Biofuel is a renewable and sustainable energy source with near-neutral carbon footprint. Algae are an ideal feedstock for biofuel production because they reproduce quickly and have high oil. Algae can be cultivated in non-arable land, and would not impact the food supply. Unfortunately, processing algae into biofuel is more expensive than land crops due to the large volumes of dilute algal suspension that must be harvested and concentrated. In order to improve algae-based biofuel economics, resins were developed that reduce costs associated with water pumping and transport. Hydrophobic resins were developed for binding oil out of an algal suspension so that the residual biomass could be recovered without solvent contamination. Binding behavior displayed lipid species specificity, and binding capacity was improved by ethanol treatment of the biomass. Algae was harvested by binding to anion exchange resin and directly converted into biodiesel. One-step, room temperature in situ transesterification of algae yielded nearly as much biodiesel as two-step, heated transesterification of dried biomass. Elution with transesterification reagent also regenerated the resin for subsequent algal binding. Functionalized resins were developed with high algal binding capacity at neutral pH. Binding was easily reversed, as treatment with buffer with pH higher than pKa of the resin functional group removed the algae and regenerated the resin for subsequent use. The resin bound 10% of its weight in algae and released it as a 100-fold concentrated suspension. The polymers developed can be scaled up for commercial processes and reduce algal harvesting and concentration costs. / text

Η παρούσα ερευνητική αυτή εργασία που αφορά στην οπτική παρατήρηση των αποθέσεων των αλάτων ανθρακικού ασβεστίου σε πορώδη μέσα εκπονήθηκε με στόχο την διερεύνηση του μηχανισμού σχηματισμού αποθέσεων ανθρακικού ασβεστίουσε πορώδη μέσα. Τα πειράματα έγιναν σε υάλινα και πλαστικά πορώδη υλικά και εξετάσθηκαν οι παράγοντες του υπερκορεσμού, της θερμοκρασίας, του pH, της παροχής και πως αυτοί επιδρούν στο σχηματισμό των κρυστάλλων ανθρακικού ασβεστίου και στον τρόπο απόθεσης του άλατος στα διάφορα τμήματα του πορώδους μέσου. / This present inquiring work that concerns in the optical observation of depositions of calcium carbonate salts in poroys media it was worked out amining at the investigation of mechanism of shaping of calcium carbonate depositions in porous media. The experiments were made and plastic porous materials and were examined the factors of supersaturation, temperature, pH and the benefit of its effect in the shaping of calcium carbonate crystals and in the way of deposition of salt in the various departments of porous means.

L'extraction d'huile de graines d'oléagineux en milieu aqueux a pour principal objectif la suppression des solvants utilisés dans les industries de trituration. Pour extraire l'huile des graines, les mélanges enzymatiques et de nombreux paramètres physico-chimiques ont été étudiés. Deux plans d'expériences consécutifs, réalisés sur le M.I.A. ont permis de formuler des mélanges d'enzymes efficaces, constitués de 3 ou 4 préparations enzymatiques commerciales parmi les 25 retenues initialement. Cette démarche permet de réaliser des mélanges optimaux pour la dégradation des parois des graines étudiées. Les extractions d'huile font apparaître 4 phases après séparation par centrifugation : résidu solide, émulsion, phase aqueuse et huile libre. Les effets de différents paramètres physico-chimiques ont été évalués (broyage, temps, température, agitation, séparation...). Au final, l'huile libérée des graines à l'aide des mélanges formulés (85% de l'huile totale pour le colza, 92% pour le tournesol), la quantité de sucres fermentescibles produite (entre 60 et 80 g/l en fonction des conditions) ou encore la concentration de protéines solubilisées (supérieure à 30g/l) sont les résultats marquants de cette étude. Cette étude décryptant les conditions à mettre en œuvre pour maximiser l'extraction d'huile en phase aqueuse constitue un socle de connaissances permettant d'envisager le développement futur d'un bioraffinage complet des graines de colza grâce à la valorisation de chacun des co-produits huiles, protéines (napines du colza) et sucres fermentescibles. / The extraction of oil from oilseed in an aqueous medium aims to remove the solvents used in the crushing industry. To extract oil from seeds, the enzymatic mixtures and numerous physico-chemical parameters have been studied. Two consecutive experimental designs, realized on the A.I.M. prepared from treated seeds, allowed to select effective enzyme mixtures, consisting of 3 or 4 commercial enzyme preparations out of the 25 originally selected. This original approach, based on the use of statistical tools, allows to achieve optimal mixtures for the degradation of the walls of studied seeds. The extraction of oil shows 4 phases after separation by centrifugation: solid residue, emulsion, aqueous phase and free oil. The effects of different physico-chemical parameters were evaluated (grinding time, temperature, agitation, separation...). Finally, the oil released from seeds using enzymatic mixtures made (85% of the total oil for rapeseed, 92 % for sunflower), the amount of fermentable sugars produced (60 and 80 g/l depending on conditions) or the concentration of solubilized protein (greater than 30g/l) are the landmark results of this study. This study, decrypting the conditions to implement the maximization of oil extraction in aqueous phase, is an important whole of knowledge to contribute the future development of a complete biorefining of rapeseed and sunflower with the use of each co-products : oils, proteins (napins from rape) and fermentable sugars.

