Study on spontaneous combustion characteristics of preoxidized coal at different temperatures
To investigate the problem related to spontaneous combustion of leftover coal in goaf,Donghuantuo gas coal was taken as the model material and pre-oxidizations at 80,160,and 230℃were carried out to study the difference in spontaneous combustion characteristics.In this paper,low-temperature nitrogen adsorption,temperature-programmed gas chromatography and thermogravi-metric(TG)experiments were used to study the pore changes of coal samples at different pre-oxidation temperatures,the changes of characteristic gases and activation energy in the early stage of spontaneous combustion oxidation,based on which the change of spontaneous combustion tendency of coal samples were explored.The results show that the higher the degree of pre-oxidization,the higher the content of macropores and the higher the risk of spontaneous combustion.The main gases are CO,CH4,C2H4 and C2H2 in the programmed temperature test.The initial production temperatures of all kinds of gases rise with the increase of pre-oxidization temperature.Among them,the rate of CO and CH4 gas released by pre-oxidized coal sample has a tendency to surpass that of raw coal.It is found that the characteristic temperature points(T1,T2,T3)of coal sample decrease with the increase of pre-oxidization temperature and the activation energy of coal sample decreases after low temperature oxidation.It is concluded that the spontaneous combustion oxidation capacity of preoxidized coal sample is stronger than that of raw coal.Additionally,the tendency of coal sponta-neous combustion of the coal sample is affected by the structural changes of coal voids and internal energy changes in low temperature oxidization environment.
secondary oxidationspontaneous combustionspontaneous combustion tendencypore structureactivation energy
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