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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Production of biosurfactant by fermentation with integral foam fractionation

Winterburn, James January 2011 (has links)
Biosurfactants are naturally occurring amphiphiles with potential for use as alternatives to traditional petrochemical and oleochemical surfactants. The unique properties of biosurfactants, including their biodegradability and tolerance of a wide range of temperature and pH, make their use in a range of novel applications attractive. Currently the wider ultilisation of biosurfactants is hindered by a lack of economically viable production routes, with downstream processing presenting a significant challenge. This thesis presents an investigation into the production of HFBII, a hydrophobin protein, using an adsorptive bubble separation technique called foam fractionation for in situ recovery of the biosurfactant. The effects of foaming on the production of HFBII by fermentation were investigated at two different scales. Foaming behaviour was characterised in standard terms of the product enrichment and recovery achieved. Additional specific attention was given to the rate at which foam, product and biomass overflowed from the fermentation system in order to assess the utility of foam fractionation for HFBII recovery. HFBII was expressed as an extracellular product during fed batch fermentations with a genetically modified strain of Saccharomyces cerevisiae, which were carried out with and without antifoam. In the presence of antifoam HFBII production is shown to be largely unaffected by process scale, with similar yields of HFBII on dry matter obtained. More variation in HFBII yield was observed between fermentations without antifoam. In fermentations without antifoam a maximum HFBII enrichment in the foam phase of 94.7 was measured with an overall enrichment of 54.6 at a recovery of 98.1%, leaving a residual HFBII concentration of 5.3 mg L-1 in the fermenter. It is also shown that uncontrolled foaming reduced the concentration of biomass in the fermenter vessel, affecting total production. This series of fermentation experiments illustrates the potential for the application of foam fractionation for efficient in situ recovery of HFBII, through simultaneous high enrichment and recovery which are greater than those reported for similar systems. After the suitability of foam fractionation was demonstrated a novel apparatus design was developed for continuously recovering extracellular biosurfactants from fermenters. The design allows for the operating conditions of the foam fractionation process, feed rate and airflow rate, to be chosen independently of the fermentation parameters. Optimal conditions can then be established for each process, such as the aeration rate required to meet the biological oxygen demand of the cell population. The recirculating foam fractionation process was tested on HFBII producing fermentations. It is shown that by using foam fractionation to strip HFBII from fermentation broth in situ the amount of uncontrolled overflowing from the fermenter was greatly reduced from 770.0 g to 44.8 g, compared to fermentations without foam fractionation. Through optimisation of the foam column operating conditions the proportion of dry matter retained in the fermenter was increased from 88% to 95%, in contrast to a dry matter retention of 66% for fermentation without the new design. With the integrated foam fractionation process a HFBII recovery of 70% was achieved at an enrichment of 6.6. This work demonstrates the utility of integrated foam fractionation in minimising uncontrolled foaming in fermenters whilst recovering an enriched product. This integrated production and separation process has the potential to facilitate improved biosurfactant production, currently a major barrier to their wider use.
32

[en] INTEGRATING INTENTIONAL MODELING TO PROCESS MODELING / [pt] INTEGRANDO MODELAGEM INTENCIONAL À MODELAGEM DE PROCESSOS

