Load Sharing between 2 Nos. Centrifugal Compressors of Different Capacity and Discharge Pressure

[sanchit11]

Hello Everyone,

I am having 2 nos. of centrifugal compressors connected from same suction header at pressure of 10 kg/cm²g

Capacity of one compressor is 5 MMSCMD and have discharge pressure of 27 kg/cm²g and capacity of other compressor is 3.5 MMSCMD and have discharge pressure of 60 kg/cm²g.

Please advise me that, is load sharing possible between these two compressor and if possible then what is required for achieving the same in term of instrumentation.

regards
Sanchit

 

[jbattershell]

if both compressors are connected to the same discharge header, the maximum discharge pressure in that header is limited to what the lower pressure rated compressor can reach (27kg/cm2). the other compressor with a higher discharge pressure must operate at its normal design pressure (or close to it) or it will be in severe choke/overload condition. therefore, the higher pressure compressor would have to have a pressure reducing valve downstream of it's discharge to reduce the pressure down the header pressure of the lower pressure compressor. that is possible but is not an efficient way to operate that compressor since it would be using power to compressor gas up to the high pressure and then a valve is used to reduce that pressure down to a lower pressure, essentially throwing away the energy used to compress the gas.

if the higher pressure compressor is variable speed, you might be able to reduce the speed enough to lower the discharge pressure down closer to the discharge pressure of the lower pressure unit.

this situation you ask about is more complicated that what can be answered in a forum though. you should engage the compressor experts within the company or the OEM that built the compressors.

 

[racookpe1978]

You used the word "compressor" but I sense English is not your primary language.

These machines are compressing "gasses" that do not condense nor vaporize in the piping, correct? You are NOT trying to pump liquids?