Research On Denitration Process In Rotating Packed Bed Based On Gas Phase Oxidation

Nitrogen oxides(NOx),as a major air pollutant,due to the increasingly stringent emission standards,the existing wet denitration technologies are urgently needed to be updated by new technologies with the advantages of high removal efficiency,small occupation and simple operation.Since the oxidation degree of nitrogen oxides in the gas phase is a key factor affecting the wet denitration technology,a combined denitration technology is proposed in this dissertation,wherein dielectric barrier discharge(DBD)and rotating packed bed(RPB)are the main reactors in the gas phase oxidation process and liquid phase absorption process,respectively.In this dissertation,the regularities which affects the oxidation degree of nitrogen oxides and the removal efficiency of wet denitration technology are systematically studied.The obtained regularities are as follows:(1)By adjusting the output frequency and peak voltage of DBD power supply,the discharge intensity could be changed,thereby affecting the oxidation degree.The oxidation degree reached the maximum when the output frequency and the peak voltage were 8.5 kHz and 28 kV,respectively.Within the scope of the study(0.04-0.10 s),gas residence time had a very limited effect on the oxidation degree,which was basically stable at about 52%.The oxidation degree was also influenced by the oxygen content and the nitrogen oxides concentration.It increased with increasing oxygen content and decreased with increasing nitrogen oxide concentration.(2)In the process of wet denitration in RPB,the removal efficiency increased with the increase of the oxidation degree of nitrogen oxides.The higher concentration of urea solution could maintain the stability of removal efficiency and thereby facilitate the long-term circulation of absorbents.The addition of a small amount of sodium chlorite(NaClO2)could effectively increase the removal efficiency of nitrogen oxides.In addition,the effects of rotating speed,gas-liquid ratio,packing thickness and nitrogen oxide concentration on removal efficiency were further studied.The optimum process conditions within the experimental range were determined as the rotational speed was 1600 rpm,the gas liquid ratio was 50 and the packing thickness was 75 mm.When the nitrogen oxides concentration was 400 ppm,the removal efficiency could reach about 85%,while it would decline to about 70%when the nitrogen oxides concentration exceeded 1000 ppm.