Pilot Plant for Solar Process Steam Supply
K. Hennecke,1* T. Hirsch2, D. Krtiger1, A. Lokurlu3 and M. Walder4
1 DLR - German Aerospace Center, Linder Hohe, 51147 Koln, Germany
2 DLR - German Aerospace Center, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany
3 Solitem, Susterfeldstr. 83, 52072 Aachen, Germany
4 Alanod, EgerstraBe 12, 58256 Ennepetal, Germany * Corresponding Author, klaus. hennecke@dlr. de
Abstract
An aluminium upgrading process will be supplied by steam directly generated in parabolic trough collectors. In this first of it’s kind installation in an industrial environment, steam at 4 bar will be fed into the existing distribution lines of the production to heat anodizing baths and storage tanks. The integration of the solar steam through separate heat exchangers in parallel to the existing system was also considered. In principle, due to the low temperatures of the baths, solar hot water systems could be integrated in the same way. However, the additional heat exchangers and pipelines between the solar system and the consuming process generate significant investment cost on top of the solar system. The selected integration of the solar steam generator in parallel to the existing boiler reduces the complexity of the system, saves cost by avoiding duplication of piping and heat exchangers, and provides flexibility in the operation to ensure security of supply and maximum use of available solar energy.
Keywords: Renewable energy, solar process heat, process steam, direct steam generation
Industrial process heat accounts for about 28% of the total primary energy consumption for final uses in EU25. More than half of that demand is required at temperatures below 400°, making it a promising and suitable application for solar thermal energy. Nevertheless, only an almost negligible fraction of the total solar thermal capacity presently installed is dedicated to this application [1]. The collaborative Task 33/IV of the Solar Heating and Cooling program and the SolarPACES program of the International Energy Agency (IEA) aimed to support a more wide spread application of solar heat for industrial processes by
• Assessing the potential and identifying most promising applications for solar technologies in industry
• Developing methods for the design and integration of solar systems for industrial applications
• Developing and testing of collectors for medium temperatures up to 250°C, and
• Initiating and monitoring of pilot plants.
In support of these efforts, the P3 project (Pilot plant for solar Process heat generation in Parabolic trough collectors) was started in February 2007 with the goal to demonstrate the direct steam generation in small parabolic trough collectors for industrial applications. The pilot plant will be installed at the production facilities of ALANOD in Ennepetal, Germany. One of the products of this aluminium anodizing plant is MiroSun™, an aluminium based mirror also used as reflector
material in the SOLITEM PTC 1800 parabolic trough collector. Scientific support for the development of the solar system design, integration, operation and control concepts is provided by DLR. The future operation will be closely monitored and evaluated by Solar Institute Julich and ZfS Rationelle Energietechnik GmbH. Although the site provides less than ideal solar radiation conditions, precedence was given to the relatively close neighbourhood of the project partners supporting the successful realization of this innovative application. To limit technical and financial risks, the solar field is restricted to a moderate size of 108 m2 aperture area. An economic operation is not expected under these conditions. However, ALANOD regards the opportunity to demonstrate on site the utilization of their product in innovative applications as an additional benefit.
