Study of CO2 capture process using aqueous ammonia

Abstract

Carbon dioxide (CO₂) emissions to the atmosphere have become an issue for many industries, especially coal-fired power plants, due to their contribution to global warming. Many research projects are presently involved the development of effective solvents to combat these severe environmental problems. Aqueous ammonia is a solvent that has been Proposed as a replacement to conventional aqueous monoethanolamine (MEA) in post-combustion CO₂ capture. In this study, an aqueous ammonia based CO₂ capture process was simulated by Aspen Plus simulator for capturing about 90% by weight of CO₂ with a purity of 98% by weight from a post-combustion flue gas based on a 180 MWe coal-fired power plant. The simulation of this process was performed to meet the ammonia emission standard. An ammonia-based simulation process consist of two parts: the CO₂ absorption process and the ammonia abatement process. To minimize the energy consumption of the process, heat integration was applied by adding a Heat Exchanger Network (HEN). HEN was besigned using stage-wise model (Yee and Grossmann, 1990) and validated using the Aspen Plus simulator. Furthermore, capital investment and annual costs were investigated using Aspen Plus Cost Estimator, and some economic parameters (Hassan et al., 2007) to assess the feasibility of this process based on standard environmental regulations. The results showed that the performance of actual aqueous ammonia plants using process integration reduced the energy requirement from a “non-integrated process by 58% on the heaters, coolers and electrical units resulting in a theoretical decrease of 47% in the annual cost of utilities, compared to the cost without process heat integration.