In today`s steel industry about one third of the total steel production is produced by electric arc steel making. The production of steel is a very energy intensive industry, but when considering the total cost of the final steel mill product, it is the cost of raw materials that are dominating. A global trend for the manufacturing industry isto produce more energy effective products by usinglow alloyed steels which in turn affects the scrap based steel industry. Thereforean increased need of iron ore based metallic, such as direct reduced iron (DRI)and hot briquetted iron (HBI), as scrap supplement is then needed formaintaining low levels of trace elements in the produced steel. The selection ofraw materials is a matter that affects the conditions for the entire productionsystem, product properties, slag properties, off gas and dust generation, energyuse and the conditions for processes downstream.For the integrated iron and steel industry and also for other energy intensiveprocess industry, research in the field of process integration has shown goodresults regarding optimization of energy use and material utilization. Theapplication of process integration as a method for the scrap based industry, andin particular for Höganäs AB:s production system, is discussed in the thesis.Mixed Integer Linear Programing has been used to develop system models foroptimization and evaluation of costs and energy usage. Also processes notpresent in Höganäs current production system have been developed for analysisof future raw material scenarios. The current system models include six mainprocess steps: a direct reduction process, an electric arc furnace, a ladle furnace, a continuous casting process and a hot rolling mill. Among the presented results in this thesis, a major result is the models` ability to predict and constrain product quality in an improved way and show potentialcost- and energy savings for the modeled production system. Furthermore,another very useful result is the models` ability to minimize cost and energy usefor sequences of different product qualities, while taking stock levels intoconsideration. A constant concern for steelmakers is that raw material prices, composition and availability are changing and fluctuating over time. Therefore, system modeling can be seen as a good tool for helping to maintain flexibility in production units by taking advantage of these market fluctuations to keep conversion costs andenergy use at lowest levels possible

Pressurised entrained‐flow gasification (PEFG) of sustainable woody biomass offers the opportunity for envi-ronmentally benign production of syngas that is suitable for synthesis of fuels and other chemicals. During the PEFG process, ash-forming matter in the fuel undergoes transformations. Slag formation is an important form of ash transformation that occurs inside a PEFG reactor. In most industrial-scale PEFG of coal, the ash-forming matter becomes predominately molten and flows down the side of the reactor wall to be continuously tapped and removed. The slagging behaviour of woody biomass fuels during PEFG is expected to be different to that of coal, due to significant differences in the amount, composition and reactivity of the ash-forming matter. The objective of this thesis study was to initiate the elucidation of slag formation during PEFG of woody biomass. This was carried out by obtaining and characterising ash deposits and slags from pilot-scale experimental cam-paigns. An oxygen-fired pilot-scale reactor (ETC Piteå, Sweden) was used for the study. A low reactor temperature (< 1200 °C) study was carried out with three different fuels fired in separate experimental campaigns: stem wood, bark and pulp mill debarking residue (PMDR). Deposits were taken from each of the campaigns from the reactor for chemical characterisation. The stem wood fuel resulted in very little deposit that exhibited only minor amounts of melt, or slag, formation with enrichment of Si. The bark and PMDR fuels resulted in larger amounts of deposits with greater amounts of melt formation that were also enriched in Si. It was found that silica-based fuel contaminants, e.g., quartz sand and feldspars, may have an important role in melt formation. Following on, high reactor temperature (> 1350 °C) experimental campaigns involving stem wood produced flowing slags that eventuated in blockages of the reactor outlet. These slags were also retrieved from the reactor and characterised. It was found that they likely comprised of products resulting from detrimental interactions between the fuel ash and the mullite-based refractory used for the reactor wall lining. Viscosity models and thermochemical equilibrium calculations (TECs) were utilised to offer an explanation for the behaviour of the slags. Additional TECs were carried out to investigate the propensity for melt formation between the main ash-forming elements of woody biomass, Ca, K and Si, under global reactor conditions with relevance to PEFG. The results showed that, in general, the conditions for melt formation are broadened with increasing pressure, increasing amounts of Si and increased concentrations of gaseous K species. Dissolution of Al₂O₃ from mullite (Al₆Si₂O₁₃) refractory due to ash deposits and the gasification atmosphere was also predicted by the calculations. A scheme of slag formation during PEFG of woody biomass in a reactor with mullite-based refractory lining was proposed in light of the experimental observations. Some practical suggestions to avoid ash-related problems during PEFG of woody biomass are also discussed. This work forms part of a broader study to elucidate the ash transformations that occur during PEFG of woody biomass, which is necessary in order to develop the process into commercial availability.

