Abstract:

The complex flow in the feed injection zone of the fluidized catalytic cracking (FCC) riser reactor was theoretically analyzed. By introducing a series of simplifications, the concept of“blocking”was proposed for the first time to convert the continuous feed spray into individual clusters, the mixing/contacting of the catalysts with feed oil was discussed in the mesoscopic scale based on the law of momentum conservation. The occurrence of the secondary flow which was separated from feed spray was interpreted sequentially. Furthermore, on the basis of the Kutta-Joukowski lift theorem in aerodynamics, the extension and the development of the secondary flow were theoretically deduced. Thus the whole evolution process of the secondary flow in the feed injection zone was clearly described. By combining the wall jet and the Kutta-Joukowski lift theories, a model for determining the location of the secondary flow centerline is given. Compared with the experimental results, the model curve has a high degree of agreement with the secondary flow development trend in the experiment, indicating that the model can be used to predict the flow characteristics of the secondary flow in the riser.

Key words: FCC, riser reactor, feed injection zone, multiphase flow, mesoscale, hydrodynamics

摘要：

针对催化裂化提升管反应器进料混合区域内的复杂流场，提出将连续喷嘴进料射流“分块”，利用动量守恒定律，从介观角度分析喷嘴射流与催化剂颗粒之间的混合接触机理；解释了“二次流”从射流主流分离出来的原因。利用空气动力学中的Kutta-Joukowski升力理论，阐明了在提升管内喷嘴射流二次流动后期的发展和扩大过程，实现了对进料射流二次流动全周期演变过程的理论描述。结合附壁射流理论与Kutta-Joukowski升力理论，建立了用于描述提升管内射流二次流动中心流线的模型方程。与实验结果对比，模型曲线与实验中二次流发展趋势有着较高的吻合度，表明该模型能够用于预测提升管内二次流的流动特性。

关键词: 催化裂化, 提升管反应器, 进料段, 多相流, 介尺度, 流体动力学