What should be the appropriate flow rate for a centrifugal pump? (No purchase of pumps; those interested in technology can discuss it, while those who just want to sell pumps can move on.)
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The process flow diagram indicates a centrifugal pump with specifications of Q=3 m3/h, H=30 m, and medium of ultra-high molecular weight polyethylene; the wastewater is at normal temperature. Can we use a pump whose nameplate specifies a flow rate of 10 m3/h?
Let there be a minimum flow line; it is usable. High energy consumption.
Consider the impact on the achievement of the equipment and process objectives throughout the entire process (for example, we installed a glass rotor flow meter with a range of 4 m3/h at the outlet of the centrifugal pump, and after starting the pump, this flow meter was damaged). . . ）
Yes, a return pipe can be installed at the outlet
The indication on the nameplate represents the rated operating condition of the pump, that is, the peak point of its performance curve. What you need is a head of 30m; you can check the performance curve of this pump to see what the flow rate will be at a head of 30m If it is greater than 3 m3/h, a return line needs to be installed for use, and the valve operation is controlled based on pressure ； If the flow rate is less than 3 m3/h, then this pump will not meet your requirements and cannot be used
Can’t the outlet valve be operated based on pressure? Is it necessary to install a return pipeline?
It is operated using pressure, but when you open or close the valve, what is affected is not only the pressure but also the flow rate. Your other post probably deals with the same topic – a pump with a flow rate of 10 cubic meters and a head of 30 meters, to be used in a situation where the required flow rate is 3 cubic meters with the same head of 30 meters. When the head is kept at 30 meters, the pump’s flow rate is around 10 cubic meters; the extra 7 cubic meters cannot be utilized and thus force the system to operate in reverse flow； If you close the valve and the flow rate decreases, the head will increase, which will lead to an increase in pressure in the pipeline downstream of the pump
Of course, the valve needs to be adjusted to control the flow rate.
A 10-cubic-meter pump, using 7 cubic meters for backflow? The return pipe has to be thicker than the main pipe; if the pressure in the pipeline after the pump increases, so be it
. . . . Changing the operating pressure of a pipeline is not something that can be decided casually; it needs to be confirmed by process engineers. Failing to vent backflow will definitely cause an increase in pressure in the subsequent pipelines; whether this will affect production depends on what the process engineers decide.
That’s not appropriate, right? Choose the right and good operation method