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.

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

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.

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.  

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.

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% C_biogenic 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.

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.

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.
 

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.

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.

Operating biomass stoves in modern buildings with tight shells often requires a room-independent air supply. One possibility to arrange this supply is to use a double-wall chimney with fresh air entering through the annular gap. For this setup, a mathematical model has been developed and checked with experimental data. It turned out that for commercially available chimneys, leakage is not negligible and inclusion of leak air in the calculation is crucial for reproduction of the experimental data. Even with inclusion of this effect, discrepancies remain which call for further investigations and a refinement of the model.

The present paper introduces a life cycle modeling approach for representing actual demand of energy or energy intensive products delivered within a system (electricity, heat, etc.) for optimization of the energy mix, according to some of the available life cycle impact assessments (LCIAs). Unlike classical LCA modeling approach, the real amount of several energy products leaving the system and the interactions due to the presence of multi-output processes are considered within the present approach. As a case study, future scenarios are obtained for the Belgian electricity mix production and the heat mix potentially substituted by CHP or biomass, switching between abandoning or not power from nuclear energy. The possibility of using natural gas, biomass for cogeneration, wind power and solar photovoltaic energy are considered within the availability ranges of these resources. Finally, results are presented from successive optimizations according to the sustainability potential defined in a previous paper. A pathway to a more sustainable Belgian energy system is obtained. Finally it is concluded that under the modeling conditions and without nuclear energy it is not possible to obtain a reduction of GHGs and despite diminishing of non-renewable resource consumption, a rising of toxicity is obtained. © 2013 Elsevier Ltd.

Product gas produced by biomass gasification contains small amounts of sulfur compounds (hydrogen sulfide) which can reduce catalyst activity during steam reforming process. Sulfur removal has a negative effect on process efficiency and steam reforming has to be run without cleaning the gas prior to the reactor. It is therefore of interest to investigate the effect of sulfur on the performance of steam reforming reactions. In this work a packed bed reactor filled with nickel based catalysts is mathematically modeled to simulate the steady state pseudo-heterogeneous equations representing heat and mass transfer in the reactor tube. Catalytic bed is subjected to hydrogen sulfide and an isotherm model for the sulfur coverage on the Ni surface is considered to exactly investigate sulfur poisoning effects on methane conversion, hydrogen yield, carbon dioxide and carbon monoxide concentration. It is shown that even when present in the hydrocarbon feedstock in small quantities, (ppm) levels, sulfur can have a significant effect in methane conversion and temperature distribution within the reactor. © 2013 Elsevier B.V.

La combustione di biomassa legnosa con piccoli apparecchi e caldaie è oggi vista con rinnovato interesse per il raggiungimento degli obiettivi comunitari di produzione di energia rinnovabile al 2020. L’aumento dell’utilizzo della biomassa combustibile è di stretto interesse del settore agroforestale, per via del notevole indotto economico che peraltro interessa tutto il territorio nazionale. Tuttavia, la combustione della biomassa è legata ad una serie di problematiche ambientali quali le emissioni in atmosfera di polveri sottili che influenzano direttamente la qualità dell’aria. Si ritiene, quindi, che l’auspicato aumento dell’utilizzo delle biomasse, soprattutto ai fini della produzione di calore (riscaldamento ambienti), sia legata al contenimento delle emissioni al camino. In questo contesto, è quindi importante la corretta misura delle polveri emesse dagli apparecchi di riscaldamento domestico alimentati a biomassa solida, tenendo conto anche della frazione condensabile, come richiesto dalla normativa. Il lavoro mette a confronto due tecniche di misura delle polveri, la tecnica di prelievo a caldo con raffreddamento dei fumi in impinger e la tecnica di diluizione con tunnel. Sono stati selezionati per il confronto due apparecchi di ridotta potenza (< 15 kWt) ed elevata efficienza: una caldaia a pellet ed una stufa a pellet. In condizioni di combustione completa le due tecniche restituiscono fattori di emissione simili. Nella stufa a pellet la misura a freddo è maggiore del 20 – 30 % rispetto alla misura a caldo. La ridotta presenza della frazione condensabile è stata confermata dall’analisi NPOC degli impinger. Sono state misurate le emissioni totali prodotte da un utilizzo reale del dispositivo, comprendendo anche le fasi transitorie di combustione (accensione, riscaldamento a regime e spegnimento), solitamente non considerate nelle misure standard di laboratorio. La fase di accensione produce fino a tre volte le polveri emesse in condizioni stazionarie. L’emissione totale si riduce all’aumentare del tempo di utilizzo del dispositivo, rientrando nell’intervallo delle emissioni delle condizioni stazionarie dopo circa 6 h. Gli IPA, emessi in quantità elevate, sono costituiti maggiormente da congeneri a peso molecolare medio – basso, associati a minore tossicità. Il TEQ è funzione della potenza e delle condizioni di
combustione del dispositivo.

Die Verbrennung fester Biomasse gewinnt als nachhaltige Form der Energieerzeugung stetig an Bedeutung. Eine mögliche Technologie stellen dabei Biomasse-Thermoölkesselanlagen dar, deren Regelungen bis jetzt noch nicht auf einem mathematischen Modell basieren und dementsprechend deren verkoppeltes und zum Teil nichtlineares Verhalten nur ungenügend berücksichtigen. Ziel dieser Arbeit ist es, ein für Biomassefeuerungsanlagen mit Wasserkesseln existierendes Modell sowie die darauf aufbauende Regelungsstrategie an die speziellen Gegebenheiten von Thermoölkesselanlagen anzupassen. Dazu wird zunächst ein einfaches Modell für Thermoölwärmeübertrager auf Basis einer Energiebilanz hergeleitet und anhand von verfügbaren Betriebsdaten qualitativ verifiziert. Anschließend wird die bei der Regelung von Wasserkesselanlagen eingesetzte Eingangs-Ausgangslinearisierung verallgemeinert. Darauf aufbauend wird eine Regelungsstrategie zur Regelung des Thermoölwärmeübertragers hergeleitet. Die Leistungsfähigkeit des Regelungskonzeptes wird schließlich in Simulationsstudien gezeigt. 

