Drying apparatus

摘要

A vacuum drying apparatus or unit for hides and skins 16, Fig. 1, comprises a heating table 10 with heat lagging 11 on its upper surface removably mounted by a sealing strip 13 on the open top of an inverted suction hood 12 of deformable sheet material connected through a line 14 with a vacuum source. The hide is supported on a compressible porous element 17,e.g. of felt, which in turn is supported on a perforated metal sheet 18 above a metallic pressure-transmitting structure 19. Upward deformation of the hood 12 on application of suction acts through the supporting elements to apply the hide upwardly against the lower heating surface of the table. Moisture removed from the hide by heat, compression, and vacuum is withdrawn through the line 14. In a modification, Fig. 2 (not shown) the suction hood 12 is arranged for horizontal displacement. In a commercial drying plant, Figs. 3, 4 and 8 (not shown) a large diameter turntable has thereabout eight of the said drying units. Heating tables are described with either U-shaped tubes or a plurality of sections for the passage of heating fluid. In the apparatus of Fig.6 (not shown) the heating table 10 is fixed and the hood 12 is of metal and is vertically movable in a framework by ram activators for loading and unloading of hide carriers comprising the felt 17 and sheet 18 which are horizontally movable on a peripheral frame over horizontal runways. The line 14 may be connected to a condenser and separator tank. In a variety of embodiments and in Figs. 12 and 13 (not shown) the deformable hood 12 comprises a flat metal sheet peripherally secured to an outer frame. Means for separating the dried skin from the heating table comprise apertures at the edges of the table through which jets of air are downwardly directed. Alternatively, a fine wire may be stretched transversely of the table between a pair of drivers endless chains. The heating table 401, Fig. 22, has a lower surface 402 covered with a protective coating 403. A frame 404 is movable horizontally on rollers 405 for charging and discharging hides and skins. The frame is peripherally bonded to a flexible hood 409. A rigid metal sheet 409a is secured to the frame to prevent sagging of the hood. The frame 404 also supports the pressure-transmitting and hide-supporting structure 415 made of wire mesh elements. The effluent moisture is discharged into a tank 411 in a central opening of the hood 409 and suction is applied through a separate vacuum connection 419. In a modification, Fig. 24 (not shown) differential pressures in the spaces between the hood and sheet 409a and in the hood, respectively, may be achieved by using two suction conduits. In another construction, the head is connected through apertures in the heating table, to an upper source of vacuum.