Today’s carbon constrained world with its increasing demand for cheap energy and a fossil fuel intensive fleet of power producers is making carbon capture and storage (CCS) desirable. Several CCS technologies are under investigation by various research and development groups globally. One of the more promising technologies is oxy-fuel combustion, since it produces a CO2 rich flue gas which requires minor processing to meet storage condition requirements. In this study the economics of an advanced super critical oxy-coal power plant burning lignite, simulated in-house was assessed. A robust and user-friendly financial tool box has been developed with commonly acceptable default parameter settings. Capital, operation and maintenance costs were estimated along with corresponding levelized cost of electricity and CO2 avoidance costs calculated using the detailed financial model developed. A levelized cost of electricity of 131 $/MWhrnet along with a levelized CO2 avoidance cost of 64 $/tonne was estimated for an ASC oxy-coal power plant with CO2 capture. Also a levelized cost of electricity of 83 $/MWhrnet was estimated for an ASC air-fired coal power plant without CO2 capture capabilities as the base plant. The price of electricity was observed to increase from 83 $/MWhrnet to 131 $/MWhrnet translating into a 57% increase. The sensitivity of the overall economics of the process was assessed to several parameters. The overall economics was found sensitive to the choice chemical engineering plant cost index (CEPCI), capacity factor, size of power plant, debt ratio, fuel price, interest rate, and construction duration.

PRESENTATION DES MODELES RELATIFS AUX DIFFERENTS ELEMENTS CONSTITUTIFS DE LA BOUCLE THERMIQUE ET DU MODELE GLOBAL DE CELLE-CI. APPLICATION DE LA METHODE CLASSIQUE DE COMMANDE CLASSIQUE AVEC CRITERE QUADRATIQUE SANS PRENDRE EN COMPTE DE FACON EXPLICITE LES CONTRAINTES. ELABORATION D'UNE COMMANDE UTILISANT "L'ETAT ADJOINT" METTANT A PROFIT CERTAINES PARTICULARITES DU SYSTEME. SIMULATION DES COMMANDES POUR DIFFERENTS ENSOLEILLEMENTS ET DIFFERENTS CHANGEMENTS DE CONSIGNE<br />PRESENTATION OF THE MODELS RELATIVE TO THE VARIOUS ELEMENTS CONSTITUTING THE THERMAL LOOP AND OF THE GLOBAL MODEL OF THE LOOP. APPLICATION OF THE CLASSICAL METHOD OF CONVENTIONAL DRIVE WITH QUADRATIC CRITERION WITHOUT EXPLICITELY TAKING INTO ACCOUNT THE CONSTRAINTS. ELABORATION OF A DRIVE USING THE "ADJOINT STATE" AND TAKING ADVANTAGE OF SOME PECULIARITIES OF THE SYSTEM. SIMULATION OF THE DRIVES FOR VARIOUS DEGREES OF SUNSHINE AND FOR VARIOUS CHANGES IN THE INSTRUCTIONS

Many contemporary grassroots environmental campaigns do not begin in urban areas but in small towns, rural enclaves, and racially or economically disadvantaged communities. Citizens with no previous activist experience or association with the established environmental movement organize to fight industry-created degradation in their communities, such as coal-fired power plants in Texas, the focus of this dissertation. The Texas coal plant opposition movement is identified as sites of environmental justice, particularly as discriminatory practices against sparsely populated communities. The movement’s collaborative efforts are defined as a new category of counterpublic, co-counterpublic, due to the discrete organizations’ shared focus and common purpose. The concept that a growing number of environmental activists are atypical is advanced; atypical environmentalists often engage in environmental practices while rejecting traditional environmentalist language and identity to avoid stigmatization as tree-huggers, extremists, or affluent whites. Presented are rhetorical analyses of identity negotiation and modalities of public enactments of citizenship within the Texas coal plant opposition movement and a critique of plant proponent hegemonic discourses. Research focused on five sites of coal plant opposition in Texas, gathered through ethnographic fieldwork and through a compilation of mediated materials. Asen’s discourse theory of citizenship was used to analyze the data for instances of rhetorical negotiation of environmentalist identity in politically conservative and in ethnically marginalized communities, their localized performances as public citizens, and the collaborative processes between established environmental groups and discrete local organizations. Texas anti-coal