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Contributions to trade journals | 2013

Conversion of fuel nitrogen in a dual fluidized bed steam gasifier

Wilk V, Hofbauer H. Conversion of fuel nitrogen in a dual fluidized bed steam gasifier. Fuel. 2013;106:793-801.

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Contributions to trade journals | 2013

Conversion of mixed plastic wastes in a dual fluidized bed steam gasifier

Wilk V, Hofbauer H. Conversion of mixed plastic wastes in a dual fluidized bed steam gasifier. Fuel. 2013;107:787-799.

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Steam gasification of plastic materials was studied in a dual fluidized bed gasification pilot plant (DFB). Several types of plastics, which are available in large amounts in waste streams, were investigated: PE, PP, and mixtures of PE + PS, PE + PET and PE + PP. It was found that the product gas from PE was rich in CH4 and C2H4 and had a LCV of 25 MJ/N m 3. About 22% of PE was converted to the monomer C2H4. Different mixtures of PE with other polymers showed, that the concentrations of CH4 and C2H4increased with an increasing proportion of PE and that they were the main decomposition products of PE. The product gas from pure PP contained more CH4 and less C2H4compared to the product gas from PE. The polymer mixtures behaved differently from the pure substances. Significantly more H2 and CO were generated from PE + PP and PE + PS. It can be assumed that the decomposition products of the two polymers in the mixture interacted strongly and alternately influenced the gasification process. More water was converted, so the gas production increased. The reforming reactions were enhanced and yielded H2 and CO at the expense of CH4 and C2H4. The mixture of PE + PET differed from the other polymers because of the high oxygen content of PET. Thus, 28% of CO2 were measured in the product gas. By contrast, CO2 was in the range of 8%, when oxygen-free polymers were gasified and CO2 was only produced from reactions with steam. Gasification of polymers resulted in significantly high tar loads in the product gas in the range of 100 g/N m 3. The GCMS analysis of tars showed that tars from polymers mainly consisted of PAH and aro-matics. Naphthalene was the most important tar compound. © 2013 Elsevier Ltd. All rights reserved.


Contributions to trade journals | 2013

Conversion of mixed plastic wastes in a dual fluidized bed steam gasifier

Wilk V, Hofbauer H. Conversion of mixed plastic wastes in a dual fluidized bed steam gasifier. Fuel. 2013;107:787-99.

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Steam gasification of plastic materials was studied in a dual fluidized bed gasification pilot plant (DFB). Several types of plastics, which are available in large amounts in waste streams, were investigated: PE, PP, and mixtures of PE + PS, PE + PET and PE + PP. It was found that the product gas from PE was rich in CH4 and C2H4 and had a LCV of 25 MJ/N m 3. About 22% of PE was converted to the monomer C2H4. Different mixtures of PE with other polymers showed, that the concentrations of CH4 and C2H4 increased with an increasing proportion of PE and that they were the main decomposition products of PE. The product gas from pure PP contained more CH4 and less C2H4 compared to the product gas from PE. The polymer mixtures behaved differently from the pure substances. Significantly more H2 and CO were generated from PE + PP and PE + PS. It can be assumed that the decomposition products of the two polymers in the mixture interacted strongly and alternately influenced the gasification process. More water was converted, so the gas production increased. The reforming reactions were enhanced and yielded H2 and CO at the expense of CH4 and C2H4. The mixture of PE + PET differed from the other polymers because of the high oxygen content of PET. Thus, 28% of CO were measured in the product gas. By contrast, CO2 was in the range of 8%, when oxygen-free polymers were gasified and CO2 was only produced from reactions with steam. Gasification of polymers resulted in significantly high tar loads in the product gas in the range of 100 g/N m 3. The GCMS analysis of tars showed that tars from polymers mainly consisted of PAH and aro-matics. Naphthalene was the most important tar compound. © 2013 Elsevier Ltd. All rights reserved.


