Measuring The Thermodynamic Performance Of Multistage Compressors Operating On Mixed Hydrocarbon Gases

Abstract

Performance measurement of multistage centrifugal compressors is often required to assess their current operating condition, e. g., to discover fouling or to gauge the operation of the compressor in relation to the overall process, especially when compressing mixed hydrocarbon gases. Generally, such field testing has not been successful in the sense of obtaining accurate and reproducible results. This paper describes the development and validation of a unified testing and data analysis procedure for field evaluation of centrifugal compressors. Experimental aspects included developing instrumentation to obtain accurate measurements of pressure, temperature, and flow rate at the suction and discharge locations of individual stages. Sampling of the gas streams and the subsequent compositional analyses were given particular attention. Equation of state computer codes were prepared to convert measured compositions to thermodynamic properties as a function of pressure and temperature. Finally, procedures were developed and reduced to computer codes for calculating stage-by-stage the work input to the gas and the compressor efficiency. Experience has demonstrated the validity of this approach to performance testing and it is now being adapted to on-line, computer-based monitoring.