activists engaged in what Asen called hybrid citizenship; activists were primarily motivated toward enacted citizenship by a sense of betrayal by authorities. Issue and identity framing theories were implemented to critique rhetorical strategies used by plant proponents. In order to silence the opposition, plant supporters marginalized local anti-coal activists using what Cloud called identity frames by foil; proponents borrowed derogatory rhetorics from well-established anti-environmentalist discourse through which they self-identified positively by framing opponents as Other. The means through which proponents deflected their responsibility to the community by promoting technological solutions to pollution and deferring authority to industry executives and government agencies is analyzed within Chong and Druckman’s competing frames and frames in communication theories. / text

Στο πρώτο κεφάλαιο, γίνεται μία αναφορά στις ανανεώσιμες πηγές ενέργειας και αναλύεται περισσότερο η αιολική. Αναφέρεται η πορεία αξιοποίησής της, και παραθέτονται πληροφορίες για την τωρινή χρήση της στην παραγωγή ηλεκτρικής ενέργειας αλλά και μελλοντικές βλέψεις. Στο δεύτερο κεφάλαιο παρουσιάζονται τα χαρακτηριστικά του ανέμου και οι εξισώσεις της ανεμογεννήτριας που μας επιτρέπουν να απομαστεύουμε ενέργεια από τον άνεμο μέσω των ανεμογεννητριών. Στο τρίτο κεφάλαιο παρουσιάζονται τα δομικά στοιχεία και ο τρόπος με τον οποίο γίνεται η κατηγοριοποίηση των ανεμογεννητριών, οι έλεγχοι που χρησιμοποιούνται και τα είδη των ανεμογεννητριών που χρησιμοποιούνται σήμερα στη βιομηχανία. Στο τέταρτο κεφάλαιο παρουσιάζονται οι τεχνικές απαιτήσεις για τους αιολικούς σταθμούς στο ελληνικό Σ.Η.Ε. Στο πέμπτο κεφάλαιο, γίνεται η προσομοίωση μέσω του προγράμματος Matlab - Simulink ενός μη γραμμικού ελέγχου ισχύος ανεμογεννητριών DFIG για ενσωμάτωση σε εικονικούς σταθμού ισχύος (V.P.P). / In the first chapter, there is a general description about renewable energy resources and more specific, about the wind energy. We present the current worldwide electrical power production and the future requirements for electrical power production in Europe and Greece. In the second chapter, we study the features of the wind performance and the equations that allows us to drain energy from the wind ,using a wind turbine. The third chapter presents the components, the kinds of control and the categories of wind turbines that are in use in industry nowadays. The fourth chapter presents the technical requirements for the wind farms in the Greek System of Electrical Energy. In the fifth chapter we use the program Matlab - Simulink in order to simulate a non-linear direct power control of DFIG wind turbines for Virtual Power Plant (V.P.P.) integration.

No description available.

Today???s carbon constrained world with its increasing demand for cheap energy and a fossil fuel intensive fleet of power producers is making carbon capture and storage (CCS) desirable. Several CCS technologies are under investigation by various research and development groups globally. One of the more promising technologies is oxy-fuel combustion, since it produces a CO2 rich flue gas which requires minor processing to meet storage condition requirements. In this study the economics of an advanced super critical oxy-coal power plant burning lignite, simulated in-house was assessed. A robust and user-friendly financial tool box has been developed with commonly acceptable default parameter settings. Capital, operation and maintenance costs were estimated along with corresponding levelized cost of electricity and CO2 avoidance costs calculated using the detailed financial model developed. A levelized cost of electricity of 131 $/MWhrnet along with a levelized CO2 avoidance cost of 64 $/tonne was estimated for an ASC oxy-coal power plant with CO2 capture. Also a levelized cost of electricity of 83 $/MWhrnet was estimated for an ASC air-fired coal power plant without CO2 capture capabilities as the base plant. The price of electricity was observed to increase from 83 $/MWhrnet to 131 $/MWhrnet translating into a 57% increase. The sensitivity of the overall economics of the process was assessed to several parameters. The overall economics was found sensitive to the choice chemical engineering plant cost index (CEPCI), capacity factor, size of power plant, debt ratio, fuel price, interest rate, and construction duration.

