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Peer Reviewed Scientific Journals | 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.


Conference Papers | 2020

Development and experimental validation of a linear state-space model for absorption heat pumping systems for model-based control strategies

Zlabinger S, Unterberger V, Gölles M, Horn M, Wernhart M, Rieberer R. Development and experimental validation of a linear state-space model for absorption heat pumping systems for model-based control strategies. International Sorption Heat Pump Conference 2020.

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Control strategies of absorption heat pumping systems (AHPS, comprising heat pumps and chillers) often
perform insufficiently well, since they usually do not explicitly consider the systems’ dynamics and crosscoupling effects. One promising approach to improve their performance is to apply model-based control strategies since they would allow for an explicit consideration of these system characteristics. Therefore, mathematically simple models of the system to be controlled are required. This contribution proposes a new approach for such a model for a H2O-LiBr AHPS. The model results from the linearization of a more complex, nonlinear simulation model, leading to a simple, but physically still meaningful linear state-space model structure. The experimental validation shows that the developed model describes the system’s dynamics and cross-coupling effects sufficiently well and indicates that it is suitable to serve as a basis for the development of a model-based control strategy for AHPS.


Scientific Journals | 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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Peer Reviewed Scientific Journals | 2015

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

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

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


Peer Reviewed Scientific Journals | 2013

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

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

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


Conference contributions | 2015

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

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

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Scientific Journals | 2018

Development of a compact technique to measure benzo(a)pyrene emissions from residential wood combustion, and subsequent testing in six modern wood boilers

Klauser F, Schwabl M, Kistler M, Sedlmayer I, Kienzl N, Weissinger A, Schmidl C, Haslinger W, Kasper-Giebl A. Development of a compact technique to measure benzo(a)pyrene emissions from residential wood combustion, and subsequent testing in six modern wood boilers. Biomass and Bioenergy. April 2018, 111: 288-300.

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Polycyclic aromatic hydrocarbons (PAHs) are emitted during incomplete combustion of organic materials and are particularly harmful to human health. As a representative of PAHs, Benzo(a)pyrene (BaP) is restricted by the European Union to an annual average value of 1 ng m−3 in ambient air. This threshold is significantly exceeded during the heating season in various regions. Residential wood combustion furnaces are considered to be a major source for BaP pollution.

In this research, a compact sampling method for BaP measurements was validated. Afterwards, the method was used to assess emissions from modern automatic wood boilers, in order to obtain a detailed knowledge of BaP emissions from residential wood combustion furnaces.

It was demonstrated that, for a wide range of BaP concentrations, sampling from the hot flue gas of residential wood combustors can be carried out effectively over a simple quartz filter, after proper dilution with cold purified air. Highest BaP emissions from the investigated boilers occurred during start, with a mean concentration value of 6.3 μg m-3. All values refer to standard conditions (273.15 °C, 100 kPa) and to an O2 volume fraction of 13% in the dry flue gas. The lowest concentrations occurred during full load operation (mean value 73 ng m-3 at STP). It was found that, amongst all flue gas compounds analysed, elemental carbon is the parameter most closely related to BaP. This work demonstrates, at optimal operating conditions, modern automatic wood boilers have potentially lowest BaP emission concentrations amongst residential wood combustion furnaces.


Contributions to trade journals | 2014

Development of a gas phase combustion model suitable for low and high turbulence conditions

Shiehnejadhesar A, Mehrabian R, Scharler R, Goldin GM, Obernberger I. Development of a gas phase combustion model suitable for low and high turbulence conditions. Fuel. 2014;126:177-87.

