Rigorous Model for the Simulation of Gas Adsorption and Its Verification

Abstract

A rigorous model containing conservation equations of momentum, energy, and mass, with their kÀε, t 2 Àε t , and newly developed c 2 Àε c closing formulations was proposed for simulating the gasÀsolid adsorption process. The feature of the proposed model is that the unknown turbulent mass-transfer diffusivity D t need not be estimated in advance. With this model, the breakthrough, regeneration, and temperature curves, as well as the D t , were simulated for the methylene chloride adsorption and regeneration processes. The simulated results were closely checked by the published data. It was found that the D t was unevenly distributed in the axial and radial directions, which means that the Schmidt number or Peclet number is varying throughout the adsorption column and cannot be simply represented by a constant or a simple formula. The simulated results on axial and radial concentration distributions along the column at different time are helpful to understand the process dynamics. The proposed model is especially useful for simulating the adsorption process where the turbulent mass-transfer diffusivity is unavailable.

Mass Transfer Coefficients for CO2 Absorption into Aqueous Ammonia Using Structured Packing

“…Difference is clearly seen between the CO 2 mass fraction at the column center region and that in vicinity of the column wall. In fact, this tendency was obtained by many simulation works, 52,59 and could be attribute to the wall effect. 6.6.2.…”

A Turbulent Mass Diffusivity Model for Predicting Species Concentration Distribution in the Biodegradation of Phenol Wastewater in an Airlift Reactor

“…In the biodegradation of wastewater in an ALR, the prediction of the distribution of species concentration is often simplified and case-specific. Sun et al proposed a theoretical model to calculate D t in a distillation column by solving the auxiliary concentration variance and its dissipation rate equations [24], and it has been successfully used for simulating the turbulent mass transfer process in adsorption columns [25], circulating fluidized beds [26], and bubble columns [27].…”

An anisotropic turbulent mass transfer model for simulation of pilot-scale and industrial-scale packed columns for chemical absorption

“…To avoid the use of the Sc t or its experimental expression, a rigorous model, so called c 02 À e c 0 model was developed recently [13] and has been successfully applied to predicting a number of mass transfer processes [13][14][15][16][17][18][19][20]. In this model, D t was calculated by (2) and the assumption of isotropic diffusivity D t , which is in contradiction with the high anisotropic turbulent diffusion existing in packed columns [21,22].…”