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Publications (10 of 12) Show all publications
Wiinikka, H., Sepman, A., Ögren, Y., Lindblom, B. & Nordin, L.-O. (2019). Combustion Evaluation of Renewable Fuels for Iron-Ore Pellet Induration. Energy & Fuels
Open this publication in new window or tab >>Combustion Evaluation of Renewable Fuels for Iron-Ore Pellet Induration
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2019 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029Article in journal (Refereed) Epub ahead of print
Abstract [en]

Induration (or sintering) of iron-ore pellets requires high temperature (∼1300 °C), which today is generated by burning fuel oil in the firing zone of the straight-grate plant (SG) or coal in the rotary kiln of grate-kiln (GK) plants. In this study, ∼150 kWth combustion experiments were used to investigate the opportunity of totally replacing fuel oil with H2 or pyrolysis oil and replacing coal with wood pellets or black pellets powder. For SG plants, the fuel oil can probably be replaced with either H2 or pyrolysis oil without any major concerns, except for slightly or much higher NOx emissions in the case of pyrolysis oil and H2, respectively. For GK induration machines, it is probably challenging to replace coal entirely with biomass since the temperature profile will be different, and there is a risk for increased ash related operational problems. For both SG and GK plants, the slightly lower O2 concentration in the flue gas observed during biomass combustion (pyrolysis oil, wood pellets, and black pellets) may, however, be negative for the induration process, and this needs to be clarified in future research.

Place, publisher, year, edition, pages
American Chemical Society, 2019
Keywords
Coal, Fuel oils, Gas plants, Iron ore pellets, Iron ores, Pelletizing, Pyrolysis, Sintering, Biomass combustion, Combustion experiments, High temperature, Operational problems, Pellet induration, Renewable fuels, Straight grate, Temperature profiles, Coal combustion
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39850 (URN)10.1021/acs.energyfuels.9b01356 (DOI)2-s2.0-85070712552 (Scopus ID)
Note

 Funding details: Energimyndigheten; Funding text 1: This work has been conducted as part of the HYBRIT research project RP1. We gratefully acknowledge financial support from the Swedish Energy Agency. HYBRIT (Hydrogen Breakthrough Ironmaking Technology) is a joint initiative of the three companies SSAB, LKAB, and Vattenfall with the aim of developing the world’s first fossil-free ore-based steelmaking route. Therese Vikström at RISE ETC is highly acknowledged for performing SEM/EDS analysis of impactor particles and the initial drawings of the experimental facility. Dr. Roger Molinder at RISE ETC is highly acknowledged for the linguistic improvement of the manuscript.

Available from: 2019-08-30 Created: 2019-08-30 Last updated: 2019-08-30Bibliographically approved
Toth, P., Brackmann, C., Ögren, Y., Mannazhi, M., Simonsson, J., Sepman, A., . . . Wiinikka, H. (2019). Experimental and numerical study of biomass fast pyrolysis oil spray combustion: Advanced laser diagnostics and emission spectrometry. Fuel, 252, 125-134
Open this publication in new window or tab >>Experimental and numerical study of biomass fast pyrolysis oil spray combustion: Advanced laser diagnostics and emission spectrometry
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2019 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 252, p. 125-134Article in journal (Refereed) Published
Abstract [en]

The objective of this work was to move towards developing a comprehensible Computational Fluid Dynamics (CFD) model to facilitate the predictive modeling of Fast Pyrolysis Oil (FPO) spray combustion. A CFD model was implemented from the literature and results were compared to 2D data from non-intrusive optical diagnostics involving Planar Laser Induced Fluorescence of the OH radical, Mie scattering imaging and two-color pyrometry using a laboratory-scale, CH 4 /air flat-flame with an air-assist atomizer. Furthermore, flame radiation and contributions from graybody sources, chemiluminescence and soot were studied experimentally using emission spectroscopy and Laser Induced Incandescence (LII). Reasonable qualitative agreement was found between experimental and model results in terms of flame structure and temperature. Emission spectroscopy and LII results revealed and confirmed earlier observations regarding the low soot concentration of FPO spray flames; furthermore, it was shown that a significant portion of flame radiation originated from graybody char radiation and chemiluminescence from the Na-content of the FPO. These suggest that the treatment of soot formation might not be important in future computational models; however, the description of char formation and Na chemiluminescence will be important for accurately predicting temperature and radiation profiles, important from the point of e.g., large-scale power applications. Confirmed low soot concentrations are promising from an environmental point of view.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Biomass fast pyrolysis oil, Emission spectroscopy, Laser diagnostics, Spray combustion, Two-color pyrometry
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38347 (URN)10.1016/j.fuel.2019.04.043 (DOI)2-s2.0-85064487596 (Scopus ID)
Note

