5 replies to this topic

[CHEMSTRONG]

Dear Sir,

 

For Centrifugal Compressor with Pure gas feed( such mixture of methane , ethane, propane, and butane) , Polytropic Efficiency is dependent upon pressure ratio, temp ratio and K value (Cp/Cv). But it is also dependent upon Gas Flow rate ??? Please advice. As in Polytropic Efficiency formula, flow is not there. so i have a query if it is dependent upon flow also? If yes, in particular operating range ?

 

Best Regards,

 

[PaoloPemi]

it's not constant,
many books include the polytropic efficiency chart proposed by Rollins (1973), there is also a generic correlation (for the range between 0.7 and 0.75)

efficiency = 0.61+0.03log(flow),

where flow = gas capacity in cfm
 
but, for accurate results, better to ask the manufacturers...

[breizh]

Hi,

Consider this excel sheet I prepared a few years ago .

Good luck

 

Breizh 

[CHEMSTRONG]

Hi Breizh Sir,

 

You are really superb in supporting and advising junior guys like me .

 

Do you have any idea about Compressor Efficiency calculation for Ethylene plant CGC compressor ? They call it water wash adjusted efficiency 

 

Thanks.

 

Best Regards

[breizh]

Hi,

Sorry I can offer more for the time being.

Breizh

[PaoloPemi]

chetanhm2,

 

if you mean the prediction of a cracking gas compressor performance see also the answers provided in your previous thread

https://www.cheresou...ompressor-query

the point is not about simulation (in addition to commercial simulators mentioned in the thread you can find free versions of tools capable to simulate single and two-phase polytropic stages, see for example Prode) but the required parameters (as efficiency) which are not easy to estimate...
these values can be provided by manufacturers or one can estimate by interpolation and fitting of measured data...

Edited by PaoloPemi, 24 February 2022 - 02:38 AM.