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Conference contributions | 2008

Evaluation of parameters determining PM emissions and their chemical composition in modern residential biomass heating appliances

Brunner T, Bärnthaler G, Obernberger I. Evaluation of parameters determining PM emissions and their chemical composition in modern residential biomass heating appliances, Int. Conf. World BIOENERGY 2008, 27th-29th of May 2008, Jönköping, Sweden.

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Conference contributions | 2017

Evaluation of the Combustion Behaviour of Straw, Poplar and Maize in a Small-Scale Biomass Boiler

Kelz J, Zemann C, Muschick D, Krenn O, Hofmeister G, Weissinger A, Gölles M. & Hochenauer C. Evaluation of the Combustion Behaviour of Straw, Poplar and Maize in a Small-Scale Biomass Boiler. Proceedings 25th European Biomass Conference and Exhibition, 12-15 June 2017, Stockholm, Sweden. p. 1958-1966

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In order to evaluate the combustion behaviour of new biomass feedstocks such as short rotation coppice (poplar wood chips), fuels from agriculture (wheat straw pellets) and biomass residues (maize spindle grits), comprehensive test runs investigating both particulate matter (PM) and gaseous emissions were performed. A commercially available small-scale biomass boiler, especially designed to enable high fuel flexibility, was used for this evaluation. The combustion behaviour was determined for various boiler load conditions and primary air ratios while maintaining a constant total air ratio. Based on wet chemical analyses of the fuels, fuel indexes were calculated to deliver primary information on the combustion behaviour to be expected. During the test runs appropriate operating conditions were determined for these new biomass feedstocks in order to optimise combustion parameters and to minimise PM and gaseous emissions as well as to inhibit ash related problems (slagging, ash deposit formation and corrosion). The optimisation of operating conditions by primary measures showed a big potential for a stable boiler operation combined with reduced emissions. The findings provide the basis for a further development of combustion systems as well as control systems for the combustion of new biomass feedstocks.


Conference Papers | 2019

Evaluation of the Operational Behaviour of Fixed-bed Biomass Gasifiers - A Novel Approach for Steady-state Analysis

Hollenstein C, Zemann C, Antolini D, Patuzzi F, Martini S, Baratieri M, Gölles M. Evaluation of the Operational Behaviour of Fixed-bed Biomass Gasifiers - A Novel Approach for Steady-state Analysis. Proceedings of the 27th European Biomass Conference and Exhibition, Vols. 27-30 May 2019, pp. 849-860, 2019.

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Assessing the operational behaviour of biomass gasification systems is a crucial basis for further improvements in terms of operational behaviour and robustness in order to increase the technologies’ operational and economic viability. However, in most fixed-bed biomass gasification systems not all parameters required for the assessment can be measured directly. Typically, unknown parameters are determined by using as many balance equations as parameters have to be determined neglecting the additional information provided by other available but not chosen balance equations. Thus, these approaches do not incorporate all measurement data available resulting in a lack of reliability in their results. A detailed analysis of these approaches emphasises that even small deviations in the measurement data can lead to significant deviations in the calculated parameters, demonstrating that individual choices of equations can be highly sensitive regarding measurement uncertainties.

Therefore, an adjusted weighted least squares approach is developed utilizing an overdetermined system of equations incorporating all balance equations simultaneously. Thus, all measurement data available is taken into account, minimizing the influences of measurement uncertainties on the determined parameters. A comprehensive analysis shows that this approach is less sensitive to measurement uncertainties, allowing for a more reliable and accurate assessment of fixed-bed biomass gasifiers.

Keywords: fixed-bed, gasification, mass balance, performance assessment


Peer Reviewed Scientific Journals | 2018

Evaluation of the Potential for Efficiency Increase by the Application of Model-Based Control Strategies in Large-Scale Solar Thermal Plants

Unterberger V, Lichtenegger K, Innerhofer P, Gerardts B, Gölles M. Evaluation of the Potential for Efficiency Increase by the Application of Model-Based Control Strategies in Large-Scale Solar Thermal Plants. International Journal of Contemporary ENERGY. 2018; 4(1): 549-559.

