Publications

Peer reviewed papers | 2008

Challenges in small-scale combustion of agricultural biomass fuels

Carvalho L, Lundgren J, Wopienka E. Challenges in small-scale combustion of agricultural biomass fuels. International Journal of Energy for a Clean Environment. 2008;9(1-3):127-42.

External Link Details

Straw, Miscanthus, maize, and horse manure were reviewed in terms of fuel characteristics. They were tested in existing boilers, and the particulate and gaseous emissions were monitored. The ash was analyzed for the presence of sintered material. All the fuels showed problems with ash lumping and slag formation. Different boiler technologies showed different operational performances. Maize and horse manure are problematic fuels regarding NOx and particulate emissions. Miscanthus was the best fuel tested. Due to the big variation of fuel properties and therefore combustion behavior of agricultural biomass, further R&D is required to adapt the existing boilers for these fuels.

Peer reviewed papers | 2008

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

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

External Link Details

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

Other Publications | 2012

Analytical approach for the determination of micro elements in anaerobic digestion systems by sequential extraction technique

Rachbauer, L. Analytical approach for the determination of micro elements in anaerobic digestion systems by sequential extraction technique, Master Thesis, University of Natural Resources and Life Sciences Vienna, Vienna, Austria, 2012.

Details

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.

Peer reviewed papers | 2012

Counteracting ammonia inhibition in anaerobic digestion by removal with a hollow fiber membrane contactor

Lauterböck B, Ortner M, Haider R, Fuchs W. Counteracting ammonia inhibition in anaerobic digestion by removal with a hollow fiber membrane contactor. Water Res. 2012;46(15):4861-9.

External Link Details

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.

Peer reviewed papers | 2012

Emissionsfaktoren und chemische Charakterisierung von Feinstaubemissionen moderner und alter Biomasse-Kleinfeuerungen über typische Tageslastverläufe

Kelz J, Brunner T, Obernberger I. Emission factors and chemical characterisation of fi ne particulate emissions from modern and old residential biomass heating systems determined for typical load cycles. Environmental Sciences Europe. 2012;24(3).

External Link Details
Peer reviewed papers | 2012

Odor, gaseous and PM 10 emissions from small scale combustion of wood types indigenous to central Europe

Kistler M, Schmidl C, Padouvas E, Giebl H, Lohninger J, Ellinger R, et al. Odor, gaseous and PM 10 emissions from small scale combustion of wood types indigenous to central Europe. Atmos Environ. 2012;51:86-93.

External Link Details

In this study, we investigated the emissions, including odor, from log wood stoves, burning wood types indigenous to mid-European countries such as Austria, Czech Republic, Hungary, Slovak Republic, Slovenia, Switzerland, as well as Baden-Württemberg and Bavaria (Germany) and South Tyrol (Italy). The investigations were performed with a modern, certified, 8 kW, manually fired log wood stove, and the results were compared to emissions from a modern 9 kW pellet stove. The examined wood types were deciduous species: black locust, black poplar, European hornbeam, European beech, pedunculate oak (also known as “common oak”), sessile oak, turkey oak and conifers: Austrian black pine, European larch, Norway spruce, Scots pine, silver fir, as well as hardwood briquettes. In addition, “garden biomass” such as pine cones, pine needles and dry leaves were burnt in the log wood stove. The pellet stove was fired with softwood pellets.

The composite average emission rates for log wood and briquettes were 2030 mg MJ−1 for CO; 89 mg MJ−1 for NOx, 311 mg MJ−1 for CxHy, 67 mg MJ−1 for particulate matter PM10 and average odor concentration was at 2430 OU m−3. CO, CxHy and PM10 emissions from pellets combustion were lower by factors of 10, 13 and 3, while considering NOx – comparable to the log wood emissions. Odor from pellets combustion was not detectable. CxHy and PM10 emissions from garden biomass (needles and leaves) burning were 10 times higher than for log wood, while CO and NOx rise only slightly. Odor levels ranged from not detectable (pellets) to around 19,000 OU m−3 (dry leaves). The odor concentration correlated with CO, CxHy and PM10. For log wood combustion average odor ranged from 536 OU m−3 for hornbeam to 5217 OU m−3 for fir, indicating a considerable influence of the wood type on odor concentration.

Other Publications | 2013

Austrian context for biowaste and case study on brewery waste

Bochmann G. Austrian context for biowaste and case study on brewery waste, Biogaz Europe 2013, 20th of March 2013, Nantes, France.

Details
Other Publications | 2013

Can bioavailability of trace nutrients be measured in an AD process?

Ortner M, Rachbauer L, Somitsch W, Fuchs W. Can bioavailability of trace nutrients be measured in an AD process? Bioenergy Conference 2013, 4th-6th of September 2013, Jyväskylä, Finnland.

Details
Peer reviewed papers | 2013

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

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

External Link Details

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

Other Publications | 2013

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

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

Details
Other Publications | 2013

Microbial conversion of H2S for sulphuric acid recycling

Rachbauer L, Gabauer W, Ortner M, Bochmann G. Microbial conversion of H2S for sulphuric acid recycling, 9th International Conference on Renewable Resources & Biorefineries 2013, 5th-7th of June 2013, Antwerpen, Belgium. (peer reviewed) (visual presentation)

Details
Other Publications | 2013

Pylogenetic (SSU) and Fatty Acid Analysis of Several Algal Strains within the Trebouxiophyceae and Implications for Commercial Purposes

Gruber M, Darienko T, Pröschold T, Jirsa F, Schagerl M. Pylogenetic (SSU) and Fatty Acid Analysis of Several Algal Strains within the Trebouxiophyceae and Implications for Commercial Purposes, 21st European Biomass Conference and Exhibition 2013, 3rd-7th of June 2013, Copenhagen, Denmark.

Details
Books / Bookchapters | 2013

Storage and pre-treatment of substrates for biogas production

Bochmann G, Montgomery L. Storage and pre-treatment of substrates for biogas production. The biogas handbook. ISBN 978 0 85709 498 8 2013:85-103.

External Link Details

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.

Other Publications | 2013

Two-Stage Anaerobic Digestion of Sugar Beet Pressed Pulp - Optimizing of reactor performance

Stoyanova E et al. Two-Stage Anaerobic Digestion of Sugar Beet Pressed Pulp - Optimizing of reactor performance, 13th World Congress on Anaerobic Digestion 2013, 25th-28th of June 2013, Santiago de Compostela, Spain. (peer reviewed) (visual presentation)

Details
Other Publications | 2014

Biomass Gasification for Synthesis Gas Production and Applications of the Syngas

Rauch R, Hrbek J, Hofbauer H. Biomass gasification for synthesis gas production and applications of the syngas. Wiley Interdisciplinary Reviews: Energy and Environment. 2014;3(4):343-62.

External Link Details

Synthesis gas from biomass can be produced and utilized in different ways. Conversion of biomass to synthesis gas can be done either in fluidized bed or entrained flow reactors. As gasification agent oxygen, steam, or mixtures are used. The most common use of biomass gasification in the last decades has been for heat and/or power production. Nowadays, the importance of transportation fuels from renewables is increased due to environmental aspects and growing fossil fuels prices. That is why the production of Fischer-Tropsch (FT) liquids, methanol, mixed alcohols, substitute natural gas (SNG), and hydrogen from biomass is now in focus of view. The most innovative and interesting ways of synthesis gas utilization and projects, BioTfueL or GoBiGas, BioLiq, Choren, etc. are discussed here. Further the microchannel technology by Oxford Catalysts and distributed production of SNG in decentral small scale are presented. The synthesis platform in Güssing, Austria is also presented. The FT liquids, hydrogen production, mixed alcohols, and BioSNG, these are the projects associated with the FICFB gasification plant in Güssing. Also the principle and examples of sorption-enhanced reforming to adjust H2/CO ratio in product gas during the gasification is described. Finally, in the conclusion also an outlook for the thermochemical pathway to transportation fuels is given. WIREs Energy Environ 2014, 3:343-362. doi: 10.1002/wene.97 For further resources related to this article, please visit the WIREs website. © 2013 Wiley Periodicals, Inc.

Other Publications | 2014

Can bioavailability of trace elements be measured in AD systems?

Ortner M, Rachbauer L, Somitsch W, Bochmann G, Fuchs W. Can bioavailability of trace elements be measured in AD systems? Biogas Science 2014, International Conference on Anaerobic Digestion 26th–30th of October 2014, Vienna, Austria.

Details
Peer reviewed papers | 2014

Can bioavailability of trace nutrients be measured in anaerobic digestion?

Ortner M, Rachbauer L, Somitsch W, Fuchs W. Can bioavailability of trace nutrients be measured in anaerobic digestion? Appl Energy. 2014;126:190-8.

