Chemical and Physical Development of Char Particles during Devolatilization: Final Report

摘要

The objective of this project was to explore the chemical and physical development of coal char particles during devolatilization and, from the data obtained, develop predictive models which would describe the chemical and physical properties of the chars as they develop and change in the devolatilization process. These predictive models relate the chemical, thermal, optical, other physical properties, and kinetic rates to time, temperature and composition parameters as they change in the devolatilization process. Experiments were performed to study the chemical and physical transformation of char during devolatilization. These experiments were used to determine the controlling mechanisms for the transformation and to develop computer models to describe it. Experiments were performed in several existing facilities (an entrained flow reactor, a heated tube reactor, and a Thermogravimetric analyzer) with analysis of evolved products by Fourier Transform Infrared spectroscopy (TG-FTIR), which were previously described. A new non-isothermal technique was developed for measuring char reactivity and a new transparent wall reactor was built to study devolatilization and combustion using in-situ FT-IR diagnostics. Results were obtained for the spectral emittance of coal and its transformation during devolatilization. The question of heat transport between coal particles and their environment was studied. Measurements were made for char reactivity and its relationship with coal properties and pyrolysis conditions. A new general model of coal devolatilization was developed. An equilibrium model was added to the general model to describe the high temperature gas phase reactions and an evaluation was made of kinetic rates measured at AFR and reported in the literature to identify reasons for the discrepancies and identify the most reliable values. 113 refs., 75 figs., 16 tabs. (ERA citation 14:014148)