Angebote zu "Fischer" (8 Treffer)

Kategorien

Shops

Optimization of Biomass-to-Liquid Plant Setups ...
32,16 € *
ggf. zzgl. Versand

Potentially rising oil prices caused by an increasing relative scarcity of mineral oil have farreachingconsequences for the transportation sector, the chemical industry and mineral oilcompanies in particular. As national laws in Germany require biofuels to be mixed intoconventional fuel to an increasing extend (BioKraftQuG 2009), mineral oil companies need toidentify economically competitive as well as technically feasible biofuel production processesto meet these requirements. A first generation of biofuels was introduced on a large scale buthas been criticized for competing with the agricultural production of food and for yieldingrelatively modest quantities of fuel per hectare of agricultural land. For this reason, 2ndgeneration biofuel production pathways such as Biomass-to-Liquid (BtL), which convertlignocellulosic material into liquid hydrocarbons using Fischer-Tropsch synthesis, have beendeveloped. While 2nd generation biofuels are superior to their 1st generation counterpartsfrom a yield-per-hectare-perspective and cause less competition for agricultural soils, asignificant disadvantage is the considerable investment required for the construction ofBiomass-to-Liquid plants. The corresponding investment-related costs affect thecompetitiveness of 2nd generation biofuels negatively, leaving it in doubt whether BtL fuelscould become an economically viable option. A frequently discussed way to improve specificinvestment-related costs is to increase plant sizes to improve economies of scale. While thisimprovement has been realized in several conventional kinds of plants like mineral oilrefineries, power plants and Coal-to-Liquid plants, the application on BtL plants iscomplicated by the fact that larger plants are associated with higher specific biomasstransportation costs. This is because a higher biomass input requires biomass to betransported over larger distances. The unresolved antagonism between economies of scaleand specific biomass transportation costs has so far hindered the realization of BtL plants.The aim of this thesis is to develop a methodology to determine optimal BtL plant sizes bytaking nonlinear factors into account. The methodology is required to determine acompromise between minimizing investment-related costs by applying economies of scaleand minimizing specific biomass transportation costs by keeping the required transportationdistances short. The optimal plant size is however influenced by a third influencing factor.Whether it is advantageous to transport biomass over a certain distance also depends on thevalue of a plant’s products. Biomass-to-Liquid plants can have a variety of productcompositions depending on the catalyst and reaction temperature used in the biofuelsynthesis reaction. Depending on which substances are produced and which are upgradedfor sale, converted into fuels or combusted for electricity generation, both the value of theproducts and the required investment may differ considerably. While a number of processes,including biomass treatment and gasification, as well as the Fischer-Tropsch synthesis itself,are required for all considered plant setup alternatives, the choice of upgrading equipmentmay result in very dissimilar plant setups. By making the capacities of the individualupgrading processes the variables of the optimization model, economies of scale, specificbiomass transportation costs and the products’ value are considered simultaneously for thefirst time.The thesis primarily focuses on the implementation of an optimization model and itsapplication on a variety of scenarios. These scenarios are intended to represent differentplant setups and logistics concepts. In order to assess the scale of differences in profitability,the essential influencing factors determining the profitability of BtL plants were included intothe model calculations. As the problem at hand is neither linear nor quadratic, it cannot besolved reliably using established solvers for these two classes of problems. Instead, severalsolvers designed to handle non-quadratic nonlinear multidimensional problems were appliedto find the most suitable way to approach the solution of the problem.The objective function has been designed to maximize the annual profit resulting from plantconstruction and operation. Maximizing this annual profit is subject to a number of primarilytechnical constraints. These result from the mass balances of the plant, its electricity demandand the specific requirements of individual processes. In addition to securing the validity ofthe mass balances, these constraints also ensure that the entire Fischer-Tropsch productstream undergoes some kind of upgrading, separation or combustion treatment. The sum ofall processes producing salable products is used to approximate the required capacity of theplant as a whole. The total plant capacity then serves to calculate the investment required forthe other plant processes and the costs for the purchase and transportation of the requiredinput biomass.Biomass transportation distances are approximated by the radius of an assumed circulararea from which biomass is supplied to the plant. Using cost functions that dividetransportation costs into fixed and variable parts makes it possible to approximate the effectof rising specific biomass transportation costs in case of increasing plant capacities.The investigated scenario calculations suggest that under the assumed circumstances, fueloriented low-temperature Fischer-Tropsch-based BtL plants are relatively competitive as longas the tax exemptions in Germany are maintained, but become significantly less attractivewithout them. By contrast, the combined production of both fuels and chemicals using hightemperatureFischer-Tropsch synthesis appears to be a more promising alternative, aschemicals are expected to earn a higher income in scenarios without tax exemptions. A thirdoption, the production of Substitute Natural Gas, appears to be relatively uncompetitiveunless methane prices rise significantly.In addition to comparing the economic attractiveness of different potential productdistributions, a number of concepts have been investigated which are intended to improveBiomass-to-Liquid economics. Decentralized pretreatment of biomass, e.g. through fastpyrolysis,leads to larger optimal plant capacities, but the additional investment for thepretreatment units appears to overcompensate the improved economies of scale. Bycontrast, the combined use of train and road transportation was not assumed to beassociated with additional investments. If train transportation is indeed feasible for a givenplant location and specific biomass transportation costs are lower than for roadtransportation, combined traffic concepts should be used whenever possible. Theconstruction of BtL plants in conjunction with mineral oil refineries is a way to reduceinvestment-related costs instead of transportation costs. While the resulting savings aresignificant for small BtL plants, they diminish if larger plant sizes are investigated. Cogasificationof biomass with another input material is another way to reduce the costlytransportation of biomass over large distances. Unless technical requirements significantlyincrease the cost of the gasification equipment, co-gasification concepts can improve theplant’s profitability even at relatively low quantities of a second fuel. The choice of fuels ishowever restricted by the Renewable Energy Directive that needs to be abided by in order toensure the eligibility for tax exemptions. In case of lignite and hard coal, fossil CO2 emissionsfurther complicate the application of co-gasification, as Renewable Energy Directive alsolimits the amount of fossil CO2 that biofuel production is allowed to cause. As savings causedby such concepts depend on the relative inefficiency of the concept that they are applied on,the effect of the implementation of several improvements diminishes if these address thesame cost item.In this work, the nonlinear effects of economies of scale and biomass transportation costs forincreasing Biomass-to-Liquid plant capacities has been modeled on a product-upgradingprocessbasis for the first time. Potential investors and plant operators of Biomass-to-Liquidplants are thus enabled to determine both the optimal plant size and the most promisingchoice of products in order to maximize the prospective competitiveness of the plant.

