Khongprom Parinya, Ratchasombat Supawadee, Wanchan Waritnan, Bumphenkiattikul Panut, Limtrakul Sunun
Department of Industrial Chemistry, Faculty of Applied Science, King Mongkut's University of Technology North Bangkok Bangsue Bangkok 10800 Thailand
Integrated Nanoscience Research Center, Science and Technology Research Institute, King Mongkut's University of Technology North Bangkok Bangsue Bangkok 10800 Thailand.
RSC Adv. 2020 Jan 16;10(5):2897-2914. doi: 10.1039/c9ra10080f. eCollection 2020 Jan 14.
Circulating fluidized bed downer reactors (downer reactors) exhibit good heat and mass transfer, and the flow behavior approaches the ideal plug flow. This reactor is superior for catalytic cracking reactions in which the intermediate is the desired product. However, the hydrodynamic behavior and reactor performance have mostly been investigated in small-scale or laboratory-scale reactors. The objective of this study was to investigate the up-scaling of the catalytic cracking of heavy oil in three downer reactors with heights of 5, 15, and 30 m, using computational fluid dynamics simulations. A two-fluid model with the kinetic theory of granular flow was used to predict the hydrodynamics and performance of the chemical reactions. The kinetics of catalytic cracking of heavy oil were described by a 4-lump kinetic model. The chemical performance similarity was identified by using radial and axial distributions of heavy oil conversion, gasoline mass fraction, and gasoline selectivity. The chemical performance similarity cannot be achieved by using the hydrodynamic similarity parameter . A modified up-scaling parameter was proposed, . The chemical performance similarity of identical catalytic cracking downer reactors can be achieved with deviation in the range of ±10% and mean relative absolute error of less than 5%.
循环流化床下行式反应器（下行式反应器）具有良好的传热和传质性能，其流动行为接近理想的活塞流。这种反应器对于中间产物为目标产物的催化裂化反应具有优势。然而，其流体动力学行为和反应器性能大多是在小规模或实验室规模的反应器中进行研究的。本研究的目的是通过计算流体动力学模拟，研究在高度分别为5米、15米和30米的三个下行式反应器中重油催化裂化的放大问题。采用带有颗粒流动力学理论的双流体模型来预测流体动力学和化学反应性能。重油催化裂化动力学由四集总动力学模型描述。通过重油转化率、汽油质量分数和汽油选择性的径向和轴向分布来确定化学性能相似性。使用流体动力学相似参数无法实现化学性能相似性。提出了一个修正的放大参数， 。相同的催化裂化下行式反应器在偏差范围为±10%且平均相对绝对误差小于5%的情况下可以实现化学性能相似性。
