Patent ID: 6652240
Filing Date: 2003-11-25
Classification: F04C,Y10T

Abstract:
A method of operating a compressor system having a plurality of throttled inlet rotary screw compressors, said method comprising the steps of:(a) establishing a set-point pressure; (b) measuring the actual pressure of the fluid in the compressor system; (c) determining which of the throttled inlet rotary screw compressors are operating; (d) calculating the actual volumetric flow rate of fluid in the compressor system by: (i) sensing the inlet pressure of each operating throttled inlet rotary screw compressor; (ii) converting the inlet pressures to corresponding outlet volumetric flow rates; and (iii) summing said outlet volumetric flow rates; (e) determining the online volumetric flow rate capacity, wherein the online volumetric flow rate capacity is equal to the sum of the corresponding rated volumetric flow rate capacities for each of the operating throttled inlet rotary screw compressors; (f) determining the excess volumetric flow rate of the compressor system, wherein the excess volumetric flow rate is equal to the online volumetric flow rate capacity minus the compressor system's actual volumetric flow rate; and (g) unloading one of the plurality of rotary screw compressors upon sensing that the actual pressure of the fluid in the compressor system is greater than the set-point pressure and the corresponding rated volumetric flow rate capacity for said one throttled inlet rotary screw compressor is less than the excess volumetric flow rate.