JPH0346239Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a centrifugal compressor diaphragm.

Prior Art Taking a multi-stage centrifugal compressor as an example, the horizontally split type centrifugal compressor diaphragm structure according to the prior art will be explained. In FIG. A partially assembled cross-section of the intermediate stage of the compressor connecting the high pressure stages is shown, each impeller of each stage is attached to the main shaft 4 by a key or shrink fit, and the diaphragm 3 is attached to the casing 5. It is fitted at the D section. Note that 6 and 7 represent labyrinth packings, and 8 represents a spacer. Now, to explain the function of the compressor mentioned above, the fluid compressed by the impeller 1 in the previous stage flows in the direction of the arrow in the figure and passes through the differential user section A and the return flow path B to the impeller in the next stage. The diff user is introduced into the inlet C of the wheel 2. Generally, the diff user is often formed in the shape of a parallel wall, and has the function of converting the velocity energy of the fluid at the impeller outlet into pressure energy. The diaphragm 3 is composed of diaphragms 3A, 3B, and 3C that are divided into two on a horizontal plane, and the diaphragm 3B forms a winged return flow path. ing. Note that the structure of each diaphragm is often a cast or welded structure.

In the conventional diaphragm structure described above, the outer circumference is supported by the pressure difference between the front and rear, but the inner circumference collapses toward the upstream side. , the shape of the deformation is larger at the horizontal joint F and smaller at the top G, as shown in FIG. In the figure, the shape before deformation is shown by a solid line, and the shape after deformation is shown by a dotted line. This is explained by the development diagram shown in FIG. 7 at section E (indicated by a dashed line) when the disc of the divided diaphragm shown in FIG. 6 is deformed due to the pressure difference between its front and rear surfaces. In other words, the shape before deformation shown by the solid line is deformed to the shape after deformation shown by the dotted line, and the amount of deformation J is equal to the horizontal joint part F.
It is maximum at the top G and the bottom H of the symmetrical part, respectively. Further, if the flow situation of the fluid in the differential user part A formed by the diaphragm 3 is explained with reference to FIGS. 8 and 9, the fluid flows out from the impeller 2 mounted on the main shaft 4 and The velocity energy of the fluid having the vector shown by the arrow is converted into pressure energy, but in FIG. 9, which shows the flow after deformation at section E in FIG. 6, expanded in the circumferential direction, The tangential component of the flow is significantly disturbed at the horizontal joint F, resulting in a significant drop in efficiency, and if the amount of deformation is large, it may contact the impeller and cause a major accident. In addition, facing FIG. 9, the upper part shows the high pressure side K, and the lower part shows the low pressure side L. Furthermore, as shown in Fig. 10, when the amount of deformation S changes along the circumference, the relative axial position between the impeller outlet and the differential user changes in the circumferential direction, which not only causes a decrease in efficiency. A force that changes periodically as the impeller rotates is applied to the impeller, causing vibration, and when this becomes severe, it may lead to fatigue failure.

The method used to address the above-mentioned drawbacks of the conventional diaphragm structure is to reduce the absolute amount of deformation deflection by making the diaphragm thicker and increasing its rigidity.According to this method, As the overall axial length of the compressor increases, the bearing spacing increases, which reduces the critical speed of the rotor, and when the design limit of the rotating machine is reached, it can be overcome by increasing the number of casings. However, these measures are undesirable as they result in an increase in manufacturing costs.

Problems to be Solved by the Invention This invention provides a centrifugal compressor diaphragm structure in which the deformation caused by the pressure difference before and after is balanced and does not cause a decrease in efficiency and does not lead to accidents. It is in.

Means for Solving the Problems This invention consists of configuring the diaphragm of a centrifugal compressor into a horizontally split type, dividing the diaphragm into double parts in the radial direction by an inner ring and an outer ring, and moving the joint surface of the outer ring to a horizontal position. In addition, the inner ring's joint surface position is shifted from the outer ring's joint surface position in the circumferential direction, and the two are respectively fitted and fixed.

Therefore, according to the configuration of this invention, the top or bottom of the inner ring, which is the least deformable, is fitted into the horizontal joint of the outer ring, which is the most deformable, so that a mutual reinforcing effect works, and this causes the circle of the diaphragm to Changes in the amount of deformation and collapse along the circumferential direction can be minimized and a balanced deformation state can be obtained.

