JPH06193743A - Shaft seal device for rotary machine - Google Patents

Abstract

PURPOSE:To reduce the shaft seal oil quantity and the hydrogen gas consumption quantity, reduce the dimension of a plant, and improve the operation performance, and economize resources, by reducing the quantity of the oil which flow out outside the machine and inside the machine. CONSTITUTION:Spiral grooves 91 and 92 each of which has the screw direction reverse to the revolution direction of a rotary shaft, viewed from the machine inside of a seal ring 71 on the machine outside, and viewed from the machine outside of a seal ring 72 on the machine inside are installed on the inner peripheral surface of the seal ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a shaft sealing device for a rotating machine such as a hydrogen cooled turbine generator.

[0002]

2. Description of the Related Art In a rotary machine such as a turbine generator, it is common to fill hydrogen gas in the machine to improve the cooling effect as the capacity increases. A shaft seal device is provided to prevent the hydrogen gas from leaking out of the machine.

The structure of a general shaft seal device is shown in FIG. Two sets of seal rings (71) and (72) are arranged side by side in the axial direction on the outer circumference of the rotary shaft (1) via gaps (81) and (82), respectively. The seal rings (71), (72) are housed in the space on the inner diameter side of the seal casing (6). The oil pressurized slightly higher than the hydrogen gas inside the machine is supplied to the seal casing (6) from the outside, and the gaps (81), (82) between the rotary shaft (1) and the seal rings (71), (72). In the axial direction toward the outside and the inside of the machine. At this time, the oil flowing through the gaps (81) and (82) flows out in the axial direction while rotating in the rotation direction of the rotary shaft due to the action of the rotation of the rotary shaft.

[0004]

The amount of oil in the shaft sealing device is generally related to the size of the gap between the rotary shaft and the seal ring. The larger the gap, the larger the amount of oil, and the smaller the amount, the smaller the amount. It is desired to reduce the amount of oil from the standpoint of downsizing the plant and increasing efficiency, but reducing the gap reduces the risk of damage to the rotating shaft and seal ring due to foreign matter in the oil. There was concern, and naturally there was a limit.

Further, the oil flowing out to the inside of the machine entrains the hydrogen gas inside the machine, is melted, and returns to the external oil system, so that hydrogen gas consumption related to the amount of oil flowing out to the inside of the machine occurs. Reduce the amount of oil in the machine from the viewpoint of plant miniaturization and resource saving,
Although it is desired to reduce the hydrogen gas consumption as in the above case, the current situation is that there is a limit to this as in the above case.

Therefore, in the present invention, it is possible to reduce the amount of oil spilled into and out of the machine without reducing the gap between the rotary shaft and the seal ring, and thus to reduce the total amount of oil and hydrogen gas consumption. An object of the present invention is to provide a simple shaft sealing device.

[0007]

In order to achieve the above object, in the present invention, a spiral groove is provided on each of the first and second inner peripheral surfaces. The spiral groove has a screw direction opposite to the rotation direction of the rotary shaft when viewed from the inside of the first seal ring on the outside of the machine and when viewed from the outside of the second seal ring on the inside of the machine.

[0008]

With the above structure, the oil having the velocity component in the rotational direction flowing through the gap between the rotary shaft and the seal ring is rotated and flows into the groove. The reaction force receives an axial force in a direction opposite to the axial velocity component that it originally has. That is, a force is generated to push back the first seal ring on the outer side of the machine to the inner side of the machine and a second seal ring of the inner side to the machine side. As a result, the amount of oil flowing out to the outside and inside of the machine is reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In addition, for simplification of the description, it is assumed that the rotating shaft rotates clockwise (clockwise) when viewed from the inside of the machine. (Structure of Example)

In this embodiment, as shown in FIG. 1, a groove in the left-hand screw direction, that is, a groove (91) extending to the right is formed on the inner peripheral surface of the outer seal ring (71). ring
A groove (92) extending in the right-handed screw direction, that is, a groove (92) extending to the left is provided on the inner peripheral surface of the (72).

Further, these grooves stop before the end face in the axial direction. That is, in the outer seal ring (71), the groove (91) extending in the axial direction from the inner side of the machine is stopped before the end face of the outer side of the machine. In the seal ring (72) on the inside of the machine, the groove (92) extending axially from the outside of the machine is stopped before the end surface of the inside of the machine. (Operation of Example)

The flow of oil produced by the above structure is shown by the arrow in FIG. The oil flowing from the inside of the machine into the gap (81) between the rotating shaft (1) and the seal ring (71) outside the machine is
It flows in the axial direction to the outside of the machine while rotating in the same direction as the rotating shaft. Oil flowing from the right in the gap (81), that is, flowing from the right in the figure, extends in the axial direction while the groove (91) leans to the right. It receives the reaction force of and tries to return to the inside of the machine in the axial direction. The oil tends to flow to the outside of the machine in the axial direction due to the pressure difference between the oil inlet and the outside of the machine, but the amount of oil decreases due to the above-described flow of returning to the inside of the machine. Further, if the groove (91) penetrates from the inside of the machine to the outside of the machine, it will flow from the inside of the machine to the outside of the machine due to the pressure difference, but in this embodiment, since the penetration of the groove (91) is eliminated, the groove It is possible to prevent an increase in the amount of oil due to the provision of. (Effects of Embodiment) With the above operation, the amount of oil can be reduced, and the reduction of the amount of oil inside the machine can reduce the consumption of hydrogen gas inside the machine. (Other embodiments)

As another embodiment, as shown in FIG.
There is a means for chamfering the corners of the inlets of the grooves (91), (92) in the direction of rotation to promote the inflow of oil into the grooves. As a result, the above effect of the groove is further improved.

[0014]

As described above, according to the present invention, it is possible to reduce the hydrogen gas consumption amount based on the oil amount and the oil amount inside the machine without reducing the gap of the rotary shaft seal ring. It is possible to downsize the plant, improve operational efficiency, and save resources.

[Brief description of drawings]

FIG. 1 is an external view of a shaft sealing device for a rotating machine showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the flow of oil in FIG.

FIG. 3 is an external view of a shaft sealing device for a rotating machine according to another embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of an upper half part showing the periphery of a shaft sealing device of a conventional rotating machine.

[Explanation of symbols]

1 ... Rotary shaft, 2 ... Bearing, 3 ... External machine, 4 ... Internal machine, 5 ... Bearing bracket, 6 ... Seal casing, 71 ... External seal ring, 72 ... Internal seal ring, 81 ... External gap, 82 ... Inner clearance, 91… Outer seal ring, 92… Inner seal ring groove.

Claims (2)

[Claims] 1. A first and a second seal rings, which are arranged in parallel on the outer periphery of a rotary shaft that penetrates the container so as to face each other in the axial direction, and a seal casing that accommodates these seal rings. A shaft seal for enclosing the high-pressure fluid in the container by causing the high-pressure fluid press-fitted into the seal casing to flow in the gaps formed by the first and second seal rings and the rotating shaft in opposite axial directions. In the device,
A shaft sealing device for a rotating machine, wherein a spiral groove is provided on an inner peripheral surface of the seal ring. 2. The spiral groove has a screw direction opposite to the rotation direction of the rotation shaft when viewed from the second and first seal rings with respect to the first and second seal rings, respectively. The shaft sealing device for a rotating machine according to claim 1.