he reason why the exhaust pressure rises slowly or not in the operation of the reciprocating cryogenic liquid pump is mainly the cavitation and liquid leakage. The above reason is only a special case, which is very rare in the production operation.
1, the cavitation
Cavitation is caused by the presence of gas in the working chamber, which causes the working chamber to have two phases of gas, and the gas is a compressible medium, which causes the pump to be unable to work properly. There are many causes of cavitation, mainly:
The cooling effect of the pipe and pump head is poor.
(2) improper placement of the suction pipe and the back pipe;
The suction pipeline and the back air passage blocked the drainage and the back gas was not smooth;
The vacuum degree of the cold end of the liquid storage tank and pump head is changed.
Leakage is refers to the liquid leakage during compression cylinder or expands from the discharge valve leakage cavity back to work, when the leakage and discharge, there is no actual flow, causing the exhaust pressure does not rise. The root causes of leakage are:
Bleed valve and discharge valve leakage;
The wear failure of the piston ring and sealing parts;
The sealing leakage of the suction valve seat and cylinder liner;
The sealing gasket of the two steps before and after the drain hole of the cylinder liner is leaked.