One of the great challenges facing society is to convert theglobal energy system to a sustainable process. Currently, 80%of the world´s energy is supplied through the combustionof fossil fuels. Not only are the fossil resources limited, theutilisation also increases the level of greenhouse gases in theatmosphere. The convertion to a sustainable energy system isproblematic since the technology needed to exploit mostnon-fossil energy sources is not yet fully developed, e.g.solar energy. Biofuel is an available renewable energy sourcewhich is already widely used in many countries. If an effectiveswitch-over from fossil fuels to biofuels is to be realised,biofuels must be viewed as a limited resource. Consequently, itis important that the handling, upgrading and utilisationprocesses involving biofuels are efficient so that itspotential can be fully exploited. This thesis considers efficient biofuel utilisation andupgrading within the sawmill industry. The goal has been toanalyse not only the technical opportunities for energy savingsin the sawmill industry, but also to analyse the costeffectiveness and environmental impact of studied measures. Theheat demand of the sawmill industry is almost completelycovered by its own by-products; primarily bark, sawdust andwood chips. The increased demand and improved economic value ofwoody biofuels on the market is thus an incentive for thesawmill industry to place more focus on energy issues. Thesawmill industry also has a more or less constant heat loadover the year, which is a beneficial factor for integrationwith district heating networks, biofuel upgrading plants andcombined heat and power plants. The conclusion of the study is that a variety of energyproducts such as heat, unrefined biofuel, pellets andelectricity can be efficiently produced in the sawmill industryand sold for profit to external customers. The payback periodsfor the proposed investments are moderate and both theemissions of volatile organic compounds and global CO2 aredecreased. Should the proposed measures be fully implemented atSwedish sawmills, about 2.8 TWh of biofuel could be savedannually, 0.5 TWh of waste heat could be sold as districtheating and 0.8 TWh of green electricity could be produced.Language: English Keywords:Sawmill industry, energy efficiency, heatrecovery, integration, biofuel, upgrading, district heating,fuel pellets, CHP, VOC, CO2

Currently pelletized woody biomass is widely used as a fuel in thermal applications toaccelerate the global transition to renewable energy. Fuel upgrade is one of the key factorsto improve energy conversion processes. Woody biomass can be fractionated into its mainconstituents by steam explosion. Steam-exploded biomass exhibits enhanced heating valueand improves pellet durability. Moreover, there is a significant deviation in thermochemicalbehavior of steam exploded (steam-treated) biomass with respect to the raw material duringpyrolysis. This thesis work concerned combustion characteristics of steam-exploded salix. The steamtreatedmaterial was pelletized and combusted under 21% of oxygen with varying thereactor temperature from 500 to 900°C to study the influence of both surrounding andpretreatment conditions during combustion process. The impact of different pretreatmentseverity factors (Ro) on burning behavior was evaluated: mild (205°C-6min, Ro=3.87),intermediate (205°C-12min, Ro=4.17) and severe (228°C-12min, Ro=4.84). Heterogeneousand homogenous ignition mechanisms were observed, which were dependent on the reactortemperature. The ignition time and devolatilization duration were observed independent onpretreatment severity near 900°C, and slightly influenced near 500°C. Enhanceddevolatilization rate was detected with the increment of Ro from 3.87 to 4.17, whilst themost severe pretreatment conditions (Ro=4.84) weakened biomass reactivity duringdevolatilization. Finally, char reactivity was lowered as a result of the increment ofpretreatment severity.

Invasive species exact important ecologic, economic, and cultural tolls in forests. This research focused on the intersections of invasive ecology, forest management, and a forest commodity. Invasive ecology was explored through an assessment of two potential biological control agents of hemlock woolly adelgid. The two species of silver fly (Leucopis spp.) from the Pacific Northwest were first examined for temporal resource partitioning patterns. The niches of these species were then examined spatially by developing a species distribution model. Leucopis spp. exhibited sinusoidal patterns of daily emergence when examined over a 29-day period, with peak daily abundances that were inversely related. Spatially, however, landscape-scale and climatic indicators were not significant in predicting the presence of Leucopis spp. in the Pacific Northwest. This adds important information about niche dynamics of Leucopis spp. in the Pacific Northwest, which may have logistical and operational implications for their use in the USDA Forest Service’s Hemlock Woolly Adelgid Initiative. Additionally, the potential opportunities and risks of using wood that has been impacted by invasive species and pests was explored through a literature analysis focused on three species posing a threat to northeastern US forests: emerald ash borer, hemlock woolly adelgid, and southern pine beetle. Based on this review, I concluded that although opportunities for the use of this wood are sometimes recognized, the phytosanitary risks in feedstock pre-treatment are not being directly addressed in US-related literature. These studies provide important evidence for adaptive solutions to forest pests that consider both forest health and forest economics.

