Breakthrough curves for fixed‐bed adsorbers: Quasi‐lognormal distribution approximation

Abstract

Abstract The quasi‐lognormal distribution (Q‐LND) approximation was used to predict breakthrough curves in fixed‐bed adsorbers for a linear adsorption system with axial dispersion, external film diffusion resistance, and intraparticle diffusion resistance for slab–, cylindrical–, and spherical‐particle geometries. The exact solution and parabolic profile approximation were also obtained for different particle geometries. Numerical results show that the Q‐LND approximation is a simple and handy solution. It predicts breakthrough curves with an accuracy comparable to the parabolic‐profile approximation over a wide range of parameters; compared with the latter, it only takes less than one hundredth the computation time and does not have a convergence problem in numerical calculations. A criterion for the applicability of the Q‐LND approximation is suggested. The effect of particle geometries on the breakthrough curves is discussed. A criterion is also provided for the Q‐LND approximation to explore the conditions where one should consider this effect on breakthrough curves.