Physicochemical properties of coal char during pressurized pyrolysis and the mineral transformations of coal ash during pressurized O₂/N₂ and O₂/CO₂ combustion were investigated by a pressurized tube furnace with Fourier transform infrared spectroscopy and X-ray diffraction analysis. The results indicated that as the pyrolysis pressure increased, the decompositions of the aromatic ring structure and the hydroxyl hydrogen bonds of char were enhanced and the aromatic ring transformed to the low-substituted single ring. Meanwhile, the aliphatic chain and carboxyl group in the char shortened at elevated pressures. Furthermore, pressurized pyrolysis increased the degree of graphitization of the char, which further influenced the microcrystalline parameters of char. During the pyrolysis process, the decompositions of some low-temperature minerals in the char were inhibited by the elevated pressure. In addition, the effect of the furnace temperature on the mineral transformations of char was more significant than the effect of the furnace pressure. Compared to what observed at atmospheric pressure, the primary minerals in the coal ash remained the same at elevated pressure, but their relative contents changed to some extent. And, the influence of the furnace pressure on the transformations of minerals in the ash was mainly affected by the combustion temperatures of different ignition mechanisms at different pressures. Compared to the O₂/N₂ mixture, the decompositions of low-temperature minerals and the formations of high-temperature minerals were restrained due to the relatively low combustion temperature in the O₂/CO₂ mixture. And, the furnace temperature instead of the furnace pressure was the primary factor which influenced the mineral transformations of ash.

中文翻译：

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加压热解过程中煤焦的理化性质及加压O2/N2和O2/CO2燃烧过程中煤灰的矿物转化研究

加压热解过程中煤焦的理化性质和加压O ₂ /N ₂和O ₂ /CO ₂过程中煤灰的矿物转化燃烧通过带傅里叶变换红外光谱和 X 射线衍射分析的加压管式炉进行研究。结果表明，随着热解压力的增加，芳香环结构和焦炭羟基氢键的分解增强，芳香环转变为低取代单环。同时，炭中的脂肪链和羧基在升高的压力下缩短。此外，加压热解增加了炭的石墨化程度，这进一步影响了炭的微晶参数。在热解过程中，炭中某些低温矿物的分解受到高压的抑制。此外，炉温对炭矿物转化的影响比炉压的影响更显着。与常压下观察到的相比，煤灰中的主要矿物质在高压下保持不变，但它们的相对含量有所变化。并且，炉压对灰中矿物质转化的影响主要受不同点火机制在不同压力下燃烧温度的影响。与奥相比 炉压对灰中矿物质转化的影响主要受不同点火机制在不同压力下燃烧温度的影响。与奥相比 炉压对灰中矿物质转化的影响主要受不同点火机制在不同压力下燃烧温度的影响。与奥相比₂ /N ₂混合物中，由于O ₂ /CO ₂混合物的燃烧温度较低，低温矿物的分解和高温矿物的形成受到抑制。并且，炉温而不是炉压是影响灰分矿物转化的主要因素。