Hydrogen Inhibition In Wet Dust Removal System For The Treatment Of Aluminum Dust

During the process of polishing and buffing of aluminum slab,or during the production of aluminum powder,there will be lots of aluminum dust produced simultaneously,which will exist and disperse in the air.This kind of dust not only effects workers'healthy,but also can lead to aluminum dust explosion accident.Wet dust removal system can prevent dust explosion accident efficiently.However,there also exists the risk of hydrogen explosion accident.According to GB standards,wet dust removal system for the treatment of aluminum dust is forbidden in China.To solve the problem of hydrogen explosion accident associated with the wet dust removal system for the treatment of aluminum dust,it is essential to figure out the law for hydrogen production and inhibition.According to the law of hydrogen production reaction between aluminum dust and water,the tester for hydrogen production was developed.Embedded software was built in its control system.By using this software,settings of experimental initial parameters,self-control during adding reactant,real-time processing or display of experimental data were achieved.The impact factors of hydrogen production were studied,including aluminum dust particles,initial pressure in the reactor,reaction temperature and different mass ratios of aluminum dust to water.The results show that increasing temperature,decreasing initial pressure,reduction of mass ration of aluminum dust to water and decreasing aluminum particle size can promote the reaction between aluminum dust and water.The specific law for hydrogen production was figured out.On this basis,the three stages model for hydrogen production reaction were developed,including Alpha Reaction Stage(ARS),Rapid Reaction Stage(RRS)and Termination Reaction Stage(TRS).To achieve the goal of inherent safety of wet dust removal system,hydrogen inhibition experiments were carried out.Solutions of K₂Cr₂O₇?Na₂Cr₂O₇·2H₂O?Cr(NO₃)₃·9H₂O?CrK(SO₄)₂·12H₂O and CeCl₃ have significant inhibition effects on reactions between aluminum dust and water.Dichromate and chromate solutions can lead to the formation of Cr(OH)₃ layer on aluminum dust particles.Cerium solution can lead to the formation of Ce(OH)₃ layer on aluminum dust particles.Shirking core model can be used to describe the mechanism of reactions between aluminum dust and different solutions.As the concentration of these solutions increased,the chemical reaction rate constant decreased and the inhibition effect became better.Hydrogen explosion accident can be fundamentally prevented by using dichromate,chromate or cerium solutions instead of water.Inherent safety was achieved in wet dust removal system.And the economic input also decreased a lot.Original aluminum particles and aluminum particles after reacting with water or different kinds of solutions were characterized by using Lazer Particle Size Analyzer,Scanning Electron Microscope(SEM),Energy Dispersive Spectrometer(EDS),X-ray Diffraction(XRD)and X-ray Photo-electron Spectroscopy(XPS).The reaction mechanism and model were identified.The Hydrogen Inhibition Method(HIM)was identified.The safety design plan was studied based on those related research results.The wet dust removal system with the functions of automatic water supply and chain exhaust during polishing was developed.This technical measure can ensure that hydrogen explosion accident will not happen.Based on the hydrogen accumulation conditions when exhaust fans stopped working,to ensure the safety of wet dust removal system,hydrogen detectors were installed and connected to chain exhaust system or enforce exhaust system.The WBS-RBS-BN quantitative risk assessment model for hydrogen explosion accident of wet dust removal system was established.Corresponding quantitative risk assessment was carried out.The risk assessment results show that the safety-designed wet dust removal system could not only prevent the issues of dust explosion,but also figure out hydrogen explosion accidents in wet dust removal system.The HIM and safety-designed plan give some insight to the direction of hydrogen explosion prevention in wet dust removal system for China,and also support the revision of terms of GB standards related to combustible dust and wet dust removal system.