Patent GB-1451261-A (GB)
Title: Centrifugal separators
IPC: B04B11/02
Filed: 1974-06-14
Abstract: 1451261 Centrifugal separator W H PECK and S A COLLIER 14 June 1974 26541/74 Heading B2P A centrifugal separator for separating the solid and liquid constituents of a slurry comprises a bowl 12, Fig. 4, having a dished bottom wall 84 which merges with an upper cylindrical rim section 86; a horizontal circular deck plate 16 disposed within the bowl and spaced from the bowl wall so as to define a first relatively wide annulus which communicates with the bottom region of the bowl; a horizontal, circular ceiling plate 22 spaced upwardly from the deck plate and inwardly from the bowl wall so as to define a second relatively narrow annulus which inhibits the free passage of solids upwardly therethrough; means for effecting rotation of the bowl and plates in unison about the vertical central axis of the bowl whereby the solid constituents of slurry fed on to the deck plate 16 will be flung in a radially outward direction between the deck and ceiling plates and establish an annular sludge seal 20 between the ceiling plate 22 and the bowl wall while the liquid constituent of the slurry will pass downwardly through the first annulus: a series of ploughs 42 disposed within the bowl and mounted for rotation about the bowl central axis in the vicinity of the sludge seal and effective when rotated to move circumferentially around the bowl wall and loosen the sludge for upward movement through the.second annulus; means 30 disposed immediately above the ceiling plate for withdrawing portions of the thus loosened sludge from the vicinity of the second annulus, conducting them inwardly of the bowl, raising them above the level of the bowl rim, and releasing them for outward radial flinging movement under the influence of centrifugal force over the bowl rim; and an outlet 14 in the bottom region of the bowl for discharge of the liquid constituent. The plates 16, 22 are secured to the bowl 12 by bolts and nuts 106, 110 and spacer assemblies. The bowl is bolted to a shaft 26 mounted in thrust bearings 272, 274, Fig. 1, and rotated through belt and pulley by a motor M 1  slidable by means of a crank 238 on a guide rod 228 to vary the drive ratio between the output shaft 222 of the motor and the shaft 26 for speed-change purposes. The slurry is fed on to the plate 16 via an axial bore 130 and radial passages 134 in the shaft 26. The ploughs 42 are secured to a carriage 32 which is driven from the shaft 26 through chain and sprocket assembly 282- 284, gear assemblies 292-300 and sleeve 304 at a speed slightly higher than that of the shaft and bowl. The portions of loosened sludge are removed from the vicinity of the second annulus by means of two series of buckets 30, Figs. 4 and 6 mounted on the carriage 32 at diametrically opposed locations relative to the shaft 26. The buckets of each series are pivotally mounted about pivot pins 184 extending across recesses 176 in a turntable 34 rotatably mounted about a shaft 162 on the carriage 32 and driven from the shaft 26 through aa associated planet gear 154 which engages a sungear 126 secured to the plate 22. Thus, in addition to being individually rotatable about the shaft 162 each turntable orbits about the shaft 26 due to rotation of the carriage 32 in the same direction as, but a slightly greater speed than the shaft 26 and bowl 12, since each turntable rotates about its own vertical axis; each bucket swings into and out of the loosened sludge stud scoops portions of it. Continued rotation of the turntable will effect a direction change so that -the bucket will reverse its direction with the result that its open leading side will ultimately face outwards of the bowl when the bucket arrives at its inside position. However as it approaches the latter position the bucket engages a cam surface 40, Fig. 15, on a member 200, Fig. 4, secured to the carriage 32 and is raised whereby at the inside position the bucket has reached its highest position shown in dotted lines, and the sludge portion under centrifugal force action is flung outwardly of the bucket over a cover plate 120 secured to the bowl rim. Upon returning to its outside position the bucket engages a cam surface 41, Fig. 17, on the carriage 32 and is thereby restored to its lowered position. The outwardly flung sludge impacts against the inside surface of a surrounding cylindrical apron 44 slowly rotated by belts 318 driven by a motor M 2 . The sludge is loosened by fixed scraper blades 46 and fall by gravity from the rotating apron. The liquid component discharges through the outlets 14 of the drum into a pan 10 having an outlet 18.