direction to carry out the second measurement;



c)



During measurement, pay attention not use too much force to put the wedge feeler into the measuring position;



d)



The measured position should be flat without any burrs;



e)



During the measurement, if certain value deviation is too much, find out the causes;



f)



Measurement of LP rotor: its rotor position is same with HP rotor, and the measurement should be carried out at 90°and 180°。



Turbine rotor maintenance



3.2.4.2.6.1 Turbine rotor alignment Procedures a)



Connect the HP and LP rotor according to the assembly mark, and dent into two special pins in the screw of the coupler for alignment (the two pins are dente in d symmetry).



b)



Install the special dial gauge (with 0.01 accuracy degree) for alignment on the screw end of the HP rotor away from 180°. Install it with the pointer of the two plane dial indicators vertically point at the end face of the LP rotor coupler and make the pointer of the circle dial indicator vertically point at the circle of the LP rotor coupler.



c)



Wind the wire rope on the circle of the LP rotor coupler along the rotating direction of the rotor, and make one end of the rope is fixed at the special pin and another end is hanged on the hooklet.



d)



Calibrate the dial indicator and rotate the rotor along the rotating direction of the rotor, and then measure the reading at the position of 0°,90°,180°, 270°and make record. When the rotor returns to the 0 position, the pointer of the dial indicator should return to the reading during the pointer calibration, otherwise find out the reasons and measure it again. Note that the wire rope must be loosened while reading to make sure that the pin installation is right.



e)



Calculate the circle difference and end face difference according to the measured value.



f)



The alignment method for LP rotor and generator rotor is the same.



3.2.4.2.6.2 Technical requirement and quality standard a)



The installation of the meter rack and dial indicator should be firm. During installation, the end face dial indicator should be vertical with the end face of the coupler, and the circle dial indicator should be vertical with the center line of the bearing as much as possible.



b)



When the rotor is rotated by the traveling crane, it should be done slowly to avoid that the rope slips, which will damage the operator or break the meter.



c)



During the reading of the dial indicator, the hooklet of the traveling crane should be loosened a little, loosen the wire rope to make the rotor at free condition.



d)



During alignment, the measurement should be carried out twice. Compare with the measuring data which should keep consistent basically. Page 66 of 241



e)



The alignment for coupler should satisfy the following standard, otherwise adjust it: End face gap: 0.03mm Circle deviation: 0.04mm



f)



The elevation adjustment for #2 and #4 lower bearing sleeper is as following: Remove 0.20-0.25mm of the #2 bearing pad foundation, and remove 0.05-0.10mm of the #4 bearing pad foundation.



3.2.4.2.6.3 Find center pointer for coupling



Fig a)



Schematic diagram for coupler alignment



The reading record of the dial indicator and the calculation, as the record in the following Figure: B1=（B1′+B3″） /2



B2=（B2′+B4″） /2



B3=（B3′+B1″） /2



B4=（B4′+B2″） /2



End face: b=B1-B3，it is upper and lower opening b′=B2-B4, it is right and left opening Circle: a=（A1-A3） /2，it is the height displacement, that is the center deviation at the vertical direction of the coupler. a′=（A2-A4） /2 ， it is the right and left displacement, that is the center deviation at the horizontal direction of the coupler. b)



Adjustment for misalignment



The adjustment calculation is as following: Page 67 of 241



δA=LA×(ΔX/Ф)+ ΔY；δB=LB×(ΔX/Ф)+ ΔY ΔX is the upper and lower opening b； ΔY is the circle height displacement a; LA and LB are the distance from the coupler to the bearing pad; and Ф is the diameter of the coupler. 3.2.4.2.6.4



The method for bearing pad adjustment The bearing pad of this unit has adjusting cushion block, and the bearing pad can be removed by changing the gasket thickness of the cushion block of the lower half bearing pad. Because the closed angle between the center line of the two sides iron cushion and the vertical center line of the bearing pad is θ, the adjustment of the gasket thickness is not equal to the required movement of the bearing pad, the relationship between them is shown in Figure a)



When it is removed V at vertical direction, the plus and minus value for the lower iron cushion and gasket are the same as the bearing pad movement V, plus and minus Vcosθ to the two sides iron cushion and gasket respectively.



b)



When it is removed H at horizontal direction, the lower iron cushion and gasket will not move, plus and minus S=Hsinθ to the two sides iron cushion and gasket respectively.



c)



If the bearing pad needs to be removed at the vertical direction and horizontal direction, the adjusting value for the two sides gasket is algebraic sum of the above two values.



Figure schematic diagram of bearing bush supporting iron 3.2.4.2.6.5 Requirements Take operation condition of this unit and installation requirements of the similar units into consideration, the coupling alignment work should meet following requirements: a)



It should keep a distance of 0.15-0.17mm from lower surface to center point of coupler between HP-IP rotor and LP rotor. For the outer overlap opening, it is required to below the center point of the coupler H-IP by 0.20-0.22 mm.



b)



The LP rotor aligns the coupler center of the generator rotor, the lower opening of the end face is 0.10-0.12mm， the center of the LP rotor is 0.08mm lower.



3.2.4.2.6.6 Lifting of rotor and putting back turbine rotor 3.2.4.2.6.6.1 Lifting of rotor 1） The rotor lifting should be directed by experienced personnel, and before the rotor lifting, the person in charge should check the following items: Page 68 of 241



a)



The couplings are unbolted and the two couplings are opened for more than 3mm clearance. Make sure the engagement is disengaged and then add gaskets between the impeller.



b)



All the measurements are finished before overhaul, the record is accurate, clear and complete;



c)



Make sure the upper half of front and rear rotor bearing is removed;



d)



Working pads of thrust pads are already taken out;



e)



Rotor support is already arranged, support roller should be clean, rotate flexible and lubricated by lube oil.



2） The traveling crane operator should cooperate with the electric operator to carry out the careful inspection for the traveling crane, and the braking and deactivation protective device should be sensitive and reliable. 3） The personnel in charge of the lifting maintenance should carry out careful inspection to the special lifting tools and wire rope. The lifting tools tests should be qualified without any damage. 4） There should be personnel around the rotor for monitoring, pay attention to monitoring the dynamic and static sound when the rotor is suspended out from the casing, and the rotor should not swing. 5） There should be not less than 6 personnel arranged at the two sides of the rotor and impeller to hold the rotor and the personnel is responsible for the lifting work during the lifting. 6） After the rotor is lifted a little bit high, put the frame type level meter at the place of the journal to check and adjust the level of the rotor, the reading of the level meter should not be more than 0.10mm/m (That means the error will not be more than 0.10mm ). 7） During rotor lifting, special attention shall be paid to ensure that there should be no friction, swing and blockage between the dynamic and static part and between the front and back gland seal. 8） After the rotor is lifted out, put it at the special bracket stably. 3.2.4.2.6.6.2 Putting back turbine rotor 1)



Adjust the concentricity of the rotor, inner casing and concavity of oil retainer at inner side of bearings to the standardized range based on the measuring result prior to disassembly and the operating state before overhaul.



2)



Before putting back rotor, the following must be proceeded; Reassemble the lower half blade carrier, the balance piston seal, the low half diaphragm, the lower bearing and the front and rear seal bushings must be reassembled. Provide lube oil to the lower half bearing pad. Adjust the thrust clearance to the stand value. Adjust the flow path clearance and make the value K meet the requirements’measure the rotor deflection, make the record well. Re-align the couplings in the case that the half casing is not covered and covered respectively. Adjust the gland seal clearance based on the rotor. After the non-service thrust pads are assembled, the rotor can be located. Page 69 of 241



3)



Before the rotor is lift up, clean up the rotor with the compressed air first.



4)



After the rotor is suspended, put the frame type level gauge on the rotor to adjust the rotor level. The reading of the level gauge should not exceed the five scales. (i.e. the error not more than 0.10mm)



5)



Direct the rotor at the casing accurately. Stabilize the rotor based on the previsions during the Lifting. Lower the rotor slowly. No friction, collision or crush on thrust pads can occur in the course of the Lifting.



6)



Remove the lifting tools after the rotor is put down. Jack the rotor to the nonworking side by special tools and install the working thrust pad. Apply some lube oil to the bearing journal and the thrust pads. Turn the rotor with the copper lever or tools manually. Check all the components, no friction should be occurred among the components.



7)



Coupling connection: Put the cleaned bolts into the coupling holes in accordance with the marking, apply some lube oil to bolts and tap the bolts with small hammer or copper in the course of assembly. Apply some MoS2 powder to the bolt threads. Tighten the two bolts in symmetric direction one by one for each time. Measure the bolts extension amount after they are tightened well (the bolts should be measured before). Install the blank flange and stopping screw and carried out the tack welding to prevent the screw looseness. Assembly sequence is as follows:



3.2.4.2.7







Connect the coupling between the HP and the IP rotors.







Connect the coupling between the LP rotor and the generator







Tighten the connection bolts of the couplings







Measure the actual extension amount: for the HP and IP rotor coupling, it is 0.16-0.20mm. For the LP rotor and the generator, it is 0.20-0.25mm.



Checklist for moving blades Clean up the blades and impeller by sand blast, rubbing or high pressure water depending on the scaling on the blades. Cleaning inspection, precaution and quality standard.



3.2.4.2.8



a)



It is required that the cleaned blade should the original metallic gloss.



b)



If the cracks, looseness, inclination or deformation, etc. occurred to the blades, they should be treated or replaced. Check whether there are the flushing grooves or rupture on the blades of the final two stages, make the record.



c)



Check the blades at each stage with the small hammer of half pound or the copper bar for the looseness.



Rotor checking items a)



Take the chemical sample to analyze the rotor.



b)



No cracks or damages on the rotor. No damage, cracks or severe corrosion on the moving blades, band or blade root. The retaining pins on the blades of each stage should be tight without looseness.



c)



The blade frequency should be within the specified range.



d)



No cracks, corrosion or mechanical damages on the blades. No friction trace on Page 70 of 241



the moving or static components. No creepage on the high temperature blades. The balance block or bolts inside the balance holes should be tightened without looseness or sever damage caused by blowing. e） The bearing journal and the service surface of the thrust pads should be the thrust pads and the coupling end surface should be less than 0.2mm. The surface roughness is less than 0.02mm. The gland seal wobbling in axial are smooth without the pitting, grooves or traces. The deflection degree of direction is less than 0.025. The bearing journal ellipticity and the conicity should be less than 0.02mm. The main shaft deflection degree should not be higher than 0.03mm. f） No cracks on the coupling bolts. No broken threads or disordered threads. The bolts surfaces are smooth without burrs. The hardness is within the specified scope. g） Check the coupling bolts holes for burrs, damages or rust. Check the turning gear engagement. h)



Check all the gland seal teeth, gland seal grooves for the damages. Make the record well.



i)



Check the impeller balance blocks for the looseness.



J)



Check the LP rotor coupling bolts for the looseness.



k)



Take the following measures to deal with the common defects on the blades.



l)



1)



If there are cracks on the blade root, replace the blade.



2)



If the steam inlet or outlet edges of the blade are rolled, support them on the arc-shaped pad and flatten them with a small hammer. For the welded rupture, file it with the filer to make it smooth.



3)



If there are slight cracks on the blade outlet edge, repair it with the filer to make it smooth, or weld the cracks partially.



Before re-assemble the rotor, install the lower half blade carrier, the diaphragm, the lower half thrust bearing and all the lower half bearing pads first.



m) Lift up the rotor with the lifting equipment and pay attention to keep in good horizontal level. Then, put the rotor on the lower half bearing pads. CAUTIONS: Do not hit the fixed components or parts (such as nozzles, diaphragms.)during lifting up. 3.2.5



Maintaining Nozzles, Diaphragms and Blade Carriers



3.2.5.1



Maintenance procedure for the diaphragm or blade carrier



3.2.5.1.1



Diaphragm Carrier & Diaphragm Disassembly a)



Dismantle the upper half and the lower half blade carriers, the bolts on the diaphragm split surface, loosen the pins, and make the markings for the reassembly. Lift the upper half blade carrier and the upper half diaphragm in order. Check for the steam leakage traces on the split surface or the friction traces on the moving and static components, and make the record. Clean up or repair the screws on the diaphragms or the blade carriers based on the practical situation.



b)



Lift out the diaphragms one by one with the guide rod, hoist or overhead crane. Page 71 of 241



Lift and take away the lower half blade carrier. If the diaphragm and the blade carrier are fixed tightly on the casing, and is not movable. Tap the both surfaces of the diaphragm and the blade carrier respectively with the copper bar to remove the oxidized membrane. Then Lift the diaphragm or the blade carrier. Or Lift them while tap them with two screw rods and with the support of channel steam frame. Make the marking on the stuck part and treat it. Check the connection of suspending pins. c)



3.2.5.1.2



Put the diaphragms on the special support or the wood board. Put the bolts dismantled from the diaphragms or the blade carriers in the parts case and keep them well. Plug the holes appearing after the diaphragm or the blade carrier is removed.



Diaphragm Maintenance a)



Check the diaphragm guide vanes for the damages, the rolled edge, the looseness, the erosion or the poor combination. Carry out the sound checking with the small hammer tapping the blade. For the abnormal blades, take the further checking with the magnifier or coloring method. Check and clean up the nozzles. Check the guide vane ring for the cracks or deformation, remove the oxidized layer.



b)



Check the diaphragm outlet edge, especially the casting connection of the fixed blades and the forged diaphragm, for the cracks or detachment. Treat the cracks or chips of the static blades. File the chips with the filer to make it smooth. For the long crack, make a hole at the end to stop the crack extension. For the severely rolled edge, make the necessary heat adjustment. For the large chips, weld them.



c)



Check the suspending pins of the diaphragm or the blade carrier for the looseness.



d)



Check the fixed blades welded on both ends surface of the diaphragm split for the detachment, the cracks, the neglected place need to be welded, the damages, the rolled edge, the poor combination, and the corrosion.



e)



After the blade carrier or the diaphragm is removed, blast the both sides of the fixed blades with the special sand blaster until the metallic color appears, or clean up the diaphragms with the emery cloth to remove the rust.



f)



Check the connection of the diaphragm split and the blade carrier split. Put the diaphragms and the blade carriers outside the casing and support them reliably for the checking,



g)



Check and measure the axial clearance and the radial clearance of the diaphragm (generally, if the diaphragm deformation is not severe, don’t do this work.)



h)



Check the suspending pins supporting surface connection in the coloring method and verify if it is ≧60%.



I） Align the blade carrier and the diaphragm. 3.2.5.1.3



Blade Carrier and Diaphragm Assembly a)



Purge the diaphragm and the blade carrier with the compressed air.



b)



Purge the HP and IP steam inlet guide pipeline. Check the guide pipeline is clean, wrap it with the cloth and seal it.



Page 72 of 241



3.2.5.1.4.



c)



Apply the black lead powder to the diaphragm edge. Lift them and put them in the casing or the blade carriers.



d)



After the rotor installation, install the upper half blade carriers or the upper half diaphragm.



Check diaphragm and mid-split surface 1） Do as follows Clean the surface of upper and the lower diaphragms and the surface of blade carrier, put some red lead powder on one surface and put on the top diaphragm (remark: the diaphragm can be slightly suspended by traveling crane or guiding chain ).Move the diaphragm along the axial and radial direction slightly, Observe contact surface and measure the clearance by feeler gauge. 2） The contact area should be more than 75%, the split clearance of the H&IP diaphragm and blade carrier should be less than 0.05mm, and the split clearance of the LP diaphragm and blade carrier should be less than 0.10mm.



3.2.5.1.5



Measuring diaphragm axial and radial clearance 1)



2)



3.2.5.1.6



Axial clearance measurement a)



Suspend the diaphragm into the casing or blade carrier.



b)



Put a dial gauge on the casing with the pointer towards the diaphragm surface.



c)



Pry the shaft axially with a lever, the reading on the dial gauge is the diaphragm axial expansion clearance.



Measuring Radial Clearance a)



The radial expansion clearance of the lower diaphragm can be measured by lead wire pressing or soap pressing method. Put the lead block (δ=3mm) into the diaphragm slot and guiding slot, and suspend the lower diaphragm. Measure that the side notching supporting surface of the diaphragm should have no clearance (if there is clearance, rap at the diaphragm plane by red copper till the clearance disappears.), and then suspend the diaphragm out, measure the thickness of the pressing lead block, that is the radial expansion clearance of the lower diaphragm.



b)



The clearance between the longitudinal key at the bottom of the diaphragm and the slot bottom must be more than the radial expansion clearance of the diaphragm.



c)



The radial clearance measurement of the upper diaphragm is that hang the upper diaphragm and put it in the upper half casing or half blade carrier, measure the difference between the diaphragm split and the casing split, the measuring result minus the difference between the lower half diaphragm split and the casing split is the expansion clearance of the upper part of diaphragm. (Generally, it is 2-2.5mm).



Blade carrier and diaphragm alignment



3.2.5.1.6.1 According to concavity center of steam seal between HP-IP rotor and HP-IP casing, concavity center of the inner oil retainer of #3 and #4 bearing located between LP rotor and LP casing. 3.2.5.1.6.2 The adjustment of the diaphragm horizontal center can be performed by scraping and b welding repair of the longitudinal pins ina the lower half diaphragm. It is required that a



c



Page 73 of 241



total clearance of 0.04-0.08 mm on both side of longitudinal pins must be guaranteed after filing and welding repair. Otherwise,re-adjust it.



