The carbon sorbent traps method was used to monitor the mercury content and speciation underhigh-temperature and high-ash content conditions that are beyond the allowable conditions of the EPAMethod 30B,to extend its ...The carbon sorbent traps method was used to monitor the mercury content and speciation underhigh-temperature and high-ash content conditions that are beyond the allowable conditions of the EPAMethod 30B,to extend its application range.The results show that,when measuring the total mercury con-centration in flue gas,this method can be applied to the occasions of high dust concentration(e.g.beforethe WFGD system),with the error caused by dust lower than 1%,if keeping the flow rate at a lower leveland employing dustproof cover.But this method is not suitable to the conditions with extreme high dustcontent.By applying air-cooled casing and controlling the sampling gun's insert depth,the temperature ofcarbon traps can be kept within a suitable range.Thus,the measurement accuracy of mercury concentrationbefore air preheater can be ensured.For the chimney inlet and other areas with low dust concentration,theproportion of Hg°measured by the 30B method is in accordance with the Hg-CEMS after the WFGD sys-tem,while after the CFB-FGD system,the proportion of Hg°measured by the 30B method is slightly lowerthan that by the Hg-CEMS method.For locations with high dust concentration,the proportion of Hg°measured by the 30B method may be much lower than the true value.展开更多
Rare and consecutive high-nitrate haze pollution episodes were observed in Beijing in spring2012. We present detailed characterization of the sources and evolutionary mechanisms of this haze pollution, and focus on an...Rare and consecutive high-nitrate haze pollution episodes were observed in Beijing in spring2012. We present detailed characterization of the sources and evolutionary mechanisms of this haze pollution, and focus on an episode that occurred between 15 and 26 April. Submicron aerosol species were found to be substantially elevated during haze episodes, and nitrates showed the largest increase and occupation（average： 32.2%） in non-refractory submicron particles（NR-PM1）, which did not occur in other seasons as previously reported. The haze episode（HE） was divided into three sub-episodes, HEa, HEb, and HEc. During HEa and HEc, a shallow boundary layer, stagnant meteorological conditions, and high humidity favored the formation of high-nitrate concentrations, which were mainly produced by three different processes —daytime photochemical production, gas-particle partitioning, and nighttime heterogeneous reactions — and the decline in visibility was mainly induced by NR-PM1.However, unlike HEa and HEc, during HEb, the contribution of high nitrates was partly from the transport of haze from the southeast of Beijing — the transport pathway was observed at ~800–1000 m by aerosol Lidar —and the decline in visibility during HEb was primarily caused by PM（2.5）. Our results provide useful information for air quality improvement strategies in Beijing during Spring.展开更多
基金The Science and Technology Project in China Huaneng Group:“Mercury Control Technology R&D Laboratory Construction”
文摘The carbon sorbent traps method was used to monitor the mercury content and speciation underhigh-temperature and high-ash content conditions that are beyond the allowable conditions of the EPAMethod 30B,to extend its application range.The results show that,when measuring the total mercury con-centration in flue gas,this method can be applied to the occasions of high dust concentration(e.g.beforethe WFGD system),with the error caused by dust lower than 1%,if keeping the flow rate at a lower leveland employing dustproof cover.But this method is not suitable to the conditions with extreme high dustcontent.By applying air-cooled casing and controlling the sampling gun's insert depth,the temperature ofcarbon traps can be kept within a suitable range.Thus,the measurement accuracy of mercury concentrationbefore air preheater can be ensured.For the chimney inlet and other areas with low dust concentration,theproportion of Hg°measured by the 30B method is in accordance with the Hg-CEMS after the WFGD sys-tem,while after the CFB-FGD system,the proportion of Hg°measured by the 30B method is slightly lowerthan that by the Hg-CEMS method.For locations with high dust concentration,the proportion of Hg°measured by the 30B method may be much lower than the true value.
基金supported by the National Natural Science Foundation of China(No.41305115)the National Key Project of Basic Research(No.2014CB447900)+1 种基金the Commonweal Project in Ministry of Environmental Protection(Nos.201409001,201309011)the Hi-Tech Research and Development Program(863) of China(No.2014AA06AA06A512)
文摘Rare and consecutive high-nitrate haze pollution episodes were observed in Beijing in spring2012. We present detailed characterization of the sources and evolutionary mechanisms of this haze pollution, and focus on an episode that occurred between 15 and 26 April. Submicron aerosol species were found to be substantially elevated during haze episodes, and nitrates showed the largest increase and occupation（average： 32.2%） in non-refractory submicron particles（NR-PM1）, which did not occur in other seasons as previously reported. The haze episode（HE） was divided into three sub-episodes, HEa, HEb, and HEc. During HEa and HEc, a shallow boundary layer, stagnant meteorological conditions, and high humidity favored the formation of high-nitrate concentrations, which were mainly produced by three different processes —daytime photochemical production, gas-particle partitioning, and nighttime heterogeneous reactions — and the decline in visibility was mainly induced by NR-PM1.However, unlike HEa and HEc, during HEb, the contribution of high nitrates was partly from the transport of haze from the southeast of Beijing — the transport pathway was observed at ~800–1000 m by aerosol Lidar —and the decline in visibility during HEb was primarily caused by PM（2.5）. Our results provide useful information for air quality improvement strategies in Beijing during Spring.
