Publications

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.

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Peer reviewed papers | 2017

A hybrid of winddiesel technology with biomass-based Fischer-Tropsch synthesis

Nikparsa P, Rauch R, Mirzaei AA. A hybrid of winddiesel technology with biomass-based Fischer-Tropsch synthesis. Monatshefte für Chemie. 10 July 2017;1-10.

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The syngas mixture produced from biomass (bio-syngas) is characterized by a H2/CO molar ratio of 1.5 in this work, which is different from that of traditional syngas ratio of 2. Therefore a hybrid of winddiesel technology with bio-syngas conversion by Fischer–Tropsch synthesis (WD-FT) on a cobalt based catalyst was investigated, for the first time, using a slurry reactor. The result from feeding this technology is compared with the direct converting biomass derived synthetic gas to fuels via Fischer–Tropsch synthesis (BS-FT). Experiments were performed at different syngas composition (variation of H2/CO ratio), keeping the other parameters (temperature 230 °C; gas flow 5 Nm³/h, pressure 20 bar) constant. Comparison of the WD-FT with the BS-FT synthesis results displayed mass fraction of light hydrocarbons and higher catalytic stability and activity after 500 h. The olefin structures for the different product distributions, obtained from different reactions, are determined by ¹H NMR spectroscopy. Negligible amounts of iso-α-olefins were detected in the product of the WD-FT reaction. In the case of the alpha value, a slight change was observed between 0.93 and 0.92 for the BS-FT and WD-FT reaction.
 

Peer reviewed papers | 2020

A novel production route and process optimization of biomass-derived paraffin wax for pharmaceutical application

Gruber H, Lindner L, Arlt S, Reichhold A, Rauch R, Weber G, Trimbach J, Hofbauer H. A novel production route and process optimization of biomass-derived paraffin wax for pharmaceutical application. Journal of Cleaner Production. 2020;275:124135

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The Biomass to Liquid (BtL) Fischer-Tropsch (FT) route converts lignocellulosic feedstock to renewable hydrocarbons. This, paper shows a novel production route for biomass-derived synthetic paraffin wax via gasification of lignocellulosic feedstock, Fischer-Tropsch synthesis (FTS) and hydrofining. The Fischer-Tropsch wax was fractionated, refined and analyzed with respect to compliance to commercial standards. The fractioned paraffin waxes were hydrofined using a commercial sulfide NiMo–Al2O3 catalyst and a trickle bed reactor. A parametric variation was performed to optimize the hydrofining process. It was shown that the produced medium-melt paraffin wax could fulfill the requirements for “Paraffinum solidum” defined by the European Pharmacopoeia (Ph. Eur). The high-melt wax fraction showed potential to be used as food packaging additive. Furthermore, the renewable wax was analyzed regarding PAH content and it was shown that the hydrofined wax was quasi-PAH-free.

Peer reviewed papers | 2021

A review on bed material particle layer formation and its positive influence on the performance of thermo-chemical biomass conversion in fluidized beds

Kuba M, Skoglund N, Öhman M, Hofbauer H. A review on bed material particle layer formation and its positive influence on the performance of thermo-chemical biomass conversion in fluidized beds.Fuel.2021.291:120214. https://doi.org/10.1016/j.fuel.2021.120214

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Bed material particle layer formation plays a significant role in thermo-chemical conversion of biomass. The interaction between biomass ash and bed material in fluidized bed conversion processes has been described for a variety of different applications and spans from fundamental research of formation mechanisms to effects of this layer formation on long-term operation in industrial-scale. This review describes the current state of the research regarding the mechanisms underlying layer formation and the positive influence of bed material particle layer formation on the operation of thermo-chemical conversion processes. Thus, the main focus lies on its effect on the catalytic activity towards gasification reactions and the impact on oxygen transport in chemical looping combustion. The review focuses on the most commonly investigated bed materials, such as quartz, feldspar or olivine. While the most relevant results for both the underlying mechanisms and the subsequently observed effects on the operation are presented and discussed, knowledge gaps where further research is necessary are identified and described.

Peer reviewed papers | 2017

An experimental approach aiming the production of a gas mixture composed of hydrogen and methane from biomass as natural gas substitute in industrial applications

Kraussler M, Schindler P, Hofbauer H. An experimental approach aiming the production of a gas mixture composed of hydrogen and methane from biomass as natural gas substitute in industrial applications. Bioresource Technology. August 2017;237: 39-46.

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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.

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Other papers | 2017

An investigation on the behaviour of nitrogen based impurities over a water gas shift stage and a biodiesel scrubber

Loipersböck J, Rauch R, Hofbauer H. An investigation on the behaviour of nitrogen based impurities over a water gas shift stage and a biodiesel scrubber. 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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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.

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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.

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Peer reviewed papers | 2017

Apparent kinetics of the water-gas-shift reaction in biomass gasification using ash-layered olivine as catalyst.

Krycaa J, Priščák J, Łojewskac J, Kuba M, Hofbauer H. Apparent kinetics of the water-gas-shift reaction in biomass gasification using ash-layered olivine as catalyst. Chemical Engineering Journal. 2018, 346: 113-119.

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Substitution of fossil fuels for production of electricity, heat, fuels for transportation and chemicals can be realized using biomass steam gasification in a dual fluidized bed (DFB).

Interaction between biomass ash and bed material in a fluidized bed leads to transformation of the bed particle due to enrichment of components from the biomass ash resulting in the development of ash layers on the bed particle surface. These ash-rich particle layers enhance the catalytic activity of the bed material regarding the water-gas-shift reaction and the reduction of tars.

The water-gas-shift reaction at conditions typical for dual fluidized bed biomass gasification at a temperature of 870 °C was investigated. Diffusion and heat transfer limitations were minimized using a lab-scale experimental set-up consisting of a gas mixing section and a quartz glass reactor in which the catalyst is investigated.

 

 

 

Conference presentations and posters | 2019

Aqueous phase reforming of Fischer-Tropsch water fraction

Zoppi G, Pipitone G, Gruber H, Weber G, Reichhold A, Pirone R, Bensaid S. Aqueous phase reforming of Fischer-Tropsch water fraction. ICPS 2019.

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Peer reviewed papers | 2020

Aqueous phase reforming of pilot-scale Fischer-Tropsch water effluent for sustainable hydrogen production

Zoppi G, Pipitone G, Gruber H, Weber G, Reichhold A, Pirone R, Bensaid S. Aqueous phase reforming of pilot-scale Fischer-Tropsch water effluent for sustainable hydrogen production. Catalysis Today.2020.

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Fischer-Tropsch (FT) synthesis produces an aqueous stream containing light oxygenates as major by-product. The low carbon concentration of the organics makes its thermal recovery unprofitable. Thus, novel processes are needed to utilize this waste carbon content. In this work, the aqueous phase reforming of the wastewater obtained from a 15 kWth Fischer-Tropsch plant was explored as a promising process to produce hydrogen at mild temperatures. The FT product water was firstly characterized and afterward subjected to the reforming at different reaction temperatures and time, using a platinum catalyst supported on activated carbon. It was observed that, besides activity, the selectivity towards hydrogen was favored at higher temperatures; equally, increasing the reaction time allowed to obtain the total conversion of most molecules found in the solution, without decreasing the selectivity and reaching a plateau at 4 hours in the hydrogen productivity. In order to get more insights into the reaction mechanism and product distribution derived from the APR of FT product water, several tests were performed with single compounds, finding characteristic features. The importance of the position of the hydroxyl group in the molecule structure was highlighted, with secondary alcohols more prone to dehydrogenation pathways compared to primary alcohols. Moreover, no interference among the substrates was reported despite the mixture is constituted by several molecules: in fact, the results obtained with the real FT product water were analogous to the linear combination of the single compound tests. Finally, the reuse of the catalyst showed no appreciable deactivation phenomena.

Other papers | 2017

Ash and bed material research in dual fluidized bed gasification of biomass in lab- and industrial-scale

Kuba M, Hofbauer H. Ash and bed material research in dual fluidized bed gasification of biomass in lab- and industrial-scale. 25th European Biomass Conference & Exhibition (oral presentation). June 2017, Stockholm, Sweden.

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Peer reviewed papers | 2022

Ash transformation during single-pellet gasification of sewage sludge and mixtures with agricultural residues with a focus on phosphorus

Hannl TK, Häggström G, Hedayati A, Skoglund N, Kuba M, Marcus Öhman. Ash transformation during single-pellet gasification of sewage sludge and mixtures with agricultural residues with a focus on phosphorus. Fuel Processing Technology. March 2022.227:107102.

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The recovery of phosphorus (P) from sewage sludge ashes has been the focus of recent research due to the initiatives for the use of biogenic resources and resource recovery. This study investigates the ash transformation chemistry of P in sewage sludge ash during the co-gasification with the K-Si- and K-rich agricultural residues wheat straw and sunflower husks, respectively, at temperatures relevant for fluidized bed technology, namely 800 °C and 950 °C. The residual ash was analyzed by ICP­AES, SEM/EDS, and XRD, and the results were compared to results of thermochemical equilibrium calculations. More than 90% of P and K in the fuels were retained in the residual ash fraction, and significant interaction phenomena occurred between the P-rich sewage sludge and the K-rich ash fractions. Around 45–65% of P was incorporated in crystalline K-bearing phosphates, i.e., K-whitlockite and CaKPO4, in the residual ashes with 85–90 wt% agricultural residue in the fuel mixture. In residual ashes of sewage sludge and mixtures with 60–70 wt% agricultural residue, P was mainly found in Ca(Mg,Fe)-whitlockites and AlPO4. Up to about 40% of P was in amorphous or unidentified phases. The results show that gasification provides a potential for the formation of K-bearing phosphates similar to combustion processes.

