| 1. |
- Hermansson, Johan, 1679-1737, et al.
(författare)
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Dissertatio gradualis, de philosophia sectaria, quam, consensu ampliss. Colleg. Philos. in Regia Academia Upsaliensi, præside celeberrimo viro, Dn. Johanne Hermansson ... publico eruditorum examini submittit alumnus regius, Sveno Hof, V. Gothus. In audit. Gustav. maj. ad d. 22 Maji. Anni MDCCXXXI. Horis ante meridiem solitis.
- 1731
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)
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| 2. |
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| 3. |
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| 4. |
- Boman, Christoffer, et al.
(författare)
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Development of innovative small(micro)-scale biomass-based CHP technologies
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- To enhance the overall efficiency of the use of biomass in the energy sector in Europe, the large electricity production potential from small-scale biomass heating systems should be utilised. So far, no technologically sound (in terms of efficiency and reliability) and economically affordable micro- and small-scale biomass CHP technologies are, however, available. Therefore, the present ERA-NET project (MiniBioCHP) aimed at the further development and test of new CHP technologies based on small-scale biomass combustion in the electric capacity range between some W and 100 kW. Within the project, an international consortium consisting of 12 partners from 4 countries, including university institutions, institutes and industry (both engineering and manufacturing), collaborated closely to perform high level R&D on three promising micro/small-scale biomass based CHP technologies which are covering a broad range of applications in the residential heating sector. The Austrian engineering company BIOS, coordinated the international project. The project was based on earlier basic research and development work related to these promising new technologies and aimed at the achievement of a technological level which allows a first (commercial) demonstration after the end of the project. The three CHP concepts included in the MiniBioCHP project were;1. Pellet stoves with a thermoelectric generator (TEG)2. Small-scale biomass boilers (10-30 kWth) with a micro-ORC process3. High temperature heat exchanger (HT-HE) for an externally fired gas turbine (EFGT)The Swedish part of the project was focused on the development of the concept of biomass based EFGT with dedicated R&D activities related to the development of the HT-HE system. The Swedish project consisted of the research partners Umeå University (project leader), Luleå University of Technology, Chalmers University of Technology and RISE Research Institutes of Sweden, together with the industrial partners Enertech AB/Osby Parca and Ecergy. The expertise of the Swedish partners regarding ash related problems, grate boiler combustion and modelling, deposit formation and high temperature corrosion, were combined with the know-how of a Polish partner regarding HT-HE design, construction, testing and optimisation.The HT-HE is the most crucial component in EFGT processes significantly influencing the investment costs, availabilities as well as the efficiencies that can be achieved. With a thermal capacity from several hundred kW up to 2-3 MWth) the CHP technology based on a biomass boiler and an EFGT is suitable for district heating systems, or process heat consumers. The electricity produced by the gas turbine (up to some 100 kWel) can be used to cover the own electricity consumption of a company and/or fed into the grid. Even though the concept of biomass based EFGT has been an interesting alternative for small-scale CHP production for some decades, and R&D activities have been undertaken, tackling both economic and technical aspects, only a few pilot-plants have been in operation and no initiative has so far reached the level of commercial implementation. Thus, the concept of EFGT fed with biomass is still considered to be in a rather early development stage and the main technical challenges are related to alkali deposit induced corrosion and thermal stress of the HT-HE material, turbine design/operation and system integration.Within the present project, a HT-HE prototype aimed for an EFGT system was therefore designed, constructed and successfully tested at flue gas temperatures up to 900°C. Thus, appropriate guidelines for a compact design of the HT-HE and recommendations have been worked out to minimize thermal stresses as well as ash related problems regarding ash deposit formation and high temperature corrosion in a biomass boiler system. Furthermore, different concepts for the overall biomass based EFGT system have been worked out and evaluated. The outcome of the project will hopefully be used in the further development work and form the basis for a first testing and demonstration plant within the coming years.
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| 5. |
- Bäck-Pettersson, Siv, 1946, et al.
(författare)
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FOU-kompetensförsörjningsprogram för sjuksköterskor i Fyrbodal
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sammanfattning Betydelsen av FoU-kompetensförsörjningsprogrammet som varit en medveten och strategisk satsning inom FoU-området kan sammanfattas på följande sätt: Deltagarnas behållning och föreskriven akademisk utveckling har haft en närmast hundraprocentig måluppfyllelse och gett kliniskt verksamma sjuksköterskor en bra start på sin akademiska karriär. Programmet illustrerar ett effektivt sätt att stimulera sjuksköterskors livslånga lärande genom att bygga upp förmågan att genomföra och tillämpa omvårdnadsforskning i klinisk praktik. Programmet har också bidragit till utvecklingen av kompetenta handledare för studenter under utbildning. Flertalet av deltagarna har utvecklat både en önskan om och kompetens för att ta på sig ledande uppdrag såväl inom den egna verksamheten som i gränsöverskridande projekt både inom Fyrbodal och nationellt. Programmet har medverkat till att bryta revirtänkande och kan bidra till en mer öppen och gränsöverskridande kultur inom Fyrbodalområdets hälso- och sjukvård. Det har även medverkat till att deltagarna skaffat sig en helhetssyn på och förståelse för olika vårdverksamheter. Programmets design kan användas för att utveckla såväl professionell som vetenskaplig kompetens och kan med fördel användas inom andra yrkesgrupper med medellång vårdutbildning, eller för en tvärprofessionell grupp.
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| 6. |
- Bäck-Pettersson, Siv, 1946, et al.
(författare)
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Nurses´Experiences of participation in a research and development programme
- 2013
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Ingår i: Journal of Clinical Nursing. - : Wiley. - 0962-1067 .- 1365-2702. ; 22:7-8, s. 1103-1111
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Tidskriftsartikel (refereegranskat)abstract
- Aims and objectives. To describe clinical nurses’ experience of participating in a Research and Development (R&D) programme and its influence on their research interest and ability to conduct and apply nursing research. Background. To stimulate nurses’ research interest and to overcome barriers for building research capacity in nursing, there is a need for sustainable research programmes. A two-year programme was designed for nurses, to take part in both an academic education for master and research seminars and workshops to conduct a research project from idea to publication. Design. A qualitative approach using using focus group interviews. Methods. Registered nurses (n = 12) with a bachelor’s degree in nursing, participated. Data were collected in focus group interviews, after one year and when the programme ended. Content analysis was used to analyse the data. Results. The findings consist of two themes: being a traveller in the world of nursing research, which included three categories, and experiencing professional growth as a result of nursing research training, in both cases focusing on the experience of students involved in a cohesive programme which included four categories: discovering new dimensions of clinical nursing practice; selected and confirmed; supported by professional others; development of professional self-concept. Conclusions. To support early career researchers, there is a need for strong leadership, an organisational and supportive infrastructure underpinning research capability building in nurses. In this context, research strategies, programmes and collaboration between leaders of academia and clinical institutions appear to be essential. Relevance to clinical practice. The R&D programme illustrates an effective way of stimulating nurses’ lifelong learning by building the capacity to conduct and apply nursing research in clinical practice. The structure of the programme can be used as a model in other contexts.