Conference contributions | 2013

Correlation between CO OFF-gassing and Linoleic fatty Acid content of wood Chips and Pellets

Emhofer W, Pöllinger-Zierler B, Siegmund B, Haslinger W, Leitner E. Correlation between CO OFF-gassing and Linoleic fatty Acid content of wood Chips and Pellets, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 1362-1364.

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During storage of wood pellets emissions of carbon monoxide (CO) and a large quantity of volatile organic compounds (VOCs) can be detected. These off-gases have been reported to originate from autooxidation reactions of woods own fatty acids, but data on CO formation rates based on fatty acid content is still scarce. In this paper data on the formation rates of CO from oxidation of pure linoleic acid are presented and compared to CO formation rates measured from spruce shavings, spruce sawdust and pellets made from the respective raw materials. To determine whether linoleic acid content is a realistic prediction tool for CO formation the fatty acid contents of the spruce materials have been determined and a comparison of predicted CO formation rates (based on linoleic acid content) to actually measured CO formation rates has been made. The results show that, albeit the fact that the determination of linoleic acid content is not the sole determining factor for an accurate prediction of CO formation rates, it is a helpful indicator in estimating a critical maximum rate of CO formation. The actual formation rates for CO, however, are typically lower than the predicted values and depend to a large extent on the history of the material and whether or not it has been activated. Activation includes treatments such as pelletizing, drying and/or milling.


Peer Reviewed Scientific Journals | 2013

Development of a biomass heating device for low energy and passive houses

Schwabl M, Schwarz M, Figl F, Carvalho L, Staudinger M, Kalb W, et al. Development of a biomass heating device for low energy and passive houses. Management of Environmental Quality. 2013;24(5):652-66.

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urpose: Decreasing energy demand due to improved building standards requires the development of new biomass combustion technologies to be able to provide individual biomass heating solutions. The purpose of this paper is, therefore, the development of a pellet water heating stove with minimal emission at high thermal efficiency. Design/methodology/approach: The single components of a 10 kW water heating pellet stove are analysed and partly redesigned considering the latest scientific findings and experimental know-how in combustion engineering. The outcome of this development is a 12 kW prototype which is subsequently down-scaled to a 6 kW prototype. Finally, the results of the development are evaluated by testing of an accredited institute. Findings: Based on an existing pellet water heating stove, the total excess air ratio was reduced, a strict air staging was implemented and the fuel supply was homogenized. All three measures improved the operating performance regarding emissions and thermal efficiency. The evaluation of the development process showed that the CO emissions are reduced by over 90 per cent during full load and by 30-60 per cent during minimum load conditions. Emissions of particulate matter are reduced by 70 per cent and the thermal efficiency increased to 95 per cent. Originality/value: The result represents a new state of technology in this sector for minimal emissions and maximal thermal efficiency, which surpasses the directives of the Eco label "UZ37" in Austria and "Blauer Engel" in Germany, which are amongst the most stringent performance requirements in the European Union. Hence this design possesses a high potential as heating solution for low and passive energy houses. © Emerald Group Publishing Limited.


Conference contributions | 2013

Development of a test gas generator for biomass gasification derived process gas - a test methodology for quality insurance and development

Martini S, Kleinhappl M. Development of a test gas generator for biomass gasification derived process gas - a test methodology for quality insurance and development, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 775-777.

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Conference contributions | 2013

Dual fluidized bed gasification: operational experiences and future developments

Wilk V, Hofbauer H. Gasification Technologies: Delivering the Potential, Workshop “Dual fluidized bed gasification: Operational experiences and future Developments”, 23rd of October, Newcastle, England, 2013.

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Other Presentations | 2013

Dynamic modelling of hydronic heating systems supplied by a biomass boiler for residential application: solutions for the optimization of the control strategy

Rimoldi, M. Dynamic modelling of hydronic heating systems supplied by a biomass boiler for residential application: solutions for the optimization of the control strategy, Master Thesis, Polytechnic University of Milan, Milan, Italy, 2013.

