Patent GB-1085313-A (GB)
Title: Shut-off device for a hydraulic turbine, pump or pump-turbine
IPC: F03B15/02
Filed: 1964-11-23
Abstract: 1,085,313. Hydraulic turbines; centrifugal pumps. ESCHER WYSS A. G. Nov. 23, 1964 [Dec. 18, 1963], No.47627/64. Headings F1C and F1T. A regulating and shut off device for a hydraulic turbine, pump or pump-turbine having an annular duct for the radial supply to or discharge from a runner, comprises a first axially movable annular closure member which is guided in an annular gap in one wall of the duct to vary the flow cross-sectional area in the duct, and a second axially movable annular closure member which is coaxial with and of the same diameter as the first closure member and is guided in an annular gap in the other wall of the duct, at least one of the two closure members, while remaining with one end in the annular gap guiding it, being adapted to move so that its other end extends into the annular gap guiding the other closure member. The duct, the two closure members and the runner are coaxial. The invention is described with reference to a Francis turbine and, in the position shown in Fig. 1, the first closure member 17 extends across and completely shuts off the duct 5, its lower face abutting the upper face of the second closure member 28 which is shown in its uppermost position in which it is held by three screws 31. The abutting faces are provided with seals 26 and 30. The member 17 may be moved by three servomotors 18 to any position between the one shown and its uppermost position in which its lower face is flush with the upper wall of duct 5. When it is desired to inspect the runner 1 or adjustable guide vanes 9, member 28 is lowered and the lower end of member 17 is lowered into the annular gap 16 guiding the member 28 until flange 22 abuts the outer surface of the upper wall of the duct 5. Closure screws 25 are then removed from assembly holes 24 in the turbine cover 2 and the flange 22 is screwed to this outer surface, bores 21 and threaded holes 23 being provided for this purpose. After admitting water under pressure or compressed air to annular sealing elements 27, 32 and disconnecting the servomotors 18 from the member 17, the turbine cover 2 or turbine lower part 3 may be removed for inspection purposes while volute casing 4 is under full water pressure. In the case of a turbine provided with fixed guide vanes, the two annular closure members are situated between the fixed guide vanes and the runner. In a modification, Fig. 2 (not shown), the upper annular closure member can be moved by servomotors to partially or completely blank off the water duct. For inspection purposes, however, it is the lower closure member which extends across the duct and into the annular gap associated with the upper closure member. In a further modification, Fig. 3 (not shown), the two annular closure members are connected together by an annular series of axially extending cross pieces, whose length corresponds with the axial width of the water duct. From the position in which the duct is wholly open, the closure members can be moved upwardly so that the lower one partially or completely blanks off the duct. On further upward movement, the lower closure member enters the upper annular gap, inspection of the runner &c. then being permitted.