Dissertations / Theses on the topic 'Processus de pivot'

Le concept de pivot reçoit beaucoup d'attention sur internet, dans le milieu de l'enseignement, par les accélérateurs de start-up et chercheurs en ingénierie. Toutefois, ce concept reste encore peu exploré dans le domaine scientifique et plus particulièrement en sciences de gestion. De plus, la littérature traitant du sujet n'aborde pas explicitement le processus de pivot de manière systémique en considérant l'entrepreneur, ses artefacts et les acteurs de son écosystème comme un tout indissociable. Par conséquent, l'objectif de ce travail de recherche est de comprendre le processus de pivot dans sa complexité en considérant cette triade comme étant le plus petit élément d'étude. Cette thèse, reposant sur un paradigme épistémologique constructiviste, considère l'entreprise comme un système complexe dont l'intelligibilité doit être trouvée non seulement dans le système lui-même, mais également dans les relations que ce système entretient avec son environnement.La résolution de cette problématique de recherche autour de la notion de pivot s'est déroulée en deux étapes. Dans un premier temps, une revue de la littérature est effectuée et trois propositions de recherche ainsi qu'une modélisation systémique du processus de pivot sont construites par rapport à celle-ci. Dans un deuxième temps, ces propositions et cette modélisation sont confrontées au terrain par le biais d'une étude de cas afin d'évaluer leur robustesse. À la suite de cela, la modélisation systémique du processus de pivot construite par rapport à la littérature est ajustée en conséquence. L'originalité de cette thèse réside dans la grille de lecture systémique mobilisée pour aborder la complexité du processus de pivot. Cette grille de lecture est la triade entrepreneur, artefacts et acteurs de l'écosystème, ainsi que les interactions entre les éléments de cette triade.Cette thèse apporte quatre contributions. Premièrement, elle met en avant une vision holistique du processus de pivot basé sur la systémique. Deuxièmement, elle propose un point de départ pour de futures recherches autour de la notion de pivot. Ce point de départ repose sur une modélisation systémique du processus de pivot validée par une étude de cas. Troisièmement, elle suggère aux entrepreneurs de conserver de la variété au niveau de leur organisation afin d'être plus à même de s'adapter aux changements survenant dans leur environnement. Cette variété se rapporte non seulement au nombre d'éléments présents dans l'organisation, mais également au nombre d'interactions que ces éléments entretiennent les uns avec les autres. Quatrièmement, elle offre une nouvelle définition du concept de pivot basée sur la systémique
The term pivoting is widely used on the internet, in the educational community, by start-up accelerators and engineering researchers. However, pivoting is still little explored in the scientific field, particularly in management sciences. Moreover, the literature on the subject does not explicitly address the process of pivoting by considering the entrepreneur, his artifacts, and the actors of his ecosystem as an inseparable whole. Therefore, this thesis aims to understand the process of pivoting by considering this triad as the smallest element of study. This thesis, based on a constructivist epistemological paradigm, considers the company as a complex system whose intelligibility must be found not only in the system itself but also in the relations that the system has with its environment.The resolution of this research problem was carried out in two stages. In the first stage, based on the literature on pivoting, three research propositions and a systemic model of the process of pivoting are developed. In the second stage, these research propositions and this model are tested empirically utilizing a case study. Following this, the systemic model of the process of pivoting developed from the literature is adjusted accordingly. The originality of this thesis lies in the systemic reading grid used to address the complexity of the pivot process. This reading grid is the triad of entrepreneurs, artifacts, and ecosystem actors, as well as the interactions between the elements of this triad.This thesis makes four contributions. First, it puts forward a holistic view of the process of pivoting based on system theory. Secondly, it provides a starting point for future research on pivoting. This starting point is based on systemic modeling of the process of pivoting validated by a case study. Thirdly, it suggests that entrepreneurs should maintain variety in their organization to better adapt to environmental changes. This variety refers not only to the number of elements present in the organization but also to the number of interactions these elements have. Fourthly, it offers a new definition of pivoting based on system theory

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O objetivo deste trabalho é mostrar o desenvolvimento do modelo de uma planta didática não linear e multivariável usando a resposta ao degrau. Esta planta didática é do curso técnico de automação industrial do IFES SERRA (ES). A partir das equações físicas do processo são desenvolvidas as relações entre as variáveis controladas e as variáveis manipuladas em regime permanente para qualquer ponto de operação. Utilizando a resposta ao degrau, de acordo com sua amplitude, são mapeadas as constantes de tempo do processo. O atraso do modelo é encontrado utilizando os mínimos quadrados. Por fim é desenvolvido um simulador a fim de comparar a resposta no tempo da planta real com a do modelo proposto.
The objective of this dissertation is to show the development of one nonlinear pilot plant model and multivariable using the step response. The pilot plant belongs to the course of industrial process control of IFES - SERRA (ES). From the physical equations of the process, are developed relationships of controlled variables in steady state at any point of operation. Using the step response, are mapped onto the time constants of the process according to the changes of the manipulated variables. The delay model is found using the least squares and step response. Finally we developed a simulator to compare the time response of the real plant with the proposed model.

Mineralogical complexity and declining ore grades poses new challenges to the mining industry. From the grinding point of view, this means that in order to liberate minerals, particles would have to be ground to a finer particle size. Already, comminution is the biggest energy consumer in the concentrating mill. When particles are ground to even smaller particles sizes, costs and energy consumption increase significantly. This coupled with the fact that conventional tumbling mills are ineffective in a size range under 50 µm, has increased interest towards in the use of stirred media mills. This thesis provides basic knowledge about grinding phenomenona in general, the basics of stirred media mills and a a basic testwork conducted with the Outotec stirred media mill (HIGmillTM). The target of the testwork was to investigate the effect of parameters on grinding efficiency. The parameters under investigation were tip speed, milling density, retention time, size and type of the grinding media, and feed scalping. The secondary target of the testwork was to create a standardized test environment and achieve test repeatability. In addition, two different test methods were tested and compared. In the test, the repeatability of the pilot HIGmillTM tests was achieved successfully. The HIGmillTM proved to be very flexible regarding a change in parameters. If the specific grinding energy was kept constant, the grinding efficiency stayed the same regardless of the change in tip speed, retention time, or milling density. Even the wear of the mill internals proved to have no notable effect on the grinding result. This fact gives the HIGmillTM a clear advantage when used in industrial applications. In the testwork semi-continuous and continuous test methods were compared and verified to give the same result. In addition dumping between grinding stages in the semi-continuous test method turned out to be overly cautious
Maailmanlaajuisesti malmioiden mineraalipitoisuudet ovat heikentyneet ja mineraalirakeiden rakenteet ovat tulleet monimuotoisemmiksi. Jauhatuksen näkökulmasta katsottuna tämä tarkoittaa, että mineraalin hienonnus täytyy suorittaa pienempään partikkelikokoon. Jauhaminen on yksikköprosessina rikastamoiden suurin energian kuluttaja ja siirryttäessä jauhamisessa pienenpään hienouteen, energian kulutus moninkertaistuu. Lisäksi perinteiset rumpumyllyt ovat osoittautuneet tehottomiksi mentäessä pienempään hienouteen kuin 50 μm. Tämän diplomityön tarkoituksena on esitellä vaihtoehto perinteiselle jauhatukselle. Työssä käydään läpi hienonnuksen perusperiaatteita, esitellään pystymyllyjen toimintaperiaate ja suoritetaan perustutkimuksia Outotecin pystymyllyllä (HIGmillTM). Testiohjelmassa tutkitaan eri parametrien vaikutusta HIG myllyn hienonnustehokkuuteen. Parametreja joita tutkitaan, ovat myllyn sekoittimen nopeus, lietteen tiheys, syöttönopeus, syötteen luokitus, jauhinkappaleiden koko sekä eri valmistajien jauhinkappaleet. Testiohjelmassa tarkastellaan myös kahden testimenetelmän eroavaisuutta. Lisäksi yksi testiohjelman keskeisemmistä tavoitteista on kehittää toistettava testimetodi pilottiajoille. Testeissä onnistuttiin rakentamaan toimiva ympäristö testien tekemiselle, myös testien toistettavuus saavutettiin. Parametrien testauksessa HIGmillTM osoittautui hyvin joustavaksi. Jos syötetty energia tonnia kohden pidettiin vakiona, jauhatustehokkuus pysyi samana huolimatta muutoksista myllyn sekoittimen nopeudessa, lietteen syöttönopeudessa tai tiheydessä. Myöskään myllyn sekoittimen kiekkojen kuluminen ei vaikuttanut jauhatustehokkuuteen. Testeissä todistettiin myös jatkuvan ja puolijatkuvan ajon vastaavuus. Lisäksi puolijatkuvassa ajossa mahdollinen näytteen heittäminen pois jauhatusvaiheiden välissä osoitettiin tarpeettomaksi

This thesis was done as an assignment and supervision of Outotec (Finland) Oy. The experimental part was carried out in the facilities of Oulu Mining School, University of Oulu. In this work two mixing mechanism setups, A and B, are compared in a pilot scale flotation cell, TankCell® 1. The aim of the thesis is to compare the gas dispersion ability of the two mixing mechanisms. The secondary goal is to define optimal operation ranges for these mixing mechanisms. The comparison is based mainly on gas dispersion parameters: gas hold-up, superficial gas velocity, bubble size and bubble surface area flux. Furthermore, power consumption and sanding of the mixing mechanisms is measured. The experiments are conducted both in two-phase system (water and air) and in three-phase system (solid, water and air). A wide range of hydrodynamic conditions were studied to cover the conditions used in actual mineral processing plants. The conditions were varied using rotor tip speeds from 4 to 7 m/s, and overall superficial gas velocities from 0.5 to 2.5 cm/s. The results of this study indicate that significant differences exist between the gas dispersion properties of the two mixing mechanisms. Mixing mechanism setup A performed substantially better at operating conditions with high air flow rates. Mixing mechanism setup B struggled to maintain good air dispersion at high air flow rates, but gave promising results at low air flow rates. The results of this study can be used as a background for future research. Furthermore, suggestions for future pilot scale testing procedures are reported
Tämä diplomityö on tehty Outotec (Finland) Oy:n toimeksiannosta ja valvonnassa. Työn kokeellinen osa on toteutettu Oulun yliopiston kaivannaisalan tiedekunnan tiloissa. Diplomityössä vertaillaan kahta sekoitusmekanismia, A ja B, pilottivaahdotuskenno TankCell®-1:ssä. Diplomityön tarkoituksena on vertailla näiden sekoitusmekanismien kykyä dispergoida ilmaa. Toissijaisena tavoitteena on määritellä sekoitusmekanismien optimaaliset toimintaolosuhteet. Sekoitusmekanismien vertailu perustuu kaasun dispersioparametreihin: kaasun tilavuusprosenttiin, ilmavuohon, kuplakokoon sekä kuplien pinta-alavuohon. Lisäksi mitataan sekoitusmekanismien tehonottoa ja hiekoittumista. Testit on suoritettu sekä kaksifaasisysteemissä (vesi ja ilma) että kolmifaasisysteemissä (kiintoaine, vesi ja ilma). Testeissä sekoitusmekanismeja tutkittiin laajasti eri toimintaolosuhteissa, joita rikastamoilla tyypillisesti käytetään. Toimintaolosuhteita muutettiin käyttämällä roottorin kehänopeuksia 4–7 m/s sekä teoreettista ilmavuota 0,5–2,5 cm/s. Diplomityön tulokset osoittavat, että sekoitusmekanismien välillä on suuria eroja niiden kyvyssä dispergoida ilmaa. Sekoitusmekanismi A:n tulokset olivat selkeästi mekanismi B:tä parempia käytettäessä suuria ilmamääriä. Sekoitusmekanismi B ei pystynyt käsittelemään yhtä suuria ilmamääriä, mutta antoi lupaavia tuloksia pienemmillä ilmamäärillä. Saatuja tuloksia voidaan käyttää jatkotutkimuksen pohjana. Pilottikokoisten vaahdotuskokeiden tekijät voivat hyötyä tässä työssä tehdyistä huomioista

The National Transportation Safety Board has cited deficiencies in judgement and decision-making as contributing factors in numerous general aviation accidents. Several studies have also indicated that some pilots exhibit hazardous attitudes in their decision-making processes. Although decision-making and judgment training is mentioned by the Federal Aviation Administration as areas that should be taught to aspiring pilots, there are relatively few current guidelines to assist flight or ground school instructors. This study centers on the decision-making characteristics of expert and novice pilots. Four expert and four novice pilots were selected by the researcher. All of the subjects were interviewed about their decision-making processes as they related to four aeronautical decision-making scenarios. Experts exhibited characteristics and themes that differed noticeably from that of the novices. One of the more pertinent differences involved what some writers have referred to as cognitive maps. These mental guides appeared to be used effectively by experts in attempting to cope with problems associated with the scenarios. Novices also appeared to make use of cognitive maps in their decision-making processes. Their maps, however, were primitive in comparison to the experts and resulted in difficulties when attempting to address specific scenarios. The findings regarding the decision-making thought processes of experts were consistent with previous studies (e.g., decisions were based on pertinent mental cues from their experiences). The findings related to novices revealed five themes that included: a. the quantity and quality of information acquired to assess risk was often deficient; b. the interpretation of the risks associated with each scenario reflected a lack of attention to pertinent issues related to the scenarios; c. decision-making was often based on recognition of familiar conditions with which novice subjects could relate; d. decision-making often reflected an emphasis on rules and procedures that novices had been taught or acquired through independent research and e. novices exhibited hazardous attitudes in their decision-making processes. The researcher reviewed significant findings and areas in need of further research. A brief conclusion and recommendations conclude the study.
Ph. D.