Peer reviewed papers | 2022

Assessment of measurement methods to characterize the producer gas from biomass gasification with steam in a fluidized bed

Anca-Couce A, von Berg L, Pongratz G, Scharler R, Hochenauer C, Geusebroek M, Kuipers J, Vilela CM, Kraia T, Panopoulos K, Funcia I, Dieguez-Alonso A, Almuina-Villar H, Tsiotsias T, Kienzl N, Martini S. Assessment of measurement methods to characterize the producer gas from biomass gasification with steam in a fluidized bed. Biomass and Bioenergy 2022.163:106527

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Measuring the producer gas from biomass gasification is very challenging and the use of several methods is required to achieve a complete characterization. Various techniques are available for these measurements, offering very different affordability or time demand requirements and the reliability of these techniques is often unknown. In this work an assessment of commonly employed measuring methods is conducted with a round robin. The main permanent gases, light hydrocarbons, tars, sulfur and nitrogen compounds were measured by several partners employing a producer gas obtained from fluidized bed gasification of wood and miscanthus with steam. Online and offline methods were used for this purpose and their accuracy, repeatability and reproducibility are here discussed. The results demonstrate the reliability of gas chromatography for measuring the main permanent gases, light hydrocarbons, benzene and H2S, validating the obtained results with other methods. An online method could also measure NH3 with a reasonable accuracy, but deviations were present for compounds at even lower concentrations. Regarding tar sampling and analysis, the main source of variability in the results was the analysis of the liquid samples, especially for heavier compounds. The presented work pointed out the need for a complementary use of several techniques to achieve a complete characterization of the producer gas from biomass gasification, and the suitability of certain online techniques as well as their limitations.

Peer reviewed papers | 2024

Bed material performance of quartz, natural K-feldspar, and olivine in bubbling fluidized bed combustion of barley straw

Bozaghian Bäckman M, Rebbling A, Kuba M, Larsson SH, Skoglund N. Bed material performance of quartz, natural K-feldspar, and olivine in bubbling fluidized bed combustion of barley straw. Fuel. 15 May 2024.364:130788.

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The present study investigates how three different silicate-based bed materials behave in bubbling fluidized bed combustion of a model agricultural residue with respect to ash composition, namely barley straw. Quartz, natural K-feldspar, and olivine were all used in combustion at 700 °C, and the resulting layer formation and bed agglomeration characteristics were determined. Based on this, a general reaction model for bed ash from agricultural residues was proposed, taking into account the reactivity of the different silicates investigated towards the main ash-forming elements K, Ca, and Si. The proposed reaction model links bed material interaction with K-rich bed ash to the degree of polymerization of the silicate bed material, where addition reactions occur in systems with high polymerization, predominately in quartz, and substitution reactions dominate for depolymerized silicates such as K-feldspar and olivine.

Peer reviewed papers | 2017

Behavior of GCMS tar components in a water gas shift unit operated with tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant

Kraussler M, Binder M, Hofbauer H. Behavior of GCMS tar components in a water gas shift unit operated with tar-rich product gas from an industrial scale dual fluidized bed biomass steam gasification plant. Biomass Conversion and Biorefinery. 1 March 2017;7(1): 69-79.

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Conference presentations and posters | 2022

BEST-Day

Sustainable biorefineries and digitalization

Schwabl M, Wopienka E, Drosg B, Kuba M, Weber G, Eßl M, Gölles M, Kaiermayer V, Liedte P, Fuhrmann M. BEST-Day: Sustainable biorefineries and digitalization. 7th Central European Biomass Conference CEBC 2023. 18. January 2023. Graz. Oral Presentation.

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List of presentations:

Biorefineries

  • Learnings from biomass combustion towards future bioenergy applications (M. Schwabl)
  • Green Carbon perspectives for regional sourcing and decarbonization (E. Wopienka)
  • Bioconversion processes for renewable energy and/or biological carbon capture and utilisation (B. Drosg)
  • Second generation biomass gasification: The Syngas Platform Vienna – current status and outlook (M. Kuba)
  • Utilization of syngas for the production of fuel and chemicals – recent developments and outlook (G. Weber)

Digital methods, tools and sustainability

  • Evaluation of different numerical models for the prediction of NOx emissions of small-scale biomass boilers (M. Eßl)
  • Digitalization as the basis for the efficient and flexible operation of renewable energy technologies (M. Gölles)
  • Smart Control for Coupled District Heating Networks (V. Kaisermayer)
  • Integrated energy solutions for a decentral energy future - challenges and solutions (P. Liedtke)
  • Wood-Value-Tool: Techno-economic assessment of the forest-based sector in Austria (M. Fuhrmann)
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.

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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.

Peer reviewed papers | 2024

Bubbling fluidized bed co-combustion and co-gasification of sewage sludge with agricultural residues with a focus on the fate of phosphorus

Hannl TK, Skoglund N, Priščák J, Öhman M, Kuba M. Bubbling fluidized bed co-combustion and co-gasification of sewage sludge with agricultural residues with a focus on the fate of phosphoru. Fuel. 1 February 2024. 357:129822

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In this work, the fate of the ash-forming elements during bubbling fluidized bed combustion and gasification of P-rich sewage sludge (SS) and mixtures with either Si-K-rich wheat straw (WS) or K-Ca-rich sunflower husks (SH) were investigated. The focus of the study was assessing the feasibility of using fuel blends in fluidized bed systems and potential P recovery from the resulting ashes. The used fuels were pure SS and mixtures including 90 wt.% WS (WSS) and 85 wt.% SH (SHS). The analyzed operating conditions were combustion (930–960 °C, λ: 1.2–1.5) and gasification (780–810 °C, λ: 0.4–0.7) in a 5 kW bench-scale reactor. Residual ash and char fractions were collected from different parts of the 5 kW bubbling fluidized bed (bed, cyclone, filter) and analyzed by CHN, SEM/EDS, XRD, and ICP-AES.

The conversion of the fuel mixtures achieved a steady state under the used process conditions except for the combustion of WSS, which led to the formation of large bed agglomerates with the bed material. The morphology of ash samples after combustion showed that SS fuel pellets mostly maintained their integrity during the experiment. In contrast, the ash and char particles from fuel mixtures were fragmented, and larger quantities were found in the cyclone, the filter, or on interior reactor surfaces. The fate of P was dominated by crystalline Ca-dominated whitlockites in all ash fractions, partially including K for the fuel mixtures SHS and WSS. 76–81 % of ingoing P was found in the bed residue after combustion and gasification of the SS-fuel. After conversion of the fuel mixtures SHS and WSS, the share was lower at 22–48 %, with larger shares of P in the entrained fractions (25–34 %). The quantity of identified crystalline compounds was lower after gasification than combustion, likely due to the limited interaction of ash-forming elements in the residual CHN matrix. Altogether, the results show that fuel mixtures of sewage sludge with agricultural residues could expand the fuel feedstock and enable P recovery. This may be used in the fuel and process design of upscaled fluidized bed processes or systems employing both combustion and gasification.

Reports | 2019

C200600_1 - Experimental Campaign Summer 2019

Fürsatz K, Kuba M, Karel T, Priscak J. C200600_1 - Experimental Campaign Summer 2019. Report on experimental test runs. November 2019.

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Reports | 2020

C200600_2 - Fluidization experiments February 2020

Fürsatz K, Kuba M. C200600_2 - Fluidization experiments February 2020. Bericht Versuchskampagne. February 2020

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Peer reviewed papers | 2018

Catalytic Efficiency of Oxidizing Honeycomb Catalysts Integrated in Firewood Stoves Evaluated by a Novel Measuring Methodology under Real-Life Operating Conditions

Reichert G, Schmidl C, Haslinger W, Stressler H, Sturmlechner R, Schwabl M, Wöhler M, Hochenauer C. Catalytic Efficiency of Oxidizing Honeycomb Catalysts Integrated in Firewood Stoves Evaluated by a Novel Measuring Methodology under Real-Life Operating Conditions. Renewable Energy, March 2018;117:300-313.

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Catalytic systems integrated in firewood stoves represent a potential secondary measure for emission reduction. However, the evaluation of catalytic efficiency is challenging since measurements, especially for PM emissions, upstream an integrated catalyst are not possible. Therefore, a special test facility, called “DemoCat”, was constructed which enabled parallel measurements in catalytically treated and untreated flue gas. The catalytic efficiency for CO, OGC and PM emissions was investigated under real-life operating conditions including ignition and preheating. The results confirmed a significant emission reduction potential (CO: > 95%, OGC: > 60%, PM: ∼30%). The conversion rates of CO and OGC emissions correlated with the space velocity and the coated area of honeycomb carriers which represent key parameters for the integration design. A quick response of the catalytic effect of around 5–12 min after ignition was observed when reaching 250 °C flue gas temperature at the catalyst. Most effective CO and OGC emission conversion was evident during the start-up and burn-out phase of a firewood batch. This reveals an important synergy for primary optimization which focuses particularly on the stretched intermediate phase of a combustion batch. The catalytic effect on PM emissions, especially on chemical composition, needs further investigations.

Peer reviewed papers | 2024

CO2 capture costs of chemical looping combustion of biomass: A comparison of natural and synthetic oxygen carrier

Fleiß B, Priscak J, Hammerschmid M, Fuchs J, Müller S, Hofbauer H. CO2 capture costs of chemical looping combustion of biomass: A comparison of natural and synthetic oxygen carrier. Jouernal of Energy Chemistry. May 2024.92:296-310.

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Chemical looping combustion has the potential to be an efficient and low-cost technology capable of contributing to the reduction of the atmospheric concentration of CO2 in order to reach the 1.5/2 °C goal and mitigate climate change. In this process, a metal oxide is used as oxygen carrier in a dual fluidized bed to generate clean CO2 via combustion of biomass. Most commonly, natural ores or synthetic materials are used as oxygen carrier whereas both must meet special requirements for the conversion of solid fuels. Synthetic oxygen carriers are characterized by higher reactivity at the expense of higher costs versus the lower-cost natural ores. To determine the viability of both possibilities, a techno-economic comparison of a synthetic material based on manganese, iron, and copper to the natural ore ilmenite was conducted. The synthetic oxygen carrier was characterized and tested in a pilot plant, where high combustion efficiencies up to 98.4% and carbon capture rates up to 98.5% were reached. The techno-economic assessment resulted in CO2 capture costs of 75 and 40 €/tCO2 for the synthetic and natural ore route respectively, whereas a sensitivity analysis showed the high impact of production costs and attrition rates of the synthetic material. The synthetic oxygen carrier could break even with the natural ore in case of lower production costs and attrition rates, which could be reached by adapting the production process and recycling material. By comparison to state-of-the-art technologies, it is demonstrated that both routes are viable and the capture cost of CO2 could be reduced by implementing the chemical looping combustion technology.

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.