Production of renewable motor fuels and green chemicals is important in the development towards a more sustainable society where fossil fuels are replaced. The global annual production of methanol and ammonia from fossil fuels is very large. Alternative production pathways are therefore needed to reduce emission of anthropogenic greenhouse gases and to reduce the fossil fuel dependency. Gasification of lignocellulosic biomass is one promising renewable alternative for that purpose. However, to be able to compete with fossil feedstocks, a highly efficient production of biomass-based products is required to maximize overall process economics and to minimize negative environmental impact. In order to reach reasonable production costs, large production plants will likely be required to obtain favourable economy-of-scale effects.Integrating large scale biofuel or green chemical production processes in existing pulp mills or in other large forest industries may provide large logistical and feedstock handling advantages due to the already existing biomass handling infrastructure. In addition, there are large possibilities to make use of different by-products. In chemical pulp mills, black liquor, a residue from pulp making, provides a good feedstock for the production of chemicals. It has previously been shown that investment in a black liquor gasification plant is advantageous regarding efficiency and economic performance compared to investment in a new recovery boiler. The potential production volume of green chemicals from black liquor is however limited since the availability of black liquor is strongly connected to pulp production. Increased chemical production volumes and thereby potential positive scale effects can be obtained either by adding other types of raw material to the gasification process or by increasing the syngas production by other gasification units operating in parallel. Several publications can be found regarding biomass gasification using one single feedstock and/or gasifier, but only a few consider cogasification of different fuels and dual gasification units. The overall aim of this thesis has therefore been to investigate technoeconomically the integration of biomass gasification systems in existing pulp and paper mills for green chemical production with the focus on creating economy-of-scale effects. The following system configurations were selected: i) a solid biomass gasifier that replaces the bark boiler in a pulp mill for methanol or ammonia production, ii) a solid biomass gasifier operated in parallel with a black liquor gasifier for methanol production, and iii) methanol production from gasification of black liquor blended with biomass-based pyrolysis oil. The main objectives were to find possible and measurable technically and economically added values for different integrated system solutions.The gasifier, the gas conditioning and synthesis were modelled in the commercial software Aspen Plus for material and energy balance calculations. A thermodynamic model developed for gasification of black liquor was used to simulate co-gasification of black liquor blended with pyrolysis oil. The outputs served as inputs for the process integration studies, where models based on Mixed Integer Linear Programming (MILP) were used. An iterative modelling approach between the two models was adopted to ensure that all constraints of the pulp and paper mill as well as for the gasification plant were met. The resulting material and energy balances were used to analyze the different system configurations in terms of overall energy efficiency and process economics. The results show that replacing the recovery or bark boiler with a biomass gasifier for green chemical production improves the overall energy system efficiency and the economic performance compared to the original operation mode of the mill and a non-integrated standalone gasification plant. Significant economy-of-scale effects were obtained when co-gasifying black liquor and pyrolysis oil. This adds extra revenue per produced unit of methanol compared to gasification of pure black liquor, even for pyrolysis oil prices that are considerably higher than projected future commercial scale production costs. Ingeneral, methanol sold to replace fossil gasoline showed good investment opportunities if exempted from taxes. Ammonia produced via gasification of lignocellulosic biomass is per unit of produced chemical significantly more capital intensive than methanol. The investment opportunity of the ammonia configuration is therefore diminished in comparison to methanol production.The main conclusion is that production of green chemicals via biomass gasification integrated in a pulp and paper mill is advantageous compared to stand-alone alternatives. Highest efficiencies and economic benefits are obtained for the systems where co-utilization of upstream (air separation unit) as well as downstream process equipment (gas conditioning units and synthesis loop) is possible.

