Exergy analysis for the design and optimization of NGL recovery process

Abstract

Thermodynamic analysis and optimization method is applied to provide design guidelines for improving energy efficiency and cost-effectiveness of NGL recovery processes. Exergy analysis is adopted in this study as a thermodynamic tool to evaluate the loss of exergy associated with irreversibility in NGL recovery processes, with which conceptual understanding on any inefficient design features or equipment can be gained. NGL processes are modeled and simulated within UniSim® simulator environment, with which detailed thermodynamic information are obtained for calculating exergy loss. In order to systematically improve energy efficiency of NGL processes, the optimization framework is developed by minimizing overall exergy loss, as an objective function, subject to product specifications and engineering constraints. The optimization is carried out within MATLAB® with the aid of a stochastic solver based on genetic algorithms. The process simulator is linked and interacted with the optimization solver, in which optimal operating conditions can be determined. Case study is presented to illustrate the benefit of using exergy analysis for the design and optimization of NGL processes and to demonstrate the applicability and practicality of design method proposed in this dissertation.