Abstract A blast furnace is the dominant process for making iron in the world. Iron ore pellets are commonly used as iron burden materials in a blast furnace, in which iron oxides are reduced to metallic molten iron. While descending, the charge faces various stresses, which affect the gas flows in the shaft and the energy efficiency of the process. Charge material testing on a laboratory scale is of crucial importance in regard to the development of material quality. This doctoral thesis presents a couple of advanced novel experimental methods: a novel camera imaging method to determine the amount of swelling during reduction; a novel reducibility test to determine the reducibility in a solid state under simulated blast furnace conditions; and a novel experimental program for the ARUL reduction-softening test to more accurately simulate blast furnace conditions. Swelling tests under conditions of fixed temperature and gas composition showed that isothermal tests do not give a realistic insight into the material behaviour in a blast furnace. As a result, it is suggested that dynamic gas composition – temperature programmes simulating actual process conditions should be used. Additionally, the test results showed that circulating elements (sulphur and potassium) also affect the pellet volume change during reduction, however no abnormal swelling was observed in any of the swelling experiments. The factors affecting the high-temperature properties of iron burden materials for blast furnace use were evaluated by both the experimental methods and computational thermodynamics. It was shown that none of the studied pellet grades has as good reduction-softening properties as the fluxed sinter because of the differences in the chemistry and macro-porosity. FeO-SiO2-CaO-MgO-Al2O3 system examinations with FactSage was found to be a useful tool for predicting the softening of an iron burden material using the original chemical composition. FactSage computations suggest that the softening properties of an iron burden material can be improved either by decreasing the proportion of SiO2, increasing the proportion of MgO or introducing an appropriate amount of CaO in relation to the proportion of SiO2. / Tiivistelmä Masuuni on merkittävin raakaraudan valmistusprosessi maailmassa. Masuunissa käytetään yleisesti rautamalmipellettejä rautapanosmateriaalina. Masuunissa raudanoksidit pelkistetään metalliseksi rautasulaksi. Vajotessaan panos kohtaa monenlaisia rasitteita, joilla on vaikutusta kuilun kaasuvirtauksiin ja masuuniprosessin energiatehokkuuteen. Panosmateriaalien testaus laboratoriomittakaavassa on merkittävässä roolissa, kun niiden laatua kehitetään. Väitöskirjassa esitetään useita kehittyneitä koemenetelmiä: uusi kamerakuvausmenetelmä, jolla voidaan määrittää turpoaminen pelkistyksen edetessä; uusi pelkistyvyystesti, jolla voidaan määrittää rautapanosmateriaalin pelkistyminen kiinteässä tilassa masuunia jäljittelevissä olosuhteissa; ja uusi koeohjelma, jolla voidaan jäljitellä aiempaa tarkemmin masuuniolosuhteita sulamis-pehmenemiskokeessa. Turpoamistestit vakioiduissa olosuhteissa osoittivat, että isotermiset testit eivät anna realistista kuvaa materiaalin käyttäytymisestä masuunissa. Tämän vuoksi dynaamisia kaasukoostumus–lämpötila-ohjelmia tulisi suosia. Lisäksi tutkimustulokset osoittavat, että myös masuunissa kiertävillä komponenteilla (rikillä ja kaliumilla) on vaikutusta pelletin tilavuuden muutokseen pelkistyksessä. Yhdessäkään turpoamiskokeessa ei kuitenkaan havaittu katastrofaalista turpoamista. Masuunin rautapanosmateriaalien korkealämpötilaominaisuuksiin vaikuttavia tekijöitä arvioitiin sekä kokeellisin menetelmin että termodynaamisin laskelmin. Yhdelläkään tutkitulla pellettilaadulla ei havaittu sintterin veroisia korkealämpötilaominaisuuksia, mikä johtuu eroista kemiallisessa koostumuksessa ja makrohuokoisuudessa. FeO-SiO2-CaO-MgO-Al2O3 systeemitarkastelut rautapanosmateriaalin lähtökoostumuksella todettiin toimivaksi menetelmäksi arvioida panosmateriaalin pehmenemiskäyttäytymistä. FactSage-laskennat antavat ymmärtää, että rautapanosmateriaalin pehmenemisominaisuuksia voidaan parantaa joko vähentämällä SiO2:n osuutta, lisäämällä MgO:n osuutta tai lisäämällä CaO:ta sopiva määrä SiO2:n osuuteen nähden.