HENRIQUE PRADO SOUSA 24 July 2012 (has links)
[pt] A modelagem de processos de negócio é utilizada por empresas que desejam documentar detalhes do fluxo de execução de seus processos, resultando em um documento rico em detalhes sobre o negócio. Este artefato também é utilizado pela Engenharia de Software para elicitação de requisitos de sistema. A modelagem intencional possui foco na modelagem de objetivos - definidos como metas e metas flexíveis - e registra as estratégias que podem ser seguidas por um ator de forma a melhor atender suas necessidades, mapeando tarefas e recursos necessários, além disso, também aborda as dependências entre atores. É importante que os modelos de processos de negócio estejam alinhados aos objetivos da organização de forma a prover fonte de informações confiável que gere consequentemente requisitos alinhados ao negócio. Diversas ferramentas estão disponíveis no mercado com o objetivo de apoiar a modelagem dos processos de negócio e dos objetivos organizacionais, entretanto, percebe-se que as soluções disponíveis ainda são incompletas quando se fala na integração de modelos de processos e modelo de objetivos e formas de verificação do alinhamento entre processos e objetivos organizacionais a partir da modelagem. Na arquitetura organizacional, processos de negócio e objetivos são intrinsecamente interdependentes, porém, as linguagens de modelagem atuais não oferecem recursos suficientes para tratar processos e objetivos de forma alinhada, uma vez que existem deficiências na integração entre a camada de modelagem de objetivos e a de processos. Assim, o uso do ferramental disponível que se apoia nessas linguagens e métodos dificulta sobremaneira a tarefa de identificar se os processos utilizados para gerar serviços e produtos, verdadeiramente atingem os objetivos da organização, bem como o impacto que as mudanças nos objetivos causariam nos processos de negócio. Neste trabalho integramos uma linguagem de modelagem de objetivos a uma linguagem de processos de negócio e provemos os elementos e métodos necessários para ampliar a capacidade de análise do alinhamento dos processos de negócio às estratégias organizacionais. / [en] The business processes modeling is used by companies who wish to document details of the execution flow of their processes, resulting in a document rich in details about the business. This artifact is also used by the Software Engineering for system requirements elicitation. The intentional modeling is focused on objectives - defined as goals and softgoals - and registers the strategies that may be followed by an actor in a way to better meet their needs, mapping the tasks and resources needs, in addition, it also addresses the dependencies between actors. It is important that business processes models are aligned to the objectives of the organization in order to provide reliable information source that generates consequently requirements aligned to business. Several tools are available on the market in order to support the business processes and organizational objectives modeling, however, it’s possible to realize that the available solutions are still incomplete when it comes to the integration of process models and goals models and ways to check the alignment between organizational goals and processes using the models. In the organizational architecture, business processes and goals are intrinsically interdependent, however, the current modeling languages treat process and goals in a misaligned way, since there are deficiencies in the integration between the modeling layer of objectives and processes. Thus, the use of the available tools that supports these language and methods greatly complicates the task of identify if the processes used to generate products and services truly achieve the organizational goals as well as the impact of the changes in the goals would cause in business processes. In this paper we integrated a goal modeling language to a business processes modeling language and proved the elements and methods needed to expand the capacity of analysis of the alignment between the business processes and the organizational strategies.
33

A Process Integration Approach to Assessing Possibilities for Improved Material Efficiency in Nordic ore-based Iron- and Steelmaking Systems / En processintegrationsstrategi för bedömning av möjligheter för förbättrad materialeffektivitet i nordiska malmbaserade järn- och ståltillverkningssystem

Lundkvist, Katarina January 2019 (has links)
Iron- and steel production is a material- and energy intensive industrial activity. The production of one tonne of steel commonly results in some 400 kilograms of residual materials such as metallurgical slags, dusts, sludge and scales generated in the processes. Much work is continuously devoted to finding possible ways of using residual materials and minimising landfilled volumes. As these materials often contain considerable amounts of valuable elements such as iron, coal, manganese and calcium, it may be profitable to use them to replace virgin raw materials or to sell them as products that may be useful in other industries and/or processes.    The thesis is based on case studies that exemplify how the use of process integration, through system analysis, can assist in assessing effects and opportunities for different concepts for increased material efficiency in Nordic ore-based steelmaking systems. The process integration approach taken for this research work was the simulation of a specific iron- and steel production system and the use of an optimisation tool for the evaluation of an extended system including the symbiosis between four steel plants.   Three different cases were studied including: system effects of increased magnesium oxide content in the lime raw material, investigation of the prospects for vanadium enrichment and slag reduction concept and a study of the logistics perspective for a joint residual material upgrading and recycling venture between four steel plants. The analysed cases present possibilities to improve the material efficiency by: •      Enhanced recovery of residual materials; •      Upgrading of residual materials to products; •      Specific elements recovery; •      Decreased use of virgin raw material; •      Improved quality of residual materials; •      Decreased amounts of materials placed in long-term storage or landfills.   From the results of the cases studied, the best scenarios and potential gains by enhanced material efficiency is presented. In the case of system effects of increased magnesium oxide content in the lime raw material, the issue was mainly to obtain maximum usage of metallurgical slags without compromising the quality of the main product. The calculated possibility of increased slag recirculation enabled further a decreased consumption of iron ore pellet and limestone. Regarding the investigation of the vanadium enrichment and slag reduction concept, the best scenario markedly increased the internal slag recirculation in order to enrich the vanadium content in the slag for ferrovanadium production. By the vanadium enrichment and recovery concept, considerable amounts of vanadium would be made useful instead of ending up in long-term storage. The study of a shared Nordic concept for residual materials upgrading and use demonstrated the potential for upgrading the materials to a direct reduced iron product for recovery in blast furnace. The concept showed high potential for significantly reducing the amount of material being long-term stored or deposited to landfill and thus a potential step towards achieving the zero-waste philosophy target.   None of the concepts for enhanced material efficiency studied in this thesis work has been implemented; however, they are still of relevance for the Nordic steel industry.
34

