Dear All I want to k

[keyhanafshar]

Dear All

I want to know what sort of modifications should be done (if neccsary) to an already existing centrifugial compressor compressing a gas with specific gravity of 0.662 if we change it to a gas with specific gravity of 0.852?

 

[MortenA]

If your flow in mol (SCF, Nm3 or whatever) pr hr/day remain constant the your mass flow will go up and thereby the duty - you should check that.

Best Regards

Morten

 

[butelja]

Your horsepower will go up in direct proportion to the density if the volumetric flow is unchanged.

 

[pmover]

If all inlet process conditions (i.e. pressure, temperature, and flow) at compressor inlet flange remain the same, then butelja response regarding HP is valid. Additionally, discharge pressure & temps will increase, which is a process condition to be analyzed and the compresor case ratings should be checked.
Other concerns are mechanical seals (or sealing system) at higher pressures and surge control. Varying or changing molecular weights will likely shift the surge control line. Depending upon surge control mfg., the control system will need attention to safely operate the compressor (i.e. have a surge margin) away from the surge line.
Lastly, I recommend contacting the compressor mfg. and requesting compressor performance curves be generated for the new inlet conditions (inlet conditions must be provided). The compressor mfg. will gladly generate these performance curves without charge - if they do, do not buy equipment from them. These curves will be useful in plant/unit operation.
Mechanical seals or sealing system should be verified at the new conditions (inlet/outlet). Again, this can be accomplished by the compressor mfg.
Good Luck!