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A novel hybrid gas phase combustion model suitable for low as well as high turbulent combustion conditions is proposed. In particular, in the region above the fuel bed of small-scale biomass combustion plants, gas phase mixing is highly influenced by laminar and low turbulence zones. Here, the eddy break-up combustion models are not valid because they were originally developed for highly turbulent flows. Therefore, a CFD gas phase reaction model applicable over the whole Reynolds range from laminar to turbulent flows is developed. It is a hybrid Eddy Dissipation Concept/finite rate kinetics model which calculates the effective reaction rate from laminar finite rate kinetics and the turbulent reaction rate and weights them depending on the local turbulent Reynolds number of the flow. To validate the proposed model, comparisons are made with experimental data for a series of jet flames covering laminar, transitional, and turbulent flow conditions. The simulation results show that the prediction of flame can be improved with the proposed hybrid combustion model. © 2014 Elsevier Ltd. All rights reserved.


Conference contributions | 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 contributions | 2015

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

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

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Conference contributions | 2014

Development of a new Type test method for residential wood combusiton (RWC) appliances focusing on real life operation

Reichert G, Schmidl C, Aigenbauer S, Figl F, Moser W, Stressler H, Haslinger W, Development of a new Type test method for residential wood combusiton (RWC) appliances focusing on real life operation, 22nd European Biomass Conference 2014, 23rd-26th of June 2014, Hamburg, Germany. p 373-380.

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Since batch-wise operated biomass roomheaters are claimed to cause high amounts of gaseous and particulate emissions effective measures for a reduction of these emissions especially in real life operation have to be implemented in the future. For a verification of the real life operation performance as well as for a better product differentiation of biomass room heating appliances on the market advanced testing methods will be necessary in the future. Therefore a new test method for roomheaters called “Stove Testing 2020” (ST2020) was developed. According to the new test method the emission and efficiency performance of roomheaters is determined under operating conditions that are closer to real life. Compared to the existing EN 13240 standard also transient combustion phases are included. For a final evaluation of the test method the reproducibility as well as the real life relevance was analysed by a Round-Robin-Test as well as by field tests. The results showed sufficient reproducibility as well as a high real life relevance of the ST2020 test method. However, due to the strong impact of user behavior on emission and efficiency performance in real life operation further technological improvements of biomass roomheaters have to be strongly supported by effective measures to guarantee a correct operation.


Conference contributions | 2015

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

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

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


Conference contributions | 2013

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

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

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Conference contributions | 2012

Development of an empirical model to describe the local high temperature corrosion risk of 13CrMo4-5 steel in biomass CHP plants regarding the fuel wood chips

Gruber T, Schulze K, Scharler R, Oberberger I. Development of an empirical model to describe the local high temperature corrosion risk of 13CrMo4-5 steel in biomass CHP plants regarding the fuel wood chips, Conference Impacts of Fuel Quality on Power Production and Environment 2012, 23th-27th of September 2012, Puchberg, Austria.

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Conference contributions | 2011

Development of biomass fired boilers with an advanced CFD model for ash deposit and aerosol formation

Schulze K, Scharler R, Obernberger I. Development of biomass fired boilers with an advanced CFD model for ash deposit and aerosol formation, 9th European Conference on Industrial Furnaces and Boilers 2011, 26th-29th of April 2011, Estoril, Portugal.

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Conference contributions | 2014

Development of novel concepts for microalgae in the Austrian energy system

Sonnleitner A, Bacovsky D. Development of novel concepts for microalgae in the Austrian energy system, 4. Central European Biomass Conference 2014, 15th-18th of January 2014, Graz, Austria.

