| 1. |
- Agar, David, et al.
(författare)
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A systematic study of ring-die pellet production from forest and agricultural biomass
- 2018
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 180, s. 47-55
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Tidskriftsartikel (refereegranskat)abstract
- Continuous global growth in the pellet production industry and renewable energy policy targets have driven interest in under-utilised lignocellulosic biomass. In this comprehensive study, pelleting trials were systematically carried out using a pilot-scale ring-die pellet press with eight different biomass feedstock; logging residues, pine bark, wheat straw, reed canary grass, coppiced willow, poplar and beech. A standard spruce/pine sawdust blend was pelleted as a reference material.Pellets were produced from feedstock at four different moisture content levels, through two press channel lengths and three replicate steady-state sampling periods. A total of 192 batches of 8 mm diameter pellets were produced within a press channel length and moisture content range of 30-60 mm and 9-17% respectively. Pellet production had a range of 141-206 kg h(-1) and relatively good pellet quality was achieved for a majority of the studied feedstock. The best pellet batches had a mechanical durability and bulk density range of 91-99% and 532-714 kg m(-3) respectively, corresponding to an energy density range of 8.3-12.5 GJ m(-3) (as received). The extruded pellet temperature ranged between 99 and 131 degrees C and was correlated to pellet bulk density for hardwoods, pine bark and forest residues. The normalised energy (reference value of 1) used in pelleting all materials varied between 0.76 and 1.3 being highest for the hardwoods and lowest for straw and forest residues.
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| 2. |
- Agar, David, et al.
(författare)
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Combining behavioural TOPSIS and six multi-criteria weighting methods to rank biomass fuel pellets for energy use in Sweden
- 2023
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Ingår i: Energy Reports. - 2352-4847. ; 10, s. 706-718
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Tidskriftsartikel (refereegranskat)abstract
- EU energy and climate policies continue to drive interest in biomass fuel pellets which can be produced from a wide variety of feedstock. The use of multi-criteria decision analysis (MCDA) to support feedstock selection has the potential for more transparent and better decision-making. This study applies the behavioural TOPSIS, a prominent MCDA technique, to rank pellets for energy use in Sweden produced from under-utilised forest and agricultural biomass. Seven criteria were used to assess and rank the biomass pellets. The alternatives include 88 types of pellets from 11 biomass materials. Possible attitudes of an expert towards the risk of losses (risk averse, risk neutral and risk-seeking) were combined with six sets of criteria weights obtained using six weighting methods – a total of 18 input settings (scenarios). Despite having different input settings, almost identical results were obtained in all scenarios, meaning that the rankings were stable and consistent. Across all 18 scenarios, pellets produced from a reference spruce/pine sawdust blend are ranked ahead of other pellet types. Pellets produced from Scots pine bark exhibited stable and consistent rankings across all scenarios; and thus this biomass is the second-best overall. The next best materials overall are poplar, reed canary grass and wheat straw, whereas torrefied pellets (torrefied beech, poplar and wheat straw) were ranked last in all scenarios. Combining behavioural TOPSIS and a variety of criteria-weighting methods is a meaningful way of improving decision-making with respect to producing a more valid and reliable ranking of biomass fuel pellets for energy use in Sweden.
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| 3. |
- Agar, David, et al.
(författare)
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Pelleting torrefied biomass at pilot-scale – Quality and implications for co-firing
- 2021
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Ingår i: Renewable Energy. - : Elsevier BV. - 0960-1481. ; 178, s. 766-774
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Tidskriftsartikel (refereegranskat)abstract
- The co-firing of solid biofuels in coal plants is an attractive and fast-track means of cutting emissions but its potential is linked to biomass densification. For torrefied materials this topic is under-represented in literature. This pilot-scale (121–203 kg h−1) pelleting study generated detailed knowledge on the densification of torrefied biomass compared to untreated biomass. Four feedstock with high supply availability (beech, poplar, wheat straw and corn cob) were studied in their untreated and torrefied forms. Systematic methods were used to produce 180 batches of 8 mm dia. pellets using press channel length (PCL) and moisture content (MC) ranges of 30–60 mm and 7.3–16.6% (wet basis) respectively. Analysis showed that moderate degrees of torrefaction (250–280 °C, 20–75 min) strongly affected pelleting behaviour. The highest quality black pellets had a mechanical durability and bulk density range of 87.5–98.7% and 662–697 kg m−3 respectively. Pelleting energy using torrefied feedstock varied from −15 to +53 kWh t−1 from untreated with increases in production fines. Optimal pelleting MC and PCL were reduced significantly for torrefied feedstock and pellet quality was characterised by a decrease in mechanical durability and an increase in bulk density. Energy densities of 11.9–13.2 GJ m−3 (as received) were obtained.
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| 4. |
- Biswas, Amit, et al.