Ionic liquids (ILs) have shown great potential to be used as liquid absorbents for CO2 capture because of its advantages, such as non-volatility, functionality, high CO2 solubility and lower energy requirements for regeneration. A significant amount of research has been carried out, but most of them are on the synthesis of novel ILs and the measurements of CO2 solubility in ILs. However, the application of IL-based technology for CO2 capture requires knowledge of gas solubility, the effect of other components on CO2 solubility, the thermo-physical properties, modeling as well as process simulation. Therefore, a tremendous gap exists between new technology development and implementation. The goal of this work is to perform a systematic study from experimental measurement, model development to process simulation in order to promote the development and application of IL-based technology for CO2 capture. In this work, the solubilities of CO2, CH4, H2, CO and N2 in choline chloride (ChCl)/urea (1:2 on a molar basis) were determined. The effect of water on the density, viscosity and CO2 solubility in ChCl/urea (1:2) were measured. The experimental gas solubility data was represented with the Non Random Two Liquid - Redlich Kwong (NRTL-RK) model. The results show that the addition of water significantly decreases the viscosity of ChCl/urea (1:2) while the effects on their density and CO2 solubility are much weaker. The excess molar volume and excess molar activation energy were calculated based on the experimental density and viscosity data. It was found that the intermolecular interaction between ChCl/urea and water is strong, and the hydrogen bond interaction is influenced by the temperature and water concentration. Meanwhile, the experimental data of CO2 solubility in imidazolium-based ILs at pressures below 10 MPa was surveyed and evaluated by NRTL-RK model. The CO2 absorption enthalpy and the energy consumption for a CO2 separation process using ILs by pressure swing and/or temperature swing were investigated. The results reveal that the temperature-dependent Henry’s constant is an important factor for energy consumption analysis in a pressure swing process, while the heat capacity of ILs plays a more important role in a temperature swing process.

By means of a literature review, critical parameters in the context of thermal energy storage systems, particularly packed bed thermal energy storage systems are identified. The goals of this thesis project are to come up with an optimized design for a PBSTES and to evaluate the thermal performance of alternative storage materials derived from byproducts of industrial processes and natural rocks in order to reduce the environmental impact of the designed system. Several CFD simulations have been performed in order to test these materials and optimize the system designusing COMSOL Multiphysics. In order to optimize the design of the packed bed TES system, given the boundary conditions provided, the dimension and arrangements of the two packed bed layers and the dimension of the pellets contained in each layer has been varied, and different system configurations with different pressure drops and thermal performance have been obtained. Through sensitivity analyses, an optimized design consisting of larger pellets (12.41 mm) in a slightly thinner inner layer (0.219 m) and smaller pellets (4.85 mm) in a larger outer layer (0.256m) is obtained. This optimized design is then tested using the alternative materials that have been identified as potential alternative filler materials which are copper slag, steel slag, aluminum dross, ceramic waste, and basalt. Granite is also tested as it has been identified as a common choice of filler material in literature and it is therefore used as a benchmark for the other materials to be compared against. The performance of these materials is then evaluated based on the identified KPIs: thermal efficiency of the systems, energy capacity of the materials, and thermocline thickness. Based on the outcomes of the KPI, copper slag, steel slag, aluminum dross, and ceramic wastes displayed better performance than granite. Among natural rocks, basalt showed better thermal performance and improved efficiency compared to granite making it a viable alternative in applications requiring the use of natural rocks as filler materials.This project showed that recycled materials and byproducts of energy intensive industries, particularly copper slag, represent a promising alternative as storage material in sensible packed bed thermal energy storage systems by reducing the environmental impact of these systems while guaranteeing appropriate