Mechanism and performance of coal spontaneous combustion with a halide carrier inorganic salt inhibitor
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摘要: 為了研究鹵鹽載體無機鹽阻化劑對煤自燃的阻化機理及性能,采用差示掃描量熱儀(DSC)測試了在稀土水滑石、MgCl2和鹵鹽載體無機鹽三種不同阻化劑作用下,煤自燃過程中分階段特征、特征溫度、熱效應和表觀活化能等參數變化規律。測試結果表明,稀土水滑石層板的?OH能夠與煤分子中的?COOH等酸性官能團產生弱氫鍵,造成?COOH等酸性官能團的活性減弱;Mg2+與煤分子中的—COO?發生絡合作用,生成了?COOMg?,造成?COO?內的 C=O活性減弱是鹵鹽載體無機鹽抑制煤自燃的主要機理。煤樣中添加鹵鹽載體無機鹽后DSC曲線吸熱峰均出現雙峰或多峰,且較原煤的峰值溫度后移了50~60 ℃、T1溫度后移了90~100 ℃、總放熱量降低了19~27 kJ?g?1,而且有效的提高了煤體各階段的表觀活化能。研究表明鹵鹽載體無機鹽阻化劑可有效抑制煤自燃反應進程。Abstract: Coal spontaneous combustion seriously restricts the safe production of coal mines, and adding an inhibitor is one of the effective methods to prevent coal spontaneous combustion. To improve the pertinence and high efficiency of the inhibitor, this paper considered the intrinsic properties and external conditions that affect the occurrence of coal spontaneous combustion, combined with the characteristics that the rare earth hydrotalcite can effectively improve the thermal stability, coupling, and flame retardancy of the coal and the halide inhibitor. The halide inhibitor can enhance the permeability, dispersion, and uniformity of the rare earth hydrotalcite as a carrier. The halide carrier inorganic salt inhibitor was prepared. To study the inhibition mechanism and performance of the halide carrier inorganic salt inhibitor on coal spontaneous combustion, differential scanning calorimetry (DSC) was used to test the variation law of parameters, such as stage characteristics, characteristic temperature, thermal effect, and apparent activation energy in the process of coal spontaneous combustion under the action of a rare earth hydrotalcite, MgCl2 and a halide carrier inorganic salt inhibitor. Test results reveal that the OH of the rare earth hydrotalcite laminate can generate a weak hydrogen bond with acidic functional groups such as ?COOH in coal molecules so that the activity of the acidic functional groups is weakened. Mg2+ complexes with ?COO? in coal molecules to form ?COOMg?, resulting in the weakening of the C=O activity in ?COO?, which is the main mechanism of the halide carrier inorganic salts inhibiting coal spontaneous combustion. The endothermic peak of the DSC curve appears as a double peak or multi-peak after the addition of halide carrier inorganic salts to the coal sample. Compared with the raw coal, the peak temperature is shifted back by 50–60 ℃, the T1 temperature is shifted back by 90–100 ℃, and the total heat release decreased by 19–27 kJ?g?1. Furthermore, the apparent activation energy of each stage of the coal body is effectively improved. Results revealed that the halide carrier inorganic salt inhibitor could effectively inhibit the reaction process of coal spontaneous combustion.
