Variable speed for compressor??

[madeleo13]

Hi there, assuming that two compressors, operating at the same conditions (air compressed, 100 psi discharge, same power, etc) one of them centrifugal and the other one dry screw, which one would you select to operate with a variable speed driver???

Thanks a lot for your help

 

[zdas04]

Centrifigul equipment loses both capacity and efficiency very quickly as you slow it down. I would vary the speed on the screw (positive displacement) and keep the centrifigul spinning fast.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

 

[quark]

I agree with Zdas. Moreover, you will have surge problems if you go with variable speed centrifugal compressor. (as you reduce speed, the hydraulic head also gets reduced but you should require your compressor to run at same thermodynamic head as you have initially)

On the other hand a screw chiller can develop same pressure even if you reduce the speed (PD machines work on back pressure principle)

Regards,

 

[roaling]

I fully agree with above replies. Just a question: why you do not use the capacity control capability of the screw compressor ?