Research On Flue Gas Mercury Removal Efficiency By Adding Calcium Bromide And Activated Carbon In A Domestic Coal-fired Power Plant

There exists a huge risk for human health on mercury pollution. Atmospheric mercury pollution has become a global problem because of its characteristics of migration and sedimentation. China is one of the more serious atmospheric mercury pollution areas all over the world, and coal-fired power plants (CFPPs) are important source of atmospheric mercury emission in China; however, domestic research on mercury removal technology falls behind developed countries now. Therefore, this paper is based on Environmental Nonprofit Industry Research Project in2009and National Science and Technology Support Program Sub-topic. Two kinds of measures for flue gas mercury removal, that is, adding calcium bromide and jetting activated carbon, are researched under actual operating condition in a CFPP. This is the first time on mercury removal efficiency for adding calcium bromide and activated carbon injection by using a variety of detection methods, including continue emission monitoring system (CEMS), sorbent tube sampling method (30B) and Ontario Hydro Method (OH Method). In this paper, elemental mercury oxidation efficiency and total mercury removal efficiency are analyzed by adding calcium bromide; flue gas mercury removal efficiency of ordinary activated carbon brominated activated carbon are compared; And mercury removal efficiency of combination adding calcium bromide with jetting ordinary activated carbon are studied.It is found that elemental mercury oxidation efficiency of SCR reactor is improved by adding calcium bromide. Adding10ppm saturated solution of calcium bromide into the furnace, the proportion of oxidized mercury in the flue gas increases from67.7%to94.2%through the SCR reactor, meanwhile, it is benefit for flue gas mercury removal. Increasing the amount of calcium bromide, on one hand, the proportion of oxidized mercury in the flue gas slightly rise, on the other hand, flue gas mercury removal efficiency evidently reduces. Jetting ordinary activated carbon and brominated activated carbon in the same amount, the latter mercury removal is much better. For example, in60kg/h injection amount of activated carbon, mercury removal efficiency of ordinary activated carbon is73.3%, while brominated activated carbon is92.6%. It is found that adding calcium bromide can greatly improve mercury removal efficiency, and that93.1%of flue gas mercury is removed when adding lOppm calcium bromide and jetting ordinary activated carbon in the injection amount of60kg/h, meanwhile, its costs is far lower than brominated activated carbon.It is found that flue gas mercury removal efficiency has a close contact with boiler load, pH of desulfurization slurry and efflux of desulfurization slurry. Proposals are accordingly raised including adjusting and optimizing the boiler operating parameters to improve synergistic mercury removal capacity in APCDs system, and precisely controlling the pH value of desulfurization slurry and regularly discharging desulfurization slurry to reduce re-release rate of mercury, which can stabilize synergistic mercury removal effect in FGD.