逐级萃取对高钠煤灰钠捕获性能的影响
Effect of sequential extraction on sodium capture capability of sodium⁃rich coal ash
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摘要: 新疆高钠煤储量丰富、燃烧性能好，具有极大的开发利用潜力。 但由于该煤种钠含量较高， 在燃用过程中极易造成锅炉受热面沾污结渣等问题，严重限制了其开发利用。 以五彩湾煤为研究 对象，进行水-醋酸铵溶液-HCl 溶液逐级萃取并燃烧制灰，再进行钠捕获实验。 利用电感耦合等 离子原子发射光谱(ICP-OES)分析各萃取等级煤灰在不同反应温度下的钠捕获量，结合 X-射线 衍射分析研究逐级萃取对五彩湾煤灰钠捕获性能的影响。 同时，以哈密煤为对比样品，并参照哈密 煤灰分组成向五彩湾煤中掺入 SiO2 和 Al2 O3 添加剂，探究硅、铝含量对五彩湾煤灰钠捕获性能的影 响。 结果表明:逐级萃取可降低五彩湾煤灰中的钙含量，从而抑制硅灰石(CaSi3O9 )、铝酸钙 (Ca12Al14O33)等含钙物质的生成，有利于煤灰中硅、铝物质对钠的捕获。 经水、醋酸铵溶液萃取后 制备的五彩湾煤灰(WCW-A2-900)在 900 °C反应温度下的钠捕获量最高，较原煤灰提升了125.23%。 随着钠捕获反应温度的升高，煤灰中的硅、铝物质与钠蒸气生成稳定的硅铝酸盐固定在煤灰中，表现 为钠捕获性能增强。 但当反应温度超过 900 °C 时，WCW-A2-900 与 WCW-A3-900 的钠捕获量由于 其物理吸附性能的下降而明显降低，但仍高于原煤煤灰。 硅、铝矿物质含量的上升有助于增强 WCW- 900 的钠捕获性能，但由于 WCWH -900 中的钙含量比 HM-900 高，因而其钠捕获性能提高有限。Abstract: The sodium⁃rich coal in Xinjiang is abundant and has good combustion performance. However， the high so⁃ dium content in coal results in fouling and slagging on the convective heating surface of boiler， which seriously re⁃ stricts its development and utilization. In this study， the Wucaiwan coal (WCW) was extracted sequentially by water/ ammonium acetate solution/HCl solution， and then was burnt into ash. The sodium capture capability of the WCW coal ash samples was determined and then the effect of the sequential extraction on the sodium capture perform⁃ ances of the ash samples was investigated. Meanwhile， according to the composition of the Hami (HM) coal ash， SiO2 and Al2 O3 were added into the WCW coal， and the effect of SiO2 and Al2 O3 additions on the sodium capture performance of the ash sample was analyzed. The results show that the sequential extraction can remove calcium from the WCW coal， which restrains the formation of calcium⁃containing materials such as wolwolite ( CaSi3 O9 ) and calcium aluminate (Ca12Al14O33)， and thus the capture reaction of the sodium by silicon and aluminum materials in the coal ash was promoted. The ash sample (WCW-A2-900) prepared from water/ammonium acetate solution ex⁃ tracted the WCW coal at the sodium capture temperature of 900 °C has the highest sodium capture amount， which is 125.23% higher than raw coal ash. With the increasing sodium capture temperature， the sodium capture performance of the WCW coal ash is enhanced due to the formation of the stable aluminosilicates from the silicon and aluminum in coal ash with sodium vapor. When the reaction temperature exceeds 900 °C， the sodium capture amount of the WCW- A2 - 900 and the WCW - A3 - 900， which is still higher than that of the WCW coal ash， decreased obviously due to their decreasing physical adsorption capability. The additions of silicon and aluminum matter can en⁃ hance the sodium capture performance of the WCW-900， but the improvement is limited because the calcium content of the resulted WCWH coal is still higher than that of the HM coal.
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