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[pt] O presente trabalho apresenta uma análise do fenômeno de carburização na zona de redução de um forno de cuba tipo Midrex. É realizada uma análise dos principias trabalhos existentes na literatura, é apresentado o aparato experimental, a caracterização das amostras e os resultados obtidos. Os experimentos foram efetuados com o auxilio da ferramenta estatística denominada planejamento fatorial. O tempo dos experimentos foi variado, simulando a operação industrial, com a finalidade de obter o equacionamento cinético. A função obtida foi não linear, envolvendo uma função transcendental, a qual melhor se ajustou aos pontos experimentais. A partir destes resultados foi efetuado uma análise termodinâmica das reações de carburização mais provaveis da zona de redução e determinados os parâmetros cinéticos da carburização. Estes ultimos foram: fator temporal, Tau de 1,32 h, tempo de incubação de 0,30 h, para 500 ºC, e 0,80 h para 900 ºC; fator de carbono de saturação A para 500 ºC com vazão de 60 NL/min foi de 2,70 %, com 90 NL/min de 3,46%; para 900 ºC com 60 NL/min foi 0,10 % e para 90 NL/min de 0,16%. Finalmente, os calculos das velocidades iniciais do processo de carburização foram de 2,3 %C.h-1, para 500 ºC e 0,10 %C.h-1 a 900ºC, para uma fração carburante de 0,37. Os resultados mostraram que o conteúdo de carbono no ferro esponja, obtido nesta zona para as condições reais do processo, alcançou uma média de 0,043 %C, fato de relevante importância para os processos de redução direta em forno de cuba. / [en] In this work an analysis of the carburation phenomena in the reduction zone of the type Midrex Furnace is presented. A revue of the principal papers found on the subject`s literature is followed by the description of the laboratory apparatus, sample characterization, and finally, the obtained experimental results are presented. The experimental planning and screening for this work was defined by a factorial analysis. Further the residence times for all experiments were defined to simulate the actual furnace industrial operation. Also, the experiments aimed at the determination of the parameters belonging to mathematical transcendental formulae designed to simulate the furnace`s charge behavior. Based upon the results, a thermodynamical analysis was conducted obeying the operational conditions inside the furnace, this to determine all the viable carburation reactions. The analysis was followed by kinetic evaluations that produced the data for the carburation process exponential formula parameters determination, namely exponential time factor = 1,32 h; incubation time, 0,30 h at 500 oC and 0,80 h at 900 oC and carbon saturation factor A, ranging from 2,7 % for a gas flow rate of 60 NLmin-1, 3,6 % for a gas flow rate of 90 NLmin-1 to 500 oC and 0,10 % for a gas flow rate of 60 NLmin-1, 0,16 for a flow rate of 90 NLmin-1 to 900 oC. Besides, the initial carburation rates were determined for atmospheres having carburating ratios of 0,37, and they measured 2,3 %C.h-1 for 500 ºC and 0,10 %C.h-1 for 900 ºC. Wrapping up the results this work showed that an average of 0,043 %C in the DRI is to be expected in the reducing zone for the actual industrial conditions.

