Thermodynamic self-consistent dynamic model of wood dust explosion

HU Taoping;YU Zi;GUO Lu;XU Changyan;College of Science,Nanjing Forestry University;College of Materials Science and Engineering,Nanjing Forestry University;

wood dust;;dust explosion;;maximum explosion pressure;;dynamic model;;thermodynamic self-consistency

According to the laws of thermodynamics and the dynamics of chemical reactions,a thermodynamic selfconsistent dynamic model of wood dust explosion was developed by considering the thermodynamic effect of reaction products and the heat absorption effect of wood dust. The experimental data were simulated based on this model,and the simulation results were compared with those of the existing theoretical models. The results showed that,for the different wood dust concentrations and wood dust particle sizes,the heat absorption of reaction products and wood dust in 20 L explosion sphere increased with the rapid increase of temperature. Therefore,the maximum pressure of the wood dust explosion was decreased,which led to that the theoretical simulation results of maximum explosion pressure were highly consistent with the experimental data. The problem of large deviation between theoretical calculation and experimental data fitting in the existing theoretical models was solved successfully. At different dust concentrations,the maximum explosion pressure calculated by this model did not increase monotonically with the increase of dust concentration. As a matter of fact,the maximum explosion pressure reached a certain concentration in the middle,which was consistent with the test results. Under different dust particle sizes,the fitting degree of explosion pressure evolution and test data simulated by this model was much higher than that of the existing models,and the maximum explosion pressure value was very close to the measured data. Furthermore,the ratio of molecular distance to molecular diameter was calculated using the thermodynamic self-consistent dynamic model of wood dust explosion.During the whole explosion,the ratio was between 10.6 and 11.2,that is,the molecular distance remained more than10 times of the molecular diameter. It was shown that the gas molecular distance satisfied the ideal gas model,which fully verified the thermodynamic self-consistency of this model. The results of the dynamic model research of wood dust explosion were of great significance to the estimation for the discharge area of the dust collector,the feeding bin and the transmission pipeline,the selection of the corresponding flameproof device,and the selection of the thermal sensor and spark detector on the surface of the processing equipment and the inner wall of the pipeline. The results of this study also had the theoretical merit for the research and development of explosion protection,and the disaster reduction technology of dust explosive equipment in the fiber board production line.