3 replies to this topic

[Muhammad.Elhassan]

Gents,

 

We're facing an issue with the centrifugal compressor as the production is declining and the flowrate to the compressor is much less now than originally designed for.

 

One solution to that is to construct a larger anti-surge line that would recycle -in our case- about 40% of the production so that the compressor's minimum flow is achieved.

 

My question is that; is the prescribed solution more economical (I'm sure there would be Capex for constructing the recycle line, the FCV, probably new larger PSV for the suction scrubber, and of course the energy loss) than purchasing a new smaller compressor that provide better performance with the current production, knowing that the compressor is required to compress about 150MMSCFD of light gas (mainly C1, MW of 17) from 25barg to 70barg?

 

Thanks for your feedback,

Cheers

 

[fallah]

Hi,

 

If you are really intended to keep the compressor, you may keep the anti surge line/valve unchanged and continuously recycle a flow equal to reduced value from design capacity from discharge back to the suction through a FV...then the anti surge valve will be activated just when it's needed to provide minimum flow through the compressor...

[Hassan seif]

hey muhammad

first i would like to know when you reduce the production does the anti surge starts to open or not - i mean do you use it for recycle or it just opens when the surge controller give the order to do so,,

secondly if the production reduction you mentioned 40 % is going to take place for a long period per year lets say above 10% of plant operation hours that new recycle line you mentioned is not practical from cost point of view as there would be a lot of energy loss i would suggest using VFD on the motor if it is motor driven compressor you will need to consult the compressor manufacturer in this case to know the minimum speed you can run the compressor on also to have the performance maps on such speed 

by the way if you are not using existing anti surge line for recirculation during operation i can help tell you how to modify your logic to do that 

regards

[Bobby Strain]

You should consult with the compressor manufacturer. They may be able to provide new internals so that the compressor operates efficiently. If you have a spare rotor, they may even be able to trim the impellers and manufacture new internals. You can install the modifications when it is convenient to shut down. You should not waste energy that is derived from fossil fuels. Harmful to the earth.

 

Bobby