Research On Wet Denitration By Urea

Against the backdrop of the severe global environmental situation,environmental problems caused by the use of fossil fuels have increasingly become the focus of attention,and the treatment of atmospheric pollutants such as NOX and SO2 brought by the use of fossil fuels has also become a hot spot for scholars from various countries.The wet denitration by urea has the advantages of low cost,simple operation,and no pollution,which makes it favored by some fine chemicals and various related small enterprises.Because the wet denitration by urea does not have a reasonable and effective process technology,the denitration efficiency is not ideal,makes it has not been widely used.Therefore,the design of a reasonable and efficient wet denitration by urea process technology is extremely important for its industrial application.In this paper,a series of denitration processes with packed tower as the main equipment were designed.The effects of gas flow,liquid flow,temperature,urea solution concentration and urea solution pH on the denitration efficiency were investigated.Method denitrification achieves greater denitration efficiency.The research in this article includes the following aspects.(1)The experiment of designing a single packed tower and two packed towers in series was used to investigate the effects of gas flow rate,liquid flow rate,solution concentration,solution pH value and temperature on the denitration efficiency by controlling the variable method and to determine the better conditions.It was found that the NO_Xremoval rate increased with the increase of urea solution concentration and liquid velocity,decreased with the increase of solution temperature and gas flow rate,and was relatively stable with the change of solution pH.At the same time,better conditions for the wet denitration of the packed tower were obtained through experiments:gas flow rate 2 L/min,liquid flow rate 60 L/h,solution temperature 30℃,solution concentration 20(w)%,and solution pH value 7.Under those conditions,NO_Xremoval rate achieved by the single-packed tower was 87.84%,and NO_X removal rate achieved by using the double-packed towers in series was 89.95%.(2)Designed single bubble tower,double bubble tower series and packed tower bubble tower combined use experiment,through the control variable method,the effects of gas flow,liquid flow,solution concentration,solution pH and temperature on denitration efficiency were investigated and better conditions were determined.It was found that the bubble tower,the double bubble tower series connection and the bubble tower packed tower combination,who’s denitration rates decreased with the increase of temperature and gas flow rate,increased with the increase of the absorption liquid concentration,and decreased slightly with the increase of pH value of the solution;the denitration rate of the combined of the bubble tower and packed tower experiment increased with the increase of the liquid flow rate of the packed tower.At the same time,the better conditions of the three experiments were obtained,namely:gas flow rate 2L/min,packed tower liquid flow rate 60 L/h,solution temperature 30℃,solution concentration 20(w)%,solution pH value 7.Under those conditions,the highest NO_Xremoval rate achieved by the single bubble tower was 73.82%,the highest NO_Xremoval rate achieved by the double bubble tower was 74.53%,and the highest NO_X removal rate achieved by the combined experiment of the packed tower and bubble tower was88.92%.(3)The joint experiment of vortex pump and packed tower was designed.Through the control variable method,the effects of gas flow,liquid flow,solution concentration,solution pH and temperature on the denitration efficiency were investigated and the better conditions were determined.It was found that the denitration rates of the vortex pump denitration experiment and The joint experiment of packed tower and vortex pump denitration experiment both decreased with the increase of temperature and gas flow rate,increased with the increase of the absorption liquid concentration and liquid flow rate,dereased with the increase of the solution pH value then tend to be stable.At the same time,the experiment obtained the better conditions of the two experiments,namely:gas flow rate 2 L/min,liquid flow rate 60 L/h,solution temperature 30℃,solution concentration 20(w)%,solution pH value 7.Under those conditions,the highest NO_X removal rate achieved by the vortex pump was 79.93%,and the highest NO_X removal rate achieved by the combined of the packed tower and vortex pump experiment was 90.23%.