GB761057A - Improvements relating to turbine-driven compressors - Google Patents

Abstract

761,057. Centrifugal and axial-flow compressors; gas turbine plant. FAIREY AVIATION CO., Ltd. July 14, 1954 [April 15, 1953], No. 10346/53. Classes 110 (1) and 110 (3). In a plant of the type comprising an output compressor for supplying compressed air to an external consumer and driven by a turbine, and a combustion-air compressor driven by the same or a separate turbine and supplying combustion air for the turbine or turbines, a pressure-release valve in the delivery passage of the output compressor is subjected to a closing force which is a function of the pressure at a point in a compressor driven by the turbine or turbines. In the embodiment shown, the output compressor 13 is driven by a turbine rotor 22, while the combustion-air compressor 15 is driven by a turbine rotor 23, the rotors 22, 23 forming successive stages of a single turbine driven by gas from combustion chambers 16. To prevent surging in the compressor 13 under low load conditions, a blow-off valve 17 in its delivery passage 14 is acted on by a bellows 18 to which compressed air is admitted through a pipe 21 from a point 19 of the compressor 15. Point 19 may be at an intermediate stage, as shown, or at the delivery of compressor 15 and part of the closing force on valve 17 may be provided by a spring. Valve flutter may be prevented by a damper. The speed of compressor 13 may be maintained constant by a speed governor (not shown). Compressed air is delivered through delivery passage 14 to a pipe grid (not shown) which may also be fed by a second plant. The pipe grid supplies different consumers, such as jet propulsion units and turbines. In a modification, compressors 13, 15 are mounted on a common driving-shaft together with a two-stage turbine which drives both compressors. The compressors may be of the centrifugal type instead of the axial-flow type shown.