Volume 16, No. 1, January 2016, Pages 36-45 PDF(1.4 MB)
A Two-Stage Virtual Impactor for In-Stack Sampling of PM2.5 and PM10 in Flue Gas of Stationary Sources
Masashi Wada1, Mayumi Tsukada2, Norikazu Namiki3, Wladyslaw W. Szymanski4, Naoki Noda5, Hisao Makino5, Chikao Kanaoka1, Hidehiro Kamiya2
1 Department of Civil Engineering, National Institute of Technology, Ishikawa College, Tsubata, Ishikawa 929-0392, Japan
2 Institute of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
3 Department of Environmental and Energy Chemistry, Kogakuin University, Hachioji, Tokyo 192-0015, Japan
4 Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna A-1090, Austria
5 Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa 240-0196, Japan
- PM2.5 concentrations compared via conventional and virtual impactors.
- Virtual impactor performance matches well the ISO7708 PM2.5 separation efficiency.
- Conventional impactor overestimated PM2.5 concentrations.
- At high-temperature sampling, grease-coated impaction plate enhanced overestimation.
- Quartz filter decreased overestimation but bounce and re-entrainment still remained.
Two ISO standard methods for in-stack sampling and measurement of PM2.5 and PM10 mass concentrations in flue gas from stationary sources were published in 2009 (ISO 23210, conventional cascade impactors) and 2012 (ISO 13271, virtual impactors). The performances of these two methods in terms of PM2.5 separation efficiency and the accuracy of measured mass concentration were compared at the same sampling point and conditions both using laboratory-scale model flue gas with different dust concentrations and using real flue gas sampled from a test facility for pulverized coal combustion. The virtual impactor showed very satisfactory performance for PM2.5 mass concentration and separation efficiency within the investigated range of mass concentrations and ambient conditions. The conventional cascade impactor method overestimated PM2.5 mass concentration by more than 25% due to particle bounce and re-entrainment of coarse particles from the collection plates. During in-stack PM2.5 sampling from coal combustion flue gas with reactive components at high temperature, the use of greased plates with the conventional impactor caused overestimation of mass concentration, even when grease with high temperature endurance was used. The use of a quartz-fiber filters on the impaction plates reduced overestimation but particle bounce and re-entrainment still remained.
PM2.5; PM10; Mass concentration; Stationary sources; Virtual impactor; Conventional impactor; Particle bounce.