No / This article evaluates Tourinho's (1979) work as one of the earliest contributors to the real options literature. His model pioneered the application of risk neutrality to uncertain investments, but his originality of introducing an option-holding cost albeit to overcome the extraction paradox is rarely imitated. We claim that the combination of a convenience yield and an option-holding cost produces a more satisfying representation. Moreover, variations in the holding cost give rise to a host of investment decisions ranging from the standard real option solution for a zero-holding cost to a net present value solution for an infinite-holding cost. Not only does the holding cost mediate between these two poles, but it provides the option seller (usually a landowner or a government) with a policy instrument for influencing the extraction timing and thus the extraction profit of the option buyer. We derive the holding cost that optimizes the landowner's combined value of the option premium, holding costs and eventual royalties.

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La présente étude a eu pour objectif la comparaison de la fabrication du biodiesel à partir de graines de caméline suivant les procédés conventionnels ou assistés/intensifiés par Détente Instantanée Contrôlée (DIC). La caméline est l'une des matières premières les plus adaptées à la fabrication de biodiesel puisqu’elle ne présente aucune concurrence aux cultures alimentaires et/ou à l’utilisation des terres agricoles. Son intérêt réside en sa teneur élevée en huile, sa courte saison de culture, ainsi que sa grande capacité à enrichir les sols pauvres, arides ou semi-arides. L'insertion de la texturation par DIC permet l'intensification à la fois de 1/ l'extraction de l’huile suivie de transestérification et 2/ du processus de transestérification in-situ en une seule étape. Dans les deux cas, les analyses statistiques ont conduit, à l'aide de la méthode de surface de réponse (RSM), à des modèles mathématiques empiriques adéquats capables de mieux développer les résultats expérimentaux, d'optimiser les paramètres de traitement et de mieux définir le changement d’échelle. Le procédé DIC se distingue par son aptitude à réaliser avec succès l’expansion structurelle des produits naturels sans affecter la qualité des huiles et des carburants produits. L'augmentation de la quantité d'huile extraite après texturation des graines par DIC a été de 38% et 22%, respectivement pour le pressage et l'extraction par solvant. En mode ISTE, la texturation DIC a permis de doubler le rendement en FAMEs. En outre, la technologie DIC est une technique très économique en raison de la grande capacité de traitement due au faible temps d’opération et d’une consommation réduite d'énergie. / The objective of this study was to compare the production of biodiesel from Camelina seeds using conventional methods or assisted/intensified by Instant Controlled Pressure-drop DIC. Camelina is one of the most suitable feedstocks for biodiesel production as it does not compete with food crops and/or agricultural land use. Its interest lies in its high oil content, short growing season, and great ability to enrich poor, arid or semi-arid soils. The insertion of texturing by DIC allows the intensification of both 1/ extraction of the oil followed by transesterification and 2/ a single step in-situ transesterification process. In both cases, using the response surface method (RSM), statistical analyzes have led to adequate empirical mathematical models capable of better developing experimental results, optimizing treatment parameters and better define the scaling-up. The DIC process stands out for its ability to successfully achieve the structural expansion of natural products without affecting the quality of sensitive compounds such as oils and fuels produced. The increase in the amount of oil extracted after DIC texturing of seeds was 38% and 22% for pressing and solvent extraction, respectively. In ISTE mode, DIC texturing approximately doubled FAMEs yields (98% increased yields). In addition, DIC technology is a very economical technique due to its high processing capacity, low operating time, and weak energy consumption.

