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Other publication | 2013

Innovative Energietechnologien in Österreich - Marktentwicklung 2013

Biermayr P, Eberl M, Enigl M, Rechner H, Kristöfel C, Leonhartsberger K, Maringer F, Moidl S, Strasser C, Weiss W, Wörgetter M. Innovative Energietechnologien in Österreich – Marktentwicklung. Berichte aus Energie und Umweltforschung. 2013:26.

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Conference Papers | 2017

Innovative flexible grate solutions for future biomass combustion appliances

Feldmeier, S., Wopienka, E., Schwarz, M., Mehrabian Bardar, R.: Innovative flexible grate solutions for future biomass combustion appliances. (European Biomass Conference and Exhibition 2017, Stockholm).

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The energetic utilization of alternative fuels (short rotation coppice, miscanthus), agricultural by-products (straw, corn cobs) or biomass residues (nut shells, coffee grounds) becomes of increasing interest. Due to variations in fuel properties – and the ash content in particular – biomass fuels considerably influence the conditions in the combustion zone and especially in the fuel bed. Usually, state-of-the-art combustion appliances are optimized for a particular fuel quality and typically approved only for utilization of standardized wood pellets or wood chips. Research activities within the GrateAdvance project focus on fuel flexible grate technologies being capable of adapting conditions in the combustion zone by a systematic and targeted adjustment of grate parameters in order to minimize emissions and slagging problems, thus setting the basis for a new generation of biomass technologies. Moreover, a novel control concept will ensure optimal combustion conditions for any biomass fuel, and specifically adjust to relevant fuel properties.


Peer Reviewed Scientific Journals | 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.


Conference contributions | 2015

Innovative room heating technologies

Schmidl C. Innovative room heating technologies, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (oral presentation)

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Peer Reviewed Scientific Journals | 2019

Input data reduction for microgrid sizing and energy cost modeling: Representative days and demand charges

Fahy K, Stadler M, Pecenak ZK, Kleissl J. Input data reduction for microgrid sizing and energy cost modeling: Representative days and demand charges. Journal of Renewable and Sustainable Energy. 2019.11:065301

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Computational time in optimization models scales with the number of time steps. To save time, solver time resolution can be reduced and input data can be down-sampled into representative periods such as one or a few representative days per month. However, such data reduction can come at the expense of solution accuracy. In this work, the impact of reduction of input data is systematically isolated considering an optimization which solves an energy system using representative days. A new data reduction method aggregates annual hourly demand data into representative days which preserve demand peaks in the original profiles. The proposed data reduction approach is tested on a real energy system and real annual hourly demand data where the system is optimized to minimize total annual costs. Compared to the full-resolution optimization of the energy system, the total annual energy cost error is found to be equal or less than 0.22% when peaks in customer demand are preserved. Errors are significantly larger for reduction methods that do not preserve peak demand. Solar photovoltaic data reduction effects are also analyzed. This paper demonstrates a need for data reduction methods which consider demand peaks explicitly.

 


Conference contributions | 2012

Integrated carbon capture (CC), field tests and further perspectives in industrial

Martini S. Integrated carbon capture (CC), field tests and further perspectives in industrial, 5 th international Freiberg Conference on IGCC & XtL Technologies 2012, 21st-24th of May 2012, Leipzig, Germany.

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Contributions to trade journals | 2014

Integrating mitigation and adaptation into development: The case of Jatropha curcas in sub-Saharan Africa

Muys B, Norgrove L, Alamirew T, Birech R, Chirinian E, Delelegn Y, et al. Integrating mitigation and adaptation into development: The case of Jatropha curcas in sub-Saharan Africa. GCB Bioenergy. 2014;6(3):169-71.

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Conference contributions | 2020

Integrating steam gasification into established infrastructure in the pulp and paper industry

Karl T, Integrating steam gasification into established infrastructure in the pulp and paper industry. 6th Central European Biomass Conference, 22-24 January 2020, Graz.

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Conference contributions | 2012

Integration Aspects in the Next Generation of CHP Plants Based on Gasification

Rauch R. Integration Aspects in the Next Generation of CHP Plants Based on Gasification, International Seminar on Gasification 2012, 18th-19th of October 2012, Stockholm, Sweden.