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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 | 2021

CPFD simulation of a dual fluidized bed cold flow model

Lunzer A, Kraft S, Müller S, Hofbauer H. CPFD simulation of a dual fluidized bed cold flow model. Biomass Conversion and Biorefinery. 2021. 11(1):189 - 203

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The present work was carried out to simulate a cold flow model of a biomass gasification plant. For the simulation, a Eulerian-Lagrangian approach, more specifically the multi-phase particle in cell (MP-PIC) method, was used to simulate particles with a defined particle size distribution. Therefore, Barracuda VR, a software tool with an implemented MP-PIC method specifically designed for computational particle fluid dynamics simulations, was the software of choice. The simulation results were verified with data from previous experiments conducted on a physical cold flow model. The cold flow model was operated with air and bronze particles. The simulations were conducted with different drag laws: an energy-minimization multi-scale (EMMS) approach, a blended Wen-Yu and Ergun drag law, and a drag law of Ganser. The fluid dynamic behavior depends heavily on the particles’ properties like the particle size distribution. Furthermore, a focus was placed on the normal particle stress (PS value variation), which is significant in close-packed regions, and the loop seals’ fluidization rate was varied to influence the particle circulation rate. The settings of the simulation were optimized, flooding behavior did not occur in advanced simulations, and the simulations reached a stable steady state behavior. The Ganser drag law combined with an adjusted PS value with (PS = 30 Pa) or without (PS = 50 Pa) increased loop seal fluidization rates provided the best simulation results.

Peer reviewed papers | 2017

CPFD simulations of an industrial-sized dual fluidized bed steam gasification system of biomass with 8 MW fuel input

Kraft S, Kirnbauer F, Hofbauer H. CPFD simulations of an industrial-sized dual fluidized bed steam gasification system of biomass with 8 MW fuel input. Applied Energy. 15 March 2017;190: 408-420.

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Dual fluidized bed (DFB) systems for biomass gasification consist of two connected fluidized beds with a circulating bed material in between. Inside such reactor systems, rough conditions occur due to the high temperatures and the movement of the bed material. Computational fluid dynamics calculations are a useful tool for investigating fluid dynamics inside such a reactor system. In this study, an industrial-sized DFB system was simulated with the commercial code CPFD Barracuda. The DFB system is part of the combined heat and power (CHP) plant at Güssing, situated in Austria, and has a total fuel input of 8 MWth. The model was set up according to geometry and operating data which allows a realistic description of the hot system in the simulation environment. Furthermore, a conversion model for the biomass particles was implemented which covers the drying and devolatilization processes. Homogeneous and heterogeneous reactions were considered. Since drag models have an important influence on fluidization behavior, four drag models were tested. It was found that the EMMS drag model fits best, with an error of below 20%, whereas the other drag models produced much larger errors. Based on this drag law, further simulations were conducted. The simulation model correctly predicts the different fluidization regimes and pressure drops in the reactor system. It is also able to predict the compositions of the product and flue gas, as well as the temperatures inside the reactor, with reasonable accuracy. Due to the results obtained, Barracuda seems suitable for further investigations regarding the fluid mechanics of such reactors.

Conference presentations and posters | 2019

Decomposition of tars in dual fluidized bed gasification – mechanisms of formation and decomposition in long-term operation

Umeki K, Priscak J, Kuba M. Decomposition of tars in dual fluidized bed gasification – mechanisms of formation and decomposition in long-term operation. ICPS 2019.

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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.

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

Other Publications | 2023

Design of an aqueous phase reforming process demonstration unit for the production of green hydrogen from organcs-laden residual waters

Arlt S, Hochgerner S, Weber G, Pipitone G, Zoppi G, Bensaid S. Design of an aqueous phase reforming process demonstration unit for the production of green hyddrogen from organics-laden residual waters. BEST Center Day. 28 June 2023

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Aqueous phase reforming (APR) describes the conversion of oxygenated hydrocarbons dissolved in
an aqueous phase to hydrogen and carbon dioxide.

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.

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Peer reviewed papers | 2020

Developing an adsorption-based gas cleaning system for a dual fluidized bed gasification process

Loipersböck J, Weber G, Rauch R, Hofbauer H. Developing an adsorption-based gas cleaning system for a dual fluidized bed gasification process.Biomass Conversion and Biorefinery. 2020.

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Biomass has the potential to make a major contribution to a renewable future economy. If biomass is gasified, a wide variety of products (e.g., bulk chemicals, hydrogen, methane, alcohols, diesel) can be produced. In each of these processes, gas cleaning is crucial. Impurities in the gas can cause catalyst poisoning, pipe plugging, unstable or poisoned end products, or harm the environment. Aromatic compounds (e.g., benzene, naphthalene, pyrene), in particular, have a huge impact on stable operation of syngas processes. The removal of these compounds can be accomplished by wet, dry, or hot gas cleaning methods. Wet gas cleaning methods tend to produce huge amounts of wastewater, which needs to be treated separately. Hot gas cleaning methods provide a clean gas but are often cost intensive due to the high operating temperatures and catalysts used in the system. Another approach is dry or semi-dry gas cleaning methods, including absorption and adsorption on solid matter. In this work, special focus was laid on adsorption-based gas cleaning for syngas applications. Adsorption and desorption test runs were carried out under laboratory conditions using a model gas with aromatic impurities. Adsorption isotherms, as well as dynamics, were measured with a multi-compound model gas. Based on these results, a temperature swing adsorption process was designed and tested under laboratory conditions, showing the possibility of replacing conventional wet gas cleaning with a semi-dry gas cleaning approach.

Peer reviewed papers | 2017

Development and experimental validation of a water gas shift kinetic model for Fe-/Cr-based catalysts processing product gas from biomass steam gasification.

Kraussler M, Hofbauer H. Development and experimental validation of a water gas shift kinetic model for Fe-/Cr-based catalysts processing product gas from biomass steam gasification. Biomass Conversion and Biorefinery. Volume 7, Issue 2, 1 June 2017, Pages 153-165

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Conference presentations and posters | 2019

Development of a New Method for Investigation of the Ash Melting Behavior in the Fluidized Bed Conversion Processes

Priscak J, Kuba M, Hofbauer H. Development of a New Method for Investigation of the Ash Melting Behavior in the Fluidized Bed Conversion Processes. ICPS 2019.

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Conference presentations and posters | 2020

Dual fluidized bed steam gasification of biomass – the basic technology for a broad product portfolio

Kuba M. Dual fluidized bed steam gasification of biomass – the basic technology for a broad product portfolio. 6th Central European Biomass Conference (oral presentation). 2020.

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Peer reviewed papers | 2023

Early layer formation on K-feldspar during fluidized bed combustion with phosphorus-rich fuel

Faust R, Fürsatz K, Aonsamang P, Sandberg M, Kuba M, Skoglund N, Pavleta Knutsson. Early layer formation on K-feldspar during fluidized bed combustion with phosphorus-rich fuel. Fuel. January 2023.331:125595.

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K-feldspar was utilized as bed material for fluidized bed combustion of bark, chicken manure, and their mixture. Bed samples were extracted after 4 and 8 h and the samples were analyzed with scanning electron microscopy to study the impact of P-rich chicken manure on the bed material. The results were compared to fixed bed exposures with different orthophosphates to investigate their influence in detail.

The fresh bed material used for this study exhibited an uneven surface with many cavities which facilitated the deposition and retention of the fuel ash. Utilizing pure chicken manure as fuel led to the formation of Ca- and P-rich particles which accumulated in these cavities. At the same time, larger ash particles were formed which consisted of the elements found in chicken manure ash. The co-combustion of bark and chicken manure led to the interaction of the two ash fractions and the formation of a thicker ash layer, which consisted of elements from both fuel ashes, namely Ca, P, Si, K and S. The layer appeared to be partially molten which could be favorable for the deposition of ash particles and thereby the formation of a mixed Ca/K-phosphate. Fixed bed exposures of the K-feldspar particles with Na3PO4 or K3PO4 caused particle agglomeration which means presence of alkali-phosphates should be limited.

The co-combustion of bark with chicken manure showed promising results both regarding a shift from Ca-phosphates to more bioavailable Ca/K-phosphates and an acceleration in ash layer formation. The formation of an ash layer after only 4 h of exposure with the mixture of bark and chicken manure could be advantageous for catalytic activation of the bed material.

Peer reviewed papers | 2021

Effect of biomass fuel ash and bed material on the product gas composition in DFB steam gasification

Fürsatz K, Fuchs J, Benedikt F, Kuba M, Hofbauer H. Effect of biomass fuel ash and bed material on the product gas composition in DFB steam gasification. Energy. 2021.219:119650.

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Gasification is a thermochemical process that transforms carbonaceous matter into a gaseous secondary energy carrier, referred to as product gas. This product gas can be used for heat and power generation but also for syntheses. One possible gasification technology suitable for further synthesis is dual fluidised bed (DFB) steam gasification. The H2:CO ratio, which determines the suitability of the product gas for further synthesis, is influenced by the catalytic activity inside the gasification reactor. Eleven DFB steam gasification experiments were performed comparing the catalytic activity for various bed material and fuel combinations. The bed materials used were K-feldspar, fresh and layered olivine, and limestone, and the fuels gasified were softwood, chicken manure, a bark–chicken manure mixture and a bark-straw-chicken manure mixture. The water-gas-shift (WGS) equilibrium deviation was used to evaluate the catalytic activity inside the gasification reactor. It was shown that both the fuel ash and bed material have an effect on the catalytic activity during gasification. Scanning electron microscopy and energy dispersive X-ray spectrometry showed the initial layer formation for experiments with ash-rich fuels. Isolated WGS experiments were performed to further highlight the influence of bed material, fuel ash and fuel ash layers on the WGS equilibrium.

Peer reviewed papers | 2023

Effect of time-dependent layer formation on the oxygen transport capacity of ilmenite during combustion of ash-rich woody biomass

Priscak J, Valizadeh A, Öhman M, Hofbauer H, Kuba M. Effect of time-dependent layer formation on the oxygen transport capacity of ilmenite during combustion of ash-rich woody biomass. Fuel. 1 December 2023. 353:129068

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Oxygen carrier aided combustion (OCAC) is a novel technology that aims to enhance combustion of heterogenous fuels by replacing the inert bed material with an active oxygen carrier. One of the promising oxygen carriers is natural ilmenite which shows decent oxygen transport capacity and mechanical stability under OCAC operating conditions. However, interactions between ilmenite and woody biomass ash lead to the formation of a calcium-rich ash layer, which affects the ability of the oxygen carrier (OC) to transfer oxygen throughout the boiler and subsequently decreases the combustion efficiency. This paper focuses on the time-dependent morphological and compositional changes in ilmenite bed particles and the consequence effects on the oxygen transport capacity and reactivity of ilmenite. Ilmenite utilized in this study was investigated in a 5 kW bubbling fluidized bed combustion unit, utilizing ash-rich bark pellets as fuel. A negative effect of iron migration on the oxygen transport capacity was observed in ilmenite bed particles after 6 h of operation in the bubbling fluidized bed reactor. The decrease in the oxygen transport capacity of ilmenite was found to correlate with the increased exposure time in the fluidized bed reactor and was caused by the migration and subsequent erosion of Fe from the ilmenite particles. On the other hand, the older bed particles show an increase in reaction rate, presumably due to the catalytic activity of the calcium-enriched outer layer on the bed particle surface.