Fig. Finding the center of diaphragm 3.2.5.1.6.3 The diaphragm height can be adjusted by scraping the lower diaphragm lug and assembling or disassembling the gaskets. Pay attention to that reserve the clearance big enough for the lug expansion. For the details, see the table 11. The adjusting data for horizontal center is (a-b)／2. The adjusting data for higher and lower centers is determined by c-（a+b）



／2



If the horizontal center for the diaphragm adjustment is lower ( less than 0.3mm), it can be ensured by adjusting the height of the right and left side notching (suspending pin), and it is no need to file and weld the longitudinal pin of the diaphragm. Designed allowable center deviation



a-b



c-(a+b ）



±0.05



±0.025



±0.30



±0.15



±0.30



±0.15



To coaxial cavity of the ±0.10 gland seal.



±0.05



The concentricity with



±0.05



To oil concavities of #1 and #2 bearing pads. To the gland seal concavities of the HP and IP casing HP and IP rotor To the blade carrier concavities



±0.10



the diaphragm LP rotor



To the cavities



oil



baffle ±0.05



of #3 and #4 bearing pads



Page 74 of 241



±0.025



The concentricity with



±0.10



±0.05



±0.10



±0.05



LP gland seal The concentricity with the LP diaphragm



3.2.5.1.6.4 The method for finding the center point of diaphragm is shown in the figure. (Take concavity center pointer of steal seal on lower diaphragm or the concavity pointer of oil retainer as reference point.) Illustration for finding diaphragm center.



钢丝 千分尺测量



定位键



Steel wire Micrometer to measure



Positioning key



a)



Put the dummy shaft into the casings, the axial displacement is 70%, there is no scratch and burr.



d)



Each packing blocks of the bearing pad connects well.



e)



The packing iron block should be made of steel sheet, the packing blocks should not be less than 3 in number.



f)



Scrape slightly to the grinding crack at the bushing surface. When scraping, pay much attention to: scrape slightly, the scraping quantity should be small and wide, it is not allowed to scrape the slot that are both shallow and deep. If the scraping quantity is too large, the scrapper should be used alternatively, it is not allowed to scrape in the same direction. When inspecting the scraper, inspect the blade of the scraper.



g)



Smear test on the bearing pillow block and the groove joint surface of the bearings. Inspect the joint surface of the bearing iron cushion and the bearing tank groove, and the joint surface of the external sphere of the inner bearing and the internal sphere of the outer bearing, they should be connect uniformly. Their



Page 80 of 241



contact area should be over 70%. Pay attention to the screw of the iron cushion when overhaul. There should be 0.03~0.05mm clearance at the iron cushion at the lower part of the bearing before rotor is equipped. 3.2.7.2.1.2 Bearing measurement 1)



2)



Measuring top clearance of elliptical bearing. a)



Clean the journal and the upper bearing pad. Put two lead wires around the bearing pad along with the direction of the shaft. The length of the wires should be from 0.5mm to 0.70mm, while the diameter is 0.50mm longer than the bottom clearance. When putting the wires, the slot in the middle of the upper bearing pad should be kept away from.



b)



Cover the upper half bearing pad; tighten the screws at the joint surface.



c)



Loosen the screws at the joint surface, hang up the bearing pad.



d)



Take out the lead wire, measure its thickness by using micrometer, and record the data.



e)



The bearing pad bottom clearance is 1‰～1.5‰ of the journal diameter.



Bearing clearance measurement Measure it by using the feeler at the four corners of the bearing pad joint surface. The depth the feeler leaf put in the opening of the shoe should be 1/10 ～1/12 of the diameter of the journal. There should be less than 3 leaves of the feeler, at this time; the thickness of the feeler is just the clearance at two sides of the bearing pad. It is generally required that the side clearance of bearing pad is 1.5‰～2‰ of the journal diameter.



3)



Bearing tension measurement a)



After the bearing pads are covered, clean up the joint surface of the baring cover and the oil chest of the bearing pedestal.



b)



According to the value of the tightening force, a lead wire with 0.30mm diameter should be put at the joint surface of the upper bearing pad and the upper part of the bearing cover. Put four gaskets with the same thickness symmetrically at the joint surface of the bearing pedestal. 0.30~0.40mm stainless steel or the copper strip is commonly used. It can also be measured by putting a lead wire instead of gaskets at the joint surface of the bearing pedestal.



c)



Cover the upper bearing, loosen the screw at the joint surface of the bearing cover, hang out the bearing cover, and measure the thickness of the lead wire. The sequence of measuring is usually from the front to the rear and then the left and at last right. The tightening force value is the average thickness of the gasket minus the average thickness of the lead wire. If the result is a negative value, it should be the gas value; otherwise, it is the tightening force



d)



Commonly, the adjustment of the bearing tightening force value is through the adjustment of the bearing pillow gasket at the top of the upper bearing pad. However, sometimes it is achieved by adjusting the one side adjusting gasket at the joint surface of the bearing cover. The tightening force of the



Page 81 of 241



spherical bearing pad is ±0.03mm. As for the situation like the temperature increase of the bearing cover is large during operation, the tightening force should be increased. But the tightening force value in cool state should be ≤0.25mm. 4)



Bearing housing oil baffle clearance measurement a)



Measure all the adjustable clearances with the feeler gauge in order. If the clearance is big, hit the copper teeth to extend the teeth which will narrow the clearance. If the clearance of upper part and the lower part is big, it can be reduced by scraping the oil baffle connective surface. If it is ineffective, the copper teeth must be replaced.



b ) The floating oil baffle clearance can meet the requirements on each part by means of mechanical processing. If the horizontal clearance meets the requirement while the vertical clearance is too big, scrape the connective surface. If the horizontal clearance is over the limit, the oil baffle must be replaced. 5)



Jacking oil bag measurement Check the depth of each bearing pad jacking oil bag. Put the straight ruler on the babbit metal, the depth of oil bag should meet the standard (0.35-0.50 mm).



3.2.7.2.1.3



Oil baffle maintenance 1)



General previsions on oil baffle installation



2)



a)



Check the oil baffle cover and oil teeth, there should be no burrs, foreign matters, or cracks, the oil filter with 5 holes in one square inch should not be obstructed.



b)



When install the oil baffle, apply the sealing glue to the vertical flange. Adjust the clearance with adjusting screws, tighten the bolts with torque spanner.



c)



The oil baffles are fixed firmly, the splits are connected tightly, the maximum clearance is ≤0.10mm. The staggered openings are not allowed.



d)



The oil baffle edge thickness is generally 0.10-0.20mm. If necessary, thin the edge. The inclined opening should be made outside, The oil baffle exhaust opening should be toward the oil chamber.



Requirements for oil baffle clearance For the oil baffles on bearing pad and bearing pedestal: the upper clearance is 0.20～0.25mm, the horizontal clearance is 0.10～0.20 mm, the lower clearance is 0.05-0.10mm.



3.2.7.2.2



Maintenance for #1 and #2 Kingsbury thrust bearing (key point) 1)



Bearing pad disassembly a)



Remove I & C elements on bearing cover. Draw out the vertical pins. Remove the bolts on the horizontal connection surface. Hang out the bearing cover.



b)



Remove the bolts on the bearing pillow and the bearing pad connection surface. Hang out the bearing pillow and the bearing pad. Record the bearing pad top clearance and the bearing spherical surface clearance.



c)



There should be the fixed numbers on the tightening bolts of bearing pad pillow and the bearing pad. Put the bolts on the assigned place. Page 82 of 241



2)



3)



Bearing pad checking a)



Paint the connection surface of packing blocks and the cavity of bearing pedestal.



b)



Install the lower bearing pad. Paint and check the connection surface of spherical bearing pad and the bearing pillow; don’t grind it. If the paint area exceeds 10mm, negotiate it with the Shanghai Turbine Company, replace the whole set of the packing blocks.



c)



Install the packing block. Check the displacement of each inclinable packing block with the filler gauge and the dial gauges.



d)



Measure the paralleling degree



e)



Check the bearing pad top clearance. For the inclinable bearing pad, the bearing pad clearance is generally 1.2‰-2‰ of the journal diameter, which can be adjusted through adding or reducing the gasket.



f)



The journal parallelism can not be changed in the process of reassembly. Quality standard a)



Requirements on bearing parallelism Check the parallelism of the bearing pad and the shaft with the micrometer and filler gauge on the right bearing pad and the four points around the journal. The parallelism should meet the following requirements. a: front right b: rear right C. front left d: rear left a+ b-(c+d)/2≤0.025mm



b) Table



Clearance data for all the bearings



Clearance data for all the bearings Unit: mm



No.



Bearing pad size (diameter X Top clearance length)



Bearing pad Oil baffle cover clearance tightening force



1



φ360×230



0.60+0.08



0.025—0.10



0.45±0.05



2



φ360×270



0.60+0.10



0.025—0.10



0.45±0.05



3.2.7.2.3



Thrust bearing checking and measurement 1)



Maintenance contents a)



The bearing journal and thrust pad and disc surfaces should be smooth without rubbing trace or damage.



b)



Remove #2 bearing cover. Remove the bolts on the horizontal surface of thrust pad cover. Jack the upper half thrust pad by 10-20mm with the jacking screws, then, hang it out. Remove the bolts on the bearing pillow horizontal Page 83 of 241



connection surface, draw out the pins, and hang out the upper half pillow with the special hanging ring. Remove the thrust pads, contact the I&C personnel to remove the temperature measuring points.



2)



c)



Take the two halves oil sealing rings (outlet oil and inlet oil), and draw out the positive and negative thrust pads of the lower half, keep them well. Check the thrust pad Babbit, they should be smooth without rubbing trace, detachment, abrasion, overheat melt and other mechanical damage. The service traces on the thrust pads should be even. The outer and inner edges and the pin holes should be without rubbing trace, and so is the supporting line for swing. The assembled thrust pads can swing freely along with the swing line.



d)



Measure the thickness of thrust pad and compare it with the original record. The difference should be significantly slight. The differences among different thrust pads should be less than 0.02mm, if not, find out the reason and deal with it. The wedge-shaped oil inlet area should be in accordance with the drawing. The inlet clearance is approximately 0.1. The thrust pad babbit thickness is generally 1.5±0.1mm.



e)



Check the oil sealing ring connection surface, the clearance should be 75%. Checking should be carried out in the dry rubbing method to avoid the illusion.



Measure and adjust the axial clearance of thrust bearing a） Cover the thrust bearing which is assembled, hit the inner pins, tighten screws on the horizontal connection surface.



3)



the



b)



Install two dial gauges with one pointing at the basis end surface and the other one pointing at the thrust cover to measure the rotor displacement and the bearing pillow displacement.



c)



Push the rotor to the limit position with two jacks or in other method. Observe the maximum and minimum indication of the dial gauges. The difference value of both dial gauges are the displacement, which minus the bearing pad displacement is thrust clearance. It is generally required that the thrust clearance is 0.40-0.45, the bearing pad displacement is 75%.



c)



In general, the thrust clearance is 0.40~0.45. The pad displacement is 3000 L



Flow



～200 kw



Power consumption



Injector: Injector is composed of Oil Feed Injector (I) and Lubricating Oil Feed Injector (II). Injector nozzle is multiport nozzle. There is a damper which prevents oil entering in injector chest. Parameters are as follows:



Name



Outlet Pressure



Outlet Flow



0.21 Mpa



3447 L/min



0.31 MPa



3600 L/min



） Oil Feed Injector(I)



Lubricating Oil Feed Injector(II)



Centralized assembling oil tank: The oil tank is assembled in a centralized tank. Most equipment in lubricant system are distributed together in the oil tank, such as AC lube-oil pump, DC emergency oil



Page 114 of 241



pump, single-disc check valve, double-disc check valve, oil-flue separator, oil level indicator, electric heater, oil overflow valve and internal pipeline. In this way, operation and monitoring are facilitated and allocation of power plant is simplified to prevent fire. Volume of oil tank in normal operation is 30.6 m3. 3.3.1.3



Lube-oil pump 1)



AC lube-oil pump This oil pump is a centrifugal pump of single stage, single suction, vertical, and motor driven. The model is 150LY-35-4. On conditions of unit startup, shutdown and lube-oil pressure is less than 0.05MPa, supply sufficient lube-oil for bearings, turning gear and jack device. The driving motor is an explosion resistant one. The featured data is shown in following table: Pump lift



35 m



Flow



3000 L/min



Rotation speed



2950 r/min



Power



AC 380V



Motor power



55 kw



AC lube-oil pump is a vertical centrifugal pump. Motor is connected with the pump by fixed coupling. Pump is submerged beneath lube-oil in the tank. Usually when oil pressure of bearing decreases down to 0.082MPa, activate the pump.



2)



DC emergency oil pump This oil pump is a centrifugal pump of single stage, single suction and vertical. The model is 125LY-23-4. It is only used when turbine units are out of service. When lube-oil pressure is lower than 0.04MPa or when AC power is lost, lubricant is supplied for all bearings to meet requirements of turbine unit safety shutdown. The driving motor is DC motor. The featured data is shown in following table: Pump lift



2600 L/min



Rotation 3000 speed r/min



DC 220V



Motor power The DC lube-oil pump is a vertical centrifugal pump. It is the standby pump for AC lube-oil pump. When AC power is cut off or when lube-oil pump of bearing fails, start up DC lube-oil pump to supply oil for bearings. Only when bearing oil pressure decreases down to 0.069-0.076MPa is this pump activated. Both structure and maintenance procedure of AC lube-oil pump (BOP) and DC lube-oil pump (EOP) are same. 3.3.1.4



HP startup oil pump HP pump is AC gear pump. It is connected to motor by fixed coupling on one pubic classis, and then installed horizontally upon round cover board at the top of oil tank. It is composed of drive and driven gears, mechanical seal, and housing. Pump end is sealed by mechanical seal. Outlet pressure oil of HP pump only serves for mechanical overspeed disengagement and manual disengaging device in front bearing box. It Page 115 of 241



also serves as standby oil source for generator hydrogen seal. This pump is only activated when main oil pump outlet pressure cannot meet requirements during startup or shutdown of the unit. Two overflow valves are equipped along outlet pipe of pump to adjust outlet oil pressure. 3.3.1.5



Fume exhaust fan Two fume exhaust fans are equipped on top cover of oil tank to absorb oil vapor in lubricant tank and discharge it. In this way, oil smoke ingress into turbine plant can be prevented, and certain vacuum in connection space along bearing seat, oil tank and sleeve. In normal case, one is in operation while the other one serves as standby.



3.3.1.6



Oil cooler The oil cooler is used to cool down lubricating oil, maintaining temperature of bearing inlet oil within range of 43℃-49℃.Two coolers are equipped in this unit. In normal operation, one is running while the other one serves as standby. One switch valve is used to switch the two coolers. There are main components and parts in each cooler, such as housing, water chamber, returning chamber, pipeline, water inlet tube plate, and water returning tube plate.



3.3.1.7



Jacking oil pump Jacking oil pump is firstly activated before unit turning gear for startup. Bearing journal is removed from bearing pad by HP oil to eliminate dry friction between journal and pad. At the same time, startup torque of turning gear can be decreased and motor power of turning gear is also decreased. Jacking oil system is composed of plunger oil pump, magnetic filter of oil inlet pipe, inlet cartridge, plunger valve, vacuum alarming switch, plate type ball valve, pressure governing valve and terminal box of jacking oil.



3.3.1.7



Maintenance procedures and technical standards of lubricating oil system equipment



3.3.1.7.1



Main oil tank



3.3.1.7.1.1 Maintenance procedure of main oil tank (1)



Open oil discharging valve on oil tank, and drain residual oil in the tank thoroughly;



(2)



Open upper cover on top of strainer and access door to pick out strainer to check. If there is damage, re-weld or change;



(3)



Check interior of oil tank by chemical personnel. Enter the tank from access door to clean up interior. Firstly plug the oil discharging port at bottom of tank. Use white cloth, kerosene and flour dough to clean. With approval from chemical personnel, reassemble the tank. Parts where are easily corroded should be treated with corrosion resistant methods;



(4)



Check oil filler and oil level injector;



(5)



Pick out oil drainer cover plate to check whether there are things being left in tank. Put strainer back in tank and fasten the cover plate and man hole cover plate;



(6)



Check fume exhaust fan;



Page 116 of 241



(7)



Close oil discharging valve on oil tank and emergency oil discharging valve. Fill oil in tank until oil level reaches regulated value.



3.3.1.7.1.2 Technical standards include: (1)



Cleaning of oil tank inner wall: clean with no corrosion, oil stain and meet requirements of chemical supervisor;



(2)



Checking and cleaning strainer: clean with no damage;



(3)



Checking pipeline and bolts in tank: no wear and no loose



3.3.1.7.2



Main oil pump



3.3.1.7.2.1 Maintenance steps (1)



Disassemble upper cover of front tank (be careful when disassembling I&C related circuit parts).



