共查询到19条相似文献,搜索用时 203 毫秒
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在固定床吸附机理研究实验台上,利用汞在线分析仪研究了超声波辅助沉淀法制备的氧化铁吸附剂在N2和模拟煤气气氛下对单质汞的吸附作用,分析煤气中气体成分对氧化铁吸附剂脱汞性能的影响.实验结果表明:氧化铁吸附剂在纯N2气氛下的脱汞效率较低;H2S可以促进氧化铁吸附剂对汞的吸附脱除,脱汞效率能够长时间维持在90%以上;在吸附床温度为150℃条件下,模拟煤气中的还原性气体CO和H2对氧化铁吸附剂的脱汞性能影响不大;模拟煤气中水蒸气抑制了氧化铁吸附剂对单质汞的吸附脱除;随着吸附床温度的升高,氧化铁吸附剂的脱汞效率先增高,而后逐渐降低. 相似文献
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概述了目前当今世界燃煤烟气中脱汞吸附剂的研究现状,介绍了碳基吸附剂、钙基吸附剂、石油焦、飞灰,以及一些新型吸附剂对汞的脱除效果。指出活性炭对汞的脱除效率高,但成本也高;飞灰吸附剂对汞脱除的成本低,但脱除效率也低。用于燃煤电厂汞吸附的吸附剂研究处于实验室研究阶段,因此开发价廉和高效脱汞吸附剂和吸附剂的再生等是吸附剂发展过程中的一个重要研究课题。 相似文献
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燃煤飞灰吸附气态汞影响因素的试验研究 总被引:3,自引:0,他引:3
利用汞渗透管产生的汞蒸气和基本气体成分,在小型固定床试验台上研究了飞灰用量、吸附温度、汞进气浓度及飞灰颗粒大小等因素对燃煤飞灰吸附气态汞的影响.研究表明:在40~120℃内,飞灰对汞的吸附主要是物理吸附,飞灰对汞的吸附效率随着温度的上升而下降;随着汞入口浓度的增大,飞灰的汞吸附效率先降低再升高,飞灰的汞相对吸附量增加;飞灰粒径在50~74μm时可能达到最佳的汞吸附效果.较高的飞灰量、较低的汞进气浓度和吸附温度,以及合适的粒径范围均有利于飞灰对汞的吸附. 相似文献
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燃煤痕量元素排放的控制研究 总被引:2,自引:1,他引:2
对燃煤中痕量元素的控制方法进行了综述;对各国制订的燃烧源中痕量元素的排放标准做了概述;总结了常用的痕量元素排放的控制方法,包括吸附剂对痕量元素排放的控制和吸附机理、非常难以捕获的气态汞的若干种控制方法。经研究发现:硅铝酸盐、钙基吸附剂在高温下会与痕量元素同时发生物理吸附和化学反应,因而它们对痕量元素的排放控制效果较好;并着重描述了低温下活性炭、二氧化钛等对气态汞的减排效果。图l表7参l0 相似文献
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《能源学会志》2020,93(2):666-678
Coal-fired power plant is the largest anthropogenic mercury source. Active carbon injection technique has been widely used to control the mercury emissions. However, high operation cost limits its development and it is necessary to find other potential mercury sorbents. In this study, raw semi-coke and a series of novel cerium (Ce) modified semi-cokes were synthesized and utilized for removing elemental mercury (Hg0) from simulated flue gas. It is noteworthy that the efficiencies were tested without hydrogen chloride (HCl) in order to evaluate the sorbents efficacy for low-chlorine (Cl) coal. The results show that the modified sorbents exhibited the best performance at 150 °C. The performance of sorbent could be reinforced due to the existence of oxygen (O2), nitric oxide (NO) and HCl. The adverse effect caused by sulfur dioxide (SO2) reduced dramatically after Ce modification. The negative impact of ammonia (NH3) on Hg0 removal in this study could be neglected owing to the tiny concentration of NH3. Raw semi-coke provided sufficient carbon content, which is favorable to mercury adsorption. As Ce loading increased, the carbon structure changed and the crystal of cerium oxide was formed in the modified semi-coke. The mass fraction of cerium oxide on the sorbent was over 4.4% when the concentration of Ce modification solution was higher than 0.2 mol L−1. The redox reaction activity and the oxygen storage ability of Ce3+/Ce4+ gave a huge boost to the performance of modified semi-coke. The addition of Ce also had an impact on the proportion of oxygen species. 相似文献
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Huijun Wu Shengwei Wang Dongsheng Zhu Yunfei Ding 《International Journal of Heat and Mass Transfer》2009,52(21-22):5262-5265
A family of composite sorbents has been acknowledged as promising thermal storage materials for low grade thermal energy storage owing to its high specific storage capacity and low regenerating temperature. This paper reports a simplified numerical model aiming to determine the dynamic characteristics of the composite sorbents and evaluate the specific capacity and COP of the open-type thermal energy storage system. The computational results were validated with the experimental measurements carried out on an open-type thermal energy storage set-up filled with composite sorbents. By using the simplified numerical model, the dynamic characteristics of the composite sorbents in the thermal energy storage process were determined. The effects of the composite sorbents and the operating parameters on thermal energy storage system performance were also evaluated. 相似文献
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《能源学会志》2020,93(4):1615-1623
In order to get a cost effective and recyclable sorbent for mercury removal, a series of magnetic iron-carbon (Fe–C-x) sorbents was developed by co-precipitation. The physical and chemical properties of obtained sorbents were evaluated through various characterization methods. According to the results, Fe3O4 precipitate on carbon weakens the surface properties, but mercury removal performance in simulated flue gas is excellent. For flue gas components, HCl promotes mercury oxidation and adsorption on sorbents, O2 has limited effect on mercury removal and SO2 plays an inhibitive role. NO could enhance mercury oxidation with O2 existence because of the generation of NO2, which could react with Hg0 through heterogeneous reaction over iron-carbon surface. Besides, effects of temperature and regeneration performance were further researched under simulated flue gas. Apart from higher temperature will decompose mercury compounds and cause the removal efficiency decrease, Fe–C-3 sorbent shows excellent Hg0 removal performance at the temperature window of 100–200 °C. Exceptional regeneration performance on Hg0 removal indicates that spent sorbent could be regenerated. 相似文献