External Link Details

Trace nutrients significantly affect the microbial metabolic activity within anaerobic digestion processes but always imply the risk of overdosing of heavy metals. In this study the applicability of a sequential extraction scheme established for soil and sediment samples on biogas slurries with different compositions was tested and compared to an adapted version of this extraction method. The analytical results proved the successful applicability of the developed analytical technique for the speciation of trace nutrients in anaerobic digestion systems. The procedure fulfills the basic requirements of reproducible data, a time-saving analytical approach and economic feasibility. Recovery rates of 90-110% were obtained for the most important trace elements Fe, Co, Cu, Mo, Ni and Zn. However, it was demonstrated that the adapted method provides more reliable information about the bioavailable fractions and it is considered the more appropriate approach. Data on fractionation indicated that up to 76% of these essential trace nutrients might be present in an insoluble state. Depending on the specific trace element a significant fraction, from 30% to more than 70%, is not directly bioavailable. This important aspect should be considered to guarantee sufficient supply of the microbial consortium with trace elements and at the same time to avoid overdosage. © 2014 Elsevier Ltd.

Peer reviewed papers | 2014

Efficient anaerobic mono-digestion of N-rich slaughterhouse waste: Influence of ammonia, temperature and trace elements

Ortner M, Leitzinger K, Skupien S, Bochmann G, Fuchs W. Efficient anaerobic mono-digestion of N-rich slaughterhouse waste: Influence of ammonia, temperature and trace elements. Bioresour Technol. 2014;174:222-32.

External Link Details

Three mono-digestion experiments treating slaughterhouse waste with high TKN concentration (~11. g/kg) were applied in lab-scale at mesophilic and psychrophilic conditions to study the impact of high ammonia concentrations and additives. Precipitation of sulphur by addition of ferrous chloride did not influence process behaviour, whereas supplementation of trace elements significantly improved process stability by reducing volatile fatty acid concentration towards zero.The limit of NH4-N concentration causing a rise of VFAs to 19,000mg/l and reduction of methane by 25% was found between 7.7 and 9.1g/kg which correspond to NH3 concentrations of 830-1060mg/l.Psychrophilic operation (25°C) lowered inhibitory NH3 concentration to 140mg/l, but process performance was stable only at low OLR of 0.4kgVS/m3d.Robust performance at highest possible NH4-N concentration (7.7g/kg), low VFA accumulation and satisfying methane yield of about 280Nm3/t COD was observed at OLR of 2.5kgVS/m3d at 37°C. © 2014 Elsevier Ltd.

Other Publications | 2014

Fermentation of biomass from micro algae

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

Details
Other Publications | 2014

H2S and NH3 tolerance of acidophilic sulfur-oxidizing bacteria

Rachbauer L, Lorber G, Ortner M, Bochmann G. H2S and NH3 tolerance of acidophilic sulfur-oxidizing bacteria, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

Details
Other Publications | 2014

Microalgae as source of biogas: Anaerobic digestion of un- and pre-treated biomass

Gruber M, Zohar E, Jerney J, Nussbaumer M, Ludwig I, Hieger C, Bromberger P, Bochmann G, Obbard JP, Schagerl M, Fuchs W, Drosg B. Microalgae as source of biogas: Anaerobic digestion of un- and pre-treated biomass, Algae Networking Event 2014, 11th of September 2014, Dürnrohr, Austria. (oral presentation)

Details
Peer reviewed papers | 2014

Reducing the risk of foaming and decreasing viscosity by two-stage anaerobic digestion of sugar beet pressed pulp

Stoyanova E, Forsthuber B, Pohn S, Schwarz C, Fuchs W, Bochmann G. Reducing the risk of foaming and decreasing viscosity by two-stage anaerobic digestion of sugar beet pressed pulp. Biodegradation. 2014;25(2):277-89.

External Link Details

Anaerobic digestion (AD) of sugar beet pressed pulp (SBPP) is a promising treatment concept. It produces biogas as a renewable energy source making sugar production more energy efficient and it turns SBPP from a residue into a valuable resource. In this study one- and two-stage mono fermentation at mesophilic conditions in a continuous stirred tank reactor were compared. Also the optimal incubation temperature for the pre-acidification stage was studied. The fastest pre-acidification, with a hydraulic retention time (HRT) of 4 days, occurred at a temperature of 55 °C. In the methanogenic reactor of the two-stage system stable fermentation at loading rate of 7 kg VS/m3 d was demonstrated. No artificial pH adjustment was necessary to maintain optimum levels in both the pre-acidification and the methanogenic reactor. The total HRT of the two-stage AD was 36 days which is considerably lower compared to the one-stage AD (50 days). The frequently observed problem of foaming at high loading rates was less severe in the two-stage reactor. Moreover the viscosity of digestate in the methanogenic stage of the two-stage fermentation was in average tenfold lower than in the one-stage fermentation. This decreases the energy input for the reactor stirring about 80 %. The observed advantages make the two-stage process economically attractive, despite higher investments for a two reactor system. © 2013 Springer Science+Business Media Dordrecht.
 

Other Publications | 2014

Scenedesmus obliquus as Source for Biogas: Anaerobic Digestion of Untreated and Pre-treated Biomass.

Gruber M, Zohar E, Jerney J, Bochmann G, Obbard JP, Schagerl M, Fuchs W, Drosg B. Scenedesmus obliquus as Source for Biogas: Anaerobic Digestion of Untreated and Pre-treated Biomass, 15. Tagung der Sektion Phykologie der DGB 2014, 23rd-26th of February 2014, Stralsund, Germany.

Details
Peer reviewed papers | 2014

Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers

Hebenstreit B, Schnetzinger R, Ohnmacht R, Höftberger E, Lundgren J, Haslinger W, et al. Techno-economic study of a heat pump enhanced flue gas heat recovery for biomass boilers. Biomass Bioenergy. 2014;71:12-22.

External Link Details

An active condensation system for the heat recovery of biomass boilers is evaluated. The active condensation system utilizes the flue gas enthalpy exiting the boiler by combining a quench and a compression heat pump. The system is modelled by mass and energy balances. This study evaluates the operating costs, primary energy efficiency and greenhouse gas emissions on an Austrian data basis for four test cases. Two pellet boilers (10kW and 100kW) and two wood chip boilers (100kW and 10MW) are considered. The economic analysis shows a decrease in operating costs between 2% and 13%. Meanwhile the primary energy efficiency is increased by 3-21%. The greenhouse gas emissions in CO2 equivalents are calculated to 15.3-27.9kg MWh-1 based on an Austrian electricity mix. The payback time is evaluated on a net present value (NPV) method, showing a payback time of 2-12 years for the 10MW wood chip test case. © 2014 Elsevier Ltd.

Other Publications | 2014

Thermo-chemical pre-treatment of brewers' spent grains

Gorter S, Rachbauer L, Scheidl S, Gabauer W, Ortner M, Bochmann G. Thermo-chemical pre-treatment of brewers' spent grains, 4th Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

Details
Peer reviewed papers | 2015

Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield

Gruber-Brunhumer MR, Jerney J, Zohar E, Nussbaumer M, Hieger C, Bochmann G, Schagerl M, Obbard JP, Fuchs W, Drosg B. Acutodesmus obliquus as a benchmark strain for evaluating methane production from microalgae: Influence of different storage and pretreatment methods on biogas yield. Algal Research. 01 November 2015;12:230-238.

External Link Details
Peer reviewed papers | 2015

Air staging to reduce emissions from energy crop combustion in small scale applications

Carroll JP, Finnan JM, Biedermann F, Brunner T, Obernberger I. Air staging to reduce emissions from energy crop combustion in small scale applications. Fuel. 2015;155:37-43.

External Link Details

The results of experimental work to investigate the effects of air staging on emissions from energy crop combustion in small scale applications are presented. Five different biomass fuels (wood, willow, miscanthus, tall fescue and cocksfoot) were combusted in a small scale (35 kW) biomass boiler and three different tests looking at the effects of (1) air ratio in the primary combustion chamber (primary air ratio), (2) temperature in the primary combustion chamber, and (3) overall excess air ratio, on NOx and particulate emissions were conducted. It was shown that by varying the primary air ratio, NOx emission reductions of between 15% (wood) and 30% (Miscanthus) and PM1 reductions of between 16% (cocksfoot) and 26% (wood) were possible. For all fuels, both NOx and particulate emissions were minimised at a primary air ratio of 0.8. Particulate emissions from miscanthus increased with increasing temperature in the primary combustion chamber, NOx emissions from Miscanthus and from willow also increased with temperature. Overall excess air ratio has no effect on emissions as no significant differences were found for any of the fuels. Emissions of particulates and oxides of nitrogen from a wide range of biomass feedstocks can be minimised by optimising the primary air ratio and by maintaining a temperature in the primary combustion chamber of approximately 900 °C.

Peer reviewed papers | 2015

Anaerobic digestion of thermal pretreated brewers' spent grains

Bochmann G, Drosg B, Fuchs W. Anaerobic digestion of thermal pretreated brewers' spent grains. Environmental Progress and Sustainable Energy. 2015;34(4):1092-6.

