A compressor going into stall is like jumping off a cliff with a bungee cord. If the bungee cord has no losses to dampen the oscillation, we have something akin to surge. A 0.5% drop in efficiency can occur for each surge cycle.
In part 3 we start a list of the essential concepts needed to understand what is most important and what to do to help make a loop meet process objectives. The concepts are presented in the broadest possible terms to provide a perspective that can be used in a wide spectrum...
Compressor surge is the fastest gas dynamic phenomena. A precipitous drop in flow occurs in 0.05 seconds and subsequent flow reversals occur every 1 to 2 seconds. The speed of response requirements for control valves, measurements, and controllers are extraordinary.
We conclude this series with a look at control schemes that can increase process efficiency for distillation control, compressor control, and neutralizer control. These control schemes can inherently reduce process variability and controller tuning difficulty and for compressors increase onstream time.