Distribution characteristics of alkali emission between gas and solid phase during Zhundong coal combustion
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摘要: 采用萃取法测量了准东煤中不同赋存形式碱金属(Na、K) 的含量, Na以水溶性为主, 占59%, K主要以不可溶的硅铝酸盐存在, 占总量的53%.进行准东煤燃烧实验, 燃烧温度为400-950℃, 研究了高碱准东煤燃烧过程中碱金属在气、固两相中的分布.结果表明, 随温度升高, 煤粉成灰率降低, Na从煤中不断析出进入气相; 而K在400℃时, 气相中的含量低于固相, 温度高于500℃, 气相中的含量超过固相并基本保持不变; 碱金属在固相中出现富集现象, 灰中碱金属的质量分数随温度升高; 气相中的Na主要来源于水溶性, 析出的K除了可溶性外, 还有部分来自不可溶的硅铝酸盐; 根据国标灰的XRD分析, 煤中碱金属在燃烧过程中会与SiO2和Al2O3反应生成钠长石和霞石等低熔点化合物.Abstract: The sequence extraction method was used to analyze the content of alkali metals in different modes of occurrence in Zhundong coal. Most sodium in the coal is water-soluble one, accouting for 59%, while potassium exists mainly in the form of non-soluble aluminosilicates, accounting for 53%. The combustion experiments of Zhundong coal at the temperature ranging from 400 to 950℃ were carried out to study the distribution characteristics of alkali emission between the gas and the solid phase. The results show that the ash yield decreases with the increase in temperature. Sodium releases continuously from coal into the gas phase; However, the content of potassium in the gas phase is lower than that in the solid phase at 400℃, while the content of potassium in gas exceeds that in solid and basically remains the same when the temperature is higher than 500℃. The enrichment of alkali metals in solid occurs and increases with temperature. Moreover, the sodium in the gas phase mainly originates from water-soluble one, and potassium not only releases from soluble ones, but also from non-soluble aluminosilicates. According to the result of XRD, alkali metals will react with SiO2 and Al2O3 to form low-melting-point albite and nepheline.
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Key words:
- Zhundong coal /
- alkali metals /
- emission
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表 1 准东煤的工业分析与元素分析
Table 1 Proximate and ultimate analysis of Zhundong coal
Proximate analysis wad/% Ultimate analysis wad/% Qnet, ar
/(J·g-1)M A V FC C H N St O 8.43 8.53 27.36 55.68 67.09 3.34 0.32 0.39 11.9 19 588.97 表 2 准东煤的灰成分分析
Table 2 Ash composition analysis of Zhundong coal
Content w/% SiO2 Al2O3 Fe2O3 CaO MgO K2O Na2O TiO2 SO3 P2O5 46.64 10.16 6.89 13.31 6.53 0.74 3.54 0.39 10.48 0.29 -
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