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Surge control in compressors

  • US 4,971,516 A
  • Filed: 08/07/1989
  • Issued: 11/20/1990
  • Est. Priority Date: 05/04/1988
  • Status: Expired due to Fees
First Claim
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1. In a method for controlling a compressor in which a control valve is employed in an electronic circuit to control the recycle of gas from the discharge outlet to the suction inlet to the compressor, the steps of:

  • measuring the sonic velocity, that is the speed of sound in the gas, and the rate of volumetric flow, Q, of gas through said operating compressor,measuring the rate of speed, N, of said operating compressor,establishing a Q/N ratio from the values Q and N generated by the operating compressor,establishing a set point Q/N ratio based on a rate of gas flow above which compressor surge can occur, andcomparing the Q/N ratio of the operating compressor with the Q/N set point ratio such that a measured Q/N ratio in the direction of a lower gas flow will open the control valve and permit the flow of recycle gas from the discharge outlet of the compressor to the suction inlet of the compressor, and return of the Q/N ratio of the operating compressor to the set point Q/N ratio will close the control valve to cut off the flow of recycle gas, wherein the Q/N set point ratio is constantly redefined based on measured gas sonic velocity during operation of the compressor.

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