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Improving the efficiency of entrained flow gasifiers by real time in-situ diagnostics and burner design
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science. RISE ETC AB.ORCID iD: 0000-0002-6473-7090
2019 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Optimering av suspensionsförgasare med hjälp av laserdiagnostik och brännardesign (Swedish)
Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2019. , p. 110
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
URN: urn:nbn:se:ltu:diva-73406ISBN: 978-91-7790-348-2 (print)ISBN: 978-91-7790-349-9 (electronic)OAI: oai:DiVA.org:ltu-73406DiVA, id: diva2:1302131
Public defence
2019-06-14, E231, Luleå, 10:00 (English)
Opponent
Supervisors
Available from: 2019-04-04 Created: 2019-04-03 Last updated: 2019-05-17Bibliographically approved
List of papers
1. Development of a vision-based soft sensor for estimating equivalence ratio and major species concentration in entrained flow biomass gasification reactors
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.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-69320 (URN)10.1016/j.apenergy.2018.06.007 (DOI)000441688100036 ()2-s2.0-85048807165 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-06-11 (andbra)

Available from: 2018-06-11 Created: 2018-06-11 Last updated: 2019-04-04Bibliographically approved
2. Comparison of Measurement Techniques for Temperature and Soot Concentration in Premixed, Small-Scale Burner Flames
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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-65767 (URN)10.1021/acs.energyfuels.7b01168 (DOI)000413710300104 ()2-s2.0-85032857034 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-11-09 (andbra)

Available from: 2017-09-22 Created: 2017-09-22 Last updated: 2019-04-04Bibliographically approved
3. Influence of oxidizer injection angle on the entrained flow gasification of torrefied wood powder
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. 

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Entrained flow gasification, Process optimization, Burner design, TDLAS, Syngas, Biomass
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-71020 (URN)10.1016/j.fuproc.2018.09.005 (DOI)000449900500002 ()2-s2.0-85053436599 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-09-28 (svasva)

Available from: 2018-09-28 Created: 2018-09-28 Last updated: 2019-04-03Bibliographically approved
4. Optical techniques for characterizing the biomass particle flow fluctuations in lab- and pilot-scale thermochemical systems
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
Extinction, Tunable diode laser, Particle flows, Particle feeder, Entrained flow gasifier
National Category
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-73384 (URN)10.1016/j.powtec.2017.03.001 (DOI)000399508100015 ()2-s2.0-85014959681 (Scopus ID)
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-04-09Bibliographically approved
5. Real-time in situ multi-parameter TDLAS sensing in the reactor core of an entrained-flow biomass gasifier
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.

Keywords
Tunable diode laser absorption spectroscopy Biomass gasification Gas temperature Potassium Carbon monoxide
National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-73382 (URN)10.1016/j.proci.2016.07.011 (DOI)000393412600136 ()2-s2.0-85002619768 (Scopus ID)
Available from: 2019-04-02 Created: 2019-04-02 Last updated: 2019-04-09Bibliographically approved
6. Development of TDLAS sensor for diagnostics of CO, H2O and soot concentrations in reactor core of pilot-scale gasifier
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, 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.

National Category
Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-15631 (URN)10.1007/s00340-016-6319-x (DOI)000372256700007 ()2-s2.0-84957948916 (Scopus ID)f29f8453-7a7a-4b01-8d88-2f948ef419ed (Local ID)f29f8453-7a7a-4b01-8d88-2f948ef419ed (Archive number)f29f8453-7a7a-4b01-8d88-2f948ef419ed (OAI)
Note
Validerad; 2016; Nivå 2; 20160211 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-04-04Bibliographically approved

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