Change from belt drive to direct connection
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Our factory has a propane unloading pump; the motor was connected to the pump via a belt. After inspection by experts, it was advised that using a belt for this connection is not allowed, so we now need to switch to a direct connection. The motor is a 4-stage motor with a speed of 1440 revolutions per minute and a power of 4 KW. With the motor’s small wheel and the pump’s large wheel, the actual rotation speed of the pump is calculated to be only 650 revolutions, based on the formula N2=N1*D1/D2. The nameplate specifications of the pump indicate an shaft power of 2.7 KW, a flow rate of 10.08 cubic meters, a head of 27 M, and a rotation speed of 2900 revolutions per minute. Can the pump and motor now be directly connected using a coupling wheel, thereby increasing the pump’s speed? What impact will such installation have?
It seems that it needs to meet the operating conditions required by the pump, right? Everything should be in accordance with the requirements specified on the pump’s label.
This indeed cannot be changed casually. Increasing the rotational speed by more than a factor of two has a significant impact on aspects such as the bending strength of the rotor, dynamic balance, and bearing design. Additionally, is this pump a positive-displacement pump or a centrifugal pump?
Sure, it can be modified – just add an inverter to adjust the speed
The flow rate of a centrifugal pump is proportional to its rotational speed, the head is proportional to the square of the rotational speed, and the power is proportional to the cube of the rotational speed. If modification is necessary, pay attention to the current flowing through the motor
The 2900 rpm indicated on the pump’s nameplate is in sharp contrast to the 650 rpm achieved after using the actual pulley for speed control
It is necessary to find the cause; determine the reason for the difference in rotation speed
We can add a gearbox with a gear ratio of 4.5 in between; we just finished modifying it