LOAD SHARING METHOD AND APPARATUS FOR CONTROLLING A MAIN GAS PARAMETER COMPRESSOR STATION WITH MULTIPLE DYNAMIC COMPRESSORS

摘要

A method and apparatus for maintaining a main process gas parameter such as suction pressure discharge pressure, discharge flow, etc. of a compressor station with multiple dynamic compressors, which enables a station controller controlling the main process gas parameter to increase or decrease the total station performance to restore the main process gas parameter to a required level, first by simultaneous change of performances of all individual compressors, for example, by decreasing their speeds, and then after operating points of all machines reach their respective surge control lines, by simultaneous opening of individual antisurge valves. In the proposed loadsharing scheme, one compressor is automatically selected as a leading machine. For parallel operation, the compressor which is selected as the leader is the one having the largest distance to its surge control line. For series operation, the leader has the lowest criterion "R" value representing both the distance to its surge control line and the equivalent mass flow rate through the compressor. The leader is followed by the rest of the compressors, which equalize their distances to the respective surge control lines or criterions "R" with respect to that of the leader.