MODELLING OF CO2 ABSORPTION WITH VARIOUS SOLVENTS

Abstract

Global concentration of CO2 in the atmosphere is increasing rapidly, which have an impact on global climate change. To control the CO2 emission in the environment, the effective CO2 emission abatement strategies such as Carbon Capture and Storage (CCS) are required. The most promising technology for carbon dioxide capture from coal and natural gas fired power plants . at large scale applications is based on post-combustion method using gas—liquid absorption. In the present work a commercial process modelling tool ASPEN Plus is used to analyse the CO2 absorption in monoethanolamine-triethylene glycol (MEA-TEG) system. The Electrolyte Non-Random Two-Liquid Activity (ENRTL) Coefficient model was used to develop a rigorous and consistent thermodynamic representation for the component systems associated with aqueous combinations of MEA-TEG for CO2 absorption and stripping from natural gas treating unit and coal fired power plants. The work focuses on the MEA-TEG system without water as an absorbent of CO2 with low energy consumption. The solubility of CO2 in TEG and MEA-TEG solutions is determined for 0.5M, 0.3M and 0.1M (the mass fraction of MEA is 28%). The solubility data for CO2 in pure TEG and MEA-TEG solutions is taken from the literature (Tan et al., 2011). The chemical reaction absorption characteristic is observed from the fact that the solubility of CO2 in MEA-TEG solutions significantly increases with the increase in MEA concentration. From the present work it has been observed that with the MEA-TEG system the absorption and desorption can be realized at relatively lower temperatures (lower than 353.15 K). Thfs may results into low energy consumption with less solvent evaporation and avoidance of MEA's degradation due to high-temperature operation.