灰分对煤自燃特性影响的实验研究

为了研究灰分对煤自燃能力的影响作用,利用绝热氧化实验装置对不同灰分含量煤样进行升温氧化实验,采用R_(70)、T_(CPT)、B3种指标表征灰分含量对煤样自发氧化过程的影响。结果表明:1)灰分含量越大,煤样低温氧化阶段温升速率越小,温升加速点温度越高,煤样的自发氧化过程越慢,煤越不易自燃;灰分含量大于40%后,煤自燃倾向性快速减弱。温升加速点是反应微观信息的零活化能温度的宏观累计结果,具有直观且滞后的特点。灰分越大,滞后越明显,温差越大。2)R_(70)、T_(CPT)、B3种指标与灰分关系表现为二次函数。R_(70)和T_(CPT)两种指标显示灰分越大,自燃倾向性越弱,与实践经验相符。受水分权重影响,B指标显示煤样在灰分小于40%时,灰分越大,煤样自燃倾向性越强,这与实践经验相悖。因此,B在判定灰分对煤样自燃倾向性的影响时具有一定的局限性。

Experimental study of the impact of ash on spontaneous combustion characteristics of coal

In order to study the influence of ash on the ability of coal spontaneous combustion, we used coal samples with different ash content to carry out temperature rising oxidation experiments in adiabatic oxidation device, and characterized the effects of the different ash content on the coal spontaneous oxidation process with 3 indicators (R₇₀, T_CPT, B). The results indicate that (1) the larger the ash content is, the slower the coal spontaneous oxidation process is. In low-temperature oxidation stage, the smaller the heating rate is, the higher the acceleration point of temperature-rising is and the more difficult the coal is to burn spontaneously. When the ash content is greater than 40%, the coal spontaneous combustion tendency is rapidly weakened. The acceleration point of temperature-rising is the accumulated results of temperature of zero-activation which reflects microscopic information, and it is intuitive and delayed. The larger the ash content is, the more obvious the lag is and the greater the difference in temperature is .(2) The relationship between ash content and the 3 indicators (R₇₀,T_CPT,B) is quadratic function. R₇₀ and T_CPT indicators show the larger the ash is, the weaker the coal spontaneous combustion tendency is, and that is in accordance with experience. Affected by the weight of water, B indicator shows when coal ash is less than 40%, the larger the ash content is, the stronger the coal spontaneous combustion tendency is, which is contrary to experience. Therefore, B indicator has certain limitations in the determination of the impact of ash on the coal spontaneous combustion tendency.