Study of the Desorption Process of Post-Combustion CO2 Capture for Coal and Combined-Cycle Thermal Power Plants

Post-combustion CO2 capture is one alternative that allows thermoelectric power plants to continue generating electricity while reducing greenhouse gas emissions. Most reported pilot plants operate with a 30% wt. MEA solution and superheated steam to regenerate it. However, the development of post-combustion CO2 capture requires experimental studies with MEA dilutions below 30% wt. MEA to analyze new regeneration absorption concentrations. The laboratory-scale post-combustion CO2 capture process is described, with a focus on the study of the desorption process. The absorbent solutions are saturated in the packed absorption column prior to desorption tests. The samples are desorbed in the packed desorption column, controlling and monitoring the process variables. The results of this work show that the technology can operate with dilute MEA solutions (10, 15, 20, 25, and 30% wt. MEA) absorbing CO2 from a gas mixture at 12.5% vol., representing a typical CO2 concentration emitted by coal-fired power plants, and at 3 and 5% vol., representing the typical CO2 concentration range emitted by combined-cycle power plants. Furthermore, it is demonstrated that the MEA solution can be regenerated using saturated steam (94 °C and 0.8 atm). The concentrations of the regenerated solutions were evaluated by measuring the refractive indices, and the regeneration was validated with experimental absorption tests.