Simulation of Carbon Capture from Flue Gas of a Coal-fired Power Plant by a Three-bed Pressure Swing Adsorption Process

Abstract

In order to reduce carbon dioxide emissions, pressure swing adsorption (PSA) process was studied to capture carbon dioxide from flue gas in a coal-fired power plant. Pressure swing adsorption features its low energy consumption, low investment, and simple operation. This study aims to capture carbon dioxide from flue gas by PSA process for at least 85 % CO2 purity and with the other stream of more than 90 % N2 purity. To validate the accuracy of the PSA simulation program, the extended Langmuir-Freundlich equation was adopted to fit measured equilibrium data to describe the adsorption equilibrium of adsorbent zeolite 13X. Next, the simulation study used the linear driving force model and compared the results of breakthrough curves and desorption curves between experiments and simulation to verify the accuracy of the mass transfer coefficient kLDF value in linear driving force model. The agreement between experimental data and the simulation results is good. Further, the simulation was verified with the 100-hour cyclic-steady-state experiment of the 3-bed 9-step PSA process studied. Flue gas after desulphurisation and water removal (13.5 % CO2, 86.5 % N2) of subcritical 1 kW coal-fired power plant was taken as feed to the designed 3-bed 9-step PSA process. To find the optimal operating conditions, the central composite design (CCD) was used. After analysis, optimal operating conditions were obtained to produce a bottom product at 89.20 % CO2 purity with 88.20 % recovery, and a top product at 98.49 % N2 purity with 93.56 % recovery. The mechanical energy consumption was estimated to be 1.17 – 1.41 GJ/t-CO2.