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- Carlsson, Per, et al.
(författare)
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Slag Formation During Oxygen Blown Entrained-Flow Gasification of Stem Wood
- 2014
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 28:11, s. 6941-6952
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Tidskriftsartikel (refereegranskat)abstract
- Stem wood powders were fired in a mullite-lined pilot-scale oxygen-blown pressurized entrained-flow gasifier. During repeated campaigns involving increases in fuel load and process temperature, slag formations that eventuated in the blockage of the gasifier outlet were observed. These slags were retrieved for visual and chemical characterization. It was found that the slags had very high contents of Al and, in particular, high Al/Si ratios that suggest likely dissolution of the mullite-based refractory of the gasifier lining due to interactions with the fuel ash. Possible causes for the slag formation and behavior are proposed, and practical implications for the design of future stem wood entrained-flow gasifiers are also discussed
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| 2. |
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| 3. |
- Molinder, Roger, et al.
(författare)
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Characterization and cleanup of wastewater from pressurized entrained flow biomass gasification
- 2014
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 2:8, s. 2063-2069
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Tidskriftsartikel (refereegranskat)abstract
- Wastewater produced during pressurized entrained flow biomass gasification (PEBG) was characterized and cleaned in order to raise the technology readiness level of the PEBG concept. Scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA) were used to study material found in the water. The material was removed using filtration and the concentration of dissolved organic carbon (DOC), polyaromatic hydrocarbons (PAHs) and metals in filtered water was studied using standardized methods. Water was sampled during operation at three oxygen equivalence ratios (λ) and the results were compared to concentrations of gaseous hydrocarbons in the syngas. As λ increased, the amount of soot in the wastewater and the amount of soot precursors in the syngas was reduced. As a result the concentration of particles in the water was reduced and their composition shifted toward a higher percentage of inorganics (ash). PAH concentration trends in the water and in the syngas correlated and dissolved organic material in the water was reduced with increased λ. A particle removal efficiency of 98-99% was achieved using sedimentation and filtration while the DOC was reduced from ≈2.5 mg L-1 to below detection limit using granular activated carbon (GAC). © 2014 American Chemical Society.
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| 4. |
- Molinder, Roger, et al.
(författare)
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Feeding small biomass particles at low rates
- 2014
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Ingår i: Powder Technology. - : Elsevier BV. - 0032-5910 .- 1873-328X. ; 269, s. 240-246
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Tidskriftsartikel (refereegranskat)abstract
- Biomass particles (75-1000μm) were fed at 9.0-66.5mgmin-1 (2.9-21.7W) using a particle feeder that dispensed particles by gravity through an injection tube. Feed rate was controlled by altering the velocity of a pusher block. Particles were agitated using a vibration motor and fed onto a balance and mass readings were continuously logged. Factors impacting reproducibility and feed rate stability were investigated as well as the effects of particle size and of pusher block velocity. Statistical analysis was applied to investigate patterns in particle feed rate data. Particle aggregation was identified as a factor which influenced feed rate stability and thereby also influencing reproducibility. Feed rate correlated well with pusher block velocity (R2=0.99). Statistical analysis showed strong indications (P values <0.01) of two patterns (clustering and trends) in the feed rate data which were attributed to changes in particle bed appearance with time. With all else being equal, particle size affected feed rate but not feed rate stability. A higher vibration amplitude was needed to agitate smaller particles. It was concluded that particle agitation control is a key to stable feeding of small biomass particles at low rates.
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| 6. |
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| 7. |
- Öhrman, Olov G. W., et al.
(författare)
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Analysis of trace compounds generated by pressurized oxygen blown entrained flow biomass gasification
- 2014
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Ingår i: Environmental Progress and Sustainable Energy. - : Wiley. - 1944-7442. ; , s. 699-705
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Konferensbidrag (refereegranskat)abstract
- Trace compounds were measured in synthesis gas and waste water from a pilot scale pressurized entrained flow oxygen blown biomass gasifier. The feedstock used was milled soft stem wood powder. Gaseous trace compounds were analyzed by gas chromatography. Up to 20 ppm of hydrogen sulfide was observed in the cold synthesis gas and the concentration seemed to be independent of the oxygen equivalence ratio (ER). Benzene varied from 30 to 1100 ppm, strongly depended on the ER and correlated well with the methane concentration. The concentrations of acetylene and ethylene increased as the ER was reduced and could have acted as precursors for the observed soot particles which were characterized using thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. Common polycyclic aromatic hydrocarbons from high temperature biomass gasification such as pyrene, phenanthrene, fluoranthene, and naphthalene were observed in low concentrations in the soot, in the cold synthesis gas and also in the waste water from the quench. Inorganic elements from the feedstock were observed in the waste water. Comparisons were also made with previous results from a black liquor gasifier.
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