Large centrifugal air compressor

[ColourfulFigsnDiags]

Sizing a large air-compressor (~870kW). This is the first air compressor calc I've done and I'm a little concerned that I've made an error.

Based on Vendor supplied test data for a centrifugal compressor (given compressor speed, inlet f/r, dens, suct pres, disch pres, suct Temp, disch temp, Z, k, and MW) ... I'm calculating a polytropic efficiency of about 39.6% and an isenotropic efficiency of about 38.3%. However, when I look up standard text books (eg C&R VI, Perry, Compressed air and gas data- Loomis ...) any graph they have shows polytropic efficiencies from about 60%-90% ... nothing like close to the range I am calculating for the test compressor.

Is it likely I have made an error, or is this just one damn inefficient machine?

Read the Eng-Tips Site Policies at FAQ731-376

 

[TD2K]

The isentropic efficiency should be easy to check. Put your suction and discharge compressors on a Mollier chart for air and see what the isentropic efficiency calculates that way versus your calculations.

 

[ColourfulFigsnDiags]

Yeah ... checked in HYSYS too and it comes up with the same answer ... just a very inefficient compressor I guess!

Read the Eng-Tips Site Policies at FAQ731-376

 

[BenThayer]

one of the best books i have seen that is user friendly for the beginner is:

Estimating Centrifugal Compressor Performance
Process Compressor Technology Volume 1 by Ronald P. Lapina

Published by Gulf Publishing Company Book Division

great reference and I think I bought it years ago through one of the McGraw Hill Engineer's Book Club offers.

 

[ColourfulFigsnDiags]

Thanks- will try and find it!

Read the Eng-Tips Site Policies at FAQ731-376