【作者】 午旭杰；

【导师】 周劲松； 骆仲泱； 高翔；

【作者基本信息】 浙江大学 ， 工程热物理， 2004， 硕士

【摘要】 目前国内外对燃煤汞污染的测试和控制方法研究处于初步研究阶段，尤其是国内在这方面尚未有全面研究的报道。本文从试验研究的角度出发通过理论分析，较全面地研究了燃煤汞析出后形态分布规律和烟气汞排放控制的各种影响因素。 本文研究了循环流化床燃煤电站中汞的排放规律以及常规污染物控制装置对汞排放的影响。燃烧产物中气态、颗粒态汞分布和文献中的叙述相似，在燃烧区域内主要以单质汞形式存在；电站除尘器对汞的排放有一定的控制作用，除尘器后烟气中汞的含量明显低于除尘器前；烟气经过除尘器前后气态汞分布变化不大；排入大气的烟气中主要为单质态汞为主。为了有效的控制燃煤烟气汞的排放进行了以下的试验研究。 首先对汞形态转化进行了试验研究，通过改变模拟烟气中HCl、SO₂、NO的浓度，在多功能燃煤烟气汞形态转化机理和控制试验台上试验，得出了在不同烟气成份下汞的形态分布状况。 其次对吸附剂进行了筛选和测评，采用固定床试验系统，模拟燃煤锅炉主要烟气成分进行试验，研究了活性炭、沸石、膨润土、飞灰以及蛭石等吸附剂及其改性物对汞蒸气的吸附能力，筛选出了以下几种有应用前景的吸附剂：活性炭、活性MnO₂浸渍活性炭、三氯化铁浸渍活性炭、600℃渗硫活性炭、活性MnO₂浸渍沸石、活性MnO₂浸渍膨润土、活性MnO₂浸渍蛭石、三氯化铁浸渍蛭石，并研究了不同烟气成分、不同入口汞浓度、不同吸附反应温度、不同炭汞比等因素对汞蒸气吸附作用的影响。 设计研究出一种有效的控制燃煤烟气汞排放方法——以半干法为基础的燃煤烟气汞排放控制技术，在小型半干法试验台上进行了以半干法为基础的小型燃煤烟气除汞技术的机理试验研究；对固定床试验台筛选出的吸附剂进行半干法试验研究；并在半干法中型试验台上面进行了试验研究。 通过模型计算，选取基本工况，对活性炭半干法中试塔体内部吸附进行了模拟，结果基本吻合。通过模型分析，选取某些影响因素，预测了在一定运行条件下活性炭吸附剂的吸附量。结果表明，在保证一定C／Hg比的条件下，随着入口浓度增大，单位吸附量也相应增大，活性炭的利用率提高了；改变吸附剂喷入量使炭汞比增大到一定程度时，吸附量曲线增长缓慢，吸附剂的单位吸附量降低，吸附效率增加。较长的接触时间有利于提高吸附效率；在较低的吸附温度下，有利于吸附效率的增加，这是由物理吸附的特点决定的。吸附剂颗粒粒径越小越有利于汞的吸附。更多还原

【Abstract】 At present, the research of mercury emission and control in coal-fired power plant was in the beginning process, especially in China. The mercury transformation mechanism in coal-fired power plant and mecury control in flue gas were studied in this paper, based on experimental and theoretical analyse.The studies of the influence of control equipment to general pollution to mercury emission and mercury transformation mechanism in circulating fluidized bed were conducted at a 6 MW stone-coal-fired plant. The experimental data showed that the speciation of mercury occurring under the systems was similar to the present in references; the dusters have the ability to decrease the mercury emission.A bench-scale experimental is conducted to study effect of flue gas composition on the speciation distribution of mercury in simulated flue gas streams, such as HC1, SO2 and NO.The mechanisms and rate of elemental mercury (Hg0) capture by activated carbons and some other modified chemically sorbents have been studied using a bench-scale fixed-bed apparatus. We have screened out some efficient sorbents such as activated carbons were impregnated with MnO2, FeCl3 and sulfur at 600, zeolite were impregnated with MnO2, roseite were impregnated with MnO2, FeCl3, and bentonite were impregnated with MnO2. The effects of flue gas composition, inlet mercury concentration, adsorption temperature and ratio of C/Hg were investigated to determine the abilities to remove mercury in simulated flue gas streams.Semi-dry mercury control method that injected sorbents and water or some oxidizers in flue gas for Hg control in coal-fired power plant was developed in bench-scale and pilot-scale.A Theoretical model was developed to predict mercury removal in duct based on activated carbon injection for Hg control as determined in pilot-scale experiments at different conditions. The simulation results indicated that the model is capable of describing the test data. Base on the model predictions, lower operating temperature, higher C/Hg ratio and mercury inlet concentration, and smaller sorbents particle size should be utilized to achieve higher Hg removal in this system.更多还原