Experimental Research On The Flame Propagation And Thermal Analysis Kinetics Characteristics Of Corn Starch Dust

Grain dust exist widely in food production, processing, storage, transportation and so on. Due to its high organic composition content and smaller particles, the grain dust has higher explosion risk. It is a serious threat to the food industry safety production. Dust flame propagation process is an important transformation process of the dust cloud from combustion to explosion. So the experimental study of flame propagation characteristics will provide effective reference for the study of dust explosion hazards evolution process. It will also promote the research of the dust explosion suppression mechanism.In this study, the flame propagation characteristics and thermal analysis kinetics characteristic of the corn starch dust have been researched. The high-speed camera system and fine thermocouple system were used to research the flame shape, the flame propagation speed and flame temperature variation in the opening vertical pipe. And meanwhile, the experimental study for the corn starch combustion characteristics has been done with the simultaneous thermal analyzer and discussed the influence for the flame propagation by combustion process and behavior. Conclusions are as follows:(1) The flame propagation process of corn starch dust cloud in the vertical pipe opening can be divided into slow flame propagation process and flame acceleration propagation process. Because of the turbulent flow in the pipeline, the flame shape under different working conditions are not the same and the degree of flame front is irregular.(2) When the concentration of corn starch cloud is lower, the flame propagation speed and flame temperature increases with the increase of concentration of dust cloud. When the concentration is 0.632 kg/m3, the flame propagation speed and the flame temperature are the highest. And then with the increase of concentration of dust cloud, the flame propagation speed and flame temperature are slowly decreasing. When the average particle size is 45 μm the flame propagation speed in the pipe and the maximum flame temperature were higher than the average particle size 33 μm and 64 μm.(3) Combine the TG and DTG curves of corn starch dust, the combustion process in the air is divided into preheating volatile drying stage, transition stage, fast pyrolysis combustion phase, coke burning stages. For solving the corn starch dust combustion reaction kinetic parameters, use FWO method to calculate the average activation energy of corn starch.(4) Heating rate changes will affect the combustion characteristic of corn starch in the air. With the increasing of heating rate, the combustion characteristic parameters and combustion discriminant index value of corn starch are moving to the side of high temperature. The performance of the ignition properties and volatile out improve. It is prone to burning and conducive to the stability of flame propagation.(5) Corn starch dust combustion process has great influence on the flame propagation process. The evaporation process in the preheating dry stage, leading to the flame propagation speed through a long time slow propagation process in the early stage of flame propagation. At the same time cause the corn starch volatiles rate and concentration distribution are different and lead to the shape of flame propagation process of irregular change.