Investigation Into The Suppression Effect Of Different Powders On Explosion Of Polyethylene Dust

In recent years,with the vigorous development of polyethylene industry,polyethylene dust explosion accidents happen one after another,causing serious casualties and property losses.At present,scholars at home and abroad have carried out a lot of research on the explosion characteristics of polyethylene dust,but there is a lack of research on the explosion suppression characteristics of polyethylene dust,especially the lack of efficient and convenient explosion suppression powder on the explosion suppression characteristics of polyethylene dust.Based on this,the effects of four different powders(Na HCO₃,Na₂C₂O₄,KHCO₃ and K₂C₂O₄)on the explosion pressure,flame propagation characteristics,minimum ignition temperature and minimum ignition energy of polyethylene dust were studied by using the pipeline explosion test system,the minimum ignition temperature test system and the minimum ignition energy test system,then the inhibition mechanism was analyzed.The main contents of this paper are as follows:(1)The effects of four powders with the same particle size on the explosion pressure and flame propagation characteristics of 16.7?m polyethylene dust were studied by using the pipeline explosion test system.The results show that the four kinds of powder have a certain inhibition effect on explosion pressure and flame of polyethylene dust,while the inhibition effect of KHCO₃ is greater than the other three kinds of powder.It is found that the inhibition effect of the bicarbonate salt powder is stronger than that of the oxalate powder,and the inhibition effect of the potassium salt powder is slightly stronger than that of the sodium salt powder.The effects of three particle sizes(80 mesh,200 mesh,400 mesh)KHCO₃ powder on the explosion pressure of polyethylene dust and explosion flame propagation characteristics show that the finer the particle size of the explosion suppressant,the stronger the inhibition effect.(2)The effects of four inhibitors of the same particle size on the minimum ignition temperature and minimum ignition energy of 16.7?m polyethylene dust were studied by using the dust cloud minimum ignition temperature test system and dust cloud minimum ignition energy test system.The results show that the minimum ignition temperature and the minimum ignition energy of polyethylene dust could be significantly increased by four kinds of powders,and the inhibition effect increases with the concentration of the powder inhibitor,while inhibition effect of KHCO₃ is the best.It is found that the inhibition effect of bicarbonate powder on the minimum ignition temperature and energy of polyethylene dust cloud is stronger than that of oxalate powder,and the inhibition effect of potassium salt powder on the minimum ignition temperature and energy of polyethylene dust cloud is stronger than that of sodium salt powder.(3)The inhibition mechanisms of the four inhibitors on the polyethylene dust explosion were explored by thermal decomposition characteristics(TG/DSC)analysis,material composition analysis(XRD),particle specific surface area analysis,and chemical suppression analysis.The results show that the four powders can be decomposed to produce inert substances CO₂ and H₂O,which can shield the heat conduction and radiation,dilute the concentration of combustible gas and oxygen in the reaction zone,at the same time,the thermal decomposition can effectively absorb the heat of the surrounding environment and produce inhibition effect.The pyrolysis of four inhibitors can produce some active groups which can effectively block the explosive chain reaction.It is found that the specific surface area of bicarbonate powder with the same particle size is larger than that of oxalate powder,and the endothermic effect of bicarbonate powder is larger than that of oxalate;the endothermic effect of potassium salt powder is larger than that of sodium salt powder,and the endothermic effect of KHCO₃ is larger than that of the other three powders.