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DL/T 932-2019: Guide of operation and maintenance of the condenser and vacuum system
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Guide of operation and maintenance of the condenser and vacuum system
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DL/T 932-2019
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| DL/T 932-2005 | English | 879 |
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Guide of operation and maintenance for the condenser and vacuum system of power plant
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Basic data | Standard ID | DL/T 932-2019 (DL/T932-2019) | | Description (Translated English) | Guide of operation and maintenance of the condenser and vacuum system | | Sector / Industry | Electricity & Power Industry Standard (Recommended) | | Classification of Chinese Standard | F23 | | Classification of International Standard | 27.100 | | Word Count Estimation | 24,234 | | Date of Issue | 2019 | | Date of Implementation | 2019-10-01 | | Issuing agency(ies) | National Energy Administration | DL/T 932-2019: Guide of operation and maintenance of the condenser and vacuum system---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Guide of operation and maintenance of the condenser and vacuum system
ICS 27.100
F 23
People's Republic of China Electric Power Industry Standard
Replace DL/T 932-2005
Guidelines for Operation and Maintenance of Condenser and Vacuum System
2019-06-04 released
2019-10-01 implementation
Issued by National Energy Administration
Table of contents
Foreword...II
1 Scope...1
2 Normative references...1
3 General...1
4 Operation and maintenance requirements...1
5 Operational monitoring and testing...3
6 Optimization of Cold End System Operation...6
7 Vacuum system failures and causes...7
8 Inspection and maintenance...11
Appendix A (Normative Appendix) Water quality requirements for condenser cooling pipes of different materials...13
Appendix B (informative appendix) Condenser operating characteristic supervision curve...14
Appendix C (informative appendix) Calculation of overall condenser heat transfer coefficient...15
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009 "Guidelines for Standardization Work Part 1.Standard Structure and Compilation".
Please note that certain contents of this document may involve patents. The issuing agency of this document is not responsible for identifying these patents.
This standard replaces DL/T 932-2005 "Guidelines for Operation and Maintenance of Condenser and Vacuum System". Compared with DL/T 932-2005, except for editorial
The main technical changes are as follows.
-Increase the operation and maintenance requirements of the vacuum pump;
-Added the main failure reasons of the vacuum pump;
-Increased the operation and maintenance requirements of the dual back pressure condenser.
This standard was proposed by the China Electricity Council.
This standard is under the jurisdiction of the Power Plant Steam Turbine Standardization Committee.
Drafting organizations of this standard. Xi'an Thermal Power Research Institute Co., Ltd., Xi'an Xire Energy Saving Technology Co., Ltd.
The main drafters of this standard. Ju Wenping, Ma Tingshan, Cheng Dongtao, Xu Pengjiang, Wang Hao, Yu Xinxin, Mou Chunhua, Zou Yang, Lv Kai.
This standard was first issued in.2005 and this is the first revision.
The opinions or suggestions during the implementation of this standard will be fed back to the Standardization Management Center of the China Electricity Council (Baiguang Road 2nd, Beijing)
Article No. 1, 100761).
Guidelines for Operation and Maintenance of Condenser and Vacuum System
1 Scope
This standard specifies the general principles and requirements for the operation and maintenance of surface water condensers and vacuum systems for steam turbine generator sets in power plants.
This standard applies to water-condensing steam turbine generator sets.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this document.
For undated references, the latest version (including all amendments) applies to this document.
GB/T 5248 Copper and copper alloy seamless pipe eddy current testing method
GB/T 7735 Steel pipe eddy current inspection method
GB/T 12969.2 Eddy current inspection method for titanium and titanium alloy pipes
DL/T 561 Water and Vapor Chemical Supervision Guidelines for Thermal Power Plants
DL/T 581 Condenser rubber ball cleaning device and circulating water secondary filtration device
DL/T 712 Guide for Selection of Materials for Condenser and Auxiliary Equipment Cooler Tubes in Power Plants
DL/T 794 Guidelines for chemical cleaning of boilers in thermal power plants
DL/T 1078 Operational performance test procedure for surface condenser
3 General
3.1 The design, manufacturing and installation units shall create conditions for the implementation of this standard, and create opportunities for the reliable and economic operation of condensers and vacuum systems.
Favorable conditions.
