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- Nilsson, Patrik, et al.
(författare)
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Sampling and Characterization of Sub-Micrometer High-Temperature Particles Present in the Product Gas from a Circulating Fluidized-Bed Biomass Gasifier
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:6, s. 3290-3295
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Tidskriftsartikel (refereegranskat)abstract
- The removal of particulate fine fractions by a proper high-temperature cleaning device is a very important issue in the development of the biorefinery concept. Therefore, in this investigation, particles from a 100 kW(th) steam-O-2 blown circulating fluidized-bed (CFB) gasifier were sampled and characterized. The sampling was performed with a specially designed heated dilution probe downstream of a high-temperature candle filter element. The dilution probe was followed by a bed of activated carbon to separate the condensed phase from the particle phase by reducing the supersahuation of the volatile material. Parallel measurements were performed by a scanning mobility particle sizer (SMPS) and sample collection by a cascade impactor assembly to obtain information about the particle size distribution and elemental analysis, respectively. The measured particle mass was found to be dominated by coarse particles from bed material together with high amounts of potassium, which is thought to have penetrated through the filter. The aim of this work is to validate the developed particle measuring setup by performing physical and chemical characterization of the fine-particle fraction that is not captured by the filtering system to avoid the catalytic deactivation of the downstream upgrading processing.
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| 2. |
- Rissler, Jenny, et al.
(författare)
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Effective Density Characterization of Soot Agglomerates from Various Sources and Comparison to Aggregation Theory
- 2013
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 47:7, s. 792-805
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Tidskriftsartikel (refereegranskat)abstract
- Soot particle (black carbon) morphology is of dual interest, both from a health perspective and due to the influence of soot on the global climate. In this study, the mass-mobility relationships, and thus effective densities, of soot agglomerates from three types of soot emitting sources were determined in situ by combining a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM). High-resolution transmission electron microscopy was also used. The soot sources were diesel engines, diffusion flame soot generators, and tapered candles, operated under varying conditions. The soot microstructure was found to be similar for all sources and settings tested, with a distance between the graphene layers of 3.7-3.8 angstrom. The particle specific surface area was found to vary from 100 to 260m(2)/g. The particle mass-mobility relationship could be described by a power law function with an average exponent of 2.3 (+/- 0.1) for sources with a volatile mass fraction <10% and primary particle sizes of 11-29nm. The diesel exhaust from a heavy duty engine at idling had a substantially higher volatile mass fraction and a higher mass-mobility exponent of 2.6. The mass-mobility exponent was essentially independent of the number of primary particles in the range covered (N-pp = 10-1000). Despite the similar exponents, the effective density varied substantially from source to source. Two parameters were found to alter the effective density: primary particle size and coating mass fraction. A correlation was found between primary particle size and mass-mobility relationship/effective density and an empirical expression relating these parameters is presented. The effects on the DMA-APM results of doubly charged particles and DMA agglomerate alignment were investigated and quantified. Finally, the dataset was compared to three theoretical approaches describing agglomerate particles' mass-mobility relationship. Copyright 2013 American Association for Aerosol Research
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