Research PaperLow scale reheating of semi-finished metal products in furnaces with recuperative burners

- Low scale reheating of copper and steel products applying fuel rich combustion.
- Post-combustion and heat transfer in recuperative burners.
- Low NOX emissions due to fuel rich combustion and post-combustion.
- Cost reduction for reheating of high-priced metal products.

Industrial furnaces for reheating semi-finished metal products are often direct fired with natural gas and air. Oxidation of the metals exposed to the furnace atmosphere causes significant material losses and additional work during furnace operation and in further processing. A reheating concept, which reduces scale formation, was developed for direct fired reheating furnaces. It involves fuel rich combustion, post-combustion of the unburned off-gas and efficient preheating of the combustion air. This paper focuses on the reheating of copper and steel in direct fired furnaces with recuperative burners. Therefore, the post-combustion in an annular gap, according to a recuperative burner was examined, concerning temperature profile in the gap and off-gas emissions, to determine technical limits of the concept. Based on energy balances and scale formation the costs for fuel and metal loss were calculated to determine economic impact on the reheating process. The results show economic potential of the concept in terms of cost savings for the reheating of copper with a fuel rich combustion but no significant cost savings for the reheating of steel.