Patent GB-1295526-A (GB)
IPC: B04B1/14
Filed: 1970-06-18
Abstract: 1295526 Operating sludge discharge valve in centrifuge MITSUBISHI KAKOKI KAISHA Ltd 18 June 1970 [18 June 1969] 29721/70 Heading B2P A centrifugal disc-bowl separator comprises a rotary bowl 14, an operating water chamber 16 between the bowl and a sleeve valve 15 which is in sliding contact with the bowl for controlling the opening or closing of a sludge discharge aperture 23, and a flange member, on the outer periphery of the bowl or, as shown at 17, on the inner periphery of the sleeve valve, protruding into the chamber 16 and dividing it into first and second chambers 16', 16", one side of the member 16 having in the first chamber 16' an area which is to be subjected to hydraulic pressure and is larger than that area of the other side of the member which is to be subjected to opposing hydraulic pressure in the second chamber 16", the first and second chambers being in communication separately through passages 18, 19 with a smaller diameter part 22 and a larger diameter part 21 of a feed water chamber 20 which is provided around a rotary shaft 13 coaxial with and fixed to the bowl. The arrangement is such that the first chamber 16' when supplied with hydraulic pressure expands so as to drive water in the second chamber 16" back to the feed water chamber 20 through the respective passage 18 and thereby cause the sleeve valve 15 to open the sludge discharge aperture 23 of the bowl, and that the second chamber 16" when supplied with hydraulic pressure expands so as to cause water in the first chamber 16' to be discharged through holes 24 through the sleeve valve and to cause the valve to close the sludge discharge aperture. Hydraulic pressure in the chambers 16', 16" is regulated by a feed water guide chamber 25 provided in the feed water chamber 20 and by a pressure regulating valve 28 across which is connected a by-pass 27 equipped with a valve 27'. The valve, 28 and by-pass 27 are connected by a duct 26 to a feeding manifold 32 equipped with nozzles 31 opening radially in the chamber 25. Holes 29, 30 through the wall of the chamber 25 communicate respectively with the parts 22, 21 of the feed water chamber 20.  In operation, when the feeding of operating water is commenced after the by-pass valve 27' is closed and the pressure regulating valve 28 is set to low, the water entering the chamber 25 through the nozzles 31 accumulates at the outer periphery of the chamber interior and flows through the hole 30 into the part 21 of the feed waterchamber 20 and then flows through the passage 19 into the lower chamber 16". Because of the low setting of valve 28 the water does not reach the hole 29 and hence no water is supplied to chamber 16'. Consequently hydraulic pressure in chamber 16" pushes sleeve valve 15 upwards to close the sludge discharge aperture 23. When the chamber 16", passage 19 and part 21 of chamber 20 become completely filled with water so that the water in guide chamber 25 extends further inwardly over the line X-X and produces a hydraulic pressure in the nozzles 31, the valve 28 operates to stop supply of the operating water. Any operating water flowing into the chamber 16' is discharged through holes 24 provided in the sleeve valve 15. After the bowl has been operating for a given time, the valve 27' is opened so that a large amount of operating water is supplied to move the feed water up to a line y-y in chamber 25 so that water flows through the hole 29, part 22 and passage 18 into chamber 16'. Since the upper side of flange 17 has a larger area than the bottom side thereof, the excess hydraulic force acting downwards on the flange causes the latter to push the water in chamber 16" back to chamber 20 thereby opening sludge aperture 23 for sludge discharge. After disludging, valve 27' is closed and water in chamber l6' is discharged through the holes 24 whereby pressure in chamber 16' is reduced and valve 15 is pushed upwards to close aperture 23.