4 replies to this topic

[Sharoon.Gill]

We have a two-stage air compressor  and a cold stream with which we have the potential to exchange heat and reduce the inlet air temperature. Suppose the inlet air conditions at atmospheric and we can bring about a change of 10 deg C in the inlet temperature. How significant will be the reduction in the power consumption. Will it be worth installing a heat exchanger and its auxiliaries.?

I have attached the excel sheet which which gives us the  indication of the polytropic index, we assume it constant and estimate the exit temperature and hence the work reduction..it does not show any significant results Is it the  Installed compressor efficiency.xlsx   152.71KB   12 downloadscorrect approach?

[PingPong]

Question can not be answered without all performance and efficiency curves of the compressor, as provided by the vendor.

 

Note also that an additional exchanger at the compressor inlet will add pressure drop and thereby reduce the compressor inlet pressure.

 

My gut feeling tells me that it is not worth the trouble, as any gain due to decrease in inlet temperature may be completely negated by decrease in inlet pressure, but without the compressor curves I cannot be sure.

 

Probably it is better to use the cold stream in some way to improve the performance of the intercooler, e.g. by precooling the cooling medium.

[Sharoon.Gill]

Thanks for the remarks,

if you can tell from a case study if temperature reduction in air has resulted in better performance or power reduction or will it really be beneficial, it will be helpful!

[PingPong]

Maybe you missed my point: I don't think there will be a benefit.

If the air temperature to the first stage is lowered from 35 to 22 ^oC, while the suction pressure remains 96 kPa, the power consumption would drop by 16 kW.

However adding a heat exchanger will lower the suction pressure. If the pressure drop of that heat exchanger plus piping would be 3 kPa (30 mBar) then the suction pressure would drop to 93 kPa and the power consumption would not drop at all.

[Sharoon.Gill]

Ok,thank you very much for your help!