Exergy Analysis and Optimization of Natural Gas Liquids Recovery Unit

Abstract

The Natural Gas Liquids (NGL) recovery unit is one of the processes that requires cooling. The sweetened gas enters this unit after the dehydration stage, and the final product called NGL Product is stored and ready for consumption or export. In this research, the first, one of the NGL units, is simulated with HYSYS software. Three types of processes with different cooling systems are studied using the exergy analysis method. Joule–Thomson’s combination with the expander is selected for its high exergy efficiency, and the exergy efficiency function has been selected as the objective function 1 to optimize this process mathematically based on this study’s findings. The critical term in this objective function is the work of the compressors and turboexpanders in the process. After defining the optimization problem, the problem is optimized by two genetic algorithms and SQP, considering the process constraints and the process’s initial conditions. Finally, using the genetic algorithm’s data application to the simulated process, a 15% increase in the plant’s exergic efficiency was observed.