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Conference contributions | 2013

Economic Comparison of Torrefaction-Based and Conventional Pellet Production-to-End-Use Chains

Ehrig R, et al. Economic Comparison of Torrefaction-Based and Conventional Pellet Production-to-End-Use Chains, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 1342-1349.

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Biomass upgrading through torrefaction is expected to relevantly reduce biomass trade costs and thus energy costs for the end-user. In this framework, the present work aims at defining crucial technical and cost parameters for the production, fuel properties, supply and end-use of torrefied pellets. The findings are used to compare four real-case wood pellet with corresponding torrefied pellet supply chains. Input data are derived from laboratory fuel, pelletising and storage experiments with torrefied biomass provided from European producers, cost estimations based on experience from related technology engineering and set-up as well as from expert consultations. This allows a step-by-step comparison of cost advantages and additional expenses from pretreatment to end-user. As a result, torrefied pellets turn out to be a certain alternative for wood pellets. The cost comparison demonstrates that the production of torrefied pellets is still much more cost-intensive, but can be partly compensated by reduced transportation costs. At the end-user, heat production in small-scale pellet boilers is technically feasible, but with slightly higher costs. Co-firing torrefied pellets in large-scale coal plants can be cost-competitive to industrial wood pellets, when no additional retrofit and operation and maintenance costs incur.


Contributions at other events | 2013

Einfluss der thermo-chemischen Vorbehandlung von Biertrebern auf die anaerobe Fermentation

Bochmann, G. Einfluss der thermo-chemischen Vorbehandlung von Biertrebern auf die anaerobe Fermentation, Ph.D. Thesis, Universität für Bodenkultur Wien, Vienna, Austria, 2013.

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Gegenstand der Arbeit ist der thermische und thermo-chemische Aufschluss von Biertrebern. Dabei werden die Prozessbedingungen wie Chemikalien, Konzentration, Aufschlusstemperatur sowie Aufschlussdauer und deren Einfluss auf die Biogasgewinnung untersucht. Der Nachweis erfolgt entlang den einzelnen Prozessstufen Hydrolyse, Acidogenese und Methanogenese. Die Prozessparameter der Aufschlüsse haben sowohl einen starken Einfluss auf die Hydrolyse der Lignozellulose als auch auf die Bildung thermischer Nebenprodukte. Diese Zwischenprodukte beeinflussen unter anderem den Schritt der Acidogenese stark. Wohingegen die Endprodukte, Melanoidine, anaerob kaum abbaubar sind und damit die Biogasausbeute reduzieren. Die höchsten Methanerträge werden mit einer Behandlungstemperatur von 140 °C erreicht. Unterschiedlich sind dabei die Höhe der zusätzlichen Gaserträge von 28 Vol.-% mit H2O sowie rund 50 Vol.-% mit Lauge und 60 Vol.-% mit Säure. In semi-kontinuierlich beschickten Reaktoren konnten mit unbehandelten Trebern Erträge von 410 m³N CH4/Mg oTS realisiert werden. Thermisch aufgeschlossene Treber ergeben Erträge von 468 m³N CH4/Mg oTS (+14 %). Durch die Zugabe von Lauge zum thermischen Aufschluss kann der Methanertrag auf 558 m³N/Mg oTS (+36 %) gesteigert werden. Auf Grund der Prozessinstabilitäten war der acido-thermisch aufgeschlossene Treber nicht auswertbar. Der Mehrertrag in den Aufschlüssen ist auf die verbesserte Verwertung der Zellulose und Hemizellulose zurückzuführen. Durch die Vorbehandlung der Biertreber gelingt es, die Treberverwertung wirtschaftlicher zu gestalten. Nach der Vergütung im Österreichischen Ökostromgesetz 2012 können Erträge von bis 13 €/Mg FM Treber erreicht werden. Dies ist insbesondere durch eine thermo-chemischen Vorbehandlung möglich


Conference contributions | 2013

Emissions from Wood Pellets During Storage Referring to the Extractive Content

Schmutzer-Rosendeder I, Emhofer W, Haslinger W. Emissions from Wood Pellets During Storage Referring to the Extractive Content, Word Sustainable Energy Days next 2013, 27th-28th of February 2013, Wels, Austria.