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This paper presents a systematic evaluation procedure to estimate the potential for performance improvement by applying model-based control strategies in large-scale thermal plants. The evaluation is performed separately for the low-level control which is in charge of the temperatures in the collector fields and for the high-level control which defines the general mode of operation of a plant. In order to evaluate the potential for the low-level control, simulation studies have been carried out, based on the assumption that the individual flows through the collector fields can be controlled separately. This can be achieved by an advanced model-based control which makes use of motor-driven control valves at the inlets of the collector fields. The potential of the high-level control has been evaluated by energy calculations based on measurement data from a typical large-scale solar thermal plant. The evaluation finally identified a potential for efficiency increase in the range of 8% for the low- level control and about 3% for the high-level control.

Contributions to trade journals | 2014

Experimental and modeling study of catalytic steam reforming of methane mixture with propylene in a packed bed reactor

Sadooghi P, Rauch R. Experimental and modeling study of catalytic steam reforming of methane mixture with propylene in a packed bed reactor. Int J Heat Mass Transfer. 2014;78:515-21.

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Producer gas from biomass gasification contains mainly hydrogen, carbon dioxide, carbon monoxide, methane and some other low molecular hydrocarbons like propylene. This paper reports mathematical simulation and experimental study of steam reforming of methane mixture with propylene in a packed bed reactor filled with nickel based catalysts. Due to the high heat input through the reformer tube wall and the endothermic reforming reactions, a two-dimensional pseudo-heterogeneous model that takes into account the diffusion reaction phenomena in gas phase as well as inside the catalyst particles has been used to represent temperature distribution and species concentration within the reactor. Steam reforming of propylene is faster and more selective than methane and it is shown that addition of propylene to the methane steam mixture reduces the conversion of methane. The obtained results play a key role in optimization and design of a commercial reactor. © 2014 Elsevier Ltd. All rights reserved.
 


Contributions to trade journals | 2015

Experimental and modeling study of hydrogen production from catalytic steam reforming of methane mixture with hydrogen sulfide

Sadooghi P, Rauch R. Experimental and modeling study of hydrogen production from catalytic steam reforming of methane mixture with hydrogen sulfide. Int J Hydrogen Energy 2015;40(33):10418-10426.

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Contributions to trade journals | 2012

Experimental and numerical investigations on a combined biomass-solar thermal system

Hartl M, Aigenbauer S, Helminger F, Simetzberger A, Malenkovic I. Experimental and numerical investigations on a combined biomass-solar thermal system. Energy Procedia. 2012;30:623-632. (peer reviewed)

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Peer Reviewed Scientific Journals | 2008

Experimental investigation of nitrogen species release from different solid biomass fuels as a basis for release models

Stubenberger G, Scharler R, Zahirović S, Obernberger I. Experimental investigation of nitrogen species release from different solid biomass fuels as a basis for release models. Fuel. 2008;87(6):793-806.

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Experimental data on the release of NOx precursors from solid biomass fuels during thermal conversion are necessary to study N release in general and to supply reliable data for the purpose of packed bed and gas phase conversion model development and validation. In this work the release of NOx precursors was studied at a lab-scale pot furnace (batch reactor) by taking measurements during the conversion process of solid biomass in a packed bed. The investigations were carried out with relevant woody biomass fuels, which cover a broad range of fuel N contents: sawdust, bark, waste wood and MDF board. The most important NOx precursor detected above the fuel bed under fuel rich conditions was NH3, while HCN was almost insignificant with the exception of sawdust. NO was detected mainly under air rich conditions. Furthermore, the experimental data were utilised to derive release functions for the relevant NOx precursors NO, NH3 and HCN. The release functions were implemented in an in-house empirical packed bed combustion model, which serves as a basis for a subsequent CFD N species gas phase calculation. © 2007 Elsevier Ltd. All rights reserved.


Peer Reviewed Scientific Journals | 2019

Experimental investigation on biomass shrinking and swelling behaviour: Particles pyrolysis and wood logs combustion

Caposciutti G, Almuina-Villar H, Dieguez-Alonso A, Gruber T, Kelz J, Desideri U, Hochenauer C, Scharler R, Anca-Couce A. Experimental investigation on biomass shrinking and swelling behaviour: Particles pyrolysis and wood logs combustion. Biomass and Bioenergy 2019;123:1-13.