3.2 When the power plant compiles the operation regulations, the following technical data should be attached.
a) The influence curve of unit back pressure on steam turbine heat rate;
b) Curve of influence of unit back pressure on power generation;
c) Condenser characteristic curve under off-condition;
d) Operating characteristic curve of circulating water pump;
e) The change curve of the performance of the pumping equipment and the cooling water temperature or working steam parameters;
f) Water quality index requirements such as the oxygen content of condensate.
4 Operation and maintenance requirements
4.1 Condenser
4.1.1 The tightness of the vacuum system is qualified.
4.1.2 The condenser is clean in good condition.
4.1.3 The cooling water flow meets the design requirements.
4.1.4 The steam pressure of the shaft seal is normal.
4.1.5 The condensate subcooling is qualified.
4.1.6 The heat transfer end difference of the condenser is within the design range.
4.1.7 The condensate water quality is qualified.
4.1.8 The water level of the hot well is normal.
4.1.9 The pressure of the condenser is measured with an absolute pressure gauge, and there is no problem of water accumulation in the pressure measuring tube of the condenser.
4.1.10 After the unit is overhauled, the condenser and vacuum system should be filled with water for leak detection.
4.1.11 All welds on the condenser body are tight and leak-free.
4.1.12 The compensator connecting the condenser throat and the low pressure cylinder is tight and leak-free. When the rubber belt compensator is equipped with a water seal, the water seal is intact.
4.1.13 All pipe welds connected to the condenser body shall be tight and leak-free.
4.1.14 The steam side drain valve of the condenser is tight and leak-free.
4.1.15 The cooling pipe has no perforation leakage.
4.1.16 The expansion joints and welds of the cooling pipe and the tube sheet of the water chamber shall be tight and leak-free.
4.1.17 The connection between the condenser water level gauge and the water level transmitter is tight and leak-free to ensure normal water level control and water level indication.
4.1.18 The action of the condenser water level switch is reliable.
4.1.19 The condenser water level should be within the normal working range.
4.1.20 The vacuum interlock protection is normal.
4.1.21 Appropriate anti-corrosion measures shall be taken for the condenser water chamber and tube sheet.
4.1.22 The water quality requirements for circulating cooling water should meet the relevant regulations in DL/T 561, and the cooling pipe flow rate requirements should meet the relevant regulations in Appendix A.
Regulations.
4.1.23 When the unit is out of operation for more than 3 days, the cooling water in the condenser water chamber and the condensed water in the hot well shall be drained in time after the unit is shut down.
4.1.24 When the unit is out of service for more than 1 month, the condenser should be dried and maintained in time after the unit is shut down.
4.1.25 For condensers with half-side cleaning function, the partition seals between the water chambers should be tight and leak-proof.
4.1.26 The pressure difference between the high and low pressure condensers of the dual back pressure condenser reaches the specified value. High and low pressure condenser pressure difference and condenser heat load
The load, cooling water temperature, cooling water flow rate and condenser working status are related, and the condensing steam under different boundary conditions and normal operating conditions of the condenser
The pressure difference of the generator is defined as the specified value, and the supervision of the unit is strengthened during operation.
4.2 Circulating cooling water and rubber ball cleaning system
4.2.1 The circulating water pump works normally, and the flow rate and outlet pressure can meet the requirements of various working conditions of the unit.
4.2.2 For closed loop cooling system, the cooling capacity of the cooling tower should meet the design requirements.
4.2.3 The operating pressure difference between the primary filter and the secondary filter of the circulating water is not greater than the specified value, and the water quality requirements can be guaranteed.
4.2.4 The water chamber should be kept clean to improve the heat transfer effect of the cooling pipe and prevent debris from blocking the cooling pipe.
4.2.5 For the condenser water chamber with siphon effect, a water chamber vacuum pump should be installed, and the water chamber vacuum pump should operate reliably, and the water chamber should be drawn out in time.
Set gas.
4.2.6 For the condenser water chamber without siphon effect, the water chamber should be fully exhausted when starting, and periodically exhausted during operation.
4.2.7 When the condenser is in normal operation, the circulating water inlet valve is fully opened, and if necessary, adjust the outlet valve opening to meet the system operation requirements.
4.2.8 The rubber ball cleaning device can be put into normal operation and work effectively, its rubber ball quality, throwing quantity, cleaning time interval and cleaning duration and
The technical indicators such as ball recovery rate shall comply with the relevant provisions of DL/T 581.For conditional power plants, the rubber ball cleaning interval and cleaning
The duration should be determined according to the cooling pipe cleanliness factor.
