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Conference contributions | 2015

Biomasse der Zukunft – Bioenergie der Zukunft?

Wopienka E. Biomasse der Zukunft – Bioenergie der Zukunft? Internationale Konferenz auf Schloss Weinzierl 2015, 29th of Januar 2015, Wieselburg, Austria.

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Conference Papers | 2015

Challenges toward model-based control for hybrid biomass-based heating systems

Unterberger V, Gölles M. Challenges toward model-based control for hybrid biomass-based heating systems. e-nova 2015. November 2015, Pinkafeld, Austria. Unterberger V, Gölles M. Challenges toward model-based control for hybrid biomass-based heating systems. Nachhaltige Gebäude, Graz. Leykam. 2015;10:393-404.

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Biomass boilers used for residential heating and hot water supply are typically combined with a buffer storage and solar collectors. However, the annual utilization rates typically achieved with such systems are far below those theoretically possible, which is mainly because of the often poor quality of both the individual control of the components as well as the high-level control of the entire system. The control strategies typically applied consist of simple decou-pled control circuits with linear controllers, which cannot deal with the mostly nonlinear and coupled behaviour of the components and thus do not ensure their reasonable interaction. The most appropriate approach to address these challenges is the application of model-based control techniques. Within the paper an overview of mathematical models suitable for control purposes, a simple to implement load forecasting method as well as control strate-gies for both the individual components and the entire system are presented. Future chal-lenges for a practical implementation of this novel approach are discussed in the outlook sec-tion.


Peer Reviewed Scientific Journals | 2015

Closing the Nutrient Cycle in Two-Stage Anaerobic Digestion of Industrial Waste Streams

Rachbauer L, Gabauer W, Scheidl S, Ortner M, Fuchs W, Bochmann G. Closing the Nutrient Cycle in Two-Stage Anaerobic Digestion of Industrial Waste Streams. Energy Fuels 2015;29(7):4052-4057.

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Industrial waste streams from brewing industries and distilleries provide a valuable but largely unused alternative substrate for biogas production by anaerobic digestion. High sulfur loads in the feed caused by acidic pretreatment to enhance bioavailability are responsible for H2S formation during anaerobic digestion. Microbiological oxidation of H2S provides an elegant technique to remove this toxic gas compound. Moreover, it allows for recovery of sulfuric acid, the final product of aerobic sulfide oxidation, as demonstrated in this study. Two-stage anaerobic digestion of brewer’s spent grains, the major byproduct in the brewing industry, allows for the release of up to 78% of total H2S formed in the first pre-acidification stage. Desulfurization of such pre-acidification gas in continuous acidic biofiltration with immobilized sulfur-oxidizing bacteria resulted in a maximum H2S elimination capacity of 473 g m–3 h–1 at an empty bed retention time of 91 s. Complete H2S removal was achieved at inlet concentrations of up to 6363 ppm. The process was shown to be very robust, and even after an interruption of H2S feeding for 10 days, excellent removal efficiency was immediately restored. A maximum sulfate production rate of 0.14 g L–1 h–1 was achieved, and a peak concentration of 4.18 g/L sulfuric acid was reached. Further experiments addressed the reduction of fresh water and chemicals to minimize process expenses. It was proven that up to 50% of mineral medium that is required in large amounts during microbiological desulfurization can be replaced by the liquid fraction of the digestate. The conducted study demonstrates the viability of microbial sulfur recovery with theoretical recovery rates of up to 44%.


Peer Reviewed Scientific Journals | 2015

Combustion related characterisation of Miscanthus peat blends applying novel fuel characterisation tools

Sommersacher P, Brunner T, Obernberger I, Kienzl N, Kanzian W. Combustion related characterisation of Miscanthus peat blends applying novel fuel characterisation tools. Fuel 2015;158:253-262.

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Conference contributions | 2015

Control of a Biomass-Furnace Based on Input-Output-Linearization

Schörghuber C, Reichhartinger M, Horn M, Gölles M, Seeber R. Control of a Biomass-Furnace Based on Input-Output-Linearization, European Control Conference 2015, 15th-17th of July 2015, Linz, Austria. p 3513-3518.