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Biomass is a suitable energy source to reduce the carbon footprint and increase the use of renewable energy. However, the biomass exploitation is still slowed by many technical issues. In most practical applications, such as gasification or combustion devices, it is important to predict the fuel physical behavior in order to determine the emissions and heat release profile as well as for modeling and design purposes. Within this paper, the study of the dimensional evolution of a biomass fuel (beech wood) in pyrolysis and combustion processes were carried out with the use of the image analysis tool. Sizes from 15 mm to 300 mm characteristic length range were employed in the experiments and the collected data were related to the mass loss and temperature evolution of the biomass particle. It was found that for all the fuel sizes employed a similar volume reduction (60%–66%) was obtained at the end of pyrolysis. However, for the small particles with minor intra-particle gradients shrinkage took place mainly at the end of conversion, while for bigger particles the size variation patter was more linear. Furthermore, swelling was detected in the pyrolysis experiments, and it was higher for a bigger particle size, while cracking and fragmentation phenomena was observed for large wood logs combustion in the stove.


Other Presentations | 2012

Experimental investigations and design of a new apparatus for measurement of emissions from stored pellets

Trinkel, V. Experimental investigations and design of a new apparatus for measurement of emissions from stored pellets, Master Thesis, Vienna University of Technology, Vienna, Austria, 2012.

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Peer Reviewed Scientific Journals | 2016

Experimental investigations of hydrogen production from CO catalytic conversion of tar rich syngas by biomass gasification

Chianese S, Fail S, Binder M, Rauch R, Hofbauer H, Molino A, Blasi A, Musmarra D. Experimental investigations of hydrogen production from CO catalytic conversion of tar rich syngas by biomass gasification. Catalysis Today. 15 November 2016;277: 181-192.

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In this paper, the activity of a cobalt/molybdenum (Co/Mo) commercial catalyst for the Water Gas Shift Reaction for hydrogen production was investigated in a three fixed-bed reactor pilot plant using a tar-rich synthesis gas from a full-scale biomass gasification plant as feed-stream. A parametric variation study was carried out to assess CO conversion (XCO) and selectivity for the water gas shift reaction as a function of the operating temperature (T) in the range 300–450 °C. The effects of four dry gas hourly space velocities (GHSV), Case A-Case D, two steam to dry synthesis gas ratios (H2O/SG), 56% v/v and 67% v/v, and a H2S concentration in the range 100–220 ppmv,db were investigated: the highest CO conversion (∼95%) was observed in the base case (Case A GHSV) at 67% v/v H2O/SG, and 450 °C, the lower the operating temperature the lower the CO concentration, the lower the gas hourly space velocity the higher the CO conversion and the higher the H2O/SG the higher the CO conversion. The effect of H2S variation on CO conversion was also studied, keeping the operating temperature constant (≈365 °C) and using the Case D GHSV: CO conversion increased as the H2S concentration increased and XCO ≈ 40%. Selectivity was not influenced by the parameters investigated. Finally, the effect of the catalyst on tar removal was studied and a CO conversion close to 85% was found.


Scientific Journals | 2018

Experimental parametric study in industrial-scale dual fluid bed gasification of woody biomass: Influences on product gas and tar composition

Kuba M, Hofbauer H. Experimental parametric study in industrial-scale dual fluid bed gasification of woody biomass: Influences on product gas and tar composition. Biomass and Bioenergy. 2018, 115: 35-44.

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Tar measurements at two industrial-scale DFB gasification plants showed clear trends regarding the influence of the above mentioned parameters on the product gas and tar composition. Since data was gathered during tar measurement campaigns over the course of four years the density of information in industrial-scale was increased significantly. As different operation points, e.g. different capacities of the power plant, are included in the consideration, the verisimilitude is comparably high.

