Experimental Study On The Synergistic Effect Of Desulfurization Wastewater Flue Evaporation And Water Mist Charge On Particle Agglomeration

To cope with the increasingly serious environmental problems,requirement of ultra-low emissions from coal-fired flue gas pollutants was put forward in China.Wet flue gas desulfurization together with dry electrostatic,as typical combination,can efficiently removal SO2 and particles in flue gas,at the same time,problems like desulfurization wastewater is difficult to treat and the fine particles removal efficiency is low still exist.Flue gas evaporation is not only an effective way to dispose of desulfurization wastewater,but also can promote the reunion of fine particles in flue gas,increasing the fine particles removal efficiency of dry electrostatic.Flue gas evaporation can realize desulfurization wastewater treatment and enhance dry electrostatic efficiency,however,due to the relatively low temperature of evaporation flue gas,desulfurization wastewater is difficult to dry,which easily cause the corrosion,scaling and blockage of the flue,limiting the popularization and application of the technology.To solve the above problems,on the basis of the previous study of charged water mist promoting the agglomeration of fine particles,this paper propose desulfurization wastewater charged evaporation to promote fine particles agglomeration,enhancing dry electrostatic efficiency.Ions in the waste water promote droplets charged,charged droplets are easy to break,which contributes to evaporation and charge transfer,thus synergistically realizing rapid evaporation of desulfurization wastewater and efficient agglomeration of fine particles,and improving the removal efficiency of fine particles.Based on this,this article set up desulfurization wastewater electric evaporation thermal test system to promote fine particles agglomeration.CaCl2 solution are adopted to simulate the pretreated desulfurization wastewater.Electrical low pressure impactor(ELPI)is used as the main analysis instrument.Characteristics of evaporation and particles size distribution and charge of drying product of desulfurization wastewater under different conditions are firstly studied;Then,by adding fly ash to simulate fine,the effects of desulfurization wastewater electric evaporation on the agglomeration rule and charge transfer characteristics of fine particles under different conditions are studied,also the morphology of agglomerated particles is analyzed.The main research conclusions are as follows:Studies on the charged evaporation characteristics of desulfurization wastewater under different conditions,particle size distribution and charge of drying products show that,the evaporation speed of desulfurization wastewater is slowed down due to the presence of CaCl2 salts in the wastewater.Increasing the charge voltage and the atomization pressure and decreasing the evaporation water quantity are benefit to the evaporation rate of desulfurization wastewater.Due to the charged droplet evaporation and crushing mechanism and the lower limit of ELPI test,increasing the charged voltage will reduce the number of particles in the measurement range while increasing the atomization pressure will increase the number of particles,the droplet secondary fracture mechanism is different in the evaporation process.With the desulfurization wastewater electric evaporation process,some of the charge carried by the droplet can be transferred to the dried particles.Studies on the agglomeration rule of fine particles by charged evaporation of desulfurization wastewater show that,within the experimental range,the charged droplet is more conducive to promoting the agglomeration of fine particles in flue gas,no matter for desulfurization wastewater or water,and the higher the charged voltage is,the more obvious the agglomeration effect of fine particles is.Compared to water,the number of particles decrease more obviously after desulfurization wastewater being charged in addition to 0.04 ?m particle size.Increasing atomization pressure can promote the agglomeration of fine particles,while atomization water has little effect on the agglomeration of fine particles.With the increase of Cl-concentration,the agglomeration effect of desulfurization wastewater charged evaporation on fine particles is weakened.Further analysis of the particle morphology after the agglomeration show that the desulfurization wastewater charged evaporation have an obvious agglomeration effect on the fine particles,particles of different sizes adhere to each other to form irregular particle groups.The charge transfer rules after desulfurization wastewater electric evaporation under different conditions show that,under experimental conditions,when the particle size is greater than lum,the average charge of a single particle changes greatly with the increase of particle size.With the increase of the charge voltage and the concentration of Cl-in the desulfurization wastewater and the decrease of atomization pressure,the average charge of single particle increases.The average charge of a single particle increases with the increase of evaporation water.The above research conclusions provide basic data and theoretical support for the industrial application of electrostatic dust removal technology enhanced by charged desulfurization wastewater evaporation promoting fine particle agglomeration,which is of great significance for the low-cost and high efficient treatment of desulfurization wastewater and the enhanced fine particle removal effeciency of dry electrostatic.