Optimal retrofit of a CO2 capture pilot plant using superstructure and rate-based models.

Finding an optimal retrofit for existing plants is a very challenging problem, since it often requires rigorous process models for describing the currently operating process and consequently the corresponding optimization problems typically become very complex. One of the possible ways to optimize such a complex problem is to limit the process alternatives considered, which bears the risk to overlook the optimal solution. Herein, a superstructure-based methodology is proposed for optimal retrofit of a CO 2 capture pilot plant using rigorous rate-based model for the reactive distillation. The methodology is applied to the Boryeong pilot plant in South Korea. Process alternatives implemented in the superstructure are selected based on thermodynamic analysis of the pilot plant and operational experience. As a result, the problem size of the superstructure can be substantially reduced and optimization can be performed using commercially available process simulators and optimization solvers. The optimum process configuration and operating conditions are obtained stochastically using a genetic algorithm. Results indicate that the optimum retrofit process includes three stages solvent recirculation, lean vapor recompression, and mechanical vapor recompression. Thermal energy and total energy consumption in the optimal retrofit process are reduced about 59% and 27%, respectively. [ABSTRACT FROM AUTHOR]