Abstract: A welding method for an impeller having a plurality of blades, a disc and an exterior body including a shroud welded to the plurality of blades, comprising the steps of: a first step for forming a groove having a prescribed depth and a prescribed width toward one of the blades on a surface of the disc or the exterior body, which is opposite to a surface against the blade abuts, emitting laser light toward the bottom of the groove, and performing melt-through bead welding to bond the bottom of the groove to an end of the blade in such a way that a bead formed on the back of the disc or the shroud is curved with an inward depression; and a second step for performing overlaying welding after completion of the first step by supplying a filler metal to a molten zone while the bottom of the groove is scanned with the laser light.

Abstract: Blades are connected to the surface of a disk and slots are formed in the surface of a shroud, which is opposite from the other surface of the shroud where the blades are to be welded. The blades are arranged on the opposite surface from the slots and a laser beam is applied from the surface in which the slots are formed, to weld the shroud and the blades. Components are installed on the surfaces of the slots on the opposite side from the blades after the blades and the shroud in which the slots are formed are welded. Alternatively, the slots are filled with a material different from that of the shroud, such as a resin. With this configuration, distortion caused by welding heat can be reduced without degrading the fluid performance.

Abstract: A welding method for an impeller having a plurality of blades, a disc and an exterior body including a shroud welded to the plurality of blades, comprising the steps of: a first step for forming a groove having a prescribed depth and a prescribed width toward one of the blades on a surface of the disc or the exterior body, which is opposite to a surface against the blade abuts, emitting laser light toward the bottom of the groove, and performing melt-through bead welding to bond the bottom of the groove to an end of the blade in such a way that a bead formed on the back of the disc or the shroud is curved with an inward depression; and a second step for performing overlaying welding after completion of the first step by supplying a filler metal to a molten zone while the bottom of the groove is scanned with the laser light.

Abstract: Blades are connected to the surface of a disk and slots are formed in the surface of a shroud, which is opposite from the other surface of the shroud where the blades are to be welded. The blades are arranged on the opposite surface from the slots and a laser beam is applied from the surface in which the slots are formed, to weld the shroud and the blades. If powder is melted and put in the slots formed for welding in the shroud to fill the slots, thermal distortion occurs. On the other hand, if the slots are left empty, a problem of degrading the fluid performance arises. To solve these problems, components are installed on the surfaces of the slots on the opposite side from the blades after the blades and the shroud in which the slots are formed are welded. Alternatively, the slots are filled with a material different from that of the shroud, such as a resin. With this configuration, distortion caused by welding heat can be reduced without degrading the fluid performance.

Abstract: Abnormality in an amount of a working gas leaked from between a rotating ring adapted to rotate with a rotor and a stationary ring of a turbo fluid machine is detected by a pressure switch and a flow meter, which are provided in a primary seal vent line, the working gas leaking from sealing surfaces of the labyrinth seal and the secondary dry gas seal, together with a purge gas purged to the space from outside is discharged outside the machine from a flow passage via a space. When abnormality generates in the secondary dry gas seal, a control valve provided in the purge gas line operates to secure a flow rate in the purge gas line, so that a flow rate detected by the flow meter provided in the purge gas line increases, and thus abnormality in the secondary dry gas seal is detected.

Abstract: With a turbo type fluid machine provided with a primary dry gas seal (9) and a secondary dry gas seal (10), abnormality in an amount of a working gas leaked from between a rotating ring (7a, 7b) adapted to rotate with a rotor (4) and a stationary ring (8a, 8b) is detected by a pressure switch (14) and a flow meter (15), which are provided in a primary seal vent line (12), and meanwhile, the working gas leaking from sealing surfaces (17) of a labyrinth seal (16) and the secondary dry gas seal, together with a purge gas purged to a space (18) from outside is discharged outside the machine from a flow passage (34) via a space (33) when abnormality generates in the secondary dry gas seal, a control valve (19) provided in the purge gas line operates to secure a flow rate in the purge gas line, so that a flow rate detected by the flow meter provided in the purge gas line increases, and thus abnormality in the secondary dry gas seal is detected.

Abstract: Abnormality in an amount of a working gas leaked from between a rotating ring adapted to rotate with a rotor and a stationary ring of a turbo fluid machine is detected by a pressure switch and a flow meter, which are provided in a primary seal vent line, the working gas leaking from sealing surfaces of the labyrinth seal and the secondary dry gas seal, together with a purge gas purged to the space from outside is discharged outside the machine from a flow passage via a space. When abnormality generates in the secondary dry gas seal, a control valve provided in the purge gas line operates to secure a flow rate in the purge gas line, so that a flow rate detected by the flow meter provided in the purge gas line increases, and thus abnormality in the secondary dry gas seal is detected.

Abstract: A shaft seal system prevents working gas in a centrifugal compressor from leaking outside from the compressor. The shaft seal system is of an oil film seal type and located in the compressor in which a plurality of centrifugal impellers are fitted on a single rotary shaft and are adapted to be rotated at a high speed. The system has two kinds of seal rings, that is, an atmospheric side seal ring and a gas side seal ring, which are loosely fitted in a casing in which bearing for rotatably journalling the rotary shaft are incorporated. A sealing sleeve shrinkage-fitted on the rotary shaft is arranged on the inner diameter side of the two kinds of seal rings. The rotary shaft is formed in its center axial part thereof with a bore extending from a suction side end to a position where the oil film seal is arranged, and a plurality of oil feed holes extending through the rotary shaft from the bore to the outer periphery of the rotary shaft.