 Im Bereich der thermischen Biomassenutzung (speziell Rostfeuerungen) werden CFD-Simulationen eingesetzt, um Hilfestellung bei der Diagnose und Lösung von Betriebsproblemen zu leisten sowie bei der Entwicklung von neuen Feuerungen und Kesseln zu unterstützen. Zurzeit sind keine Modelle verfügbar, mit denen sowohl die Vorgänge im Brennstoffbett als auch in der Gasphase einer Biomasse-Rostfeuerung mit Hilfe von detaillierten numerischen Modellen bei akzeptabler Berechungszeit simuliert werden können. Um die direkte Kopplung des Bett-Modells mit der Gasphase zu bewerkstelligen, ist es nötig, ein geeignetes Partikel-Modell zu entwickeln, welches die thermische Konversion (Trocknung, Pyrolyse und Holzkohle-Ausbrand) von thermisch dicken Biomassepartikeln beschreibt und mit bereits vorhandenen CFD-Modellen für die Gasphasensimulation gekoppelt werden kann. In diesem Schalenmodell werden die einzelnen Biomassepartikel als thermisch dick behandelt, d.h. die Temperaturgradienten in den einzelnen Partikeln sowie der gleichzeitige Ablauf mehrerer Umwandlungsprozesse berücksichtigt. Das Schalenmodell wurde mit Hilfe von gemessenen Partikeloberflächen- und -zentrumstemperaturen sowie mit Messwerten des Gesamtmasseverlustes während der Verbrennung in einem Einzel-Partikelreaktor validiert. Ein weiteres Problem, das bei der Simulation von Biomasse-Rostfeuerungen auftritt, ist die Modellierung der Gas-Festkörper-Mehrphasenströmung. Das Modell muss dabei in der Lage sein, den Einfluss der Partikel-Partikel-Wechselwirkung währenden der Partikelbewegung am Rost korrekt zu beschreiben. Aus diesem Grund wurde durch Kopplung von Euler- und Lagrange Mehrphasenströmungs- Ansätzen ein neues, dreidimensionales Schüttungsmodell entwickelt. Dabei wird die Partikelbewegung am Rost mit Hilfe eines Euler-Ansatzes (Euler-Granular-Modell) beschrieben, während die thermische Umwandlung der Biomassepartikel mit Hilfe eines Lagrange-Ansatzes und dem entwickelten Einzelpartikelmodell beschrieben wird. Das 3D-Festbettmodell für Biomasserostfeuerungen wurde eingesetzt, um eine 20 kW Biomasse-Unterschubfeuerung zu simulieren. Da es keine experimentelle Daten hinsichtlich der Bedingungen im Brennstoffbett gab, wurden qualitative Informationen hinsichtlich der Positionen der Trocknungs-, Pyrolyse- und Holzkohle-Ausbrandzonen, sowie mit Thermoelementen gemessenen Rauchgastemperaturen an verschiedenen Positionen in der Brennkammer zum Vergleich mit den Simulationsergebnissen herangezogen. Des Weiteren erfolgte im Zuge dieser Arbeit eine Weiterentwicklung des Festbett-Modells, indem der Strahlungsaustausch zwischen den Partikeln sowie detaillierte kinetische Modelle für die Gasphasenverbrennung im Modell implementiert wurden. Das weiterentwickelte Modell wurde mit Hilfe von experimentellen Daten aus Testläufen in einem Festbett-Laborreaktor validiert. Diese Messdaten beinhalten gemessene Konzentrationen von CO, CO2, CH4, H2, H2O und O2 im Rauchgas über dem Brennstoffbett sowie Temperaturen in unterschiedlichen Positionen im Bett und über dem Bett. Die vorhergesagten Werte zeigten eine gute Übereinstimmung mit den gemessenen Werten.

Für den ökonomisch und ökologisch effizienteren Betrieb von Dampfkesselanlagen ist die Untersuchung von Korrosionsvorgängen in Wärmetauschern, verursacht durch das Rauchgas aus einer Biomasse-Feuerung, notwendig. Daher wurden bei Bioenergy 2020+ kurzzeitige Korrosionsversuche im Umfang von 300h Betriebszeit an einem Wärmetauscherstahl 13CrMo4-5 mit einer ONLINE-Korrosionssonde der Firma Corrmoran GmbH für die Erstellung eines empirischen Korrosionsmodells durchgeführt. Als Brennstoffe dienten Waldhackgut, Weizenstrohpellets und Altholz. Die Messung benötigt eine Ionen leitende Deckschicht, die sich erst am Beginn des Versuchs aufbaut. Aufgrund der fehlenden Deckschicht wird daher zu Beginn der Messung der Korrosionsleitwert unterschätzt. Daraus ergeben sich systematische Messfehler. Ziel dieser Arbeit war die Eruierung des Zusammenhanges zwischen Messfehler und Versuchszeit. Dabei stellten sich zwei systematische Messfehler als relevant heraus: •Die Abzehrrate ist zum Korrosionsleitwert proportional. Daher wird die Abzehrrate während der Eingangsphase der Messung unterschätzt. •Die Abzehrrate berechnet sich aus dem Korrosionsleitwert, multipliziert mit einem Kalibrierungsfaktor. Dabei ergibt sich der Kalibrierungsfaktor aus dem Verhältnis des gesamten korrosionsbedingten Materialverlustes über die gesamte Versuchsdauer, dividiert durch den über denselben Zeitraum integrierten Korrosionsleitwert. Aufgrund des zu Beginn unterschätzten Korrosionsleitwertes wird der Kalibrierungsfaktor und somit die Abzehrrate, berechnet aus dem reproduzierbaren Signal, überschätzt. Die Literaturrecherche zeigte, dass die Kinetik bei der Hochtemperaturkorrosion bei konstant gehaltenen korrosionsrelevanten Parametern einen linearen, parabolischen oder paralinearen Verlauf einnehmen kann. Die kleinstmögliche Abzehrrate und somit der kleinstmögliche Korrosionsleitwert zu Beginn der Messung ergibt sich bei der Annahme eines linearen Verlaufs, welcher die möglicherweise erhöhten Abzehrraten der Initialkorrosion nicht mitberücksichtigt. Aus dieser Annahme konnte der kleinstmögliche Korrekturfaktor cmin berechnet werden. Dazu mussten die Daten bei konstant gehaltenen Parametern gefiltert und daraus der zeitlich integrierte Korrosionsleitwert PL,Messung gebildet werden. Das Verhältnis von PL,Messung mit einem über die gesamte Versuchszeit konstant angenommenen zeitlich integrierten Korrosionsleitwertes PL,linear ergibt den Korrekturfaktor, der multipliziert mit den ursprünglich bei gleichen Parametern bestimmten Abzehrraten eine neue Abzehrrate k(t)neu ergibt. Der Vergleich mit den Ergebnissen eines Langzeitversuches unter ähnlichen Betriebsbedingungen in einem Biomasse-Heizkraftwerk zeigte dadurch eine Verbesserung der Abweichung der Kurzzeitversuche von 125% auf 55%. Aufgrund der Parametervariationen sowie der Temperaturschwankungen, verursacht durch Ein- und Ausschaltvorgänge der Anlage, haben die bei konstanten Parametern bestimmten Korrekturfaktoren für die durchgeführten Versuche nur bedingt Gültigkeit. Daher wurde in einem weiteren Schritt ein Korrekturfaktor cmin,var bestimmt, welcher alle Daten der Versuchsserie berücksichtigt. Dazu wurde das Signal der Eingangsphase durch ein gleichlanges reproduzierbares Signal, gemessen unter denselben Bedingungen am Ende der Versuchsserien, ersetzt. Es ergibt sich aus dem Verhältnis der zeitlich integrierten Korrosionsleitwerte PL,Messung der Originalkurve zu PL,idealisiert des idealisierten Verlaufs der Korrekturfaktor cmin,var. Dieser hat aufgrund der Berücksichtigung aller gesammelten Daten für alle bei den Versuchen bestimmten Abzehrraten Gültigkeit. Durch cmin,var konnte eine Reduktion der Abweichung auf 110% erreicht werden. Diese wird auf die im Gegensatz zur Langzeitmessung im Biomasse-Heizkraftwerk unterschiedliche Versuchsmethode sowie auf den unbekannten Einfluss der möglicherweise erhöhten Abzehrraten der Initialkorrosion zurückgeführt.  

