Hello Everybody, One of my company Customer want us to provide piping pulsation analysis for gas compressor station where theoretically pulsation sources are two centrifugal compressors. I know that Puls software is not designed for piping pulsation with centrifugal compressors. Centrifugal compressors particularly in these times should not be considered as pulsation pressure source, however it has been assumed and defined by the Customer that these pulsation sources should not exceed 10% of maximum pulsation value peak to peak based on API 618 in Puls software for given rpm of compressors? 1.Based on requirement of 10% how exactly should I define the pulsation source to perform pressure and force simulation vs frequency in Puls? Would 10% of the pressure pulsation curve based on API 618 be my input, and having that I should calculate forces vs frequecy for each node then the harmonics would be imported to Autopipe (harmonics described by damping of ~2%, frequency for the 1-st, 2-nd, and 3-rd harmonics with phases and forces acting in different direction)? Can I find any example in Bentley resources that could show me practical way of solving problem mentioned above? Given data:
Suction side – 4MPa
Discharge side – 6,5MPa
Methane gas flow – 140 thousand m3/h
2. If the piping model in Puls will have less than 400 nodes for both suction and discharge lines it seems to me that option 1 of Puls software be good enough to make pressure and dynamic forces acoustic simulations (with two centrifugal compressors) ? Am I correct thinking so?
Best Regards
Robert Augustyn
1. PULS allows for modeling pressure pulsation source, however it is necessary to know the frequency characteristics of this source. In this case it does not seem that you have any model of this kind. Also I am afraid API618 limits have nothing in common with centrifugal compressors.
If you could 'simulate' numerically the loading (i.e. pressure pulsation source, no matter how you gain the spectrum of this pulsation), you would be able to apply it in PULS. Then you could get the dynamic forces to be applied in AutoPIPE, and further calculate dynamic response.
I believe you should return to you customer and discuss what are true goals of this analysis.
2. Yes, I believe that 400 nodes is the model contents limit, however I am not sure about how many pressure pulsation sources are allowed for Option 1. This would be easy to verify - just build the sample model and insert predicted (for analysis) number of boundary conditions of this kind.
Best regards,
Maciej Rydlewicz, PhD Eng.
maciej.rydlewicz@softdesk.pl
+48 512206994
Thank you Maciej for your response. I may call you to try to discuss this issue when appropriate time will come.
Best regards
Hello Robert,
To add a little more to what MaciejRyd mentioned above, see WIKI here for limitations for nodes and BC in each edition of PULS.
Regards,
Mike DattilioBentley Systems Design AnalystDesign Engineering Analysis group===================================================