【摘要】 多孔介质反应器内流体同固体骨架间的化学反应和流体的传输过程同时进行,并相互影响·采用Ergun-Forchheimer-Brinkman方程描述多孔介质中的流体流动,建立了柱坐标下多孔介质反应体系内对流-扩散-非线性反应数学模型·运用交替方向隐式(ADI)方法对模型离散求解·以固定床中铁矿石的间接还原反应为例,计算了不同条件下床层内反应气体浓度场和固体转化率分布·结果表明,增大入口渗流速度将使得反应气体浓度场升高,发生化学反应的区域加深,固体物料转化率增大·在反应器入口端附近,颗粒半径越小,固体转化率越高,但随反应区域的逐渐深化,固体转化率分布则呈相反变化的趋势·更多还原

【Abstract】 The chemical reactions between fluid and porous matrix and the fluid transfer process are proceeding simultaneously and interactively with each other in a porous reactor. A nonlinear mathematical model is developed for the convection/diffusion in cylindrical coordinates through Ergun-Forchheimer-Brinkman equation to express the fluid flow within the porous medium, which is solved discretely and numerically by an ADI (alternate dimension implicit) method. Taking the indirect reduction of iron ore in fixed bed as example, the profiles of the reactive gas concentration field and fractional conversion distribution of solid reactants are given by changing relevant parameters. The results show that the seepage flowrate and particle size are the important parameters affecting significantly the reactive characteristics of the porous reactor. An increase in convection velocity results in both increasing concentration fields of reactive gas and solid fractional conversion which also increases with decreasing particle size in the region near reactor entrance. But, when the region where the chemical reaction takes place deepens gradually, the solid fractional conversion distribution varies reversely, i.e., the solid fractional conversion decreases with particle size.更多还原