4.2.9 The quality of circulating water shall be monitored and measured regularly, and effective measures shall be taken to ensure the quality of circulating water when necessary.
4.2.10 There is no obvious fouling on the inner surface of the condenser cooling pipe.
4.3 Condensate system
4.3.1 The condensate pump should meet the requirements of the flow and head of each load of the unit under variable frequency operation or industrial frequency operation, and be able to
The steam turbine operates normally under low water level conditions without cavitation and vibration damage.
4.3.2 The condensate pump inlet filter (if any) should be checked for blockage in time and cleaned up. For the process with automatic backwash function
The filter should ensure its function and be put into operation frequently so that the pressure difference of the filter does not exceed the set value.
4.3.3 If the condensate pump shaft seal adopts a mechanical seal, the gap should be adjusted to meet the regulations to prevent wear and cause the gap to be too large. Packing dense
For sealing, the sealing water and cooling water should be adjusted appropriately, and the packing should not be too loose or too tight to avoid air leakage or excessive wear.
4.3.4 The flanges, exhaust valves and traps from the hot well to the inlet section of the condensate pump are tight and leak-free.
4.3.5 The condensate recirculation door's valve stem, flange and pipe welds are tight and leak-free.
4.4 Shaft seal steam system
4.4.1 The shaft seal steam system is designed reasonably and the steam supply and return to the shaft seal are smooth.
4.4.2 Each shaft seal inlet steam regulating valve operates normally.
4.4.3 Adjust the shaft seal steam supply parameters in time according to the operating conditions to maintain the slightly positive pressure operation of the shaft seal system.
4.4.4 The shaft seal heater fan works normally.
4.4.5 The water level of the shaft seal heater is normal.
4.4.6 The height of the water seal in the drainage U-shaped tube of the shaft seal heater is reasonable.
4.5 Air extraction system
4.5.1 The vacuum destruction door of the condenser is tight and leak-free.
4.5.2 The vacuum pump and pumping equipment are working normally.
4.5.3 The air extraction method of the double back pressure condenser is arranged reasonably to avoid the mutual influence of the air extraction system between the high and low pressure condensers.
4.5.4 The water level of the steam-water separation tank of the vacuum pump is normal.
4.5.5 Adjust the cooling water flow to make the cooling water temperature of the pumping equipment as close to the design value as possible.
4.5.6 The temperature of the working fluid of the vacuum pump should be as low as possible.
4.5.7 The vacuum pump has sufficient cooling water flow and sufficient working fluid flow.
4.5.8 The heat exchanger of the vacuum pump is clean and free of dirt and clogging.
4.5.9 If possible, use low-temperature water whose temperature is lower than the circulating water as the cooling water source of the vacuum pump.
4.5.10 The inlet pressure of the water jet air extractor is normal.
4.5.11 When the working water temperature of the water jet air extractor is higher than the normal value, the air extractor water tank should be supplemented with low-temperature cooling water in time.
4.5.12 Control the water level of the water tank of the water jet pump to be normal.
4.5.13 The working steam pressure of the steam ejector is normal. If it is lowered, the working steam inlet door should be properly opened to restore to the rated value, or
The operator switches the working steam to a steam source with a higher pressure level.
4.5.14 The drainage of the steam ejector is normal, and there is no cross flow.
4.5.15 Keep the filter screen in front of the aspirator nozzle clean.
4.5.16 Check that the cooling water temperature, cooling water flow, and cleanness coefficient of the intercooler of the multi-stage air extractor are normal.
4.6 Heater drain exhaust system
4.6.1 The operating water level of the low-pressure heater is normal.
4.6.2 The low-pressure heater is running and exhausting works normally.
4.6.3 The emergency drain regulating valve works normally without leakage.
4.6.4 The steam turbine body drain and pipeline drain entering the condenser should be closed during normal operation.
4.7 Low pressure cylinder of steam turbine
4.7.1 The facet of the low-pressure cylinder is flat and without deformation, tight and without leakage.
4.7.2 The clearance of the shaft seal of the low pressure cylinder meets the design requirements.
4.7.3 The safety door of the low pressure cylinder is tight and leak-free.
4.7.4 The welds, valves and connecting flanges on the exhaust pipe of the heater in the negative pressure section are tight and leak-free.
