Study On Effect Of The Addition Of Calcium And Halogen On The Formation Of Particle Mercury

Mercury pollution is in a situation that is becoming more and more serious, and mercury emitted from coal-fired power plants has been identified as the largest source of atmospheric mercury while as a significant threat to both human health and environment. And control of mercury emission form coal-fired power plants has become one of the most active topics in current international research.Aiming at the issue that how to promote transformation from elemental mercury into particle mercury, employing additives containing halogen or calcium such as bromine salts and calcium based compounds, experimental studies on particle mercury formation in fly ash and mercury content in gas after the addition of calcium-based sorbents has been conducted utilizing a one-dimensional corundum pulverized coal sedimentation furnace. The temperature of combustion area is maintained at about 1250 Celsius Degree while quantity of coal and wind is precisely controlled. A gas analyzer is used to monitoring components of the gas, so as to ensure that there is comparability between different experiments. Adopting HNO3-HCl-HF digestion system, samples is digested. Values of mercury content have been obtained from a QM208 type atomic fluorescence photometer and verified by a DMA-80 type solid liquid mercury directly measuring instrument measuring. Combining XRD, SEM and EDS, comprehensive tests have been carried out in order to uncover possible catalytic mechanism in the view of microscopic and elemental. Experimental results show that CaBr2 and KBr have relatively obvious catalytic effect on the formation of particle mercury, the profile corresponding to HgBr can be obviously detected in ash samples that are obtained from the combustion of coals when bromine salts is added. But there is obvious difference between microstructure of different sample adding different salt. When KBr is added, the content of iron drift pearl in ash samples is increasing and ash samples become friable. To the contrary, a trend in ash samples towards aggregation is noticed when CaBr2 is added. Different bromine salts have different effective regions for different coals, while content of mercury in ash sample always tends to increase with decreasing sample size. In experiments on calcium-based sorbents, the existence of SO2 has a significant impact on the effect of calcium-based sorbents, making them more physically and chemically efficient to mercury removal.