The three integral gear units will be used in the compressors of a direct reduction plant of the SALCOS (Salzgitter Low CO2 Steelmaking) project at the Salzgitter site in Germany.
The gear units are developed and built at the Renk site in Winterthur, Switzerland. They are used in a direct reduction plant in Siemens compressors. In direct reduction, iron ore is converted into sponge iron with the help of a reducing agent. In the process, the reducing gas dissolves the oxygen out of the iron ore without it melting. This process takes place in the direct reduction plant at overpressure and at about 1,050 °C. The iron ore is reduced to sponge iron. Instead of CO2, this technology produces water, which in turn is reused in the integrated process. In a direct reduction plant, both natural gas and hydrogen can be used flexibly as reducing agents. In this way, the natural gas content is gradually reduced and finally completely replaced by hydrogen.
Thomas Fritschi, managing director of Renk-Maag in Winterthur, said: “Our high-speed gear units for compressors are an important component for the ramp-up of the hydrogen economy – whether for storage, processing or transport. These turbo compressors are characterised by a high pressure build-up and are suitable for large gas volumes. Specifically, we are talking about gear units with a speed of 8,000 to 50,000 revolutions per minute – but we have also produced units with a speed of over 60,000 revolutions per minute. Just for comparison, the engine speed of a passenger car in normal driving is a maximum of 2,000 to 3,000 revolutions per minute.”