Na_2S溶液吸收低浓度SO_2的控制步骤分析

Analysis of controlling steps study on absorption dilute gases of sulfur dioxide by sodium sulfide solution

在一个半连续式反应器中采用硫化钠溶液吸收低浓度的SO2 气体 ,随着SO2 吸收量的增加 ,吸收液中pH值的变化出现两次突降 ,表现为三阶段模式。pH值第二次突降后的第三阶段吸收液失去完全吸收SO2 的能力。SO2 吸收的增强因子的变化范围为 :2 2 9+6 9× 10 -10 C-2H+ i+1 1× 10 -2 C-1H+i- (6 9×10 -10 C-2H+l+1 1× 10 -2 C-1H +l)CSO2 lCSO2 i< <2 2 9+6 9× 10 -10 C-2H+i+1 1× 10 -2 C-1H+l,结合Gianni根据增强因子大小判断气体吸收的传质阻力控制步骤的分析 ,得出在本研究体系中 ,当吸收液pH >3 4 6时硫化钠溶液吸收低浓度的SO2 气体的过程为气侧传质阻力控制。这一结论正好与实验相符。

Sodium sulfide aqueous solution is used to remove SO 2-containing dilute gas in a semi-continuous batch reactor.With the increase of the amount of absorbed SO 2,there are two sudden marked drops in the pH value and three stages in the process in accordance to the profile of pH value change.Sulfur dioxide has been fully absorbed in the first two stages.In stage Ⅲ the solution has not the ability of full absorption of sulfur dioxide.The change range of increase factor  of absorption sulfur dioxide is 2.29+6.9×10 -10C -2 H +i+1.1×10 -2C -1 H +i-(6.9×10 -10C -2 H +l+1.1×10 -2C -1 H +l)C SO 2lC SO 2i<<2.29+6.9×10 -10C -2 H +i+1.1×10 -2C -1 H +l In addition,in the light of Gianni′ theory about the judgment of controlling step according to increase factor,when pH>3.46,the gas film mass transfer controlling step is observed for the absorption of sulfur dioxide,as is in line with experiment effects.