Khongprom Parinya, Ratchasombat Supawadee, Wanchan Waritnan, Bumphenkiattikul Panut, Limtrakul Sunun
Department of Chemical Engineering, Faculty of Engineering, Prince of Songkla University Songkhla 90110 Thailand
Air Pollution and Health Effect Research Center, Prince of Songkla University Songkhla 90110 Thailand.
RSC Adv. 2022 Aug 2;12(33):21394-21405. doi: 10.1039/d2ra03448d. eCollection 2022 Jul 21.
The practical realization of the scaling up of gas-solid multiphase flow reactors with chemical reactions is hindered by chaotic flow behaviors and complex heat and mass transfers in the reactor. In addition, a law to scale up complex reaction mechanisms in multiphase flow systems has been rarely proposed in the existing literature. Thus, this study aims to investigate the scaling up of the catalytic cracking fluidized bed downer reactor based on the similitude method of chemical reaction performance. Three downer reactor scales with a height of 5, 15, and 30 m, were investigated. To anticipate the behavior of reactive flow, a Eulerian-Eulerian CFD model, two-fluid model, was constructed, which was combined with the kinetic theory of granular flow. A four-lump kinetic model was chosen to represent the mechanism of the catalytic cracking reaction of heavy oil from the pyrolysis of waste plastic. The CFD model accurately predicted the species composition distribution. The scaling law based on the geometric similarity, kinematic similarity, and chemical reaction similarity, was proposed. The catalytic cracking performance similarity of the downer reactor was obtained. With variances in the range of 10% and mean relative absolute error less than 5%, the axial and lateral distributions of chemical performance (heavy oil conversion, gasoline mass fraction, and gasoline selectivity) were found to be extremely similar.
气固多相流化学反应器放大的实际实现受到反应器内混沌流动行为以及复杂的传热传质过程的阻碍。此外，现有文献中很少提出多相流系统中复杂反应机理的放大规律。因此，本研究旨在基于化学反应性能的相似性方法，研究催化裂化下行床反应器的放大问题。研究了三种高度分别为5米、15米和30米的下行床反应器。为预测反应流行为，构建了欧拉-欧拉计算流体力学模型（双流体模型），并结合颗粒流动力学理论。选择四集总动力学模型来描述废塑料热解产生的重油催化裂化反应机理。该计算流体力学模型准确预测了物种组成分布。提出了基于几何相似、运动相似和化学反应相似的放大规律。获得了下行床反应器的催化裂化性能相似性。发现化学性能（重油转化率、汽油质量分数和汽油选择性）的轴向和横向分布极为相似，方差范围为10%，平均相对绝对误差小于5%。
