Patent GB-1224243-A (GB)
Title: An apparatus for hydraulically transporting granular solid material
IPC: B65G53/30
Filed: 1968-04-04
Abstract: 1,224,243. Conveying solids in liquids. HITACHI Ltd. April 4, 1968 [April 7, 1967; April 12, 1967; April 24, 1967], No.16366/68. Heading F1R. Apparatus for hydraulically transporting granular solid material comprises a mixing tank 13, Fig. 8, for mixing the solid material and water, a lowpressure mixture pump BP for charging the solidwater mixture from the mixing tank into a plurality of parallel main feed pipes 1, 2, 3, and a highpressure clear water pump TP for discharging the mixture out of the main feed pipes towards a transport pipe 5. Valves B 1 , B 2 , B 3  and D 1 , D 2 , D 3  are opened to allow mixture to be pumped into the main feed pipes 1, 2, 3 via pipes 6, 7, 8 and to allow clean water already in the main feed pipes to be expelled via pipes 10, 11, 12 to the mixing tank. Then these valves as closed and valves A 1 , A 2 , A 3  and C 1 , C2, C 3  are opened to allow clean water to be pumped into the main feed pipes via a pipe 4 so as to discharge the mixture from the main feed pipes into the transport pipe 5. As shown, the opening and closing of the valves for three main feed pipes 1, 2, 3 can be staggered so that transport of the mixture occurs continuously and the pumps BP and TP are operated continuously. The Specification discusses the relationships between the volumes and velocities of flow of the mixture and clear water, the length of each main feed pipe and the times of opening and closing of the valves necessary to ensure that (a) clear water rather than mixture is passing through the valves, especially the valves C 1 , C 2 , C 3 , at the time they are closed, whereby damage to the valves by closing on solid material is avoided; (b) the return of solid material to the mixing tank, which would reduce the transport efficiency, is avoided and (c) no unduly long dead space is left between the leading end of the charged mixture and the valves C 1 , C 2 , C 3 . Fig.9 shows a preferred form of valve, which is closed by lifting a valve plate 40. Lumps of solid material lying on or near the border of the opening 41 and the bottom edges of the valve seats 37 are lifted and are shed out between the valve seats and the opening before the valve finally closes, whereby damage to the valve is avoided. Because the effective area of the lower-end of the valve plate 40 is greater than that of the upper-end by the cross-sectional area of the operating spindle 30, water at high pressure leaking into the spaces above and below the valve exerts a net upward force which, in the event of failure of the oilpressure operating the actuating piston 31, causes the valve to close and therefore fail safe. As shown for valve A 1  in Fig. 8, a pressure relief valve f can be opened after the valve is closed to relieve the high-pressure exerted on one side of the valve plate to cause the latter to be urged into firm closing contact with one of the valve seats 37. When the valve is to be opened again, a pressure equalizing valve e is first opened. The exit opening 16, Fig.5, from the mixing tank 13 is adjustable by means of a slide valve 18 actuated by a hydraulic piston 20. Additional clear water is supplied to the mixture from a tank 22 in which an overflow port keeps the water level below that in the mixing tank 13.