GB949769A - Method of and apparatus for dewatering wet webs of papermaking fibres - Google Patents

Abstract

949,769. Dewatering wet webs of paper-making fibres. HUYCK CORPORATION. Dec.28, 1962 [Jan. 4,1962], No. 48777/62. Heading D2A. A wet web 29 of paper. fibres is deposited on a straight upper run 27 of a first, foraminous, synthetic fibre, moving carrier belt 23 and the upper surface of the web is then brought into contact with a second similar belt 33 and the three ply assembly so formed is caused to travel around sharply curved paths 37, 43 defined by parts of the surfaces of rotating guide rolls 35, 39, water being ejected from the assembly in passing around the rolls. Ejection of the water is the combined result of centrifugal forces and of the working of the web which results from the stretching of one (the outer) belt and the web face in contact therewith, and the compressing of the other, inner, belt and web face. The carrier belts which may for example be of nylon, or of acrylic, polyester or vinyl, fibres, allow water to be expressed freely while preventing damage to the surface of the web. Ejection of water may be assisted by causing streams of hot or cold air or other gas or superheated steam to pass through the web in the region of the sharply curved paths and to this end the roll 35 is provided with a perforated outer shell through which air is forced by air supply means 68, shown in greater detail in Fig. 2 (not shown). Since water is ejected on the upper side of the three ply assembly in its passage around roll 39 there is a danger of reabsorption of water in this region and for this reason suction means 71 are preferably provided on the outer side of the web at the roll 39. Doctors 59a and 60 may be provided to assist in the removal of water. In a modification (Fig. 3 not shown), the paper stock is discharged from pressure forming inlet means almost directly into the nip of the two carrier members which are trained, one around a breast roll and the other around a slice roll mounted above the breast roll. To provide adequate initial drainage in this case the breast roll may be of open-vaned construction. In a further modification (Fig. 4 not shown), the pulp is supplied by a vertical conduit to a first carrier belt on a breast roll and is formed and initially dewatered as it travels around a part of the circumference of the breast roll before contacting the second carrier member. Specification 827,754 is referred to.