苏金水,卓相宇,张丽芳,等. 低浓度铵盐高效精准脱除新疆准东煤中钠[J]. 煤炭学报,2024,49(S1):1−9. doi: 10.13225/j.cnki.jccs.2023.0379
引用本文: 苏金水,卓相宇,张丽芳,等. 低浓度铵盐高效精准脱除新疆准东煤中钠[J]. 煤炭学报,2024,49(S1):1−9. doi: 10.13225/j.cnki.jccs.2023.0379
SU Jinshui,ZHUO Xiangyu,ZHANG Lifang,et al. Efficient and accurate removal of Na from Xinjiang Zhundong coal with low concentration ammonium salts[J]. Journal of China Coal Society,2024,49(S1):1−9. doi: 10.13225/j.cnki.jccs.2023.0379
Citation: SU Jinshui,ZHUO Xiangyu,ZHANG Lifang,et al. Efficient and accurate removal of Na from Xinjiang Zhundong coal with low concentration ammonium salts[J]. Journal of China Coal Society,2024,49(S1):1−9. doi: 10.13225/j.cnki.jccs.2023.0379

低浓度铵盐高效精准脱除新疆准东煤中钠

Efficient and accurate removal of Na from Xinjiang Zhundong coal with low concentration ammonium salts

  • 摘要: 新疆准东地区拥有丰富的高钠煤资源,它们是优质动力煤和化工原料用煤,但钠质量分数高会导致燃烧和气化过程中设备污染和积灰结渣严重,从而严重限制了准东煤的大规模高效利用,钠的高效经济绿色脱除对准东煤的清洁利用具有重要意义。详细研究了系列低浓度铵盐对准东低阶高钠煤中钠的脱除规律及机制,结果表明:去离子水仅能脱除约52%的煤中钠,当使用0.006 mol/L的低浓度NH4Ac、NH4Cl、(NH4)2SO4、NH4NO3、TMACl等各类铵盐时,总钠和有机钠脱除率可达90%~97%和80%~95%。煤灰中Na2O质量分数从原煤的6.21%和水处理煤的2.77%显著降低至低浓度铵盐处理煤的0.27%~0.81%。在上述各类铵盐中,NH4Ac脱钠效果最佳。脱钠药剂中阳离子对有机钠的脱除起着重要作用,其脱钠量顺序为H+ > NH4+ > TMA+,这归因于小的阳离子更有利于进入煤孔隙和有机质本体,与有机钠进行离子交换。铵盐能够脱除煤中各类羧酸钠是常规的离子交换机理,但酚钠的脱除机理可能涉及离子交换、酚铵盐的复分解及NH4+的水解等反应。提高温度、延长时间和增加铵盐量均能显著提高煤中总钠、水溶性无机钠和有机钠等各类形态钠的脱除量。建立了不同铵盐添加量与煤中总钠和有机钠脱除量之间的正相关关系,如对于NH4Ac为y(total Na) = 12479x(ammonium amount) + 2200, y(organic Na) = 12394x(ammonium amount) + 136。该准东煤满足国家燃煤标准(Na2O < 2.0%,以灰分计质量分数),需脱除约70%的总钠,每吨准东煤需添加约4.26 kg NH4Ac。

     

    Abstract: The Zhundong region in Xinjiang has abundant high-Na coal resource, which can be used as high-quality fuel and chemical raw material. However, the high-Na content can lead to severe equipment pollution and ash slagging during combustion and gasification processes, thereby significantly restricting its large-scale and efficient utilization. The efficient, economical, and environmental friendly removal of Na is of great significance for the clean utilization of the Zhundong coal. This study investigates the rule and mechanism of Na removal from low-rank high-Na coal in the Zhundong region using a series of low-concentration ammonium salts. The results show that the deionized water (DI) can only remove about 52% of Na in the coal. When some low-concentration ammonium salts such as NH4Ac, NH4Cl, (NH4)2SO4, NH4NO3 and TMACl with a concentration of 0.006 mol/L are used, the total Na removal rate and organic Na removal rate can reach to 90%~97% and 80%~95%, respectively. The Na2O mass fraction in coal ash is significantly reduced from 6.21% in raw coal, 2.77% in water-treated coal and 0.27%~0.81% in coal treated with low-concentration ammonium salts. Among the various ammonium salts mentioned above, the NH4Ac shows the best Na removal effect. The size of the cation in the Na removal agent plays an important role in the removal of organic Na, and the Na removal capacity follows the order: H+ > NH4+ > TMA+, which is due to the smaller cations are more favorable for entering coal pores and interacting with organic Na through ion exchange. Ammonium salts can remove various types of Na carboxylates through conventional ion exchange mechanisms, but the removal mechanism of phenolic Na may involve ion exchange, complex decomposition of phenolic ammonium salts, and hydrolysis of NH4+. Increasing the temperature, prolonging the time, and increasing the amount of ammonium salts significantly enhance the removal of total Na, water-soluble inorganic Na, and organic Na in coal. A correlation between the amount of ammonium salt added and the removal of total Na and organic Na in coal has been established. For NH4Ac, the correlation is as follows: y(total Na) = 12479x(ammonium amount) + 2200, y(organic Na) = 12394x(ammonium amount) + 136. In order to meet the national coal combustion standard (Na2O < 2.0%, mass fraction by ash) for the Zhundong coal, about 70% of the total Na needs to be removed, about 4.26 kg of NH4Ac should be added per ton of the Zhundong coal.

     

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