Co-firing coal and biomass has the potential to reduce GHG emissions. However, high levels of alkali and alkaline metals in biomass ash can bring additional issues to the operation of coal-fired boilers. This study investigates the effects of ilmenite as the bed material on CO and NO_x emissions and combustion efficiency of a coal and biomass blend, and the agglomeration tendency of the bed material with a pilot-scale (30 kWth) bubbling fluidised bed combustor. The experiments were carried out at 900 °C using a bituminous coal blended with wheat straw pellets at 40 wt% as the fuel and silica sand as the baseline bed material. Samples of agglomerates collected from the combustor and cyclone ash were characterised by SEM-EDS, XRD, and XRF. The results revealed that ilmenite could reduce the level of excess air required to achieve complete combustion due to lower CO emissions and less efficiency loss compared to silica sand. However, ilmenite increased NO_x emissions. Furthermore, the characterisation of the obtained agglomerates and cyclone ash showed that ilmenite could hinder the K-rich molten substance attachment to the bed material, leading to significantly smaller agglomerates and hence less tendency towards defluidisation in comparison to silica sand.

煤和生物质混烧具有减少温室气体排放的潜力。然而，生物质灰中的高浓度碱金属和碱金属会给燃煤锅炉的运行带来额外的问题。本研究调查了钛铁矿作为床层材料对 CO 和 NO _{x 的影响}煤和生物质混合物的排放和燃烧效率，以及具有中试规模（30 千瓦时）鼓泡流化床燃烧器的床材料的结块趋势。实验在 900 °C 下进行，使用与 40 wt% 小麦秸秆颗粒混合的烟煤作为燃料，硅砂作为基线床材料。通过 SEM-EDS、XRD 和 XRF 对从燃烧器和旋风灰烬中收集的附聚物样品进行表征。结果表明，与硅砂相比，钛铁矿可以降低实现完全燃烧所需的过量空气水平，因为它具有更低的 CO 排放和更低的效率损失。然而，钛铁矿增加NO _X排放。此外，获得的附聚物和旋风灰分的表征表明，钛铁矿可以阻碍富含钾的熔融物质附着在床层材料上，导致附聚物显着更小，因此与硅砂相比更不易流化。