 Funding details: Energimyndigheten; Funding text 1: This work was supported by the Swedish Energy Agency through projects 41895-1 and 44110-1 and through the Centre of Combustion Science and Technology (CECOST), incentive project 215.

Available from: 2019-05-06 Created: 2019-05-06 Last updated: 2019-06-17Bibliographically approved
Toth, P., Ögren, Y., Sepman, A., Vikström, T., Gren, P. & Wiinikka, H. (2019). Spray combustion of biomass fast pyrolysis oil: Experiments and modeling. Fuel, 237, 580-591
Open this publication in new window or tab >>Spray combustion of biomass fast pyrolysis oil: Experiments and modeling
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2019 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 237, p. 580-591Article in journal (Refereed) Published
Abstract [en]

In this work, we are the first to report a detailed comparison between the predictions of a current Computational Fluid Dynamics (CFD) model for describing Fast Pyrolysis Oil (FPO) spray combustion and results from a laboratory-scale experiment. The objectives were to assess the predictive power of the CFD model, evaluate its usefulness in a numerical optimization scenario and characterize the spray flame. The spray flame was produced by using an air-assist atomizer piloted by a CH4/air flat-flame. Pyrolysis oil from a cyclone fast pyrolysis plant was combusted. The flame was characterized by using two-color pyrometry, Tunable Diode Laser Absorption Spectroscopy and high-magnification shadowgraphy. Overall, the assessed model correctly predicted flame structure and seemed appropriate for engineering applications, but lacked predictive power in estimating droplet size distributions. Numerical results were the most sensitive to variations in the initial droplet size distribution; however, seemed robust to changes in the multicomponent fuel formulation. Several conclusions were drawn regarding FPO spray combustion itself; e.g., the amount of produced soot in the flames was very low and droplets exhibited microexplosion behavior in a characteristic size-shape regime. 

Keywords
biomass fast pyrolysis oil, spray combustion, computational fluid dynamics, optical diagnostics
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:ri:diva-35530 (URN)10.1016/j.fuel.2018.10.031 (DOI)2-s2.0-85054708357 (Scopus ID)
Funder
Swedish Energy Agency, 41985-1Swedish Energy Agency, 44110-1
Available from: 2018-10-30 Created: 2018-10-30 Last updated: 2019-06-17Bibliographically approved
Ögren, Y., Toth, P., Garami, A., Sepman, A. & Wiinikka, H. (2018). Development of a vision-based soft sensor for estimating equivalence ratio and major species concentration in entrained flow biomass gasification reactors. Applied Energy, 226, 450-460
Open this publication in new window or tab >>Development of a vision-based soft sensor for estimating equivalence ratio and major species concentration in entrained flow biomass gasification reactors
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2018 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 226, p. 450-460Article in journal (Refereed) Published
Abstract [en]

A combination of image processing techniques and regression models was evaluated for predicting equivalence ratio and major species concentration (H2, CO, CO2 and CH4) based on real-time image data from the luminous reaction zone in conditions and reactors relevant to biomass gasification. Two simple image pre-processing routines were tested: reduction to statistical moments and pixel binning (subsampling). Image features obtained by using these two pre-processing methods were then used as inputs for two regression algorithms: Gaussian Process Regression and Artificial Neural Networks. The methods were evaluated by using a laboratory-scale flat-flame burner and a pilot-scale entrained flow biomass gasifier. For the flat-flame burner, the root mean square error (RMSE) were on the order of the uncertainty of the experimental measurements. For the gasifier, the RMSE was approximately three times higher than the experimental uncertainty – however, the main source of the error was the quantization of the training dataset. The accuracy of the predictions was found to be sufficient for process monitoring purposes. As a feature extraction step, reduction to statistical moments proved to be superior compared to pixel binning.