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《Geothermics》2002,31(4):431-442
Sulfur-impregnated and virgin activated carbons have been used in a laboratory scaled fixed-bed reactor to investigate their capability of removing mercury vapours from a gas mixture containing H2S, O2 and moisture that is representative of the exhaust gas emissions of the geothermal power plants of the Monte Amiata field in Italy. The observed deposition of sulfur from H2S oxidation on the carbonaceous matrix increases the mercury scavenging capacity of the commercial sulfur-impregnated activated carbon and makes virgin activated carbon capable of adsorbing mercury vapours by the formation of HgS contextually to the deposition of sulfur, achieving a mercury adsorption capacity comparable to the commercial sulfur-impregnated activated carbon. This result suggests that the extremely economic virgin activated carbon can be used in this specific application, provided that a suitable carbonaceous matrix is selected to achieve a sulfur deposition rate that can guarantee a high mercury adsorption capacity. 相似文献
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Li JIA Baoguo FAN Xianrong ZHENG Xiaolei QIAO Yuxing YAO Rui ZHAO Jinrong GUO Yan JIN 《Frontiers in Energy》2021,15(1):112-123
The mercury emission was obtained by measuring the mercury contents in flue gas and solid samples in pulverized coal (PC) and circulating fluidized bed (CFB) utility boilers. The relationship was obtained between the mercury emission and adsorption characteristics of fly ash. The parameters included unburned carbon content, particle size, and pore structure of fly ash. The results showed that the majority of mercury released to the atmosphere with the flue gas in PC boiler, while the mercury was enriched in fly ash and captured by the precipitator in CFB boiler. The coal factor was proposed to characterize the impact of coal property on mercury emissions in this paper. As the coal factor increased, the mercury emission to the atmosphere decreased. It was also found that the mercury content of fly ash in the CFB boiler was ten times higher than that in the PC boiler. As the unburned carbon content increased, the mercury adsorbed increased. The capacity of adsorbing mercury by fly ash was directly related to the particle size. The particle size corresponding to the highest content of mercury, which was about 560 ng/g, appeared in the range from 77.5 to 106 µm. The content of mesoporous (4–6 nm) of the fly ash in the particle size of 77.5–106 µm was the highest, which was beneficial to adsorbing the mercury. The specific surface area played a more significant role than specific pore volume in the mercury adsorption process. 相似文献
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Zhang Junying Zhao Yongchun Ding Feng Zeng Hancai Zheng Chuguang 《Frontiers of Energy and Power Engineering in China》2007,1(3):273-279
Hazardous trace element emissions have caused serious harm to human health in China. Several typical high-toxic trace element
coals were collected from different districts and were used to investigate the emission characteristics of toxic trace elements
(As, Se, Cr, Hg) and to explore preliminary control methods. Coal combustion tests were conducted in several bench-scale furnaces
including drop tube furnace (DTF), circulating fluidized bed (CFB) combustion furnace, and fixed-bed combustion furnace. Calcium
oxide was used to control the emission of arsenic and selenium. The granular activated carbons (AC) and activated-carbon fibers
(ACF) were used to remove mercury in the flue gas from coal combustion. The chemical composition and trace element contents
of ash and particulate matter (PM) were determined by X-ray fluorescence (XRF) spectrometry and inductively coupled plasma-atomic
emission spectrometry (ICP-AES), respectively. The speciation and concentration of mercury were investigated using the Ontario-Hydro
method. X-ray diffraction spectrometry (XRD) was used to determine the mineral composition of production during combustion
experiments. With the addition of a calcium-based sorbent, arsenic concentration in PM1 sharply decreased from 0.25–0.11 mg/m3. In fixed-bed combustion of coal, the retention rates of selenium volatiles were between 11.6% and 50.7% using lime. In the
circulating fluidized-bed combustion of coal, the content of selenium in ash from the chimney was reduced to one-fourth of
its original value and that in leaching water from the chimney decreased by two orders of magnitude using lime. Calcium-based
sorbent is an effective additive to control the emission of As and Se during coal combustion. The emission of chromium is
influenced by the occurrence mode of Cr in coal. Chromium emission in PM2.5 during coal combustion is 55.5 and 34.7 μg/m3 for Shenbei coal and mixed Pingdingshan coal, respectively. The adsorptive capacity of granular activated carbon for Hg0 is significantly enhanced through ZnCl2-impregnation. The activated carbon fibers showed decent efficiency in mercury adsorption, on which surface oxygen complex
showed positive effects on mercury adsorption. 相似文献