Effect of NaCl vapor concentration on sodium⁃capturing performance and sintering temperature of coal ash
ZHANG Shouyu,XU Zihang,HUANG Dongdong,LANG Sen,LIU Simeng, YANG Jifan,ZHOU Yi,HU Nan,WU Yuxin
新疆的高钠煤是一种开采成本低、灰分低、含硫量低的优质燃料,但较高的钠含量导致其在 燃烧利用的过程中易出现沾污结渣等现象,严重阻碍了高钠煤的开发利用。 以 2 种高钠煤(五彩 湾煤(WCW)、哈密煤(HM))和 1 种低钠煤(平朔煤(PS))作为实验对象,在 900 °C下燃烧制灰,并 将所制煤灰置于 38%、51%和 76%的 NaCl 蒸气下进行钠捕获实验,使用 ICP-OES 测得钠捕获前后 煤灰的钠含量,采用 XRD 分析钠捕获前后煤灰中矿物质的变化,采用压降法测量钠捕获前后煤灰 的烧结温度,深入探究不同 NaCl 蒸气体积分数下煤灰烧结特性的衍变规律。 结果表明:在 3 种 NaCl 蒸气体积分数下,3 种煤灰样品中 PS 煤灰的钠捕获量最大,HM 煤灰次之,WCW 煤灰最 低。 Si、Al 能增强煤灰的钠捕获性能,而 Ca 则会与 Si、Al 发生反应,从而抑制 Si、Al 对 NaCl 蒸气的 化学固定,不利于煤灰的钠捕获。 随 NaCl 蒸气体积分数升高,钠捕获量增大,煤灰的烧结温度降低 幅度与其钠捕获量呈正相关。 HM、WCW 煤灰烧结温度降低幅度均大于 PS 煤灰,一方面是由 于 HM 和 WCW 煤灰固钠后生成的含钠化合物的熔点低于 PS 煤灰,另一方面 NaCl 蒸气体积分数 升高促进了低熔点含钠化合物的生成。 PS 煤灰在 900 °C 下尚未发生烧结,其结构疏松、内部孔隙 多,与 NaCl 蒸气反应完全程度相对较高,其烧结温度受 NaCl 蒸气体积分数影响最小。
Zhundong coal in Xinjiang is a kind of high⁃quality fuel with low mining cost, low ash yield and sulfur con⁃ tent, but high sodium content leads to the fouling and slagging during its combustion process, which seriously hin⁃ ders the further utilization of the sodium⁃rich coal. In this study, two kinds of sodium⁃rich coals, the Wucaiwan coal (WCW) and the Hami coal (HM), and one low sodium⁃content coal, the Pingshuo coal (PS), were burned into ash at 900 °C , and the sodium capture experiments of the coal ashes were conducted in the atmosphere of the NaCl vapor with 38%, 51% and 76% concentration. The sodium content in the coal ash before and after the so⁃ dium capture experiment was measured by the ICP-OES analyzer, and the mineral changes in the coal ash samples were analyzed by XRD. Finally, the pressure drop method was used to determine the sintering temperature of the coal ash sample, and then the effect of the sodium vapor concentration on the sintering characteristics of the coal ash was explored. The results show that in the range of the employed NaCl vapor concentrations, in terms of the sodi⁃ um⁃capturing amount, the PS coal ash is the highest, the HM coal ash is the second, and the WCW coal ash is the lowest. Silicon and aluminum in the coal ash samples can enhance its sodium⁃capturing performance, while calcium in the coal ash will react with the silicon and aluminum contained in the minerals, and thus result in the decrease in the chemical fixation capability of the silicon and aluminum for the sodium contained vapor, which is not conducive to the sodium capture process of the coal ash samples. With the increase of NaCl vapor concentration, the sodium⁃capture amount increases, and the decrease in the sintering temperature of the coal ash is positively correlated with the sodium⁃capturing amount. The decrease in the sintering temperature of the HM and the WCW coal ashes is greater than that of the PS coal ash because the melting point of the sodium⁃containing compounds produced by the chemical fixed sodium of the HM and the WCW coal ashes is lower than that of the PS coal ash and the forming reaction of low melting point sodium⁃containing compounds is promoted by the increasing the NaCl vapor concentration. In addition, the sintering behavior of the PS coal ash with loose structure and rich internal pores was not observed at 900 °C , thus the reaction degree of the ash with the NaCl vapor was relatively high, and its sinte⁃ ring temperature of the resulted ash was less affected by the NaCl vapor concentration.
sodium⁃rich coal;sodium capture;combustion;coal ash;sintering temperature
1 实验
1.1 实验样品制备
1.2 实验装置及步骤
1.3 分析方法
2 实验结果与分析
2.1 不同煤灰的钠捕获性能
2.2 钠捕获前后煤灰中矿物质的衍变
2.3 煤灰固钠后烧结温度的衍变
3 结论
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会