It was shown, that reducing the operation temperature leads to an increase of the total tar amounts. However, while the concentration of the tar compounds benzofuran, styrene, and 1H-indene was increased when lowering the temperature, the concentration of naphthalene was decreased. These results were in good correlation with previous work from lab-scale investigations. The temperature did not have a measureable influence on the concentration of the tar compounds anthracene and ace-naphthalene, which was against former experience from lab-scale. The concentration of those larger PAHs anthracene and ace-naphthalene was more dominantly influenced by the bed height in the gasification reactor. Increasing the bed height led to a decrease of the concentration of larger PAHs while it did not have a distinctive influence on benzofuran, styrene, and 1H-indene.

The reactor design was identified as an influencing effect, due to the presence of a moving bed section above the inclined wall, where no fluidization is ensured. Thus, additional fluidization nozzles were installed to reduce the effect of the inclined wall. Finally, two operation points for optimized long-term operation were derived from the results.


Peer Reviewed Scientific Journals | 2015

Experimental validation of a thermodynamic boiler model under steady state and dynamic conditions

Carlon E, Verma VK, Schwarz M, Golicza L, Prada A, Baratieri M, et al. Experimental validation of a thermodynamic boiler model under steady state and dynamic conditions. Appl Energy. 2015;138:505-16.

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Nowadays dynamic building simulation is an essential tool for the design of heating systems for residential buildings. The simulation of buildings heated by biomass systems, first of all needs detailed boiler models, capable of simulating the boiler both as a stand-alone appliance and as a system component. This paper presents the calibration and validation of a boiler model by means of laboratory tests. The chosen model, i.e. TRNSYS "Type 869", has been validated for two commercially available pellet boilers of 6 and 12. kW nominal capacities. Two test methods have been applied: the first is a steady state test at nominal load and the second is a load cycle test including stationary operation at different loads as well as transient operation. The load cycle test is representative of the boiler operation in the field and characterises the boiler's stationary and dynamic behaviour. The model had been calibrated based on laboratory data registered during stationary operation at different loads and afterwards it was validated by simulating both the stationary and the dynamic tests. Selected parameters for the validation were the heat transfer rates to water and the water temperature profiles inside the boiler and at the boiler outlet. Modelling results showed better agreement with experimental data during stationary operation rather than during dynamic operation. Heat transfer rates to water were predicted with a maximum deviation of 10% during the stationary operation, and a maximum deviation of 30% during the dynamic load cycle. However, for both operational regimes the fuel consumption was predicted within a 10% deviation from the experimental values. © 2014 Elsevier Ltd.


Other Presentations | 2012

Experimentelle Entwicklung eines Pellet-Raumheizgerätes

Raab, A. Experimentelle Entwicklung eines Pellet-Raumheizgerätes, Bachelor Thesis, FH Oberösterreich, Wels, Österreich, 2012.

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Other Presentations | 2013

Experimentelle und numerische Untersuchung der Wärmeleitung in Depositionsschichten

Andonov, W. Experimentelle und numerische Untersuchung der Wärmeleitung in Depositionsschichten, Diploma Thesis, Technische Universität Graz, Graz, Austria, 2013.

