CLU® – Superheated steam
Superheated steam in converter refining was jointly developed by Creusot-Loire in France and Uddeholm in Sweden, under the name CLU®. UHT, now as an independent company, continues to develop and market the process. The CLU® process is the most flexible refining process, both for stainless steel and ferroalloy production. By using steam as an additional process gas, all grades of stainless steel can be produced with low argon consumption, high productivity and low refractory wear.
When superheated steam enters the hot melt in the converter it decomposes into oxygen and hydrogen. The formed hydrogen gas acts as an inert gas to replace argon or nitrogen while the oxygen takes part in the carbon oxidation process.
Since the reduction of steam consumes heat, an additional cooling benefit is obtained in the CLU® process compared to conventional AOD, which means that the need for coolant material is reduced. Improved temperature control and reduced refractory contact time also leads to low refractory wear.
Superheated steam is especially efficient in production of nitrogen sensitive stainless steel products and MC and LC ferroalloys.
- 1 kg of steam substitutes 1.25 Nm3 Argon and 0.625 Nm3
- 1 kg of steam replaces 10 kg of coolant material
The CLU® process is for example currently used at Acerinox Columbus Stainless and Samancor Ferrometals in South Africa.