Dynamic Modelling, Simulation and Comparison of Large Scale
Carbon Dioxide Capture in Coal Fired Power Plant using Various Amine Solvents

Abstract

Chemical absorption in post combustion capture of carbon dioxide (CO2) is the most feasible and economical technology to capture CO2. In the present work, the efficacy of CO2 capturing were studied for three different amine solvents-monoethanolamine (MEA), a mixed solvent composed of methyldiethanolamine (MDEA) and piperazine (PZ), called activated MDEA (a-MDEA) and aqueous ammonia (NH3) solution. In the first part of this study, an Aspen Plus simulation model was developed and in the second part, the simulation model was used to carry out sensitivity analyses. The different key parameters for different solvents were also determined and analysed in the present study. For MEA, the key parameters were the effects of type of packing, solvent temperature and absorber height on the reboiler duty. Activated-MDEA has two key process parameters which are variation of PZ concentration in the mixed solvent and the solvent to feed ratio with the CO2 recovery and energy consumption in the reboiler of the stripper. Finally, a complete state-of-art study was done for aqueous NH3 solution on several key parameters like NH3 concentration, CO2 loading, absorber height, temperature of absorber and stripper, flow rate of lean and rich solvent, boilup ratio, condenser temperature, regeneration energy and the reboiler duty. In the final part of the study, an overall comparison is done between the three solvents by taking cost economics into consideration and thus recommending the best solvent for CO2 capturing in Post Combustion Capture using chemical absorption. Energy consumption is the major challenge for this process. Paralleling more columns or capturing a part of the overall flue gas can reduce the energy consumption.