Experimental Study On Chemical And Acoustic Co-Agglomeration Of Coal-Fired Flue Gas PM_2.5

Smog has become an issue of atmospheric environment which are increasing concerned all over the world.At present,conventional dust collectors used in coal-fired power stations have low PM2.5 capture rates.Agglomeration pretreatment before conventional dust collector is an effective measure,but the effect of single agglomeration method is limited.Besides,to increase the agglomeration efficiency requires more consumption of energy.Therefore,co-agglomeration is a new direction of development.In the study of chemical agglomeration,the physical model and mathematical model for the evaporation of agglomerant atomized droplets in the flue gas of the boiler’s tail were established,and the regualr pattern of the evaporation of droplets was analysised and calculated.Moreover,the fly ash of coal-fired power station was taken as the object of research.The agglomeration thermal system was used to comprehensively investigate the volume distribution and microscopic morphology changes of PM2.5 before and after the agglomeration process.And the influence of various factors on the chemical agglomeration effect was also studied.The results showed that,after adding agglomeration agent,the wetting effect and solid bridge force can enhance the binding performance between PM2.5 and larger particlesand are conducive to the formation of even larger aggregates.Under the standard conditions,the agglomeration efficiency can be more than 90%.In addition,increasing agent concentration can promote the agglomeration of PM2.5.The amount of agent added should be appropriate to the concentration of soot.Properly lowering the pH of the agent favors PM2.5’s agglomeration.What’s more,when the chemical agglomeration system is arranged,the residence time,the size of the atomized droplet and the temperature of the agent adding point should be considered to avoid the incomplete evaporation of the chemical agglomerates.This paper further explored chemical and acoustic co-agglomeration.It was proposed that the "dual-modal" agglomeration and positive feedback of agglomeration are the main mechanisms of the combination.Furthermore,the method of orthogonal experiment and univariate analysis were used to investigate the single factor influenced on the effect of co-agglomeration The results indicated that the order by the significance of the factors,which is:agglomerant concentration>frequency>flue gas concentration>sound pressure level.The optimal solution is the agglomerant concentration of 0.1%,the flue gas concentration of 10 g·m-3.the frequency of 1400Hz.the sound pressure level of 140dB.Besides,the highest agglomeration efficiency exists when the agglomerant concentration is 0.1%,while flue gas concentration at 10g·m-3 frequency at 1400Hz.Meanwhile,the agglomeration efficiency increases with the increase of sound pressure level.