Centrifugal Compressor Discharge Pressure

[liberoSimulation]

Does anyone have an idea about the proper design discharge pressure of a big centrifugal compressor (Driven by 60MW steam turbine). I think API calls for shut off pressure that is much higher than the max operating discharge pressure. If this is the case, piping and downstream equipment located within the compressor envelope shall be designed to the shut off pressure and PSVs set points will be close to this with some margin (buildup pressure).

Any help or experience is appreciated

Regards

 

[roker]

hi,

what is the design and test pressure of the compressor?

regards,
roker

 

[TD2K]

What API spec are you referring to? API 617?

I don't understand this comment "I think API calls for shut off pressure that is much higher than the max operating discharge pressure". What does the API standard you are referring to state?

What is your question?

 

[liberoSimulation]

roker :such information is still not available as the design has been done since few weeks.
TD2K : I know shut off pressure is much higher than the max operating pressure and this what I did mention in the question,
Actually I don't recall which API standard that calls for designing the stages based on the shut off pressure, and if this is mentioned somewhere in the well known standards, then the piping and equipment downstream of the last stage of centrifugal compressor will be designed based on the shut off pressure.
Now, we have considered the max operating pressure with a safety factor of about 10% for the design pressure of downstream piping and equipment.

Regards

 

[Samiran]

I don't understand at what stage of design you are in. But once you get the compressor curves you will be able to get the max head (near about surge). Now that may or may not determine your design pressure downstream. Why I say may not because you may take advantage of surge control valves opening which will drop the discharge pressure. But in my opinion design should be based on the max head at the top end of the curve.

 

[TD2K]

For the gas, calculate the volumes occupied by the gas in the piping and vessels. Where you have various pressures, you need to do this for each pressure. Calculate the density of the gas for each pressure/temperature and the resulting mass of gas. For the liquid, calculate the volumes. It's just time consuming.

Use a spreadsheet ;-)