Abstract To initiate the elucidation of deposit formation during the iron-ore pelletization process, a comprehensive set of experiments was conducted in a 0.4 MW pilot-scale pulverized-coal-fired furnace where three different scenarios were considered as follows; Case 1 (reference case): Coal was combusted without the presence of pellet dust. Case 2: Natural gas was combusted together with simultaneous addition of pellet dust to the gas stream. Case 3: Coal was combusted together with the addition of pellet dust simulating the situation in the large-scale grate-kiln setup. Particles and deposits were sampled from 3 positions of different temperature via a water-cooled sampling probe. Three distinct fragmentation modes were identified based on the aerodynamic particle diameter (Dp). The fine mode: Particles with 0.03 10 μm). A transition from a bimodal PSD (particle size distribution) to a trimodal PSD was observed when pellet dust was added (Case 3) and consequently the elemental bulk composition of the abovementioned modes was changed. The most extensive interaction between pellet dust and coal-ash particles was observed in the coarse mode where a significant number of coal ash globules were found attached to the surface of the hematite particles. The morphology of the sharp-edged hematite particles was changed to smooth-edged round particles which proved that hematite particles must have interacted with the surrounding aluminosilicate glassy phase originating from the coal ash. The short-term deposits collected during coal combustion (Case 1) were highly porous in contrast to the high degree of sintering observed in the experiments with pellet dust addition (Case 3) which is attributed to the dissolution of hematite particles in the aluminosilicate glassy phase. The results suggest that pellet dust itself (Case 2) has low slagging tendency, independent of temperature. However, when coal-ash is present (Case 3), auxiliary phases are added such that tenacious particles are formed and slagging occurs.

中文翻译：

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破碎的铁矿球团粉尘对中试煤粉燃烧炉中沉积物形成的影响。第 I 部分：工艺气体颗粒和沉积物的表征

摘要 为了阐明铁矿石球团过程中矿床的形成，在 0.4 MW 中试规模的煤粉炉中进行了一系列综合实验，其中考虑了以下三种不同的情况：案例 1（参考案例）：煤在不存在颗粒粉尘的情况下燃烧。案例 2：天然气与同时向气流中添加颗粒粉尘一起燃烧。案例 3：煤与添加球团粉尘一起燃烧，模拟大型炉排窑设置中的情况。通过水冷采样探头从 3 个不同温度的位置对颗粒和沉积物进行采样。根据空气动力学粒径 (Dp) 确定了三种不同的碎裂模式。精细模式：颗粒大小为 0.03 10 μm）。当添加颗粒粉尘（案例 3）时，观察到从双峰 PSD（粒度分布）到三峰 PSD 的转变，因此上述模式的元素整体组成发生了变化。在粗模式下观察到球团粉尘和煤灰颗粒之间最广泛的相互作用，其中发现大量煤灰球附着在赤铁矿颗粒的表面。锋利边缘的赤铁矿颗粒的形态变为边缘光滑的圆形颗粒，这证明赤铁矿颗粒必须与周围源自煤灰的铝硅酸盐玻璃相相互作用。煤燃烧期间收集的短期沉积物（案例 1）是高度多孔的，而在添加颗粒粉尘的实验（案例 3）中观察到的高度烧结是由于赤铁矿颗粒溶解在铝硅酸盐玻璃相中所致. 结果表明，球团粉尘本身（案例 2）具有低结渣倾向，与温度无关。然而，当存在煤灰时（情况 3），会添加辅助相，从而形成坚韧的颗粒并产生结渣。