(2)



Remove rotor extending shaft out from HP rotor. Use dial meter to measure flange eccentricity connecting extending shaft and HP rotor, which can serve as reference when reassembling. Remove connecting bolts between extending shaft and HP rotor and make marks on each bolt.



(3)



Take apart all oil pipelines at upper cover of main oil pump and emergency tripper, and mark them respectively.



(4)



Remove connecting bolts on main oil pump centering surface and lift out upper cover of the pump.



(5)



Use clearance ruler to measure clearances between four oil seal rings that are located in front and rear of the pump.



(6)



Take out four oil seal rings to check: surface of tungsten has to be smooth, complete with no detachment, crack and wear.



(7)



Lift out rotor extending shaft and put it on a bracket.



(8)



Use special spanner to remove the speed governing mechanism to check: surface should have no wear and crack. Inner oil flows freely with no blockage.



(9)



Take apart impellers, keys and lined gaskets to check: surface has to be no wear and crack. Inner oil flow way should be unobstructed. Interface of impeller and oil seal ring has to be no wear, crack and not loose.



(10)



Check extending shaft surface of rotor and measure eccentricity of the



Page 117 of 241



shaft. (11)



Reassemble all parts in accordance with reverse order of disassembly process after they are cleaned up thoroughly.



3.3.1.7.2.2 Technical standard (1)



Surface of tungsten (of oil seal ring) has to be smooth and complete with no detachment, crack and wear. Interface is even.



(2)



Clearances of four oil seal rings have to meet following requirements:







Radial clearance between rear oil seal ring and rotor extending shaft: 0.05mm-0.15mm







Axial clearance between rear oil seal ring and main oil pump housing: 0.05mm-0.13mm







Radial clearance between rear oil seal ring and impeller: 0.05mm0.15mm







Axial clearance between rear oil seal ring and main oil pump housing: 0.05mm-0.13mm







Radial clearance between front oil seal ring 0.15mm







Axial clearance between front oil seal ring and main oil pump housing: 0.05mm-0.13mm







Radial clearance between front oil seal ring and speed governing mechanism: 0.05mm-0.15mm







Axial clearance between front oil seal ring and main oil pump housing: 0.05mm-0.13mm



(3)



Surface of speed governing mechanism has to be no wear and crack. Inner oil flow way has to be unobstructed.



(4)



Surface of impeller, keys, lining and wear resistant rings has to be no wear and crack. Regarding wear resistant rings, they have to be firm with no wear or crack. Impeller, shaft and pins have to match properly with no loose parts. When impeller is replaced with new one, stationary balance has to be calibrated again.



(5)



Horizontal interface of pump housing has to be tight. Bolt has to be screwed on for two thirds of its total length after it is cleaned up. Use clearance ruler of 0.02mm to measure the interface. It has to be stopped outside. Interface has to be complete. No gasket is used.



(6)



Bending of pump shaft is ≤0.02mm while deflection of impeller is ≤0.04mm.



3.3.1.7.3



AC lubricating oil pump and DC lubricating oil pump



3.3.1.7.3.1 Maintenance steps



Page 118 of 241



and impeller: 0.05mm-



(1)



Inform electrical personnel to disconnect motor wiring.



(2)



Remove connecting bolts between motor and pump housing and coupling bolts and keep them well.



(3)



Enter main oil tank. Remove oil connection pipeline from the pump. Remove bolts on outlet flange. Count all disassembled bolts and keep them well. Take them out of tank.



(4)



Use hoister to lift out the motor and pump body and place them at designated maintenance site.



(5)



Measure axial run-out of shaft and make record. Remove lubricating oil pipe of pump bearing and seal pipe port.



(6)



Take apart coupling, bearing cover, shaft nuts, cartridge at oil inlet, oil pipe short sections, and impeller bolts. Remove short sections and impellers.



(7)



Use copper rod to knock the pump shaft gently form motor side to pump side, and pick out pump shaft.



(8)



Thoroughly check and clean all parts. Measure clearance between different parts. Reassemble in accordance with reverse order of disassembly steps.



3.3.1.7.3.2 Technical standards (1) Clearance between impeller and seal ring: 0.12-0.20mm. (2) Axial displacement of pump is 3-5mm. (3) Pump shaft should be smooth, no galling, and not bent. Impeller should be complete with no crack and wear. (4) All bearings should be easy to operate without blockage and loosing defects. If there are, replace new parts. After pump is reassembled, it should be easily operated manually with no blockage. Axial displacement should be same with that of previous value before repair. (5) Pump shaft bentness is ≤0.21mm while impeller deflection is ≤0.04mm. (6) Centering: surface is ≤0.05mm while end face deviation is ≤ 0.04mm. 3.3.1.7.4



HP startup oil pump



3.3.1.7.4.1 Maintenance steps



(1)



Contact electrical personnel and disconnect motor wiring.



(2)



Remove outlet pressure gauge, outlet flange blots and coupling bolts. Wrap each oil ports.



(3)



Lift pump to maintenance location by hoister and then disassemble oil pump.



(4)



Disassemble shaft end cover and mechanical seal. Gently pick out rotating and stationary rings as well as spring. Do not damage rotating Page 119 of 241



ring. Check sealing surface interface of rotating ring and stationary ring. (5)



Remove pump end. Mark on main driving shaft and take out the driving shaft.



(6)



Thoroughly check and clean each part. Measure clearance between different parts and make records.



(7)



Reassemble in accordance with reverse order of disassembly steps.



3.3.1.7.4.2 Technical standards (1) Sealing surface of mechanical seal rotating ring and stationary ring should be smooth with no defect like scratching, wear, and crack. Use red lead powder to grind the contact surface of two rings to maintain coverage area is above 90%. Spring should have no deformation, distortion or rupture. (2) Engagement of drive and driven gear should be complete without any defect like loose or deflection. Rotation should be easy. Engagement clearance meets relevant standards. (3) Centering: gap is ≤0.04mm while end face deviation is ≤0.05mm. 3.3.1.7.5



Oil cooler and diverting valve



3.3.1.7.5.1 Technical standards of oil cooler



(1)



Open oil discharging valve at bottom of oil cooler as well as water discharging valve to drain residual oil and water completely.



(2)



Remove flange bolts of cooling water inlet and outlet pipes and also the flange bolts of vent pipe at water side.



(3)



Remove connecting bolts on returning chamber and housing and take out sealing space ring and O ring.



(4)



Remove upper water chamber cover and bolts and lift out water chamber to maintenance site.



(5)



Use hoister to lift out cooler cartridge and place it in a special heater. Use heated trisodium phosphate (TSP) to boiler and clean it for 2 hours. Content of TSP is 5-10%. When this process is finished, lift it out and clean up with clean water.



(6)



Contact chemical personnel to prepare acid solution to carry out acid washing to cooler cartridge. After it meets requirements, use TSP solution to boil and clean for 1 hour. Content of TSP solution is 2-5%. Then lift it out. Use softened water to clean it up. Use white cloth to wipe the diaphragm until there is no stain on cloth. Use compressed air to dry it.



(7)



It has to be accepted by chemical department. Surface of copper pipe should be clean without crack and corrosion. No defect like drop-off or flaking-off or scaling (on surface of copper pipe) is permitted.



(8)



Change oil in lower water chamber and O ring in water side. After Page 120 of 241



requirements are met, reassemble the cooler in reverse order of disassembly steps. Do not assemble the upper cover at this point. (9)



Activate lubricating oil pump. Check cooper pipe of oil cooler. If there is leakage, use red copper plugs to block two ends of the leaking pipe until requirements are met.



(10)



Re-assemble the upper cover and change O-ring in oil-water side. Clean up maintenance site.



3.3.1.7.5.2 Technical standards of oil cooler diverting valve



(1)



Remove plug at bottom of oil inlet chamber of diverting valve and drain residual oil in valve thoroughly.



(2)



Remove bolts connecting oil inlet chamber and valve body, and then take apart oil inlet chamber of diverting valve.



(3)



Remove cotter pin, specially made gasket and nuts that fix valve disc at oil inlet side of diverting valve. Disassemble the valve disc at oil inlet side of diverting valve.



(4)



Remove handle and hand wheel of diverting valve, as well as the gasket beneath hand wheel, sleeve, and O ring.



(5)



Loosen flange bolts on oil outlet chamber of diverting valve and take out flange and sleeve.



(6)



Lift out central shaft and valve disc of oil outlet chamber.



(7)



Check valve discs of oil inlet and outlet chambers.



(8)



Check sealing rings between sleeve and central shaft and between upper flange and sleeve.



(9)



Clean up inlet and outlet oil chambers and valve inner wall and check for corrosion conditions.



3.3.1.7.5.3 Technical standards



(1)



Inner wall of oil cooler copper pipe has to be clean without water scaling.



(2)



Surface of copper pipe has to be clean without oil stain.



(3)



Result after water side test of oil cooler has to meet 0.6MPa while testing period is 15 min. Result after oil side test of oil cooler has to meet 0.4MPa while testing period is 15min.



(4)



Strainer of oil cooler has to be clean without damage.



(5)



Sealing surface of diverting valve disc has to be complete with no crack. Sealing line has to be continuous without interruption. Contact area of valve disc and valve body sealing surface is not Page 121 of 241



less than 85% while partial clearance is less than 0.02mm. (6)



Radial clearance between valve disc and valve body is 1.5-2mm.



(7)



Inner wall of valve body is clean with no corrosion.



3.3.1.7.6



Jacking oil pump



3.3.1.7.6.1 Maintenance procedure



(1)



De-energize motor and disconnect wires. Close outlet and inlet oil valves. Disassemble all pipe ports and seal them.



(2)



Loosen coupling bolts on motor.



(3)



Remove coupling end flange and take out O ring.



(4)



Loosen bolts connecting pump body and pump housing and take out body. Remove buffer ring of ball bearing and then the bearing.



(5)



Take out the oil distribution disc, pump side end cover and then take out bearing.



(6)



Take out returning disc, centering ball, plunger, inner bushing and spring outer bushing.



(7)



Measure clearances at each part and make records.



(8)



Check thoroughly and clean all parts. Reassemble in accordance with reverse order of disassembly steps.



3.3.1.7.6.2 Technical standards



3.3.2



(1)



Surface of plunger has to be smooth without single side wear. It matches with casing properly without loose or blockage. Intermediate oil hole is unobstructed.



(2)



There is no wear between returning disc and sliding block and no galling on contact surface. Surface of centering ball is smooth with no wear.



(3)



There is no galling or wear on contact surface between inner/outer bushing and oil distribution disc. It matches with housing perfectly without loose part. Spring is in good state without deformation and crack.



(4)



There is no deterioration of O-ring. Good performance of Bearings, perfect clearance without looseness. Surface of driving shaft is smooth and not bent at all.



(5)



Clearance between different parts accord with standards and requirements.



Sealing oil system of generator



Page 122 of 241



3.3.2.1



General Sealing oil system aims to supply demanded pressure oil continuously for generator sealing pad to seal hydrogen in the generator. The sealing oil system in this unit uses double-flow ring sealing pad to seal part of rotor that extends out of generator end cover. This is to prevent the pressure gas in generator overflowing along the axis. Sealing oil of generator is supplied to two ring oil distribution cells that are located on sealing pad from air side and hydrogen side in two ways. Oil flows through clearance between sealing pad inner shaft and rotor along the rotor shaft and overflows afterwards. As long as pressure of sealing oil is higher than that of gas in generator, the gas will not overflow. Oil fed at hydrogen side flows through clearance between axis and sealing pad into hydrogen side and finally enters bubble eliminating tank. Oil fed at air side flows through clearance between axis and sealing pad into bearing side and finally enters return oil sealing tank at air side together with bearing return oil. In this way air and humid gas are prevented from entering into generator interior. Main equipment in generator sealing oil system includes sealing oil pump, hydrogen side return oil sealing tank, bubble eliminating tank, oil cooler, differential pressure valve, balance valve, oil filter, fume exhaust fan, and hydrogen side return oil control panel. Sealing oil pump is used to supply two independent circulating sealing oil sources for sealing pad. The system contains four pumps which are respectively hydrogen side AC main oil pump, hydrogen side DC standby oil pump, air side AC main oil pump and air side DC standby pump. All these pumps are screw rod type constant current pumps. In bubble eliminating tank, air in oil from sealing pad hydrogen side expands and flows out. Bubble eliminating tank also prevents sealing oil entering generator. After return oil flows into air side return oil sealing tank, most of it returns to main oil tank through U shape pipe, and one part is transported into air side sealing oil circuit by oil pump as oil source for air side sealing oil pump. Return oil sealing tank at air side also prevents gas in generator flows into main oil tank together with sealing oil. Two fume exhaust fans and one vacuum pressure gauge are located at top of return oil sealing tank at air side, to maintain negative pressure of the tank (-500 － -250Pa). Function of differential pressure valve and balance valve is to drive valve core to move upwards and downwards by difference variation of input pressure signal. It changes opening height of valve and adjusts oil pressure in further way. With adjustment of differential pressure valve, sealing oil pressure at air side is kept0.056 MPa higher than air pressure in generator. With balance valve adjustment, air side sealing oil pressure in sealing pad is kept 1.5KPa higher than sealing oil pressure at hydrogen side. Page 123 of 241



Oil control tank at hydrogen side is oil storage tank for hydrogen side oil circuit. It consists of tank body, oil make-up valve, oil discharge valve, oil level indicator and low level alarm controller. During operation, certain oil level is maintained by oil make-up valve and oil discharge valve that are controlled by two floating balls. In addition, oil cooler and oil filter are installed both at hydrogen side and air side to adjust oil temperature and separate contaminant in oil. Oil filter is of self-cleaning and doctor-bar structure. It is installed in oil admission pipe. The advantage lies in high filtration precision and convenient removal of dust in filter element during operation. Floating oil of sealing pad for air side



Air side sealing oil inlet



H2 side sealing oil inlet



Structure of double flow ring sealing pad Double flow ring sealing pad



Sealing pad bracket



Generator main bearing



Labyrinth sealing ring



Air side ring clearance Centering line of generator rotating shaft



H2 side ring clearance



Air side sealing out drain (Mixed with bearing return oil) H2 side sealing oil drain



双流环密封瓦结构图 3.3.2.2



Maintenance procedure and technical standards



Maintenance period



Overhaul period: once every three years Repair period: once every half year



Overhaul items



(1)



Disassembly maintenance of sealing oil pump



(2)



Disassembly maintenance of oil-gas pressure difference control valve



(3)



Disassembly maintenance of balance



Page 124 of 241



Maintenance



valve



items



(4)



Cleaning of oil cooler



(5)



Cleaning of strainer



(6)



Maintenance of pipelines and valves



Repair



(1)



Cleaning of strainer



items



(2)



Cleaning of oil cooler



(3)



Trouble shooting of equipment during operation



3.3.2.3



Differential pressure governing valve



3.3.2.3.1



Structure and function description Pressure difference valve is located along air side sealing oil pipeline to control air side oil pressure. The purpose is to maintain pressure of air side oil pressure and hydrogen pressure in generator at 0.05±0.02Mpa. Valve body is of dual seat structure, upper part of which is measuring mechanism. Main parts are piston and counterbalance block. They are connected to valve stem through valve core. When hydrogen pressure in generator increases, thrust force of piston upper end face is higher than that of lower end face, piston moves downwards and opening of valve increases. In this case, excessive flow increases while sealing oil pressure at air side rises up. When thrust force at piston two ends reaches their balance, piston ceases moving and oil-hydrogen pressure is maintained in this way. Specific structure refers to Fig. 9. Because pressure valve is gravity structured, it has to be installed vertically.



3.3.2.3.2



Maintenance technology



a)



Remove flange connecting differential pressure governing valve and the system. Lift the valve to designated maintenance site.



b)



Open hydrogen side vent port to discharge residual gas.



c)



Loosen bolts connecting upper gas chamber of differential pressure governing valve and valve body, and take out housing of gas chamber.



d)



Make a record about locations of pressure governing spanner and adjusting nuts before loosening spanner and nuts.



e)



Take out air side corrugated pipe and sealing corrugate pipe to check. Immerse it in kerosene or carry out pressure tests to check whether there is leakage on corrugated pipe. The pipe should have no deformation and leakage.



f)



Remove bolts connecting valve stem and spring holder to check spring and measure flexible length of spring.



g)



Remove bolts connecting lower oil admission valve of differential pressure governing valve and valve housing. Take out lower oil admission valve.



Page 125 of 241



h)



Remove bottom board of oil admission valve and take out valve stem to check.



i)



Check interior of oil admission lower section and sealing surface of valve base.



j)



Reassemble in reverse order of disassembly sequence after parts are cleaned up.



3.3.2.3.3



Quality standards a)



There is no deformation, rupture or corrosion on spring.



b)



There is no wear on valve stem and it is not bent. Sealing surface is complete with no crack or corrosion. Sealing line is continuous without interruption.



c)



There is no crack on valve body and no corrosion on valve interior. Sealing surface of valve seat is complete without crack or corrosion. Sealing line is continuous without interruption.



d)



Radial clearance between piston and housing is 0.06-0.08mm. Sliding of piston is easy without blockage. Check valve core for crack or corrosion. Apply red lead powder and check valve core and valve seat. Sealing line should be a round circle and continuous.



e)



Reassemble in reverse order of disassembly sequence. Make sure piston works easily without any blockage. Centering of valve has to reach a standard that is center line is in parallel with horizontal line.



