1000MW超超临界燃煤机组汞排放特征

Emission Characteristics of Mercury in 1000MW Ultra-supercritical Coal-fired Unit

为探究1000MW超超临界燃煤机组汞的排放特性,针对国华寿光电厂2号1000MW超超临界燃煤机组,采用安大略方法(Ontario hydro method,OHM)法对烟气污染物控制设备6个点位(选择性催化还原系统(selectivecatalytic reduction,SCR)前后、静电除尘器(eletrostatic precipitator,ESP)前后、湿法烟气脱硫系统(wet flue gas desulfurization,WFGD)前后)开展了颗粒态、氧化态、零价态以及总汞测量。研究表明,在45%负荷下,SCR前入口汞浓度为11.47μg/m^(3),催化剂促进零价汞氧化,ESP出口汞浓度为2.7μg/m^(3);经过脱硫和湿除系统后,汞的最终排放浓度降到0.34μg/m^(3),污染物控制设备对汞的总脱除效率为97.07%;从SCR到ESP,汞的脱除效率为76.44%,脱硫和湿除对汞的脱除效率为20.63%。在100%负荷下,最终排放汞浓度为0.56μg/m^(3),污染物控制设备对汞的总脱除效率为92.62%。基于质量平衡分析,发现低负荷时富集在飞灰中汞的比例降低,而石膏中的比例升高,可知在低负荷情况下,汞的排放浓度更低,且更易富集在石膏之中。

In order to explore the mercury emission characteristics of 1000 MW ultra-supercritical coal-fired units,OHM method was used to measure the particulate mercury,elemental mercury,and oxidation mercury in flue gas before and after selective catalytic reduction(SCR),before and after eletrostatic precipitator(ESP),as well as before and after wet flue gas desulfurization(WFGD) of Shouguang ultrasupercritical coal-fired power plant 1000 MW unit.At 45% load,the mercury concentration at the front of the SCR was 11.47μg/m^(3),catalyst promotes Hg0 oxidation,and the mercury concentration at the ESP outlet was 2.7μg/m^(3).After the desulfurization system and the WESP system,the final emission concentration of mercury decreased to 0.34 μg/m^(3).The total removal efficiency of mercury by the APCDs was 97.07%.From SCR to ESP,the removal efficiency of mercury was 76.44%,the removal efficiency of mercury by desulfurization and WESP was 20.63%.At 100% load,the final mercury emission concentration was 0.56μg/m^(3),and the total removal efficiency of mercury by the APCDs was 92.62%.Based on the mass balance analysis,at low load situation,the proportion of mercury enriched in fly ash decreased while that in gypsum increases.It shows that under low load conditions,the mercury emission is lower and mercury is more likely to be concentrated in gypsum.