How is the maximum resistance torque of a piston pump calculated?
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Hello, experts. I would like to ask how to calculate the maximum resistance torque of a piston pump, and what is the formula used for that? I’m a complete novice in the field of chemistry. I noticed that for a pump with an axis power of 6.1 KW, the manufacturer chose a 15 KW four-stage motor with a speed of 990 revolutions per minute. The pump’s flow rate is 1 m3/h, and the inlet pressure is 0.02 MPa (with a maximum inlet pressure of 0.2 MPa). Therefore, I’d like to know how to select an appropriate powered motor for an electromagnetic-speed-controlled piston pump. From what I’ve read, it seems that the maximum resistance torque of the piston pump needs to be calculated first in order to determine the motor’s rated torque; then, using the relationship between the rated torque and the motor’s rated power, the rated power of the motor can be determined. I’m not sure if this approach is correct; if not, I would appreciate your guidance.
A reminder from the design institute: there is a fixed relationship among the motor’s rated power, torque, and speed. I remember it was related to the 9550; for reciprocating equipment, it is necessary to check whether the motor’s torque is sufficient, and both the starting torque and the maximum torque need to be verified. However, the power of the motor is not determined based on torque; instead, the shaft power is calculated using the compressor’s power formula, and then the motor power is selected accordingly. Then check whether the torque meets the requirements; otherwise, the motor should be selected again. As for how to calculate torque, it is actually the component of the rod force along the tangent to the crankshaft; there are many explanations on Baidu Wenku regarding how to calculate the rod force. For reference.
Turn left | Turn right. P---Input power of the pump; PP---Maximum operating pressure of the pump; qVP---Flow rate of the pump; ηp---Overall efficiency of the hydraulic pump; Tn----Input torque of the pump. Additional note: A gear pump is a rotary pump that transports liquids or increases their pressure by utilizing changes and movements in the working volume formed between the pump cylinder and the meshing gears. It consists of two gears, a pump body, and front and rear covers, creating two enclosed spaces. When the gears rotate, the volume of the space on the side where the gears are separated decreases, creating a vacuum that draws in the liquid; meanwhile, the volume of the space on the side where the gears are in contact with each other decreases, forcing the liquid into the pipeline. The intake chamber and the discharge chamber are separated by the meshing line of two gears. The pressure at the outlet of a gear pump depends entirely on the magnitude of the resistance at the pump outlet.
You can refer to this book for the calculation method