4.7.5 The low-pressure cylinder water spray cooling system works normally.
5 Operational monitoring and testing
5.1 Operation monitoring parameters
5.1.1 The parameters listed in Table 1 should be monitored during operation.
5.1.2 When the vacuum tightness index is unqualified, leak detection during operation should be carried out in time, or the condenser should be inspected for water filling by taking the opportunity of shutdown and maintenance.
Leakage; when the condenser pressure is greater than 15% of the design value under the assessment conditions, the condenser heat transfer characteristic test shall be carried out, and the test items shall be at least
Should include condenser pressure, cooling water inlet temperature, cooling water outlet temperature, condensate oxygen content, vacuum tightness, circulating cooling water flow,
Heat load, condenser cleanness coefficient, heat transfer coefficient, etc.
5.1.3 Refer to Appendix B for condenser operation supervision.
5.3 Condenser heat transfer characteristic test
5.3.1 Master the operating conditions of the condenser through experiments, and clarify the way to increase the vacuum of the condenser.
5.3.2 The condenser heat transfer characteristics test shall be carried out before and after the overhaul of the unit.
5.3.3 During the operation of the unit, if the condenser performance drops significantly, the condenser heat transfer characteristic test should be carried out.
5.3.4 During the test period, the condenser is required not to make up water, the system is in normal operation mode, and the unit load is stable.
5.3.5 The test instrumentation should comply with the relevant regulations of DL/T 1078.
5.3.6 See Table 1 for test measurement items.
5.3.7 Test items
5.3.7.1 Cooling water flow
5.3.7.2 Condenser heat load
5.3.7.3 Cooling water temperature rise
5.3.7.4 Condenser water side resistance
5.3.7.5 Condenser steam side resistance
5.3.7.6 Heat transfer end difference
5.3.7.7 Subcooling
5.3.7.8 Overall heat transfer coefficient
5.3.7.9 Operational cleanliness factor
5.3.7.10 Calculation of condenser pressure under different operating conditions. For a given cooling water flow rate, cooling water temperature and operating cleanliness factor,
Calculate the overall heat transfer coefficient under this working condition according to Appendix C; then according to the heat load of the condenser test or the heat level of the steam turbine unit provided by the manufacturer
Calculate the thermal load based on the balance parameters and make corrections in consideration of the operating conditions of the unit. Calculate the saturation temperature under condenser pressure by the following formula.
6 Optimization of cold end system operation
6.1 System equipment
Cold end system equipment includes steam turbine low-pressure cylinder, condenser, low-pressure heater operating under vacuum, circulating water pump, cooling tower,
Air extractor, rubber ball cleaning device, etc.
6.2 Optimization purpose
Through comparative tests under different unit loads, different air extractor operation modes, different cooling water temperatures and different cooling water flow conditions,
Determine the condenser pressure and operation mode when the difference between the increase in the output of the unit and the increase in the power consumption of the circulating water pump, air extractor and other equipment is the largest.
6.3 Optimization method
6.3.1 Unit micro-increasing output test
Under different unit loads, change the condenser pressure to obtain the relationship between unit output and back pressure.
6.3.2 Variable condition characteristic test of condenser
Under different heat loads, different cooling water temperatures and different operation modes of the air extractor, change the condenser cooling water flow to obtain the condenser pressure
The relationship between force and cooling water flow.
6.3.3 Power consumption test of cold end equipment
Under different operation modes of the aspirator, measure the power consumption of the aspirator; high and low speed configuration of the circulating water pump, different blade angles (blade angle adjustable
Pumps) and different frequencies (with inverters) and other configuration modes, measure the cooling water flow and circulating water pump power consumption, and obtain the power consumption increase of the equipment
The relationship of quantity.
6.4 Calculation of the optimal back pressure of the condenser
By solving the objective function with condenser pressure, cooling water inlet temperature and cooling water flow as variables, the optimal operating performance of the condenser is obtained.
Pressure. Under certain unit load and cooling water inlet temperature conditions, the difference between unit power increment and cold end equipment power consumption increment is the maximum
The condenser pressure is the optimal operating back pressure of the unit.
6.5 Determination of the best operating mode
According to the calculated optimal back pressure and the corresponding cooling water inlet temperature and cooling water flow rate, determine the air extractor and circulation under different working conditions
The best way to run water pumps and other equipment. Operators should adjust the operating parameters and system in time according to the best operating mode determined under different working conditions.
System equipment to ensure that the unit operation is always maintained in the best condition.
