Effiziente Verstromung von Biogas in einem SOFC-System : Entwicklung, Charaktersieirung und Betriebsverhalten

Der Einsatz von Biogas in SOFC-Brennstoffzellen ermöglicht eine wirkungsgradoptimierte Nutzung des Methans im Vergleich zu BHKW-Anwendungen. Ziel dieses AiF-Projektes und dieser Arbeit war der Nachweis, dass die kombinierte Trocken/Dampf-Reformierung von Biogas mit der Verstromung des resultierenden Reformatgases in einer SOFC technisch realisierbar sind und das Gesamtsystem sicher und dauerhaft mit hohem Wirkungsgrad betrieben werden kann. Zusätzlich ist eine Wirtschaftlichkeitsbetrachtung erfolgt. Der Aufbau eines solchen Systems bedingt die Kenntnis der zu erwartenden Biogaszusammensetzung inklusive der Schadkomponenten wie Schwefel, Siloxanen, Fluor und Chlor und deren Auswirkungen auf die SOFC. Die Biogaszusammensetzung und die vorhandenen Schadkomponenten sind abhängig vom eingesetzten Substrat und der Betriebsweise der Biogasanlage. Zusätzlich zu Literaturwerten wurde exemplarisch eine Biogasanlage (Nordzucker AG, Werk Uelzen) ausgewählt und ein umfangreiches Monitoring der Biogaszusammensetzung durchgeführt. Anhand dieser Daten konnte eine Gasfeinreinigung entwickelt, unter Laborbedingungen charakterisiert und nach erfolgtem Upscaling an der Biogasanlage erprobt werden. Um das Biogas in einer SOFC verstromen zu können, muss eine vorgeschaltete Reformierung erfolgen, welche anhand der ermittelten Biogaszusammensetzungen vom ZBT Duisburg entwickelt wurde. Die Auswirkungen eines direkten Einsatzes des Biogases in der SOFC wurden in einer Ofenumgebung untersucht und ergaben, dass die vorgeschaltete Reformierung notwendig ist, um ein adäquates Thermomanagement zu ermöglichen. Die interne Reformierung in der SOFC führt durch deren Endothermie zur Abkühlung der Zellen, welche die Exothermie der Verstromung im kleinen Leistungsbereich bis 1 kWel nicht kompensieren kann. Anschließend wurden umfangreiche Untersuchungen mit simuliertem Biogasreformat in der SOFC durchgeführt und anhand der Ergebnisse ein Betriebsfenster für das SOFC-Biogas-System festgelegt. Ein 1400 h Dauerversuch mit synthetischem Biogasreformat erlaubte eine Degradationsabschätzung bei Einsatz einer Biogasreformatgasmischung unter Idealbedingungen. Im Ergebnis zeigte sich keine nennenswerte Degradation der Zelle. Das SOFC-Systemkonzept wurde entwickelt, aufgebaut und eine Steuerung inklusive Sicherheitskonzept erarbeitet und implementiert. Die Inbetriebnahme erfolgte unter Laborbedingungen zunächst mit reinem Methan und anschließend mit synthetischem Biogas. Es wurde eine Parametervariation durchgeführt, um das System zu charakterisieren und Betriebsfenster zu ermitteln. Nach Abschluss der Voruntersuchungen wurde das System bei der Nordzucker AG mit realem Biogas betrieben und die Parametervariation wiederholt. Das Biogas der Nordzucker AG weist sehr hohe Methankonzentrationen und vergleichsweise wenige Schadkomponenten auf. Um das System in Hinblick auf den Einsatz an anderen Biogasanlagen beurteilen zu können, wurden zusätzlich Versuche mit synthetischem Biogas mit Methangehalten von 50 bis 80 Vol.-% durchgeführt. Dabei lag der Fokus auf vier Betriebsführungsstrategien, deren Leistung und Wirkungsgrad ermittelt und bewertet wurde. Um die Wirtschaftlichkeit eines solchen SOFC-Systems zu beurteilen, erfolgte ein Vergleich der experimentell ermittelten Daten mit einem Biogas-BHKW.Using biogas in SOFC fuel cells allows an effective use of methane compared to CHP applications. The aim of both the public funded project und this work was to prove that a combined dry/steam reformation of biogas with the power generation of the resulting biogas is technically feasible and that the complete system can be run safely and durably with a high efficiency. Moreover an economic efficiency calculation has been made. The setup of such a system requires the understanding of the expected composition of the biogas including the harmful substances like sulphur, siloxane, fluorine and chlorine and their influences on the SOFC. The composition of the biogas and the harmful substances depend on the applied substrate and the operation of the biogas plant. In addition to reference values, a biogas plant (Nordzucker AG, Werk Uelzen, Germany) was chosen as an example and a complex monitoring of the biogas composition was conducted. Based on this data a gas purification unit was developed, characterised under laboratory conditions and tested at the biogas plant after a successful upscaling. In order to generate power from biogas in a SOFC an upstream reforming process is necessary, which was developed by ZBT Duisburg using the measured biogas composition. The effects of a direct use of the biogas in a SOFC were tested in a furnace environment and indicated that the upstream reforming is necessary in order to allow an adequate thermal management. Internal reforming cools down the SOFC cells because the exothermic reaction by power generation up to 1 kWel can not compensate the endothermic reforming. Subsequently extensive tests with simulated biogas reformate in a SOFC stack were realised and an operational window was determined. A long term test with simulated biogas for 1400 h allowed a degradation appraisal under ideal conditions. In fact there was no significant degradation of the used cells. The SOFC system was engineered, constructed, a control system was implemented and a safety system was developed. The start-up under laboratory conditions occurs with methane and synthetical biogas. To characterize the system and determine an operation window a parameter variation was realized. The parameter variation was repeated at the biogas plant. The biogas plant from Nordzucker produces high calorific values by high methane concentrations and offers poor contaminant concentrations. Additional tests with methane concentrations from 50 up to 80 Vol.-% gave a hint for system operation at different biogas plants. Four operation modes were tested and benchmarked. To estimate the economic efficiency the SOFC system was compared with biogas CHP using experimental data