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Wood pellets and wood raw materials such as chips or sawdust emit hazardous gases such as carbon monoxide (CO) and volatile organic compounds (VOCs) during processing and storage. Due to the high toxicity of CO it is necessary to identify the release mechanisms for CO and VOCs. Several studies show that organic extractives decrease during storage as well as the emissions. Therefore, the purpose of this study was to investigate a possible correlation between the organic extractive content and the release of CO and VOCs. Sawdust and pellets from Norway spruce (Picea abies), European larch (Larix decidua) and loblolly pine (Pinus taeda) were examined. Additionally, five different pellet samples from Austrian pellet producers were investigated. Soxhlet extraction with acetone was used to extract the organic content. The concentration of CO and VOCs was measured from stored wood materials and pellets in sealed glass flasks. The highest (3,41 mg CO/kg sample dm/d) and the lowest (0,02 mg CO/kg sample dm/d) release of CO were reported with freshly produced pine pellets and a spruce pellets sample from an Austrian do-it-yourself store, respectively. The results showed that the pelletizing process reduced the content of organic extractives. The emissions of pine samples concerning CO and VOCs were higher than of the spruce and larch samples. Moreover, the organic extractive content also decreased in that order. However, a direct correlation between organic extractive content and released quantities of emissions could not be established.


Other Presentations | 2013

Energy independent food processing industry -- realization of an innovative waste & energy management concept

Ortner M, Pröll T, Schumergruber A, Fuchs W. Energy independent food processing industry - realization of an innovative waste & energy management concept, Beijing International Environmental Technology Conference 2013, 21st-23rd of October 2013, Beijing, China.

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Conference contributions | 2013

Enhanced flue gas condensation technology: analysis of a 10MW demonstration plant

Hebenstreit B, Höftberger E, Ohnmacht R, Lundgren J, Toffolo A. Enhanced flue gas condensation technology: analysis of a 10MW demonstration plant, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark. p 1614-1617.

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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.  


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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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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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.


Contributions at other events | 2013

Hydrogen Production by Steam Reforming of Hydrocarbons from Biomass Gasification Modeling and Experimental Study

Sadooghi, P. Hydrogen Production by Steam Reforming of Hydrocarbons from Biomass Gasification Modeling and Experimental Study, Ph.D. Thesis, Vienna University of Technology, Vienna, Austria, 2013.

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Contributions to trade journals | 2013

Implementing an advanced waste separation step in an MBT plant: assessment of technical, economic and environmental impacts

Meirhofer M, Piringer G, Rixrath D, Sommer M, Ragossnig AM. Implementing an advanced waste separation step in an MBT plant: Assessment of technical, economic and environmental impacts. Waste Management and Research. 2013;31(10 SUPPL.):35-45.

