Patent GB-847595-A (GB)
Title: Improvements relating to gas turbine engines
IPC: F02C6/10
Filed: 1957-06-14
Abstract: 847,595. Gas-turbine plant. GARRETT CORPORATION. June 14, 1957 [June 15, 1956], No. 1615/60. Divided out of 847,594. Class 110 (3). [Also in Group XXIX] A gas-turbine plant comprising a compressor supplying combustion air to a combustion chamber feeding a gas-turbine driving the compressor has a bleed duct for withdrawing compressed air from the compressor delivery for external use, an augmentation air duct for supplying compressed-air to the turbine from a source other than the compressor and a non- return valve situated in the passage leading from the compressor delivery to the turbine inlet at a point between the bleed duct and the augmentation air duct so that the turbine can be operated entirely on augmentation air from an external source which the compressor delivery is employed for external use without contamination. The invention is described with reference to a gas-turbine plant comprising a mixed axial-radial flow compressor which supplies air to an external user and to a combustion chamber feeding a radial flow turbine driving the compressor. A non-return valve 32, Fig. 2, is provided between the compressor discharge and the inlet to the combustion chamber. The valve 32 has arms 41 pivoted to an intermediate point of links 42 which are carried on brackets 48, fixed to the compressor frame structure, by levers 44, 45. Tension springs 51 connect the pivot pin 43 with a pin 52 on one of the levers 45 so that the check valve 32 is maintained on its annular seats 39, 40 until the compressor discharge pressure reaches a predetermined value. Additional air from another engine may be supplied to the turbine inlet 19, Fig. 5, by a duct 29, the flow through which is controlled by mechanism 30. The mechanism 30 is put into operation by energization of the solenoid valve 195 which causes the ball elements 196 to be moved away from the seats 205, 206 and to engage the seats 208, 209. The solenoid may be energized by a manual control switch 233 and de-energized by an overspeed switch 232. The thermostat 31 in the turbine inlet controls the flow through a vent 182 and thus the pressure in the tube 181. This pressure acts on a spring-loaded diaphragm 189 to position a pilot valve 188. The valve 188 controls the flow through the tube 193 and thus the pressure in the tube 194. The pressure in the tube 194 acts on a spring-loaded diaphragm 200 connected by linkwork 202, 203 to the valve 179. Movement of the valve 179 rotates the cam 185 which positions the follower 186 so that the leak-off through the pilot valve 188 is returned to its original value. Fluid for the tubes 193, 194 is supplied from the duct 29 upstream of the valve 179 through a tube 210, pressure regulator 211, chamber 213 and orifice 220. The chamber 213 forms part of a check valve 214 provided with a diaphragm 215 which carries a check valve member 216 adapted to engage a seat 217 communicating with a tube 218. The tube 218 is connected to a chamber 230 on the other side of the diaphragm 200 to the chamber 198. The check valve 214 is also provided with a second check valve member 221 having in it an orifice 222. The valve member 221 is carried by a diaphragm 223 which separates two chambers 224, 225, and is held on its seat by a spring 226. The chamber 225 is connected to the duct 29 downstream of the valve 179. A tube 229 connects the chamber 224 to the solenoid valve 195. If the valve 195 is de-energized by operation of the switch 232, pressure fluid is admitted from the tube 194 into the chamber 224 through the seat 208 and tube 229. From the chamber 224 the fluid passes through orifice 222 and conduit 218 to the chamber 230 under the diaphragm 200. The chamber 198 above the diaphragm 200 is connected to atmosphere through conduit 197, seat 208 and vent 231. The pressure drop across the diaphragm 200 and the loading of the spring 204 will cause rapid closing of the valve 179. The valve 179 also prevents undesirable high pressure at the inlet of the turbine. The pressure at the outlet of the pressure regulator 211 and thus the pressure in the chamber 213 is set to correspond substantially with the desired maximum pressure in the duct 29. When the pressure downstream of the valve increases beyond this maximum, this pressure in the chamber 225 is greater than that in the chamber 213 and the check valve 216 is opened. Pressure air from the chamber 225 then flows into the tube 218 and chamber 230 and so closes the valve 179. The check valve 216 also senses the pressure difference between the chambers 213, 225 when the pressure of the air delivered by the duct 29 is less than that at the turbine inlet and will operate to close the valve 179. The gas-turbine plant is also controlled by the means described in Specification 847,594. Specifications 775,454 and 770,563 also are referred to.