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Der Schwerpunkt dieser Arbeit richtet sich auf die Kondensation von Aschedämpfen und die Feinstaubablagerung in Biomasse-befeuerten Kesseln. Zu diesem Zweck wurden in einer Versuchsanlage aschebildende Substanzen verdampft und anschließend auf einer gekühlten Sonde kondensiert. Als Modellsubstanz für die Aschedämpfe der Biomasse wurde Kaliumchlorid verwendet. Das Rauchgas wurde dabei mittels Verbrennung von Erdgas durch einen Gasbrenner zur Verfügung gestellt. Es sollten Informationen darüber gewonnen werden, welche Struktur die Depositionsschicht durch Kondensation oder Feinstaubablagerung ausbildet (Porosität, Homogenität, Festigkeit, Struktur) und wie die gebildete Depositionsschicht den Wärmeübergang beeinflusst. Die Berechnung des Kondensationsmassenstromes der aschebildenden Substanz mittels eines Ähnlichkeitsansatzes zum Wärmeübergang (Lewis-Ansatz) zeigt eine gute Übereinstimmung zu den experimentellen Versuchen. Die Depositionsschicht weist eine sehr hohe Porosität (p > 0,97) auf. Das Wärmeleitmodell „k maximum“ berechnet entsprechende Werte für die Wärmeleitfähigkeit der Depositionsschicht. Die Struktur der gebildeten Depositionsschicht ist von der Oberflächentemperatur der Sonde abhängig. Bei niedriger Sondentemperatur (T1 = 300 °C) bildet sich das Gefüge der Kondensationsschicht aus Kaliumchlorid als würfelförmige Kristalle aus, die „turmartig“ aufeinander herauswachsen. Diese Schicht zeichnet sich durch eine höhere Stabilität aus. Bei höherer Sondentemperatur (T2 = 500 °C) ist das Gefüge aus kleineren nadeligen und tröpfchenförmigen Kristallen aufgebaut, welche „baumartig“ herauswachsen. Wenn man die Kondensationsschicht am Depositionsring betrachtet wird ersichtlich, dass sich die Verteilung der Depositionsmenge in Abhängigkeit von der Depositionsmasse sehr unterschiedlich ausbildet. Bei geringer Depositionsmenge (m < 0,01 [g]) ist die Verteilung gleichmäßig um den Ring verteilt, bei höherer Depositionsmenge (m>0,01 [g]) befindet sich der Hauptteil der Depositionsmasse hauptsächlich auf der rauchgaszugewandten Seite der Sonde. Obwohl die Berechnung der Kondensationsmassenströme mit Hilfe des Ähnlichkeitsansatzes eine gute Übereinstimmung zeigt, sind die berechneten Werte stets etwas höher als die gemessenen Ergebnisse. Es wird vermutet, dass die Ursache in der hohen Instabilität der Depositionsschicht liegt, wodurch Erosionsvorgänge durch die vom Rauchgas erzeugten Schubspannungen die Depositionsschichtdicke reduzieren. Die Wärmeleitfähigkeit der Depositionsschicht ist aufgrund der hohen Porosität (hoher Anteil des fluiden Rauchgasanteils mit geringer Wärmeleitfähigkeit, kleiner Anteil des stark wärmeleitenden festen Kaliumchlorids) sehr niedrig, aber trotzdem deutlich höher als die Wärmeleitfähigkeit des Rauchgases. Sie liegt in der Größenordnung von k = 0,1-0,2 [W/mK]. Schon geringe Depositionsschichtmassen bewirken eine starke Verringerung des Wärmeüberganges und einen damit verbundenen hohen Temperaturgradienten in der Depositionsschicht. In dieser Arbeit wurden die für den Aufbau der Depositionsschicht maßgebenden Einflussfaktoren untersucht. Diese sind die Rauchgasgeschwindigkeit, die Salzfreisetzung, die Kondensationsdauer und die Oberflächentemperatur. Die Salzfreisetzung ist maßgebend für die Kondensationsmasse. Eine Verdoppelung der Salzfreisetzungsrate zeigte im untersuchten Wandbereich eine Verdoppelung der Kondensationsrate. Eine Verdoppelung der Rauchgasgeschwindigkeit führte zu einer geringen Abnahme der Kondensationsmasse bei gleichbleibenden Betriebsparametern, welches höchstwahrscheinlich durch Erosionsvorgänge bedingt ist. Die Sondenoberflächentemperatur zeigte im untersuchten Temperaturbereich von 300°C-500°C bei geringen Kondensationsmassen keinen Einfluss auf die Kondensationsrate. Bei größeren Depositionsschichten hatte die höhere Temperatur eine Verringerung der Kondensationsrate zur Folge.  


Other Presentations | 2012

Experimentelle Untersuchungen an einem Gasflammenreaktor zur Charakterisierung der Gasphasenverbrennung in Biomasserostfeuerungen

Kamnig, H. Experimentelle Untersuchungen an einem Gasflammenreaktor zur Charakterisierung der Gasphasenverbrennung in Biomasserostfeuerungen, Master Thesis, Technische Universität Graz, Graz, Austria, 2012.

