IGNITION CHARACTERISTICS OF COAL PARTICLES AND SLURRY FUEL DROPLETS UNDER CONDUCTIVE HEATING

This article presents the experimental investigation results of ignition of particles and dust of lignite coal (B2 rank, Krasnoyarsk region, Borodino deposit) as well as slurry fuel droplets (mixture of coal dust and water) based on this coal at interaction with heated surface. The studies are focused on determining the mechanisms and conditions of ignition of organic fuels (which are used in thermal power plants) at direct contact with heated surface. Conductive heat transfer is typical for actual conditions of technological processes at interaction of fuel particles or droplets with heated surfaces of power equipment at the stages of preparing components, their filtration, drying, transportation and supply to combustion chambers. For several characteristic sizes (from 1 to 5mm)of the coal particles we determined the duration of inert heating until the implementation moment of intense exothermic process in the range of heat source temperatures from 600 to 850 °Ñ. Similar results were obtained for slurry fuel droplet with characteristic size of 5 mm. The significant influence of coal particle sizes on their ignition delay times was revealed. Analysis of experimental results showed, that the process duration of ignition initiating for slurry fuel droplet considerably exceeds (more than 20 %) the similar characteristic for coal particle under the identical research conditions.