Study On Monitoring And Control Of Mercury Emission From Coal Flue Gas From Thermal Power Plant Based On MOx/AC

China is the largest coal consumption country,where coal is widely used in power plant,steel-making,metallurgy,and other fields.Mercury emitted during coal combustion,is considered to be one of the most dangerous air pollutants because of its strong harmfulness and enrichment to ecosystem.Coal-fired power plants have become the largest source of anthropogenic mercury emissions in China.The control of oxidized mercury(Hg2+)and particulate mercury(Hgp)can be captured by existing air pollution control devices.Hg0 cannot be effectively captured by any of the existing air pollution control devices,due to its strong volatility,poor water solubility and long retention time.In the study and practice of mercury control technology for the flue gas of coal burning,it is found that the mercury removal technology in the flue gas after combustion is a more effective mercury control technology.The mercury removal technology by adsorbent has become the focus of current research because of its excellent control effect.In this research,the factors affecting the removal of elemental mercury in flue gas from coal-fired power plants were studied.To simulate the reaction temperature and flue gas composition of pollution control device in coal-fired power plant.A mercuryremoving agent(MOx/AC)with high efficiency was prepared by using activated carbon(AC)as the carrier and supported by transition metal oxide.The catalytic oxidation characteristics of metal oxides were used to promote the oxidation of elemental mercury to Hg2+,and the effective control of Hg0 in flue gas of coal-fired power plants was achieved.In the study,a self-built fixed-bed experimental device was used to test the performance of MOx/AC mercury removal by simulating coal-fired flue gas conditions.At the same time,the research optimized and improved the atomic absorption spectrophotometer,through the cold atomic absorption spectrophotometry to achieve the real-time on-line monitoring of elemental mercury in the reaction.Finally,the regeneration performance of MOx/AC was studied by temperature-programmed desorption(TPD),and the existing forms and influencing factors of mercury compounds on the surface were analyzed.The main results of this research are as follows:(1)The effects of preparation process and reaction temperature on mercury removal performance of adsorbent were discussed in this study.The results showed that the plasma treatment could serve as an efficient method of preparing catalyst,which can improve the dispersion of active centers,and effectively improve the mercury removal performance of MOx/AC.At the same time,MOx/AC can effectively remove mercury from flue gas at different reaction temperatures(80℃,120℃,150℃,180℃),reaching the mercury emission standard(0.03mg/m3)of flue gas from thermal power plants.The Hg0 removal efficiency of the adsorbent could be recovered by the temperature programmed desorption(TPD)process under relatively mild regeneration temperature.(2)The sulfur resistance of MOx/AC adsorbent and the action mechanism of SO2 were studied.The industrial application prospect of the adsorbent was also prospected It was found that existence of SO2 flue gases inhibited the mercury removal capacity of MOx/AC,and the x%CeO2/AC adsorbent had better SO2 resistance than Co loaded.The results of XPS and O2-TPD showed that SO2 could occupy the active centers on the surface of adsorbent and react with the active center to produce a mixture of MOn·SxOy,which reduce the lattice oxygen content,resulting in the poisoning and deactivation of MOx/AC.Based on the experimental results,it was innovatively proposed that the inhibition of SO2 on the mercuy removal capacity of adsorbent could be relieved by increasing the loading of metal oxide,and achieve the efficient removal of mercury in coal flue gas.