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Microalgae are seen worldwide as a new and promising feedstock for the energy supply chain.
Because of their high productivity and their ability to convert CO2 into biomass, microalgae are a
potential raw material for biorefineries, avoiding the food versus fuel conflict, and contributing to an
increased share of renewable energy. According to the current state of the art the utilization of algal
biomass for the production of fuel, energy and heat seems to be economically not competitive and the
life cycle assessment shows improvement possibilities in energy consumption (project
Algae&Energy:Austria). There are different options for utilization concepts which are technologically
and economically feasible. New concepts need to be developed and synergies with already existing
technologies need to be used.
Challenges along the value chain:
· Supply of water for cultivation
· Supply of nutrients for cultivation
· Energy consumption during cultivation
· Harvesting and processing of biomass
· Investment and operating costs
One possibility to cover the need of water and nutrients in a cost-effective way is the combination of
microalgae cultivation and waste water treatment. The cultivation of algae using different waste water
types common in Austria is technologically possible. In particular municipal waste water and effluents
from breweries and dairies are suitable as substrate. Due to the usage of this synergy the need for
fresh water and artificial fertilizer for algae cultivation decreases substantially and therefore operating
costs are reduced. Promising production concepts were developed and further research and
development needs were pointed out (project SAM).
After producing algal biomass the harvesting and processing steps for further utilization seem to be
difficult. In particular the high amount of water increases the energy expenditure in most of the
conversion pathways. Hydrothermal liquefaction seems to be promising to reduce the energy intensity
through two major factors: First, the conversion takes place in the liquid phase, and no energy
intensive drying of the algal biomass is needed. Second, the entire carbon which is fixed in the algae
can be used for energy production. The main product of hydrothermal liquefaction is a bio-oil, which
can be further processed in existing refinery processes into biogenic motor fuels, plastics and basic
chemicals (project microHTL).
In Austria many scientific research groups and companies are dealing with microalgae in the energy
system. These research and development efforts comprise different topics and approaches, like
different cultivation system designs (open pond, photobioreactor), biotechnological optimization of
microalgae species, the utilization of algal biomass in energetic and material pathways or the
combination of microalgae cultivation with existing technologies. It is of growing importance to
establish a network of Austrian experts and research groups for enhancement of cooperation and
research within the field of algae (project network biobased industry).
Through the optimization along the entire value chain with special regard to novel concepts of
cultivation, harvesting, processing, conversion and utilization, as well as an enhanced network of
Austrian experts and research groups, microalgae can serve as biogenic feedstock for the energy


Conference contributions | 2010

Development of process routes for synthetic biofuels from biomass (BTL)

Weber G, Potetz A, Rauch R, Hofbauer H. Development of process routes for synthetic biofuels from biomass (BTL), 18th European Biomass Conference and Exhibiton 2010, 3rd-7th May 2010, Lyon, France. p 1829-1833.

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In Güssing a nearly nitrogen free product gas can be provided by the Fast Internal Circulating Fluidized Bed (FICFB) – gasification system. The main components of the product gas are hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4). A Fischer – Tropsch (FT-) trial plant uses the product gas components H2 and CO in an exothermic, catalytic reaction to produce hydrocarbon chains. Catalysts based on iron and cobalt are used for the synthesis. In Güssing a slurry reactor is used for low temperature FT – synthesis. The main parts of the plant are the gas cleaning section, the gas compression section, the FT – slurry reactor and the product separation section. In the year 2008 eight experiments with a catalyst based on iron and from April to July 2009 ten experiments with a catalyst based on cobalt were done. Over 1400 operating hours were reached and approximately 170 kg of FT – raw product was produced. The product of the experiments with cobalt catalyst was split into the fractions naphtha, diesel and waxes by vacuum distillation. The long chain waxes of the distillation were used in a hydro – treater to convert them to diesel.


Contributions at other events | 2012

Development of the 1MW Bio-SNG plant, evaluation on technological and economical aspects and upscaling considerations

Rehling, B. Development of the 1MW Bio-SNG plant, evaluation on technological and economical aspects and upscaling considerations, Ph.D. Thesis, Vienna University of Technology, Vienna, Austria, 2012.

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Conference contributions | 2020

Die Donau - Eine Chance für die Bioenergiebranche?

Dißauer C, Strasser C. Die Donau - Eine Chance für die Bioenergiebranche? 6th Central European Biomass Conference, 2020, Graz.

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Conference contributions | 2008

Die Situation der energetischen Nutzung von Stroh in Österreich

Eder G, Haslinger W, Wörgetter M. Die Situation der energetischen Nutzung von Stroh in Österreich, Fachtagung Strohenergie 2008, 29th-30th of March, Jena, Deutschland.

