对流扩散对多孔介质气固反应的影响

Effect of convection and diffusion on gas-solid reaction in porous media

针对填充床中的气固反应aA(g)+bB(s)=cC(g)+dD(s),在微元体动力学研究的基础上,考虑到气体的压缩性和惰性组分的存在,从渗流力学观点出发,导出了反应气体与产物气体的非线性对流反应扩散方程和混合流体渗流方程,用有效容积法求方程的数值解,通过实例计算,分析了不同条件下的反应转化情况.结果表明,颗粒尺度和反应器长度对反应进程有明显影响,这些影响可以用Thiele数、Peclet数及它们的比值来衡量,适当选取颗粒尺度和反应器长度可以改善反应器性能.

The gas-solid reaction aA(g)+bB(s)=cC(g)+dD(s) in a packed bed is theoretically investigated. For the packed bed with uniform particle size, the overall rate of representative-element volume is obtained from that of a single particle. Owing to the presence of inert gas and the compressibility of the gas mixture, the nonlinear convection-reaction-diffusion equations for the gas reactant and gas product, and the nonlinear flow equation for mixed gas are presented. Computation cases are given numerically by the finite volume method. The results show that the particle size and the reactor length affect considerably the performance of the reactor. Their effects on reaction and conversion can be represented by two dimensionless numbers, Peclet number and Thiele number. The reactor performance can be improved by changing the particle size and the reactor length.`