Patent GB-760781-A (GB)
Title: Improvements in or relating to gland seals for gas-filled electric machines
IPC: F16J15/44
Filed: 1954-08-03
Abstract: 760,781. Stuffing-box substitutes. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Aug. 3, 1954 [Aug. 11, 1953], No. 22449/54. Class 122 (5). In a shaft seal for a hydrogen or other gascooled turbo-generator comprising an annular sealing ring 15a (Fig. 2) surrounding the shaft 8a with a small clearance 19, housed in a groove in a seal housing 14a and forming therewith an annular chamber 18 supplied with pressure sealing liquid which flows through a passage 21<SP>1</SP>, 21 in the ring to the clearance 19, the axial load on the ring due to the hydrogen or other gas pressure, which forces the ring against the outer wall of the groove and may cause binding, is counteracted by supplying some of the sealing liquid through means such as passages 26, 27 to the overlapped portion of the outer side wall of the ring. Sealing liquid supplied to the clearance 19 from the chamber 18 flows to the air-side of the seal and further sealing liquid supplied through passages 24, 25 and 22<SP>1</SP>, 22 in the housing 14a and ring respectively, also to the clearance 19, circulates to the hydrogen side of the seal. The sealing liquid is preferably the same oil as used for the shaft bearings and a suitable oil-circulation system is shown in Fig. 1. Leakage oil from the shaft bearings 9a, 9b and the air-side of the seals drains through pipes 31a, 31b and 33 to a reservoir RES from where it is drawn by a pump P1 and delivered, at a pressure above the hydrogen pressure and controlled by a valve V operated by a differential mechanism connected to both the oil delivery pipe 38 and the interior of the generator housing 6, through a cooler C1 and pipes 39, 23 and 23b to the chambers 18. Leakage oil from the hydrogen-side of the seals is drained via defoaming tanks 64a, 64b and pipes 65a, 65b and 68 to a float chamber 44 supplied with additional oil from pipe 39 when necessary. Oil is pumped from the chamber 44 by a pump P2 and delivered through a cooler C2, pipes 47, 48, 24 and 24b to the inner walls of the seal housings 14a, 14b. The pressures in pipes 23 and 24 and 23b and 24b are equalized by valves 50 and 51 respectively. A pump P3 connected on its suction side to the pipe 39 pumps oil at a predetermined pressure through pipes 54, 55, 26, 26b to the outer walls of the seal housings. Pipes 39 and 55 are connected by a non-return valve V7 which operates in the event of failure of the pump P3. In a modification (Fig. 3) two seal rings 90, 91 are housed side-by-side in the groove in the seal housing 94 and the abutting surfaces of the rings are recessed to form a passage 95 opening into the clearance 19 and communicating through passages 96 in the rings with the chamber 18 provided with sealing oil through a passage 83; sealing liquid is supplied to the outer and inner walls of the housing through passages 97, 98 and 97<SP>1</SP>, 98<SP>1</SP>. In a further modification, the passages 97, 98, 97<SP>1</SP> and 98<SP>1</SP> are omitted and the outer side face of the ring 90 is relieved to form a space-extending over the major part of the overlapping portion of the face and communicating with the chamber 18.