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This Master’s thesis deals with design of heating source and heating system in the model object. Design is based on three variants of sources and heating systems. The first option is a heating pump air/water, the second option is pellet boiler and the third option is heating pump ground/water. At first heating losses are determined. Then heating systems and related heating sources are designed. The fundamental part of these free options is a design of alternative source for central heat and and hot water and heat storage. The last part is comparison of all variants.

My diploma thesis deals with heating with the aid of renewable energy sources and thier application in the building of elementary school. This thesis is devided into three parts. The first part is theoretical and is focused on overview of renewable energy sources. It deals with biomass boilers and heat pumps in detail. The second part of this thesis contains comparison of two variants of heat sources and necessary calculations and designs. The first variant is an air-to-water heat pump and the second one is a pellet boiler. The chosen variant is elaborated in detail in the last part. The last part contains technical drawings and technical report.

With the increasing demand and interest in wind power worldwide, it is interesting to study the effects of running windfarms on the activity of reindeers and estimate the associated Zone of Influence (ZOI) relative to these disturbances. Through simulation, Hierarchical Likelihood (HL) and adaptive Lasso methods are used to estimate the ZOI of windfarms and catching the correct threshold at which the negative effect of the disturbances on the reindeer behaviour disappears. The results found some merit to the explanation that the negative effect may not disappear abruptly and more merit to the fact that a linear model was still a better choice than the smooth polynomial models used. A real-life data related to reindeer faecal pellet counts from an area in northern Sweden were windfarms were running were analyzed. The yearly time series data was divided into three periods : before construction, during construction and during operation of the windfarms. Logistic regression, segmented model, and HL methods were implemented for data analysis by using covariates as distance from wind turbine, vegetation type, the interaction between distance to wind turbine and time period. A significant breakpoint could be estimated using the segmented model at a distance of 2.8 km from running windfarm, after which the negative effects of the windfarm on the reindeer activity disappeared. However, further work is needed for estimation of ZOI using HL method and considering other possible factors causing disturbances to the reindeer habitat and behaviour.

Several types of reactors are encountered in industry where reagents in a gas and a liquid phase need to be catalysed by a solid catalyst. Common reactors that are used to this end, are trickle-bed reactors, where gas and liquid flow cocurrently down a packed bed of catalyst. Apart from the catalytic process itself, several mass transfer steps can influence the rate and/or selectivity of a solid catalysed gas-liquid reaction. In trickle-bed reactors, flow morphology can have a major effect on these mass transfer steps. This study investigates the interaction between liquid flow morphology and mass transfer in trickle-bed reactors from three different angles. The primary focus is on liquid-solid mass transfer and internal diffusion as affected by the contacting between the liquid and the catalyst. First, the contacting between the liquid and the solid in trickleflow, or wetting efficiency, is characterised using colorimetry. Though this investigation is limited to the flow of nitrogen and water over a packed bed at ambient conditions, it provides useful information regarding liquid flow multiplicity behaviour and its influence on the distribution of fractional wetting on a particle scale. The colorimetric study also provides descriptions of the geometry of the liquid-solid contacting on partially wetted particles. These are used in a second investigation, for the numerical simulation of reaction and diffusion in partially wetted catalysts. This second investigation uses numerical simulations to evaluate and develop simple theoretical descriptions of liquid-solid contacting effects on catalyst particle efficiency. Special attention is given to the case where external and intraparticle mass transfer rates of both a volatile and non-volatile reagent affect the overall rate of reaction. Also, since these are not often considered in theoretical studies, some suggestions are made for the evaluation of the particle efficiency of eggshell catalyst. Finally, liquid-solid contacting is investigated in a high-pressure pilot reactor. Wetting efficiency is measured with a useful technique that does not rely on descriptions of particle kinetics or liquid-solid mass transfer rates. Liquid-solid mass transfer coefficients are also measured and results agree well with the colorimetric investigation, suggesting the existence of different types of flow within in the hydrodynamic multiplicity envelope of trickle-flow. Since it consists of different investigations of liquid-solid contacting from different angles, the study highlights several aspects of liquid-solid contacting and how it can be expected to influence trickle-bed reactor performance. / Thesis (PhD)--University of Pretoria, 2009. / Chemical Engineering / unrestricted

