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- Molinder, Roger, et al.
(författare)
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Extractives in the Scandinavian pulp and paperindustry : Current and possible future applications
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The forest industry is one of Sweden’s most important business sectors. Thanks to its biobased rawmaterials and products, the forest industry plays a key role in the development towards asustainable, circular economy. To meet market needs, and to drive the growth of the circulareconomy, the forest industry is continually developing its processes and products. It is seeking to useits raw material, the forest, as efficiently as possible and is constantly seeking to improve quality andincorporate new functions into materials and products.Pulp and paper makes up the largest part of the forest industry, followed by sawn wood productsand products made from paper and paperboard. 3.9 million tons of pulp and 10.1 million tons ofpaper were produced in Sweden in 2016.The pulp and paper industry uses stem wood as its raw material. Stem wood consists of cellulose,hemicellulose, lignin, and extractives. Cellulose and hemicellulose are separated in the pulpingprocess and the economically most important components in wood. Lignin and extractives areusually burned to provide the mill with heat and power, but the use/needs has changed over timedue to development of more energy efficient mills. Today lignin is extracted from the black liquor forexternal use, while extractives are fractionated and used for production of a wide range of productssuch as, biodiesel, adhesives, and chemical intermediates.The extractives make up between 3 and 5 weight-% of the wood and consists of a wide range ofcompounds. The majority of those compounds are fatty acids such as oleic- and linoleic acid androsin acids, such as abietic- and pimaric acid. The remaining compounds are commonly referred to as“neutrals” and are dominated by β-sitosterol. The extractives in Scots pine for example, consist of 70% fatty acids, 20 % rosin acids and 5 % neutrals.Today, the extractives are separated at the pulp and paper mills during the regeneration of cookingchemicals into a product called crude tall oil (CTO). 2.5 million metric tons of CTO is producedglobally with 80% of the production situated in North America and Scandinavia. 1.3 million tons isproduced in North America and 600 000 tons is produced in Scandinavia. 2.0 million metric tons iscurrently refined globally, while the rest is used internally by the mills for the production of heat andpower.CTO is currently refined into a range of products which can be divided up into (i) chemicalintermediates, (ii) biodiesel, and (iii) tall oil pitch. The chemical intermediates are mostly used for theproduction of adhesives, while the biodiesel is used as a transport fuel, and the tall oil pitch is usedfor production of heat and power.To meet market needs, and to drive the growth of the circular economy, extractives could potentiallybe used for the production of other products, either through new refinement routes of CTO or novelextraction and separation methods from the raw material. In order to identify opportunities for theproduction of other extractives based products, the extractives value chain must first be mapped.Second, refinement routes as well as extraction and separation methods suitable for isolation andprocessing of valuable compounds must be identified.
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| 3. |
- Winikka, Henrik, et al.
(författare)
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Particle formation during pressurized entrained flow gasification of wood powder : Effects of process conditions on chemical composition, nanostructure, and reactivity
- 2018
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Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180 .- 1556-2921. ; 189, s. 1339-1351
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Tidskriftsartikel (refereegranskat)abstract
- The influence of operating condition on particle formation during pressurized, oxygen blown gasification of wood powder with an ash content of 0.4 wt% was investigated. The investigation was performed with a pilot scale gasifier operated at 7 bar(a). Two loads, 400 and 600 kW were tested, with the oxygen equivalence ratio (λ) varied between 0.25 and 0.50. Particle concentration and mass size distribution was analyzed with a low pressure cascade impactor and the collected particles were characterized for morphology, elemental composition, nanostructure, and reactivity using scanning electron microscopy/high resolution transmission electron microscopy/energy dispersive spectroscopy, and thermogravimetric analysis. In order to quantify the nanostructure of the particles and identify prevalent sub-structures, a novel image analysis framework was used. It was found that the process temperature, affected both by λ and the load of the gasifier, had a significant influence on the particle formation processes. At low temperature (1060 °C), the formed soot particles seemed to be resistant to the oxidation process; however, when the oxidation process started at 1119 °C, the internal burning of the more reactive particle core began. A further increase in temperature (> 1313 °C) lead to the oxidation of the less reactive particle shell. When the shell finally collapsed due to severe oxidation, the original soot particle shape and nanostructure also disappeared and the resulting particle could not be considered as a soot anymore. Instead, the particle shape and nanostructure at the highest temperatures (> 1430 °C) were a function of the inorganic content and of the inorganic elements the individual particle consisted of. All of these effects together lead to the soot particles in the real gasifier environment having less and less ordered nanostructure and higher and higher reactivity as the temperature increased; i.e., they followed the opposite trend of what is observed during laboratory-scale studies with fuels not containing any ash-forming elements and where the temperature was not controlled by λ.
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