GB684401A - Improvements in or relating to a power plant - Google Patents

Abstract

684,401. Gas turbine plant; stuffing-box substitutes. GARRETT CORPORATION. May 31. 1949 [Aug. 6, 1948], No. 14577/49. Classes 110(iii) and 122(v) In a gas turbine plant comprising a turbine driving an air compressor which supplies air to combustion means feeding the turbine, the turbine and compressor are positioned with their discharge openings at the outer ends of the plant, a compressor air intake with a side duct connection opening is disposed between the compressor and turbine and a branch connection for bleeding off compressed air is disposed upstream of the combustion means. In the arrangement shown, Fig. 4, a two stage compressor unit 11 is driven by a radial inward flow gas turbine 10 through a quill shaft 70 the ends of which engage splined portions 68 and 52 of the turbine and compressor shafts. The shaft 70 is able to flex and twist and thus forms a resilient readily detachable connection between the turbine and compressor. The turbine may be removed by releasing bolts 58. The turbine bearings 34 are mounted in a housing 32 which is bolted to the turbine nozzle annulus 15. Attached to the housing 32 by screws 37, Fig. 5, is a sealing ring carrier member 38. This member allows cool air to contact the back of the turbine wheel 30 and also hot gas to act on the outer periphery of the rear face of the wheel to balance the axial thrust. A pair of concentric annular grooves 42 in the member 38 receive annular sealing rings 43 held in place by snap rings 45. The sealing rings, which are preferably made from stainless steel, engage against the outer inclined surfaces of V-shaped bands 47 formed on the wheel 30. Bolts 53 hold the housing 32 and member 38 together so that by removing the bolts 30<SP>1</SP>, the sealing system and bearing assembly may be removed. The compressor impellers 81, 84 are mounted on a shaft 63 supported by bearings 59 and 96. The impellers, which have backward curved blades, discharge into a pair of volute chambers 89, 90. The first stage impeller 81 has a short diffuser around its periphery and only a portion of the velocity reduction occurs at that point, the air passage which conveys the air to the second stage also acts as a diffuser. Connected to the ends of the volute discharge ducts by means of flexible couplings are shells 105, 106 which form the casing of the combustion chambers 12, 13. The elbow ducts 101, 102 are provided with outlets 107, 108 through which air is bled off for aircraft controls or other uses. Vanes 110 are provided to direct the proper amount of air into the shells 105, 106. The flame tubes 112 are formed as extensions of the inlet pipes 22, 23 of the turbines. The rearward end of each flame tube is tapered and connected to a sleeve 113 in which the fuel nozzle 115 is disposed. The forward end of each shell 105, 106 is connected to an enlarged portion 117 of the tube 112 by means of a clamp ring 118. By disconnecting this ring and the flexible coupling 100 the shell 105 or 106 and the elbow 101 or 102 together with the fuel nozzle 115 may be removed. An accessory unit 122 comprising an electric starter motor 125, a fuel control 130 and oil and fuel pumps 140, 133 is mounted by means of a frame 121 on the rear end of the compressor. This unit is driven from the compressor shaft by a splined shaft 128. The starter motor 125 is connected to the compressor shaft through an over-running clutch and is de-energised when the turbine speed exceeds that of the motor. The fuel control 130 maintains the speed of the unit constant irrespective of the load. Specification 684,428 is referred to.