便捷的網路購物交易機制之研究

陳逸秉 Unknown Date (has links)
在全球化的競爭下,電子商務日益蓬勃發展的同時,國內外各大企業紛紛投入各類型之網路交易的建置,但如何營造一個讓使用者方便使用且安心參與的環境,是未來網路交易成功的關鍵。 目前的網路購物機制不勝楣舉,但大多是站在企業的角度加以思考,而未思索網路交易的啟動者─網路客戶的需求。雖然,一個完整的網路購物交易需要網路公司、物流業及扮演金流的銀行業者三者共同合作才算完整,但是,消費者希望感受到的不是受到「三個個別的服務」而是「一個完整的服務」,所以在規劃網路交易整體作業的流程設計時,不再只是要吻合內部管理的需要,而且必須以外部客戶的需求為導向,才不會造成網路購物速度的延宕及消費者的抱怨。 本研究首先採取 AHP 研究分析方法,找出影響便捷網路購物交易的顯著因素,並透過對各業界專家的深入訪談來加以驗證後,就目前的網路購物交易機制,加強網路公司、物流公司、銀行之間的資訊流串聯,以加速整體網路交易流程;並導入實體憑證之動態密碼以提高網路交易安全,建構一個方便、安全、即時的 BtoBtoC 網路購物機制,供日後業界及學術界的參考,並讓網路無空間的理想更有實現的可能。 / Under the global competition, while e-commerce grows vigorously day by day. Most of big enterprises build all kinds of internet-shopping platform. But how to build an environment that offers more conveniences to the users? It is the key for the internet-shopping succeeds in the future. So far, there are many types of online transactional modes. These modes stand for the enterprises' inside procedure but the customers' demand. Although an intact trade of internet-shopping needs network company, logistics industry and bank to cooperate together, the consumers hope for 「an intact service」 but a 「three specific services」. That is to say, when we plan an internet transactional procedure, we must put emphasis on the customer' demand rather than the need of inside management, which will accelerate the speed of the internet-shopping and the reduction of the customers' complaint. This research takes AHP method to find out the factors that influence "The convenient internet-shopping mode", and establish the convenient internet-shopping mode, which contact the information flow among the network company, logistics company and bank in order to accelerate the internet transactional speed, and use the One-Time-Password of entity's evidence so as to raise the security of the network trading. After visiting the industry experts to verify this mechanism's practicability, this research will build a more convenient, safer and faster BtoBtoC mode, to let business and academia for reference, and let the ideal without space of the network can be realized.
35

Source and drain engineering in SiGe-based pMOS transistors

Isheden, Christian January 2005 (has links)
A new shallow junction formation process, based on selective silicon etching followed by selective growth of in situ B-doped SiGe, is presented. The approach is advantageous compared to conventional ion implantation followed by thermal activation, because perfectly abrupt, low resistivity junctions of arbitrary depth can be obtained. In B-doped SiGe layers, the active doping concentration can exceed the solid solubility in silicon because of strain compensation. In addition, the compressive strain induced in the Si channel can improve drivability through increased hole mobility. The process is integrated by performing the selective etching and the selective SiGe growth in the same reactor. The main advantage of this is that the delicate gate oxide is preserved. The silicon etching process (based on HCl) is shown to be highly selective over SiO2 and anisotropic, exhibiting the densely packed (100), (311) and (111) surfaces. It was found that the process temperature should be confined between 800 ºC, where etch pits occur, and 1000 ºC, where the masking oxide is attacked. B-doped SiGe layers with a resistivity of 5×10-4 Ωcm were obtained. Well-behaved pMOS transistors are presented, yet with low layer quality. Therefore integration issues related to the epitaxial growth, such as selectivity, loading effect, pile-up and defect generation, were investigated. Surface damage originating from reactive-ion etching of the sidewall spacer and nitride residues from LOCOS formation were found to degrade the quality of the SiGe layer. Various remedies are discussed. Nevertheless, high-quality selective epitaxial growth could not be achieved with a doping concentration in the 1021 cm-3 range. The maximum doping level resulting in a high-quality layer, with the loading effect taken into account, was 6×1020 cm-3. After this careful process optimization, a high-quality layer was obtained in the recessed areas. Finally, Ni mono-germanosilicide was investigated as a material for contact formation to the epitaxial SiGe layers in the recessed source and drain areas. The formation temperature is 550 ºC and it is stable up to 700 ºC. The observation of a recessed step and lateral growth of the silicide led to a detailed treatment of the contact resistivity of the NiSi0.8Ge0.2/Si0.8Ge0.2 interface using 2-D as well as 3-D modeling. Different values were obtained for square shaped and rounded contacts, 5.0x10-8 Ωcm2 and 1.4x10-7 Ωcm2, respectively. / QC 20101028
36

