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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.
21

Integrating biomass gasification with electric arc furnace steel making / Integrering av biomassaförgasning med ljusbågsugn

Andersson, Filippa January 2023 (has links)
Utsläppen av växthusgaser ökar över hela världen och nya tekniker används för att minska utsläppen. 7% av utsläppen kommer från stålsektorn. 25% av världens stålproduktion görs via återvinningstekniken ljusbågsugn. Genom återvinningsprocessen släpps det ut 500kg CO2 per ton producerat flytande stål. En möjlighet att sänka dessa direkta utsläppär att koppla ljusbågsugnsprocessen med biomassa förgasnings och koldioxidavskiljning. Den föreslagna lösningen i denna avhandling är att utnyttja avgaserna från stålsmältningen i förgasningsprocessen och skapa värdefulla produkter. Projektet utvärderar den tekniska genomförbarheten i form av energieffektivitet och kolutnyttjande. Den föreslagna processen simulerades med Aspen Plus. Ett problem med ljusbågsugnens avgaser är fluktuationen i sammansättningen. Tre fall avavgassammansättning undersöktes. Fall 1 var den genomsnittliga avgassammansättningen, medan fall 2 och 3 var extrema med högt CO- respektive CO2-innehåll. Resultatet visade att syntetsgassammansättningen starkt beror på förgasningsmedlet. I samtliga fall ökade energieffektiviteten och de direkta utsläppen minskade, jämfört med nuvarande process. Fall 1 visade generellt högst effektivitet och kolutnyttjande, medan det CO2 rika fallet (fall 3) hade lägst. Ett kontinuerligt flöde av förgasningsmedel krävs för att driva förgasningsprocessen. Eftersom ljusbågsugn är en satsvis process, sker luftförgasning när avgaser inte är tillgängliga. Det önskade resultatet av luftförgasning är att producera syntetsgas som liknar avgasförgasningens syntesgas. Resultaten visade att luftinfiltration i avgaser är gynnsamt för mer liknande syntesgas . / Greenhouse gas emissions are increasing worldwide, and new techniques are being adopted to suppress the emissions. The steel sector is responsible for 7% of the emissions. 25% ofthe world’s steel production is made through the recycling technique EAF. Throughout the recycling process, 500 kg CO2 gets emitted per ton of liquid steel produced. An opportunity to lower these direct emissions is to couple the EAF process to biomass gasification and CO2 utilisation process. The proposed solution in this thesis is to utilise the off-gases in the gasification process and create high-valuable products. The project evaluates the technical feasibility via energy efficiency and carbon utilisation. The proposed process was simulated using Aspen Plus. A problem with the off-gases from EAF gasification is the fluctuation in composition. Three cases of off-gas composition were therefore investigated. Case 1 was the average off-gas composition, while cases 2 and 3 were extreme with high CO and CO2 content, respectively. The result showed that the syngas composition strongly depends on the gasifying agent. In all cases, the energy efficiency increased, and the direct emissions decreased. Case 1 generally showed the highest efficiency and carbon utilisation, while the CO2 heavily case (case 3) had the lowest. A continuous flow of gasifying agents is required to run the gasification process. Since EAF is a batch process, air gasification runs when off-gases are unavailable. The desired outcome of air gasification is to produce syngas similar to off-gas gasification. The results showed that air infiltration in off-gases is favourable for more similar syngas composition.
22

Process Window Challenges in Advanced Manufacturing: New Materials and Integration Solutions

Fox, Robert, Augur, Rod, Child, Craig, Zaleski, Mark 22 July 2016 (has links) (PDF)
With the continued progression of Moore’s law into the sub-14nm technology nodes, interconnect RC and power dissipation scaling play an increasingly important role in overall product performance. As critical dimensions in the mainstream Cu/ULK interconnect system shrink below 30nm, corresponding increases in relative process variation and decreases in overall process window mandate increasingly complex integrated solutions. Traditional metallization processes, e.g. PVD barrier and seed layers, no longer scale for all layout configurations as they reach physical and geometric limitations. Interactions between design, OPC, and patterning also play more and more critical roles with respect to reliability and yield in volume manufacturing; stated simply, scaling is no longer “business as usual”. Restricted design layouts, prescriptive design rules, novel materials, and holistic integration solutions each therefore become necessary to maximize available process windows, thus enabling new generations of cost-competitive products in the marketplace.
23

