Experimental Study On Factors Affecting Particle Static Electricity In Multiscale Devices

The pneumatic conveying of solid particles was widely used in mining,chemical industry,food,agriculture and other industries for various applications such as catalytic reaction,drying,and mixing.The electrostatic charging of particles in the pneumatic conveying system led to serious problems in the project,such as the accumulation of particles in the pipeline,which led to blockage of the pipeline,and even the explosion accident caused by static electricity,attracted attention of people.Therefore,understanding the mechanism of static electricity generation when particles were transported in pipelines was a great significance to reduce the static electricity generation of particles in pneumatic conveying systems and electrostatic accidents in industry.In this paper,the mechanism of the charge generated by the sliding of single particles and the charging phenomenon in multi-particle pipeline transportation were studied,summarizing the influence of different factors on the charge generation of particles.Three scale experimental devices were carried out in this work.Firstly,the property of particles influenced in the static electricity generated by sliding was studied.After a comparative analysis of various factors,it was found that the static charge generated by the sliding of the particles increased first and then decreased as the roughness of the increase of sliding surface,and the maximum specific charge of log particles occurred when the roughness at 5-7?m.Under low roughness conditions,humidity had a significant effect on the static electricity of the particles.And particle sliding surface area,aspect ratio,etc.had a great influence on the charge generation.That was,the larger the aspect ratio of the particles,the greater the amount of triboelectric charge,and the larger the contact area of the same particles,the greater the amount of static electricity.In addition,the static electricity of the particles increased with the increase of the sliding distance,and the cumulative amount of the particles continued to increase.After sliding for 7 or 8 times,the static electricity carried by the particles reached the maximum value and remained constant.Besides that,in this paper,the electrostatic mechanism of multi-particle transport was studied in the laboratory pneumatic transport system device.The research showed that the static electricity of the particles increased during the repeated experiments in the pneumatic conveying system.After about five experiments,the amount of static electricity generated by the particles reaches the maximum value and remains constant.In addition,the charge density of different particles after mixing was greater than the charge density of a single material particle.In order to verify the application of laboratory research results in actual industry,experiments in the actual industrial scale silo circulation system was conducted,some factors that affected the generation of static electricity in conveyed particles in actual industrial production was studied.It was found that the greater mass flow rate of materials during transport,the smaller the charge-to-mass ratio of the material,and the greater the transport air flow,the greater the charge-to-mass ratio of the material.In this experiment,the longer the delivery pipe,the greater the charge generated by the material.