The use of biomass in manually charged room heating appliances to cover the domestic heating demand has traditionally been of a high percentage in the European Union. As a result of continued or even increased use of firewood stoves, the enhancement of available stoves is a declared objective of the European Union.
Therefore, an example-optimization of the firewood stove Stûv 16/78-in (available on the European market) was performed in preparation of this paper. There was a primary- and a secondary optimization carried out to quantify the potential of optimization. When optimizing, the gas and particulate emissions was considered. The operating behavior were measured and evaluated by performing combustion experiments on a specially designed test rig.
The primary optimization is divided into five sub-steps. Each Step was quantified by gas analysis. The achieved reduction of particulate emissions was measured before and after the entire primary optimization.
In comparison to the delivery condition it was possible to reduce the CO emissions to one quarter and the particulate emissions from 100 mg / mn³ to 39 mg / mn³ over the course of the primary optimization.
As a secondary optimization, a Catalyst was implemented. The used catalyst is a solid-state catalyst in the modification of a heterogeneous supported catalyst in the shape of honeycomb, which is marketed by Clariant International Ltd. under the name "EnviCat ® Longlife Plus". The catalytically active materials platinum and palladium are used.
After a strictly implemented primary optimizations, a further reduction to half of emissions was achieved by the integration of the catalyst even though a bypass of 20 % had to be integrated to ensure the operating safety.

To meet the aims of the worldwide effort to reduce greenhouse gas emissions, product gas from biomass steam gasification in DFB (dual fluidized bed) gasification plants can play an important role for the production of electricity, fuel for transportation and chemicals. Using a catalytically active bed material, such as olivine, brings advantages concerning tar reduction in the product gas. Experience from industrial scale gasification plants showed that a modification of the olivine occurs during operation due to the interaction of the bed material with ash components from the biomass and additives. This interaction leads to a calcium-rich layer on the bed material particles which influences the gasification properties and reduces tar concentration in the product gas. In this paper, the influence on the gasification performance, product gas composition and tar formation of a reduction of the gasification temperature are studied. A variation of the gasification temperature from 870 °C to 750 °C was carried out in a 100 kW pilot plant. A reduction of the gasification temperature down to 750 °C reduces the concentration of hydrogen and carbon monoxide in the product gas and increases the concentration of carbon dioxide and methane. The product gas volume produced per kg of fuel is reduced at lower gasification temperatures but the calorific value of the product gas increases. The volumetric concentration of tars in the product gas increases slightly until 800 °C and nearly doubles when decreasing the gasification temperature to 750 °C. The tars detected by gas chromatography-mass spectrometry (GCMS) were classified into substance groups and related to the fuel input to the gasifier and showed a decrease in naphthalenes and polycyclic aromatic hydrocarbons (PAHs) and an increase in phenols, aromatic compounds and furans when reducing the gasification temperature. The comparison with results from an earlier study, where the gasification properties of unused fresh olivine were compared with used olivine, underlines the importance of a long retention time of the bed material in the gasifier, ensuring the formation of a calcium-rich layer in the bed material. © 2012 Elsevier Ltd. All rights reserved.

The increasing demand for woody biomass increases the price of this limited resource, motivating the growing interest in using woody materials of lower quality as well as non-woody biomass fuels for heat production in Europe. The challenges in using non-woody biomass as fuels are related to the variability of the chemical composition and in certain fuel properties that may induce problems during combustion. The objective of this work has been to evaluate the technical and environmental performance of a 15. kW pellet boiler when operated with different pelletized biomass fuels, namely straw (Triticum aestivum), Miscanthus (Miscanthus× giganteus), maize (Zea mays), wheat bran, vineyard pruning (from Vitis vinifera), hay, Sorghum (Sorghum bicolor) and wood (from Picea abies) with 5% rye flour. The gaseous and dust emissions as well as the boiler efficiency were investigated and compared with the legal requirements defined in the FprEN 303-5 (final draft of the European standard 303-5). It was found that the boiler control should be improved to better adapt the combustion conditions to the different properties of the agricultural fuels. Additionally, there is a need for a frequent cleaning of the heat exchangers in boilers operated with agricultural fuels to avoid efficiency drops after short term operation. All the agricultural fuels satisfied the legal requirements defined in the FprEN 303-5, with the exception of dust emissions during combustion of straw and Sorghum. Miscanthus and vineyard pruning were the best fuels tested showing comparable emission values to wood combustion. © 2012 Elsevier Ltd.

