Pass-through furnace for heat recovery in the heat treatment of aggregates of metallic articles or parts

Claim 1

Pass-through furnace for heat treatment of metallic articles or parts comprising: a furance chamber having adjacent preheat, treatment and cooling zones interconnected so as to permit passage of said articles or parts through said zones in direct succession, said preheat zone having a work input region and said cooling zone having a work output region, said furnace chamber also having a flow path (S31, 32; 33) through said treatment zone (7) for heat-transferring gas, which path connects said preheat (6) and cooling (8) zones for said gas; means for transport successively through said preheat, treatment and cooling zones of said articles or parts, in batches in the form of aggregates permitting interstitial passage of gas therethrough, said transport means being consituted so as to permit flow of gas vertically through said aggregates and being further constituted to advance said aggregates intermittently through said said zones in steps of at least one entire batch space, said transport means including batch carriers for said articles or parts having bottom partitions provided with apertures for flow of gas therethrough and having end portions fitting substantially gastight in abutment with an end portion of another one of said batch carriers, and means for producing and directing a flow of heat transferring gas through said cooling zone, said flow path of said chamber connecting said cooling and preheat zone and said preheat zone of said furance chamber in succession and for constraining said gas to flow vertically through said aggregates in said cooling and preheat zones in transverse countercurrent to the advancement of said aggregates through said zones, said gas flow producing and directing means including channels provided below said transport means for for providing access and removal of said gas through and from said aggregates through portions of said transport means which are contituted so as to enable passage of gas therethrough, said channels being closed off at the top by the apertured bottoms of said batch carriers disposed in close abutment to each other for constraining gas to flow vertically through said batch carriers and their contents, and including also a valve-controlled return line (22,17) having a blower (19) interposed therein for causing flow of said gas coming out from the work input region of said preheat zone (6) through said return line and into the work output region of said cooling zone (8).