Effect of Diffusion of Coal Pyrolysis Products on the Ignition Characteristics and Conditions of Coal–Water Fuel Droplets

Abstract

This paper presents a theoretical study of the thermal preparation and ignition of a coal–water fuel droplet under intense radiative-convective heating with diffusion of gaseous pyrolysis products of the solid fuel into the ambient gaseous medium. It has been found that gaseous pyrolysis products are ignited at a distance from the heating surface approximately equal to the radius of the droplet, after which the coke of the main fuel layer is ignited. The time between the ignition of volatiles and the coke residue is less than 0.5 s. Comparison of the ignition delays obtained by mathematical modeling and experimentally has shown satisfactory agreement between theoretical and experimental values.