Self-heating of coal during its storage and transportation has been a serious problem for decades. Coal stored in large piles for long duration is subjected to weathering by atmospheric air that prevails with different temperatures and moisture content. Chemisorption of atmospheric oxygen results in low-temperature oxidation of pile, which generates heat due to exothermic reactions. If the local heat release rate is higher as compared to the heat dissipated, a significant increase in temperature is possible and this results in spontaneous ignition of the pile. The presence of moisture in coal delays the occurrence of self-heating. This motivates to analyze a scenario of using moist coal to delay or even prevent the self-ignition in dry coal until a given time period of its storage. The main objective of this work is to investigate the critical conditions, which may lead to spontaneous ignition in large coal stockpiles containing dry and moist coal layers. A one-dimensional numerical model is used for this purpose. A parametric study is carried out considering different porosity, superficial air velocity and reactivity values. The time period of coal pile storage is fixed as 360 days. The location and time taken for self-ignition in the pile within this period is reported for each case. In summary, considering several cases, the simulations systematically reveal that highly reactive coal with high pile porosity and higher superficial gas velocity takes the least time to reach the self-ignition temperature.

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大型煤堆自燃的参数研究

几十年来，煤炭在储存和运输过程中的自热一直是一个严重的问题。长期储存在大堆中的煤炭会受到空气的风化，这种空气普遍具有不同的温度和水分含量。大气氧的化学吸附导致桩的低温氧化，由于放热反应而产生热量。如果局部放热率高于散发的热量，则温度可能会显着升高，从而导致桩自燃。煤中水分的存在延迟了自热的发生。这激发了分析使用湿煤来延迟甚至防止干煤自燃直到其储存的给定时间段的情况。这项工作的主要目的是调查可能导致含有干和湿煤层的大型煤堆自燃的临界条件。为此使用一维数值模型。考虑到不同的孔隙度、表观空气速度和反应性值，进行了参数研究。煤堆存放时间固定为360天。为每个案例报告在此期间堆中自燃所需的位置和时间。总之，考虑到几种情况，模拟系统地揭示了具有高孔隙率和较高表观气速的高活性煤达到自燃温度所需的时间最短。为此使用一维数值模型。考虑到不同的孔隙度、表观空气速度和反应性值，进行了参数研究。煤堆存放时间固定为360天。报告每个案例在这段时间内自燃的位置和时间。总之，考虑到几种情况，模拟系统地揭示了具有高孔隙率和较高表观气速的高活性煤达到自燃温度所需的时间最短。为此使用一维数值模型。考虑到不同的孔隙度、表观空气速度和反应性值，进行了参数研究。煤堆存放时间固定为360天。为每个案例报告在此期间堆中自燃所需的位置和时间。总之，考虑到几种情况，模拟系统地揭示了具有高孔隙率和较高表观气速的高活性煤达到自燃温度所需的时间最短。报告每个案例在这段时间内自燃的位置和时间。总之，考虑到几种情况，模拟系统地揭示了具有高孔隙率和较高表观气速的高活性煤达到自燃温度所需的时间最短。为每个案例报告在此期间堆中自燃所需的位置和时间。总之，考虑到几种情况，模拟系统地揭示了具有高孔隙率和较高表观气速的高活性煤达到自燃温度所需的时间最短。