This thesis examines the current state of crude oil extraction and production in the Greater Burgan oilfield, Kuwait's largest and oldest oilfield. This thesis is based on interviews with oilfield workers, analyses of official documents from the Kuwaiti government and the Kuwait Oil Company (KOC), and my own experience as an oilfield worker in Kuwait. through this, I trace the changing social and environmental relationships in the Burgan oilfield. Through Actor-Network-Theory and Assemblage Theory, I explore the different actors and the power dynamics negotiated between actants in the oil industry. Specifically, I am interested in how economic and social relationships are assembled in oil economies, how oil dependency impacts society, and how we can prepare for a future without oil. Burgan reservoirs have shifted from natural production to artificial lift, indicating that Burgan has reached its oil production peak. This plateau in oil production has incited KOC to further invest in technology, to compensate for the anticipation in oil production shortfalls. Furthermore, I examine how 'cultures' are created around oil in the oilfields. This leads me to ask how labour security, safety, and dependencies are negotiated in relation to global processes. I conclude that the declining profitability of the oil market is compensated for by lower salaries, the deterioration of working conditions and worker rights. Finally, I explore the long-term health and environmental effects, and how their mitigation is negotiated in the oilfields. The study highlights the practice of gas flaring as leading to carbon emissions in extraction of oil and shows that the official data on flaring is underrepresented. In addition, a lack of awareness and mitigation around Naturally Occurring Radioactive Material (NORM) is highlighted and discussed. Finally, the argument is made that the traditional oil industry in Kuwait is disassembling, KOC now invests in oil markets else-where to compensate for losses. As shown here, oilfield workers are the first point of contact in this complex situation, so they should be considered in the transition process.

Esta dissertação apresenta um estudo ergonômico sobre o trabalho de operadores de processo de plataformas marítimas de produção de petróleo. As primeiras investigações sobre as atuais práticas e produtos finais de projetos de sistemas produtivos de grande porte resultaram em indícios de um ambiente de produção com aspectos operacionais não equilibrados e desintegrados. A partir destes indícios, foi realizada uma revisão bibliográfica que destacou as considerações e limitações de aspectos relacionados à Ergonomia em assuntos como gestão de projetos, projetos de engenharia, de sistemas produtivos e de arranjo físico. A revisão relativa à Ergonomia destacou seus conceitos básicos, a Ergonomia de Concepção e estudos relacionados ao trabalho de operadores de produção contínua, tendo o objetivo de indicar possibilidades de atuações desta ciência em projetos de plantas produtivas. Desta forma, a pesquisa de campo desenvolvida procurou destacar aspectos operacionais como dificuldades e constrangimentos enfrentados pelos operadores. Tais aspectos foram investigados com o objetivo de ressaltar os desequilíbrios presentes nesta situação de trabalho e as estratégias desenvolvidas por estes operadores para manterem o funcionamento satisfatório da unidade produtiva, atendendo aos objetivos da organização empresarial em que se inserem. / This work presents the ergonomics study based on offshore oil production platforms, in operation works for the process plant. The first investigations resulted on indications of disintegrated and unbalanced operational aspects into the production environment. From those evidences, the bibliographical revision indicated the considerations and limits of aspects related to Ergonomics in subjects as design management, engineering design, productive systems and layout design. The revision of Ergonomics included basic concepts, Ergonomics of Conception, and studies related to the operator works of continuous production process, having the aim of indicating participation possibilities of this science in production plants design. In such a way, the developed research tried to raise operational aspects as difficulties and constraints daily faced by operators. Such aspects were investigated intending to stand out the disequilibriums in this situation of work and strategies developed by these operators to keep satisfactory performance of a productive unit, taking care of company goals where they are inserted.

