A general model of pulverized coal devolatilization

A general model for pulverized coal devolatilization is proposed in this paper. The difference between the present model and previous models is that the equivalent activation energy, E, and the equivalent frequency factor, K0, of coal particle devolatilization are independent of coal type, and depend only on the final temperature, T∞, of the coal particles. This is a new conclusion that is contrary to previous theories. The relationship between EK0 and T∞ has been obtained and is found to be universal for all types of coals. If the final volatile yield, V∞, is determined under certain conditions, the devolatilization processes of fine coal particles for any kind of coal can be predicted by using the model. This model has been tested with three Chinese coals, and five American coals. The coal devolatilization process was studied in a drop tube furnace heated by an arc plasma jet using ArN2 as an operating gas and by electrical heating elements. The experimental conditions were as follows: the diameters of the coal particles range from 35 μm to 100 μm and temperature from 973 K to 2100 K. The volatile yield was obtained by means of an ash tracer. The gas flow inside the tube is laminar, so that the dispersion of coal particles in the tube is quite small.