Tenova LOI Thermprocess’ HPH®-BAF for thyssenkrupp


Tenova LOI Thermprocess’ HPH®-BAF for thyssenkrupp

thyssenkrupp Hohenlimburg achieved CO2-neutral heat treatment of precision strip in an Ultra Low NOx HPH®-flameless Bell-type Annealing Plant by Tenova LOI Thermprocess

Tenova LOI Thermprocess collaborated on a project with thyssenkrupp Hohenlimburg GmbH to prove that CO2-neutral heat treatment can go together with low nitrogen oxide (NOx) emissions.

Traditionally fueled by natural gas, bell-type annealing plants perform precipitation and spheroidizing annealing of steel coils to tailor mechanical properties for subsequent rolling processes or meet specific product requirements for end customers. At thyssenkrupp's Hagen-Hohenlimburg site, Tenova LOI Thermprocess has successfully employed its latest generation heating hoods featuring the patented Ultra Low NOx HPH®-flameless concept for approximately 12 years. The innovative technology, characterized by significantly increased air preheating temperatures of 600°C, has resulted in energy and CO2 savings of up to 12%.

In a joint project aimed at decarbonizing steel production, a further significant milestone has been reached through a series of annealing cycles. Production trials involved the gradual transition of fuel gas supply for the heat treatment of hot-rolled narrow strip from natural gas to up to 100% hydrogen. Notably, 70 t of steel strip were heat treated in a bell-type annealing plant using Tenova LOI’s HPH®-flameless technology, marking the world's first locally CO2-neutral process. Despite the higher combustion temperature and the associated potential for increased nitrogen oxide emissions compared to natural gas, the flameless concept demonstrated remarkably low NOx emissions.

To facilitate the flexible delivery of natural gas/H2 mixtures, a specially designed mobile natural gas/hydrogen mixing station was deployed during the annealing process. This allowed for an assessment of the impact of increased hydrogen admixtures on the overall system. A special trailer supplied the increased hydrogen needed for annealing cycles due to the lower calorific value, feeding it directly into the pipework systems of the bell-type annealing plant.

The success of this project affirms that Tenova LOI Thermprocess's Ultra Low NOx HPH®-flameless bell-type annealing plant is well-suited for use with hydrogen. The utilization of regeneratively produced hydrogen can result in savings of up to 2600 kg of CO2 per annealing cycle, maintaining productivity and product properties.


Jan Bernhofen
Jan Bernhofen
Team Coordinator Processing, thyssenkrupp Hohenlimburg GmbH

"The project is part of thyssenkrupp Steel Europe's long-term decarbonisation strategy and includes the goal of achieving climate neutrality in all downstream production processes by 2045 at the latest, in addition to iron and steel production.”

Dr. Gökhan Gula
Dr. Gökhan Gula
Project Manager and Process Engineer, Tenova LOI Thermprocess

"The combustion of hydrogen is technically more complex than the direct use of electricity or the combustion of natural gas. This project has provided us with further insights into the decarbonization of the bell-type annealing process and is helping us on our joint path towards the transformation to climate-neutral steel production. Tenova LOI Thermprocess supplies the suitable technologies for a wide variety of plant types.”

Want to know more?

Get in touch with our experts on the subject

Submit your request

By submitting your request and accepting the terms of this information, you declare that you have read and understood Tenova’s Privacy Policy about the processing of your data for the sole purpose of responding to your query.
For more details and the data retention period, please refer to the above-mentioned Privacy Policy.