Abstract: The present invention relates to a device for blowing preheated air into a shaft furnace, comprising several separate tubular elements, wherein an outer shielding made of steel and an inner lining made of cast refractory concrete are connected in pairs by a ball joint and a compensator. The ball joint includes a convex pivot which is integral with a first tubular element and which can pivot in a concave dish integral with a second tubular element. At least the convex pivot of the ball joint comprises a profiled refractory brick anchored in the inner refractory lining made of cast refractory concrete.

Abstract: A device is presented for injecting preheated air into a shaft furnace and comprises of a plurality of tubular elements provided with a refractory lining, which are connected to each other by a ball-and-socket articulation and an expansion joint. The ball-and-socket articulations comprise a convex ball portion formed in the refractory material of the adjacent segment. They comprise a protective shell made of refractory steel which extends around the convex part up to the base of the ball portion. The radius of curvature of each ball-and-socket articulation is in the range of magnitude of half the diameter of the tubular elements.

Abstract: The device comprises an oblique portion connected by a gooseneck, a nozzle, atuyere and a ball-and-socket joint to the wall of the furnace, in which the oblique portion comprises a tapered tube flange-mounted by its upper part onto an upper connection piece forming part of a bustle pipe and the lower part of which dips axially into a lower connection piece integral with the gooseneck, a bellows expansion joint and tension rods ensuring the mechanical connection between the tapered tube and the lower connection piece. The lower connection piece and the tapered tube can move mutually in the axial direction and have means for limiting their radial mobility.