Simulation of 3D velocity and concentration profiles in a packed bed adsorber by lattice Boltzmann methods

Full 3D simulations of velocity and concentration profiles were carried out for the several ordered packing arrangements of spherical particles with small tube-to-particle diameter ratio (<10) using lattice Boltzmann methods. The effects of voids and diffusion coefficients on the adsorption concentration profiles in a packed bed of circular cross-section were investigated. In particular, the radial (r) and circumferential (θ) dependencies of the concentrations due to non-uniform velocity and particle voids across tube's cross-section, especially near the walls, were ascertained. The lattice Boltzmann technique allows simultaneous solution to velocity and concentration fields at all locations inside the packed tube without using any empirical correlations for certain transport parameters, for example, dispersion coefficient. Depending upon the packing arrangements and the magnitudes of diffusion coefficient, the concentration gradients in r- and θ-directions were found to be significant. The lattice model simulation results were also compared to the tomographic data obtained in a tubular adsorber packed with the zeolites coated glass beads and were found to be in reasonably good agreement.