A mathematical model is developed to simulate synthesis gas production by methane steam reforming process in a fixed bed reactor filled with catalyst particles. Due to the endothermic nature of the reforming reactions heat is supplied into the reactor by means of electrical heating, therefore, the reactor and catalyst particles are exposed to significant axial and radial temperature gradients. A pseudo heterogeneous model is used in order to exactly represent diffusion phenomena inside the reactor tube. Heat and mass transfer equations are coupled with detailed reaction mechanisms and solved for both the flow phase and within the catalyst pellets. The reaction has been investigated from a modeling view point considering the effect of different temperatures ranging from 873 to 1073 (K) on methane conversion and hydrogen yields. The result provides temperature and concentration distribution along the reactor axial and radial coordinates and strong radial temperature gradients particularly close to the entrance of the reactor have been found. © 2013 Elsevier B.V.

Current levels of ambient air fine particulate matter (PM_2.5) are associated with mortality and morbidity in urban populations worldwide. In residential areas wood combustion is one of the main sources of PM_2.5 emissions, especially during wintertime. However, the adverse health effects of particulate emissions from the modern heating appliances and fuels are poorly known. In this study, health related toxicological properties of PM₁ emissions from five modern and two old technology appliances were examined. The PM₁ samples were collected by using a Dekati® Gravimetric Impactor (DGI). The collected samples were weighed and extracted with methanol for chemical and toxicological analyses. Healthy C57BL/6J mice were intratracheally exposed to a single dose of 1, 3, 10 or 15mg/kg of the particulate samples for 4, 18 or 24h. Thereafter, the lungs were lavaged and bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation, cytotoxicity and genotoxicity. Lungs of 24h exposed mice were collected for inspection of pulmonary tissue damage. There were substantial differences in the combustion qualities of old and modern technology appliances. Modern technology appliances had the lowest PM₁ (mg/MJ) emissions, but they induced the highest inflammatory, cytotoxic and genotoxic activities. In contrast, old technology appliances had clearly the highest PM₁ (mg/MJ) emissions, but their effect in the mouse lungs were the lowest. Increased inflammatory activity was associated with ash related components of the emissions, whereas high PAH concentrations were correlating with the smallest detected responses, possibly due to their immunosuppressive effect. © 2012 Elsevier B.V.

Most of the current pyrolysis/torrefaction mechanisms are not able to predict the composition of pyrolysis/torrefaction products. They usually lump the products as permanent gases, liquids (condensable species) and solid residuals. However, the composition of the emitted species is required to predict the calorific value of the torrgas and to model the possible subsequent gas phase reactions and the temperature distribution within the reactor. Therefore, in this work a mechanism from literature is applied for the first time to predict the composition of the torrgas as a combination of twenty typical species. Several experimental data sets from literature are used to evaluate the mechanism. Since the mechanism predicts several relevant species (>1% wt.) in the torrgas for which no experimental data in the literature are available, test runs at a lab-scale packed bed reactor have been performed to achieve more detailed data of torrgas composition for model validation. Among the species for which measured data are available, carbon monoxide and methanol are well predicted. The predictions of carbon dioxide, methane, formaldehyde, acetaldehyde and ethanol are qualitatively correct. The predictions of water vapour, acetic acid, propanal, ethylene and sugar components show deviations. However, yields of solid residual and total emitted gas and tar are well predicted by the mechanism.

In order to enlarge the range of feedstock for the dual fluidized bed (DFB) gasification process, the influence of several fuel properties was studied in the 100 kW DFB pilot plant. Fuels with high concentration of nitrogen and sulfur, fuels with an increased concentration of fine particles, and fuels with extremely high content of volatiles were tested. The DFB gasification system is found to be robust and can handle all the materials. Nitrogen, sulfur and chlorine from the fuel are predominantly converted in the gasification reactor, either to gases (nitrogen, sulfur) or bound to ash (chlorine, sulfur). For the performance of the DFB gasifier, sufficient contact of fuel, product gas and bed material is important. Increasing amounts of fine particles or volatiles in the fuels lead to higher tar loads in the product gas, because the residence time of fuel particles in bubbling fluidized bed is shorter.

Biogas substrates are typically moist, which can make them difficult to store because bacteria and mould can grow on them. Ensiling, which involves the production of acid by lactic acid bacteria, is often used to preserve crops cheaply. Biogas substrates are also often fibrous, which can make them difficult to mix and means that some of their energy is locked up within the fibres. Different pre-treatment technologies are being investigated to access the energy in these fibres, to increase the rate of biogas production and to improve the mixing qualities of the substrates. Pre-treatment technologies are based on three principles: physical (including mechanical shear, heat, pressure and electric fields), chemical (acids, bases and solvents) and biological (microbial and enzymatic). Combinations of these principles are also used, including steam explosion, extrusion and thermo-chemical processes. Although many of these processes have been investigated at small scale, few have been analysed at large scale in un-biased studies. Many of these techniques are associated with high energy input (e.g. mechanical and heat pre-treatment), high equipment costs (e.g. mechanical systems where the blades erode) or use large volumes of chemicals (e.g. alkali pre-treatment). Different pre-treatment technologies work better with different substrates, and more research is required in this field to understand which combinations are worthwhile. This chapter describes some of the common pre-treatment technologies along with some advantages and disadvantages.

The bed material and especially its catalytic activity plays an important role in biomass steam gasification in dual fluidized bed gasifiers. The bed material is modified by interaction with biomass ash during operation of the gasification plant forming layers at the particles which are induced by the biomass ash. Optimization of dual fluidized biomass steam gasification will have significant influence on the process variables such as temperatures, inorganic composition and product gas composition. The influence of these changes on layer formation is still unknown. This paper summarizes results of investigations about bed material characteristics taken from the industrial-scale biomass steam gasification plant in Güssing where woody biomass is used as fuel. Analyses of the surface and the crystal structures of the bed material particles treated in gasification and combustion atmospheres were carried out. The thermal behavior of used olivine and fresh olivine in different atmospheres was analyzed. A suggestion for the mechanism of formation of the layers is presented and the influence of possible optimization measures is discussed. A change in the elemental composition of the surface was not detectable but a slight change in the crystal structure. Thermal investigations show a weak endothermic weight loss with used olivine in a CO₂-rich atmosphere which could not be determined with fresh olivine. The formation of layers at the olivine particles is considered to be caused by the intensive contact with burning char particles in the combustion reactor. © 2013 Elsevier B.V.

