Turbine vs. Motor driven pumps

[Falcon03]

Gentlemen,

We have noticed in our refinery that the Steam driven pumps (pare pumps) are not reliable as the motor driven pumps. In other word, the turbine driven pumps are not delivering the required capacity. If you speaking of hp it should be equal.

We are planning to spend a lot of money to upgrade the turbine pumps to match it with the motor driven pumps in terms of horse power requirement.

I would think that both pumps (motor/turbine) should deliver the same flows and same power output.


Any comments? Thanks for your usual cooperation.

 

[BobPE]

In an ideal word they should be the same however, the quality of the steam is probably not as consistant as the quality of the electric service.

You are probably making a good decision. You study of the steam pumps should allow you to make a reverse calculation of the quality of the steam system. The steam is used for many other functions in your industry which do not involve driving mechanical loads which means it probably has a wide delivery range from where you produce it.


BobPE

 

[Kawartha]

Falcon03,

Further to BobPE's comments from the steam side, you may also investigate the need to upgrade your speed control system. From the information that you provided, it would appear that the turbine driven pumps are operating at a lower speed than the motor driven pumps. You may want to check the operating rpm of both to see if this is part of your problem, since at the same rpm, pump performance should be within a few percentage points (head, capacity & hp) of each other.

If drive speed is the problem, you may want to look at upgrading your speed control system. At same time it may be worthwhile considering a digital control system and tieing into the DCS for possible remote monitoring and control.

 

[TBP]

Are the turbines being supplied with the specified steam conditions? If the inlet pressure has been reduced, and/or the exhaust pressure increased, turbine output will suffer.

Check the easy stuff first - steam pressures, clogged sensing line between the pump discharge and the turbine, turbine & pump valves fully open, etc. Very disappointing to discover that a lot of money has been spent when the problem was actually something like an isolation valve only partially open, or a strainer was plugged.