(författare)
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Effect of pelletizing conditions on combustion behaviour of single wood pellet
- 2014
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 119:15, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents how pelletizing die temperature and moisture content affect combustion behaviour of single wood pellet. Pine wood particles with two different moisture contents (i.e. 1 wt.% and 12 wt.%) were pelletized in a laboratory-scale single pelletizer (single die pellets) at die temperature of 20, 100, 150 and 200 °C. The pellets were combusted in a laboratory scale furnace at 800 °C. Time required for single pellet combustion generally increased with both increase of pelletizing temperature and moisture content of biomass. In addition, combustion behaviour of single die pellets was significantly different than those produced in a pilot scale pelletizing plant (semi-industrial scale pellet). That difference was due to variation in physical properties of pellets (e.g. density, and morphology).
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| 5. |
- Borén, Eleonora, et al.
(författare)
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Off-gassing from 16 pilot-scale produced pellets assortments of torrefied pine : impact of torrefaction severity, storage time, pelletization parameters, and pellet quality
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Off-gassing from wood pellets poses risks in large scale handling chains - yet little is known on off-gassing from pellets of torrefied wood. This study reports CO, CO2, and O2 concentrations in off-gases during storage of 16 torrefied and two untreated pellets assortments. According to an experimental design, pellets were produced in pilot scale from pine chips torrefied at five different set points. Off-gassing was assessed in relation to storage conditions, torrefaction and pelletization parameters, and pellet quality. Pellets from the most severely torrefied pine formed CO, CO2, and consumed O2 similarly to untreated pellets. Off-gassing was positively correlated to pellet moisture content; however, the most severely torrefied also retained the least moisture. Open air storage (20–270 days) of torrefied chips prior to pelletization did not affect off-gassing levels. Results are important for safe handling; torrefied pellets can cause comparable levels as untreated pellets of CO, CO2, and O2.
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| 6. |
- Das, Atanu Kumar, et al.
(författare)
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A review on wood powders in 3D printing : processes, properties and potential applications
- 2021
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Ingår i: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 15, s. 241-255
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional (3D) printing is a technology that, for a multitude of raw materials, can be used in the production of complex structures. Many of the materials that currently dominate 3D printing (e.g. titanium, steel, plastics, and concrete) have issues with high costs and environmental sustainability. Wood powder is a widely available and renewable lignocellulosic material that, when used as a fibre component, can reduce the cost of 3D printed products. Wood powder in combination with synthetic or natural binders has potential for producing a wide variety of products and for prototyping. The use of natural binders along with wood powder can then enable more sustainable 3D printed products. However, 3D printing is an emerging technology in many applications and more research is needed. This review aims to provide insight into wood powder as a component in 3D printing, properties of resulting products, and the potential for future applications.
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| 7. |
- Das, Atanu Kumar, et al.
(författare)
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A review on wood powders in 3D printing: processes, properties and potential applications
- 2021
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Ingår i: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 15, s. 241-255
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Forskningsöversikt (refereegranskat)abstract
- Three-dimensional (3D) printing is a technology that, for a multitude of raw materials, can be used in the production of complex structures. Many of the materials that currently dominate 3D printing (e.g. titanium, steel, plastics, and concrete) have issues with high costs and environmental sustainability. Wood powder is a widely available and renewable lignocellulosic material that, when used as a fibre component, can reduce the cost of 3D printed products. Wood powder in combination with synthetic or natural binders has potential for producing a wide variety of products and for prototyping. The use of natural binders along with wood powder can then enable more sustainable 3D printed products. However, 3D printing is an emerging technology in many applications and more research is needed. This review aims to provide insight into wood powder as a component in 3D printing, properties of resulting products, and the potential for future applications.
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| 8. |
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| 9. |
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| 10. |
- Das, Atanu Kumar, et al.
(författare)
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Green Milling of Biomass and Implications for Conversion Processes
- 2021
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Konferensbidrag (refereegranskat)abstract
- The quality of biomass powders depends on the size reduction technology used to produce them. Attritional mills (e.g. hammer mills) require biomass that is chipped and pre-dried. These processes degrade the green chemical profile of biomass and complicate handling and storage. A multi-blade shaft mill (MBSM) produces fine powders in a single step from green biomass. This enhances utilisation in downstream biorefining processes. Investigations have evaluated the powder quality and the energy requirements of MBSM milling using pinewood at a range of moisture contents. The shape and size properties of powders were analysed using two-dimensional image analysis and surface features investigated by scanning electron microscopy. A higher fraction (55 to 80 %) of finer powders (< 0.5 mm) was observed through multi-blade milling in comparison to hammer milling (41 %). There were also significant differences in particle (MBSM powders produced from green logs) aspect ratios (0.54 to 0.58 vs. 0.36 to 0.43) and specific surface (33 to 56 mm-1 vs. 29 to 38 mm-1). The MBSM specific milling energy ranged from 99 to 232 kWh t−1 (dry mass (DM)). These results are promising for the conversion of biomass powders into value added products (e.g. bio-based chemicals and nanocellulose) and indicate that MBSM technology may have a niche application in biorefining.
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