CO<sub>2</sub> Capture With MEA: Integrating the Absorption Process and Steam Cycle of an Existing Coal-Fired Power Plant

Alie, Colin January 2004 (has links)
In Canada, coal-fired power plants are the largest anthropogenic point sources of atmospheric CO<sub>2</sub>. The most promising near-term strategy for mitigating CO<sub>2</sub> emissions from these facilities is the post-combustion capture of CO<sub>2</sub> using MEA (monoethanolamine) with subsequent geologic sequestration. While MEA absorption of CO<sub>2</sub> from coal-derived flue gases on the scale proposed above is technologically feasible, MEA absorption is an energy intensive process and especially requires large quantities of low-pressure steam. It is the magnitude of the cost of providing this supplemental energy that is currently inhibiting the deployment of CO<sub>2</sub> capture with MEA absorption as means of combatting global warming. The steam cycle of a power plant ejects large quantities of low-quality heat to the surroundings. Traditionally, this waste has had no economic value. However, at different times and in different places, it has been recognized that the diversion of lower quality streams could be beneficial, for example, as an energy carrier for district heating systems. In a similar vein, using the waste heat from the power plant steam cycle to satisfy the heat requirements of a proposed CO<sub>2</sub> capture plant would reduce the required outlay for supplemental utilities; the economic barrier to MEA absorption could be removed. In this thesis, state-of-the-art process simulation tools are used to model coal combustion, steam cycle, and MEA absorption processes. These disparate models are then combined to create a model of a coal-fired power plant with integrated CO<sub>2</sub> capture. A sensitivity analysis on the integrated model is performed to ascertain the process variables which most strongly influence the CO<sub>2</sub> energy penalty. From the simulation results with this integrated model, it is clear that there is a substantial thermodynamic advantage to diverting low-pressure steam from the steam cycle for use in the CO<sub>2</sub> capture plant. During the course of the investigation, methodologies for using Aspen Plus?? to predict column pressure profiles and for converging the MEA absorption process flowsheet were developed and are herein presented.
24

[en] IT STRATEGIES FOR THE ELECTRONIC INTEGRATION OF INFORMATION: A STUDY OF THE STATE OF THE ART AND THE PRACTICE / [pt] ESTRATÉGIAS DE TI PARA A INTEGRAÇÃO ELETRÔNICA DA INFORMAÇÃO: UM ESTUDO SOBRE O ESTADO DA ARTE E DA PRÁTICA

DANIEL VALENTE SERMAN 03 March 2008 (has links)
[pt] A informação passou a ser vista ao longo do tempo como um insumo importante para a tomada de decisão e para a obtenção de vantagens competitivas pelas empresas. A tecnologia passou a fazer parte do cotidiano das empresas para melhor administrá-la e disseminá-la. Entretanto, nem sempre as organizações adotaram esse caminho de forma planejada. Percebe-se uma confusão no uso de conceitos e de soluções em TI, que se estende para o tema da integração eletrônica da informação. O trabalho consistiu em uma revisão da literatura sobre a integração de sistemas e de dados, verificando-se os conceitos mais comuns, as soluções mais utilizadas e as promessas encontradas. Além disso, realizou-se uma pesquisa de campo, na qual gestores expuseram em entrevistas qualitativas o que acontece na prática sobre o assunto, aludindo a benefícios, problemas e requisitos para o desenvolvimento e adoção de soluções de integração. / [en] Organizations began to see information like an important component for decision making and obtaining above average profits, when well used. Computational tools and communication technologies became common on the quotidian of these organizations. However, those tools and technologies weren`t always adopted through the right way. We notice confusion on the use of concepts and the adoption of solutions on IT and that problem extends to information integration. This work consisted on an intense review of the literature about systems and data integration, verifying most common concepts, most utilized solutions and promises about them. Besides, a field research was realized, which manages showed on qualitative interviews what actually happens about this subject, referring to benefits, problems and requisites for the development and adoption of integration solutions.
25

