Simulation And Dynamic Analysis Of Powder Centrifugal Compression Process

It is one of the effective methods to dispose of hazardous chemical leakage accident safely and efficiently to eliminate the toxic hazard in polluted objects and areas by spraying disinfectant.With the development of micro and nano technology,the powderdecontamination-agent in granular form has a great application prospect.The advantage of this lies in the large specific surface area of powder particles,which can improve the reaction speed with chemicals and improve the washing efficiency.In addition,this method can not only wash the contaminated ground in a short distance,but also wash the large area of contamination in a long distance by throwing the decontamination bomb.Powder-decontamination-agent needs to be filled in the container before being used.In order to fill the powder as much as possible in the container,the powder needs to be compressed.In view of the environmental pollution caused by powder spilling in the traditional powder hydraulic compression process,the research group proposed a new method of powder compression by centrifugal.Because the density distribution of powder in the compression process has an important influence on the subsequent airflow dispersion,but the powder is in the process of dynamic change during the compression process,the relevant parameters are difficult to obtain.And the compressed powder column is not completely compaction,it is difficult to take out and measure,so how to obtain the density distribution parameters of the powder has become a difficult problem.Therefore,this paper mainly focuses on the density and its distribution in the process of centrifugal compression of powder,integrated experimental and numerical simulation research methods to explore.In this paper,the density and its distribution in the process of centrifugal compression of powder were simulated by the discrete element method(DEM);The flow and compression parameters of five ultra-fine powders were measured,and the relationships between the parameters of the powders were analyzed;In order to evaluate the internal density distribution of compressed powder column,an experimental device for powder invasion resistance was designed and built independently,and the relationship between the internal resistance force of ultra-fine powder after centrifugal compression and centrifugal speed was investigated.This paper mainly focused on the centrifugal compression process of powder,the main research work and results are as follows:(1)The discrete element simulation results of powder centrifugal compression process were compared with the experimental data of actual powder centrifugal compression,the validity of this simulation process was verified.The density and its distribution law of the powder in the dynamic stage of centrifugal compression were analyzed,and the influence law of different compression modes on the density distribution of the powder was discussed.In addition,the effects of particle size,particle mixing and coefficient of wall friction on the density and its distribution of powder after centrifugal compression were investigated.(2)The basic physical properties,flow properties and compression properties of five ultra-fine powders were tested by powder testing equipment.The powder parameters were analyzed by principal component analysis(PCA),and two principal components were constructed to characterize the flow and static properties of powder respectively.(3)Through the dynamic analysis of the powder column in the centrifugal compression process,a mechanical equation was established which used to describe the centrifugal force of the powder column in the centrifugal compression process.According to the experimental data of centrifugal force and volume change of powder column during centrifugal compression,the Kawakita powder compression equation was used to describe it.(4)Considering that there was a certain relationship between the internal resistance force of powder and its density,a self-designed test equipment was used to test the change of intrusion resistance force with the penetration depth of compressed powder column,the analysis showed that the internal resistance force of compressed powder column could be used to describe the internal density qualitatively.On this basis,the influence of centrifugal speed,penetration depth and different positions on the internal resistance force of powder column were analyzed,an empirical equation was established which could be used to predict the internal resistance force of powder column at different speeds and heights,and verified by experimental data.The relevant research results could provide fundamental basis for the density and its distribution of compressed powder-decontamination-agent,and provide a reference for the subsequent dispersion process.