Burnout rates of fuel slurries containing petrochemicals, coals and coal processing waste

The purpose of this study is a comparative analysis of droplet burnout rates of coal-water slurries with typical composition (based on coal dust) and new compositions of waste-derived slurries (based on coal flotation waste and used petroleum oil). The main variable parameters included the temperature in the combustion chamber (700–900°С), the initial droplet diameter (0.8–2.2 mm), the particle size (40–250 μm) and the component composition of slurry. We tested the effect of these parameters on three main characteristics: ignition delay time, burnout time, and burnout rate). The dominant impact of petroleum oil on ignition delay times and burnout rates of fuel slurry droplets was found. These parameters can change 2- or 3-fold with the addition of as little as 15–25% of used turbine oil. It was established that the ultra-grinding of coal dust is impractical to increase the burnout rate of a slurry droplet. The burnout rates of fuel slurries based on coal dust and coal processing waste are almost identical under adequate conditions. Also, the burnout rates of a coal-water slurry containing petrochemicals, in contrast to those of coal-water slurry, grow nonlinearly as the droplet size increases. In the conditions under study, the investigated characteristics may change several times. This result shows ample opportunities for adjusting combustion systems to the required conditions and a wide range of slurry compositions.