Integrating hydroprocessors in refinery hydrogen network optimization

Umana, Blessing January 2016 (has links)
Effective distribution of hydrogen in refinery hydrogen networks is a major concern for refiners tackling the stringent specifications on maximum sulphur levels in middle distillates and the increasing global demand of diesel fuel. A major challenge is the implementation of a shift from conventional to ultra-deep methods of desulphurisation. Meanwhile, the capacity of secondary conversion processes such as fluid catalytic cracking (FCC) and hydrocracking in refineries has steadily increased in converting the bottom of the barrel into high-value lighter products resulting in increased levels of hydroprocessing, which exerts a higher demand on refinery hydrogen systems. Previous methodologies on hydrogen network optimization have been developed mainly based on the assumption of fixed hydroprocessing performance with constant hydrogen consumption and light hydrocarbon yields, in order to reduce the complexity of the optimisation problem. Consequently, critical interactions among feed and catalyst properties, hydroprocessor operating conditions, product quality and yields, and hydrogen consumption are usually neglected. This research work involves three major aspects: 1. Development of semi-empirical nonlinear lumped hydrodesulphurisation (HDS) and hydrocracker models that are robust and sufficiently detailed to capture the behaviour of the process with changes in feed characteristics and operating conditions. The formation of light hydrocarbons during HDS reactions have been accounted for. Hydrocracker conversion models and five/six-lumped product yield models for vacuum gas oil (VGO) and vacuum residue (VR) feedstocks have been developed from a combination of first principles and empirical methods based on several process parameters. The proposed models are validated with different feedstocks and shows good agreement with industrial data. 2. Integration of HDS and hydrocracker performance models into refinery hydrogen network models to explore existing interactions between processes and the hydrogen network, and their combined effect on the overall network objective. 3. Optimization of the overall superstructure under different operating scenarios to facilitate the efficient distribution and utilization of hydrogen and the maximization of clean high-value products. The integrated superstructure network model is developed and optimized within the General Algebraic Modelling System (GAMS). The model is representative of the dynamic interactions between hydrodesulphurisation and hydrocracking processes in the refinery hydrogen network as demonstrated by the reproducibility of industrial refinery data. Thus, this work presents a holistic and realistic implementation of refinery hydrogen management technique.
26

CO<sub>2</sub> Capture With MEA: Integrating the Absorption Process and Steam Cycle of an Existing Coal-Fired Power Plant

Alie, Colin January 2004 (has links)
In Canada, coal-fired power plants are the largest anthropogenic point sources of atmospheric CO<sub>2</sub>. The most promising near-term strategy for mitigating CO<sub>2</sub> emissions from these facilities is the post-combustion capture of CO<sub>2</sub> using MEA (monoethanolamine) with subsequent geologic sequestration. While MEA absorption of CO<sub>2</sub> from coal-derived flue gases on the scale proposed above is technologically feasible, MEA absorption is an energy intensive process and especially requires large quantities of low-pressure steam. It is the magnitude of the cost of providing this supplemental energy that is currently inhibiting the deployment of CO<sub>2</sub> capture with MEA absorption as means of combatting global warming. The steam cycle of a power plant ejects large quantities of low-quality heat to the surroundings. Traditionally, this waste has had no economic value. However, at different times and in different places, it has been recognized that the diversion of lower quality streams could be beneficial, for example, as an energy carrier for district heating systems. In a similar vein, using the waste heat from the power plant steam cycle to satisfy the heat requirements of a proposed CO<sub>2</sub> capture plant would reduce the required outlay for supplemental utilities; the economic barrier to MEA absorption could be removed. In this thesis, state-of-the-art process simulation tools are used to model coal combustion, steam cycle, and MEA absorption processes. These disparate models are then combined to create a model of a coal-fired power plant with integrated CO<sub>2</sub> capture. A sensitivity analysis on the integrated model is performed to ascertain the process variables which most strongly influence the CO<sub>2</sub> energy penalty. From the simulation results with this integrated model, it is clear that there is a substantial thermodynamic advantage to diverting low-pressure steam from the steam cycle for use in the CO<sub>2</sub> capture plant. During the course of the investigation, methodologies for using Aspen Plus® to predict column pressure profiles and for converging the MEA absorption process flowsheet were developed and are herein presented.
27

