With the constant progress of the society, electric power and industrial development and people's life is closely related to the high grade energy, one of the growing demand for its people. Thermal power though right now the consumption of fossil fuels such as coal and pollution of the environment has a great influence, but according to the special national conditions of our country, coal is still the main mode of power supply, the proportion of the total installed capacity at about 70%. Thermal power plant is composed of boiler, steam turbine and generator three host and feed water pump, coal mill and other auxiliary equipment and control system. Feed water pump is a core system of thermal power plant boiler auxiliaries, its purpose is to continuously provide to boiler has the pressure, temperature and flow rate of water supply. Feed water pump is generally divided into two kinds of electric and steam, shanxi jincheng a 300 MW thermal power plant boiler supporting electric feed water pump. In the plant electric feed water pump, for example, this paper introduces the working process of the feed water pump, the common faults in the operation process and the corresponding solutions, in order to provide some reference for the general electric power staff.
Feed water pump is not only to provide sufficient pressure, temperature and flow rate of feed water boiler, but also provide reheater, superheater attemperator and reduction of warm water, so the safety and reliability of the feed water pump, a direct impact on the safety operation of boiler system and steam turbine generator set, serious when still can cause boiler water dry the occurrence of serious accidents, such as the higher the greater unit capacity and parameter, the importance of the feed water pump, the more prominent. [1]
Shanxi jincheng a thermal power plant 300 MW unit configuration is as follows: 50% capacity electric three main feed pump, two with one case. Models for DG600-240 - v (FK6D32); Type of cylinder core package, horizontal; Has six levels of impeller, motor models for YKS800-4 electric (Shanghai), feed water pump directly driven by motor through coupling, booster pump driven by motor directly, feed water pump and coupling, coupling and motor and motor and booster pump through the fold type shaft coupling.
Two common faults in the operation of feed water pump
Feed water pump can be stable operation of the safety and economy of boiler has a close relationship with large boiler unit generally configuration many sets of feed water pump, there are one or two electric feed water pump as backup. The power plant capacity 50% electric three main feed pump, 2 in one case, in the process of actual operation, the feed water pump fault has common motor overheating overheating [2], the pump body, pump body flow and system fault, such as vibration malfunction phenomenon, the possible reasons and solutions to see table 1.
3 in the operation of the feed water pump fault solution
3.1 the feed water pump troubleshooting
3.1.1 mechanical seal leakage, high temperature in the water injection pipe
As water injection pipe in air, check the mesh cleanliness, check whether the external cooling water is enough; If big is the collapse of the mechanical seal leakage, check whether the pump ring is installed backwards, cooler and the purity of the mesh, dynamic and static ring for wear.
3.1.2 bearing temperature is high
Check the lube oil cooler, increase the cooling water, adjust the oil hole plate, increase in traffic; Adjust the pressure relief valve, the oil pressure; The collapse of the bearing when necessary, check the bearing clearance.
3.2 the feed water pump booster pump troubleshooting
3.2.1 mechanical seal leakage
Spring force is not enough, loosen screw mechanical seal on the shaft sleeve, the sleeve to move about 1 ~ 2 mm, outside the pump to tighten the screw. If the big leakage, the need to strip inspection, replace if necessary.
3.2.2 the drive end bearing oil
Thrust bearing oil return is not the driving end plug holes on the bearing cover plate, often to the bearing chamber oil return, because of the large amount of oil return cause oil leakage. Reveal a plug hole plate, narrow small aperture.
3.2.3 booster pump shaft in small flow up
Double-suction volute pump in the small flow rate, the impeller out of the mouth room is easy to produce pressure fluctuations caused by axial channeling move, in the big traffic (about 300 t/h or above) or disappear completely, cold center, in accordance with requirements can reduce the booster pump shaft move.
3.2.4 cold installation to the center
Remove the upper cover of motor bearing, with a precise level 4 meters, on the shaft neck area, check the shaft back in internal carotid should be equal on both sides of the shaft, and in the opposite direction. If you need adjustable wedgeplug pad under the floor, to ensure our internal jugular back degrees equal on both sides of the axis, the reset bearing upper cover.
3.2.5 the axial position of motor rotor must be consistent with the center of the magnetic field of the motor
Runtime box body heat expansion, gear tooth force when rotating, bearing clearance, and the hydrodynamic lubricating oil can cause axis offset. Therefore in the pump set is cold find center, must be set in the horizontal, vertical, axial offset, the expected offset compensation when starting and running.
4 conclusion
Thermal power is made up of boiler, turbine and generator three host and feed water pump, coal mill, such as auxiliary coordination of unified whole, an equipment or system malfunction could affect the safety and reliability of the whole system, especially the feed water pump as the working medium for boiler equipment, is the core of the auxiliary boiler system, its role in the boiler system is self-evident. In the process of actual operation, because of the feed water pump working environment is bad. Frequently, all kinds of feed water pump failure, the staff must be regularly for feed water pump of power plants for maintenance, found problems in a timely manner, to ensure the safe operation of boiler feed water pump and system.
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