Patent GB-722092-A (GB)
Title: Presses for separating liquids from solids
IPC: B01D25/164
Filed: 1950-09-28
Abstract: 722,092. Presses for separating liquids from solids. CARVER, Inc., F. S. Sept. 28. 1950 [Oct. 8, 1949], No. 23760/50. Class 46. In a multi-chamber press operated by pressure of the type in which each chamber is formed by two carrier members each presenting a filter element towards the inside of the chamber and by a peripheral ring normally urged into a position where it closes the chamber by spring means which also maintain the carrier members apart when the press is inoperative, lost motion connections are provided which limit the separation of the carrier members on release of the pressure. Each member comprises a rectangular platen 29, Fig. 10, having secured to it on its left a cylindrical piston 33, Figs. 2 and 7, the faces of the member each having a filter element 38 and the chamber formed by two adjacent members being closed by a ring 45, Figs. 7 and 9e. The rings 45 and platens 29 slide on horizontal fixed guides 50, Fig. 2, of the press framework by bearing surfaces 48 and 47 respectively, each ring normally being maintained in contact with the platen to its left, whether pressure is being applied to the chambers or not, by four springs 66, Figs. 7 and 10, each operating between an annular recess 53 in the platen to its right, Fig. 7, and a flange formed at the bottom of a counterbored hole 55 in a lug 54 of the ring 45. The distance apart of adjacent platens and hence the axial length of the chamber between filter elements 38 is limited by lost motion connections, each surrounded bv one of the springs 66 and comprising a hollow sleeve 59, Fig 7, secured to the left of a platen and co-operating with the head 65 of a bolt 64 protruding from the right of the platen on the left. Although there is a clearance between the lugs 54 and the platen on the left the body of the ring 45 is in contact with the platen as shown in Fig. 7. The springs 66 thus serve also to maintain the carrier members their maximum distance apart when the press is not being operated. Fig. 2 shows the press when pressure fluid has been introduced to the right of a ram 26 secured to cross head 28, Fig. 9g, which is in turn secured to the platen 29a, at the ex treme right of the press, bearing its piston 33a Fig. 7 shows a single chamber under compression containing cake C. When pressure on the ram 26 is relieved the members are restored to their normal positions by the springs 66, each bolt head 65, Fig. 7, then bearing against a shoulder 61 in its sleeve 59. In this position the righthand filter element 38 has become detached from the cake C. The cake is detached from the filter element on the left and finally from the ring 45 by movement of the ring 45 from the platen on its left to the platen on its right, where it surrounds the piston 33, against the pressure of the springs 66. This movement (see below) is effected by a shaft 75, Fig. 8, (one at each side of the press, Fig. 2,) each bearing a number of collars 88a, one to engage with a lug 67, Fig. 9e, on each ring 45. Each shaft 75 is secured to a piston 70, Fig. 2, in a cylinder 68 through a piston rod 71, Fig. 8, slidable for a short distance in a hole 73, Fig. 9g, in the crosshead 28. Each shaft, piston rod and piston is moved to the left on pressure-operation of the ram 26 by engagement of lug 67a with collar 88a which together with collars 88b, 88c, forms part of a sleeve 77 secured to a ring 81 providing a fourth collar 88d and engaged in a reduced portion 82 of the shaft, Fig. 8. The next four collars form part of a sleeve 78 having sliding connection with a reduced portion 85 of the shaft, Fig. 8, this sleeve being moved by lug 67e, Fig. 2. Since the integrated movement of the members and rings decreases from right to left the sleeve 78 moves a smaller distance than the shaft (which moves with the sleeve 77) as shown by the exposed part of the reduced portion 85, Fig. 2. The next three collars form part of a sleeve 79, Fig. 8, and the last collar is constituted by a short sleeve 86, these being retained on the shaft by a nut 87 but permitting the shaft to slide freely through them from right to left as shown in Fig. 2. The sleeve 86 slides in the resistance head 20 of the press. On release of ram pressure the springs 66 restore the chamber-forming members to their former positions, each shaft 75 and associated sleeves being restored almost to the position of Fig. 8 by engagement of the lug 67a with a collar 76. The ram and cross-head 28 are also returned to their starting positions bv movement of the chambers. For release of the cakes C all the rings 45 are moved to the right through the same distance by introducing pressure fluid on the left of the piston 70 in the cylinder 68. The first small movement of each shaft 75 results in the configuration of Fig. 8 where each collar 88 is in contact with its lug 67 and all lost motion between sleeves and shaft has been taken up. Further movement results in each ring 45 moving out of contact with the platen on its left, the cake C at the same time leaving the filter element 38, Fig. 7, on its left. As each ring 45 slides over its respective piston 33 the cake C is sheared from inside its ring, and in the limiting position of the rings the cakes C are free to drop from the apparatus. The collar 76, Fig. 8, then abuts the cross-head 28. The rings 45 are restored to normal positions on completion of this step by the springs 66, and each shaft 75 and sleeves are restored by the ring lugs 67 acting against the collars 88 or by compressed air admitted to the cylinder 68 at venthole 68b, Fig. 2. Each filter element 38, Fig. 10, comprises a circular plate 41 with a central hole and having annular and radial drain grooves 99, 100 on its rear face which communicate by drillings 101 with annular grooves 102 on its front face. The inner and outer edges of the plate 41 are bevelled and on the annular portion remaining are disposed in order a coarse mesh screen 109, a perforated plate 112 and a fine mesh screen 111. The last two extend over the bevelled edges and are held in place by an outer ring 115, and by an inner feed tube having a steeply-tapered inner surface 117 when the element is mounted on a platen 29 as in Fig. 10, or by a plug (not shown) when it is mounted on a piston 33. The feed tube 117 communicates by a passage 90 in the platen with a feed pipe 138 for liquid to be filtered. Liquid is withdrawn through a passage 121 in the platen 29, Fig. 10, leading from a drilling 103 in the platen communicating with the outermost groove 99 in the plate 41. The drilling 103 is in line with a similar drilling 104 (not shown) in the piston behind the platen and communicating with the back of the piston filter element. A tortuous steam-passage (not shown) is provided in each platen 29 for heating it. In a modification, not shown, each piston is secured on the right of a platen and each ring in chamber-closing position is in contact with the right hand platen. The pistons have a central opening to convey liquid to be filtered from the platens to the left-hand filtering-members. The cylinders 68 for the ring-retracting mechanism are in this case secured to the cross-head 28 and each collar 88 is to the right of its corresponding lug. Pressure fluid is admitted to the right of each piston 70 to retract the rings. In a further modification the complete press is arranged vertically with the ram head at the bottom supported on legs and the platens, rings and cross head are guided by corner tie members. Suitable mechanism is provided to remove the cakes laterally. In all cases the pumping pressure under which the liquid to be filtered is supplied may be continued for some time after the press has been filled to cause initial filtering before shortening of the chambers. Specification 722,170 is referred to.