performance. / Genom en litteraturöversikt identifieras kritiska parametrar i sammanhanget av termiskt energilagringssystem, särskilt packbäddar för termiskt energilagringssystem. Målen för detta avhandlingsprojekt är att utveckla en optimerad design för en PBSTES och att utvärdera den termiska prestandan hos alternativa lagringsmaterial som härstammar från biprodukter av industriella processer och naturliga bergarter för att minska den miljömässiga påverkan av det designade systemet. Flera CFD-simuleringar har utförts för att testa dessa material och optimera systemdesignen med hjälp av COMSOL Multiphysics. För att optimera designen av packbädd TES-systemet har dimensionen och arrangemangen av de två packbäddslagren och storleken på pelletsen i varje lager varierats, och olika systemkonfigurationer med olika tryckfall och termisk prestanda har erhållits. Genom känslighetsanalyser erhålls en optimerad design bestående av större pellets (12,41 mm) i ett något tunnare inre lager (0,219 m) och mindre pellets (4,85 mm) i ett större yttre lager (0,256 m). Denna optimerade design testas sedan med de alternativa material som har identifierats som potentiella fyllnadsalternativ, vilka är kopparslagg, Stålslagg, aluminiumslagg, keramiskt avfall och basalt. Granit testas också eftersom det har identifierats som ett vanligt val av fyllnadsmaterial i litteraturen och används därför som en referenspunkt för de andra materialen att jämföras med. Prestandan hos dessa material utvärderas sedan baserat på de identifierade KPI:termisk verkningsgrad hos systemen, energikapacitet hos materialen och termoklinens tjocklek. Baserat på resultaten av KPI visade kopparslagg, Stålslagg, aluminiumslagg och keramiska avfall bättre prestanda än granit. Bland naturliga bergarter visade basalt bättre termisk prestanda och förbättrad effektivitet jämfört med granit, vilket gör det till ett livskraftigt alternativ i tillämpningar som kräver användning av naturliga bergarter som fyllnadsmaterial. Detta projekt visade att återvunna material och biprodukter från energiintensiva industrier, särskilt kopparslagg, utgör ett lovande alternativ som lagringsmaterial i sensibla packbäddar för termiskt energilagringssystem genom att minska miljöpåverkan av dessa system samtidigt som de garanterar lämplig prestanda.

Ethiopia is a landlocked country located in northeast Africa with a predominantly rural population dependent on rainfed agriculture and traditional biomass. The Ethiopian economy is growing fast and as it continues to grow, so does the demand for water, food, and energy. Ethiopia is already facing food, energy, and water scarcity issues, and climate change's impacts have been increasing the strain on these resources. The country has great renewable energy resource potential, which is largely unexploited. The Ethiopian government aims to improve the water, and energy systems, and make them more resilient to climate change. The water, energy and land resources are not unlimited and sustainable management of these resources is therefore important. This thesis examines Ethiopia's energy, land, and water systems to identify cross-system challenges and their impact on Ethiopian food, water, and energy security. Furthermore, the food, water, and energy systems' vulnerability to climate change is also investigated. This integrated assessment is done by creating a Climate, Land, Energy, and Water systems (CLEWs) model of Ethiopia with the open-source energy modelling tool OSeMOSYS.The study showed that a development and transformation of the agricultural sector, from a predominantly rainfall-dependent agriculture to an agricultural sector with a greater share of irrigation, had both beneficial and negative effects on the resource systems. The development of the agricultural sector increases the yield per hectare and creates a more climate-resilient agriculture, increasing food security. However, irrigated agriculture is more expensive, with a larger water and electricity demand, which in turn could harm water and energy security. The study also showed that climate change could impact electricity generation in Ethiopia; however, the climate resilience of the energy system can be improved by investing in more biomass, wind, and solar PV. / Etiopien är ett kustlöst land på Afrikas horn i nordöstra Afrika. Majoriteten av befolkning bor på landsbygden och livnär sig på ett regnberoende jordbruk. Traditionell biomassa i form av ved och jordbruksavfall är den vanligaste energikällan för matlagning och uppvärmning förhushållen på landsbygden. Etiopien är en av världens fattigaste länder men har under de senaste åren haft en stor ekonomiska tillväxt. Tillsammans