JPH03288068A - Shaft vibration reducing device for turbo machine - Google Patents

Abstract

PURPOSE:To reduce shaft vibration by providing a resistance plate, having radial grooves formed to prevent the turning of an inflow fluid, on the upstream side of a labyrinth seal provided between a shaft and a casing. CONSTITUTION:Labyrinth seal 14 as a sealing device is provided at a gap 13 between a shaft 11 and a casing 12, and a recessed part 15 coaxial with the shaft 11 is formed at a casing 12, on the fluid flow upstream side of the labyrinth seal 14. An annular resistance plate 16 is fitted at this recessed part 15 in such a way as to close the gap 13, and this resistance plate 16 is formed in the internal tooth gear state and provided with plural radial grooves 18. An operating fluid that is going to flow along the shaft 11 is stopped in its turning by these radial grooves 18, and that its flow speed is lowered before flowing into the labyrinth seal 14. The inner pressure change of the labyrinth seal 14 is not therefore generated easily, and thus shaft vibration is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a shaft vibration reduction device for a turbomachine, which prevents swirling of fluid flowing between a rotating shaft and a casing. This is particularly effective in the case of high-pressure working fluids.

[Prior art] Turbo machines (turbo fluid machines) include a driven machine such as a pump or blower that decelerates a given swirling flow and converts it into pressure, and a turbine or water wheel that converts high-pressure fluid into a low-pressure one. There is a prime mover that allows the water to flow to a certain location and generates a small amount of power during that time.

In any of these turbomachinery, there is a risk of the working fluid leaking from the gap formed between the fixed rotation or the peak and the fixed side casing, so a sealing device is usually installed to seal it. There is.

For example, in the turbine as a prime mover shown in Fig. 4, the rotation? A labyrinth seal 4, which is a non-contact sealing device, is provided in the gap 3 between the ill 1 and the casing 2, and sealing is performed by using the working fluid 11 of the turbine as a sealing gas, or by supplying another sealing gas or extracting air. It is designed to prevent leakage of working fluid.

[Problems to be Solved by the Invention] Even in a turbomachine equipped with such a labyrinth seal 4, the working fluid tends to flow out along the rotating shaft 1. A pressure change occurs in the circumferential direction inside the labyrinth seal 4,
There is a problem in that vibrations of the rotating shaft 1 occur and become more pronounced as the pressure of the working fluid increases.

Therefore, some labyrinth seals 4 are formed with a radial #5 at the end to prevent swirling of the working fluid and reduce the flow velocity. At present, the end portion of the seal 4 is small and the resistance due to the groove 5 is small, so that almost no effect of reducing shaft vibration can be expected at present.

For this reason, conventionally, there have been problems such as the need to detect the vibrations of the rotating shaft 1 of the turbomachine using a contact type sensor and operate the turbomachine while constantly monitoring it.

This invention has been made in view of the problems of the prior art, and aims to provide a shaft vibration reduction device for a turbo machine that can easily reduce the shaft vibration of a turbo machine and allow safe operation. It is something.

[Means for Solving the Problems] In order to solve the above problems, the shaft vibration reduction device for a turbo machine of the present invention includes a labyrinth seal provided between the rotating shaft of the turbo machine and a casing, on the upstream side in the fluid flow direction.
This device is characterized in that a resistance plate is provided in which a plurality of radial grooves are formed to prevent swirling of fluid flowing into the labyrinth seal.

[Function] According to such a shaft vibration reduction device for a turbo machine, a resistance plate is provided on the entrance side of the labyrinth seal of the casing, and a resistance plate is formed that is larger than the end of the labyrinth seal, thereby reducing vibration along the rotation axis. In addition to preventing swirling of the working fluid that is about to flow, the flow velocity is reduced to reduce pressure changes and reduce shaft vibration.

Therefore, the turbomachine can be operated safely.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 and 2 show an embodiment of the shaft vibration reducing device for a turbomachine according to the present invention, with FIG. 1 being a longitudinal cross-sectional view of a main part, and FIG. 2 being a front view of a resistance plate.

In a turbomachine equipped with the shaft vibration reduction device 10 for a turbomachine according to the present invention, a labyrinth seal 14 is provided as a sealing device in a gap 13 between a rotating shaft 11 and a casing 12, and the working fluid of the turbomachine itself is supplied with a sealing gas. Seal is achieved by supplying another sealing gas.

