Simulation Analysis On CO₂ Capture By MEA Method Based On Heat Pump Technology

With the rapid development of national economy, the total energy consumption is increasing. Meanwhile, the concentration of CO2 in atmosphere is increasing gradually caused by the combustion and emission of fossil fuels, which makes global warming increasingly serious. The coal-fired power plant is the concentrated emission source of CO2, and it is especially important to control CO2 emissions by separating and capturing CO2 from flue gas. As a kind of mature CO2 removal process, the chemical absorption method with MEA (mono-ethanolamine) as sorbent has good application potential. The MEA method has the advantage of fast absorption rate and good removal effect, but the desorption energy consumption and operating cost of it are high. Therefore, in order to reduce capture cost, it has high directive practice sense of science and engineering to do energy saving research on traditional MEA method. In this study, the focus aims at reducing the desorption energy consumption of CO2 capture system by MEA. The main works are summarized as following.The process flow of CO2 capture by MEA was simulated and analyzed by Aspen Plus. Taking the flue gas from some power plant as simulation object, the system model of CO2 capture by MEA was established. The stream parameters of system, temperature distribution of stripper, and factor of reboiler duty were analyzed. Moreover, the value of reboiler duty was obtained, which provided powerful reference for the simulation analysis of other systems on the basis of this process.Based on the energy saving study of CO2 capture by MEA, the CO2 capture system by lean solution source heat pump was introduced. According to the simulation of this system by Aspen plus, the stream parameters of system and temperature distribution of stripper were analyzed. It showed that the temperature distribution of stripper was uniform, which was beneficial to desorb CO2 quickly. The desorption energy consumption of CO2 capture system by lean solution source heat pump was obtained, which showed that the desorption energy consumption saving effect of CO2 capture by lean solution source heat pump was 55.80%.A new type of CO2 capture system by MEA based on solar assisted heat pump technology was put forward on the basis of CO2 capture system by lean solution source heat pump. The solar assisted heat pump technology was applied in the MEA method, and the SLHP system was used to provide all the desorption heat required by the stripper. The desorption energy" consumptions of the the three CO2 capture systems were compared and analyzed theoretically, which showed that the CO2 capture process by SLHP had lower desorption energy consumptions than the CO2 capture process by lean solution source heat pump.The CO2 capture process by SLHP was simulated by Aspen Plus, and the stream parameters of system and temperature distribution of stripper were analyzed. It showed that the temperature distribution of stripper was more uniform, which was beneficial to desorb CO2 more quickly. The desorption energy consumption of system was obtained, which showed that the desorption energy consumption saving effect of CO2 capture by SLHP was 63.80%.The thermal efficiency of power plant, CO2 capture cost and electrovalence after capturing CO2 by the three CO2 capture processes were calculated and analyzed by the thermodynamics and economics analysis models. The results showed that comparing with the basic process of MEA method, the thermal efficiency of power plant had increased by 8.32% and 9.51% respectively after capturing CO2 by lean solution source heat pump and SLHP, and the CO2 capture cost and electrovalence had reduced significantly. Above all, the various performance of CO2 capture system by SLHP was better than that of CO2 capture systyem by lean solution source heat pump.In this study, the three CO2 capture processes were simulated and analyzed by Aspen Plus, and the thermodynamics and economics analysis were conducted. The results showed that the CO2 capture system by SLHP had the minimum desorption energy consumption; the thermal efficiency of power plant was maximum, and the CO2 capture cost and electrovalence were minimum after capturing CO2 by SLHP. Therefore, the CO2 capture system by SLHP had the best energy-saving effect and economic benefit. Based on the full work summary of the thesis, the research direction of following work for the SHLP system of the CO2 capture system by MEA method based on solar assisted heat pump technology was pointed out.