JPS62271996A - Multi-stage hub flow type fluid machine - Google Patents

Abstract

PURPOSE:To prevent an impeller from being damaged, by fixing a thrust piece to opposed surfaces of diaphragms opposed to the impeller and setting a clearance in the axial direction between the thrust piece and the impeller smaller than the clearance in the axial direction between the other impeller and its directly opposed diaphragm. CONSTITUTION:Thrust pieces 10, 11 are fixed to side surfaces of diaphragms 4A, 4B opposed to side surfaces in the axial direction of a main plate 2a and a side plate 2c of impellers 2. A clearance l1 in the axial direction between point end surfaces of the thrust pieces 10, 11 and side surfaces of the impellers 2 is formed smaller than a clearance l2 in the axial direction between the other impeller and its directly opposed diaphragm. Accordingly, when a rotor moves along the axial direction by damage or the like of a thrust bearing, the thrust piece, which is brought into contact with the impeller absorbing rotary energy, prevents the impeller from being damaged.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a multistage radial flow type fluid machine such as a multistage centrifugal compressor, a multistage mixed flow pump, and a multistage centripetal expander.

(Prior Art) An example of a conventional multi-stage centrifugal compressor is shown in FIG. 4, where 1 is a rotating shaft, and 2 is a rotary shaft 1 that is clamped or shrink-fitted at a predetermined interval along the axial direction. It is an impeller fixed by etc., and consists of a main plate 2a, blades 2b, and side +ff12c. 3 is a casing; 4 is a diaphragm that is fitted and locked in the casing 3 and faces the axial side surface of the impeller 2; 5 is a spacer that regulates the axial distance between adjacent impellers 2; It is fitted. 6 and 7 are labyrinth seals.

The fluid flowing from the previous stage is accelerated and pressurized while flowing through the impeller 2. The energy then enters the diffuser 8, where the velocity energy is converted into pressure energy, and the energy flows through the return flow path 9 into the impeller 2 at the next stage.

(Problems to be solved by the invention) In this type of multi-stage centrifugal compressor, the rotating shaft 1, the impeller 2
The axial position of the rotor is regulated by a thrust bearing (not shown), and the axial clearance between each impeller 2 and the diaphragm 4 facing it is approximately the same across all stages.

Therefore, if the thrust bearing is damaged, each impeller 2
The rotor moves rightward along the axial direction due to the thrust applied to the impeller 2, and almost all of the impellers 2 are connected to the diaphragm 4.
come into contact with Then, since the impeller 2 and the diaphragm 4 are both made of materials with high strength, there was a problem in that they came into contact with each other at high speed, causing a serious accident. To deal with this, a safety device was proposed in which the lubricating oil pressure decreases when the thrust bearing is damaged, automatically stopping the drive motor of the compressor. Since there is a slight time delay before it starts operating, damage to the impeller could not be completely prevented.

(Means for Solving the Problems) The present invention has been proposed in order to solve the above problems, and its gist is to provide a rotary shaft with a rotating shaft at a predetermined interval along the axial direction. A plurality of fixed impellers,
In these multi-stage radial flow type fluid machines equipped with diaphragms facing the axial side surfaces of impellers, a thrust piece made of a soft material is fixed to the facing surface of the diaphragm facing one or more impellers, and this thrust piece is A multi-stage radial flow type fluid machine characterized in that the axial clearance between the impeller and the impeller is smaller than the axial clearance between another impeller and a diaphragm directly opposing the other impeller.

(Function) Since the present invention has the above configuration, when the rotor moves in the axial direction due to damage to the thrust bearing, etc.,
or more impellers contact the thrust piece first. When this thrust piece deforms or wears out, it absorbs the rotational energy of the rotor and prevents damage to the impeller.

(Example) One embodiment of the invention is shown in FIG.

In Fig. 1, 1 is a rotating shaft, 2 is an impeller, 3 is a casing, 4 is a diaphragm, 5 is a spacer, 6.7 is a labyrinth seal, 8 is a diffuser, and 9 is a return flow path. This is the same as the conventional one shown in .

