On our FCU wet gas compressor, we have an orifice plate that operates from 0” to 100” of water DP. The flow is typically high. The meter reads full scale – at an orifice plate DP of 95” H2O, or 3½ psi pressure drop. As the compressor suction pressure is only 3 psig, it seems to me that we are wasting a lot of compressor capacity on that orifice plate. What do you suggest? Also, high compressor suction pressure backs air out of the regenerator.
Eliminate the orifice plate. Use the vapor outlet nozzles of the upstream K.O. drum, as a restriction orifice. Measure the DP between the drum and the compressor suction. You can back-calculate the “orifice” coefficient based on the unit material balance. I’ll show you how to do this, if you send me the operating data. Looks like you can increase compressor capacity by about 10%, with zero investment cost.