7 Vacuum system failures and causes
7.1 Leakage of vacuum system
7.1.1 Phenomenon
Leakage of the vacuum system has the following phenomena.
a) The tightness of the vacuum system is reduced;
b) Condenser heat transfer end difference rises;
c) The condenser pressure rises.
7.1.2 The main possible leaks
The main possible leaks are as follows.
a) Low pressure cylinder shaft seal;
b) The horizontal middle face of the low pressure cylinder;
c) Low pressure cylinder safety door;
d) Vacuum destruction door and its pipeline;
e) The steam side drain valve of the condenser;
f) Water seal of shaft seal heater;
g) The connection between the low pressure cylinder and the condenser throat;
h) Feedwater pump steam turbine shaft seal;
i) The front and rear flanges of the steam turbine exhaust disc valve of the feedwater pump;
j) The connecting flange or weld between the exhaust pipe of the feedwater pump and the condenser, the flange or the weld of the expansion joint;
k) The sealing water of the feed water pump returns to the condenser pipeline;
l) The connecting flange of the suction pipe in the negative pressure section;
m) Low pressure heater drain pipeline;
n) The pipeline from the aspirator to the condenser;
o) Condensate pump packing;
p) Low pressure heater drain pump packing;
q) Hot well drain valve;
r) Cooling pipe damage or port leakage;
s) Low pressure bypass isolation valve and flange;
t) Pipelines and connections of vacuum system measuring instruments.
7.2 Failure of cooling water system
7.2.1 Phenomenon
The condenser cooling water temperature rises.
7.2.2 Main reasons
The main reasons for the failure of the cooling water system are as follows.
a) Circulating water pump failure;
b) Circulating water pipeline and valve failure;
c) Unbalanced regulation of circulating water system;
d) The operation mode of the circulating water pump set is unreasonable;
e) The adjustable guide vane of the circulating water pump is out of adjustment;
f) The flow of the circulating water pump does not meet the design requirements;
g) There is air gathering on the top of the condenser water chamber;
h) Blockage of cooling water system, etc.;
i) Improper operation.
7.3 Condenser water level rises
7.3.1 Phenomenon
The degree of subcooling of the condensed water increases.
7.3.2 Main reasons
The main reasons for the increase in condenser water level are as follows.
a) Condensate pump failure;
b) Air leakage at the inlet of the condensate pump or clogged inlet filter;
c) Leakage of condenser cooling pipe;
d) Condenser make-up valve failure;
e) The low-pressure bypass desuperheating water door opens by mistake;
f) The valve of the condensate system is closed by mistake or the backstop valve of the backup pump is leaking;
g) The condensate recirculation door opens by mistake;
h) The outlet regulating door of the condensate pump fails;
i) Leakage on the water side of the heater;
j) The water level gauge or water level transmitter is not working properly.
7.4 Abnormal operation of suction equipment
7.4.1 Phenomenon
The condenser pressure rises.
7.4.2 Main reasons
The main reasons for the malfunction of the suction equipment are as follows.
a) Failure of pumping equipment;
b) The working fluid temperature of the vacuum pump is high;
c) The cooling water flow of the vacuum pump is low;
d) The working fluid flow of the vacuum pump is low;
e) The vacuum pump heat exchanger is dirty;
f) The heat exchanger of the vacuum pump is blocked;
g) The water level in the steam-water separation tank of the vacuum pump is low;
h) Air leakage from the water jet pump;
i) The inlet pressure of the water jet pump is low;
j) The working water temperature of the water jet pump is high;
k) The nozzle of the water jet aspirator is blocked;
l) The valve of the suction pipe is not fully opened or closed by mistake, or blocked;
m) The control equipment fails and cannot start normally.
7.5 Abnormal pressure difference in double back pressure condenser
7.5.1 Phenomenon
a) The pressure difference between the high and low pressure condensers is larger than the expected value;
b) The pressure difference between the high and low pressure condensers is smaller than the expected value.
7.5.2 Main reasons
The main reasons for the abnormal pressure difference of the double back pressure condenser are as follows.
a) The cleaning factor of the high-pressure condenser is reduced;
b) Air accumulation in the high-pressure condenser;
c) Increased air leakage from high-pressure condenser;
d) The corresponding pumping equipment of the high-pressure condenser works abnormally;
e) The cleanliness factor of the low-pressure condenser is reduced;
f) Air accumulation in the low-pressure condenser;
g) The air leakage of the low pressure condenser increases;
h) The corresponding pumping equipment of the low-pressure condenser works abnormally;
i) The high and low ...
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