磁性可循环吸附剂集中控制燃煤烟气零价汞污染的研究

发布时间：2018-02-19 21:13

本文关键词： 零价汞集中控制吸附剂再生 Fe-Ti-Mn尖晶石磁黄铁矿铁闪锌矿　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国的汞污染排放状况已经引起了全球范围的高度关注。燃煤电厂排放的零价汞是我国大气汞的主要来源。国际上用于控制燃煤电厂零价汞排放的技术为活性炭吸附法和SCR协同氧化法,但这两种技术的脱汞效率较依赖于原煤氯含量,且会将汞引入燃煤副产物中造成二次污染,限制了这两种技术在我国的推广应用。本文中创新性地提出了以磁性Fe-Ti-Mn尖晶石和磁黄铁矿为吸附剂,分别协同静电除尘器(ESP)+布袋除尘器(FF)和湿式电除尘器(WESP)集中控制烟气汞污染的技术工艺,并开发了用于储存高浓度气态零价汞的吸附材料铁闪锌矿。主要研究成果如下:(1)Fe-Ti-Mn尖晶石喷入ESP后FF前的烟气中吸附零价汞。在150 ℃含有400 ppm SO2和10%H2O的模拟烟气条件下,Fe-Ti-Mn尖晶石的零价汞吸附容量为0.8 mg g-1。由于Fe-Ti-Mn尖晶石的超顺磁性,可通过磁分离将其从FF捕集的细粒子飞灰中分离出来。吸附在Fe-Ti-Mn尖晶石上的HgO在450℃热处理时再次分解,产生高浓度的气态零价汞,从而实现吸附剂的再生和汞的集中控制。此外,研究通过水洗改善了 Fe-Ti-Mn 尖晶石在循环吸附中因 S02 导致的硫化失活现象。(2)磁黄铁矿喷入WESP前的烟气中吸附零价汞。在60 ℃的模拟烟气中磁黄铁矿的零价汞吸附速率为0.28ugg-1 min-1,其吸附活性不受烟气中SO2的影响。磁黄铁矿可通过磁分离从WESP捕集的混合物中回收,经热再生后再次投入烟气中吸附零价汞。在5次吸附再生循环中,磁黄铁矿始终保持着优秀的零价汞去除效率和强磁性。同时,烟气中低浓度的零价汞在再生过程中被富集成高浓度的汞蒸气,便于汞的集中控制。(3)由水热法合成的铁闪锌矿(Fe0.1Zn0.9S)在室温下的零价汞吸附速率达4.82ug g-1 min-1,吸附容量高于8.65 mg g-1可用于储存由吸附剂再生过程释放的高浓度零价汞。零价汞以HgS的形式吸附在铁闪锌矿上,室温下稳定存在,在溶液中不存在浸出毒性。铁闪锌矿还可作为液态汞泄漏后的处置材料,8 g铁闪锌矿能够完全遏制0.3 g液态汞向环境中释放气态零价汞。总之,运用Fe-Ti-Mn尖晶石、磁黄铁矿和铁闪锌矿能够实现燃煤烟气中零价汞污染的集中控制并使之资源化利用,具有广阔的应用前景。
[Abstract]:Mercury pollution situation in China has attracted worldwide attention. Zero valent mercury emissions from coal-fired plants is a major source of atmospheric mercury in China. International is used to control the zero valent mercury emission from coal-fired power plant technology method for CO oxidation of activated carbon adsorption and SCR, but these two kinds of technology for mercury removal the efficiency is dependent on coal chlorine content, and will introduce a by-product of coal-fired mercury cause two pollution limits, these two kinds of technology application in China. This paper put forward the innovation of the magnetic Fe-Ti-Mn spinel and pyrrhotite as adsorbent were synergistic electrostatic precipitator (ESP) + bag dust collector (FF) and wet electrostatic precipitator (WESP) concentration of mercury pollution control technology of flue gas, and the development of the adsorption material used for marmatite storage of high concentrations of gaseous elemental mercury. The main research results are as follows: (1) Fe-Ti-Mn spinel after ESP before FF injection The adsorption of zero valent mercury in flue gas. The condition of simulating flue gas containing 400 ppm SO2 and 10%H2O at 150 DEG C, Hg0 adsorption capacity of Fe-Ti-Mn spinel is 0.8 mg g-1. due to superparamagnetic Fe-Ti-Mn spinel, by magnetic separation of fine particles from the FF will capture fly ash. The adsorption separation in Fe-Ti-Mn HgO on the decomposition of spinel at 450 DEG C during the heat treatment, produce high concentrations of gaseous mercury, so as to realize the centralized control of regeneration and mercury sorbent. In addition, the research by washing improved Fe-Ti-Mn spinel in cyclic adsorption due to sulfide S02 leads to deactivation phenomenon. (2) injected into pyrrhotite the adsorption of zero valent mercury in flue gas before WESP. In simulated flue gas of 60 DEG C in Hg0 adsorption rate of pyrrhotite is 0.28ugg-1 min-1, its activity is not affected by the adsorption of SO2 in flue gas. The mixture of pyrrhotite from WESP capture by magnetic separation In the heat recovery, regeneration after adsorption again into zero valent mercury in flue gas. In 5 adsorption regeneration cycle, pyrrhotite has always maintained a good Hg0 removal efficiency and strong magnetism. At the same time, zero valent mercury in low concentration of flue gas in the regeneration process by enrichment and high concentrations of mercury vapor, centralized control for mercury. (3) by hydrothermal synthesis of marmatite (Fe0.1Zn0.9S) zero valent mercury adsorption rate at room temperature up to 4.82ug g-1 min-1, the adsorption capacity is higher than 8.65 mg g-1 can be used for storage of high concentration of Hg0 released during regeneration of the adsorbent. By zero valent mercury adsorbed on iron in the form of HgS sphalerite, stable at room temperature, the leaching toxicity does not exist in solution. Marmatite can be used as a liquid mercury leak after the disposal of materials, 8 g christophite able to fully contain 0.3 g liquid mercury release into the environment of gaseous elemental mercury. In short, the use of Fe-Ti-Mn spinel Stone, pyrrhotite and sphalerite can realize centralized control and utilization of zero valent mercury pollution in coal-fired flue gas, and have a broad application prospect.

【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X701

【参考文献】