Source and drain engineering in SiGe-based pMOS transistors

Isheden, Christian January 2005 (has links)
<p>A new shallow junction formation process, based on selective silicon etching followed by selective growth of in situ B-doped SiGe, is presented. The approach is advantageous compared to conventional ion implantation followed by thermal activation, because perfectly abrupt, low resistivity junctions of arbitrary depth can be obtained. In B-doped SiGe layers, the active doping concentration can exceed the solid solubility in silicon because of strain compensation. In addition, the compressive strain induced in the Si channel can improve drivability through increased hole mobility. The process is integrated by performing the selective etching and the selective SiGe growth in the same reactor. The main advantage of this is that the delicate gate oxide is preserved. The silicon etching process (based on HCl) is shown to be highly selective over SiO<sub>2</sub> and anisotropic, exhibiting the densely packed (100), (311) and (111) surfaces. It was found that the process temperature should be confined between 800 ºC, where etch pits occur, and 1000 ºC, where the masking oxide is attacked. B-doped SiGe layers with a resistivity of 5×10-<sup>4</sup> Ωcm were obtained. Well-behaved pMOS transistors are presented, yet with low layer quality. Therefore integration issues related to the epitaxial growth, such as selectivity, loading effect, pile-up and defect generation, were investigated. Surface damage originating from reactive-ion etching of the sidewall spacer and nitride residues from LOCOS formation were found to degrade the quality of the SiGe layer. Various remedies are discussed. Nevertheless, high-quality selective epitaxial growth could not be achieved with a doping concentration in the 1021 cm-3 range. The maximum doping level resulting in a high-quality layer, with the loading effect taken into account, was 6×10<sup>20 </sup>cm-<sup>3</sup>. After this careful process optimization, a high-quality layer was obtained in the recessed areas. Finally, Ni mono-germanosilicide was investigated as a material for contact formation to the epitaxial SiGe layers in the recessed source and drain areas. The formation temperature is 550 ºC and it is stable up to 700 ºC. The observation of a recessed step and lateral growth of the silicide led to a detailed treatment of the contact resistivity of the NiSi<sub>0</sub>.<sub>8</sub>Ge<sub>0.2</sub>/Si<sub>0.8</sub>Ge<sub>0.2</sub> interface using 2-D as well as 3-D modeling. Different values were obtained for square shaped and rounded contacts, 5.0x10<sup>-8</sup> Ωcm<sup>2</sup> and 1.4x10<sup>-7</sup> Ωcm<sup>2</sup>, respectively.</p>
37

Analys av en returprocess inom omnihandel : Analysis of a return process in omni channel

