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BETA
Schmidt, Florian, Dr.
Alternative names
Publications (10 of 33) Show all publications
Fatehi, H., Schmidt, F. M. & Bai, X.-S. (2018). Gas phase combustion in the vicinity of a biomass particle during devolatilization: model development and experimental verification. Combustion and Flame, 196, 351-363
Open this publication in new window or tab >>Gas phase combustion in the vicinity of a biomass particle during devolatilization: model development and experimental verification
2018 (English)In: Combustion and Flame, ISSN 0010-2180, E-ISSN 1556-2921, Vol. 196, p. 351-363Article in journal (Refereed) Published
Abstract [en]

A numerical and experimental study on the devolatilization of a large biomass particle is carried out to quantify the effect of homogeneous volatile combustion on the conversion of the particle and on the temperature and species distribution at the particle vicinity. A global chemical kinetic mechanism and a detailed reaction mechanism are considered in a one dimensional numerical model that takes into account preferential diffusivity and a detailed composition of tar species. An adaptive moving mesh is employed to capture the changes in the domain due to particle shrinkage. The effect of gas phase reactions on pyrolysis time, temperature and species distribution close to the particle is studied and compared to experiments. Online in situ measurements of average H2O mole fraction and gas temperature above a softwood pellet are conducted in a reactor using tunable diode laser absorption spectroscopy (TDLAS) while recording the particle mass loss. The results show that the volatile combustion plays an important role in the prediction of biomass conversion during the devolatilization stage. It is shown that the global reaction mechanism predicts a thin flame front in the vicinity of the particle deviating from the measured temperature and H2O distribution over different heights above the particle. A better agreement between numerical and experimental results is obtained using the detailed reaction mechanism, which predicts a wider reaction zone.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Biomass particle, Boundary layer, Combustion, Numerical modeling, Tunable diode laser absorption spectroscopy (TDLAS)
National Category
Chemical Sciences Atom and Molecular Physics and Optics Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-150268 (URN)10.1016/j.combustflame.2018.06.025 (DOI)000445848100031 ()2-s2.0-85049728200 (Scopus ID)
Available from: 2018-07-31 Created: 2018-07-31 Last updated: 2018-10-26Bibliographically approved
Fatehi, H., Qu, Z., Schmidt, F. M. & Bai, X.-S. (2017). Effect of Volatile Reactions on the Thermochemical Conversion of Biomass Particles. In: Yan, J Sun, F Chou, SK Desideri, U Li, H Campana, P Xiong, R (Ed.), 8TH INTERNATIONAL CONFERENCE ON APPLIED ENERGY (ICAE2016): . Paper presented at 8th International Conference on Applied Energy (ICAE), OCT 08-11, 2016, Beijing, PEOPLES R CHINA. ELSEVIER SCIENCE BV, 105
Open this publication in new window or tab >>Effect of Volatile Reactions on the Thermochemical Conversion of Biomass Particles
2017 (English)In: 8TH INTERNATIONAL CONFERENCE ON APPLIED ENERGY (ICAE2016) / [ed] Yan, J Sun, F Chou, SK Desideri, U Li, H Campana, P Xiong, R, ELSEVIER SCIENCE BV , 2017, Vol. 105Conference paper, Published paper (Refereed)
Abstract [en]

A numerical and experimental study on the conversion of a biomass particle is carried out to quantify the effect of homogeneous volatile combustion on the biomass pyrolysis. The numerical domain consists of a particle and its surrounding and the model considers detailed chemical kinetic mechanism for reaction of pyrolysis products. A detailed pyrolysis model is employed which provides the composition of pyrolysis products. The effect of gas phase reaction on the conversion time and temperature of the particle is analyzed and it was shown that the gas phase reactions results in shorter pyrolysis time. H2O mole fraction and temperature above a biomass pellet from wheat straw (WS) and stem wood (SW) were experimentally measured using tunable diode laser absorption spectroscopy (TDLAS) while recording the particle mass loss. The TDLAS data were used to validate the numerical model developed for biomass conversion. The results showed that by considering the gas phase reactions a good agreement between the measurement and the model prediction for mass loss and temperature can be achieved. For H2O mole fraction on top of the particle, on the other hand, some discrepancy between the model prediction and the experimental data was observed. Nevertheless, the difference in H2O mole fraction would be much larger by neglecting the gas phase reaction at the particle boundary.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Series
Energy Procedia, ISSN 1876-6102 ; 105
Keywords
Biomass Particle, Boundary Layer, Combustion, Numerical Modeling
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-140928 (URN)10.1016/j.egypro.2017.03.1007 (DOI)000404967904114 ()
Conference
8th International Conference on Applied Energy (ICAE), OCT 08-11, 2016, Beijing, PEOPLES R CHINA
Available from: 2017-10-23 Created: 2017-10-23 Last updated: 2018-06-09Bibliographically approved
Sepman, A., Ögren, Y., Qu, Z., Wiinikka, H. & Schmidt, F. M. (2017). Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier. Proceedings of the Combustion Institute, 36(3), 4541-4548
Open this publication in new window or tab >>Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier
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2017 (English)In: Proceedings of the Combustion Institute, ISSN 1540-7489, E-ISSN 1873-2704, Vol. 36, no 3, p. 4541-4548Article in journal (Refereed) Published
Abstract [en]

