The Simulation And Optimization Of CO₂Removal System And Power Generation System In Coal-fired Power Plant

The carbon dioxide emission by coal fired power plant and the global climatechanging has been paid highly attention.The frequent occurrence of haze and theincrease of particulates in the air has been extremely threaten human’s survival andhealth. Countries around the world have realized the environmental deteriorationreduced by industrial development, Low-carbon revolution has been performed toimprove the efficiency of energy utilization and reduce the waste emissions. In China,the main source of carbon dioxide’s emission is power plant, construction, chemicalengineering and transportation etc., thermal power station accounts for nearly50percent in national CO2emissions. It is an important way to solve the environmentalproblem and climate issues by promoting the technological research of carbon capturefor the coal fired power plant.Method of chemical absorption for CO2capture of coal-fired flue gas has beenmature, among which the amine absorption was studied and used widely because ofits fast absorption rate and high absorption efficiency. CO2capture system forcoal-fired power plant is simulated by Aspen Plus, among which themonoethanolamine (MEA) has been chosen as absorbent. The simulation of absorberand stripper is using rate-based model, which is nearly to the practical value. Propertymethod is Aspen Plus’s included data package kemea, in which the ELECNRTL isfor electrolyte simulation. In order to make full use of waste heat and reduce publicengineering consumptions, the traditional CO2removal process has been modified.Then the modified system has been optimized by NSGA-II algorithm through datatransfer platform between Matlab and Aspen Plus. The optimal pareto front curve ofthe maximize CO2capture rate and the minimize reboiler duty is obtained. At last, theoptimal compromise solution is achieved, with which the weight coefficients of twoobjectives based on fuzzy set theory are one. The lean solution load is0.323, leansolution flow rate is209.095t/h, CO2capture rate is91.45%, and reboiler duty is709.49MW. Based on reference data, power generation system model of600MWpower plant is built, and the heat integration of power generation system combined with CO2removal system is developed. The end of medium pressure turbine ischosen as extraction point for stripper’s reboiler. Without considering the CO2compression work and fluid transport power consumption, the net power generationof coal-fired power plant with CO2removal system decreases20%～40%.As thesame above, the optimal pareto front curve of the maximize CO2capture rate and themaximize net power generation of per ton CO2is obtained, the optimal compromisesolution are as follows: The lean solution load is0.2，lean solution flow rate is209.951t/h，extraction flow rate is557.046t/h，net power generation of per ton CO26.33kW/t﹒h，CO2capture rate is92.4%，reboiler duty is701.15MW.The research achievement will provide a useful theoretical basis for the designand parameter optimization of the CO2Capture system, and provide a theoreticalreference for reducing the efficiency and power output penalty of the coal fired powerplant associated with CO2capture process.