Study On NO Conversion Efficiency Of Sludge Combining With Biomass By Using Dielectric Barrier Discharge Method

The treatment of nitric oxide（NO）which is the main component of flue gas pollution,is one of the important problems of environmental pollution.In the paper,the NO conversion efficiency and nitrogen dioxide（NO₂）generation efficiency in simulated flue gas are studied by using dielectric barrier discharge（DBD）technology combined with additive materials.The conversion efficiency of NO is studied by carbonization and modification of original sludge and biomass（including walnut shell,industrial sawdust,corn straw,rice straw,wheat straw）.The main conclusions of the experiments are obtained as follows:Firstly,the influence of power supply parameters on NO conversion efficiency is studied.Experimental results show that the optimal power frequency of the system is9.5 k Hz,and the starting voltage of the power supply is set as 20V.The optimal concentration of NO is 300 PPM,and the volume fraction of oxygen is 5%,by following the introduction of C₂H₄gas.With the appropriate increase of C₂H₄gas concentration,the NO conversion efficiency can be improved.The total gas flow rate is determined to be 1.00 L/min.Secondly,when the original sludge and biomass are added to the reactor,and the NO conversion efficiencies are obtained from high to low as:original sludge,walnut shell,industrial sawdust,corn straw,rice straw,wheat straw and filling agent-free,sequentially.The experimental results show that the optimal roasting time of the activated carbon is 30min and the optimal roasting temperature is 400℃by carburizing treatment of the original sludge.The sludge with biomass composite activated carbon is prepared under the conditions of sludge mixed with different proportions of biomass which is used as a carburizer.Results show that the NO conversion effect of the sludge with walnut shell composite activated carbon is the best.NO conversion efficiencies from second to fifth are as following:sludge with industrial sawdust composite activated carbon,sludge with rice straw composite activated carbon,sludge with wheat straw composite activated carbon,sludge with maize straw composite activated carbon,respectively.The above composite activated carbon materials also have an obvious role in promoting the NO₂generation efficiency.Above five kinds of composite activated carbon are put into a dielectric barrier discharge reactor for repeated experiments to observe their attenuation conditions.It is found that after 8 times of repeated experiments,the NO conversion efficiencies of five kinds of composite sludge activated carbon are not decreased significantly.Finally,the original sludge is modified under different concentrations of acid and alkali solutions.The experimental results show that the best acidic solution modification concentration is 15%HCl solution and the best alkaline solution modification concentration is 10%Na OH solution.The biomass and the original sludge in different proportions are modified with 10%Na OH solution to prepare the composite adsorbent,and the influence of the composite adsorbent on the NO conversion efficiency is investigated.The results show that the NO conversion efficiency and the NO₂generation efficiency are improved obviously by the composite adsorbent compared with the original modified sludge adsorbent.