活性炭纤维吸附填充床突破曲线预测(Ⅰ)精确解与近似解

PREDICTION OF BREAKTHROUGH CURVES IN FIXED-BED ADSORBERS OF ACTIVATED CARBON FIBER (Ⅰ) EXACT SOLUTION AND APPROXIMATE SOLUTIONS

针对活性炭纤维吸附填充床,当吸附等温方程为线性时,考虑轴向弥散、纤维内扩散以及纤维外对流传质阻力,获得了阶跃进样时突破曲线的精确解以及拟对数概率密度函数近似解和二次方近似解。并在讨论模型参数对突破曲线影响的同时,对精确解和两种近似解进行了比较。结果表明,在较宽的模型参数范围内,两种近似解与精确解均吻合较好,但二次方近似解复杂,计算困难;而拟对数概率密度函数近似解简单,计算方便。

For the linear adsorption isotherm, an exact solution for the prediction of breakthrough curves (step response) in fixed-bed adsorbers packed with activated carbon fiber is obtained, that takes into account axial dispersion, intrefiber diffusion and external convective mass transfer resistance. The effects of model parameters on the breakthrough curves are discussed. Two kinds of approximate solutions, i. e. , the parabolic profile approximation and the quasi -log normal distribution approximation are also obtained. The results show that the two approximate solutions are in good agreement with the exact solution over a wide range of parameters of Bi, Pe and the bed length parameter θ. The quasi -log normal distribution approximate solutionis a simple, rapid approximate solution for the calculation of breakthrough curves.