Optimization of annular distributor for industrial riser reactor with weakened catalyst attrition

Abstract

AbstractCatalyst attrition and nonuniform gas–solid distribution were observed in an oil refining and chemical enterprise with straight pipe as C4 mixture gas feed zone, which induced unfavored catalytic reaction and unqualified products. In this work, a fluidized attrition experiment circulating system consisting of a riser reactor at a bench scale was constructed to implement fluidized attrition experiment. Four annular pipe distributors were designed as C4 mixture gas feed zones and compared with traditional straight pipe in order to gain insight into the catalyst attrition condition in the riser reactor. At the same time, computational fluid dynamic technique was applied to investigate the gas–solid mixing situation in the riser reactor with five different C4 mixture gas feed zones. Structure four of annular distributor with nine nozzles distributed as well as an inclination of 30° displayed a catalyst attrition of 5.7% in 12 h of fluidized circulation and possessed the best gas–solid mixing condition as well as the highest catalyst volume fraction distribution in the main catalyst reaction space. Therefore, structure four was selected as C4 mixture gas feed zone for industrial riser reactor. Flow behavior in the industrial riser reactor with the optimized C4 annular distributor was further investigated via numerical simulation and compared with traditional straight pipe as C4 mixture gas feed zone so as to provide reference for the optimization of industrial riser reactor. When annular distributor was applied, propylene yield enhanced to 19.86%, and meanwhile, enhancement of catalyst particle with size smaller than 40 μm obviously decreased in comparison with traditional riser reactor.