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燃煤电厂是最主要的人为汞排放污染源,氯元素对汞的形态转化及脱除率有非常重要的影响。本文概述了燃煤电厂汞的释放特性和现有控制技术,从氯元素作为烟气组分、活性炭改性物以及燃料添加剂这3个方面详细阐述了氯对汞排放控制的影响。首先氯化氢作为烟气组分,对单质汞向氧化态汞的形态转化有促进作用,这有利于现有除尘、脱硫装置对烟气汞的脱除。含氯化合物改性活性炭吸附剂时,物理吸附和化学吸附同时存在,这能有效提高吸附剂对汞的吸附性能。氯化物作为燃煤添加剂也能有效促进烟气汞的氧化和脱除,其中氯元素在湿法脱硫废水中富集,如何把其利用到烟气汞的脱除对开发高效脱汞技术有重要的意义。同时,比较了以上3种氯添加方案的优缺点。最后指出,深入研究氯元素对汞作用机理是今后的研究方向。 相似文献
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文章介绍了三大类燃煤烟气脱硫脱硝脱汞技术,即高能辐射、活性炭以及烟气流化床技术。对其反应原理和工艺特点进行了论述,对比了三种技术在脱硫脱硝脱汞方面的研究进展和发展潜力,最后根据各方法的优缺点及我国燃煤烟气污染现状提出了对今后烟气治理工作的建议。 相似文献
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燃煤烟气汞污染近些年来被世界公认为又一大污染问题,本文较为详细地论述了汞排放控制技术现状及研究进展.目前有多种在研的汞控制技术,其中湿法洗涤和烟气中喷入活性炭吸附荆方式等较有发展潜力,但现在还没有一种适用性强的技术可广泛推广.最后介绍了烟气脱汞的一些新技术,并对脱汞技术的发展前景进行了展望. 相似文献
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Impact of calcium chloride addition on mercury transformations and control in coal flue gas 总被引:2,自引:0,他引:2
Pilot-scale experiments were conducted to investigate mercury transformations in coal flue gas when firing subbituminous coal with a CaCl2 additive. Cofiring the CaCl2 additive with the subbituminous coal resulted in approximately 50% oxidized mercury, as a result of reactive chlorine species formed in coal flue gas, compared to the dominance of elemental mercury in the baseline flue gas. The mercury data indicate that mercury-flue gas chemistry reactions may occur at fairly high temperatures (>400 °C) in chlorine-enriched flue gas. Field tests were conducted to further demonstrate the impact of cofiring CaCl2 on the eventual fate of mercury. These tests were completed on a 650-MW subbituminous coal-fired power plant equipped with selective catalytic reduction (SCR), a fabric filter (FF), and a wet scrubber. Overall mercury removals across the SCR-FF-wet scrubber system ranged from 75% to 96% with 200-800 ppm (coal basis) chlorine addition compared to 18-32% during baseline operations. Field data indicate that the SCR enhanced mercury oxidation, possibly as a result of the supplemental formation of reactive chlorine species and the aid of the SCR catalyst. As a result, most of the mercury in the flue gas was in an oxidized state and was removed in the downstream wet scrubber, indicating that cofiring CaCl2 is an effective mercury control approach for a subbituminous coal-fired plant equipped with an SCR and wet scrubber. 相似文献
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针对目前玻璃纤维窑炉烟气成分的特点,提出半干法脱硫除尘技术——循环流化床脱硫塔+布袋除尘器。经工程实践运行监测,该综合治理技术脱硫效率≥90%,除尘效率≥99%,系统运行可靠性高,投资费用低,运行费用低。 相似文献
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Heterogeneous mercury oxidation was studied by exposing whole fly ash samples and magnetic, nonmagnetic, and size-classified fly ash fractions to elemental mercury vapor in simulated flue gas streams. Fly ash from sub-bituminous Wyodak-Anderson PRB coal and bituminous Blacksville coal were used. Scanning electron microscopy, X-ray diffraction, thermogravimetric analyses, and BET N2 isothermal sorption analyses were performed to characterize the fly ash samples. Mercury speciation downstream from the ash was determined using the Ontario Hydro method. Results showed that the presence of fly ash was critical for mercury oxidation, and the surface area of the ash appears to be an important parameter. However, for a given fly ash, there were generally no major differences in catalytic oxidation potential between different fly ash fractions. This includes fractions enriched in unburned carbon and iron oxides. The presence of NO2, HCl, and SO2 resulted in greater levels of mercury oxidation, while NO inhibited mercury oxidation. The gas matrix affected mercury oxidation more than the fly ash composition. 相似文献
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The objectives of this study were the evaluation of the effect of MgO addition to coal on the reduction of ash deposition during upgraded brown coal (UBC) combustion, and the elucidation of the mechanisms of the reduction of ash deposition. The melting temperature of UBC ash is 1494 K, which is lower than that of bituminous coal ash. Before the actual ash-deposition experiments, the molten slag fraction in the UBC ash was estimated by means of chemical equilibrium calculations for various mixing mass ratios of MgO to coal ash. The simulation results indicate that MgO addition plays a role in decreasing the molten slag fraction. It was confirmed that Mg formed solid composites with Si, Fe, Al, Ca, and Mn, and played a role in decreasing the molten slag fraction in the ash on the tube. As a next step, ash-deposition tests were conducted using a pilot-scale pulverized coal combustion furnace equipped with a refractory wall. The results showed that MgO addition contributed to decreasing the rate of ash deposition even for UBC. These calculations and experimental results suggested that one of the reduction mechanisms due to MgO addition involved the production of solid-phase aluminosilicates. 相似文献
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简述了湿法烟气脱硫废水的特性、处理原理及调试方法;对石灰石-石膏湿法脱硫废水的形成以及各种污染物做了详细分析,并就废水在各反应池的停留时间、投药量、污泥的排放控制等主要因素对处理效果的影响、及工艺控制过程和最终处理结果进行了讨论。经工艺调试后,脱硫废水处理系统目前已正常投入并运行稳定,各项排放指标均符合标准要求。 相似文献