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Peer Reviewed Scientific Journals | 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 Scientific Journals | 2021

Integration of market aspects into material development: approach and exemplification for a wood composite

Fuhrmann M, Schwarzbauer P, Hesser F. Integration of market aspects into material development: approach and exemplification for a wood composite. European Journal of Wood and Wood Products. 2021. https://doi.org/10.1007/s00107-021-01697-z

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Due to a variety of applications and complex requirements in specific fields of use, the number of different materials is increasing. Thereof, the majority fails at the stage of market introduction, because the focus of material development is mostly on technical aspects, while market aspects are often neglected. One possible way of market introduction is material substitution. Thereby, requirements a material needs to meet are well known. However, a certain market focus on material development would be helpful regarding the final goal of the customer satisfaction. Therefore, this study presents an approach, which aims at guiding the technical material development and thus starts one stage earlier than most other studies, which focus on market introduction. A multi-stage approach helps integrating market aspects into material development, using the following methods: (1) method of Ashby to compare materials from a technical point of view and identify theoretically substitutable material groups and potential applications, (2) market data research and comparison for the identification of attractive markets, (3) method of Kano to classify material requirements and prioritize the optimization of material properties to satisfy the customers in selected markets. This approach is showcased and discussed using the example of an innovative wood composite under development, where it represented an aiding tool for guiding the further material development. An adaptation to any other material is possible at each of the three stages, although there are some limitations, which have to be considered, for example the selection of technical properties for the material comparison.


Conference contributions | 2015

Integration of Oxidative Honeycomb Catalysts in Firewood Stoves - Perfomance Analysis, Safety Aspects and Long Term Durability

Reichert G, Schmidl C, Schwabl M, Stressler H, Sturmlechner R, Haslinger W. Integration of Oxidative Honeycomb Catalysts in Firewood Stoves - Perfomance Analysis, Safety Aspects and Long Term Durability, 23rd European Biomass Conference 2015, 1st-4th of June 2015, Vienna, Austria. (oral presentation)

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Conference contributions | 2010

Integration of Sensor Based Sorting in the Mechanical Treatment of Municipal and Commercial Waste

Brooks L, Ragossnig A, Meirhofer M, Pieber S. Integration of Sensor Based Sorting in the Mechanical Treatment of Municipal and Commercial Waste, Orbit 2010, 29th of June-3rd of July 2010, Heraklion, Crete.

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Due to the Austrian legal framework provided by the landfill ordinance from 1996 which has been fully implemented by January 1st 2009, waste with an organic content higher than 5% TOC (total organic carbon) must not be dumped without prior treatment in order to avoid greenhouse gas emissions from landfills. Besides thermal treatment also mechanical-biological treatment (MBT) has been enabled by the regulator as an eligible treatment approach, whereby waste to be dumped must comply with the threshold of 6,600 kJ/kg DM (dry mass) stipulated for the upper caloric value. This is a tough challenge due to the high energy content of plastic, paper, cardboard and wood components which are still contained in the low caloric output fraction of the MBT of municipal and commercial waste as those materials have a much higher upper caloric value. From the resource conservation point of view the utilization of these waste components for energetic purposes is desirable too.
The implementation of the legal framework as one measure battling climate change as well as constantly rising energy prices have caused a change from pure waste management with the intention to reduce the organic content in waste, to the point where high caloric components have become a substitute for fossil fuels in certain sectors of industries (cement industry, pulp & paper industry, steel works, etc). Using waste derived or so-called refuse derived fuel (RDF) demands high purity in order to secure environmental standards as well as product quality and therefore process related requirements have to be met. This can be achieved by 1) qualified selection of the waste streams into the treatment plants and 2) by processing technologies allowing the separation of wanted/unwanted waste components within the plant concept. In cooperation with a regional waste management company, responsible for the treatment and disposal of 82,000 t/a of municipal and commercial waste and operator of a MBT plant as well as a landfill, further processing of a specific output waste stream from the MBT plant was analysed in order to allow an optimized routing of the output streams including the energetic utilization of high caloric components and landfilling of low caloric and inert components. Experiments using the innovative treatment technology of sensor based sorting were conducted with a waste stream characterized by 59 % high caloric components (polymers, paper and cardboard, wood), 8 % other organic components, 27 % inert waste, 3 % metals and 3 % other waste (textiles, fine fraction < 20 mm, hazardous waste). The particle size of that particular waste stream is 20-80 mm. The sorting machine was a NIR (near infrared) multiplex sensor based sorting system with a wavelength of 1,400-1,900 nm in pilot scale. Results showed that by varying the parameters air pressure (bar), scanning speed (Hz), blow out time (ms) and the evaluation of spectra, about 76 % of polymers, 86 % of wood and 96 % of paper and cardboard of the input fractions could be separated from the inorganic waste stream. The remaining components were inert waste (53%), metals (3 %), other waste (textiles, contaminated waste, fine fraction < 20 mm) (3 %), but also dark polymers (12 %), undefined organics (e.g. fruits, vegetables) (9%) and still 20 % of polymers, wood, paper and cardboards. Due to the high portion of organic components and dark polymers in the stream, the threshold of 6,600 kJ/kg DM defined for waste to be landfilled could not be met. Further experiments with a more sensitive sorting system, a spectral imaging technology (wavelength up to 2,500 nm), are planned, supposing that the rejection rate of dark polymers could be increased. Theoretical considerations have shown that in that case the threshold could be met.


