10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Effects of Natural and Modified Attapulgite on the Emission of Ultrafine PM and Heavy Metals during Coal Combustion Process
YISHU XU, Xiaowei Liu, Hao Wang, Yufeng Zhang, Minghou Xu, Huazhong University of Science & Technology
Abstract Number: 1706 Working Group: Control and Mitigation
Abstract PM2.5 pollution is one of the most severe environmental issues in China. Ultrafine PM is an important part of PM2.5 and is of increasing concerns due to its toxicity and control difficulty. Coal-fired power stations are a primary PM source and are facing with increasing strict emission requirements. Currently, devices such as electrostatic precipitators and fabric filters are implemented to capture and remove the PM in flue gas out of the furnace. Although those devices generally have a total PM removal efficiency of as high as 99.9%, they can not effectively capture the ultrafine PM. So, an in-furnace PM reduction technology has been proposed, which is aimed to reduce the formation of ultrafine during the coal combustion process by adding additives into the furnace.
In this study, clay mineral attopulgite (ATT) was selected as the additive. And another two modified ATT were prepared by HCl and CaCl2 treatments of the natural one respectively. Then, the natural and modified ATTs were separately added into pulverized coal and burn in a drop tube furnace at 1500 °C. To explore their impacts on the ultrafine PM formation, the generated PM was collected via a Dekati low pressure impactor and the mass yields, size distributions, compositions and heavy metal contents of the PM were determined via microbalance, XRF and the microwave digestion-ICP/MS procedure.
The results showed that the natural ATT reduced the mass yield of ultrafine PM by ~27%. By the contrast, the HCl and CaCl2 modified ATT reduced the ultrafine PM by ~44% and ~32% respectively, indicating higher ultrafine PM reduction efficiencies than that of the natural one. What’s more, Adding ATT reduced the partitioning of heavy metal (e.g., lead, etc.) into the ultrafine PM and this performance was also improved after HCl modification. These results indicated that the above modification treatments could help improve the capture performance of both ultrafine PM and heavy metals.