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| 2. |
- Eriksson, D., et al.
(författare)
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Characterization of Scots pine stump-root biomass as feed-stock for gasification
- 2012
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 104, s. 729-736
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Tidskriftsartikel (refereegranskat)abstract
- The main objective was to explore the potential for gasifying Scots pine stump-root biomass (SRB). Washed thin roots, coarse roots, stump heartwood and stump sapwood were characterized (solid wood, milling and powder characteristics) before and during industrial processing. Non-slagging gasification of the SRB fuels and a reference stem wood was successful, and the gasification parameters (synthesis gas and bottom ash characteristics) were similar. However, the heartwood fuel had high levels of extractives (≈19%) compared to the other fuels (2-8%) and thereby ≈16% higher energy contents but caused disturbances during milling, storage, feeding and gasification. SRB fuels could be sorted automatically according to their extractives and moisture contents using near-infrared spectroscopy, and their amounts and quality in forests can be predicted using routinely collected stand data, biomass functions and drill core analyses. Thus, SRB gasification has great potential and the proposed characterizations exploit it. © 2011 Elsevier Ltd.
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| 3. |
- Kuncarayakti, Hanindyo, et al.
(författare)
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SN 2017dio : A Type-Ic Supernova Exploding in a Hydrogen-rich Circumstellar Medium
- 2018
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 854:1
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Tidskriftsartikel (refereegranskat)abstract
- SN 2017dio shows both spectral characteristics of a type-Ic supernova (SN) and signs of a hydrogen-rich circumstellar medium (CSM). Prominent, narrow emission lines of H and He are superposed on the continuum. Subsequent evolution revealed that the SN ejecta are interacting with the CSM. The initial SN Ic identification was confirmed by removing the CSM interaction component from the spectrum and comparing with known SNe Ic and, reversely, adding a CSM interaction component to the spectra of known SNe Ic and comparing them to SN 2017dio. Excellent agreement was obtained with both procedures, reinforcing the SN Ic classification. The light curve constrains the pre-interaction SN Ic peak absolute magnitude to be around M-g = -17.6 mag. No evidence of significant extinction is found, ruling out a brighter luminosity required by an SN Ia classification. These pieces of evidence support the view that SN 2017dio is an SN Ic, and therefore the first firm case of an SN Ic with signatures of hydrogen-rich CSM in the early spectrum. The CSM is unlikely to have been shaped by steady-state stellar winds. The mass loss of the progenitor star must have been intense, M similar to 0.02 (epsilon(H alpha)/0.01)(-1) (nu(wind)/500 km s(-1)) (nu(shock)/10,000 km s(-1))M--3(circle dot) yr(-1), peaking at a few decades before the SN. Such a high mass-loss rate might have been experienced by the progenitor through eruptions or binary stripping.
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| 4. |
- Ma, Charlie, et al.
(författare)
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Ash Formation in Pilot-Scale Pressurized Entrained-Flow Gasification of Bark and a Bark/Peat Mixture
- 2016
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 30:12, s. 10543-10554
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Tidskriftsartikel (refereegranskat)abstract
- Pressurized entrained-flow gasification (PEFG) of bark and a bark/peat mixture (BPM) was carried out in a pilot-scale reactor (600 kWth, 7 bar(a)) with the objective of studying ash transformations and behaviors. The bark fuel produced a sintered but nonflowing reactor slag, while the BPM fuel produced a flowing reactor slag. Si was enriched within these slags compared to their original fuel ash compositions, especially in the bark campaign, which indicated extensive ash matter fractionation. Thermodynamically, the Si contents largely accounted for the differences in the predicted solidus/liquidus temperatures and melt formations of the reactor slags. Suspension flow viscosity estimations were in qualitative agreement with observations and highlighted potential difficulties in controlling slag flow. Quench solids from the bark campaign were mainly composed of heterogeneous particles resembling reactor fly ash particles, while those from the BPM campaign were flowing slags with likely chemical interactions with the wall refractory. Quench effluents and raw syngas particles were dominated by elevated levels of K that, along with other chemical aspects, indicated KOH(g) and/or K(g) were likely formed during PEFG. Overall, the results provide information toward development of woody biomass PEFG and indicate that detailed understanding of the ash matter fractionation behavior is essential.
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| 5. |
- Ma, Charlie, et al.
