硫酸溶液中二氧化硫的臭氧化过程影响因素的研究

Characterization of sulfur dioxide ozonation in sulphuric acid solution

为了优化SO2液相氧化产硫酸过程中的试验操作条件,研究了在O3氧化SO2的过程中反应器进口气体中SO2浓度、O3浓度及臭氧化氧气流量对SO2氧化效果的影响规律。结果表明,在反应器进口气体中低浓度的SO2和高浓度的O3均利于溶液中SO2的氧化,液相氧化时反应器进口气体中SO2的体积比控制在20 000 mL/m3以内为宜。溶液ORP是考察O3氧化SO2的重要指标,溶液ORP降低较快时硫酸根产率较高,表明O3对SO2的氧化效果较好。臭氧化氧气流量增大并不能使硫酸根产率增加。在吸收液硫酸质量分数为3%,气相SO2体积比为6667mL/m3,臭氧化氧气体积流量为1.5 L/min,氮气体积流量为1.5 L/min时,硫酸根产率达到100%。同时,通过研究吸收液硫酸浓度与温度对溶液中的O3饱和浓度影响,得到在稀硫酸(质量分数小于10%)溶液中,O3达到饱和时质量分数较浓硫酸(质量分数大于等于10%)溶液中O3质量分数高,而且吸收液温度越低越利于O3溶解。

In order to optimize the operating conditions of the liquid-phase oxidation process of sulfur dioxide into sulphuric acid, the effect of various parameters including the concentration of gas-phase sulfur dioxide in the reactor inlet, oxygen flow from ozone generator and the concentration of ozone in the inlet, on the oxidation of sulfur dioxide in the solution have been systematically explored in a glass bubbling reactor. The results showed that both lower concentration of gas-phase sulfur dioxide and higher concentration of ozone in the inlet are beneficial for the oxidation of sulfur dioxide in the solution. In addition, the concentration of sulfur dioxide was better to be controlled within 2 000 mL/m3 in the liquid-phase oxidation of sulfur dioxide. The oxidation reduction potential （ORP） of the solution is an important parameter which affects the oxidation of sulfur dioxide by ozone. The faster decrease of ORP in the solution and higher yield of sulfate ions are key identifiers of good oxidation process. The increasing oxygen flow from ozone generator could not promote the oxidation of sulfur dioxide. The sulfate ion yield was up to 100% at sulphuric acid solution of 3% （mass concentration）, gas-phase sulfur dioxide concentration of 6 667 mL/m3, oxygen flow from ozone generator of 1.5 L/min and nitrogen flow of 1.5 L/min. Meanwhile, the influence of concentration of sulphuric acid as the absorbing medium as well as temperature on the saturated concentration of ozone in sulphuric acid solution were investigated. It showed that saturated concentration of ozone was higher in dilute sulphuric acid solution （mass concentration of sulphuric acid less than 10%） than that in concentrated sulphuric acid solution, and low temperature of absorption liquid sulphuric acid was favorable for the dissolution of ozone.