Solar energy is a virtually inexhaustible energy resource, and thus, has great potential in helping meet many of our future energy requirements. Current technology used for solar energy conversion, however, is not cost effective. In addition, solar thermal power systems are also generally less efficient as compared to fossil fuel based thermal power plants. There is a large variety of systems for solar thermal power generation, each with certain advantages and disadvantages. A distinct advantage of solar thermal power generation systems is that they can be easily integrated with a storage system and/or with an auxiliary heating system (as in hybrid power systems) to provide stable and reliable power. Also, as the power block of a solar thermal plant resembles that of a conventional thermal power plant, most of the equipment and technology used is already well defined, and hence does not require major break through research for effective utilisation. Manufacturing of components, too, can be easily indigenized. A solar collector field is generally used for solar thermal energy conversion. The field converts high grade radiation energy to low grade heat energy, which will inevitably involve energy losses as per the laws of thermodynamics. The 2nd law of thermodynamics requires that a certain amount of heat energy cannot be utilised and has to be rejected as waste heat. This limits the efficiency of solar thermal energy technology. However, in many situations, the waste heat can be effectively utilized to perform refrigeration and desalination using absorption or solid sorption systems, with technologies popularly known as “polygeneration”. There is extensive research done in the area of solar collectors, including but not limiting to thermal analysis, testing of solar collectors, and economic analysis of solar collectors. Exergy and optimization analyses have also been done for certain solar collector configurations. Research on solar thermal power plants includes energy analysis at system level with certain configurations. Research containing analysis with insolation varying throughout the day is limited. Hence, there is scope for analysis incorporating diurnal variation of insolation for a solar thermal power system. This thesis centres on the thermodynamic analysis at system level of a solar thermal power system using a concentrating solar collector field and a simple Rankine cycle power generation (with steam as the working fluid) for Indian conditions. The aim is to develop a tool for thermodynamic analysis of solar thermal power systems, with a generalised approach that can also be used with different solar collector types, different heat transfer fluids in the primary loop, and also different working fluids in the secondary loop. This analysis emphasises the solar collector field and a basic sensible heat storage system, and investigates the various energy and exergy losses present. Comparisons have been made with and without a storage unit and resulting performance issues of solar thermal power plants have been studied. Differences between the system under consideration and commercially used thermal power plants have also been discussed, which brought out certain limitations of the technology currently in use. A solution from an optimization analysis has been utilized and modified for maximization of exergy generated at collector field. The analysis has been done with models incorporating equations using the laws of thermodynamics. MATLAB has been used to program and simulate the models. Solar radiation data used is from NREL’s Indian Solar Resource Data, which is obtained using their SUNY model by interpreting satellite imagery. The performance of the system has been analysed for Bangalore for four different days with different daylight durations, each day having certain differences in the incident solar radiation or insolation received. A particular solution of an optimization analysis has been modified using the simulation model developed and analysed with the objective of maximization of exergy generated at collector field. It has been found that the performance of the solar thermal power system was largely dependent on the variation of incident solar radiation. The storage system provided a stableperformance for short duration interruptions of solar radiation occurred on Autumn Equinox (23-09-2002).The duration of the interruption was within the limits of storage unit capacity. The major disruption in insolation transpired on Summer Solstice (21-06-2002) caused a significantly large drop in the solar thermal system performance; practically the system ceased to function due to lack of energy resource. Hence, the use of an auxiliary heating system hasbeen considered desirable. The absence of a storage unit has been shown to cause a significant loss in gross performance of the power system. The Rankine cycle turbine had many issues coping with a highly fluctuating energy input, and thus caused efficiency losses and even ceased power generation. A storage unit has been found to be ideal for steady power generation purposes. Some commercial configurations may lack a storage system, but they have been compensated by the auxiliary heating system to ensure stable power generation. The optimization of the solar collector determines that optimal collector temperatures vary in accordance to the incident solar radiation. Hence, the collector fluid outlet temperature must not be fixed so as to handle varying insolation for optimal exergy extraction. The optimal temperatures determined for Bangalore are around 576 K which is close to the values obtained by the simulation of the solar thermal power system. The tools for analysis and simulation of solar thermal power plants developed in this thesis is fairly generalised, as it can be adapted for various types of solar collectors and for different working fluids (other than steam), such as for Organic Rankine Cycle (ORC). The model can also be easily extended to other types of power cycles such as Brayton and Stirling cycles.

