Spontaneous combustion behavior of crushed coal at different preoxidation temperatures under uniaxial compression
Objectives To study the spontaneous combustion characteristics of crushed coal at different pre-oxidation temperatures under various stress conditions,Methods a uniaxial compression device equipped with a temperature-programmed oxidation device(UCTP)was used to analyze the characteristic parameters such as oxygen consumption rate,characteristic temperature points,gas production,and activation energy changes during the oxidation process.Results The experimental results showed that uniaxial compression en-hanced the oxidation characteristics of the coal samples,as evidenced by the increase in oxygen consump-tion rate,the higher concentration of CO and C2H4 gases,the forward shift of characteristic temperature points,and the decrease in activation energy.When the uniaxial compression was 0 MPa and 4 MPa,the oxidation characteristics of the pre-oxidized 70℃coal samples were the strongest.At 8 MPa,the increase in pre-oxidation temperature led to a decrease in the oxidation characteristics of the coal samples.Combining the changes in oxygen consumption rate,index gases,and activation energy,it was found that the sponta-neous combustion tendency of pre-oxidized 70℃coal was higher and more prone to reignition.Conclu-sions(1)The spontaneous combustion characteristics of coal samples with different pre-oxidation tempera-tures behaved consistently under the influence of axial pressure.Specifically,uniaxial compression en-hanced the oxidation characteristics of the coal,making it more likely to reignite and progress to the rapid oxidation stage.(2)The effects of pre-oxidation temperature on coal's spontaneous combustion characteris-tics under different axial pressures varied.Increasing the pre-oxidation temperature reduced the coal's oxi-dation characteristics,indicating that higher pre-oxidation temperatures weakened the oxidation properties of the coal under high axial pressure.
uniaxial compressionoxygen consumption ratecharacteristic temperature pointindex gasesapparent activation energypropensity for spontaneous combustion
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