Modelling of adsorption separation of gas mixtures with allowance made for the thermal effects accompanying adsorption: V. Specific patterns of adsorption separation of one substance from a gas mixture in the adiabatic case

Abstract

The procedure for the elimination of the terms of model equations of non-isothermal adsorption dynamics for multicomponent mixtures that take into account dispersive factors (both the kinetics of mass and heat transfer and longitudinal mixing and longitudinal heat conductance along the adsorber) has been analysed. It is emphasized that the elimination of terms is only valid in the case where conditions ‘F’ (see References 19 and 20) are satisfied. The transformation of the stable frontal patterns into unstable frontal patterns using the Langmuir thermal adsorption equations is shown. The concept of effective thermal diffusion for the adiabatic adsorption of one substance in the mixed kinetic region in the absence of the ‘classical’ thermal diffusion transfer within porous grains of adsorbents is considered. The role and the influence of effective thermal diffusion and diffusion thermal heat and mass transfer on the kinetics and dynamics of adiabatic adsorption have also been analysed. For various thermal models of the adiabatic case simple practical formulae have been obtained for use in calculating the width of heat and mass transfer zones in the real laboratory and in industrial adsorbers.