A bloodshed caused by jointly filling a pump (shutdown)
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This post was last edited by wangcheng89 on 2017-7-2 23:19. The feed tank is located on a 5-meter-high frame, with a pressure of 0.26 MPa. Pumps A and B are multi-stage pumps; the inlet pipes have a diameter of 10 inches, while the outlet pipes have a diameter of 6 inches. Pump B is in operation, and the medium being handled is mixed C4. The outlet pressure is 4.2 MPa, with a flow rate of 35 t/h. Pump A is ready to start operating – the vapor line has been opened, and the inlet valve of pump A was slightly opened. As a result, the flow rate of pump B dropped from 35 t/h to 7 t/h before returning to its normal level quickly. The system stopped operating due to interlocks :( I want to know why the flow rate of pump B changed suddenly from 35 t/h to 7 t/h Is the pump cavitating? Multiple tests were conducted later; after tank A was emptied, even quickly opening the inlet valve of A did not cause any fluctuations in the flow rate of pump B
The check valve of pump A became stuck, but then returned to normal
The pump outlet valve is closed, so there is no flow from B to A
There is no backflow; the check valve at outlet A is in the open position. If the outlet valve of A leaks or is not closed, opening the gas line at A will cause fluctuations in the flow rate at the outlet of pump B
Are there any flowcharts, piping diagrams, etc.? Photos are also fine. Let everyone take a look so that it can be analyzed. When the flow rate of pump B changes, does its motor current also decrease? Is flow rate the condition for device interlock? Is it still the reduced traffic causing other variables?
It’s a bit like trying to force an excessive flow rate; the supply volume from the inlet pipeline is insufficient. As for cavitation, it shouldn’t occur
The last edit to this post was made by xgog on 2017-7-2 at 11:40: The inlet of pump AB is connected; when the exhaust valve of pump A is opened, it is very likely that the gas phase from pump A will be drawn into pump B, causing pump B to be emptied in an instant
Images will not be uploaded. The B current will definitely decrease; a low flow interlock is installed at the pump outlet
The pump inlet pipeline is 10 inches, and the outlet is 6 inches. Besides, when A is available, the inlet valve opens for less than a full turn, and there is pressure inside pump A; as a result, the flow rate into A is not very high, so it does not compete with the flow rate at the inlet of pump B
Can it be understood that pump A is connected to the feed tank via a vapor line, with a pressure of 0.26 MPA? The pressure at the center of the impeller and at the inlet of pump B is below 0.26 MPa; when the inlet valve of pump A is opened, the gas phase inside pump A enters pump B instantly, causing pump B to fail to deliver flow for a short period of time
Don’t you turn on the drain and vent for the filling pump? ?