EVALUATION OF ERRORS RESULTING FROM PARTICLE SHAPE ASSUMPTIONS APPLIED IN COAL COMBUSTION MODELING

Abstract

This chapter presents an evaluation of errors resulting from particle shape assumptions applied in coal combustion modeling. An electrodynamic balance (EDB) system has been developed with high-speed instrumentation to rapidly heat individual coal or carbon particles while measuring and recording changes in particle size and temperature. This system has been applied to study the early stages of heating and devolatilization of coals at heating rates on the order of 10 K/s. The chapter presents a study in which experiments were performed on individual particles of an aerodynamically size-classified Pittsburgh seam bituminous coal designated as PSOC-1451D. A number of approaches were applied to characterize coal particle shape and mass. Mean mass measurements were made by weighing and counting several thousand particles. A volume mean diameter for the size cut studied was determined using a Coulter counter. Drag-to-mass ratios for individual particles were determined by applying a dynamic force balance model to match measured particle oscillations in the EDB. The mass of individual particles was inferred from drag/mass measurements using projected cross-sectional areas taken in the image planes parallel and perpendicular to particle motion.