Para aplicações de extração de petróleo de poços em terra foi desenvolvido pelo Laboratório de Eletromagnetismo Aplicado (LMAG) da Escola Politécnica da Universidade de São Paulo um protótipo de motor de indução linear tubular (MILT), onde o movimento axial do secundário do motor aciona diretamente a bomba de extração situada no fundo do poço. Numa segunda etapa, foi prevista a substituição dos mancais mecânicos por dois mancais magnéticos ativos (AMBs), que permitem melhor movimentação e praticamente nenhum atrito, reduzindo o desgaste causado por impurezas contidas no petróleo extraído, e consequentemente os esforços de manutenção. Todavia, o protótipo atual possui apenas um mancal magnético, e o outro é mecânico. O presente trabalho apresenta a instalação do segundo mancal magnético ao protótipo do MILT, e propõe realizar o controle do sistema de mancais magnéticos para o MILT, tendo em vista um problema multivariável, onde as posições do secundário do motor em relação aos dois mancais são correlacionadas, bem como as ações de controle sobre os mesmos. O trabalho faz uma revisão do sistema atual com um AMB, abordando sua concepção física, modelagem e o controlador, e tal controlador é replicado para o segundo AMB. Um novo modelo é apresentado, considerando o comportamento multivariável dos dois AMBs, e um sistema de controle robusto multivariável é projetado, através da técnica LQG/LTR. Resultados de simulação do novo controlador são analisados e comparados com os resultados experimentais do controlador atual aplicado aos dois AMBs, e apresentam-se as conclusões. / For onshore oil extraction applications, a tubular linear induction motor (TLIM) prototype was developed by Applied Electromagnetism Laboratory (LMAG) of Escola Politécnica da Universidade de São Paulo, on which the axial movement of the motor secondary drives the suction pump, placed in the down hole of the oil well. In a second step, it was planned to replace the mechanical bearings by two Active Magnetic Bearings (AMB), in order to have better movement and practically no friction, reducing damages caused by impurities in the oil, thus reducing maintenance effort. Nevertheless, the actual prototype has only one AMB, being the other one a mechanical bearing. This paper presents the installation of the second AMB onto TLIM prototype, and a proposal to implement the control algorithm for the TLIM magnetic bearing system, considering now a multivariable problem, where the position of the motor secondary for both AMB are related, as well as control efforts. The present work review the actual system with only one AMB, approaching its physical construction, mathematical model and applied control system; and this control system is applied to the second AMB. A new model is presented, considering the AMB system multivariable behavior, and a multivariable robust control system is then designed, using LQG/LTR approach. Simulation results for the new controller are analyzed and compared to experimental results from the actual controller applied to both AMB, and some conclusions are presented.

O presente trabalho apresenta a identificação de parâmetros de motor de indução linear tubular para a extração de petróleo, denominado de MATÆOS -- Motor Assíncrono Tubular para Aplicação na Extração de Óleo Subterrâneo. O primeiro passo para a identificação de parâmetros do motor foi a implementação da bancada de testes com o seu sistema de controle e supervisório. O modelo adotado corresponde à situação de operação em regime estacionário e consiste no circuito contendo resistores e indutores tradicionalmente utilizado para representar motores de indução. A identificação dos parâmetros foi realizada por meio de um procedimento de otimização tomando por base o balanço de potência do motor. Para isso, em função dos parâmetros do modelo, definiu-se e minimizou-se uma medida de erro entre as potências medidas e as calculadas pelo modelo para um conjunto pré-fixado de escorregamentos. A solução desse problema de otimização foi obtida por meio de uma busca exaustiva, uma vez que o número de variáveis independentes do problema é pequeno e uma região contendo o ponto de mínimo é conhecida com razoável confiança. Os resultados obtidos indicam que os valores dos parâmetros nominais a quente apresentam algumas diferenças em relação àqueles produzidos pelo método de identificação. Essas diferenças se devem possivelmente a variações nas características térmicas do motor e a erros introduzidos pelos instrumentos de medida. O modelo identificado apresentou uma menor disponibilidade de força e um pior rendimento quando comparado com os valores de projeto do modelo nominal a quente. Apesar disto, verificou-se uma boa proximidade entre a curva característica do modelo e as obtidas experimentalmente. / This work presents the identification of parameters of the tubular linear induction motor for the extraction of oil, called MATÆOS - which is the Portuguese acronym for Asynchronous Tubular Motor for Application to Subterranean Oil Extraction. The first step to the identification of the motor parameters was the implementation of the supervisory and control system for the test bench. The model, which is the usual one containing resistors and inductors, represents the motor operating in steady-state. The parameter identification problem was written as an optimization problem based on the motor power balance. An error between the measured power and the one given by the model was defined and minimized with respect to the model parameters in correspondence to a given set of slipping frequencies. The numerical solution to this problem was obtained by an exhaustive search algorithm. This choice was made because the number of independent variables is small and a region containing the solution is known with a significant degree of confidence. The results obtained show that the nominal values of the model parameters differ slightly from those produced by the identification method. Possibly, such differences are due to the variations in the model caused by temperature changes and to the measurement errors. The identified model presented both a lower available force and a worst efficiency when compared to the nominal design values for the warm motor. Despite this the characteristic curve of the model was quite close to the nominal design one.