Clausthal-Zellerfeld, Germany
Clausthal-Zellerfeld, Germany

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Muller E.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Hilty L.M.,Empa - Swiss Federal Laboratories for Materials Science and Technology | Hilty L.M.,University of Zürich | Hilty L.M.,KTH Royal Institute of Technology | And 3 more authors.
Environmental Science and Technology | Year: 2014

Dynamic material flow analysis (MFA) is a frequently used method to assess past, present, and future stocks and flows of metals in the anthroposphere. Over the past fifteen years, dynamic MFA has contributed to increased knowledge about the quantities, qualities, and locations of metal-containing goods. This article presents a literature review of the methodologies applied in 60 dynamic MFAs of metals. The review is based on a standardized model description format, the ODD (overview, design concepts, details) protocol. We focus on giving a comprehensive overview of modeling approaches and structure them according to essential aspects, such as their treatment of material dissipation, spatial dimension of flows, or data uncertainty. The reviewed literature features similar basic modeling principles but very diverse extrapolation methods. Basic principles include the calculation of outflows of the in-use stock based on inflow or stock data and a lifetime distribution function. For extrapolating stocks and flows, authors apply constant, linear, exponential, and logistic models or approaches based on socioeconomic variables, such as regression models or the intensity-of-use hypothesis. The consideration and treatment of further aspects, such as dissipation, spatial distribution, and data uncertainty, vary significantly and highly depends on the objectives of each study. © 2014 American Chemical Society.

Al Momani F.,CUTEC Institute | Al Momani F.,Mu'tah University | Schaefer S.,CUTEC Institute | Sievers M.,CUTEC Institute
Ozone: Science and Engineering | Year: 2010

Chemical treatment processes such as ozonation have mostly been considered as an efficient way for bio-solids minimization. The improvement of sludge dewatering was more a welcoming side effect in these sequential processes. However, some times the loaded ozone dose to the sludge has a negative effect on dewaterability.This work address the most important issue found - the effect of ozone on sludge dewaterability in a single ozonation processes as well as in a sequential ozonation biological processes. It was found that the maximum sludge dewaterability was achieved with an ozone dose of 0.05 gO3/gTSS. This value was found to be less than the required ozone dosage that leads to sludge disintegration. However, it was observed that the sequential ozone and aerobic treatment allows further strong improvement of dewatering efficiencies. © 2010 International Ozone Association.

Vodegel S.,CUTEC Institute | Muller F.,CUTEC Institute
DGMK Tagungsbericht | Year: 2015

Biomass is an attractive source for synthesis gas due to its renewable character. The gasification can be difficult if thermo-chemical complex kinds like switchgras, straw e.c. are used. But these are interesting to avoid ethic discussions. CUTEC possesses in a pilot plant the complete line from chopper, gasifier, gas cleaning and conditioning until a Fischer Tropsch Synthesis (FTS) and a methane synthesis. In the last years the synthesis gas production based on biomass was developed. Special results were: 1. The crushing behavior of blades including the energy consumption depends from the time of harvest very much. The gasification is affected 2. In the developed circulating fluidized bed is the gasification of thermo-chemical difficult biomass up to 820°C possible 3. Five mass-% of the tars can have a condensation point up to 500°C and higher 4. The H2 to CO ratio can be varried with process parameters 5. Most of the chlorine is found in the filter ash; only a small part is existing as HCl in the gas phase 6. A very clean synthesis gas with only 7 vol.-% CO2 is possible.

Lindermeir A.,CUTEC Institute | Dietrich R.-U.,CUTEC Institute | Oelze J.,CUTEC Institute
Ceramic Engineering and Science Proceedings | Year: 2014

Power generation from biogas using motor-driven CHP units has a limited electrical efficiency far below 50%, especially for smaller engines in the power range below 100 kWe. Fluctuating quality and/or low CH4 content reduce operation hours and economical and ecological benefit. On the other hand, solid oxide fuel cell (SOFC) systems promise electrical efficiencies above 50% even for small-scale units and/or low-calorific biogas. Current development tasks of SOFC stack technology are the scale-up of the power range up to the hundreds of kWe range and further improvements regarding their fuel efficiency, costs and lifetime. Nevertheless commercial state-of-the-art stacks and stack modules are already established in the market and thus available for the evaluation of different system concepts. In collaboration with the Zentrum für BrennstoffzellenTechnik (Center for Fuel Cell Technology, ZBT) CUTEC has developed a biogas fed 1 kWe SOFC-system using combined dry and steam reforming of CH4 for fuel processing. It demonstrates the opportunities of SOFC technology in the biogas market and allows cost-benefit-estimations for future development tasks. To assure a H2S concentration < 1 ppmv in the reformate gas a sulfur trap was developed based on actual biogas monitoring campaigns. A commercial SOFC stack module with two 30-cell ESC-stacks was used and the system was evaluated with both synthetic biogas mixtures and biogas from the wastewater treatment facility of a sugar refinery. Electrical power output of 850 to 1,000 We and electrical gross efficiencies between 39 and 52% were received for CH4 contents between 55 and 100 Vol.-%. Results were confirmed during a 500 h test period with synthetic biogas containing 55 Vol.-% CH 4 proving an electric power output of 1,000 We and an efficiency of 53%. No degradation of the stacks or the system components was observed.

