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摘要: 提出了煤灰不均匀熔融概念，有助于解决灰熔融性测定结果和锅炉实际情况不符的问题。采用山西晋城煤，将其粉磨到工业煤粉细度，通过浮沉分成不同密度级别子样，使用灰锥法测定其在弱还原气氛下的熔融温度，使用压降法测量其烧结温度，采用XRD、XRF、SEM-EDX等分析手段对灰样的不均匀熔融现象进行机理研究。结果表明，晋城煤灰软化温度为1501℃，而不同密度级别子样发生分化，软化温度从1292℃到高于1600℃变化；同样，晋煤煤灰烧结温度为885℃，子样的烧结温度从833到943℃变化。机理研究表明，不同密度级别子样Al2O3、Fe2O3和SO3含量发生不均匀分布，是造成煤灰熔融特性和烧结特性差异的根本原因。Abstract: According to the contradiction between ash melting theory and practice, an uneven melting theory was proposed. A typical Jincheng coal from Shanxi, China, was selected, which was ground into the particle size similar to the industrial use. It was separated into different density fractions through float and sink tests, and its chemical composition and mineral composition were analyzed with XRF and XRD, respectively. Ash fusion temperatures (AFTs) under light reducing atmosphere and the pressure-drop temperature(PDT) were tested. SEM-EDX was also employed to observe the melting behavior. It is found that the softening temperature of Jincheng coal is 1501℃, while that of its density fractions changes from 1292℃ to 1600℃. The sintering temperature changes from 833℃ to 943℃, while that of the raw coal ash was 885℃. The study of mechanism shows that the difference of melting and sintering behaviors is caused by the segregation of chemical composition in different density samples, mainly Al2O3, Fe2O3 and SO3.
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Key words:
- Jincheng coal /
- density fraction /
- ash melting behavior /
- slagging
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图 1 烧结炉结构示意图
Figure 1 Schematic diagram of sintering furnace
1: intake tube; 2: flowmeter; 3: gas mixing tank; 4: differential pressure instrument; 5: quartz tube; 6: furnace body; 7: ash pellet; 8: thermocouple
图 4 晋城煤样及其不同密度级别样品的XRD谱图
Figure 4 XRD patterns of pulverized Jincheng coal and its density fractions
K: kaolinite; C: calcite; Q: quartz; P: pyrite; Mu: muscovite
图 5 晋城煤及其不同密度级别样品的熔融温度
Figure 5 Ash melting temperatures of pulverized Jincheng coal and its density fractions
图 6 晋城煤及其不同密度样品的烧结温度
Figure 6 Sintering temperature of pulverized Jincheng coal and its density fractions
图 7 晋城煤及其不同密度级别煤灰样品1300 ℃灰样SEM照片
Figure 7 SEM pictures of pulverized Jincheng coal ashes and its density fractions under 1300 ℃
(a): JC; (b): JC1; (c): JC2; (d): JC3; (e): JC4; (f): JC5
图 8 晋城煤及其不同密度级别煤灰样品1500 ℃灰样SEM照片
Figure 8 SEM pictures of pulverized Jincheng coal ashes and their density fractions under 1500 ℃
(a): JC; (b): JC1; (c): JC2; (d): JC3; (e): JC4; (f): JC5
图 9 Al2O3/(Fe2O3+CaO+SO3)与ST关系图
Figure 9 Relationship between Al2O3/(Fe2O3+CaO+SO3) and ST
表 1 晋城煤的工业分析和元素分析
Table 1 Proximate and ultimate analysis of Jincheng coal
Proximate analysis w/% Ultimate analysis wdaf/% Qgr, ad/(kJ·kg-1) Mad Ad Vd C H N S O* 4.49 19.24 7.78 71.56 2.62 0.9 3.18 21.74 20467 *：by difference 
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表 2 粉煤密度组成和工业分析
Table 2 Density composition of pulverized Jincheng coal and their proximate analyses
Sample Density
ρ/(kg·cm-3)Content
w/%Proximate analysis w/% Mad Ad Vdaf JC1 ≤ 1.60 37.51 1.01 6.27 6.84 JC2 1.60-1.70 27.39 1.33 14.39 10.76 JC3 1.70-1.80 16.15 1.25 21.64 14.21 JC4 1.80-2.00 14.31 1.25 35.61 20.19 JC5 ＞2.00 4.64 0.81 65.65 35.72
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表 3 晋城煤及其不同密度级别样品灰化学组成
Table 3 Ash composition analyses of pulverized Jincheng coal and its density fractions
Sample Content w/% K2O Na2O SiO2 Al2O3 CaO MgO SO3 TiO2 P2O5 Fe2O3 JC 0.96 0.18 47.50 33.05 3.07 1.12 2.20 1.17 0.058 8.39 JC1 1.01 0.25 49.23 36.21 2.96 1.40 0.60 1.00 0.060 5.72 JC2 1.00 0.22 48.52 36.74 2.56 1.14 0.72 1.10 0.061 5.34 JC3 1.00 0.23 49.84 34.57 2.83 1.10 0.78 0.86 0.060 5.56 JC4 1.04 0.20 49.08 33.91 3.18 1.16 1.82 1.07 0.056 6.18 JC5 0.69 0.06 43.09 24.45 4.28 0.95 4.34 1.02 0.047 18.99
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表 4 JC和JC1的元素组成(EDX)
Table 4 Element composition of JC and JC1 (EDX)
Element content w/% C O Mg Al Si K Ca Ti Fe JC 1 8.55 41.87 0.29 28.92 14.06 0.47 1.77 0.31 3.75 2 12.31 43.03 0.35 14.84 19.2 0.55 3.1 0.51 6.11 3 13.95 49.14 0.11 18.04 14.39 0.95 1.09 0.39 1.94 4 20.16 50.7 0.09 12.4 11.26 0.82 1.07 0.69 2.81 mean value 13.74 46.19 0.21 18.55 14.73 0.7 1.76 0.48 3.65 JC1 1 25.95 40 0.58 17.23 12.22 0.67 1.25 0.67 1.43 2 11.85 49.27 0.28 19.83 12.86 0.53 1.67 1.02 2.7 3 24.36 42.51 0.8 17.92 9.38 0.61 1.97 0.37 1.6 4 14.41 46.4 0.79 19.48 12.43 0.73 2.09 0.59 2.22 mean value 19.14 44.55 0.61 18.62 11.72 0.64 1.75 0.66 1.99
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