Optimal design and sensitivity analysis of post-combustion CO2 capture process by chemical absorption with amines

This paper focuses on the optimization of the specific total annual cost (operating costs and investments) of a post-combustion CO2 capture plant with chemical absorption and on the sensitivity analyses of all of the model parameters. Using a mathematical programming approach and a detailed model the optimal design of the entire process (absorption, amine regeneration, compression stage, and energy recovery system) is investigated. For a more general discussion, two optimal designs that differ on how the total operating cost is computed are discussed. In the former case, the operating cost includes the MEA and H2O make-ups and cooling water costs. In the second case the cost of the steam required in the reboiler and the total electricity cost are also included. In both cases, the entire process is simultaneously optimized in order to determine the optimal sizes of each process unit and the operating conditions that minimize the specific total cost. The solutions obtained for both objective functions are compared in detail. Then, sensitivity analyses are performed in order to identify and to investigate how the two optimal designs are modified with the variations of the model parameters. Among others, the results revealed that the specific total cost varies from −0.10 to 7.7% when the parameters are ±2.5% of their nominal values. However, significant differences are observed in the optimal sizes in several process units (variations up to 118.30% depending on the case) and also in the requirements of steam, electricity and cooling water (variations up to 27.60% depending on the case). The numerical results that support the conclusions are presented and discussed through several optimization solutions.