Effective Diffusivities and Convective Coefficients for CaO‐CaSO₄ and CaO‐CaCl₂ Pellets

Abstract

Diffusion and convective flow in the pores of pellets formed by compressing mixtures of calcined limestone and CaSO 4 /CaCl 2 powders have been studied experimentally by using the single pellet moment technique. The experiments were conducted in a diffusion cell by flowing nitrogen gas (carrier) through both faces of the pellet. Limestone powder was calcined in an atmosphere of N 2 at 800 C and mixed with CaSO 4 /CaCl 2 for diffusion experiments. Effective diffusivity of helium has been estimated by exposing the upper face of the pellet to a pulse of and matching the response peak on the lower face of the pellet with theoretical expressions. The values of the effective diffusivities increased with temperature, but decreased with increasing CaSO 4 /CaCl 2 content in the pellet. The convective flow contribution to the diffusion flux was found to increase with increasing pressure drop across the pellet.

Dynamic Analysis of Diffusion and Adsorption of Water‐Miscible and Water‐Immiscible Organic Vapors in Soil

“…The single pellet moment technique originally developed by Dogu and Smith [10] has been extensively used for the determination of effective diffusivities of non-adsorbing and adsorbing gases and adsorption equilibrium constants in porous catalyst pellets [10±12], and other solid pellets [13]. Recently, the single pellet moment technique has been modified and applied to investigate the adsorption and diffusion of volatile organic pollutants in soil [14±17].…”