External Link Details

Anaerobic digestion offers a good opportunity to degrade residues from breweries to biogas. To improve the anaerobic degradation process thermal pretreatment of brewers' spent grains (BSG) offers the opportunity to increase degradation rate and biogas yield. Aim of the work is to show the influence of the thermal pretreatment of BSG to anaerobic digestion. BSG were pretreated at different temperature levels from 100 to 200°C. The biogas production of thermally pretreated BSG lies between 30 and 40% higher than for untreated reference. The temperature of the pretreatment process has a significant influence on the degradation rate or gas yield, respectively. Up to a temperature of 160°C, the biogas yield rises. Temperatures over 160°C result in a slower degradation and decreasing biogas yield. Substrate with and without pretreatment gave a daily biogas yield of 430 and 389 Nm3 × kg-1 VS, respectively. Batch analysis of the biochemical methane potential gives a total methane yield of 409.8 Nm3 CH4 × kg-1 VS of untreated brewers' spent grains and 467.6 Nm3 CH4 × kg-1 VS of the pretreated samples. For pretreatment energy balance estimation has been carried out. Without any heat recovery demand is higher than the energy surplus resulting from pretreatment of BSG. With energy recovery by heat exchanger the net energy yield could be increased to 38.87 kWh × kg-1 FM or 8.81%. © 2015 American Institute of Chemical Engineers Environ Prog.

Other Publications | 2015

Aspects of microalgal biomass as feedstock in biogas plants

Gruber M, Zohar E, Jerney J, Ludwig I, Bochmann G, Nussbaumer L, Montgomery L, Fuchs W, Drosg B, Schöpp T, Obbard JP. Aspects of microalgal biomass as feedstock in biogas plants, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (visual presentation)

Details
Peer reviewed papers | 2015

Bioavailability of essential trace elements and their impact on anaerobic digestion of slaughterhouse waste

Ortner M, Rameder M, Rachbauer L, Bochmann G, Fuchs W. Bioavailability of essential trace elements and their impact on anaerobic digestion of slaughterhouse waste. Biochemical Engineering Journal. 15 July 2015;99:107-113.

External Link Details
Peer reviewed papers | 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.

External Link Details

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 papers | 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.

External Link Details
Peer reviewed papers | 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.

External Link Details

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.

Peer reviewed papers | 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.

External Link Details
Other Publications | 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)

Details
Peer reviewed papers | 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.

External Link Details
Peer reviewed papers | 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.

External Link Details

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.

Peer reviewed papers | 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.

External Link Details

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.

Peer reviewed 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.

External Link Details
Peer reviewed papers | 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.

External Link Details

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 papers | 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

External Link Details

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.

Peer reviewed papers | 2015

Investigation of the corrosion behaviour of 13CrMo4-5 for biomass fired boilers with coupled online corrosion and deposit probe measurements

Gruber T, Schulze K, Scharler R, Obernberger I. Investigation of the corrosion behaviour of 13CrMo4-5 for biomass fired boilers with coupled online corrosion and deposit probe measurements. Fuel. 2015;144:15-24.

External Link Details

High-temperature corrosion in biomass fired boilers is still an insufficiently explored phenomenon which causes unscheduled plant shutdowns and hence, economical problems. To investigate the high-temperature corrosion and deposit formation behaviour of superheater tube bundles, online corrosion probe as well as deposit probe measurements have been carried out in a specially designed fixed bed/drop tube reactor in order to simulate a superheater boiler tube under well-controlled conditions. The investigated boiler steel 13CrMo4-5 is commonly used as steel for superheater tube bundles in biomass fired boilers. Forest wood chips and quality sorted waste wood (A1-A2 according to German standards) as relevant fuels have been selected to investigate the influence on the deposit formation and corrosion behaviour. The following influencing parameter variations have been performed during the test campaigns: flue gas temperature between 650 and 880°C, steel temperature between 450 and 550°C and flue gas velocity between 2 and 8 m/s. One focus of the work presented is the detailed investigation of the structure and the chemical composition of the deposits formed as well as of the corrosion products. A further goal of the work presented was the development of an empirical model which can be used within CFD simulations of flow and heat transfer to calculate and evaluate the local corrosion potential of biomass fired plants already at the planning stage. The corrosion probe measurements show a clear dependency on the parameters investigated and the empirical function developed reproduces the measured corrosion behaviour sufficiently accurate. Since the additional calculation time within the CFD simulation is negligible the model represents a helpful tool for plant designers to estimate whether high-temperature corrosion is of relevance for a certain plant or not, when using fuels with similar compositions and the steel 13CrMo4-5. © 2014 Elsevier Ltd. All rights reserved.

Other papers | 2015

Investigations on the catalytic activity of bed material coating regarding the water-gas-shift reaction and the steam reforming of model compounds for lighter and heavier hydrocarbons

Kuba M, Havlik F, Kirnbauer F, Hofbauer H. Investigations on the catalytic activity of bed material coating regarding the water-gas-shift reaction and the steam reforming of model compounds for lighter and heavier hydrocarbons. 23rd European Biomass Conference & Exhibition (oral presentation). June 2015, Vienna, Austria.

Details
Other Publications | 2015

Life cycle analysis of small scale pellet boilers characterized by high efficiency and low emissions

Monteleone B, Chiesa M, Marzuoli R, Verma VK, Schwarz M, Carlon E, Schmidl C, Ballarin Denti A. Life cycle analysis of small scale pellet boilers characterized by high efficiency and low emissions. Applied Energy. 1 October 2015;155:160-170.

External Link Details
Other papers | 2015

Liquid biofuels from biomass steam gasification

Rauch R. Liquid biofuels from biomass steam gasification. 23rd European Biomass Conference & Exhibition, side event Austrian Day (oral presentation). June 2015, Vienna, Austria.

Details
Peer reviewed papers | 2015

Optimization of a 50 MW bubbling fluidized bed biomass combustion chamber by means of computational particle fluid dynamics

Kraft S, Kuba M, Kirnbauer F, Bosch K, Hofbauer H. Optimization of a 50 MW bubbling fluidized bed biomass combustion chamber by means of computational particle fluid dynamics. Biomass and Bioenergy. 4 August 2015;89:31-39.

External Link Details

An efficient utilization of biomass fuels in power plants is often limited by the melting behavior of the biomass ash, which causes unplanned shutdowns of the plants. If the melting temperature of the ash is locally exceeded, deposits can form on the walls of the combustion chamber. In this paper, a bubbling fluidized bed combustion chamber with 50 MW biomass input is investigated that severely suffers deposit build-up in the freeboard during operation. The deposit layers affect the operation negatively in two ways: they act as an additional heat resistance in regions of heat extraction, and they can come off the wall and fall into the bed and negatively influence the fluidization behavior. To detect zones where ash melting can occur, the temperature distribution in the combustion chamber is calculated numerically using the commercial CPFD (computational particle fluid dynamics) code, Barracuda Version 15. Regions where the ash melting temperature is exceeded are compared with the fouling observed on the walls in the freeboard. The numerically predicted regions agree well with the observed location of the deposits on the walls. Next, the model is used to find an optimized operating point with fewer regions in which the ash melting temperature is exceeded. Therefore, three cases with different distributions of the inlet gas streams are simulated. The simulations show if the air inlet streams are moved from the freeboard to the necking area above the bed a more even temperature distribution is obtained over the combustion chamber. Hence, the areas where the ash melting temperatures are exceeded are reduced significantly and the formation of deposits in the optimized operational mode is much less likely.

Conference presentations and posters | 2015

Parameter Study with Sulfidized Molybdenum Catalyst for Mixed Alcohol Synthesis with Biomass-Derived Synthesis Gas

Weber G, Rauch R, Hofbauer H. Parameter Study with Sulfidized Molybdenum Catalyst for Mixed Alcohol Synthesis with Biomass-Derived Synthesis Gas, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (oral presentation)

External Link Details
Peer reviewed papers | 2015

Performance of a water gas shift pilot plant processing product gas from an industrial scale biomass steam gasification plant

Kraussler M, Binder M, Fail S, Bosch K, Hackel M, Hofbauer H. Performance of a water gas shift pilot plant processing product gas from an industrial scale biomass steam gasification plant. Biomass and Bioenergy. 4 August 2015;89:50-57.

External Link Details

In this paper, the performance of a commercial Fe/Cr based catalyst for the water gas shift reaction was investigated. The catalyst was used in a water gas shift pilot plant which processed real product gas from a commercial biomass steam gasification plant with two different qualities: extracted before and extracted after scrubbing with a rapeseed methyl ester gas scrubber. The performance of the WGS pilot plant regarding these two different gas qualities was investigated. For this reason, extensive chemical analyses were carried out. CO, CO2, CH4, N2, O2, C2H6, C2H4, and C2H2 and H2S, COS, and C4H4 S were measured. In addition, GCMS tar and NH3 analyses were performed. Furthermore, the catalyst's activity was observed by measuring the temperature profiles along the reactors of the water gas shift pilot plant. During the 200 h of operation with both product gas qualities, no catalyst deactivation could be observed. A CO conversion up to 93% as well as a GCMS tar reduction (about 28%) along the water gas shift pilot plant was obtained. Furthermore, a specific H2 production of 63 g H2 per kg biomass (dry and ash free) was reached with both product gas qualities. No significant performance difference could be observed.

Other papers | 2015

Performance of a water gas shift pilot plant processing tar-rich product gas from a commercial biomass steam gasification plant operating at partial load conditions

Kraussler M, Binder M, Hofbauer H. Performance of a water gas shift pilot plant processing tar-rich product gas from a commercial biomass steam gasification plant operating at partial load conditions. International Bioenergy Exhibition and Asian Bioenergy Conference 2015. October 2015, Shanghai, China.

