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摘要: 以金鸡滩煤为原料, 沙子为添加剂, 研究不同比例添加剂下高钙高铁煤灰熔融及黏温特性变化; 通过XRD、高温热台显微镜与扫描电镜-能谱等分析方法研究矿物质转变对其灰熔融及黏温特性影响。结果表明, 煤灰熔点随添加剂量的增加先降低后升高, 辉石类低温共熔物生成是其降低的主要原因; 原煤熔渣黏度波动与钙铝黄长石生成有关, 而含铁矿物质析出导致其黏度迅速增加; 添加沙子后, 煤灰熔渣临界温度显著下降, 熔渣由结晶渣向玻璃渣转变。原煤熔渣中Fe、Ca元素分布不均匀, 添加沙子后均匀程度明显改善, 与黏温曲线测试结果吻合。实验结果表明, 沙子是改善高钙高铁煤黏温特性的一种有效添加剂。Abstract: Jinjitan coal and sand were respectively chosen as raw material and additive. Under the different proportion of additive, ash fusion and viscosity behavior of coal ash with high contents of Fe and Ca were studied. X-ray diffraction (XRD), high-temperature stage microscope (HTSM) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) were applied to investigate effect of mineral transformation on ash fusion and viscosity behavior of coal ash. The results show that ash fusion temperature decreases at first and then increases with the rising content of additive, and formation of low temperature eutectic augite is the main reason for the lower ash fusion temperature. The viscosity fluctuation is related to the formation of gehlenite, and the precipitation of iron-bearing minerals causes significant increase of viscosity. The temperature of critical viscosity (tcv) of coal ash slag drops dramatically and the slag type transforms from crystal slag to glass slag with addition of sand. Distribution of Fe and Ca shows obvious different in raw coal slag, but additive makes it become more uniform, which is in agreement with the viscosity curve. Moreover, the industrial results prove that sand is an effective additive to improve the viscosity behavior of coal ash with high content of Fe and Ca.
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图 3 煤灰熔融温度随添加剂的变化
Figure 3 Variation of ash fusion temperature with different ratio additive
图 4 添加不同比例的沙子金鸡滩煤煤灰黏温特性曲线
Figure 4 Viscosity-temperature curves of JJTC ash with different sand ratio
图 5 熔渣与不同温度下灰样的XRD谱图
Figure 5 XRD spectra of slags and ash in different temperatures
(a): 1 100 ℃; (b): 1 200 ℃; (c): 1 300 ℃; (d): slags G-Gehlenite-Ca2Al2SiO4; H-Hercynite-Fe (2+) Al2O4; D-Diopside-Ca (Al, Mg)(Si, Al)2O6; S-Spinel Ferrian-Mg (Fe, Al)2O4; A-Aegirine-NaFe (3+)(SiO3)2; M-Magnetite-Fe3O4; W-Wollastonite-CaSiO3; Q-Quartz-SiO2; He-Hematite-Fe2O3
图 6 灰渣熔融过程
Figure 6 Fusion progress of slags
(a): coal ash salg; (b): slag of ash+20%sand; (c): slag of ash+40%sand
图 7 熔渣扫描电镜照片(BSE)
Figure 7 SEM images of slags (BSE)
(a): coal ash salg; (b): slag of ash +20% sand; (c): slag of ash +40% sand
表 1 金鸡滩煤的元素分析与工业分析
Table 1 Proximate and ultimate analysis of Jinjitan coal (JJTC)
Sample Proximate analysis wad/% Ultimate analysis wad /% M A V FC C H O N S JJTC 4.53 5.76 33.80 55.91 74.10 5.20 13.48 0.91 0.55 
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表 2 煤灰熔融温度
Table 2 Ash fusion temperature of coal ash
Sample Ash fusion temperature (weak reducing atmosphere) t/℃ DT ST HT FT JJTC 1 272 1 289 1 294 1 300
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表 3 煤灰与添加剂的化学组成
Table 3 Chemical composition of coal ash and additive
Sample Chemical composition w/% SiO2 Al2O3 CaO Fe2O3 SO3 MgO K2O TiO2 Na2O others Coal ash 29.48 18.18 23.73 14.76 7.38 2.86 0.13 0.45 2.12 0.91 Additive 77.20 11.85 - - - 9.00 - - - 1.95
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表 4 添加不同比例的沙子后煤灰主要组分变化
Table 4 Change of main composition of coal ash with different sand ratio
Sand/coal ash w/% Content w/% S/A SiO2 Al2O3 CaO Fe2O3 0 29.48 18.18 23.73 14.76 1.62 10 33.83 17.60 20.66 13.42 1.92 20 37.44 17.13 18.94 12.30 2.19 40 43.12 16.37 16.24 10.54 2.63 60 47.38 15.81 14.21 9.23 3.00 80 50.69 15.37 12.63 8.20 3.30
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表 5 添加不同沙子金鸡滩煤灰临界温度与参考温度
Table 5 t25 and tcv of JJTC ash with different sand ratio
Sample Ash Ash+20%sand Ash+40%sand tcv/℃ 1 435 1 187 1 152 t25/℃ 1 396 1 191 1 152
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表 6 熔渣中元素分布
Table 6 Distribution of elements in slags
Test point Elemental analysis w/% O Na Mg Al Si P S K Ca Fe a (bright) 18.09 2.75 1.79 18.60 0.76 2.98 1.00 0.65 1.04 52.33 a (dark) 31.19 2.21 0.68 19.57 11.30 3.26 1.16 0.85 26.44 3.35 b 38.65 2.99 0.64 12.52 17.91 2.16 0.50 1.03 17.81 5.79 c 34.60 4.94 1.97 12.39 19.31 2.65 1.09 2.01 14.48 6.56
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表 7 气化炉操作条件与气化结果
Table 7 Gasifier operating conditions and gasification results
Operating temperature t/℃ Operating pressure p/MPa Residual carbon content w/% Carbon conversion x/% (H2+CO) φ/% fine slags coarse slags 1 350 4.0 20.28 2.87 99.35 81.90
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