褐煤物化结构对水分复吸的影响

Influence of lignite physical and chemical structure on moisture re-absorption

阐述了褐煤中水分的赋存形态及其在受热过程中的转化行为。分析了不同提质干燥过程中褐煤物化结构的变化,探讨了褐煤物化结构与水分脱除及复吸的关系。结果表明:褐煤表面丰富的孔结构和大量亲水性含氧官能团是其水分较高的主要原因。干燥提质过程中,孔结构坍塌和交联反应的剧烈程度对于抑制复吸非常重要。加热过程中褐煤表面活性含氧官能团的数量、形成和分解行为直接影响褐煤的持水和吸氧能力,含氧官能团的分解会使煤的疏水性增加,自燃倾向性降低。最后说明褐煤提质的关键是水分的高效安全脱除,脱水煤表面氧化和水分复吸的抑制,并提出了抑制提质褐煤复吸水分的可能途径是依据不同组成、结构褐煤的水分赋存和脱除行为,针对性地改善干燥操作条件,调节样品孔径分布、比表面积和表面含氧官能团的存在形态及数量。

Introduce the existing forms of moisture in lignite and its conversion in heating process. Analyse the physical and chemical structure changes of lignite during different upgrading drying processes. Investigate the influence of lignite structure on its moisture removal and re-absorption. The results show that, abundant pore structure and hydrophilie oxygen-containing functional groups on lignite surface lead to high moisture in lignite. During upgrading drying process, pore structure collapse and cross-linking reaction play an important part in restraining moisture re-absorption. The number of functional oxygen-containing groups on lignite surface and their formation and decomposition directly influence the moisture and oxygen holding capacity of lignite. Their decomposition ean enhance the hydrophobieity and weaken spontaneous combustion. The key to lignite upgrading is the efficient removal of moisture and restraining of dehydrated lignite oxidation and moisture re-absorption. To better restrain moisture re-absorption, it can improve upgrading condition ,adjust pore-size distribution, surface area as well as forms and amounts of oxygen-containing functional groups based on the moisture existing forms and its removing performance.