Method for reducing the pulsation level in a multi-compressor plant employing reciprocating compressors

A method for reducing a pressure pulsation level in a multi-compressor plant, the multi-compressor plant comprising a plurality of reciprocating compressors connected in parallel to a gas piping system, each reciprocating compressor being driven by a respective motor, the method comprising:

• assessing a number of reciprocating compressors running in parallel;
• determining a worst operating condition of a single reciprocating compressor of the plurality of reciprocating compressors running by determining a highest peak-to-peak value for a pressure pulsation sum of the single reciprocating compressor of the plurality of reciprocating compressors running;
• determining a worst operating condition imposing 0° phase among the plurality of reciprocating compressors running in parallel by determining a highest peak-to-peak value for a pressure pulsation sum of the plurality of reciprocating compressors running in parallel;
• determining a lowest pressure pulsation sum imposing a different phase among the plurality of reciprocating compressors starting from a phase that is equal to 360°/Nc, wherein Nc is a maximum number of reciprocating compressors in operation;
• determining a best phase shift among the plurality of reciprocating compressors when a pressure pulsations peaks generated by each reciprocating compressor is distributed so as to avoid superimposition under a condition that, for each capacity control case, a resulting main frequency of combination is a highest possible;
• starting a first motor of a first reciprocating compressor of the plurality of reciprocating compressors;
• and
• starting in succession each other motor and synchronizing all of the motors between each other with the determined best phase shift by coupling the reciprocating compressor crankshafts with respective motor shafts with respective mechanical shifts.