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A exacerbação da atividade pestosa no início dos anos 1960 e o desconhecimento de aspectos da epidemiologia levaram o Governo Brasileiro, através do Departamento Nacional de Endemias Rurais (DNERu), a convidar Marcel Baltazard, do Instituto Pasteur de Paris, para elaborar um projeto de pesquisa visando a elucidação da conservação, focalização, epizootização e epidemização da peste no Brasil, com vistas à implementação de atividades eficazes de controle. O projeto, denominado Plano Piloto de Peste em Exu, foi executado na Chapada do Araripe-PE de 1966 a 1974. Apesar de toda a sorte de óbices, dificultando o desempenho da equipe, composta basicamente por dois técnicos brasileiros, auxiliares semi-analfabetos e consultores dos Institutos Pasteur de Teerã e de Paris, foi desenvolvido um amplo programa de pesquisas elucidando a maioria das questões propostas. A compilação das atividades jamais foi publicada, mas registros isolados permitem listar os principais resultados obtidos: a) a comprovação da infecção natural de roedores silvestres e de outros pequenos mamíferos e suas pulgas; b) o papel do Bolomys lasiurus (Zygodontomys lasiurus pixuna) na epizootização; c) a capacidade vetora da Polygenis bolhsi jordani e o seu papel na transmissão da infecção ao homem, com um desempenho superior aos de Xenopsylla cheopis e Pulex irritans; d) a participação da P. irritans na epidemização; e) a sensibilidade dos sigmodontinos e equimídeos e a relativa resistência do Ratus rattus; f) a resistência dos cavídeos, decorrente da sua asparaginasemia; g) a resistência da X. cheopis e P. irritans aos inseticidas organoclorados; h) o descarte das pestes endógena e crônica como mecanismos responsáveis pela conservação; i) a redução dos prazos para confirmação diagnóstica; j) o isolamento de 719 cepas, que deram origem à maior coleção brasileira de culturas de Yersinia pestis; k) a definição de um programa de controle baseado na vigilância contínua e sistemática, privilegiando a participação comunitária e contemplando a pesquisa da Y. pestis nos roedores e suas pulgas e pesquisa de anticorpos contra o antígeno F1 em animais-sentinela, o que ensejou a estruturação de uma rede nacional de laboratórios, bem como a intervenção imediata nas ocorrências, com diagnóstico precoce, pronto tratamento, quimioprofilaxia e despulização

La mécanique quantique a modifié notre façon d'interpréter ce que jadis l'on appelait communément "réalité physique". A titre d'exemple, selon l'interprétation standard de la mécanique quantique (dite interprétation probabiliste de Copenhague) les propriétés d’un objet quantique n'ont pas de réalité physique, du moins, pas avant que l’observateur ne les mesure. De plus, tout semble se passer comme s'il y avait un indéterminisme intrinsèque à la dynamique quantique qui ne permettrait pas de prédire avec certitude le résultat d'une mesure. Dès lors, plusieurs interprétations physiques et philosophiques ont vu naissance afin de décrire (notre connaissance de) cette réalité.C'est au cours de la conférence de Solvay en 1927 que Louis de Broglie, un opposant à l'interprétation probabiliste, proposa une solution alternative qui permettait d'une part de restaurer le déterminisme (ainsi que le réalisme) et d'autre part de remettre au premier plan la notion de trajectoire. Par la suite cette théorie fut redécouverte et complétée par David Bohm pour donner naissance à la théorie connue aujourd'hui sous l'appellation de théorie de l'onde pilote. John Bell a dit à propos de cette interprétation : " En 1952, l'impossible a été rendu possible. C'était dans l'article de David Bohm. Bohm a montré explicitement comment une description indéterministe pouvait être transformée en théorie déterministe."Les travaux présentés dans ce manuscrit de thèse s'inscrivent dans la continuité de la vision de de Broglie et consistent en deux parties, chacune d'elles ayant pour but de répondre à une problématique particulière. Dans la première, on considère deux formalismes du type onde pilote, une version déterministe (dynamique de de Broglie-Bohm chapitre 2) ainsi qu'une de ses extensions stochastiques (dynamique de Bohm-Hiley-Nelson chapitre 3). On s'attardera notamment sur l’émergence de la probabilité quantique à partir de ces dynamiques dans l’approche dite du "Quantum Non-Equilibrium". Cette approche permet entre autres de s'affranchir du statut axiomatique de la distribution de probabilité mais aussi de la justifier par des arguments similaires à ceux que l'on retrouve en mécanique statistique. Parmi ces arguments on retrouvera à titre d’exemple la notion d’ergodicité, de chaos, de mixing ainsi que d’autres propriétés qui feront l’objet d’une étude approfondie (chapitre 4). En particulier, l’émergence de l’équilibre s'accompagne d'un processus de relaxation que nous allons caractériser dans chacune de ces dynamiques (dans le chapitre 3 nous dériverons un théorème H qui décrit quantitativement ce processus dans le cas stochastique). Par ailleurs, nous nous efforcerons, dans une approche phénoménologique, d’appliquer ces théories quantiques d'onde pilote à la dynamique macroscopique des gouttes d'huile rebondissantes dans un bain (chapitre 5).La deuxième problématique quant à elle, repose sur une hypothétique généralisation non-linéaire de la mécanique quantique. En particulier, nous considérerons l'équation de Schrodinger Newton comme une première proposition a cette généralisation. Cette équation non-linéaire découle d’une approximation semi-classique de la gravité et a été entre autres proposée par Roger Penrose pour expliquer le collapse de la fonction d’onde. Nous montrerons dans un premier temps comment le programme de la double solution de Louis de Broglie se développe dans ce contexte (chapitre 6). Par la suite nous verrons comment tester cette généralisation non-linéaire par deux propositions expérimentales (chapitre 7). En particulier, l’une de ces propositions nous conduira à étudier des effets de décohérence lors du refroidissement laser (Doppler cooling, chapitre 8). Pour cela on utilisera le modèle de Ghirardi–Rimini–Weber (GRW) comme modèle de décohérence. Ce qui nous permettra par la suite de généraliser les résultats obtenus auparavant par GRW dans leur modèle
The quantum theory has modified the way we interpret what in the past was commonly called "physical reality". As an example, according to the standard interpretation of quantum mechanics (the so-called probabilistic interpretation of Copenhagen), the properties of a quantum object have no physical reality, at least not before the observer measures them. Moreover, everything seems to happen as if there was an intrinsic indeterminism in the quantum dynamics that forbids to predict with certainty the result of a measurement. From then, several physical and philosophical interpretations were born to describe (our knowledge of) this reality.It is in 1927, during the Solvay conference, that Louis de Broglie, an opponent of the probabilistic interpretation, proposed an alternative solution to that problem. He proposed on the one hand to restore determinism (as well as realism) and on the other hand to bring back the notion of trajectory to the foreground. Subsequently this theory was rediscovered and supplemented by David Bohm to give birth to the theory known today as pilot wave theory. John Bell said about this interpretation: " In 1952, I saw the impossible done. It was in papers by David Bohm. Bohm showed explicitly how .... the indeterministic description could be transformed into a deterministic one."The works carried out in this manuscript are in continuity with de Broglie’s view and can be summed up in two main parts, each of them having the aim of answering a particular problem. In the first part, we consider two versions of the pilot wave theory: a deterministic version (de Broglie-Bohm dynamics in chapter 2) as well as one of its stochastic extensions (Bohm-Hiley-Nelson dynamics in chapter 3). In the framework of what is called the "Quantum non-equilibrium" approach we shall see how the quantum probability emerges from those dynamics. This approach makes it possible to get rid of the axiomatic status of the probability distribution but also to justify it by arguments similar to those found in statistical mechanics. Among these arguments we shall for instance find ergodicity, chaos, mixing and other properties that will be studied in depth (chapter 4). In particular, the emergence of the quantum probability is accompanied by a relaxation process that will be characterized for both dynamics (in chapter 3 we derive a strong H-theorem for the stochastic dynamics which quantitatively describes how this process occurs). In addition, we will try in a phenomenological approach to apply these quantum pilot wave theories to the macroscopic dynamics of bouncing oil droplets (chapter 5).The second problem is linked to a hypothetical nonlinear generalization of the quantum theory. In particular, we considered the Schrodinger Newton equation as a first proposal to this generalization. In a nutshell, this non-linear equation derives from a semi-classical approximation of gravity and has been proposed by Roger Penrose among others to explain the collapse of the wave function. We shall first show how it is related to the double solution program of Louis de Broglie (chapter 6). Subsequently we will see how to test this nonlinear generalization by considering two experimental proposals (chapter 7). In particular, one of these proposals will lead us to study the interplay between decoherence and Doppler cooling (chapter 8). To do this we shall use the model of Ghirardi-Rimini and Weber (GRW) as a decoherence model, which will allow us to generalize their original results

Conjugate flow and heat transfer has been investigated in an unbaffled pilot-scale stirred tank reactor with a plain jacket. The vessel volume was 25 litres with a nominal capacity of 20 litres. Experiments and three-dimensional CFD simulations have been conducted on this vessel. The experiments involved heating, boiling, and cooling of methanol as well as water. The heat transfer medium in the jacket was an oil mixture called ‘DW-Therm’. The CFD simulations of some aspects of these experiments have been broken down into jacket-only and process-only simulations, followed by a fully conjugate simulation. The link between flow patterns, pressure drop and heat transfer in conventional jackets of stirred tank reactors has been analysed. The experiments and CFD simulations have been performed using a range of DW-Therm inlet temperatures. The CFD results were compared with experimental data of temperature measurements and with the use of engineering correlations found in the literature to predict heat transfer coefficients from the experimental data. The simulations produced values of total heat transferred by the jacket within 10% of the experimental results. The simulations of boiling inside the vessel approximated a constant process temperature which was used to investigate the jacket-only phenomena. The process-only and the conjugate simulations simulated heating of water inside the vessel. Mathematical analysis as well as and industrially and academically used correlations from the literature were used to estimate heat transfer coefficients for boiling and external heat loss. These correlations for overall heat transfer coefficients overlook maldistribution of heat transfer coefficients in jackets that use a liquid heat transfer medium. This is industrially important because it provides new information to consider when maintaining highly temperature-dependent processes, in which adequate heat transfer to or from the process is required. This could be for a variety of reasons, from maintenance of product quality to preventing runaway reactions.

The standardization of operational procedures in chemical plants through the use of automation have became a mandatory practice for the current companies that tries or have tried a place in the commodities competitive stock. Real gains in productivity and recovery are closely related to controller s performance used in chemical process of this companies. There are a several controllers strategies in which the predictive control is a powerful tool that shows attractive results. The use of predictive control is achieved by the implementation of the control strategy in a pilot plant of a MIMO (Multiple-Input Multiple-Output) non-linear process. The nonlinear process is a experimental system of a neutralization reactor with three input flows and one output flow, and the manipulated variable are the level of reactor and the pH of mixture. The input flows are one of acid, one of base and one of buffer solution and this are the controlled variables. The information used to controller project was obtained in a open loop procedure. In this procedure, it was made disturbances in input variable and watched the output variable behavior. The MPC ( Model Predictive Control) performance was tested in a simulation and after in the pilot plant. The results achieved in simulation and practice implementation shows the excellent performance of controller to the process.
A padronização dos procedimentos operacionais nas plantas químicas através do emprego de automação vem tornando-se uma prática obrigatória para as atuais empresas que ocupam ou tentam ocupar um lugar de destaque no competitivo mercado de commodities. Ganhos reais de produtividade e recuperação estão intimamente associados ao desempenho dos controladores utilizados nos processos químicos destas empresas. Dentre as diversas estratégias de controle existentes, o controle preditivo corresponde a uma poderosa ferramenta que apresenta resultados bastante atrativos. Este trabalho investiga a aplicação prática de controle preditivo em uma planta piloto representativa de processos não-lineares MIMO (Multiple-Input Multiple-Output). O processo não-linear é um sistema experimental composto por um reator de neutralização com três correntes de entrada e uma de saída, sendo que as variáveis manipuladas correspondem ao nível do tanque e ao pH da mistura. As correntes de entrada são uma de ácido, uma de base e uma de solução tampão e correspondem às variáveis controladas. Informações necessárias para o projeto do controlador foram coletadas através do procedimento de operação em malha aberta, no qual provocou-se pertubações nas variáveis de entrada e observou-se o comportamento das variáveis de saída. O desempenho do controlador MPC (Model Predictive Control) proposto foi inicialmente avaliado em simulação e posteriormente na planta piloto. Os resultados obtidos na simulação e na implementação prática comprovam o excelente desempenho do controlador para o processo em estudo.
Mestre em Engenharia Química

With increasing water reuse applications and upcoming stringent regulations for treated wastewater effluent discharge, wastewater plants need to consider alternative technologies beyond conventional treatment processes. The new regulations, Numeric Nutrient Criteria (NNC), may regulate discharge nitrogen and phosphorus concentrations to as low as 0.5 mg/L as N and 10 μg/L as P respectively. To meet these target requirements, system retrofitting to incorporate chemical or advanced nutrient removal systems possibly with membrane technology will most likely be required. Although microfiltration/ultrafiltration membranes coupled with biological processes, otherwise known as membrane bioreactors (MBR), remove contaminants and suspended solids, nutrient removal is minimal to none. This emphasizes the importance of the biological process in MBRs. This study evaluated and tested the improvement of biological nutrient removal (BNR) in an MBR system which can meet NNC regulations along with the optimization of membrane operation for the reduction of fouling and energy consumption. A pilot study was conducted at the City of Tampa wastewater treatment plant and was divided into four phases of experimentation using two submerged MBR membranes operated with modified biological configurations. Laboratory analyses and data collection were conducted during the experiments and the performance evaluated for each configuration. System configurations were also optimized throughout each phase of testing for nutrient removal. Important factors used in the development of an appropriate configuration included isolation of the membrane tank from the biological reactors in the design, control of the dissolved oxygen (DO) concentrations or specifically the oxidation reduction potential (ORP) during operation and appropriate internal recirculation rates between the reactors. The results of this study provided information relevant for the assessment of both the BNR process and membrane performance. Membrane performance data indicated the importance and effect of air scouring (despite energy consumption) on membrane fouling for long-term stable flux operation as well as the cleaning frequency whether chemical enhanced backwash (CEB) or clean-in-place (CIP). This assessment also discussed how BNR systems can be enhanced through the incorporation of important design factors to eliminate the inhibiting factors of nitrogen and phosphorus removal such as dissolved oxygen. One of the biological processes tested in this study achieved effluent nitrogen and phosphorus concentrations below 5 mg/L and 1 mg/L respectively. Although the process tested did not meet NNC criteria, it can be applied with chemical precipitation. This, in turn, can reduce the operating and maintenance (O&M) costs associated with the chemical precipitation of phosphorus.

