Multicomponent Transport Effects in Sorbent Particles under Pressure Swing Conditions

Abstract

A comprehensive theoretical study of the problem of multicomponent adsorption−desorption in sorbent particles under pressure swing conditions is carried out in this study. A rigorous mathematical model is formulated for the process in which the dusty-gas model and the commonly used Fickian model are employed to describe the coupling of the mass fluxes and the partial pressures in the pore space, with or without viscous flow. The dusty-gas model is used as a standard against which the performance of the Fickian model is tested. Computations are carried out for binary and quaternary mixtures. It is found that the rigorous model (the one based on the dusty-gas model) predicts faster responses for the partial pressures of the components in the mixture. Faster responses are also observed when the viscous flow is accounted for in the transport model, with the effect being considerably stronger in the case of the Fickian model. The obtained results are also used to investigate the performance of the Glueckauf linear driving force approximation for multicomponent systems. It is concluded that like the Fickian diffusion model on which it is based, this approximation cannot predict, even qualitatively, the dynamic responses of the partial pressures in a multicomponent system.

Adsorption Characteristics of Hydrogen Mixtures in a Layered Bed: Binary, Ternary, and Five-Component Mixtures

“…Recently, the Stefan-Maxwell approach 28,29 or the dusty gas model 30,31 have been used to describe adsorption kinetics. However, Sircar and Hufton 32 pointed out that the LDF model for gas adsorption kinetics is frequently and successfully used for the analysis of adsorption column dynamic data and for adsorptive process designs because of its simplicity, ease of analysis, and physical consistency.…”

Macropore diffusion dusty-gas coefficient for pelletised zeolites from breakthrough experiments in the O2/N2 system

“…It is assumed in this study that interpellet gas temperature T B changes directly with pellet temperature T P such that T B = T P = T . Serbezov and Sotirchos (1998) have shown the pellet-to-gas heat transfer resistance is negligible under the relatively high gas velocity conditions typical of a PSA cycle. Simulations with varying magnitudes on the pelletto-gas heat transfer coefficient have also confirmed this result (Todd, 2003).…”

Elementary Kinetic Theory of Gases

“…However, the validity of Knudsen diffusion modeling by the dusty gas and Wilke-Bosanquet models are subjected to criticism in the literature, see for example, the recent review by Krishna [76]. Mathematical modeling of intra-particle mass and heat transport in porous pellets has thus been widely investigated by numerous researchers, e.g., [12,34,51,125,127,128,155,156], because the intra-particle transport limitations often play an important role in the design of chemical rectors. Most mass diffusion problems in chemical reactor processes involve transport of multicomponent mixtures.…”