In der Dissertation werden die während der Mahltrocknung von Rohbraunkohle ablaufenden Teilprozesse systematisch analysiert und allgemein gültigen Funktionen für den Stoffumsatz zugeordnet. Es entsteht eine Kenntnisstandmatrix, die ausgewählte Literaturstellen einordnet und unbearbeitete Forschungsfelder offenlegt. Diesbezüglich werden Untersuchungen zum Bewegungsverhalten der Kohle beim Eintritt in das Schlagrad angestellt. Anhand eines neuen Berechnungsmodells und experimenteller Fallversuche lassen sich u.a. Aussagen zur konstruktiven Ausführung der Mühlentür treffen. Weiterhin wird in der Arbeit untersucht, welchen Einfluss Partikelgröße, -dichte und -form der Kohlebestandteile Berge, Xylite und Kohlenstaub auf den Sichtprozess haben. Zur Darstellung der berechneten Trennfunktionen T(vs) dient die stationäre Sinkgeschwindigkeit vs als Trennmerkmal. Abschließend folgt ein Ergebnisvergleich mit Messwerten an einem Modellversuchsstand und an realen Mahltrocknungsanlagen im Kraftwerk.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-01T13:36:45Z No. of bitstreams: 1 DALTON CÉZANE GOMES VALADARES - DISSERTAÇÃO PPGCC 2015..pdf: 6500440 bytes, checksum: f8b244a64bf81646d322b68023c204d9 (MD5) / Made available in DSpace on 2018-05-01T13:36:45Z (GMT). No. of bitstreams: 1 DALTON CÉZANE GOMES VALADARES - DISSERTAÇÃO PPGCC 2015..pdf: 6500440 bytes, checksum: f8b244a64bf81646d322b68023c204d9 (MD5) Previous issue date: 2015-07 / No âmbito industrial, é sabido que as redes sem fio são as mais indicadas, já que possuem baixo custo de implantação, maior flexibilidade e são menos invasivas ao ambiente. Na literatura, dentre as tecnologias de rede sem fio aplicadas em ambientes industriais, pouco destaque é dado às tradicionais 802.11a/b/g, conhecidas pelo uso doméstico e chamadas WiFi (acrônimo de Wireless Fidelity). A pesquisa, ora descrita, tem como objetivo avaliar o desempenho de uma rede 802.11g em um ambiente industrial de uma usina termoelétrica (UTE). O cenário de análise foi constituído de 4 enlaces de comunicação, com o principal deles possuindo uma distância de, aproximadamente, 150 metros. Para a avaliação do desempenho da rede, foram consideradas três métricas: taxa de perda de pacotes, Taxa de Transferência e tempo de resposta. Os testes foram realizados por meio do estabelecimento de comunicação entre pontos dentro da sala de motores (primeiro enlace) e o servidor localizado na sala de administração (último enlace). Os resultados obtidos para potência do sinal foram comparados aos valores estimados por meio do modelo Log Distance Path Loss. Observou-se que o desempenho da comunicação realizada pela rede não sofreu degradação significativa, mesmo em um ambiente sujeito à interferência eletromagnética e demais características intrínsecas a uma UTE. Após a análise concluída, verificou-se a viabilidade do uso da tecnologia 802.11g para comunicação de dados em ambientes com características similares às de uma usina termoelétrica. / In industry, it is known that wireless networks are the most suitable, since they have low implementation cost, greater flexibility and are less invasive to the environment. In the literature, among the wireless network technologies applied in industrial environments, little attention is given to traditional 802.11a/b/g, known by the domestic use and by the acronym WiFi (Wireless Fidelity). This work aims to evaluate the performance of an 802.11g network in an industrial environment of a thermal power plant. The scenario consists of four communication links, with the main one having a distance of approximately 150m. For the evaluation of network performance, we considered three metrics: packet loss rate, bandwidth and response time. Tests were carried out through the establishment of communication between points within the engine square (first link) and the server located in the boardroom (last link). The obtained results for the signal strength at each point were compared with the estimated values by the Log Distance Path Loss Model. It was verified that the performance of the communication performed by the network did not suffer significant degradation, even being in an environment subject to considerable electromagnetic interference. After the concluded analysis, it was found feasibility of using 802.11g technology for data communication in environments with characteristics similar to those of a thermal power plant.