An investigation was done into the recovery of invert sugar from sugar cane molasses. A pilot plant was designed and constructed to evaluate the clarification and separation of molasses to produce invert sugar syrup. The aim of the pilot plant was to prove the process and deliver data so as to facilitate the design and prove the financial viability of a commercial plant. The pilot plant had to process 300 kg/day of molasses. The clarification of molasses by centrifugal separation, a known desludging process, did not produce a product of acceptable quality which could be used in a chromatographic separator. The results were disappointing. The product obtained was also not suitable for dead end pressure filtration. The turbidity remaining after the centrifugal separation also did not respond to a second flocculation process. Conventional settling clarification was investigated. Seven factors that could influence the consolidation and settling of suspended solids in molasses were identified, namely: the age of the diluted molasses, the temperature of the flocculated mixture, the variations across various batches of flocculant, the effect of reaction time of the phosphoric acid, the optimum flocculant dosing concentration, the optimum concentration of the molasses solution and the effect of increasing the acid dosage. The optimum conditions to clarify molasses through settling were found to be: fresh molasses, at 28 Brix and 60°C, allowing 10 min intervals between acidification with 3,75 g (as 100%) phosphoric acid/ kg dry material (assumed equal to Brix) and neutralisation with 5 g (as 100%) caustic/kg dry material (assumed equal to Brix), flocculation with any batch of flocculant 6195, dosed as a 1000 ppm solution. Commercial equipment was evaluated. The pilot plant E-cat clarifier was operated at 300 l/h and a thick sludge formed. The overflow was clear and it could be filtered. The molasses obtained was suitable for chromatographic separation. The recovery of sugars from molasses sludge has economic merit. From the evaluation of centrifugal separation and gravity separation it is clear that gravity separation again is the best method. The sweet-water obtained is consistent within the clarity requirement of 10 NTU/Brix and can be used to dilute raw molasses in the upstream processing step. The clarification process that was developed is patented. [Bekker, Stolz et.al. (2001)] A sugar recovery of 93.9 mass % at a purity of 99.7 mass % from molasses, was achieved using a simulated moving bed, ion exclusion, pilot plant. The operating conditions for this performance were: feed flow at 14 l/h and at a temperature above 60 °C; water flow at 63 l/h and at a temperature above 65 °C; extract flow at 21 l/h; raffinate flow at 56 l/h; loop flow at 78 l/h and step time at 1326 seconds. This relates to the following bed volumes of the various separation zones: Bed Volume Zone 1 = 0.694; Bed Volume Zone 2 = 0.591; Bed Volume Zone 3 = 0.661; Bed Volume Zone 4 = 0.383. There is a trade-off between purity and recovery and a reduction in water usage. A preliminary environmental impact assessment and conceptual mass balance were done. The proposed plant integrates well into the existing Komati Mill of TSB and does not pose any significant environmental threat. The plant requires certain services from the mill. The mass balance investigated the water and steam consumption of the plant. Process integration was done so as to obtain the optimum utility consumption. The utility consumption of the plant does not exceed the capacity available at the mill. A small boiler is however required to produce steam during the annual mill maintenance period. Various techniques were used in a cost estimation for the invert sugar plant. The internal rate of return (IRR) is 42% for a fixed capital investment of R94,270,000.00. The net return rate (NRR) for the project is 4%/year, the net present value (NPV) - discounted at a 30% cost-of-capital is R41,782,000.00. The net payout time (NPT) is 5.207 years. The project fulfils the financial requirements set by TSB. It is now possible and viable to desugarize cane molasses.

I takt med att städerna växer ökar belastningen på de kommunala avloppsreningsverken. Käppalaförbundet förutspår att antalet anslutna personekvivalenter till Käppalaverket kommer att öka med över 160 % under de kommande tre decennierna. En ökad belastning leder till en större mängd slam som måste behandlas. Detta görs idag med stabilisering genom mesofil rötning samt efterföljande avvattning och hygienisering. Samtidigt finns ett behov av hållbara energikällor i samhället, dit avloppsreningsverken bidrar genom tillhandahålla energirik biogas som biprodukt från rötningen.  Utrötningsgraden är beroende av slammets uppehållstid i rötkammaren och uppehållstiden kommer att bli kortare i takt med att belastningen ökar. Termofil rötning har identifierats som ett möjligt alternativ till inköp av ytterligare rötkammarvolym då metoden har rapporterats ge en snabbare stabilisering och därmed ett likvärdig resultat med kortare uppehållstid. Dessutom finns indikationer för att termofil rötning kan producera en större mängd biogas per enhet organiskt material i jämförelse med mesofil rötning. För att utreda huruvida Käppalaförbundet kan åtnjuta dessa fördelar har ett termofilt rötningsförsök bedrivits i pilotskala.  Pilotanläggningen bestod av en 5 m³ rötkammare som matades semikontinuerligt med 65 mass% primärslam och 35 mass% överskottsslam. Försöket inleddes med en temperaturövergång från en mesofil ymp till termofila betingelser, följt av att processen tilläts acklimatisera. Processen drevs därefter under tre uppehållstider med en längd på 18 dygn vardera. Samtliga driftparametrar härleddes i den mån det var möjligt från fullskalig slambehandling på Käppalaverket. De experimentella resultaten jämfördes med simuleringsresultat baserade på den matematiska modellen Anaerobic Digestion Model No. 1. Temperaturövergången och acklimatiseringen utfördes med framgång. Vid referensbelastningen var utrötningsgraden 54.4 % och den specifika metanproduktionen var 0.221 Nm3 CH4/kgVS, vilket var otillräckligt för att överträffa den mesofila, fullskaliga processen. Försöket indikerade att proteiner bryts ned lättare i en termofil process. Vidare observerades avtagande processtabilitet och försämrade avvattningsegenskaper hos rötresten.
As cities grow, the load on the municipal wastewater treatment plants increases. The Käppala Association predicts that the number of population equivalents connected to the Käppala Wastewater Treatment Plant will increase by over 160 % in the coming three decades. An increased load leads to a larger amount of sludge that must be treated. This is done today with stabilization through mesophilic anaerobic digestion and subsequent dewatering and hygienization. At the same time, there is a need for sustainable energy sources in society, to which wastewater treatment plants contribute by providing energy-rich biogas as a by-product from the anaerobic digestion. The degree of digestion is dependent on the retention time of the sludge in the digester and the retention time will become shorter as the load increases. Thermophilic anaerobic digestion has been identified as a possible alternative to the investment of additional digester volume as the method has been reported to provide a faster stabilization and thus an equivalent result with a shorter retention time. In addition, there are indications that thermophilic anaerobic digestion is able to produce a larger amount of biogas per unit of organic material in comparison with mesophilic anaerobic digestion. To evaluate whether the Käppala Association can enjoy these benefits, a thermophilic anaerobic digestion experiment has been conducted on a pilot scale. The pilot plant included a 5 m³ digester which was fed semi-continuously with 65 mass% primary sludge and 35 mass% waste activated sludge. The experiment began with a temperature transition from a mesophilic inoculum to thermophilic conditions, followed by allowing the process to acclimatize. The process was operated thereafter for three retention times with a length of 18 days each. All process parameters were derived as far as possible from the full-scale sludge treatment at Käppala Wastewater Treatment Plant. The experimental results were compared with simulation results based on the mathematical model Anaerobic Digestion Model No. 1. The temperature transition and acclimatization was performed successfully. At reference load, the degree of digestion was 54.4 % and specific methane production was 0.221 Nm3 CH4/kgVS, which was not enough to overcome the mesophilic full-scale process. Indications pointed towards proteins being more easily digested in a thermophilic process. Furthermore, deteriorating process stability and dewaterability of the digestate was observed.

This work is done in cooperation with the Halmstad local police. We examine how seizedphones are handled throughout the organisation. We investigate where and if there canoccur issues with the physical device handling and we also look at how the extractions madeon seized phones are analysed and the possible problems with that work.We have interviewed several employees, both sworn and unsworn staff, we have looked atprovided statistics and done thorough background research in this field. The comparison andanalysis of the material show that the evidence integrity and the chain of custody standcomparably firm. We do on the other hand see issues with the knowledge level in the ITforensic field, the wish for more training, the lack of knowledge sharing between groups andthe risk for missing crucial evidence due to these issues. We also look at some possibleways of meeting the risks mentioned by investigating the newly employed IT caseadministrators and how that has turned out. At the local police stations, these persons solveissues that needed addressing but were previously neglected due to lack of knowledgeablestaff. The suggestions on adding these types of employees address some of the issues withextraction analysis. The paper also proposes some possible solutions to some of theproblems mentioned.

This paper is about improving the efficiency of nitrogen and other organic nutrient removal from activated sewage treatment by adopting an innovative technology. The work is to study the changes in nitrogen removal in pilot-scale experiments with the ITEST unit. The report also describes the various sources contributing to the eutrophication of the sea and water, caused by an increase in nutrient levels in different water bodies. Ineffective treatment of sewage contributes to the eutrophication. In the Baltic regions the temperature will be zero (0) or less than zero degree-centigrade during winter season. It results in decreased or fall in temperatures of incoming water to wastewater treatment plants. The temperature is an important parameter for sewage/wastewater treatment processes. Bacteriological nitrification and denitrification is an effective process for removing nitrogen from wastewater. From various research works and articles, it can be found that 23 + / - 2 °C, is the optimum temperature for nitrification and denitrification processes. So, the main aim is to study the effect of maintaining the incoming wastewater temperature by use of heat exchangers on incoming water to an activated sludge process line in pilot plant scale. In the pilot plant there were two testing lines; one line with heating system and the second line without heating system. A temperature of 19 to 20 °C was maintained in the influent to testing line. The nitrogen removal rates were compared between the two lines during the test period of approximately more than 8 months. Other biological activities in the treatment process were also compared between the two lines.

This thesis studies how the changes to the flotation process caused by adjusting pH and the dosage of the flotation reagents affect the electrical conductivity of the froth flotation froth in different parts of the froth. The measurements in the experimental part were done in Oulu Mining School’s continuous minipilot beneficiation plant at the University of Oulu in March and May of 2015. The conductivity of the froth was measured with Outotec’s ERT (Electrical Resistance Tomography) based test probe. The probe was placed inside the 4-litre flotation cell that acted as a rougher in copper refining circuit. Froth’s bubble size, colour, stability and speed were measured with Outotec’s FrothSenseTM -camera. Elemental composition of the process streams was measured with a method based on x-ray fluorescence. The effect of three chemical reagents used in froth flotation, and also the effect of pH, was studied: dosage of Dowfroth (Test 1), xanthate (Test 2), zinc sulphate (Test 3) and pH (Test 4). Each test consists of three step tests, where the value of variable in question was changed while other values were kept at their base levels. Each test was performed twice. Assumption was that the adjusting of mentioned variables affects the other process variables, such as bubble size, froth thickness, elemental compositions etc., which in turn affects the electrical conductivity of the froth. Froth was divided vertically into layers so that the possible differences in different parts of the froth could be observed. Theoretical part of this thesis presents an overview of beneficiation process chain, starting from grinding and ending in dewatering processes. The chemical reagents used in flotation and some basic methods for measuring different parameters are also introduced. The results from the experimental part showed that the changing dosage of chemical regents and pH causes changes in process which also affected the electrical conductivity of the froth. Especially bubble size and froth thickness had clearly an effect on the conductivity. Furthermore, the conductivity values and changes to them were different in different layers of the froth, when the froth was thick. In a thin froth, the differences in the conductivity values and changes in them between the froth layers were much smaller
Tässä diplomityössä tutkittiin miten pH:n ja vaahdotusrikastuksessa käytettävien kemikaalien annostuksien säätämisen prosessiin aiheuttamat muutokset vaikuttavat vaahtopatjan eri osien sähkönjohtavuuteen vaahdotusrikastus prosessissa. Kokeellisessa osiossa mittaukset tehtiin Oulu Mining School:in jatkuvatoimisella minipilot -rikastamolla Oulun Yliopistolla maalis- ja toukokuussa 2015. Vaahdon sähkönjohtavuutta mitattiin Outotecin ERT:n (Electrical Resistance Tomography) perustuvalla testisauvalla. Sauva oli asennettu tilavuudeltaan nelilitraiseen vaahdotuskennoon, joka toimi kuparin rikastuspiirissä esivaahdotuskennona. Vaahdon kuplakokoa, väriä, stabiilisuutta ja nopeutta mitattiin Outotecin FrothSenseTM -kameralla. Prosessivirtojen kemialliset koostumukset mitattiin röntgenfluoresenssiin perustuvalla menetelmällä. Työssä selvitettiin kolmen eri vaahdotuksessa käytettävän kemikaalin ja pH:n vaikutusta vaahtopatjan sähkönjohtavuuteen: Dowfrothin (Testi 1), ksantaatin (Testi 2) ja sinkkisulfaatin (Testi 3) annostuksien sekä pH:n (Testi 4) vaikutus. Jokainen testi koostui kolmesta askelkokeesta, jossa mainitun muuttujan arvoa muutettiin muiden muuttujien arvojen pysyessä vakioina. Jokainen testi toistettiin kahdesti. Ennakko-oletus oli, että muutokset pH:hon ja reagenssien annostuksiin aiheuttavat muutoksia prosessinparametreihin kuten kuplakokoon, vaahdon paksuuteen, kemiallisiin koostumuksiin jne., jotka puolestaan vaikuttavat vaahdon sähkönjohtavuuteen. Vaahto jaettiin korkeussuunnassa kerroksiin, jotta mahdollisia eroja sähkönjohtavuuksien arvoissa ja niiden muutoksissa eri vaahdon osien välillä pystyttiin tarkastelemaan. Työn teoriaosuudessa esitellään mineraalien rikastuksen prosessiketju, alkaen jauhatuksesta ja päättyen vedenpoistoprosesseihin. Työssä käydään läpi myös vaahdotusrikastuksessa käytettäviä kemikaaleja sekä eri parametrien mittauksessa käytettäviä mittausmenetelmiä. Kokeellisesta osiosta saadut tulokset osoittavat, että pH:lla sekä vaahdotuksessa käytettävien kemikaalien annostuksien muutoksilla on vaikutusta vaahtopatjan sähkönjohtavuuteen. Erityisesti kuplakoolla ja vaahdon paksuudella oli selkeästi vaikutusta vaahdon sähkönjohtavuuteen. Lisäksi huomattiin, että paksussa vaahdossa sähkönjohtavuuden arvot ja niiden muutokset olivat erilaisia vaahdon eri kerroksissa. Ohuessa vaahdossa erot sähkönjohtavuuksien arvoissa ja muutoksissa vaahtokerrosten välillä olivat huomattavasti pienempiä

Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Carbon dioxide (CO2) is seen as one of the main contributors to global warming. The use of fossil fuels for power production leads to large quantities of carbon dioxide being released into the atmosphere. The released CO2 can, however, be captured by retrofitting capture units downstream from the power plant called Post Combustion Carbon Dioxide Capturing. Post combustion CO2 capture can involve the reactive absorption of CO2 from the power plant flue gas steam. Reactive solvents, such as monoethanolamine (MEA), are used for capturing the CO2 and the solvent is regenerated in a desorber unit where the addition of heat drives the reverse reaction, releasing the captured CO2. However, the large energy requirement for solvent regeneration reduces the viability of employing CO2 capture on an industrial scale. This study focused on establishing a facility for CO2 capture studies – the main aim being the construction and validation of the results produced by the pilot plant facility. A secondary aim of this study was developing an Aspen Plus® Simulation method that would simplify simulating the complex CO2 capture process. Results from the simulation were to be compared to that of the pilot plant experiments. A pilot plant facility with a closed gas system, allowing gas recycling from both the absorber and the stripping columns, was set up. The absorber column (internal diameter = 0.2 m) was set up to allow one to obtain information regarding gas- and liquid temperatures and compositions at various column heights. Online gas analysers are used for analysing the gas composition at various locations in the absorber column. The pilot plant was initially commissioned with 20 weight % MEA in aqueous solution; however the main validation experiments were conducted with 30 weight % MEA in aqueous solution. 30 weight % MEA (aq) is generally used as the reference solvent for pilot plant studies. Pilot plant results with regards to the carbon dioxide concentration profiles for the absorber column as well as the regeneration energy requirement and capture rates compared well to literature data. The Aspen Plus® simulation was also set up and validated using published pilot plant data. The comparison of the pilot plant results from this study, to the results from the Aspen Plus® Simulation, showed good agreement between the two. The Aspen Plus® Simulation could further be used to validate pilot plant data that has been gathered outside the range of reported CO2 capture efficiencies. The Aspen Plus®model was evaluated at liquid-to-gas ratios of 1.7 and regeneration energies matching the pilot plant results. It was found that the model under predicts the capture efficiency of CO2 with an average of 4.0%. The model was corrected for this error at liquid-to-gas ratios of 2 and the fit of the model to pilot plant results improved considerably (R2-value = 0.965). Pilot plant repeatability was investigated with both 20 weight %- and 30 weight % MEA in aqueous solution. Temperature- and gas concentration profiles from the absorber column showed good repeatability. The maximum deviation of the regeneration energy and the capture efficiency from the calculation means were ±0.72% and ±1.40% respectively. The aims of this study have been met by establishing, and validating the results of a pilot plant facility for carbon dioxide capture studies. It has been shown that the pilot plant produces repeatable results. Results from the Aspen Plus® Simulation were validated and also match results from the established pilot plant setup. The simulation may prove to provide valuable information regarding the optimal operating conditions for the pilot plant and may aid in performing a full parametric study on the CO2 capture process.
AFRIKAANSE OPSOMMING: Koolstofdioksied (CO2) word geklassifiseer as een van die bekendste kweekhuisgasse wat ʼn groot bydra lewer tot aardverwarming. Die gebruik van fossielbrandstowwe om na die energiebehoeftes van die mens om te sien lei daartoe dat groot hoeveelhede koolstofdioksied, hoofsaaklik vanaf kragstasies, vrygestel word in die atmosfeer. Daar is verskeie maniere hoe die CO2 uit die uitlaatgas van kragstasies verwyder kan word – die vernaamste hiervan is bekend as die Na-verbranding opvangs metode. Die opvangs van CO2 na verbranding van fossielbrandstowwe vir kragproduksie kan vermag word deur van reaktiewe absorpsie tegnieke gebruik te maak. Mono-etanol-amien (MEA) kan vir hierdie doeleindes aangewend word deur dit, in ʼn absorpsiekolom, in kontak te bring met die CO2. Die gereageerde oplosmiddel word geregenereer deur die oplosmiddel te verhit in ʼn stropingskolom. ʼn Bykans suiwer CO2 stroom word vrygestel. Die implementering van hierdie opvangtegniek op industriële skaal lei egter tot groot energieverliese vir die kragstasies. Die hoofrede hiervoor is die hoeveelheid energie wat benodig word om die oplosmiddel te regenereer vir hergebruik. Die hoofdoel van hierdie studie was gemik op die oprigting en inwerkstelling van 'n navorsingsfasiliteit vir studies aangaande die na-verbranding opvangs van CO2. Dit het behels die ontwerp, konstruksie en stawing van gelewerde resultate met resultate in die literatuur. 'n Sekondêre doel van hierdie studie was die metode-ontwikkeling vir die opstel van 'n Aspen Plus® Model wat die simulasie van die CO2 opvangsproses met ʼn reaktiewe oplosmiddel, MEA, vereenvoudig. Gesimuleerde resultate is vergelyk met resultate uit die literatuur. Die toetsaanleg, met 'n geslote gas stelsel, maak voorsiening vir die hersirkulering van gas wat vir eksperimentele doeleindes gebruik word. Die absorpsie kolom (interne diameter van 0,2 m) is opgestel sodat informasie aangaande die gas- en vloeistof temperature, sowel as gas- en vloeistof komposisies vanaf verskillende kolomhoogtes, bekom kan word. ʼn Aanlyn CO2 analiseerder word gebruik om vir CO2 in die prosesgas te analiseer. Die toetsaanleg is aanvanklik in bedryf gestel met ʼn 20 massa % MEA in waterige oplossing; die hoof eksperimente is egter uitgevoer deur van 30 massa % MEA in waterige oplossing gebruik te maak. Die laasgenoemde oplosmiddel word algemeen gebruik in die CO2 opvangs verwante navorsingsveld. Die resultate van die toetsaanleg, vergelyk goed met resultate in die literatuur. Die gesimuleerde Aspen Plus® resultate is ook vergelyk met resultate in die literatuur en die gevolgtrekking is gemaak dat die simulasie gebruik kan word om redelike akkurate voorspellings van die werklike prosesresultate te gee. Die simulasie is verder ook gebruik om resultate, verkry vanaf die opgerigte toetsaanleg, te verifieer en ʼn goeie ooreenstemming tussen die gesimuleerde en die eksperimentele resultate is waargeneem. ʼn Verder gevolgtrekking aangaan die Aspen Plus® simulasie metode was dat dit in die toekoms ʼn groot doel kan dien in die optimeringsproses van toetsaanlegte waar navorsing aangaande die na-verbranding opvang van CO2 gedoen word. Die Aspen Plus® model is geëvalueer by ‘n vloeistof-tot-gas-verhouding van 1,7 en ooreenstemmende toetsaanleg resultate, aangaande die hoeveelheid energie wat ingesit is vir die regenerasie van die oplosmiddel. Die onakkuraathede in die model, met betrekking tot die voorspelling van die hoeveelheid CO2 wat vasgevang sal word, is hierdeur bepaal en die model is daarvoor aangepas. Resultate van die verbeterde model vergelyk baie goed met die toetsaanleg resultate – ʼn R2-waarde van 0.965. Die herhaalbaarheid van die toetsaanleg resultate is ondersoek en ʼn goeie herhaalbaarheid van die temperatuur- en CO2 konsentrasieprofiele is verkry. Die toetsaanleg dui ook goeie herhaalbaarheid met betrekking tot die effektiwiteit waarmee die CO2 uit ʼn gasstroom verwyder word (± 1,40%), sowel as die hoeveelheid energie wat benodig word vir regenerering van die oplosmiddel (± 0,72%). Die doelwitte van hierdie studie is bereik deur die oprigting en verifiëring van resultate gelewer deur 'n toetsaanleg vir studies aangaande die na-verbrandingsopvang van CO2. Die herhaalbaarheid van toetaanleg resultate is bewys. Resultate van die Aspen Plus® simulasie stem ooreen met resultate in die literatuur sowel as resultate van die toetsaanleg wat opgerig is in hierdie studie.

Att begränsa globala uppvärmningen till 1,5°C kommer kräva negativa koldioxidutsläpp. En metod för att generera negativa koldioxidutsläpp är så kallad Bio-Energy Carbon Capture and Storage (BECCS). En direkt implementering av BECCS är att fånga in CO2 från rökgas som genereras vid förbränning av biomassa i en så kallad post-combustion capture-konfigurering. Post-combustion BECCS har skapat en stor resonans hos kraftverksoperatörer och pappersproducenter. Stockholm Exergi, som ägs av Fortum och Stockholms Stad, siktar på att fånga in upp till 800 kt CO2 per år från deras biomass-eldade CHP-anläggning i Värtaverket vid 2024. Planen är att fånga in CO2 från rökgasen genom en absorptionsprocess och sedan skeppa det till Norge för geologisk förvaring. Mastersexamensarbetet följde en experimentskampanj driven av Stockholm Exergi som siktade på att uppnå experimentell validering av en absorptionsprocess för koldioxidinfångning från rökgas vid förbränning av biomassa. En testenhet konstruerades och tester genomfördes från december 2019 till maj 2020. Examensarbetet fokuserade på rollen absorptionsmedlet hade på infångningshastigheten. Tester med tre olika lösningsmedel genomfördes och de experimentella resultaten analyserades genom en kombination av jämviktsmodeller och Murphree-effektiviteter. Resultatet visar att ett absorptionsmedel baserat på vattenlöslig K2CO3 är kompatibel med rökgas från förbränning av biomassa, eftersom infångningshastigheter mellan 5 och 13 % uppmättes. De undersökta hastighetspromotorerna (3 vikt% H3BO3 + 1 vikt% V2O5) visade dock inte den förväntade effekten på infångningshastigheter, och på grund av tidsbegränsningar testades inte olika vikt% av promotorn under det här examensarbetet. Ingen tydlig slutsats drogs därför med hänsyn till promotorer. Baserat på Murphree-effektiviteterna som beräknats genom experimenten med konstant förhållande mellan vätske- och gasflöde uppskattas en 28–35 m hög kolonn fånga 90% av CO2 i rökgasen.
Limiting global warming to 1.5°C will require negative carbon emissions. One way for generating negative carbon emissions is through bio-energy carbon capture and storage (BECCS). A direct implementation of BECCS is to capture CO2 from the flue gas originating from the combustion of biomass in a post-combustion capture configuration. Post-combustion BECCS has generated considerable resonance among power plant operators and paper manufactures. Stockholm Exergi, owned by Fortum and Stockholm Stad, aims at capturing up to 800 kt CO2 per year from their biomass-fired CHP plant in Värtaverket by 2024. The plan foresees to capture CO2 from the flue gas utilizing an absorption process and shipment of the captured CO2 to Norway for geological storage. The Master thesis project followed an experimental campaign run by Stockholm Exergi that aimed at experimental validation of an absorption process for carbon capture from flue gas originating from the combustion of biomass. A test unit was constructed, and test trials were run from Dec. 2019 to May 2020. The thesis focused on the role of the absorption solvent on the capture rate. Test trails with three different solvents were conducted, and the experimental results were analyzed using equilibrium models combined with Murphree efficiencies. The results show that an absorption solvent based on aqueous K2CO3 is compatible with the flue gas derived from biomass combustion, i.e., capture rates ranging from 5 to 13 % were measured. However, the investigated rate promoters (3 wt.% H3BO3 + 1 wt.% V2O5) did not show the expected effect with regards to capture rates and due to time constrain different wt.% of the promoter were not tested within the scope of this thesis. Therefore, no firm conclusion was given with regards to promoters. Based on the Murphree efficiency calculated from the experiment with keeping a constant liquid to gas flow ratio, a column height of 28-35 m is estimated to capture 90% of CO2 from the flue gas.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

In the search for large-scale production of renewable fuels and chemicals, hydrothermal liquefaction (HTL) of biomass has emerged as one of the most promising routes. Whilst this conversion route is suitable for various feedstocks, there has been enormous attention directed towards the utilisation of algae. The aim of this thesis is to gain a better understanding of the process scaling effects and to enhance the quality of the bio-crude oil product. A novel feature of this work is that it has successfully tested the HTL process in a continuous-flow (15–70 L/h) pilot-scale plant – by doing so, it has been able to shed light on the process engineering and scaling aspects. A maximum bio-crude yield of ~42 wt.% was achieved from a commercially-available microalga (Chlorella) while being processed with a 10 wt.% solids loading at 350 °C, 200 bar and 3 min residence time. The results indicate that maximal product yields may be obtained in much shorter times under continuous flow hydrothermal processing than batch studies have previously suggested. Collaboration with algal cultivation specialists also allowed links between biomass production and subsequent conversion to be explored. Promising results for a robust microalgae polyculture grown under waste streams from a coal-fired power station are presented and discussed. The opportunity of tailoring the algal growth process, through nutrient starvation, to improve the bio-crude properties was also investigated. Oils obtained from starved Oedogonium macroalgae were shown to contain considerably lower N levels (<2%), compared to those from normal Oedogonium as well as microalgae (>4%). A two-step batch HTL process, also aimed at producing low-N oil, is additionally put forward. In summary, a number of key contributions are contained in this thesis which included providing insights into scaling the HTL process, as well as employing novel approaches to enhance the quality of the derived products.