Details
Other papers | 2015

Performance of a Water Gas Shift Unit Processing Product Gas from Biomass Steam Gasification

Kraussler M, Binder M, Fail S, Rauch R, Bosch K, Hackel M, Hofbauer H. Performance of a Water Gas Shift Unit Processing Product Gas from Biomass Steam Gasification. 23rd European Biomass Conference & Exhibition (oral presentation). June 2015, Vienna, Austria.

Details
Peer reviewed papers | 2015

Short term online corrosion measurements in biomass fired boilers. Part 1: Application of newly developed mass loss probe

Retschitzegger S, Gruber T, Brunner T, Obernberger I. Short term online corrosion measurements in biomass fired boilers. Part 1: Application of a newly developed mass loss probe. Fuel Process Technol 2015;137:148-156.

External Link Details
Peer reviewed papers | 2015

Simultaneous online determination of S, Cl, K, Na, Zn and Pb release from a single particle during biomass combustion Part 1: Experimental setup implementation and evaluation

Sommersacher P, Kienzl N, Brunner T, Obernberger I. Simultaneous online determination of S, Cl, K, Na, Zn and Pb release from a single particle during biomass combustion Part 1: Experimental setup implementation and evaluation. Energy and Fuels. 15 October 2015;29:6734-6746.

External Link Details

The interest in experimental data regarding thermal fuel decomposition as well as the release behavior of ash-forming elements of biomass fuels for modeling and simulation purposes is continuously increasing. On the basis of combustion experiments with lab-scale reactors and single-particle reactors, integral release data regarding ash-forming vapors can be obtained, whereby the release is calculated on the basis of analysis data of the fuel and the ash residues. At the moment, almost no time-resolved release data of ash-forming elements from single particles exist. Therefore, a single-particle reactor was designed, which has been coupled to an inductively coupled plasma mass spectrometer (ICP-MS). This reactor can be used for targeted experiments in a temperature range of 250–1050 °C under inert, reducing, and oxidizing conditions. With this reactor, it is possible to simultaneously determine the surface and center temperatures of a biomass particle, weight loss of the particle, and flue gas composition. The reactor has been coupled to an ICP-MS through a gas stream that is sufficiently diluted with Ar. First performance tests with pure salts (KCl, NaCl, (NH4)2SO4, ZnCl2, and PbCl2) proved that relevant volatile ash-forming elements can be detected with the ICP-MS. For a further validation of the received signals, combustion tests with Miscanthus pellets have been carried out, whereby the controlled interruption of the experiments has also been investigated. These tests prove that with this system the simultaneous time-resolved determination of S, Cl, K, Na, Zn, and Pb is possible whereby the Cl signal can only be used with restrictions. On the basis of the determined release of ash-forming elements for the entire combustion experiment, a quantification/calibration of the measured intensities has been carried out. The data gained from these tests will provide deeper insights into release processes as well as form a relevant basis for release model development.

Other papers | 2015

State of the art biomass gasification for CHP production – the Ulm plant

Kirnbauer F, Maierhans F, Kuba M, Hofbauer H. State of the art biomass gasification for CHP production – the Ulm plant. Regatec 2015. 7-8 May 2015, Barcelona, Spain.

External Link Details
Other Publications | 2015

Survey of modern pellet boilers in Austria and Germany - System design and customer satisfaction of residential installations

Büchner D, Schraube C, Carlon E, von Sonntag J, Schwarz M, Verma VK, Ortwein A. Survey of modern pellet boilers in Austria and Germany - System design and customer satisfaction of residential installations. Applied Energy;160: 390-403.

External Link Details

The variety of available technical building equipment leads to increasingly complex heating systems with various requirements for efficient operation. Furthermore, in existing buildings the heating system is often historically evolved and contains parts having different ages. Those systems have limited capacity to suit the requirements of replaced components. This paper investigates the operational behavior of small-scale pellet heating systems in Austria and Germany, considering installations in new buildings and boiler replacements in existing buildings and how they are influencing the customer satisfaction.

This investigation was carried out by means of a comprehensive survey for residential customers using pellet fired heating systems. More than 2500 questionnaires were distributed between 2011 and 2013 in Austria, Germany, Greece, Spain and the United Kingdom. In total 293 returned questionnaires were evaluated. The efficiency of the monitored heating systems was estimated using surveyed boiler parameters. Successively, the influence of different operational parameters on the boilers efficiency was evaluated with a statistical analysis, using Pearson correlation coefficient and Spearman correlation.

Results showed that the correct installation of the monitored pellet heating system is easier for new buildings compared to the replacement of old fossil boilers in existing buildings. Optimal operating conditions are characterized by less frequent ignitions and by higher operational loads. Pellet systems operated with a high efficiency in both building types, but for new buildings it is more likely to occur. More than 87% of the participating customers stated that they are highly satisfied with their pellet boiler.

Peer reviewed papers | 2015

The behavior of biomass and char particles in a dual fluidized bed gasification system

Kraft S, Kuba M, Hofbauer H. The behavior of biomass and char particles in a dual fluidized bed gasification system. Powder Technology 2018;338:887-897.

External Link Details
Biomass gasification in fluidized beds is a complex process in which particles occur in a wide range of size and density. In this paper, the mixing behavior of the char, biomass and bed material in a gasification reactor of a typical dual fluidized bed (DFB) system was investigated in a cold flow model. Experiments with ternary mixtures were performed in which the size and the density of the used particles were varied. For the experiments, a cold flow model was constructed with a full bed material recirculation loop, similar to DFB systems. Experiments revealed that at low fluidization velocities, the smaller char particles and biomass particles occur more preferentially in the bed material recirculation stream. If the fluidization velocities are increased, this tendency diminishes. Furthermore, the experiments showed that the mass fraction of biomass particles in the recirculation stream is always higher than that of the lighter char particles. It is also shown that the current design of the gasification reactor in DFB systems is not optimal. A way to overcome this issue in existing plants is presented.
Other papers | 2015

The role of 1H-indene in product gas of biomass gasification

Kuba M, Kirnbauer F, Hofbauer H. The role of 1H-indene in product gas of biomass gasification. International Bioenergy Exhibition and Asian Bioenergy Conference 2015. October 2015, Shanghai, China.

Details
Peer reviewed papers | 2015

The Role of Leak Air in a Double-Wall Chimney

Lichtenegger K, Hebenstreit B, Pointner C, Schmidl C, Höftberger E. The role of leak air in a double-wall chimney. Heat Mass Transfer. 2015;51(6):787-94.

External Link Details

In modern buildings with tight shells, often room-independent air supply is required for proper operation of biomass stoves. One possibility to arrange this supply is to use a double-wall chimney with flue gas leaving through the pipe and fresh air entering through the annular gap. A one-dimensional quasi-static model based on balance equations has been developed and compared with experimental data. Inclusion of leak air is crucial for reproduction of the experimental results. © 2014, Springer-Verlag Berlin Heidelberg.

Peer reviewed papers | 2015

Use of Hazelnut's Pruning to Produce Biochar by Gasifier Small Scale Plant

Colantoni A, Longo L, Evic N, Gallucci F, Delfanti L. Use of Hazelnut‟s Pruning to Produce Biochar by Gasifier Small Scale Plant. International Journal of Renewable Energy Research. 2015;5(3):873-878.

External Link Details

Biochar is the product of biomass pyrolysis and gasification. One of the possible application of this product is certainly in agronomic sector, as soil amendment. However biochar use in Italy is subordinated to insert this product in fertilizer list, which biochar could be commercialized with. The aim of this paper is to know the biochar from gasification process (using an Imbert downdraft prototype), in particular investigating its potentiality as soil amendment in terms of European and Italian regulations and in terms of physical and chemical characterizations.

Other papers | 2015

Validation of a Kinetic Model for the Catalyzed Water Gas Shift Reaction Applying a Fe/Cr Catalyst Processing Wood Gas from Biomass Steam Gasification

Kraussler M, Fail S, Plaza Quevedo A, Cortes Guerro JA, Rauch R, Hofbauer H. Validation of a Kinetic Model for the Catalyzed Water Gas Shift Reaction Applying a Fe/Cr Catalyst Processing Wood Gas from Biomass Steam Gasification. 23rd European Biomass Conference & Exhibition (Poster). June 2015, Vienna, Austria.

Details
Peer reviewed papers | 2015

Ventilation of Carbon Monoxide from a Biomass Pellet Storage Tank - A Study of the Effects of Variation of Temperature and Cross-Ventilation on the Efficiency of Natural Ventilation

Emhofer W, Lichtenegger K, Haslinger W, Hofbauer H, Schmutzer-Roseneder I, Aigenbauer S, et al. Ventilation of carbon monoxide from a biomass pellet storage tank - A study of the effects of variation of temperature and cross-ventilation on the efficiency of natural ventilation. Ann Occup Hyg. 2015;59(1):79-90.

