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.

Routes for Hydrogen Introduction in the Industrial Hard-to-Abate Sectors for Promoting Energy Transition

“…By blending hydrogen with natural gas, the carbon intensity of the combustion process can be lowered. This approach allows for a gradual transition by leveraging existing infrastructure while reducing carbon emissions [18][19][20].…”

NOx Emission Limits in a Fuel-Flexible and Defossilized Industry—Quo Vadis?

“…Different non-fossil fuels are under investigation for a wide range of applications, showing the significant efforts on the decarbonization of industrial combustion: theoretical studies [22,23], application-oriented H 2 demonstration projects [24][25][26][27][28][29], investigation of the use of H 2 /natural gas (NG) blends in industrial furnaces [30][31][32][33], and first full-scale furnace conversions [34]. As an alternative fuel, pure ammonia and blends are investigated in demonstration projects [35] and at lab scale [36][37][38][39].…”