[EN] The main objective of this thesis is the analysis and comprehension of the association of two different combustion concepts (premixed and diffusive combustion) on the pollutant emissions and engine performance in a mid-size Diesel engine. The evaluation is performed at mid and high load conditions, where the implementation of premixed combustion is generally challenging. The association of the two combustion modes is hard to attain in a conventional Diesel engine, especially the preparation of the premixed charge with early pilot injection. Therefore, the approach followed during the study has been divided in two main steps: first, the bibliography on the subject is reviewed and two strategies avoiding the main issues mentioned in the literature are grossly evaluated in order to estimate their potential for emission reduction. Second, a deeper study of the combustion processes and emissions formation is performed, focusing only on the partially premixed combustion strategies that actually have the potential for emissions reduction. Along the second part of the study, the association of premixed and diffusive combustion is evaluated together with variation of conventional calibration parameters such as the intake oxygen concentration (via exhaust gas recirculation), the boost pressure and the start of the main injection timing, at different engine speed and load conditions. A cross analysis of the results obtained is performed in order to understand the key reasons that permit the reduction of the pollutant emissions with this strategy. In a final part of the thesis, the partially premixed combustion strategies studied are confronted with the challenges they might face when really considered for their introduction in a production engine (oil-dilution, noise...) to finally conclude on their technological potential.
[ES] El objetivo principal de la Tesis es el an álisis y la comprensi ón de la asociaci ón de dos conceptos de combusti ón diferentes (combusti ón en premezcla y por difusi ón) en las emisiones contaminantes y las prestaciones en un motor Diesel de cilindrada media. La evaluaci ón se realiza en condiciones de media y alta carga, en la cuales la implementaci ón de una combusti ón premezclada es generalmente complicada. La asociaci ón de los dos modos de combusti ón es dif cil de conseguir en un motor Diesel convencional, especialmente la preparaci ón de la carga premezclada con inyecci ón piloto adelantada. Por esa raz ón, el estudio se divide en dos partes principales: primero se revisa la bibliograf ía acerca del tema, centrando la atenci ón en dos estrategias que permiten evitar los principales problemas evocados en la literatura, determinando su potencial para la reducci ón de las emisiones contaminantes. En un segundo lugar, se realiza un estudio m as profundo de los procesos de combusti ón y de formaci ón de contaminantes, centr ándose únicamente en las estrategias de combusti ón parcialmente premezclada que sí tienen el potencial para reducir las emisiones contaminantes. En la segunda parte del estudio, se aborda la asociaci ón de combustiones premezclada y por difusi ón junto con la variaci ón de par ametros de calibraci on convencionales como la concentraci ón de ox ígeno en la admisi ón (por medio de recirculaci ón de los gases de escape), la presi ón de sobrealimentaci ón y el inicio de la inyecci ón principal, en diferentes condiciones de r egimen y de carga del motor. El an álisis cruzado de los resultados se realiza con el af án de entender las razones claves de los procesos que permiten la reducci ón de las emisiones contaminantes con esta estrategia. Como etapa final de esta tesis, se confrontan las estrategias de combusti ón parcialmente premezclada estudiadas con los problemas a los cuales podr ían llevar si realmente se considerar a su implementaci ón y un motor de serie (diluci ón de aceite, ruido...) para finalmente concluir sobre su potencial tecnol ógico.
[CAT] L'objectiu principal de la tesi es l'an alisi i la comprensi o de l'associaci o de dos conceptes de combusti o diferents (combusti o en premescla i per difusi o) en les emissions contaminants i les prestacions en un motor Di esel de cilindrada mitjana. L'avaluaci o es realitza en condicions de mitja i alta c arrega, en las quals la implementaci o d'una combusti o premesclada es generalment complicada. L'associaci o dels dos modes de combusti o es dif cil d'aconseguir en un motor Di esel convencional, especialment la preparaci o de la c arrega premesclada amb injecci o pilot avan cada. Per eixa ra o, l'estudi es divideix en dos parts principals: primer es revisa la bibliogra a sobre el tema, centrant l'atenci o en dos estrat egies que permeten evitar els principals problemes evocats en la literatura, determinant el seu potencial per a la reducci o de les emissions contaminants. En un segon lloc, es realitza un estudi m es profund dels processos de combusti o i de formaci o de contaminants, centrant-se unicament en les estrat egies de combusti o parcialment premesclada que si que tenen el potencial per a reduir les emissions contaminants. En la segona part de l'estudi, s'aborda l'associaci o de combustions premesclada i per difusi o junt amb la variaci o de par ametres de calibratge convencionals com la concentraci o d'oxigen en l'admissi o (per mitj a de recirculaci o dels gasos d'escapament), la pressi o de sobrealimentaci o i l'inici de la injecci o principal, en diferents condicions de r egim i de c arrega del motor. L'an alisi creuat dels resultats es realitza amb l'afany d'entendre les raons claus dels processos que permeten la reducci o de les emissions contaminants amb esta estrat egia. Com a etapa final d'esta tesi, es confronten les estrat egies de combusti o parcialment premesclada estudiades amb els problemes als quals podrien portar si realment es consideraria la seua implementaci o en un motor de s erie (diluci o d'oli, soroll...) per a finalment concloure sobre el seu potencial tecnol ogic.
Arthozoul, SJL. (2016). Study of the association of premixed and diffusive combustion processes on the combustion and pollutant emissions in a mid-size Diesel engine [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63262
TESIS

The focus of this thesis was on investigation of culture selection step for PHA production by using food waste as no-cost feedstock with mixed microbial cultures (MMC). PHAs (polyhydroxyalkanoates) are biologically synthesized polymers that can be produced from renewable resources and are completely biodegradable. Because at the present times the demand of alternatives to replace conventional plastics is rapidly growing due to environmental issues, the possibility to produce PHAs on a large scale by using waste materials as carbon source is considered to be very attractive both from an environmental and economic point of view. The experimental work was developed during a traineeship carried out at the Laboratory of Biochemical and Chemical Engineering of NOVA School of Science and Technology. The selection step was conducted through the employment of a sequential batch reactor (SBR) at pilot scale and had the main goal of getting a high performance process while ensuring a satisfying reactor stability. Operations were performed using fermented food waste provided by ValorSul. ValorSul is a Portuguese company which is responsible for the management of urban solid waste produced in five municipalities in the area of Lisbon. In particular, the aim was to assess selection step outcomes while operating with a high OLR (organic loading rate). Few studies on MMC culture selection step conducted applying high OLR values are currently reported in literature. Two different SBR operating conditions were investigated and compared in this thesis work: HRT (hydraulic retention time) equal to 1 day in a first phase and HRT equal to 0.66 day in a second phase. After several cycles, a PHA-rich culture was selected from the SBR and it was inoculated in fed-batch lab scale reactors during accumulation tests with the main aim of evaluating the maximum reachable PHA content and PHA productivity for both two operating conditions configurations.

In the Basin and Range Province, the geologic regime of the Pilot Valley, linear trending block faults have isolated many valleys both topographically and hydrologically. Discharge from these arid, closed basins occurs only as evaporation. Minerals dissolved in discharging fluid are precipitated at the valley floor as the liquid evaporates. The resulting salt flats and high density brines are known as playas. The Pilot Valley Playa surface was sampled concurrently with the recording of a Thematic Mapper remotely sensed image to define the surface conditions that correspond to image data. An association was found between the band 7 (infrared wavelength radiation) image data and the measured depth to water; and between the visible wavelength data and the evaporite mineral deposits on the playa. The specific gravity of the shallow subsurface brine was found to increase as the liquid brine surface approached the elevation of the valley floor. By using the observed relationships, three remotely sensed images were interpreted with respect to temporal changes in the areal extent of playa evaporite deposits and water depth between 1984 and 1988. The visible wavelength data indicated that the areal extent of the evaporite deposits diminished during the study period. The water level at the playa margins was interpreted to have dropped, and at the playa center to have remained stable. These interpretations suggest that a decrease in the extent of evaporite deposition is related to a drop in the water level around the playa margins. The interpreted changes of the playa surface are used to draw the following conclusions about the hydrology of the Pilot Valley. The distinct variation in depth to water around the playa margin suggests that these areas are influenced by the discharge from the surrounding ranges. The relatively stable water depth in the central playa and the associated thicker evaporite deposits suggest that the subsurface brine acts here as a buffer to discharge variations. If the temporal changes of the playa margins do result from discharge variation, the discharge zone at the base of the Silver Island Range is wider than that of the adjacent, higher elevation Pilot Range.

Relapse prevention after pain management is a neglected area and Internet-based interventions have the potential to partly fill this gap. A challenge in designing effective relapse prevention program is how to motivate patients to persist throughout the full length of treatment. Following a regular pain management program, 29 participants underwent a 20 week long Internet–based relapse prevention program based on acceptance-oriented CBT. Qualitative analyses showed changes in attitudes towards their pain and body during the course of treatment. Degree of personal commitment in treatment goals seemed to affect gains relating to new perspective on self and future. Therapeutic strategies of defusion and mindfulness seemed to ease perspective changes and persistence to comply. Values interventions are hypothesized to be a plausible therapeutic strategy to engage participants in continuous behavior change. Further studies on non-compliers and drop-outs could enhance understanding of interventions necessary to maintaining motivation. When and how to give therapist support during Internet-based treatment for chronic pain is another area in need of further studies.

A reutilização de resíduos e sua destinação são desafios seguidamente enfrentados na indústria. Por ser extensa e empregar uma grande variedade de processos, matérias-primas e insumos, a cadeia do aço se beneficia por ter ampla flexibilidade e diversas possibilidades de reintrodução de compostos em sua rota de fabricação. Resíduos carbonosos, por exemplo, podem ser parcialmente usados em misturas de carvões no processo de coqueificação dependendo do tamanho e da composição química. Este trabalho, teve como objetivo, avaliar a influência da adição de moinha de carvão vegetal em uma mistura de carvões para a produção de coques em forno piloto de coqueificação e determinar os teores máximos de incorporação suportados pela mistura, avaliando parâmetros de qualidade do coque. Para isso, a moinha de carvão vegetal de eucalipto foi introduzida em duas frações granulométricas distintas, uma composta por partículas mais grosseiras (fração G) e outra composta por partículas mais finas (fração F), e caracterizado juntamente com a mistura utilizada. Posteriormente, os coques produzidos em forno piloto também foram caracterizados através de diversas análises: imediata, elementar, área superficial, porosidade, textura óptica, reatividade em termobalança, CRI/CSR e DI150/15. Os resultados atingidos mostraram que inserção da fração G de moinha comprometeu menos os parâmetros de qualidade dos coques com carvão vegetal. Teores de até 3% de moinha foram suportados para essa distribuição de tamanho de partícula enquanto que para a fração F, somente 1%. Outro fator observado foi que os coques produzidos com adição de moinha de carvão vegetal não tiveram queda significativa no teor de enxofre, a exceção da amostra contendo 10% de carvão vegetal na fração G. Em todas as amostras com moinha de carvão vegetal também foi possível notar o aumento da área superficial em relação ao coque de referência. Os testes termogravimétricos dinâmicos também trouxeram informações relevantes a respeito das temperaturas e taxas aparentes de reações dos coques feitos com moinha de carvão vegetal.
The reuse of waste materials and its destination are challenges continuously faced for industry. For being far-flung and apply a huge variety of process, raw materials and inputs, the steel supply chain benefits from having a high flexibility and many possibilities of reintroducing compounds in its manufacturing route. For example, carbonaceous materials can be used partially in coal blends for cokemaking process depending on particle size and chemical composition. The current work aimed to evaluate the influence of adding fine charcoal to a coal blend for coke production in a pilot oven and to determine the maximum content tolerated for the blend, assessing coke quality parameters. For this, a eucalyptus charcoal residue was introduced in two different size distributions, one composed of coarser particles (fraction G) and another of finer (fraction F), and characterized together with the coal blend used. Afterwards, the cokes produced in pilot oven were also characterized through several analyzes: proximate, ultimate, surface area, porosity, optical texture, reactivity on thermobalance, CRI/CSR e DI150/15. The results achieved showed that the insertion of charcoal on fraction G compromised less the quality parameters of cokes with charcoal. Contents up to 3% of charcoal were tolerated for this particle size distribution while for fraction F, only 1%. Another point noticed was that the coke produced with charcoal addition had no significant drop on sulfur content, with the exception of the coke sample with 10% of charcoal and fraction G. In all samples with charcoal it was also possible to see an increase on surface area in relation to the reference coke. The dynamic thermogravimetric tests also provided relevant information regarding to the temperatures and apparent reaction rates of cokes made with charcoal.

