关键词: 多孔介质, 传质, 化学反应, 微元体, 综合速率, 数学模拟

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.