Kinetically Controlled O2 - N2 Adsorption for Air in a Carbon Molecular Sieve

One of the more interesting separation processes which has been developed in recent years in air separation by fixed bed adsorption on a carbon molecular sieve. Unlike most adsorptive separations the selectivity in the system is kinetic and depends on the faster diffusion of oxygen within the micropores of the carbon sieve. The oxygen is therefore preferentially adsorbed and using properly selected conditions it is possible to obtain a fairly high purity nitrogen product. The analysis of the above experiments requires a model for a two-component system. We consider an isothermal, dispersed plug-flow system in which frictional pressure drop in the bed is negligible. The variation in fluid velocity along the length of the column is accounted. The equilibrium relationships are represented by ternary Langmuir isotherm, and the mass transfer rates are given by linear driving force (LDF) rate expression .In order to solve the coupled partial differential equation, an orthogonal collocation method is employed. Also, we constructed an experimental set up .The experimental set up is a single column, of stainless steel (length 1000 mm, inside diameter 25 mm) was packed with carbon molecular sieve. The separation of air by pressure fixed bed carbon molecular sieve has been studied both experimentally and numerically over a wide range of product purities. A good agreement has been found between the experimental results and the prediction of dynamic adsorption process simulator over a wide range of purities.

Keywords:

Air Separation , Carbon Molecular Sieves , Kinetically Adsorption , Dynamic Model