预氧化煤低温氧化放热和动力学特性研究

闫国锋; 黄兴利; 闫振国

doi:10.13272/j.issn.1671-251x.2022030032

预氧化煤低温氧化放热和动力学特性研究

doi: 10.13272/j.issn.1671-251x.2022030032

1.
陕西黄陵矿业集团有限公司, 陕西延安　727306
2.
陕西黄陵二号煤矿有限公司, 陕西延安　727306
3.
西安科技大学安全科学与工程学院, 陕西西安　710054

基金项目: 陕西省自然科学基础研究计划项目（S2019-JC-LH-QY-SM-0065）。

详细信息

作者简介:
闫国锋（1982-），男，陕西宝鸡人，工程师，硕士，主要从事煤矿“一通三防”工作，E-mail：1157076743@qq.com

中图分类号: TD713
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出版历程
- 收稿日期: 2022-03-08
- 修回日期: 2022-06-30
- 网络出版日期: 2022-05-13

Research on exothermic and kinetic characteristics of low-temperature oxidation of preoxidized coal

1.
Shaanxi Huangling Mining Group Co., Ltd., Yan'an 727306, China
2.
Shaanxi Huangling No. 2 Coal Mine Co., Ltd., Yan'an 727306, China
3.
College of Safety Science and Engineering, Xi'an University of Science and Technology, Xi'an 710054, China

摘要

摘要: 现有氧化煤自燃特性研究大多以较低氧化温度和空气条件下制取的煤样为研究对象，缺乏对预氧化煤氧化过程中动力学特性的分析。针对上述问题，利用C80微量热仪以不同氧化温度（100，200，300 ℃）和氧气体积分数（21%，15%，5%）条件下制取的预氧化煤为对象，研究了其低温氧化反应的放热和动力学特性，并探讨了氧化温度和氧气浓度对预氧化煤低温氧化反应活化能的影响。预氧化煤低温氧化放热特性分析结果：① 预氧化煤低温氧化进程滞后于原煤样，且滞后程度随氧化温度和氧气浓度升高而增大。② 预氧化煤低温氧化反应的放热量低于原煤样，且放热量随氧化温度和氧气浓度升高逐渐降低。当氧化温度为100 ℃时，不同氧气浓度预氧化煤的t₁（热流＞0时对应的温度）、t₂（热流增长率最大值对应的温度）及低温氧化过程的反应热基本相等。③ 随着氧化温度升高，氧气浓度对t₁、t₂及低温氧化过程的反应热的影响才逐渐明显。表明氧气浓度对预氧化煤低温氧化反应的影响在较高的氧化温度下才体现。但是，太高的氧化温度导致预氧化煤低温氧化反应进程严重滞后且反应放热量＜0。预氧化煤低温氧化动力学参数分析结果：① 预氧化煤低温氧化反应加速氧化阶段的活化能高于原煤样，快速氧化阶段的活化能低于原煤样。表明预氧化煤氧化反应进入加速氧化阶段的门槛提高，却更容易进入快速氧化阶段。② 从指前因子数据可看出，预氧化煤低温氧化反应相较于原煤样更为迅速。③ 预氧化煤低温氧化过程的活化能没有随氧化温度和氧气浓度的变化表现出明显的规律性：在加速氧化阶段活化能随氧化温度升高而增大，随氧气浓度升高呈先降低后升高趋势；在快速氧化阶段，当氧化温度为100 ℃，活化能随氧气浓度升高呈先降低后升高趋势，而氧化温度为200 ℃时则相反。
- 煤自燃 /
- 氧化煤 /
- 预氧化煤 /
- 低温氧化 /
- 动力学参数 /
- 加速氧化 /
- 快速氧化 /
- 氧化温度 /
- 氧气浓度 /
- 活化能 /
- 指前因子
Abstract: The existing research on the spontaneous combustion characteristics of oxidized coal is mostly based on the coal samples prepared under the conditions of lower oxidation temperature and air. It lacks the analysis of the kinetic characteristics during the oxidation process of oxidized coal. In order to solve the above problems, the C80 microcalorimeter is used to study the exothermic and kinetic characteristics of low-temperature oxidation reaction of preoxidized coal prepared under different oxidation temperatures (100, 200, 300 ℃) and oxygen volume fraction (21%, 15%, 5%). The effects of oxidation temperature and oxygen concentration on the activation energy of low-temperature oxidation reaction of preoxidized coal are discussed. The analysis results of low-temperature oxidation exothermic characteristics of preoxidized coal are shown as follows. ① The low-temperature oxidation process of preoxidized coal lags behind that of raw coal. The degree of lag increases with the increase of oxidation temperature and oxygen concentration. ② The heat release of low-temperature oxidation reaction of preoxidized coal is lower than that of raw coal. The heat release gradually decreases with the increase of oxidation temperature and oxygen concentration. When the oxidation temperature is 100 ℃, t₁ (the temperature at which the heat flow value starts ＞0), t₂ (the temperature corresponding to the maximum growth rate of heat flow value) and the reaction heat of low-temperature oxidation of preoxidized coals with different oxygen concentrations are basically equal. ③ With the increase of oxidation temperature, the effect of oxygen concentration on t₁, t₂ and the reaction heat of low-temperature oxidation is gradually obvious. The results show that the effect of oxygen concentration on the low-temperature oxidation reaction of preoxidized coal is only reflected at higher oxidation temperatures. However, too high oxidation temperature will lead to a serious lag of the low-temperature oxidation reaction process of pre-oxidized coal and the reaction heat release is less than 0. The analysis results of kinetic parameters (activation energy and pre-exponential factor) of low-temperature oxidation of pre-oxidized coal are shown as follows. ① The activation energy of the low-temperature oxidation reaction of pre-oxidized coal in the accelerated oxidation stage is higher than that of raw coal. The activation energy of the rapid oxidation stage is lower than that of raw coal. The results show that the threshold of the oxidation reaction of pre-oxidized coal entering the accelerated oxidation stage is increased, but it is easier to enter the rapid oxidation stage. ② The pre-exponential factor data show that the low-temperature oxidation reaction of pre-oxidized coal is more rapid than that of raw coal. ③ The changes of oxidation temperature and oxygen concentration have no obvious regularity with the activation energy of the low-temperature oxidation process of preoxidized coal. In the accelerated oxidation stage, the activation energy increases with the increase of oxidation temperature. The activation energy first decreases and then increases with the increase of oxygen concentration. In the rapid oxidation stage, when the oxidation temperature is 100 ℃, the activation energy first decreases and then increases with the increase of oxygen concentration, while 200 ℃ is the opposite.
- coal spontaneous combustion /
- oxidized coal /
- preoxidized coal /
- low-temperature oxidation /
- dynamic parameters /
- accelerated oxidation /
- rapid oxidation /
- oxidation temperature /
- oxygen concentration /
- activation energy /
- pre-exponential factor