Anbieter: Dodax
Stand: 28.10.2020
Zum Angebot
Investigation into High Efficiency Visible Ligh...
111,88 € *
ggf. zzgl. Versand

This thesis describes novel strategies for the rational design of several cutting-edge high-efficiency photocatalysts, for applications such as water photooxidation, reduction, and overall splitting using a Z-Scheme system. As such, it focuses on efficient strategies for reducing energy loss by controlling charge transfer and separation, including novel faceted forms of silver phosphate for water photooxidation at record high rates, surface-basic highly polymerised graphitic carbon nitride for extremely efficient hydrogen production, and the first example of overall water splitting using a graphitic carbon nitride-based Z-Scheme system.Photocatalytic water splitting using solar irradiation can potentially offer a zero-carbon renewable energy source, yielding hydrogen and oxygen as clean products. These two 'solar' products can be used directly in fuel cells or combustion to provide clean electricity or other energy. Alternatively they can be utilised as separate entities for feedstock-based reactions, and are considered to be the two cornerstones of hydrogenation and oxidation reactions, including the production of methanol as a safe/portable fuel, or conventional catalytic reactions such as Fischer-Tropsch synthesis and ethylene oxide production.The main driving force behind the investigation is the fact that no photocatalyst system has yet reported combined high efficiency, high stability, and cost effectiveness, though cheap and stable, most suffer from low efficiency.