(författare)
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Characterization of reactor ash deposits from pilot-scale pressurized entrained-flow gasification of woody biomass
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:11, s. 6801-6814
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Tidskriftsartikel (refereegranskat)abstract
- Pressurized entrained-flow gasification of renewable forest residues has the potential to produce high-quality syngas suitable for the synthesis of transport fuels and chemicals. The ash transformation behavior during gasification is critical to the overall production process and necessitates a level of understanding to implement appropriate control measures. Toward this end, ash deposits were collected from inside the reactor of a pilot-scale O 2-blown pressurized entrained-flow gasifier firing stem wood, bark, and pulp mill debarking residue (PMDR) in separate campaigns. These deposits were characterized with environmental scanning electron microscopy equipped with energy-dispersive X-ray spectrometry and X-ray diffractometry. The stem wood deposit contained high levels of calcium and was comparatively insubstantial. The bark and PMDR fuels contained contaminant sand and feldspar particles that were subsequently evident in each respective deposit. The bark deposit consisted of lightly sintered ash aggregates comprising presumably a silicate melt that enveloped particles of quartz and, to a lesser degree, feldspars. Discontinuous layers likely to be composed of alkaline-earth metal silicates were found upon the aggregate peripheries. The PMDR deposit consisted of a continuous slag that contained quartz and feldspar particles dispersed within a silicate melt. Significant levels of alkaline-earth and alkali metals constituted the silicate melts of both the bark and PMDR deposits. Overall, the results suggest that fuel contaminants (i.e., quartz and feldspars) play a significant role in the slag formation process during pressurized entrained-flow gasification of these woody biomasses.
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| 6. |
- Weiland, Fredrik, et al.
(författare)
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Influence of process parameters on the performance of an oxygen blown entrained flow biomass gasifier
- 2015
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Ingår i: Fuel. - : Elsevier Ltd. - 0016-2361 .- 1873-7153. ; 153, s. 510-519
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Tidskriftsartikel (refereegranskat)abstract
- Pressurized, O2 blown, entrained flow gasification of pulverized forest residues followed by methanol production is an interesting option for synthetic fuels that has been particularly investigated in the Nordic countries. In order to optimize gasification plant efficiency, it is important to understand the influence of different operating conditions. In this work, a pressurized O2 blown and entrained flow biomass gasification pilot plant was used to study the effect of four important process variables; (i) the O2 stoichiometric ratio (λ), (ii) the load of the gasifier, (iii) the gasifier pressure, and (iv) the fuel particle size. Commercially available stem wood fuels were used and the process was characterized with respect to the resulting process temperature, the syngas yield, the fuel conversion and the gasification process efficiency. It was found that CH4 constituted a significant fraction of the syngas heating value at process temperatures below 1400 °C. If the syngas is intended for catalytic upgrading to a synthetic motor fuel where CO and H2 are the only important syngas species, the process should be optimized aiming for a process temperature slightly above 1400 °C in order to reduce the energetic losses to CH4 and C6H6. This resulted in a cold gas efficiency (based only on CO and H2) of 70%. The H2/CO ratio was experimentally determined within the range 0.45-0.61. Thus, the syngas requires shifting in order to increase the syngas composition of H2 prior to fuel synthesis.
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| 7. |
- Weiland, Fredrik, et al.
(författare)
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Pressurized entrained flow gasification of pulverized biomass - Experiences from pilot scale operation
- 2016
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Ingår i: Chemical Engineering Transactions. - 1974-9791 .- 2283-9216. - 9788895608419 ; 50, s. 325-330
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Tidskriftsartikel (refereegranskat)abstract
- One of the goals in the national energy strategy of Sweden is that the vehicle fleet should be independent of fossil fuels by 2030. To reach that goal and to domestically secure for supply of alternative fuels, one of the suggested routes is methanol production from forest residues via pressurized and oxygen blown entrained flow gasification. In this context, ongoing industrial research in a 1 MWth gasification pilot plant is carried out at SP Energy Technology Center (SP ETC) in Pitea, Sweden. The plant is operated with pulverized or liquid fuels at process pressures up to 10 bar and this work summarizes the experiences from over 600 hours of operation with forest based biomass fuels. This paper covers results from thorough process characterization as well as results from extractive samplings of both permanent gases and particulate matter (soot) from inside the hot gasifier. Furthermore, the challenges with pressurized entrained flow gasification of pulverized biomass are discussed. During the characterization work, four of the most important process parameters (i.e. oxygen stoichiometric ratio (λ), fuel load, process pressure and fuel particle size distribution) were varied with the purpose of studying the effect on the process performance and the resulting syngas quality. The experimental results showed that the maximum cold gas efficiency (CGE) based on all combustible species in the syngas was 75% (at λ=0.30), whereas the corresponding value based only on CO and H2 (with respect to further MeOH synthesis from the syngas) was 70% (at λ=0.35). As expected, the pilot experiments showed that both the soot yield and soot particle size was reduced by increasing λ. One of the additional conclusions from this work was that; minimizing heat losses from the gasifier is of utmost importance to optimize the process performance regarding energy efficiency (i.e. CGE). Therefore, a well-insulated refractory lined gasifier is the primary alternative in regards to reactor design to maximize the CGE. Future development of the PEBG process should focus on identifying suitable hot-phase refractory, that exhibit long life-time and can sustain the alkali-rich biomass ash under gasification conditions. In addition to this, the remaining issue around how to improve the slag flow from the reactor, by additives or fuel mixing, should be investigated.
