Single Nonisothermal Noncatalytic Solid-Gas Reaction. Effect of Changing Particle Size

Abstract

The effect of changing particle size and other time-dependent phenomena, including intermolecular gas film diffusion, intraparticle ash layer diffusion, and chemical reaction rate, on conversion-time relationships in a spherical pellet undergoing a first-order irreversible reaction was deduced from a shrinking-core model. For both isothermal and nonisothermal conditions, particle size changes proved significant whenever the reaction was controlled by intermolecular and/or intraparticle diffusion. When both intermolecular and intraparticle resistances were present simultaneously and the heat transfer coefficient was small, the shrinking particle required less time than the growing particle to give a particular conversion in the nonisothermal case but more time in the isothermal case. The results of this U.S. Energy Research and Development Administration-supported study, which could apply also to coked catalyst regeneration, will be used to model fluidized bed reactors for coal conversion.