基于循环流化床灰渣余热利用的烟气CO_(2)吸附系统模拟

Simulation of flue gas CO_(2)adsorption system based on CFB ash waste heat utilization

利用CFB(循环流化床)高温灰渣吸收烟气中的CO_(2)有利于灰渣余热利用与电厂碳减排。采用CPFD(计算颗粒流体力学)方法对基于CFB灰渣余热利用的烟气CO_(2)吸附系统进行模拟研究,考察烟气流速、隔墙高度、隔墙位置、颗粒粒径对吸附系统的影响。结果表明:灰渣吸附性能在固定床状态随烟气流速的增加而提高,在鼓泡床状态则降低,反应器出口烟温、两仓室床温与排渣口渣温均随流速的提高而降低;加大隔墙高度有利于提高灰渣吸附性能,但不宜过高;反应器出口烟温随隔墙高度的提高而升高,两仓室床温与排渣口渣温随隔墙高度的提高而降低;隔墙位置靠近排渣口时有利于灰渣吸附CO_(2);吸附性能随灰渣粒径的减小而提高,但粒径过小不利于CO_(2)的吸附。此模拟可为电厂烟气CO_(2)吸附系统设计提供一些理论支撑。

The use of CFB(circulating fluidized bed)high temperature ash to absorb CO_(2)from flue gas is conducive to the utilization of ash waste heat and carbon reduction in power plants.A CO_(2)adsorption system based on CFB ash waste heat utilization was simulated by CPFD(computational particle fluid dynamics).The effects of flue gas flow rate,partition height,partition position and particle size on the adsorption system were investigated.The results show that the adsorption properties of bottom ash increase with the increase of flue gas flow rate in the fixed bed state,but decrease in the bubble bed state,and the flue gas temperature at the reactor outlet,the bed temperature of two chambers and the slag temperature at the discharge outlet all decrease with the increase of flue gas flow rate.Increasing the height of partition is conducive to improving the adsorption performance of ash,but it should not be too high.The flue gas temperature at the reactor outlet increases with the increase of the height of partition,and the bed temperature and the slag temperature at the discharge outlet decrease with the increase of the height of partition.The location of partition near the slag discharge port is conducive to the adsorption of CO_(2)by the bottom ash.The adsorption performance increases with the decrease of ash particle size,but too small particle size is not conducive to CO_(2)adsorption.The simulation can provide some theoretical support for the design of CO_(2)adsorption system from flue gas in power plant.