| Mercury emission from the coal combustion process is the main source of atmospheric mercury pollution. Adsorption of mercury by sorbent injection is a simple way of removal mercury after combustion. Because of its high cost, activated carbon is not widely used in coal-fired power plants for mercury removal. So it's necessary to develop non-carbon-based adsorbent technologies.In the thesis, a fixed-bed furnace was used to investigate influence of temperature and the Br content in the sorbents to the capture efficiency. Also the temperature programmed decomposition desorption (TPDD)of the mercury species over the sorbent was used to investigate the reaction product on the surface of sorbents.The mercury removal ability of the sorbents in actual pyrolysis gas was proven in the pilot-scale fluidized bed.The results on experiments of fixed-bed show that, temperature is the most important factor for the sorbents'mercury removal ability.The mercury removal ability of all sorbents was enhanced by the increasing temperature between 100℃and 200℃and the highest mercury removal efficiency was appeared on 200℃For the largest BET, highest Br content and the catalysis of Na and Mg,Br- impregnated zeolite's mercury removal efficiency was higher than Br- impregnated kaolin and limestone. Br- impregnated kaolin performed well when the temperature was higher than 150℃. Br- impregnated limestone was efficient to remove the mercury in a short time when the temperature was over 175℃.The higher Br content in the sorbents obviously enhaced the mercury removal ability when the temperature was low.The results of TPDD experiments in indicated that, the mercury was removed through the chemical adsorption and binded on the sorbents.The Hg was changed to HgBr2 on the Br- impregnated sorbents.The results of the experiments in pilot-scale fluidized bed was proven that the Br-impregnated sorbents were efficient to remove the mercury from the actual pyrolysis gas. |
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