Pump selection
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Experts, the medium is pumped from the low-pressure tank to the high-pressure tank via a pump; the pressure in the high-pressure tank is 4 MPa. Is it sufficient to choose a pump whose outlet pressure at its maximum efficiency point is greater than 4 MPa? Also, how is this 4MPa backpressure of the high-pressure tank reflected in the pipeline network resistance curve? Thank you.
The design institute is required to prepare the pump data sheet and inquiry form. Pumps have rated points and operating points, which are not necessarily at the point of maximum efficiency. The head at the rated point must overcome the pipeline losses and deliver the fluid to the high-pressure tank; the exact value requires calculation by the design institute. API610 requires that the rated point be located to the right of the peak efficiency point; it is difficult for many pumps to achieve this, but it is advisable to have the pump’s rated point at more than 90% of the flow rate at the peak efficiency point.
The inlet pressure, the volumetric losses of the pump, the pressure losses in the inlet and outlet pipelines (which are related to the medium, i.e., flow velocity, and to the size of the pipes), the back pressure at the outlet, the pressure loss across the filter, as well as the pressure losses due to valves and fittings, all need to be taken into consideration. Aspen can be used for calculations to ultimately determine the outlet pressure. After calculating the pressure, the inlet pressure, density, and saturation vapor pressure of the medium are provided to the manufacturer, who then determines the head, power, and net positive suction head required for the pump.