| Coal mine dust seriously restricts the safe and sustainable development of the coal industry,especially the respiratory dust seriously affects the health of workers.Therefore,there is an urgent need to develop high-efficiency fine particle removal technologies.The basic principle of ionized rainfall technology is to charge some of the aerosol in the air.These electrostatic fields with electric sol particles have a polarization effect on clusters of other neutral water molecules,resulting in non-contact electric field cohesion of the charged molecules with polarized water molecules,which promotes the coagulation rate and promotes the formation of rainfall.In this paper,the mechanism of charged droplet growth and the mechanism of particle charge condensation were studied.The growth process of water droplets under ionization conditions and the influence of ions on the relative humidity in the climate chamber were studied experimentally.It is verified that it is feasible as a dust removal method based on ionized rainfall,and provides a basis for the application of ionized rainfall method to dust removal technology.Firstly,the mechanism of droplet growth and particle charge coagulation in the presence of ions is theoretically analyzed.It shows that the gas-liquid two-phase discharge process contains a large number of active components such as high-energy hydrated electrons,hydrogen radicals and hydroxyl radicals.Both water molecules and O2 molecules in the air have strong electronegativity,and it is easy to adsorb electrons to form negative ions H2O-and O2-,and the polarization of the particles will attract ions in the environment to the surface of the particles.The increase in polarization ability causes the ions to move more strongly toward the particle surface,causing the particles to cohere.The presence of water vapor significantly enhances the charge coagulation effect of the particles.Secondly,the coagulation effect of ions on water vapor in ionized and non-ionized states under supersaturated and unsaturated conditions was studied.The results showed that the condensation process of water vapor in supersaturated natural state was relatively slow,but under the condition of supersaturated ionization,the size of water droplets increases rapidly.After 30 min,the diameter of water droplets can grow to about 3 mm under the condition of negative ion concentration of 2.76×106cm-3.And the size of the water droplets is affected by the concentration of negative ions,and the greater the concentration,the faster the growth rate of the water droplets.The increase in relative humidity of the air does not change the spatial distribution of negative ions.The increase in relative humidity of air under unsaturated ionization conditions is lower than that of natural conditions.The calculated moisture content at the same time indicates that the water vapor content in the ionized state is always lower than the natural condition.The condensation amount of water vapor increases with the increase of humidity.At the same time,under the condition of higher humidity,the condensation efficiency of negative ions on water vapor is higher,and it is easier to promote the condensation of water vapor,so as to promote the occurrence of sedimentation.Thirdly,the paper moisture absorption experiment was designed,and the paper hygroscopicity change under dust-free environment was studied.The results show that the moisture absorption of paper per unit area increases with the increase of relative humidity.When the relative humidity is more than 70%,the moisture absorption of paper increases with the increase of negative ion concentration.At the same time,by adding the micro-dust particles into the experimental environment,the changeoftheunitpaperweightissaturatedstate<saturation+dust state<saturation+ionization state<saturation+dust+ionization state,indicating that ionization conditions can promote the sedimentation of fine dust particles,and provides the condition for the dust removal technology. |
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