Experiments Study On The Removal Of CO₂ From Flue Gas Of Power Plants Via Membrane Absorption And Chemical Absorption

It's well known that greenhouse effect is the great environment problem that mankind confronts. 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.Chemical absorption, adsorption, cryogenic distillation, membrane separation and membrane-based absorption are the main technologies to separation CO₂ from flue gas. Investigation from International Energy Agency and British Investigation and Development Association on greenhouse gases indicates that membrane-based gas absorption and chemical absorption are the most promising separation technologies. Founded by National High Technology Research and Progress Projects, this thesis studies membrane-based separation and chemical absorption.In this paper, several technologies are introduced including chemical absorption, adsorption, cryogenic distillation, membrane separation and membrane-based absorption, and techno-economical analysis is studied on the above technologies.Several factors (species, concentration and temperature of absorbents, velocity of flue gas and liquids, concentration of flue gas) of the craft flow in which flue gas flowed out of the hollow membrane with the relationship of mass transfer and removal rates are obtained. It is found that species of absorbents has great influence upon the mass transfer velocity and the removal rates. As the liquid velocity increases, the mass transfer and the removal rate increases. As the gas velocity and concentration of CO₂ increase, the mass transfer increases, but the removal rate decreases. 2.0mol.L^-1 is the appropriate concentration and 40℃ is the proper temperature.Influence of absorbents ingredients and liquid velocity on CO₂ removal rate in the flow chat of flue gas flowing out of the hollow fiber membrane ( I) are investigated on the simple device for the CO₂ removal taking pure and blend absorbents as absorbents. The experiments indicate that the flow chat of flue gas flowing in the membrane lumen (II) is better than I from the point of view of mass transfer. Putting little amino acetic acid potassium(AAAP) or mono-ethanol-amine (MEA) in methyl-diethanol-amine greatly increases the CO₂ removal rate. Micro-pores of the membrane tend to be wetted easily by the mixture of above absorbents.The absorption (desorption) character of blend absorbents with different species and different ingredients are studied. The results show that keeping absorbents boiling over is necessary for desorption. AAAP and MDEA are promising in the industry apply.The CO₂ removal of flue gas by chemical absorption is studied in the packed tower, mass transfer (volume) coefficient and mass transfer velocity of the three flow chats mentioned abovewere studied. It is found that the mass transfer resistance of chemical absorption is least, volume mass transfer of II is maximal, and volume mass transfer of I is lowest.The research can form a connecting link between the preceding and the following, and the results will be of significance for CO2 pollution control.