3.3.2.4



Pressure balance valve



3.3.2.4.1



Structure and function description Oil pressure balance valve aims to automatically control hydrogen side sealing oil pressure of two flow ring sealing pad and balance it with air side sealing oil pressure. Acted by the oil pressure between hydrogen side and air side of seal pad, the balance valve forms axial displacement and changes the opening degree of valve core. As a result, oil pressure at seal pad hydrogen side is adjusted. The balance valve is composed of valve body, valve stem, piston and bi-tapering valve core.



3.3.2.4.2



Maintenance technology (1)



Remove bolts connecting pressure balance valve and system as well as oil pipelines. Lift differential pressure governing valve to designated maintenance site.



(2)



Remove bolts on blind cover of balance valve, and open blind



Page 126 of 241



cover. (3)



Loosen bolts on upper and lower seat rings and take out rings. Disassemble inner part of valve and check.



(4)



Disassemble bolts connecting piston oil cylinder and valve body, and then separate the cylinder and valve body.



(5)



Loosen bolts on cylinder lower cover and take out the cover.



(6)



Measure locations of adjusting bolts. Loosen bolts after clamping nuts are loosened.



(7)



Loosen bolts connection piston oil cylinder cover and cylinder to take out the cover. Pay attention to tension of spring during disassembly process. Had better use lengthened bolts.



(8)



Take out spring adjusting block, piston spring, spring and piton nuts to check.



(9)



Take out piston to check. Measure radial clearance between piston and oil cylinder.



(10)



Remove fixing nuts on valve stem and take out stem to check. There should be no wear on stem and stem is not bent.



(11)



Clean up and check inner wall of oil cylinder.



(12)



Reassemble in reverse order of disassembly sequence after parts are cleaned up.



3.3.2.4.3



Quality standards



(1)



Sealing surface of inner valve is complete without crack or corrosion. Sealing line is continuous without interruption.



(2)



There is no deformation, rapture or corrosion.



(3)



Valve stem is not bent or worn.



(4)



There is no crack or inner corrosion on valve body. Sealing surface of valve seat is complete without crack or corrosion. Sealing line is continuous without interruption.



(5)



Radial clearance between piton and housing has to be maintained within 0.06-0.08mm. It has to move easily without blockage. Check valve core for any crack or corrosion. Apply a coat of red lead powder to check whether sealing line of valve core and seat is continuous and even or not.



(6)



Reassemble in reverse order of disassembly sequence. Carefully adjust the piton to make it work easily.



3.3.2.5



Sealing oil pump Page 127 of 241



3.3.2.5.1



System overview: The sealing oil system is used to guarantee the continuous pressurized oil supply required by the sealing pads of the generator to seal in the hydrogen. Bi-directional circulation sealing device is installed on both ends of the generator, and its sealing oil supply system is composed of two independent and interrelated sealing oil lines. The air-side oil line has two AC pumps and one DC pump. The required pressure of oil is regulated by oil-gas pressure regulator. The oil enters into hydrogen-side of the sealing pad after the oil pump pressurizes the oil. The hydrogen-side oil line has two AC oil pumps, two oil coolers, two balancing valves and one sealing oil tank. For convenient operation and maintenance, there are three parts in sealing oil system: sealing oil supply station, sealing oil tank and sealing oil pressure regulating station.



3.3.2.5.2



3.3.2.5.3



Maintenance cycle: A



Major overhaul cycle: every three years;



B



Minor overhaul cycle: half a year;



Maintenance items A



Major overhaul items: 1. Overhaul the sealing oil pump; 2. Overhaul the oil-gas pressure regulator; 3. Overhaul the balancing valve; 4. Clean the oil cooler; 5. Clean the filter; 6, Overhaul the tube valve



B



Minor repair items: 1. Clean the filter; 2. Clean the oil cooler; 3. Eliminate the defects during the operation of the equipment.



3.3.2.5.4



Maintenance process: a. Remove the pump inlet and outlet flange bolts and foundation bolts. Unlock the pump coupling bolts. Wrap up the adjusting gasket under the foundation and properly mark and store the items. b. Remove the vertical contact bolts of pump shell and cantilever shell. Remove the cantilever shell. Loosen the impeller tip on the shaft end. Remove the impeller to



Page 128 of 241



check for cracks, erosion and wear. c. Loosen the mechanical sealing end cover. Disassemble the coupling bolts of pump cover and shaft. Remove the O seal ring to check its elasticity, aging and wear. d. Take out the mechanical seal and shaft sleeve. The mechanical seal should meet the quality standard. Rotating direction of the spring should be the same as the rotating direction and there should be no looseness between shaft sleeve and shaft. e. Take out, check and clean the bearings in front or and behind the gears. Reassembly should be conducted in reverse order. 3.3.2.5.5



Quality standards 1)



The sealing surface between the stationary ring and moving ring of the mechanical sealing device should be smooth without wear and scratches. The device should be rubbed with metallurgical sandpaper. Apply red lead powder. The contact area should be more than 80%.



2)



The mesh marks of drive and driven gears should be uniform and without apparent wear. The bearings should rotate freely without jamming and looseness.



3)



The clearance of each part should meet the requirements.



4)



The pump should work freely after it has been reassembled. The run-out should be the same as before repair.



3.3.3



Feedwater pump



3.3.3.1



It is mainly used to feed the low pressure feedwater that comes from the deaerator into the boiler. Before entering the boiler, the water is pressurized and heated by the HP heater. FK6D32 feedwater pump



Name



Model



TMCR



CHTC4∕7



Type



Horizontal drum core



Conveyed medium



Boiler feedwater



6 Level 347



Page 129 of 241



Outlet flow



Inlet pressure



Outlet pressure



1.182



22.78



2195



Stroke



Tap head (third level)



NPSH (must)



1125



37.9



81.7



Efficiency



Tap outlet pressure



8.81



34



Tap flow



Shaft power



Inlet water temperature



Rotating speed



3.3.3.2



Maintenance Cycles



3.3.3.2.1



Major Overhaul Cycle: 3 years



3.3.3.2.2



Minor Overhaul Cycle: 1 year



3.3.3.3



Maintenance Items



3.3.3.3.1



Major Overhaul Items



4517



183.49



5268



1.



Disassembly and maintenance of pump package



2.



Disassembly and maintenance of radial and thrust bearings



3.



Disassembly and maintenance of gland seal devices



Page 130 of 241



3.3.3.3.2



3.3.3.4



Minor Overhaul Items 1.



Disassembly and maintenance of radial and thrust bearings



2.



Cleaning of magnetized bi-directional filter



Internal components Components inside the pump can be taken out without disassembling inlet and outlet pipes. These components form the main pressure boundary of the pump shell. The end cover connects with final stage vanes in the rabbet mode. There is an O ring between end cover and shell which forms a high efficiency seal. This sealing ring is mounted in the slot of the shell. The bolts of end cover are hydraulically tightened. The connection surface between the end cover and shell should be made smooth. There is a gasket, which is a copper plating steel ring, between the last stage internal body and shell. Adjacent joint of internal body is in rabbet mode and has an O ring. Fixing pins of each stage of the vanes are fixed on the front stage pump body. All pins of each stage of the vanes are fully-enclosed type and they do not contact with the transported fluid in the pump. Internal components are the fixed connection parts between the internal pump body and vanes. They are fixed on the shell via butterfly springs between the last stage vanes and outlet end cover. During the installation and shutdown period, these springs can supply adequate static pressure to contact surfaces so as to allow internal components to expand freely. When the pump is running, hydraulic pressure differential is created to produce a tight seal between the surfaces. An Inlet guide plate is positioned in rabbet mode at the inlet of the pump so as to guarantee the neutral position of internal components when installing the pump package. This rabbet guarantees the inlet guide device is tightly fixed on cylinder by the take-up ring. At the same time device will extend freely during thermal fluctuations. Intermediate Pin There is an intermediate pin on the secondary stage. Two sealing rings are used for sealing between the pump cartridge and shell. A circumferential space is formed at the front secondary stage pump casing. A radial hole is located on the casing of the secondary internal pump, causing under pressure water to enter the circumferential space. There is a bleed-off opening on the drum, casuing secondary bleed off water from circumferential space to enter into intermediate pin space. Balance Device This pump is a balanced drum which is installed behind last stage impeller of the bearing. The balanced drum rotates inside the throttling sleeve which is fixed at the end cover, forming a pressure decreasing device. Outlet pressure acts on the unbalanced zone of last stage impeller, which forms a redundant driving force aimed towards the inlet, making the bearing in an extended state. The balanced drum is fixed on the bearing. This bearing direction is fixed by the shaft collar and a nut on the low pressure side. The drum is fixed on the shaft with a key and secured with nuts. Bearing



3.3.3.4.1



Radial bearings The pump shaft is supported by two common cylindrical radial sliding bearings. It uses Babbitt lining with forced lubrication from main lube oil system. The bearings are under the bearing clamp cover, which are clamped by bolts on lower bearing support. Page 131 of 241



The whole assemblies are positioned by the pins to ensure the accurate reassembly 3.3.3.4.2



Auto-adjustable thrust bearing



Fig. Thrust bearing drawing The thrust bearing can bears the same thrusting load in two directions. So it is suitable for the rotor rotating clockwise or counterclockwise. In the flange that connects to bear support ring, the ends of positioning thrust pads are embedded in the grooves on both sides. In this way, thrust pad can be positioned loosely. This makes it possible to let pads move freely without falling off. Shaft end sealing The pump is provided with the fixed lining water injection unloading labyrinth seal to prevent the sealing water from entering the pump and pump water from leaking while pump is running. The cooling water is injected into the sealing chamber, then it flows towards the direction that pump water comes from. Next, it meets the leak water from outside in the unloading ring where it is connected with the booster pump inlet via a tube. Provided the sealing water pressure is higher than the booster pump inlet pressure, the hot water in the sealing chamber will not leak out. Some condensate sealing water flows into the condenser along with the labyrinth seal via the U-shaped tube. 3.3.3.5



Maintenance Technology



3.3.3.5.1



Bearing checking: If it is necessary to disassemble the bearing for on-site checking or replacement under the condition that the core stays. The following procedure should be adopted:



3.3.3.5.2



Driving end radial bearing



Page 132 of 241



3.3.3.5.2.1 Cut off and remove all the instrument affecting the disassembling work. Make the marking on the wire joint and wrap it for reassembly. 3.3.3.5.2.2 Remove the small caliber tube influencing the disassembling work. Remove the shield of the coupling connected with the boiler feed pump, disconnect the coupling, and remove the shims and intermediate connection component. 3.3.3.5.2.3 Remove the nuts and bolts on driving end shaft supporter cover and inlet end cover. 3.3.3.5.2.4 Remove the tightening nuts on the stud bolts of bearing supporter cover and the supporter, and the retaining pins. 3.3.3.5.2.5 connect the lift eye-ring on the bearing cover. Jack the bearing supporter cover by the jacking screws, hang the cover away carefully. Avoid damage of oil baffle on both sides of the bearing supporter in the process of hanging. 3.3.3.5.2.6 Remove the tightening nuts on the stud bolts of radial bearing gland and the supporter. Remove the retaining pins. Jack the bearing gland with the jacking screws. Remove the bearing gland. 3.3.3.5.2.7 Remove the upper half radial bearing and the oil baffle. Remove the anti-rotating pins, jack the shaft, remove the lower half radial bearing and oil baffle. Caution that don’t exchange the upper half bearing and oil baffle with the lower half ones. Make the distinct marking on the upper half and lower half bearings for reassembly. 3.3.3.5.2.8 Check the bearing and journal for damage and wear. If necessary, replace them. Measure the bearing clearance and compare measuring result with the data in the Table 2. If the clearance exceeds the specified value or there is the possibility that the clearance will exceed the specified value in the next time measurement. Replace the bearing. Caution: apply some lube grease to the shaft and the bearing surface before the final assembly. 3.3.3.5.2.9 Turn the lower half bearing and the oil baffle to their positions, they put down the shaft. 3.3.3.5.2.10 Fit together the upper half bearing and the oil baffle; ensure the retaining pins are in their positions. Identify the markings on the upper half and lower half bearings and oil baffles. 3.3.3.5.2.11 Mount the bearing gland and keep the anti-rotating locating pins are in their positions accurately. Screw on the two locating pins and tightening nuts on the bearing gland. 3.3.3.5.2.12 Hoist and put the bearing supporter cover to its position, ensure the oil baffles on both ends are located correctly. Screw on the tightening nuts and retaining pins. Remove the lifting tools. 3.3.3.5.2.13 Screw on the tightening nuts and bolts of the bearing supporter cover and the inlet end cover. 3.3.3.5.2.14 Reconnect all the opened tube of small caliber. Mount the instrument. 3.3.3.5.2.15 Mount the coupling and its shield. 3.3.3.5.2.16 Free end radial thrust bearing 3.3.3.5.3



Cut off and remove the entire instrument. Make the markings on the wire joints and wrap them for reassembly.



3.3.3.5.3.1 Remove the small caliber tube influencing the disassembling work. Page 133 of 241



3.3.3.5.3.2 Remove the coupling shield at the driving end, disconnect the coupling, and remove the shims and intermediate connection component. 3.3.3.5.3.3 Remove the tightening screws between the end cover and free end bearing supporter. Remove the end cover and O-rings. 3.3.3.5.3.4 Remove the tightening nuts on the stud bolts of bearing supporter cover and the supporter. Remove the retaining pins. 3.3.3.5.3.5 Remove the bolts and nuts for clamping bearings support with the cover at big side. 3.3.3.5.3.6 Mount the lifting ring on the bearing supporter cover. Jack the bearing supporter cover with the jacking screws. Set up the appropriate lifting tools. Hoist the bearing supporter cover and take it away, avoid the damage to oil baffles. 3.3.3.5.3.7 Remove the retaining pins. Remove the tightening nuts on the stud bolts between the axial bearing gland and bearing supporter. Dismount the bearing gland. 3.3.3.5.3.8 Remove the upper half radial bearing and the oil baffles. 3.3.3.5.3.9 Remove the tightening screws and retaining pins on the thrust bearing shield. Jack the shield and remove it. Caution that avoid damage to the bearing and oil baffle in the process of dismantling the upper half bearing pedestal and thrust bearing cover. 3.3.3.5.3.10 Jack the shaft. Remove the lower half radial bearing and oil baffle. 3.3.3.5.3.11 Loosen the spring. Remove the lube oil sealing ring from the lower half bearing supporter. 3.3.3.5.3.12 Remove the internal hexagonal screws on the baffle of end cover. Remove the baffle. Dismantle the lube oil sealing ring and the spring from the end cover groove. 3.3.3.5.3.13 Remove the entire supporting board of the thrust bearing in the following way. 1)



The resistance temperature detector of thrust bearing is inside the thrust pad and fixed on the supporting board. The conductor enter the junction box via the lower half bearing pedestal. Before remove the supporting plate of the thrust bearing from pedestal, you should disconnect the wire that connecting with the probe from junction box and remove it from seal sleeve. Turn the supporting board around the shaft until half the support board with the stopping pins can be removed, then turn and remove the other half. Remove the supporting board on the other thrust disc. Caution that jack the shaft until the load on the radial bearing reduces to zero.



2)



Check the radial bearing, the bearing journal, the thrust pads, the thrust disc and the lube oil sealing rings and oil baffles for wear and damage. If necessary, replace them. Caution that the there should be no appreciable abrasion on babbit surface except for the color changing. It is recommended that replace the bearing pad if the color changing area exceeds 50% of the total surface. Check the bearing, the bearing journal and the oil baffle for abrasion and damage. If necessary, replace them. Measure the bearing clearance and compare the result with the data in Table 2. If the clearance exceeds the specified value or there is possibility that it will exceed the specified value in the next time measurement, replace the bearing. Apply some lube grease to the thrust disc, the thrust pad surface before the final reassembly.



3)



Jack the shaft, turn the lower half radial bearing and oil baffle around the shaft until they reach their places. Mount the lube oil sealing ring and the spring on it. Put down the shaft. Page 134 of 241



4)



Assemble the thrust bearing supporting board one by one in the following way. Pay attention to that the resistance temperature detector is inserted into the thrust pad and fixed on the supporting board correctly. The rest conductor should go through the lower half bearing pedestal. The combined conductor of thrust bearing supporting board and the level split of bearing supporter forms an angle of 90°. The retaining pins are located in one groove of the thrust bearing gland. Put the half supporting board without retaining pins on the shaft, make the thrust pad surface connect with the thrust disc, then turn it into the bearing supporter. Then, put the other half supporting board with retaining pins. Turn the entire the supporting board around the shaft until the retaining pins are against with the bearing supporter. Mount the thrust bearing supporting board on the other side. Don’t use the filler gauge to measure the clearance between the thrust pad and the thrust disc, the measuring result is not accurate and the babbit surface will be damaged.



