弱还原性烟煤氧吸附及其动力学研究
Study on oxygen adsorption and kinetic of weakly reductive bituminous coal
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摘要: 为掌握弱还原性烟煤在自然环境中的低温氧化规律,预防高温深井煤炭自燃,采用自制的固定床反应器对哈密煤样(HM)和灵武煤样(LW)进行不同载气流量的氧吸附试验,并对其动力学参数进行了拟合计算。研究结果表明,与载气中氧体积分数为25%相比,氧体积分数为15%时,LW和HM煤样氧吸附量明显增大,当温度达到160℃,2种煤样固定床出口氧体积分数分别为7.71%和6.41%。对于HM煤样,随着温度逐渐升高至100℃,煤样中氧吸附量逐渐增大,但此时载气中氧体积分数对煤样中氧含量变化影响较小。与原煤相比,脱灰煤样以及干燥温度较高的煤样比表面积较大,由于HM煤样比表面积大于LW煤样,吸附氧的活性位大于LW煤样,进而导致HM煤样在固定床出口处氧体积分数小于LW煤样。此外,当载气流量降低时,煤样中氧吸附量较大。HM和HM-D脱灰煤样在载气流量为40 m L/min时活化能最小,此时自燃倾向性最大;当载气流量为80 m L/min时,LW和LW-D脱灰煤样活化能最小,且LW-D煤样活化能大于LW煤样。Abstract: in order to understand the rule of ow temperatureoxidation of weakly reductive coals in the natural environment and prevent the coal spontaneous combustion in deep mine on high temperaure oxygen adsorption experiment wit adfferent carier gas velocity and the knetic parameters were analyzed and calculated based on Hani and Llingwu weakly reductive biuminous coals( Hami and Lingw biuminous coal were dencoted as HM and LW respectively) were caried out with a fixed bed reactot Theresuls showt that compared with the volume frction of oxygen in the carier gas i 25%, when the volunme fraction of oxygen is 15%, he oxygen consumption of LW and HM coal sample are obviously larger. when the temperature reaches 160 C,the volume fracion of cutet oygen in fied bed is 7.71% and6.41%respectivly. or HMl coal sample as the temperature increased to 100 ℃C.the adsoption content of oxygen in coal sample also graduay increase bu at the moment,the oxygen content in the caier gas has itle ifuence on the conent of oxygen in cal sample.compared with raw coal deminfralzed coal samples and higher drying temperature of cal sample have larger specific surace area,and the specific surace area of HhM coal sample is greater than the LN coal sample and the acivty of oxygen adsorption is greater than the LW cal sample,which leading to the volume fraction of oxygen in the outle ofixed bed oflM/ cal sample is smallea than L/lcoal sampleIn aditon.when the carrier gas fow rate i decreased,the amount of oxygen adsopion in coal sample is larer chen the cariergasfow rate is 4 m L:mi.the ciation energy of HM and denineralized HI-D cal sample is mininmunm.and the spontaneous combustion tendency is maxinun at tis time .When thecarergasfiow rete is 80 m L/ min,the activation energy of LN and LW-D coal sample is mininum,and the activation energy of demineralized LW-D is greater than the Lw.