Xuan Jingjian, Yuan Shujie, Xu Xiaoxue
School of Safety Science and Engineering, Anhui University of Science and Technology, Huainan, Anhui 232001, China.
Key Laboratory of Safe and Effective Coal Mining, Ministry of Education, Huainan, Anhui 232001, China.
ACS Omega. 2024 Feb 1;9(6):6773-6786. doi: 10.1021/acsomega.3c08098. eCollection 2024 Feb 13.
In order to study the synergistic effect of the moisture content and pH value of aqueous solutions on coal oxidation, coal samples with different moistures were prepared by using aqueous solutions with different pH values (3, 5, 7, and 8). The CO, CH production, oxygen consumption rate, and crossing point temperature parameters in the process of low-temperature oxidation of the prepared coal and raw coal samples were studied by using a low-temperature oxidation device. Thermogravimetry-derivative thermogravimetry (TG-DTG) curves of coal samples with different moistures were obtained on the basis of thermogravimetric analysis of coal by using a synchronous thermal analyzer. According to the characteristic temperature, the process of coal spontaneous combustion (CSC) can be divided into the water evaporation and desorption stage, oxygen absorption and weight gain stage, thermal decomposition and combustion stage, and burnout stage. The Coats-Redfern integral method was used to select the appropriate reaction mechanism function to calculate the apparent activation energy at different stages of the coal reaction process. The results show that the activation energy of the oxidation reaction of the coal sample with a moisture of 15% is the smallest, and the oxidation reaction is the most easy to occur. When the coal samples with a moisture of 15% were oxidized at low temperature, the CO and CH emissions and oxygen consumption rates were the highest. The pH value of the aqueous solution has dual effects on CSC. When the moisture is 15%, the higher the pH value of the aqueous solution, the weaker the promotion effect on the coal oxidation process is and the lower the pH value of the aqueous solution is, the higher the production of CO and CH and the oxygen consumption rate is and the earlier the crossing point temperature is reached during low-temperature oxidation of the coal sample.
为研究水溶液的含水量和pH值对煤氧化的协同作用，采用不同pH值（3、5、7和8）的水溶液制备了不同含水量的煤样。利用低温氧化装置研究了所制备煤样和原煤样低温氧化过程中的CO、CH生成量、耗氧率和交叉点温度参数。在对煤进行热重分析的基础上，利用同步热分析仪获得了不同含水量煤样的热重-微商热重（TG-DTG）曲线。根据特征温度，煤自燃过程可分为水分蒸发和解吸阶段、吸氧增重阶段、热分解燃烧阶段和燃尽阶段。采用Coats-Redfern积分法选择合适的反应机理函数来计算煤反应过程不同阶段的表观活化能。结果表明，含水量为15%的煤样氧化反应活化能最小，氧化反应最易发生。含水量为15%的煤样低温氧化时，CO和CH排放量及耗氧率最高。水溶液的pH值对煤自燃有双重影响。当含水量为15%时，水溶液的pH值越高，对煤氧化过程的促进作用越弱；水溶液的pH值越低，煤样低温氧化时CO和CH的生成量及耗氧率越高，交叉点温度出现得越早。
