Patent ID: 8109283

Claim:
A dry descaling apparatus for scale removal from a surface of a metal product comprising at least one heating area for heating the metal product, at least one reducing area for performing a reaction between a metal-oxide reducing gas and at least the scale, at least one area for cooling the metal product, first heating means for heating the metal product, second heating means for heating the reducing gas, means for removing reaction products from the reducing gas after reaction, means for removing reaction products which are left on the surface of the metal product after treatment, and means for cooling the metal product; a dry-pickling apparatus being characterised by the fact that it comprises first control means ( 16 , 17 , B 1 , C 1 ) for fluid dynamic control of the boundary layer produced by the flow of said reducing gas over the surface of said metal product wherein said first control means are adapted for generating regular pressure oscillations comprising overpressure and depression areas, which are repeated in succession along the entire surface of said metal product, the overpressure areas being associated with a reducing gas blowing stage towards the surface of said metal product, the depression areas being associated with a reducing gas evacuation phase downstream of the blowing stage, means for purging and recycling reducing gas after reducing operation of the scale, third control means for controlling reducing gas temperature; wherein said first control means comprise a plurality of coaxial Venturi ( 16 , 17 ) tubes placed at a reciprocal distance between 10 mm and 1500 mm and having their axis positioned along the conveying direction of the metal product.