Research On Design Of Post-combusiton CO₂ Capture System And Its Integration With Power Plant System

With the growing global warming, CO2 mitigation has become the international research focus. In China, coal-fired power plants are the largest CO2 emission source which occupies nearly half of the total CO2 emissions. Thus, it's very important for mitigating CO2 from coal-fired power plants.The most promising near-term strategy for mitigating CO2 emissions is the post-combustion capture of CO2, especially the method of chemical absorption is used widely because of its mature and availability. According to the characteritics of coal-fired power plant flue gas with the less CO2 partial pressure, extensive researches suggest that the monoethanolamine(MEA) absorption of CO2 from coal-derived flue gases is technologically feasible and could be a reasonable choice. But MEA absorption is also an energy and capital investment intensive process which has always been an obstruction for its wide application in coal-fired power plant on a large-scale.In this paper, the CO2 capture system based on MEA has been simulated with the help of ASPEN PLUS software. The effects of the key parameters on the absorption and regeneration processes were studied and the relationship between the parameters and the energy consumption of amine regeneration has been investigated. The increase of the stripper operating pressure and rich solvent temperature are be favorable to reducing reboiler duty. The thermal energy requirement decreases with the increase of lean solvent loading until a minimum is reached. The point at which the energy requirement is lowest will be defined as the optimum lean solvent loading. For 85% CO2 removal rate and a 30 wt.% MEA solution the optimum lean solvent loading was around 0.2-0.3mol CO2/mol MEA, with a thermal energy requirement of 2.83 GJ/ton CO2.Based on the operational data of a certain power plant, the steam cycle system model of a 600MW power plant and the integration mode of CO2 capture system with the power plant are developed. This paper proposes two different integration schemes and provides the detailed integration method including a set of modifications of a supercritical steam cycle to overcome the energy requirements through energetic integration, also the effect of CO2 mitigation on the efficiency and power output penalty is analyzed. Results show that the efficiency penalty is around 6-8 percent point.The research achievement from this paper will provide a useful reference for the design and parameter optimization study for the CO2 capture system, and proposes two integration solutions with the aim of reducing the efficiency and power output penalty associated with CO2 capture process.