As we close the second phase of TWINGHY, we would like to highlight two technical tasks that have now been completed and that are particularly relevant for the next stage of the project.

Before introducing hydrogen into a reheating furnace under operational conditions, we needed to better understand its impact on two critical elements: the steel surface and the refractory lining. These questions have guided the work carried out over the last period of the project.

At the University of Oulu, the focus has been on mill scale formation. When steel billets are heated before rolling, a thin oxide layer naturally forms on the surface. Changing the combustion atmosphere by introducing hydrogen can influence how this layer develops. The study confirmed that while hydrogen-rich conditions can slightly modify the amount of scale formed, the overall structure and behaviour of the oxide layers remain consistent with current industrial practice. This is a positive result, as it indicates that product quality can be maintained during the transition.

In parallel, RWTH Aachen University analysed how refractory materials respond to hydrogen-containing atmospheres. The results show that the main refractory materials used in the furnace remain stable under the tested conditions. No critical degradation mechanisms were identified, providing reassurance that the furnace structure can withstand the new operating environment.

Together, these studies reduce uncertainty and strengthen our technical position as we prepare for hydrogen trials.

At plant level, the installation of the new hybrid burners at the Celsa 3 facility represents a significant milestone for the project. Meanwhile, development of Digital Twin is progressing so that it can be validated against real operational data.

The foundations are now in place. Our focus is clear: to move into the pilot phase fully prepared and continue advancing TWINGHY towards demonstration in an industrial environment.

The most exciting stage is about to begin!