Apparatus for optimal loadsharing between parallel gas compressors

A gas compressing system, comprising:

• a plurality of n compressors connected in a parallel pneumatic circuit, each compressor in the plurality of n compressors each having a suction line in pneumatic communication with a common suction manifold configured to receive a gas stream from an upstream source and each having a discharge line in pneumatic communication with a common discharge manifold configured to deliver compressed gas to a downstream load;
• a plurality of n suction flow transducers configured to measure a suction line flow rate of gas flowing through each suction line into the plurality of n compressors and further configured to produce signals representing said flow rates;
• a plurality of n suction pressure transducers configured to measure a suction line pressure of gas flowing through each suction line and produce signals representing said pressures;
• a plurality of n discharge pressure transducers configured to measure a discharge line pressure of gas flowing through each discharge line from the plurality of n compressors and produce signals representing said pressures;
• a discharge flow transducer configured to measure a discharge line flow rate of gas flowing through the common discharge manifold and produce a signal representing said flow rate;
• a discharge manifold pressure transducer configured to measure a discharge pressure of gas in the common discharge manifold and produce a signal representing said pressure;
• a process controller having an input signal being either representative of the discharge line flow rate signal or representative of the common discharge manifold pressure signal, and generating an output signal representing an aggregate load demand for all n compressors based upon an operator set point;
• an adaptive load sharing optimizing controller configured to generate n−1 signals representing load split parameters λi for the plurality of n compressors based on suction line pressure signal and suction line flow rate signal in each suction line and discharge line pressure signal in each discharge line in the plurality of n compressors and the aggregate load demand signal provided by the process controller;
• and
• a plurality of n speed demand computation modules configured to compute a speed demand signal for each compressor in the plurality of n compressors, based on the signal representing load split parameters λi, and send these speed demand signals to each compressor in the plurality of n compressors, to control the speed of each compressor in the plurality of n compressors.