A one-dimensional model for the thermal conversion of thermally thick biomass particles is developed for the simulation of the fuel bed of biomass grate furnaces. The model can be applied for cylindrical and spherical particles. The particle is divided into four layers corresponding to the main stages of biomass thermal conversion. The energy and mass conservation equations are solved for each layer. The reactions are assigned to the boundaries. The model can predict the intra-particle temperature gradient, the particle mass loss rate as well as the time-dependent variations of particle size and density, as the most essential features of particle thermal conversion. When simulating the fuel bed of a biomass grate furnace, the particle model has to be numerically efficient. By reducing the number of variables and considering the lowest possible number of grid points inside the particle, a reasonable calculation time of less than 1 min for each particle is achieved. Comparisons between the results predicted by the model and by the measurements have been performed for different particle sizes, shapes and moisture contents during the pyrolysis and combustion in a single-particle reactor. The results of the model are in good agreement with experimental data which implies that the simplifications do not impair the model accuracy.

This thesis focuses on portraying the thermal behavior of a biomass pellet boiler through measurement and simulation. During operation the power of a pellet boiler changes depending on the heat demand. Detailed measurements were conducted to record this changing behavior of some boilers and estimate their levels of efficiencies. Subsequently a mathematical model was created to emulate boilers and their thermal performance without such measurements. The first part of this thesis deals with the description of the simulation model and the measurements which were carried out. Secondly, the verification of the model is discussed. For this verification simulation results of three different boilers are compared to measurement data and pictured in various diagrams. The last part of this thesis is about further simulations of these three boilers where the control units were emulated too. The model was built in the MATLAB/Simulink® environment and is generally based on
thermodynamic relationships and heat balances in a boiler. However, through constant comparison of the simulation results with the measurement data some parameters were adapted to fit the simulation to reality. Therefore this model is “semi-empirical” as physical correlations are included but some parameters were deduced from measurement. Following, the verification of the model is discussed through the comparison of measurement data and simulation results. For the verifications the boiler power, fuel mass flow as well as
the heat consumption were taken from the measurement data and set as input for the simulation. The calculated results show that the boiler model enables to portray the thermal behavior of the three boilers tested with only small divergences. At the end of this thesis it was attempted to model the control unit of the three boilers by analyzing the measurement data. Having a model for the control unit, the inputs from the measurement data are reduced to just two variables, the water inlet temperature and the water volume flow (heat consumption). The comparison of the calculated values to the measurement data shows slightly higher divergences than during the validation, especially where the simulated control unit does not behave like the real one. Through the simulation of further boilers the model could be continuously enhanced. In the future this “virtual boiler” should be used to test control algorithms of boiler control units to enhance their efficiencies.

To examine relevant combustion characteristics of biomass fuels in grate combustion systems, a specially designed lab-scale reactor was developed. On the basis of tests performed with this reactor, information regarding the biomass decomposition behavior, the release of NO_x precursor species, the release of ash-forming elements, and first indications concerning ash melting can be evaluated. Within the scope of several projects, the lab-scale reactor system as well as the subsequent evaluation routines have been optimized and tests with a considerable number of different biomass fuels have been performed. These tests comprised a wide variation of different fuels, including conventional wood fuels (beech, spruce, and softwood pellets), bark, wood from short rotation coppice (SRC) (poplar and willow), waste wood, torrefied softwood, agricultural biomass (straw, Miscanthus, maize cobs, and grass pellets), and peat and sewage sludge. The results from the lab-scale reactor tests show that the thermal decomposition behavior and the combustion behavior of different biomass fuels vary considerably. With regard to NO_x precursors (NH₃, HCN, NO, N₂O, and NO₂), NH₃ and, for chemically untreated wood fuels, also HCN represent the dominant nitrogen species. The conversion rate from N in the fuel to N in NO_x precursors varies between 20 and 95% depending upon the fuel and generally decreases with an increasing N content of the fuel. These results gained from the lab-scale reactor tests can be used to derive NO_x precursor release models for subsequent computational fluid dynamics (CFD) NOx post-processing. The release of ash-forming vapors also considerably depends upon the fuel used. In general, more than 91% of Cl, more than 71% of S, 1–51% of K, and 1–50% of Na are released to the gas phase. From these data, the potential for aerosol emissions can be estimated, which varies between 18 mg/Nm³ (softwood pellets) and 320 mg/Nm³ (straw) (dry flue gas at 13% O2). Moreover, these results also provide first indications regarding the deposit formation risks associated with a certain biomass fuel. In addition, a good correlation between visually determined ash sintering tendencies and the sintering temperatures of the different fuels (according to ÖNORM CEN/TS 15370-1) could be observed.

