1. Renovation plan The adjustment method of the water pump is: throttling regulation, backflow regulation, frequency conversion regulation, etc. Among them, the frequency conversion regulation is an energy-saving adjustment method. The frequency conversion control transformation of high-power rotating machinery such as feed pumps is a very effective way for power plants to save energy and reduce emissions. Over the past few years, with the development of AC frequency conversion technology, Shanghai Wuai Pump & Valve Factory has solved the problem of the influence of higher harmonics generated in the AC conversion process on the power supply and the motor. At the same time, it has high regulation efficiency, wide speed range, and With the advantages of stepless speed change and high-precision operation, it is decided to use the scheme of AC frequency conversion for the feed pump.
After the transformation, the water supply system maintains the parental control operation mode, and the operation-frequency conversion adjustment method is adopted. The boiler feedwater adjustment door opening is adjusted from about 60% to 90%, and the remaining 10% opening is used for fine adjustment of the water supply of a single boiler.
The ZNVERT-A6H2000/06YB 10 high-voltage inverter is used for the second transformation. The frequency control of the inverter is controlled by the backstage control platform installed in the central control room.
2. Energy-saving analysis of the frequency conversion operation of the two feed pumps Under normal circumstances, when the two feed pumps are operating with variable frequency, the high-pressure feed water-cooled mother tube of the feedwater pump is put into operation, and the feedwater is divided into two after the high-pressure water-cooled mother tube, and all the way through No. 1 After the machine is added, it is sent to the No. 1 furnace, and the other way is sent to the No. 2 furnace after the No. 2 machine is added. The high-pressure water supply hot mother pipe of the Gaojia outlet is cut and stopped. The water supply volume of the two boilers is basically the same. The performance curve and pipeline performance curve of each feed pump can be considered to be the same as that of a single feed pump, and the energy saving effect is also the same. That is, the power consumption of the two pumps of Shanghai Wuai Pump & Valve Factory is compared with that of the power frequency operation. for:
N=272 x 2=544 KW
Energy saving rate is 22 88%
3. Other problems in the frequency conversion reform of the feed water pump After the reform, the feed water pump maintains the two operation and standby parent control operation mode. If the standby pump adopts the frequency conversion method, it takes about 100 seconds from the linkage to reach the set output, and the safety cannot meet the requirements. In addition, from the perspective of saving investment, it is determined that the standby pump adopts the power frequency standby mode. Without the AC frequency conversion, the inverter sets up two bypass switches and switches through the switch to achieve the purpose of the frequency conversion operation of the two feed pumps. However, the switching operation is still cumbersome.
In addition to the direct energy-saving benefits, the frequency conversion of the feed pump also brings other benefits, mainly including the improvement of the power factor, and greatly reducing the reactive power demand of the system; realizing the soft start of the motor, eliminating the excessive starting current, and reducing the sudden change of the starting torque to the motor. The electrical and mechanical damage, prolong the service life of the motor; reduce the friction of the bearing, reduce the vibration of the bearing; reduce the erosion of the working substance to the valve and the pipeline, reduce the maintenance workload.
4. Concluding remarks The ESC EH system plays an important role in the control of steam turbines. Failure of the EH system will directly threaten the normal operation of the unit. The relevant technicians must perform maintenance procedures, routine maintenance and management, oil quality supervision, and equipment file management. Grasping in many ways, the quality of each link should be improved. At the same time, it is necessary to strengthen the technicians' technical reserves, and pay attention to the daily experience of accumulation, so as to maintain the long-term normal operation of the EH system.
After the transformation, the water supply system maintains the parental control operation mode, and the operation-frequency conversion adjustment method is adopted. The boiler feedwater adjustment door opening is adjusted from about 60% to 90%, and the remaining 10% opening is used for fine adjustment of the water supply of a single boiler.
The ZNVERT-A6H2000/06YB 10 high-voltage inverter is used for the second transformation. The frequency control of the inverter is controlled by the backstage control platform installed in the central control room.
2. Energy-saving analysis of the frequency conversion operation of the two feed pumps Under normal circumstances, when the two feed pumps are operating with variable frequency, the high-pressure feed water-cooled mother tube of the feedwater pump is put into operation, and the feedwater is divided into two after the high-pressure water-cooled mother tube, and all the way through No. 1 After the machine is added, it is sent to the No. 1 furnace, and the other way is sent to the No. 2 furnace after the No. 2 machine is added. The high-pressure water supply hot mother pipe of the Gaojia outlet is cut and stopped. The water supply volume of the two boilers is basically the same. The performance curve and pipeline performance curve of each feed pump can be considered to be the same as that of a single feed pump, and the energy saving effect is also the same. That is, the power consumption of the two pumps of Shanghai Wuai Pump & Valve Factory is compared with that of the power frequency operation. for:
N=272 x 2=544 KW
Energy saving rate is 22 88%
3. Other problems in the frequency conversion reform of the feed water pump After the reform, the feed water pump maintains the two operation and standby parent control operation mode. If the standby pump adopts the frequency conversion method, it takes about 100 seconds from the linkage to reach the set output, and the safety cannot meet the requirements. In addition, from the perspective of saving investment, it is determined that the standby pump adopts the power frequency standby mode. Without the AC frequency conversion, the inverter sets up two bypass switches and switches through the switch to achieve the purpose of the frequency conversion operation of the two feed pumps. However, the switching operation is still cumbersome.
In addition to the direct energy-saving benefits, the frequency conversion of the feed pump also brings other benefits, mainly including the improvement of the power factor, and greatly reducing the reactive power demand of the system; realizing the soft start of the motor, eliminating the excessive starting current, and reducing the sudden change of the starting torque to the motor. The electrical and mechanical damage, prolong the service life of the motor; reduce the friction of the bearing, reduce the vibration of the bearing; reduce the erosion of the working substance to the valve and the pipeline, reduce the maintenance workload.
4. Concluding remarks The ESC EH system plays an important role in the control of steam turbines. Failure of the EH system will directly threaten the normal operation of the unit. The relevant technicians must perform maintenance procedures, routine maintenance and management, oil quality supervision, and equipment file management. Grasping in many ways, the quality of each link should be improved. At the same time, it is necessary to strengthen the technicians' technical reserves, and pay attention to the daily experience of accumulation, so as to maintain the long-term normal operation of the EH system.
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