GB872646A - Improvements in and relating to condensing steam turbines - Google Patents

Abstract

872,646. Elastic-fluid turbines; stuffing-box substitutes. ENGLISH ELECTRIC CO. Ltd. Jan. 15, 1958 [Jan. 18, 1957], No. 1882/57. Addition to 781,505. Classes 110 (3) and 122 (5). A shaft gland 3 of a condensing steam turbine 1 has a first pocket 6 connected at opposite points to a source of sealing steam and to a vent condenser 5 and a second pocket 11 nearer the turbine cylinder than the first pocket and connected to a sub-atmospheric pressure-point of the turbine plant. In the arrangement shown in Fig. 1, sealing steam is supplied through an isolating valve 10, strainer 16, needle valve 17 and regulating-valves 8, 8<SP>1</SP>, provided with locking means 18, 18<SP>1</SP>, to pockets 6 and 26 of labyrinth glands 3 and 3<SP>1</SP> at the high-pressure and low-pressure ends, respectively, of the turbine. The pocket 6 and a pocket 4 in the gland 31 are connected to vent condensers 5 and 5<SP>1</SP>, respectively, in which surplus steam is condensed by water-cooled coils and led to drain via tundishes 24. Pockets 11 and 14 in the gland 3 are connected by pipes 12 and 15 respectively to the turbine condenser 13 and an intermediate stage of the turbine. The regulating valves 8, 8<SP>1</SP> are initially set in conjunction with the needle valve 17, at light load and without water circulating in the vent condenser cooling coils, to give the correct flow of sealing steam to the glands and maintain a chosen pressure at the gauge 19 ; the regulating valves then being locked by means 18, 18<SP>1</SP>. During subsequent running, gland steam supply is controlled by adjusting the needle valve 17 to give the chosen pressure at the gauge 19. In the arrangement shown in Fig. 3 for a two-stage turbine comprising H.P. and L.P. cylinders 1, 101 having their shafts 2, 102 sealed by glands 3, 31 and 103, 1031, sealing steam is supplied through strainer 16, isolating valve 10, needle valve 17 and regulating valves 18, 18<SP>1</SP>, 108, 108<SP>1</SP> to pockets 6, 6<SP>1</SP>, 126, 1261 of glands 3, 3<SP>1</SP>, 103, and 1031, respectively. The pockets 6, 6<SP>1</SP> are also connected to vent condensers 5, 51 and pockets 104, 1041 in glands 103, 103<SP>1</SP> are connected to vent condensers 105, 105<SP>1</SP>. Pockets 11, 11<SP>1</SP> in glands 3, 3<SP>1</SP> are connected by pipe 12 to intermediate stages of the L.P. cylinder 101. Pockets 9 and 14 in the gland 3 are connected respectively to the end and to an intermediate stage of the H.P. cylinder 1. The regulating valves are set and locked as described above and the supply and pressure of the sealing steam is controlled by the needle valve 17. The pressure of the sealing steam may be maintained by a reducing valve 27 fitted in a line 29 by-passing valves 10 and 17.