Jump to content



Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

Vertical Tank Selection

New Blog Entry

Low Flow in Pipes- posted in Ankur's blog

3

Centrifugal Compressor Off-Design Inlet Conditions Impact


6 replies to this topic
Share this topic:
| More

#1 Said Salim

Said Salim

    Gold Member

  • Members
  • 89 posts

Posted 10 August 2022 - 12:44 PM

Hi All

I have digitized all our centrifugal compressors performance curves and obtained correlations between polytropic efficiencies vs Inlet flow for all stages at different rpm. However, those curves are valid for design inlet conditions ( Pressure, Temperature and Composition). I am intending to improve those correlations to address all changes in the inlet conditions of each stage. Can any share supportive documents or references that address impact the off-design conditions on the obtained value of polytropic efficiencies.

Said Salim

#2 Bobby Strain

Bobby Strain

    Gold Member

  • Members
  • 3,301 posts

Posted 10 August 2022 - 02:56 PM

I would start with the curves you generated. Then calculate polytropic efficiency by taking measurements. See if it fits. As I recall, the curves should be reasonably close if the inlet conditions are not greatly different from design.

 

Bobby



#3 Pilesar

Pilesar

    Gold Member

  • Members
  • 1,045 posts

Posted 10 August 2022 - 05:19 PM

Multistage centrifugal compressors are tough to extrapolate too far away from measurements. There are simulators that will model the compressor 'by the wheel' instead of 'by the stage' but the usual steady-state simulators do pretty well adjusting performance based on changing conditions. Compressor vendor curves have a tolerance that I think is too broad. Measured values give better accuracy. Use the Fan Laws to estimate how performance would change with different inlet conditions if you do not have a simulator do this for you. Assume the measured efficiency is fixed for the same fouling condition -- that is about the best you can do. 



#4 breizh

breizh

    Gold Member

  • Admin
  • 5,633 posts

Posted 10 August 2022 - 06:15 PM

Hi,

You may find tips in the document attached .

Breizh



#5 Said Salim

Said Salim

    Gold Member

  • Members
  • 89 posts

Posted 10 August 2022 - 07:30 PM

Bobby
There is minor changes in pressure and composition. However, the difference is significant in inlet temperature especially when you know thay our cooling system is dependent on sea water temperature which is varying during the day itself. Also, for air compressors inlet temperature is affected by ambient teamperature which is changing between summer and winter by more than 7 degrees C.

#6 Bobby Strain

Bobby Strain

    Gold Member

  • Members
  • 3,301 posts

Posted 10 August 2022 - 10:36 PM

Get the data. That's the only way you can confirm anything. Of course, the data must be accurate.

 

Good luck,

Bobby



#7 Said Salim

Said Salim

    Gold Member

  • Members
  • 89 posts

Posted 11 August 2022 - 10:21 AM

Bobby
I am getting the actual data to calculate the efficiencies. However, my idea is to take design data to the new conditions and see how design values will change and finally compare those values to the actual values.




Similar Topics