Simulation Of CO₂ Capture System For Coal-fired Power Plants

As the development of mankind economy, the demand of energy supply expanded. A large amount of carbon dioxide emited to atmosphere from combustion of fossil fuels causes severe environment damage and greenhouse effect. The emission of greenhouse gases induces greenhouse effect among which CO2 is typical. The amount of CO2 emission from fossil fuels accounts for 80 percent of all the emission caused by human activity, and the amount of CO2 from power plants is 30 percent. So the removal of CO2 from flue gas of power plants is the sticking point on greenhouse effect mitigation.Method of chemical absorption is using most widely process because of its mature and availability. Among the methods, the amine absorption has good qualities of faster absorption rate, higher efficiency and so on, so it has been studied and made a rapid progress in these years. According to the less presstrue CO2 in coal-fired flue gas, the monoethanolamine (MEA) absorption of CO2 from coal-derived flue gases on the scale proposed above is technologically feasible. But MEA absorption is an energy intensive process and especially requires large quantities of low-pressure steam.In order to reduce the CO2 capture system operation cost, we use the theories of process systems engineering in the simulation and study on how to reduce the energy requirement for solvent regeneration was provided. A CO2 removal process for post-combustion CO2 capture from a 500 MW coal-fired power plant, based on absorption/desorption process with MEA solutions, was described. Then a process simulation model had been developed by using Aspen Plus with the RateFrac unit operation module for the absorber and stripper.According to the physical properties of the carbon dioxide removal system, the proper thermodynamic property calculation method (ELECNRTL) and the thermodynamic equation (NRTL) are chosen, the method of decomposing the flow sheet is adopted, to the system simulation and calculation on the steady state process simulation software Aspen Plus.To achieve the requirement of carbon dioxide removal system, this simulation and optimization aimed to reduce the energy consumed, by investigating the effects of the number of absorber trays, the number of stripper strays, lean MEA loading. The sensitivity analysis and design regulation function in the Aspen Plus software has been used to determine the optimizing parameters of the carbon dioxide removal system. The detailed process parameters of this system, the fundamental for the design and the production, are get hold of. An advanced amine CO2 removal system was put forward. The reduced recovery rates can be achieved by two methods which respectively are achieved by treating only part of the flue gas stream in the absorber and bypassing the remainder of the flue gas stream directly to the stack. The bypassing method allows the energy requirement of amine regeneration system to be smaller and less.This system model is applicabled to the basic study and to steady performance study for the system of CO2 absorbed by MEA, and can provide an academic reference for the design,operation,technics,and parameter optimization study for the system of absorber and stripper. It is testified that what we did have theory and applied price.