| The combustible dust explosion is a common accident in metal processing,wood processing,grain processing,mining,chemical industry and other industries.It is easy to cause secondary explosions or multiple serial explosions,resulting in heavy casualties and property losses.heavy casualties and property losses.According to the statistics of dust explosion accidents in China in recent years,the proportion of metal dust explosion accidents has reached 43%.This paper selects the typical polishing aluminum dust,based on the polishing aluminum dust explosion characteristic parameters and the propagation law,the flameless explosion venting technology and mechanical isolation technology to prevent secondary explosion are studied.The flameless explosion venting device and explosion isolation device are designed for the dust removal system in polishing workplaces.It has important economic and social significance for improving the safety of the polishing process in industrial places and reducing the loss of people’s lives and property.The main results are as follows:(1)Using 20 L dust explosion characteristic test system and dust cloud ignition energy test system,the explosion characteristic parameters of polished aluminum dust are tested.The result shows that the lower limit of explosion concentration is between30g/m~3 and 40g/m~3,the maximum explosion pressure is 1.00 MPa,the maximum pressure rising rate is 91.00MPa/s,the explosion index was 24.70MPa?m/s,and the minimum ignition energy is 12.5m J.These explosion characteristic parameters can provide theoretical basis for the design of the flameless venting device.(2)The explosion pressure and flame propagation of polished aluminum dust in the pipe of dust removal system was studied by explosion test platform of self-made dust removal system.Under the conditions of this test,the average pressure inside the dust removal chamber reached 0.335 MPa.In the process of explosion propagation,the arrival time of shock wave was faster than the arrival time of flame,and the maximum flame propagation speed reached 111m/s.(3)Based on the analysis of pressure venting theory and flame elimination mechanism,according to the measured parameters of dust explosion characteristics,the cylindrical and fan-shaped flameless venting devices were designed.The performance verification tests of the devices were carried out on the explosion test platform of the dust removal system.The devices were successfully eliminate flame,and the external shock waves collected were all small,less than 5k Pa in the distance of 5m.(4)Based on the theoretical analysis of the explosion isolation technology principle of the pipe in the dust removal system,according to the explosion pressure and flame propagation law of polished aluminum dust,the rotary explosive isolation device was designed.According to the results of the explosion isolation test,the structure of the device was improved,and the improved rotary explosion isolation device was tested for its flameproof performance.No explosion flame was detected at the back end of the device,and the explosion was isolated successfully. |
