Abstract: Segmented conduits for transmitting heated fluid, and particularly tuyere feed lines for injecting preheated air into shaft furnaces, have an annular cooling chamber incorporated into the coupling joints between conduit sections. The cooling chambers are positioned inwardly toward the conduit axis with respect to flexible bellows devices which heremetically seal the articulated coupling joints.

Abstract: Intercrystalline stress corrosion of the walls of heat exchangers employed to produce hot air for injection into a blast furnace, particularly the wall of the passage interconnecting the combustion and heat exchange chambers, is avoided by eliminating pressure differentials across the walls. Also, the walls of the heat exchanger are heated to a temperature above the condensation point of deleterious vapors present or formed in the apparatus to thereby further minimize the possibility of occurrence of stress corrosion.

Abstract: A hermetic expansion joint employing an external bellows and means positioned within the bellows for limiting the relative axial displacements of the conduits being joined in both compression and tension. The expansion joint device has, located within the annular chamber defined by the bellows, a layer of compressible refractory material which bridges the joint between the conduits and a shielding tube which envelopes the compressible refractory material. The expansion joint device is further provided, on oppositely disposed fittings which connect the bellows to the conduits, with means for limiting the axial width of the joint.

Abstract: A tuyere stock wherein the blast nozzle, which is the downstream section of the stock, is rigidly coupled to the blast tuyere through which the preheated gas is injected into the furnace. The blast nozzle-blast tuyere assembly and a cooling jacket, which is mounted in the furnace wall about the aperture through which the tuyere stock passes, cooperate to define an articulated connection whereby thermally induced distortions of the various components of the stock may be accommodated without interrupting the sealing efficiency of the connection.

Abstract: A method of and apparatus for cooling and cleaning the sealing surfaces of the sealing valves of a material storage hopper which are subjected to the high temperature and pressure within a shaft furnace. The method comprises introducing a cooling medium into the charging installation of the furnace and causing the coolant to continuously impinge upon the sealing valves. The apparatus includes a rotatable sealing flap having a sealing surface of resilient material and a cooling fluid supply conduit for directing a flow of cooling fluid towards the sealing surface of the flap when the flap is in its opened position.