Compressor Surge And Anti-Surge Control

Compressor surge has been discussed often on the forum with many posts dedicated to the subject. Despite all these discussions there was a serious lack of the basic scheme of anti-surge control. Today's blog entry tries to remedy the situation. I am presenting an excel attachment related to basic anti-surge control which should help all those who have been trying to understand what anti-surge control is all about. Mind you, this is a compilation and not any research. The reference has been clearly mentioned in the excel sheet

Before all of you make a beeline to download the excel attachment, I would like you to read a simplistic definiton of what compressor surge is all about, which I liked very much and am reproducing from "ChemicalProcessing.com" and originally provided by Dr. Meherwan P. Boyce an authority on compressors.
The link for what I am reproducing is:

http://www.chemicalp...s/2007/125.html

A very basic description of the surging phenomenon is that the gas streamlines normally at the diffuser entrance and sometimes at the impeller eye to exhibit a high incidence angle and stall, not unlike an airplane going into a sudden climb. When the stall is reached, the gas in the compressor ceases to flow forward in the compressor and a reverse flow takes place. The reverse flow collides with the forward flow, making the noise one hears when a centrifugal compressor goes into surge. This phenomenon is accompanied by a sudden rise in discharge temperature. Surge prevention can be accomplished by bypassing discharged cool gas back to the inlet using an amply sized valve. The quantity of gas must be equal to the surge flow (taken from the compressor pressure volume curve plus a small margin, such as 10%).

Hope all of you enjoy reading this blog entry and the attached excel worksheet. I look forward for your valuable comments on today's blog entry.

Download the MS Excel file that accompanies this blog entry in the download section:
Compressor Surge and Anti-Surge Control - MS Excel Spreadsheet


Regards,
Ankur.