Experimental And Numerical Simulation Research On Dust Explosion Of Bucket Lifter

As the most widely used equipment in vertical grain conveying system,bucket elevator is prone to produce a large amount of grain dust when it works.Once dust explosion occurs,it will cause a large number of casualties and property losses.Therefore,it is urgent to study the law of grain dust explosion in bucket elevator.Based on the theoretical analysis,experimental measurement and numerical simulation,the explosion characteristics of grain dust in bucket elevator are measured by 20L spherical dust explosion experimental instrument.On this basis,Eddy Break Up(Vortex Breaking)model is used to simulate the explosion process of grain dust in bucket elevator by CFD software.The results are as follows:Firstly,an experimental study on the bucket elevator of a grain processing enterprise in Wuchang City was carried out.The grain dust inside the bucket elevator was taken as the experimental sample.The particle size distribution of the dust was measured by laser particle size analyzer.The lower limit concentration,maximum explosion pressure and maximum explosion rate of dust explosion were determined by 20L spherical dust explosion experimental instrument.The explosion was summarized.The relationship between the pressure and the explosion rising rate and the dust mass concentration,and according to the classification of dust explosion hazard,the grain dust explosion hazard was identified.Secondly,the process of grain dust explosion in bucket elevator is simulated by CFD software,and the pressure variation law is obtained.The reliability of the measured parameters is verified by experiment.The results show that the experiment and numerical simulation fit well.Finally,the dust explosion process was simulated by changing the structure(aspect ratio),dust mass concentration and ignition position of bucket elevator.The temperature,velocity and pressure changes of bucket elevator at different time were obtained.The relationship between the length-diameter ratio,dust mass concentration and ignition position and grain dust explosion was revealed.The simulation results show that:With the increase of the length-diameter ratio of the bucket elevator,the peak temperature,velocity and pressure of dust explosion increase continuously;within the mass concentration range of 300 g/m~3-700 g/m~3,the maximum pressure is positively correlated with the mass concentration,while within the mass concentration range of 700 g/m~3-900g/m~3,the maximum pressure is negatively correlated with the mass concentration;the ignition conditions in the middle part of the bucket elevator have a promoting effect on the dust explosion rate and the explosion pressure.The peak value has no promotion effect,and the bottom ignition condition will produce a greater peak pressure.