CO2-neutral Process Heating for Carburizing Furnaces – an Ecological Analysis*

Abstract In order to achieve the goal of a massive reduction of CO2-emissions, fossil fuels have to be substituted. In Germany, continuous carburizing furnaces for high capacities are almost exclusively fired by natural gas due to the lower energy costs. Electrical heating and hydrogen combustion are obvious alternatives. While electrical heating elements are state-of-the-art for these types of furnaces, hydrogen combustion has not been investigated. Furthermore, these two alternatives strongly depend on the specific energy mix, which determines the CO2-emissions. This case study compares different process heat generation options for continuous ring hearth furnaces for carburizing automotive steel parts by a quantitative approach. The investigated alternatives are natural gas/air heating as the reference, electrical heating and hydrogen/air heating. Besides the energy balances, primary energy consumption and resulting CO2-emissions are calculated. Furthermore, possible developments until 2050 are analysed. The results show that both alternative cases have a high potential to decrease CO2-emissions which strongly depend on the development of the energy mix and, therefore, the future expansion of renewable energy sources.