The mixig characteristics of the particles, the combustion behavior and the combustibility of low grade anthracite coal in the fluidized bed were determined.
A model, which assumed the main combustion zone located at the upper part of the bed, was proposed and compared with experiments. The mixing of the particles was experimentally studied by employing an impulse tracer technique both for hot combusting bed and for cold bed. Also, the combustion zone was experimentally confirmed by analyzing the temperature changes in the bed after injecting a small amount coal particles to the hot ash fluidized bed.
The experimental results on the mixing in the combusting bed were considerably different from those in the cold bed and that could be interpreted by assuming the upward stratification of burning coal particles. Through this investigation, it could be concluded that the proposed model agreed well with the experiments and that the recommendable operation conditions for combusting the low grade anthracite in the fluidized bed would be, the aspect ratio, lower than 1.5; the temperature of combustor, about 900 ℃; feeding of the coal, at the top of bed; and discharging at the bottom of the bed.