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Syngas production by integrating thermal conversion processes in an existing biorefinery
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The use of carbon from fossil-based resources result in changes in the earth’s climate due to emissions of greenhouse gases. Biomass is the only renewable source of carbon that may be converted to transportation fuels and chemicals, markets now fully dominated by traditional oil supply. The biorefinery concept for upgrading and refinement of biomass feedstocks to value-added end-products has the potential to mitigate greenhouse gas emissions and replace fossil products. Most biorefineries use biochemical conversion processes and may have by-product streams suitable as feedstocks for thermal conversion and production of syngas. Further synthesis to value-added products from the syngas could increase the product output from the biorefinery.

The application of thermal conversion processes integrated into an existing biorefinery concept has been evaluated in this licentiate thesis work. Two by-product streams; hydrolysis (lignin) residue from an ethanol plant and biogas from wastewater treatment, have been investigated as gasification/reforming feedstocks. Also, the pre-treatment method torrefaction has been evaluated for improved gasification fuel characteristics and integration aspects. A new process and system concept (Bio2Fuels) with potential carbon negative benefits has been suggested and evaluated as an alternative route for syngas production by separating biomass into a hydrogen rich gas and a carbon rich char product.

The evaluation demonstrated that hydrolysis residue proved a suitable feedstock for gasification with respect to syngas composition. Biogas can be further reformed to syngas by combined biomass gasification and methane reforming, with promising results on CH4 conversion rate and increased H2/CO ratio at temperatures ≥1000°C. The pre-treatment method torrefaction was demonstrated to improve fuel qualities and may thus significantly facilitate entrained flow gasification of biomass residue streams. Also, integration of a torrefaction plant at a biorefinery site could make use of excess heat for drying the raw material before torrefaction. The Bio2Fuels concept was evaluated and found feasible for further studies.

The application of thermal conversion processes into an existing biorefinery, making use of by-products and biomass residues as feedstocks, has significant potential for energy integration, increased product output as well as for climate change mitigation.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2014. , 27 p.
Keyword [en]
biorefinery, biofuels, syngas, gasification, torrefaction, methane reforming, H2/CO ratio, system analysis, CO2 negativity
National Category
Chemical Process Engineering
Identifiers
URN: urn:nbn:se:umu:diva-92860ISBN: 978-91-7601-101-0 (print)OAI: oai:DiVA.org:umu-92860DiVA: diva2:744519
Presentation
2014-09-05, N460, Naturvetarhuset, Umeå Universitet, Umeå, 13:00 (Swedish)
Supervisors
Available from: 2014-12-19 Created: 2014-09-08 Last updated: 2014-12-19Bibliographically approved
List of papers
1. Torrefaction and Gasification of Hydrolysis Residue
Open this publication in new window or tab >>Torrefaction and Gasification of Hydrolysis Residue
2008 (English)In: 16th European Biomass Conference and Exhibition: Proceedings, 2008Conference paper, Published paper (Other academic)
Abstract [en]

When producing ethanol from lignocellulosic material using hydrolysis combined with fermentation, a large amount of residue consisting of mainly lignin is generated. A significant amount of energy is retained in this residue which may be utilised as a measure for the process to become economically viable. One possibility is as fuel in a gasification process for synthesis gas production, improving the fuel yield and the overall plant efficiency. Furthermore, the pre-treatment method torrefaction has been shown to significantly improve biomass fuel characteristics such as energy density, moisture content, feeding and hydrophobic properties, as well as significantly facilitate particle size reduction. Therefore, the process chain from hydrolysis residue to synthesis gas was investigated and demonstrated in the present work through bench-scale experiments in a batch torrefaction reactor and a bubbling fluidised bed gasifier. The results from the torrefaction work confirmed the improved fuel characteristics and the effects of process variables were evaluated by factorial designed experiments. The torrefaction residence time was identified as the most influential variable. The results from reactivity tests and gasification experiments indicate that hydrolysis residue and corresponding torrefied residue are suitable for synthesis gas production, with some improved feedstock handling characteristics for the latter.

