催化重整固定床反应器传递及反应过程的数值模拟

NUMERICAL SIMULATION OF THE TRANSFER AND REACTION PROCESSES IN CATALYTIC REFORMING FIXED BED REACTORS

全面系统地分析了催化重整固定床反应器(Catalytic reforming fixed bed reactor,以下简称CRFBR)内物料的流动、传热、传质和重整反应等过程及各过程之间强烈的相互作用,以流体力学的基本微分方程为基础,考虑流体的湍流流动和多孔介质内流体流动、传热、传质等过程,结合催化重整集总反应动力学模型,建立了CRFBR传递及反应过程的综合数学模型,并给出了模型求解的边界条件和相应的数值计算方法。模拟计算得到了反应器内轴向和径向速度场、压力场、温度场和组分浓度场的详细信息,揭示了各种过程之间的内在规律和相互作用。结果表明,径向反应器床层中上部,沿流程方向,单位厚度上的床层温降逐渐变小;轴向上压力梯度很小,温度梯度较明显。径向反应器床层底部流体流动不均匀,出现"冷点"。用工业装置数据对模型进行了验证,两者基本吻合,验证了模型的合理性。

Flow, heat transfer, mass transfer, reforming reactions and their intense coupling effect in catalytic reforming fixed bed reactor （CRFBR） were analyzed systematically. By considering flow, heat transfer, mass transfer in porous media bed, a mathematical model for CRFBR was developed based on basic transport differential equations of hydrodynamics, together with k-ε turbulence model, and coupling with reforming reaction kinetic model. At the same time, the boundary conditions and related numerical solutions were put forward. Some detailed information about the velocity field, the pressure field, the temperature field and concentration distribution in axial and radial reactors was obtained, presenting the basic characteristics of every process and their effect. The results indicated that the temperature drop became slow along flow in the middle and top of the bed in radial reactor, and the pressure drop was small, but temperature drop was evident in axial direction, at the bottom of radial reactor the flow was inhomogeneous with the lowest temperature point over there. The numerical simulation in industrial CRFBR by this model was carried out to prove its rationality.