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  • 351.
    Öhman, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Hedman, H
    Jirjis, R
    Reasons for slagging during stemwood pellet combustion and some measures for prevention2004In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 27, no 6, p. 597-605Article in journal (Refereed)
    Abstract [en]

    Ash related problems have more than occasionally been observed in pellet burners during the last years. These problems lead to reduced accessibility of the appliances and also bad publicity for the pellet market. The objectives of the present work were therefore to: (i) determine the critical levels of the problematic ash components in stemwood pellets regarding slagging, (ii) document the variations of these problematic elements in the outgoing pellets from two pellet-mills during one operational season, (iii) determine how frequently these elements exceed the critical levels, (iv) determine how different sub-processes in the pelletising process (especially the dryer) effect the slagging properties of the pellet, and if possible (v) suggest some measures for prevention. A significant number of wood pellets reported to be problematic and problem-free, regarding slagging in ordinary residential pellet burners, were collected from the Swedish market. The ash compositions of these fuels were analysed and the results compiled in a database. Partial Least-Squares Discriminant Analysis (PLS-DA) and F-tests were used to statistically identify both the critical ash components and the critical levels of these components that separated the two reported classes. In addition, chemical equilibrium model calculations were used to interpret the findings. The variations of these elements in the in-going raw material and in the produced pellets were determined during one season in two pellet mills equipped with exhaust gas dryers. The results showed that the problematic wood-pellets had a significantly higher amount of Si, but also Al and Fe, in the fuel ash. The critical level of Si (given as SiO2) was about 20-25 wt% of the fuel ash, i.e. pellets with levels in or over this range resulted in slagging problems in residential burners. This critical Si content was exceeded once and twice for the analysed samples in the two studied pellet mills. In one of the studied mills, this was because of contamination by sand of the raw material during storage and handling, and in the other mill the reason was found to be contamination of the raw material by elutriated particles from the dryer fuel. The major conclusion of the work is that both raw materials and drying fuels/processes should be carefully treated to avoid mineral contamination, and an additional cyclone separator could potentially also be used to improve the pellet quality.

  • 352.
    Öhman, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nordin, Anders
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Lundholm, Karin
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Hedman, Hedman
    Energy Technology Centre, Piteå.
    Lundberg, Margareta
    Kvaerner Pulping AB, Power Division, Göteborg.
    Ash Transformations during Combustion of Meat-, Bonemeal, and RDF in a (bench-scale) Fluidized Bed Combustor2003In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 17, no 5, p. 1153-1159Article in journal (Refereed)
    Abstract [en]

    Following the recent Bovine spongiform encephalopathy (BSE) experiences, thermal treatment of meat- and bonemeal (MBM) in existing fluidized bed combustion (FBC) plants for refuse-derived fuels (RDFs) has evolved as an interesting disposal and disintegration method. However, only a limited number of studies have previously been performed for combustion of MBM in fluidized beds. The objectives of the present work were, therefore, to determine the bed agglomeration tendencies of these materials during combustion in fluidized beds and to evaluate the effects of dolomite and kaolin addition to the fuel mix, as well as to elucidate the overall ash transformation mechanisms governing the potential bed agglomeration and fouling processes. By controlled agglomeration experiments in a 5 kW bench-scale fluidized bed reactor, the fuel-specific critical agglomeration temperatures in normal quartz bed material were determined for the different fuel/additive mixtures. All collected samples of bed materials, final bed agglomerates, and cyclone ashes were analyzed using SEM/EDS and XRD. The results indicated that the MBM fuels could be expected to be problematic concerning bed agglomeration in normal quartz beds, while kaolin and possibly dolomite addition could be used to reduce this risk to moderate levels. A significant elemental fractionation between the bed material and the cyclone ash was obtained. Apatite (Ca5(PO4)3(OH) or potentially some other calcium phosphates are elutriated from the bed and enriched in the fly ash, while sodium and potassium are enriched in the bed material. The characteristics and the corresponding melting behavior estimations of the necks formed between agglomerated bed particles suggest that silicate melts are responsible for the bed agglomeration. Results from XRD analysis of the fly ash formed from the fuels used in the present study indicated that the risk for melt-related fly ash problems seem relatively small.

  • 353.
    Östergren, Simon
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energiutredning av en hälsocentral samt förbättringsarbete av modulen Energi & Miljö i DeDU2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Byggnadssektorn är en av de tre största områdena inom världens energianvändning och den står för ungefär en tredjedel av den totala energianvändningen. Det är därför av stor vikt att byggnadssektorn effektiviseras för en mer hållbar framtid.

