氨水溶液同时吸收烟气中SO2和CO2的实验及模拟
Simultaneous absorption of SO2 and CO2 from flue gas using aqueous ammonia

燃煤电厂排放大量SO2和CO2等气态污染物，相应的减排技术研究十分必要。利用湿壁塔实验台对氨水溶液（质量分数为0.2%~7%）同时吸收SO2和CO2的传质特性进行了实验研究，并结合Aspen Plus速率模型分析了填料塔的吸收性能，对氨水溶液同时吸收SO2和CO2吸收系统的设计做了必要的探讨。实验结果表明：随着CO2体积分数（5%~20%）的增加，SO2选择性吸收因子有所降低，SO2的传质系数变化较小且均高于CO2的传质速率一个数量级；SO2质量浓度（0~11428 mg/m3）和反应温度（20~80℃）的增加，对CO2的吸收产生不利影响，氨水溶液趋向于选择性吸收SO2。氨水溶液中SO2负载量（SO2在氨水溶液中相对NH3的摩尔浓度）在0.1~0.4之间增加时，CO2的传质系数大幅降低。氨水溶液质量分数增加对CO2及SO2的吸收传质均有利，选择性吸收因子降低，且实验值和模型计算值符合良好。采用同时吸收SO2和CO2的填料吸收塔，结合控制氨挥发的氨洗塔及用于SO2负载控制的离子交换装置的吸收系统，可以实现污染物的有效脱除。
Abstract：Coal-fired power plants emit large quantities of SO2 and CO2, so more research is needed on SO2 and CO2 capture. Experimental tests were conducted in a wetted wall column system to analyze the simultaneous absorption of SO2 and CO2 using aqueous ammonia (weight percent, 0.2%-7%). The Aspen Plus RateSep model was then used to analyze the CO2 and SO2 mass transfer in the packed column to comprise the design of the ammonia based CO2 and SO2 absorption system. The experiments show that the SO2 selectivity absorption factor decreases as the CO2 volume concentration increases. The CO2 volume concentration (5%-20%) has little effect on the SO2 mass transfer and the SO2 absorption rate is always an order of magnitude higher than that of CO2. Increasing the SO2 mass concentration and reaction temperature has a negative effect on the CO2 absorption and the ammonia tends to selectively absorb the SO2. When the SO2 loading (mole concentration ratio between SO2 and NH3 in the aqueous ammonia solvent) increases from 0.1 to 0.4, the CO2 mass transfer rate significantly decreases. Increasing the ammonia mass concentration improves the absorption of both CO2 and SO2 and the predicted results are in good agreement with the experimental data. Thus, the packed column combined with an ammonia scrubber to reduce the ammonia slip and a resin exchange device used to control the SO2 loading can achieve simultaneous removal of CO2 and SO2.