惰性气体对粉尘爆炸泄放特性影响的实验研究

Experimental study on the dust explosion venting behavior by the addition of inert gas

爆炸泄放和爆炸抑制是工业上降低粉尘爆炸危害性的两个重要手段,同时实现粉尘爆炸抑制和泄放共同作用的效果值得关注。基于标准20 L球形粉尘爆炸装置侧向开泄放口,实验研究不同泄放口径和静态动作压力时CO_(2)/N_(2)对石松子粉泄放过程压力的影响,采用热重分析法分析了石松子粉尘分别在CO_(2)、N_(2)氛围的热重变化。结果表明,在20 mm泄放口径时,随着CO_(2)/N_(2)浓度的增加,泄放压力的降低幅值逐渐增大,且CO_(2)对粉尘爆炸泄放最大超压的减小效果要优于N_(2)。泄放压力值随着CO_(2)浓度的增加基本呈线性降低,当体系中的CO_(2)和N_(2)浓度增加到10%时对体系泄放压力值的降低效果开始趋于一致。对于40 mm泄放口径,添加相同浓度的CO2体系泄放压力值要略低于N_(2),降低幅值为6%~8%。对于60 mm泄放口径,CO_(2)/N_(2)两者抑制效果差别不大,且在添加浓度不超过8%时对体系泄放压力值的降低幅值影响较小。通过TGA曲线可以发现,在N_(2)气氛和CO_(2)气氛的热流条件中,石松子粉的热解过程在370℃左右开始出现明显的差异,CO_(2)气氛中石松子粉的热解速率要快于其在N_(2)气氛中的,因此在这个过程中CO_(2)的存在一定程度上会促进石松子粉的热解,随着热解温度进一步提升,CO_(2)对石松子粉热解的抑制效果开始逐渐体现。

Explosion venting and explosion suppression are two important means to reduce the hazard of dust explosion in industry.Therefore,the coupling of the two methods to reduce the hazard of dust explosion is worth to attention.The influence of CO_(2)/N_(2)on the pressure release process of lycopodium powder was experimentally studied with different discharge diameters and static activation overpressure by employing standard 20 L spherical dust explosion device with a lateral venting device.The thermogravimetric analysis method was used to analyze the thermogravimetric changes of lycopodium dust in the atmosphere of CO_(2)and N_(2) respectively.The results show that at 20 mm discharge caliber,with the increase of CO_(2)/N_(2) concentration,the reduction amplitude of discharge pressure gradually increases,and the reduction effect of CO_(2)on the maximum overpressure of dust explosion discharge is better than that of N_(2).The reduced pressure basic linearly with the increase of CO_(2) concentration decreased.The reduced pressure began to be consistent when adding 10%concentration of CO_(2) or N_(2).For the 40 mm venting diameter,the value of reduced pressure when added CO_(2) is slightly lower than that of N_(2),from 6% to 8%.For the 60 mm venting diameter,with the increase of CO_(2)/N_(2) concentration,the reduction of the reduced pressures are basically the same,and when the added concentration is no more than 8%,it has little influence on the amplitude reduction of the system reduced pressure.According to the TGA curve,in the heat flow conditions of N_(2) atmosphere and CO_(2) atmosphere,the pyrolysis process of lycopodium began to show significant differences around 370℃.The pyrolysis rate of lycopodium in CO_(2) atmosphere was faster than that in the N_(2) atmosphere,so the presence of CO_(2) in this process promoted the pyrolysis of lycopodium.With the further increase of pyrolysis temperature,the inhibition effect of CO_(2) on the pyrolysis of lycopodium powder began to show gradually.