Centrifugal Compressors

Dear Mr. Norman Lieberman – Thank you and Mrs. Lieberman for writing Working Guide to Process Equipment. A question I have is when our compressor begins to surge, the surging seems to get louder. Then when I lower the discharge pressure to stop the surge, it does not help, even though it’s the same discharge pressure we had before the surging stared. Please explain to me.

--Kia Vala

 

Mr. Vala – Once surging starts, the gas inside the compressor case goes forward, then back, then forward,  and then back, etc. This causes the gas to become hotter and less dense. The reduced density reduces delta P developed by the compressor, which promotes gas flow reversal.

--Regards, Norm Lieberman