Abstract:

Based on the analysis of experimental phenomena of particles clustering in the gas-solid system, taking the catalytic cracking reactions of vacuum gas oil for example, the flow, heat transfer and the cracking reactions occurred on the spherical and ellipsoidal particles clusters were simulated. The distribution of gas velocity, temperature and species concentration as well as the reaction rate inside and outside the particles clusters were obtained. The simulated results showed that the particles clustering hinders the sufficient contact of oil gas and catalyst particles, thus leading to the non-uniform distribution of velocity and temperature, and affecting the catalytic cracking reactions. The rates of primary reactions on cluster particles are greatly lower than those on the isolated single particle, and the formation of cluster affects the reaction time notably, which results in a higher yield of light gas and coke, which is undesirable in the industry production.

Key words: catalytic cracking, particle cluster, reaction, numerical simulation, numerical analysis

摘要：

在对气固流动体系颗粒聚团实验现象分析的基础上,以减压馏分油裂化反应为例,对反应器中最常见的球形和椭球形聚团上的流动、传热和反应过程进行了模拟计算,得到了聚团内外油气和催化剂颗粒的速度分布、温度分布、浓度分布以及反应速率分布。研究结果表明,催化剂颗粒聚团的存在阻碍了油气与催化剂颗粒的充分接触,进而造成系统内速度和温度的不均匀分布,影响了裂化反应的发生,使得有颗粒聚团时的一次反应速率明显低于无聚团时的反应速率,颗粒聚团显著影响了油气在颗粒上的反应时间,最终导致气体和焦炭产率升高,对裂化反应产品收率分布十分不利。

关键词: 催化裂化, 颗粒聚团, 反应, 数值模拟, 数值分析