Kisch, Jonathan, Lindhagen, Albert January 2018 (has links)
The purpose with the study is to provide a basis for an implementable, improved returns management process. This will help to obtain an empirical result for Lager 157 and to fill any scientific knowledge gap. The study has been divided into two research questions that are of a hierarchical nature. The authors first want to map the return process in order to then make suggestions for improvements using collected data along with collected theory. Method – A single case study has been conducted because the authors are studying a process and want a more in-depth knowledge. The study is carried out on Lager 157, who is active in fashion retailing and has a pronounced strategy for omnichannels, where they use both stores and e-commerce. Because the study only is made on one company, the external validity will be low. But the authors will compare collected theory with the empirics, which will increase the external validity. The literature has been collected through different sources, such as; databases, snowballing and recommendations from teachers and fellow students. The methods for collecting data has been; interviews, observations and document studies. Triangulation of data has ensured that the collected data is correct. Findings – The authors have, together with data and theory, provided a basis on how the study company could improve their returns management. The basis stated is that a web-based return registration should be implemented early in the process but also that the stores should use the same ERP as they do in the e-commerce department. These suggestions are based on that the study company should highlight activities such as gatekeeping and return avoidance, which leads to an improved returns management. Because of these changes, the company can increase their process speed but also improve their process integration and take a step towards fully integrated omni channels. Implications –The study has provided with both empirical and scientific implications. The study company has, from the results, got an overview of their returns management but also been provided with suggestions that can lead to an improved returns management in the future. In the results, the study company can also see which effects these suggestions could have and see how the new returns management could look like compared to have it looked before. During the literature study, the authors found that research connected to omni channels and the focused area were missing. Based on this the authors have created a model which illustrates what the companies should prioritize. Because the study only is made on one single company, the authors thinks that there is room for further research where the model could be evaluated and evolved to fit a greater number of companies. Limitations – Because of a time limit of the study, a single case study was considered to be of high relevance. It gave the authors the opportunity to use different methods to collect data in order to strengthen the results obtained. The external validity would have been higher if an multi case study would have been conducted with a quantitative approach. The interviews where following a semi-structured structure because the authors wanted to gather a large amount of information and leave space for follow-up questions. The observations were unstructured in order to make sure that the observation object where acting naturally. On the other hand, a structured observation would have shown differences and deviations in the activities. The document studies were only used to find out which type of data that the study company did collect. This could have been more extensive in a quantitative focus on the study. / Syfte – Syftet med studien är att ta fram underlag för en implementerbar, förbättrad returprocess. Detta skall bidra till att få fram ett empiriskt resultat åt Lager 157 samt att fylla igen eventuella vetenskapliga kunskapsgap. Studien har delats in i två forskningsfrågor av en hierarkisk karaktär. Författarna vill först kartlägga returprocessen för att i sedan ta fram underlag för förbättringar med hjälp av insamlade data tillsammans med insamlad teori. Metod – En enfallsstudie har genomförts då författarna ämnar studera en process och vill ha en mer djupgående kunskap. Studien är genomförd på Lager 157 som är verksamma inom mode och har en uttalad strategi för omnihandel, där de använder sig av både butiker och e-handel. Då studien enbart är genomförd på ett fallföretag så kommer den externa validiteten vara låg. Däremot ämnar författarna jämföra insamlad teori med empirin, vilket stärker den externa validiteten. Författarna har samlat in litteratur genom olika tillvägagångssätt, såsom; databassökningar, snöbollsmetoden samt rekommendationer ifrån handledare och medstudenter. De metoder som har använts för att samla in data är; intervjuer, observationer och dokumentstudier. Triangulering av data har säkerställt att den insamlade data är korrekt. Resultat – Tillsammans med insamlade data och teori har författarna tagit fram underlag för hur fallföretaget skulle kunna förbättra sin process. Det underlag som tagits fram är dels att en webbaserad returregistrering bör implementeras tidigt i flödet samt att butikerna och e- handeln bör använda sig av samma affärssystem. Detta underlag har sin grund i att fallföretaget bör lyfta fram aktiviteter så som gatekeeping och return avoidance, vilket leder till en förbättrad returprocess. Effekterna anses bidra till att fallföretaget kan öka sin bearbetningshastighet men också förhöja sin processintegration och ta ett steg mot en fullt integrerad omnihandel. Implikationer – Studien har både tagit fram empiriska och vetenskapliga implikationer. Dels har fallföretaget utifrån studiens resultat fått en överblick i hur returprocessen ser ut men också fått ett underlag med åtgärdsförslag som kan leda till en förbättrad returprocess i framtiden. I studiens resultat kan fallföretaget se vilka effekter detta kan mynna ut i men också hur det nya flödet skulle komma att se ut i de båda kanalerna. Då forskning inom omnihandel kopplat till det studerade området ansågs saknas så har författarna tagit fram en modell som illustrerar vad företag bör prioritera. På grund av att studien enbart är genomförd på ett företag anser forskarna att det finns ett tillfälle för vidare forskning, där modellen kan utvärderas och utvecklas för att passa ett större antal företag. Begränsningar – Då författarna har en tidsbegränsning kopplat till arbetet ansåg författarna att en enfallstudie var av högst relevans. Detta gav även möjligheten för författarna att ta användning av olika datainsamlingstekniker för att stärka de resultat som tagits fram. Om en flerfallstudie hade genomförts med mer kvantitativ datainsamling hade det gett en mer överblickande bild, vilket skulle kunna stärka den externa validiteten. De intervjuer som genomfördes följde en semistrukturerad struktur då författarna ämnade att samla in en stor mängd information och där utrymme fanns för följdfrågor. De observationer som genomfördes var ostrukturerade för att säkerställa att observationsobjekten betedde sig naturligt. Däremot hade en strukturerad observation visat på skillnader och avvikelser i aktiviteterna. Dokumentstudierna användes enbart för att säkerställa vilken typ av data som samlades in i dagsläget och kunde ha varit mer omfattande vid en kvantitativ inriktning på studien.
38