Der Einfluss von Nährstoffzusammensetzung und Additivzugabe beim anaeroben Abbau organischer Substanz stieß in den letzten Jahren vermehrt auf Interesse. Im Besonderen Spurenelemente haben erwiesenermaßen erheblichen Einfluss auf u.a. methanogene Archaeen und deren metabolische Aktivität. Massive Probleme der Prozessstabilität speziell bei Monovergärung unterschiedlichster Substrate können durch Co-Fermentation oder gezielte Zudosierung von Spurenelementmischungen überwunden werden. Ein profundes Verständnis der Wirkung dieser Elemente auf die verschiedenen mikrobiellen Spezies im Biogasreaktor als auch ihre Verfügbarkeit, ist die Voraussetzung für eine wirtschaftliche Gestaltung des anaeroben Fermentationsprozesses organischer Roh- als auch Reststoffe. Der heutige Stand-der-Technik zur Analyse von Biogasproben hat seinen Ursprung in der Wasser-, Abwasser- und Schlammanalytik und besteht aus einem einzelnen Filtrationsschritt vor Elementdetektion mittels ICP-OES bzw. ICP-MS. Diese Methodik erlaubt nur einen äußerst begrenzten Einblick in die Verteilung von essentiellen Spurenelementen in Anaerobreaktoren. Eine aussagekräftige Beurteilung der mikrobiellen Verfügbarkeit von beispielsweise Cobalt, Nickel oder Molybdän ist somit nur eingeschränkt möglich. Ziel dieser Arbeit war es, eine bestehende Methode zur sequentiellen Extraktion aus dem Bereich der Boden- und Sedimentanalytik für die Anwendung auf Biogasproben zu adaptieren. Der daraus resultierende Einblick in die Verteilung von Spurenelementen in den einzelnen Fraktionen erlaubt eine genauere Bewertung der mikrobiellen Verfügbarkeit von Nährstoffen in Biogasreaktoren, verglichen mit bestehenden analytischen Untersuchungsmethoden. Anforderungen an das Verfahren wie die Reproduzierbarkeit der Daten, zeitsparende Analytik und wirtschaftliche Realisierbarkeit konnten erfüllt werden. Wiederfindungsraten zwischen 90 und 110 % wurden für die wichtigsten Spurenelemente erreicht. Durch die sequentielle Extraktion konnte gezeigt werden, dass essenzielle Mikro-Nährstoffe bis zu 98 % in einer unlöslichen Form vorliegen können. Die Ergebnisse dieser Arbeit belegen die Anwendbarkeit der entwickelten Methodik zur Spurenelement-Extraktion in Anaerob-Systemen.

To systematically investigate high-temperature corrosion of superheaters in biomass combined heat and power (CHP) plants, a long-term test run (5 months) with online corrosion probes was performed in an Austrian CHP plant (28 MW_NCV; steam parameters: 32 t/h at 480 °C and 63 bar) firing chemically untreated wood chips. Two corrosion probes were applied in parallel in the radiative section of the boiler at average flue gas temperatures of 880 and 780 °C using the steel 13CrMo4-5 for the measurements. Corrosion rates were determined for surface temperatures between 400 and 560 °C. The results show generally moderate corrosion rates and a clear dependence upon the flue gas temperatures and the surface temperatures of the corrosion probes, but no influence of the flue gas velocity has been observed. The data are to be used to create corrosion diagrams to determine maximum steam temperatures for superheaters in future plants, which are justifiable regarding the corrosion rate. Dedicated measurements were performed at the plant during the long-term corrosion probe test run to gain insight into the chemical environment of the corrosion probes. From fuel analyses, the molar 2S/Cl ratio was calculated with an average of 6.0, which indicates a low risk for high-temperature corrosion. Chemical analyses of aerosols sampled at the positions of the corrosion probes showed that no chlorine is present in condensed form at the positions investigated. Deposit probe measurements performed at the same positions and analyses of the deposits also showed only small amounts of chlorine in the deposits, mainly found at the leeward position of the probes. Subsequent to the test run, the corrosion probes have been investigated by means of scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses. The results confirmed the deposit probe measurements and showed only minor Cl concentrations in the deposits and no Cl at the corrosion front. Because, in the case of Cl-catalyzed active oxidation, a layer of Cl is known to be found at the corrosion front, this mechanism is assumed to be not of relevance in the case at hand. Instead, elevated S concentrations were detected at the corrosion front, but the corrosion mechanism has not yet been clarified.

Der vorliegende Beitrag analysiert die historische Entwicklung der Bioenergienutzung sowie deren aktuellen Stellenwert in der Energieversorgung Österreichs. In weiterer Folge werden auf Basis von Prognosen die zukünftige Entwicklung der Bioenergienutzung in Österreich sowie die damit einhergehenden Herausforderungen umrissen. Aktuelle Leuchtturmprojekte im Bioenergiesektor und Aspekte aus der österreichischen Bioenergieforschung ergänzen den Beitrag.

Management of municipal and commercial waste in Austria frequently involves mechanical-biological treatment (MBT) followed by incineration. A middle-caloric MBT output stream (lower heating value (LHV) = 9.90 MJ/kg WW, particle size = 20-80 mm) with a high proportion of inert material like stones, bricks, and metals (40.5 %m) is currently incinerated. Under favorable market conditions, it could be economically advantageous to split off a low-caloric heavy fraction (HF) that can be landfilled and to incinerate only the remaining, lighter fraction (LF) with a higher heating value. This study analyzes the specific global-warming potential (100-year GWP per tonne of input waste) of such an additional separation step and of the subsequent treatment processes. Four treatment alternatives were considered: a reference scenario without separation and three separation scenarios – a near-infrared (NIR) sensor-based scenario, an X-ray-transmission (XRT) sensor-based scenario, and a mechanical separation scenario using a diagonal sifter (DS). To calculate the specific GWP, the analysis applied techniques from life-cycle assessment (LCA). Primary data were obtained from pilot-scale and full-scale separation experiments, and from equipment manufacturers. Commercial databases provided secondary data. The results consist of separate LCA models for each scenario, including credits for fossil fuels replaced by LF incineration and HF landfill gas utilization. When only direct separation-related emissions are considered, the DS separation has by far the lowest specific GWP, followed by NIR-based separation, and by XRT-based separation. Overall specific GWP is strongly influenced by the choice of separation technology. It is lowest for the XRT scenario, followed closely by the reference scenario, while the DS and NIR scenarios show considerably higher results. Results are dominated by the net emissions from LF incineration. While incineration emissions are largely compensated by credits from replaced fossil fuels, credits for landfill gas utilization are much smaller than direct landfilling emissions. The ranking of the separation scenarios is largely determined by three waste stream characteristics: the ratio of biogenic to fossil carbon content and the LHV in the LF, and the degradable biogenic carbon content in the HF. Changes in important modeling assumptions leave the ranking between scenarios unchanged. It can be concluded that – given the right choice of
separation technology – a small positive effect of sorting on the overall specific GWP is feasible. This
work demonstrates that global warming effects of waste treatment decisions can be estimated and
considered early in the planning stage of treatment system design.

