TO CALCULATE GAS COMPRESSOR FLOW 1

[chemjay]

We had Centrifugal Lean gas ( Natural Gas) compressors which are driven by Gas Turbines. Lean Gas molecular weight is nearly around 16.5 , suction pressure is 10.7 kg/cm2 (g) & discharge pr. 24.5 kg/cm2(g). Suction Temp. is around 23 Deg.C. , inlet flow is 170 TPH with Antisurge full close and speed is 95% of full rpm.
Some one get an idea to reduce suction temp. to 15 Deg.C. from 23 Deg.C. My query is that will flow through compressor increases at same 95% rpm, remaining all the condition same.

 

[pmover]

to achieve lower inlet temperature to the compressor implies that heat must be removed from the gas. depending upon location and economics, this is accomplished by cooling methods (air coolers, refrigeration, etc.).

your "query" (last sentence) is true as volumetric/mass flow increases with lower inlet temps and other inlet gas conditions remaining the same.

hope this helps!
good luck!
-pmover

 

[dcasto]

oh and discharge pressure will go up!

 

[chemjay]

Thank you Sirs,
But Is there any simple formula to calculate flow in both the conditions, as we know that by reducing suction Temperature Gas volumetric & density will change but Mass flow will remain same ?

 

[dcasto]

Centrifugal compressors obey the fan laws. So they have a constant Actual Cubic Feet per Minute (ACFM) at a given speed. So, at your base condition you know the mass rate and the density so you know the ACFM. At the new conditions you know the density and now the ACFM so you get the mass rate. density1/density2 = mass1/mass2.

Next, the compressure emparts head to the gas in terms of feet and its a constant head at a constant speed. so you know the head because you know the pressure in and out and the desity. density1/density2 = deta P1/delta P2