Sustainable supply chain management implementation-enablers and barriers in the textile industry

The distinct definition of accordance in the perceived barriers and enablers for sustainable supply chain management (SSCM) policy implementation has been the subject of various research studies, but a distinct focus on the textile sector has been the object of limited previous attention. However, it has been found that it affects the approach to developments in company approaches to sustainable supply chain management within that industry. This article presents the results of an in-depth comparative case study analysis, drawing on 23 interviews with managers of 10 companies from the textile industry. The analysis demonstrates that specific modes of collaboration can both enable an effective SSCM and diminish barriers for policy implementation. The width and depth varies between a collaborative management approach for an effective internal SSCM versus industry collaboration and buyer supplier collaboration to address external barriers and enablers

Animal Rationality

In Animal Rationality: Later Medieval Theories 1250-1350, Anselm Oelze offers the first comprehensive and systematic exploration of theories of animal rationality in the later Middle Ages. Readership: Everyone interested in medieval philosophy and psychology in general, as well as the history of the concept of animal rationality and of the animal/human boundary in particular

#HashtagPedagogies: Improving Literacy and Course Relevance through Social Media Metaphors

Article by Micah Oelze that explores implementing social media for higher-education research trainin

Exploring the Relationship Between Parental Satisfaction with CTARS and Improving Child\u27s School Performance and to Identity the Resilient Attributes in These Children

The purpose of this research was to explore parental satisfaction with CTARS, an early intervention program, housed in an elementary in South East Minneapolis. The study also examined whether there was a. Relationship between parental satisfaction and improved child’s school performance. Finally, the study identified resilient attributes in children within this program. The research focused on parents of 5th grade students who participated in CTARS during the 1994-95 academic school year. The research design included both qualitative and quantitative methods. A questionnaire was developed and distributed to 24 parents. Findings indicate that, parental participation and satisfaction with CTARS does positively influence their child’s overall school performance. Findings also identified eight resilient attributes identified in 72% of the children. Implication for social work practice in the areas of education, program planning and development are discussed

