HEAT-EFFECTS IN ADSORPTION COLUMN DYNAMICS .1. COMPARISON OF ONE-DIMENSIONAL AND 2-DIMENSIONAL MODELS

A two-dimensional model that includes radial thermal conduction has been developed to investigate the dispersive effect of heat, including the effect of a radial temperature gradient, on adsorption column dynamics. Such effects can be much greater than axial dispersion. The form of the breakthrough curves can be well represented by the isothermal dispersed plug flow model using an appropriately modified dispersion coefficient. When the natural velocity of the temperature wave is lower than that of the concentration wave, leading to a combined wave front, a simple one-dimensional model with heat transfer to the column wall provides a good prediction of the dynamic behavior. However, when the thermal front leads the concentration wave (pure thermal wave formation), the one-dimensional model overpredicts the dispersion. To obtain an accurate prediction of the dynamic behavior under these conditions requires the use of the two-dimensional model. © 1990, American Chemical Society. All rights reserved.