External Link Details

Wood pellets have been reported to emit toxic gaseous emissions during transport and storage. Carbon monoxide (CO) emission, due to the high toxicity of the gas and the possibility of it being present at high levels, is the most imminent threat to be considered before entering a pellet storage facility. For small-scale (<30 tons storage capacity) residential pellet storage facilities, ventilation, preferably natural ventilation utilizing already existing openings, has become the most favored solution to overcome the problem of high CO concentrations. However, there is little knowledge on the ventilation rates that can be reached and thus on the effectiveness of such measures. The aim of the study was to investigate ventilation rates for a specific small-scale pellet storage system depending on characteristic temperature differences. Furthermore, the influence of the implementation of a chimney and the influence of cross-ventilation on the ventilation rates were investigated. The air exchange rates observed in the experiments ranged between close to zero and up to 8 m3h-1, depending largely on the existing temperature differences and the existence of cross-ventilation. The results demonstrate that implementing natural ventilation is a possible measure to enhance safety from CO emissions, but not one without limitations. © 2014 © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Peer reviewed papers | 2016

2250-h long term operation of a water gas shift pilot plant processing tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant

Kraussler M, Binder M, Hofbauer H. 2250-h long term operation of a water gas shift pilot plant processing tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant. International Journal of Hydrogen Energy. 27 April 2016;41(15): 6247-6258.

External Link Details
Other Publications | 2016

Air pollution reduction due to the adoption of high efficiency small scale pellet boilers characterized by low emissions

Chiesa M, Monteleone B, Venuta ML, Maffeis G, Greco S, Cherubini A, Schmidl C, Finco A, Gerosa G, Ballarin Denti A. Air pollution reduction due to the adoption of high efficiency small scale pellet boilers characterized by low emissions. Biomass and Bioenergy. 1 July 2016;90: 262-272.

External Link Details
Other papers | 2016

An investigation on the behavior of impurities over a water gas shift stage using biomass derived syngas for hydrogen production

Loipersböck J, Lenzi M, Rauch R, Hofbauer H. An investigation on the behavior of impurities over a water gas shift stage using biomass derived syngas for hydrogen production. iSGA 2016 - 5th International Symposium on Gasification and its Applications (invited lecture). November/December 2016, Busan, Korea.

Details
Other Publications | 2016

Analisi del ciclo di vita di caldaie a pellet di bassa potenza caratterizzate da alta efficienza e ridotte emissioni

Monteleone B, Chiesa M, Marzuoli R, Verma VK, Schwarz M, Carlon E, Schmidl C, Ballarin Denti A. Analisi del ciclo di vita di caldaie a pellet di bassa potenza caratterizzate da alta efficienza e ridotte emissioni. Agriforenergy. February 2016.

External Link Details
Peer reviewed papers | 2016

Analysis of optimization potential in commercial biomass gasification plants using process simulation

Wilk V, Hofbauer H. Analysis of optimization potential in commercial biomass gasification plants using process simulation. Fuel Processing Technology. 01 December 2016;141: 138-147.

Details
Peer reviewed papers | 2016

Apparent kinetics of the catalyzed water-gas shift reaction in synthetic wood gas

Plaza A, Fail S, Cortés JA, Föttinger K, Diaz N, Rauch R, Hofbauer H. Apparent kinetics of the catalyzed water-gas shift reaction in synthetic wood gas. Chemical Engineering Journal. 1 October 2016;301: 222-228.

External Link Details
Peer reviewed papers | 2016

Associated effects of storage and mechanical pre-treatments of microalgae biomass on biomethane yields in anaerobic digestion

Gruber-Brunhumer MR, Jerney J, Zohar E, Nussbaumer M, Hieger C, Bromberger P, Bochmann G, Jirsa F, Schagerl M, Obbard JP, Fuchs W, Drosg B. Associated effects of storage and mechanical pre-treatments of microalgae biomass on biomethane yields in anaerobic digestion. Biomass and Bioenergy. October 2016;93: 259-268.

External Link Details
Other Publications | 2016

beReal - Comparative assessment of EN standard test methods and new real-life test methods for biomass room heating appliances

Schmidl C, Reichert G, Schwabl M, Stressler H, Sturmlechner R, Haslinger W. beReal - Comparative assessment of EN standard test methods and new real-life test methods for biomass room heating appliances. 24th European Biomass Conference & Exhibition (poster). June 2016, Amsterdam, Netherlands.

Details
Other Publications | 2016

beReal - Development of a New Test Method for Firewood Roomheaters Reflecting Real Life Operation

Reichert G, Hartmann H, Haslinger W, Oehler H, Schmidl C, Schwabl M, Stressler H, Sturmlechner R, Woehler M. beReal - Development of a New Test Method for Firewood Roomheaters Reflecting Real Life Operation. 24th European Biomass Conference & Exhibition (poster). June 2016, Amsterdam, Netherlands.

Details
Peer reviewed papers | 2016

Biological biogas upgrading capacity of a hydrogenotrophic community in a trickle-bed reactor

Rachbauer L, Voitl G, Bochmann G, Fuchs W. Biological biogas upgrading capacity of a hydrogenotrophic community in a trickle-bed reactor. Applied Energy. 15 October 2016;180: 483-490.

External Link Details
Peer reviewed papers | 2016

Biomass-Based Heating and Hot Water Supply Systems for Prefabricated, High Energy Performance Houses: a Comparison of System Configurations and Control Strategies

Carlon E, Schwarz M, Prada A, Verma V, Baratieri M, Gasparella A, Schmidl C. Biomass-Based Heating and Hot Water Supply Systems for Prefabricated, High Energy Performance Houses: a Comparison of System Configurations and Control Strategies. 12th REHVA World Congress CLIMA 2016 (full paper review and oral presentation). 22 May 2016, Aalborg, Denmark.

Download PDF Details

Nowadays prefabricated houses are becoming increasingly popular, thanks to their low cost and high energy performance. Heating systems installed in these houses should be carefully designed and controlled, to ensure sufficient thermal comfort while maintaining low fuel consumptions. This study presents the simulation of different system configurations and control strategies for a pre-fabricated house, located in Lower Austria. The house is heated by a 6 kW pellet boiler directly connected to a floor heating system, in a configuration without buffer storage tank. Using the TRNSYS simulation suite, a coupled simulation of the house and its heating and hot water supply system was set up, calibrated and validated with reference to monitoring data. As monitoring data evidenced that the control strategy of the heating system is not ideal to maintain a comfortable indoor temperature during the whole day, two improved strategies were simulated over the heating season and evaluated in terms of thermal comfort, pellet consumption and boiler’s efficiency. Moreover, to better understand the influence of the system configuration, simulations have been repeated considering another heat distribution system (radiators instead of floor heating). Results show that the radiators’ network, if adequately controlled, reduces by 85% the total discomfort time. In addition, the pellet boiler mainly operates in load modulation regime, leading to lower pellet supply rates and therefore to lower pellet consumptions (18% less than floor heating). However, the lower operational loads and frequent ignitions result in a slightly lower efficiency of the pellet boiler (4% less than the configuration with floor heating.

Peer reviewed papers | 2016

Characterization of biochars produced from pyrolysis of pelletized agricultural residues

Colantoni A, Evic N, Lord R, Retschitzegger S, Proto A, Gallucci F, Monarca D. Characterization of biochars produced from pyrolysis of pelletized agricultural residues. Renewable and Sustainable Energy Reviews. 1 October 2016;64: 187-194.

External Link Details

Biochars produced from pelletized grape vine (GV) and sunflower husk (SFH) agricultural residues were studied by pyrolysis in a batch reactor at 400 and 500 °C. Chemical and physical evolution of the biomass under pyrolysis conditions was determined and the products were characterized, including the main gaseous organic components. Results showed a decrease in solid biochar yield with increasing temperature. Biochar is defined as a “porous carbonaceous solid” produced by thermochemical conversion of organic materials in an oxygen depleted atmosphere, which has physiochemical properties suitable for the safe and long-term storage of carbon in the environment and, potentially, soil improvement. The aim of this work is to improve the knowledge and acceptability of alternative use of the biochar gained from agro-forestry biomass residuals, such as grape vine and sunflower husks, by means of modern chemical and physical characterization tools.

Other papers | 2016

Cold flow modelling of char concentration in the recirculated bed material stream of a dual fluidized bed steam gasification system

Kraft S, Kirnbauer F, Hofbauer H. Cold flow modelling of char concentration in the recirculated bed material stream of a dual fluidized bed steam gasification system. Fluidization XV. 22-27 May 2016, Quebec, Canada.

External Link Details

The dual fluidized bed (DFB) steam gasification technology of biomass was developed at Vienna University of Technology and is well-established for transforming biomass into a product gas which can be used for further applications. The DFB steam gasification reactor consists of a gasification chamber (bubbling bed, fluidized with steam) and a combustion chamber (turbulent bed, fluidized with air). Biomass is fed into the gasification chamber and gets in contact with the bed material, typically Olivine, at about 840°C. The released volatiles leave the gasification reactor as product gas. A part of the solid residue, called char, flows with the bed material via a chute to the combustion chamber where it is burnt with air. The bed material is heated up, separated from the flue gas stream in a cyclone and flows back to the gasification reactor via a loop seal where it provides the heat for devolatilization and drying of the biomass. The movement of the char is crucial since a sufficient amount has to flow to the combustion chamber and burn to provide enough energy for bed material heat-up. Up to now little is known about the char concentration in the bed material recirculation stream (or short recirculation stream) and its influencing variables. Therefore, a cold flow model, operated with ambient air, was constructed to study the influence of various parameters on the char concentration in the recirculation stream. Bronze is used as bed material since is matches closest to the scaling criteria. The char is also scaled; polyethylene is used as model char.

