Patent GB-837975-A (GB)
Title: Nozzlebox structure for elastic fluid turbines
IPC: F01D9/06
Filed: 1956-09-24
Abstract: 837,975. Elastic-fluid turbine nozzle structures. GENERAL ELECTRIC CO. Sept. 24, 1956 [Sept. 30, 1955], No. 29133/56. Class 110 (3). [Also in Group XXVIII] A high-pressure, high-temperature steam turbine comprises an outer casing 1 and an inner casing 2, a number of nozzle-box assemblies being disposed within the inner casing, only one such assembly being shown in the sectional part view of Fig. 1. The nozzle-box assembly comprises a nozzle-box 6 with a projecting inlet conduit 5 secured thereto, the conduit 5 being of circular cross-section and having adjacent the nozzle-box an axially-extending cylindrical portion 5e spaced radially from the conduit so as to define an annular space therewith. A radially-extending locating flange portion 5f is formed integrally with the inlet conduit 5 being spaced axially from the cylindrical portion 5e at the side thereof remote from the nozzle-box. The turbine inner casing 2 has a cylindrical boss portion 3 surrounding the conduit 5 and means are provided for supporting the nozzle-box within the turbine inner casing. The supporting means comprises a pair of lugs 6b, 6c formed on the nozzle-box 6 which engage in an annular groove 2a in the casing and a third lug 6d which engages a recess 2b in the casing. The supporting means also comprises a locking-ring 15 formed of two or more segmental parts, the ring 15 having an axially-extending flange with an inwardly-extending flange 17. The central portion of the ring 15 is entered into the axial space between the cylindrical portion 5e and the locating flange 5f while the flange 17 engages a circumferential groove 18 in the cylindrical boss portion 3, the segmental construction of the ring 15 allowing the parts thereof to be assembled in a radial direction. The parts of the locking-ring 15 are clamped together after assembly by means of a clamping-ring 16 and bolts 20. Four axially-extending keyways such as 5h shown in Fig. 3 are formed in the periphery of the locating flange 5f and four corresponding lugs 16a are formed in the inner periphery of the clamping ring 16. Two blocks 16b of L-shape are disposed on either side of the lug between the sides of the lug and of the keyway 5h. The blocks are secured to the lug 16a after assembly by means of bolts. A multiple ring packing 14 is disposed between the outer surface of the cylindrical extension 5e and the inner surface of the cylindrical boss 3. The inlet conduit 5 is made in two parts 5a, 5b secured together by welding 5d, the part 5b being formed integral with the nozzle-box 6. The end of the conduit 5 engages in a socket 8, a multiple ring packing 7 being disposed therebetween, the socket 8 being formed integrally with a conduit portion 8a which is secured by welding to the inlet conduit 9, and with a thin-walled axial extension 10 which terminates in a thick flange 11. The flange 11 is secured to the turbine outer casing 1 by means of a thick ring member 13 and studs 12. A cylindrical heat-shield 21 is disposed in the annular space between the conduit 5b and the cylindrical extension 5e, the shield 21 having three annular ribs 21c on its inner surface, which define two insulating spaces, and having a helical rib 21d on its outer surface which defines a helical passage for flow of relatively cool steam which enters at 5m and discharges through port 15a in the locking-ring 15. A similar cooling arrangement is provided between the cylindrical extension 10 of the conduit 8a and the boss portion 1a of the outer casing 1. The clamping ring 16 may be formed of a number of segmental parts instead of as a single integral member. Specifications 718,534 and 825,849 are referred to.