溴素改性ESP飞灰脱汞机理的实验研究

发布时间：2018-03-20 07:36

本文选题：燃煤电厂　切入点：溴素改性　出处：《中国电机工程学报》2017年11期 　论文类型：期刊论文

【摘要】：燃煤飞灰因含有残炭(UBC)及少量过渡金属元素而被认为是一种具有工业应用前景的价廉高效脱汞吸附剂。然而由于飞灰的成分、结构及性质复杂,在烟道中与汞的反应机理尚不统一清晰。文中在固定床上对4种燃煤电厂静电除尘器(ESP)飞灰(FA)及1%NH4Br改性后的ESP飞灰(NBFA)进行了汞吸附实验,分别考查了N2及模拟烟气气氛对吸附剂汞吸附的影响,利用X射线荧光光谱法(X-ray fluorescence spectrometry,XRF)、扫描电子显微镜(scanning electron microscope,SEM)对其汞吸附能力的影响因素进行了分析。利用程序升温脱附(temperature programmed desorption,TPD)探讨了改性飞灰对汞的吸附机理。结果表明溴化铵改性可显著增加NBFA的汞吸附性能,且在模拟烟气下汞吸附能力大大增强;烟气中酸性气体的存在能极大的促进Hg~0的氧化,其中75%的Hg~0被氧化,只有25%Hg~0被吸附在飞灰表面。溴素改性飞灰对Hg~0的作用机制主要遵循Langmuir-Hinshelwood和Eley-Rideal机理,而飞灰含有的无机组分对Hg~0的氧化作用遵循Mars-Masessen机理;在飞灰表面主要生成的是HgB r2和HgO,UBC含量高的飞灰表面还会生成HgS和Hg_2(NO_3)_2。根据实验结果,飞灰对汞吸附氧化主要以Langmuir-Hinshelwood和Eley-Rideal机理为主,伴随有微弱的Mars-Masessen机理。
[Abstract]:Coal fly ash is considered to be a cheap and efficient adsorbent for mercury removal because it contains carbon residue UBC) and a small amount of transition metal elements. However, the composition, structure and properties of fly ash are complex. The mechanism of reaction with mercury in flue is not uniform. In this paper, mercury adsorption experiments have been carried out on four kinds of electrostatic precipitator (ESP) fly ash (FAA) and 1NH4Br modified ESP fly ash (Nbfa) in a fixed bed. The effects of N2 and simulated flue gas atmosphere on the adsorption of mercury adsorbent were investigated. The factors influencing the mercury adsorption ability of the modified fly ash were analyzed by X-ray fluorescence spectroscopy and scanning electron microscopy (SEM). The adsorption mechanism of the modified fly ash for mercury was investigated by temperature programmed desorptiont TPDs. The modification of ammonium bromide can significantly increase the mercury adsorption performance of NBFA. The presence of acid gas in flue gas can greatly promote the oxidation of Hg~0, of which 75% of Hg~0 is oxidized. The action mechanism of bromine modified fly ash on Hg~0 mainly follows the mechanism of Langmuir-Hinshelwood and Eley-Rideal, while the oxidation of Hg~0 by inorganic components of fly ash follows Mars-Masessen mechanism. On the surface of fly ash, HgS and Hg2NO3C will be generated on the surface of fly ash with high content of HgB R2 and HgOG UBC. According to the experimental results, the adsorption and oxidation of mercury by fly ash are mainly composed of Langmuir-Hinshelwood and Eley-Rideal mechanisms, accompanied by weak Mars-Masessen mechanism.
【作者单位】：能源热转换及其过程测控教育部重点实验室(东南大学);
【基金】：国家自然科学基金项目(51376046) 国家重点研发计划(2016YFC0201105,2016YFB0600604-02)~~
【分类号】：X701

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