A NEW DISCRETE SIMULATION METHOD FOR MODELING CHAR GASIFICATION IN TXE DIFFUSION-CONTROLLED REGIME

Cellular automata and discrete iterations are employed to develop a new simula-tion method for gas-solid reactions. This approach overcomes many of the limita-tions of earlier models since it can handle heterogeneous systems with multiple porous reactants and arbitrary pore/solid geometries. The new models are used to simulate the gasification of porous char particles under conditions leading to strong intraparticle diffusional limitations and to low utilization of the micro-pores. In order to accurately account for the effects of the macropore structure on char reactivity, the new models employ computational grids obtained by digi-tizing images of actual char particle cross-sections using an optical microscope equipped with a video camera and an image processing computer. Simulation results are presented from multiple runs performed on several char samples that were pre-pared in o u r laboratory by pyrolyzing two parent coals under various operating conditions. Model predictions are compared and analyzed in order to elucidate the effects of the macropore structure on the gasification rates and particl