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Simultaneous detection of potassium, water vapor and temperature with tunable diode laser absorption spectroscopy
Umeå University, Faculty of Science and Technology, Department of Physics. (Applied Laser Spectroscopy Group)
2015 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Existing tunable diode laser absorption spectroscopy (TDLAS) sensors for potassium (K) and for water vapor (H2O) and temperature were combined to enable simultaneous measurements in combustion and gasification processes. In-situ real-time detection of the above mentioned combustion parameters will improve the understanding of ash-formation during thermochemical conversion of biomass. Simultaneous measurements facilitate the experimental procedure and decrease the methodological uncertainty introduced by the heterogeneous nature of the pellets. The K sensor is based on direct absorption spectroscopy (DAS), whereas the H2O system employs wavelength modulation spectroscopy (WMS) together with two-line thermometry for temperature assessment. Two methods for combining the laser beams were evaluated, the first involving dichroic elements, the second using available fiber optic combiners. The latter method was considered advantageous. An existing LabVIEW program was modified to allow for simultaneous signal generation and data acquisition for both sensors. The sensors were then tested separately in a low pressure K cell and in ambient air. The combined sensor was applied to simultaneous measurements above various pelletized biofuels during combustion in a single pellet reactor (SPR). Significant difference in absolute concentration and time histories were observed between fuels, in particular for K and temperature. Significant K concentrations were only observed during the devolatilization phase. The combined sensor will be useful in fundamental combustion research.

Place, publisher, year, edition, pages
2015. , 34 p.
Keyword [en]
TDLAS, DAS, WMS, Simultaneous detection, Measurement, Potassium, Water vapor, Temperature, Biomass, Optics
National Category
Atom and Molecular Physics and Optics
URN: urn:nbn:se:umu:diva-105950OAI: diva2:839168
Subject / course
Examensarbete i teknisk fysik
Educational program
Master of Science Programme in Engineering Physics
2015-04-01, Universitetsklubben, Umeå universitet, Umeå, 10:00 (English)
Available from: 2015-08-17 Created: 2015-07-01 Last updated: 2015-08-17Bibliographically approved

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Norén, Edvin
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