Centrifugal pumps control
Centrifugal pumps control
(OP)
Hi all
I need your expert feedback on below problem. This is related to newly installed pump station on the cross country pipeline.
One new pump station with three pumps are installed mid way of existing cross country 1200 km pipeline. Pumps are going to commission. We are worried that during start-up pumps will run at end of curve.
Pumps are with VFD with max speed 5300rpm with no discharge control valve. Normal pressure in the pipeline at this point is 1200psig. Pumps will start first on recycle mode with suction pressure 950 and discharge pressure 1500psig at 3400rpm. Pumps will shift from recycle mode to operating mode by opening discharge ZV. During this shifting time pump resistance is lower than pump discharge pressure. Under this condition can pump move to end of curve.
This case was simulated and came to know that pumps go to end of curve by achieving maximum speed 5300 rpm during shifting from recycle to operating mode. This result very low pressure at suction less than vapor pressure of NGL fluid.
Please give your opinion how this situation can be handled
I need your expert feedback on below problem. This is related to newly installed pump station on the cross country pipeline.
One new pump station with three pumps are installed mid way of existing cross country 1200 km pipeline. Pumps are going to commission. We are worried that during start-up pumps will run at end of curve.
Pumps are with VFD with max speed 5300rpm with no discharge control valve. Normal pressure in the pipeline at this point is 1200psig. Pumps will start first on recycle mode with suction pressure 950 and discharge pressure 1500psig at 3400rpm. Pumps will shift from recycle mode to operating mode by opening discharge ZV. During this shifting time pump resistance is lower than pump discharge pressure. Under this condition can pump move to end of curve.
This case was simulated and came to know that pumps go to end of curve by achieving maximum speed 5300 rpm during shifting from recycle to operating mode. This result very low pressure at suction less than vapor pressure of NGL fluid.
Please give your opinion how this situation can be handled





RE: Centrifugal pumps control
Or am I missing something?
RE: Centrifugal pumps control
If you need specific information, please let me knwow.
RE: Centrifugal pumps control
Artisi, happens all the time. Many pipelines are designed without ever considering actual operations. They figure if the horsepower is there, you can run it.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Centrifugal pumps control
A lot of my engineering career has been fixing just such problems. It is worth $$$ to someone.
Right answer, BigInch.
rmw
RE: Centrifugal pumps control
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Centrifugal pumps control
RE: Centrifugal pumps control
Why not start and run the pump up to 3000 rpm to give you about the same 1200 psig discharge pressure you have now? You could bring the control valves down to that corresponding %open and once the line has about stabilized at its original flowrate, start increasing rpm to build speed to 5300 rpm? I don't believe you can't do that. If not, I'm sure you must have your control valves acting too slowly, or maybe your ramp rate is too fast. Increase the actuator's stroke speed, or use a slower pump ramp rate.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/