Experimental Study On Combustion And Explosion Characteristics Of Drug Dust Ignited By Electrostatic Discharge

The dust explosion accidents in the pharmaceutical industry have always occurred,especially the electrostatic discharge(ESD)has accounted for a certain proportion,but the related research is very few.Based on this,this paper takes the intermediates of organic synthetic drugs of a pharmaceutical company as the research object,uses the laboratory electrostatic spark sensitivity instrument,high-voltage spark generator,high-speed camera system and circular semi closed vertical test tube designed by the research group to study the electrostatic discharge spark law,electrostatic sensitivity of drug dust samples and its combustion and explosion characteristics The research includes the following aspects:(1)Under the condition of electrode gap of 0.5mm and discharge voltage of 1507V,the process of spark generation and extinction was photographed by using high-speed camera system.The time from spark generation to discharge channel breakdown was only 0.074ms,and the duration of the whole discharge process was about 1.408ms.The results show that the electrode gap and material have obvious influence on the spark diameter,and the spark diameter decreases with the increase of pressure.In addition,the environmental wind speed,temperature and humidity have little influence.(2)Study on the basic characteristic parameters of drug dust.Using particle size distribution tester,scanning electron microscope,20 liter spherical explosive device,dust layer/dust cloud ignition temperature test device,the median diameter of the powder sample is 12.65μm;The minimum ignition temperature of dust layer is higher than 200℃,and the minimum ignition temperature of dust cloud is 550℃;respectively;the lower explosion limit is between 30-40g/m~3;the limiting oxygen concentration is 11%;the maximum explosion pressure is 0.72mpa,and the corresponding explosion index is15.76MPa·m/s,according to the relevant standards,the powder sample belongs to the dust with explosion risk,and the explosion level is st1.(3)Study on electrostatic sensitivity of powder samples.The sensitivity parameters of powder electrostatic discharge spark:the critical initiation voltage of electrostatic spark sensitivity is 2.7KV,the explosion energy is about 56m J;the minimum ignition energy of powder with inductance is 1m J<E<m J,while that without inductance is 3m J<E<10m J,the former is significantly higher than the latter.(4)Study on flame propagation law of powder ignition.The flame propagation of powder explosion is mainly divided into preheating stage,flame propagation stage and flame extinction stage.The whole process lasts for 734.08 ms.The experimental results show that the increase of powder injection pressure makes the dust cloud environment more uniform,which is conducive to ignition;increasing ignition energy directly shortens the explosion preheating time,while the mass concentration has the opposite effect.