酒精蒸气/烟草粉尘两相混合体系最小点火能试验研究

Experimental study on the minimum ignition energy of hybrid mixtures of alcohol vapor and tobacco dust

在烟草加工的加香工序,挥发的酒精和搅拌混料产生的烟草粉尘形成气粉混合体系,其燃爆特性相较于单相烟草粉尘有较大变化。对20 L爆炸球进行了部分改造,可完成20℃~80℃环境温度、100%LEL以下酒精蒸气浓度、最大2 J电火花能量组合的气粉混合物的最小点火能测试。选用烘丝和加香烟草粉尘做对比,探究了环境温度和酒精蒸气浓度对酒精蒸气/烟草粉尘两相混合体系点火能的影响规律。结果表明:相同环境温度下,加香烟草粉尘的最小点火能比烘丝烟草粉尘低;加香粉尘、烘丝粉尘及混合体系的最小点火能随环境温度变化的趋势一致,均随温度的升高而降低;加入10%LEL的酒精蒸气后,相同温度下气粉混合体系的最小点火能低于单相烟草粉尘。随着环境温度的升高,二者的差值逐渐减小,酒精蒸气诱导烟草粉尘最小点火能降低的能力逐步减小甚至消失;在电点火条件下,当酒精蒸气浓度低于50%LEL时,气粉混合体系较难被点燃,当酒精蒸气浓度高于75%LEL时,混合体系较易被点燃。

In the flavoring procedure of tobacco processing, the combustion and explosion characteristics of the gas-dust mixtures formed by dust from stirring tobacco and volatile alcohol are significantly different compared with single tobacco dust. The 20 L explosive device is partially modified to test the minimum ignition energy test of the gas-dust mixture with the combination condition of ambient temperature of 20 ℃~80 ℃, the alcohol vapor concentration below 100%LEL and the maximum 2 J spark energy. The effects of ambient temperature and alcohol vapor concentration on the ignition energy of alcohol vapor-tobacco dust hybrid mixture system were investigated by comparing silk drying and flavored tobacco dust. The results show that the ignition energy of flavoring tobacco dust is lower than that of silk drying tobacco dust at the same ambient temperature. The ignition energy of flavored dust, silk drying tobacco dust and hybrid mixtures have the same trend with temperature, and all decrease with the increase of ambient temperature. With the participation of 10%LEL alcohol vapor, the minimum ignition energy of gas-dust mixture system is lower than that of single-phase tobacco dust at the same temperature. The difference gradually decreases and tends to be consistent with the increase of temperature, which indicates the ability of reducing the minimum ignition energy of tobacco dust induced by alcohol vapor gradually decreases or even disappears. Tests under electric ignition condition show that the gas-dust mixed system is more difficult to ignite when the alcohol vapor concentration is lower than 50%LEL, and the flavored tobacco dust is insensitive to ignition energy. The flavored tobacco dust is more sensitive to ignition energy when the alcohol vapor concentration is higher than 75%LEL.