Techno-economic analysis and optimization of a CO2 absorption process with a solvent looping system at the absorber using an MDEA/PZ blended solvent for steam methane reforming

Abstract

Advanced CO2 capture processes for steam methane reforming that supplies large quantities of H2 to industries are critical for cost-effective blue H2 and CO2 production. In this study, a pre-combustion CO2 absorption process with a novel solvent looping system was developed to capture CO2 from SMR gas at a flow rate of 6946.5 kmol/h and 21 bar. A techno-economic analysis of the advanced absorption process using MDEA/PZ blended solvent was performed with respect to five key operating parameters. For 90 % and 99 % CO2 capture rates, the minimal reboiler duties were 0.622 and 0.751 GJ/CO2 ton, which were approximately 70 % lower than those of conventional post-combustion CO2 capture processes. Despite a significant increase in the CO2 capture rate (90 % to 99 %), the increase in energy consumption and OPEX was only 4 % while using the novel blended-solvent looping system through a low-pressure flash drum, resulting in a lower CO2 capture cost per ton at 99 % CO2 capture rate. The economic analysis suggested that the minimal CO2 capture cost decreased from 44.89 to 42.56 USD/CO2 ton as the capture rate increased. Furthermore, DNN models could predict the CAPEX and OPEX under higher than 98 % accuracy. DNN-based optimization with a multi-variable mutation of features revealed the optimum operating conditions for a minimum CO2 capture cost (42.44 USD/CO2 ton) over a short computational time (12 s). Thus, this study provides insights on the blended solvent and guidelines for a high-pressure CO2 absorption process with a solvent looping system for cost-effective blue H2 production.