Il seguente lavoro di tesi ha lo scopo di verificare una procedura di dimensionamento per silo contenenti polveri solide - Jenike's procedure - che è utilizzata al fine di ottenere, durante lo svuotamento degli impianti, il mass flow come regime di flusso. Tale verifica della procedura consiste nel confrontare i valori calcolati dell'angolo di inclinazione rispetto alla verticale della tramoggia del silo e della dimensione principale della sezione d'uscita con i valori direttamente misurati in un silo di piccole dimensioni. L'esecuzione della Jenike's procedure richiede una caratterizzazione della flowability delle polveri indagate: chalk, sawdust, perlite e potato starch. La misurazione delle flow properties delle polveri solide è stata effettuata utilizzando una RST-XS (Ring Shear Tester). Le prove svolte con tale strumento sono lo yield locus test e il wall yield locus test, permettendo di misurare così yield loci, wall yield loci e flow fuctions. In parallelo a questo lavoro sono state effettuate misurazioni dell'AOR (Angle of Repose) al fine di cercare una correlazione diretta con l'angolo di inclinazione della tramoggia dell'impianto pilota. Durante lo svolgimento del progetto è inoltre stato implementato uno stress sensor all'interno del silo con lo scopo di effettuare misurazioni dello stato degli stress agenti in pianta. E' stato ottenuto che la Jenike's procedure sovradimensiona di un certo valore il silo pilota. Ulteriori indagini riguardanti il metodo adottato per effettuare il dimensionamento potrebbero presumibilmente permettere la riduzione del sovradimensionamento. Per quanto riguarda il confronto tra AOR e l'angolo di inclinazione della tramoggia non è stata invece trovata alcuna correlazione. Mentre i valori dello stress misurati con lo stress sensor sono emersi conformi con i valori attesi dalle relazioni teoriche (Janssen's equation e method of Arnold and McLean).

This dissertation reports on research related to ultrafiltration (UF) membranes in drinking water applications. A pilot-scale investigation identified seasonal surface water quality impacts on UF performance and resulted in the development of a dynamic chemically enhanced backwash protocol for fouling management. Subsequent analysis of UF process data revealed limitations with the use of specific flux, transmembrane pressure (TMP), and other normalization techniques for assessing UF process fouling. A new TMP balance approach is presented that identifies the pressure contribution of membrane fouling and structural changes, enables direct process performance comparisons at different operating fluxes, and distinguishes between physically and chemically unresolved fouling. In addition to the TMP balance, a five component optimization approach is presented for the systematic improvement of UF processes on the basis of TMP variations. Terms are defined for assessing process event performance, a new process utilization term is presented to benchmark UF productivity, and new measures for evaluating maintenance procedures are discussed. Using these tools, a correlation between process utilization and operating pressures was established and a sustainable process utilization of 93.5% was achieved. UF process capabilities may be further enhanced by pre-coating media onto the membrane surface. Silicon dioxide (SiO2) and powdered activated carbon (PAC) are evaluated as pre-coating materials, and the applicability of the TMP balance for assessing pre-coated membrane performance is demonstrated. The first use of SiO2 as a support layer for PAC in a membrane pre-coating application is presented at the laboratory-scale. SiO2-PAC pre-coatings successfully reduced physically unresolved fouling and enhanced UF membrane organics removal capabilities.
Ph.D.
Doctorate
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Environmental Engineering

The US Department of Energy in 2010 has identified several rare earth elements as critical materials to enable clean technologies. As part of ongoing research in REEs (rare earth elements) recovery from coal sources, the University of Kentucky has designed, developed and is demonstrating a ¼ ton/hour pilot-scale processing plant to produce high-grade REEs from coal sources. Due to the need to control critical variables (e.g. pH, tank level, etc.), process control is required. To ensure adequate process control, a study was conducted on leaching and solvent extraction control to evaluate the potential of achieving low-cost REE recovery in addition to developing a process control PLC system. The overall operational design and utilization of Six Sigma methodologies is discussed. Further, the application of the controls design, both procedural and electronic for the control of process variables such as pH is discussed. Variations in output parameters were quantified as a function of time. Data trends show that the mean process variable was maintained within prescribed limits. Future work for the utilization of data analysis and integration for data-based decision-making will be discussed.

Coal preparation plants are required in some cases to produce a high-grade product using a low specific gravity cut-point. For these situations, a second higher gravity separation would be desirable to generate a mid-grade product that can be utilized for electricity generation thereby maximizing coal recovery. A study was conducted to evaluate the potential of achieving efficient separations at two different density cut-points in a single stage using a three-product dense medium cyclone. Variations in density cut-point and process efficiency values were quantified as a function of the feed medium density, feed medium-to-coal ratio, and feed pressure using a three-level experimental design program. Results indicate the ability to effectively treat coal over a particle size range from 6mm to 0.15mm while achieving both low- and high-density cut-points up to 1.95 relative density. Ash content decreased from 27.98% in the feed to an average of 7.77% in the clean coal product and 25.76% in the middlings product while sulfur content was reduced from 3.87 to 2.83% in the clean coal product. The overall combustible recovery was maintained above 90% while producing clean coal products with ash and total sulfur content as low as 5.85 and 2.68%, respectively. Organic efficiency values were consistently about 95% and probable error values were in the range of 0.03 to 0.05, which indicates the ability to provide a separation performance equivalent to or better than traditional coal cleaning technologies.

Dans de nombreux procédés industriels apparaît une étape de séparation liquide/solide qui est très souvent effectuée en combinant en série une séparation mécanique et une séparation thermique (séchage). L'intégration d'un apport thermique dans un équipement de séparation mécanique offre de nombreux avantages (investissement réduit, productivité améliorée, encombrement limité...). Par ailleurs, l'utilisation simultanée des effets mécaniques et thermiques peut conduire dans certains cas à des synergies permettant une utilisation optimisée de l'énergie. Un apport thermique par chauffage diélectrique peut être adapté à une essoreuse. L'objectif de la thèse est de concevoir et réaliser un prototype à l'échelle semi-industrielle dans le but de démontrer l'intérêt énergétique d'une telle technique. Les résultats obtenus sont : le développement et l'instrumentation complète d'un pilote d'essoreuse autorisant l'insertion des micro-ondes. La mise en évidence d'une synergie entre les phénomènes de séchage induits par un chauffage diélectrique et les effets centrifuges liés à la rotation du panier dans de cas des bobines textiles.La modélisation de différents phénomènes physiques liés à l'essorage de gâteaux de filtration, à l'évaluation de leur permittivité complexe, à la connaissance du champ électromagnétique, aux écoulements d'air utilisés pour l'extraction de la vapeur et à la détermination des transferts de masse et de chaleur
In a lot of industrial processes, liquid/solid separation is carried out by combination of mechanical and thermal separation (drying). Thermal drying in a mechanical separation device offers a lot of advantages (lower investment, higher productivity, limited footprint. . . ). Moreover, coupling mechanical and thermal effects may lead in some cases to synergic effects allowing an optimal use of energy.Thermal input by dielectric heating may be adapted to a centrifuge. The objective of the project is to design and produce a prototype at pilot scale in order to point out the energetic interest of such a process. So, mechanical separation (centrifuge filtration, drainage) and dielectric heating have to be used simultaneously. Pilot instrumentation will allow to control key parameters of the coupled operation and the global energy consumption. Main results are : the development and the full instrumentation of a centrifuge pilot allowing implement of microwaves. The demonstration of a synergy, in the case of textile spools, between drying effects generated by dielectric heating and centrifuge effects generated by centrifuge basket rotation. The simulation of different physical phenomena linked to filtration cake drainage, dielectric constants assessment, determination of electromagnetic field, air flow used for vapor extraction and determination of heat and mass transfers

In this study a supercritical fluid extraction process using carbon dioxide as a solvent was developed and investigated as a potential energy efficient and cost effective alternative to conventional distillation for the extraction and subsequent fractionation of high value renewable chemicals from lignocellulosic bio-oil. Fundamental solubility studies utilizing both laboratory and pilot infrastructure were completed, and equation of state modelling and process simulations developed for the first time for this supercritical fluid extraction process. Techno-economic evaluation of the processes revealed that supercritical fluid extraction of bio-oil is a competitive alternate to conventional distillation process.

A pirólise rápida é um processo para conversão térmica de uma biomassa sólida em altos rendimentos de um produto líquido chamado de bio-óleo. Uma das alternativas para geração de um bio-óleo com menor teor de oxigênio é uso de catalisadores nos reatores de pirólise, ao invés de um inerte, num processo chamado de pirólise catalítica. O objetivo deste trabalho foi testar catalisadores comerciais, um ácido e outro básico, em uma unidade piloto de leito fluidizado circulante. O catalisador ácido utilizado foi o Ecat, proveniente de uma unidade industrial de craqueamento catalítico fluido (FCC), e como catalisador básico foi utilizado uma hidrotalcita. Os resultados foram comparados com testes utilizando um material inerte, no caso uma sílica. Uma unidade piloto de FCC do CENPES foi adaptada para realizar os testes de pirólise catalítica. Após fase de modificação e testes de condicionamento, foi comprovada a viabilidade na utilização da unidade piloto adaptada. Contudo, devido a limitações operacionais, maiores tempos de residência tiveram que ser aplicados no reator, configurando o processo como pirólise intermediária. Foram então realizados testes com os três materiais nas temperaturas de 450C e 550C. Os resultados mostraram que o aumento do tempo de residência dos vapores de pirólise teve um impacto significativo nos rendimentos dos produtos quando comparada com o perfil encontrado na literatura para pirólise rápida, pois devido ao incremento das reações secundárias, produziu maiores rendimentos de coque e água, e menores rendimentos de bio-óleo. O Ecat e a hidrotalcita se apresentaram mais efetivos em termos de desoxigenação. O primeiro apresentou maiores taxas de desoxigenação via desidratação e a hidrotalcita apresentou maior capacidade para descarboxilação. Contudo, o uso de Ecat e hidrotalcita não se mostrou adequado para uso em reatores de pirólise intermediária, pois acentuou ainda mais as reações secundárias, gerando um produto com alto teor de água e baixo teor de compostos orgânicos no bio-óleo, além de produzirem mais coque. À temperatura de 450C estes efeitos foram mais pronunciados. Em termos de caracterização química, a condição de pirólise intermediária apontou para a produção de bio-óleos com perfil fenólico, sendo a sílica o que proporcionou os melhores rendimentos, principalmente a temperatura de 550C, sendo superiores aos encontrados na literatura. Analisando as composições dos bio-óleos sob a ótica da produção de biocombustíveis, nenhum dos materiais testados apresentou rendimentos consideráveis em hidrocarbonetos. De maneira geral, a sílica foi o que proporcionou os melhores resultados em termos de rendimento e qualidade do bio-óleo. Sua menor área superficial e sua característica de inerte se mostraram mais adequados para o processo de pirólise intermediária, onde a contribuição das reações secundárias em fase gasosa é elevada em função do tempo de residência no reator
The fast pyrolysis is a thermal process that converts, at high yield, solid biomass into a liquid product called bio-oil. One alternative for the generation of bio oil with lower oxygen content is the use of catalysts in the pyrolysis reactor, rather than an inert, a process called catalytic pyrolysis. The objective of this study was to test two such commercial catalysts, one acid and the other basic, in a pilot plant with a circulating fluidized bed reactor. The acid catalyst used was the Ecat, which is a catalyst from an industrial fluid catalytic cracking plant (FCC), and the base catalyst used was hydrotalcite. The results were compared with tests using an inert material, a type of silica. A FCC pilot plant at CENPES was chosen and adapted to perform the catalytic pyrolysis tests. After the modification phase, the feasibility of using the adapted pilot unit was verified. However, due to operational limitations, higher reactor residence times had to be adopted in the reactor, leading to the re-classification of the pyrolysis process as intermediate in terms of this parameter. Tests were then conducted with the three materials at temperatures of 450C and 550C. The results showed that increasing the residence time of pyrolysis vapors had a significant impact on products yields, when compared with the profile found in the literature for fast pyrolysis, since the increase in secondary reactions produced higher yields of coke and water, and lower yields of bio-oil. The Ecat and hydrotalcite showed to be more effective in terms of deoxygenation. The Ecat presented higher deoxygenation rates by dehydration and the hydrotalcite showed greater capacity for decarboxylation. However, the use of Ecat and hydrotalcite was not suitable for intermediate pyrolysis reactors, since both materials increase secondary reactions, generating a product with high water content and low content of organic compounds in bio-oil and produce more coke. These results were more pronounced at the lower temperature tested (450C). In terms of chemical characterization, the intermediate pyrolysis conditions produced bio-oils with phenolic profile. Among the tested materials, silica presented better phenolic yields, especially at higher temperatures (550C). These results are also superior to those found in current literature. Analyzing the composition of bio-oils from the standpoint of biofuel production, none of the materials tested showed considerable hydrocarbons yields. In general, silica had the best results in terms of yield and quality of bio-oil. Being an inert material, silica was more suitable for intermediate pyrolysis process, where the contribution of secondary reactions in the gas phase is high due to the residence time in reactor

Detta projekt har utförts på ett charterflygbolag som verkar på den skandinaviska flygmarknaden, och är en första del i flygbolagets projekt (översatt till svenska) ”Världens bästa planeringsprocess”. ”Världens bästa planeringsprocess” skall kartlägga flygbolagets planeringsprocess sett till från det att en förfrågan kommer in till flygbolaget, till dess att ett svar kan lämnas till kunden. Detta projekt som behandlas i denna rapport studerar informationsflödesprocessen inom flygbolaget med fokus på den planering som sker efter att en kommande säsongs flygprogram är fastlagt. Det vill säga, detta projekt behandlar de förfrågningar som utgör förändringar och tillägg i flygprogrammet. Utifrån en kartläggning har informationsflödesprocessen analyserats utifrån Lean production-teori och tillämpbara åtgärder för att uppnå tidseffektivisering i flöden. Detta har sammanfattats i de följande möjliga åtgärderna för flygbolaget: - Omfördelning av flödet genom synkronisering, parallellisering och sekvensering - Omfördelning av arbetsuppgifter - Tillämpning av Alternate Chief Pilot Det rekommenderas att tillämpa samtliga åtgärdsförslag, vilket bedöms kunna ge en tidsbesparing på mellan 7 och 52 % i ledtid.

