Combustion Characteristics of Oil-Impregnated Sorbent Under Different Heating Conditions

In the present study, using advanced methodologies together with analytical and experimental equipment, the ignition and combustion characteristics were determined for coal-based fuels, sorbent derived from this coal, and oil-impregnated sorbent (33.3 wt.% oil), as well as blended compositions of coal with oil-impregnated sorbent, where the mass fraction of the latter in the mixture was varied from 10 to 30%. By means of simultaneous thermal analysis, high-speed video recording under radiant-convective (500–800 °C) and radiant-conductive (600–1000 °C) heating conditions, and flue gas composition analysis, the principal combustion patterns and characteristics of the fuel set were established. The following parameters were determined: ignition temperature Ti, burnout temperature Tb, maximum Rmax and mean Rmean mass loss rates, integral combustion index S, ignition delay time td, as well as CO, CO2, and NOx concentrations in the flue gases. The experimental results indicate that the addition of 20% oil-impregnated sorbent to coal yields the maximum combustion index (3.18 min−2·°C−3) and the lowest burnout temperature (537 °C), whereas at a 10% addition, the highest burnout efficiency (98.4%) and the shortest ignition delay time in a heated air flow are achieved. Co-combustion of coal with 10–20% oil-impregnated sorbent is a promising approach for spent sorbent utilization while maintaining high energy performance of solid fuel combustion.