Zhang Jin H, Wang Zhen B, Zhao Hui, Tian Yuan Y, Shan Hong H, Yang Chao H
State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, 266580 China.
Appl Petrochem Res. 2015;5(4):255-261. doi: 10.1007/s13203-015-0130-1. Epub 2015 Aug 15.
Fixed fluidized bed reactor is widely used to evaluate the crackability of heavy oils and the activity of catalysts. To understand the hydrodynamics, reaction kinetics and thermodynamics in conventional and modified fixed fluidized bed reactors, the computational fluid dynamics method, energy-minimization multi-scale-based two-fluid model coupled with a six-lump kinetic model was used to investigate the gas-solid flow and cracking reactions. The gas mixing and particle volume fraction distributions, as well as product yields in the conventional and modified fixed fluidized bed reactors were analyzed. The residence time distribution model was utilized to obtain the parameters indicating the back-mixing degree, such as mean residence time and dimensionless variance of the gas. The results showed that the simulated product distribution is in reasonable agreement with the experimental data; the modified fixed fluidized bed reactor is closer to the ideal plug flow reactor, which can efficiently enhance the gas-solid mixing, reduce the gas back-mixing degree, and hence improve the reaction performance.
固定流化床反应器被广泛用于评估重油的裂化性能和催化剂的活性。为了理解常规和改进型固定流化床反应器中的流体动力学、反应动力学和热力学，采用计算流体动力学方法，基于能量最小化多尺度的双流体模型结合六集总动力学模型来研究气固流动和裂化反应。分析了常规和改进型固定流化床反应器中的气体混合、颗粒体积分数分布以及产物产率。利用停留时间分布模型获得了表示返混程度的参数，如气体的平均停留时间和无量纲方差。结果表明，模拟的产物分布与实验数据合理吻合；改进型固定流化床反应器更接近理想的平推流反应器，能够有效增强气固混合，降低气体返混程度，从而提高反应性能。
