【作者】 刘松涛；

【导师】 赵毅；

【作者基本信息】 华北电力大学（河北） ， 热能工程， 2009， 博士

【摘要】 随着我国经济的发展,电力能源需求量也会越来越大,而燃煤电厂环境污染居高不下,环保迫在眉睫。国、内外现有烟气净化技术中除尘、脱硫、脱硝和脱汞往往是在多个独立系统中分别完成,极少有同时一体化处理技术。本文进行了模拟烟气同时脱除Hg0、SO2和NOx的研究,在固定床实验系统上,筛选出了具有同时脱硫脱硝脱汞性能的改性吸收剂并进行了影响因素实验研究;使用SEM、EDS、XPS和化学分析等方法对吸收剂和脱除产物进行了分析;建立了固定床脱汞的数学模型并进行了编程计算;另外还进行了液相条件下的同时脱硫脱硝脱汞的实验研究和传质反应动力学分析。本课题的研究对发展适合我国燃煤烟气多污染物同时控制技术具有一定的理论意义和应用价值。利用粉煤灰和石灰为主要物质,制备了可用于同时脱硫脱硝脱汞的改性吸收剂,比表面积和孔结构测试分析结果显示,吸收剂的比表面积和孔容积与制备原料相比增加了10倍左右,孔径大部分在3~40纳米之间,属于中等孔隙。扫描电镜和X-射线能谱分析表明,Ca(OH)2在吸收剂表面的相对含量高于吸收剂中Ca的平均含量,添加剂在吸收剂表面得到了很大程度的分散。在固定床实验系统上主要研究了温度、入口汞浓度、SO2和NO浓度变化等对吸收剂脱汞性能的影响,以及模拟烟气中Hg0对吸收剂同时脱硫脱硝性能的影响。平行实验显示,改性吸收剂具有较好的同时脱硫脱硝脱汞性能。XPS分析和化学分析结果显示,脱除产物中硫元素主要以硫酸盐形式、氮元素主要以硝酸盐和亚硝酸盐的形式存在,汞主要以离子态汞存在,以此为基础探讨了改性吸收剂同时脱硫脱硝脱汞的反应机理。有毒物质特性浸出实验结果表明,脱除产物中汞的溶出量低于中国和美国EPA溶出标准,产物可以进行有水加工和后续综合利用。依据汞在系统中的质量平衡和实验数据为基础,建立了吸收剂脱汞宏观吸附动力学数学模型,用Matlab程序结合欧拉算法,进行了编程计算。结果显示,模拟计算结果与实验结果吻合较好。在液相条件下进行了亚氯酸钠溶液同时脱除模拟烟气中SO2、NO和Hg0的实验,研究了吸收剂浓度、初始pH值、温度、SO2和NO浓度等因素对溶液脱汞性能的影响,研究结果表明亚氯酸钠溶液具有较好的同时脱硫脱硝脱汞性能。用化学方法测定了鼓泡反应器的传质特性,在得出的物性参数和传质参数的基础上,进行了液相脱汞传质反应动力学的研究,计算了液相脱汞的吸收速率常数、增强因子等。更多还原

【Abstract】 With the development of economy, the demand of power energy would increase greatly as well. However, the pollution from coal-fired power plant more and more and the environmental protection become very urgent. In the existing gas purification technology at home and abroad, the removal of dust, SO2, NOx and Hg0 were completed separately in different independent systems usually, and there is very few simultaneous and integrative processing. The study on simultaneous desulfurization, denitration and mercury removal from simulated flue gas was carried out in this paper. At the fixed-bed experimental system, the modified absorbents which have the performance of simultaneous desulfurization, denitration and mercury removal were selected to have an experimental study farther. The metheds such as SEM, EDS, XPS and chemical methods were used to analysis the absorbents and there byproducts. The mathematical model of mercury removal based on the fixed-bed were established and calculated. In addition, the experimental study and mass transfer kinetics of desulfurization, denitration and mercury removal in liquid phase were carried out. The study of this paper have certain theoretical meaning and application value for developing the technique of multiple pollutants simultaneous controlled from coal-fired flue gas.The modified absorbents which have the performance of simultaneous desulfurization, denitration and mercury removal was prepared by fly ash and CaO mainly. The analysis results of specific surface area and pore structure tests showed that the specific surface area and pore volume of fly ash increased about 10 times after digestion at certain hydrothermal condition by calcium oxide. Most of the micropore pore size were in the range of 3~40 nm, belonging to medium pore. The SEM and X-ray energy spectrum analysis showed that: the relative average content of Ca(OH)2 on the absorbents surface was higher than that inside. The additives were dispersed in the absorbent surface evenly.The effects of temperature, inlet mercury concentration, SO2 and NOx concentration on the mercury removal efficiency were investigated at fixed-bed experimental system. The effect of mercury in the flue gas on the simultaneous desulfurization and denitration was investigated also. The experimental results showed that the modified absorbents had preferable performance of simultaneous desulfurization, denitration and mercury removal from flue gas.The XPS analysis and chemical analysis results showed that the sulfur element in modified absorbent’s byproducts mainly existed in the form of sulfate, and nitrogen element existed with nitrate and nitrite mainly, mercury element existed with ion-state. The mechanism of simultaneous removal of SO2, NOx and Hg0 by modified absorbents was discussed.The TCLP leaching experiment were adopted in the laboratory and the experiment results showed that the leaching amount of merury from byproducts lower than the standard of national and American EPA. These indicated that the byproduct could be used in water processing comprehensive utilization subsequently.Based on mass balance of mercury in the system and experimental data, adsorption macrokinetics models were developed to describe the adsorption characteristic of mercury from flue gas. The differential equations were established based on mass balance of mercury in the gas phase and solide phase. The model was solved using a Matlab program with a improved euler method process. The results showed that the experimental data were fitted to the simulation very well.The experiments of simultaneous desulfurization, denitration and mercury removal were carried out in NaClO2 solution. The effect of solution concentration, initial pH value, reaction temperature, concentration of SO2 and NO on the mercury removal performance was researched in the paper. The study showed that NaClO2 solution had a better performance of simultaneous removal of SO2, NO and Hg0 from flue gas. Based on mass transfer parameters of bubbled reactor measured by chemical method, mass transfer and reactor kinetics was studied after obtaining physical parameters and mass transfer coefficient. Some data, such as the absorption rate constant and enhancement factor of mercury removal in liquid phase, were calculated in the paper.更多还原