This publication deals with the characterisation of Jatropha curcas seeds and the oil obtained hereof. The analyzed seeds have been harvested from hedges and plantations in the regions of Teriya Bugu and Bla in Mali in the years 2009 and 2010. The oil is obtained through solvent extraction. Parameters analyzed are those which are relevant for processing of the oil into fatty acid methyl ester (FAME, biodiesel), and include acid value, fatty acid profile and contents of S, P, K, Na, Ca and Mg. All oil samples are suitable for processing into biodiesel, but some of them require pre-treatment because of high contents of free fatty acids and phosphorous. The margin of deviation of acid value and element contents throughout the oil samples depends on the way of cultivation, harvest and storage of the Jatropha curcas plants and seeds. Despite high acid values, all oil samples show high oxidation stability. © 2012 Elsevier Ltd.

Der vorliegende Beitrag analysiert die Auswirkungen unterschiedlicher Brennstoffversorgungsszenarios im Calcinator des Zementherstellungsprozesses auf die emittierten CO2-Emissionen. In weiterer Folge werden die Grenzvermeidungskosten für CO2 im Vergleich zum Referenzszenario (100 % PetCoke) berechnet und dargestellt. Als alternative Brennstoffe werden auf Basis von Betriebserfahrungen sowie großtechnischer Versuche die alternativen Brennstoffe hochkalorischer Fluff (Standardszenario) sowie Schilf (Szenario A) und biogen angereicherter Ersatzbrennstoff (Szenario B) und vergleichend dazu in einer Literaturbasierten Analyse getrockneter Klärschlamm (Szenario C) betrachtet. Um die Auswirkung sich ändernder Marktbedingungen auf die Grenzvermeidungskosten abzubilden erfolgt eine Sensitivitätsanalyse hinsichtlich der Brennstoffgestehungskosten für die alternativen Brennstoffe sowie drei unterschiedliche Preisniveaus für Emissionsrechte und Brennstoffgestehungskosten des Referenzbrennstoffes PetCoke.

The aim of the current study was to investigate the feasibility of membrane contactors for continuous ammonia (NH₃-N) removal in an anaerobic digestion process and to counteract ammonia inhibition. Two laboratory anaerobic digesters were fed slaughterhouse wastes with ammonium (NH₄⁺) concentrations ranging from 6 to 7.4 g/L. One reactor was used as reference reactor without any ammonia removal. In the second reactor, a hollow fiber membrane contactor module was used for continuous ammonia removal. The hollow fiber membranes were directly submerged into the digestate of the anaerobic reactor. Sulfuric acid was circulated in the lumen as an adsorbent solution. Using this set up, the NH₄⁺-N concentration in the membrane reactor was significantly reduced. Moreover the extraction of ammonia lowered the pH by 0.2 units. In combination that led to a lowering of the free NH₃-N concentration by about 70%. Ammonia inhibition in the reference reactor was observed when the concentration exceeded 6 g/L NH₄⁺-N or 1-1.2 g/L NH₃-N. In contrast, in the membrane reactor the volatile fatty acid concentration, an indicator for process stability, was much lower and a higher gas yield and better degradation was observed. The chosen approach offers an appealing technology to remove ammonia directly from media having high concentrations of solids and it can help to improve process efficiency in anaerobic digestion of ammonia rich substrates. © 2012 Elsevier Ltd.

In this study the economic boundary conditions for successful active condensation systems are evaluated.
The concept of active condensation utilizes the flue gas enthalpy exiting the boiler by combining a quench for flue gas condensation and a heat pump. Through the heat pump the flue gas can be cooled down below the dew point of the water vapor. Therefore, the sensible heat as well as the latent heat of water can be recovered. This study evaluates the economic viability  for  different  test  cases.  On  the  one  hand  pellet  boilers  of  small  (10kW)  and  medium  (100kW)  size  are considered. On the other hand wood chip boilers of medium (100kW) and big (10MW) size are studied. The economic analysis shows a decrease in operating costs between 2% and 13%. The payback time is evaluated on a net present value (NPV) method, showing a payback time of 2-10 years for the large scale system and approx. 10-35 years for the medium sized ones.

A one-dimensional single particle model is utilised to investigate the effects of radiation temperature, moisture content, particle size and biomass physical properties on the heating rate in biomass particles during pyrolysis. The model divides the particle into four layers - drying, pyrolysis, char and ash layer - corresponding to the four main stages of biomass thermal conversion. The average of the time derivative of the pyrolysis layer centre temperature weighted by the pyrolysis rate is introduced as an appropriate indicator for the heating rate in the particle during pyrolysis. The influencing parameters on the heating rate are summarised in the Biot number and the thermal time constant, to make the investigation of their effects easier. The heating rate is inversely proportional to the thermal time constant. The effect of a variation of the Biot number on the heating rate is negligible in comparison to the thermal time constant. Therefore, the thermal time constant can be sufficiently used to specify the heating rate regimes during pyrolysis. It is found that for thermal time constants of more than 50 s, pyrolysis takes place in a low heating rate regime, i.e. less than 50 K/min. Additionally, the heating rate during pyrolysis of various biomass types under a wide range of thermal conversion conditions has been examined, in order to classify the heating rate regime of pyrolysis in state-of-the-are combustion/gasification plants. The pyrolysis of wood dust and wood pellets is found to happen always in high heating rate regimes. Therefore, the kinetic parameters obtained by conventional TGA systems (typically with heating rates lower than 50 K/min) are not applicable for them. On the contrary, the pyrolysis of wood logs always happens in low heating rate regimes, which indicates that kinetic parameters obtained by conventional TGA systems can be applied. However, pyrolysis of wood chips can undergo low or high heating rate regimes depending on their particle size. Concerning the moisture content, it can be stated that it does not strongly influence the heating rate regime of certain biomass particles. © 2011 Elsevier Ltd. All rights reserved.

