Modeling of Drying of Gases Using Solid Desiccants.

The article presents theoretical analysis of the adsorptive drying process of gases in a cyclic temperature swing adsorption (TSA) system with two fixed bed adsorption columns. Silica gel is used as a solid desiccant due to its ability to provide extremely low dew points. In each column the adsorption cycle consists of three steps: water vapor adsorption, water desorption, and bed cooling. A mathematical model describing the TSA process consists of integrated partial differential and algebraic equations. The model considers mass transfer resistances, axial diffusion, and the heat transfer from the columns to the atmosphere. The set of partial differential equations (PDEs) representing the packed bed is solved by the numerical method of lines (NMOL). The computer simulations results are used to study the effects of the inlet gas relative humidity φin on the breakthrough curves in the adsorption step and purge gas temperature Tin on the breakthrough curves in the desorption step. The distribution of the moisture and the temperature in the bed is analyzed for the adsorption and regeneration steps. [ABSTRACT FROM AUTHOR]