| At present,the frequently occurred haze weather in China seriously affects the daily life of residents.And the emission of fine particles that mostly from coal-fired power plants is the main reason.Fine particles have the characteristics of small size and large specific resistance.The conventional dust removal technology has low removal efficiency.Aimed at the high wet flue gas,the cooling condensation film agglomeration and chemical agglomeration are the most promising.The cooling condensation film technology is to make the water vapor in the flue gas supersaturated by cooling.Under the driving force of phase change,the ultrafine particles are as condensation nodules,which promotes the agglomeration and growth of ultrafine particles;At the same time,the temperature gradient is formed,and the ultrafine particles are easily deposited on the cooling tube bundles under the action of the swimming force.Chemical agglomeration technology is to increase the liquid bridge force between condensed particles by adding chemical agglomeration agent,and change the way that particles are connected together,which can effectively prevent the fine particles separated again after coagulation.At present,the research on chemical agglomeration technology has been quite effective,but the cooling condensation film technology and cooling condensation film coordination chemical agglomeration which achieves efficiently removal of high wet fine particles have poor search result.In this paper,our group proposes a new method that fine particles have high efficiency removal by combined chemical agglomeration and cooling condensation film.The flue gas has achieved the saturation state after the desulfurization tower.By reducing the flue gas' temperature or injecting chemical agglomeration agent,the fine particles in wet flue gas were condensed and agglomerated,so we could have efficient removal of fine particles.This paper mainly focuses on two aspects:cooling condensation film and chemical agglomeration.The distribution and evolution of fine particles and the removal characteristics of fine particles in the electrostatic precipitator were investigated during the process of cooling and adding chemical agglomeration agents.Firstly,a small experimental platform was designed and constructed by theoretical calculation.The humidity of the flue gas in the experimental system was consistent with the humidity of the outlet flue gas of the desulfurization tower through numerical tests;In order to eliminate the influence of moisture in wet flue gas,the concentration of particles was measured by an electric low pressure impactor with one stage dilution.Secondly,by changing the cooling rate,entrance particles concentration,aggregation agent types and concentration,adding point temperature of multiple factors,we explored the changes of two levels which was the total particle number and classification of particle matter of high wet flue gas.The results showed that the cooling rate increases,the number of fine particles decreased continuously;The spray tower added agglomeration solution,or adding point temperature increases(<80 C),all could enhance particles removal;The agglomeration agent and the temperature reducing device were used together,the concentration of particles was effectively reduced.Finally,the particle size distribution and removal characteristics in electrostatic field under the action of cooling film and chemical agglomeration were studied.The results showed that reducing saturated wet flue gas' temperature could enhance the fine particles,coagulation and aggregation,increase the particles removal efficiency in the ESP,especially for the particles of 0.04?2 ?m size which has a high penetration rate.With different kinds of agglomeration agents,the quantity and quality of particles removal efficiency were improved.When the cooling condensation film was combined with the chemical agglomeration,the agglomeration effect of fine particles in wet flue gas would be enhanced.The quantity and mass removal efficiency of fine particles in ESP could reach 90.3%and 97%respectively. |
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