Increasing demand of automobile fuel and a need to process heavier crude oil makes it imperative to find improvements to the design of existing fluid catalytic cracking (FCC) units. Several modifications to the design of the riser section of FCC units have been suggested in previous studies including: improved feed nozzle designs, multiple nozzle configurations, internal baffles, and novel two-stage-riser systems. In this study, we investigate the effects of baffles on the performance of FCC risers using computational fluid dynamics simulations. In this study, predictions from a basis model (without baffles) are compared with those from four different configurations including: (i) 5-cm baffles at 5-m spacing, (ii) 7.5-cm baffles at 5-m spacing, (iii) 10-cm baffles with 5-m spacing, (iv) 10-cm baffles at 2.5-m spacing, and (v) 10-cm baffles at 1-m spacing. The baffles force the catalyst away from walls toward the center of the riser, enhancing the radial dispersion of the catalyst and the heat transfer inside the riser. The use of longer baffles and smaller spacings further increases the dispersion, yielding more homogeneous radial profiles. The changes in the radial dispersion result in variations in the conversion, yields, and pressure drops. The baffles increase conversion of vacuum gas oil (VGO) and the yield of gasoline. However, the simulations showed that longer baffles and a larger number of baffles did not always give a higher yield or higher conversion. Among the simulated configurations, the 5-cm baffles at 5-m spacing gave the highest conversion of VGO, whereas the 10-cm baffles at 1-m spacing resulted in the highest yield of the gasoline. Thus, rational optimization of baffle configurations is required to achieve optimal performance.

汽车燃料的需求不断增长，以及需要处理更重的原油，因此必须对现有的流化催化裂化（FCC）装置的设计进行改进。在先前的研究中，已经提出了对FCC单元提升管部分设计的一些修改，包括：改进的进料喷嘴设计，多喷嘴配置，内部挡板和新颖的两级提升系统。在这项研究中，我们使用计算流体动力学模拟研究挡板对FCC立管性能的影响。在本研究中，将基础模型（无挡板）的预测与四种不同配置的预测进行了比较，包括：（i）5厘米间隔的5厘米挡板，（ii）5米间隔的7.5厘米挡板，（ iii）间距为5米的10厘米挡板，（iv）间距为2.5米的10厘米挡板，（v）1米间隔的10厘米挡板。挡板迫使催化剂从壁向立管的中心离开，从而增强了催化剂的径向扩散以及立管内部的热传递。较长的挡板和较小的间距的使用进一步增加了分散度，从而产生了更均匀的径向轮廓。径向色散的变化导致转化率，产率和压降的变化。挡板提高了真空瓦斯油（VGO）的转化率和汽油的收率。但是，仿真显示，较长的挡板和大量的挡板并不总是能够提供更高的产量或更高的转化率。在模拟配置中，以5米间隔的5厘米挡板提供了最高的VGO转化率，而以1米间隔的10厘米挡板则获得了最高的汽油收率。因此，