Exergetic balances and analysis in a Process Simulator : A way to enhance Process Energy Integration / Approche combinant analyse pinch, analyse exergétique et optimisation pour la minimisation de la consommation énergétique dans des industries de procédés

Ghannadzadeh, Ali 26 November 2013 (has links)
Dans un contexte de réduction des émissions de gaz à effet de serre (GES) et de forte volatilité du prix des énergies, les investissements en efficacité énergétique des sites industriels résultent souvent d'un processus de décision complexe. L'industriel doit pouvoir disposer d'outils lui permettant d'élaborer les solutions d'efficacité énergétique envisageables sur son site. Outre la recherche des sources d'énergie alternatives, que sont les énergies renouvelables, qui n'atteindront leur maturité technologique que sur le long terme, une solution à court terme consiste plutôt à favoriser une utilisation plus rationnelle de l'énergie. Pour relever ce défi, l'analyse exergétique apparaît comme un outil très efficace, car elle permet d'identifier précisément les sources d'inefficacité d'un procédé donné et de proposer des solutions technologiques visant à y remédier. Malheureusement, contrairement au concept d'enthalpie traditionnellement utilisé pour réaliser des bilans énergétiques sur un procédé, ce concept demeure assez difficile à appréhender et n'est que très rarement implémenté dans les simulateurs de procédés. Les travaux présentés dans ce document visent d'abordà rendre l'analyse exergétique plus accessible en l'intégrant dans un simulateur de procédés, puis à démontrer la pertinence d'une telle analyse pour l'amélioration de l'efficacité des procédés et des utilités associées. Dans un premier temps, une formulation générique et indépendante du choix du modèle thermodynamique pour l'évaluation de l'exergie des flux de matière est introduite. Une méthode de calcul des différentes contributions de l'exergie (contributions thermique, mécanique et chimique) est développée et un nouveau concept visant à évaluer les potentiels de récupérations thermique et mécanique maximales est introduit. Par la suite, la notion de bilan exergétique sur un système donné (opération unitaire ou procédé complet) est introduite. Pour l'évaluation des exergies des flux de travail et de chaleur, deux cas de figure sont étudiés : le cas de l'amélioration de procédés existants (« retrofitting ») et le cas de la conception de nouveaux procédés (« design»). Dans le cas de l'amélioration de procédés existants et afin d'aider au diagnostic énergétique de ces systèmes, des tableaux synthétiques proposant des solutions technologiques visant à réduire les irréversibilités ou les pertes exergétiques externes du procédé sont proposés. Par ailleurs, après une analyse comparative des différentes formulations d'efficacité exergétiques existant dans la littérature, la notion d'efficacité intrinsèque est retenue comme le critère le plus adapté pour une optimisation de l'efficacité exergétique d'un procédé complexe. Enfin, une nouvelle méthodologie structurée dédiée à l'analyse exergétique et permettant de pallier les lacunes des méthodologies existantes est présentée. L'ensemble de ces concepts est implémenté dans un premier prototype logiciel écrit en langage VBScript et intégré au simulateur de procédés ProSimPlus. Enfin, l'efficacité de la procédure est démontrée à travers une étude de cas portant sur la production de gaz naturel. / Energy issue is becoming increasingly crucial for industrial sector that consumes large quantities of utilities. Although the scientific world should continue to look for alternate sources of energy, a short-term solution would rather rely on a more rational use of energy. To face this challenge, exergy analysis appears a very efficient tool as it would enable to increase efficiency and reduce environmental impact of industrial processes. Unfortunately, contrary to enthalpy, this concept is rather difficult to handle and exergy analysis is rarely implemented in process simulators. In this context, the major objective of the study presented in this dissertation is to make exergy analysis more understandable by coupling it with the use of a process simulator and also to demonstrate the value of this approach for analysis of energy efficiency of processes and utilities. This dissertation presents a generic formulation for exergy of material streams that does not depend on the thermodynamic model, so that it could be easily implemented in a process simulator. The different contributions of exergy (thermal, mechanical and chemical) have been developed and new concept such as the maximal thermal and mechanical recovery potential has been introduced in order to pave the way for exergy analysis. The formulations of exergy balances on a real process are presented. For that purpose, the formulation of exergy for heat and work flux is developed. The formulation of exergy balances has been introduced for both design and retrofit situations and then a set of hints for the interpretation of this exergy balance has been given. Synthetic tables providing solutions to reduce irreversibilities and external losses have been introduced. Moreover, different kinds of exergy efficiency have been defined to provide a new criterion for the optimization of the process. A new structured methodology for exergy analysis is developed to overcome the limitations of existing methodologies. To make exergy analysis easier for any engineer, a first prototype has been developed to implement the calculation of exergy for the material streams in a process flowsheet modeled in ProSimPlus. Thanks to this prototype, exergy of each material stream appears in a synthesis table next to the traditional thermodynamic values such as the enthalpy. Finally, a case study on Natural Gas Liquids recovery process is presented to demonstrate the benefit of the exergy analysis for the improvement of existing processes. First, the exergy analysis permits to make an energy diagnosis of the process: it pinpoints the inefficiencies of the process which relies not only on irreversibilities but also on external exergy losses. Then, based upon respective values of internal and external losses and also thanks to the breaking down of exergy into it thermal, mechanical and chemical contributions, some technological solutions are suggested to propose a retrofit process. Finally, the exergy efficiency criteria enable to optimize the operating parameters of the process in order to improve its energy efficiency.
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Framställning av syntetiska bio-drivmedel från förgasad biomassa : En studie i potentiell värmeintegration / Production of synthetic biofuels from gasified biomass : A study in process integration