The cold flow model, see Figure 1 for the flowsheet, consists of a “gasification chamber” which corresponds to the gasification chamber in the hot plant and is as well operated as a bubbling bed. Via a chute the recirculation stream moves to a rotary valve which enables to set a fixed recirculation rate and make it independent from the following pneumatic conveying. Then, gas and solids are separated in a cyclone and the recirculation stream finally flows back to the gasification chamber. After the loop seal samples are taken for investigation of the model char concentration in the recirculation stream. In the present study the influence of fluidization rate in the gasification chamber, bed material recirculation rate and model char mass in the system on the char concentration in the recirculation stream are investigated. It was found that the model char particles show a flotsam behavior. Higher fluidization rates increase the model char concentration in the recirculation stream because of better mixing, whereas the bed material recirculation rate has only little influence. Doubling and tripling the overall char mass in the system did not lead to a doubling or tripling model char concentration in the recirculation stream. The present observations are helping to better understand the ongoing phenomena inside of the dual fluidized bed gasification reactor and provide knowledge to further optimize it.

Peer reviewed papers | 2016

Dominating high temperature corrosion mechanism in low alloy steels in wood chips fired boilers

Gruber T, Retschitzegger S, Scharler R, Obernberger I. Dominating high temperature corrosion mechanism in low alloy steels in wood chips fired boilers. Energy and Fuels. 17 March 2016;30(3): 2385-2394.

External Link Details

Ash related problems such as slagging, fouling, and high temperature corrosion in biomass fired boilers are still insufficiently explored due to the complexity of the underlying processes. High temperature corrosion of low alloy steels like 13CrMo4-5 has already been investigated in plants firing chemically untreated wood chips. In this earlier work it has been suggested that the oxidation of the steel is the dominating mechanism in the material temperature range between 450 and 550 °C. Unfortunately the exponential dependence of the material degradation on the flue gas temperature also found within this work cannot be explained with the proposed corrosion mechanism. To determine the dominating corrosion mechanism, additionally test runs have been carried out in a specially designed drop tube reactor. To investigate the time-dependent corrosion behavior of 13CrMo4-5, a newly developed mass loss probe was applied under several constant parameter setups. In addition to these measurements, the time-dependent oxidation of 13CrMo4-5 under air was investigated in a muffle furnace. To gain relevant information regarding the corrosion mechanism prevailing, the deposits as well as the corrosion products have been examined subsequently to the test runs by means of scanning electron microscopy and energy dispersive X-ray analyses. With the experimental data gained it could be shown that the dominating corrosion mechanism strongly depends on the conditions prevailing (e.g., steel temperature, flue gas temperature, and velocity) and can either be the oxidation of the steel by gaseous O2 and H2O or a combination of oxidation and active Cl-induced oxidation.

Other Publications | 2016

Emission Reduction of Firewood Roomheaters by Optimization of Operating Conditions and Catalyst Integration

Reichert G, Stressler H, Schmidl C, Schwabl M, Sturmlechner R, Haslinger W. Emission Reduction of Firewood Roomheaters by Optimization of Operating Conditions and Catalyst Integration. 24th European Biomass Conference & Exhibition (oral presentation). June 2016, Amsterdam, Netherlands.

Details
Peer reviewed papers | 2016

Enhanced Separation of the Organic Fraction from Paper Mill Effluent for Energy Recovery

Stoyanova E, Bochmann G, Couperus A, Fuchs W. Enhanced Separation of the Organic Fraction from Paper Mill Effluent for Energy Recovery. Waste and Biomass Valorization. 1 October 2016;7(5): 1031-1039.

External Link Details
Peer reviewed papers | 2016

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

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

External Link Details

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

Peer reviewed papers | 2016

Hydrogen production within a polygeneration concept based on dual fluidized bed biomass steam gasification

Kraussler M, Binder M, Schindler P, Hofbauer H. Hydrogen production within a polygeneration concept based on dual fluidized bed biomass steam gasification. Biomass and Bioenergy. 24 December 2016;

External Link Details
Other papers | 2016

Hythane from biomass steam gasification as natural gas substitute in industrial applications

Kraussler M, Schindler P, Hofbauer H. Hythane from biomass steam gasification as natural gas substitute in industrial applications. Biorestec (poster). October 2016, Sitges, Spain.

Details
Peer reviewed papers | 2016

Impact of Na Promoter on Structural Properties and Catalytic Performance of CoNi/Al2O3 Nanocatalysts for the CO Hydrogenation Process: Fischer–Tropsch Technology

Nikparsa P, Mirzaei AA, Rauch R. Impact of Na Promoter on Structural Properties and Catalytic Performance of CoNi/Al2O3 Nanocatalysts for the CO Hydrogenation Process: Fischer–Tropsch Technology. Catalysis Letters. January 2016;146(1): 61-71.

External Link Details
Other papers | 2016

Improving the propanol yield of mixed alcohol synthesis based on wood gas derived from biomass steam gasification

Binder M, Rauch R, Hofbauer H. Improving the propanol yield of mixed alcohol synthesis based on wood gas derived from biomass steam gasification. iSGA 2016 - 5th International Symposium on Gasification and its Applications (invited lecture). November/December 2016, Busan, Korea.

Details
Peer reviewed papers | 2016

Influence of firebed temperature on particle emissions in a residential wood pellet boiler

Gehrig M, Jäger D, Pelz SK, Weissinger A, Groll A, Thorwarth H, Haslinger W. Influence of firebed temperature on particle emissions in a residential wood pellet boiler. Atmospheric Environment. July 2016;136: 61-67.

External Link Details

The crucial point in inorganic particle formation from biomass combustion is the temperature-dependent release of inorganic compounds, especially potassium (K). Currently, common wood fuels comprise of a comparatively low amount of K, but the increased usage of wood energy requires new feedstocks in the future. Potentially new feedstocks, such as short rotation coppice (SRC), fuels from agriculture (e.g., straw), or wood from broad-leafed trees of low rotation, contain usually high ash contents and/or high K concentrations. Apparently, these feedstocks will cause increased inorganic particle emissions from biomass combustion processes. The principle of a decreased firebed temperature as a primary measure aiming at a retention of K in the ashes of the firebed is a common approach for particle emission reduction and was investigated in several previous studies. The present study describes the usage of an ash-rich fuel from SRC pellets made from willow in a residential pellet boiler modified with an unique prototype of direct water-based firebed cooling. This test setup enables the study of the isolated impact of decreased firebed temperatures and its influence on the combustion process and emissions as well. A statistically significant effect of the firebed cooling on temperatures below the burner plate as on gaseous HCl and SO2 was found. The high ash content of the used fuel limited the effectiveness of the applied direct firebed cooling in residential biomass combustion. The accumulation of a thick and thermal insulating ash layer above the burner plate decreased the heat transfer, limited the cooling efficiency, and revealed deviations from the expected particle formation process.

Other Publications | 2016

Influence of leak tightness and heat storage capacity of biomass room heating appliances on thermal efficiency

Sturmlechner R, Reichert G, Stressler H, Aigenbauer S, Schmidl C, Schwabl M, Haslinger W. Influence of leak tightness and heat storage capacity of biomass room heating appliances on thermal efficiency. 24th European Biomass Conference & Exhibition (poster). June 2016, Amsterdam, Netherlands.

Details
Peer reviewed papers | 2016

Investigation of real life operation of biomass room heating appliances – results of a European survey

Wöhler M, Andersen JS, Becker G, Persson H, Reichert G, Schön C, Schmidl C, Jaeger D, Pelz SK. Investigation of real life operation of biomass room heating appliances – results of a European survey. Applied Energy. 1 May 2016;169: 240-249.

External Link Details
Peer reviewed papers | 2016

Investigation of User Behavior and Assessment of Typical Operation Mode for Different Types of Firewood Room Heating Appliances in Austria

Reichert G, Schmidl C, Haslinger W, Schwabl M, Moser W, Aigenbauer S, Wöhler M, Hochenauer C. Investigation of User Behavior and Assessment of Typical Operation Mode for Different Types of Firewood Room Heating Appliances in Austria. Renewable Energy. August 2016;93: 245-254.

External Link Details

Firewood heaters like firewood roomheaters, tiled stoves and residential biomass cookers are commonly used for supplying the residences with renewable heat. However, these kinds of appliances were identified as responsible for relevant amounts of gaseous CO and OGC as well as particulate emissions causing negative health effects. Beside technological reasons, the operating conditions and the user behavior are essential reasons for increased emissions, especially in real life operation.

Therefore, this study aimed at an investigation and assessment of typical real life user behavior by a survey. Based on the findings effective and customer friendly technological and non-technological optimization approaches for a better and more environmental friendly real life performance were defined.

The results of the study showed principally similar user behavior of all considered types of appliances regarding most relevant operation characteristics, i.e. kind, properties and amount of used fuels, ignition procedure and air valve settings. Most effective non-technological optimization approaches were found for an enhancement of external training arrangements and the development of user friendly manuals that aimed mainly at an improvement of the ignition procedure from bottom–up to top–down ignition method. The use of devices with an automatically controlled combustion air supply was identified as promising technological measure.