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Peer Reviewed Scientific Journals | 2015

Deposit build-up and ash behavior in dual fluid bed steam gasification of logging residues in an industrial power plant

Kuba M, He H, Kirnbauer F, Boström D, Öhman M, Hofbauer H. Deposit build-up and ash behavior in dual fluid bed steam gasification of logging residues in an industrial power plant. Fuel Processing Technology. 25 June 2015;139:33-41.

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A promising way to substitute fossil fuels for production of electricity, heat, fuels for transportation and synthetic chemicals is biomass steam gasification in a dual fluidized bed (DFB). Using lower-cost feedstock, such as logging residues, instead of stemwood, improves the economic operation. In Senden, near Ulm in Germany, the first plant using logging residues is successfully operated by Stadtwerke Ulm. The major difficulties are slagging and deposit build-up. This paper characterizes inorganic components of ash forming matter and draws conclusions regarding mechanisms of deposit build-up. Olivine is used as bed material. Impurities, e.g., quartz, brought into the fluidized bed with the feedstock play a critical role. Interaction with biomass ash leads to formation of potassium silicates, decreasing the melting temperature. Recirculation of coarse ash back into combustion leads to enrichment of critical fragments. Improving the management of inorganic streams and controlling temperature levels is essential for operation with logging residues.


Scientific Journals | 2015

Developing a simulation model for a mixed alcohol synthesis reactor and validation of experimental data in IPSEpro

Weber G, Di Giuliano A, Rauch R, Hofbauer H. Developing a simulation model for a mixed alcohol synthesis reactor and validation of experimental data in IPSEpro. Fuel Process Technology. 141:167-176, 2015.

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Peer Reviewed Scientific Journals | 2015

Development and validation of CFD models for gas phase reactions in biomass grate furnaces considering gas streak formation above the packed bed

Shiehnejadhesar A, Mehrabian R, Scharler R, Obernberger I. Development and validation of CFD models for gas phase reactions in biomass grate furnaces considering gas streak formation above the packed bed. Fuel Processing Technology. Volume 139, November 2015, Pages 142–158.

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State-of-the-art packed bed models supply continuous concentration profiles as boundary conditions for subsequent CFD simulations of gas phase, leading to pre-mixed combustion conditions. However, in reality the “porous” nature of the packed bed leads to streak formation influencing gas mixing and combustion. Therefore, in the present work, in order to account for the influence of the streaks on gas phase combustion, a gas streak model based on a correlation between the local gas residence time and a mixing time has been developed based on numerical simulations. Finally, the streak model was linked with an in-housed developed hybrid gas phase combustion model suitable for laminar to highly turbulent flow conditions and applied for an under-feed pellet stoker furnace (20 kWth) concerning the simulation of gas phase combustion and NOx formation. The results in comparison with a simulation without the streak formation model show that the flue gas species prediction can be improved with the proposed streak formation model. Especially, in the region above the fuel bed (in the primary combustion chamber), this is of special importance for NOx reduction by primary measures.


Conference contributions | 2015

Development of a briquette stove with a candle burning principle - characteristics and measurement results

Kirchhof J, Schmidl C, Moser W, Haslinger W. Development of a briquette stove with a candle burning principle - characteristics and measurement results, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (visual presentation)

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Conference contributions | 2015

Development of a new test method for defining a real life thermal heat output of firewood stoves

Sturmlechner R, Aigenbauer S, Moser W, Schmidl C, Reichert G, Stressler H, Schwabl M, Haslinger W. Development of a new test method for defining a real life thermal heat output of firewood stoves, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (visual presentation)

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Conference contributions | 2015

Development of a streak formation model for an improved prediction of gas phase combustion in biomass grate furnaces

Shiehnejadhesar A, Mehrabian R, Scharler R, Goldin GM, Obernberger I. Development of a streak formation model for an improved prediction of gas phase combustion in biomass grate furnaces, INFUB 10th European Conference on Industrial Furnace and Boilers 2015, 7th-10th of April 2015, Porto, Portugal.

