Improvements relating to steam turbines

1,108,265. Gaseous seals. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. 26 Nov., 1964 [13 Dec., 1963], No. 49346/63. Heading F2B. [Also in Division F1] In a steam turbine the steam supplied to the high pressure and intermediate pressure sealing glands 4, 41 and 5, 51, is desuperheated before entering the glands by indirect heat exchange with steam which has been cooled to below a desired gland inlet temperature by indirect heat exchange with a cooling fluid of substantially constant temperature. Superheated steam from the turbine boiler or other source is supplied via pipe 9, control valve 10 and throttle valve 11 to a coil 12, where it is desuperheated by cooled steam in the space 18 of the heat exchanger 13, part of the steam then being supplied through an orifice 14 to the glands 4, 41 and 5, 51 and the remaining passing via pipe 15, coil 16 and pipe 17 to the space 18 of the heat exchanger 13. The steam is cooled in the coil 16 by heat exchange with condensate of steam which is discharged from the low pressure glands 6, 61 to a chamber 22 and condensed by coolant flowing through a coil 25. Steam from the space 18 together with steam discharged from the glands 4, 41 and 5, 51 is desuperheated in coil 21 by heat exchange with the condensate in chamber 22 and then passed to the low pressure glands 6, 61. The chamber 22 is at atmospheric pressure and the level of the condensate therein is limited to 26 by overflow means (not shown). In a modification, Fig. 2 (not shown), superheated steam is supplied directly from the pipe 9 to both the coil 12 and the coil 16 through adjustable orifices. In a further modification, condensate in the chamber 22 is obtained from steam from the turbine valve spindle mechanism which is led into the vapour space 24, the exhaust from the low pressure glands 6, 61 being separately condensed. Reference has been directed by the Comptroller to Specification 1,059,917.