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 Ziel der Diplomarbeit war die Bereitstellung von Messdaten für die Entwicklung eines Gasphasenverbrennungsmodells, welches den niedrig-turbulenten Strömungsbereich und den Einfluss der Strähnenbildung auf den Mischungsfortschritt von partiell vorgemischten Flammen über dem Brennstoffbett von Biomasse-Rostfeuerungen abbildet. Diese Arbeit beschäftigt sich mit der Konstruktion und dem Bau eines Flammenreaktors und einer Gasverteilungsstation zur Erzeugung von kalten Strömungen ohne chemische Reaktion und partiell vorgemischten Flammen mit chemischer Reaktion, welche die niedrig-turbulenten Strömungen über dem Brennstoffbett in Biomasse Rostfeuerungen genähert abbilden sollen. Zur Untersuchung der auftretenden Gas- und Luftsträhnen und deren Einfluss auf den Mischungsfortschritt über dem Biomasse Brennstoffbett, wurde für den Versuchsaufbau ein Düsenkonzept zur Gas- und Luftverteilung verwendet. In kalten Strömungen sollen die Mischungseffekte niedrig turbulenter Strömungen sowie der Mischungsfortschritt aufgrund der Strähnenbildung, entkoppelt von chemischen Reaktionen, untersucht werden. In den Flammen gilt es zusätzliche Einflüsse, wie die Expansion des Gases und die chemischen Reaktionen, zu untersuchen. Im Rahmen dieser Diplomarbeit wurden im Flammenreaktor extraktive FTIR- und RGA-Spezieskonzentrationsmessung in kalten Strömungen und in Flammen sowie optische LDA-Gasgeschwindigkeitsmessungen in kalten Strömungen durchgeführt. Für die finalen Messungen wurden nur Gaskonzentrationsmessungen mittels FTIR und RGA durchgeführt und diskutiert, da die LDA-Messeinheit nicht mehr zur Verfügung stand. Die Messergebnisse in kalten Strömungen mit einem CO2/N2-Gasgemisch und einem Luftstrom, liefern rotationssymmetrische CO2- und O2-Konzentrationsprofile. Die Messergebnisse zeigen, dass der Mischungsfortschritt entlang der Strömungsrichtung weitgehend entkoppelt ist von den Gaseintrittsgeschwindigkeiten vGas=2 m/s bis vGas=4. Die Konzentrationsergebnisse der Messungen mit den CO2/N2/Luft-Gemischen konnten mittels einer Stoffbilanz erfolgreich geprüft werden. Die Messergebnisse in kalten Strömungen entsprechen bezüglich der Gasgeschwindigkeiten zwischen 2 und 4 m/s sowie mit den Reynoldszahlen zwischen 800 und 9000 den laminaren bis niedrig-turbulenten Strömungsbedingungen von partiell vorgemischten Flammen über dem Brennstoffbett in Biomasse Rostfeuerungen. Die Messergebnisse der Flammenmessungen mit einem CH4/Luft-Gasgemisch und einem Luftstrom, liefern mit RGA- und FTIR-Messungen nicht reproduzierbare Ergebnisse innerhalb der Flamme und weisen große Gasspeziesasymmetrien in der Flamme auf. Die Messergebnisse zeigen, dass die Gaseintrittsgeschwindigkeiten vGas=2 m/s bis vGas=4 mit dem Verbrennungsfortschritt von CH4 in Strömungsrichtung gekoppelt sind. Die Konzentrationsergebnisse der Flammenmessungen mit einem CH4/Luft-Gemisch konnten mit den vorhandenen Messwerten nicht erfolgreich mittels einer Stoffbilanz geprüft werden. Zusammengefasst liefen die Konzentrationsmessungen in kalter Strömung sehr gute Messergebnisse in Hinblick auf Strömungsstabilität, rotationssymmetrische Strömungsausbildung und Messgenauigkeit. Für Messungen in kalten Strömungen sind die Messverfahren mittels FTIR und RGA zur Konzentrationsmessung und das LDA-Messverfahren zur Gasgeschwindigkeitsmessung zu empfehlen. Die RGA- und FTIR-Konzentrationsmessungen in den Flammen liefern keine zufriedenstellenden Messergebnisse aufgrund von Flammenasymmetrien sowie dem Einfluss der extraktiven Probenahme mittels einer Probenahmelanze. Für Flammenmessungen im Reaktor sind berührungsfreie, optische Messverfahren mit einer hohen Messauflösung zu empfehlen. Durchlichtverfahren benötigen zwei optische Zugänge zum Messraum. Für die Anwendung von Durchlichtverfahren müsste der Flammenreaktor von einem auf zwei optische Zugänge umgebaut werden.  


