Patent GB-775285-A (GB)
Title: Improvements in or relating to apparatus for increasing the consistency of fibrous suspensions
Inventor: COOK ERNEST PARISH
IPC: D21F1/66
Filed: 1955-07-06
Abstract: 775,285. Presses for separating liquids from solids. BROWN, CO. July 6, 1955. No. 19514/55. Class 46. The apparatus comprises inner and outer rotating cylinders having opposed filtering surfaces rotating in paths forming a nip of minimum clearance between the surfaces, and internal circumferentially-spaced passages in at least one of the cylinders communicating with the filtering surface of that cylinder and also with rotary valves at at least one end of the cylinder for applying pressure changes to the passages. An inner cylinder 32, Fig. 3, is rotated by bevel gear 42, 44 about an axis in the same horizontal plane as, but displaced from, the axis of an outer cylinder 16, driven by a worm gear 22 at the same peripheral speed. More than half the space between the cylinders at each end of the assembly is closed by a crescent-shaped plate 50, Figs. 2, 3and 6, held in place by bolts 52, 54, Fig. 6, 56 in brackets 58, the brackets being secured between slotted outer and inner rings 60, 70, respectively, Figs. 2 and 6. The inner surface of the outer cylinder 16 is lined with a series of concentric rings 102, Figs. 6 and 7, each ring having a series of transverse holes 103 which communicate with the free edge of the ring by a cutaway portion 104, Fig. 7, The rings are keyed to the cylinder 16 in such a manner that the holes 103 are aligned to form collectively helical passages pitched downwardly on either side of the middle of the cylinder, Fig. 8, whereby the middle of each passage reaches the nip in advance of its ends. Each passage communicates at each end with a port 108 in a bevelled valve ring 106, Figs. 6 and 9, which, at certain positions in its path, makes contact with the shoes 92 of valves 120, 121, 124 and 126, Figs. 2, 3 and 9, and with the elongated shoe 127 of valve 122. Each valve consists of the end of a pipe longitudinally slidable in a bearing at the end of a bracket 90 secured to the slotted ring 60, Fig. 9. The inner cylinder 32, Figs. 6, 7 and 9, is similarly provided with a lining of apertured rings and with a bevelled valve ring at each end. Valves radially aligned with those in contact with the ring 106 make contact with the inner cylinder valve ring 114 at each end of the apparatus, Figs. 2 and 9. In operation fibrous suspension is fed to a pipe 140, Fig. 2, which is cut away at the top between the plates 50, and vacuum is applied to the valve pairs at positions 120, 121. Compressed air is applied to the valve pair at position 122 to prevent retention of filtrate beyond the nip position, and also to the valves at position 124 to loosen the mats of fibres from the cylinders prior to deposition in a casing 136 whence the fibres are conveyed by a screw 134, Figs. 2 and 3. The cylinder linings are backwashed at valve positions 126 and thereafter cleaned by blades 149. An alternative cylinder lining, Fig. 11, consists of a cylinder 170 provided with helically-arranged axial grooves 171 and circumferential grooves 172, and covered with a perforated plate 173. Deepened ends 174 of grooves 171 communicate with ports 108a as before. Specification 775,286 is referred to.