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Monday, September 10, 2012

Centrifugal Compressors


I attended your seminar in Sasol, Secunda in 2008. Our problem is that when we open our compressor spill-back, which we thought would stop surge, it sometimes makes the compressor surge. What is our problem?

--H.K. Masa

 
Your problem is that the spill-back flow is hot. This reduces vapor density. Which reduces compressor delta P. Which reduces compressor discharge pressure. Which allows gas flow to stop and reverse. I had this exact problem in 1974 on my alky unit in Texas City. I desuperheated compressor suction by injecting a spray of liquid isobutane into the suction. This would quickly bring the compressor out of surge. Hope this helps.

--Norm

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