Evaluation Of Explosion Risk Of Aluminum Powder In Polishing And Polishing Workplace And Study On Combustion And Explosion Characteristics In Confined Space

With the rapid development of the industrial level,the number of labor-intensive enterprises has increased,and a large number of processing links that require polishing and grinding operations have emerged,which will generate a large amount of dust.These dusts are extremely fine-grained and have the characteristics of large specific surface area and high activity,which can easily cause combustion and explosion.In recent years,dust explosion accidents have become more frequent.In these dust explosion accidents,metal dust,especially aluminum dust explosions account for a large proportion,which will cause huge casualties and economic losses.In this paper,the theoretical analysis,laboratory tests and numerical simulation are used to systematically study the causes of aluminum powder explosion accidents in the polishing and polishing workplace.The paper achieved the following research results:(1)Using the sharp point mutation theory,the external factors such as the person,machine,management,and environment that caused the aluminum powder explosion and the internal factors of the aluminum powder oxidation energy accumulation were used as the two control variables of the explosion accident to construct the aluminum powder explosion accident The cusp catastrophe model discusses the external and internal causes of aluminum powder explosion accidents,and obtains 11 main influencing factors of aluminum powder explosion and their weight ranking,and establishes the risk of aluminum powder explosion in such workplaces.Index system for sexual evaluation.Combining catastrophe theory and fuzzy mathematics,the danger degree of the workplace is studied,the target evaluation system is established,and the layered recursive method is used to obtain the value of the membership function of the risk of external unsafe factors.(2)The minimum ignition temperature of the aluminum dust cloud was studied through experiments,and the relationship between the micron-level aluminum powder particle size and the minimum ignition temperature was revealed.As the particle size decreases,it decreases.The minimum ignition temperature of aluminum dust cloud decreases first and then increases with the increase of aluminum powder concentration.When the concentration of aluminum powder is 4.55kg/m3,the minimum ignition temperature of aluminum dust cloud is 585?.The effect of particle size,concentration,and pressure on the minimum ignition temperature was further studied.On the basis of the optimal dispersion pressure and sensitive concentration,the relationship between the aluminum powder particle size and the minimum ignition temperature of aluminum powder was obtained.(3)Using the 20L spherical explosive device,the orthogonal experiment method was used to study the effect of particle size and moisture content on the lower explosion limit of aluminum powder;it is concluded that the sensitivity of the particle size,ignition delay time,and concentration to the explosion characteristics is sequentially reduced.The microstructure of the explosive products was analyzed,and the results showed that the unreacted aluminum powder clustered together in a flocculent form under a relatively low explosion pressure;the aluminum powder explosion products were more dispersed under a larger explosion pressure;the aluminum powder explosion process was mainly controlled by oxygen diffusion and melting of aluminum powder particles at the same concentration.(4)Using numerical simulation,taking the dust collector of Kunshan aluminum powder explosion accident as the research object,the dust concentration distribution in the bag dust collector was studied,and the concentration distribution of aluminum powder suspended above the dust collection barrel and the aluminum in the dust collection barrel were obtained.The temperature field distribution of the self-heating reaction after the powder gets wet.Combined with the minimum ignition temperature and lower explosion limit of the aluminum powder obtained by the experiment,a safety state evaluation model of the dust collector of the dust collector is established,which provides an experimental basis for monitoring the temperature and dust concentration of the dust removal system.