Als feste biogene Brennstoffe gewinnen Pellets durch ihre hohe Energiedichte, ihre gleichbleibende Qualität und die wachsende Nachfrage immer mehr an Bedeutung. Bei der Lagerung von Holzpellets werden Emissionen frei, welche aus Abbaureaktionen von Holzbestandteilen entstehen. Es gibt bereits einige Publikationen, welche das Auftreten und die Zusammensetzung dieser Emissionen in Pelletslagern beschreiben. Es fehlen jedoch noch jegliche Nachweise zur Klärung der ursächlichen Reaktionen, weshalb die Untersuchung der Emissionen aus Pellets und deren Rohstoffen erforderlich ist.
Im Zuge dieser Arbeit werden daher zunächst die Freisetzungsraten von Kohlenmonoxid (CO) und flüchtigen organischen Verbindungen (VOC) verschiedener Holzrohstoffe und Pellets in Lagerungsversuchen untersucht. Des Weiteren erfolgt die Bestimmung des organischen Extraktstoffgehaltes dieser Holzproben mittels Soxhletextraktion. Anschließend werden diese Charakteristika einander gegenübergestellt, um mögliche Zusammenhänge zu identifizieren. Bei den untersuchten Holzarten handelt es sich um die Gemeine Fichte (Picea abies), die Europäische Lärche (Larix decidua) sowie um die Weihrauchkiefer (Pinus taeda). Von diesen drei Holzarten werden verschiedene Späne und Pellets miteinander verglichen. Zudem werden unterschiedliche am österreichischen Markt erhältliche Pellets untersucht. Die höchste Freisetzung von CO wird bei frischen Kieferpellets mit 2,88 mg CO/kg Brennstoff (BS) absolute Trockenmasse (atro)/d gemessen. Die geringste Menge an CO wird von einer handelsüblichen Pelletsprobe mit 0,02 mg CO/kg BS atro/d emittiert. Allen untersuchten Holzproben ist gemein, dass in den Lagerungsversuchen höhere Mengen an CO als an VOC freigesetzt werden. Der organische Extraktstoffgehalt der Kieferproben ist am höchsten. Der geringste organische Extraktstoffgehalt tritt bei den Fichtenhobelspänen auf. Bei allen Proben wird festgestellt, dass der organische Extraktstoffgehalt mit der Pelletierung abnimmt. Zudem wird bestimmt, dass sich mit zunehmender Trocknungstemperatur der organische Extraktstoffgehalt verringert. Ein eindeutiger Zusammenhang zwischen Extraktstoffgehalt und freigesetzten Emissionsmengen kann nicht hergestellt werden.

 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.  

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 NO_x, HCl, and SO_x 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 NO_x 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 SO_x 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.

Global trade of biomass-related products is growing exponentially, resulting in increasing 'teleconnections' between producing and consuming regions. Sustainable management of the earth's lands requires indicators to monitor these connections across regions and scales. The 'embodied human appropriation of NPP' (eHANPP) allows one to consistently attribute the HANPP resulting from production chains to consumers. HANPP is the sum of land-use induced NPP changes and biomass harvest. We present the first national-level assessment of embodied HANPP related to agriculture based on a calculation using bilateral trade matrices. The dataset allows (1) the tracing of the biomass-based products consumed in Austria in the year 2000 to their countries of origin and quantifying the HANPP caused in production, and (2) the assigning of the national-level HANPP on Austria's territory to the consumers of the products on the national level. The dataset is constructed along a consistent system boundary between society and ecosystems and can be used to assess Austria's physical trade balance in terms of eHANPP. Austria's eHANPP-trade balance is slightly negative (imports are larger than exports); import and export flows are large in relation to national HANPP. Our findings show how the eHANPP approach can be used for quantifying and mapping the teleconnections related to a nation's biomass metabolism. © 2012 Elsevier B.V.

In large scale industrial processes, such as iron production, or in gasification based process chains (coal/biomass to synthesis gas, fuel, or power, etc.), the separation of CO2 (Carbon Capture-CC) can lead to ecological and procedural benefits. Chemical absorption of CO2 is a well proved technology for CC with comparatively low electrical energy demand. However, the high heat demand, absorption kinetics, CO2 capacity and sorbent degradation are limiting factors for the industrial application. Further investigation and development of sorbent-solutions in relation to specific gas conditions are necessary for optimisation. For testing different sorbent-solutions a mobile test plant was designed and built up. Focus of this work was the evaluation of process key data for CC in blast furnace gas under real conditions. The tests have been carried out continuously up to 300 hours. Aqueous monoethanol-amine (MEA), diethanol-amine (DEA) and methyl-diethanol-amine (MDEA) solutions have been investigated. Detailed analyses of the process gas, analyses of used liquids (chemical properties, degradation products) and the examination of process data lead to further development in process design, control strategies for specific applications and give routes for an efficient implementation of CC to increase the benefit in the overall process chain.

Residential wood combustion causes major effects on the air quality on a global scale. The ambient particulate levels are known to be responsible for severe adverse health effects that include e.g. cardio-respiratory illnesses and cancer related effects, even mortality. It is known that biomass combustion derived emissions are affected by combustion technology, fuel being used and user-related practices. There are also indications that the health related toxicological effects are influenced by these parameters. This study we evaluated toxicological effects of particulate emissions (PM ₁) from seven different residential wood combusting furnaces. Two appliances i.e. log wood boiler and stove represented old batch combustion technology, whereas stove and tiled stove were designated as new batch combustion as three modern automated boilers were a log wood boiler, a woodchip boiler and a pellet boiler. The PM ₁ samples from the furnaces were collected in an experimental setup with a Dekati ® gravimetric impactor on PTFE filters with the samples being weighed and extracted from the substrates and prior to toxicological analyses. The toxicological analyses were conducted after a 24-hour exposure of the mouse RAW 264.7 macrophage cell line to four doses of emission particle samples and analysis of levels of the proinflammatory cytokine TNFα, chemokine MIP-2, cytotoxicity with three different methods (MTT, PI, cell cycle analysis) and genotoxicity with the comet assay. In the correlation analysis all the toxicological results were compared with the chemical composition of the samples. All the samples induced dose-dependent increases in the studied parameters. Combustion technology greatly affected the emissions and the concomitant toxicological responses. The modern automated boilers were usually the least potent inducers of most of the parameters while emissions from the old technology log wood boiler were the most potent. In correlation analysis, the PAH and other organic composition and inorganic ash composition affected the toxicological responses differently. In conclusion, combustion technology largely affects the particulate emissions and their toxic potential this being reflected in substantially larger responses in devices with incomplete combustion. These differences become emphasized when the large emission factors from old technology appliances are taken into account. © 2012 Elsevier Ltd.