新型一体化半干法脱硫系统同时脱汞的试验研究与微观机理分析

Experimental Research and Microscopic Mechanism Analysis on Simultaneous Mercury Removal by Novel Integrated Semi-dry Desulfurization Systems

对某台安装有新型一体化烟气脱硫（NID）系统的燃煤电站锅炉的煤、底渣、飞灰进行取样，测定了样品中汞的含量．并采用Ontario—Hydro方法测定了NID系统前后烟气中汞的形态．利用比表面积及孔隙度分析仪、X衍射仪、扫描电镜和能谱仪对NID系统中各种灰的物理化学特性进行了分析，揭示了NID半干法脱硫系统同时脱除烟气中Hg的微观机理．结果表明：在NID半干法脱硫系统中，消石灰与飞灰可以充分混合，脱硫塔内飞灰循环倍率高，混合灰表面始终有新鲜的脱硫剂Ca（0H）2，而且脱硫塔内有水合硅酸钙形成，颗粒团聚严重，对脱除烟气中的SO2和Hg非常有利．NID半干法脱硫系统对烟气中总汞的脱除效率高达86．6％～92．2％，对燃煤电站汞排放的控制效果显著．

Coal, slag, and fly ash samples were taken from a utility boiler equipped with the NID （Novel Integrated Desulfurization） system, and the mercury contents of these samples were measured. OntarioHydro method was applied to determine the mercury patterns in flue gas before and after NID system. The physicochemical characteristics of the ashes in NID system were analyzed by specific surface and porosity analyzer, X ray diffractometer, scanning electron microscope and spectrometer, and the microscopic mechanism of simultaneous mercury removal by the novel integrated semi-dry desulfurization system was revealed. Results indicate that the lime hydrate and quick lime can mix thoroughly in the novel integrated semi-dry desulfurization system and the circulation ratio of fly ash in the desulfurization tower is high. There is always fresh Ca（OH）2 on the surface of the mixture ash. Furthermore calcium silicate hydrate is formed in the desulfurization tower and particle agglomeration is serious, which is very beneficial for SO2 and mercury removal from the flue gas. The mercury removal efficiency of the novel integrated semi-dry desulfurization system for flue gas is as high as 86. 60% -92. 2%, and the control effect for mercury emission of the coal-fired power station is obvious.