Other papers | 2016

Investigations of a dual fluidized bed steam gasification plant by means of computation particle fluid dynamics

Kraft S, Kirnbauer F, Hofbauer H. Investigations of a dual fluidized bed steam gasification plant by means of computation particle fluid dynamics. 24th European Biomass Conference & Exhibition (oral presentation). June 2016, Amsterdam, Netherlands.

Details
Peer reviewed papers | 2016

Mechanism of Layer Formation on Olivine Bed Particles in Industrial-Scale Dual Fluid Bed Gasification of Wood

Kuba M, He H, Kirnbauer F, Skoglund N, Boström D, Öhman M, Hofbauer H. Mechanism of Layer Formation on Olivine Bed Particles in Industrial-Scale Dual Fluid Bed Gasification of Wood. Energy & Fuels. 15 September 2016;30(9): 7410-7418.

External Link Details

Utilization of biomass as feedstock in dual fluidized bed steam gasification is a promising technology for the substitution of fossil energy carriers. Experience from industrial scale power plants showed an alteration of the olivine bed material due to interaction with biomass ash components. This change results mainly in the formation of Ca-rich layers on the bed particles. In this paper, a mechanism for layer formation is proposed and compared to the better understood mechanism for layer formation on quartz bed particles. Olivine bed material was sampled at an industrial scale power plant before the start of operation and at pre-defined times after the operation had commenced. Therefore, time dependent layer formation in industrial-scale conditions could be investigated. The proposed mechanism suggests that the interaction between wood biomass ash and olivine bed particles is based on a solid-solid substitution reaction, where Ca2+ is incorporated into the crystal structure. As a consequence Fe2+/3+ and Mg2+ ions are expelled as oxides. This substitution results in the formation of cracks in the particle layer due to a volume expansion in the crystal structure once Ca2+ is incorporated. The results of this work are compared to relevant published results including those related to quartz bed particles.
 

Peer reviewed papers | 2016

Methodological approaches for fractionation and speciation to estimate trace element bioavailability in engineered anaerobic digestion ecosystems: An overview

van Hullebusch ED, Guibaud G, Simon S, Lenz M, Yekta SS, Fermoso FG, Jain R, Duester L, Roussel J, Guillon E, Skyllberg U, Almeida CMR, Pechaud Y, Garuti M, Frunzo L, Esposito G, Carliell-Marquet C, Ortner M, Collins G. Methodological approaches for fractionation and speciation to estimate trace element bioavailability in engineered anaerobic digestion ecosystems: An overview. Critical Reviews in Environmental Science and Technology. 17 August 2016;46(16): 1324-1366.

External Link Details
Conference presentations and posters | 2016

Mixed alcohol synthesis based on wood gas derived from dual fluidized bed biomass steam gasification - applying a rapeseed oil methyl ester gas scrubber for gas conditioning

Binder, M., Rauch, R., Hofbauer, H., 2016, "Mixed alcohol synthesis based on wood gas derived from dual fluidized bed biomass steam gasification - applying a rapeseed oil methyl ester gas scrubber for gas conditioning", poster presentation at BioResTec2016 - 1st International Conference on Bioresource Technology for Bioenergy, Bioproducts & Environmental Sustainability , 23 - 26 October 2016, Sitges, Spain.

Details
Peer reviewed papers | 2016

Modification of Co/Al2O3 Fischer–Tropsch Nanocatalysts by Adding Ni: A Kinetic Approach

Nikparsa P, Mirzaei AA, Rauch R. Modification of Co/Al2O3 Fischer–Tropsch Nanocatalysts by Adding Ni: A Kinetic Approach. International Journal of Chemical Kinetics. 1 March 2016;48(3): 131-142.

External Link Details
Other Publications | 2016

On site monitoring and dynamic simulation of a low energy house heated by a pellet boiler

Carlon E, Schwarz M, Prada A, Golicza L, Verma V, Baratieri M, Gasparella A, Haslinger W, Schmidl C. On site monitoring and dynamic simulation of a low energy house heated by a pellet boiler. 15 March 2016;116: 296-306.

External Link Details

Prefabricated low energy houses are becoming increasingly popular thanks to their low cost and high energy performance. Heating systems installed in these houses should be optimally designed and controlled, to ensure thermal comfort for the whole heating season.

This study presents the on-site monitoring and dynamic simulation of a low energy house heated by a pellet boiler via a floor heating system. The house combines a lightweight envelope, a heat distribution system with a high thermal inertia and a biomass-based heat supply. The one-year monitoring campaign allowed to closely investigate the system's response to the heat demand. Moreover, a coupled simulation of the house and its heating and hot water supply system was set-up, calibrated, and validated against measured indoor temperature profiles and energy consumptions. Root mean square deviations between simulated and measured indoor temperature were in the range 0.4–0.8 K, while simulated energy consumptions fulfilled the criteria of the ASHRAE 14-2002 Guideline. As monitoring data evidenced the importance of better managing the high thermal inertia of the floor heating system, two improved control strategies were tested in the simulation environment and evaluated in terms of thermal comfort, pellet consumption and efficiency of the pellet boiler.

Other papers | 2016

Phase Sewparation Behaviour of FAME and Water

Bardolf R, Thoma C, Bosch K, Rauch R, Hofbauer H. Phase Sewparation Behaviour of FAME and Water. 24th European Biomass Conference & Exhibition (poster). June 2016, Amsterdam, Netherlands.

Details
Other papers | 2016

Possibility of industrial scale BioH2 production from product gas in existing dual fluidized bed biomass gasification plant

Jovanovic A, Stamenkovic M, Nenning L, Rauch R. Possibility of industrial scale BioH2 production from product gas in existing dual fluidized bed biomass gasification plant. 4th International Symposium on Environment Friendly Energies and Applications, EFEA 2016. 18 November 2016, Belgrade, Serbia.

External Link Details

Conceptual solution of production of pure renewable hydrogen from wood gas or product derived from the commercial biomass steam gasification plant Güssing, Austria was carried out. The proposed process of product gas upgrading consisted of tree basic operations: (I) catalyzed water-gas shift (WGS) reaction, (II) gas drying and cleaning in a wet scrubber and (III) hydrogen purification by pressure swing adsorption. The tail gas or adsorbate can be used like fuel for gas engine for electrical energy production or like a boiler fuel for hot water-heat production.

Other papers | 2016

Progress in hydrogen production from product gas generated by dual fluidized bed biomass steam gasification

Kraussler M, Hofbauer H. Progress in hydrogen production from product gas generated by dual fluidized bed biomass steam gasification. 24th European Biomass Conference & Exhibition (oral presentation). June 2016, Amsterdam, Netherlands.

Details
Other Publications | 2016

Progress in Mixed Alcohol Synthesis - Based on Wood Gas Derived from Dual Fluidized Bed Biomass Steam Gasification

Binder, M., Weber, G., Rauch, R., Hofbauer, H.: Progress in Mixed Alcohol Synthesis - Based on Wood Gas Derived from Dual Fluidized Bed Biomass Steam Gasification. Poster presentation at CASCATBEL workshop 2016, 18 - 20 May 2016, Porto Carras, Greece.

Details
Peer reviewed papers | 2016

Short term online corrosion measurements in biomass fired boilers. Part 2: Investigation of the corrosion behavior of three selected superheater steels for two biomass fuels

Retschitzegger, S., Gruber, T., Brunner, T., Obernberger, I. Short term online corrosion measurements in biomass fired boilers. Part 2: Investigation of the corrosion behavior of three selected superheater steels for two biomass fuels. Fuel Processing Technology. Volume 142, February 2016, Pages 59-70.

External Link Details

The high temperature corrosion behavior of the boiler steels 13CrMo4-5 (1.7335), P91 (1.4903) and 1.4541 has been investigated during short-term test runs (~ 500 h) at a biomass fired grate furnace combined with a drop tube. For the test runs performed with 13CrMo4-5 and P91 chemically untreated wood chips have been used as fuel, whereas waste wood has been used for test runs with P91 and 1.4541. Online corrosion probes and a mass loss probe have been used applying a methodology developed in a previous study to correct for a measurement error occurring during short-term measurements with online corrosion probes (mass loss correction). Furthermore, deposit probe measurements have been performed to evaluate the deposit build-up rate and the chemical composition of deposits. SEM/EDX analyses of the corrosion probes have been performed subsequently to the test runs to gain information regarding the chemical composition and structure of the deposits as well as the corrosion layers.

The furnace has been operated at constant load to ensure constant combustion conditions. The flue gas temperature at the probes has been varied between 740 and 900 °C and the probe surface temperature has been varied between 400 and 560 °C in order to determine their influence on the corrosion rate.

General trends determined by the variation of these temperatures were similar for all boiler steels: the corrosion rate increased with increasing flue gas temperature and also with increasing probe surface temperature. For chemically untreated wood chips combustion at low flue gas temperatures (740 °C) the corrosion rates were comparable for 13CrMo4-5 and P91 at all probe surface temperatures. However, at flue gas temperatures of 800 °C and higher P91 showed better corrosion resistance than 13CrMo4-5. For waste wood combustion 1.4541 generally showed a better corrosion resistance than P91.