Pogosean, Ararat January 2013 (has links)
Fossila bränslen har sedan de upptäcktes konkurrerat ut biomassa som den huvudsakliga energikällan. Framförallt i trafiksektorn har drivmedel som härstammar från fossil olja varit dominerande. Främst på grund av deras fördelar mot biomassan såsom tillgänglighet, pris, energidensitet och enkelhet att användas i en förbränningsmotor. Men dessa drivmedel innehåller kolatomer som inte längre är en del av det naturliga kretsloppet och vid förbränning leder detta till nettotillskott av koldioxid till atmosfären. Utsläpp av koldioxid utgör den största antropogena inverkan på den accelererande växthuseffekt världen upplever vilket kommer att medföra förödande klimatändringar. Det är mot den bakgrunden nödvändigt att istället framställa drivmedel från en förnybar källa, som innebär en koldioxidneutral förbränning, nämligen biomassa. Samtidigt måste även hänsyn tas till vilken typ av biomassa som används, produktion av biodrivmedel får inte konkurrera med livsmedelproduktion. Därför är det viktigt att ”träaktigt” biomassa används som råvara vilket inte utgör någon konkurrens. Ett lovande sätt att omvandla biomassa till drivmedel är via förgasning där biomassa upphettas tills dess att en gas erhålls, bland annat bestående av kolmonoxid, vätgas, metan och diverse spårämnen. Denna gas genomgår sedan rening och bearbetning där partiklar, tjäror, alkalimetaller och spårämnen renas till dess att gasen endast består av kolmonoxid och vätgas, kallat syntesgas (ofta förkortat som syngas). Syngasen kan sedan i en process omvandlas till en rad olika bränslen, såsom bensin och metan. När gasen renas och bearbetas uppstår stora mängder termisk överskottsenergi. Om anläggningen är fristående kan överskottsenergi inte nyttjas vilket innebär relativ låga verkningsgrader. Men om anläggningen integreras mot till exempel ett massa- och pappersbruk kan överskottsenergi komma väl till pass och på så vis erhålls högre verkningsgrader. I arbetet presenteras en sammanställning av renings- och bearbetningsmetoder. Utifrån denna sammanställning har åtta processlösningar simulerats i processmodellerings-programmet CHEMCAD. De åtta fallen som ingår i studien är för produktion av bensin, diesel, metanol och metan, samtliga med rening vid relativ låga temperaturer (kall gasrening) respektive vid relativ höga temperaturer (het gasrening). Utifrån simuleringsresultateten har det varit möjligt att genomföra en så kallad Pinch-analys där det är möjligt att grafiskt avläsa potential för värmeintegration mot ett typiskt massa- och pappersbruk. Slutligen har en utvärdering av samtliga fall gjorts utifrån olika verkningsgradsberäkningar. Klart står att möjligheterna till värmeintegration är stora, på användbara temperaturnivåer, och uppgår i vissa fall till nästan 40 MW för en 100 MWth–anläggning. Verkningsgraderna är definierade på fyra olika sätt vilket möjliggör djupare tolkning och utvärdering av resultaten men samtidigt kräver det en viss försiktighet från läsaren. Dock framgår det tydligt ur resultaten från verkningsgradsberäkningar att totala effektiviteten för processen kan öka med 10-tals procentenheter om värmeöverskotten tillvaratas.   Resultaten framhåller vikten av värmeintegration och indikerar samtidigt möjligheten till effektivare produktion av bio-drivmedel. Detta innebär med stor sannolikhet också ett ekonomiskt sundare alternativ som i sin tur ökar intresset för investeringar på förnybara bränslen. Investeringar av denna typ är en absolut nödvändighet för en hållbar drivmedelskonsumtion i framtiden. / Fossil fuels have since their discovery replaced biomass as the main source of energy. Especially in the transportation sector, fuels derived from fossil oil have been the dominant source of energy, mainly due to their advantages compared to biomass such as availability, price, energy density and easiness of use in an internal combustion engine. Unfortunately these fuels contain carbon atoms that no longer are part of the natural