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| 7. |
- Dahl, Jan, et al.
(författare)
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Use of video-based Particle Image Velocimetry technique for studies of velocity fields in a water heat storage vessel
- 1995
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Ingår i: Experiments in Fluids. - 0723-4864 .- 1432-1114. ; 18:5, s. 383-388
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Tidskriftsartikel (refereegranskat)abstract
- A video-based Particle Image Velocimetry technique has been developed. The technique is particularly suitable for measurement of small velocities, below 3 cm/s. It has proved to be useful for the documentation of non-stationary velocity fields in a scaled-down model of a water heat storage vessel. An ordinary video camera is used to record the in-plane movements of particles in a light sheet in seeded water. The hardware used, the experimental method and the accuracy of the method are discussed. The use of two commercially available software packages (NIH-Image and IGOR) for the analyses is described. Examples of velocity fields are presented, showing that the measuring technique can be used for studies of mixing near the inlet of the storage vessel and exchange of water between the boundary layer and the core.
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| 8. |
- Fahnestock, Jesse, 1974-, et al.
(författare)
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RISEnergy: Roadmaps for energy innovation in Sweden through 2030
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- RISE Research Institutes of Sweden is a group of research and technology organisations. RISE is a leading innovation partner working global cooperation with academia, enterprise and society to create value, growth and competitiveness through research excellence and innovation.In the area of Energy, RISE has developed innovation Roadmaps covering:Energy Efficient TransportElectric Power SystemEnergy Efficient and Smart BuildingsSustainable Thermal ProcessesEfficient Energy Use in IndustryDecarbonisation of Basic IndustriesThese Roadmaps describe development pathways for technologies, non-technical elements (market design, user behaviours, policies, etc.) and key actors that deliver on a plausible, desirable vision for each respective innovation area in 2030. These Roadmaps are intended to support RISE’s strategic planning and development, but should be relevant reading for anyone interested in energy innovation in Sweden.
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| 9. |
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| 10. |
- Furborg, Johan, et al.
(författare)
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Vedkaminen år 2020 - en del av boendemiljön
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Wood Stove year 2020 - a part of the living environmentThis project is a collaboration between Nibe AB / Contura and SP Technical Research Institute of Sweden. Based on earlier evaluations of six different technology tracks, three tracks were selected to further evaluate: CFD modeling, active control and catalyst technology, with the long term goals of particle emission, control of maximum output and long burning time. A literature review of available sensors for O2, CO and hydrocarbons have been conducted followed by a market research, focusing on developments during the last decade and experiences from biomass combustion. Sensors were long-term tested. The lambda probe works well and is affordable, while sensors for unburnt gases still need to be further optimized for accuracy and long-term stability and also become less expensive to be of practical use. Active control has been applied to a prototype and evaluated with good results. In further work with active control, emphasis should be on safety. A CFD method for stove combustion has led to an industrial application with significant cuts in time and resources. Advanced CFD simulation has been used to examine the impact of furnace temperature on wood conversion and how wood log size can be used to counteract an accelerating power output. Simulation results show that log size has good potential to contribute to an improved combustion, but should be combined with further design of the stove. A rig for evaluation of catalyst coatings has been built and experimental results are promising. CO was in principle eliminated from the flue gas and hydrocarbon concentration were reduced down to a level equivalent to 25-70% of the original content.
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| 11. |
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| 12. |
- Ghirelli, Federico, 1971, et al.
(författare)
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Reactor residence time analysis with CFD
- 2006
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Ingår i: Progress in computational fluid dynamics. ; 6:4/5, s. 241-247
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: The residence time of the fluid in a reactor can be analysed with at least three differentcomputational methods:(a) Eulerian simulation of the residence time measurements(b) solution of the Eulerian transport equation for residence time(c) Lagrangian particle tracking.Methods (a) and (c) are compared with analytical and experimental data from a pilot lagoon forvalidation, and the superiority of the Eulerian approach is demonstrated. Method (b), which hasbeen validated in earlier studies, is applied to study the flow in the secondary combustionchamber of a biomass grate furnace. An inefficiently exploited zone of the furnace is identified,and a change in operating conditions, aimed at improving the reactor utilisation, is discussed.
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| 13. |
- Gustavsson, Lennart, et al.