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Peer Reviewed Scientific Journals | 2021

Digestate as Sustainable Nutrient Source for Microalgae - Challenges and Prospects

Bauer L, Ranglová K, Masojidek J, Drosg B, Meixner K. Digestate as Sustainable Nutrient Source for Microalgae - Challenges and Prospects. Applied Sciences (Switzerland). February 2021. 11(3):1 - 211.

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The interest in microalgae products has been increasing, and therefore the cultivation industry is growing steadily. To reduce the environmental impact and production costs arising from nutrients, research needs to find alternatives to the currently used artificial nutrients. Microalgae cultivation in anaerobic effluents (more specifically, digestate) represents a promising strategy for increasing sustainability and obtaining valuable products. However, digestate must be processed prior to its use as nutrient source. Depending on its composition, different methods are suitable for removing solids (e.g., centrifugation) and adjusting nutrient concentrations and ratios (e.g., dilution, ammonia stripping). Moreover, the resulting cultivation medium must be light-permeable. Various studies show that growth rates comparable to those in artificial media can be achieved when proper digestate treatment is used. The necessary steps for obtaining a suitable cultivation medium also depend on the microalgae species to be cultivated. Concerning the application of the biomass, legal aspects and impurities originating from digestate must be considered. Furthermore, microalgae species and their application fields are essential criteria when selecting downstream processing methods (harvest, disintegration, dehydration, product purification). Microalgae grown on digestate can be used to produce various products (e.g., bioenergy, animal feed, bioplastics, and biofertilizers). This review gives insight into the origin and composition of digestate, processing options to meet requirements for microalgae cultivation and challenges regarding downstream processing and products.

Peer Reviewed Scientific Journals | 2021

Digestate as Sustainable Nutrient Source for Microalgae—Challenges and Prospects

Bauer L, Ranglová K, Masojidek J, Drosg B, Meixner K. Digestate as Sustainable Nutrient Source for Microalgae—Challenges and Prospects. Applied Sciences. 2021.11(3):1056

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The interest in microalgae products has been increasing, and therefore the cultivation industry is growing steadily. To reduce the environmental impact and production costs arising from nutrients, research needs to find alternatives to the currently used artificial nutrients. Microalgae cultivation in anaerobic effluents (more specifically, digestate) represents a promising strategy for increasing sustainability and obtaining valuable products. However, digestate must be processed prior to its use as nutrient source. Depending on its composition, different methods are suitable for removing solids (e.g., centrifugation) and adjusting nutrient concentrations and ratios (e.g., dilution, ammonia stripping). Moreover, the resulting cultivation medium must be light-permeable. Various studies show that growth rates comparable to those in artificial media can be achieved when proper digestate treatment is used. The necessary steps for obtaining a suitable cultivation medium also depend on the microalgae species to be cultivated. Concerning the application of the biomass, legal aspects and impurities originating from digestate must be considered. Furthermore, microalgae species and their application fields are essential criteria when selecting downstream processing methods (harvest, disintegration, dehydration, product purification). Microalgae grown on digestate can be used to produce various products (e.g., bioenergy, animal feed, bioplastics, and biofertilizers). This review gives insight into the origin and composition of digestate, processing options to meet requirements for microalgae cultivation and challenges regarding downstream processing and products.


Conference contributions | 2012

Direct Heating with Logwood ‐ State of the Art, Opportunities and Challenges

Schmidl C, Haslinger W. Direct Heating with Logwood ‐ State of the Art, Opportunities and Challenges, 20th European Biomass Conference 2012, 18th-22nd of June 2012, Milano, Italy.

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Other Presentations | 2012

Domestic Heating with Biomass – State‐of‐the‐Art and Strategic Research Needs

Haslinger W. Domestic Heating with Biomass – State‐of‐the‐Art and Strategic Research Needs, Annual Conference Renewable Heating and Cooling 2012, 26th-27th of April 2012, Copenhagen, Denmark.

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Peer Reviewed Scientific Journals | 2016

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

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

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