Study On The Combined Coagulation Of Electric And Turbulent Flow Of Fine Particles And Enhanced Removal Performance

The electrostatic precipitator(ESP)has low efficiency in removing submicron particles.Coagulation technology,as a fine particle pretreatment technology,uses an external effect to agglomerate and grow fine particles,increase the average particle size,and make it easier to remove by subsequent dust removal equipment.It is an effective means of enhanced removal.However,the coagulation efficiency of a single coagulation technology is limited.Aiming at the particle charging mechanism and coagulation mechanism in the electric/turbulent composite coagulation process of fine particles,this paper used a combination of numerical simulation and experiment to study the effects of different structural parameters,discharge parameters and flue gas parameters on corona discharge and particle charge.On this basis,the coagulation characteristics of charged particles in the turbulent flow field were studied,and efficient particle charging,coagulation and removal methods based on the coordinated regulation of multiple fields such as voltage,temperature and flow rate were obtained.(1)Establishment of electrical/turbulent composite coagulation physical model: In order to simulate the composite coagulation process of charged particles with different diameters in the turbulent flow field in the condenser,the Brownian coagulation model of Smoluchowski,Williams and Loyalka’s Coulomb coagulation model of heteropolar charged particles and Saffman and Turner’s turbulent coagulation model were combined to obtain a physical model that can describe the coagulation process of fine particles.The accuracy of the model was verified by comparison with experimental results.(2)Numerical study of particle charging characteristics: In order to reveal the influence of structural parameters and operating parameters in the bipolar particle charger on the charging characteristics of particles,the effects of different needle tip angles,power supply voltages,and temperature on the charging characteristics of particles were studied.And the reasons for the influence of various factors on particle charging were explored.The results show that the corona discharge effect is the best when the angle of the tip of the puncture electrode is 90°;when the power supply voltage rises,the particle charge increases,but when the power supply voltage rises further,the particle charge growth rate drops;high temperature environment brings significant increment on the charge of the particles,and the gap between the positive and negative corona charges also increases.(3)Numerical study on the coagulation characteristics of charged particles:In order to reveal the influence of various operating parameters in the condenser on the coagulation characteristics of charged particles,the effects of different voltage matching forms,temperatures,and intake flow rates on the coagulation of charged particles were studied.The reasons for the coagulation of charged particles that are affected by various factors are explored.The results show that when the applied positive voltage is 29 k V and the negative voltage is-35 k V,the agglomeration efficiency of particles measures up to the maximum value;high temperature environment brings the increasing particle agglomeration effectiveness;with the rising air velocity,the particle agglomeration effectiveness drops.(4)Experimental research on electric/turbulent composite coagulation and enhanced removal performance of fine particles: The electrical/turbulent composite coagulation and enhanced removal experimental system was designed,and a comprehensive experimental platform was built.The influence of power supply voltage and temperature on particle charging is studied;the influence of different voltage matching forms,temperature and intake flow rate on the condensation of charged particles is studied.The error between the experimental and simulation results is within 12%,which proves that the numerical simulation method is reliable.