Other Presentations | 2012

Integration vom Hydroprocessing in die Fischer-Tropsch Synthese

Götz, F. Integration vom Hydroprocessing in die Fischer-Tropsch Synthese, Master Thesis, Technische Universität Wien, Vienna, Austria, 2012.

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Conference contributions | 2020

Integration von Biogas in Bioprozesse - Nährstoffrückführung und Energiegewinnung

Drosg B. Integration von Biogas in Bioprozesse - Nährstoffrückführung und Energiegewinnung. 6th Central European Biomass Conference (oral presentation). 2020.

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Contributions to trade journals | 2014

Integration von Oxidationskatalysatoren in Holzöfen

Reichert G, Schmidl C. Integration von Oxidationskatalysatoren in Holzöfen, 13. Holzenergiesymposium 2014, 12th of September 2014, Zürich, Schweiz. pp 77-92. (peer reviewed)

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Batch-wise operated wood stoves for room heating purposes are popular and widespread in Europe. Beside economic and ecological reasons they are also very important for reaching the European CO2 emission targets. However, since they contribute significantly to harmful gaseous as well as particulate emissions, they have to be optimized towards clear emission reduction in real life operation. Catalysts integrated in wood stoves can significantly contribute to reach this target. The results of this study showed an emission reduction potential of
integrated ceramic and metallic honeycomb catalysts of around 30 % to 99 %. Thereby the highest reduction potential was investigated for CO emissions (reduction rate 75 % to 99 %), followed by reductions of VOC emissions (reduction rate 40 % to 60 %) and reductions of PM emissions of around 30 % to 40 %. Long term tests and safety test series lead to the conclusion that integrated catalysts have to be cleaned regularly in order to prevent blocking and to guarantee optimal reduction performance.


Other Presentations | 2014

Integration von Thermogeneratoren in einen Scheitholzofen zur Eigenstromversorgung der automatischen Luftklappenregelung

Mair, C. Integration von Thermogeneratoren in einen Scheitholzofen zur Eigenstromversorgung der automatischen Luftklappenregelung, Diploma Thesis, Technische Universität Wien, Vienna, Austria, 2014.

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Peer Reviewed Scientific Journals | 2017

Intelligent Heat Networks: First Results of an Energy-Information-Cost-Model

Lichtenegger K, Hoeftberger E, Schmidl C, Woess D, Proell T, Halmdienst C. Intelligent Heat Networks: First Results of an Energy-Information-Cost-Model. Sustainable Energy, Grids and Networks. September 2017;11: 1-12.

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Integrating additional renewable heat sources into district heating networks can have several beneficial effects, but it also requires more sophisticated control strategies than supply by only one central plant. In this article, we study the integration of prosumers (i.e. buildings which have both the capacity to produce and the need to consume energy, here heat) into heat distribution grids.

This study is performed with a simplified model, based on energy and information flows. The prosumers can act autonomously, based on a price communicated by the central heat plant. This price is determined based on the benefit for the network by additional heat feed-in and is regularly updated. This leads to an interlocking of a physical/technical and an economic feedback loop. The control parameters are optimized by using a stochastic optimization algorithm, based on simulation runs for one typical week in winter, spring and summer.