    I det här examensarbetet var syftet att utföra en energiutredning på en hälsocentral med hjälp av energistatistik från modulen Energi & Miljö i WSP:s egenutvecklade programvara DeDU. Den andra delen i arbetet var att med erfarenheter från energiutredningen undersöka hur modulen Energi & Miljö kan förbättras för att bättre uppmärksamma dess användare på energianvändning.

    Energiutredningen utfördes med hjälp av konstruktionsritningar och energistatistik från DeDU för total fjärrvärmeanvändning, total elanvändning samt timvärden för elanvändningen. Fördelning mellan fastighetsel och verksamhetsel togs fram med hjälp av statistik från studien STIL2 utförd av Energimyndigheten. Det visade sig att Hörnefors hälsocentral är relativt energieffektiv sett till andra liknande fastigheter. Byggnadens klimatskal visade sig vara bra med ett Umedel på 0,45 W/m2K. Av de energieffektiviseringsförslag som togs fram visade det sig att förslaget med störst besparingspotential är byte av 2-glasfönster till 3-glasfönster.

    Förbättringsarbetet av modulen Energi & Miljö i DeDU utfördes genom en enkätundersökning, en workshop samt en undersökning av befintliga energirapporter för att ta fram förslag på nya rapporter. Från enkätundersökningen framkom det att de tillfrågade kunderna generellt är nöjda med modulen Energi & Miljö men att det finns önskemål om en del förbättringsförslag. Tre förslag på nya energirapporter kopplade till DeDU togs fram. Huvudsakliga tanken bakom förslag 1 och 2 var att ge kunderna möjlighet att lättare göra jämförelser mellan olika fastigheter/byggnader samt jämförelse av energianvändningen för samma fastighet/byggnad. Tanken med förslag 3 var att ge möjlighet att uppskatta olika verksamheters fördelning mellan fastighetsel och verksamhetsel. Slutligen kan det konstateras att det är fördelaktigt att presentera färdig förbättringsförslag, då de flesta kunder inte själva vet vad de behöver eller vad som saknas.

  • 354.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energieffektivt byggande i kallt klimat2012In: Bygg & teknik, ISSN 0281-658X, Vol. 104, no 8, p. 39-42Article in journal (Other (popular science, discussion, etc.))
  • 355.
    Östin, Ronny
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Evaluation of a Single Family Low Energy Building in Cold Climate2017In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 132, p. 9-14Article in journal (Refereed)
    Abstract [en]

    Verification of energy performance and indoor climate by detailed field measurements in buildings is of great importance and promotes an assurance in the process of constructing low energy buildings and enables to utilize the full potential of energy efficiency measures.

    In the present work a single family building with a heated living space area of 175 m2 has been monitored. The heating system has a wood pellet stove for space heating (SH) and domestic hot water (DHW) and on the roof there are solar collectors in a southerly direction contributing to SH and DHW. SH is distributed by the ventilation system and an under floor heating system which is connected to a heat storage water tank. The incoming outdoor air is pre-heated in an earth-to-air heat exchanger and the building has a measured specific energy usage of 54 kWh/m2year which is far lower than today’s regulation at 130 kWh/m2year in the actual climate zone. The low energy use in the building are due to thick thermal insulation (average Um = 0.18 W/°C m2), an air tight envelope (q50 = 0.165 l/sm2), heat recovery of exhaust air (average 74 % efficiency) and free heat from the ground pre-heating of supply air which is above 2°C even for outdoor temperatures down to -27°C. An essential factor was the low rate of air changes during the heating season about 40 % of the regulated requirement. Measurements of indoor air quality like carbon dioxide occasionally indicated insufficient ventilation.

  • 356.
    Östin, Ronny
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Eklund, Erik
    Johansson, Christer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Energieffektivt byggande i kallt klimat2012Report (Other academic)
    Abstract [en]

    The project Energy efficient construction in cold climate is a study of six newly produced low energy buildings in the region of Umeå. Four buildings are houses and two residential buildings which are located from Sikeå up north to Nordmaling down south.

    The buildings have been equipped with wireless logger system for collecting data of energy performance for the entire building and for individual components of the energy system. Loggers for relative humidity and temperature have been placed in ventilation and the buildings construction shell. The later of the position of loggers have been placed in different depths of the constructions isolating shell.

    The purpose of this study is to investigate these buildings energy performance and what risks constructing energy efficient buildings in cold climate due to humidity. The relative humidity and temperature sensors located in the construction shell show no signs of risk for rotting and mold. Moisture migration is a slow process and to be certain longer measurements are required.

    With the method called energy signature the measured energy usage have been normal corrected by year and the average U-value calculated. Expected energy usage and average U-value is compared to our measured data in this report.

    Two buildings in the study are equipped with a buried pipe for supply air which is 36m and 10 m long. The longest (36m) shows a big increase of air temperature (from -25°C outside to +°2 at the inlet connecting to the heat exchanger). This by means no extra heat is required for the inlet air to reach comfortable temperature.