Purchasing Process integration in manufacturing industry in China : Case study of three Chinese manufacturing companies

Liu, Weihua, Chen, Ying January 2011 (has links)
Background:China could be seemed as a highly developing country. There are many opportunities and challenges inChina. Its preferential policies and huge potential market attract a lot of foreign companies to come toChina. Meanwhile, Chinese government encourages the development of domestic enterprises. Therefore, at present there mainly coexist three forms of enterprises inChina: foreign-funded companies, private companies and state-controlling companies. In order to enhance competitiveness, almost every company in china has its own supply chain network. Supply Chain management plays an important role in Chinese companies. Research question: 1.     What is the current situation of purchasing process and purchasing process integration for some manufacturers of different ownerships in China?   2.     How can purchasing process be integrated for some manufacturers of different ownerships in China from manufacture’s perspectives?   Purpose: The purpose of this thesis is to study the current situation in purchasing process integration in Chinese manufacturing industry of three kinds of ownership and evaluate the purchasing process of three kinds of companies in China. In addition, it gives some suggestions to remove potential obstacles and optimize the purchasing process; and aims to help the companies to gain competitive advantage in the long term.   Method: The empirical foundation for this thesis is intended to be on multiple case study method. It studies of the three types of manufacturing enterprises in China. To represent these three types of companies, three companies are chosen from each as selected research objects. Data is collected through semi-structure interviews, so the questionnaire would be open-ended. Long-distance telephone interview with purchasing managers and material managers separately for each company would be adopted.   Conclusion: The purchasing process of three companies who represent three different types of ownership is studied. It studies the current situation in purchasing process integration in Chinese manufacturing industry of three kinds of ownership and evaluates the purchasing process of three kinds of companies in China. Then the obstacles in purchasing process are found out. Then suggestions on purchasing process integration are used to tackle these obstacles.   Future Work: This thesis focuses on three manufacturing companies in China. The result of this thesis cannot represent all the obstacles in purchasing process in manufacturing industry in China. But the purchasing process, characteristics, strength and weakness are similar in the same type of ownership. Meanwhile, the recommendation on purchasing process integration also cannot solve all the obstacles found, due to the companies’ own condition. In future research, it recommends to add more research companies. Furthermore, more studies could be included to identify common obstacles and dig out solutions related to purchasing process integration in Chinese manufacturing industry.
28

Integrated approaches to the optimization of process-utility systems

Al-Azri, Nasser Ahmed 15 May 2009 (has links)
The goal of this work is to develop a conceptual framework and computational tools for the optimization of utility systems in the process industries. The emphasis is devoted to the development of systematic design techniques aimed at identifying modifications to the process and the associated utility-systems to jointly optimize the process and the utility system. The following contributions describe the specific results of this work: • Development of shortcut methods for modeling and optimizing steam systems and basic thermodynamic cycles with the objective of using these methods in the optimization of combined heat and power. To enable efficient mathematical programming formulations, simple yet accurate correlations have been developed for the thermodynamic properties of steam in the utility system. • Optimization of multi-level steam system for combined process requirements and power cogeneration. A general procedure is developed to determine rigorous cogeneration targets and the optimal configuration of the system with the associated design and operating variables. • Graph theory methods are also used to optimize the pipeline layout in the plant for the distributing the utilities. • Finally, because of the nonconvex nature of much of the developed optimization formulations, a global optimization method has also been suggested by using interval analysis and simulated annealing. The techniques proposed in this work are compared to previous works and their applicabilities are presented in case studies. These techniques outperform previously suggested ones in terms of the accuracy, computational efficiency and/or optimality.
29

