The Formation and Emission of Particulate Matter during the Combustion of Density Separated Coal Fractions
In: Energy & fuels, Jg. 22 (2008), Heft 6, S. 3844-3851
academicJournal
- print, 37 ref
Zugriff:
The present study is a further effort to extend our knowledge of the included and excluded mineral characteristics responsible for the formation of particulate matter (PM). A Chinese bituminous coal was first separated into three density fractions using the float-sink method: heavy (>2.0 g/cm3), medium (1.4-2.0 g/cm3) and light (<1.4 g/cm3). Then, combustion and pyrolysis of coal with different density fractions were carried out in a laboratory-scale drop tube furnace to understand the formation mechanism of inhalable particulate matter, less than 10 μm (PM10) and less than 1 μm (PM1). PM10 was collected with a 13-stage low pressure impactor (LPI) having aerodynamic cutoff diameters ranging from 10.0 to 0.03 μm for a size-segregated collection. The experimental results indicated that the light fraction of the coal produced 44 wt % of total PM10 and 45 wt % of total PM1. The medium fraction of the coal contributed 52 wt % of total PM10 and 49 wt % of total PM1. The heavy fraction contributed 4 wt % of total PM10 and 6 wt % of total PM1. The light fraction and the medium fraction of the coal contained mostly included mineral and the heavy fraction contained largely excluded minerals. The PM10 and PM1 contents formed by the excluded minerals were very low compared to those formed primarily from included minerals. The proportion of the minerals in the light density fraction converted into PM1 and PM10 was the highest, with their weight percentages being 9.59% and 43.49%, respectively. There were three reasons for this. One of reasons was the mineral particle size. The median mineral size in the light density fraction coal was smallest. However, the median size of each coal fraction was almost the same. Another reason was mineral transformation during combustion. The light fraction and the medium fraction of the coal contained mostly included minerals, and the heavy fraction contained largely excluded minerals. The transformations of included and excluded minerals were largely different and played a different role during coal combustion. The last reason was char fragmentation. Char formed by the light coal fraction was easier to fragment and subsequently formed more fine ash particles. This was because the swelling ratio, BET surface area, and total pore volume of char decreased with increasing parent coal density.
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The Formation and Emission of Particulate Matter during the Combustion of Density Separated Coal Fractions
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Autor/in / Beteiligte Person: | XIAOWEI, LIU ; MINGHOU, XU ; HONG, YAO ; DUNXI, YU ; DANGZHEN, LV ; KE, ZHOU |
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Zeitschrift: | Energy & fuels, Jg. 22 (2008), Heft 6, S. 3844-3851 |
Veröffentlichung: | Washington, DC: American Chemical Society, 2008 |
Medientyp: | academicJournal |
Umfang: | print, 37 ref |
ISSN: | 0887-0624 (print) |
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