This is a longitudinal couples therapy process study using coded data from eleven couples to identify which therapist behaviors (warmth, listener responsiveness, communication, dominance) influenced positive couples exchanges (warmth and listener responsiveness) over time in Emotionally Focused Couples Therapy (EFT). A mixed effects model was used to examine within- and between-individual variability. Men and women were modeled separately. A series of two-level multilevel models of change were examined, where Time is Level 1 and Individual is Level 2. Results indicated no significant relationship between variables of therapist warmth, listener responsiveness, communication, and dominance with couple listener responsiveness. Where client warmth was an outcome variable, the only significant relationship was between therapist warmth toward husband and husband warmth toward wife. Findings demonstrated that 62.9% of the variance in husband warmth toward wife was accounted for by therapist warmth to husband across time in therapy. Specifically, therapist warmth toward husband was significantly and positively related to husband warmth toward wife over time in therapy. Clinical implications and directions for future research are discussed.

It is becoming more important that transport agendas acknowledge complex social sustainability matters like feelings of safety and security. For developing knowledge in this context today, participatory descriptive assessments hold a strong position. However, quantitative methods providing popular transport appraisals, have a clearer impact focus, but struggle with encompassing social sustainability matters. Filling the methodological gap that exists between the participatory descriptive tradition and the quantitative impact tradition, can be vital in moving methods closer to public and policy demands and norms. This work uses independent interdisciplinary collaboration and assesses the appropriateness of the Participatory Value Evaluation (PVE) method for encompassing feelings of safety and security in public transport in the context of Stockholm, Sweden. The PVE method evaluates projects through participation and quantifies results without relying monetary valuation, while allowing for norms to be detected. By using in depth descriptive information as PVE input, this study aims to provide a methodological contribution by analysing the PVE method in a new complex setting with modifications made. Descriptive results from the PVE method is regarded to still advance knowledge on feelings of safety and security, while improving the impact focus of appraisals by evaluating projects. The method can benefit from a focus on transparency, attractive participation and quality in results and the amendment here called ‘re-categorisation’ was found necessary for PVE appraisals. Incentives to keep flawed processes can be found in political and policy realms and with no actor controlling the intersectoral (and interdisciplinary) issue of feelings of safety and security, traditions can have a strong impact. However, this study shows feasibility in improving appraisals given the contemporary public and policy standards.

Owing to its ability to improve both spectral and energy efficiency of wireless networks, massive multiple-input multiple-output (mMIMO) has become one of the key enablers of the fifth-generation (5G) and beyond communication systems. For successful integration of this promising physical layer technique in the upcoming cellular standards, it is essential to have a comprehensive understanding of its network-level performance. Over the last decade, stochastic geometry has been instrumental in obtaining useful system design insights of wireless networks through accurate and tractable theoretical analysis. Hence, it is only natural to consider modeling and analyzing the mMIMO systems using appropriate statistical constructs from the stochastic geometry literature and gain insights for its future implementation. With this broader objective in mind, we first focus on modeling a cellular mMIMO network that uses fractional pilot reuse to mitigate the sole performance-limiting factor of mMIMO networks, namely, pilot contamination. Leveraging constructs from the stochastic geometry literature, such as Johnson-Mehl cells, we derive analytical expressions for the uplink (UL) signal-to-interference-and-noise ratio (SINR) coverage probability and average spectral efficiency for a random user. From our system analysis, we present a partitioning rule for the number of pilot sequences to be reserved for the cell-center and cell-edge users that improves the average cell-edge user spectral efficiency while achieving similar cell-center user spectral efficiency with respect to unity pilot reuse. In addition, using the analytical approach developed for the cell-center user performance evaluation, we study the performance of a small cell system where user and base station (BS) locations are coupled. The impact of distance-dependent UL power control on the performance of an mMIMO network with unity pilot reuse is analyzed and subsequent system design guidelines are also presented. Next, we focus on the performance analysis of the cell-free mMIMO network, which is a distributed implementation of the mMIMO system that leads to the second and third contributions of this dissertation. Similar to the cellular counterpart, the cell-free systems also suffer from pilot contamination due to the reuse of pilot sequences throughout the network. Inspired by a hardcore point process known as the random sequential adsorption (RSA) process, we develop a new distributed pilot assignment algorithm that mitigates the effect of pilot contamination by ensuring a minimum distance among the co-pilot users. This pilot assignment scheme leads to the construction of a new point process, namely the multilayer RSA process. We study the statistical properties of this point process both in one and two-dimensional spaces by deriving approximate but accurate expressions for the density and pair correlation functions. Leveraging these new results, for a cell-free network with the proposed RSA-based pilot assignment scheme, we present an analytical approach that determines the minimum number of pilots required to schedule a user with probabilistic guarantees. In addition, to benchmark the performance of the RSA-based scheme, we propose two optimization-based centralized pilot allocation schemes using linear programming principles. Through extensive numerical simulations, we validate the efficacy of the distributed and scalable RSA-based pilot assignment scheme compared to the proposed centralized algorithms. Apart from pilot contamination, another impediment to the performance of a cell-free mMIMO is limited fronthaul capacity between the baseband unit and the access points (APs). In our fourth contribution, using appropriate stochastic geometry-based tools, we model and analyze the downlink of such a network for two different implementation scenarios. In the first scenario, we consider a finite network where each AP serves all the users in the network. In the second scenario, we consider an infinite network where each user is served by a few nearby APs in order to limit the load on fronthaul links. From our analyses, we observe that for the finite network, the achievable average system sum-rate is a strictly quasi-concave function of the number of users in the network, which serves as a key guideline for scheduler design for such systems. Further, for the user-centric architecture, we observe that there exists an optimal number of serving APs that maximizes the average user rate. The fifth and final contribution of this dissertation focuses on the potential improvement that is possible by the use of mMIMO in citizen broadband radio service (CBRS) spectrum sharing systems. As a first concrete step, we present comprehensive modeling and analysis of this system with omni-directional transmissions. Our model takes into account the key guidelines by the Federal Communications Commission for co-existence between licensed and unlicensed networks in the 3.5 GHz CBRS frequency band. Leveraging the properties of the Poisson hole process and Matern hardcore point process of type II, a.k.a. ghost RSA process, we analytically characterize the impact of different system parameters on various performance metrics such as medium access probability, coverage probability, and area spectral efficiency. Further, we provide useful system design guidelines for successful co-existence between these networks. Building upon this omni-directional model, we also characterize the performance benefits of using mMIMO in such a spectrum sharing network.
Doctor of Philosophy
The emergence of cloud-based video and audio streaming services, online gaming platforms, instantaneous sharing of multimedia contents (e.g., photos, videos) through social networking platforms, and virtual collaborative workspace/meetings require the cellular communication networks to provide high data-rate as well as reliable and ubiquitous connectivity. These constantly evolving requirements can be met by designing a wireless network that harmoniously exploits the symbiotic co-existence among different types of cutting-edge wireless technologies. One such technology is massive multiple-input multiple-output (mMIMO), whose core idea is to equip the cellular base stations (BSs) with a large number of antennas that can be leveraged through appropriate signal processing algorithms to simultaneously accommodate multiple users with reduced network interference. For successful deployment of mMIMO in the upcoming cellular standards, i.e., fifth-generation (5G) and beyond systems, it is necessary to characterize its performance in a large-scale wireless network taking into account the inherent spatial randomness in the BS and user locations. To achieve this goal, in this dissertation, we propose different statistical methods for the performance analysis of mMIMO networks using tools from stochastic geometry, which is a field of mathematics related to the study of random patterns of points. One of the major deployment issues of mMIMO systems is pilot contamination, which is a form of coherent network interference that degrades user performance. The main reason behind pilot contamination is the reuse of pilot sequences, which are a finite number of known signal waveforms used for channel estimation between a user and its serving BS. Further, the effect of pilot contamination is more severe for the cell-edge users, which are farther from their own BSs. An efficient scheme to mitigate the effect of pilot contamination is fractional pilot reuse (FPR). However, the efficiency of this scheme depends on the pilot partitioning rule that decides the fraction of total pilot sequences that should be used by the cell-edge users. Using appropriate statistical constructs from the stochastic geometry literature, such as Johnson-Mehl cells, we present a partitioning rule for efficient implementation of the FPR scheme in a cellular mMIMO network. Next, we focus on the performance analysis of the cell-free mMIMO network. In contrast to the cellular network, where each user is served by a single BS, in a cell-free network each user can be served by multiple access points (APs), which have less complex hardware compared to a BS. Owing to this cooperative and distributed implementation, there are no cell-edge users. Similar to the cellular counterpart, the cell-free systems also suffer from pilot contamination due to the reuse of pilot sequences throughout the network. Inspired by a hardcore point process known as the random sequential adsorption (RSA) process, we develop a new distributed pilot assignment algorithm that mitigates the effect of pilot contamination by ensuring a minimum distance among the co-pilot users. Further, we show that the performance of this distributed pilot assignment scheme is appreciable compared to different centralized pilot assignment schemes, which are algorithmically more complex and difficult to implement in a network. Moreover, this pilot assignment scheme leads to the construction of a new point process, namely the multilayer RSA process. We derive the statistical properties of this point process both in one and two-dimensional spaces. Further, in a cell-free mMIMO network, the APs are connected to a centralized baseband unit (BBU) that performs the bulk of the signal processing operations through finite capacity links, such as fiber optic cables. Apart from pilot contamination, another implementational issue associated with the cell-free mMIMO systems is the finite capacity of fronthaul links that results in user performance degradation. Using appropriate stochastic geometry-based tools, we model and analyze this network for two different implementation scenarios. In the first scenario, we consider a finite network where each AP serves all the users in the network. In the second scenario, we consider an infinite network where each user is served by a few nearby APs. As a consequence of this user-centric implementation, for each user, the BBU only needs to communicate with fewer APs thereby reducing information load on fronthaul links. From our analyses, we propose key guidelines for the deployment of both types of scenarios. The type of mMIMO systems that are discussed in this work will be operated in the sub-6 GHz frequency range of the electromagnetic spectrum. Owing to the limited availability of spectrum resources, usually, spectrum sharing is encouraged among different cellular operators in such bands. One such example is the citizen broadband radio service (CBRS) spectrum sharing systems proposed by the Federal Communications Commission (FCC). The final contribution of this dissertation focuses on the potential improvement that is possible by the use of mMIMO in the CBRS systems. As our first step, using tools from stochastic geometry, we model and analyze this system with a single antenna at the BSs. In our model, we take into account the key guidelines by the FCC for co-existence between licensed and unlicensed operators. Leveraging properties of the Poisson hole process and hardcore process, we provide useful theoretical expressions for different performance metrics such as medium access probability, coverage probability, and area spectral efficiency. These results are used to obtain system design guidelines for successful co-existence between these networks. We further highlight the potential improvement in the user performance with multiple antennas at the unlicensed BS.

The purpose of this final thesis isto develop a model for justification and evaluation of RFID technology. RFID is a new, relatively untested, technology using radio signals for automatic identification of different objects. Our theoretical frame of references focuses on research about RFID and implementation iss ues, we also conducted case studies and interviews in order to learn about RFID. Most RFID installations of today are Pilots or early adopters wanting to try new technology. A lot of the written sources were reports from consultancy firms or suppliers of technology.

Implementing RFID in real environment gave important insights into potentials and limitations of the technology. It proved that it is difficult to achieve sufficient readability in a steel environment. We also learned that one should not underestimate the time for installation and tuning in order to meet higher readability. The project finally resulted in an iterative model for justification and evaluation of RFID technology.

