| 1. |
- Davidsson, Kent, 1967, et al.
(författare)
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Potassium, chlorine, and sulfur in ash, particles, deposits, and corrosion during wood combustion in a circulating fluidized-bed boiler
- 2007
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 21:1, s. 71-81
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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.
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| 2. |
- Hak, Claudia S., 1976, et al.
(författare)
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A new approach to in-situ determination of roadside particle emission factors of individual vehicles under conventional driving conditions
- 2009
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 43:15, s. 2481-2488
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Tidskriftsartikel (refereegranskat)abstract
- A method for continuous on-road measurements of particle number emissions for both diesel- and petrol-fuelled vehicles is presented. The setup allows the determination of particle number emission factors on an individual vehicle basis by the simultaneous measurement of CO2 and particle concentrations. As an alternative to previous measurements on the kerbside, the sample is taken directly in the street, with the advantage of sampling in-situ within the exhaust plumes of passing vehicles, allowing the separation of the individual high-concentration plumes. The method was tested in two experiments that were conducted in the Gothenburg area. In the first study, which was performed at an urban roadside, we were able to determine particle emission factors from individual vehicles in a common car fleet passing the measurement site. The obtained emission factors were of the same order of magnitude (between 1.4 × 1012 and 1.8 × 1014 particles km−1) as values published in the recent literature for light duty vehicles. An additional on-road experiment was conducted at a rural road with four light duty reference vehicles (three of them petrol-powered and one diesel-powered) at driving speeds of 50 and 70 km h−1, realised with different engine speeds. The results of the traffic emission studies show that the method is applicable provided that instruments with an adequate dynamic range are used and that the traffic is not too dense. In addition, the variability in particle emissions for a specified driving condition was estimated.
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| 5. |
- Noda, Jun, 1969, et al.
(författare)
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Aerosol from Biomass Combustion in Northern Europe: Influence of Meteorological Conditions and Air Mass History
- 2019
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Ingår i: Atmosphere. - 2073-4433. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- Alkali-containing submicron particles were measured continuously during three months, including late winter and spring seasons in Gothenburg, Sweden. The overall aims were to characterize the ambient concentrations of combustion-related aerosol particles and to address the importance of local emissions and long-range transport for atmospheric concentrations in the urban background environment. K and Na concentrations in the particulate matter PM1 size range were measured by an Alkali aerosol mass spectrometer (Alkali-AMS) and a cluster analysis was conducted. Local meteorological conditions and trace gas and PM concentrations were also obtained for a nearby location. In addition, back trajectory analyses and chemical transport model (CTM) simulations were included for the evaluation. The Alkali-AMS cluster analysis indicated three major clusters: (1) biomass burning origin, (2) mixture of other combustion sources, and (3) marine origin. Low temperatures and low wind speed conditions correlated with high concentrations of K-containing particles, mainly owing to local and regional emissions from residential biomass combustion; transport of air masses from continental Europe also contribute to Cluster 1. The CTM results indicate that open biomass burning in the eastern parts of Europe may have contributed substantially to high PM2.5 concentrations (and to Cluster 1) during an episode in late March. According to the CTM results, the mixed cluster (2) is likely to include particles emitted from different source types and no single geographical source region seems to dominate for this cluster. The back trajectory analysis and meteorological conditions indicated that the marine origin cluster was correlated with westerly winds and high wind speed; this cluster had high concentrations of Na-containing particles, as expected for sea salt particles.
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| 8. |
- Svane, Maria, 1957, et al.
(författare)
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Cesium as a tracer for alkali processes in a circulating fluidized bed reactor
- 2006
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 20:3, s. 979-985
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Tidskriftsartikel (refereegranskat)abstract
- Addition of cesium salt has been used to study the removal rate, transport, and fate of alkali components during combustion of a mixture of wood chips and pellets in a 12-MW circulating fluidized bed (CFB) reactor. The alkali concentration in the flue gas was monitored with a recently developed aerosol mass spectrometer to provide on-line measurements of alkali-containing submicron particles. Cs2CO3 was fed with the fuel during a 5.5-h period, and the Cs concentration in the flue gas and in ash samples was followed for 70 h. Cesium addition resulted in a 1000-fold increase in Cs concentrations, followed by a slow decay of the concentrations during the following days. Cs was concluded to bind strongly to the fluidized bed material and to be removed with the bed ash or by slow release to the gas phase. The apparent rate coefficient for Cs removal from the bed was approximately 0.03 h(-1). After 70 h, 33 +/- 10% of the added cesium had been removed with the bottom ash, 7 +/- 5% with secondary cyclone ash, and 45 +/- 10% with the bag-house filter ash. About 15% of the Cs remained in the facility at this time, either bound to the fluidized bed material or as deposits on surfaces. Cesium compounds released from the bed participate in the formation of new particles that are efficiently collected by the bag-house filters. A minor Cs fraction also condenses on fly ash particles that are removed by the secondary cyclone. The study shows that the results of cesium addition can be followed in detail under typical operation conditions, and the potential of the tracer method for studies of transformations and fate of alkali compounds in commercial scale boilers is discussed.
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| 9. |
- Svane, Maria, 1957, et al.
(författare)
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Chemical analysis of individual alkali-containing aerosol particles: Design and performance of a surface ionization particle beam mass spectrometer
- 2004
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 38:7, s. 655-663
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Tidskriftsartikel (refereegranskat)abstract
- A mobile particle beam mass spectrometer has been developed to measure the alkali metal content in individual submicron aerosol particles. The instrument employs an aerodynamic inlet system for efficient sampling of particles into vacuum, and the detection of individual particles is based on decomposition and surface ionization on a hot platinum surface. A boxlike design of the hot ionizing surface is shown to limit problems associated with particle bounce effects and incomplete ionization, and the decomposition/ionization process is not sensitive to detailed particle properties. High transmission efficiencies and quantitative determination of the alkali metal content in individual particles with diameters down to 14 nm are demonstrated. Experiments with particles doped with alkali salt show that the size range may be extended down to a few nanometers after further improvements of the inlet system. High size resolution can be achieved with the instrument for particle sizes down to tens of nanometers, as illustrated by the detection of multiply charged particles passing through a DMA. The robustness of the instrument makes it suitable for field measurement applications, and the technique is demonstrated at a 12 MW biomass combustion facility. The performance of the instrument and further refinements of the technique are discussed, and potential applications in field and laboratory studies are outlined.
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