Due to ecological reasons and because of the need to remain independent from foreign energy suppliers, the power generation in offshore wind parks becomes more and more important in Germany. It is therefore planned to build up approximately 1,300 new offshore wind power plants with a capacity of 6,500 MW near the German coastline until 2020. The structures are installed on the ground of the sea in a water depth that might in some cases reach 50 m. The mechanical loading situation for these structures is characterised by an enormous weight combined with high cyclic stresses resulting from the service loads and the tide. Hence, hot rolled steels with a yield strength of 355 MPa are employed in a maximum thickness of 100 mm. Until now, the required toughness properties for these structural steels and their welds are 40 J at -20 C. However, in a plate thickness of 100 mm, only the submerged arc welding (SAW) process can be used to guarantee such toughness properties, but especially in these heavy plates, submerged arc welding is rather time consuming and consequently more uneconomic compared to other welding techniques. Due to these disadvantages, it can even be expected that only part of the planned power plants will be built up in time as the high welding time of several hours per m causes too many delays. From the point of structural integrity, it can be argued wether a Charpy impact toughness of 40 J is really required, as this criterion is only set based on experiences of mechanical and civil engineers. Thus, it can be concluded that different welding techniques should be regarded as alternatives to SAW in case that the 'real' toughness requirements are less than 40 J at -20 C. Electron beam welding would be a favourable welding process for such heavy plates as even 100 m thick plates can be welded in one single step, but until now the toughness requirements of 40 J have not yet been met. It is therefore the aim of the research project to reinforce the electron beam welding process for the application to heavy plates in offshore wind power plants. To reach this aim, the following tasks are be carried out: - improvement of the electron beam welding process in order to achieve better toughness properties of the welds, - application of reliable fracture mechanics concepts in order to calculate realisitc toughness requirements. With regard to the process, already a this stage of the project an enormous improvement of the toughness properties of EB weld seams could be demonstrated based on optimisation of the welding process. Furthermore, it could be shown that by establishing the leakage before breakage criterion combined with regular inspections, the toughness requirements can be significantly reduced. Thus, the EB welding can be applied to offshore wind energy installations even if steels of higher yield strength (e.g. S460Q) are selected.
In order to be able to sustainably use fossil fuels as an energy source, various techniques are being considered to capture the carbon dioxide produced in combustion and sequester it or otherwise prevent it from being released into the atmosphere. Several of these techniques involve the adsorption of gases, especially CO2, to adsorbent solid materials, either as a means of separating gases from each other, or as a storage mechanism (e.g. in coal seams). In all cases of interest, moisture is present, affecting the adsorption of gases in ways that are not fully understood yet. This project will study the interaction of CO2 and the other gases involved (nitrogen, hydrogen, methane depending on the specific application) with different adsorbents in the presence of water. Adsorption plays a role in the capture of carbon dioxide as a technique to separate the greenhouse gas from other gases. This can be done in pre-combustion capture, where the CO2 has to be separated from hydrogen, usually by pressure swing adsorption (PSA) on activated carbon or zeolites; or it can be done by post-combustion capture, where the CO2 is separated from the rest of the flue gas, mainly nitrogen. This is typically done by temperature swing adsorption (TSA) on activated carbon. Another application involves adsorption as a way of extracting carbon dioxide directly from ambient air In the area of carbon dioxide storage, adsorption is significant when the carbon dioxide is to be used for enhanced coal bed methane recovery (ECBM). In this application, CO2 is injected into coal seams as a displacer for methane adsorbed into the pores in the coal. This is an attractive option to store CO2, as it enhances methane production at the same time. The capacity of coal for carbon dioxide has consistently been higher for carbon dioxide than for methane, leading to a net storage of carbon dioxide. Both systems for CO2 capture and for storage have been the subjects of study, but the effect that water has on these systems has yet to be investigated in detail. The scientific questions that are to be addressed with this project are (1) how to characterize the role of water on CO2 adsorption, (2) how to understand and describe it, and (3) how to use this knowledge to overcome or to exploit the effect of water in order to design better separation processes.
Der Praxis werden eine Vielzahl von ein- und mehrkomponentigen kunststoffgebundenen Fugenmörteln angeboten, die von den Herstellern als wasserdurchlässig beschrieben werden. In einem 2002 begonnenen Versuch mit drei epoxidharzgebundenen Fugenmörteln wurden bei gleichen Mörteln unterschiedliche Wasserdurchlässigkeiten festgestellt. Im Versuch soll die Wasserdurchlässigkeit der am häufigsten verwendeten kunststoffgebundenen Fugenmörtel sowohl an Probekörpern als auch Pflasterflächen untersucht werden. Ferner soll untersucht werden, inwieweit es durch Bewitterung/Alterung zu Änderungen der Durchlässigkeit zur Folge haben.
Der Praxis werden eine Vielzahl von ein- und mehrkomponentigen kunststoffgebundenen Fugenmörteln angeboten, die von den Herstellern als wasserdurchlässig beschrieben werden. In einem 2002 begonnenen Versuch mit drei epoxidharzgebundenen Fugenmörteln wurden bei gleichen Mörteln unterschiedliche Wasserdurchlässigkeiten festgestellt. Im Versuch soll die Wasserdurchlässigkeit des Systems Fugenmörtel / zementgebundene Bettungsschicht im Vergleich zu einer ungebundenen Splittbettung untersucht werden.
Um die Durchfeuchtung einer Fassade oder eines Fassadenteils durch die Reinigung mit Wasser zu verringern, sollen im Prinzip bekannte wasserarme Reinigungsverfahren verbessert werden. Ziel ist ein von der Denkmalpflege festgelegtes Reinigungsergebnis unter Verwendung von moeglichst wenig Wasser zu erzielen. Dies koennte zB durch die Entwicklung eines Feinststaubstrahlverfahrens moeglich sein. Bei dem Ersatz von schadhaften Fugenmoertel im Rahmen einer Instandsetzungsmassnahme kann heute aufgrund fehlender geeigneter Geraete und Verfahren eine sehr schmale Fuge nur unter Verlust des Originalfugenbildes durch Verbreiterung ausgeraeumt werden. Ziel ist, vorhandene Geraete so zu modifizieren, dass mit ihnen erschuetterungsfrei, dem Fugenverlauf folgend der alte Fugenmoertel entfernt werden kann, ohne dabei die angrenzende Bausubstanz zu schaedigen. Dies koennte durch geeignete mechanische Werkzeuge bzw durch einen Hochdruckwasserfeinststrahl-Verfahren erreicht werden.