A New Look at Performance Analysis of Centrifugal Compressors Operating With Mixed Hydrocarbon Gases

Abstract

A program was undertaken to examine the thermodynamic performance of multistage centrifugal compressors operating with hydrocarbon gas mixtures. Experimental aspects included methods for accurate measurement of such variables as the pressure and temperature of the process gas stream before and after each compressor stage and the acquisition of gas samples and their analysis. Emphasis was placed on development of an analytical technique using an equation-of-state representation for the gas mixture to evaulate its thermodynamic properties. This permitted integration of the exact thermodynamic equations developed by Schultz in 1962 for describing the compression path of the gas stream. The effect of the variation of the so called polytropic volume exponent, n, on the performance parameters was examined. The special case of the polytropic path, i.e., n considered a constant, was shown to be acceptable in most practical applications. The technique was validated by examples of field tests and by comparison with test cases reported in the literature.