Den ökade efterfrågan på pellets har fört med sig högre krav på pelletkvalité och detta har lett till att forskningen i Sverige har övergått från att studera möjliga bränslen till att studera pelletkvalité, ofta med fokus på mekanisk hållfasthet. För att pröva den mekaniska hållfastheten så finns olika standardmetoder såsom tumling enligt ISO 17831-1:2015, som är europeisk standard, och lignotest. Standardmetoderna kräver en större mängd pellets och kan inte användas för att pröva pellets från en singelpelletpress, vilket är ett mycket vanligt sätt att producera nya pelletsammansättningar. En singelpelletpress tillverkar en pellet åt gången och för att prediktera mekaniska hållfastheten finns många olika metoder, till exempel dropp- och hårdhetstest. Det är idag oklart hur väl metoderna för att pröva pellets från en singelpelletpress predikterar mekaniska hållfastheten och det finns en begränsad mängd forskning som undersöker korrelationen med standardmetoderna. Äldre forskning visar på en positiv linjär korrelation medan nyare forskning visar att korrelationen även beror på pelletens sammansättning. Det finns också studier som använder nya sätt att pröva enstaka pellets. En ny studie tumlar pellets tillsammans med plastpellets, men inga jämförelser med andra metoder utförs. En annan studie prövade tumling samt lignotest för en pellet åt gången och jämförde med tumling enligt ISO 17831-1:2015. Den studien visade ett R2 på 0.83 respektive 0.94 för pellets med en mekanisk hållfasthet över 90%.  En metod som korrelerar med standardmetoderna skulle mycket tydligare indikera hur en pellet från en singelpelletpress skulle prestera i större produktionsskala. Om metoden även utnyttjar redan tillgänglig teknik finns möjligheten för en bred användning, likt en standardmetod, som skulle underlätta jämförelser mellan olika studier och samarbeten mellan forskningsinstitut.  I detta arbete undersöks validiteten av att tumla enstaka pellets tillsammans med plastpellets. Plast- och singelpelletsmixen som innehöll 3, 10 och 20 pellets, resterande del (upp till 500g ±10g) plastpellets, tumlades för 6 olika sorters pellets. Standardavvikelse, relativ standardavvikelse samt medelvärdet av mekaniska hållfastheten bestämdes och den linjära regressionen med tumling enligt ISO 17831-1:2015 undersöktes. För samma pelletsorter genomfördes dropptest och hårdhetstest där den linjära regressionen med tumling enligt ISO 17831-1:2015 även gjordes för hårdhetstestet. Resultaten visar att tumling med plast- och singelpelletmix fungerar som alternativ metod till ISO 17831-1:2015 för pellets med en mekanisk hållfasthet över 92,45%, där mycket tillförlitligt resultat fås för 3 eller fler tumlade pellets över 96,62% mekanisk hållfasthet där 8 av 9 uppmätta standardavvikelser var under 1 %. För hela det prövade kvalitetsintervallet visades en korrelation (R2) med standardmetoden på 0,88-0,98 och ett R2 nära 1 för pellets med en mekanisk hållfasthet över 95 %. Dropptestet gav ingen information om pelletens mekaniska hållfasthet och bedömdes inte som en lämplig metod. Hårdhetstestet visade en hög relativ standardavvikelse mellan 19-40 % och en korrelation (R2) med standardmetoden på 0,78. Tumling med plast- och singelpelletmix hade både lägre standardavvikelse och högre korrelation med standardmetoden som visar att det är en bättre metod för att prediktera mekaniska hållfastheten för enstaka pellets än hårdhetstest. / The increased demand of pellets has led to higher demand on pellet quality causing a shift in Swedish research from studying possible fuels to studying pellet quality, often with a focus on mechanical durability. To test the mechanical durability there are various standard methods such as tumbling according to ISO 17831-1:2015, which is the European standard, and lignotest. The standard methods require a large amount of pellets and can´t be used to test pellets from a single-pellets press, a common way to produce new pellet compositions. A single-pellet press produces one pellet at a time and to predict the mechanical durability there are different methods, such as drop and hardness tests. Today it´s unclear how well the methods for testing pellets from a single-pellets press predicts the mechanical durability and there are a limited amount of research that examines the correlation with