Centrifugal Pump Design - Motor Driven and Turbine Driven

Assuming that the pumps run independently (are not in parallel) so that the duty given applies to each pump, and that the head does not increase (due to greater system losses at the higher flowrate), the easiest way is to increase the speed to about 1750rom. You might be able to use a VFD on the electric motor driven pump, which would mean about 60Hz, and the turbine driven pump might have an adjustable governor that can reach this speed. However, you will need to check:

a) With the pump manufacturer that it can run at this speed (usually any pump that runs at 50Hz speed is designed to also run at 60Hz speed).

b) With the motor manufacturer that it can run at 60Hz in standard form, and more importantly that it has the power rating to handle the increase in absorbed power (current abs. kw x 1.44).

c) With the turbine manufacturer that it is speed-adjustable, can reach 1750rpm and can handle the absorbed power.

These are quite big pumps, so safety margins for motor and engine size selection could be quite small, and it is quite likely neither will be able to handle the increase in power absorbed, in which case you would have to consider new motors/turbines.

Hi Ed. Haven't heard from you for a while. Have you been on vacation? If so, welcome back.

I believe the OP mentioned that the impeller is already at max diameter, which is why I did not consider this option. It seems to me the only options (short of fitting new pumps) are increasing speed or reducing TDH (if the system permits). Thinking about it, if the pumps have a fairly flat curve it might not need much of a speed increase to reach the desired flowrate, but the limiting factor is always going to be motor/turbine power ratings. If they are lucky there might be enough in hand to accomodate the increase. I don't think we can go much further than this without seeing pump & system curves & specs.