Inlet pressure requirements for the pump as specified in the pump data sheet
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Dear experts: The data sheet for the pump (the pump used in the bottom of the stripping tower) specifies that the inlet pressure should be 0.5 MPa. However, when the tower is started up for the first time, the pressure does not reach 0.5 MPa; in some cases it is not even 0.1 MPa. Although the liquid level is sufficient, the pump and the pipes at its inlet and outlet experience severe vibration once the pump starts operating. Is this caused by cavitation or some other factor?
Reply to 1# a599084643: What you said is possible, as the suction head is not sufficient, which can lead to cavitation at the pump inlet. Specifically, one can check the required net positive suction head for the pump; by combining this with the effective net positive suction head available during testing, the value can be determined!
“Refinery operator: Lowering the pump outlet flow rate will solve it. ” I disagree. A decrease in inlet pressure directly affects the value of NPSHA; the phenomenon mentioned by the original poster is likely cavitation, and measures should be taken to increase the pump’s inlet pressure. Reducing the pump outlet size can only ensure that the outlet pressure does not drop, but it does not solve the problem of cavitation
Reply to 3# FLYTOINTER: That’s indeed the case. The opening degree of the outlet valve cannot solve the problem of cavitation; only by increasing the pressure at the inlet can cavitation be prevented.
How did the friend upstairs solve the problem? Could you share it?
Reply to 4# a599084643: No. If driving in a cold state, that is, establishing a cold cycle, what should be done if the inlet pressure cannot be increased? Is it necessary to use additional nitrogen to raise the pressure?
Just like the bottom pump of the desorption tower in absorption stabilization, at the beginning of operation, neither the inlet pressure nor the backpressure reaches the design values, yet the operation still proceeds. Can you say that the pressure in the desorption tower needs to be increased? What should be done during water intermodal transport?
Increasing the pump inlet pressure can resolve cavitation, as anyone who has worked with chemical unit operations knows.
Reply to 5# Refinery Operator: We can solve this by using steam to increase the pressure before feeding the material; it’s a hot-start operation. The cold transport step is missing; I think that if cold transport is desired, nitrogen would need to be added to increase the pressure, but this has not been tested.
I’m not sure what the original poster means by steam pressure increase Is it to heat the material in order to increase pressure? Is this a design requirement or a measure taken due to the abnormal condition of the aforementioned pump?
I wonder what technique the original poster uses? What kind of pump is it exactly? Could you explain it in more detail? Let’s all analyze it together