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Kuhn S.,Freudenberg Forschungsdienste SE and Co. KG | Unterumsberger F.,Mitsubishi Hitachi Power Systems Europe GmbH
Praktische Metallographie/Practical Metallography | Year: 2014

Generally, the clarification of hydrogen induced component damage cases by means of failure analysis is based on fractographic examinations in combination with hydrogen analyses. However, due to high diffusion rates of hydrogen in steels at RT (room temperature), providing the analytical evidence of an excessive hydrogen content is rarely possible. This work presents potential production and application related hydrogen sources as well as the mechanisms of hydrogen induced delayed formation of cracks and illustrates a systematical approach to produce comparative hydrogen fracturing. Therefore, the damaged component's specific material condition is the basis in order to generate a comparative fracture surface with an identical fracture morphology and applying the same damage mechanism. The approach of producing comparative fracturing is illustrated by two cases of damage. Source

Nikolopoulos N.,Center for Research and Technology Hellas | Violidakis I.,Center for Research and Technology Hellas | Karampinis E.,Center for Research and Technology Hellas | Agraniotis M.,Mitsubishi Hitachi Power Systems Europe GmbH | And 5 more authors.
Fuel | Year: 2015

Lignite constitutes a major energy source and has long been used for energy production despite its contribution in greenhouse gas (GHG) emissions, as a fossil fuel. For example, 27.4% of Germany's electricity originates from lignite power plants, while in Greece more than 55% of its electric energy consumption is provided by lignite. 45% of the total global coal reserves consist of low-rank coals (LRCs) such as lignite. With this background, the utilization of lignite for energy production is expected to remain a common practice in the decades to come since the availability of lignite is considerable in many countries of Europe and the world (e.g. Germany, Poland, Greece, USA, and Australia). Therefore, problems regarding the combustion and use of lignite should be addressed in a more efficient and environmentally friendly way. One of the main existing problems is the high moisture contained in raw lignite as received from the mine. The high moisture content results in higher CO2 emissions per unit of energy produced and is responsible for high capital and transport costs as well as other technical problems such as reduction in coal friability and difficulties in its blending and pneumatic transportation. Therefore, processing of lignite through drying is considered of great interest in the implementation of energy production in lignite power plants. Taking into account the significance of the subject and the usefulness of such an attempt, an overview of the currently existing drying technologies, including both evaporative and non-evaporative drying methods is reported in the present paper. © 2015 Elsevier Ltd. Source

Enomoto A.,Hitachi Ltd. | Fujii N.,Hitachi Ltd. | Nonaka Y.,Hitachi Ltd. | Rasch J.,Mitsubishi Hitachi Power Systems Europe GmbH | And 6 more authors.
Procedia CIRP | Year: 2015

Planning alternative multiple carry-in/out paths is essential to the engineering work of replacement tasks in power plant maintenance, adapting to the uncertain 3D environment of the plant building. For this subject, dissimilarity of the planned paths and fast response time for the query are required for a path finding algorithm. Existing path finding algorithms can find exact multiple paths but the differences of found paths are very little. Besides, the computation times are not feasible for a large volume of 3D space such as power plant. In this paper, a novel multiple paths finding algorithm is proposed for dissimilar paths planning with fast response time for the query, realizing interactive operations. Furthermore, performance indices for the path finding is designed with consideration of secure carry-in/out operations in the proposed algorithm. The algorithm outputs crane suspension trajectory avoiding collision with the plant building. The system has been applied to replacement tasks of an existing boiler building of a power plant. The building is expressed by over 5 GB stereo-lithography binary data. © 2014 The Authors. Published by B.V. Source

Stein-Brzozowska G.,Mitsubishi Hitachi Power Systems Europe GmbH | Bergins C.,Mitsubishi Hitachi Power Systems Europe GmbH | Kukoski A.,Mitsubishi Hitachi Power Systems Americas Inc. | Wu S.,Mitsubishi Hitachi Power Systems Americas Inc. | And 2 more authors.
Journal of Energy Resources Technology, Transactions of the ASME | Year: 2016

In terms of CO2 emissions, the year 2030 has been addressed as a very crucial deadline for both European Union (EU) and the U.S. Whereas the U.S. Clean Power Plan proposes the reduction of national CO2 emissions from the existing power stations by 30% with respect to 2005, the EU aims at cutback by 40% from their levels in 1990. Due to the restricted emission goals dictated by the European and U.S. energy policies, both energy markets witness currently drastic changes. Whereas the U.S. wants to shift away from coal, the EU shifts away from gas due to high natural gas prices in Europe while drastically increasing the feed-ins from renewable energy sources (RES). In some of the European countries constantly growing installation of renewable energy plants is superseding natural gas-fired power plants and thus causing the electrical grid stabilization to be overtaken by coal fired power stations. On the contrary, the U.S. market due to increasing extraction of shale gas and low natural gas prices puts the gas power plants in favor and poses increasing pressure on closing some coal fired plants. A solution that uses the potential of the existing site and reduces overall emissions is converting from coal into gas-fired power plants, so-called fuel switch. Whereas for the U.S. market the later solution is relevant, in the vast majority of EU Member States the focus is on increasing the flexibility of coal fired power plants. The challenges and technical solutions developed and applied according to the demands of the market in both EU and U.S. are addressed in this paper. Both currently applied technologies and technologies under development are shortly presented. Copyright © 2016 by ASME. Source

Okabe A.,Hitachi Ltd. | Enomoto A.,Hitachi Ltd. | Fuji N.,Hitachi Ltd. | Nonaka Y.,Hitachi Ltd. | And 4 more authors.
Procedia CIRP | Year: 2016

When a component is replaced in the maintenance of a large plant, for example several dozen meters size, the replacement-operation's cost is highly affected by its transportation route in the plant. When a component is transported by an overhead-crane, the number of corners in the route is desired to be minimized because it represents the number of required lanes, which affects the cost. Given that the corner count is minimized, maximizing average collision margin, which is represented by the average distance between the component and the obstacles in the plant, is required to reduce the workload of adjusting component's postures to avoid collision. The route length comes as the third factor. Dijkstra method, which is a well-known route-finding method, only accepts factor which increases or decreases monotonically during route-finding. While factors with monotonic trend such as corner count and route length can be optimized by Dijkstra method, we could not optimize average collision margin which is non-monotonic-trend factor in our previous work. In this paper, we propose an improvement on route-finding method so that it can optimize multiple factors for plant maintenance including average collision margin, a factor with non-monotonic trend. The proposed method optimizes average collision margin using Dijkstra method by introducing cascade evaluation of multiple factors with vector cost function and limiting the update condition for average collision margin during route-finding. The proposed method is evaluated with an actual plant data. The evaluation result shows that the average collision margin of a route found by the developed method was improved by maximum 17% with the same corner counts compared to the previous method using a weighed sum of the factors. © 2016 The Authors. Source

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