What kinetic and thermodynamic characteristics are established in a melt of hydrogen-reduced iron ore pellets? The pellets contain self-fluxing slag components which upon melting form an initial slag. Refining capabilities of this slag, such as dephosphorization power, are investigated in a lab-scale vertical furnace. Understanding the initial slag and the reactions taking place when hydrogen-reduced iron ore pellets melt is important for future optimization of ingoing raw materials as well as industry scale process design. A sample of either crushed hydrogen-reduced iron ore pellets or a powder mixture representative of iron ore pellets in terms of composition was melted in a lab-scale vertical furnace. The sample was lowered into the argon atmosphere furnace which had a temperature of 1600°. The sample was kept inside a magnesia crucible with a molybdenum loosely-fitted lid. The purpose of the lid was to fix the oxygen partial pressure. The reduction degree of the pellets or corresponding powder mixture as well as the total melting times were varied. XRF and OES analysis were employed to find the composition of the slag and metal phases, respectively. SEM analysis was employed to investigate phases present in the slag. Comparison of melted iron ore pellets and corresponding powder mixture show that powder can be employed to represent reduced iron ore pellets accurately. It was found that reduction degree strongly impacts both phosphorus and vanadium distributions as well as the types of phases formed in the slag fraction. During melting, almost all of the Vanadium and most of the Phosphorus content goes to the slag fraction. At lower reduction degrees, dephosphorization is greater; however, the Phosphorus content in the steel is still quite high at 130 ppm or higher. Modification to the amount and/or composition of the self-fluxing slag is suggested to reach lower levels of phosphorus in the steel. / Vilka kinetiska och termodynamiska egenskaper skapas i en smälta av vätgasreducerade järnmalmspellets? Pellets innehåller självflussande slaggkomponenter som vid smältning bildar en initial slagg. Slaggens raffineringsförmåga, till exempel fosforreningsförmåga, undersöks i laboratorieskala. För framtida optimering av ingående råvaror såväl som industriellskalig processdesign är det viktigt att förstå den initiala slaggen samt de reaktioner som äger rum vid nedsmältning av vätgasreducerade järnmalmspellets. Ett prov av antingen krossade vätgasreducerade järnmalmspellets eller en pulverblandning som är representativ för järnmalmspellets med avseende på sammansättning smältes ned i en laboratorieskalig vertikal ugn. Ugnen hade en argonatmosfär och temperatur på 1600°C då provet sänktes ner i ugnen för smältning. En magnesiumoxiddegel med ett löst inpassat molybdenlock användes som behållare för provet under nedsmältningen. Syftet med locket var att kontrollera syrgaspartialtrycket. Reduktionsgraden av pellets eller motsvarande pulverblandning såväl som de totala smältningstiderna varierades. XRF och OES mätverktyg användes för att undersöka sammansättning av slagg- och metallfraktionerna. SEM analys användes för att identifiera närvarande faser i slaggfraktionen. Jämförelse av nedsmälta vätgasreducerade järnmalmspellets med motsvarande pulverblandning visar att de två är representativa av varandra till stor grad. Resultaten visar på att reduktionsgraden påverkar starkt både fosfor- och vanadinfördelningarna samt faserna som bildas i slaggfraktionen. Vid smältning går nästan all mängd vanadin och majoriteten av fosfor till slaggfraktionen. Vid lägre reduktionsgrader är fosforreningen bättre. Fosforhalten i stålet är relativt hög och har ett värde på 130 ppm eller högre för samtliga prover. Ändring av mängden och/eller sammansättning av den självflussande slaggen rekommenderas för att nå lägre nivåer av fosfor i stålet.

<p> An Experimental investigation has been conducted to determine the effects on degree of reduction and efficiency of utilization of gases of changes in the levels of several variables when reducing fixed beds of commercial hematite pellets. The effects on reduction behaviour of changes in the levels of reducing gas composition and flow rate, and reaction temperature, were determined by graphical and numerical techniques.</p> / Thesis / Master of Engineering (MEngr)

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[EN] In the framework of a sustainable bio-based economy, this doctoral thesis aims to stimulate sustainable forest management by providing scientific information and guidelines tending to plan and mobilizate bioenergy resources from Mediterranean forests, protect forest ecosystems from forest fires, optimize the carbon balances of the entire bioenergy value chain and finally, contribute to the rural development through employment and richness creation in the renewable energy sector. To achieve these goals, the general objective of this research is to analyse and develop an integral management, planning, logistics and energy valuation model for the forest biomass residues available in the Valencian Province. For that purpose, forest and agricultural crops data in the Valencian Province have been analised by using Geographical Information Systems (GIS) and applying selection and sustainable