Equipment for heat-treating flat, band-like lengths of material

Claim 1

In heat-treating equipment for flat, band-like lengths of materials supported on a gas-permeable perforated conveyor means, using a gaseous flowing drying medium, said equipment being composed of a thermally insulated housing with transmission slots at both ends for a length of material, nozzle conduits arranged in sequential spacing above and below the length of material and directed transversely to the direction of motion of said material and being provided with nozzles and communicating with pressure chambers, at least one heat exchanger connected to suction chambers above and below the length of material, and at least one circulating fan communicating with said nozzle conduits and suction chambers, the improvement comprising that the upper and lower nozzle conduits include ledge means between the spacings of the nozzles extending transversely to the length of material and forming together a backflow cross-cut means, the backflow cross-cut means between the ledges of the upper nozzle conduits being covered with stop means reducing the open area of said backflow cross-cut means and flow therethrough, and the backflow cross-cut means between the ledges of the lower nozzle conduits and between the lower nozzles of a lower nozzle conduit being open toward a suction chamber, whereby a uniform discharge of drying medium is obtained from the upper and lower nozzle conduits, and a differential evacuation of drying medium in the suction chambers above and below the length of material.