Coal combustion: Effect of process conditions on char reactivity. Quarterly technical report No. 14, January 1, 1995--March 31, 1995

The project will quantify the effect of the following pyrolysis conditions on the macropore structure and on the subsequent reactivity of chars: (a) pyrolysis heating rate; (b) final heat treatment temperature; (c) duration of heat treatment at HTT (or soak time); (d) pyrolysis atmosphere (N{sub 2} or O{sub 2}/N{sub 2} mixtures); (e) coal particle size (100--1,000 {mu}m in diameter); (f) sulfur-capturing additives (limestone); and (g) coal rank. Pyrolysis experiments will be carried out for three coals from the Argonne collection: (1) a high-volatile bituminous coal with high ash content (Illinois No. 6), (2) a bituminous coal with low ash content (Utah Blind Canyon) and (3) a lower rank subbituminous coal (Wyodak-Anderson seam). A systematic study was carried out in the past quarter to validate the mathematical model for ignition phenomena presented in the previous quarterly report. Model predictions of the effect of pyrolysis heating rate, particle size, and oxygen concentration on ignition behavior are in excellent agreement with experimental results. Moreover, our results show that the model can be used to estimate the particle temperature during ignition and the minimum ignition temperature for various process conditions