Online Detection And Adsorption Of Mercury In The Flue Gas

Mercury exists as a kind of trace toxic substances in the environment, and ithas many hazards: hidden, highly volatile, easy mobility, high bioaccumulation,persistence and others. Atmospheric mercury emissions mainly comes fromcoal-fired power plants, which the main morphology are: elemental mercury (Hg0),divalent mercury (Hg2+) and particulate mercury (Hgp). Elemental mercury (Hg0),which is difficult to remove. Aiming at controlling the growing problem of mercurypollution, studies on adsorption and online monitoring of gaseous Hg of the flue gasare necessary.CeO2has a typical fluorite structure. With good storage and release of oxygenproperties, it can occur reversible oxidation-reduction reaction in a mild condition.In a reducing atmosphere, the cerium oxide can be reduced Ce4+to Ce3+and releaseoxygen; in an oxidizing atmosphere, Ce3+can be oxidized by O2to Ce4+in the fluegas and store oxygen. In this article, we select Cerium Oxide loaded on activatedcarbon and aimed at improving its adsorption capacity.Based on gas phase molecular absorption spectrometer we built a test rig on-line monitoring and adsorbing of mercury vapor. At the same test rig can produceand detect elemental mercury. Experimental results show that the concentration ofelemental mercury ranges from0to80μ g/L, the relationship between Hgconcentration and the absorbance value is linear, and the test rig performancesstable.In this paper, we prepared the adsorption material by using equivalent-volumeimpregnation. The load evaluation of cerium dioxide and stability of the adsorbentmaterial was evaluated by XRD and TGA. The results showed that: ceria wassupported on activated carbon uniformly and in flue gas, the absorbent materialshould be used in a low temperature less than370℃. After adsorbing saturation in aatmosphere which is full of elemental mercury, we found that the high temperatureconducive to negative cerium activated carbon mercury desorption, but if thetemperature is too high, that will result in the loss of activated carbon.In this paper,through the calculation of desorption kinetics, the desorption activation energy Edofthe absorbent material is282.48KJ, pre-exponential factor k0is6.6632.The use ofcombining Factsage2.1and experimental of online monitoring of divalent mercuryand a reaction HgO with A, the divalent mercury can be monitored on line.It is because that cerium oxide belongs to the rare earth element compounds,and the higher the market price, cerium oxide must be retrieved after using. werecycle it in a high-temperature and oxygen-rich atmosphere. XRD and XRF characterization analysis showed that: most ceria powder was recovered, the rate ofrecovery is about83.25%.