This paper investigates the effects of multistage centrifugal compressor fouling on the performance of machine and plant operation. A thermodynamic model for the compressor has been developed for studying in-situ compressor performance deterioration due to internal component fouling at high power settings. The four casings, six sections compressor train is one of the critical process loop components in meeting ethylene production targets in a large scale petrochemical complex. The compressor handles process gas which is a complex mixtures of cracked gases (17 constituents) containing measurable concentrations of high molecular weight hydrocarbons. The model requires minimum inputs (pressure, temperature, flow, speed) from readily available instrument sensors and derives all the necessary information that predicts overall performance. Various parameters characterizing multistage compressor health condition were investigated. The study revealed that fouling of early stages adversely affect the polytropic efficiency of later stages. The model is cost effective in operation and is fully capable of detecting small changes occurring periodically in the compressor. A simple predictive monitoring scheme was developed for assessing the degree of compressor fouling that will strongly help engineers responsible for decision making.

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