| 1. |
- Davidsson, Kent, 1967, et al.
(författare)
-
Potassium, chlorine, and sulfur in ash, particles, deposits, and corrosion during wood combustion in a circulating fluidized-bed boiler
- 2007
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 21:1, s. 71-81
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of the addition of chlorine and/or sulfur to the fuel on fly ash composition, deposit formation, and superheater corrosion has been studied during biomass combustion in a circulating fluidized-bed boiler. The chlorine (HCl (aq)) and sulfur (SO2 (g)) were added in proportions of relevance for the potassium chemistry. The composition of the bottom and the fly ashes was analyzed. Gas and particle measurements were performed downstream of the cyclone before the convection pass and the flue gas composition was recorded in the stack with a series of standard instruments and an FTIR analyzer. At the position downstream of the cyclone, a deposit probe was situated, simulating a superheater tube. Deposits on the probe and initial corrosion were examined. It is concluded that addition of sulfur and chlorine increases the formation of submicron particles leading to deposition of potassium sulfate and chloride. The results compare well with earlier work based on laboratory-scale experiments concerning effects of chlorine and sulfur on potassium chemistry.
|
|
| 2. |
- Kovacevik, Borka, 1972
(författare)
-
Alkali-containing aerosol particles-release during biomass combustion and ambient air concentrations
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Air pollution in the form of particles has considerable influence on human health and climate. Atmospheric aerosol particles arise from direct emissions of particles and from the conversion of certain gases to particles in the atmosphere. They are produced by a number of different sources and have a typical lifetime of about a week in the atmosphere. The chemical composition of the atmospheric aerosol is highly variable in time and space, and the different effects of the aerosol can usually not be understood without taking its multi-component nature into account. The overall aim of this thesis is to contribute to an improved understanding of climate effects and air quality issues related to aerosol particles. The thesis focuses on aerosol particles containing alkali-compounds, and particles produced by biomass combustion are of particular interest. Aerosol mass spectrometer techniques for highly sensitive and selective detection of alkali-containing particles have been further developed and applied in laboratory experiments, in fluidised bed combustion, and in ambient air measurements. The experimental techniques provide the chemical composition of individual aerosol particles with high time resolution and they are well suited for combustion aerosol applications, and for detection of sea salt particles that contain a large fraction of sodium compounds. Laboratory experiments were performed to study the emission of potassiumand sodium-containing compounds during rapid pyrolysis of birchwood. The alkali emission during the pyrolysis phase and from ash and char formed at high temperatures was characterized. Studies were also carried out during biomass combustion in a 12 MW(thermal) circulating fluidized-bed boiler. The effect of the addition of chlorine and/or sulphur to the fuel on fly ash composition, deposit formation, and superheater corrosion was investigated. Addition of sulphur and chlorine increased the formation of submicron particles and lead to enhanced deposition of potassium sulphate and chloride. The results compared well with results from earlier laboratory-scale experiments concerning the effects of chlorine and sulphur on potassium chemistry. The findings are of importance for actions aimed at minimizing alkali related corrosion and deposition problems during large-scale biomass conversion. The seasonal variation of the elemental composition of particulate matter in Skopje was studied by chemical analysis of samples collected with impactor technique. Major aerosol components were identified including mineral dust, oil combustion, traffic-related aerosol and secondary sulphate, while a separate biomass burning component could not be identified with the employed methods. Aerosol mass spectrometry was used to study the influence of atmospheric transport patterns and meteorology on alkali concentrations in Gothenburg. The observed potassium and sodium concentrations were concluded to be affected both by emissions from the nearby region and by long-range transport. Sodium-rich sea salt particles were favoured by westerly winds and high wind speeds, and were preferentially observed in air masses originating from the Atlantic. Potassium-rich particles originating from biomass burning were favoured by low temperatures and low wind speeds, and they were most abundant in air masses transported from Eastern and Central Europe.
|
|
| 3. |
- Kovacevik, Borka, 1972, et al.
(författare)
-
Elemental composition of fine particulate matter (PM2.5) in Skopje, FYR of Macedonia
- 2011
-
Ingår i: X-Ray Spectrometry. - : Wiley. - 0049-8246 .- 1097-4539. ; 40:4, s. 280-288
-
Tidskriftsartikel (refereegranskat)abstract
- Aerosol samples were collected at an urban background site in Skopje, Former Yugoslavic Republic of Macedonia, during four measurement campaigns from December 2006 to October 2007. An impactor was used to collect particulate matter (PM2.5) aerosol particles and the samples were analyzed for the concentrations of particulate mass, black carbon (BC), and 17 elements. The 12-h average PM2.5 concentrations varied in the range 10-140 mu g m(-3) with the highest concentrations measured during wintertime pollution episodes and during the summer period. Pair-wise correlations and crustal enrichment were studied and the data set was analyzed by factor analysis and positive matrix factorization. Major aerosol components were identified as mineral dust (main observed tracers Si, K, Ca, Ti, Fe, Sr, and Rb), combustion (BC, S, K, V, and Ni), traffic-related aerosol (Pb and Zn), and secondary sulfate combined with mineral dust. Combustion sources dominated during wintertime and were likely due to heavy oil combustion, biomass burning, and other industrial activities within the city area. Mineral dust was observed throughout the year, but the concentrations peaked during the unusually hot and dry summer of 2007. It is concluded that Skopje suffers from serious air pollution due to central and residential heating, the transport sector, and industrial activities within the city, and contributions from mineral dust increase the PM2.5 concentrations under dry periods. Topography and meteorological conditions aggravate the problems and make the air quality comparable with the conditions in other highly polluted cities in Southern Europe and worldwide.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Svane, Maria, 1957, et al.
(författare)
-
On-Line Chemical Analysis of Individual Alkali-Containing Aerosol Particles by Surface Ionization Combined with Time-of-Flight Mass Spectrometry
- 2009
-
Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 43:7, s. 653-661
-
Tidskriftsartikel (refereegranskat)abstract
- An aerosol mass spectrometer for measurements of the alkali metal content in individual submicron aerosol particles is presented. The instrument combines surface ionization of individual particles on a hot platinum surface with orthogonal acceleration time-of-flight mass spectrometry. The instrument simultaneously provides the content of different alkali metal elements in single particles with high sensitivity. The instrument is characterized in laboratory experiments, and determination of the alkali metal content is demonstrated for particle diameters of 50-500 nm. The technique is demonstrated in ambient air measurements at an urban background site, and sea spray particles and particles originating from biomass burning are identified based on their content of sodium and potassium. Possible further improvements and applications of the technique are discussed.
|
|
| 7. |
|
|
