Research On Purging Type Charged Spray System And Its Application In Removal Of Flue Gas Particles

Wet desulfurization is the end treatment process of flue gas pollutants in coal-fired power plants,but its effect on the removal of fine particles is not ideal.Charged spray can promote the agglomeration and growth of fine particles while conventional charging methods are difficult to apply in high humidity environments.Based on this background,this paper designs a purge charged spray system and studies its spray charging characteristics.The system is applied to the desulfurization tower model to experimentally study the influence of different operating parameters on the removal efficiency of particulate matter.The main work of this paper is as follows:1.A new type of purged charged atomization nozzle is designed,and the spray characteristics of the nozzle are measured and analyzed experimentally.The results show that the charging effect of the droplets is most obviously affected by the spray flow rate and spray angle.When the spray flow rate is 0.4 L/min and the spray angle is45°,the new nozzle can achieve the best charging effect.By comparing the working performance of two different charging environments(humidity 95%and 45%respectively),the nozzle can be stably charged even in a high humidity environment.2.A double-spray layer desulfurization tower model test device is designed and built,and used numerical simulation methods to analyze the influence of the internal flow field distribution and the size of the slurry droplets on the dust removal efficiency.Simulation studies have shown that spraying slurry spray can effectively improve the uniformity of the flue gas velocity distribution in the tower compared to the non-spraying state;In addition,the size of the slurry droplets is an important factor affecting the escape of flue gas.When the spray droplet size is too small,the spray droplets will be entrained by the reversed flue gas and escape from the outlet of the desulfurization tower;When the droplet size is greater than 2 mm,it can effectively prevent the spray droplets from escaping from the upper outlet,which is conducive to the collection and recycling of the slurry.3.Based on the built-up desulfurization tower model experimental device,the effect of graded particle size removal under different working conditions was studied experimentally.The results show that with the increase of particle size,the removal efficiency of particle classification particle size gradually increases;in the large-flow spray layer(the first layer),the spray volume is in the range of 4 m~3/h～12 m~3/h,and the particulate matter removal efficiency of all levels has been improved,especially for particulate matter(3.3μm≤dp≤4.7μm)removal efficiency increased by 7.4%.When the spray volume is greater than 8 m~3/h,the increase in spray volume has no obvious effect on the particle removal efficiency of each particle size section.Appropriately increasing the dust concentration and reducing the flue gas flow rate are conducive to improving the dust removal efficiency.In the charged spray layer(second layer),the dust removal efficiency of the charged spray on fine particles(1.1μm≤dp≤2.1μm)is increased by 10%compared with that of uncharged.