IGF project 17810 N

Process development for non-scaling reheating of metallic semi-finished products

The aim of this project is the further development of direct firing of furnaces for the heating of metallic semi-finished products by burners with preheated combustion air in order to improve resource and energy efficiency. By means of a sub-stoichiometric air ratio in the furnace chamber, a low oxygen partial pressure is set and the material loss due to scale formation in copper and unalloyed steel is reduced. A three-stage process is developed which uses the energy of the incompletely burnt fuel in the furnace chamber for recuperative or regenerative air preheating.

The experimental investigations show an almost complete reduction of the scale quantity for copper and copper-nickel alloys with an air number of 0.96. For steel the scale quantity is halved with a reduction of the air number from 1.15 to 0.95. The generation of a sub-stoichiometrically burnt furnace atmosphere is possible with a conventional recuperative burner. A process window is determined as a function of burner output, air number and air preheating. Afterburning takes place in an annular gap or pipe geometry. For a complete CO burnout, afterburning must be carried out upstream of the heat exchanger. A process window for the stable operation of the post-combustion is determined as a function of the primary air number, the secondary air volume and the exhaust gas and air preheating temperature. The CO emissions after post-combustion are significantly less than 150 ppm and the NOX emissions are significantly less than 50 ppm.

An overall technical and economic analysis shows that the process can be used for sub-stoichiometric combustion with an air number greater than 0.95. The air number of the combustion chamber is 0.95. The air number of the combustion chamber is 0.95. The greatest potential for economic improvement through the use of the process is available for copper and copper-nickel alloys as well as the heating of steel with a central recuperator.

Publications within the project

Schwotzer, C.; Schnitzler, M.; Pfeifer, H.; Ackermann, H.; Diarra, D.: Low scale reheating of semi-finished metal products in furnaces with a central recuperator, heat processing, 14 (2016), Nr. 3, S. 83-89

Schwotzer, C.; Schnitzler, M.; Pfeifer, H.: Zunderarme Wiedererwärmung von Metall-Halbzeugen mit Rekuperatorbrennern, Gaswärme International, 65 (2016), Nr. 3, S. 67-72

C. Schwotzer, M. Schnitzler, H. Pfeifer, H. Ackermann, D. Diarra: Untersuchung der Energieeffizienz und Abgasemissionen eines Verfahrens zur zunderarmen Wiedererwärmung von Metall-Halbzeugen, ProcessNet Fachausschuss Hochtemperaturtechnik, 10.-11.03.2016, Erlangen-Nürnberg

C. Schwotzer: Experimental investigation of a concept for scale free reheating of semi-finished metal products – example copper, Aachen-Freiberg-Magdeburger-Kolloqium, 07.-08.10.2015, Magdeburg

C. Schwotzer, M. Schnitzler, H. Pfeifer: Untersuchung der Abgasnachverbrennung für ein Verfahren zur zunderarmen Wiedererwärmung von Metall-Halbzeugen, 27. VDI Flammentag, 16.-17.09.2015, Clausthal-Zellerfeld

T. Lummerich: Technisch-ökonomische Analyse eines Verfahrens zur zunderarmen Wiedererwärmung von Metall-Halbzeugen, Bachelorarbeit, RWTH Aachen, Institut für Industrieofenbau und Wärmetechnik, 09.2015

C. Schwotzer: Verfahren für eine zunderarme Wiedererwärmung von Metall-Halbzeugen, 6. GWI Praxistagung, 14.-15.04.2015, Essen

C. Schwotzer, T. Balkenhol, M. Schnitzler, H. Pfeifer, H. Ackermann, K. Lucka: Experimental investigation of a concept for scale free reheating of semi-finished metal products, European Conference on Industrial Furnaces and Boilers (INFUB), 07.-10.04.2015, Porto, Portugal

C. Schwotzer, M. Schnitzler, H. Pfeifer, H. Ackermann, K. Lucka: Experimental investigation of a concept for scale free reheating of semi-finished metal products, European Combustion Meeting (ECM), 30.03.-02.04.2015, Budapest, Ungarn

C. Schwotzer, M. Schnitzler, H. Pfeifer, H. Ackermann, K. Lucka: Verfahren für eine zunderarme Wiedererwärmung von Metall-Halbzeugen, ProcessNet Fachausschuss Hochtemperaturtechnik, 19.-20.02.2015, Rheinfelden

T. Balkenhol: Experimentelle Untersuchung zum Einfluss der Ofenatmosphäre auf das Oxidationsverhalten von Metall-Halbzeugen, Masterarbeit, RWTH Aachen, Institut für Industrieofenbau und Wärmetechnik, 09.2014


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The IGF project 17810 N of the Forschungsvereinigung Forschungskuratorium Maschinenbau e.V. was funded by the AiF within the framework of the programme for the promotion of joint industrial research (IGF) of the Federal Ministry of Economics and Energy on the basis of a resolution of the German Bundestag.

Further information and the final report can be obtained from the Forschungskuratorium Maschinenbau e.V., Lyoner Straße 18, 60528 Frankfurt, Germany or info@fkm-net.de