Study On Synergistic Removal Of Selenium And Nitrogen Oxides By Deacidification Process Of Hazardous Waste Incineration

Incineration is an effective means of hazardous waste disposal.The selenium and nitrogen oxides produced by hazardous waste incineration have great harm to human body and ecological environment,and need to be effectively controlled.Firstly,this paper explored the distribution,migration and transformation of selenium in the process of hazardous waste incineration,and analyzed the ash samples collected at different points.The results showed that selenium was mainly distributed in fly ash.Four typical selenium compounds(SeO2,Fe2(SeO3)2,Na2SeO3 and CaSeO3)can be classified by decomposition temperature.The temperature was 300℃,500℃ and 800℃.The main selenium in the fly ash was Na2SeO3,which accounts from 81.65%to 93.08%.Dry deacidification agent had a certain removal of selenium in flue gas.Then,the effect mechanism of complex flue gas conditions on the adsorption of selenium by dry deacidification agents was investigated by experiments and density functional theory.The results showed that at 140℃ to 220℃,the increase of temperature increased the adsorption effect of NaHCO3 on SeO2 by changing the physical structure and promoting the reaction trend.The Na2CO3 decomposed from NaHCO3 during the adsorption process had stronger reactivity and reacted with SeO2 to form Na2SeO3,and the reaction site was the surface O atom.Acid gas inhibited the adsorption of selenium through material consumption and point competition,while water will only inhibit the adsorption of selenium through point competition.In addition,based on the multi-pollutant disposal method combining the wet deacidification and the oxidation absorption denitrification,this paper explored the factors of different ratios of NaClO2/NaOH solution and the effect mechanism of acidic gas on denitrification.The results showed that NaClO2 had a good removal efficiency of NO.The efficiency increased with the increase of concentration,the decrease of pH and the presence of acidic gas.On the one hand,H-promoted the reaction between ClO2-and NO,on the other hand,ClO2 gas with stronger oxidation was produced.The denitrification efficiency of NaClO2/NaOH solution was low,but the acid gas can effectively improve the denitrification efficiency.