Fachinformationszentrum Karlsruhe

Processing metal with solar energy

Solar-generated saturated steam fed into steam network at 140 °C
In Germany, industrial process heat comprises around 10% of the energy requirements. Part of it can be generated with solar thermal systems. Using twelve collectors that track the sun’s position, a metal processing company in Ennepetal, Germany, has for the first time generated saturated steam and integrated it into an existing steam network. The pilot system is presented in the new BINE-Projektinfo brochure “The sunny side of saturated steam” (11/2011). In this research project, the process’s operational basis for utilising solar process heat was tested and optimised, whereby a particular focus was on the future use of such systems in more southern parts of the globe.

Saturated steam is steam produced at the saturation temperature and is used in many industrial production processes up to 200 °C. In the pilot system, steam is generated directly in the absorbers within the parabolic trough collectors, thus eliminating the need for a special heat exchanger. This improves the efficiency. A company in the aluminium-finishing sector has integrated the solar steam generator into its existing steam network. Here, the steam is used to quickly heat various chemical baths to temperatures between 60 and 110 °C. As expected, the solar yields from this pilot system were relatively low, which is partly due to the limited collector surface area. The project itself, however, was deemed to be successful because it enabled a highly promising process for generating and directly feeding solar steam to be realised and tested in long-term operation. The process could also be used in other sectors for drying and heating processes and for solar refrigeration.

In order to achieve temperatures above 100 °C with solar heat, concentrating collectors are deployed. The pilot system uses parabolic trough collectors – a technology in which German companies are among the best in the world. The BINE Projektinfo brochure “The sunny side of saturated steam” (11/2011), which can be obtained free of charge from the BINE Information Service at FIZ Karlsruhe, is available online at www.bine.info.