Stabilization of coal dust-air mixture by bluff bodies

Abstract

The process of flame stabilization by means of bluff bodies has been studied theoretically and experimentally for coal dust-air mixtures. The experiments were carried out on a test stand that provided variation of the parameters and visualization of the process. In the first stage the tests were of a preliminary character, their object being to reveal the essential factors influencing the stabilization of the flame and to explain its mechanism. On this basis, a physical model and a mathematical model of the process were established. The former explains the mechanism of stabilization and the latter enables its theoretical range to be determined. It has been found that the range of stable combustion is influenced primarily by the rate of emission of volatiles from the coal dust within the layer flowing past the recirculation zone. The size of the stabilizer, the fuel and oxidizer concentrations, and their initial temperatures were also found to be important, as was already known from the theory of stabilization of homogeneous gaseous mixtures. The theoretical results for the stability ranges were confirmed experimentally.