Optimal Preparation Of Sludge-based Activated Carbon And Experimental Investigation On Adsorption Of NO_x In Flue Gas From Coal-fired Power Plants

The massive emission of NOx in flue gas from coal-fired power plants poses a serious threat to human health and ecological environment.Therefore,it is imperative to take appropriate measures to reduce the emissions of NOx.Dry flue gas denitrification technology has been widely used in many power plants.The application of activated carbon as catalyst for denitrification has been in the research stage due to the immature process.Urban sludge and agricultural wastes are two major wastes in urban production and life,and agricultural production.It is of great significance to use wastes for activated carbon preparation for pollution control and resource utilization.The experimental study on the physicochemical properties of surface activated sludge activated carbon and its denitrification performance was mainly carried out in the thesis.The main results are summarized as follows:(1)Based on the chemical activation method,the sludge-straw-based activated carbon was prepared by using municipal sludge and reed straw as precursors.The optimum parameters for blending 30%reed straw with sludge-straw-based activated carbon were identified.The carbonization temperature is 500℃ and the activation temperature is 600℃.The activation time is 90 minutes and the alkali-carbon ratio is 3:1.(2)BET,SEM,SEM-EDS,XRD and FTIR were used to compare and analyze the ratio and activation process on surface physicochemical properties of modified activated carbon.The research showed that the increasing carbon content of activated carbon prepared by incorporation of reed straw significantly improves the low carbon content in the sludge,and the microporous ratio gradually increases.The silicon element in the sludge has effectively reduced the polarity of the activated carbon surface and improved its affinity for non-polar adsorbates.(3)The experimental results showed that the modification of ZnCl2/KOH can effectively improve the pore structure of activated carbon and improve the functional groups on the surface of activated carbon.Compared with ZnCl22/KOH modification,the specific surface area of activated carbon prepared by ZnCl2 activation is larger,but the production rate of micropores is lower.The modified activated energy of KOH can produce activated carbon with higher microporosity and more basic functional groups on the surface.The micropore in activated carbon and the CO functional group on the surface play a major role in the adsorption of NOx,which is less affected than the surface area.(4)The single-factor experimental method was used to test the denitration performance of sludge-straw-based activated carbon.The flue gas conditions such as flue gas temperature,oxygen content in flue gas,initial NO concentration,airspeed,ammonia-nitrogen ratio,and the content of SO2 were investigated.The effect of denitrification efficiency showed that the temperature of the flue gas is 250℃;the content of O2 in the flue gas is 5%;the NO concentration is 500 ppm;the airspeed is 500h-1;the ratio of ammonia to nitrogen is 1:1;the SO2 concentration is 0 ppm;the best denitrification performance is up to 76%.