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Characterization and densification of carbonized lignocellulosic biomass

Rudolfsson, Magnus (2016). Characterization and densification of carbonized lignocellulosic biomass. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2016:61
ISBN 978-91-576-8624-4
eISBN 978-91-576-8625-1
[Doctoral thesis]

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This thesis focuses on developing two main areas: characterization and densification of carbonized lignocellulosic biomass.

Thermally treated biomass undergoes changes that enrich the content of carbon in the remaining solid fraction. The carbon content is correlated to the temperature and residence time of the treatment and affects the properties of the material as a fuel e.g. gross calorific value. Near infrared (NIR) spectroscopy was used to predict a wide range of variables from forest- and agro-based biomass thermally treated at 240 to 850 ˚C. The result showed that NIR provided excellent predictions e.g. for energy, carbon, oxygen and hydrogen contents.

The changes of the biomass properties after thermal treatment, such as torrefaction, change also the pelletizing properties. A parametric study was conducted at bench scale in a single pellet press tool where four parameters were examined with respect to pellet quality responses. The study showed a narrow process window for pelletizing at around 5% moisture content. Further pelletizing studies in pilot scale demonstrated that higher moisture contents were needed for satisfying pellet quality. This indicated that there is a discrepancy between the material’s moisture content before pelletizing and at the actual moment of feed layer formation and pelletizing. By drying both torrefied and untreated material it was shown that torrefied materials dried at a significantly higher rate. Thus, observed uneven pellet production caused by feed layer breakage was related to the drying rate due to heat from friction in the pellet press channels. This was demonstrated by developing two methods for cooling the pelletizing process: one with direct cooling by water injection and one with indirect cooling by coils in the die, and hereby reduce drying and keep the moisture content at a level where pelletizing was possible. This showed that cooling of the pelletizing process can be beneficial for the pellet quality.

The overall result for successful densification of thermally treated lignocellulosic biomass into a standardized commodity with high energy and bulk density stresses the need: (1) to find tools that characterize biomass facilitating suitable settings in the densification step; (2) to apply new innovative steps in sub-processes like cooling of the feed layer; and, finally, (3) to find matching combinations of torrefaction and pelletization.

Authors/Creators:Rudolfsson, Magnus
Title:Characterization and densification of carbonized lignocellulosic biomass
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2016
Depositing date:20 May 2016
Number of Pages:74
ILestander, T.A., Rudolfsson, M., Pommer, L., Nordin, A. (2014). NIR provides excellent predictions of properties of biocoal from torrefaction and pyrolysis of biomass. Green Chemistry, 16(12), pp. 4906-4913.
IIRudolfsson M, Stelte W., Lestander T.A. (2015). Process optimization of combined biomass torrefaction and pelletization for fuel pellet production – A parametric study. Applied Energy 140 378–384
IIILarsson, S.H., Rudolfsson, M., Nordwaeger, M., Olofsson, I. & Samuelsson, R. (2013). Effects of moisture content, torrefaction temperature, and die temperature in pilot scale pelletizing of torrefied Norway spruce. Applied Energy, 102, pp. 827-832.
IVRudolfsson M., Borén E., Pommer L., Nordin A., Lestander T.A. (2016). Effects of combined parameters for torrefaction and pelletization on wood pellet quality. Submitted manuscript.
VLarsson, S.H., Rudolfsson, M. Temperature control in energy grass pellet production - Effects on process stability and pellet quality. Applied Energy 97 (2012) 24-29.
VIRudolfsson M., Larsson S.H., Lestander T.A. (2016). New tool for improved control of sub-process interactions in rotating ring die pelletizing of torrefied biomass. Manuscript
Place of Publication:Umeå
Publisher:Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8624-4
ISBN for electronic version:978-91-576-8625-1
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:K Forestry > K50 Processing of forest products
P Natural resources > P06 Renewable energy resources
Subjects:(A) Swedish standard research categories 2011 > 2 Engineering and Technology > 209 Industrial Biotechnology > Bioenergy
Agrovoc terms:picea abies, pinus sylvestris, salix, phalaris arundinacea, wood, lignocellulose, biomass, heat treatment, torrefaction, wood density, pelleting, spectroscopy
Keywords:densification, characterization, torrefaction
Permanent URL:
ID Code:13395
Faculty:S - Faculty of Forest Sciences
Department:(S) > Department of Forest Biomaterials and Technology (from 131204)
Deposited By: Magnus Rudolfsson
Deposited On:23 May 2016 05:39
Metadata Last Modified:10 Sep 2020 13:41

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