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State-of-the-art packed bed models supply continuous concentration profiles as boundary conditions for subsequent CFD simulations of gas phase, leading to pre-mixed combustion conditions. However, in reality the “porous” nature of the packed bed leads to streak formation influencing gas mixing and combustion. Therefore, in the present work, in order to account for the influence of the streaks on gas phase combustion, a gas streak model based on a correlation between the local gas residence time and a mixing time has been developed based on numerical simulations. Finally, the streak model was linked with an in-housed developed hybrid gas phase combustion model suitable for laminar to highly turbulent flow conditions and applied for an under-feed pellet stoker furnace (20 kWth) concerning the simulation of gas phase combustion and NOx formation. The results in comparison with a simulation without the streak formation model show that the flue gas species prediction can be improved with the proposed streak formation model. Especially, in the region above the fuel bed (in the primary combustion chamber), this is of special importance for NOx reduction by primary measures.


Peer Reviewed Scientific Journals | 2015

Econometric analysis of the wood pellet market in Austria

Kristöfel C, Strasser C, Morawetz U, Schmid E. Econometric analysis of the wood pellet market in Austria. 12th International Conference On The European Energy Market, 20-22 May 2015. 20 August 2015, Lisbon, Portugal.

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Other Presentations | 2015

Effects of pretreatment and storage methods on biomethane potential of different microalgae in anaerobic digestion

Gruber M, Jerney J, Zohar E, Nussbaumer M, Hieger C, Bochmann G, Schagerl M, Obbard JP, Fuchs W, Drosg B. Effects of pretreatment and storage methods on biomethane potential of different microalgae in anaerobic digestion, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (oral presentation)

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Peer Reviewed Scientific Journals | 2015

Efficiency and operational behaviour of small-scale pellet boilers installed in residential buildings

Carlon E, Schwarz M, Golicza L, Verma VK, Prada A, Baratieri M, et al. Efficiency and operational behaviour of small-scale pellet boilers installed in residential buildings. Appl Energy 2015;155:854-865.

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Conference contributions | 2015

Emission Reduction of Firewood Stoves by Integrated Honeycomb Catalysts

Reichert G, Schmidl C, Schwabl M, Sedlmayer I, Stressler H, Sturmlechner R, Wöhler M, Haslinger W. Emission Reduction of Firewood Stoves by Integrated Honeycomb Catalysts, Word Sustainable Energy Days next 2015, 24th-27th of February 2015, Wels, Austria.

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Peer Reviewed Scientific Journals | 2015

Energy self-supply of large abattoir by sustainable waste utilisation based on anaerobic mono-digestion

Ortner M, Wöss D, Schumergruber A, Pröll T, Fuchs W. Energy self-supply of large abattoir by sustainable waste utilisation based on anaerobic mono-digestion. Applied Energy. 2015;143:460-471.

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Abattoirs have a large number of energy intensive processes. Beside energy supply, disposal costs of animal by-products (ABP) are the main relevant cost drivers. In this study, successful implementation of a new waste and energy management system based on anaerobic digestion is described. Several limitations and technical challenges regarding the anaerobic digestion of the protein rich waste material had to be overcome. The most significant problems were process imbalances such as foaming and floatation as well as high accumulation of volatile fatty acids and low biogas yields caused by lack of essential microelements, high ammonia concentrations and fluctuation in operation temperature. Ultimately, 85% of the waste accumulated during the slaughter process is converted into 2700 MW h thermal and 3200 MW h electrical energy in a biogas combined heat and power (CHP) plant. The thermal energy is optimally integrated into the production process by means of a stratified heat buffer. The energy generated by the biogas CHP-plant can cover a significant share of the energy requirement of the abattoir corresponding to 50% of heat and 60% of electric demand, respectively. In terms of annual cost for energy supply and waste disposal a reduction of 63% from 1.4 Mio € to about 0.5 Mio € could be achieved with the new system. The payback period of the whole investment is approximately 9 years. Beside the economic benefits also the positive environmental impact should be highlighted: a 79% reduction of greenhouse gas emissions from 4.5 Mio kg CO2 to 0.9 Mio kg CO2 annually was achieved. The realized concept received the Austrian Energy Globe Award and represents the first anaerobic mono-digestion process of slaughterhouse waste worldwide.


Other Presentations | 2015

Entwicklung eines modellbasierten Optimierungsalgorithmus für die Wärmeversorgung mit Biomassefeuerungen

Oberlechner, F. Entwicklung eines modellbasierten Optimierungsalgorithmus für die Wärmeversorgung mit Biomassefeuerungen, Master Thesis, Technische Universität Graz, Graz, Austria, 2015.

