Approximately half of the energy in induction heaters is lost when the magnetic field is generated by copper coils and alternating current. While conventional heating methods achieve an efficiency of at most 50 percent, the new superconducting magnetic heaters achieve 70 percent. They can also be designed to be robust and low-maintenance. THEVA, Bültmann, Beck Maschinenfabrik and the KIT/ Institut für Technische Physik (ITEP) intend to jointly develop such a "RoWaMag" (robust and low-maintenance magnetic heater). The Federal Ministry of Economics has now approved the project application.
Specifically, the RoWaMag is to be used in a billet furnace that is part of a production line for the manufacture of extruded profiles. The magnetic heater will be equipped with built-in HTS magnets and second generation HTS conductors. Thanks to its compact design, a durable and robust cooling system and uninterrupted operation in the event of failure and maintenance of a cooler, the project participants expect a technically and economically forward-looking solution for the broad application of the magnetic heater.
In concrete terms, the 160 extrusion plants of the German aluminium industry alone could save 55,000 MWh of electricity per year, or 30 percent, by processing 800,000 tons of aluminium. This corresponds to the annual power generation capacity of 14 medium-sized wind turbines. CO2 emissions in this sector would decrease by more than 30,000 tons per year.
The idea is not new: already in 2009 Petra Bültmann-Steffin and Dr. Carsten Bührer received the German Environmental Award for their innovative induction heater based on high-temperature superconductor (HTS) technology. However, the project came to a standstill and a broad market breakthrough was not achieved because Zenergy Power had to file for bankruptcy.
Now the project is picking up speed again. "Our experience in the series production of second-generation high-temperature superconductors (HTSs) has convinced us that we can deal very well with the problems that arose at the time. These consisted of insufficient magnetic field strength, weaknesses in the coil design and cooling and the resulting downtimes. All this is now a thing of the past, as we have already proven in various projects," explains Dr. Werner Prusseit, Managing Director of THEVA, who is responsible for the production of the high-temperature superconductor and the development of the magnetic coil in the project.
If the targets are achieved, RoWaMag will be able to save 55,000 MWh of electricity per year and thus 30 percent in the 160 extrusion plants of the German aluminium industry alone by processing 800,000 tons of aluminium. This corresponds to the annual power generation capacity of 14 medium-sized wind turbines. CO2 emissions in this sector would decrease by more than 30,000 tons per year.
Induction heaters are used in industry for the production of profiles and pipes made of aluminium, copper, copper alloys and e.g. titanium and magnesium. The products are used, for example, for lightweight car bodies or for copper conductors in e-mobility. The increase in temperature ensures that materials are made soft and malleable. In this way, they can be specifically formed into the corresponding components - with considerably less effort. In contrast to other heating methods, induction ensures uniform heating and thus the best possible results and faster cycle times in production.