the standard methods. Earlier research shows a positive linear correlation while a recent publish study showed that the correlation also depends on the composition of the pellet. However, also new ways to test individual pellets has recently bin published, where single pellets were tumbled together with plastic pellets, but no comparisons with other methods were made. Another study tried tumbling and lignotest for one pellet at a time and compared with ISO 17831-1:2015. The study showed an R2 of 0,83 and 0,94 respectively for pellets with a mechanical durability above 90% A method that correlates with the standard methods would indicate how a pellet from a single-pellet press would preform on a larger production scale. If the method also uses already known technology there is the possibility of a broad use, similar to a standard method, wich would facilitate comparisons between different studies and collaborations between research institutes.   In this study, the validity of tumbling individual pellets together with plastic pellets is investigated. The plastic and single-pellet mix containing 3, 10 and 20 pellets, the remaining part (up to 500 ±10g) plastic pellets, was tumbled with 6 different types of pellets. Standard deviation, relative standard deviation and the mean value of the mechanical durability were determined and the linear regression with tumbling according to ISO 17831-1:2015 was examined. For the same pellet varieties, drop and hardness tests where preformed, where the linear regression with ISO 17831-1:2015 was also examined for the hardness test.   The results show that tumbling with plastic and single-pellet mix works as an alternative method to ISO 17831-1:2015 for pellets with a mechanical durability above 92,45 %, where very reliable results was obtained for 3 or more tumbled pellets above 96.62 % mechanical durability where 8 out of 9 standard deviations measured below 1%. For the entire tested quality range, a correlation (R2) was shown with ISO 17831-1:2015 of 0.88-0.98 and an R2 close to 1 for pellets with a mechanical durability over 95 %. The drop test did not provide any information on the mechanical durability of the pellet and was not considered an appropriate method. The hardness test showed a high relative standard deviation between 19-40 % and a correlation (R2) with ISO 17831-1:2015 of 0.78. Tumbling plastic and single-pellet mix had both lower standard deviation and higher correlation with the standard method ISO 17831-1:2015 which shows that it is the superior method for predicting the mechanical durability of individual pellets over hardness test.

We are facing an important challenge, to reduce the greenhouse gas emissions to make sure that we limit global warming to 2 °C, preferably 1.5 °C. Drastic changes and developing new methods may be our only chance to keep global warming under 1.5 °C. The steel production in Sweden today accounts for 10% of the CO2 emission. The joint venture HYBRIT (Hydrogen Breakthrough Ironmaking Technology), between SSAB, LKAB and Vattenfall, aims to reduce the CO2 emission by developing a method that reduces iron ore pellets with hydrogen gas, leaving only water as off-gas. From simple thermodynamic calculations, it is evident that the reduction of iron ore using hydrogen gas is an endothermic reaction, requiring heat. Based on the calculated energy requirement, the temperature at the center of the pellet should not be the same as the temperature at the surface of the pellet but instead, decrease as the reduction reaction takes place. This report presents the temperature profile at the surface and in the center of a hematite pellet during hydrogen reduction at temperatures of 600 °C, 700 °C, 800 °C and 900 °C. Ideally, the results can be implemented in a model to better simulate the reduction reaction taking place inside a hematite pellet. The experiment consists of three sub-experiments, the first measures the temperature profile of the unreduced iron ore pellet in an argon gas atmosphere, secondly, the temperature profile and mass loss are measured during reduction, lastly, the temperature profile is measured for the reduced pellet in a hydrogen atmosphere. The mass loss measured during hydrogen reduction is used to calculate the degree of reduction. The results show that the reaction rate increases with increasing temperature and concentration of H2. Additionally, a higher reduction temperature gives the largest temperature decrease inside the pellet during reduction. At 900 °C, the temperature decrease is equal to 39 °C and at 600 °C, it is equal to 3 °C. The results prove that after a certain initial stage, gas diffusion and heat conduction through the product layers play important roles in controlling the reaction rate. There is even a period where a plateau of the reduction is observed, the reaction is mostly controlled by heat transfer. / Idag står vi inför en viktig utmaning, att minska utsläppen av