5)



Use hex bolts to clamp the cover with half bearing pedestal. When check the axial clearance, fix the driving end firmly, make the thrust disc against the thrust pad. Measure the clearance between the outer thrust bearing lining and inner wall of thrust bearing chest at the end cover. The original axial clearance refers to the list 2. For any deviation, find out the reason and remove the end cover. Ensure the temperature detector are in the thrust pads and the conductor going through the lower half bearing pedestal before t thrust bearing cover is mounted.



6)



Mount the thrust bearing gland, and fix it with the retaining pins and the screws.



7)



Mount the upper half radial bearing.



8)



Ensure the anti-rotating pins of the bearing are in their places correctly, Mount the bearing gland and fix it on the bearing supporter with the pins and nuts.



9)



Mount the upper half oil baffle.



10) Mount the bearing supporter cover at the free end, and fix it on the bearing supporter and the big end cover with the retaining pins, bolts and nuts. Remove the lifting tools and rings. 11) Insert the split oil sealing ring and the spring into the end cover groove. Mount the damper with the internal hexagonal screws to squeeze the oil sealing ring. 12) Mount two new O-rings on the end cover. Mount the end cover on the bearing supporter, and fix it with the screws, and tighten the screws by the torque 130N.m. 13) Mount the coupling and its shield. 14) Mount and connect the small caliber tube with the instrument. 3.3.3.6



Overhaul This section is suitable for the pump disassembly and pump core dismantling. If the spare core is available, mount it in the following method before disassembling the pump core or repairing the core abraded.



3.3.3.6.1



Preparation



3.3.3.6.1.1 Same as the above mention. 3.3.3.6.1.2 Remove all the instrument and the small caliber tube affecting the disassembling work from the bearing supporter and gland seal at the driving end and free end.



Page 135 of 241



3.3.3.6.1.3 Open and remove the both water returning pipelines of the balance chamber. 3.3.3.6.1.4 Open and remove the lube oil inlet and returning pipeline of the bearing. 3.3.3.6.1.5 Check all the lifting equipment and the special tools are in good condition. Pay attention to that the pump shaft nuts at the driving end rotate leftward while the nuts on the free end rotate rightward. If necessary, make the new markings on the components. 3.3.3.6.1.6 Core drawing out The entire procedure is illustrated in the given drawing.



3.3.3.6.1.7



1)



Remove the coupling shield, the laminations and the intermediate connective component.



2)



Remove the tightening screws from the coupling nuts. Then screw off the nuts from the coupling.



3)



Remove the half coupling and it keys.



4)



Remove the bolts on the tightening ring and the tightening ring. Remove the Oshaped ring and the gaskets.



5)



Mount the removed pipe on the bearing at the driving end in accordance with INDRAMAYU-J1-3A-00. Mount the supporting rolling wheel assembly in the pump seat.



6)



Remove the nuts of the bolts on the big end cover. Remove the nuts on the big end cover in the procedure specified in INDRAMAYU-J8-3B-00.



7)



Draw out the core from the drum with the disassembling tools. See the drawing INDRAMAYU-J1-3A-00.



Disassembly of pump Core 1



Preparation. Support the core stably in the process of disassembling. The disassembly is carried out horizontally first and vertically at last. Never support the core with the shaft. Pay attention to the balance drum tightening nuts, free end sealing bushing, water-throwing ring nuts at the free end, locking nuts, thrust disc nuts are nuts rotating rightward, the driving end coupling nuts, water-throwing ring nuts and the locking nuts are such nuts rotating leftward.



2



The appropriate supporting frame or working platform on maintenance site has been set up when the core is hanging out by the overhead crane.



3



Put the core on the frame horizontally. Remove the lifting tools or lug.



4



See the drawing. Mount the core supporting board and make it against inlet end cover tightly. Screw on 4 draw rod on the supporting board via the big end cover hole, and tighten the tightening nuts until they go against the supporting board tightly.



5



Mount the washer on the other end of the draw rod, screw on the nuts to fix the core assembly.



6



Mount lifting eyes on the big end cover with bolts and nuts & washer.



7



Remove the driving end bearing and the gland seal



Page 136 of 241



3.3.3.6.1.8



8



Remove the nuts and the washers of the core, the stud bolts on the pressure board and the shaft head.



9



Unscrew the first stage disassembling tube. Remove the disassembling board on the bearing supporter at the driving end. Remove the bearing and the sealing sleeve.



10



Remove the radial bearing, the thrust bearing and the gland seal at the free end.



Inner pump shell disassembly 1



Remove the bearing and the mechanical sealing at the driving end and the free end.



2



Fix the rotor with stud bolts, nuts and the supporting board.



3



Hoist the core and put it on the supporter. Pay attention to that never support core weight with the pump spindle.



4



Remove the nuts and the washers at the big end cover and the draw rod. Remove the draw rod.



5



Hoist the big end cover and take it away from the pump spindle. Pay attention to that avoid damages to balance drum and balance drum sleeve when the big end cover is being hoisted.



6



Flatten the stop bar of balance drum stop washer. Unscrew the balance screws with the special spanner. Remove the stop washers.



7



Remove the balance drum sealing pressure ring and sealing rings.



8



Heat the balance drum with the flame until it expands adequately. Remove the balance drum and the keys on it with tools and keep them well. If it can not be removed, repeat the procedure after it is cooled.



9



Remove the butterfly-shaped spring from the final stage guide vane.



10



Remove the locking sheets or the screws for the final stage guide vane. Then remove the guide vane.



11



Heat the final stage impeller hub until it expands adequately and the final stage impeller can be removed. Make the marking on the impeller for reassembly. Remove and keep the keys and retaining rings on the impeller. Cautions: Do not remove it forcedly. If it is difficult to remove them, repeat the procedure.



12



Remove the tightening screws of inner pump shell at the stage V and the stage IV. Remove the inner pump shell at the stage V. Remove the O-shaped ring and the baffle on it.



13



Hang and take away the stage V inner pump shell and the guide vane.



14



Heat the stage V impeller hub until it expands adequately and the impeller can be removed. Remove the impeller. Remove and keep the keys and retaining ring on it



15



Repeat the procedure 12 to 13 until only the stage I impeller is left. Remove the O-shaped ring and the sealing baffle on the stage II pump shell. Pay attention to that the screws connecting the stage III pump shell and the stage II pump shell are tightened by the locking gaskets. Remove those locking gaskets first before removing the screws.



Page 137 of 241



16



Screw on the lug on the shaft end. Mount the lifting tools. Hoist the shaft away from the inlet end cover carefully.



17



Support the shaft horizontally. Heat the stage I impeller hub. Remove the stage I impeller. Remove the impeller keys and keep them well.



18 3.3.3.6.2



lift up the inlet end cover away from the support with the lifting tools.



Maintenance and replacement technology regulations Check all the components for wear and damages. Measure the clearances among all the components with the outer micrometer and the inner micrometer in accordance with the data in List 2. If the clearance reaches the allowable maximum value or will reach the allowable maximum value before the next time overhaul, replace the component. Under the consideration about the working performance, if the outlet pressure drop exceeds the limit, the motor power consumption or the steam consumption is too much, or the pump vibration exceeds the limit, the pump overhaul should be carried out.



3.3.3.6.2.1 Impeller and abrasive ring 3.3.3.6.2.2 Check the impeller for abrasion, especially the blade tip. Check the inner edge of the impeller for the damage caused in the process of the disassembly. Remove the burr ensuring inner holes are smooth without deformation. 3.3.3.6.2.3 Check the outer surface of the impeller neck and its corresponding guide vane and inner pump shell lining. Measure the radial clearance. If it exceeds the data specified in List 2, or it will exceed the specified data before the next time maintenance. The abrasive ring must be replaced. The maintenance should be carried out in the following procedure. 3.3.3.6.2.4 Repair the outer surface of the shaft neck based on the impeller inner hole. 3.3.3.6.2.5 Lathe the inlet end cover, inner pump shell and the abrasive ring on the guide vane. 3.3.3.6.2.6 Clean the abrasive ring seat thoroughly. Immerse the new abrasive ring into the liquid nitrogen for few minutes. Put it in the specified position after it shrinks. Pay attention to that don’t take it out from the liquid nitrogen with the bare hand. 3.3.3.6.2.7 Fix the abrasive ring by the spot welding technology 3.3.3.6.2.8 Process the inner edge of the abrasive ring in accordance with new data in List. 3.3.3.6.2.9 Shaft 3.3.3.6.2.10 Check the shaft for damages or deformation. Check the concentricity which should be less than 0.02mm. 3.3.3.6.2.11 Check all the threads are in good condition or not, the key slots are glossy or not. 3.3.3.6.2.12 Gland seal 3.3.3.6.2.13 Check the sealing shaft sleeve and sealing bushing for damages. 3.3.3.6.2.14 Measure the radial clearance of the sealing shaft sleeve and the sealing bushing. If the clearance exceeds the limit, replace the sealing shaft sleeve and the sealing bushing. Page 138 of 241



3.3.3.6.2.15 Radial bearing and thrust bearing 3.3.3.6.2.16 Clean up the radial bearing thoroughly and check it for damages or abrasion. Measure the bearing clearance, compare the measuring result with the data specified in List. If necessary, replace the bearing. 3.3.3.6.2.17 Clean up and check the thrust pads for abrasion and damages. Pay attention to that any appreciable abrasion can not appear on the thrust pad Babbitt alloy surface except for the metal color changing. It is recommended that if the color-changed area exceeds half the total surface, replace the thrust pad. 3.3.3.6.2.18 Check the thrust disc for abrasion or damages. If necessary, replace it. 3.3.3.6.2.19 Check the lube oil sealing ring for abrasion or damages. If necessary, replace it. 3.3.3.6.3



General Inspection List



3.3.3.6.3.1



Check all the stud bolts, the nuts and the screws for damages or defects. If necessary, replace them.



3.3.3.6.3.2



Replace all the joint gaskets, O-rings, and baffles for assembly.



3.3.3.6.3.3



Clean up all the retaining pins which must be in good condition. Replace the abraded or damaged keys.



3.3.3.6.3.4



All the keys must be in good condition and Mounted in the key slots. Replace the abraded or damaged keys.



3.3.3.6.3.5



Check the couplings and bolts for abrasion or damages. If necessary, replace them.



3.3.3.6.3.6



Clearance



3.3.3.6.3.7



The top clearance and bearing pad tightening force can be measured via a lead wire. The side clearance can be measured with the filler gauge. The requirements are as follows:



Measuring position



Standard (mm)



Bearing pad tightening 0～0.03mm force Top clearance Side clearance



0.215mm Max. 0.26mm 0.14mm



Oil-throwing ring and oil 0.41/0.35mm baffle max.0.47mm



Means Lead wire



Lead wire Filler gauge Filler gauge



Bearing radial scrape & leveling criteria: Put a layer of red lead powder on the shaft journal and Mount the lower half bearing pad.



Page 139 of 241



Turn the shaft to check Babbitt alloy surface connection. It is generally required that the contact angle is approximately 45 0-600. The contact surface of the lower half bearing pad should reach 75% and the contact should be even. 3.3.3.6.3.8 Core assembly Before assembling, clean up all the components including inner hole and oil route thoroughly. It is recommended that apply some colloidal graphite or something like that to the shaft, the impeller inner edge, the shaft sleeve and the balance drum inner edge, after they become dry, polish them. 3.3.3.6.3.9



Inner pump shell and impeller assembly



3.3.3.6.3.10 Put the pump shaft on the support horizontally, Mount the stage I impeller keys. 3.3.3.6.3.11 Warm up the hub after the stage I impeller, mount it on the shaft and the key to make it closely against the shaft collar. Be careful that do not apply excessive force. If it could not reach the required position, take down it and check it for dirty with the shaft collar, remove the impeller and check it for the burr or contamination. If necessary, clean it up. Then repeat the procedure 8, 9. If the shaft temperature is higher than the ambient temperature, mount the impeller after the shaft becomes cooled. 3.3.3.6.3.12 Lift it up and put the inlet end shied on the support, ensure it is located on the supporting board correctly. 3.3.3.6.3.13 After the shaft and the stage I impeller becomes cool, Mount the lifting eye at the free end. Hoist the pump shaft vertically from the inlet end cover. 3.3.3.6.3.14 Put down the pump shaft carefully until the impeller inlet neck enters the end shield sleeve. The impeller is located at the inlet end cover. Remove the shaft end lug. 3.3.3.6.3.15 Fit the new O-shaped ring, baffle and Garlock seal on the inner pump shell. 3.3.3.6.3.17 Mount the anti-rotating pins on the guide vane. Mount the stage I pump shell and the guide vane on the stage I impeller. Ensure the inner pump shell is on the inlet end cover properly. Remove the lifting tools. 3.3.3.6.3.18 Fix the stage I pump shell on the inlet end cover with the internal hex screws. The screws can not protrude from the inner pump shell surface. 3.3.3.6.4



Check the axial displacement total in the following way before further assembly.



3.3.3.6.4.1



Mount the hoist lug at the free end. Mount the appropriate lifting tools.



3.3.3.6.4.2



Hoist the pump shaft, the stage I impeller can be supported on the inlet end cover.



3.3.3.6.4.3



Take the surface of first stage as reference, align and make them



3.3.3.6.4.4



Jack the shaft with the jacks and endeavor to make it against the free end. Make the second line also based on the above basis. Lower the shaft.



3.3.3.6.4.5



Measure the distance between both lines, the result should be approximately 8mm. If not, find out the reason. The allowable minimum displacement is 6mm.



3.3.3.6.4.6



Mount the retaining ring and the keys on the stage II impeller



3.3.3.6.4.7



Assemble the impeller in the procedure 2.



3.3.3.6.4.8



Mount the other impeller, inner pump shell and guide vane in the procedure 2 and 7. Page 140 of 241



a line.



Check the axial displacement total in procedure 5, it should be not changed. Pay attention to that the tightening gaskets must be assembled for the screws connecting the stage II and stage III pump shells. 3.3.3.6.4.9



Fix the final stage guide vane on the final stage pump shell with the hexagonal screws.



3.3.3.6.4.10 Mount the balance drum keys on the shaft. Heat the balance drum and Mount it on the shaft. Make it against the shaft collar and aim at the key slot. Screw on the balance drum nuts. 3.3.3.6.4.11 After the assembly becomes cool, unscrew the balance drum nuts, Mount the new sealing ring and sealing pressure ring, the new locking washer, screw on and tighten the balance drum nuts. 3.3.3.6.4.12 Mount the lamination spring 3.3.3.6.4.13 Screw on the tightening nuts on one end of the draw rod, Mount the draw rod on the core supporting board and tighten it with the tightening nuts. 3.3.3.6.4.14 Put the adjustable bolt nuts between the final stage guide vane and the big end cover, put down the big end cover carefully, make it to through the pump shaft and tightening screw. 3.3.3.6.4.15 Adjust the bolts and nuts until the clearance between the supporting board and the big end cover service surface reaches 752±0.10mm. 3.3.3.6.4.16 Put the washers and nuts on the pull-up screw rod and tighten the nuts. Remove the lifting device. 3.3.3.6.4.17 Mount the positioning device at the driving end 3.3.3.6.4.18 Mount the lugs. Hang the core horizontally and put it on the support. Remove the positioning device. Pay attention to that when the core is horizontal, don’t support the core with the shaft at any time. 3.3.3.6.5



Mechanical seal mounting The core must be on the support when it is assembled, and Mount the soft gaskets to prevent the damages. The following instruction is available for mechanical seal at both driving end and free end.



3.3.3.6.6



1)



Replace the O-rings in the grooves of each cooling jacket with new ones. Mount the cooling jacket on the inlet end cover and the big end cover.



2)



Replace the O-rings in the groove of each seal chest. Mount the seal chest on the cooling jacket.



3)



Fix the cooling jacket and the seal chest on the inlet end cover and the big end cover with the bolts.



4)



Mount the keys and the mechanical seal in accordance with the instruction.



Mounting bearing at drive shaft end. 1)



Put the new O-rings in the grooves of the oil throwing ring. Mount the oil throwing rings. Direct the oil throwing ring opening at the bearing. Fix the oil throwing ring on the shaft with the tightening screws.



2) Position drives end support on inlet end cover with the retaining pins. Tighten it with the bolts and nuts. Page 141 of 241



3) 4)



3.3.3.6.7



Lift the shaft. Apply some grease to the lower half radial bearing. Turn it to its position. Turn the lower half oil baffle around the shaft to its position. Then put down the shaft.



5)



Mount the upper half radial bearing ensuring the markings on the upper and the lower half bearings match.



6)



Mount the radial bearing gland. Ensure the anti-rotating pins are in their positions. Tighten the bearing gland with the retaining pins and nuts.



7)



Mount the upper half oil baffle.



8)



Mount the bearing support cover at the driving end. Fix it on the support with the retaining pins, bolts and nuts and tighten it.