Tunable diode laser absorption spectroscopy (TDLAS) was used to measure several important process parameters at two different locations inside the reactor of an atmospheric, air-blown 0.1 MWth biomass gasifier. Direct TDLAS at 2298 nm was employed for carbon monoxide (CO) and water vapor (H2O), calibration-free scanned wavelength modulation spectroscopy at 1398 nm for H2O and gas temperature, and direct TDLAS at 770 nm for gaseous elemental potassium, K(g), under optically thick conditions. These constitute the first in situ measurements of K(g) and temperature in a reactor core and in biomass gasification, respectively. In addition, soot volume fractions were determined at all TDLAS wavelengths, and employing fixed-wavelength laser extinction at 639 nm. Issues concerning the determination of the actual optical path length, as well as temperature and species non-uniformities along the line-of-sight are addressed. During a 2-day measurement campaign, peat and stem wood powder were first combusted at an air equivalence ratio (lambda) of 1.2 and then gasified at lambdas of 0.7, 0.6, 0.5, 0.4 and 0.35. Compared to uncorrected thermocouple measurements in the gas stream, actual average temperatures in the reactor core were significantly higher. The CO concentrations at the lower optical access port were comparable to those obtained by gas chromatography at the exhaust. In gasification mode, similar H2O values were obtained by the two different TDLAS instruments. The measured K(g) concentrations were compared to equilibrium calculations. Overall, the reaction time was found to be faster for peat than for stem wood. All sensors showed good performance even in the presence of high soot concentrations, and real-time detection was useful in resolving fast, transient behaviors, such as changes in stoichiometry. Practical implications of in-situ TDLAS monitoring on the understanding and control of gasification processes are discussed.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Tunable diode laser absorption spectroscopy, Biomass gasification, Gas temperature, Potassium, Carbon monoxide
National Category
Chemical Process Engineering Atom and Molecular Physics and Optics Energy Systems Bioenergy Energy Engineering
Identifiers
urn:nbn:se:umu:diva-124706 (URN)10.1016/j.proci.2016.07.011 (DOI)000393412600136 ()
Available from: 2016-08-22 Created: 2016-08-22 Last updated: 2018-06-07Bibliographically approved
Weidemann, E., Andersson, P. L., Bidleman, T., Boman, C., Carlin, D. J., Collina, E., . . . Jansson, S. (2016). 14th congress of combustion by-products and their health effects-origin, fate, and health effects of combustion-related air pollutants in the coming era of bio-based energy sources. Environmental science and pollution research international, 23(8), 8141-8159
Open this publication in new window or tab >>14th congress of combustion by-products and their health effects-origin, fate, and health effects of combustion-related air pollutants in the coming era of bio-based energy sources
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2016 (English)In: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 23, no 8, p. 8141-8159Article in journal (Refereed) Published
Abstract [en]

The 14th International Congress on Combustion By-Products and Their Health Effects was held in UmeAyen, Sweden from June 14th to 17th, 2015. The Congress, mainly sponsored by the National Institute of Environmental Health Sciences Superfund Research Program and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, focused on the "Origin, fate and health effects of combustion-related air pollutants in the coming era of bio-based energy sources". The international delegates included academic and government researchers, engineers, scientists, policymakers and representatives of industrial partners. The Congress provided a unique forum for the discussion of scientific advances in this research area since it addressed in combination the health-related issues and the environmental implications of combustion by-products. The scientific outcomes of the Congress included the consensus opinions that: (a) there is a correlation between human exposure to particulate matter and increased cardiac and respiratory morbidity and mortality; (b) because currently available data does not support the assessment of differences in health outcomes between biomass smoke and other particulates in outdoor air, the potential human health and environmental impacts of emerging air-pollution sources must be addressed. Assessment will require the development of new approaches to characterize combustion emissions through advanced sampling and analytical methods. The Congress also concluded the need for better and more sustainable e-waste management and improved policies, usage and disposal methods for materials containing flame retardants.

