GB879091A - Improvements in and relating to thermal treatments at high pressure - Google Patents

Abstract

Apparatus for treating materials in long lengths at a superatmospheric pressure comprises a closed chamber with two endless conveyers arranged with the material therebetween, characterized in that the conveyers during passage through inlet and outlet slits in the chamber cooperate with sealing arrangements, each of which has a deformable element fixed at one edge to the wall of the chamber at some distance from the slits and resting, at its other edge, on the surface of the conveyer, the whole being arranged so that the internal excess pressure presses the last-named edges against the surfaces of the conveyers. The high pressure chamber 1, Fig. 1, has a jacket 2 heated by vapour supplied through a conduit 3 and inlet and outlet slits 4, 5 having sealing elements for the passage of conveyer bands 6, 7 driven by drums 9, 11 and having adjustable drums to adjust the tension of the bands. The material is fed between the bands by variable speed rollers 22, 23 and conveyed through the chamber between the bands supported by intermediate rollers to a rewind spindle 24. A conduit 25, Fig. 2, supplies treatment fluid to the chamber which is removed by an exhaust 25a and the chamber may have additional heating elements 36a in the form of steam coils, electrical resistances or like heaters. Each sealing element comprises elastic jointing elements 13, 14, Fig. 5, mounted on resilient metal elements 16, 17 secured to the chamber wall above and below the conveyer, respectively, and having strips 15 of a self-lubricating material mounted on the edges, which strips are pressed into contact with the surface of the bands 6, 7. The resilient elements 13, 14 may be replaced by rigid, hinged elements or the elements may be formed of short segments instead of single piece covering the whole width of the slits. The endless bands may be of thin stainless metal with polished surfaces, or coated with a non-metallic insulating material, or the bands may be perforated with the dimensions of the perforations being less in the direction of travel of the bands than the width thereof, or the perforations may be covered by a nonperforated band comprising short strips that transversely overlap to facilitate passage of the bands and strips through the slits and which lift slightly from the perforated bands during their travel through the drying chambers. In a modification, Fig. 3, (not shown), the bands separate after entering the interior of the chamber and the passage of the material is effected in a sinuous path by two series of intermediate rollers to elongate the duration of stay of the material within the chamber. In a further modification, Fig. 4, (not shown), the material passes through an impreg <FORM:0879091/IV(c)/1> <FORM:0879091/IV(c)/2> <FORM:0879091/IV(c)/3> <FORM:0879091/IV(c)/4> nation vat within the treatment chamber. In another modification a cylinder 42, Fig. 8, rotated by a motor 43 and having heating elements 69, 70 is mounted within the high pressure chamber 41 which has slits 44, 45 with seals 52, 521, 53, 531 for the endless bands 46, 47. An air lock 48 having slits 49, 50 with seals 54, 541, 55, 551 protects the slits and has a discharge conduit 51 for evacuating gases escaping from the chamber. The band 46 passes around the cylinder and the shorter band 47 which is driven by an adjustable roller 57, serves to protect one surface of the material during its passage through the air lock.