Revalidation of measurement method of free radical concentration and its application in coal chemistry
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摘要: 对前人建立的标准曲线法测煤中自由基浓度进行优化,以DPPH标准样品和基准样品的二次积分面积比值为新参数,结果显示新参数标准曲线法的实测值与理论值相对误差都在5%以内;重复性、复现性实验的相对标准偏差都小于3%。将新参数标准曲线法用于分析不同煤化程度煤和新疆黑山煤(HS)沥青质的自由基浓度,发现随着煤化程度增加,其煤中自由基浓度逐渐增大,从低阶褐煤的8.531×1017/g上升到高阶无烟煤3.37899×1019/g;而在HS煤液化过程中,随着加氢液化温度的升高,其沥青质自由基浓度逐渐下降,从290℃的1.5793×1018/g降到450℃的7.410×1017/g,沥青质自由基浓度变化趋势与其产率变化趋势相一致。Abstract: The standard curve method established by predecessors to measure the concentration of free radicals in coal was optimized to take the quadratic integral area ratio of the DPPH standard sample to the reference sample as new parameters. The results show that the relative error between the measured and theoretical values of the new parameter standard curve method is less than 5%, and the relative standard deviations of repeatability and reproducibility are less than 3%. The new parameter standard curve method was used to analyze the free radical concentration of the coal with different coal ranks and the asphaltene of Xinjiang Heishan Coal (HS). It is found that with the increase of coal rank, the free radical concentration in the coal increases gradually, from 8.531×1017/g for low-rank lignite to 3.37899×1019/g for high-rank anthracite. In the process of HS coal liquefaction, with the increase of liquefaction temperature, the free radical concentration of asphaltene decreases gradually, from 1.5793×1018/g at 290℃ to 7.410×1017/g at 450℃. The change trend of free radical is concentration in the asphaltene consistent with that of asphaltene yield.
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Key words:
- free radical concentration /
- standard curve method /
- coal chemistry /
- asphaltene /
- revalidation
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表 1 煤样的工业分析和元素分析
Table 1 Proximate and ultimate analyses of coal samples
Coal Proximate analysis w/% Ultimate analysis wdaf/% Mad Ad Vdaf FCdaf C H N S Oa XLT 16.68 10.21 55.62 44.38 68.94 4.72 1.86 1.21 23.27 NMH 15.06 5.12 51.35 48.65 73.52 5.68 0.96 0.24 19.60 HS 4.50 9.45 40.39 59.61 79.80 5.02 0.93 0.86 13.39 BLT 7.33 6.22 36.84 63.16 80.82 4.84 0.88 0.44 13.02 DT 2.69 7.97 35.35 64.65 83.85 5.20 1.62 0.37 8.96 LH 1.75 10.04 29.55 70.45 88.78 5.23 1.46 0.42 4.11 JX 1.81 9.29 20.60 79.40 89.27 4.82 1.48 0.52 3.91 HN 1.61 9.63 17.95 82.05 90.23 4.83 1.47 0.33 3.14 JC 4.92 8.97 7.65 92.35 92.17 3.41 1.32 0.31 2.79 a: by difference 表 2 标准曲线法准确性验证
Table 2 Accuracy of standard curve method
Sample(g) Measured value Nc/1016 Theoretical value Nc/1016 RE/% 0.0057 2.8766 2.7847 3.30 0.0095 4.5938 4.6411 -1.02 0.0151 7.0573 7.3769 -4.33 0.0205 10.1030 10.0150 0.88 0.0244 11.9292 11.9203 0.07 0.0294 13.9561 14.3630 -2.83 表 3 相同质量NMH煤的EPR测定
Table 3 EPR determination of NMH coal with the same quantity
NMH (g) Ng/(1018·g-1) AVG/(1018·g-1) R/% VAR/% RSD/% 0.0100 2.0843 0.0100 2.0601 0.0103 2.0660 2.0702 4.39 0.11 1.61 0.0098 2.1158 0.0099 2.0250 表 4 相同质量BLT煤的EPR测定
Table 4 EPR determination of BLT coal with the same quantity
BLT (g) Ng/(1018·g-1) AVG/(1018·g-1) R/% VAR/% RSD/% 0.0043 10.1352 0.0043 10.2089 0.0038 10.2584 10.2827 3.57 1.96 1.36 0.0040 10.5024 0.0037 10.3313 表 5 标准曲线法复现性测试
Table 5 Reproducibility of standard curve method
NMH(g) Ng/(1018·g-1) AVG/(1018·g-1) R/% VAR/% RSD/% week 1 week 2 week 3 week 4 week 5 0.0042 2.1350 2.1025 2.0535 2.0318 2.1460 2.0938 0.0079 2.0342 2.1104 1.9654 2.0231 2.0614 2.0389 0.0119 2.0785 1.9876 2.0031 2.0034 2.0125 2.0170 3.73 0.10 1.57 0.0165 2.0920 2.1388 2.0598 2.0134 2.1274 2.0863 0.0209 2.0540 2.0033 2.0745 2.1003 2.1025 2.0669 表 6 不同煤化程度煤的EPR测试
Table 6 EPR parameters of different rank coals
Coal Coal rank Cdaf/% Ng/(1018·g-1) ΔH/(Gs) g XLT lignite 68.94 0.8513 5.46 2.00448 NMH lignite 73.52 2.0702 6.95 2.00423 HS long flame coal 79.80 9.3406 5.39 2.00381 BLT non caking coal 80.82 10.2827 5.76 2.00372 DT gas coal 83.85 15.2712 5.56 2.00370 LH fat coal 88.78 16.1770 5.76 2.00305 JX coking coal 89.27 19.0823 5.86 2.00297 HN lean coal 90.23 21.9365 5.46 2.00281 JC anthracite 92.17 33.7899 3.98 2.00280 -
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