GB744317A - Apparatus for preventing surging in a turbo-compressor - Google Patents

Abstract

744,317. Centrifugal compressors. MASCHINENFABRIK OERLIKON. April 7, 1953 [April 9, 1952], No. 9456/53. Class 110(1) [Also in Group XXIX] Apparatus for preventing surging in a centrifugal compressor comprises a venturi or like measuring nozzle 6 which creates a pressure difference corresponding to the amount of medium from the compressor passing through it, a control member such as the liquid sealed bell 8 responsive to the pressure difference created by the nozzle 6 and to the pressure difference between the pressure at the throat of the nozzle and the atmosphere, an actuating device such as the differential piston 22 controlled by the control member, and a hollow cylindrical sliding valve 1 operated by the actuating device to throttle the inlet of the compressor. The valve is guided by rollers 3 engaging fixed tracks (not shown) in the compressor casing and is operated through a bell crank lever 24 by the differential piston 22, the smaller area Fb of which is exposed to the pressure in the compressor delivery pipe 5 and the larger area Fa of which is connected to the pipe 5 through a throttle screw 23. The pressure on the area Fa is controlled by needle valve 19 supported by resilient steel plates 21 and operated through a floating lever 15 and a flexible link 16 by the spring loaded liquid sealed bell 8. The link 16 is maintained in tension by a weight 17. The delivery pipe 5 contains a throttle valve 7. The bell 8 operates in a mercury seal 13. A bellows 9 connects the bell 8 to a housing 10. The floating lever 15 is re-set by a cam 25 acting through a lever 27 having a fixed pivot 28. In the case of a multi-stage compressor, the lever 24 operates, through a shaft 26 bearing suitably profiled cams 30, bell crank levers 32 connected to operate further valves such as the hollow cylindrical valve 1. Reference has been directed by the Comptroller to Specification 700,152.