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图 1 特征温度和特征阶段

Figure 1. Characteristic temperatures and stages

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图 2 预氧化煤和原煤样热流曲线

Figure 2. Heat flow curves of pre-oxidized coal and raw coal samples

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图 3 预氧化煤和原煤样活化能拟合曲线

Figure 3. Fitting curves of activation energy of pre-oxidized coal and raw coal samples

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图 4 不同氧化温度和氧气浓度下活化能变化

Figure 4. Variation of activation energy under different oxidation temperatures and oxygen concentrations

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表 1 实验煤样的工业分析和元素分析

Table 1. Proximate and ultimate analysis of experimental coal samples %

工业分析					元素分析
煤样	水分	挥发分	灰分	固定碳	C	H	O	N
气煤	3.65	17.24	33.93	45.18	79.42	5.36	13.83	1.53

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表 2 预氧化煤和原煤样特征温度

Table 2. Temperature characteristics of pre-oxidized coal and raw coal samples

煤样	t₁/℃	t_2/℃
原煤样	134	199
氧化温度100 ℃、氧气体积分数21%的预氧化煤	139	203
氧化温度100 ℃、氧气体积分数15%的预氧化煤	139	203
氧化温度100 ℃、氧气体积分数5%的预氧化煤	136	201
氧化温度200 ℃、氧气体积分数21%的预氧化煤	185	240
氧化温度200 ℃、氧气体积分数15%的预氧化煤	173	232
氧化温度200 ℃、氧气体积分数5%的预氧化煤	154	204
氧化温度300 ℃、氧气体积分数21%的预氧化煤	234	—
氧化温度300 ℃、氧气体积分数15%的预氧化煤	213	—
氧化温度300 ℃、氧气体积分数5%的预氧化煤	188	—

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表 3 预氧化煤和原煤样动力学参数

Table 3. The dynamic parameters of pre-oxidized coal and raw coal samples

煤样	q/(J·g⁻¹)	阶段	E_a/(kJ·mol⁻¹)	A/s⁻¹	R²/(J·mol⁻¹·K⁻¹)
原煤样	2 860.05	2	99.67±7.94	9.44×10⁶±8.75	0.92
原煤样	2 860.05	3	25.34±1.54	0.029 7±1.43	0.93
氧化温度100 ℃、氧气体积分数21%的预氧化煤	2 765.84	2	107.69±9.74	7.52×10⁷±14.12	0.92
氧化温度100 ℃、氧气体积分数21%的预氧化煤	2 765.84	3	24.00±1.52	0.035 2±1.42	0.94
氧化温度100 ℃、氧气体积分数15%的预氧化煤	2 820.19	2	104.14±8.77	2.91×10⁷±10.87	0.92
氧化温度100 ℃、氧气体积分数15%的预氧化煤	2 820.19	3	23.49±1.52	0.031 5±1.43	0.94
氧化温度100 ℃、氧气体积分数5%的预氧化煤	2 824.62	2	109.32±9.92	1.13×10⁸±14.81	0.92
氧化温度100 ℃、氧气体积分数5%的预氧化煤	2 824.62	3	24.06±1.59	0.035 6±1.45	0.93
氧化温度200 ℃、氧气体积分数21%的预氧化煤	1 642.95	2	161.85±12.52	6.20×10¹²±22.12	0.94
氧化温度200 ℃、氧气体积分数21%的预氧化煤	1 642.95	3	23.97±3.83	0.051 6±2.35	0.81
氧化温度200 ℃、氧气体积分数15%的预氧化煤	2 018.45	2	142.38±13.53	3.88×10¹¹±36.36	0.92
氧化温度200 ℃、氧气体积分数15%的预氧化煤	2 018.45	3	24.64±1.84	0.043 4±1.53	0.92
氧化温度200 ℃、氧气体积分数5%的预氧化煤	2 528.45	2	147.10±11.19	2.75×10¹¹±16.83	0.94
氧化温度200 ℃、氧气体积分数5%的预氧化煤	2 528.45	3	22.28±3.04	0.031 4±1.98	0.84
氧化温度300 ℃、氧气体积分数21%的预氧化煤	−215.29	—	—	—	—
氧化温度300 ℃、氧气体积分数15%的预氧化煤	−67.66	—	—	—	—
氧化温度300 ℃、氧气体积分数5%的预氧化煤	354.92	—	—	—	—

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