The problem of the minimum flow line for high-speed centrifugal pumps
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Previously, the minimum flow line of high-speed centrifugal pumps was located in front of the pump outlet valve, whereas in modern designs it is placed behind the pump outlet valve. In the past, we would open the minimum flow line to a certain level before starting the pump, and then start the pump and open the outlet valve. What should I do now? Is it necessary to modify it further in front of the pump outlet valve? I seek advice from experts.
Generally, we keep the pump outlet valve slightly open; in the case of a liquefied gas high-speed pump, we can adjust the small hand valve on the outlet side to reduce pressure
First, it is necessary to clarify the purpose of this line. Is it used to fill the pump with liquid before starting it, or is it designed to prevent overpressure caused by the vaporization of the liquid? No matter how it is set up or modified, it is essential to follow the operating procedures. If any changes occur, the operating procedures should be revised. If nothing is changed, proceed according to the original procedures. In principle, the above two scenarios are mainly based on the physical and chemical properties of the material medium, for reference only.
It is used to prevent vaporization; the media involved are carbon 7, carbon 9, and carbon 10. I think it’s better to use it in the outlet valve – so that when the pump is turned off, it can be done while keeping the minimum flow rate active, thereby preventing vaporization that could damage the pump. Does this reasoning make sense?
Oh, there’s one issue that has been overlooked here: the entry and exit positions of this minimum flow line have not yet been determined. Oh, there’s another important condition that needs to be mentioned: is a check valve installed at the pump outlet? ? ? It is recommended to include a flowchart; it will be easier to understand things when looking at the diagram.