Anbieter: Dodax
Stand: 28.10.2020
Zum Angebot
Outwitting the Dilemma of Scale
79,00 € *
ggf. zzgl. Versand

There is hardly any topic in the renewable energy sector that is as dynamic as the world of biofuels. Due to growing concerns about CO2 emissions, the importance of the transport sector in everybody s life as well as concerns about security of fuel supply in Europe and the US biofuels are an interesting field of research.One of the most fascinating questions particularly in synthetic biofuels is the debate about the ideal scale of production plants. On the one hand, fossil fuel supply is based on large and centralized facilities, on the other, bioenergy systems are typically characterized by small and decentralized technologies. The question is: Which way to go in biomass-based Fischer-Tropsch fuel production? As the author disagrees with common wisdom that synfuel plants have to be of enormous scale to allow cost-competitive production, an unconventional and innovative process design is proposed that combines small-scale and low-cost fuel production. Consequently, the production based on polygeneration and a revival of the historic normal pressure synthesis could open the door to decentralized, biomass-based Fischer-Tropsch synfuel technology.

Anbieter: Dodax
Stand: 28.10.2020
Zum Angebot
Fischer 506196 Dübel 8 cm 100 Stück(e)
38,68 € *
ggf. zzgl. Versand

The fischer frame fixing SXR is a frame fixing made of high-quality nylon. Due to the special plug geometry, the SXR can be used in solid and hollow building materials. The frame fixing can be used in a particularly cost-effective manner due to the low anchorage depth of only 50 mm. The fischer frame fixing SXR is suitable for fixing timber substructures, coat racks, and kitchen cabinets. Top Features - Cost-effective fixing due to low anchorage depth. - Expansion in solid building materials. - Knotting in hollow building materials. - Suitable for concrete and brickwork.

Anbieter: Dodax
Stand: 28.10.2020
Zum Angebot
Fischer 506194 Dübel 6 cm 100 Stück(e)
17,69 € *
ggf. zzgl. Versand

The fischer frame fixing SXR is a frame fixing made of high-quality nylon. Due to the special plug geometry, the SXR can be used in solid and hollow building materials. The frame fixing can be used in a particularly cost-effective manner due to the low anchorage depth of only 50 mm. The fischer frame fixing SXR is suitable for fixing timber substructures, coat racks, and kitchen cabinets. Top Features - Cost-effective fixing due to low anchorage depth. - Expansion in solid building materials. - Knotting in hollow building materials. - Suitable for concrete and brickwork.

Anbieter: Dodax
Stand: 28.10.2020
Zum Angebot
New Science of Learning
218,00 CHF *
ggf. zzgl. Versand