Keywords
Products of incomplete combustion, Human health, Soot, Particles, Polychlorinated dibenzo-p-dioxins, Polychlorinated dibenzofurans, Congress paper
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-121585 (URN)10.1007/s11356-016-6308-y (DOI)000374994600105 ()26906006 (PubMedID)
Projects
Bio4Energy
Available from: 2016-06-27 Created: 2016-06-03 Last updated: 2019-09-02Bibliographically approved
Valiev, D., Qu, Z., Steinvall, E. & Schmidt, F. (2016). Measurement and simulation of atomic potassium in the plume above potassium hydroxide in a methane-air flat flame. In: : . Paper presented at 36th International Symposium on Combustion, Seoul, Korea, July 31 - August 5, 2016. , Article ID 4P057.
Open this publication in new window or tab >>Measurement and simulation of atomic potassium in the plume above potassium hydroxide in a methane-air flat flame
2016 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Other Mechanical Engineering Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-124996 (URN)
External cooperation:
Conference
36th International Symposium on Combustion, Seoul, Korea, July 31 - August 5, 2016
Available from: 2016-09-01 Created: 2016-09-01 Last updated: 2018-06-07
Rutkowski, L., Khodabakhsh, A., Johansson, A. C., Valiev, D. M., Lodi, L., Qu, Z., . . . Foltynowicz, A. (2016). Measurement of H2O and OH in a Flame by Optical Frequency Comb Spectroscopy. In: Proceedings Conference on Lasers and Electro-Optics: . Paper presented at Conference on Lasers and Electro-Optics (CLEO), JUN 05-10, 2016, San Jose, CA.
Open this publication in new window or tab >>Measurement of H2O and OH in a Flame by Optical Frequency Comb Spectroscopy
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2016 (English)In: Proceedings Conference on Lasers and Electro-Optics, 2016Conference paper, Published paper (Refereed)
Abstract [en]

We measure broadband H2O and OH spectra in a flame using near-infrared cavity-enhanced Fourier transform optical frequency comb spectroscopy, we retrieve temperature and OH concentration, and compare water spectra to an improved line list.

Series
Conference on Lasers and Electro-Optics, ISSN 2160-9020
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-132064 (URN)000391286403500 ()978-1-9435-8011-8 (ISBN)
Conference
Conference on Lasers and Electro-Optics (CLEO), JUN 05-10, 2016, San Jose, CA
Available from: 2017-03-17 Created: 2017-03-17 Last updated: 2018-06-09Bibliographically approved
Qu, Z., Steinvall, E., Ghorbani, R. & Schmidt, F. M. (2016). Tunable Diode Laser Atomic Absorption Spectroscopy for Detection of Potassium under Optically Thick Conditions. Analytical Chemistry, 88(7), 3754-3760
Open this publication in new window or tab >>Tunable Diode Laser Atomic Absorption Spectroscopy for Detection of Potassium under Optically Thick Conditions
2016 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 88, no 7, p. 3754-3760Article in journal (Refereed) Published
Abstract [en]

Potassium (K) is an important element related to ash and fine-particle formation in biomass combustion processes. In situ measurements of gaseous atomic potassium, K(g), using robust optical absorption techniques can provide valuable insight into the K chemistry. However, for typical parts per billion K(g) concentrations in biomass flames and reactor gases, the product of atomic line strength and absorption path length can give rise to such high absorbance that the sample becomes opaque around the transition line center. We present a tunable diode laser atomic absorption spectroscopy (TDLAAS) methodology that enables accurate, calibration-free species quantification even under optically thick conditions, given that Beer−Lambert’s law is valid. Analyte concentration and collisional line shape broadening are simultaneously determined by a least-squares fit of simulated to measured absorption profiles. Method validation measurements of K(g) concentrations in saturated potassium hydroxide vapor in the temperature range 950−1200 K showed excellent agreement with equilibrium calculations, and a dynamic range from 40 pptv cm to 40 ppmv cm. The applicability of the compact TDLAAS sensor is demonstrated by real-time detection of K(g) concentrations close to biomass pellets during atmospheric combustion in a laboratory reactor. 

