AN IMPROVED MODEL FOR FIXED-BED COAL COMBUSTION AND GASIFICATION - SENSITIVITY ANALYSIS AND APPLICATIONS

Detailed sensitivity analysis and applications of an improved, compreh ensive, one-dimensional model for combustion and gasification of coal in fixed beds, FBED-1, are presented. The effects of the devolatilizat ion, oxidation and gasification submodels on the model predictions are discussed. The product gas compositions predicted by various options for gas-phase chemistry are shown. The effects of five model parameter s and one operational variable on the predictions of the model are als o presented. The sensitivity analysis presented is quantitative since the boundary conditions for both the feed coal and the feed gas stream s are satisfied exactly. The utility of the model as a design and anal ysis tool is demonstrated by simulating two gasifiers: an METC medium- pressure gasifier, and a PyGas high-pressure staged gasifier. Submodel s and areas that need further improvements are identified; among these are submodels for large-particle devolatilization, oxidation and gasi fication and a robust solution method suitable for stiff, highly non-l inear problems. Additional features that should be implemented to deve lop a model for general industrial applications are also identified. T hese include provisions for additions and withdrawals of gases at mult iple locations and options for different flow configurations. Copyrigh t (C) 1996 Elsevier Science Ltd.