Thermodynamic properties of pulverized coal during rapid heating devolatilization processes. Quarterly progress report, January--March 1994

Knowledge of the thermodynamic and morphological properties of coal associated with rapid heating decomposition pathways is essential to progress in coal utilization technology. Specifically, knowledge of the heat of devolatilization, surface area and density of coal as a function of rank characteristics, temperature and extent of devolatilization in the context of rapid heating conditions is required both, for the fundamental determination of kinetic parameters of coal devolatilization, and to refine existing devolatilization sub-models used in comprehensive coal combustion codes. The objective of this research is to obtain data on the thermodynamic properties and morphology of coal under conditions of rapid heating. Specifically, the total heat of devolatilization, external surface area, BET surface area and true density will be measured for representative coal samples. In addition, for one coal, the contribution of each of the following components to the overall heat of devolatilization will be measured: the specific heat of coal/char during devolatilization, the heat of thermal decompose ion of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Progress reports are presented for the following tasks: heat of devoltalization of voltaile coal samples; specific heat and heat of fusion of tars; heat of vaporizationmore » of tars from rapid heating; and morphological characterization of coal/char samples as a function of extent of devoltalization.« less