Screw pump problems
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Oil products with different viscosities can be transported using screw pumps, but if the outlet pressure is to remain the same, can the flow rate stay constant?
Shaft power = head × density × flow rate × gravitational acceleration
This one is a centrifugal pump, while his is a positive-displacement pump
Can using an inverter-driven motor and appropriately increasing the motor’s power solve this issue?
The outlet pressure is determined by the system backpressure; assuming the pump outlet is vented, the pump outlet pressure is almost equal to 0. A screw pump is a positive-displacement pump; viscosity affects the electrical efficiency, and at a constant rotational speed, the volumetric flow rate is theoretically constant. To control the flow rate, variable frequency control can be used, or a pump can be employed for backflow regulation; remember not to adjust it by closing the outlet valve, as this will damage the pump
No, screw pumps are positive-displacement pumps. Although the fluid itself is essentially incompressible, there are gaps between the screws, which leads to backflow (i.e., internal leakage). The lower the viscosity, the greater the backflow; however, if it falls below the pump’s design limits, excessive vibration can occur and cause problems.
Using variable frequency control allows for appropriate adjustment of the flow rate, but this must be done in conjunction with the manufacturer’s designed viscosity curve range for that pump.
Adhere to one principle: for screw pumps, the volume of fluid transported each time is constant