Peer reviewed papers | 2017

Estimation of binary diffusion coefficients in supercritical water - A mini review

Kraft S, Vogel F. Estimation of binary diffusion coefficients in supercritical water - A mini review. Industrial & Engineering Chemistry Research. 26 April 2017;56(16): 4847-4855.

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Diffusion coefficients of various solutes in supercritical water, which were either measured or retrieved from Molecular Dynamics simulations, were reviewed. Diffusion coefficients of molecules relevant for supercritical water processes were calculated with correlations reported in the literature and compared to the values of reference data. For conditions well above the critical point of water the simple Stokes-Einstein equation predicts the diffusion coefficients with an accuracy better than 20%. For conditions near the critical point the Wilke-Chang correlation gives the most accurate results. Diffusion coefficients for typical molecules occurring in supercritical water processes such as O2, N2, CO, CO2, or CH4 are estimated to be in the range of 60 · 10⁻⁹ m²/s at 673 K and 30 MPa. For H2, for which no experimental data are available, much higher diffusion coefficients in the range of 250 · 10⁻⁹ m²/s seem plausible. The data set of binary diffusion coefficients in supercritical water, either determined experimentally or by Molecular Dynamics simulations, should be extended significantly to include more solutes, as well as higher temperatures and pressures.
 

Peer reviewed papers | 2018

Experimental demonstration and validation of hydrogen production based on gasification of lignocellulosic feedstock

Loipersböck J, Luisser M, Müller S, Hofbauer H, Rauch R. Experimental demonstration and validation of hydrogen production based on gasification of lignocellulosic feedstock. 2018.2:61-73.

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The worldwide production of hydrogen in 2010 was estimated to be approximately 50 Mt/a, mostly based on fossil fuels. By using lignocellulosic feedstock, an environmentally friendly hydrogen production route can be established. A flow sheet simulation for a biomass based hydrogen production plant was published in a previous work. The plant layout consisted of a dual fluidized bed gasifier including a gas cooler and a dust filter. Subsequently, a water gas shift plant was installed to enhance the hydrogen yield and a biodiesel scrubber was used to remove tars and water from the syngas. CO2 was removed and the gas was compressed to separate hydrogen in a pressure swing adsorption. A steam reformer was used to reform the hydrocarbon-rich tail gas of the pressure swing adsorption and increase the hydrogen yield. Based on this work, a research facility was erected and the results were validated. These results were used to upscale the research plant to a 10 MW fuel feed scale. A validation of the system showed a chemical efficiency of the system of 60% and an overall efficiency of 55%, which indicates the high potential of this technology

Peer reviewed papers | 2019

Experimental demonstration of 80 kWth chemical looping combustion of biogenic feedstock coupled with direct CO2 utilization by exhaust gas methanation

Fleiß B, Bartik A, Priscak J, Benedikt F, Fuchs J, Müller S, Hofbauer H.Experimental demonstration of 80 kWth chemical looping combustion of biogenic feedstock coupled with direct CO2 utilization by exhaust gas methanation. Biomass Conversion and Biorefinery.10 May 2023

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Chemical looping combustion is a highly efficient CO2 separation technology without direct contact between combustion air and fuel. A metal oxide is used as an oxygen carrier in dual fluidized beds to generate clean CO2. The use of biomass is the focus of current research because of the possibility of negative CO2 emissions and the utilization of biogenic carbon. The most commonly proposed OC are natural ores and residues, but complete combustion has not yet been achieved. In this work, the direct utilization of CLC exhaust gas for methane synthesis as an alternative route was investigated, where the gas components CO, CH4 and H2 are not disadvantageous but benefit the reactions in a methanation step. The whole process chain, the coupling of an 80 kWth pilot plant with gas cleaning and a 10 kW fluidized bed methanation unit were for this purpose established. As OC, ilmenite enhanced with limestone was used, combusting bark pellets in autothermal operation at over 1000 °C reaching high combustion efficiencies of up to 91.7%. The fuel reactor exhaust gas was mixed with hydrogen in the methanation reactor at 360 °C and converted with a methane yield of up to 97.3%. The study showed especially high carbon utilization efficiencies of 97% compared to competitor technologies. Based on the experimental results, a scale-up concept study showed the high potential of the combination of the technologies concerning the total efficiency and the adaptability to grid injection.

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.

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

Peer reviewed papers | 2018

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

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

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

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

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

Peer reviewed papers | 2020

Fate of Phosphorus in Fluidized Bed Cocombustion of Chicken Litter with Wheat Straw and Bark Residues

Häggström G, Fürsatz K, Kuba M, Skoglund N, Öhman M. Fate of Phosphorus in Fluidized Bed Cocombustion of Chicken Litter with Wheat Straw and Bark Residues. Energy and Fuels. 2020.34:1822-1829

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This study aims to determine the fate of P during fluidized bed co-combustion of chicken litter (CL) with K-rich fuels [e.g., wheat straw (WS)] and Ca-rich fuels (bark). The effect of fuel blending on phosphate speciation in ash was investigated. This was performed by chemical characterization of ash fractions to determine which phosphate compounds had formed and identify plausible ash transformation reactions for P. The ash fractions were produced in combustion experiments using CL and fuel blends with 30% CL and WS or bark (B) at 790–810 °C in a 5 kW laboratory-scale bubbling fluidized bed. Potassium feldspar was used as the bed material. Bed ash particles, cyclone ash, and particulate matter (PM) were collected and subjected to chemical analysis with scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM–EDS) and X-ray diffraction. P was detected in coarse ash fractions only, that is, bed ash, cyclone ash, and coarse PM fraction (>1 μm); no P could be detected in the fine PM fraction (<1 μm). SEM–EDS analysis showed that P was mainly present in K–Ca–P-rich areas for pure CL as well as in the ashes from the fuel blends of CL with WS or B. In the WS blend, P was found together with Si in these areas. The crystalline compound containing P was hydroxyapatite in all cases as well as whitlockite in the cases of pure CL and WS blend, of which the latter compound has been previously identified as a promising plant nutrient. The ash fractions from CL and bark blend only contained P in hydroxyapatite. Co-combustion of CL together with WS appears to be promising for P recovery, and ashes with this composition could be further studied in plant growth experiments

Other Publications | 2023

First results from a novel temperature swing adsorption plant for clean synthesis gas

Egger A, Binder M, Weber G, Fürsatz K. First results from a novel temperature swing adsorption plant for clean synthesis gas. BEST Center Day. 28 June 2023

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Other Publications | 2023

Fischer-Tropsch pilot plant

Hochgerner S, Arlt S, Köffler T, Weber G, Kuba M, Rauch R, Hofbauer H. Fischer-Tropsch plant. BEST Center Day. 28 June 2023

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This work presents the first results of a newly commissioned biomass-to-liquid Fischer-Tropsch (FT) pilot plant. A 1 MWth dualfluidized bed (DFB) steam gasifier, a 55 Nm3/h 4-step gas cleaning plant and a 250 kW slurry bubble column FT synthesis reactor (SBCR) form the full process chain.

Reports | 2019

Fischer-Tropsch products from biomass-derived syngas and renewable hydrogen

Gruber H, Groß P, Rauch R, Reichhold A, Zweiler R, Aichernig C, Müller S, Ataimisch N, Hofbauer H. Fischer-Tropsch products from biomass-derived syngas and renewable hydrogen. 2019.

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Global climate change will make it necessary to transform transportation and mobility away from what we know now towards a sustainable, flexible, and dynamic sector. A severe reduction of fossil-based CO2 emissions in all energy-consuming sectors will be necessary to keep global warming below 2 °C above preindustrial levels. Thus, long-distance transportation will have to increase the share of renewable fuel consumed until alternative powertrains are ready to step in. Additionally, it is predicted that the share of renewables in the power generation sector grows worldwide. Thus, the need to store the excess electricity produced by fluctuating renewable sources is going to grow alike. The “Winddiesel” technology enables the integrative use of excess electricity combined with biomass-based fuel production. Surplus electricity can be converted to H2 via electrolysis in a first step. The fluctuating H2 source is combined with biomass-derived CO-rich syngas from gasification of lignocellulosic feedstock. Fischer-Tropsch synthesis converts the syngas to renewable hydrocarbons. This research article summarizes the experiments performed and presents new insights regarding the effects of load changes on the Fischer-Tropsch synthesis. Long-term campaigns were carried out, and performance-indicating parameters such as per-pass CO conversion, product distribution, and productivity were evaluated. The experiments showed that integrating renewable H2 into a biomass-to-liquid Fischer-Tropsch concept could increase the productivity while product distribution remains almost the same. Furthermore, the economic assessment performed indicates good preconditions towards commercialization of the proposed system.

Peer reviewed papers | 2021

Fischer-Tropsch products from biomass-derived syngas and renewable hydrogen

Gruber H, Groß P, Rauch R, Reichhold A, Zweiler R, Aichernig C, Müller S, Ataimisch N, Hofbauer H. Fischer-Tropsch products from biomass-derived syngas and renewable hydrogen. Biomass Conversion and Biorefinery. 2021.11(6):2281-2292

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Global climate change will make it necessary to transform transportation and mobility away from what we know now towards a sustainable, flexible, and dynamic sector. A severe reduction of fossil-based CO2 emissions in all energy-consuming sectors will be necessary to keep global warming below 2 °C above preindustrial levels. Thus, long-distance transportation will have to increase the share of renewable fuel consumed until alternative powertrains are ready to step in. Additionally, it is predicted that the share of renewables in the power generation sector grows worldwide. Thus, the need to store the excess electricity produced by fluctuating renewable sources is going to grow alike. The “Winddiesel” technology enables the integrative use of excess electricity combined with biomass-based fuel production. Surplus electricity can be converted to H2 via electrolysis in a first step. The fluctuating H2 source is combined with biomass-derived CO-rich syngas from gasification of lignocellulosic feedstock. Fischer-Tropsch synthesis converts the syngas to renewable hydrocarbons. This research article summarizes the experiments performed and presents new insights regarding the effects of load changes on the Fischer-Tropsch synthesis. Long-term campaigns were carried out, and performance-indicating parameters such as per-pass CO conversion, product distribution, and productivity were evaluated. The experiments showed that integrating renewable H2 into a biomass-to-liquid Fischer-Tropsch concept could increase the productivity while product distribution remains almost the same. Furthermore, the economic assessment performed indicates good preconditions towards commercialization of the proposed system.