Keyword
gasification, enzymatic hydrolysis, bio-ethanol
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-92861 (URN)
Conference
16th European Biomass Conference and Exhibition, Valencia, Spain, June 2-6, 2008
Available from: 2014-09-08 Created: 2014-09-08 Last updated: 2014-12-19
2. Syngas production by combined biomass gasification and in-situ methane reforming
Open this publication in new window or tab >>Syngas production by combined biomass gasification and in-situ methane reforming
(English)Manuscript (preprint) (Other academic)
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-97523 (URN)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2014-12-19Bibliographically approved
3. Effects of temperature and residence time on torrefaction of spruce wood
Open this publication in new window or tab >>Effects of temperature and residence time on torrefaction of spruce wood
Show others...
(English)Manuscript (preprint) (Other academic)
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-97521 (URN)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2016-08-15Bibliographically approved
4. Process and system integration aspects of biomass torrefaction
Open this publication in new window or tab >>Process and system integration aspects of biomass torrefaction
Show others...
2010 (English)In: 18th European Biomass Conference and Exhibition: Proceedings, 2010Conference paper, Published paper (Other academic)
Abstract [en]

The pre-treatment method torrefaction has been shown to significantly improve biomass fuel characteristics such as energy density, moisture content, milling energy, feeding and hydrophobic properties. These improvements establish torrefaction as a key process in facilitating an expanding market for biomass raw materials. Most of the previous work has focused on evaluating and optimizing the torrefaction process alone. However, to fully explore the maximum energy/exergy and cost efficiency of biomass torrefaction, the entire fuel supply chain and site specific systems must be considered; including logistics, scale and integration with other processes. The present work in progress aims to develop a model that incorporates optimization of the biomass supply chain and process integration systems together with the torrefaction process in order to avoid sub-optimization.

Keyword
analysis, conversion systems, integration, model, supply chain, torrefaction
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-92862 (URN)10.5071/18thEUBCE2010-OB3.4 (DOI)
Conference
18th European Biomass Conference and Exhibition, Lyon, France, May 3-7, 2010
Available from: 2014-09-08 Created: 2014-09-08 Last updated: 2017-09-28Bibliographically approved
5. Low-temperature slow pyrolysis of biomass for H2-enriched syngas production and carbon negativity
Open this publication in new window or tab >>Low-temperature slow pyrolysis of biomass for H2-enriched syngas production and carbon negativity
(English)Manuscript (preprint) (Other academic)
Abstract [en]

To optimally utilize biomass resources as feedstock for fuels and chemicals production as well as for a potential substantial carbon sink, a dedicated process and system concept is suggested. The desired outcome of the process is a hydrogen-enriched pyrolysis gas and a carbon-enriched char, also retaining the ash-forming elements. To obtain a transport-driven large-scale CO2 negative system, the char is suggested as co-firing fuel in a facility with carbon capture and storage technology. In the present work, the basis for this Bio2Fuels separation concept was evaluated by 1) analysis of previously published empirical data for pyrolysis, and 2) chemical equilibrium calculations. The former analysis indicated on the potential for a significant separation of H and C to the pyrolysis gas and char respectively, with ~80% of the hydrogen and 40-60% of the carbon from the raw feedstock present in the pyrolysis gas product. Based on analyzed thermochemical driving forces, most of the ash-forming elements can be expected to be retained in the char, and an ash and alkali-free gas may be achieved at temperatures below 500°C. In addition, chemical equilibrium modelling of the pyrolysis gas reforming demonstrated a significantly increased H2/CO ratio in the syngas compared to gasification of the raw biomass.

Keyword
biomass, slow pyrolysis, carbon negativity, hydrogen, pyrolysis gas reforming, syngas
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-97525 (URN)
Available from: 2014-12-19 Created: 2014-12-19 Last updated: 2017-09-28Bibliographically approved

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