During the scheduled shutdown in August, the Celsa 3 plant took a decisive step forward in the Twinghy project. Eight new burners were installed in the reheating furnace at the Barcelona rolling mill. Designed and developed by our partner Fives, they are ready to operate with hydrogen in the future.
In a reheating furnace, the burners mix a fuel—currently natural gas—with an oxidant (air or oxygen) to generate the flame that raises the temperature of the steel before rolling. This process presents a major challenge from a thermal efficiency standpoint, given its high energy consumption due to the need to ensure uniform heating of the load, which is essential for the quality of the rolled product.
The first week was devoted exclusively to allowing the furnace, which normally operates at temperatures above 1,200 °C, to cool down. Subsequently, the teams organised themselves into continuous shifts, 24 hours a day, 7 days a week, to carry out the tasks in record time.
The challenge was enormous: never before had so many burners been replaced simultaneously in such a short period of time. As Joan Jiménez, maintenance manager at Celsa and project coordinator, explains:
‘The biggest challenge was the complexity of combining a set of interdependent tasks in a short period of time. Usually, one or two burners are replaced per year, but never before had so many changes been made at once.’
The new burners are larger than the previous ones, which required the installation of new natural gas piping, the addition of extra valves and the complete renovation of the furnace’s refractory material, a task carried out by Calderys.
Moving the eight units, due to their weight and dimensions, was one of the most significant difficulties. The team devised a specific handling system that allowed the operation to be completed safely and efficiently in a confined space of just 10 m².
The burners are now running on natural gas and maintain the same CO₂ and NOx emission levels as the previous equipment, despite their larger size. Imanol Bilbao,from Fives, also points out: ‘It is very noteworthy that it will be possible to switch to hydrogen supply without having to shut down the furnace.’
Ahead of the December shutdown, the piping will be adapted for hydrogen use and the burners supplied by Nippon will be installed. This will enable the first tests to begin in 2026 to partially replace natural gas with green hydrogen, using different mixing ratios, and to assess its impact on product quality.
With this advance, Twinghy first ensures environmental and operational equivalence with natural gas and, next year, will conduct tests partially replacing the natural gas supply with green hydrogen. Thus, the project continues its commitment to the decarbonisation of the steel industry.