The earliest educational software simply transferred print material from the page to the monitor. Since then, the Internet and other digital media have brought students an ever-expanding, low-cost knowledge base and the opportunity to interact with minds around the globe—while running the risk of shortening their attention spans, isolating them from interpersonal contact, and subjecting them to information overload. The New Science of Learning: Cognition, Computers and Collaboration in Education deftly explores the multiple relationships found among these critical elements in students’ increasingly complex and multi-paced educational experience. Starting with instructors’ insights into the cognitive effects of digital media—a diverse range of viewpoints with little consensus—this cutting-edge resource acknowledges the double-edged potential inherent in computer-based education and its role in shaping students’ thinking capabilities. Accordingly, the emphasis is on strategies that maximize the strengths and compensate for the negative aspects of digital learning, including: Group cognition as a foundation for learning Metacognitive control of learning and remembering Higher education course development using open education resources Designing a technology-oriented teacher professional development model Supporting student collaboration with digital video tools Teaching and learning through social annotation practices The New Science of Learning: Cognition, Computers and Collaboration in Education brings emerging challenges and innovative ideas into sharp focus for researchers in educational psychology, instructional design, education technologies, and the learning sciences.     Endorsements: 'The book brings together leading researchers who study how technology can enhance student learning. They address questions of how technology can support collaborative learning, knowledge building, assessment, metacognition, and professional development. For example, a chapter by Howard Gardner and his colleagues describes how students are changing as they grow up with new technologies, and a chapter by Kurt W. Fischer and his colleagues describes redesigning testing with the use of latest in computer technology and learning science. Altogether it is a fine collection of chapters about the latest advances in educational technology.'Allan Collins, Northwestern University – Author, Rethinking Education in the Age of Technology   'Modern learning technologies have emerged in the 21st century as powerful tools to enhance learning and thinking, but much of their potential remains to be realized. Remarkably, as we explore how learners interact with diverse learning environments, including digital media, we are discovering that these tools also are revealing new insights into how our minds operate and how better to realize the promise that learning technologies offer. This book presents some of the latest discoveries and theoretical insights about how we think and learn, especially through explorations employing digital media. This is a first-class book containing chapters by some of the best researchers worldwide.' O. R. Anderson, Columbia University, Teachers College – Chair, Mathematics, Science and Technology

Anbieter: Orell Fuessli CH
Stand: 28.10.2020
Zum Angebot
New Science of Learning
203,99 € *
ggf. zzgl. Versand

The earliest educational software simply transferred print material from the page to the monitor. Since then, the Internet and other digital media have brought students an ever-expanding, low-cost knowledge base and the opportunity to interact with minds around the globe—while running the risk of shortening their attention spans, isolating them from interpersonal contact, and subjecting them to information overload. The New Science of Learning: Cognition, Computers and Collaboration in Education deftly explores the multiple relationships found among these critical elements in students’ increasingly complex and multi-paced educational experience. Starting with instructors’ insights into the cognitive effects of digital media—a diverse range of viewpoints with little consensus—this cutting-edge resource acknowledges the double-edged potential inherent in computer-based education and its role in shaping students’ thinking capabilities. Accordingly, the emphasis is on strategies that maximize the strengths and compensate for the negative aspects of digital learning, including: Group cognition as a foundation for learning Metacognitive control of learning and remembering Higher education course development using open education resources Designing a technology-oriented teacher professional development model Supporting student collaboration with digital video tools Teaching and learning through social annotation practices The New Science of Learning: Cognition, Computers and Collaboration in Education brings emerging challenges and innovative ideas into sharp focus for researchers in educational psychology, instructional design, education technologies, and the learning sciences.     Endorsements: 'The book brings together leading researchers who study how technology can enhance student learning. They address questions of how technology can support collaborative learning, knowledge building, assessment, metacognition, and professional development. For example, a chapter by Howard Gardner and his colleagues describes how students are changing as they grow up with new technologies, and a chapter by Kurt W. Fischer and his colleagues describes redesigning testing with the use of latest in computer technology and learning science. Altogether it is a fine collection of chapters about the latest advances in educational technology.'Allan Collins, Northwestern University – Author, Rethinking Education in the Age of Technology   'Modern learning technologies have emerged in the 21st century as powerful tools to enhance learning and thinking, but much of their potential remains to be realized. Remarkably, as we explore how learners interact with diverse learning environments, including digital media, we are discovering that these tools also are revealing new insights into how our minds operate and how better to realize the promise that learning technologies offer. This book presents some of the latest discoveries and theoretical insights about how we think and learn, especially through explorations employing digital media. This is a first-class book containing chapters by some of the best researchers worldwide.' O. R. Anderson, Columbia University, Teachers College – Chair, Mathematics, Science and Technology

Anbieter: Thalia AT
Stand: 28.10.2020
Zum Angebot