GB427152A - Improvements in and relating to governing mechanism for elastic fluid turbines - Google Patents

Abstract

427,152. Steam turbines. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London. June 23, 1934, No. 18609. Convention date, June 23, 1933. [Class 110 (iii)] The admission valve 3 of a turbine 1, particularly of the back-pressure type, is regulated by apparatus 76 which is responsive to an operating condition of the turbine other than its speed, e.g. the pressure or temperature in the back-pressure conduit. The mechanism comprises a duplex servo-motor system. In the form shown in the Figure, the casing 76 is connected by a pipe 78 to the exhaust conduit 2<a>, a liquid seal 79 and an adjustable orifice 80 being interposed. A bellows 77 in the casing is connected to a stem 75, movement of which is governed by an adjustable spring 83 which has a strength such that appreciable successive increases in pressure are required to compress the bellows successive steps. The stem 75 is connected to a pivoted lever 72 having an adjustable weight 74, which lever actuates, through a floating lever 70, the pilot valve 42 of a servo-motor 32. This servo-motor, acting through levers 27, 24, 21, controls the pilot valve 19 of the servo-motor 14 which regulates the admission valve 3 of the turbine. The follow-up or restoring mechanism for the pilot valve 42 comprises two casings 49, 56, hydraulically connected, and a pivoted lever 59 arranged to be rocked between adjustable springs 91, 92. The casings contain bellows 48, 57, and the spaces above and below the bellows 48 are connected by a passage 53, the restricted area of which may be varied by a screw 54. A pre-emergency speed governor 38 is connected to a pilot valve 35 of the servo-motor 32, and takes control of the governing of the turbine if the back pressure governor ceases to function.