Abstract Alkali species in coal play an important role in mineral matter reactions during gasification. Brown coal ashes can be high in sodium (up to 20 wt%), which interacts with other minerals to significantly affect the formation of slag (liquid phase). At high temperatures, sodium in slag affects phase equilibria, liquidus temperature, and slag viscosity. We investigated phase transformations in brown coal ashes at 800–1000 °C and slags at 1200–1600 °C to study the behaviour of sodium species in the range of 3–15 wt% using X-ray powder diffraction, thermogravimetric analysis and electron probe microanalysis. Sodium species appeared in coal ashes in different forms, such as sulfates, carbonates, and alumina-silicates, resulting in different ash bulk compositions. After processing under gasification conditions, alkaline species react with other minerals and may result in the appearance of a liquid phase. In this study, the liquid-phase content of ashes generally increased with increasing sodium concentration. In slags, sodium often decreased the liquidus temperature and solids content below liquidus temperature. It results lower slag viscosity in sodium enriched slags. These findings demonstrate the importance of phase transformations in brown coal mineral matter during gasification, and the potential they have to strongly affect the required operational conditions.

中文翻译：

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钠对气化条件下褐煤灰转化及结渣行为的影响

摘要 煤中的碱类在气化过程中的矿物质反应中起重要作用。褐煤灰的钠含量可能很高（高达 20 wt%），钠与其他矿物质相互作用，显着影响炉渣（液相）的形成。在高温下，炉渣中的钠会影响相平衡、液相线温度和炉渣粘度。我们研究了 800–1000 °C 的褐煤灰和 1200–1600 °C 的炉渣中的相变，以使用 X 射线粉末衍射、热重分析和电子探针研究 3–1​​5 wt% 范围内的钠物质的行为微量分析。钠物质以不同的形式出现在煤灰中，如硫酸盐、碳酸盐和铝硅酸盐，导致不同的灰块组成。在气化条件下加工后，碱性物质与其他矿物发生反应，并可能导致液相的出现。在这项研究中，灰分的液相含量通常随着钠浓度的增加而增加。在炉渣中，钠经常降低液相线温度和低于液相线温度的固体含量。它导致富含钠的炉渣中炉渣粘度较低。这些发现证明了气化过程中褐煤矿物相变的重要性，以及它们必须强烈影响所需操作条件的潜力。它导致富含钠的炉渣中炉渣粘度较低。这些发现证明了气化过程中褐煤矿物相变的重要性，以及它们必须强烈影响所需操作条件的潜力。它导致富含钠的炉渣中炉渣粘度较低。这些发现证明了气化过程中褐煤矿物相变的重要性，以及它们必须强烈影响所需操作条件的潜力。