We compare the results with standard setups (heat network with only consumers, central heat generation and additional heat-producing building disconnected from the grid) and obtain an improvement concerning fuel consumption in most and concerning emissions in many situations. While economic benefits are achieved in most scenarios, it is a non-trivial task to construct a market model that distributes these benefits in a fair way between the central heat plant and the prosumers.


Peer Reviewed Scientific Journals | 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 Scientific Journals | 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.


Scientific Journals | 2019

Interrelation of Volatile Organic Compounds and Sensory Properties of Alternative and Torrefied Wood Pellets

Poellinger-Zierler B, Sedlmayer I, Reinisch C, Hofbauer H, Schmidl C, Kolb LP, Wopienka E, Leitner E, Siegmund B. Interrelation of Volatile Organic Compounds and Sensory Properties of Alternative and Torrefied Wood Pellets. energy & fuels 2019.33:5270-5281.

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The increasing demand for wood pellets on the market, which is caused by their excellent combustion properties, inspires the production as well as the utilization of alternative biomass pellets as fuel. However, the emission of volatile organic compounds gives pellet materials a distinct odor or off-odor, which is directly perceived by the end user. Thus, there is an urgent need for knowledge about the emitted volatile organic compounds and their potential formation pathways as well as their contributions to odor properties of the pellets. In this study, pellets made of biomass energy crops (i.e., straw or miscanthus), byproducts from the food industry (i.e., rapeseed, grapevine, or DDGS (dried distillers grains with solubles from beer production)), or eucalyptus, as well as torrefied pinewood and torrefied sprucewood were investigated with respect to the emitted volatile compounds and their possible impact on the pellet odor. Headspace solid-phase microextraction in combination with gas chromatography–mass spectrometry was used to enrich, separate, and identify the compounds. Techniques used in sensory science were applied to obtain information about the odor properties of the samples. A total of 59 volatile compounds (acids, aldehydes and ketones, alcohols, terpenes, heterocyclic compounds, and phenolic compounds) were identified with different compound ratios in the investigated materials. The use of multivariate statistical data analysis provided deep insight into product–compound interrelation. For pellets produced from bioenergy crops, as well as from byproducts from the food industry, the sensory properties of the pellets reflected the odor properties of the raw material. With respect to the volatiles from torrefied pellets, those volatiles that are formed during the torrefaction procedure dominate the odor of the torrefied pellets covering the genuine odor of the utilized wood. The results of this work serve as a substantiated basis for future production of pellets from alternative raw materials.


Peer Reviewed Scientific Journals | 2016

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

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

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Peer Reviewed Scientific Journals | 2020

Investigation of solid oxide fuel cell operation with synthetic biomass gasification product gases as a basis for enhancing its performance

Pongratz G, Subotić V, Schroettner H, Stoeckl B, Hochenauer C, Anca-Couce A, Scharler R. Investigation of solid oxide fuel cell operation with synthetic biomass gasification product gases as a basis for enhancing its performance. Biomass Conversion and Biorefinery.2020.

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Solid oxide fuel cells represent a promising technology to increase the electrical efficiency of biomass-based combined-heat-power systems in comparison to state-of-the-art gas engines, additionally providing high temperature heat. To identify favorable fuel gas compositions for an efficient coupling with gasifiers at low degradation risk is of major importance to ensure stability, reliability, and durability of the systems used, thus increasing attractiveness of electricity production from biomass. Therefore, this study presents a comprehensive analysis on the influence of main gas components from biomass gasification on the performance and efficiency of a cell relevant for real application. An industrial-size electrolyte supported single cell with nickel/gadolinium-doped ceria anode was selected showing high potential for gasifier-solid oxide fuel cell systems. Beneficial gas component ratios enhancing the power output and electric efficiency are proposed based on the experimental study performed. Furthermore, the degradation stability of a SOFC fueled with a synthetic product gas representing steam gasification of woody biomass was investigated. After 500 h of operation under load at a steam-to-carbon ratio of 2.25 in the fuel gas, no performance or anode degradation could be detected.


Peer Reviewed Scientific Journals | 2015

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

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

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


Technical 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.