VFD-compressor control 1

[edetaen]

.....currently the compressor in flash gas recycle unit are sized based on the flash gas from condensate stabilization trains. But the client thinks the condensate production would be much less than the design of 60000 BLPD. This means the quantity of the flash gas generation would also be proportionately lower. With regards to this, it was advised to use VFD for each machine so that they could be operated at lower speed depending on the process load. Otherwise at low load these machines (if fixed speed) would go to recycle and waste huge amount of energy. This would definitely increase the operating cost. Although VFD is there for machines start up but not for capacity control.
Another argument is speed control VFD is quite expensive which is not justified to save OPEX.
Can someone please advise .

Note these are reciprocating compressors of about 3MW.

 

[ScottyUK]

It's well within the capability of an MV drive, but is the machine capable of variable speed operation? If the VFD is already there then it would make sense to use it provided the machine is capable of variable speed operation. This is largely a question for the compressor manufacturer.

 

[waross]

Recip. compressors generally depend on the effect of the flywheel to smooth out the torque variations. They may not respond well to low speed operation. It will probably be just as efficient to use unloaders to cut cylinders in and out as needed.
Compressors consume very little power when unloaded.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Parchie]

Great one, @waross!