Motor power of the pump
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Centrifugal pump: head 70m, flow rate 8m3/h. What motor power is required? Provide the calculation process: handshake
The question raised by the poster seems to not require any calculations actually; one just needs to find a sample from a manufacturer and check the motor power required for a centrifugal pump with a flow rate of 8 cubic meters per second and a head of 70 meters. If calculations are really necessary, then I’m not sure how to do them, haha!
It’s better to check the sample directly. Do we still need to calculate this? Maybe I just don’t understand.
I have this idea: considering energy aspects now, it’s about lifting 8 cubic meters of material per hour to a height of 70 meters; the energy change associated with this can be calculated. Convert this energy into electrical energy, in kilowatt-hours, that is, per hour; then the power can be determined. However, it is also necessary to take into account shaft power and efficiency issues – these are aspects related to the selection of centrifugal pumps. This is covered in Chapter 2 of the principles of chemical engineering. Of course, you also need to consider the pump’s performance curve, which is determined by the model of pump you choose; the manufacturer will provide its performance curve. Taking all of the above into account ； Only then can the power of the motor be determined.
If the medium is water and the efficiency is 0.6, then the shaft power is 2.5 KW. Ne=Q*H*density/(3600*102*efficiency)
The shaft power of a centrifugal pump can be calculated directly using efficiency: Shaft power = Pump head * Pump flow rate * Liquid density * g / Efficiency. The value obtained from this formula should be multiplied by 1.1 or more to determine the power required for the motor. Motors come in various rated power levels. Last edited by vavin456 on 2009-1-6 at 11:54
What the people ahead said is all correct; it’s easy to calculate the power based on the working principle. But if you want to know the motor power, you must know the efficiency. Different pumps have different efficiencies ； Pumps of the same type can have different flow efficiency values; it’s best to request samples from the manufacturer in such cases.
I just checked a pump for you: 40AYB40×2, with a flow rate of 9 m3/h, a head of 80 m, a rotation speed of 2950 r/min, an efficiency of 35%, a net positive suction head of 2.7 m, and a shaft power of 5.6 kW. It is equipped with a motor of type YB132S2-2, whose power is 7.5 kW. The weight of the pump is 163 kg; this figure includes some margin and is provided for reference only.
Centrifugal pump: head of 70 m, flow rate of 8 m3/h. These two parameters alone are not sufficient; it is also necessary to know the properties of the medium: temperature, density, viscosity, etc.
I’m also interested in rough calculations – how can we estimate it under normal water and room temperature conditions? I hope experts can give me some advice!