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Heavy fractions resulting from mechanical treatment stages of mechanical-biological waste treatment plants are posing very specific demands with regard to further treatment (large portions of inert and high-caloric components). Based on the current Austrian legal situation such a waste stream cannot be landfilled and must be thermally treated. The aim of this research was to evaluate if an inert fraction generated from this waste stream with advanced separation technologies, two sensor-based [near-infrared spectroscopy (NIR), X-ray transmission (XRT)] and two mechanical systems (wet and dry) is able to be disposed of. The performance of the treatment options for separation was evaluated by characterizing the resulting product streams with respect to purity and yield. Complementing the technical evaluation of the processing options, an assessment of the economic and global warming effects of the change in waste stream routing was conducted. The separated inert fraction was evaluated with regard to landfilling. The remaining high-caloric product stream was evaluated with regard to thermal utilization. The results show that, in principal, the selected treatment technologies can be used to separate high-caloric from inert components. Limitations were identified with regard to the product qualities achieved, as well as to the economic expedience of the treatment options. One of the sensor-based sorting systems (X-ray) was able to produce the highest amount of disposeable heavy fraction (44.1%), while having the lowest content of organic (2.0% Cbiogenic per kg waste input) components. None of the high-caloric product streams complied with the requirements for solid recovered fuels as defined in the Austrian Ordinance on Waste Incineration. The economic evaluation illustrates the highest specific treatment costs for the XRT (€23.15 per t), followed by the NIR-based sorting system (€15.67 per t), and the lowest costs for the air separation system (€10.79 per t). Within the ecological evaluation it can be shown that the results depend strongly on the higher heating value of the high caloric light fraction and on the content of Cbiogenic of the heavy fraction. Therefore, the XRT system had the best results for the overall GWP [-14 kg carbon dioxide equivalents (CO2eq) per t of input waste] and the NIR-based the worst (193 kg CO2 eq per t of input waste). It is concluded that three of the treatment options would be suitable under the specific conditions considered here. Of these, sensor-based sorting is preferable owing to its flexibility. © The Author(s) 2013.


Conference contributions | 2013

Improvement of real life operation performance of residential wood combustion

Schmidl C, Haslinger W, Aigenbauer S, Figl F, Kirchhof JM, Moser W, Reichert G, Schwabl M, Verma V, Wöhler M. Improvement of real life operation performance of residential wood combustion, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark.

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Contributions to trade journals | 2013

Influence of fuel feeding positions on gasification in dual fluidized bed gasifiers

Wilk V, Schmid JC, Hofbauer H. Influence of fuel feeding positions on gasification in dual fluidized bed gasifiers. Biomass Bioenergy. 2013;54:46-58.

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An in-bed and an on-bed feeding system are implemented in a dual fluidized bed gasifier in order to investigate the influence of the fuel feeding position on the gasification process. Two bed materials, fresh and used olivine, are used because of their varying catalytic activity. The comparison of in-bed and on-bed feeding of wood pellets shows that in-bed feeding is more favorable, because lower tar concentrations are achieved and the gas composition is closer to water-gas shift equilibrium. Better mixing of bed material and fuel particles occurs with in-bed feeding. The residence time of the gas phase in the fluidized bed is longer in the case of in-bed feeding, and therefore better performance of the gasifier is achieved. Sufficient residence time of the fuel in the bubbling bed is important when a less active bed material is used. More active bed material is capable of compensating for the shorter residence time of the gas phase in contact with bed material during on-bed feeding. •Experimental investigation of in-bed and on-bed feeding.•Two bed materials (catalytic activity) and two fuels (devolatilization behavior).•In-bed feeding more favorable due to lower tar concentration and better gas quality.•Residence time of the gas phase in the fluidized bed is longer during in-bed feeding.•More active bed material compensates for shorter residence time of the gas phase. © 2013 Elsevier Ltd.


Contributions to trade journals | 2013

Influence of fuel particle size on gasification in a dual fluidized bed steam gasifier

Wilk V, Hofbauer H. Influence of fuel particle size on gasification in a dual fluidized bed steam gasifier. Fuel Process Technol. 2013;115:139-51.

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The influence of the distribution of fuel particle size on steam gasification was studied systematically in a dual fluidized bed gasifier. Pilot plant gasification experiments have been conducted using sawdust and pellets produced from the same raw material. Three different kinds of waste wood with a broad particle size distribution were also considered for comparison. The fuels differ in their content of particles smaller than 1 mm of equivalent diameter. With an increasing proportion of particles smaller than 1 mm, the product gas contained less H2 and more CO and CH4. Less product gas was generated and the concentration of tar increased. It is observed that entrainment of small fuel particles plays an important role in the dual fluidized bed gasifier. Based on the superficial gas velocity in the freeboard of the gasification reactor, a limiting diameter for the entrainment of fuel particles can be determined. Under the conditions investigated a total of 22 wt.% of fuel particles present in the mixture of sawdust and pellets was entrained very rapidly after feeding because of their size. They mainly devolatilize in the freeboard and only have limited contact with the catalytic bed material. Therefore, these volatiles are less likely to be reformed and more tar is found in the product gas. As a conclusion, the particle size determines the region where the thermal conversion of the fuel particle mainly takes place: within the fluidized bed or in the freeboard. © 2013 Elsevier B.V.
 