A thrust piece 10 is fixed to the left side surface of a diaphragm 4A that is opposite to the right side surface in the axial direction of the main plate 2a of one impeller 2,
A thrust piece 11 is fixed to the right side surface of the diaphragm 4B, which faces the left side surface in the axial direction of the side plate 2C of the impeller 2. This thrust piece 10.11 may be annular as shown in the upper half of FIG. Alternatively, the thrust pieces 10A, (11A) of the fan-shaped annular body and the spacer pieces 12A may be arranged in an annular shape alternately as shown in the upper half or the lower half of FIG. This thrust piece 10.11 is made of a soft material such as lead or lead alloy, and by embedding its base in the diaphragms 4A and 4B, its tip surface protrudes from the opposing surface of the diaphragms 4A and 4B, and this tip surface and the impeller The axial clearance i between the impeller 2 and the side surface of the impeller 2 is made smaller than the axial clearance 12 between the other impeller and the diaphragm that directly opposes it.

If the thrust bearing (not shown) is damaged, the thrust force applied to each impeller 2 will cause the rotating shaft 1, impeller 2,
The rotor composed of the spacer 5 and the like moves rightward along the axial direction, but at that time, the spacer piece 10 moves toward the impeller 2.
When it comes into contact with the main plate 2a, it deforms and melts itself, thereby removing the generated heat and absorbing the rotational energy of the rotor. In this way, damage to this impeller 2 can be prevented, and other impellers 2 can be prevented from coming into direct contact with the diaphragm 4.

Note that when the rotor moves to the left, such as when the rotor has a balance piston or a counterflow impeller, the thrust piece 11 comes into contact with the side plate 2C of the impeller 2 and is deformed and melted. If the rotor is limited to only one direction of movement due to the structure of the compressor, either one of the thrust pieces 10 or 11 can be omitted. And these thrust pieces 10.11
are embedded in each outer surface of the diaphragms 4A and 4B, so machining thereof is extremely easy.

In addition, as the thrust piece 10.11, pure carbon or a material made of pure carbon mixed with fluororesin can be used, and this material has good dry lubricity, high thermal conductivity, low dry friction coefficient, and is corrosive. High corrosion resistance against gas,
Moreover, since it has excellent plastic workability, the thrust piece 10
．． It is suitable as the material of No. 11. Moreover, it goes without saying that the thrust piece may be fixed to the facing surface of the diaphragm facing two or more impellers.

(Effects of the Invention) In the present invention, a thrust piece made of a soft material is fixed to the opposing surface of a diaphragm facing one or more impellers, and the axial gap between this thrust piece and the impeller is The axial clearance between the rotor and the diaphragm that directly opposes it is made smaller than the axial clearance between the rotor and the diaphragm that directly opposes it. Therefore, if the rotor moves along the axial direction due to damage to the thrust bearing, etc., the thrust piece made of soft material will come into contact with the impeller, causing deformation or wear. This absorbs the rotational energy of the rotor. Therefore, damage to the impeller that has come into contact with the thrust piece can be prevented, and contact between other impellers and the diaphragm can be prevented, thereby preventing such damage.

[Brief explanation of drawings]

FIG. 1 is a partial vertical sectional view showing one embodiment of the present invention, and FIG.
3 and 3 are views taken along the arrow A--A in FIG. 1, respectively, showing the arrangement of the thrust pieces. FIG. 4 is a partial longitudinal sectional view of a conventional multistage centrifugal compressor. Rotating shaft...1, impeller...-2, diaphragm...-4
, Figure 2, Figure 3

Claims (1)

[Claims] In a multi-stage flow-type fluid machine comprising a plurality of impellers fixed to a rotating shaft at predetermined intervals along the axial direction thereof, and a diaphragm facing the axial side surface of these impellers, one or more A thrust piece made of a soft material is fixed to the opposing surface of the diaphragm facing the impeller, and the axial clearance between this thrust piece and the impeller is larger than the axial clearance between the other impeller and the diaphragm that directly opposes it. A multi-stage radial flow type fluid machine characterized by its small size.