2 replies to this topic

[vinod]

Sirs

Can anyone tell me what is the sizing criterion for the single phase gas lines in the inter stage compressor piping – suction and discharge? I know for compressor suction / discharge line, by thumb rule the velocity should fall within 20 m/s on suction side and 30 m/s on discharge side. Also it has pressure drop criterion also. What would it be for an inter-stage compressor…like in my case I have a LP, MP and HP compressor and the discharge of LP is inlet to MP and discharge of MP to HP, so what would be the sizing criteria in terms of velocity for MP compressor piping..?

Regards

Vinod

[Art Montemayor]

Vinod:

I've said it many times before, but I'll repeat it again here: I always design for the economical, practical pressure drop in a line and always check to make sure I'm within a safe velocity "window" to avoid errosion, noise, etx. The pressure is the driving force for a fluid; therefore, it is the FIRST priority to meet.

The same applies to a gas compressor - regardless whether reciprocating or centrifugal - except that in this case, the pressure drop is of an ultra high priority because of the extra energy it presents to the compression operation. You want to minimize the pressure drop between stages as much as possible. The optimum interstage pipe size is often already determined by the compressor manufactuter - it has to be that way because the machine has to be manufactured with pipe flanges at each stage. You are free to increase the interstage piping size if you wish to reduce the pressure drop even further if you so desire. I certainly would never entertain reducing the manufacturer's interstage pipe size.

Why are you asking for sizing and velocity information on a compressor? Are you planning to manufacture your own compressor(s)? I doubt it. Why don't you follow the manufacturer's indicated (or supplied) pipe sizes? If you want to learn, then ask your manufacturer what criteria is followed. Each manufacturer has probably developed their own method(s).

[vinod]

Thanks a lot Art