The Symphony of State: São Paulo\u27s Department of Culture, 1922-1938

In 1920s-30s São Paulo, Brazil, leaders of the vanguard artistic movement known as “modernism” began to argue that national identity came not from shared values or even cultural practices but rather by a shared way of thinking, which they variously designated as Brazil’s “racial psychology,” “folkloric unconscious,” and “national psychology.” Building on turn-of-the-century psychological and anthropological theories, the group diagnosed Brazil’s national mind as characterized by “primitivity” and in need of a program of psychological development. The group rose to political power in the 1930s, placing the artists in a position to undertake such a project. The Symphony of State charts this previously unexamined intellectual project and explains why elite leaders believed music to be the most-promising strategy for developing the national mind beyond primitivity. In 1935, they founded the São Paulo Department of Culture and Recreation in order to fund music education, train ethnomusicologists, commission symphonies, and host performances across the city. Until now, historians of twentieth-century Brazil have praised music as a critical site for marginalized groups to sound out political protest. But The Symphony of State shows the reverse has also been true: elite groups used music as a top-down civilizing project designed to naturalize racial hierarchies and justify class difference. The intellectual history portion of the dissertation turns on archival sources, newspaper accounts, personal correspondence, modernist literature, and the period’s scholarly journals. The examination of literary form, discourse analysis, and marginalia lends depth to a carefully-documented study of ideas. Then, The Symphony of State brings to bear an innovative reading of ethnographic field books, vinyl records, and music scores to show that the department’s scholarship and symphonic compositions alike furthered the narrative of a nation jeopardized by primitivity. What is more, the department’s composers employed musical properties such as harmony and dissonance as metaphors to convince listeners that a harmonious society required the maintenance of racial and class hierarchies. In bringing further clarity to the department’s intellectual project, the sections featuring music analysis speak to the value of reading music as an historical text. The dissertation accomplishes multiple goals. It uncovers the theory of national psychology driving the musical institution; examines ethnographic material to further understand racial and regional prejudice in the period; and analyzes concert music commissioned and performed by the municipal department. The examination of the musical institution reveals a moment in Brazilian history in which national identity was constructed atop the notion of a shared psychology and in which modernity was believed to come with the musical tuning of the body politic and the training of its mind

Animal Rationality

In Animal Rationality: Later Medieval Theories 1250-1350, Anselm Oelze offers the first comprehensive and systematic exploration of theories of animal rationality in the later Middle Ages. Readership: Everyone interested in medieval philosophy and psychology in general, as well as the history of the concept of animal rationality and of the animal/human boundary in particular

Control by light and oxygen of B875 and B850 pigment-protein complexes in Rhodopseudomonas sphaeroides

AbstractControl by light and oxygen of the formation of B875 and B850 pigment-protein complexes in Rhodopseudomonas sphaeroides was evaluated by use of Hill plots. Kinetics of oxygen-dependent control exhibited Hill coefficients of n = 1.06 and n = 0.65 for B875 and B850 complexes, respectively. Half-maximum inhibition of B875 complexes was at 20.4% air saturation of the medium and of B850 complexes at 0.9%. Light controlled both complexes with an identical sigmoidal kinetics of n = 2.1

11,12-EET stimulates the association of BK channel α and β(1) subunits in mitochondria to induce pulmonary vasoconstriction

In the systemic circulation, 11,12-epoxyeicosatrienoic acid (11,12-EET) elicits nitric oxide (NO)- and prostacyclin-independent vascular relaxation, partially through the activation of large conductance Ca2+-activated potassium (BK) channels. However, in the lung 11,12-EET contributes to hypoxia-induced pulmonary vasoconstriction. Since pulmonary artery smooth muscle cells also express BK channels, we assessed the consequences of BKβ1 subunit deletion on pulmonary responsiveness to 11,12-EET as well as to acute hypoxia. In buffer-perfused mouse lungs, hypoxia increased pulmonary artery pressure and this was significantly enhanced in the presence of NO synthase (NOS) and cyclooxygenase (COX) inhibitors. Under these conditions the elevation of tissue EET levels using an inhibitor of the soluble epoxide hydrolase (sEH-I), further increased the hypoxic contraction. Direct administration of 11,12-EET also increased pulmonary artery pressure, and both the sEH-I and 11,12-EET effects were prevented by iberiotoxin and absent in BKβ1−/− mice. In pulmonary artery smooth muscle cells treated with NOS and COX inhibitors and loaded with the potentiometric dye, di-8-ANEPPS, 11,12-EET induced depolarization while the BK channel opener NS1619 elicited hyperpolarization indicating there was no effect of the EET on classical plasma membrane BK channels. In pulmonary artery smooth muscle cells a subpopulation of BK channels is localized in mitochondria. In these cells, 11,12-EET elicited an iberiotoxin-sensitive loss of mitochondrial membrane potential (JC-1 fluorescence) leading to plasma membrane depolarization, an effect not observed in BKβ1−/− cells. Mechanistically, stimulation with 11,12-EET time-dependently induced the association of the BK α and β1 subunits. Our data indicate that in the absence of NO and prostacyclin 11,12-EET contributes to pulmonary vasoconstriction by stimulating the association of the α and β1 subunits of mitochondrial BK channels. The 11,12-EET-induced activation of BK channels results in loss of the mitochondrial membrane potential and depolarization of the pulmonary artery smooth muscle cells