GB875319A - Turbine driven compressors - Google Patents

Abstract

875,319. Centrifugal compressors; stuffing- box substitutes. GARRETT CORPORATION. Dec. 20, 1957 [Dec. 21, 1956], No. 8321/61. Divided out of 875,318. Classes 110 (1) and 122 (5). A refrigerant compressor having an impeller 10 and a driving turbine 11 on a common shaft 12 comprises a shaft seal comprising an axially movable non-rotatable valve ring 41 which, when the compressor is at rest, is urged by a spring 45 into sealing contact with a seat 40 on a ring 35 secured to the shaft 12 and is moved out of engagement with the seat 40 by means actuated by turbine motive fluid when motive fluid is admitted to the turbine. The valve ring 41, which may be of moulded plastic, is mounted on one end of a piston 42 slidable in a cylinder 47 and sealed to the impeller housing 15 by a flexible diaphragm 43. When the compressor is started turbine motive fluid passes from the turbine inlet 57 through gap 59, space 52 and passages 51 and 50 into space 46 to move the piston 42 to the left and retract the valve ring 41 from its seat 40. A spring-loaded ball valve 54 in the passage 51 delays the drop in pressure in space 46 when the turbine is shut off to prevent seating of the valve ring 41 whilst the compressor is coasting to a stop. The shaft is sealed when the compressor is running by a carbon ring 36 in fluid rubbing sealing contact with the ring 35; this seal also assists to prevent leakage when the compressor is at rest. The impeller 10 is sealed to the housing 15 by labyrinth seals 25 and 30.