催化裂化烟气脱硫实验研究

Experimental study of FCCU flue gas scrubbing

近年来催化裂化原料油的硫含量不断增加,导致催化剂再生烟气中的二氧化硫含量增加。国外已工业化的催化裂化烟气脱硫技术有Belco公司的LABSORBTM工艺,国内有中石化洛阳工程有限公司的RASOC技术。通过对上述两种方法的分析比较并结合传统钠法,开发一种新的催化裂化装置再生烟气脱硫工艺。通过对亚硫酸钠脱硫废液的处理,回收其中的无水亚硫酸钠,母液循环回脱硫系统再次使用,形成一种回收亚硫酸钠的循环烟气脱硫工艺。在实验室内以小型填料塔为吸收塔,在吸收液初始量浓度为0.3～0.5 mol/L条件下考察吸收剂的pH值、液气比、催化剂颗粒对脱硫率的影响,同时考察了吸收剂的再生情况。结果表明:在吸收剂pH值为6.5～7.0,液气比为2～3 L/m3,吸收液初始量浓度为0.3～0.5 mol/L时脱硫率可达到90%以上。回收的无水亚硫酸钠产品可以达到工业级,再生的吸收剂脱硫率与新鲜液效果相当。

In recent years, the increased sulfur in FCC feedstock has resulted in increased amount of SO2 in flue gas from FCCU regenerator. The commercialized FCCU flue gas scrubbing processes in the world are Beleo＇ s LABSORBTM process and LPEC＇ s RASOC process. Based on the analysis and comparison of above two processes and in consideration of conventional method, a new FCCU flue gas scrubbing process has been developed. In this process, anhydrous sodium sulfite is recovered from the solution which has absorbed SO2 from flue gas. Then the solution recycled back to scrubbing system to absorb SO2 again. Therefore, a recycled regeneration flue gas scrubbing process is formed. In the laboratory, a small packed tower is used as absorption tower to study the impact of pH value of absorbent, liquid to gas ratio and catalyst particle size distribution on the desulfurization efficiency under the conditions of 0.3 - 0.5 mol/L initial concentration of absorption solution. At same time, the condition of absorption solution regeneration is investigated. The results show that the sulfur removal efficiency can reach over 90% when the pH value of absorption solution, liquid to gas ratio and initial concentration of absorption solution are 6.5 - 7.0, 2.0 - 3.0 L/m3 and 0.3 - 0.5 mol/L respectively. The recovered anhydrous sodium sulfite can reach the industrial level, and the desnlfurization rate of regenerated absorption solution is as same as the fresh solution.