GB938820A - Rotary sealing mechanism - Google Patents

Abstract

938,820. Stuffing-box substitutes. SOC. ALSACIENNE DE CONSTRUCTIONS MECANIQUES. April 6, 1961 [April 7, 1960], No. 12449/61. Class 122 (5). A sealing arrangement for the rotary shaft 34 of a compressor or other machine comprises means to supply sealing gas at subatmospheric pressure to a space 49 intermediate inner and outer spaces 42 and 48 respectively and suction means, for example vacuum pumps 58 and 56, connected to the spaces 42 and 48 to maintain pressures in each of those spaces less than that in the space 49. A compressor wheel 31 secured to the shaft 34 has a sleeve 35 coaxial with the shaft and mounted on bearings 36 in the machine casing 33. Helical grooves 38 and 38a of opposite hand in the sleeve 35 extending from a land 39 oppose leakage along the sleeve of compressor gas, which may be uranium hexafluoride, from space 62 and of sealing gas from space 42. The sealing gas, which may be nitrogen, is supplied to the space 49 through duct 52. Compressed air is supplied through a duct 50 to a space 47 and bearings 36 are lubricated by a mixture of oil and air fed from a mixer 57 through a duct 54. The spaces 47, 48, 49 and 42 are separated by serrated sections L1, L2 and L3. In operation, nitrogen supplied to the space 49 flows partly to space 42 where it is drawn off by pump 58 and partly to space 48 where it is drawn off by pump 56 together with compressed air flowing from space 47 through section L1. The remainder of the compressed air in space 47 escapes outwardly past the bearings 36. When the compressor is at rest or rotating at a speed below a certain value a sealing member 41 operated through rods 44 is automatically moved to sealingly engage seats on the sleeve 35 and the casing 33. Specification 820,348 is referred to.