基于实测的燃煤电厂氯排放特征

A Full-Scale Field Study on Chlorine Emission of Pulverized Coal-Fired Power Plants in China

选取我国4家电厂的6台煤粉锅炉进行现场测试,采集并分析烟气以及飞灰、底渣、脱硫石膏等燃煤副产物样品,以开展燃煤电厂Cl污染物排放特征的研究. 结果表明：燃煤中96.99%以上的Cl析出进入烟气,原烟气中ρ（Cl）范围为10.17-33.63mgm3.除尘器和石灰石-石膏湿法脱硫装置对烟气中的Cl具有协同脱除作用,尤其是石灰石-石膏湿法脱硫装置. 除尘器对烟气中Cl脱除效率为12.29%-19.86%,石灰石-石膏湿法脱硫装置对烟气中Cl的平均脱除效率为95.22%. 经过燃烧和烟气污染控制装置后,燃煤中0.35%-3.01%的Cl转移到底渣中,6.46%-15.00%的Cl转移到飞灰中,68.88%-77.31%通过脱硫废水排放,9.19%-15.95%的Cl转移到脱硫石膏中；只有2.21%-5.54%的Cl排入大气中,净烟气ρ（Cl）仅为0.34-1.38mgm3. 目前我国燃煤电厂Cl污染的主要问题是妥善处理脱硫石膏和废水,以防止Cl的二次污染.

Chlorine （Cl） is a harmful element and may cause technological （fouling, slagging, corrosion） and environmental issues during coal combustion. A full-scale field study of Cl emissions was conducted at six pulverized coal-fired （PC） boiler units of four coal-fired power plants in China. Flue gas samples were collected from the inlets and outlets of the existing air pollutant control devices （APCDs） to investigate their effects on speciation and distribution of Cl in the flue gas. Concurrent with flue gas sampling, coal, bottom ash, fly ash, and samples from the FGD process （desulfurization gypsum and waste water） were collected to investigate the partitioning of Cl in a full-scale combustion process equipped with APCDs. Prior to entering APCDs, Cl concentrations in flue gases in the measured power plants ranged from 93-135μgg. Over 96.99% Cl contained in coal was released to gas phase during combustion in the examined PC boilers, and the total Cl concentration in the flue gas from boilers was in the range of 10.17-33.63mgm3, mainly in the form of HCl. The wet FGD and de-dusting devices were able to remove the pollutants of Cl in the flue gas, wet FGD being more effective. The wet FGD process removed over 90% of Cl in the flue gas. Particulate bound Cl can be removed by de-dusting devices, and the removal efficiency of de-dusting devices varied from 12.29% to 19.86% for Cl compounds in the flue gas. The Cl released from coal combustion was transferred into slag, fly ash, desulfurization gypsum and waste water after passing through APCDs. In terms of the final Cl emissions after APCDs, Cl in slag occupied 0.35%-3.01%, and around 6.46%-15.00% of the Cl was transported into fly ash. Most of Cl was transferred into the waste water, accounting for 68.88%-77.31%, and the gypsum contained 9.19%-15.95% of the total Cl. Only 2.21%-5.54% of Cl was emitted directly into the atmosphere, and the total Cl concentration in the flue gas from stacks was in the range of 0.34-1.38mgm3. The results indicated some possible environmental pollution of water and soil with Cl in the areas surrounding the coal-fired thermoelectric power plants in China.