Experimental Research On Waste Heat Recovery And CO₂ Capture Of Coal-fired Power Plants Based On Ionic Liquid

Climate change is already an important factor affecting global social progress and economic growth.In the early stage of development,China has formulated the basic national policy of energy conservation and emission reduction to deal with this problem.There are also many problems facing the active development of renewable energy.Therefore,it is necessary to find a new way to store and produce energy.As a material with great potential,ionic liquid is widely used in the fields of chemical industry,battery,biomass and so on.Ionic liquids have advantages over traditional solvents,such as wide liquid range,better physical and chemical stability,low vapour pressure and adjustability of anion,cations or structures.In a traditional coal-fired power plant,because of its own low thermal efficiency,resulting in a high smoke emission temperature with a high heat loss.In addition,flue gas contains CO₂needs to be absorbed before emissions.Based on the background of coal-fired power plants,a system of fume residual heat recovery and CO₂capture is designed and constructed by using ionic liquid as a medium for heat conduction,heat storage and CO₂capture.Under laboratory conditions,different ionic liquids are selected for practical testing,the circulatory and stability of are explored,and the experimental basis is provided for the thermal storage of ionic liquids.（1）The experimental system is mainly divided into a heat conduction,heat storage part and a CO₂capture part.The simulated flue gas mixed gas path and the ionic liquid circulation path constitute the heat conduction,heat storage part.Considering the recycling of ionic liquids in the system design,indirect heat exchange is adopted.During the construction of the system,continuous improvements were made to simulate the heating method of the flue gas,the flow rate control of the ionic liquid,the acquisition of experimental parameters,and the insulation and connection of the pipes.The operation process of the system was determined in detail to ensure the normal operation of experiment.（2）In the experimental system,the ionic liquids（[Omim][PF₆],[Omim][BF₄],[Omim][NTf₂]）were used to cycle 20 times under the conditions of setting the simulated flue gas mixture temperature to 110℃,115℃,120℃,125℃,130℃.The experimental results show that the ionic liquid reduces the temperature of the simulated flue gas to about 20℃and calculates the heat exchange rate of both,up to 41.9%.The samples taken were sampled by TG and FT-IR,the results showed that the ionic liquid kept good thermal and chemical stability in the cycle.（3）The CO₂ capture experiment was carried out on the basis of three types of ionic liquids with large molecular volumes([P₁₄][NTf₂],[bmim][NTf₂],[emim][NTf₂])on the basis of the selection of 3 conditions of the heat exchanger part of the experimental system（simulating the outlet temperature of flue gas at 16.8℃,18.2℃,19.1℃）.The results showed that ionic liquids reached the maximum absorption capacity within 50min and carried out 6cycles.The maximum absorption of CO₂is 0.137g.The sample is also characteristicized,and the results show that the ionic liquid has good circulation and stability.