Free end bearing Mounting



3.3.3.6.7.1 Insert the new O-rings in the grooves of oil throwing rings. Mount the oil throwing rings on the shaft. Direct the oil throwing ring opening at the bearing. Fix it on the shaft with the tightening screws. 3.3.3.6.7.2 Assemble the thrust disc keys on the shaft 3.3.3.6.7.2 Heat the thrust disc hub. Mount the thrust disc on the shaft ensuring the key grooves are pointing at the thrust disc and against the shaft collar. Screw on the nuts on the thrust disc tightly right away. 3.3.3.6.7.3 When the thrust disc and shaft are cooled to room temperature, unscrew the nuts on the thrust disc. Mount the new retaining washer. Screw on the nuts on the thrust disc and tighten them with the special spanner. 3.3.3.6.7.4 Fix the free end bearing support on the big end cover with the retaining pins, and tighten it with the bolts and nuts. Pay attention to that apply some grease to the bearing and radial bearing surface before assembling. 3.3.3.6.7.5 Lift the shaft. Turn the lower half radial bearing and the oil baffle to the specified position. Mount the oil seal ring and the spring on the shaft, put down the shaft. Pay attention to that the resistance temperature detector is inserted into the thrust pad and fixed on the thrust bearing supporting board. When the thrust bearing supporting board is mounted, the detector should be in its place before fixing the seal. The other conductors go through the bearing support and seal ring and return to terminal. 3.3.3.6.7.7 Put the half supporting board without the retaining pins on the shaft, make the thrust pad surface contact with thrust disc. Turn the supporting board until it enters the bearing support. Put the other half supporting board. Turn the entire supporting board together around the shaft until the retaining pins are against the bearing support. Mount the supporting board on the other side in the same way. Pay attention to that don’t insert the filler gauge between the thrust pad and thrust disc to measure the clearance, otherwise, it will damage the thrust pad surface and the measuring result is not accurate. 3.3.3.6.7.8 Fix the bearing end cover on the bearing support clearance, make thrust disc against the inner side the clearance between the outside thrust bearing end cover. The original axial clearance is 0.40mm. from it, find out the reason.



with the screws. Check the axial of the thrust pad tightly. Measure supporting board gasket and the If the measuring result is different



Note: Before mounting the thrust bearing, ensure the temperature detector conductor Page 142 of 241



lug is in the groove of bearing support. 3.3.3.6.7.9 Mount the thrust bearing casing. Fix it on the bearing support with the retaining pins and the screws. 3.3.3.6.710 Mount the upper half radial bearing 3.3.3.6.7.11 Mount the upper radial bearing gland. Ensure the anti-rotating pins of the bearing are in their places. Fix it on the lower half bearing support with the retaining pins and nuts. 3.3.3.6.7.12 Mount the upper half oil baffle 3.3.3.6.7.13 Mount the bearing support cover, ensure the oil baffle anti-rotating pins are in their places under the support cover. 3.3.3.6.7.14 Fix the bearing support cover on the support with the retaining pins, bolts and nuts. 3.3.3.6.7.15 Mount the oil seal ring in the groove of end cover and Mount the spring. Fix the damper on the end cover with the screws to squeeze the seal rings. 3.3.3.6.7.16 Mount two new O-rings on the end cover. Fix them on the bearing pedestal with the screws, the tightening torque is 130N·m. 3.3.3.6.8



Core assembly



3.3.3.6.8.1 Fix the disassembling board on the driving end bearing support with the bolts. Mount the first stage disassembling tube. 3.3.3.6.8.2 Remove the nuts and clamping rod of the core. Remove the supporting board from the inlet end cover. 3.3.3.6.8.3 Mount the new O-shaped ring in the circumferential groove of the big end cover and the inlet end cover. Mount the stainless steel teeth gasket between the inlet end cover and drum. Pay attention to that seal ring baffle at the inlet end cover must be mounted on the water inlet side of O-shaped ring. 3.3.3.6.8.4 Mount the lifting eye at the big end cover. Mount the lugs at the inlet end cover. 3.3.3.6.8.5 Fix the drum jacking assembly on the pump pedestal. 3.3.3.6.8.6 Connect all the disassembling tubes. Put the disassembling tube assembly into the drum until the disassembling tube is on the drum jacking assembly. 3.3.3.6.8.7 Shift the core into the drum until the first stage pipe used for removing connects with tube assembly and seats on jacking device. Remove slings between the pipes and cylindrical bolts. 3.3.3.6.8.8 Remove the lifting equipment and the lift ear on the inlet end lid. Pay attention to that when the core enters the drum, adjust the jacking assembly to ensure the concentricity of the inlet end cover and the drum. 3.3.3.6.8.9 Push the core into the drum carefully. Remove the each stage disassembling tube at the drum jacking assembly until all the bolts are mounted in the big end cover. Pay attention to that when the core enter the drum, ensure the O-shaped ring and the Garlock seal element will not be damaged and the concentricity of the core and the drum. 3.3.3.6.8.10 Continue pushing the core into the drum until the inlet end cover and big end cover reach their places accurately. 3.3.3.6.8.11 the big end cover contacts the drum, remove the lifting eye of the lower end cover. Page 143 of 241



3.3.3.6.8.12 Remove the drum jacking assembly from the pump pedestal. Remove the disassembling tube from the driving end bearing pedestal. 3.3.3.6.8.13 Mount the big nuts on the stud bolts of the big end cover and tighten them by hand. 3.3.3.6.8.14 Pre-tighten the big nuts with hydraulic tightening device, see the drawing INDRAMAYU-J8-3B-00. 3.3.3.6.8.15 Mount the protective caps on the bolts 3.3.3.6.8.16 Mount the new gaskets, O-shaped ring and baffle between the inlet end cover and the big drum. 3.3.3.6.8.17 Mount the retaining ring in the groove between the inlet end cover and the big drum. Fix the retaining ring on the big drum with the bolts. 3.3.3.6.8.18 Mount the coupling keys and the upper half coupling. 3.3.3.6.8.19 Screw in the nuts on the coupling, tighten them with the special spanner and fix them with the screws. 3.3.3.6.8.20 Turn the pump manually at the coupling ensuring the pump can rotate freely. 3.3.3.6.8.21 Check the coupling alignment. 3.3.3.6.8.22 Mount the coupling lamination and the intermediate connective components. Then Mount the casing. 3.3.3.6.8.23 Mount the instrument. Connect the cooling water pipeline, lube oil pipeline and all the small caliber tube disconnected before disassembly with the new joint washers. 3.3.3.6.9



Trouble checking and treatment When the failure occurred to one component or the assembly, the reasons for the failure must be found out before replacing the damaged components. Faults and solutions



Failure



Failure to start up



Possible reasons



Solutions



1 The power supply failed.



Check the power supply



2 Motor failed



Check the motor.



3 Starting device failed.



Check the starting device. Open the couplings one by one to



4 The pump is stuck.



find the stuck position. If necessary, repair it.



Low output



5 The pump is in tripped state.



Find out the reason. Reset the trip value.



1Motor or power supply failed.



Check the motor and the power supply.



2 The rotating direction is not correct.



Page 144 of 241



Check the rotating direction.



3 Severe wear inside the booster



Disassemble the pump. If



pump and boiler feed pump.



necessary, repair it thoroughly.



4 Recirculation system failed.



Check this system. Check the coupling adjusting



5 Boiler feed water speed is lower.



system and working conditions.



6 The pump inlet pressure is lower.



Check the inlet.



1 The lube oil is not sufficient or Check the oil source. severely contaminated. Bearing



2 Misalignment of pump and the Check the alignment. coupling.



overheat



3



The



bearing is deviates.



or



Check the bearing.



4 The lube oil specification is not correct.



Check the oil specification.



1 The outlet pressure is too low.



Check the flow.



2 Rubbing High power



abraded



between the pump rotor



and the static component. 3 Inside clearance is too big.



Check the clearance. Check the clearance.



4 The mechanical seal is Mounted Check the mechanical seal. incorrectly. Check the inlet valve is opened or 1 The pump is running under the



not, the inlet filter is clean or not.



water interruption condition.



Check the booster pump outlet pressure is normal or not.



Water pump overheat or stuck



2Rubbing occurs inside the water Check the clearance. pump. 3 The oil supply is insufficient or the oil specification is incorrect.



Check the oil source and the oil specification.



4 The lube oil system failed.



Check the oil system.



5 The bearing abrasion or deviation.



Check the bearing.



6



The



pump alignment accurate.



Big noise or



1 Poor dynamic balance



vibration



performance of the motor.



is



not



Page 145 of 241



Check the alignment. Find out the device causing the failure.



Check rotor balance.



dynamic



2Misalignment of the coupling.



Check the alignment.



3 The bearing abrasion.



Check the bearing.



4 The anchor bolts are loosened.



Check the bolts.



5 The clearance inside the pump is too big.



Check the clearance.



6 The suction opening has no Check the water inlet system. pressure. 7 The coupling is damaged.



Check the coupling.



8 The vibration caused by the poor Check the pipeline and the support nearing the pumps. support for the pipeline leads to the resonance. 9 Recirculation system failed.



3.3.4



Hydraulic coupler



3.3.4.1



Equipment constitution



Check the recirculation system.



The hydraulic coupler basically consists of coupler body, input shaft (low speed gear shaft), high speed gear shaft, input shaft, output shaft, lubrication and working oil pump components, auxiliary lubricating oil pump components, and rotating speed control units. These parts, together with some part of oil pipelines, are installed in a tank, lower part of which is oil storage tank. Lubricating and cooling oil for each bearing and working oil for hydraulic coupler power transmission are supplied by oil pump through oil suction pipelines. Three shafts are supported by six sliding bearings respectively. Axial positioning and axial thrust force at all working conditions are achieved by two thrust bearings respectively. Lubricating oil pump and working oil pump are driven by input shaft through gear type coupling while auxiliary lubricating oil pump is driven by motor. As core components for torque driving, Coupler is composed of turbo and pump wheel as well as enclosure. Turbo is fixed on high speed gear shaft by bolts while pump wheel is fixed on output shaft by bolts. Enclosure is fixed on turbo by bolts. It rotates together with turbo during operation. Rotating speed control units are composed of scoop tube, working oil flow control valve and scoop tube driving mechanism. 3.3.4.2



Overhaul and repair period and items



3.3.4.2.1



Periodic inspection



3.3.4.2.1.1 Perform an hour preheating operation every two months during a long outage. 3.3.4.2.1.2 Daily inspection for temperature, lube oil pressure, working oil pressure, lube oil filter Page 146 of 241



differential pressure. 3.3.4.2.1.3 Measure vibration and make record every three months, compare with the last time values and find out the problem. 3.3.4.2.1.4



Check oil level every week, add oil to specified position.



3.3.4.2.2



Minor overhaul period item: half a year once



3.3.4.2.2.1 Disassembly and clean oil-filter strainer 3.3.4.2.2.2 Leakage elimination for coupling components connecting flange joint 3.3.4.2.2.3 Scoop tube components add lubricating grease. 3.3.4.2.2.4 Filter oil in oil tank 3.3.4.2.3



Major overhaul period item: disassembly major overhaul performed every ３ ～ ５ years.



3.3.4.2.3.1 Part disassembly maintenance for coupling 3.3.4.2.3.2 Appearance inspection for driving gear and driven gear. 3.3.4.2.3.3 #1—6 bearing pad inspection, thrust pad inspection. 3.3.4.2.3.4 Disassembly maintenance for gear oil pump. 3.3.4.2.3.5 Disassembly maintenance for lube oil pump. 3.3.4.2.3.6 Disassembly maintenance for scoop tube and piston. 3.3.4.2.3.7 Disassembly maintenance for auxiliary oil pump. 3.3.4.2.3.8 Filter oil quality in oil tank, clean oil tank.



Periodical inspection



(1) If outage for long time, carry out preheating operation for one hour once every two months; (2) Check temperature, lubricating oil pressure, working oil pressure, pressure difference of lubricating oil filter everyday; (3) Test vibration condition and make a record once every three months. Compare with that of last time to check any problem;



Repair inspection



(4)



Check oil level weekly and fill oil till regulated level.



(1)



Take apart oil filter strainer and clean up;



(once every half (2) year) (3)



Overhaul inspection



Remove leakage at coupler connecting flange joints; Add lubricant grease to scoop tube parts;



(4)



Filter oil in oil tank.



(1)



Partly disassemble coupler and repair;



Page 147 of 241



(every 3-5 years)



3.3.4.3



(2)



Check appearance of driving gear and driven gear;



(3)



Check bearing #1-6 and thrust bearing.



(4)



Disassemble gear oil pump and repair;



(5)



Disassemble lubricating oil pump and repair;



(6)



Disassemble scoop tube and piston to repair;



(7)



Disassemble auxiliary oil pump and maintain;



(8)



Filter oil in the tank and clean up oil tank.



Technical specification Table



Equipment specification



Name



Unit



Model



R15K400M



Input rotating speed



r/min



1490



Output rotating speed



r/min



5564



Maximum output power



kW



4517



Speed adjusting scope



％



25-100



Mechanical loss (full load)



kW



205±32



Hydraulic loss (full load)



kW



96.5



Efficiency



%



94



Slip



%



≤3



Main components of hydraulic coupler equipment include: enclosure, driving gear, shaft, hydraulic coupler, bearing, oil pump, scoop tube adjusting mechanism, oil cooler, and oil strainer. Slide control of coupler is achieved by scoop tube that adjusts oil supply and output. Many radical blades are located in coupler pump wheel, about 20-40 ones. To prevent resonance condition, blades on turbo are usually 1-4 ones less than that of pump wheel. One safety fusible plug is installed on outward rotary casing of the coupler in case of excessive temperature of operating oil inside the coupler. Scoop tube adjusting mechanism One piece of scoop tube equipment is fixed close to rotary inner sleeve of turbo side. Hydraulic transmitting capacity can be changed by adjusting travel length of scoop tube. Rotating speed of pump is changed in this way. Scoop tube moves away from location of operating chamber (towards oil surface direction). Oil discharged from the scoop tube decreases while oil is filled into operation chamber from mail oil pump. In this way, rotating speed of the pump is increased. As scoop tube moves towards oil surface, oil discharged from the scoop tube increases. Rotating speed of the pump decreases consequently.



Page 148 of 241



3.3.4.4



Maintenance technology



3.3.4.4.1



Disassembly



3.3.4.4.1.1 Drain oil in coupler oil tank by oil filter. Take apart temperature testing parts and scoop tube control parts by I & C personnel. Seal all testing holes temporally. 3.3.4.4.1.2 Remove diverting bolts in tank and blots at upper part of thrust bearing end cover. Check and take apart all accessories on tank cover and lift upper cover away to maintenance site. Use jackscrew to lift tank cover 10mm up before lifting it away. Take out thrust bearings at two ends and remove bolts connecting motor and input shaft, bolts connecting input shaft and main oil pump and bolts connecting output shaft and feed pump coupling. Disassemble the coupling. 3.3.4.4.1.3 Remove bolts connecting coupler enclosure and turbo vertical interface and make relevant marks. Disassemble the whole circle. Spin the high speed gear shaft by motor and bolts at input shaft coupling as well as lengthened handle. 3.3.4.4.1.4 Check interior of coupler enclosure, interior of pump shaft, outer appearance and fusible plug. 3.3.4.4.1.5 Lift out the high speed shaft and low speed shaft stably and gently, and locate them at designated maintenance site. 3.3.4.4.1.6 Take apart power piston flange of scoop tube by loosening bolts and positioning pin on it. Pull out scoop tube and piston components manually. Be gentle and slow in pulling out. Check if there is blockage in case of damage to scoop tube. Place it at maintenance site where there is rubber cushion placed on floor.



(1)



Use kerosene or gasoline to clean scoop tube and thrust piston;



(2)



Clean up piston chamber;



(3)



Do not loosen bolts connecting scoop tube and piston or disassemble it when there is no need to change the scoop tube. If tube is severely bent and has to be replaced, calibrate the tube together with piston that is installed on the machine. Check deviation of scoop tube end.



(4)



Remove bolts on center face of #5, 6 bearing bushes. Take out scoop tube sleeve from lower bearing sleeve side. Lift #5, 6 bearings and pump impeller parts and place them at maintenance site. Disassemble bearing bushings of #5, 6 shafts. Check lined Babbitt metal of pump turbo and #5, 6 bearings.



3.3.4.4.1.7 Remove flange bolts of oil suction pipe at working oil inlet and lubricating oil inlet, and bolts connecting oil pump outlet and pipeline. Lift the whole pump body and place it to maintenance site for disassembly. Page 149 of 241



(1)



Remove end cover and bearing pad along lubricating pump drive and driven shafts, drive and driven shaft end pad and cover of working oil pump.



(2)



Check lubricating pump, driven gear, shaft, drive and driven gear shaft pad of working pump.



(3)



Check shaft bushing of connecting multiple keys of drive shaft of lubricating pump and working pump for crack. Assembly has to be easy.



(4)



Take out two suction pipes of oil pipe and check completeness of bottom valve.



(5)



Use kerosene or gasoline to clean up all parts and measure clearances between different parts.



(6)



Apply a coat of antirust paint and assemble after bearing pad, gear and shaft are checked.



3.3.4.4.1.8 Disassemble lubricating oil pump and working oil pump overflow valve. Clean and check piston spring. 3.3.4.4.1.9 Disassemble auxiliary oil pump and check pump gear. Clean internal parts of gear pump. 3.3.4.4.1.10 Clean up oil and mud in oil tank. Remove rusted defects by polishing. Use flour dough to clean up. 3.3.4.4.2



Reassembly



(1)



Reassemble sequence is reverse to disassembly after all parts and components are cleaned and checked.