harvesting criteria. Biomass quantity and real available biomass residues have been estimated. Based on a sustainable management, planning, logistics, transformation and biomass use model, eight bioenergy districts have been identified at a supramunicipal level. Representative forest plots have been selected and two harvesting systems, the integrated system (separated use of logs and forest residues) and the whole tree system, have been tested. Subsequently, productivity, costs, environmental impact, carbon emissions and energy balances have been compared and the quality of the obtained chips has been analysed according to European quality norms. In addition, a pilot pellet plant at a laboratory scale has been designed and started and pellets have been fabricated. Finally, pellet quality and influencing variables such as species, tree fraction of the chips and bark presence have been studied together with the maximum amount of bark that quality pellets can tolerate. It has been estimated 28t/ha of residual biomass for the Valencian Province. A total of eight bioenergy districts have been identified, which could provide a in which a sustained supply of high quality biomass. Representative forest plots are those with a pole stage of Pinus halepensis with a canopy cover estimated in between 40-69% at altitudes around 600 m above the sea level, east-southwest dominating aspects and 15% of average slope. The integrated system has proven to be the most suitable for harvesting Pinus halepensis in a pole stage in the Valencian Province due to a higher harvesting productivity, which in turn means lower fuel consumption, lower total costs, higher economic and financial profitability due to the higher value of log woodchips in the market, lower environmental impact due to the need of less manoeuvrability forwarder space with the integrated systems and a lower number of cycles, slightly lower emissions thanks to a lower fuel consumption and finally, a slightly higher energy balance, with an energy contained in biomass that is around ten times the energy necessary for the biomass mobilization and use. In conclusion, it is possible to obtain high quality woodchips from these two harvesting systems (integrated and whole tree system) when moisture and ash content are properly monitored. It is also possible to obtain high quality pellets from barked and debarked logs as well as from branches. This implies that the abundant forest biomass residues in the Valencian Province can be transformed into high added value solid biofuels. / [ES] En el marco del desarrollo de una bioeconomía sostenible, esta tesis doctoral pretende estimular la gestión forestal sostenible orientada a la ordenación y movilización de los recursos bioenergéticos de los montes mediterráneos, proteger los ecosistemas forestales frente a los incendios forestales, optimizar los balances de carbono en la cadena de valor de la bioenergía forestal y, finalmente, contribuir al desarrollo rural mediante la generación de empleo y riqueza en el sector de las energías renovables. Para alcanzar estos retos, el objetivo general de la investigación es el análisis y el desarrollo de un modelo integral de gestión, planificación, aprovisionamiento y valorización energética de la biomasa forestal residual de la Provincia de Valencia. Para ello, se ha analizado el territorio de la Provincia de Valencia a partir de información forestal y agrícola recogida en distintas bases de datos mediante la aplicación de Sistemas de Información Geográfica (SIG) y de criterios de selección y aprovechamiento sostenible. Se ha estimado la cantidad de biomasa agroforestal residual existente y aprovechable. Se han definido e identificado distritos bioenergéticos en base a un modelo sostenible de gestión, aprovisionamiento, transformación y uso de la biomasa a escala supramunicipal. Se han seleccionado parcelas forestales representativas y en ellas se han llevado a cabo aprovechamientos experimentales de biomasa mediante el sistema de aprovechamiento integrado (aprovechamiento separado de fuste y residuos forestales) y el sistema de árbol completo. A continuación, se han comparado rendimientos, productividad, costes, rentabilidad, impacto ambiental, emisiones de carbono y balances energéticos de ambos sistemas. Posteriormente, a partir del material recogido se ha analizado la calidad de las astillas según la normativa de calidad europea. En paralelo, se ha diseñado y puesto en marcha una planta piloto a escala de laboratorio para la fabricación de pellets a partir de astillas obtenidas en campo. Por último, se ha analizado la calidad de los pellets y se ha estudiado la influencia de factores como la especie, la fracción del árbol y la presencia de corteza sobre las variables de calidad, estableciendo los límites máximos tolerables de corteza para la producción de pellets de calidad. Como resultados, se ha estimado que en la Provincia de Valencia la cantidad de biomasa residual aprovechable es de en torno a 28t/ha, identificándose ocho distritos bioenergéticos en que se podría dar un suministro sostenido en cantidad y calidad de biomasa en base a sus propios recursos agroforestales. Las parcelas representativas de las masas dominantes pertenecen al estrato Pinus halepensis en estado de latizal-fustal