Other Publications | 2020

GreenGas die Alternative zu Erdgas

Strasser C, Luisser M, Drosg B. GreenGas die Alternative zu Erdgas. TGA Planung 2021. December 2020.

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Reports | 2020

Handbook: Technical options for retrofiting industries with bioenergy

Rutz D, Janssen R, Reumerman P, Spekreijse J, Matschegg M, Bacovsky D, et al. Handbook: Technical options for retrofiting industries with bioenergy. March 2020

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Other papers | 2017

HCNG or hythane production from biomass steam gasification

Kraussler M, Priscak J, Hofbauer H. HCNG or hythane production from biomass steam gasification. 5th Central European Biomass Conference (oral presentation). January 2017, Graz, Austria.

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Peer reviewed papers | 2017

Hydrogen production from biomass: The behavior of impurities over a CO shift unit and a biodiesel scrubber used as a gas treatment stage

Loipersböck J, Lenzi M, Rauch R, Hofbauer H. Hydrogen production from biomass: The behavior of impurities over a CO shift unit and a biodiesel scrubber used as a gas treatment stage. Korean Journal of Chemical Engineering. 22 June 2017; 1-6.

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Most of the hydrogen produced is derived from fossil fuels. Bioenergy2020+ and TU Wien have been working on hydrogen production from biomass since 2009. A pilot plant for hydrogen production from lignocellulosic feedstock was installed onsite using a fluidized bed biomass gasifier in Güssing, Austria. In this work, the behavior of impurities over the gas conditioning stage was investigated. Stable CO conversion and hydration of sulfur components could be observed. Ammonia, benzene, toluene, xylene (BTX) and sulfur reduction could be measured after the biodiesel scrubber. The results show the possibility of using a commercial Fe/Cr-based CO shift catalyst in impurity-rich gas applications. In addition to hydrogen production, the gas treatment setup seems to also be a promising method for adjusting the H2 to CO ratio for synthesis gas applications.

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;

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Peer reviewed papers | 2018

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. April 2018, 111: 320-329.

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Dual fluidized bed biomass steam gasification generates a high calorific, practically nitrogen-free product gas with a volumetric H2 content of about 40%. Therefore, this could be a promising route for a polygeneration concept aiming at the production of valuable gases (for example H2), electricity, and heat. In this paper, a lab-scale process chain, based on state of the art unit operations, which processed a tar-rich product gas from a commercial dual fluidized bed biomass steam gasification plant, is investigated regarding H2 production within a polygeneration concept. The lab-scale process chain employed a water gas shift step, two gas scrubbing steps, and a pressure swing adsorption step. During the investigations, a volumetric H2 concentration of 99.9% with a specific H2 production of 30 g kg−1 biomass was reached. In addition, a valuable off-gas stream with a lower heating value of 7.9 MJ m−3 was produced. Moreover, a techno-economic assessment shows the economic feasibility of such a polygeneration concept, if certain feed in tariffs for renewable electricity and H2 exist. Consequently, these results show, that the dual fluidized bed biomass steam gasification technology is a promising route for a polygeneration concept, which aims at the production of H2, electricity, and district heat.

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.

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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.

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Peer reviewed papers | 2020

Impact of residual fuel ash layers on the catalytic activation of K-feldspar regarding the water–gas shift reaction

Fürsatz K, Kuba M, Janisch D, Aziaba K, Hammerl C, Chlebda D, Łojewska J, Hofbauer H. Impact of residual fuel ash layers on the catalytic activation of K-feldspar regarding the water–gas shift reaction. Biomass Conversion and Biorefinery. 2020

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Interaction of biomass ash and bed materials in thermochemical conversion in fluidized beds leads to changes of the bed particle surface due to ash layer formation. Ash components present on the bed particle surface strongly depend on the ash composition of the fuel. Thus, the residual biomass used has a strong influence on the surface changes on bed particles in fluidized bed conversion processes and, therefore, on the catalytic performance of the bed material layers. Ash layer formation is associated with an increase in the catalytic activity of the bed particles in gasification and plays a key role in the operability of different biomass fuels. The catalytic activation over time was observed for K-feldspar used as the bed material with bark, chicken manure, and a mixture of bark and chicken manure as fuels. The changes on the bed material surfaces were further characterized by SEM/EDS and BET analyses. Raman, XPS, and XRD analyses were used to characterize the crystal phases on the bed material surface. An increase in surface area over time was observed for K-feldspar during the interaction with biomass ash. Additionally, a more inhomogeneous surface composition for fuels containing chicken manure in comparison to pure bark was observed. This was due to the active participation of phosphorus from the fuel ash in the ash transformation reactions leading to their presence on the particle surface. A decreased catalytic activity was observed for the same BET surface area compared to bark combustion, caused by the different fuel ash composition of chicken manure.

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.

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Conference presentations and posters | 2020

Influence of ash forming elements from biogenous residues on fluidized bed conversion processes

Fürsatz K, Influence of ash forming elements from biogenous residues on fluidized bed conversion processes. 6th Central Eurpean Biomass Conference, 22-24 January 2020, Graz.

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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

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

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

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

Peer reviewed papers | 2020

Influence of bed materials on the performance of the Nong Bua dual fluidized bed gasification power plant in Thailand

Siriwongrungson V, Hongrapipat J, Kuba M, Rauch R, Pang S, Thaveesri J, Messner M, Hofbauer H. Influence of bed materials on the performance of the Nong Bua dual fluidized bed gasification power plant in Thailand. Biomass Conversion and Biorefinery. 2020;

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Bed materials and their catalytic activity are two main parameters that affect the performance of the dual fluidized bed (DFB) gasification system in terms of product gas composition and tar levels. Two sources of bed materials were used for the operation of a commercial DFB gasification system in Thailand, using woodchips as a biomass feedstock. One source of the bed materials was the calcined olivine which had been used in the Gussing Plant, Austria, and the other activated bed material was a mixture of fresh Chinese olivine and used Austrian olivine with additives of biomass ash, calcium hydroxide and dolomite. These bed materials were collected and analysed for morphological and chemical composition using a scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray fluorescence spectroscopy (XRF). The product gas was cleaned in a scrubber to remove tars, from which the samples were collected for gravimetric tar analysis. Its composition data was automatically recorded at the operation site before it entered the gas engine. From the SEM, EDS and XRF analyses, calcium-rich layers around the bed materials were observed on the activated bed material. The inner layers of bed materials collected were homogeneous. Biomass ash, which was generally added to the bed materials, had significant calcium and potassium content. These calcium-rich layers of the bed materials, from the calcium hydroxide, biomass ash and dolomite, influenced system performance, which was determined by observing lower tar concentration and higher hydrogen concentration in the product gas.

Peer reviewed papers | 2022

Influence of bed materials on the performance of the Nong Bua dual fluidized bed gasification power plant in Thailand

Siriwongrungson V, Hongrapipat J, Kuba M, Rauch R, Pang S, Thaveesri J, Messner M, Hofbauer H. Influence of bed materials on the performance of the Nong Bua dual fluidized bed gasification power plant in Thailand. Biomass Conversion and Biorefinery 2022. 12:2965-2979.

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Bed materials and their catalytic activity are two main parameters that affect the performance of the dual fluidized bed (DFB) gasification system in terms of product gas composition and tar levels. Two sources of bed materials were used for the operation of a commercial DFB gasification system in Thailand, using woodchips as a biomass feedstock. One source of the bed materials was the calcined olivine which had been used in the Gussing Plant, Austria, and the other activated bed material was a mixture of fresh Chinese olivine and used Austrian olivine with additives of biomass ash, calcium hydroxide and dolomite. These bed materials were collected and analysed for morphological and chemical composition using a scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray fluorescence spectroscopy (XRF). The product gas was cleaned in a scrubber to remove tars, from which the samples were collected for gravimetric tar analysis. Its composition data was automatically recorded at the operation site before it entered the gas engine. From the SEM, EDS and XRF analyses, calcium-rich layers around the bed materials were observed on the activated bed material. The inner layers of bed materials collected were homogeneous. Biomass ash, which was generally added to the bed materials, had significant calcium and potassium content. These calcium-rich layers of the bed materials, from the calcium hydroxide, biomass ash and dolomite, influenced system performance, which was determined by observing lower tar concentration and higher hydrogen concentration in the product gas.

Other papers | 2017

Influence of Calcium-rich Coatings on the Catalytic Activity of Bed Materials in CO2-Gasification of Biomass

Kuba M, Kirnbauer F, Hofbauer H. Influence of Calcium-rich Coatings on the Catalytic Activity of Bed Materials in CO2-Gasification of Biomass. 24th European Biomass Conference & Exhibition (poster). June 2016, Amsterdam, Netherlands.

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Peer reviewed papers | 2017

Influence of coated olivine on the conversion of intermediate products from decomposition of biomass tars during gasification

Kuba M, Kirnbauer F, Hofbauer H. Influence of coated olivine on the conversion of intermediate products from decomposition of biomass tars during gasification. Biomass Conversion and Biorefinery. 1 March 2017;7(1): 11-21.

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Steam gasification of solid biomass in dual fluidized bed systems is a suitable technology for the production of chemicals, fuels for transportation, electricity, and district heating. Interaction between biomass ash and bed material leads to the development of Ca-rich bed particle layers. Furthermore, incomplete decomposition of biomass leads to the formation of tar components; among these are stable intermediate products such as 1H-indene and stable gaseous hydrocarbons such as methane. In this work, the influence of bed particle layers on the conversion of intermediate products such as 1H-indene and methane via steam reforming was investigated by conducting experiments in a lab-scale test rig. Satisfying conversion of 1H-indene into gaseous molecules (e.g., CO, CO2, H2) was achieved with used, layered olivine, whereas fresh olivine showed significantly poorer performance. Since steam reforming was connected to the water-gas-shift reaction for the tested hydrocarbons, investigations regarding carbon monoxide conversion in the presence of steam were conducted as well. Furthermore, a comparison of the influence of fresh and used bed material concerning the conversion of methane is presented, showing that methane is not affected by the bed material, independent of the presence of particle layers.
 

