Oxidation, reemission and mass distribution of mercury in bituminous coal-fired power plants with SCR, CS-ESP and wet FGD
Oxidation, reemission and mass distribution of mercury in bituminous coal-fired power plants with SCR, CS-ESP and wet FGD
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DOI：
10.1016/j.fuel.2011.10.012
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发表时间：
2012-03
期刊：
影响因子：
7.4
通讯作者：
D. Pudasainee;J. Kim;Young-Sik Yoon;Y. Seo
中科院分区：
文献类型：
--
作者：
D. Pudasainee;J. Kim;Young-Sik Yoon;Y. Seo
研究了选择性催化反应器（SCR）、冷侧静电除尘器（CS-ESP）、湿法烟气脱硫系统（FGD）和烟煤电厂烟囱等不同大气污染控制装置（APCD）进出口烟气中汞（Hg）形态的变化规律。研究了烟气温度、流量和烟气组分对汞氧化的影响。关联选定的参数对Hg 0的氧化和去除的APCD和系统内的汞的质量分布进行了估计。采用安大略Hydro方法进行取样和分析。分别根据US EPA方法7470 A和7471 A分析固体和液体样品。锅炉出口烟气和烟囱出口烟气中汞浓度分别为4.70 ~ 27.3μg/Sm 3和3.1 ~ 0.48μg/Sm 3。在APCD的总汞去除率为43.8%至94.9%，氧化汞在烟气中的降低随着温度的升高。随着HCl浓度的增加、烟气流速的减小和温度的降低，燃烧烟气中元素汞的氧化程度增加。烟气中SOx和NOx浓度对元素汞氧化的影响比较复杂。在所研究的参数中，影响APCD整体除汞的最重要参数依次为ESP中的除汞、SCR系统中的氧化和湿法FGD中的除汞。实验数据和统计分析证实，促进了汞的SCR，CS-ESP和湿法烟气脱硫配置中的互利控制。汞的质量分布表明，43.0%的汞被收集在电除尘器飞灰中，49.4%的汞被收集在湿法烟气脱硫副产物和排出物中，3.9%的汞被去除在锅炉底灰中，3.7%的汞被释放到大气中。在SCR+CS-ESP+湿法烟气脱硫配置中，大部分汞被分配到副产品中，并被APCD去除，而CS-ESP+湿法烟气脱硫配置中的去除水平较低。
Mercury (Hg) speciation variations in flue gas at the inlet and outlet of various air pollution control devices (APCDs) were studied, including a selective catalytic reactor (SCR), a cold side-electrostatic precipitator (CS-ESP), a wet flue gas desulfurization system (wet FGD) and the stack of bituminous coal-fired power plants. Effects of flue gas temperature, flow rate and selected flue gas components on Hg oxidation were also studied. The association of selected parameters on Hg0oxidation and removal by the APCDs and the mass distribution of Hg within the system were estimated. Sampling and analysis were carried out using the Ontario Hydro Method. Solid and liquid samples were analyzed according to US EPA methods 7470A and 7471A, respectively. Hg concentration in the flue gas at the outlet boiler and stack ranged from 4.70 to 27.3μg/Sm3and 3.1 to 0.48μg/Sm3, respectively. The overall Hg removal efficiency in the APCDs ranged from 43.8% to 94.9%, and oxidized Hg in flue gas decreased with increasing temperature. With an increase in HCl concentration, a decrease in flue gas flow rate and decreasing temperature, oxidation of elemental Hg in combustion flue gas increased. The effects of SOxand NOxconcentrations on elemental Hg oxidation in flue gas were rather complex. Among the parameters studied, the most significant parameters affecting overall Hg removal in the APCDs, in order, were removal in the ESP, oxidation in the SCR system and removal in the wet FGD. Experimental data and statistical analysis confirmed the promotion of a co-beneficial control of Hg in the SCR, CS-ESP and wet FGD configurations. The mass distribution showed that 43.0% of Hg was collected in ESP fly ash, 49.4% in wet FGD by-products and effluents, 3.9% of Hg was removed in boiler bottom ash and 3.7% was released into the atmosphere. In the SCR+CS-ESP+wet FGD configuration, a major portion of Hg was distributed into the by-products and removed by the APCDs compared to the lower removal levels seen in the CS-ESP+wet FGD configuration.