Patent GB-895166-A (GB)
Title: Improvements in expansion turbines
IPC: F01D17/20
Filed: 1958-08-25
Abstract: 895,166. Elastic-fluid turbines. LAWS, P. Aug. 25, 1959 [Aug. 25, 1958], No. 27251/58. Class 110 (3). An outward radial flow turbine comprises an output shaft 1 and a hollow shaft 43 aligned with the output shaft and constituting an inlet duct for motive fluid such as steam, at least one hollow arm 50 extending radially of the shafts and connected to rotate therewith, the arm communicating with the interior of the hollow shaft and having at its outer end an expansion nozzle 52, a ring of fixed blades 58 being located so as to receive motive fluid discharged from the nozzle or nozzles and to re-direct it on to a set or sets of rotor blades 68 mounted on a rotor disc 64 radially outwardly of the nozzle or nozzles. The hollow shaft 43 is formed with a flange 47 which is received in a recess in a hub member 44, the latter abutting against the rotor disc 64. A flange 45 formed at the upper end of the output shaft 1 abuts against the other face of the rotor disc 64, and a flange member 85 abuts against the hub member 44 and against the flange 47 of the hollow shaft 43, the parts being secured together by means of through bolts 65. The hollow shaft 43 is provided with steam inlet ports 71, and the upper end of the shaft is closed by a cover plate 77. A hollow sleeve 72 is disposed around the shaft 43, the sleeve having steam inlet ports 76 which cooperate with the ports 71 in the shaft 43. The upper end of the sleeve is closed by a cover plate 80, and the sleeve is connected to the shaft 43 so as to rotate therewith but so that the sleeve may move axially with respect to the shaft, by means of dowels 78 secured to the cover plate 77 but slidable in bores in the cover plate 80. The position of the sleeve 72 with respect to the shaft 43 is controlled by means of a pair of semicircular governor weights 83 of L-section which pivot outwardly under the action of centrifugal force so as to bear against a flange 81 on the sleeve 72 so reducing the area of the steam inlet formed by the co-operating ports 71, 76. The sleeve is loaded axially in the downward direction by means of springs 85A and 95 which act against a spring plate 86 bearing against the cover plate 80. The loading of the spring 95 is adjustable. The radially extending tubes 50 are secured to the hub member 44 and communicate with the steam space within the shaft 43 through aligned bores 48 in the hub member 44 and 49 in the shaft 43. Tangentially directed nozzles 52 formed by members 53, 54 are secured at the outer ends of the tubes 50. Outwardly of the nozzles 52 is a ring of stator blades 58 extending parallel to the turbine axis, the blades being secured to a transversely extending annular plate member 35, the periphery of which is secured between flanges 31, 33 secured to the dished plate members 29, 34 which form the turbine stator casing. Sets of rotor blades 68 are disposed radially outwardly of the stator blades 58 being secured to the periphery of the rotor disc 64, one set of rotor blades being disposed radially outwardly of each nozzle 52. Exhaust steam is discharged from the casing 29, 34 through an outlet duct 30. The output shaft 1 is supported by bearings 7, 8 within a tubular member 20 secured to the stator casing end wall 23 as disclosed in Specification 887,106. An L-seetion ring member 37 is secured to the upper dished plate 34 of the stator casing, a tubular member 38 being secured to the ring member 37 so as to provide a steam chest to which steam is supplied through an inlet pipe 41 extending into the member 38. A ring member 39 is secured to the tubular member 38 and a cover plate 40 is secured thereto. An overspeed trip device is provided and comprises a plate valve 106 which may enter a slot formed in the inner end of the inlet pipe 41 so as to cut off the steam supply. The valve 106 is formed with an arm 108 and is pivotally mounted on a sleeve 109 in the tubular wall 38, a spring 120 tending to hold the valve in its closed position. The valve is moved to its open position by means of a hand-operated lever 114, the valve then being retained in the open position by means of a spring latch 125 which engages in a notch 126 in the arm 108. A spring-loaded bolt 129 is mounted diametrically in the rotatable cover plate 80 and at a certain speed, the bolt moves outwardly and engages a projection 133 on the spring latch 125, the end of which is thereby caused to disengage from the notch 126 and the valve 106 is moved to its closed position by the action of the spring 120. The valve is re-set manually by means of the lever 114.