The mass loss correction of the measurement error occurring in the initial phase resulted in different errors of 55% for 13CrMo4-5 and 32% for P91 for chemically untreated wood chips. For waste wood the mass loss correction resulted in errors of 55% for P91 and 77% for 1.4541. The results from the mass loss determination for the waste wood test runs scattered stronger compared to the wood chips test runs. Therefore, the fits were not that accurate and the error margin was higher. However, the results outline that the mass loss correction is relevant in order to achieve a meaningful comparison of different short-term test runs using online corrosion probes.

Peer reviewed papers | 2016

Simultaneous Online Determination of S, Cl, K, Na, Zn, and Pb Release from a Single Particle during Biomass Combustion. Part 2: Results from Test Runs with Spruce and Straw Pellets

Sommersacher P, Kienzl N, Brunner T, Obernberger I. Simultaneous Online Determination of S, Cl, K, Na, Zn, and Pb Release from a Single Particle during Biomass Combustion. Part 2: Results from Test Runs with Spruce and Straw Pellets. Energy and Fuels. 21 April 2016;30(4): 3428-3440.

External Link Details

To gain better insight into inorganic element release processes, test runs with a specially designed single particle reactor connected with an inductively coupled plasma mass spectrometer (ICP-MS) have been performed. Relevant combustion related parameters such as mass loss during thermal degradation, temperature development of the particle (surface and center), and composition of released gases were recorded. By coupling the reactor to an ICP-MS, time-resolved release profiles of relevant aerosol forming elements (S, Cl, K, Na, Zn, and Pb) were determined. Targeted and controlled interruptions of the experiments (quenching) after a certain time were performed to validate reactor performance and reliability of the measurements. Test runs with softwood and straw pellets (8 mm in diameter and about 20 mm in length) were performed at reactor temperatures of 700, 850, and 1000 °C under oxidizing conditions (5.6 or 4.2 vol % O2). These test runs have revealed that the release ratios of volatile and semivolatile ash forming elements (S, Cl, K, Na, Zn, and Pb) generally increase as reactor temperatures rise. Moreover, regarding straw, higher Si and Al contents influence the release behavior of K, Na, Zn, and Pb. For K, existing release mechanisms proposed in the literature have been confirmed, and for Na it has been suggested that release mechanisms similar to K prevail. Especially during the starting phase of the experiment, a distinct temperature gradient exists from the surface to the center of the particle. Thus, different conversion phases occur in parallel in different layers of the particle, which has to be considered during the interpretation of the time-resolved release profiles of the main inorganic elements. Furthermore, transport limitations due to the occurrence of molten phases (especially for straw at reactor temperatures of 1000 °C) were obvious and could be directly derived from the online recorded release profiles. The targeted interruption of the ongoing decomposition process (quenching) provided an indication of the validity of the release profiles for S, K, Na, Zn, and Pb. Additionally, these experiments delivered valuable information regarding possible release mechanisms.

Peer reviewed papers | 2016

The influence of oxygen availability on off-gassing rates of emissions from stored wood pellets

Meier F, Sedlmayer I, Emhofer W, Wopienka E, Schmidl C, Haslinger W, Hofbauer H. The influence of oxygen availability on off-gassing rates of emissions from stored wood pellets. Energy & Fuels. 18 February 2016;30(2): 1006-1012.

External Link Details

The phenomenon of off-gassing from wood pellets during storage has been the cause of several, in some cases fatal, accidents due to toxic atmospheres in storages. To optimize safety measures the nature of the responsible processes needs to be clarified. In this study the impact of O2 availability, which is a decisive factor for the presumed oxidation of fatty acids, is pointed out. Off-gassing rates of CO, CO2, VOC, and CH4 of pellets at relatively constant O2 levels of approximately 35%, 20%, and <1% over a period of 20 d at approximately 295 K were investigated. For this purpose 7 kg of spruce pellets was stored under simulated ventilation of the atmosphere in a 31 L tank. Gas concentrations were determined every 24 h by GC-FID/TCD. Compared to the mean emission rates at 35% O2 of CO (0.22 mg kg–1pelletsd.b. in 24 h) and CO2 (0.76 mg kg–1pelletsd.b. in 24 h) the lowest O2 concentration of <1% resulted in a significant reduction of off-gassing rates of 40% for both gases. In contrast the release rates of VOCs and also CH4 decreased with the higher O2 concentration (0.035 to 0.025 mg kg–1pelletsd.b. in 24 h; 0.0085 to 0.0061 mg kg–1pelletsd.b. in 24 h), presumably, because of increased onward reactions to CO and CO2. Since off-gassing was not prevented by the lack of O2 (<1% O2-trial) it is assumed that the O2 required for the reactions originated from the biomass itself. During the storage of pellets at 20% O2, emission rates of CO (0.18 mg kg–1pelletsd.b. in 24 h) and CO2 (0.79 mg kg–1pelletsd.b. in 24 h) at the start decreased by more than 20% and those for VOCs (0.032 mg kg–1pelletsd.b. in 24 h) by almost 30% after 3 weeks. It can be assumed that in ventilated storages the reactivity and thus a potential risk from off-gases from wood pellets decreases considerably in only a few weeks. The effects of aging, in terms of declining reactivity at relatively constant tank conditions, on off-gassing rates could be clarified for the first time. A realistic development of the decline of reactivity of the material itself could be determined.

Peer reviewed papers | 2016

The interplay of self-reflection, social interaction and random events in the dynamics of opinion flow in two-party democracies

Lichtenegger K, Hadzibeganovic T. The interplay of self-reflection, social interaction and random events in the dynamics of opinion flow in two-party democracies. International Journal of Modern Physics C. 1 May 2016;27(5).

External Link Details
We propose a continuous process opinion formation model to study the dynamics of a multi-level relationship between voters, political parties, and facts in two-party democratic elections. In our model, opinions can take any real value between two extremes and an unaligned, moderate opinion state without a preference. Starting with a random opinion configuration, individual voter opinions evolve and change over time due to self-reflection, inter-personal communication, external media influence, and noise. Parties are influenced by their own ideologies, facts, and voters’ opinions. Elections are held periodically and the party that is closer in opinion to the majority of voters forms the new government. The government policy is then expected to be in proximity to the voter opinions and the policies of the currently ruling political party. We analyze the tension of opinions as a measure of how dramatically opinions can disagree within a given sample of voters and the success of the government and parties as the degree of coincidence between the policies and facts. Our model generates realistic quasi-periodic alternations between incumbents and challengers that are typical for two-party systems. Moreover, our model shows that relative to other voters’ strategies, conscious voting can lead to more successful governments of not only fact-oriented but also pragmatic and balanced political parties, irrespective of the strategies of the competing opposition parties. In addition, our simulations uncover several interesting features including less victories for strictly ideological or fact-oriented parties unless they include some aspects of populism or pragmatism. In this sense, our model can also describe situations where election outcomes are not necessarily based on votes for the current programs of competing parties and their placement on relevant issues, but instead result from voters’ dissatisfaction with the previous government and the votes against it.


Read More: http://www.worldscientific.com/doi/abs/10.1142/S0129183116500650
Peer reviewed papers | 2016

Thermal Stability of Bed Particle Layers on Naturally Occurring Minerals from Dual Fluid Bed Gasification of Woody Biomass

Kuba M, He H, Kirnbauer F, Skoglund N, Boström D, Öhman M, Hofbauer H. Thermal Stability of Bed Particle Layers on Naturally Occurring Minerals from Dual Fluid Bed Gasification of Woody Biomass. Energy & Fuels. 20 October 2016;30(10): 8277-8285.

External Link Details

The use of biomass as feedstock for gasification is a promising way of producing not only electricity and heat but also fuels for transportation and synthetic chemicals. Dual fluid bed steam gasification has proven to be suitable for this purpose. Olivine is currently the most commonly used bed material in this process due to its good agglomeration performance and its catalytic effectiveness in the reduction of biomass tars. However as olivine contains heavy metals such as nickel and chromium no further usage of the nutrient-rich ash is possible and additional operational costs arise due to necessary disposal of the ash fractions. This paper investigates possible alternative bed materials and their suitability for dual fluid bed gasification systems focusing on the behavior of the naturally occurring minerals olivine, quartz and K-feldspar in terms of agglomeration and fractionation at typical temperatures. To this end samples of bed materials with layer formation on their particles were collected at the industrial biomass combined heat and power (CHP) plant in Senden, Germany, which uses olivine as the bed material and woody biomass as feedstock. The low cost logging residue feedstock contains mineral impurities such as quartz and K-feldspar which become mixed into the fluidized bed during operation. Using experimental analysis and thermochemical it was found that the layers on olivine and K-feldspar showed a significantly lower agglomeration tendency than quartz. Significant fractionation of particles or their layers could be detected for olivine and quartz, whereas K-feldspar layers were characterized by a higher stability. High catalytic activity is predicted for all three minerals once Ca-rich particle layers are fully developed. However quartz may be less active during the build-up of the layers due to lower amounts of Ca in the initial layer formation.
 

Filter

Contact Us

We invite you to contact our office under office@best-research.eu or a member of our personnel directly from this website. Fast and simple.

To Our Team Page