Device for injecting preheated air into a shaft furnace

DETAILED DESCRIPTION The object of the present invention is to provide a novel device for injecting preheated air into a shaft furnace which is relatively simple and inexpensive and which adapts satisfactorily to deformations and stresses.
In order to achieve this objective, the device proposed by the present invention includes a plurality of separate elements, each consisting of an external armoring and an internal refractory lining, and comprising an oblique portion connected by a gooseneck, a nozzle, a tuyere 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 ensuring the sealing between the tapered tube and the lower part, and tension rods ensuring the mechanical connection between the tapered tube and the lower connection piece and is essentially characterized in that the lower connection piece and the tapered tube can move mutually in the axial direction and have means for limiting their radial mobility.
In other words, the problems of mastering the radial components of the forces, and the displacements which caused the sealing pad to be crushed at the articulation of certain blast connections according to the prior art are eliminated using means for limiting the radial or angular mobility of the tapered tube and of the lower connection piece, and compensated for by a relative axial mobility, or telescoping, of these two elements.
It has been established that, if these means are designed to prevent an axial misalignment of more than 2.
degree.
between the tapered tube and the lower connection piece, satisfactory results can be foreseen.
According to a first embodiment, these means consist of two flanks integral with a flange of the upper connection piece which extend laterally, when viewed in the direction of the furnace, on either side of the expansion joint and are guided in corresponding recesses of a flange of the lower connection piece