木质粉尘燃爆的爆炸指数理论评估

Theoretical evaluation of explosion index for wood dust explosion

从燃烧化学反应动力学出发,结合热力学原理以及气体分子动理论,提出了木粉燃爆的动力学理论模型,对木粉燃爆试验的测量数据进行了理论计算。在不同木粉浓度以及不同木粉粒径下,将本模型的计算结果与已有模型的理论计算结果对比。结果表明:本模型的理论结果更接近试验测量结果,最大爆炸压力以及最大压力上升速率理论计算值与试验数据的平均偏差仅为9%。此外,利用本理论模型计算了最大压力上升速率随连续木粉浓度的变化曲线,得到在木粉质量浓度845 g/m3附近,爆炸指数的极大值为14.57 MPa·m/s。爆炸指数大于10 MPa·m/s的木粉质量浓度为330～1 945 g/m3,在此区间,利用本理论模型可以对不同浓度木粉的爆炸指数进行理论估算。研究得到的相关结果对试验测量以及实际生产中的燃爆防控技术均有理论指导意义。

In the existing theoretical model of wood dust combustion and explosion parameters,the theoretical calculation only roughly simulated the evolution trend of explosion pressure over time,and there was a large deviation between the theoretical calculation result and the experimental result,which included the maximum explosion pressure and the increase rate of pressure.Based on the kinetics of combustion chemistry,the theory of thermodynamics and the theory of gas molecular dynamics,the dynamical theoretical model of wood dust explosion was proposed.According to the experimental conditions,the newly developed model was used to theoretically calculate the maximum explosion pressure and the pressure increase rate.The results were compared with the theoretical calculation results by using the existing model under different wood dust concentrations and different wood dust sizes.The comparison results indicated that the results calculated using the newly developed model were closer to the experimental results.The average deviations of the maximum explosion pressure and the maximum increase rate of pressure between this calculation and the experimental data were lower than 9%.In the case of different wood dust concentrations and different wood dust sizes,using the same experimental data,the maximum explosion pressure,the maximum increase rate of pressure and the explosion index of wood dust explosion were also calculated theoretically.Compared with the experimental measurement data,the new model was better than that of the existing theoretical model.In addition,this new model could be used to calculate the curve of the maximum increase rate of pressure with the continuous change of wood dust concentration.The results showed that the maximum pressure increased firstly and then decreased with the increase of wood dust concentration,and the maximum value appeared at the intermediate wood dust concentration.The maximum value of the explosion index calculated was 14.57 MPa ·m/s,and the corresponding wood dust concentration was 845 g/m^3 .The concentration range of wood dust with an explosion index of over 10 MPa ·m/s was 330-1 945 g/m^3 .In this interval,the explosion indexes of different wood dust concentrations can be accurately confirmed by this new theoretical model.In conclusion,the newly developed model had high consistency with experimental data,which can accurately predict the possible explosion index of wood dust explosion.