混燃石油焦CFB锅炉汞排放特性研究

为研究烟煤与石油焦混燃的循环流化床锅炉汞的迁移排放特性,采用安大略法(OHM)对机组布袋除尘器(FF)前后和湿法脱硫装置(WFGD)后的烟气进行取样,并同时对入炉燃料、飞灰、脱硫浆液、清洗水、石膏和脱硫废水进行了取样并分析。通过汞的质量平衡核算得到了汞在燃煤副产物中的分配比例以及汞的迁移排放特性。结果表明:飞灰中排放的汞占总汞排放的62.31%,大约30.38%的汞排放到大气中。FF可以高效地脱除颗粒态汞,对总汞的脱除率可达67.36%。WFGD对可溶性的二价汞脱除性能较好,对总汞的脱除率达24.24%。单质汞的排放因子远大于氧化汞,说明电厂大气汞的排放主要以单质汞为主。

Study of the Mercury Emission Characteristics of a CFB Boiler Burning Coal Blended With Petroleum Coke

Abstract:To study the migration and emission characteristics of mercury from a CFB boiler burning coal blended with petroleum coke,the Ontario hydro method (OHM) was adopted to sample the flue gases before and after the fabric filter (FF) and after the wet flue gas desulfurization (WFGD) device and at the meantime,to sample and analyze the fuel going into the boiler,flying ashes,desulfurized slurry,washing water,gypsum and desulfurization waste water.Through calculating the mass balance of mercury,obtained were the proportion of mercury distributed in the by-products from combustion of coal and the migration and emission characteristics of mercury.It has been found that the amount of mercury discharged from flying ashes will occupy 62.31% of the total mercury emissions and approximate 30.38% of mercury will be discharged to the atmosphere.FF can efficiently remove the particulate mercury,the removal rate of the total mercury will reach 67.31%.The WFGD device will enjoy a relatively good removal performance of dissolvable Hg2+ and the removal rate of the total mercury will reach 24.24%.The emission factor of the elementary mercury will be far more than that of mercury oxide,indicating that the mercury emissions to the atmosphere from power plants will be dominated by the elementary mercury.