(författare)
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Kvalitetssäkring av bränslepellets - system och erfarenheter
- 2011
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Rapport (refereegranskat)abstract
- Inom detta arbetspaket har principer och underlag för ett kostnadseffektivt och tillförlitligt kvalitetssäkringssystem för pellets tagits fram. Systemet skall säkerställa att det bränsle som levereras till kund möjliggör stabil och fullgod förbränningsteknisk funktion och inte förorsakar driftsstörningar eller stopp. Befintliga kvalitetssäkringssystem och standarder på nationell och internationell nivå har inventerats, analyserats och sammanställts. Kontakter har tagits med ett större urval pelletstillverkare och nyckelpersoner med insikt i området, och deras erfarenheter av och synpunkter på kvalitetssäkringssystem har kartlagts dels i form av telefondiskussioner, dels i form av en enkät. Vid analysen av befintliga system har tonvikten lagts på främst det nya europeiska ENplus-systemet, det tysk-österrikiska DINplus-systemet, det nordiska miljömärkningssystemet Svanen och det nya amerikanska PFI-systemet. Omfattning och gränsdragningar, strukturell uppbyggnad och ingående krav avseende råvaror, processer, produkt och hantering har analyserats och jämförts. Slutsatserna är att systemen har väsentliga likheter men också skillnader som kan vara väsentliga. Det system som bedöms vara mest näraliggande att anknyta till är ENplus-systemet, dock inte nödvändigtvis i alla detaljer eller kravnivåer. Den genomförda enkäten visar att det stora flertalet av de tillfrågade pelletproducenterna arbetar aktivt med kvalitetsfrågor, samt att dessa tillsammans med tillfrågade nyckelpersoner inom pelletkedjan är positivt inställda till ett frivilligt certifieringssystem riktat mot villasegmentet. En direkt anslutning till ENplus-systemet tolkas dock som icke önskvärt. Systemet anses för kostsamt och byråkratiskt för en certifiering av något som idag redan uppfylls på den svenska marknaden. Däremot anser merparten att man genom anpassningar – främst beträffande administration, avgifter och strykning/tillägg av olika kravdelar – kan skapa ett system som är lämpat för den svenska marknaden. Ett sådant system kan bygga på svensk/europeisk standard för pelletkvalitet – till vissa delar förbättrat – samt generella krav i linje med ISO 9001, i vilka råvarukvalitet, produkttransport och produktion bör utgöra de viktigaste länkarna. För att få en bred acceptans för ett svenskt QA-system är det enligt enkätsvaren av stor vikt att en mer ingående jämförelse mellan ENplus, PFI och EN 15234 genomförs tillsammans med representanter från branschen, så att en modifierad version anpassad för den svenska marknaden kan utkristalliseras. Det utfärdande organet bör därför vara väl förankrat i branschen och ha god transparens. Som utfärdare föreslås därför Svebio. Enkätsvaren antyder också att vissa av parametrarna i de europeiska standarderna för produktkvalitet är lågt satta jämfört med svensk normal kvalitetsnivå – exempelvis asksmältpunkten. Ett svenskt QA-system skulle därmed kunna utgå ifrån europeisk standard – A1, A2 och B – men även innefatta ett högre kvalitetssteg för svenska produkter. En viktig del i ett QA-system är definiering av långsiktiga kvalitetsmål, samt hur dessa skall uppnås. Detta ingår inte i något av de befintliga systemen, men blir troligen aktuellt för att kunna bibehålla hög och jämn produktkvalitet vid breddad råvarubas, exempelvis skogsavfall och agrara produkter. I samtalen med PiR och i enkätsvaren har tydligt framkommit att branschen efterfrågar ett motkrav på brännarutrusning (villasegmentet) om ett QA-system skall bli aktuellt. Man menar att högre krav borde ställas på EN/P/kvalitetsmärkning, kontinuerlig trimning av driften samt införande av O2-styrning för att en hög och jämn pelletkvalitet skall vara motiverad.
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| 14. |
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| 15. |
- Hermansson, Daniel, et al.
(författare)
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Oberoendehotet är överdrivet
- 2017
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Ingår i: Balans. - 0346-8208. ; :7, s. 43-44
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Det finns anledning att ifrågasätta det instinktiva motståndet mot marknadsföring av revisionstjänster. Det skriver studenterna Daniel Hermansson och Rikard Hjalmarsson samt deras handledare Sven-Olof Yrjö Collin, vid Linnéuniversitetet. Affärsmannaskap är i sig inte ett avgörande hot mot revisionskvaliteten, menar de.
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| 16. |
- Hermansson, Hélène, et al.
(författare)
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A Three-Party Model Tool for Ethical Risk Analysis
- 2007
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Ingår i: Risk Management. - : Springer Science and Business Media LLC. - 1460-3799 .- 1743-4637. ; 9:3, s. 129-144
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Tidskriftsartikel (refereegranskat)abstract
- Ethical aspects are crucial in the analysis of risk, but they have often been neglected. One of the reasons for this is the lack of operational tools for the ethical analysis of risks. A model for ethical risk analysis is proposed that focuses on the ethical relationships between three critical parties (or roles) that are present in almost all risk-related decisions: the risk-exposed, the beneficiary and the decision-maker. Seven crucial questions are proposed that can be used to characterize these relationships. It is shown with examples from the railway sector how they can be used to identify the salient ethical features of risk management problems.
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| 17. |
- Hermansson, Hélène
(författare)
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Ethical aspects of risk management
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The subject of this thesis is ethical aspects of risk management. It is argued that a model for risk management needs to be developed that acknowledges several ethical aspects and most crucial among these, the individual’s right not to be unfairly exposed to risks. Article I takes as its starting point the demand frequently expressed in the risk literature for a consistent risk management. Such consistency is often assumed to be in accordance with some kind of cost-benefit analysis. It is maintained that such a model, here called the Standard Model, does not respect the rights of the individual. Two alternative models are outlined in order to better deal with this ethical weakness, the Model of Inviolable Rights and the Model of Procedural Justice. The arguments in the alternative models evolve around the separateness of individuals, rights and fair risk taking. It is claimed that the latter model, which focuses on a fair procedure, seems most fruitful to develop. Article II is a discussion of the NIMBY (Not In My Backyard) conflict, which is well known from situations of siting potentially risky facilities. Of special concern is to investigate what the ethical premises are behind the negative characterization of the NIMBY concept. It is argued that, contrary to the assumption that the total benefit should outweigh the individual’s cost, individuals in siting scenarios have rights not to be unfairly exposed to risks. Article III, which is co-authored with Professor Sven Ove Hansson, presents a three party model as a tool for ethical risk analysis. It is argued that ethical dimensions need to be acknowledged in the analysis of risks and that this is best done through a discussion of three parties that are involved in risk decisions – the risk-exposed, the beneficiary, and the decisionmaker. Seven crucial ethical questions are recognized and discussed regarding the relation between these parties. By using examples from the railway sector it is shown how the questions can be used to identify salient ethical features of risk management problems.