Embodiment Next, an embodiment of this invention will be described with reference to the drawings. In FIGS. 1 and 2, a diaphragm inner ring 32, which is also configured in a horizontally split type, is placed inside a diaphragm outer ring 31, which is configured in a horizontally split type. An outer ring joint part M of the outer ring that is horizontally divided into two is formed by fitting and fixing a flange part 33 projecting in the direction into a groove part 34 molded inside the outer ring. are connected by horizontal flange bolts 9, and the inner ring joint part N of the inner ring, which is divided into two parts, is connected by vertical flange bolts 10 with its joint joining surface perpendicular to the joint joining surface of the outer ring joint part M. The relative assembly positions of the inner and outer rings are maintained by inserting a pair of piece metal fittings 11 between the two wheels. Note that 9' and 10' shown in FIG. 1 indicate insertion holes for the flange bolts 9 and 10 of the outer ring and inner ring, respectively.
Further, the diaphragm outer ring is a diaphragm 3A.
1, 3B1 and 3C1, the diaphragm inner ring is diaphragm 3A2, 3B2 and 3C2.
They are each composed of Furthermore, although the relative deviation angles of the inner and outer rings in the circumferential direction, that is, the relative deviation angles between the surfaces of both joint parts are described above as being orthogonal, it is not necessary to make them orthogonal; Any shift angle may be adopted as long as it does not interfere with the joining work.

Therefore, when the inner and outer ring fitting portion of the diaphragm in this invention is developed at a position corresponding to the E section in FIG. 6 mentioned above, the situation will be as shown in FIG. correspond to the outer ring 31, respectively.

According to the above-mentioned embodiment of this invention, the change in the amount of deformation and inclination along the circumference of the diaphragm, that is, the difference in the amount of inclination between the divided portions and the center portion on the circumference, decreases and the inclination becomes uniform. We are getting closer,
This prevents a decrease in centrifugal compressor efficiency, prevents vibrations caused by flow turbulence in the impeller, and prevents damage accidents caused by this.In order to keep the range of change in the amount of inclination along the circumferential direction to the conventional level, the diaphragm is It can be made thinner, which reduces the axial length of the entire compressor and improves the rigidity of the entire machine, significantly improving reliability and reducing manufacturing costs. It becomes possible.

Effects of the invention As mentioned above, this invention has great practical benefits because it helps improve reliability and reduce costs by preventing efficiency loss, preventing vibration and eliminating causes of accidents, and simplifying the entire machine. There is something.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional side view of the main part showing an embodiment of this invention, Fig. 2 is a cross-sectional view of the previous figure, and Fig.
The figure is a developed view of the fitting part of the inner and outer rings according to this invention, FIG. 4 is a longitudinal side view of the main part of a conventional centrifugal compressor diaphragm, and FIG. 5 is a perspective view of a semicircular disk of the diaphragm. FIG. 6 is a front view of the diaphragm disk, FIG. 7 is a developed view showing the state of the diaphragm disk E before and after deformation, and FIG.
This figure is an explanatory diagram showing the fluid flow situation in the differential user section, Fig. 9 is an explanatory diagram showing the flow situation expanded, and Fig. 10 is an explanatory diagram showing the main parts similarly showing the causes of efficiency reduction and vibration generation. It is an explanatory diagram. 1...Previous stage impeller, 2...Next stage impeller, 3...
Diaphragm, 3A, 3B, 3C... Constituent diaphragm, 9... Outer ring horizontal flange bolt, 10
... Vertical flange bolt of inner ring, 11 ... Piece fitting, 31 ... Diaphragm outer ring, 3A1, 3B
1,3C1... Outer ring configuration diaphragm, 32...
Diaphragm inner ring, 3A2, 3B2, 3C2...
Inner ring constituent diaphragm, 33...Inner ring flange, 3
4...Outer ring groove cutting part, A...Diff user part, B...
...Return channel, C...impeller inlet, D...fitting part, E...expanded surface of diaphragm disk, G...top of diaphragm disk, H...bottom, J...
...Deformation amount, K...High pressure side, L...Low pressure side, M...
Outer ring joint, N: Inner ring joint, S: Deformation amount.

Claims (1)

[Scope of utility model registration request] A centrifugal compressor diaphragm having a horizontally split diaphragm structure, characterized in that the diaphragm is divided into an inner ring and an outer ring, and the respective joint surfaces are fitted and fixed with relative shifts.