Keywords
AI, Gasification diagnostics, Gaussian process regression, Image processing, Machine learning, Neural network, Process monitoring
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33999 (URN)10.1016/j.apenergy.2018.06.007 (DOI)2-s2.0-85048807165 (Scopus ID)
Available from: 2018-07-03 Created: 2018-07-03 Last updated: 2019-06-17Bibliographically approved
Ögren, Y., Gullberg, M., Wennebro, J., Sepman, A., Toth, P. & Wiinikka, H. (2018). Influence of oxidizer injection angle on the entrained flow gasification of torrefied wood powder. Fuel processing technology, 181, 8-17
Open this publication in new window or tab >>Influence of oxidizer injection angle on the entrained flow gasification of torrefied wood powder
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2018 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 181, p. 8-17Article in journal (Refereed) Published
Abstract [en]

In the present work, 5 different axisymmetric burners with different directions of the oxidizer inlets were experimentally tested during oxygen blown gasification of torrefied wood powder. The burners were evaluated under two different O2/fuel ratios at a thermal power of 135 kWth, based on the heating value of torrefied wood powder. The evaluation was based on both conventional methods such as gas chromatography measurements and thermocouples and in-situ measurements using Tunable Diode Laser Absorption Spectroscopy. It was shown that changes in the near burner region influence the process efficiency significantly. Changing the injection angle of the oxidizer stream to form a converging oxidizer jet increased process efficiency by 20%. Besides increased process efficiency, it was shown that improvements in burner design also influence carbon conversion and hydrocarbon production. The burner with the best performance also produced less CH4 and achieved the highest carbon conversion. The effect of generating swirl via rotating the oxidizer jet axes was also investigated. Swirl broadened or removed the impingement area between the fuel and oxidizer jets, however resulting in differences in performance within the measurement uncertainty.

Keywords
Biomass, Burner design, Entrained flow gasification, Process optimization, Syngas, TDLAS, Absorption spectroscopy, Carbon, Efficiency, Gas chromatography, Gasification, Optimization, Thermocouples, Conventional methods, Hydrocarbon production, Measurement uncertainty, Syn-gas, Tunable diode laser absorption spectroscopy, Uncertainty analysis
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35577 (URN)10.1016/j.fuproc.2018.09.005 (DOI)2-s2.0-85053436599 (Scopus ID)
Note

Funding details: Energimyndigheten; Funding text: This work was performed within the platform for entrained-flow gasification (Bio4Gasification) at the Swedish Gasification Centre financed by the Swedish Energy Agency and the member companies.

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2019-06-17Bibliographically approved
Wiinikka, H., Vikström, T., Wennebro, J., Toth, P. & Sepman, A. (2018). Pulverized Sponge Iron, a Zero-Carbon and Clean Substitute for Fossil Coal in Energy Applications. Energy & Fuels, 32(9), 9982-9989
Open this publication in new window or tab >>Pulverized Sponge Iron, a Zero-Carbon and Clean Substitute for Fossil Coal in Energy Applications
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2018 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 9, p. 9982-9989Article in journal (Refereed) Published
Abstract [en]

The direct combustion of recyclable metals has the potential to become a zero-carbon energy production alternative, much needed to alleviate the effects of global climate change caused by the increased emissions of the greenhouse gas CO2. In this work, we show that the emission of CO2 is insignificant during the combustion of pulverized sponge iron compared to that of pulverized coal combustion. The emissions of the other harmful pollutants NOx and SO2 were 25 and over 30 times lower, respectively, than in the case of pulverized coal combustion. Furthermore, 96 wt % of the solid combustion products consisted of micrometer-sized, solid or hollow hematite (α-Fe2O3) spheres. The remaining 4 wt % of products was maghemite (Î-Fe2O3) nanoparticles. According to thermodynamic calculations, this product composition implies near-complete combustion, with a conversion above 98%. The results presented in this work strongly suggest that sponge iron is a clean energy carrier and may become a substitute to pulverized coal as a fuel in existing or newly designed industrial systems.