Peer reviewed papers | 2018

Influence of drag laws on pressure and bed material recirculation rate in a cold flow model of an 8 MW dual fluidized bed system by means of CPFD

Kraft S, Kirnbauer F, Hofbauer H. Influence of drag laws on pressure and bed material recirculation rate in a cold flow model of an 8 MW dual fluidized bed system by means of CPFD. Particuology, February 2018;36:70-81.

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A cold flow model of an 8 MW dual fluidized bed (DFB) system is simulated using the commercial computational particle fluid dynamics (CPFD) software package Barracuda. The DFB system comprises a bubbling bed connected to a fast fluidized bed with the bed material circulating between them. As the hydrodynamics in hot DFB plants are complex because of high temperatures and many chemical reaction processes, cold flow models are used. Performing numerical simulations of cold flows enables a focus on the hydrodynamics as the chemistry and heat and mass transfer processes can be put aside. The drag law has a major influence on the hydrodynamics, and therefore its influence on pressure, particle distribution, and bed material recirculation rate is calculated using Barracuda and its results are compared with experimental results. The drag laws used were energy-minimization multiscale (EMMS), Ganser, Turton–Levenspiel, and a combination of Wen–Yu/Ergun. Eleven operating points were chosen for that study and each was calculated with the aforementioned drag laws. The EMMS drag law best predicted the pressure and distribution of the bed material in the different parts of the DFB system. For predicting the bed material recirculation rate, the Ganser drag law showed the best results. However, the drag laws often were not able to predict the experimentally found trends of the bed material recirculation rate. Indeed, the drag law significantly influences the hydrodynamic outcomes in a DFB system and must be chosen carefully to obtain meaningful simulation results. More research may enable recommendations as to which drag law is useful in simulations of a DFB system with CPFD.

Conference presentations and posters | 2019

Influence of fuel ash and bed material on the water-gas-shift equilibrium in DFB steam gasification

Fürsatz K, Fuchs J, Bartik A, Kuba M, Hofbauer H. Influence of fuel ash and bed material on the water-gas-shift equilibrium in DFB steam gasification. ICPS 2019.

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The bed material chosen for dual fluidized bed steam gasification has an important effect on the performance of gasification. Depending on their characteristics and properties, bed materials can have either a higher or lower catalytic activity, which influences the product gas composition as well as the tar content in the product gas. More catalytically active bed materials, like limestone and olivine, improve the quality of the product gas by e.g. promoting the water-gas-shift reaction and tar reforming reaction. The layers formed on the bed material are another aspect influencing the product gas composition. These layers are formed by the interaction of bed material and fuel ash. The deviation from the water-gas-shift equilibrium was chosen to quantify the effect of several bed materials and ash layers on the catalytic activity. The bed materials tested were K-feldspar, limestone, and activated olivine, while the used fuels were softwood, chicken manure, a bark – chicken manure mixture, and a bark –straw – chicken manure mixture. The performed experiments showed that an increased catalytic activity can be achieved by either using a catalytically active bed materials or ash-rich fuels.

 

Peer reviewed papers | 2021

Influence of solvent temperature and type on naphthalene solubility for tar removal in a dual fluidized bed biomass gasification process

Tonpakdee P, Hongrapipat J, Siriwongrungson V, Rauch R, Pang S, Thaveesri J, Messner M, Kuba M, Hofbauer H. Influence of solvent temperature and type on naphthalene solubility for tar removal in a dual fluidized bed biomass gasification process. Current Applied Science and Technology. 2021.21(4):751-76.

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Tar condensation is a cause of blockage in downstream application of the gasification process. An oil scrubber is considered as an effective method for tar removal. In this research, the naphthalene solubility in different local Thai oils and water was investigated in a laboratory-scale test-rig. The solubility value was conducted at 30, 50, 70, and 80°C. Biodiesels investigated were rapeseed methyl ester (RME) and two different palm methyl esters (PME 1 and PME 2). Furthermore, vegetable oils including sunflower oil, rice bran oil, crude palm oil, and refined palm oil were examined. The results showed that higher temperature enhanced naphthalene solubility in all types of investigated oils. Biodiesel has the highest value of naphthalene solubility. All scrubbing oils have similar naphthalene solubility trends at the temperature range of 50-80°C in the order of RME > PME 1 > PME 2 > diesel > sunflower oil > refined palm oil > rice bran oil > crude palm oil. Based on these experimental investigations, PME 1 has a naphthalene solubility value similar to RME. Therefore, PME 1 has been selected to be tested as scrubbing solvent in the 1 MWel prototype dual fluidized gasifier located in Nong Bua district, Nakhon Sawan province, Thailand.

Other papers | 2017

Influence of sulfur components on the catalytic mixed alcohol synthesis based on wood gas derived from biomass steam

Binder, M., Rauch, R., Koch, M., Summers, M., Aichernig, C., and Hofbauer, H.: Influence of sulfur components on the catalytic mixed alcohol synthesis based on wood gas derived from biomass steam. In: Proceedings of the 25th European Biomass Conference and Exhibition, 12 - 15 June 2017, Stockholm, Sweden.

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Peer reviewed papers | 2021

Innovative laboratory unit for pre-testing of oxygen carriers for chemical-looping combustion

Fleiss B, Fuchs J, Penthor S, Arlt S, Pachler R, Müller S, Hofbauer H. Innovative laboratory unit for pre-testing of oxygen carriers for chemical-looping combustion. Biomass Conversion and Biorefinery. 2021

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Chemical-looping combustion (CLC) is a highly efficient CO2 separation technology with no direct contact between combustion air and fuel. A metal oxide is used as an oxygen carrier (OC) and acts in a dual fluidized bed as a separation tool and supplies the fuel with oxygen, which as an oxidation medium causes combustion to CO2 and H2O. The use of solid fuels, especially biomass, is the focus of current investigations. The OC plays a key role, because it must meet special requirements for solid fuels, which are different to gaseous fuels. The ash content, special reaction mechanisms, and increased abrasion make research into new types of OC essential. Preliminary testing of OC before their use in larger plants regarding their suitability is recommended. For this reason, this work shows the design and the results of a laboratory reactor, which was planned and built for fundamental investigation of OC. Designed as a transient fluidized bed, the reactor, equipped with its own fuel conveying system and an in situ solid sampling, is intended to be particularly suitable for cheap and rapid pre-testing of OC materials. During the tests, it was shown that the sampling device enables non-selective sampling. Different OC were tested under various operating conditions, and their ability to convert different fuels could be quantified. The results indicate that OC can be sufficiently investigated to recommend operation in larger plants.

Peer reviewed papers | 2021

Integration of dual fluidized bed steam gasification into the pulp and paper industry

Kuba M, Benedikt F, Fürsatz K, Fuchs J, Demuth M, Aichernig C, Arpa L, Hofbauer H. Integration of dual fluidized bed steam gasification into the pulp and paper industry. Biomass Conversion and Biorefinery. 23 Dec 2021

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The pulp and paper industry represents an industry sector which is characterised by its already high degree of sustainability. Biomass is a renewable input material, and typically highly developed recovery cycles minimise the loss of chemicals used in the pulping process. However, certain parts of the recovery cycle are still operated on fossil fuels. This study deals with the substitution of the fossil-based gaseous fuel with product gas from biomass gasification.

Gasification experiments have shown that bark available at pulp and paper mills is suitable to produce a product gas via dual fluidised bed steam gasification as a promising substitute for natural gas. Based on the comparison of process layouts regarding the separation of non-process elements, separation efficiency is derived for different setups. To ensure operational security of the chemical recovery cycle, comprehensive gas cleaning including heat exchangers, a particle filter, and a liquid scrubber unit is advised. The gas flow of fuel gas into the gas burner is increased as the heating value of the product gas is accordingly lower in comparison to natural gas. Furthermore, adaptions of the gas burner might be necessary to address the earlier ignition of the H2-rich product gas compared to natural gas.

Peer reviewed papers | 2023

Integration of dual fluidized bed steam gasification into the pulp and paper industry

Kuba M, Benedikt F, Fürsatz K, Fuchs J, Demuth M, Aichernig C, Arpa L, Hofbauer H. Integration of dual fluidized bed steam gasification into the pulp and paper industry. Biomass Conversion and Biorefinery. 17 Novewmber 2023.13:15933 - 15948

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Peer reviewed papers | 2021

Interactions of Olivine and Silica Sand with Potassium- or Silicon-Rich Agricultural Residues under Combustion, Steam Gasification, and CO2 Gasification

Li G, Nathan GJ, Kuba M, Ashman PJ, Saw WL. Interactions of Olivine and Silica Sand with Potassium- or Silicon-Rich Agricultural Residues under Combustion, Steam Gasification, and CO2 Gasification. Industrial and Engineering Chemistry Research. 6 October 2021. 60 (39):14354 - 14369.

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Interactions between olivine or silica sand and potassium (K)-rich grape marc or silicon (Si)-rich wheat straw were studied in a fixed-bed reactor under combustion, steam, or a CO2 gasification atmosphere. This study focused on the effects of atmosphere composition, feedstock, and bed material type on the thermochemical aspects of agglomeration. The agglomeration extent of grape marc with olivine as the bed material under air and steam atmospheres is significantly less than with silica sand. The presence of CO2, compared to that of O2 or steam, was found to promote the reaction between K and olivine by facilitating the production of reactive silica from olivine carbonization. The use of olivine promotes the release of K by more than 10% compared with silica. No significant differences were observed in the agglomeration extent of wheat straw in its interaction with either olivine or silica sand. Nevertheless, olivine alters the agglomeration mechanism of wheat straw to become “melting-induced” from “coating-induced” in a silica bed.

Peer reviewed papers | 2021

Interactions of Olivine and Silica Sand with Potassium- or Silicon-Rich Agricultural Residues under Combustion, Steam Gasification, and CO2Gasification

Li G, Nathan GJ, Kuba M, Ashman PJ, Saw WL. Interactions of Olivine and Silica Sand with Potassium- or Silicon-Rich Agricultural Residues under Combustion, Steam Gasification, and CO2Gasification. Industrial and Engineering Chemistry Research. 2021.60(39):14354-14369.

