Study On The Removal Of Fine Particles From Coal-fired Flue Gas By An Electrostatic Precipitator Enhanced By Adding The Turbulent Agglomeration

Due to the action of combustion,condensation and other mechanisms,the combustion process of coal produces a large number of fly ash fine particles which makes coal-fired power stations become an important source of fine particulate matter.It is precisely because the excessive emissions of fine particles have an increasingly serious impact on the atmospheric environment and human health,it is also particularly important to research and development more efficient fine particulate emission control technology of coal-fired power plant.In order to obtain the preliminary law of turbulent agglomeration,the commercial fluid dynamics calculation software Ansys Fluent was used to simulate the relevant parameters in the turbulent agglomeration process of fine particles.The actual coal-fired flue gas condition was simulated by the fine particle generating device on the coal-fired hot pilot test platform.After the turbulent agglomeration generating device worked,a series of analytical testing equipment such as the electrical low pressure impactor(ELPI),the smoke sampler,and the field emission scanning electron microscopy(FESEM)were used to study the changes of fine particle parameters such as fine particle concentration,particle size distribution,and microscopic morphology.The numerical simulation method was used to analyze the turbulent effects of different factors such as structure,quantity and arrangement of the turbulent vortex sheets.It was found that the cross-shaped and Z-shaped turbulent vortex sheets were more conducive to the development of turbulent kinetic energy of the flow field;When the column spacing of vortex sheets was 75 mm and the line spacing of vortex sheets was 50 mm,the development of turbulent kinetic energy of the flow field was at the highest level;The number of vortex sheets used in the turbulent device needed to be at least 4 pairs to ensure the full development of the turbulent kinetic energy of the flow field;No matter the vortex sheets were arranged side by side or staggered,both of them had obvious effects on the improvement of the turbulent kinetic energy of the flow field,while the improvement effect of the in-line arrangement of the vortex sheets was poor.Carried out experiments of the turbulent agglomeration and the enhancing effect of the removal of fine particles by the electrostatic precipitators with the turbulent method.It was found that the coupling of the cross-shaped and Z-shaped vortex sheets increased the agglomeration efficiency of the fine particle from 20% to 35%;The removal efficiency of fine particles by the electrostatic precipitators increased from 73% to 89%;the removal efficiency of total dust by the electrostatic precipitators increased from 81% to 89%.The coupling of turbulent and chemical agglomeration further increased the removal efficiency of fine particles by the electrostatic precipitators to more than 90%,It also further improved the removal efficiency of total dust to 95%,What's more,there has the internal coupling mechanism between turbulent agglomeration and chemical agglomeration,the coupling agglomeration effect of them is better than the simple superposition of the agglomeration effects when the two are applied separately.Numerical simulation of turbulent agglomeration based on local flue before the electrostatic precipitators of a 300 MW coal-fired power plant was carried out,including the setting of the deflector sheets in the local flue before the electrostatic precipitator,and also including the setting of gas distribution plate and vortex sheets in the expansion part of the inlet section of the electrostatic precipitator.Based on this,a kind of "overall uniform flow,local turbulent flow" vortex sheets setting method was proposed,which provided a significant guide for the future industrial applications.