ABSTRACT
This chapter considers aspects of heterogeneous combustion which relate to the combustion of droplets, pools of flammable liquids and kinetic aspects of carbon or char oxidation. It discusses some practical applications which involve heterogeneous combustion. In liquid–gas and solid–gas systems, combustion may occur either at the surface or in the gas phase. Commonly the vaporisation of liquids precedes reaction so that combustion occurs in the gas phase, but solids may decompose quite readily also to form volatile components. In heterogeneous systems, the products of combustion tend to separate the fuel from the oxidant but this protection is reduced if the gas is in motion relative to the condensed material. If the liquid droplet exceeds the critical size the combustion takes the form of a spherical diffusion flame around the droplet. The best-known example of coal combustion is provided by the domestic fire and the majority of industrial coal burners operate on the same overfeed principle.