Keywords
Carbon, Carbon dioxide, Climate change, Coal, Emission control, Gas emissions, Greenhouse gases, Hematite, Pulverized fuel, Sponge iron, Direct combustion, Energy applications, Global climate changes, Industrial systems, Product composition, Pulverized coal combustion, Pulverized coals, Thermodynamic calculations, Coal combustion
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35286 (URN)10.1021/acs.energyfuels.8b02270 (DOI)2-s2.0-85052297503 (Scopus ID)
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2019-06-17Bibliographically approved
Ögren, Y., Sepman, A., Qu, Z., Schmidt, F. M. & Wiinikka, H. (2017). Comparison of Measurement Techniques for Temperature and Soot Concentration in Premixed, Small-Scale Burner Flames. Energy & Fuels, 31(10), 11328-11336
Open this publication in new window or tab >>Comparison of Measurement Techniques for Temperature and Soot Concentration in Premixed, Small-Scale Burner Flames
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2017 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 10, p. 11328-11336Article in journal (Refereed) Published
Abstract [en]

Optical and intrusive measurement techniques for temperature and soot concentration in hot reacting flows were tested on a small-scale burner in fuel-rich, oxygen-enriched atmospheric flat flames produced to simulate the environment inside an entrained flow reactor. The optical techniques comprised two-color pyrometry (2C-PYR), laser extinction (LE), and tunable diode laser absorption spectroscopy (TDLAS), and the intrusive methods included fine-wire thermocouple thermometry (TC) and electrical low pressure impactor (ELPI) particle analysis. Vertical profiles of temperature and soot concentration were recorded in flames with different equivalence and O2/N2 ratios. The 2C-PYR and LE data were derived assuming mature soot. Gas temperatures up to 2200 K and soot concentrations up to 3 ppmv were measured. Close to the burner surface, the temperatures obtained with the pyrometer were up to 300 K higher than those measured by TDLAS. Further away from the burner, the difference was within 100 K. The TC-derived temperatures were within 100 K from the TDLAS results for most of the flames. At high signal-to-noise ratio and in flame regions with mature soot, the temperatures measured by 2C-PYR and TDLAS were similar. The soot concentrations determined with 2C-PYR were close to those obtained with LE but lower than the ELPI results. It is concluded that the three optical techniques have good potential for process control applications in combustion and gasification processes. 2C-PYR offers simpler installation and 2D imaging, whereas TDLAS and LE provide better accuracy and dynamic range without calibration procedures.

Keywords
Absorption spectroscopy, Atmospheric movements, Calibration, Combustion, Dust, Gasification, Pyrometers, Pyrometry, Signal to noise ratio, Soot, Thermocouples, Comparison of measurement techniques, Electrical low-pressure impactor, Entrained Flow Reactor, Fine-wire thermocouples, High signal-to-noise ratio, Measurement techniques, Process-control applications, Tunable diode laser absorption spectroscopy, Atmospheric temperature
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33179 (URN)10.1021/acs.energyfuels.7b01168 (DOI)2-s2.0-85032857034 (Scopus ID)
Note

Funding details: Energimyndigheten;

Funding details: Bio4Energy;

Funding details: Kempestiftelserna

Available from: 2018-01-22 Created: 2018-01-22 Last updated: 2019-06-17Bibliographically approved
Sepman, A., Ögren, Y. & Wiinikka, H. (2017). Optical techniques for characterizing the biomass particle flow fluctuations in lab- and pilot-scale thermochemical systems. Powder Technology, 313, 129-134
Open this publication in new window or tab >>Optical techniques for characterizing the biomass particle flow fluctuations in lab- and pilot-scale thermochemical systems
2017 (English)In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 313, p. 129-134Article in journal (Refereed) Published
Abstract [en]

The work demonstrates the performance of the optical extinction technique for real-time diagnostics of the fluctuations in biomass particle flows. The online measurements of fluctuations of density were used to determine the biomass particle mass flow fluctuations. Biomass flows were produced using laboratory biomass particle feeder (mass flux up to 10 g/min) and the hopper-screw feeding system of the pilot-scale entrained flow rector, mass flux up to 500 g/min, located at SP ETC in Piteå. The experiments showed that the time-averaged extinction appeared to be linearly related to the real particle mass flow. The relatively fast variations in biomass feeding rates measured using the extinction technique were confirmed by fast balance measurements (in laboratory feeder experiments) and by real-time tunable diode laser CO and H2O concentrations measured in the reactor core of the entrained flow gasifier.