(2)



Prevent scoop tube end part from being bent during reassembly process. Mark the positions of coupling shield and impeller.



(3)



Restore measuring instruments by I&C personnel.



(4)



Add ideal N32 turbine oil into oil tank till regulated oil level.



3.3.4.5



Removal of coupling bolts When disassembling coupling, related positions of bolts, screw caps, gaskets and holes should be marked respectively. When taking apart bolts, do not use iron hammer to hit the bolt end. Instead, one cooper rod should be placed as a cushion to prevent damage to screw thread. The disassembled pins from the coupling should be kept well in case of loss. Page 150 of 241



3.3.4.6



Repeat testing of coupling center After disassembling couplings at two ends of coupler, recheck centers of the coupler and equipment at two ends and record the results. Generally, when rechecking coupler center, only the actual value at center needs to be recorded. Not necessary to adjust it back within the standard range. Altogether 3 dial indicators are needed to retest impeller center, among which two are assigned to test end face, and the other one is to test circle. These three gauges are fixed on coupling by clips. In order to pursue test precision, two gauges for both ends should be located at corresponding positions which are in same diameter and have equal distance with impeller center. Make a record of initial values of each gauge. When starting to measure, firstly please divide the circle into four equal sections. Ever since rotor moves 90°, record the reading value (rotor has to move a whole circle). Fill the checked results into related tables. At this point, the disassembling work can be started.



3.3.4.7



3.3.4.8



3.3.4.9



Disassembly of control scoop tube includes: a)



Disassemble the link lever that is connected to actuator, and check control handle on it.



b)



Take apart pointer and staff gauge bracket at position of scoop tube.



c)



Remove position control ring and move it, which is beneficial for checking the control handle.



Removing Enclosure: a)



Take apart shaft centerline and other fittings that may cause blockage.



b)



Disassemble all vertically arranged bolts and tapered pins.



c)



Remove fixed bolts above all interfaces.



d)



Loosen bolts on motor enclosure of auxiliary oil pump, and then lift down motor.



e)



After disassembling intermediate enclosure, screw off flange bolts on enclosure wall of auxiliary lubricating oil pump.



f)



Disconnect upper cover by screwing off bolts, and lift up top cover of coupler with crane.



g)



During lifting process, top cover has to be kept in balance in case of any collision between top cover and rotor components, causing damage to equipment. Put top cover on a bed timber stably.



Disassembly of (coupler) rotor components includes: a)



Take apart control shaft from enclosure guide apparatus and lubricating oil injecting tube from input side.



b)



Remove all temperature sensors.



c)



Disassemble thrust bearing cover as well as thrust bearing that is located outside.



d)



Take apart thrust disc and remove sector block from inner bearing.



e)



Put a steel wire (minimum diameter is Φ1mm) through oil supply slot on bearing seat of measuring point 6, and tighten it together at top of the base. Bearing bushing at measuring point 7 and bearing pad are connected together by calotte.



Page 151 of 241



3.3.4.10



f)



Remove fusible plug out of the main body and discharge the residual oil liquid in tank.



g)



Remove the bolts for tightening pump cover bearing.



h)



Fit a lift eye of M24 into central hole on main driving shaft of the coupler rotor components and tighten it.



Disassembling coupling components After driving worm wheel is removed from enclosure, enclosure itself may slide downwards. Therefore, three wood columns are usually used to support the enclosure. Screw off bolts connecting enclosure and pump wheel. Disconnect driving worm wheel with shaft from enclosure. Put away three wood columns and slowly put down enclosure in scoop tube direction. Screw off bolts fixing driven worm wheel and press it down. There are two holes on driven shaft flange. Disassemble the inwards opening spring clamp through the inside bore diameter and draw off positioning bolts. From scoop tube chamber, draw off scoop tube and its positioning sleeve. At this point, enclosure can only be removed through scoop tube chamber. Take off scoop tube chamber in horizontal level and loosen bolts. Upper part of scoop tube chamber can be disassembled to give convenience to disassembly of bearing bush and measuring point 9, 10, 11, 12 of the thrust bearing.



3.3.4.11



Disassembly of input shaft includes following steps:



3.3.4.12



a)



Loosen fixing bolt on bearing cover of bush 1.



b)



Bind measuring point 1 and 2 of bearing on bearing bush together with binding wire (minimum diameter is Φ1mm).



c)



Lift input shaft away from enclosure and put it on a bed timber.



d)



Remove binding wire and bearing bush from input shaft.



Clean up and check coupler components 1)



Clean all rotating components after disassembly.



2)



Check driving worm wheel and driven worm wheel (blades resonance test).



3)



Check wear condition of scoop tube mechanical mechanism and functions of it. Check to see whether necessary to change a new fusible plug or not. Examine conditions of all bearings.



4)



Before slide bearing is reassembled, installation surface of shaft and bearing has to be polished.



5)



Clean waste sealing gel away from sealing surface.



6)



Flush oil tank and remove oil and mud residue and sealing gel residue.



3.3.4.13



Reassembly



3.3.4.13.1



Reassembly of coupler rotor components includes following steps: a)



Assemble thrust bearing bush 8, 9, and 10 according to marks. Page 152 of 241



b)



Put scoop tube chamber into its exact space position.



c)



Assemble upper and lower parts of the chamber and bind them together.



d)



After painting the sealing gel, assemble output shaft end cover.



e)



Screw on the fusible plug tight onto the drum. The drum should be installed back to its working position through the chamber.



f) Assemble scoop tube and its guide apparatus into chamber. Positions are in accordance with the positioning bolt holes.



3.3.4.13.2



3.3.4.13.3



g)



Assemble positioning bolts and opening spring clamp.



h)



Put in driven worm wheel and screw it tight enough.



i)



Lift enclosure and support it with three wood rods.



j)



Assemble driving worm wheel onto driving shaft and tighten it onto enclosure.



Reassembly of coupler rotor components includes following steps: a)



Assemble bush 5 and 6 and tighten them with binding wire.



b)



Lift rotor components.



c)



Paint lower part of flange surface with sealing gel.



d)



Put rotor components back into enclosure and remove the binding wire.



e)



Assemble thrust bush base, thrust bush, thrust disc, and bearing end cover.



f)



Install control stem.



Reassembly of input shaft includes steps: a)



Tighten bush 1/2 and bush 3/4 with binding wire.



b)



Lift input shaft and install it into enclosure.



c)



Remove binding wire.



3.3.4.13.4



Assembly of main oil pump.



3.3.4.13.5



Installation of auxiliary oil pump.



3.3.4.13.6



Installation of the enclosure cover.



3.3.4.13.7



Position adjusting of scoop tube includes steps: a) Install position adjusting ring on coupler enclosure and tighten it onto adjusting stem with positioning bolts.



3.3.4.13.8



b)



Put in measuring rule bracket and pointer at position of scoop tube according to their original positions.



c)



Connect link lever of actuator with adjusting link lever. Note that there is no adjusting limit on the scoop tube, but the adjusting limit is on the actuator.



Other work includes: a)



Check alignment of primary mover and driven machine.



b)



Connect coupling and install protection shield.



Page 153 of 241



3.3.4.14



c)



Install disassembled pipelines and leg wires.



d)



Fill in working oil again.



Quality standards (1) Bearing clearance Table



Clearance parameter of hydraulic coupler bearings Bearing number



Size



1



2



3, 4



5



6



7



8, 9



10



Φ105



Φ115



Φ85



Axial clearance



Φ90



Shaft diameter



Φ140



Φ140



Axial clearanc e



Min



0.21



0.21



0.200



0.17



0.17



0.088



0.200



0.094



Max



0.275



0.275



0.319



0.232



0.23 2



0.14



0.324



0.145



0.295



0.295



0.619



0.252



0.25 2



0.160



0.624



0.165



Clearance value for exchanging bearings



(2) Axial clearance between pump wheel and worm wheel is: 4.5-5.0mm. (3) Radial run-out and end face run-out of pump wheel rotor and worm wheel rotor should be: ≤0.03mm. (4) Radial shaking degree of rotor and shoulder end face deviation should be ≤0.03mm. (5) Speed raising gear basic end face deviation should be ≤0.02mm. (6) Top tooth radial shaking degree of speed raising gear should be ≤0.05mm. (7) Thrust disc end face deviation should be≤ 0.04mm. (8) Cooperative clearance between pump wheel and worm wheel sleeve should be within range of: 0.03-0.09mm. (9) Speed raising gear interface area along gear width should be ≥75％, and it should be ≥65％ along the gear height. (10) Side clearance of speed raising gear should be 0.30-0.45mm. (11) Contact area of thrust pad should be ≥75%. (12) Thickness deviation of thrust pad is ≤0.02mm. (13) Connecting bolts and screws between driving torque and power should be tight and secure, no loose, no deformation, no crack or damage. (14) Blades of pump wheel and worm wheel should have no crack and damage.



Page 154 of 241



(15) Babbitt alloy on worm wheel and its sleeve should have no crack or detachment. (16) Total radial clearance between worm wheel and oil chamber should be within 0.30-0.50mm. (17) No horizontal slot, scratch or damage exists on enclosure and oil tank flange interface. (18) Scoop tube port has no defects like collision, dishing or gap. (19) Assembly tension of bearing and oil chamber has to be within 0.03-0.05mm. (20) Working clearance between scoop tube and its sleeve is within 0.03-0.05mm. They have to match easily without any jamming. (21) Total radial clearance between worm wheel sleeve and oil chamber is within1.001.10mm, and surrounding has to be even and equal. (22) Total working clearance between sequential valve core and valve sleeve is within 0.03-0.05mm. These parts have to be smooth without any galling or jamming. (23) There should be no defects like crack, tooth loss or undercut. (24) Quality standards of relief valve are same with sequence valve. (25) Single side axial clearance of lubricant oil pump gear shaft is 0.04-0.07mm. (26) Tooth side clearance of gear oil pump is 0.10-0.20mm. (27) Bearing bush clearance of gear oil pump is 0.08-0.12mm. (28) Tooth interface contact of gear oil pump is above 75% without any deviation. (29) Shaft turning after all rotors being installed is easy with no blockage or wear. (30) Installation of scoop tube and control stem: one free tooth. (31) Axial clearance of thrust pad is 0.25-0.30mm. (32) Axial run-out is 0.20-0.30mm. (33) Axial distance between sealing ring and sealing end cover of big gear rotor is ≥1.5mm. (34) No leakage occurs after oil cooler being tested with pressure for 5 min. (35) Lubricating oil pressure is around 0.25 MPa. (36) Quality center requires seeing parts of feed water pump quality standards. 3.3.5



Condensate pump



3.3.5.1



Construction Introduction Condensate pump is a kind of vertical pump manufactured by Changsha Water Pump Cop. Ltd. It mainly collects condensate water in condenser and transports it into gland seal heater and LP heater for heating. After this process, it is sent into HP deaerator to satisfy demand of boiler feedwater. This pump is composed of three main sections, which are respectively cylinder, working section and water outlet section. Cylinder of pump is roll-welded with stainless steel plates (20/1Cr18Ni9Ti). Working section consists of pump rotors (six



Page 155 of 241



stages of impellers allocate in same direction) and deflecting casing that is forms deflecting space in outer space. Rotating section of pump consists of impeller, pump shaft, key, shaft bushing, and inducer. Water outlet section is composed of reducing elbow with 90°. Floating type gland seal device and relief hole are located on outlet base. For each unit, there are two condensate pumps with 100% capacity. One is in operation while the other is standby. Condensate pump is driven by constant speed motor directly. Water flow is controlled by control valve behind the pump. When running pump trips due to emergency trip, standby pump activates automatically. Pump is of centrifugal vertical &outer cylinder type that is located in a pit with 6-stage guide vanes. Pump body is located inside outer cylinder with mounting bedplate. It is achieved by connecting pressure water pipes with spew elbow by bolts. The pump comprises of components like outer cylinder, shell body inside cylinder, rotor components and gland seal components. The rotor components are supported by guide bearing in radial, and bearing is lubricated by self-conveyed media. Gland seal is of mechanical seal type. Axial thrust of condensate pump is bore by pump proper. On this condition, there are one thrust adjusting roller bearing and one deep groove ball bearing on pump proper. Weight of axial thrust and rotor is bore by thrust adjusting roller bearing. 3.3.5.2



3.3.5.3



Maintenance period A



Overhaul period: 3 years



B



Repair period: 1 year



Maintenance items (1) Jumping components; Overhaul items



Minor Repair items



and



clearance



inspection



of



rotor



(2) Check and calibration of pump shaft. Inspection and repair of moving and stationary blades. Change if necessary; (3)



Radial bearing inspection and replace;



(4)



Inspection and modification of thrust bearing;



(5)



Inspection and replace of gland seal.



(1)



Inspection and replace of bearing lubricating oil;



(2)



Defects removal.



3.3.5.4



Maintenance technology and quality standards



3.3.5.4.1



Disaseembly of pump includes following steps: (1) Remove the bolts between motor and pump and lift out motor and place it on predesignated timber bed. (2) Remove plug of 1/2 inch at lower part of thrust bearing. Drain residual lubricating



Page 156 of 241



oil in the thrust bearing by connecting a temporary pipe. (3) Remove pipes of all gauges and pipes of sealing water and cooling water. Loosen bolts connecting pump outlet pipe flange and take out sealing gaskets at joints. (4) Remove bolts connecting pump and outer enclosure. Lift up pump body in vertical direction and place it onto an installation brace with appropriate height or an installation pit. Firm the rotating part of pump with gaskets or cushions. (5) Take apart coupling, bearing cover, thrust ring and all bearings sequentially. . (6) Lift out thrust bearing seat as a whole body together with cooling disc, sealing oil tank, and thrust pad which will be disassembled individually. (7) Lift out motor bracket. (8) Respectively remove sealing gland seal, water return pipe and bearing. Take apart sealing mechanism as a whole and disassemble parts inside it individually. (9) Pull out throttling bushing with three lengthened bolts of M10 or a rod with M10 threads on front section. (10) Place remained parts in horizontal direction. One end with pump outlet flange facing downwards is put on a wooden board or rubber cushion. Another end should be balanced with a wooden block. Shaft end of driving end should be placed in horizontal with help of cushion or gaskets. No collision or hitting is permitted during lifting process. (11) Respectively take apart impeller nuts, inducers, adjusting gaskets, inlet nozzles, inducer chamber, and primary impeller keys. (12) Remove guide vane enclosure, impeller positioning shaft bushing, taper sleeve, primary impeller, and keys after sealing water filling pipe is disassembled. Respectively disassemble each stage in this way. During disassembly process, wooden blocks have to be placed between rotor and stator to keep relative balance in case of scratching damage of components. (13) Remove pilot enclosure, bearing components, straight pipe and adjusting gaskets. (14) Lift out shaft carefully and place it well with necessary cushions. Wooden cushions of V type have to be no less than 4 ones. (15) Loosen coupling of sleeve. 3.3.5.4.2



Coupling run-out measurement



3.3.5.4.2.1 Before pump is disassembled, divide coupling circle into 8 equal parts and mark them in sequential number. Install dial indicator and position measuring stick to 1. At this point, the measuring stick and outward circle of coupling are in vertical angle. Spin rotor in rotating direction to measure it at these points. Reading number at initial position after a rotation circle has to accord with that of initial measurement.



Page 157 of 241



Otherwise, ascertain possible reasons and measure again. Maximum shaking degree is maximum difference between two ends of impeller diameter. 3.3.5.4.2.2 Coupling Marking Make relative marks on pump wheels, motor wheels and adjusting gaskets before coupling is disassembled. Installation has to accord with marks made before. Mark disassembled wheel pins, bolts and corresponding bolt holes to avoid unnecessary mistakes. 3.3.5.4.3



Centering of coupling and wheel space reexamination Before coupling is disassembled and after it is reassembled, center the coupling and reexamine wheel space. Specific examining methods are as follows: 1） Coupling center calibration. Install three dial indicators at coupling end faces and around its circle. Two measuring sticks of dial indicators point to coupling end faces, and the other one points around coupling circle. Install indicator bases onto motor coupling. After adjusting sticks, spin motor coupling. For every 90°, measure the deviation between coupling circle and end face and make relative records. Use adjusting bolts on bases to adjust motor position, and keep deviation within permitted range. Use proper thick cushion between motor and pump interface to adjust deviation. If deviations at these three positions have reached requirement, use bolts to connect coupling. After pump shaft is slightly lifted, spin motor and pump around 180°. Recalibrate coupling center. Make an average value of two times of calibration. The standard for center calibration is no more than 0.05mm for circularity, and no more than 0.05mm for surface. 2） Reexamine coupling space. Measure the plane distance between two couplings and thickness of adjusting ring. Difference between two values should be equal as half of total pump shaft lifting value. If difference is too big, the adjusting ring should be adjusted or exchanged. Parallelism at two ends of adjusting ring is no more than 0.015mm.



3.3.5.4.4



Before disassembling coupling, take apart (two ears) nuts.



