Search Results
You are looking at 11 - 14 of 14 items for
- Author or Editor: W. Maenhaut x
- Refine by Access: All Content x
Abstract
The chemical composition of aerosols emitted during coal combustion was studied as a function of particle size down to 0.01 
m. The aerosol collections were carried out in a 81 MW capacity boiler that burned Venezuelan coal in a circulating fluidized bed combustion chamber. The samples were analyzed with upstream of the electrostatic precipitator using a Berner low-pressure impactor, which was quipped with a cyclone pre-cutter to avoid overloading of the first impaction stages. The samples were analyzed by INAA for up to about 40 elements. The elemental concentrations in the particulate matter for each impaction stage were plotted as a function of stage number (particle size). For the elements Na, Al, K, Ca, Sc, Ti, V, Ga, La and Sm, the concentration variation was limited to a factor of 2 to 4, and the concentrations of these elements were lower for the initial and final impactor stages than for the intermediate particle sizes. The variations were also limited to a factor of 2–4 for Mn, Fe, As, Sb and Th, butall these elements showed increasing concentrations with decreasing particle size. Still other elements, such as Ni, Cr, Co, Za, W, Mo and the halogens, were highly enriched (up to 20–100 fold) in the fine particles when compared with the coarse particles.
Abstract
Abstract
Atmospheric aerosol samples were collected during spring sampling campaigns in 1988 and 1989 at Birkenes and Nordmoen in southern Norway. The aerosol collectors used included stacked filter units (SFUs), a low volume sampler (referred to as ILVS), which consists of a filter preceded by three impaction stages, and an 11-stage Berner low-pressure impactor (LPI). All samples were analyzed for up to about 40 elements by INAA and PIXE. The resuls obtained from parallel samplings were intercompared in terms of ratios ILVS/SFU and LPI/SFU, whereby these ratios were calculated separately for the coarse and fine size fractions. For the ILVS/SFU parallel samplings, excellent agreement was observed between the results for the fine fraction, with the overall mean average ratio (based on 21 samples and 22 elements) being 0.99±0.10. For the coarse fraction, the overall mean ILVS/SFU ratio (based on 21 elements) was 0.75±0.13. This low result is explained by different upper-particle-size cut-offs of the two samplers. For the parallel samplings with LPI and SFU, the agreement was poorer, but still reasonable. The atmospheric concentrations observed at the two sites in the two campaigns and also the LPI size distributions for the various elements are discussed briefly.
