Pumps generally require short-circuiting
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I’m looking at the process diagrams for natural gas liquefaction, and I see that all the pumps (including water pumps, solution pumps, make-up pump, lean liquid pump, etc.) have their inlets and outlets connected together with a pipe, with a valve in between. May I ask why this shortcut is used? At home, I see that the water pumps in the farmlands don’t need to be short-circuited. What’s the difference?
Is it a centrifugal pump? Bypassing a centrifugal pump is generally used to ensure a minimum amount of return flow. (min. safety flowrate)
Installing short circuits at the pump’s inlet and outlet is mainly to facilitate disassembly during pump maintenance.
Reply to 2# Pingsha: Does the pump still need a return flow? Minimum backflow volume; if there’s no short circuit, then there should be no backflow.
This post was last edited by jintchinssen on 2011-1-20 09:34. Reply to 4# *aolu8317: Centrifugal pumps need to have their interiors filled with liquid in order to function properly. To maintain this filled state, it is necessary that the fluid flow rate be above a certain value; this value is what we refer to as the minimum backflow rate. That is, the safe return flow rate. There are many ways to achieve backflow; some involve direct short-circuiting into the pipeline before the pump, while others involve injecting it into the storage tank before the pump. Short connectors sometimes also have flow-limiting orifice plates to prevent excessive fluid from bypassing.
It should be the minimum flow line; let’s take a look at what the normal operating temperature is
Easy to maintain; it can be secured by inserting screws at both ends
I think none of you are correct; minimum flow circulation lines usually have flow control orifice plates installed. The original poster should check whether that pipe is really that small – it’s probably a purge line.