The combustion of clouds of coal particles in shock-heated mixtures of oxygen and nitrogen

Abstract

A shock tube method is described for studying the combustion of a cloud of coal particles under pressure. Two important types of reaction are observed. First, the preflame reaction, in which particle heating rates are controlled by conduction from the gas together with the exothermal release of heat at the particle surface. This stage always precedes the second type of reaction which is characterized by a highly luminous flame. Here solid particles of less than 80 μ m and their products of volatilization appear to burn simultaneously and completely in less than 2 ms. The kinetics of the two types of reaction are analysed by means of thermal explosion theory and oxygen transport rates respectively.