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Design and validation of an advanced entrained flow reactor system for studies of rapid solid biomass fuel particle conversion and ash formation reactions
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Department of Chemical and Materials Engineering, San Jose State University, One Washington Square, San Jose, California, USA.
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Thermochemical Energy Conversion Laboratory (TEC-Lab))ORCID iD: 0000-0002-5777-9241
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Thermochemical Energy Conversion Laboratory (TEC-Lab))ORCID iD: 0000-0003-1095-9154
2018 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 6, article id 065101Article in journal (Refereed) Published
Abstract [en]

The design and validation of a newly commissioned entrained flow reactor is described in the present paper. The reactor was designed for advanced studies of fuel conversion and ash formation in powder flames, and the capabilities of the reactor were experimentally validated using two different solid biomass fuels. The drop tube geometry was equipped with a flat flame burner to heat and support the powder flame, optical access ports, a particle image velocimetry (PIV) system for in situ conversion monitoring, and probes for extraction of gases and particulate matter. A detailed description of the system is provided based on simulations and measurements, establishing the detailed temperature distribution and gas flow profiles. Mass balance closures of approximately 98% were achieved by combining gas analysis and particle extraction. Biomass fuel particles were successfully tracked using shadow imaging PIV, and the resulting data were used to determine the size, shape, velocity, and residence time of converting particles. Successful extractive sampling of coarse and fine particles during combustion while retaining their morphology was demonstrated, and it opens up for detailed time resolved studies of rapid ash transformation reactions; in the validation experiments, clear and systematic fractionation trends for K, Cl, S, and Si were observed for the two fuels tested. The combination of in situ access, accurate residence time estimations, and precise particle sampling for subsequent chemical analysis allows for a wide range of future studies, with implications and possibilities discussed in the paper.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2018. Vol. 89, no 6, article id 065101
National Category
Other Physics Topics
Identifiers
URN: urn:nbn:se:umu:diva-147729DOI: 10.1063/1.5030603ISI: 000437195200054PubMedID: 29960572Scopus ID: 2-s2.0-85048128383OAI: oai:DiVA.org:umu-147729DiVA, id: diva2:1206094
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-10-02Bibliographically approved
In thesis
1. Entrained flow studies on biomass fuel powder conversion and ash formation
Open this publication in new window or tab >>Entrained flow studies on biomass fuel powder conversion and ash formation
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Partikelomvandling och askbildning i pulverflammor
Abstract [en]

Reducing the global dependence on fossil fuels is of paramount importance in tackling the environmental challenges we face, not only tomorrow, but already today. Biomass offers a renewable supply of CO2-neutral raw material that can be converted into many different forms of fuels and valuable chemicals, making it a prime candidate for the technologies of tomorrow. However, the heterogeneous nature and distinctly different elemental composition of biomass compared to traditional fossil sources present new challenges to be solved. When it comes to thermochemical technologies, key issues concern fuel conversion efficiency, ash formation, ash/fuel interactions and ash/reactor material interactions.

The objective of the present thesis was to provide new knowledge and insights into thermochemical fuel conversion, in particular its application in entrained flow technologies. A laboratory-scale reactor was constructed, evaluated and was used to study several aspects of high-temperature entrained flow biomass fuel conversion. Pulverized fuel particles from different biomass sources were used, and their physical and chemical interactions with the surrounding atmosphere, the concurrent ash element release, ash formation, and phase interactions were also studied in detail. In addition to the entrained flow reactor designed and constructed for this purpose, the main method for data collection was in situ optical studies of converting particles, either while entrained in the flow or when impacting upon surfaces. Elemental composition analysis of collected samples and gas analysis were also performed, allowing for a deeper understanding of ash element fractionation and interactions and thus explaining the observed properties of the resulting deposits or slag.

The degree of conversion of fuels with very low ash content, such as stem wood, was well described and modeled by a novel method using optical data, offering a non-intrusive and non-destructive alternative to traditional techniques. Coupling computational fluid dynamics with optical data allowed for improved experimental data interpretation and provided improved accuracy for fuel particle residence time estimations, which is an important parameter when studying fast chemical reactions such as those taking place in reactors for entrained flow conditions. The results from studies on ash formation gave new insights into the feasibility of using dry-mixed K-rich additives for improving slag properties during gasification of Ca-rich and Si-rich fuels. Interpretations of the experimental results were supported by thermodynamic equilibrium calculations, and the conclusions highlight both possibilities and challenges in gasification with high fuel flexibility while at the same time producing a flowing slag. Applications and future implications are discussed, and new topics of interest are presented.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2018. p. 63
Keywords
Thermochemical biomass conversion, particle image velocimetry, gasification, entrained flow reactor, ash transformation, equilibrium calculations, slag formation
National Category
Inorganic Chemistry Chemical Engineering Energy Engineering
Identifiers
urn:nbn:se:umu:diva-152332 (URN)978-91-7601-937-5 (ISBN)
Public defence
2018-10-26, N430, Naturvetarhuset, Umeå, 10:00 (English)
Opponent
Supervisors
Funder
Bio4EnergySwedish Research CouncilSwedish Energy Agency
Available from: 2018-10-05 Created: 2018-10-02 Last updated: 2018-10-18Bibliographically approved

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Wagner, David R.Holmgren, PerSkoglund, NilsBroström, Markus

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