The downleg designed by SAB is lined with a thermal isolation in the appropriate areas. This method is already well-known and used in hot blast valves.
Depending on the design, the external temperature on the pipe can be reduced to approx. 150 degrees Celsius. This means that the corresponding energy losses on the tuyere stock can be reduced. This was first successfully used at ArcelorMittal Bremen, followed by ArcelorMittal Lìege.
The thermal isolation used by us is a microporous thermal insulator with extremely low thermal conductivity coefficients. It is made from inorganic, siliceous substances. The main component is fine-particle silicic acid. The remaining components are opacifiers to minimise infra-red radiation. For flexibility and manipulation reasons, the thermoblocker is welded into a P A/PE composite film system.
By using a spherical insert with a refractory lined sphere in the frontal convex part, instead of a spherical insert made of stainless steel, the various expansion factors of both materials can be eliminated. This prevents the refractory from breaking off early in this area. At the same time, the spherical insert is screwed in, which reduces the dismantling/removal work, and ensures reusing of the spherical insert shell.
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