Comparison of mercury emission from around 300 MW coal-fired power generation units between pulverized boiler and circulating fluidized-bed boiler
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摘要: 选取某地330 MW煤粉炉（PC炉）和350 MW循环流化床锅炉（CFB）的燃煤电厂进行汞排放特性的研究。采用30B法和安大略法对两个燃煤电厂的除尘器入口、除尘器出口、脱硫塔出口和湿式电除尘器出口的烟气进行了取样和汞浓度分析，采集了入炉煤和副产物底渣、飞灰及脱硫石膏样品。通过样品中汞含量的分布，探讨了PC炉与CFB锅炉机组现有污染物控制设备对汞的协同脱除作用。结果表明，350 MW CFB电厂除尘器出口烟气平均汞浓度降低至0.43 μg/m3，布袋除尘器对汞的捕获效率达到98.9%，相应的燃烧副产物中飞灰是汞的主要富集对象。对于330 MW PC炉电厂，除尘器入口和除尘器出口烟气汞浓度均高于350 MW CFB电厂，烟气汞浓度从除尘器入口、除尘器出口到脱硫塔出口依次降低，在脱硫塔出口烟气汞浓度降低至0.42 μg/m3，静电除尘器和湿式脱硫塔对烟气汞的捕获效率分别为75.0%和22.4%，相应的产物中飞灰和脱硫石膏中汞都有一定程度的富集。Abstract: The mercury emission characteristics are investigated and compared at a coal-fired power plant with 330 MW pulverized coal (PC) boiler and a coal-fired power plant with 350 MW circulating fluidized bed (CFB) boiler. EPA 30B method and Ontario method were used to test the mercury concentration in flue gas at the inlet of dust extraction unit, outlet of dust extraction unit, outlet of desulfurization unit, and outlet of wet dust extraction unit. The feed coal, bottom ash, fly ash and gypsum sample were collected at the same time together with gas sampling. The effect of the existing air pollution control device on mercury control was discussed toward PC and CFB units based on the mercury distribution data. The results show that the mercury concentration at fabric filter (FF) outlet of CFB power plant is decreased to 0.43 μg/m3 and the mercury removal efficiency of FF reaches 98.9%. A predominating portion of mercury is enriched in fly ash. With respect to a PC power plant, the mercury concentrations at inlet and outlet of ESP are both higher than those in the CFB power plant, and the mercury concentration gradually drops from electrostatic precipitator (ESP) inlet to wet flue gas desulfurization (WFGD) outlet. The mercury concentration reaches a low value of 0.42 μg/m3 at the WFGD outlet, and the mercury removal efficiency of ESP and WFGD is 75.0% and 22.4%, respectively, which can meet the ultra low mercury emission controlling.
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图 1 350 MW的CFB锅炉机组和取样位置示意图
Figure 1 Schematic diagram of 350 MW CFB boiler unit and sampling positions
图 2 330 MW的PC锅炉机组和取样位置示意图
Figure 2 Schematic diagram of 330 MW PC boiler unit and sampling positions
图 3 两电厂各烟气取样位置气相汞浓度
Figure 3 Comparison of gas phase mercury concentration at each sampling point for two power plants
图 4 两电厂固相燃烧副产物中汞的分布
Figure 4 Comparison of mercury distribution in solid byproducts for two power plants
图 5 两电厂污染物控制设备对汞的脱除效率
Figure 5 Comparison of mercury removal efficiency of pollutant control equipments in two power plants
表 1 入炉煤的工业分析和平均汞含量
Table 1 Proximate analysis and average mercury content of feed coal samples
表 2 除尘器入口30B法测试得到的烟气汞浓度
Table 2 Mercury concentration in inlet flue gas of dust collector detected by 30B method
表 3 除尘器入口OHM法测试得到的烟气汞浓度
Table 3 Mercury concentration in inlet flue gas of dust collector detected by OHM method
表 4 除尘器出口30B法测试得到的烟气汞浓度
Table 4 Mercury concentration in outlet flue gas of dust collector detected by 30B method
表 5 湿式脱硫塔出口30B法测试得到的烟气汞浓度
Table 5 Mercury concentration in outlet flue gas of wet desulfurization tower detected by 30B method
表 6 湿式电除尘器出口30B法测试得到的烟气汞浓度
Table 6 Mercury concentration in outlet flue gas of wet ESP detected by 30B method
表 7 两电厂各固相废弃物中的汞含量
Table 7 Mercury content in solid wastes for two power plants
表 8 330 MW PC电厂五级ESP飞灰的汞含量
Table 8 Mercury content in fly ash from ESP for a 330 MW PC power plant
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