Other publication | 2013

Innovative Energietechnologien in Österreich - Marktentwicklung 2013

Biermayr P, Eberl M, Enigl M, Rechner H, Kristöfel C, Leonhartsberger K, Maringer F, Moidl S, Strasser C, Weiss W, Wörgetter M. Innovative Energietechnologien in Österreich – Marktentwicklung. Berichte aus Energie und Umweltforschung. 2013:26.

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Contributions to trade journals | 2013

Investigations of aerosol formation pathways during MSW combustion based on high-temperature impactor measurements

Brunner T, Fluch J, Obernberger I, Warnecke R. Investigations of aerosol formation pathways during MSW combustion based on high-temperature impactor measurements. Fuel Process Technol. 2013;105:154-60.

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In order to gain deeper insights into aerosol formation processes during MSW combustion, test runs with a specially developed high-temperature aerosol measurement and sampling device, the so called high-temperature impactor (HTI), as well as subsequent chemical analyses of the particles sampled have been performed at a real-scale plant. The results show that aerosol formation during MSW combustion is based on the volatilisation of minor amounts of Si-, Ca-, Mg- and Al-compounds followed by nucleation in the fuel bed region which is then followed by excessive condensation of alkaline metal sulphates and especially chlorides in the radiative and the convective boiler sections. At lower flue gas temperatures in the superheater as well as the economiser section also the condensation of heavy metal (Zn, Pb) chlorides provides contributions to aerosol formation. © 2011 Elsevier B.V.


Contributions to trade journals | 2013

Jatropha mahafalensis oil from Madagascar: Properties and suitability as liquid biofuel

Sonnleitner A, Rathbauer J, Randriamalala JR, Raoliarivelo LIB, Andrianarisoa JH, Rabeniala R, et al. Jatropha mahafalensis oil from Madagascar: Properties and suitability as liquid biofuel. Energy for Sustainable Development. 2013;17(4):326-30.

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Access to affordable and renewable sources of energy is crucial to reducing poverty and enhancing rural development in countries of the global South. Straight vegetable oil was recently identified as a possible alternative to conventional biomass for rural energy supply. In this context, the Jatropha curcas Linn. species has been extensively investigated with regard to its potential as a biofuel feedstock. In contrast, only little is known about Jatropha mahafalensis Jum. & H. Perrier, which is an indigenous and endemic representative of the Jatropha genus in Madagascar. This paper explores the potential and suitability of J. mahafalensis as a biofuel feedstock. Seed samples were collected in the area of Soalara in south-western Madagascar in February and September 2011. Two agro-ecological zones (coastal area and calcareous plateau) and two plant age groups (below and above 10. years) were considered. These four sample groups were analyzed with regard to oil properties, element contents, and fatty acid profiles. Measured values differed greatly between the two harvests, probably owing to different climatic or storage conditions. No direct relation between age of trees or location and oil quality could be established. The analyses indicate that J. mahafalensis oil can be used in oil lamps, cooking stoves and stationary combustion engines for electrification or for biodiesel production. However, modifications in storage and extraction methods, as well as further processing steps are necessary to enable its utilization as a straight vegetable oil and feedstock for biodiesel production. If these technical requirements can be met, and if it turns out that J. mahafalensis oil is economically competitive in comparison with firewood, charcoal, paraffin and petroleum, it can be considered as a promising feedstock for rural energy supply. © 2013 International Energy Initiative.


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