燃煤烟气中SO2对氨法脱碳的影响

Impact of SO_2 on CO_2 capture in coal-fired flue gas using aqueous ammonia

利用湿壁塔实验台对燃煤烟气中SO2对氨水溶液[1%～7%(质量)]吸收CO2的影响进行了实验研究,具体分析了不同反应温度(20～80℃)和CO2体积分数(5%～20%)条件下,CO2传质通量及传质系数随SO2浓度和SO2负载量的变化规律。结果表明,SO2浓度由0增至11428mg.m-3,CO2传质通量及传质系数均有一半左右降幅,而SO2负载量[0.1～0.4mol SO2.(mol NH3)-1]的增加,同样导致CO2传质通量及传质系数明显减小。氨水浓度及反应温度增加可有效提高CO2传质通量和传质系数,相对降低SO2对CO2传质的影响。CO2浓度的增加可明显提高其传质通量,但是CO2的传质系数有所降低。

Aqueous ammonia has potential to capture the large amounts of SO2 and CO2 in coal-fired flue gas.The study in this area,however,is very limited.The reaction of SO2 with aqueous ammonia is much faster than that of CO2,so SO2 in the flue gas may have impact on capture of CO2.A series of experimental tests were conducted in a wetted wall column system,and the impact of SO2 concentration and SO2 loading on CO2 flux and coefficient of mass transfer using aqueous ammonia[1%—7%（mass）]was analyzed at various absorption temperatures（20—80℃）and CO2 concentrations[5%—20%（vol）].The results show that when SO2 concentration increases from 0 to 11428 mg·m-3,CO2 mass transfer flux and coefficient decrease to one half of the original values.When SO2 loading[0.1—0.4 mol SO2·（mol NH3）-1]increases,CO2 mass transfer flux and coefficient also have significant reduction.Higher ammonia concentration and absorption temperature can effectively improve CO2 mass transfer flux and coefficient,and relatively reduce the impact of SO2 on CO2 mass transfer.CO2 mass transfer flux increases when its concentration increases,and its mass transfer coefficient decreases.