Lindermeir A.,CUTEC Institute | Dietrich R.-U.,CUTEC Institute | Immisch C.,CUTEC Institute
Ceramic Engineering and Science Proceedings | Year: 2014

A compact propane driven SOFC-system with recycling of hot AOG is developed at CUTEC Institute with partners from Zentrum für BrennstoffzellenTechnik GmbH (ZBT, Duisburg), Institute of Energy and Process Systems Engineering (InES, TU Braunschweig) and Institute of Electrical Power Engineering (IEE, TU Clausthal). The system extends the commercially available integrated stack module (ISM) of Staxera GmbH (Dresden, Germany) by the required fuel processing unit and auxiliary components. The expected electrical power output for a propane flow of 1.0 1N/min is 950 We (gross). Thus, electrical system efficiency will be 61% (based on propane LHV). CUTEC developed a tailor-made hot gas ejector for anode offgas recycling that uses pressurised propane from standard gas bottles as propellant gas. Propane leaves the ejector nozzle at high velocity and hereby mixes with AOG. A Laval nozzle accelerates the propane stream to supersonic speed and enables a recycle ratio sufficient for soot-free reformer operation. As the ejector has no moving parts it is expected to work robust, even at the high operating temperatures of about 600°C. The system concept, design options for thermal integration and high compactness and experimental results for the component development will be discussed. Ejector performance data will be presented.

Birkenfeld S.,CUTEC Institute
2010 World Automation Congress, WAC 2010 | Year: 2010

In order to locate cylindrical objects like pipes and cables buried underground using ground penetrating radar it is necessary to detect reflexion hyperbolas in the measured radargrams. In practice, this task is in many cases complicated due to different geological environments, incomplete or disturbed hyperbolas, and first of all the fact that nearby objects lead to hyperbolas interfering with each other. In this paper we present an automatic detection system based on a specially connected neural network using receptive fields. We show that with an adequate definition of training data the system is capable of reliably detecting reflexion hyperbolas even in those challenging situations. © 2010 TSI Press.

Dietrich R.-U.,CUTEC Institute | Oelze J.,CUTEC Institute | Lindermeir A.,CUTEC Institute | Spitta C.,Zentrum fur BrennstoffzellenTechnik GmbH | And 5 more authors.
Journal of Power Sources | Year: 2011

The transfer of high electrical efficiencies of solid oxide fuel cells (SOFC) into praxis requires appropriate system concepts. One option is the anode-offgas recycling (AOGR) approach, which is based on the integration of waste heat using the principle of a chemical heat pump. The AOGR concept allows a combined steam- and dry-reforming of hydrocarbon fuel using the fuel cell products steam and carbon dioxide. SOFC fuel gas of higher quantity and quality results. In combination with internal reuse of waste heat the system efficiency increases compared to the usual path of partial oxidation (POX). The demonstration of the AOGR concept with a 300 Wel-SOFC stack running on propane required: a combined reformer/burner-reactor operating in POX (start-up) and AOGR modus; a hotgas-injector for anode-offgas recycling to the reformer; a dynamic process model; a multi-variable process controller; full system operation for experimental proof of the efficiency gain. Experimental results proof an efficiency gain of 18 percentage points (η·POX = 23%, η·AOGR = 41%) under idealized lab conditions. Nevertheless, further improvements of injector performance, stack fuel utilization and additional reduction of reformer reformer O/C ratio and system pressure drop are required to bring this approach into self-sustaining operation. © 2010 Elsevier B.V. All rights reserved.

Bormann H.,CUTEC Institute | Sievers M.,CUTEC Institute
Wasser und Abfall | Year: 2014

A great number of methods for the recovery of phosphorus from secondary raw materials has been developed in Germany in the past years and partially led towards practical maturity. A review will be presented in this article.

Reuter M.,CUTEC Institute | Bohlmann S.,CUTEC Institute
World Automation Congress Proceedings | Year: 2012

In this paper we present a tool, supervising a multi-cut aggregate working in the German factory for pipeline production Salzgitter Mannesmann Line Pipe GmbH by CI-based methods. To achieve this aim we use special pre-processing strategy of the DLS-Spectra and topological closed SOMs used as unsharp classifiers in a defined range by using the principle of Computing with Activities (CWA). We will show that this strategy leads to an early detection of machinery faults, creeping trends of wear effects and sudden uprising of so far unknown sensor states. © 2012 TSI Press.

Birkenfeld S.,CUTEC Institute
World Automation Congress Proceedings | Year: 2014

In many applications of neural networks, e.g. time series prediction or pattern analysis, training data are generated automatically out of large data sets. The problem is to determine the varying significance of the resulting training vectors concerning the given task in order to make appropriate decisions for the training phase. In this paper we propose a self-organized significance analysis based on a rareness assessment for each vector in the generated training data set. The resulting significance measure can be used to achieve considerably improved classification results for a wide variety of applications by systematically controlling training parameters like learning rate or frequency of presentation for each single vector. © 2014 TSI Press.

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