With a growing concern of climate change due to increased levels of CO2 in the atmosphere, carbon sequestration has been suggested as a possible solution for climate change mitigation. Biochar,a highly carbonaceous product produced through pyrolysis, is considered a viable option due to its content of stable carbon. This work covers the investigation of the possibility to produce biocharfrom four different feedstocks, namely peat, straw, horse manure and sewage sludge. The study includes a literature study and a five-week trial period at a 500 kW pilot plant, PYREG 500, in Högdalen. The thermal behaviour of the feedstocks, including garden waste, was investigated using thermogravimetric analysis (TGA). The TGA results were used to decide the optimal pyrolysis temperature for peat and straw at the pilot plant. The TGA results showed that the feedstocks behave differently when pyrolysed; the mass loss rate as well as the final mass loss varied. Physiochemical characterisation of the biochar was completed and the results were in agreement with previous studies. The produced biochar from straw and two types of peat had a C content above50 wt.% (76.6, 80.7, 79.2 wt.%) and low molar ratios of H/C (0.33, 0.36, 0.38) and O/C (0.032,0.023, 0.024). The pH increased as a consequence of pyrolysis and the biochars were alkaline (pH10.1, 8.5, 8.3). Polycyclic aromatic hydrocarbons (PAHs) were found in biochar from both strawand peat (8.26, 1.03, 5.83 mg/kg). In general, nutrients and heavy metals were concentrated in the biochar, except for Cd which decreased and Hg which could not be determined. The specific surface area of biochar from straw was considered small (21 m2/g) while biochar from peat had a higher specific surface area with a greater span (102-247 m2/g). The properties of the produced biochar were compared to the criteria included in the European Biochar Certificate and some of them were fulfilled, including the content of C, PAH and heavy metals. A flue gas analysis was completed when operating the pilot plant on straw pellets and it was showed that several emissions were released, including NO2, SOX, HCl and particulates, however, solely the emissions of NO2 exceed the regulations which will be applied in 2020. Regarding process design of a future pyrolysis plant, it is suggested that the means of material transport, particle separation, temperature control and quenching of biochar should be improved.

This thesis deals with software process improvement based on the deployment package Software testing, which is a guide for implementation of testing related processes of the international standard ISO/IEC 29110 Life-Cycle Profiles for Very Small Entities. The aim of this thesis is localization of the deployment package Software testing into Czech and realization of the pilot project based on this package on the real software project in a very small enterprise. Another aim is to evaluate the deployment package and to propose modifications to improve it. The real benefit of this thesis is in realization of the pilot project itself, which resulted in testing process improvement in the enterprise. Another expected benefits of this thesis based on its goals are in actual localization of the deployment package into Czech, its evaluation and suggestion of its modifications. Thesis as a whole can be used as a guide and information source for other enterprises seeking an improvement of the testing process as it provides an example of the deployment package Software testing implementation and also theoretical introduction to testing and software process improvement in a small enterprise.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Heightened concerns for cleaner air and increasingly more stringent regulations on sulphur content in transportation fuels will make desulphurization more and more important. The sulphur problem is becoming more serious in general, particularly for diesel fuels as the regulated sulphur content is getting an order of magnitude lower, while the sulphur contents of crude oils are becoming higher. This thesis aimed to develop a desulphurisation process (based on oxidation followed by extraction) with high efficiency, selectivity and minimum energy consumption leading to minimum environmental impact via laboratory batch experiments, mathematical modelling and optimisation. Deep desulphurization of model sulphur compounds (di-n-butyl sulphide, dimethyl sulfoxide and dibenzothiophene) and heavy gas oils (HGO) derived from Libyan crude oil were conducted. A series of batch experiments were carried out using a small reactor operating at various temperatures (40-100 °C) with hydrogen peroxide (H2O2) as oxidant and formic acid (HCOOH) as catalyst. Kinetic models for the oxidation process are then developed based on 'total sulphur approach'. Extraction of unoxidised and oxidised gas oils was also investigated using methanol, dimethylformamide (DMF) and N-methyl pyrolidone (NMP) as solvents. For each solvent, the 'measures' such as: the partition coefficient (KP), effectiveness factor (Kf) and extractor factor (Ef) are used to select the best/effective solvent and to find the effective heavy gas oil/solvent ratios. A CSTR model is then developed for the process for evaluating viability of the large scale operation. It is noted that while the energy consumption and recovery issues could be ignored for batch experiments these could not be ignored for large scale operation. Large amount of heating is necessary even to carry out the reaction at 30-40 °C, the recovery of which is very important for maximising the profitability of operation and also to minimise environmental impact by reducing net CO2 release. Here the heat integration of the oxidation process is considered to recover most of the external energy input. However, this leads to putting a number of heat exchangers in the oxidation process requiring capital investment. Optimisation problem is formulated using gPROMS modelling tool to optimise some of the design and operating parameters (such as reaction temperature, residence time and splitter ratio) of integrated process while minimising an objective function which is a coupled function of capital and operating costs involving design and operating parameters. Two cases are studied: where (i) HGO and catalyst are fed as one feed stream and (ii) HGO and catalyst are treated as two feed streams. A liquid-liquid extraction model is then developed for the extraction of sulphur compounds from the oxidised heavy gas oil. With the experimentally determined KP multi stage liquid-liquid extraction process is modelled using gPROMS software and the process is simulated for three different solvents at different oil/solvent ratios to select the best solvent, and to obtain the best heavy gas oil to solvent ratio and number of extraction stages to reduce the sulphur content to less than 10 ppm. Finally, an integrated oxidation and extraction steps of ODS process is developed based on the batch experiments and modelling. The recovery of oxidant, catalyst and solvent are considered and preliminary economic analysis for the integrated ODS process is presented.

The separation of aqueous and organic mixtures with thermal separation processes is an important and challenging task in the chemical industry. Rising prices for energy, stricter environmental regulations and the increasing demand for high purity chemicals are the main driving forces to find alternative solutions to common separation technologies such as distillation and absorption. These are mostly too energy consumptive and can show limited separation performance, especially when applied to close boiling or azeotropic mixtures. Pervaporation can overcome these thermodynamic limitations and requires less energy because only the separated components need to be evaporated. This separation technology is already well established for the production of anhydrous solvents, but not yet widely distributed in the chemical and petrochemical industry due to some crucial challenges, which are still to overcome. Besides the need of high selective membranes, the development of membrane modules adapted to the specific requirements of organoselective pervaporation needs more research effort. Furthermore, only few modelling and simulation tools are available, which hinders the distribution of this process in industrial scale. In this work, these issues are addressed in a combined approach. In close collaboration with our cooperation partners, a novel membrane module for organophilic pervaporation is developed. A novel technology to manufacture high selective polymeric pervaporation membranes is applied to produce a membrane for an industrially relevant organic-organic separation task. A three step modelling approach ranging from a shortcut and a discrete to a rigorous model is developed and implemented in a user interface. A hydrophilic and an organophilic membrane are characterised for the separation of a 2-butanol/water mixture in a wide range of feed temperature and feed concentration in order to establish a generally valid description of the membrane performances. This approach is implemented in the three developed models to simulate the novel membrane module in industrial scale. The simulations are compared to the results of pilot scale experiments conducted with the novel membrane module. Good agreement between simulated and experimental values is reached.

Pressure swing adsorption (PSA) is a widely applied technology for separating gases, which operates based on selective adsorption on solid adsorbents. Indeed, the demand of PSA process plants for nitrogen production on industrial scale is continuously growing, as consequence of the improvements achieved in terms of efficiency, competitiveness, and cost-effectiveness. In this work, the N2-PSA pilot plant located at the Münster University of Applied Sciences, was used as study-case for the drafting of the industrial-scale basic design package of the plant. Firstly, it was shown that it is acceptable to develop the basic design package of full-scale PSA system based on information obtained by operation of pilot-scale system. Subsequently, a detailed description of technical data of plant components has been given, according to the international and European standards in force. Therefore, it was possible to produce technical drawings of the plant, i.e. process flow diagram (PFD) and piping and instrumentation diagram (P&ID), along with the required datasheets and a preliminary plant layout. Eventually, a preliminary safety assessment of the system was carried out.

Catalytic hydrotreating (HDT) is a mature process technology practiced in the petroleum refining industries to treat oil fractions for the removal of impurities (such as sulfur, nitrogen, metals, asphaltene). Hydrotreating of whole crude oil is a new technology and is regarded as one of the more difficult tasks that have not been reported widely in the literature. In order to obtain useful models for the HDT process that can be confidently applied to reactor design, operation and control, the accurate estimation of kinetic parameters of the relevant reaction scheme are required. This thesis aims to develop a crude oil hydrotreating process (based on hydrotreating of whole crude oil followed by distillation) with high efficiency, selectivity and minimum energy consumption via pilot plant experiments, mathematical modelling and optimization. To estimate the kinetic parameters and to validate the kinetic models under different operating conditions, a set of experiments were carried out in a continuous flow isothermal trickle bed reactor using crude oil as a feedstock and commercial cobaltmolybdenum on alumina (Co-Mo/¿-Al2O3) as a catalyst. The reactor temperature was varied from 335°C to 400°C, the hydrogen pressure from 4 to10 MPa and the liquid hourly space velocity (LHSV) from 0.5 to 1.5 hr-1, keeping constant hydrogen to oil ratio (H2/Oil) at 250 L/L. The main hydrotreating reactions were hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodeasphaltenization (HDAs) and hydrodemetallization (HDM) that includes hydrodevanadization (HDV) and hydrodenickelation (HDNi). An optimization technique is used to evaluate the best kinetic models of a trickle-bed reactor (TBR) process utilized for HDS, HDAs, HDN, HDV and HDNi of crude oil based on pilot plant experiments. The minimization of the sum of the squared errors (SSE) between the experimental and estimated concentrations of sulfur (S), nitrogen (N), asphaltene (Asph), vanadium (V) and nickel (Ni) compounds in the products, is used as an objective function in the optimization problem using two approaches (linear (LN) and non-linear (NLN) regression). The growing demand for high-quality middle distillates is increasing worldwide whereas the demand for low-value oil products, such as heavy oils and residues, is decreasing. Thus, maximizing the production of more liquid distillates of very high quality is of immediate interest to refiners. At the same time, environmental legislation has led to more strict specifications of petroleum derivatives. Crude oil hydrotreatment enhances the productivity of distillate fractions due to chemical reactions. The hydrotreated crude oil was distilled into the following fractions (using distillation pilot plant unit): light naphtha (L.N), heavy naphtha (H.N), heavy kerosene (H.K), light gas oil (L.G.O) and reduced crude residue (R.C.R) in order to compare the yield of these fractions produced by distillation after the HDT process with those produced by conventional methods (i.e. HDT of each fraction separately after the distillation). The yield of middle distillate showed greater yield compared to the middle distillate produced by conventional methods in addition to improve the properties of R.C.R. Kinetic models that enhance oil distillates productivity are also proposed based on the experimental data obtained in a pilot plant at different operation conditions using the discrete kinetic lumping approach. The kinetic models of crude oil hydrotreating are assumed to include five lumps: gases (G), naphtha (N), heavy kerosene (H.K), light gas oil (L.G.O) and reduced crude residue (R.C.R). For all experiments, the sum of the squared errors (SSE) between the experimental product compositions and predicted values of compositions is minimized using optimization technique. The kinetic models developed are then used to describe and analyse the behaviour of an industrial trickle bed reactor (TBR) used for crude oil hydrotreating with the optimal quench system based on experiments in order to evaluate the viability of large-scale processing of crude oil hydrotreating. The optimal distribution of the catalyst bed (in terms of optimal reactor length to diameter) with the best quench position and quench rate are investigated, based upon the total annual cost. The energy consumption is very important for reducing environmental impact and maximizing the profitability of operation. Since high temperatures are employed in hydrotreating (HDT) processes, hot effluents can be used to heat other cold process streams. It is noticed that the energy consumption and recovery issues may be ignored for pilot plant experiments while these energies could not be ignored for large scale operations. Here, the heat integration of the HDT process during hydrotreating of crude oil in trickle bed reactor is addressed in order to recover most of the external energy. Experimental information obtained from a pilot scale, kinetics and reactor modelling tools, and commercial process data, are employed for the heat integration process model. The optimization problem is formulated to optimize some of the design and operating parameters of integrated process, and minimizing the overall annual cost is used as an objective function. The economic analysis of the continuous whole industrial refining process that involves the developed hydrotreating (integrated hydrotreating process) unit with the other complementary units (until the units that used to produce middle distillate fractions) is also presented. In all cases considered in this study, the gPROMS (general PROcess Modelling System) package has been used for modelling, simulation and parameter estimation via optimization process.
Tikrit University, Iraq

The topic of this thesis is carbon dioxide (CO2) capture and storage (CCS), which is a technology that is currently being promoted by industries, scientists and governments, among others, in order to mitigate climate change despite a continued use of fossil fuels. Because of the complex nature of CCS and the risks it entails, it is controversial. The aim of this thesis is to analyse how the technology may be further developed in a responsible manner. In the first part of the thesis different methods for capturing CO2 from industrial processes as well as power plants are analysed. The aim is to identify early opportunities for CO2 capture, which is considered important because of the urgency of the climate change problem. Three potential early opportunities are studied: i) capturing CO2 from calcining processes such as cement industries by using the oxyfuel process, ii) capturing CO2 from pressurised flue gas, and iii) capturing CO2 from hybrid combined cycles. Each opportunity has properties that may make them competitive in comparison to the more common alternatives if CCS is realised. However, there are also drawbacks. For example, while capturing CO2 from pressurised flue gas enables the use of more compact capture plant designs as well as less expensive and less toxic absorbents, the concept is neither suitable for retrofitting nor has it been promoted by the large and influential corporations. The second part of the thesis has a broader scope than the first and is multidisciplinary in its nature with inspiration from the research field of Science and Technology Studies (STS). The approach is to critically analyse stakeholder percep-tions regarding CCS, with a specific focus on the CCS experts. The thesis sheds new light on the complexity and scientific uncertainty of CCS as well as on the optimism among many of its proponents. Because of the uncertain development when it comes to climate change, fossil fuel use and greenhouse gas emissions, the conclusion is that CCS has to be further developed and demonstrated. A responsible strategy for a future development of CCS would benefit from: i) a search for win-win strategies, ii) increasing use of appropriate analytical tools such as life-cycle analysis, iii) a consideration of fossil fuel scarcity and increasing price volatility, iv) funding of unbiased research and v) increasing simultaneous investments in long-term solutions such as renewable energy alternatives and efficiency improvements.
QC 20100727