GB893086A - Surge control device for centrifugal compressors - Google Patents

Abstract

893,086. Centrifugal compressors. GARRETT CORPORATION. June 11, 1958 [June 11, 1957], No. 18702/58. Class 110 (1). [Also in Groups XIII and XXIX] In a centrifugal compressor which, as shown, may be used in a vapour cycle refrigerator circuit, the rate of flow through the discharge passage 21 is sensed by a probe comprising orifices 80 and 81 facing upstream and downstream, respectively, the pressures developed at the orifices being applied through pipes 82, 83 to opposite sides of a diaphragm 60 to urge the diaphragm towards the left so as to close the end of a tube 64. When the rate of flow is reduced to a value at which surging in the compressor is imminent, the resultant reduction of the difference between the pressures developed at the orifices 80, 81 allows a spring 70 to move the diaphragm 60 away from the tube 64. Vapour from the discharge passage 21 then flows through the tube 64 to a chamber 90 and thence through the hollow stem 36 of a valve 35 to the compressor inlet 14. When this flow occurs, a constriction 53 in this flow path raises the pressure in chamber 90 above the pressure at the inlet 14, the resultant force on a diaphragm 45 opening the valve 35 against the action of a spring 51. Vapour is then returned from the refrigerator condenser 12 to the inlet 14 by way of the valve 35 to increase the flow through the compressor sufficiently to prevent surging.