Simulation Reaction Kinetics and Syngas Compositions from Steam Gasification of Lignite Char

Gasification is a thermal process involving the interaction between physical and chemical processes. Thus, it is necessary to understand the operating conditions in the design and operation. The optimum conversion of the solid fuel to the desired gas will depend heavily on the configuration, size and selection of gasifier operating condition. Optimum operating conditions can be obtained through research on existing plants or testing on a particular equipment. In addition, the optimum conditions can also be obtained through mathematical modeling. Although it cannot provide very accurate results, this method can provide clues about the quantitative effects of design, raw materials and other operating parameters. Representation of the gasification process in the form of mathematical equations can also help understand the importance of the effect of operating parameters on the performance of a gasifier and can provide a good understanding of the mechanisms that occur. Gasification involves mass transfer events and chemical reactions. The kinetic equations constructed in the gasification process are mostly based on heterogeneous (solid-gas) reactions whereas in gasification reactions and there is also a homogeneous reaction (gases). It is therefore necessary to prepare a kinetic calculation involving heterogeneous reactions and homogeneous reactions. Random Pore Model was first proposed by Bhatia and Perlmutter. The model uses the assumption that char consists of cylindrical pores with a random size distribution. The rate of heterogeneous reactions, which take place on the contact surface of solid and reactant gas, are dominated by the inner surface area of the pores. The diameter of the pores also influences the transportation of the reactant gases into the solid and the resultant gases out of the solid. The homogeneous reactions are those among gas species; both volatile gases and gasification agent gases reactions include water gas shift reaction. The developed model for the steam gasification of solid chars has been solved under the operating temperatures of 600 degrees C, 700 degrees C and 800 degrees C as used in this experiment. The model has been solved in MATLAB software using a numerical technique.