Developing Centrifugal Compressor Train Optimization Models for Performance Evaluation

Abstract

Recent advances in numerical optimization software now allow problems arising in the evaluation of complex centrifugal compressor train performance to be solved readily by machinery users. Analyses of compressor operations often require consideration of multiple nonlinear constraints involving pressure, temperature, flow rate, composition, and power. Based on these constraints, the operational boundaries of the machinery must be evaluated. Frequently operating points of greatest interest exist where one of the operational variables, such as flow rate, is maximized subject to operational constraints. A methodology is proposed that can be used to apply commercially available optimization software to problems of this type. A review of gas equation of state relationships needed to determine thermodynamic properties is provided, as well as methods for calculating compressor discharge pressure based on polytropic head and efficiency. Recycle control is considered and a model is proposed.