多孔介质中可逆化学反应和传质过程数值模拟

Numerical Simulation of Reversible Chemical Reaction and Mass Transfer Process in Porous Media

考虑到流体同固体骨架间的化学反应对多孔介质内的传递过程有很大影响,在导出微元体的综合速率表达式基础上,建立了描述当流体同固体骨架间存在可逆化学反应时多孔介质内传递过程的数学模型,运用有效容积隐式方法对其进行数值求解·针对固定床中铁矿石的间接还原反应,分析了流速、颗粒半径、化学反应平衡常数、化学反应速率等主要参数以及Peclet数和Thiele数的相对大小对床层内气体浓度分布和固体转化率分布的影响规律·研究结果对反应器的设计和运行具有一定的参考作用·

The chemical reactions between fluid and porous matrix affect greatly the mass transfer process in porous media. A convection-reaction-diffusion mathematical model is thus developed by deriving a comprehensive formula of the representative elementary volume (REV), to describe the mass transfer process in porous media when the fluid and porous matrix take reversible chemical reaction. A numerical solution to the model is available by way of the finite volume implicit method. Taking the indirect reduction of iron ore in static bed into account, the influences of such main parameters as flow rate, particle size, equilibrium constant in chemical reaction and reaction rate and the ratio of the Peclet number to the Thiele number on the distribution of gas concentration and of fractional solid conversion are all analyzed. The results are useful for the conceptual design and operation of reactor.