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-01T14:25:43Z No. of bitstreams: 1 ADALBERTO GOMES TEIXEIRA JÚNIOR - DISSERTAÇÃO PPGCC 2015..pdf: 2611686 bytes, checksum: 6b9c4a2efc3946611ad0263328434bd1 (MD5) / Made available in DSpace on 2018-05-01T14:25:43Z (GMT). No. of bitstreams: 1 ADALBERTO GOMES TEIXEIRA JÚNIOR - DISSERTAÇÃO PPGCC 2015..pdf: 2611686 bytes, checksum: 6b9c4a2efc3946611ad0263328434bd1 (MD5) Previous issue date: 2015-07 / Capes / O som gerado por motores em funcionamento contém informações sobre seu estado e condições, tornando-se uma fonte importante para a avaliação de seu funcionamento sem a necessidade de intervenção no equipamento. A análise do estado do equipamento muitas vezes é realizada por diagnóstico humano, a partir da experiência vivenciada no ambiente ruidoso de operação. Como o funcionamento dos motores é regido por um processo periódico, o sinal de áudio gerado segue um padrão bem definido, possibilitando, assim, a avaliação de seu estado de funcionamento por meio desse sinal. Dentro deste contexto, a pesquisa ora descrita trata da modelagem do sinal acústico gerado por motores em usinas termoelétricas, aplicando técnicas de processamento digital de sinais e inteligência artificial, com o intuito de auxiliar o diagnóstico de falhas, minimizando a presença humana no ambiente de uma sala de motores. A técnica utilizada baseia-se no estudo do funcionamento dos equipamentos e dos sinais acústicos por eles gerados por esses, para a extração de características representativas do sinal, em diferentes domínios, combinadas a métodos de aprendizagem de máquinas para a construção de um multiclassificador, responsável pela avaliação do estado de funcionamento desses motores. Para a avaliação da eficácia do método proposto, foram utilizados sinais extraídos de motores da Usina Termoelétrica Borborema Energética S.A., no âmbito do projeto REPARAI (REPair over AiR using Artificial Intelligence, código ANEEL PD6471-0002/2012). Ao final do estudo, o método proposto demonstrou acurácia próxima a 100%. A abordagem proposta caracterizou-se, portanto, como eficiente para o diagnóstico de falhas, principalmente por não ser um método invasivo, não exigindo, portanto, o contato direto do avaliador humano com o motor em funcionamento. / The sound generated by an engine during operation contains information about its conditions, becoming an important source of information to evaluate its status without requiring intervention in equipment. The fault diagnosis of the engine usually is performed by a human, based on his experience in a noisy environment. As the operation of the engine is a periodic procedure, the generated signal follows a well-defined pattern, allowing the evaluation of its operating conditions. On this context, this research deals with modeling the acoustic signal generated by engines in power plants, using techniques from digital signal processing and artificial intelligence, with the purpose of assisting the fault diagnosis, minimizing the human presence at the engine room. The technique applied is based on the study of engines operation and the acoustic signal generated by them, extracting signal representative characteristics in different domains, combined with machine learning methods, to build a multiclassifier to evaluate the engines status. Signals extracted from engines of Borborema Energética S.A. power plant, during the REPARAI Project (REPair over AiR using Artificial Intelligence), ANEEL PD-6471-0002/2012, were used in the experiments. In this research, the method proposed has demonstrated an accuracy rate of nearly 100%. The approach has proved itself to be efficient to fault diagnosis, mainly by not being an invasive method and not requiring human direct contact with the engine.