influence of gas composition on the compression efficiency

[fons]

Hello!
Can somebody help me with the question how does the gas composition influence the compression efficiency. How big differences should I expect from a centrifugal compressor for CO2, air or O2 and why?

 

[BigInch]

This is a nice general summary of what to expect,

http://www.jmcampbell.com/november--2008

Come back if you have any specific questions.

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"Pumping accounts for 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[dcasto]

centrifugal compressors put up constant head at a constant speed. so, the inlet gas density times the head from the compressor curve equals differential pressure. At the same temp and press, then the gas mole weight is the main variable. SO, AIR =29, O2 =32 and CO2 = 44. The compressor having air puts up "X" psi, then O2 will be "X"/29 * 32 psi and CO2 will be "X"/29 * 44, this 150% more pressure differntial on CO2 than air and therefore more work is required.