Combustion and gasification of individual coal particle during pyrolysis
Journal
Journal of the Chinese Institute of Engineers, Transactions of the Chinese Institute of Engineers,Series A/Chung-kuo Kung Ch'eng Hsuch K'an
Journal Volume
12
Journal Issue
6
Pages
721-728
Date Issued
1989
Author(s)
Abstract
Abstract This work studies the combustion and gasification behavior of individual coal particles in a hot environment. The model contains (1) heat and mass transfer and pyrolysis within the particle, (2) thermal radiation, diffusion and combustion of the reactive gases outside of the particle. The stages of preheating, ignition, and combustion are discussed separately. An index of t 95.50/t 50–5 is proposed and works very well for identifying the border of heat trnasfer controlled regime and the kinetically controlled regime for both the combustion and the gasification processes. The conditions of higher temperature and larger particle favor the heat transfer controlled regime and vice versa. In the kinetically controlled regime the reactivity is very sensitive to the particle size and the gas temperature, especially for the combustion process. The border for combustion is confined to the ranges of smaller particle size and lower surrounding air temperature while compared with the gasification process. The ignition delay time increases with increasing particle size. The particle surface temperature at ignition is higher for smaller particles and hotter surroundings.
Type
journal article