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煤氧化热反应特性与SHAP可解释温度预测模型

Thermal reaction characteristics of coal oxidation and SHAP-explainable temperature prediction model

  • 摘要: 为构建适用于复杂氧化工况的煤自燃温度高精度预测模型,揭示氧化反应热动力机制与温度演化过程之间的耦合特征,提升对关键热反应节点的识别能力,支撑矿井自燃智能预警体系建设。通过在不同氧气体积分数和升温速率条件下开展程序升温与同步热分析试验,监测气体释放行为及TG–DSC响应曲线,提取煤氧化过程中具有代表性的特征温度点(TC1TC7T1T6),构建煤自燃过程的阶段划分体系。并将氧化过程整合为4个宏观反应区间,采用Coats–Redfern法计算各合并阶段的表观活化能和焓变,结合气体特征共同构建基于极端梯度提升算法(Extreme Gradient Boosting,XGBoost)与梯度提升算法(Gradient Boosting,GBR)的多维温度预测模型,并引入沙普利加性解释(Shapley Additive Explanations,SHAP)进行特征贡献度可解释性分析。结果表明:随着氧气体积分数降低,特征温度点TC6TC7显著向高温区偏移,偏移率分别为−2.0 ℃/%与−1.33 ℃/%;随着升温速率升高,特征温度点T2T4的温度变化显著加快,偏移率分别为2.85 ℃/(℃·min−1)和2.83 ℃/(℃·min−1)。综合特征温度点变化趋势与煤样氧化过程的官能团响应特征,将煤氧化过程划分为7个阶段:吸附氧积累、诱导启动、氧化加速、热解活化、热失控临界、缓慢氧化与燃烧反应阶段,反映温度演化、气体释放与分子结构转化的阶段性耦合特征。其中热失控临界区间的活化能达78.86 kJ/mol,焓变为74.16 kJ/mol,明显高于前期诱导区间,体现反应放热强度提升。在多源特征融合基础上构建的XGBoost模型在测试集上决定系数R2为0.999 6,平均绝对误差MAE为0.32 ℃,优于GBR模型。SHAP分析结果表明,Ea与ΔH等热分析参数在温度预测中具有阶段性贡献权重,联合气体特征共同反映反应演化特性,增强了模型的物理一致性与解释能力。研究构建的煤温预测模型可为煤自燃过程中的特征识别与注氮、通风等干预策略的动态制定提供数据支撑与理论依据。

     

    Abstract: A high-precision temperature prediction model for coal spontaneous combustion under complex oxidation conditions is developed to enhance stage identification and support early warning in underground coal mines. Programmed heating and simultaneous thermal analysis experiments are performed under varying oxygen concentrations and heating rates. Characteristic temperature points (TC1TC7, T1T6) are extracted, and the oxidation process is divided into seven stages according to their evolution and functional group responses. The process is further integrated into four macro intervals for calculating apparent activation energy and enthalpy change using the Coats–Redfern method. These thermal and gas features are used as inputs for temperature prediction models based on XGBoost and GBR algorithms. SHAP analysis is applied to interpret feature contributions. Results show that TC6 and TC7 are shifted significantly toward higher temperatures as oxygen concentration decreases, with deviation rates of −2.0 ℃/% and −1.33 ℃/%, respectively. T2 and T4 are highly sensitive to increases in heating rate, with deviation rates of 2.85 ℃/( ℃·min−1) and 2.83℃/(℃·min−1). The thermal runaway threshold stage exhibits the highest activation energy (78.86 kJ/mol) and enthalpy change (74.16 kJ/mol), indicating intensified heat release. Superior predictive performance is achieved by the XGBoost model (R2 = 0.999 6, MAE = 0.32 ℃), outperforming GBR. SHAP analysis confirms stage-dependent contributions of thermal and gas parameters, thereby improving physical interpretability. A reliable basis is provided for dynamic identification of combustion risk and for optimization of nitrogen injection and ventilation strategies in spontaneous combustion control.

     

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