Conference contributions | 2013

Experimentelle Untersuchungen der Hochtemperaturkorrosion von 13CrMo4-5 in einem mit Biomasse befeuerten Fallrohr und ihre Übertragbarkeit auf Großfeuerungsanlagen

Gruber T. Experimentelle Untersuchungen der Hochtemperaturkorrosion von 13CrMo4-5 in einem mit Biomasse befeuerten Fallrohr und ihre Übertragbarkeit auf Großfeuerungsanlagen, VDI-Fachkonferenz: Feuerungen und Kessel - Beläge und Korrosion - in Großfeuerungsanlagen 2013, 24th-25th of June 2013, Düsseldorf, Germany.

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Scientific Journals | 2018

Experiments and modelling of NOx precursors release (NH3 and HCN) in fixed-bed biomass combustion conditions

Anca-Couce A, Sommersacher P, Evic N, Mehrabian R, Scharler R. Experiments and modelling of NOx precursors release (NH3 and HCN) in fixed-bed biomass combustion conditions. Fuel. 2018, 222: 529-537.

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There is a need to reduce NOx emissions, which can only be achieved through a detailed understanding of the mechanisms for their formation and reduction. In this work the release of the NOx precursors, NH3 and HCN, for different fuels is experimentally analysed and modelled in typical fixed-bed combustion conditions. It is shown that NH3 and HCN are released during the main devolatilization phase and the NH3/HCN ratio increases for fuels with a higher nitrogen content. A simplified two-steps model for their release is presented. The model can predict with a reasonable accuracy the release for fuels with a low nitrogen content, however deviations are present for fuels with a high nitrogen content, which probably arise due to a reduction of NH3 and HCN taking place already in the bed.


Contributions at other events | 2013

Extending the range of feedstock of the dual fluidized bed gasification process towards residues and waste

Wilk, V. Extending the range of feedstock of the dual fluidized bed gasification process towards residues and waste, Ph.D. Thesis, Vienna University of Technology, Vienna, Austria, 2013.

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Other Presentations | 2014

Fermentation of biomass from micro algae

Gruber M, Zohar E, Jerney J, Bochmann G, Obbard JP, Schagerl M, Fuchs W, Drosg B. Fermentation of biomass from micro algae, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

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Other Presentations | 2009

First test runs and tar analyses of a low temperature pyrolysis

Wolfesberger, U. First test runs and tar analyses of a low temperature pyrolysis, Master Thesis, Vienna University of Technology, Vienna, Austria, 2009.

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The global warming, the increasing CO2 emission, the combustion and dependency on fossil fuels, as well as the high-energy prices have resulted in an increasing demand in renewable energy sources. Biomass, as a renewable energy source, has the potential to contribute to the future energy mix in many countries. In this thesis the so-called low temperature or slow pyrolysis is chosen to convert biomass into energy rich products. Pyrolysis is a process to convert biomass directly into solid, liquid and gaseous products by thermal decomposition in absence of oxygen. The goal of the pilot plant Dürnrohr is to generate a combustible gas to substitute fossil fuels in the thermal power plant Dürnrohr. The complete process consists of individual steps. First of all the biomass is pyrolysed and pyrolysis gas and pyrolysis char are produced. The obtained pyrolysis gas is combusted in a fluidized bed combustion chamber implemented as afterburner. The following step is fluidized bed combustion of
the intermediate-stored pyrolysis char. Due to the use of different biomasses and adjustment of the individual steps, the process should be optimized for the application for the power plant Dürnrohr. One major point of the production of the pyrolysis gas is the amount of tar. The tar amount was analyzed during pyrolysis operation to find out how much tar is produced at which process settings with a main focus on the temperature. The gravimetric
analysis included gravimetric tar, dust, entrained char, water content and ph-value, as well as the GC/MS tars of the pyrolysis gas. All these data was sampled, analyzed and evaluated as well as discussed.


