催化裂化提升管反应器气液固3相流动反应的数值模拟Ⅲ.流动传热及反应的数值模拟

NUMERICAL SIMULATION ON THE GAS LIQUID SOLID THREE PHASE FLOW REACTION IN FCC RISER REACTORS Ⅲ.Numerical Simulation on the Flow,Heat Transfer and Reaction

在对工业提升管反应器气液固３ 相系统的数值模拟，得到原料液雾流动与气化状况的基础上，获得了气固两相的速度场、温度场和浓度场的详细信息， 并与两相模型的相应结果进行了对比。模拟结果表明， 提升管下部是最复杂的部分，气固两相流场、湍动能以及催化剂颗粒浓度场在轴向、径向和圆周方向都存在着较大的梯度。气固两相温度分布在３ 个坐标方向上是非常不均匀的， 但两相温差除喷嘴附近外均较小，反应结果表现出类似的不均匀分布形态。出口处反应温度和气相各组分浓度的计算值与工业数据吻合较好，说明模型对工业催化裂化提升管反应器流动反应状况的良好预测性，也验证了本研究的合理性和可靠性。与两相模型的结果对比发现， 各物理量的空间分布形态基本一致， 但在进料区域因对进料的模化方法不同而有一定差异。由于３相模型较真实地体现了原料气化过程及其影响，且出口计算结果更接近工业数据，故其预测性、合理性和可靠性都优于气固两相流动模型。

Some detailed information about the flow field,temperature field and concentration field of gas and solid phases was obtained by the comprehensive numerical simulation on the gas liquid solid three phases in the commercial FCC risers and on the basis of the acquisition of feed spray flow and evaporation patterns.Comparison between the above results and their counterparts of two phase model was worked out.The results showed that the most complicated part is at the bottom of the riser reactor.The flow field,turbulent energy and catalyst concentration field of both gas and solid phases are characteristic of big gradients in the radial,axial and tangential directions.The temperature distributions of gas and solid phases are also inhomogeneous in three coordinate directions.Gaseous composition showed the similar distribution,but gas solid temperature slip was small except at the vicinity of feed nozzles.A good correspondence of the predicted riser outlet temperature and gaseous composition with the commercial data gave a good evidence that the three phase flow reactin model was excellent for predicting the flow and reactions in the catalytic cracking riser reactor.Meanwhile,the rationality and reliability of the present study were examined thereof.It showed that the distribution of all variables was identical over the riser with the results predicted by two phase model.However,there are some discrepancies of the distribution in the feeding zone by adopting different feed spray simulation ways for different models.It was seen that the predictability,rationality and reliability of the three phase model were better than that of the two phase,because in the former case the influence of the feed spray evaporation and its predicted riser outlet data are more in comformity with the commercial data.