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| 18. |
- Hermansson, Hélène, 1973-
(författare)
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Rights at Risk : Ethical Issues in Risk Management
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- he subject of this thesis is ethical aspects of decision-making concerning social risks. It is argued that a model for risk management must acknowledge several ethical aspects and, most crucial among these, the individual’s right not to be unfairly exposed to risks. Article I takes as its starting point the demand frequently expressed in the risk literature for consistent risk management. It is maintained that a model focusing on cost-benefit analysis does not respect the rights of the individual. Two alternative models are outlined. They evolve around the separateness of individuals, rights, and fair risk taking. It is claimed that a model that focuses on a fair procedure for risk decisions seems most fruitful to develop. Article II discusses the NIMBY (Not In My Backyard) conflict. The ethical premises behind the negative characterization of the NIMBY concept are investigated. It is argued that a collective weighing of risks and benefits ignores individuals’ rights not to be unfairly exposed to risks in siting scenarios. Article III presents a three-party model tool for ethical risk analysis. The focus in such analysis is a discussion of three parties that are involved in risk decisions: the risk-exposed, the beneficiary, and the decision-maker. Seven crucial ethical questions are discerned by combining these parties pairwise. Article IV discusses a model for procedural justice for risk decisions. Two theories of deliberative democracy are explored. The first focuses on a hypothetical contract, the second argues for the actual inclusion of affected parties. It is maintained that hypothetical reasoning should mainly serve as a guide concerning risk issues that affect people who cannot be included in the decision-making process. Otherwise an interactive dialogical reasoning is to be preferred. Article V explores the claim that there are no real, objective risks – only subjective descriptions of them. It is argued that even though every risk can be described in different ways, involve value judgements and emotions, the ideal of objectivity should not be abandoned.
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| 19. |
- Hermansson, Sven, 1978, et al.
(författare)
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CFD modelling of bed shrinkage and channelling in fixed-bed combustion
- 2011
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Ingår i: Combustion and Flame. - : Elsevier BV. - 1556-2921 .- 0010-2180. ; 158:5, s. 988-999
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Tidskriftsartikel (refereegranskat)abstract
- Combustion of fixed fuel beds in grate furnaces is common within production of heat and power fromsolid fuels. Available theoretical and experimental experience provides a solid base of knowledge onhow a conversion model of a fuel bed, using Computational Fluid Dynamics (CFD), needs to be structuredand solved. Most existing models, however, handle the conversion in one single dimension of constantbed properties; when observing a burning fuel bed in a grate furnace it becomes apparent that the fuelbed is neither homogeneous nor uni-dimensional. In this study, a two-dimensional model of the combustionof fixed fuel beds has been developed for the purpose of studying the influence of heterogeneousfuel-bed properties on the conversion. In the model, the available experience from fuel-bed modellingby means of the sub-models for fixed-bed conversion was structured into a fluid-flow scale and into afuel-particle scale, in which new formulations describing the shrinkage of the fuel bed on a multi-particlescale was introduced. Both available and new sub-models were introduced into a pre-existing CFD-platform,in which the framework for simulating fluid flow in porous media was used to solve also the conversionrelated processes acting within the particle scales as well as within the multi-particle scales. Thecomplete model was validated with good correspondence between available measurements of temperatureand species concentration in a wood-char combustor. In addition, the modelled shrinkage was foundto well describe the observed shrinkage of the fuel bed in a combustion experiment. Results of modelsimulations by using heterogeneous bed porosity show that a porous passage through the bed risks causingchannelling in the fuel bed – a phenomenon common in modern grate furnaces and suspected tocause increased emissions of nitric oxides and unburned carbon compounds. The channelling tendencycould, however, to a large extent be reduced by grates of higher flow resistance. The natural porosityincrease attributable to the packing of particles onto a wall was shown to concentrate combustion disturbancesclose to the surface of the grate. Thus, larger changes in the porosity than caused by natural fuelpacking against a wall are needed to give rise to channels that emerge through the fuel bed.
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| 20. |
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| 21. |
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| 22. |
- Hermansson, Sven, 1978, et al.
(författare)
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Combustion Disturbances Related to the Fuel Bed in Grate Furnaces
- 2005
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Ingår i: Swedish-Finnish Flame Days 2005. - 9171781854 ; 1:1, s. 150-158
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Combustion in grate furnaces is a common method for conversion of biofuels to energy, especially in small-scale heat production. In these furnaces combustion instabilities in the fuel bed are often observed. Here, an inventory is presented of combustion disturbances found in the fuel bed in grate furnaces. The inventory was carried out by interviewing personnel responsible for operation of ten furnaces and by recording of the fuel bed in eight of them by a portable video camera. Combustion disturbances were experienced in all except one of the furnaces. The most common disturbances were burnouts in the fuel bed and channelling at the bounding furnace walls. These disturbances are affected by practical factors related to the operation of grate furnaces. Those factors are presented together with suggestions for measures to reduce the frequency and magnitude of the disturbances. Digital image analysis was used to detect and quantify the size and movement of local burnouts in the fuel bed in one of the furnaces. The method can be used to find the source of disturbances or to evaluate contra-measures against burnouts.
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| 23. |
- Hermansson, Sven, 1978
(författare)
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Detecting, Modelling and Measuring Disturbances in Fixed-bed Combustion
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Combustion of fixed fuel beds in grate furnaces is one of the most common techniques within production of heat and power from solid fuels. The grate furnace used to be a working horse for combustion of hard coal, while today the incitement of using renewable fuel sources has turned biomass and municipal waste into dominating fuel types. These fuels are more conveniently managed by the robust grate furnace than by, for example, fluidised bed or suspension boilers. However, the introduction of the, in many cases, complicated and heterogeneous biomass and waste fuels have, while at the same time subjected to increasingly stringent demands on efficiency and emission of harmful substances, given rise to diffuse challenges to the operation and design of grate furnaces. The influence of the heterogeneous fuels and the low air flow rate required for low nitric oxide emissions are, to a large extent, unclear. The outcome is that different furnaces not only rely on diverging strategies of design and operation – they also show a variety of disturbance characteristics. To make way for more efficient use of modern biomass fuels in grate furnaces, by improving the understanding of the combustion situation and disturbance characteristics, the following steps were made in this study: (1) a set of grate furnaces were investigated separating hands-on problems from underlying research oriented questions, (2) three methods for detecting and measuring disturbances in grate furnaces were developed, and (3) the fundamentals behind disturbances in the part of a fuel bed of grate furnace dominated by char conversion were addressed by mathematical modelling. The outcome of the inventory of furnaces is that fuel-bed channelling and grate material deterioration are common – the first causing increased emissions of unburned carbon compounds and nitric oxides, while the latter giving rise to high material costs and operation failures. In some furnaces, the disturbances could be detected by logical reasoning and visual observations while abated by hands-on adjustments to the fuel handling, operation conditions or grate design. The continued study adds two instruments to further improve this category: (1) a method of video recording inside furnaces to detect, quantify and fend off disturbing channelling, and (2) a new method of on-line monitoring of the fuel moisture content to detect disturbing changes in fuel moisture content during operation. Furthermore, a third developed method of analysing the residence time field of the gas flow in a furnace by mathematical modelling provides an opportunity to optimise the furnace chamber for both steady conditions and transient disturbances. The inventory of furnaces also identified some fundamental question marks concerning the conversion of the fuel bed – how channels in the fuel bed arise and how these disturbances may be avoided, also during low combustion air flow, without causing grate-material deterioration. Computational Fluid Dynamics (CFD) modelling of two-dimensional conversion of a fixed char bed was developed and used for investigating these matters, in which it was confirmed that a provoked change of bed porosity may cause process disturbing channelling. An obvious solution to avoid bed-channelling is, therefore, to create an as homogeneous fuel bed as possible. However, the structure of the fuel bed may only to a certain extent be affected; the low cost of the inferior quality fuel is, to a large extent, attributable to the fact that it is heterogeneous and, furthermore, advanced fuel pre-treatments drastically reduce the economical outcome. Thus, the most powerful parameter to avoid disturbances in a heterogeneous fuel bed is to manipulate the distribution of air by means of grate design. Here, a considerable flow resistance across the grate – an effect which may be achieved by reducing the amount and/or size of the air holes in the grate rods – was found to dampen channelling. The CFD modelling, however, indicates that the placing or shaping of these holes, under certain circumstances during the char conversion, may cause thermal and/or carburizing material deterioration – one of the most common disturbances in the inventory of furnaces. Consequently, recommendations for placing of holes along the lower part of a combustion grate, counter-acting the risk of grate material deterioration, could be given from the modelling outcome. These recommendations, which also include recirculation of flue-gases into the combustion air, may in a straight forward manner be applied to the design of future grate furnaces to improve the combustion of heterogeneous fuel beds.