Keywords
Entrained flow gasifier, Extinction, Particle feeder, Particle flows, Tunable diode laser, Feeding, Gasification, Light absorption, Light extinction, Mass transfer, Semiconductor lasers, Thermomechanical treatment, Balance measurement, Entrained flow gasifiers, Extinction techniques, On-line measurement, Particle flow, Real-time diagnostics, Thermochemical systems, Tunable diode lasers, Biomass
National Category
Physical Sciences
Identifiers
urn:nbn:se:ri:diva-29176 (URN)10.1016/j.powtec.2017.03.001 (DOI)2-s2.0-85014959681 (Scopus ID)
Available from: 2017-04-03 Created: 2017-04-03 Last updated: 2019-06-17Bibliographically 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 employed to measure several important process parameters at two different locations inside the reactor of an atmospheric air-blown 0.1 MW biomass gasifier. Direct TDLAS at 2298 nm was employed for CO and water 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 which correspond the first in situ measurements of K(g) and temperature in a reactor core and in biomass gasification respectively. Actual average temperatures in the reactor core were significantly higher than the uncorrected thermocouple measurements in the gas stream. The CO concentrations at the lower optical access port were comparable to those obtained by GC at the exhaust. In gasification mode similar H2O values were obtained by the two different TDLAS instruments. The reaction time was faster for peat than for stem wood.

Keywords
Biomass gasification, Carbon monoxide, Gas temperature, Potassium, Tunable diode laser absorption spectroscopy, Absorption spectroscopy, Biomass, Gas chromatography, Molecular spectroscopy, Peat, Reactor cores, Semiconductor lasers, Soot, Thermocouples, Equilibrium calculation, Measurement campaign, Optical path lengths, Soot volume fraction, Thermocouple measurements, Gasification
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-31081 (URN)10.1016/j.proci.2016.07.011 (DOI)2-s2.0-85002619768 (Scopus ID)
Note

 Funding details: Energimyndigheten; Funding details: Kempestiftelserna; Funding details: VR, Vetenskapsrådet; Funding text: The authors acknowledge financial support from the Swedish Research Council, the Swedish Energy Agency, the Kempe Foundations, the Swedish strategic research program Bio4Energy and the Swedish Center for Gasification.

Available from: 2017-09-01 Created: 2017-09-01 Last updated: 2019-06-17Bibliographically approved
Sepman, A., Ögren, Y., Gullberg, M. & Wiinikka, H. (2016). Development of TDLAS sensor for diagnostics of CO, H2O and soot concentrations in reactor core of pilot-scale gasifier. Applied physics. B, Lasers and optics (Print), 122(2), 1-12, Article ID 29.
Open this publication in new window or tab >>Development of TDLAS sensor for diagnostics of CO, H2O and soot concentrations in reactor core of pilot-scale gasifier
2016 (English)In: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 122, no 2, p. 1-12, article id 29Article in journal (Refereed) Published
Abstract [en]

This paper reports on the development of the tunable diode laser absorption spectroscopy sensor near 4350 cm−1 (2298 nm) for measurements of CO and H2O mole fractions and soot volume fraction under gasification conditions. Due to careful selection of the molecular transitions [CO (υ″ = 0 → υ′ = 2) R34–R36 and H2O at 4349.337 cm−1], a very weak (negligible) sensitivity of the measured species mole fractions to the temperature distribution inside the high-temperature zone (1000 K < T < 1900 K) of the gasification process is achieved. The selected transitions are covered by the tuning range of single diode laser. The CO and H2O concentrations measured in flat flames generally agree better than 10 % with the results of 1-D flame simulations. Calibration-free absorption measurements of studied species in the reactor core of atmospheric pilot-scale entrained-flow gasifier operated at 0.1 MW power are reported. Soot concentration is determined from the measured broadband transmittance. The estimated uncertainties in the reactor core CO and H2O measurements are 15 and 20 %, respectively. The reactor core average path CO mole fractions are in quantitative agreement with the µGC CO concentrations sampled at the gasifier output.

Place, publisher, year, edition, pages
Springer Berlin/Heidelberg, 2016
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-387 (URN)10.1007/s00340-016-6319-x (DOI)2-s2.0-84957948916 (Scopus ID)
Available from: 2016-06-22 Created: 2016-06-22 Last updated: 2019-06-17Bibliographically approved
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2253-6845

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