Droplet ignition of coal–water slurries prepared from typical coal- and oil-processing wastes

Abstract

The requirements for stable ignition (and subsequent combustion) of fuel suspensions prepared from typical coal- and oil-processing wastes are studied experimentally. Attention focuses on the differences between the ignition characteristics of coal–water slurries (containing petrochemicals) obtained on the basis of filter cakes containing T, K, SS, Zh, D, and G coal. To eliminate the influence of the droplet holder (traditionally, thermocouple junctions, ceramic rods, or metal wire) on the ignition characteristics of the fuel droplet, the experiments employ a special model combustion chamber and a device for introducing a single drop of suspension. The ignition time and the minimum temperature of stable ignition of a droplet of coal–water slurries suspended in an oxidant flux are established. The influence of the following factors on the initiation of fuel combustion is determined: the oxidant temperature, the droplet size, the size of the coal dust, and the properties and concentrations of the components. The compositions of the coal–water slurries corresponding to optimal ignition (minimum inertia) are identified.