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| 24. |
- Hermansson, Sven, 1978
(författare)
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Disturbances in Fixed-Bed Combustion
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Conversion of solid fuels in fixed beds is a common method for heat and power production. A frequent fixed-bed technique in small to medium scale is combustion in grate furnaces. Grate furnaces are widely used in the industrial energy branch and appreciated for their stability and simplicity of control. Also, the fuel flexibility makes the method economically attractive as an energy supplier to district heating systems. With increasing demands on combustion efficiency and fuel flexibility, it has been observed, though, that the fuel bed in grate furnaces often suffers from disturbances causing problems in the fuel bed and in the free-board above it, such as elevated emissions and increased material wear. To reduce these problems it is important to gain a deeper understanding of the processes in the fuel bed, both by practical investigations and modelling. An inventory of disturbances in the fuel bed of grate furnaces was carried out, in which interviews with operating personnel and recordings of fuel beds with a video camera, was made. The results show that disturbances in the fuel bed are very common. Most frequent is channelling in the fuel bed and at the bounding walls, which occur naturally at walls of packed beds and in connection with local changes in bed porosity. The inventory shows that a range of practical measures in the operation of grate furnaces amplify this phenomenon. Modelling of combustion in the free-board of a grate furnace and in the fixed fuel bed was performed. The free-board modelling was carried out with a numerical software, using a simplified bed model to describe the inlet conditions from the fuel bed. The results clearly emphasise the practicability of such a combination and effects that are difficult to foresee by measurements and observations are highlighted. A zone in the furnace that is poorly exploited by the combustion process was revealed by the computation, and an alternative design was evaluated. The first steps in creating a bed model that describes the processes in a burning bed of char were also taken. The model was implemented into a commercial software and enriched with model-specific functions. Emphasis was put on describing a two-dimensional flow, including spatial variations in flow conditions and their influence on bed porosity and shrinkage, which enables modelling of channel formation in fixed beds.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Hermansson, Sven, 1978, et al.
(författare)
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Measures to Reduce Grate Material Wear in Fixed-Bed Combustion
- 2011
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 25:4, s. 1387-1395
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Tidskriftsartikel (refereegranskat)abstract
- To avoid extreme temperatures and reducing conditions along combustion grate surfaces reducing the risk of grate material deterioration-the configuration and out-placing of air passages through a grate have been investigated by mathematical modeling. In the two-dimensional CFD-simulations of wood-char combustion On top of the grate, the number and width of the air passages through the grate were varied. The different grate configurations were further investigated for different air flux rates and for the recirculation of flue gases to the combustion air. The results of the simulation; show that the maximal temperature in the grate is sensitive to the amount of air fed to the bed and,,at constant air flow rate, to the entering velocity of the combustion air to the fuel bed. The possibility of using the air flow, as a control parameter in modern grate :Furnaces is limited, due to a general wish to reduce the air flow through the grate to reduce nitric oxide emissions. Extreme temperatures in the grate should, therefore, according to the modelin;, be avoided by making sure that the entering velocity of the air to the Fuel bed is sufficiently high. Practically, this can be achieved by reducing the number of passages in the grate, or by introducing flue-gas recycling. However, to avoid areas of reducing conditio as along the grate, the number of passages should not be reduced further than resulting in a maximal distance of 4-5 cm between them, when working with pure air.
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| 29. |
- Hermansson, Sven, 1978, et al.
(författare)
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On-line monitoring of fuel moisture-content in biomass-fired furnaces by measuring relative humidity of the flue gases
- 2011
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Ingår i: Chemical Engineering Research and Design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 89:11, s. 2470-2476
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Tidskriftsartikel (refereegranskat)abstract
- Combustion of biomass for heat and power production is continuously growing in importance, because of incentivesfor replacing fossil energy resources with renewable ones. In biomass combustion, the moisture content of the fuel isan essential operation parameter, which often fluctuates for biomass fuels. Variation in moisture content complicatesthe operation of the furnaces and results in an uncertainty in the energy content of the fuel delivered to a plant.The fuel moisture-content in a furnace may be determined either by direct measurement on the entering fuel or bymeasuring the moisture and oxygen contents of the flue gases deriving the moisture content of the fuel. However,reliable methods of a motivated cost for the small to medium-scale furnaces are today not available. An exception isif the furnace is equipped with flue-gas condenser, which can be used to estimate the moisture content of the fluegases. A limitation of this method is, though, that not all furnaces have flue-gas condensers and that the measuredsignal has an inherent time delay.In thiswork, measurement of the relative humidity (RH) of the flue gases froma furnace is investigated as the centralcomponent in the on-line monitoring of the moisture content of the fuel in a furnace. The method was analysedwith humid air in a laboratory environment and tested for accuracy and dynamical behaviour in two biomass-firedheat-production units, one circulating fluidised-bed boiler (CFB) and one grate furnace. The results show that themethod, which is easy to calibrate on site, can be used to predict the moisture content of the biomass fuel in thegrate furnace with very good precision (
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| 30. |
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| 31. |
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| 32. |
- Hermansson, Sven, 1978, et al.