växthusgaser och se till så att vi inte överskrider 2 °C uppvärmning, helst inte 1.5 °C. För att klara detta krävs drastiska förändringar och utvecklingar av nya metoder kan vara vår enda chans att uppnå 1.5-gradersmålet. Ståltillverkningen i Sverige idag står för 10% av CO2 utsläppen och för att bidra till att minska utsläppen av CO2 har företaget HYBRIT, vilket står för Hydrogen Brakethrough Ironmaking Technology, skapats. HYBRIT är en joint venture mellan SSAB, LKAB och Vattenfall som tillsammans vill skapa stål på ett mer miljövänligt sätt. Processen går ut på att reducera järnmalmspellets med hjälp av vätgas för att producera järnsvamp och ge ifrån sig vatten som avgas. Från enkla termodynamiska beräkningar är det lätt att inse att reduktionen med hjälp av vätgas är en endoterm process, som kräver energi. Det är genom denna kunskap som en kan föreställa sig att reduktionen av järnmalmspellets med hjälp av vätgas kommer bidra till en temperaturminskning. I denna rapport har temperaturprofilen inne i och på ytan av en hematitpellet mätts under tiden som den blivit reducerad med vätgas. Idealt kan resultaten implementeras i en modell för att bättre simulera reduktionsreaktionen som äger rum i en hematitpellets. Fyra olika reduktionstemperaturer har undersökts: 600 °C, 700 °C, 800 °C och 900 °C. Experimenten består av tre del-experiment, först mäts temperaturprofilen av den oreducerad hematitpelletsen i en argonatmosfär, sedan mäts viktminskningen och temperaturprofilen av pelleten medan den reduceras i en vätgasatmosfär, slutligen mäts temperaturprofilen av den reducerade pelleten i en argonatmosfär. Viktminskningen under reduktionen används för att beräkna reduktionsgraden under reduktionsförloppet. Resultaten visade att reduktionshastigheten ökade med ökande temperatur och koncentration av H2. Ökad temperatur gav även den största temperaturminskningen inne i pelleten då den reducerats med vätgas. Vid 900 °C uppmätes en temperaturminskning på 39 °C, varav reduktion vid 600 °C gav en temperaturminskning på 3 °C. Resultaten visar att efter en viss tids reduktion, spelar gasdiffusionen och värmeledningen genom produktlagret en viktig roll och är det som begränsar reduktions-hastigheten. Fortsatt, då hematitpelleten reducerades uppstod en platå där temperaturen var konstant och reaktionen till största delen var begränsad av värmeledningen genom produktlagret.

In dry interim storage of spent nuclear fuel, thermal creep is one of the major threats to the fuel cladding integrity due to the constant decay heat generation from the fission products and minor actinides in the fuel, and the increase in fuel rod internal pressure which is present after burnup. Plenty of research has been done on either empty cladding tubes irradiated in a research reactor, or on spent fuel that is defueled prior to the examination. This type of research excludes the effects of the pellet-cladding bonding that may be present after burnup, where the bonding might have significant effects on the thermal creep behavior. Therefore, this work aims to construct and validate an experimental model that is designed to perform thermal creep tests on as-received spent nuclear fuel, where the pellet-cladding bonding is still intact, in order to gain knowledge in the causal relation that the pellet-cladding bonding has on the thermal creep phenomenon during dry storage. The experimental model is validated by a number of qualification tests, as well as a series of creep tests on unirradiated Zircaloy-4 tubes. The results are compared to the literature which shows the reproducibility of the model, which further supports its validity. / I torrt mellanförvar av använt kärnbränsle så är termisk krypning en av de främsta farhågorna för kapslingens fysiska integritet genom sönderfallsvärmen från klyvningsprodukter och andra aktinider, samt det förhöjda interna trycket i kapslingen som är närvarande efter utbränning. Åtskillig forskning har gjorts på antingen tomma kapslingsrör som är bestrålade i en forskningsreaktor, eller på använt bränsle där bränslekutsen är urborrad innan undersökning. Denna typ av forskning utelämnar effekten av kuts-kapsling bindningen som uppstår under uppbränning, där bindningen kan ha en betydande effekt på kapslingens beteende under termisk krypning. Därför så dedikeras detta arbete till att konstruera och validera en experimentell modell som är designad till att utföra tester av termisk krypning på opåverkat använt bränsle, där kuts-kapsling bindningslagret fortfarande är intakt, för att lära om bindningslagrets effekt på fenomenet termisk krypning under torrt mellanförvar. Den experimentella modellen är validerad genom ett antal kvalificeringstester, samt en serie av kruypningstester på obestrålade Zircaloy-4 rör. Resultaten är jämförda mot litteraturen, vilket visar reproducerbarheten hos modellen, som i sin tur understöder modellens validitet.

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