Performance calculation of centrifugal pumps — A problem from injection chemistry
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In the calculation of centrifugal pump performance parameters, all other conditions remain unchanged. When the flow rate increases, why does the vacuum gauge pressure of the pump rise while the pressure gauge drops?
When the outlet valve is opened wider, the outlet pressure decreases, the gauge reading increases, and the flow rate rises as well (this is a characteristic of centrifugal pumps). The reading of the vacuum gauge increases because, as the flow rate rises, the pressure loss in the water suction pipe increases, resulting in a decrease in the pressure inside the pipe; this is reflected in an increase in the reading of the inlet vacuum gauge (note that an increase in vacuum value means a decrease in pressure).
The issue with the pump’s performance curve and the pipeline’s performance curve is as mentioned above
It is sufficient to establish equilibrium using the Bernoulli equation respectively (from the liquid layer to the vacuum gauge, from the liquid layer to the outlet gauge)
The four performance parameters of a centrifugal pump are flow rate, head, efficiency, and shaft power. A vacuum gauge is installed on the suction line, while a pressure gauge is placed at the outlet valve. It is possible to use Bernoulli’s equation to make calculations in two steps. I recommend that you take a look at the version of Chemical Engineering Principles published by Tianjin University; it explains these concepts very clearly