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Interactions between olivine or silica sand and potassium (K)-rich grape marc or silicon (Si)-rich wheat straw were studied in a fixed-bed reactor under combustion, steam, or a CO2 gasification atmosphere. This study focused on the effects of atmosphere composition, feedstock, and bed material type on the thermochemical aspects of agglomeration. The agglomeration extent of grape marc with olivine as the bed material under air and steam atmospheres is significantly less than with silica sand. The presence of CO2, compared to that of O2 or steam, was found to promote the reaction between K and olivine by facilitating the production of reactive silica from olivine carbonization. The use of olivine promotes the release of K by more than 10% compared with silica. No significant differences were observed in the agglomeration extent of wheat straw in its interaction with either olivine or silica sand. Nevertheless, olivine alters the agglomeration mechanism of wheat straw to become “melting-induced” from “coating-induced” in a silica bed.

Reports | 2020

Investigation of the formation of coherent ash residues during fluidized bed gasification of wheat straw lignin

Priscak J, Fürsatz K, Kuba M, Skoglund N, Benedikt F, Hofbauer H. Investigation of the formation of coherent ash residues during fluidized bed gasification of wheat straw lignin. Energies. 2020;13(15):3935:

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Thermal conversion of ash-rich fuels in fluidized bed systems is often associated with extensive operation problems caused by the high amount of reactive inorganics. This paper investigates the behavior of wheat straw lignin—a potential renewable fuel for dual fluidized bed gasification. The formation of coherent ash residues and its impact on the operation performance has been investigated and was supported by thermochemical equilibrium calculations in FactSage 7.3. The formation of those ash residues, and their subsequent accumulation on the surface of the fluidized bed, causes temperature and pressure fluctuations, which negatively influence the steady-state operation of the fluidized bed process. This paper presents a detailed characterization of the coherent ash residues, which consists mostly of silica and partially molten alkali silicates. Furthermore, the paper gives insights into the formation of these ash residues, dependent on the fuel pretreatment (pelletizing) of the wheat straw lignin, which increases their stability compared to the utilization of non-pelletized fuel.

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.

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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.

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Peer reviewed papers | 2017

Investigations using a cold flow model of char mixing in the gasification reactor of a dual fluidized bed gasification plant

Kraft S, Kirnbauer F, Hofbauer H. Investigations using a cold flow model of char mixing in the gasification reactor of a dual fluidized bed gasification plant. Powder Technology. 1 July 2017;316: 687-696.

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This paper treats the mixing and movement of char in a dual fluidized bed (DFB) biomass gasification plant. In these plants such measurements are troublesome to perform, and so a cold flow model has been developed to investigate this topic. This cold flow model allows simulating the fluidization behaviour of the gasification reactor in the DFB plant in Güssing, Austria. The recirculation of the bed material is also possible, and can be easily controlled with a rotary valve. In the cold flow model, bronze is used as the bed material and polyethylene as the char. It is possible to take samples during operation to investigate the char concentration in the bed material recirculation stream. Experiments have shown that the char shows a flotsam behaviour since it is of low density. Furthermore, the investigations have shown that higher fluidization rates and higher bed material recirculation rates enhance the char mixing and increase the char concentration in the recirculation stream. It was found that doubling the overall char concentration in the system does not lead to a doubling of the char concentration in the bed material recirculation stream. Furthermore, the influence of the bed height in the gasification reactor was investigated. It was found that higher bed heights lead to lower char concentrations in the recirculation stream. These initial investigations revealed that much is still unknown about DFB plants, but the knowledge of the behaviour of the different types of particles in the bubbling bed of the gasification reactor helps to further improve and develop the DFB technology.

Peer reviewed papers | 2019

Layer formation mechanism of K-feldspar in bubbling fluidized bed combustion of phosphorus-lean and phosphorus-rich residual biomass.

Wagner K, Häggström G, Skoglund N, Priscak J, Kuba M, Öhman M, Hofbauer H. Layer formation mechanism of K-feldspar in bubbling fluidized bed combustion of phosphorus-lean and phosphorus-rich residual biomass. Applied Energy 2019.248:545-554.

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The use of phosphorus-rich fuels in fluidized bed combustion is one probable way to support both heat and power production and phosphorus recovery. Ash is accumulated in the bed during combustion and interacts with the bed material to form layers and/or agglomerates, possibly removing phosphorus from the bed ash fraction. To further deepen the knowledge about the difference in the mechanisms behind the ash chemistry of phosphorus-lean and phosphorus-rich fuels, experiments in a 5 kW bench-scale-fluidized bed test-rig with K-feldspar as the bed material were conducted with bark, wheat straw, chicken manure, and chicken manure admixtures to bark and straw. Bed material samples were collected and studied for layer formation and agglomeration phenomena by scanning electron microscopy combined with energy dispersive X-ray spectrometry. The admixture of phosphorus-rich chicken manure to bark changed the layer formation mechanism, shifting the chemistry to the formation of phosphates rather than silicates. The admixture of chicken manure to straw reduced the ash melting and agglomeration risk, making it possible to increase the time until defluidization of the fluidized bed occurred. The results also highlight that an increased ash content does not necessarily lead to more ash melting related problems if the ash melting temperature is high enough.

Peer reviewed papers | 2019

Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood Part 1: K-Feldspar

Faust R, Hannl T K, Berdugo Vilches T, Kuba M, Öhmann M, Seemann M C, Knutsson P Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood Part 1: K-Feldspar.Energy&Fuels 2019.33:8:7321-7332

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The choice of bed material for biomass gasification plays a crucial role for the overall efficiency of the process. Olivine is the material conventionally used for biomass gasification due to the observed activity of olivine toward cracking of unwanted tars. Despite its catalytic activity, olivine contains high levels of chromium, which complicates the deposition of used bed material. Feldspar has shown the same activity as olivine when used as a bed material in biomass gasification. As opposed to olivine, feldspar does not contain environmentally hazardous compounds, which makes it a preferred alternative for further applications. The interaction of bed material and ash heavily influences the properties of the bed material. In the present study interactions between feldspar and main ash compounds of woody biomass in an indirect gasification system were investigated. Bed material samples were collected at different time intervals and analyzed with SEM-EDS and XRD. The obtained analysis results were then compared to thermodynamic models. The performed study was divided in two parts: in part 1 (the present paper), K-rich feldspar was investigated, whereas Na-rich feldspar is presented in part 2 of the study (DOI: 10.1021/acs.energyfuels.9b01291). From the material analysis performed, it can be seen that, as a result of the bed materials’ interactions with the formed ash compounds, the latter were first deposited on the surface of the K-feldspar particles and later resulted in the formation of Ca- and Mg-rich layers. The Ca enriched in the layers further reacted with the feldspar, which led to its diffusion into the particles and the formation of CaSiO3 and KAlSiO4. Contrary to Ca, Mg did not react with the feldspar and remained on the surface of the particles, where it was found as Mg- or Ca-Mg-silicates. As a result of the described interactions, layer separation was noted after 51 h with an outer Mg-rich layer and an inner Ca-rich layer. Due to the development of the Ca- and Mg-rich layers and the bed material–ash interactions, crack formation was observed on the particles’ surfaces.

Peer reviewed papers | 2019

Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 1. K-Feldspar

Faust R, Hannl TK, Berdugo Vilches T Kuba M, Öhman M, Seemann M, Knutsson P. Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 1. K-Feldspar. Energy and Fuels 2019.33:7321-7332.

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The choice of bed material for biomass gasification plays a crucial role for the overall efficiency of the process. Olivine is the material conventionally used for biomass gasification due to the observed activity of olivine toward cracking of unwanted tars. Despite its catalytic activity, olivine contains high levels of chromium, which complicates the deposition of used bed material. Feldspar has shown the same activity as olivine when used as a bed material in biomass gasification. As opposed to olivine, feldspar does not contain environmentally hazardous compounds, which makes it a preferred alternative for further applications. The interaction of bed material and ash heavily influences the properties of the bed material. In the present study interactions between feldspar and main ash compounds of woody biomass in an indirect gasification system were investigated. Bed material samples were collected at different time intervals and analyzed with SEM-EDS and XRD. The obtained analysis results were then compared to thermodynamic models. The performed study was divided in two parts: in part 1 (the present paper), K-rich feldspar was investigated, whereas Na-rich feldspar is presented in part 2 of the study (DOI: 10.1021/acs.energyfuels.9b01291). From the material analysis performed, it can be seen that, as a result of the bed materials’ interactions with the formed ash compounds, the latter were first deposited on the surface of the K-feldspar particles and later resulted in the formation of Ca- and Mg-rich layers. The Ca enriched in the layers further reacted with the feldspar, which led to its diffusion into the particles and the formation of CaSiO3 and KAlSiO4. Contrary to Ca, Mg did not react with the feldspar and remained on the surface of the particles, where it was found as Mg- or Ca-Mg-silicates. As a result of the described interactions, layer separation was noted after 51 h with an outer Mg-rich layer and an inner Ca-rich layer. Due to the development of the Ca- and Mg-rich layers and the bed material–ash interactions, crack formation was observed on the particles’ surfaces.

Peer reviewed papers | 2019

Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 2. Na-Feldspar

Hannl TK, Faust R, Kuba M, Knutsson P, Berdugo Vilches T, Seemann MC, Öhman M. Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood Part 2: Na-Feldspar. Energy and Fuels 2019.33:7333-7346.

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Selecting a suitable bed material for the thermochemical conversion of a specific feedstock in a fluidized bed system requires identification of the characteristics of potential bed materials. An essential part of these characteristics is the interaction of the bed material with feedstock ash in a fluidized bed, which leads to layer formation and morphology changes. For this purpose, the interaction of feldspar bed material with the main ash-forming elements in wood ash (Ca, K, Mg, Si) in an indirect gasification system was analyzed using SEM-EDS, XRD, and thermodynamic modeling. In part 1 of this work (DOI: 10.1021/acs.energyfuels.9b01291), the layer formation on K-feldspar dominated by Ca reaction and ash deposition was investigated. The aim of this second part of the work was to determine the time-dependent layer formation on Na-feldspar and compare the results with the findings for K-feldspar. Interaction of Na-feldspar with ash-derived elements resulted in different layers on Na-feldspar: K reaction layers, where K replaced Na and Si shares decreased; Ca reaction layers, where Ca enriched and reacted with the Na-feldspar; and ash deposition layers, where wood ash elements accumulated on the surface. Ca reaction layers were formed first and became continuous on the surface before K reaction layers and ash deposition layers were detected. Cracks and crack layer formation in the Na-feldspar particles were found after several days of operation. The layer compositions and growth rates indicate that the diffusion of Ca and K plays an essential role in the formation of Ca reaction and K reaction layers. The reaction with Ca and the crack formation coincide with the interaction previously found for quartz and K-feldspar. In contrast to K-feldspar, Na-feldspar showed high potential for reaction with K. The findings indicate that the reaction of Na-feldspar with ash-derived K makes Na-feldspar a less stable bed material than K-feldspar during the thermochemical conversion of K-rich feedstocks in a fluidized bed system.