(författare)
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Structural collapses and inhomogeneous flow conditions in fixed-bed conbustion
- 2007
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Ingår i: Proceedings of the American-Japanees Flame Research Committees International Symposium.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Combustion in fixed beds, such as in grate furnaces, often suffers from problems with inhomogeneous flow conditions through the fuel bed. The effect is also referred to as channelling and it is believed to cause elevated emission levels and increased ware on grate and furnace material. The inhomogeneous flow is primarily caused by inhomogeneous fuel properties in the fuel bed, or as a result of the design of the air injection through the grate. In addition, the fuel properties change during the conversion processes. During the conversion of a batch of wood pellets, it has been observed that both a linear increase in bed porosity and sudden structural collapses occur. This dynamic behaviour is believed to play an important role for the formation of inhomogeneous bed properties. In this work, a computational fluid-dynamics model is used to evaluate the combustion of a batch of wood char. It takes into account inhomogeneous flow conditions, inhomogeneous fuel-bed properties and also the collapse processes that occur in fuel beds. The results show that the inhomogeneous flow conditions, in combination with bed collapse, causes a channel-like flow in the fuel bed. When disabling the collapse processes and letting the conversion result only in linear shrinkage at constant porosity, the channelling is dampened. It can, hence, be concluded that the collapse processes inside a fuel bed play have influence on the formation of channelling flow in fixed beds. Further investigations of the structural dynamics of fuel beds are needed to learn more about how different fuel properties affect the collapses in fuel beds and how it influences the combustion.
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| 33. |
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| 34. |
- Hermansson, Sven, et al.
(författare)
-
Testbädd Mellanskalig Biorbränsleförbränning - en förstudie
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Conversion of biomass to heat and power plays an important role in the transition of the Swedish energy system from fossil based to renewables. For manufacturers and users of medium scale combustion plants (0.5 – approx. 15 MWth), a spectrum of challenges are accounted with both today’s and future flexible use of modern biomass fuels. Such challenges are e.g. fuel handling and processing together with combustion instabilities caused by new fuels with resulting ware-and-tear and elevated emission levels. However, the possibilities to test and try out new innovations is very limited, which is why a Test Bed has the potential to significantly contribute to the innovation growth within the sector. The purpose of this feasibility study therefore to investigate the prerequisites for the establishment of a Test Bed for Medium Scale Biomass Combustion. The fundament of the feasibility study is a survey of the existing infrastructure for testing and innovation development of medium scale biomass combustion, which could be further developed and interconnected. Furthermore, a broad inquiry has been performed among market actors, focusing on the present and future need together with existing conditions for taking part in the development of a test bed. These first two steps has then been synthesized into recommendations on how a test bed should be developed and exploited by relevant actors. The major conclusions and recommendations of the feasibility study are: A cost efficient and innovative Test Bed system for medium scale biomass combustion could be developed by enhanced cooperation between passive test-bed like plants and systems, industrial testing plants and research activities, Development of a test bed system is hindered by the fact that there is no clear receiver of such system on the market. Stake holder cooperation is today weak, which makes common investments and financing impossible There is no economic support for the erection of new, dedicated test bed facilities for medium scale biomass combustion, Pre-treatment of biomass raw material with the purpose of enhancing fuel quality simultaneously refining products from the biomass has been found to show good potential for further development of test beds. This study therefore recommends that such investigation should be taken under consideration.
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| 35. |
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| 36. |
- Hourahine, B., et al.
(författare)
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Evidence for H2* trapped by carbon impurities in silicon
- 2001
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 308, s. 197-201
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Tidskriftsartikel (refereegranskat)abstract
- Local mode spectroscopy and ab initio modelling are used to investigate two trigonal defects found in carbon-rich Si into which H had been in-diffused. Isotopic shifts with D and 13C are reported along with the effect of uniaxial stress. Ab initio modelling studies suggest that the two defects are two forms of the CH2* complex where one of the two hydrogen atoms lies at an anti-bonding site attached to C or Si, respectively. The two structures are nearly degenerate and possess vibrational modes in good agreement with those observed.
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| 37. |
- Jannasch, Anna-Karin, et al.
(författare)
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ANALYSIS OF P2G/P2L SYSTEMS IN PITEÅ/NORRBOTTEN FOR COMBINED PRODUCTION OF LIQUID AND GASEOUS BIOFUELS : Report from an f3 project
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is the result of a collaborative project within the Swedish Knowledge Centre for Renewable Transportation Fuels (f3). f3 is a networking organization, which focuses on development of environmentally, economically and socially sustainable renewable fuels, and Provides a broad, scientifically based and trustworthy source of knowledge for industry, governments and public authorities, Carries through system oriented research related to the entire renewable fuels value chain, Acts as national platform stimulating interaction nationally and internationally.f3 partners include Sweden’s most active universities and research institutes within the field, as well as a broad range of industry companies with high relevance. f3 has no political agenda and does not conduct lobbying activities for specific fuels or systems, nor for the f3 partners’ respective areas of interest.The f3 centre is financed jointly by the centre partners, the Swedish Energy Agency and the region of Västra Götaland. f3 also receives funding from Vinnova (Sweden’s innovation agency) as a Swedish advocacy platform towards Horizon 2020. Chalmers Industriteknik (CIT) functions as the host of the f3 organization (see www.f3centre.se).
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| 38. |
- Johansson, Magnus, et al.
