Centrifugal pumps have a wide range of flow rates; what should be done if low-flow operation requires a constant head? ? ?
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My pump (centrifugal pump) has a flow rate of 32 m3/h and a head of 40 meters. I need a minimum flow rate of 5 m3/h, with a maximum flow rate of 30 m3/h; the head should remain around 35 meters. It’s not a problem when the flow rate is high, but what should I do if it drops to 5 m3/h? Do you have any good suggestions? ? ?
Is there no control valve? If the flow rate decreases, the head should also change; otherwise, reduce the motor speed
To save energy, variable-frequency pumps are generally used for this purpose. As for head and flow rate, the higher the head, the better it will meet your requirements regarding height. Why bother focusing on this then?
Use frequency conversion for control or add a control valve at the pump outlet
Frequency conversion will simultaneously reduce the head, and the decrease in head is even faster than that in flow rate
Well, I thought about it the wrong way; by using a variable-frequency pump along with a control valve, it will definitely meet the requirements
After frequency conversion, the flow rate becomes around 15%–30% of the centrifugal pump’s rated flow rate. For example, if the pump originally has a flow rate of 30 m3/h and a head of 30 M, then after frequency conversion the desired flow rate is 5 m3/h, but the head still needs to remain around 25 M. With frequency conversion, the head almost decreases to nothing; in such a case, even by using control valves to maintain pressure, the required head won’t be sufficient, right? ? ? ?
{:3_46:}{:3_46:} No, you have the order reversed; one has to figure this out on their own. There are countless combinations regarding the opening degree of the control valves and the pump frequency that can meet your requirements for flow rate and head pressure. For example, if the flow rate remains constant but the head pressure needs to increase, you can raise the pump frequency and reduce the valve opening degree. This still requires the personnel on site to figure it out by themselves
The simple solution is to use a high-flow backflow; as long as the condition of low flow lasts for a short period of time, it’s reasonable to consume more electricity~