Multi-stage pump energy reduction
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Our factory has a multi-stage water pump with a designed head of 127 meters; it has nine impellers inside. For our actual production needs, a head of 90 meters is sufficient. We now want to remove two of the impellers – is that possible? This pump has been disassembled; the nine impellers are all of the same size. I think since the impellers are identical in size, the pressure ratio should also be the same. Based on this calculation, a single impeller can generate a pressure of 127/9 = 1.4 kilograms. Even after removing two impellers, there is still enough head left, so theoretically it is feasible. I wonder if removing the impellers will affect the operation of the equipment? Also, if going to the impeller, it’s better to go to those two stages. Has anyone in the industry made such adjustments? It would be useful to get some references!
Yes, it is possible to remove two stages symmetrically along the axis, such as stages 2 and 8; after removal, the rotor needs to be dynamically balanced. But the head of this pump in your factory is only a little over 100 meters – why not replace it with a pump of the first stage? Generally, pumps of the first stage can achieve a head of over 90 meters
Thank you for the advice. We have also considered replacing the pump, but at the moment we need to cut costs, you know... Is it possible to proceed without doing a dynamic balance?
Generally, multi-blade shafting requires dynamic balancing. Since each impeller has a mass eccentricity, under high-performance operating conditions (thin shafts, a large number of impellers, high rotational speeds), it is necessary to perform dynamic balancing on each impeller individually first, and then after they are assembled, perform dynamic balancing again. If it is a cascade pump, you can rework the shaft and remove the two stages of the pump, which will be better.
Is it a vertical pump? Many vertical water pumps come with a configuration like yours
The impeller can be removed; we have done this as well, and it works quite well.
Remove the two symmetric levels. . . Redo an axis. . . This one is possible. . .