(författare)
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Effects of Internet-Based Cognitive Behavioral Therapy for Harmful Alcohol Use and Alcohol Dependence as Self-help or With Therapist Guidance : Three-Armed Randomized Trial
- 2021
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Ingår i: Journal of Medical Internet Research. - : JMIR Publications. - 1438-8871. ; 23:11
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Alcohol use is a major contributor to health loss. Many persons with harmful use or alcohol dependence do not obtain treatment because of limited availability or stigma. They may use internet-based interventions as an alternative way of obtaining support. Internet-based interventions have previously been shown to be effective in reducing alcohol consumption in studies that included hazardous use; however, few studies have been conducted with a specific focus on harmful use or alcohol dependence. The importance of therapist guidance in internet-based cognitive behavioral therapy (ICBT) programs is still unclear.OBJECTIVE: This trial aims to investigate the effects of a web-based alcohol program with or without therapist guidance among anonymous adult help-seekers.METHODS: A three-armed randomized controlled trial was conducted to compare therapist-guided ICBT and self-help ICBT with an information-only control condition. Swedish-speaking adult internet users with alcohol dependence (3 or more International Classification of Diseases, Tenth Revision criteria) or harmful alcohol use (alcohol use disorder identification test>15) were included in the study. Participants in the therapist-guided ICBT and self-help ICBT groups had 12-week access to a program consisting of 5 main modules, as well as a drinking calendar with automatic feedback. Guidance was given by experienced therapists trained in motivational interviewing. The primary outcome measure was weekly alcohol consumption in standard drinks (12 g of ethanol). Secondary outcomes were alcohol-related problems measured using the total alcohol use disorder identification test-score, diagnostic criteria for alcohol dependence and alcohol use disorder, depression, anxiety, health, readiness to change, and access to other treatments or support. Follow-up was conducted 3 (posttreatment) and 6 months after recruitment.RESULTS: During the recruitment period, from March 2015 to March 2017, 1169 participants were included. Participants had a mean age of 45 (SD 13) years, and 56.72% (663/1169) were women. At the 3-month follow-up, the therapist-guided ICBT and control groups differed significantly in weekly alcohol consumption (-3.84, 95% Cl -6.53 to -1.16; t417=2.81; P=.005; Cohen d=0.27). No significant differences were found in weekly alcohol consumption between the self-help ICBT group and the therapist-guided ICBT at 3 months, between the self-help ICBT and the control group at 3 months, or between any of the groups at the 6-month follow-up. A limitation of the study was the large number of participants who were completely lost to follow-up (477/1169, 40.8%).CONCLUSIONS: In this study, a therapist-guided ICBT program was not found to be more effective than the same program in a self-help ICBT version for reducing alcohol consumption or other alcohol-related outcomes. In the short run, therapist-guided ICBT was more effective than information. Only some internet help-seekers may need a multisession program and therapist guidance to change their drinking when they use internet-based interventions.TRIAL REGISTRATION: ClinicalTrials.gov NCT02377726; https://clinicaltrials.gov/ct2/show/NCT02377726.
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| 39. |
- Johansson, Magnus, et al.
(författare)
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Internet-based therapy versus face-to-face therapy for alcohol use disorder, a randomized controlled non-inferiority trial
- 2021
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Ingår i: Addiction. - : John Wiley & Sons. - 0965-2140 .- 1360-0443. ; 116:5, s. 1088-1100
-
Tidskriftsartikel (refereegranskat)abstract
- Background and aimsMost people with alcohol use disorder (AUD) are never treated. Internet-based interventions are effective in reducing alcohol consumption and could help to overcome some of the barriers to people not seeking or receiving treatment. The aim of the current study was to compare internet-delivered and face-to-face treatment among adult users with AUD.DesignRandomized controlled non-inferiority trial with a parallel design, comparing internet-delivered cognitive–behavioural therapy (ICBT) (n = 150) with face-to-face CBT (n = 151), at 3- and 6-month follow-ups.SettingA specialized clinic for people with AUD in Stockholm, Sweden. Participants were recruited between 8 December 2015 and 5 January 2018.ParticipantsA total of 301 patients [mean age 50 years, standard deviation (SD) = 12.3] with AUD, of whom 115 (38%) were female and 186 (62%) were male.Intervention and comparatorParticipants were randomized in blocks of 20 at a ratio of 1 : 1 to five modules of therapist-guided ICBT or to five modules of face-to-face CBT, delivered over a 3-month period. The same treatment material and the same therapists were used in both groups.MeasurementsThe primary outcome was standard drinks of alcohol consumed during the previous week at 6-month follow-up, analysed according to intention-to-treat. The pre-specified non-inferiority limit was five standard drinks of alcohol and d = 0.32 for secondary outcomes.ResultsThe difference in alcohol consumption between the internet and the face-to-face group was non-inferior in the intention-to-treat analysis of data from the 6-month follow-up [internet = 12.33 and face-to-face = 11.43, difference = 0.89, 95% confidence interval (CI) = −1.10 to 2.88]. The secondary outcome, Alcohol Use Disorder Identification Test score, failed to show non-inferiority of internet compared with face-to-face in the intention-to-treat analysis at 6-month follow-up (internet = 12.26 and face-to-face = 11.57, d = 0.11, 95% CI = –0.11 to 0.34).ConclusionsInternet-delivered treatment was non-inferior to face-to-face treatment in reducing alcohol consumption among help-seeking patients with alcohol use disorder but failed to show non-inferiority on some secondary outcomes.
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| 40. |
- Johansson, Magnus, et al.
(författare)
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Web-Based Self-Help for Problematic Alcohol Use : a Large Naturalistic Study
- 2017
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Ingår i: International Journal of Behavioral Medicine. - : Springer Science and Business Media LLC. - 1070-5503 .- 1532-7558. ; 24:5, SI, s. 749-759
-
Tidskriftsartikel (refereegranskat)abstract
- This observational study examined user characteristics, intervention use patterns, and variables associated with reductions in alcohol consumption for anonymous Internet help-seekers using a Web-based self-help program.A Web-based cognitive behavioral therapy (CBT) program with eight modules delivered over 10 weeks was offered to participants with at least hazardous use of alcohol according to the Alcohol Use Disorders Identification Test (AUDIT) (n = 4165). At baseline and 10-week follow-up, participants completed the Timeline-followback (TLFB), AUDIT, Drug Use Disorders Identification Test (DUDIT), Hospital Anxiety and Depression Scale (HADS), EuroQol-5 dimension (EQ-5D), World Health Organization Quality of Life Scale-abbreviated version (WHOQOL-BREF), Readiness to Change Questionnaire (RCQ), and Readiness Ruler. Follow-up completers and non-completers were compared at baseline, and follow-up completer outcomes were reported. Predictors of change in drinking behavior were evaluated at follow-up.Registered users were 41.88 years old on average (SD = 12.36), and 52 % were women; the mean baseline number of drinks during the past week was 27.27 (SD = 17.92) with 62 % in the AUDIT category of probable dependence and only 7 % having low-risk consumption according to public health guidelines. At follow-up (n = 1043), 53 % showed a clinically significant change to a lower level of alcohol use (chi(2) = 254.403, p < 0.001); the mean alcohol consumption fell (t = 22.841, p < 0.001) and the proportion with low-risk consumption rose to 40 %. Being male, scoring higher on baseline readiness, completing the program, and accessing other support predicted low-risk drinking and clinically significant change to a lower level of alcohol use at follow-up.A publicly available Web-based program for managing problematic alcohol use attracted users with considerable alcohol- and health-related problems, which were changed to lower severity for follow-up completers.
