Multi-stage centrifugal pump failure maintenance


Multi-stage centrifugal pump failure maintenance


First, the phenomenon: centrifugal pump displacement, pressure drop.


The main reason:
① filter clearance is too large, impurities in crude oil clogging pump impeller suction port.
② balance plate and balance plate with improper clearance, shaft and impeller, impeller mouth ring and guide wing anti-friction ring with excessive clearance (caused by different centers);; ③ impeller damage (caused by different centers); ③ impeller damage (caused by different centers); ③ impeller damage (caused by different centers).
③ Impeller damage (wear damage, vapor corrosion damage, processing quality); ④ Oil inlet line leakage; ④ Oil inlet line leakage.
④ oil pipeline leakage caused by supply and transmission relationship disorders.


Treatment method:
① Open the low-pressure end of the pump and remove the blockage in the impeller.
② open the centrifugal pump, with vernier calipers, internal and external calipers to check the fit gap, the installation of the pump should follow the installation requirements; ③ carefully check the impeller wear surface.

④ check the oil pipeline and related equipment; ④ check the oil pipeline and related equipment; ④ check the oil pipeline and related equipment.


Phenomenon: After starting the pump, the oil delivery is normal, and then the pressure drops slowly.


The main reason:
① filter is too dirty, affecting the flow of oil through; ② oil temperature is too high (the oil flow).
② oil temperature is too high (cavitation) or too low (oil thick); ③ balance tube clogging (oil).
③ balance pipe blockage (can be checked by hand touch) resulting in high pressure section of the pump head heat affecting the head; ④ incomplete venting, the delivery of the head; ④ the pump is not completely emptied, the delivery of the head.
④ Incomplete emptying, gas bubbles gradually accumulate in the process of oil transfer to form a gas section, affecting the liquid into the pump; ⑤ After emptying the tank, the pipeline is filled with gas, which affects the head of the pump.
⑤ After emptying the tank, the pressure change in the pipeline leads to the precipitation of dissolved gas, which affects the oil transfer environment.


Treatment:
① stop the pump to clean the filter; ② control the oil temperature; ① stop the pump to clean the filter
② control the oil temperature; ③ remove the balance pipe to clear the blockage
③ Remove the balance pipe to clear the blockage.
④ Emptying completely (check diligently in the early stage of oil delivery, observe the change of pressure gauge pointer, and empty the gas in the pump at any time; ⑤ Emptying the gas caused by dumping the tank; ⑤ Emptying the gas caused by dumping the tank.
⑤ Empty the gas section plug flow caused by the inverted tank (it is recommended to rearrange the oil pipeline to separate the buffer tank inlet pipeline from the oil pipeline of the big tank in front of the filter; ⑤ Empty the gas section plug flow caused by the inverted tank.


Third, the phenomenon: centrifugal pump operation process, balance disk wear, pump string volume exceeds the prescribed range.


The main reason:
① pump on the amount of bad, too many impurities in the oil caused by pump balance disk wear; ② improper assembly, resulting in pump shaft wear.
② improper assembly, resulting in the pump shaft allowable string amount is too large or too small; ③ bearing wear, clearance.
③ bearing wear, the gap becomes large resulting in the shaft allowable string amount is too large; ④ improper operation, every time you start the centrifugal pump.
④ Improper operation, each time the centrifugal pump is started, do not adjust (open) the balance disk and balance plate clearance; ⑤ The gap between the motor shaft and the pump shaft is too large or too small.
⑤ The motor shaft and pump shaft are not centered (radial runout, axial runout) causing a series of mechanical damage, resulting in excessive clearance between the balance disk and the balance plate.

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