cycle and combustion leads to net addition of carbon dioxide to the atmosphere. Carbon dioxide has the largest anthropogenic impact on the accelerated greenhouse effect that the world is experiencing, which will lead to devastating climate changes. In this context it is necessary to instead produce fuel from a renewable source, which means a carbon neutral combustion, namely biomass. At the same time it is necessary to also take into account the type of biomass used, the production of biofuels should not compete with food production. Therefore it is important that “woody” biomass is being used as the raw material, which poses no competition. A promising way to convert biomass into fuels is with gasification where biomass is heated until a gas is obtained, mainly consisting of carbon monoxide, hydrogen, methane and various trace elements. This gas then undergoes purification and processing, where particles, tars, alkali metals and trace elements are purged until only a gas consisting of carbon monoxide and hydrogen remains, called syngas (synthesis gas). The syngas can then be converted into a variety of fuels such as petrol and methane. When the gas is being purified and processed large amounts of excess thermal energy are released. If it is a stand-alone plant, excess energy cannot be utilized, which leads to relatively low efficiencies. But if the plant is integrated with, for example, a pulp and paper mill, the excess energy can be utilized, thus resulting in higher overall efficiencies. This work presents a compilation of purification and processing methods. This compilation was used as the basis for the modelling of eight process solutions that were simulated in the flow-sheeting program CHEMCAD. The eight cases included in the study aim to produce gasoline, diesel, methanol and methane, all with purification at relatively low temperatures (cold gas cleaning) or at relative high temperatures (hot gas cleaning). Based on simulation results, a so-called Pinch analysis has been carried out where it is possible to graphically read off the potential for heat integration with a typical pulp and paper mill. Finally, overall assessments of the eight cases have been made based on different efficiency calculations. The results clearly show that the potential for process integration is great, with useful temperature levels, and amounts in up to almost 40 MW when the biomass input is 100 MWth. The efficiencies are defined in four different ways allowing for deeper interpretation and evaluation of the results, but require a certain amount of caution from the reader. However, it is evident from the results of efficiency calculations that overall efficiency of the process can be increased by 10's of percentage points if surplus heat is utilized. The results emphasize the importance of heat integration and simultaneously indicate the possibility of increased efficiency in production of biofuels. Which most likely also means a more economically sound alternative, which in turn increases the interest from investors in renewable fuels. Investments of this type are an absolute necessity for sustainable fuel consumption in the future.
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Globale Collaboration im Kontext mit PLM

Muschiol, Michael, Schulte, Stefan 25 September 2017 (has links) (PDF)
Aus der Einleitung: "Bedingt durch eine geforderte, lokale Präsenz eines global agierenden Unternehmens gegenüber weltweiten Kunden sowie durch global verteiltes Engineering, Produktion und Service sind Unternehmen zunehmend in der Pflicht, sich global zu positionieren. Auch die Verlagerung von Engineeringaufgaben zu externen Zulieferern und Partnern erfordern organisatorische sowie prozesstechnische Maßnahmen, die durch eine entsprechende informationstechnische Unterstützung flankiert werden müssen. Für diese Unterstützung können sogenannte PLM-Systemumgebungen genutzt werden, die sich auf PDM-Systemen abstützen."

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