con una fracción de cabida cubierta de entre el 40-69%, situadas a altitudes medias de 600 m sobre el nivel del mar, con orientaciones dominantes este-suroeste y pendientes medias en torno al 15%. El sistema de aprovechamiento integrado ha resultado ser el más adecuado para el aprovechamiento de estas masas debido a un mayor rendimiento en el desembosque que se traduce en menores consumos de combustible, menores costes totales, mayor rentabilidad económica y financiera, un menor impacto ambiental, emisiones ligeramente menores en el sistema integrado frente al completo y un balance energético algo superior, siendo la energía contenida en la biomasa, en ambos casos, diez veces superior respecto a la que se necesita para su aprovechamiento. Se concluye que es posible obtener astillas de calidad procedente de estos sistemas de aprovechamiento biomásico (fustes y árbol completo) siempre que se controle la humedad y el contenido en cenizas y que es posible obtener pellets de alta calidad a partir de fustes descortezados y sin descortezar, así como de su fracción de ramas, lo que implica que los abundantes recursos biomásicos en la Provincia de Valencia pueden ser transformados en / [CA] En el marc del desenvolupament d'una bioeconomia sostenible, aquesta tesis doctoral pretén estimular la gestió forestal sostenible orientada a l'ordenació i movilització dels recursos bioenergètics dels forets mediterranis, protegir els ecosistemes forestals front als incendis forestals, optimitzar els balanços de carboni en la cadena de valor de la bioenergia forestal i, finalment, contribuir al desenvolupament rural mitjançant la generació de treball i riquesa en el sector de les energies renovables. Per a assolir aquests reptes, l'objectiu general de la investigació és l'anàlisis i el desenvolupament d'un model integral de gestió, planificació, aprovisionament i valorització energètica de la biomasa forestal residual de la Provincia de València. Per a fer açò possible, s'ha analitzat el territori de la Provincia de València a partir d'informació forestal i agrícola recollida en distintes bases de dades mitjançant l'aplicació de Sistemes d'Informació Geogràfica (SIG) i de criteris de selecció i d'aprofitament sostenible. S'ha estimat la quantitat de biomasa agroforestal residual existent i aprofitable. S'han definit e identificat districtes bioenergètics en base a un model sostenible de gestió, aprovisionament, transformació i ús de la biomasa a escala supramunicipal. S'han seleccionat parcel·les forestals representatives i en elles s'han dut a terme aprofitaments experimentals de biomasa mitjançant el sistema integrat (aprofitament per separat de canó i de residus forestals) i el sistema d'arbre complet. A continuació, s'han comparat ambdós sistemes pel que fa a rendiments, productivitat, costs, impacte ambiental, emissions de carboni i balanços energètics. Posteriorment, a partir del material recollit s'ha estudiat la qualitat de les estelles generades amb els aprofitaments segons la normativa de qualitat europea. En paralel, s'ha disenyat i posat en marxa una planta pilot a escala de laboratori per a l'elaboració de pellets a partir de les estelles obtingudes de camp. Per últim, s'ha analitzat la qualitat dels pellets i s'ha estudiat la influència de factors com l'espècie, la fracció de l'arbre i la presencia d'escorça sobre les variables de qualitat establint els límits màxims tolerables d'escorça per a la producció de pellets de qualitat. Com resultats, s'ha estimat que en la Provincia de València la quantitat de biomasa residual aprofitable és d'al voltant de 28t/ha, identificant-se huit districtes bioenergètics en els que es podria donar un sumisitre sostingut en quantitat i en qualitat de biomasa en base als seus propis recursos agroforestals. Les parceles representatives de les mases dominants perteneixen al estrate Pinus halepensis en estat de perxada amb una desnitat de recobriment de entre el 40-69%, situades a altituds mitjanes de 600 m sobre el nivell del mar, amb orientacions dominants est-suroest i pendents mitjanes al voltant del 15%. El sistema d'aprofitament integrat ha resultat ser el més adequat per a l'aprofitament d'estes mases dominants debut a un major rendiment en el desembosc que se tradueix en menors consums de combustible, menors costs totals, major rentabilitat econòmica i financiera, un menor impacte ambiental, unes emissions lleugerament menors del sistema integrat front al complet per menor consum de combustibles i un balanç energètic lleugérament superior, siguent l'energia continguda en la biomasa per a amdós sistemes deu voltes superior respecte a la que es necessita per a la seua mobilització i aprofitament. Se conclou que és possible obtindre estelles de qualitat procedent d'aquests sistemes d'aprofitament biomàsic (canó i arbre complet) sempre que se controle la humitat i el contigut de cendres i que és possible obtindre pellets d'alta qualitat a partir de canons descorçats i amb escorça, així com de la seua fracció de rames, el que implica que els abundants recursos biomàsics de la Provincia de València poden ser / Lerma Arce, V. (2015). Planificación, logística y valorización de biomasa forestal residual en la provincia de Valencia [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52391