Devolatilization of coal particles in a flat flame -- Experimental and modeling study
- Universite des Sciences et Technologies de Lille, Villeneuve D`Ascq (France). Laboratorie de Cinetique et Chimie de la Combustion
- CERCHAR, Mazingarbe (France)
- Ecole National Superieure de Chimie, Mulhouse (France). Lab. de Gestion des Risques et Environnement
Pulverized coals have been tested under the conditions of industrial flames, with high heating rate and high temperatures. The chars were collected after different pyrolysis times. For eight coals, the devolatilized fraction of coal has been measured, as well as those of carbon, hydrogen and nitrogen. During pyrolysis, the evolution of the texture of the grains has been studied by measurement of their microporous surface area, which undergoes a large increase, depending on coal rank. The composition of the volatiles, as deduced from the ultimate and proximate analysis of chars, showed high volatile bituminous coals to essentially produce tars with an aromatic structure. Low and medium volatile bituminous coals produced light hydrocarbons on devolatilization and the char`s surface area continued increasing slowly during the whole of devolatilization, according to the slow increase of the fraction of hydrogen devolatilized. The char`s reactivity with oxygen was followed by measurements of Active Surface Area (ASA). It was shown that the ASA continuously decreases during devolatilization. Five models of devolatilization in the literature were tested and compared to the experimental results, assuming first-order reactions with respect to the remaining volatile matter. Badzioch`s model correctly fitted the experimental results and values of the rate constant obtained by computer trial and error adjustment were higher for lower ranks of the four bituminous coals. Anthony`s model also fits the measurements, provided an adjustment of the preexponential factor of activation energy for which it is shown that an infinite number of such pairs is suitable. If the model is run isothermally at the flame`s peak temperature, it also correctly fits the experimental results.
- OSTI ID:
- 116462
- Journal Information:
- Combustion and Flame, Vol. 103, Issue 1-2; Other Information: PBD: Oct 1995
- Country of Publication:
- United States
- Language:
- English
Similar Records
A model for the devolatilization of a coal particle sufficiently large to be controlled by heat transfer
Thermodynamic properties of pulverized coal during rapid heating devolatilization processes. Quarterly progress report, April--June 1993