National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-118864 (URN)10.1021/acs.analchem.5b04610 (DOI)000373656300046 ()
Available from: 2016-04-05 Created: 2016-04-05 Last updated: 2018-06-07Bibliographically approved
Qu, Z., Ghorbani, R., Valiev, D. & Schmidt, F. M. (2015). Calibration-free scanned wavelength modulation spectroscopy – application to H2O and temperature sensing in flames. Optics Express, 23(12), 16492-16499
Open this publication in new window or tab >>Calibration-free scanned wavelength modulation spectroscopy – application to H2O and temperature sensing in flames
2015 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 23, no 12, p. 16492-16499Article in journal (Refereed) Published
Abstract [en]

A calibration-free scanned wavelength modulation spectroscopy scheme requiring minimal laser characterization is presented. Species concentration and temperature are retrieved simultaneously from a single fit to a group of 2f/1f-WMS lineshapes acquired in one laser scan. The fitting algorithm includes a novel method to obtain the phase shift between laser intensity and wavelength modulation, and allows for a wavelengthdependent modulation amplitude. The scheme is demonstrated by detection of H2O concentration and temperature in atmospheric, premixed CH4/air flat flames using a sensor operating near 1.4 μm. The detection sensitivity for H2O at 2000 K was 4 × 10−5 cm−1 Hz-1/2, and temperature was determined with a precision of 10 K and absolute accuracy of ~50 K. A parametric study of the dependence of H2O and temperature on distance to the burner and total fuel mass flow rate shows good agreement with 1D simulations.

National Category
Atom and Molecular Physics and Optics Energy Systems
Identifiers
urn:nbn:se:umu:diva-105147 (URN)10.1364/OE.23.016492 (DOI)000356902500128 ()
Available from: 2015-06-18 Created: 2015-06-18 Last updated: 2018-06-07Bibliographically approved
Khodabakhsh, A., Qu, Z., Abd Alrahman, C., Johansson, A. C., Rutkowski, L., Schmidt, F. M. & Foltynowicz, A. (2015). Cavity-Enhanced Optical Frequency Comb Spectroscopy of High-Temperature Water in a Flame. In: 2015 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO): . Paper presented at Conference on Lasers and Electro-Optics (CLEO), MAY 10-15, 2015, San Jose, CA.
Open this publication in new window or tab >>Cavity-Enhanced Optical Frequency Comb Spectroscopy of High-Temperature Water in a Flame
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2015 (English)In: 2015 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), 2015Conference paper, Published paper (Refereed)
Abstract [en]

We demonstrate detection of broadband high-temperature water spectra in a laminar, premixed methane/air flat flame using high-resolution near-infrared cavity-enhanced optical frequency comb spectroscopy incorporating a fast-scanning Fourier transform spectrometer.

Series
Conference on Lasers and Electro-Optics, ISSN 2160-9020
Keywords
Absorption, Cavity resonators, Fires, Fourier transforms, Optical transmitters, Spectroscopy, Temperature measurement
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-118811 (URN)000370627102267 ()2-s2.0-84954052266 (PubMedID)978-1-55752-968-8 (ISBN)
Conference
Conference on Lasers and Electro-Optics (CLEO), MAY 10-15, 2015, San Jose, CA
Available from: 2016-04-18 Created: 2016-04-04 Last updated: 2018-06-07Bibliographically approved
Qu, Z. & Schmidt, F. M. (2015). In situ H2O and temperature detection close to burning biomass pellets using calibration-free wavelength modulation spectroscopy. Applied physics. B, Lasers and optics (Print), 119(1), 45-53
Open this publication in new window or tab >>In situ H2O and temperature detection close to burning biomass pellets using calibration-free wavelength modulation spectroscopy
2015 (English)In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 119, no 1, p. 45-53Article in journal (Refereed) Published
Abstract [en]

The design and application of an H2O/temperature sensor based on scanned calibration-free wavelength modulation spectroscopy (CF-WMS) and a single tunable diode laser at 1.4 μm is presented. The sensor probes two H2O absorption peaks in a single scan and simultaneously retrieves H2O concentration and temperature by least-squares fitting simulated 1f-normalized 2f-WMS spectra to measured 2f/1f-WMS signals, with temperature, concentration and nonlinear modulation amplitude as fitting parameters. Given a minimum detectable absorbance of 1.7×10-5 cm-1 Hz-1/2, the system is applicable down to an H2O concentration of 0.1 % at 1000 K and 20 cm path length (200 ppm·m). The temperature in a water-seeded lab-scale reactor (670-1220 K at 4 % H2O) was determined within an accuracy of 1 % by comparison with the reactor thermocouple. The CF-WMS sensor was applied to real- time in situ measurements of H2O concentration and temperature time histories (0.25 s time resolution) in the hot gases 2 to 11 mm above biomass pellets during atmospheric combustion in the reactor. Temperatures between 1200 and 1600 K and H2O concentrations up to 40 % were detected above the biofuels. 

National Category
Renewable Bioenergy Research Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-99509 (URN)10.1007/s00340-015-6026-z (DOI)000352292500007 ()
Funder
Bio4EnergySwedish Energy Agency
Available from: 2015-02-10 Created: 2015-02-09 Last updated: 2018-06-07Bibliographically approved
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