| A variety of pollutants will release from the coal combustion, including SO2, NOx, Hgand fly ash, etc. At present most of the coal fired boilers in our country are equipped withdesulphurization equipment, so the SO2and fly ash pollution is brought under control,which received a significant environmental benefit. In recent years, more emphasis isplaced on the NOxcontrol in our country. Along with the related emission standards comeon stage, more and more coal fired boilers are installed with the denitration devices. Therequirements on the mercury emission of flue gas has been proposed in related emissionstandards, but because of the flue gas mercury pollutants’ characteristics of low amountand difficulty to remove, no special devices were established before. Use of the existingdenitration devices to remove NOxand Hg at the same time is a kind of economic way, andit is expected to be applied in industry in the future.This article is about the development of a new type removal agent for removingmercury in light of the previous study on mercury removal with denitration catalysts-activated carbon fiber （ACF） load CeCl3remover. ACF impregnated with CeCl3wasdeveloped and some related experiments including reaction temperature, CeCl3loadingvalue and flue gas component on Hg0removal efficiencies were conducted. The massfraction of CeCl3was set to0%,3%,5%,7%and9%. The temperature ranged from80to200℃, and gas composition included O2, N2, NO and SO2and H2O. In addition,Brunauer-Emmett-Teller （BET）, X-ray diffractometer （XRD） analyses and ScanningElectron Microscopy （SEM） were used to characterize the samples. The results showedthat CeCl3significantly improved the mercury removal capacity of activated carbon fiberin the simulated flue gas. Under this experimental condition, the optimal loading value ofCeCl3was5%（mass fraction）; when the temperature was below140°C, the removalefficiency of CeCl3/ACF for Hg0was enhanced with the increase of the temperature andthen decreased above140°C; moreover, the effect of NO, SO2and water vapor on theremoval of mercury were studied. It has been found that NO had a certain facilitating roleon removal of elemental mercury, and there was a positive relationship between theconcentrations of NO and the removal efficiency of Hg0; SO2inhibited the removal of Hg0,and the removal efficiency decreased with the increase of SO2concentrations; the Hg0removal efficiency of CeCl3/ACF was hindered by the water vapor. In this experimentcondition, CeCl3/ACF had certain effect on HgCl2removal, but the efficiency declined gradually when the reaction was kept running. According to the results, the mainly effectfor removing HgCl2with CeCl3/ACF was adsorption. Along with the increase of surfaceadsorption, adsorption capacity gradually weakened. The influence of NO to removeHgCl2can be neglected in this experiment condition. The inhibition effect of SO2wassimilar for both of HgCl2and Hg0removal, and it may cause by sulphuric acid and sulfatewhich generated by the conversion of SO2and SO3when the water vapor existed, whichled to the decrease of surface adsorption capacity and adsorption rate. |
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