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Wärmeversorgungsanlagen von Gebäuden, bestehend aus Biomasse-Feuerung, Solarkollektoren, Pufferspeicher, Heizkreis und Warmwasserzapfstellen gewinnen aufgrund ihrer Nachhaltigkeit zunehmend an Bedeutung. In den letzten Jahren wurden insbesondere für eine effiziente Regelung der Biomasse-Feuerung sehr gute Konzepte entwickelt. Diese können jedoch zumeist aufgrund unzureichender, übergeordneter Systemregelungen nicht ihr volles Potential ausschöpfen. In ihrer primitivsten Ausführung schaltet eine Systemregelung die Biomasse-Feuerung anhand der Ladehöhe des Pufferspeichers aus und ein. Diese Art der Regelung hat unweigerlich viele Ein-/ Ausschaltvorgänge der Feuerung, sowie eine schlechte Ausnutzung des solaren Eintrags zur Folge. Insbesondere bei Biomasse-Feuerungen sind Ein-/ Ausschaltvorgänge äußerst unwirtschaftlich und führen zu stark erhöhten Schadstoffemissionen. Die häufigen Ein-/ Ausschaltvorgänge verursachen zusätzlich erhöhte Wartungs- und Betriebskosten und schlussendlich eine verkürzte Lebensdauer zahlreicher Komponenten. Um die Ein-/ Ausschaltvorgänge zu minimieren und den solaren Eintrag zu steigern, soll im Rahmen dieser Arbeit ein übergeordnetes, modellprädiktives Regelungskonzept für die gesamte Wärmeversorgungsanlage entwickelt werden. Nach einer theoretischen Einführung in gemischt-ganzzahlige Optimalsteuerungsprobleme sowie ausgewählter Lösungsmethoden werden Prädiktionsmodelle für alle Komponenten der Wärmeversorgungsanlage entwickelt. Aufbauend auf den mathematischen Modellen für die einzelnen Komponenten der Anlage wird eine nichtlineare modellprädiktive Regelung entwickelt. Diese berücksichtigt zusätzlich Wetterprognosen sowie die erwartete Lastabnahme und führt schlussendlich zu einer Minimierung des Brennstoffverbrauchs sowie der Anzahl der Ein-/ Ausschaltvorgänge. Den Abschluss der Arbeit bilden ausführliche Simulationsstudien mit unterschiedlichen Wetterszenarien sowie Vergleiche mit herkömmlichen Regelungsstrategien.  


Contributions to trade journals | 2015

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

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

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Peer Reviewed Scientific Journals | 2015

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

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

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


Conference contributions | 2015

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

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

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Reviewed Conference Papers | 2015

Heat pump enhanced heat recovery from flue gas of wood chips combustion

Hebenstreit B, Schwabl M, Höftberger E, Kronberger B, Gappmayr B, Gautsch H, Lundgren J, Toffolo A. Heat pump enhanced heat recovery from flue gas of wood chips combustion, INFUB 10th European Conference on Industrial Furnace and Boilers 2015, 7th-10th of April 2015, Porto, Portugal.

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Contributions to trade journals | 2015

Hydrogen from the high temperature water gas shift reaction with an industrial Fe/Cr catalyst using biomass gasification tar rich synthesis gas

Chianese, S, Loipersböck J, Malits M, Rauch R, Hofbauer H, Molino A, Musmarra D. Hydrogen from the high temperature water gas shift reaction with an industrial Fe/Cr catalyst using biomass gasification tar rich synthesis gas. Fuel Processing Technology. 2015;132:39-48.

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The high temperature water gas shift reaction (HTS) over an iron/chromium (Fe/Cr) industrial catalyst was investigated in a pilot scale plant consisting of two fixed-bed reactors arranged in series and a biomass-derived tar-rich synthesis gas was used as a feed-stream. CO conversion and selectivity for the water gas shift reaction were evaluated through parameter variation. Four dry gas hourly space velocities (GHSv) and two steam to dry synthesis gas ratios (H2O/SGd) equal to 52% v/v and 60% v/v were investigated at temperatures (T) of 350–450 °C. CO conversion was investigated by varying H2S concentration 180–540 ppmv (dry basis) at a temperature of 425 °C, considering two GHSVd. The highest CO conversion (~ 83%) was observed in the basis case at 60% v/v H2O/SGd, and 450 °C. The catalyst appeared to be resistant to sulfur poisoning deactivation, and achieved 48% CO conversion at the maximum H2S concentration used.


