Nonlinear Electric Field Optimization Design And Experimental Study On Decarbonization Process Of Coal Fly Ash

Fly ash,as solid waste generated by thermal power generation,is an available resource.However,the excessively high carbon content in fly ash restricts its comprehensive utilization,So decarbonization is a research hotspot in the treatment of fly ash.Triboelectric separation is widely used in the technical field of fly ash decarbonization because of its simple process and economical efficiency.Traditional separation electric field mostly adopts the structure of parallel polar plates.During separation,particles with a small charge-to-mass ratio can’t be effectively separated due to the fixed electric field strength and cross-sectional flow rate between the plates;And the quality difference of fly ash will affect the charging effect of the particles,so that the constant electric field strength can’t meet the requirements of efficient separation.This paper proposes the application of a non-linear electric field,which uses a curved electrode plate boundary to form a separated electric field whose strength and direction change with changes in spatial position,and it is suitable for sorting particles with small charge-to-mass ratio and large charge range.By changing the profile structure of the parallel polar plate boundary,the separation electric field model of two different profiles is established,and then the mathematical model of the nonlinear electric field is established using the complex variable function.At different wind speeds,the distribution characteristics of the flow field in the electric field were obtained by Fluent numerical simulation of the gas flow field in the electric field.Comparing the gas flow fields of linear electric field structure and two non-linear electric field structures,the electric field structure suitable for particle separation is determined according to the characteristics of uniform flow field distribution and stable flow velocity.Combined with ANSYS simulation,the field strength variation law of the nonlinear electric field is obtained,which shows that the gas flow field in the linear electric field first enters a stable state.Its zone of uniform and stable flow velocity is long,where field strength is strong,so the linear one electric field is beneficial to the separation of charged particles.Through the CFD-DEM coupling calculation,the movement behavior of fly ash particles in the electric field was studied.Under the same conditions,the separation effect of different electric field structures were evaluated based on the results of particle separation in the electric field and the receiving tank.The results show that the separation effect of the nonlinear electric field is better than the linear electric field.Then study the influence of inlet wind speed and loading voltage on particle separation in three sorting electric fields,it is found that the separation effect of the linear two electric field increases with the increase of wind speed.The separation effect of the parallel plate and the linear one electric field increases first and then decreases,20 m/s is the optimal flow velocity.The separation effect of the three separate electric fields increases with increasing voltage.According to the discrete element results,the best separation electric field is linear one electric field.Finally,in linear one electric field,study the effects of particle feed and charge-to-mass ratio on separation.The best simulated feeding parameters are 7500 particles per second with a charge-to-mass ratio ranging from 1.1 to 1.2 nc/g.Based on the linear-electric field model,a non-linear electric field sorting system is established.A single factor experiment of wind speed and voltage was conducted with the LOI of the product collected on the positive and negative plates as indicators.The results show that the sorting effect of the linear one electric field increases first and then decreases with the increase of wind speed and the sorting effect increases first and then decreases slightly with the increase of voltage;under the same operating conditions,the product decarbonization rate of the linear one electric field is higher than Parallel plate electric field.The thesis contains 50 figures,6 tables and 89 pieces of references.