| After the wet desulfurization tower of coal-fired power plants,a large amount of sulfur trioxide still escapes in the form of acid mist aerosol.Because its particle size is mostly distributed between 1～10 microns,it has excellent followability with flue gas.Therefore,the removal efficiency of the wet desulfurization tower of the power plant for acid mist aerosol is not high,only 30～50%.At present,the"Coal Power Energy Saving,Emission Reduction,Upgrading and Retrofitting Action Plan"states:our country strictly controls the emission of air pollutants,and sets requirements for the emission concentration of smoke,sulfur dioxide,and nitrogen oxides,and their emissions are not higher than 10,35,and 50 mg/m3.However,there is no clear requirement for the emission of sulfur trioxide,only the reduction of sulfur trioxide emissions is mentioned.Acid mist aerosol not only causes great damage to power plant equipment,but also causes serious harm to the human body and the environment when it is discharged into the atmosphere through the chimney.Therefore,it is very important to conduct related research on the removal technology of acid mist aerosol.In this paper,a self-designed and built acid mist aerosol generating device and removal device are used to carry out the removal experiment of sulfuric acid trioxide mist aerosol at low temperature.The structure design of the generating device and removal device is determined by simulation software.The incident tube diameter of sulfur trioxide is selected as a small tube diameter and a large flow rate,which can make the SO3 gas more uniformly dispersed after entering the aerosol generating device.At the same flow rate,the gas possesses greater momentum,and the SO3 gas can reach a position farther from the inlet.The inlet layout of the aerosol generating device is selected as:air in the middle,SO3 gas on the top,and water vapor on the bottom.This can make SO3 not directly contact with water vapor at the first time it enters the generating device,and there is more room for full development.The spray incident angle in the aerosol removal device is designed to be 135°,which can increase the disturbance of the spray droplets after entering the mainstream pipe section,and the proportion of filling the mainstream pipe section is the highest.Experiments were carried out to study the influence of factors such as temperature,molar ratio,type of removal agent,initial concentration of SO3,angle of incidence,atomization gas volume and residence time on removal efficiency.The experimental results show that the removal efficiency changes with the increase in temperature as follows:first increase steadily and then fluctuate near the highest value,when the reaction temperature is increased from 40℃to 55℃,the removal rate increases by 23%,the best removal efficiency The corresponding temperature is 52～56℃;the removal efficiency of the three alkaline removal agents sodium carbonate,sodium hydroxide,sodium bicarbonate for acid mist aerosol is basically the same;as the molar ratio increases from 1 to 4,the removal efficiency increases,but it increases trend is weakening,at this time,the collision probability of spray droplets and acid mist aerosol becomes the main factor restricting the removal efficiency;the recommended molar ratio is 2～3;when the initial concentration of SO3 is increased from 75 mg/m3 to 150 mg/m3,the maximum removal efficiency is basically unchanged;among the three incident angles（45°,90°,135°）,the removal efficiency is the highest under the 135°incident structure;increasing the amount of atomization gas can reduce the spray particle size of the alkaline adsorbent,thereby increase the removal efficiency,when the atomization gas volume is 12.5 L/min,the removal rate is 10%higher than that at 7.5 L/min;increase the residence time of alkaline adsorbent spray and acid mist aerosol in the removal device can improve the removal efficiency,the removal efficiency of 1.2 s is 64.5%,which is 95.5%higher than that of 0.6 s. |
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