超低排放电厂脱硫及湿式电除尘废水中汞排放分析

Analysis on Mercury Emission From WFGD and WESP Wastewater in Ultra-Low Air Pollutant Emission Coal-Fired Power Plants

为达到烟气超低排放目的,神华国华三河发电有限责任公司300 MW亚临界自然循环燃煤机组实施了一系列改造项目,如低氮燃烧器改造,SCR脱硝改造,新增低低温省煤器,静电除尘器高频电源改造,湿法脱硫塔脱硫提效并增加管式除雾器,新增湿式静电除尘器等。为研究超低排放改造后脱硫废水及湿式静电除尘器废水中汞浓度变化,以该机组为研究对象,取样分析了脱硫塔、湿式电除尘器补充水及排放废水中汞含量。研究结果表明:由于燃煤、石灰石及补充水中汞含量较低,实验期间该超低排放改造电厂脱硫废水及湿式电除尘器废水中汞含量均较低,分别为0.140~0.468μg/L和0.094~0.102μg/L;脱硫塔所排52 m3/h废水中汞增加量为1.75~5.50 mg;湿式电除尘器所排废水中汞含量没有明显变化。

In order to achieve the goal of ultra-low flue gas emission, a series of retrofit projects have been carried out on the 300 MW subcfitical natural circulation coal-fired unit of Sanhe Power Generation Co., Ltd., such as low NO~ burner modification, SCR denitration modification, low-low temperature economizer installation, high frequency power source modification for the electrostatic precipitator （ESP）, efficiency improvement and tubular demister installation for the WFGD absorber, as well as the installation of wet ESP （WESP）. Taking the unit as the study object to explore the changes of the mercury concentrations in the WFGD and WESP wastewater after the retrofits, the makeup water and discharge water of both the FGD absorber and WESP are sampled to analyze the mercury contents. The results show that due to the low mercury content in coal, limestone and the makeup water, the mercury concentration in WFGD and WESP wastewater is also very low which ranges between 0.140 and 0.468 I^g/L and between 0.094 and 0.102 I^g/L respectively. The mercury contents in the 52 m3/h WFGD discharge water increase by 1.75 to 5.50 mg while no significant changes of the mercury concentration is observed in the WESP discharge water.