    The measurement of energy displays that constructing buildings with lower energy use then the Swedish Boverkets requirements are confirmed. The houses shows a specific energy usage as Boverkets definition (energy for heating and for domestic hot water per heated surface area) from 59.7 to 91.8 kWh/m2, year and the residential buildings from 68 to 75.5 kWh/m2, year which are lower than today regulations at 130 kWh/m2, year and 95 kWh/m2, year for electric heated.

  • 357.
    Östling, Ida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Life cycle analysis as a tool for CO2 mitigation in the building sector2018Independent thesis Advanced level (professional degree), 300 HE creditsStudent thesis
  • 358.
    Östling, Ida
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Life cycle analysis as a tool for CO2 mitigation in the building sector2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    After the Paris agreement 2015 the Energy Commission in Sweden proposed a goal for Sweden of net zero greenhouse gas emissions by 2045. The focus in this report has been on how buildings in Sweden could reduce their greenhouse gas emissions. Year 2017 the government gave a task for Boverket in Sweden (National Board of Housing, Building and Planning) to investigate the possibility to introduce a climate declaration on buildings. The idea is a life cycle analysis (LCA) should be performed on the building in order to get a building permit. An LCA include all CO2 emissions emitted from resources used for raw material extraction, production of materials, construction site operations, user phase and also the demolition and disposal in the end of life of the building. The first draft from Boverket was published in February 2018 where they recommended a simple declaration. They recommended in the beginning to only include a few components in the declaration, and to only include the production phase. The major interest in this report have been to gain more understanding on how to perform LCAs and also how the LCA result could be used to decrease CO2 emissions. A case study was made on a residential building project called Mården, in Umeå Sweden.

    The first part in this thesis was to determine the phase in the buildings life cycle with the largest potential for decreasing CO2 emissions. When the LCA was performed on case study building Mården it was difficult to use exact data, since only 20 % of the construction products where declared in an environmental product declaration (EPD). Therefore the other 80 % where approximated with similar products declared in an EPD, or with generic data (general data for a type of product). An EPD is an LCA on a single product and could therefore give exact information on CO2 emissions for a specific product. However, several improvements where implemented in the buildings life cycle and where compared with this reference case. The result from the LCA showed the energy use in the user phase emitted the largest amount of CO2 emissions, and therefore also where the phase with the largest potential for reducing CO2 emissions. When the Swedish district heating mix where replaced with an energy source with 50 % less CO2 emissions, the emissions for the whole life cycle could be decreased with 20 %. Smaller improvements such as more environmental friendlier concrete, shorter transport distance between manufacturer and construction site or less water usage resulted in a decrease by 1.6-7 %. It was though shown these smaller improvement could result in a large decrease of CO2 emissions if more buildings also would improve the same thing. 2.4 million tons of CO2 emissions could for example be reduced in Sweden if 50 % of Sweden’s all new building projects would improve their choice of concrete. To make sure buildings could reduce their CO2 emissions there is important LCAs are performed before the building is constructed, to make sure all phases in the life cycle can be improved. If an LCA will be performed when the building is constructed, it is only possible to improve a few parts in the user phase, since the other phases already have passed.

    The second part in this thesis was to compare the different LCA softwares; (i) One Click LCA (needs license, from Finland), (ii) e-tool (free, from Australia) and (iii) BM (free, from Sweden). When more exact data were tried to be used in e-tool and One Click LCA the results were similar for the CO2 emissions from the production phase. E-tool only resulted in 6 % higher CO2 emissions in the production phase than One Click LCA. The LCA in the eventual future climate declaration will probably be performed with generic data, since in an early stage the contractors will not have detailed information on their construction products. An LCA was thus performed in each software with generic data, and the result differed a lot. The CO2 emissions from the production phase resulted in 36 % and 23 % less CO2 emissions in BM and e-tool than in One Click LCA. If several softwares will be allowed in this eventual climate declaration, the judgment could be difficult since different generic data is used in each sofware. The generic data were also different for one type of product in a single software, where the CO2 emission could differ with as much as 50 % between two types of generic data for one type of products. This leads to a difficulty when choosing generic data since there will be lack of information on the construction products at the time when this eventual climate declaration should be performed. A main focus for the future development should be on evaluating a standard database that could be used in EU.

    If a future law will be implemented it could be valuable to declare detailed rules on how to perform the LCA. Since depending on who will perform the LCA different results could occur due to different data used or assumptions on things like products, boundaries or used resource. However, this master thesis has shown there is possible to use the LCA methodology to find solutions for decreasing the CO2 emissions for buildings.

5678 351 - 358 of 358
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