Studies On The Release Of The Mercury During Biomass And Coal Co-firing

Mercury and its compounds with high bioaccumulation and toxicity, causing great harm to the humans and ecosystem. And large amounts of mercury are release by the process of the coal-fired, which are the largest source of anthropogenic mercury emissions. In 2013, according to the United Nations environment programme (unep) report, the global mercury emissions of coal combustion in 2010 reached 475 tons. At the same time, because of the rapid development of the modern life, fossil fuels, particularly coal, is consumed fast, in order to find the renewable and clean energy, biomass energy into our sight. Nowadays, the utilization of biomass and coal co-firing is applied widely, mixed combustion of biomass and coal industrial boiler and power generation technology is also increasingly mature. With literature study showed that biomass burning also has become one of atmospheric mercury pollution which can not be ignored, the emissions of mercury from buring biomass could be 675 ton a year. And mercury content in different kind of biomass is also different, during the biomass buring mercury emisson is between 30 and 1500ng/g. Therefore this article selects high mercury content biomass, which mixed coal combustion in the temperture program, to analyze the characteristics of mercury release.This paper use the designed temperature programmed device with Lumex mercury measurement instrument, put the high content mercury biomass, coal sample, and according to different mass ratios mixing biomass with coal sample into the temperature program device to heat up, the release of the mercury in the heating process is real-time detection, then get the release curve of mercury with temperature. Chlorine content in biomass is more than coal, therefore this article mainly in comparing the mercury release curve of coal and biomass and compound sample, to analyze mercury release characteristics of mixed combustion of biomass, depend on these data to illustrate the release mechanism of mercury after mixed combustion of biomass. In the process of biomass blended with coal combustion, the mercury in coal released after 300 ℃ released early, and with fewer biomass mixing, the impact of mercury release waning. Next, change the sample temperature programmed reaction environment and ventilation with N2, under the same heating rate and flow experiment, comparison and analysis under oxidizing atmosphere and reducing atmosphere in mixed combustion of biomass different influence on the release of mercury in coal. Compared in the oxidizing is not far apart, and the curve of the first peak temperature is close to oxidation, but the second release peak have a difference temperature of 200 ℃ or so, showed the oxidation or reduction atmosphere to influence the release of mercury mainly affect the release of mercury compounds at high temperatures.At the same time, in order to further study the release of mercury in the process of coal and biomass of mixed combustion process, using thermogravimetric and mass spectrometry instruments to conduct about the biomass, coal and their mixture experiment, analysis the weight of the sample change and a corresponding relationship with the temperature of gaseous product. Through the analysis of TGA curve and the DTGA curve to get the combustion characteristic, at the same time, through the research of CO2, HC1 and SO2 these has a significant effect on mercury release elements release to illustrate its influence on the release of mercury.