384 / 2018-12-20 12:10:50

Experimental Investigation on Combustion Performance of Dry Coal Slime Powders in a Pilot Circulating Fluidized Bed

dry coal slime powder, Circulating Fluidized Bed Boiler, combustion performance

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Combustion in fluidized bed or suspension furnace is the dominant option for utilizing the coal-washing byproduct – coal slime. However, the high water content （>20%）of the coal slime reduces its heat content at received basis, and it also increases the opacity of the flue gas. With the advances recently made in the coal slime drying technology, the combustion of dry coal slime powders becomes possible and necessary. In this paper, extensive experiments on hydrodynamic and combustion characteristics of dry coal slime powders were conducted in a 4 MW pilot circulating fluidized bed system. A mathematic model was developed based on the axial solid concentration distributions, and the influences of fluidizing gas velocity, fuel feeding rate and the secondary air entry position on the bed temperature profile, thermal capacity as well as gaseous emissions were examined. It is believed that the experimental data and the underlaying mechanisms presented in this study would provide insightful basis for developing and promoting combustion of dry coal slime powders in circulating fluidized bed boilers.