med den växande ekonomin har även den Etiopiska befolkningen ökat och därmed även mat, vatten och energiefterfrågan i landet. Mat, vatten och energi är idag bristvaror i Etiopien, och klimatförändringar har medfört ytterligare belastning på mat, energi, och vattensystemen i landet. Landet har en stor outnyttjad potential för att utöka den förnybara energianvändningen. Etiopien strävar efter att utveckla land, vatten, energisystemen, och samtidigt göra de mer klimattåliga. Land, energi, och vattenresurserna är ändliga, och en hållbar användning av dessa resurser är därmed viktig. I detta arbeta undersöks de Etiopiska vatten, land och energisystemen för att identifiera systemövergripande utmaningarna och deras inverkan på mat, vatten och energiresurserna i landet. Vidare undersöks även systemens sårbarhet för klimatförändringar. Denna integrerande bedömnings görs genom att skapa en modell av Etiopiens klimat, land, energi, och vattensystem med hjälp av energimodelleringsverktyget OSeMOSYS. Studien visade att en utveckling och omställning av jordbrukssektorn, från ett övervägande nederbördsberoende jordbruk till en jordbrukssektor med en större andel irrigation, hade båda fördelaktiga och negativa effekter. Utvecklingen av jordbrukssektor ökade hektarskörden och skapade ett mer klimattåligt jordbruk. Däremot är det konstbevattnade jordbruket dyrare med ett större vatten och elbehov, vilket i sin tur belastar vatten och energisystemen. Studien visade även att klimatförändringar har en negativ påverkan på elproduktionen. Ett mer klimattåligt energisystem kan skapas genom att investera i mer vindkraft, solkraft och hållbar bioenergi.

Ample land for agriculture is a valuable resource and combining agriculture and photovoltaicpowerplant can give more effective usage of the available area. The vertical double-sidedpanels used in this study are more dependent on the albedo compared to standard-mountedpanels. This study searched for and implemented available albedo models and used researchdata gathered from the agrivoltaic site in Kärrbo Prästgård over two periods of differentseasons. In-situ measurements were studied concerning the albedo's impact on power outputwith the focus on comparing albedo with power output during ground conditions Ley, Winterwheat, and snow. Two models were found and tested with the available in-situ data tovalidate if the models could predict the albedo, both daily and hourly during the differentseasons. Most of the work on the models was coded in MATLAB. The impact of albedo wasshown to differ between the two photovoltaic systems and the different ground conditions.The hourly albedo model produced a decent prediction, both on the summer set and winterset with input of site-dependent measurements of irradiance. The daily albedo model withthe input of satellite data produced a good albedo prediction for both seasons. Both models can be used to predict a more refined albedo value. Keywords: agrivoltaic, photovoltaics, albedo, model, LIN-FIT, prediction

This paper deals with heat transfer in plate evaporators, with a focus on the effects caused by carried-over compressor oil ending up in the heat exchanger. A common standpoint in literature regarding the effect of immiscible oil contamination, in for example an ammonia PHE evaporator, is that the oil can accumulate as a layer on the plate surface causing an additional thermal conduction resistance. However, it is questionable whether this simplistic reasoning is sufficient to fully describe the effect of the oil in the evaporator. In any case, the often severe heat transfer degradation experienced with immiscible oil contamination should be worth analyzing thoroughly from different perspectives. Validated knowledge of what really happens to the boiling and the heat transfer in theunit under the influence of the lubricant can obviously be valuable. Let it be as a potential tool in designing or improving systems that avoid negative oileffects, or just to further validate current knowledge. The work presented in this report aims to emphasize that immiscible oil in a PHE plate gap not only affects the heat transfer in terms of an insulating layer, but can also show as changed appearance and characteristics of the boiling. A special flooded PSHE evaporator with a transparent end-wall was used inthe experimental part, tested in a thermosiphon-type of loop. Differences between an oil-free reference case and an oil-contaminated situation were revealed visually by using high-speed video capture. The boiling tests were limited to water as refrigerant as a first step. Similar studies with ammonia as refrigerant would be natural to aim