Process simulation, integration and optimization of blending of petrodiesel with biodiesel

Wang, Ting 15 May 2009 (has links)
With the increasing stringency on sulfur content in petrodiesel, there is a growing tendency of broader usage of ultra low sulfur diesel (ULSD) with sulfur content of 15 ppm. Refineries around the world should develop cost-effective and sustainable strategies to meet these requirements. The primary objective of this work is to analyze alternatives for producing ULSD. In addition to the conventional approach of revamping existing hydrotreating facilities, the option of blending petrodiesel with biodiesel is investigated. Blending petrodiesel with biodiesel is a potentially attractive option because it is naturally low in sulfur, enhances the lubricity of petrodiesel, and is a sustainable energy resource. In order to investigate alternatives for producing ULSD, several research tasks were undertaken in this work. Firstly, base-case designs of petrodiesel and biodiesel production processes were developed using computer-aided tools ASPEN Plus. The simulations were adjusted until the technical criteria and specifications of petrodiesel and biodiesel production were met. Next, process integration techniques were employed to optimize the synthesized processes. Heat integration for petrodiesel and biodiesel was carried out using algebraic, graphical and optimization methods to maximize the integrated heat exchange and minimize the heating and cooling utilities. Additionally, mass integration was applied to conserve material resources. Cost estimation was carried out for both processes. The capital investments were obtained from ASPEN ICARUS Process Evaluator, while operating costs were calculated based on the updated chemical market prices. The total operating costs before and after process integration were calculated and compared. Next, blending optimization was performed for three blending options with the optimum blend for each option identified. Economic comparison (total annualized cost, breakeven analysis, return on investment, and payback period) of the three options indicated that the blending of ULSD with chemical additives was the most profitable. However, the subsequent life-cycle greenhouse gas (GHG) emission and safety comparisons demonstrated that the blending of ULSD with biodiesel was superior.
30

A Process Integration Approach to the Strategic Design and Scheduling of Biorefineries

Elms, Rene ̓Davina 2009 December 1900 (has links)
This work focused upon design and operation of biodiesel production facilities in support of the broader goal of developing a strategic approach to the development of biorefineries. Biodiesel production provided an appropriate starting point for these efforts. The work was segregated into two stages. Various feedstocks may be utilized to produce biodiesel, to include virgin vegetable oils and waste cooking oil. With changing prices, supply, and demand of feedstocks, a need exists to consider various feedstock options. The objective of the first stage was to develop a systematic procedure for scheduling and operation of flexible biodiesel plants accommodating a variety of feedstocks. This work employed a holistic approach and combination of process simulation, synthesis, and integration techniques to provide: process simulation of a biodiesel plant for various feedstocks, integration of energy and mass resources, optimization of process design and scheduling, and techno-economic assessment and sensitivity analysis of proposed schemes. An optimization formulation was developed to determine scheduling and operation for various feedstocks and a case study solved to illustrate the merits of the devised procedure. With increasing attention to the environmental impact of discharging greenhouse gases (GHGs), there has been growing public pressure to reduce the carbon footprint associated with fossil fuel use. In this context, one key strategy is substitution of fossil fuels with biofuels such as biodiesel. Design of biodiesel plants has traditionally been conducted based on technical and economic criteria. GHG policies have the potential to significantly alter design of these facilities, selection of feedstocks, and scheduling of multiple feedstocks. The objective of the second stage was to develop a systematic approach to design and scheduling of biodiesel production processes while accounting for the effect of GHG policies. An optimization formulation was developed to maximize profit of the process subject to flowsheet synthesis and performance modeling equations. The carbon footprint is accounted for through a life cycle analysis (LCA). The objective function includes a term reflecting the impact of the LCA of a feedstock and its processing to biodiesel. A multiperiod approach was used and a case study solved with several scenarios of feedstocks and GHG policies.

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