Conditions and characteristics of mixed fuel granules ignition based on coal and finely dispersed wood

Analysis of the possibility of lumber waste disposal via combustion in a mixture with coal has been conducted. Conditions and characteristics of pellets ignition of fuel mixtures based on coal dust and grounded wood at various mass concentrations of the components have been experimentally determined. Fuel pellets were made by cold pressing on a hydraulic press. The experiments were performed in a medium of still air heated to high (from 600 °C to 800 °C) temperatures. Record of heating processes of the researched promising for thermal power engineering granules of mixed fuels, their subsequent ignition and combustion has been conducted using a high-speed video camera (image format - 1024 × 1024 pixels, frame rate - up to 100000 per second), which provides high discretization of registration results of processes characteristic times. It has been established that an increase in the proportion of wood components in the fuel granule significantly reduces values of ignition delay times of all researched mixtures based on 2B and 3B brown coal. The limit of stable ignition of such fuels has been determined. It is shown that ignition delay times of fuel pellets with characteristic sizes up to 8 mm (height) with diameter of 8 mm even at relatively low temperatures of the combustion medium do not exceed 16 s, which illustrates the promising application of such fuels even in small-scale power engineering.