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| 8. |
- Weiland, Fredrik, et al.
(författare)
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Pressurized oxygen blown entrained-flow gasification of wood powder
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:2, s. 932-941
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, an oxygen blown pilot scale pressurized entrained-flow biomass gasification plant (PEBG, 1 MWth) was designed, constructed, and operated. This Article provides a detailed description of the pilot plant and results from gasification experiments with stem wood biomass made from pine and spruce. The focus was to evaluate the performance of the gasifier with respect to syngas quality and mass and energy balance. The gasifier was operated at an elevated pressure of 2 bar(a) and at an oxygen equivalence ratio (λ) between 0.43 and 0.50. The resulting process temperatures in the hot part of the gasifier were in the range of 1100-1300 °C during the experiments. As expected, a higher λ results in a higher process temperature. The syngas concentrations (dry and N 2 free) during the experiments were 25-28 mol % for H2, 47-49 mol % for CO, 20-24 mol % for CO2, and 1-2 mol % for CH 4. The dry syngas N2 content was varied between 18 and 25 mol % depending on the operating conditions of the gasifier. The syngas H 2/CO ratio was 0.54-0.57. The gasifier cold gas efficiency (CGE) was approximately 70% for the experimental campaigns performed in this study. The synthesis gas produced by the PEBG has potential for further upgrading to renewable products, for example, chemicals or biofuels, because the performance of the gasifier is close to that of other relevant gasifiers.
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| 9. |
- Öhrman, Olov G. W., et al.
(författare)
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Pressurized oxygen blown entrained flow gasification of a biorefinery lignin residue
- 2013
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Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 115, s. 130-138
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Tidskriftsartikel (refereegranskat)abstract
- Renewable fuels could in the future be produced in a biorefinery which involves highly integrated technologies. It has been reported that thermochemical conversion (gasification) of lignocellulosic biomass has a high potential for end production of renewable biofuels. In this work, lignin residue from biochemical conversion of wheat straw was gasified in an oxygen blown pressurized entrained flow gasifier (PEBG) at 0.25-0.30 MWth, 0.45 < λ < 0.5 and 1 bar (g). A video camera mounted inside the PEBG was used to observe the flame during start up and during operation. Hydrogen (H 2), carbon monoxide (CO) and carbon dioxide (CO2) were the main gas components with H2/CO ratios varying during the gasification test (0.54-0.63). The methane (CH4) concentration also varied slightly and was generally below 1.7% (dry and N2 free). C2-hydrocarbons (< 1810 ppm) and benzene (< 680 ppm) were also observed together with low concentrations of hydrogen sulfide (H2S, < 352 ppm) and carbonyl sulfide (COS, < 131 ppm). The process temperature in the reactor was around 1200 C. The slag seemed to consist of Cristobalite (SiO2) and Berlinite (AlPO4) and Na, Ca, Mg, K and Fe in lower concentrations. Cooling of the burner will be necessary for longer tests to avoid safety shut downs due to high burner temperature. The cold gas efficiency and carbon conversion was estimated but more accurate measurements, especially the syngas flow, needs to be determined during a longer test in order to obtain data on the efficiency at optimized operating conditions. The syngas has potential for further upgrading into biofuels, but will need traditional gas cleaning such as acid gas removal and water gas shifting. Also, higher pressures and reducing the amount of N2 is important in further work.
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| 10. |
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