直馏柴油预处理及其蒸汽裂解性能优化研究

STUDY ON PRETREATMENT OF STRAIGHT-RUN DIESEL AND ITS STEAM CRACKING PERFORMANCE OPTIMIZATION

针对柴油需求量下降、柴油产品出厂困难的现状,结合炼化一体化装置优势,利用加氢精制、单段加氢裂化(SSOT)和吸附脱芳烃3种工艺进行柴油预处理,并利用评价试验装置完成3种预处理产品的裂解性能评价,同时考察产品的结焦性能。结果表明:与直馏柴油相比,经SSOT和吸附脱芳烃工艺预处理后的柴油产品的裂解性能明显提升,可作为蒸汽裂解原料;与SSOT工艺相比,吸附脱芳烃工艺具有更高的芳烃脱除率,所得低芳烃含量馏分(低芳馏分)裂解时的目标烯烃收率明显提升,结焦量明显降低。利用试验装置进行吸附脱芳烃所得低芳馏分裂解的裂解炉出口温度(COT)优化,并开展结焦性能优化试验的结果显示,以吸附脱芳烃所得低芳馏分作为蒸汽裂解原料时,推荐的COT为830℃,推荐的硫化物加入量(w)为200~300μg/g。

In view of the current situation of the decreasing demand for diesel and the difficulty of diesel products leaving the factory,combined with the advantages of integrated refining and chemical unit,three processes,hydrofining,single-stage hydrocracking(SSOT)and adsorption dearomatization,were used to carry out the diesel pretreatment.The pyrolysis performance of three pretreated products was evaluated by the test equipment,and the coking performance of the products was also investigated.The results showed that the pyrolysis performance of diesel pretreated by SSOT and adsorption dearomatization process was significantly improved,which could be used as steam cracking feedstock,and adsorption dearomatization process had higher aromatics removal rate than the SSOT process.The yield of target olefin of the low aromatics fraction was significantly increased,while the yield of coke was remarkablely decreased.Optimization of pyrolysis furnace outlet temperature(COT)of low aromatics fraction after adsorption dearomatization pretreatment was carried out on a test set.The results of coking performance optimization test showed that,when the adsorption dearomatization low aromatic fraction was used as steam cracking raw material,the recommended COT was 830℃,and the recommended sulfide addition content was 200-300μg/g.