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Coal Char (coal + char)
Selected AbstractsModeling and experimental studies on combustion characteristics of porous coal char: Volume reaction modelINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2010Anup Kumar Sadhukhan A generalized single-particle model for the prediction of combustion dynamics of a porous coal char in a fluidized bed is analyzed in the present work using a volume reaction model (VRM). A fully transient nonisothermal model involving both heterogeneous and homogeneous chemical reactions, multicomponent mass transfer, heat transfer with intraparticle resistances, as well as char structure evolution is developed. The model takes into account convection and diffusion inside the particle pores, as well as in the boundary layer. By addressing the Stefan flow originated due to nonequimolar mass transfer and chemical reactions, this work enables a more realistic analysis of the combustion process. The model, characterized by a set of partial differential equations coupled with nonlinear boundary conditions, is solved numerically using the implicit finite volume method (FVM) with a FORTRAN code developed in-house. The use of a FVM for solving such an elaborate char combustion model, based on the VRM, was not reported earlier. Experiments consisting of fluidized-bed combustion of a single char particle were carried out to determine the internal surface area of a partially burned char particle and to enable model validation. Predicted results are found to compare well with the reported experimental results for porous coal char combustion. The effects of various parameters (i.e., bulk temperature and initial particle radius) are examined on the dynamics of combustion of coal char. The phenomena of ignition and extinction are also investigated. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 299,315, 2010 [source] Kinetic study of the gasification of an Australian bituminous coal char in carbon dioxideASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Chetan R. Chodankar Abstract Experimental work was carried out to study the kinetics of the carbon dioxide gasification of a coal char. The coal char was prepared from an Australian bituminous coal by pyrolyzing it at 900 °C in a tube furnace for 9 min in inert environment. The coal char was gasified in a thermo-gravimetric analyzer (TGA) with a mixture of carbon dioxide and nitrogen. The effects of gasification temperature (800,875 °C) and carbon dioxide concentration (10,80%) were studied. In the present study the reaction rate of the pyrolyzed coal was obtained and interpreted by Random pore model. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||