In a turbomachine equipped with such a labyrinth seal 14, a circular recess 15 is formed in the casing 12 on the upstream side of the labyrinth seal 14 in the fluid flow direction, coaxially with the rotating shaft 11. An annular resistance plate 16 is attached with screws 17 so as to close an annular entrance portion of a gap 13 between the rotating shaft 11 and the casing 12.

As shown in FIG. 2, this resistance plate 16 is formed in a shape similar to an internal gear, and a radial groove 18 is formed on the rotating shaft 1.
A plurality of holes are formed at a depth corresponding to the distance from the insertion portion 1 to the casing 12, for example, at intervals of about 10 degrees in the circumferential direction.

Therefore, the gap 13 on the upstream side of the labyrinth seal 14 in the fluid flow direction is closed by the radial groove 18, and the labyrinth seal 14 is located on the downstream side thereof.

Shaft vibration reduction device 10 for a turbo machine configured in this way
According to, for example, in the case of a turbine (prime mover), when high-pressure working fluid is supplied to the impeller, the rotating shaft 11 is rotationally driven and power is extracted, but at the same time, a part of the working fluid is It attempts to flow into the labyrinth seal 14 while being rotated by the rotating shaft 11 and the impeller.

However, since a resistance plate 16 is attached to the casing 12 on the upstream side of the labyrinth seal 14 in the fluid flow direction, the resistance plate 16 is rotated by its radial groove 18. The working fluid that attempts to flow along the line 11111 is stopped from swirling and flows into the labyrinth seal 14 at a reduced inflow speed.

Therefore, pressure changes are less likely to occur inside the labyrinth seal 14, and shaft vibration can be significantly reduced.

When such a resistance plate 16 is installed (Fig. 3(a))
FIG. 3 shows the results of measuring the shaft vibration of the rotating shaft of the turbine in the case where the resistance plate 16 was not attached (FIG. 3(b)).

This vibration measurement was performed by attaching a non-contact eddy current sensor to the bearing portion of the turbine at one location on the circumference of the rotating shaft 11.

As can be seen from the amplitude measurement results, it was confirmed that by providing the resistance plate 16, the amplitude of the vibration of the rotating shaft 11 could be reduced to about 1/7, and that the shaft vibration could be reduced.

In addition, although the above embodiment has been explained in the case where it is applied to a turbine as a turbomachine, it is not limited to this, and can be widely applied to other driven machines, prime movers, and other turbomachines, and the higher the pressure of the working fluid, the more effective it is. .

Further, in the above embodiments, the resistance plate is made separate from the casing, but it may be formed integrally with the casing, and the radial grooves may be formed in the casing itself.

Further, the shape and number of the radial grooves are not limited to those in the embodiments, and any shape and number may be used as long as they provide resistance to swirling of the working fluid.

Further, each component may be changed without changing the gist of the invention.

[Effects of the Invention] As described above in detail with one embodiment, according to the shaft vibration reduction device for a turbo machine of the present invention, a resistance plate is provided on the labyrinth seal population side of the casing, and the resistance plate has radial grooves. , the radial grooves of this resistance plate can prevent the working fluid from swirling as it attempts to flow along the rotation axis, and can also reduce the flow velocity, minimizing pressure changes within the labyrinth seal. This can reduce shaft vibration.

Furthermore, the structure is simple and can be easily applied to existing turbomachinery.

Therefore, the turbomachine can be operated safely.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the shaft vibration reducing device for a turbomachine according to the present invention, with FIG. 1 being a longitudinal cross-sectional view of the main part, and FIG. 2 being a front view of a resistance plate. FIG. 3 is an explanatory diagram of the results of measuring the amplitude of shaft vibration with and without the shaft vibration reduction device of the turbomachine according to the present invention. FIG. 4 is a sectional view of a main part of a conventional example. 10: Axial vibration reduction device for turbo machinery, 11: Rotating shaft, 1
2: Casing, 13: Gap, 14: Labyrinth seal, 15: Recess, 16: Resistance plate, 17: Screw, 18: Radial groove. Figure 3 - Bg (H'') 1 hour (Hr) @Figure 4

Claims (1)

[Claims] A resistance plate is provided on the upstream side in the fluid flow direction of the labyrinth seal provided between the rotating shaft of the turbomachine and the casing, and has a plurality of radial grooves formed therein to prevent the fluid flowing into the labyrinth seal from swirling. shaft vibration reduction device for turbomachinery.