Peer-reviewed publications | 2013

Fischer Tropsch Synthesis to Biofuels (BtL Process)

Rauch R, Kiennemann A, Sauciuc A. Fischer Tropsch Synthesis to Biofuels (BtL Process). The role of catalysis for the sustainable production of Bio-fuels and Bio-chemicals. ISBN 978-0-444-56330-9 2013:397-443.

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Fischer-Tropsch (FT) synthesis is one option to produce liquid transportation fuels from carbon-containing feedstocks. In the past, FT synthesis was used mainly to convert coal or natural gas to diesel and gasoline. In the last decade, much R&D effort has been made to use this technology to convert biomass to a high-quality transportation fuel. In this chapter, the technology for BtL (conversion of biomass to liquid transportation fuels over FT synthesis) is described, from synthesis gas production including requirements on the gas quality to a detailed description of the FT synthesis itself. The main focus of this chapter is to give an overview of the types of catalysts, also including their preparation, reduction, and aging; the types of FT reactors; and also the reaction conditions including kinetic laws and mechanistic proposals.


Conference contributions | 2015

Forecasting the Pellet Boiler Stock in Austria until 2030 and Assessing the Potential to Reduce GHG Emissions and Substitute Fossil Fuels

Karner K, Schmid E, Strasser C, Kristöfel C, Enigl M. Forecasting the Pellet Boiler Stock in Austria until 2030 and Assessing the Potential to Reduce GHG Emissions and Substitute Fossil Fuels, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (visual presentation)

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Conference contributions | 2012

Frauen‐ und Familienförderung beginnt bei Männern – Systematisches Karenzmanagement für Mütter, Väter und das Unternehmen

Haslinger W. Frauen‐ und Familienförderung beginnt bei Männern – Systematisches Karenzmanagement für Mütter, Väter und das Unternehmen, Expertenforum K3 "Karenzmanagement macht Karriere" 2012, 9th of May 2012, Linz, Austria.

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Conference contributions | 2012

Fuel indexes –a novel method for the evaluation of relevant combustion properties of new biomass fuels

Sommersacher P, Brunner T, Obernberger I. Fuel indexes –a novel method for the evaluation of relevant combustion properties of new biomass fuels, Conference Impacts of Fuel Quality on Power Production and Environment 2012, 23th-27th of September 2012, Puchberg, Austria.

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The increasing demand for biomass fuels leads to the introduction of new biomass fuels into the market. These new biomass fuels (e.g., wastes and residues from agriculture and the food industry, short rotation coppices, and energy crops) are usually not well-defined regarding their combustion behavior. Therefore, fuel characterization methods with a special focus on combustion-related problems (gaseous NOx, HCl, and SOx emissions, ash-melting behavior, and PM emissions) have to be developed. For this purpose, fuel indexes are an interesting option. Fuel indexes are derived from chemical fuel analyses and are checked and evaluated regarding their applicability by measurements performed at lab- and real-scale combustion plants for a large variety of fuels. They provide the possibilities for a pre-evaluation of combustion-relevant problems that may arise from the use of a new biomass fuel. A possible relation to describe the corrosion risk is, for instance, the molar 2S/Cl ratio. The N content in the fuel is an indicator for NOx emissions, and the sum of the concentrations of K, Na, Zn, and Pb in the fuel can give a prediction of the aerosol emissions, whereas the molar (K + Na)/[x(2S + Cl)] ratio provides a first indication regarding the potential for gaseous HCl and SOx emissions. The molar Si/K ratio can supply information about the K release from the fuel to the gas phase. The molar Si/(Ca + Mg) ratio can give indications regarding the ash-melting temperatures for P-poor fuels. For P-rich fuels, the (Si + P + K)/(Ca + Mg) ratio can be used for the same purpose. The fuel indexes mentioned can provide a first pre-evaluation of combustion-relevant properties of biomass fuels. Therefore, time-consuming and expensive combustion tests can partly be saved. The indexes mentioned are especially developed for grate combustion plants, because interactions of the bed material possible in fluidized-bed combustion systems are not considered.


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