for in a next step. Based on the visual study of the surface, some possible connections to the heat transfer were hypothesized. Observed phenomena were related to bubble nucleation, vapor/liquid movements, and flow patterns. Effects on heat transfer were mainly discussed in terms of changed surface characteristics, such as liquid repellency and wettability. The interpretations herein suggest that, to get the full picture of how immiscible oil influences the heat transfer, it may be worth to study or discuss the issue in terms of altered plate surface characteristics and interface interactions in the four-phase system (solid-oil liquid-vapor). / Detta arbete behandlar värmeöverföring i plattförångare, med fokus på hurdenna påverkas när olja från systemets kompressor hamnar i värmeväxlaren. En vanlig utgångspunkt i litteraturen gällande effekten av oblandbar olja i förångaren, exempelvis i en plattvärmeväxlare för förångning av ammoniak, är att oljan ansamlas som ett skikt på platt-ytorna och att detta orsakar ett ytterligare värmeledningsmotstånd. Frågan är om detta förenklade resonemang är tillräckligt för att beskriva oljans påverkan i förångaren. I vilket fall som helst bör den ofta avsevärda försämringen av värmeöverföringen till följd av kontamination med oblandbar olja vara värd att analysera grundligt ur olika synvinklar. Validerad kunskap om hur kokningen och värmeöverföringen egentligen påverkas av oljan kan utgöra ett verktyg för att designa eller förbättra system som undviker negativa oljeeffekter, eller bara för att ytterligare bekräfta nuvarande kunskap. Arbetet som presenteras i denna rapport belyser att oblandbar kompressor olja inte bara påverkar värmeöverföringen i form av ett isolerande skikt, utan även kan visa sig som förändrat utseende och egenskaper hos kokningen. I den experimentella delen av arbetet användes en testrigg av termosifontyp med en speciell flödande plattförångare av PSHE-typ utrustad med transparentsidovägg för observation av kokningen. Skillnader mellan ett oljefritt referensfall och en oljekontaminerad situation uppdagades visuellt med hjälp av höghastighetskamera. Som ett första steg var testerna begränsade till vatten som köldmedium. Liknande tester med ammoniak som köldmedium vore ett naturligt nästa steg för vidare studier. Baserat på den visuella undersökningen av ytan diskuteras några möjliga kopplingar till värmeöverföringen. Observerade fenomen relateras till bubbelbildning, ång-/vätskerörelser och flödesmönster. Effekter på värmeöverföringen diskuteras främst i termer av förändrade ytegenskaper, såsom vätskeavstötning och vätbarhet. Tolkningarna här tyder på att det, för att få en helhetsbild av hur icke-blandbar olja påverkar värmeöverföringen, kan vara värt att studera eller diskutera frågan i termer av förändrade ytegenskaper på plattan samt gränssnittsinteraktioner i fyrfassystemet (fast-olja-vätska-ånga). / For Finnish see document

The project aims at quantifying differences in power production and fatigue loads for wind turbines placed in the Baltic sea and in forested, topographically-complex areas compared to turbines placed offshore and in flat terrain. Based on these results, suggestions will be provided on how to optimally site and operate turbines in these conditions. / <p>Introduktionsuppsats på forskarutbildning.</p>

This project involves analyzing if there are opportunities to make energy savings by finding the optimal operating point for the pumps and whether there are any other energy saving opportunities in the pumping process. This project is carried out for Tekniska Verken i Kiruna AB and included their various facilities. Through tests for the various facilities the optimal speed for each pump was identified. This was carried out with help from the program Drive composer and with help from frequency converters. The results showed that the total savings that could be made by controlling the pumps towards the optimal speed was 9400 kWh per year. The significant savings opportunity for Tekniska Verken i Kiruna AB is to shift the operations to the time that is not covered by the peak period. With a change in operation of 20%, savings for 180 000 SEK per year can be made, while the load of the electricity grid from a large consumer is reduced during times when there are more users on the electricity grid. Investing in frequency converters for the pumps that don’t have one, is a profit from an energy saving perspective as well as from a financial perspective, where the payback period for this type of investment is calculated just over a year. This is applied to the purchase of frequency converters of the type found on the current pumps.