Contributions to trade journals | 2015

Hydrogen from the high temperature water gas shift reaction with an industrial Fe/Cr catalyst using biomass gasification tar rich synthesis gas

Chianese S, Loipersböck J, Malits M, Rauch R, Hofbauer H, Molino A, et al. Hydrogen from the high temperature water gas shift reaction with an industrial Fe/Cr catalyst using biomass gasification tar rich synthesis gas. Fuel Process Technol 2015;132:39-48.

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Peer Reviewed Scientific Journals | 2015

Implementation of a firebed cooling device and its influence on emissions and combustion parameters at a residential wood pellet boiler

Gehrig M, Pelz SK, Jaeger D, Hofmeister G, Groll A, Thorwarth H, Haslinger W. Implementation of a firebed cooling device and its influence on emissions and combustion parameters at a residential wood pellet boiler. Applied Energy. 01 December 2015;159: 310-316.

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This study investigates the general concept of reduced firebed temperatures in residential wood pellet boilers. Residential wood pellet boiler development is more and more concerned with inorganic aerosols characterized by a temperature-dependent release from the firebed. Hence, different concepts are applied aiming to reduce firebed temperatures. Unfortunately, these concepts influence not only firebed temperatures, but also other important parameters like air flow rates which may cause unwanted side effects with respect to combustion quality or efficiency. Thus, a new approach was developed solely affecting firebed temperature by implementing a water-based firebed cooling in a 12 kW underfeed pellet boiler. The effectiveness of the cooling was monitored by comprehensive temperature measurement in the firebed. The cooling capacity ranged from 0.4 kW to 0.5 kW resulted in a significant decrease of firebed temperatures. Gaseous emissions remain stable showing no significant changes in major components (O2, CO2, NOx). Furthermore, CO emissions were even reduced significantly by the activated cooling, which was supposedly caused by a stabilized devolatilization due to the firebed cooling. Moreover, the temperature-dependent release of aerosol forming elements was influenced at activated firebed cooling, which is proved by a decrease of 17 wt% of dust (Total Suspended Particles; TSP). At the same time the gaseous emissions of HCl increase, supposedly by a reduced potassium release from the firebed to the gas phase and a subsequently different particle formation. The general concept of reduced firebed temperatures proved to be successful decreasing overall aerosol emissions without impacting combustion quality.


Peer Reviewed Scientific Journals | 2015

Influence of bed material coatings on the water-gas-shift reaction and steam reforming of toluene as tar model compound of biomass gasification

Kuba M, Havlik F, Kirnbauer F, Hofbauer H. Influence of bed material coatings on the water-gas-shift reaction and steam reforming of toluene as tar model compound of biomass gasification. Biomass and Bioenergy. 7 August 2015;89:40-49

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A promising technology replacing fossil energy carriers for the production of electricity, heat, fuels for transportation and synthetic chemicals is steam gasification of biomass in a dual fluid bed (DFB). The principle of this technology is the separation into a gasification and a combustion reactor. Bed material, nowadays olivine, circulates between them, and has two functions. It acts as a heat carrier from the combustion to the gasification zone and as catalyst regarding gasification reactions. Today, an alternative to olivine does yet not exist.

In this work, experiments in a lab-scale test rig were performed investigating the catalytic activity of different fresh and used bed materials, such as olivine and quartz. The enhancement of the catalytic activity due to particle coatings was tested regarding the water-gas-shift reaction and steam reforming of toluene. Calcite is known as an active material in this respect and is therefore used as a benchmark substance.

Experiments revealed a correlation between the catalytic activity of bed particle coatings towards both the water-gas-shift reaction and the reduction of toluene by steam reforming. Results showed bed material particles with a calcium (Ca)-rich layer achieve satisfactory conversion of carbon monoxide and reduction of toluene. Furthermore, a qualitative comparison regarding hydrogen production relative to the benchmark material CaO is given for the water-gas-shift and steam reforming of toluene and ethene - used as model substance for lighter hydrocarbons. These results are the basis for further research on the catalytic properties of potential bed materials for DFB gasification of biomass.


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