Peer reviewed papers | 2019

Layer formation on K-feldspar in fluidized bed combustion and gasification of bark and chicken manure

Wagner K, Häggström G, Mauerhofer AM, Kuba M, Skoglund N, Öhman M, Hofbauer H. Layer formation on K-feldspar in fluidized bed combustion and gasification of bark and chicken manure. Biomass and Bioenergy 2019.127:105251.

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Understanding layer formation on bed materials used in fluidized beds is a key step for advances in the application of alternative fuels. Layers can be responsible for agglomeration-caused shut-downs but they can also improve the gas composition in fluidized bed gasification. Layers were observed on K-feldspar (KAlSi3O8) impurities originating from the combined heat and power plant Senden which applies the dual fluidized bed (DFB) steam gasification technology. Pure K-feldspar was therefore considered as alternative bed material in DFB steam gasification. Focusing on the interactions between fuel ash and bed material, K-feldspar was tested in combustion and DFB steam gasification atmospheres using different fuels, namely Ca-rich bark, Ca- and P-rich chicken manure, and an admixture of chicken manure to bark. The bed particle layers formed on the bed material surface were characterized using combined scanning electron microscopy and energy-dispersive X-ray spectroscopy; area mappings and line scans were carried out for all samples. The obtained data show no essential influence of operational mode on the layer-formation process. During the combustion and DFB steam gasification of Ca-rich bark, a layer rich in Ca formed while K was diffusing out of the layer. The use of Ca- and P-rich chicken manure inhibited the diffusion of K, and a layer rich in Ca and P formed. The addition of P to bark via chicken manure also changed the underlying layer-formation processes to reflect the same processes as observed for pure chicken manure.

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.

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Peer reviewed papers | 2019

Mathematical model of Fischer-Tropsch synthesis using variable alpha-parameter to predict product distribution.

Filip L, Zámostný P, Rauch R. Mathematical model of Fischer-Tropsch synthesis using variable alpha-parameter to predict product distribution. Fuel 2019;243:603-609.

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A mathematical model was developed based on data obtained on Fischer-Tropsch (FT) laboratory scale unit operated in steady state, belonging to BIOENERGY 2020+ GmbH, Austria to demonstrate alpha-parameter dependence on carbon number. The lab-scale unit processed the synthesis gas, obtained by the gasification of biomass (woodchips), to produce liquid fuels for transportation applications. The FT reaction took place in a slurry reactor filled with dispersed cobalt-based catalyst. The products were then separated by partial condensation depending on their boiling points. The final output of the FT laboratory scale unit comprised three product streams – wax, diesel and naphtha. The reaction and separation of products were simulated in Aspen Plus software. The mathematical model used kinetic description based on power-law rate equations. The modeled product selectivity was controlled using an alpha-parameter of the Anderson-Schulz-Flory distribution. Because of the significant deviation of products spectrum from typical Anderson-Schulz-Flory distribution, a modified description of reaction selectivity was developed. The description introduces variable alpha-parameter, dependent on number of carbon atoms in the reacting molecule. The mathematical model developed using MATLAB software considered the production of aliphatic paraffins having a number of carbon atoms from C1 to C60. The mathematical model of simulated lab-scale unit comprised an ideally mixed reactor RCSTR and three FLASH2 separators for the separation of desired products. The results from mathematical model were validated by a comparison with experimental results from FT lab-scale unit. The modified polynomial dependency of alpha-parameter on carbon number showed significantly better description of composition and amounts of FT products, especially for wax stream where the description using constant alpha led to enormous deviations. Such better prediction of composition and amounts of acquired products is important for evaluating efficiency of further upgrading the FT products to liquid fuel.

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.

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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.
 

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.

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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.

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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.

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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 | 2020

Optimizing of a hydrogen production plant by optimization of the CO2 removal step

Loipersböck J. Optimizing of a hydrogen production plant by optimization of the CO2 removal step. 6th Central European Biomass Conference (oral presentation) 2020.

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Hydrogen production in 2010 was estimated to 50 Mt/a. 96 % of today’s hydrogen is produced by converting fossil fuels in thermochemical processes. As main conversion technology steam reforming of natural gas and naphtha has been established. Hydrogen is mainly used in refineries, for ammonia production and in several chemical production plants. Hydrogen is also seen as a promising alternative energy carrier for the transport sector. Therefor an increasing demand on hydrogen over the next years can be assumed.  
To substitute fossil produced hydrogen several renewable hydrogen routes have been established. Beside electrolysis of water also steam reforming of biogas, methane pyrolysis and gasification technologies have been developed. This work will focus on hydrogen production based on dual fluidized bed gasification of biomass.  
Dual fluidized bed gasification gives the possibility to establish a renewable hydrogen production route and substitute fossil fuels. A hydrogen production plant consisting of a dual fluidized bed gasifier, a water gas shift stage, a CO2 removal, a pressure swing adsorption and a steam reformer were erected and operated over 1000 h. The gathered data was validated and a model for up-scaling was developed. A benchmark size of 10 MW fuel input power was used as base for economic estimations. As described in previous work an overall efficiency of 55 % can be achieved, which is comparable to alternative technologies. Compared to other renewable routes, hydrogen production based on dual fluidized bed gasification gives the possibility of a fuel flexible system for continuous hydrogen production.  
Hydrogen production derived by DFB gasification of wood is a reliable process, which needs to be optimized due to economic reasons. Special attention has to be paid on the CO2 removal, to obtain an economic efficient process.  
In this study a parameter variation of the CO2 removal, which consists of absorption and desorption column, was done. Mono-ethanol-amine (MEA) was used as a solvent. One focus of the experimental investigations was the desorption at low temperatures to gain the possibility of using temperature levels which are common in district heat grids. For the experiments real synthesis gas with impurities was used. Over the gas cleaning steps of the hydrogen production plant, impurities were removed and hydrogen content was increased. To increase the efficiency of the CO2 removal and further the hydrogen production, a parameter study was done. A good correlation between separation efficiency and desorption temperature could be observed.  
Economics were calculated comparing natural gas steam reforming, electrolysis and hydrogen production based dual fluidized bed gasification. First results show a high potential for establishing the BioH2 plant as a commercial production plant. An economic plant operation with wood chips can be achieved at plant sizes of 20-30 MW fuel input power. A switch to lower quality biomass can reduce the economic feasible plant size even further.  
Keywords: hydrogen, up-scaling, economics, CO2 removal

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)

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Other papers | 2017

Performance of a mixed alcohol synthesis lab-scale process chain operated with wood gas from dual fluidized bed biomass steam gasification

Binder M, Weber G, Rauch R, Hofbauer H. Performance of a mixed alcohol synthesis lab-scale process chain operated with wood gas from dual fluidized bed biomass steam gasification. 5th Central European Biomass Conference (Poster). January 2017, Graz, Austria.

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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.

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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.

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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.

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Peer reviewed papers | 2017

Performance of a water gas shift unit processing tar-rich product gas from a commercial dual fluidized bed biomass steam gasification plant which operates at partial load

Kraussler M, Binder M, Hofbauer H. Performance of a water gas shift unit processing tar-rich product gas from a commercial dual fluidized bed biomass steam gasification plant which operates at partial load. International Journal of Oil, Gas and Coal Technology. 2017;14(1-2): 32-48.

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In this paper, the performance of a water gas shift unit processing product gas from a commercial dual fluidised bed biomass steam gasification plant is studied. The experiments were carried out during a partial load operation of the gasification plant. In order to investigate a water gas shift process, a water gas shift unit, located at the site of the gasification plant in Oberwart, Austria, was used. The water gas shift unit consisted of three reactors in series filled with a commercial Fe'Cr-based catalyst and was operated with tar-rich product gas. No performance decrease of the water gas shift unit was observed during the partial load operation of the gasification plant. Furthermore, a CO conversion of 92% and a GCMS tar reduction of about 30% were reached. In addition, it was found that partial load operation of the gasification plant did not negatively affect the performance of the water gas shift unit.

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.

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Other papers | 2017

Polygeneration of hydrogen and a gas mixture composed of H2 and CH4 via sorption enhanced reforming of biomass

Kraussler M, Priscak J, Benedikt F, Hofbauer H. Polygeneration of hydrogen and a gas mixture composed of H2 and CH4 via sorption enhanced reforming of biomass. 25th European Biomass Conference & Exhibition (oral presentation). June 2017, Stockholm, Sweden.

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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.

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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.

Peer reviewed papers | 2018

Power to fuels: Dynamic modeling of a Slurry Bubble Column Reactor in lab-scale for Fischer Tropsch synthesis under variable load of synthesis gas

Seyednejadian S, Rauch R, Bensaid S, Hofbauer H, Weber G, Saracco G. Power to fuels: Dynamic modeling of a Slurry Bubble Column Reactor in lab-scale for Fischer Tropsch synthesis under variable load of synthesis gas. Apllied Sciences. 2018, 8(4): 514.

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This research developed a comprehensive computer model for a lab-scale Slurry Bubble Column Reactor (SBCR) (0.1 m Dt and 2.5 m height) for Fischer–Tropsch (FT) synthesis under flexible operation of synthesis gas load flow rates. The variable loads of synthesis gas are set at 3.5, 5, 7.5 m3/h based on laboratory adjustments at three different operating temperatures (483, 493 and 503 K). A set of Partial Differential Equations (PDEs) in the form of mass transfer and chemical reaction are successfully coupled to predict the behavior of all the FT components in two phases (gas and liquid) over the reactor bed. In the gas phase, a single-bubble-class-diameter (SBCD) is adopted and the reduction of superficial gas velocity through the reactor length is incorporated into the model by the overall mass balance. Anderson Schulz Flory distribution is employed for reaction kinetics. The modeling results are in good agreement with experimental data. The results of dynamic modeling show that the steady state condition is attained within 10 min from start-up. Furthermore, they show that step-wise syngas flow rate does not have a detrimental influence on FT product selectivity and the dynamic modeling of the slurry reactor responds quite well to the load change conditions.

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.

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