Characteristics of the ignition of organic coal–water fuels for boiler installations

The ignition processes of organic coal–water fuels (OCWFs) in the flow of a heated oxidant (temperature, 700–1000 K; velocity, 0.5–5 m/s) were studied. The experiments were carried out with the small single drops of OCWFs (radii, 0.2–0.5 mm), which correspond to the injection devices of typical boiler installations. The component base of the test composition fuels included B2 brown coal, typical waste coals (the filter cakes of G and D coals), spent motor and transformer oils, and petroleum residue. The influence of the component composition (the properties and concentrations of solid and liquid combustible components) on the characteristics of the initiation of the combustion of single OCWF drops was found. The dependences of the delay times of ignition and complete combustion on the temperature of an oxidant and on the drop sizes of OCWFs were determined. It was established that, at maximum oxidant temperatures (above 900 K) and minimum drop sizes (smaller than 300 μm), difference between the integral characteristics of ignition was sufficiently small (smaller than 10%) for the fuels prepared from components with substantially different properties.