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圖 4 各樣品熱釋放速率曲線圖。(a)試驗樣品1;(b)試驗樣品2;(c)試驗樣品3;(d)試驗樣品4;(e)試驗樣品5;(f)試驗樣品6;(g)試驗樣品7;(h)試驗樣品8;(i)試驗樣品9;(j)試驗樣品10;(k)試驗樣品11;(l)試驗樣品12
Figure 4. Heat release rate curve: (a) sample 1;(b) sample 2;(c) sample 3;(d) sample 4; (e) sample 5;(f) sample 6;(g) sample 7;(h) sample 8; (i) sample 9;(j) sample 10;(k) sample 11;(l) sample 12
表 1 煤的工業分析與元素分析(質量分數)
Table 1. Industrial analysis and element analysis of coal
% Proximate analysis Ultimate analysis Mad Aad Vad FCad Cdaf Hdaf Nda Oda Sdaf 4.66 15.84 32.88 46.62 76.04 3.95 0.68 19.25 0.08 表 2 阻化劑配制成分表(質量分數)
Table 2. Composition list of the inhibitor
% Sample Rare earth
hydrotalciteH2O Sample MgCl2 Rare earth hydrotalcite H2O 1 0 100 7 20 0 80 2 1 99 8 20 1 79 3 3 97 9 20 3 77 4 5 95 10 20 5 75 5 7 93 11 20 7 73 6 9 91 12 20 9 71 表 3 試驗樣品在不同氧化階段的放熱量
Table 3. Heat release of test samples at different oxidation stages
Sample Total heat released/
(J?mg?1)Total heat absorbed
(heat absorption stage)/
(J?mg?1)Slow heat release stage Rapid heat release stage Heat released/
(J?mg?1)Percentage of total
heat released /%Heat released/
(J?mg?1)Percentage of total
heat released /%1 74.31 1.72 29.49 39.69 44.82 60.31 2 88.76 1.6 30.02 33.82 58.74 66.18 3 98.6 0.12 25.46 25.82 73.14 74.17 4 94.48 0.13 21.68 22.94 72.8 77.05 5 103.83 0.31 27.37 26.36 76.46 73.64 6 98.13 0.48 33.53 34.17 64.6 65.83 7 63.09 1.17 19.22 30.46 43.87 69.53 8 49.17 1.06 15.63 31.79 33.54 68.21 9 53.31 1.08 16.18 30.35 37.13 69.65 10 55.37 1.6 17.73 32.02 37.64 67.98 11 47.11 1.77 16.06 34.09 31.05 65.91 12 48.68 2.31 16.18 33.24 32.5 66.76 表 4 緩慢放熱階段表觀活化能參數
Table 4. Apparent activation energy parameters in the slow heat release stage
Sample Fitting linear
equationApparent activation
energy, E /
(J·mol–1)Correlation
coefficient,
R21 y=?3392.23468x+3.47896 28203.0391 0.97832 2 y=?4771.26045x+7.20905 39668.25938 0.95058 3 y=?3677.22585x+4.10123 30572.45572 0.96386 4 y=?3994.97463x+4.91556 33214.21907 0.97228 5 y=?4037.2746x+4.84162 33565.90102 0.9789 6 y=?4163.42638 x+5.24455 34614.72692 0.98845 7 y=?6428.62213x+9.04335 53447.56439 0.9187 8 y=?5443.14126x+7.62782 45254.27644 0.99003 9 y=?6140.78185x+9.03888 51054.4603 0.98428 10 y=?6653.1257x+ 9.91782 55314.08707 0.95261 11 y=?5802.11937x+8.25131 48238.82044 0.98814 12 y=?5623.12086 x+ 8.04004 46750.62683 0.9913 表 5 快速放熱階段活化能參數
Table 5. Apparent activation energy parameters in the rapid heat release stage
Sample Fitting linear
equationApparent activation
energy, E /
(J·mol–1)Correlation
coefficient,
R21 y=?6881.26298x+7.89178 57210.82042 0.90249 2 y=?9425.37165x+11.82431 78362.5399 0.98207 3 y=?8808.86618x+10.8194 73236.91342 0.96555 4 y=?7816.14674x+9.33284 64983.444 0.9513 5 y=?7140.95942x+8.32359 59369.93645 0.93582 6 y=?7994.84827x+9.5651 66469.16852 0.94128 7 y=?9377.78707x+11.73499 77966.9217 0.97704 8 y=?10237.40606x+12.94076 85113.79398 0.95442 9 y=?8923.61423x+10.90617 74190.92871 0.94638 10 y=?10153.61359x+12.85178 84417.14339 0.9656 11 y=?10102.1723x+12.81694 83989.4605 0.9858 12 y=?10299.87431x+13.13003 85633.15501 0.96873 www.77susu.com -
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