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| 41. |
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| 42. |
- Lindblom, Lars, 1971-, et al.
(författare)
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How agencies inspect : a comparative study of inspection policies in eight Swedish government agencies
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundThe regulatory approach used by SKI has an impact on the licensee and, therefore, indirectly on the safety of the nuclear facilities. The regulatory policy and its implementation also influences the way SKI is working and the competency needed by the regulator as well as by the industry. One of SKI´s tasks is to be able adjust the regulatory approach to current and future needs.Little research is available on the use of regulatory strategies, methods and activities used by regulatory agencies in their work (to assure safety), as well as their impacts. To address this gap in knowledge, SKI has contracted two separate research projects. This project, where the focus is on comparing inspection policies in Swedish government agencies, and another one where regulatory strategies across selected countries, are studied and compared.SKI´s purpose and goalsThe goal of this research project is to gain knowledge about selected Swedish agencies and their inspection policies. All the selected agencies are working with issues regarding health, environmental protection or safety. A number of persons at each agency have been interviewed about the regulatory work at their organizations. A questionnaire was developed as a first part of the project, and it was used during the interviews.In addition to provide insights as a basis for improvement within SKI, the purpose has been to promote exchange of experience between agencies with similar tasks. By this study SKI also wanted to contribute to the development of competency in this field of research.ResultsA lot of information has been gathered and analyzed during the project. The focus of the research is on comparing agencies and their practices. The report includes an analysis regarding similarities and differences in a number of areas across the agencies. The report also provides information and evidence on the problems related to comparison between agencies, partly due to the difference in the use of definitions. The recommendations resulting from this study focus on improving cooperation among Swedish agencies and on improving inspection methodologies, areas where further analysis is suggested. The conclusions and recommendations in the report belong to the persons participating in this work, and are not necessarily the same as the once drawn by SKI.
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| 43. |
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| 44. |
- Oskarsson, Sven, 1971-
(författare)
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The Fate of Organized Labor : Explaining Unionization, Wage Inequality, and Strikes across Time and Space
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The point of departure for this thesis is the divergent fate of organized labor during the last decades in the Western world. Given what we know about actual trends, how are we to explain the variation in the strength of organized labor across time and space? The thesis consists of four self-contained essays.Essay 1: Using aggregate data from 15 advanced capitalist societies, I show that the estimated effects of domestic cyclical, labor market structural, and globalization variables differ in a predictable manner across nation-specific institutional frameworks.Essay 2: In the second essay I argue that two institutional properties – the degree of centralization in the bargaining system and the workplace access of the union movement – will interactively influence the unionization process. The empirical results indicate that these institutional variables positively influence the aggregate density levels and cushion the effects of compositional factors on the probability of being a union member.Essay 3: In the third essay I argue that coordinated wage bargaining alters the causal logic when explaining wage inequality, in the sense that common explanatory factors have different effects depending on the degree of bargaining coordination. The evidence presented supports the theoretical argument.Essay 4: In this essay I propose a formal model of strike behavior predicting a curvilinear relationship between employer beliefs about union bargaining strength and the probability of a strike. Further, I argue that this curvilinear relationship is valid only under uncoordinated wage bargaining.
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| 45. |
- Razmjoo, Narges, et al.
(författare)
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Characterization of the fuel bed combustion of wood residues in a 4 MW grate boiler
- 2015
-
Ingår i: European Biomass Conference and Exhibition Proceedings. - 9788889407516 ; , s. 741-744
-
Konferensbidrag (refereegranskat)abstract
- Information about distributions of temperature and gas species within the fuel bed is of great importance in studying the formation of pollutants in an industrial-scale biomass boiler. The main objective of this study was to investigate the gas composition and temperature in some available sections of the fuel bed of a 4 MW reciprocating grate boiler, burning mixture of fresh pine wood chips, bark, and sawdust with two significantly different moisture content levels. The averageCO, CO2,CH4, and O2 concentrations measured during the combustion of the more moist fuel (about 60 mass %) were about 12, 12, 2, and 4 vol. %, respectively, whereas the corresponding values for the less moist fuel (about 45 mass %) were about15, 10, 2.5, and 5 vol. %, respectively. Higher concentration of CO and lower concentration of CO2 for the less moist fuel could originate either from the char conversion process or from the reactions of the devolatilizationgas products.
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| 46. |
- Razmjoo, Narges, et al.
(författare)
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Study of the transient release of water vapor from a fuel bed of wet biomass in a reciprocating-grate furnace
- 2019
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Ingår i: Journal of the Energy Institute. - : Elsevier BV. - 1743-9671 .- 1746-0220. ; 92:4, s. 843-854
-
Tidskriftsartikel (refereegranskat)abstract
- The present study investigates how sudden changes in fuel moisture affected the combustion characteristics of the fuel bed in a 4-MW reciprocating-grate furnace. The moisture content of the fuel fed to the furnace was monitored online using a near-infrared spectroscopy device, and the water vapor concentration in the flue gas was measured continuously. To obtain experimental data on fuel-bed conditions, the temperature and gas composition in the bed were measured using a probe. A simplified drying model was developed using the measured gas composition values as inputs. The model was then used to estimate the drying rate and to simulate the extent of the drying zone along the grate. Measurements indicated that a change in the moisture content of the fuel fed to the furnace was detected as a change in water vapor concentration in the flue gas with a delay of about 2 h. The model predicted that a portion of wet fuel would need about 2 h to become dry, in line with the measured time delay of the water vapor concentration change in the flue gas. Overall, there was good alignment between the measured and simulated results, supporting the validity of the model and the assumed mechanisms. © 2018 Energy Institute
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| 47. |
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| 48. |
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| 49. |
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Seminarium Förbränning av biobränsle på rost
- 2009
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- Presentationsunderlag från årligt återkommande seminarium om förbränning av biobränsle på rost. Medverkande är forskare från Chalmers och Lunds tekniska högskola samt representanter från tillverkare och brukare av rosteldade förbränningsanläggningar.
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| 50. |
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