Analysis of the combustion reaction of carbon and lignite char with ignition and extinction phenomena: Shrinking sphere model

Single-particle combustion of carbon and lignite char is analyzed in the present work using a generalized shrinking sphere model. Finite volume method (FVM), which was earlier employed by the authors in solving such moving boundary problems involving single particle analysis of general fluid-solid noncatalytic reactions, has been used in this work to solve the transient mass and energy balance equations. The computed results are compared with published experimental data of fluidized-bed combustion of lignite char. The effects of various parameters like bulk temperature, initial particle temperature, initial particle radius, etc. are examined on the dynamics of combustion of carbon and lignite char. The phenomena of ignition and extinction are also investigated. The importance of nonequimolar diffusion in the combustion reaction has also been analyzed. (C) 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 307-319, 2007.