3.3.5.4.5



Respectively loosen connecting bolts and nuts on coupling. However, two backup bolts should be located at position of 180° and loosen them afterwards. Make sure rotor starts being lowered. After it is done, measure clearance between adjusting nuts and motor coupling end face. This number is lifting height of the pump rotor.



3.3.5.4.6



Check alignment of water pump and motor. Measure clearance between shaft and mechanical seal sleeve and use the measured value to adjust alignment for perfect aligning.



3.3.5.4.7



Take apart connecting bolts and nuts on motor and spew elbow, and then lift the motor onto temporary location. Pay close attention to the whole process because of heavy weight of motor. For placement of motor, a bracket should be used to prevent coupling at shaft ends touching ground, and also motor cannot fall down in this way.



3.3.5.4.8



Loosen stop screws on backup cap of pump coupling and take apart the cap. Manual hoist or chain fall can be adopted to lift coupling. After coupling is removed, paint a coat of antirust paint or lubricating oil on shaft and shaft holes of coupling. Thread at shaft end should be protected well in case of damage.



3.3.5.4.9



Remove mechanical seal and take it out as a whole set. Refer to Instruction of Mechanical Seal.



Page 158 of 241



stopper gaskets on bolts and



3.3.5.4.10



Install lifting bolts on shaft top part. Use manual hoist or travel crane to lift and lower the rotor. Measure and make a record of full displacement of the rotor.



3.3.5.4.11



Take apart nuts connecting stuffing box and spew elbow. Screw top cover bolts into screw hole. Slowly pull out stuffing box together with guide bearing and relief sleeve at a constant speed and distance.



3.3.5.4.12



Take apart clamping screw connecting spew elbow and outer cylinder during pump body lifting process. Since there are vibration resistant device (fastening bolts) installed between outer cylinder and inside shell, it needs great attention and care to lift pump body gently and vertically to prevent collision to vibration resistant device. At slot of outer cylinder, a cover board should be placed to prevent foreign matter from falling into the cylinder. Besides, an ENTRY FORBIDDEN area should be enclosed to response for personnel’s safety.



3.3.5.4.13



After pump body is lifted up, transport it to designated disassembly location, and it has to be placed in horizontal.



3.3.5.4.14



When disassembling spew elbow and pressure water connecting pipe, lift the spew elbow horizontally and pull it out gently. After spew elbow is removed, use a lifting jack to support the shaft in case of shaft being bent.



3.3.5.4.15



Disassembly of inner enclosure and rotor part includes following steps:



(1)



When disassembling pressure water pipe, it is better to remove inner enclosure with connection to pipe, to ensure safety as there is no guide bearing inside;



(2)



If there is sleeve (intermediate) coupling, pay attention to thread seizing problem during disassembly;



(3)



Install bolts on suction bell to force out suction bell. There is guide bearing installed inside the bell. Remove it gently in horizontal direction.



(4)



Loosen locknut at shaft ends, and respectively pull out sleeve, keys, and primary impeller;



(5)



Take apart pump body, cover, sleeve, impeller, guide vane, middle section, and final guide vane;



(6)



As pressure water pipe is connected to spew section, pull out shaft heading forward spew side. To facilitate pulling-out of the shaft, sleeve adhered on shaft cannot be removed;



(7)



Remove pressure water connecting pipe and spew section;



(8)



Sleeve on middle part of bearing can be pulled out if necessary. As there are lock screws on sleeve nuts, first remove positioning bolts and then take apart the sleeve. After above mentioned steps are finished, put all disassembled components on plane board in case of damage or loss.



3.3.5.5



Cleaning of components After disassembling, clean all components thoroughly following steps as mentioned:



Page 159 of 241



(1)



Use oil stone to polish interfaces of components and packing chambers;



(2)



Carefully polish on movable fitting parts of rotating components by oil stone;



(3)



Use steel brush to clean enclosure, impeller, guide vane, and intermediate seciton flowing parts or use emery paper to polish them;



(4)



If there is scaling at water flowing parts, use solutions like chloroethylene to remove it;



(5)



Carefully clean shaft and all components which work with shaft. Otherwise, any engagement may cause unvalidity of components;



(6)



Completely remove pollutants in labyrinth slot and water guiding slot at movable fitting parts;



(7)



Make sure throttling hoels for pipe distribution and components with small holes not jammed.



3.3.5.6



Inspection of components



3.3.5.6.1



Check following items of rotor components



(1)



Whether there is wear or scratch on movable fitting parts or fitting parts. Measure sizes of movable fitting parts and make a record. Refer to movable fitting part clearance table;



(2)



Whether there is abnormities like wear or deformation suction port and flowing part;



(3)



Whether there is wear or blockage at shaft movable fitting parts or thread part;



(4)



Whether vibration value of shaft is within permitted value and make a record;



(5)



When shaft is bent, rectify it with reference to related methods.



3.3.5.6.2



at



impeller



Check following items of components of pump body (flow guiding) and inner enclosures.



(1)



Whether there is wear, corrosion or collision damage on movable fitting parts or fitting parts. Measure sizes of movable fitting parts and make a record. Refer to movable fitting part clearance table;



(2)



Whether there are defects like wear or leakage at component interfaces and packing parts;



(3)



Whether there is abnormal wear or hitting at flowing part of pump (especially components like guide vane);



(4)



Whether installation bolts on components which are not disassembled completely (such as bearing, sealing ring or lined sleeve) are loose or not.



Page 160 of 241



3.3.5.6.3



Check following items of bearing components:



(1)



Whether there is wear or scratch on movable fitting parts or fitting parts. Measure sizes and make a record. Refer to movable fitting part clearance table;



(2)



Whether there is wear or scratch on bearing movable parts (shaft bushing). Whether there is abnormality of fitting condition. Measure sizes and make a record. Refer to movable fitting part clearance table;



3.3.5.6.4



Check following items of coupling:



(1)



Whether there is deformation or wear of coupling (including lengthened coupling) and adjusting nuts;



(2)



Whether there is abnormality on connecting bolts and nuts, and whether bolt holes are normal or not;



(3)



Whether there is scratch, concavo convex or corrosion on centering surface and matching surface;



(4)



Whether there is abnormal concavo convex or damage occurring along pipelines or other parts, and whether there is foreign matter mixing in, which may consequently causes jamming problem.



3.3.5.7



Assembly of pump Recheck components interior and interfaces to see whether there are defects like collision damage or damage on interface when improper components are to be replaced or repaired. Assembly work can be carried out after all components are ready and complete. Assembly sequence is almost the reverse order of disassembly steps. However, pay attention to following aspects:



3.3.5.7.1



Complete Assembly



(1)



Assembly positions, quantities, sizes, and material of O sealing rings, sealing gaskets and cushion blocks have to be in accordance with General Assembly Drawing. Assemble ideal components in sequence. Pay attention to surfaces of O ring and sealing gaskets in case of collision or omission during installation;



(2)



Apply solid lubricant agent (like molybdic sulfide) on surfaces of each movable fitting part, fitting parts with shaft and keys as well as threads of bolts;



(3)



Pay attention to flake-off of keys and other components;



(4)



Assemble in accordance with centering marks and number of stages if there are marks or numbers on the components;



(5)



Prevent any foreign matter entering into pump during assembly;



(6)



Regarding positioning bolts on shaft bushing, tighten them only when they are installed properly in places.



3.3.5.7.2



Before water pump body is installed into outer enclosure, make sure horizontal degree of installation basis plate of outer enclosure. Horizontal degree has to be lower Page 161 of 241



than 0.05/1000. 3.3.5.7.3



Make sure stopping gaskets (rings) or falling apart of bolts and nuts.



3.3.5.8



Quality standards Clearance permitted value



at different positions are bent in case of loose



Unit : mm Permitted maximum friction clearanc e



Minimum



Maximum



clearance



clearance



Outer edge of inducer



0.10



0.38



0.55



Front ring of primary impeller



0.34



0.41



0.60



Rear ring of primary impeller



0.34



0.41



0.60



Standard impeller ring



0.34



0.41



0.60



Guide bearing



0.25



0.38



0.55



Guide bearing between stages



0.25



0.38



0.55



Throttling bushing



0.42



0.48



0.65



Throttling guide bearing



0.12



0.24



0.45



Location



(1)



Matching tension between impeller and shaft is 0-0.02mm;



(2)



Single side clearance between guide bearing and shaft bushing is 0.005-0.21mm. Maximum value is 0.40mm;



(3)



Single side clearance between intermediate bearing and shaft bushing is 0.05-0.21mm. Maximum value is 0.40mm;



(4)



Matching clearance between shaft and shaft bushing is 0-0.05mm;



(5)



Total clearance of sealing ring is 0-0.55mm;



(6)



Clearance between inducer and inducer bushing is 0.2-0.35mm;



(7)



Rotor total run-out before inducer is installed is 8±1mm while that after inducer is installed is 4±0.5mm;



(8)



Maximum bending of each section of shaft is less than 0.03mm while maximum value of whole shaft is less than 0.05mm;



(9)



Shaking degree of impeller and inducer has to be less than 0.10mm;



(10)



Center of coupling: end face deviation is ＜0.05mm while deflection is ＜0.04mm;



Page 162 of 241



(11)



There is no steam corrosion or crack on pump impeller. Surface of bearing is smooth without crack. No crack or wear is on coupling. Interior and outer surface of each shaft bushing are smooth. Welding joint of intermediate connection pipe and each pump components have to be no defect like crack.



Common failures, causes, treatment, maintenance technology and quality standard Category



Items Incorrect rotation direction



No water drain s out



●



Lower flow



●



Lower lift



Cavitation Poor suctio Noise n



High shaft power



High temperature of bearing



Violent vibratio n



Follow the instruction to correct the motor wiring.



●



Open the air exhaust valve and system valves to feed liquid into the pump until all the air are exhausted.



Conveying liquid is not ● top up



Insufficient liquid in the ● suction pipe



●



Air entering the suction ● pipe



●



Air in liquid



the



Insufficient effective cavitation allowance The air in distribution



●



●



●



Solutions



●



●



●



●



●



●



Open the air exhaust valve on the suction pipe, feed the liquid into the pipeline until all the air are exhausted. Check the suction pipeline.



●



Treat it in accordance with the item 2, 3



●



Check the suction pipeline valves and the conical filter.



●



●



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Check suction



the



pipe sucked



is



The rated revolution ● can not be reached.



distribution system.



●



Speed is too high.



Insufficient outlet pressure



The jammed meshes of conical filter ● exceed the limit



The seal ring, spindle sleeve is abraded.



damaged Impeller abrasion.



Check the motor in accordance with the instruction.



●



●



handle it based on the item 8.



●



Close the outlet valve until the pressure can be adjusted. But the frequent above action will accelerate the abrasion.



●



Check the differential pressure indicator before and after the filter to see whether its reading is within the specified range. If not, flush and clean up the filter.



●



Replace the sealing rings, spindle sleeve, parts. Check whether the rotor deviates or foreign matters enters or not.



●



Replace the impeller, check whether the rotor deviates



or



Page 164 of 241



or foreign matters enters.



Excessive leak from



Check the components inside the pump. Replace the damaged components.



●



The spindle core is in poor condition Spindle bending



●



The rotor contacts the fixed components.



●



●



●



Calibrate the spindle



●



Rotor is unbalanced.



Unstable foundation



Motor vibration The poor support for the pipeline



●



Check the bearing abrasion. If the clearance exceeds the allowable value, it needs to be replaced.



●



Perform the dynamic balance test on the rotor. Calibrate the rotor balance.



●



Check and strength the foundation.



●



Check the motor based on the instruction/.



●



Page 165 of 241



the



Check the spindle meets the requirements or not, the spindle bends or not.



●



The bearing wear



Realign shaft.



Check the support point of the valve



and distribution pipelines connected with the pump.



connected with the pump



3.3.6



Vacuum pump



3.3.6.1



Overview It mainly serve as extracting the air in the condenser and the incondensable air in the exhaust steam from the condenser to form a certain vacuum degree and improve the unit output. Main equipment includes water ring motor, steam water separator, heat exchanger, steam ejector, foundation, pneumatic butterfly valve, stop valve, connective pipeline and valves, etc. The pump is driven directly. The motor is connected with the pump via coupling. The entire equipment adopts the closed circulation. In normal operation, the mixture of the air and the steam is sucked into the pump. The eccentric impeller compresses the mixture, the mixture will go out through the outlet and enters the steam water separator to be separated. The separated air is discharged outside the pump house through the check valve. The left liquid enters the pump for recycle via the heat exchanger to reduce the temperature. Working principle: The impeller is installed inside the pump eccentrically. Fill water into the pump until it reaches certain level. The water inside the pump will form a revolving ring under the centrifugal force when the impeller rotates. The sealed chest is built up by the blades and the distributor on both sides. In the first half of revolution, the seal volume expands and air is sucked into the pump through the air holes. In the second half revolution, seal volume will be contracts, and air exhausts through the air vent with some water. In order to keep the constant water ring, continue to fill water into the pump during the operation. Additionally, in order to prevent inner components & parts from corrosion or erosion caused by the sea water sucked into the vacuum pump, the water drain tank is arranged before the vacuum pump. The automatic level controller is provided for the water drain tank. When the level reaches the limit, the vacuum pump will stop automatically, the pneumatic butterfly valve at the inlets of both water drain tank and the vacuum pump will stop automatically. The water tank is vertical, with a volume of 1m3 and a design pressure of 0.6MPa. Its material is carbon steel lining rubber which can resist seawater corrosion. Water tank should have water discharging valve at the bottom and air discharging valve at the top.



3.3.6.2



Inspection period



3.3.6.2.1



Overhaul period: It is 3 years for the water ring type mechanical vacuum pump.



3.3.6.2.2



Maintenance period: It is 4-8 months for the water ring type mechanical vacuum pump.



Page 166 of 241



3.3.6.3



Inspection & Repair Items



3.3.6.3.1



Overhaul items 1） Water ring pump disassembly 2） Heat exchanger inspection after disassembly 3） Separator automatic make up water valve disassembly 4） Steam exhaust check valve disassembly



3.3.6.3.2



Maintenance items 1） Bearing disassembly checking 2） Gland seal disassembly checking 3） Heat exchanger disassembly checking 4） Defects elimination



3.3.6.4



Maintenance procedure and technology standard Water ring vacuum pump maintenance procedure



3.3.6.4.1



Disassembly



3.3.6.4.1.1 Before the disassembly, prepare the spare parts, tools, and select repair site, also prepare the parts container; 3.3.6.4.1.2 Inform the relevant departments, disassemble and remove the motor power, dismantle connecting elastic dowel pin of the coupling, recheck the center, remove the motor. Record the central values; 3.3.6.4.1.3 Dismantle the flange at the inlet and outlet of the pump and all the pipes connecting with the pump, I&C components and all kinds of valves, etc; 3.3.6.4.1.4 Release the anchor bolts and transport the pump to the designated overhaul site, and pull out the pump side coupling with special tools or heating method; 3.3.6.4.1.5 Dismantle the joint of the end covers of both sides; 3.3.6.4.1.6 After the demolition of the seal ring of both sides, loose the fixing bolt of the bearing caps, at the same time remove the end caps on both sides and the oil ring and retaining ring; 3.3.6.4.1.7 Respectively, dismantle the sleeves of the bearings, the bearings, inner bearing blankets and centrifugal disk on both sides; 3.3.6.4.1.8 Remove the stuffing cover, stuffing, stuffing ring, and remove the stuffing sleeve; 3.3.6.4.1.9 Dismantle and inspect the cover. Open side cover fixing bolts, and all bolts connecting with the pump body, and mark them. Steadily remove the side cover and lay the side panels in a safe place, measure and record the thickness of the jointing washer; 3.3.6.4.1.10 Pull out the rotors stage by stage and lift away the pump proper. 3.3.6.4.2



Cleaning Inspection



3.3.6.4.2.1 Visual inspection for shaft. There should be no scars and corrosion of the rotor, all the Page 167 of 241



thread should be normal, all the key groove is smooth without burr; blades should be without abrasion, steam corrosion and broken ; 3.3.6.4.2.2 Check the bearing clearance, and the abrasion situation of the sleeves and rollingbody, and if they are confirmed able for continue use, apply Glycerol to them and put them at clean area for re-installment. Bearing clearance ≤ 0.25mm; the sleeves are with no damage, and the rolling body is with no point corrosion; 3.3.6.4.2.3 Inspect the easy-to–damage such as the sealing ring, retaining rings, oil ring, centrifugal disc, stuffing sleeve, water sealing ring. These parts should have no abrasion, no cracks and no fracture. Replace if necessary. 3.3.6.4.2.4 Inspect the side cover, side panels, valves and valves platen. These parts should be with no cracks and trachoma, and the valve should be replaced one by one; 3.3.6.4.2.5 Impeller inspection. If there are serious abrasion and steam corrosion replace it, the impeller should have abrasion and steam corrosion; 3.3.6.4.2.6 Measuring the shaft bending. Shaft bending value should ≤0.03mm; 3.3.6.4.2.7 The shift degree and the swinging degree of the jointing components should meet the requirements. The rotor swinging degrees: