JPH0133678B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a horizontally split casing for fluid machinery, which is composed of an upper half casing and a lower half casing, and is particularly applicable to single-shaft multi-stage centrifugal compressors, centrifugal blowers, etc. This method is most suitable for use in turbo machines whose casings are manufactured by welding.

[Conventional technology]

For example, in conventional single-shaft multi-stage centrifugal compressors, the casing was generally formed by casting.
However, this cast casing structure has drawbacks such as difficulty in obtaining cast products and prolonging the production time due to casting defects.

Therefore, recently, for example, US Patent No. 3407995
As shown in the specification, a welded casing is often used instead of a cast casing. This welded structure type casing has a cylindrical diaphragm support member attached to the inside of the cylindrical casing via a support, and is connected to the diaphragm support member in order to guide fluid discharged from an impeller provided inside the diaphragm. An exit scroll is formed between it and the casing. Since the cylindrical casing is a pressure-resistant member, it has a cylindrical structure with a uniform diameter in order to have sufficient strength and improve welding and manufacturability.

[Problem that the invention seeks to solve]

Such a welded structure casing has the following drawbacks.

(b) The casing is constructed as a cylindrical body with a uniform diameter located on the outer diameter side of the scroll in order to provide strength and improve welding and manufacturability. As a result, the weight increases significantly, and the number of manufacturing steps including welding and material costs increase, resulting in an expensive product.

(b) The weight of the main body of the compressor increases, leading to an increase in the capacity of related peripheral equipment, that is, maintenance cranes, and an increase in the cost of foundation work.

(c) Efficiency would be improved if the area of the scroll was changed smoothly toward the outlet nozzle, but such a configuration is extremely difficult in this welded casing.

The present invention has been made based on the above-mentioned problems, and an object of the present invention is to provide a horizontally split casing that can provide a sufficient flow path area for the outlet scroll and is easy to process.

[Means for solving problems]

The above object of the present invention is to form the width of the through groove provided in one half casing so as to increase in the radial direction, and to set the width of the scroll groove on the inner surface of the other casing to be equal to the width of the through groove. This is achieved by making the other casing large enough to fit and attaching and fixing this separate casing to the outer periphery of the other casing.

[Effect]

Since the groove width of the scroll groove formed on the inner surface of the other casing is larger than the groove width of the scroll groove formed on the inner surface of one half of the casing, the flow passage area of the exit scroll becomes larger, which improves the efficiency of the turbomachine. can. Furthermore, since a sufficient flow passage area of the outlet scroll can be secured without increasing the wall thickness of the separate casing, bending work of the separate casing becomes easy.

〔Example〕

Embodiments of the horizontally split type casing of the present invention will be described below with reference to FIGS. 1 to 7. In each figure, parts given the same reference numerals indicate the same parts.

FIG. 1 is a longitudinal sectional view showing a single-shaft multistage centrifugal compressor equipped with a horizontally split casing according to the present invention, and FIG. 2 shows only the horizontally split casing shown in FIG. The seen view, FIG. 3, is a view taken along the - line arrow in FIG.

In the figure, 1 is a rotor in which a plurality of impellers 1b are attached to a rotating shaft 1a, and 2 is an impeller 1.
b arranged around the inflow of gas into the impeller;
A diaphragm 3 for regulating and guiding outflow is a horizontally divided casing configured to rotatably support the rotor 1, fix the diaphragm 2, and withstand internal pressure. The horizontally split casing 3 is composed of an upper half casing 3a and a lower half casing 3b. ) and are firmly connected by bolts (not shown).
Scroll grooves 41 and 51 for forming outlet scrolls 4 and 5 are formed on the inner surface of one half casing 3b of the upper and lower half casings 3a and 3b, and the other half casing 3a The parts corresponding to the exit scrolls 4 and 5 are removed so as to form a through groove in the circumferential direction, and another semi-cylindrical casing 6 is installed on the outer peripheral surface of this other half casing to cover the removed part. By forming scroll grooves 42, 52 on the inner surface of this separate casing 6 to form the outlet scrolls 4, 5, the depth of the grooves of the scrolls 4, 5 is deepened and the flow path thereof is increased. It is designed to have a large area. In addition, in the present invention, in order to further increase the flow path area of the exit scrolls 4 and 5, a scroll groove 41 formed on the inner surface of the lower half casing 3b has the same groove width as the scroll grooves 42 and 52 formed on the separate casing 6. , 51. That is, the groove width of the scroll groove 42 is the same as that of the scroll groove 41.
Further, the groove width of the scroll groove 52 is configured to be larger than the groove width of the scroll groove 51. The differential user 7 formed on the outer diameter side of the final stage impeller 1b' has a shortened length, and the outlet scrolls 4 and 5 are directly formed on the outer diameter side of this differential user 7. As shown in the figure, the exit scrolls 4 and 5 are composed of the diaphragm 2, a cut-out portion of the casing 3, and scroll grooves 42 and 52 formed on the inner surface of another casing 6 on the upper half casing 3a side. Further, on the lower half casing 3b side, the scroll grooves 41 and 51 are formed on the inner surface of the diaphragm 2 and the casing 3.

FIG. 4 is a view taken along the - line in FIG. 2. As mentioned above, the groove depth and groove width of the scroll grooves 42 and 52 formed in the separate casing 6 are the same as those of the scroll groove 4 formed on the inner surface of the lower half casing 3b.
1 and 51, it is necessary that the scroll grooves 41 and 42 and the scroll grooves 51 and 52 are connected smoothly at the flange portion 3a'. Changes in the shape of the passages of the outlet scrolls 4, 5 in this flange portion 3a' will be explained with reference to FIGS. 2 and 4. Solid lines or dashed-dotted lines a to e in FIG. 4 indicate the shapes of the exit scrolls 4 and 5 in portions a to e in FIG. 2, respectively. As described above, in this embodiment, the groove depth and groove width of the scroll grooves 42, 52 formed in the flange 3a' portion are configured to gradually increase toward the outlet nozzle 8. Casing 6 separate from formed scroll grooves 41, 51
The scroll grooves 42 and 52 formed in the flange portion 3a' are smoothly connected to each other by the flange portion 3a'.

In addition, in this embodiment, the lower half casing 3b
The groove depths of the side scroll grooves 41, 51 are constant, but the groove depths of the scroll grooves 42, 52 formed in the other casing 6 increase from the flange portion 3a' toward the outlet nozzle 8. It is designed to become progressively deeper.

That is, as shown in FIG. 2, the scroll grooves 42, 52 are machined so that the distance from the center O of the casing 3 to the outer peripheral surface of the exit scrolls 4, 5 gradually increases toward the exit nozzle 8. Thereby, the flow path area of the exit scrolls 4 and 5 is configured to gradually increase. A scroll groove 42 formed in this separate casing 6,
The shape of 52 is shown in FIGS. 5 to 7. FIG. 5 is a bottom view of the second casing, and FIGS. 6 and 7 are a view taken along the - line in FIG. 5 and a view taken along the - line, respectively. With this configuration, if the flow path area of the exit scrolls 4, 5 is gradually increased toward the exit nozzle 8, the flow velocity of the gas flowing out from the final stage impeller 1b' can be made to be approximately equal within the exit scrolls 4, 5. You can make it like this.

Note that the groove widths of the scroll grooves 42 and 52 formed in the different casings 6 can also be gradually increased from the flange 3a' toward the outlet nozzle 8.

The separate casing 6 can be easily manufactured by first forming the scroll grooves 42, 52 on a flat plate, and then bending the flat plate into a semi-cylindrical shape so as to be in close contact with the outer peripheral surface of the upper half casing 3a. Another casing 6 produced in this way
If welded and attached to the upper half casing 3a,
The horizontally split type casing of the present invention can also be easily manufactured. When manufacturing another casing 6 by bending a flat plate, the thickness of the other casing 6 is limited to a thickness that can be bent, so the groove depth of the scroll grooves 42 and 52 cannot be made very deep. . However, since the width of the casing 6 can be freely selected, the scroll grooves 42, 5
The width of the groove 2 can be almost freely increased. Therefore, the exit scrolls 4, 5 can be easily removed without increasing the wall thickness of the separate casing 6 too much.
It is possible to freely set the flow path area so as to obtain high efficiency.

Next, the flow of gas handled in the single-shaft multi-stage centrifugal compressor equipped with a horizontally divided casing according to the present invention will be explained with reference to FIG. Gas is sucked in through the suction nozzle 9, and after being pressurized by the two stages of impellers 1b and 1b' on the low pressure side, it passes from the differential user 7 through the outlet scroll 4, and from the outlet nozzle 8, passes through the pipe 10 and exits the casing 3. After being guided and cooled by the cooler 11 provided in the middle of the pipe 10,
After being sucked in from the suction nozzle 12 on the high pressure side and further boosted in pressure by the three stages of impellers 1b and 1b' on the high pressure side, it passes through the differential user 7 and the outlet scroll 5 and is discharged from the outlet nozzle (not shown) to the discharge pipe 13.
The gas is then sent to the required location outside.

In the embodiment of the present invention described above, the scroll grooves 41 and 51 formed in the lower half casing 3b have a constant groove depth, but the groove depth may be configured to gradually become deeper toward the outlet nozzle 8. is also possible. Further, in this embodiment, the upper half casing 3a
However, depending on the mounting position of the outlet nozzle 8, such as when the outlet nozzle 8 is provided in the upper half casing 3a, a different casing 6 may be attached to the lower half casing 3.
Naturally, it may be attached to the b side. Furthermore, the scope of application of the present invention is that a plurality of impellers 1
The present invention is not limited to single-shaft multi-stage centrifugal compressors in which b are arranged facing each other, but also applies to turbo machines such as single-stage centrifugal compressors and single-shaft multi-stage centrifugal compressors in which multiple impellers are arranged in sequence. It is possible.

〔Effect of the invention〕

As explained above, the horizontally split casing of the present invention is configured such that the groove width of the exit scroll formed in the separate casing is larger than the groove width provided in the half casing. It is possible to obtain a sufficient flow passage area of the exit scroll without increasing the thickness too much, thus improving the efficiency of the turbomachinery, and
When a separate casing is manufactured by bending a flat plate, the bending process can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a single-shaft multistage centrifugal compressor equipped with a horizontally split casing according to an embodiment of the present invention, and FIG. 2 shows only the horizontally split casing shown in FIG. FIG. 3 is a view taken from the - line in FIG. 2, FIG. 4 is a view taken from the - line in FIG. 2, and FIG. 6 is a bottom view showing only the two casings taken out, FIG. 6 is a view taken along the - line in FIG. 5, and FIG. 7 is a view taken along the - line in FIG. 5. 3... Horizontal split casing, 3a... Upper half casing, 3b... Lower half casing, 3a', 3
b'...Flange part, 4, 5...Exit scroll,
41, 42, 51, 52...scroll groove, 6...
... Separate casing, 8... Outlet nozzle.

Claims (1)

[Claims] 1. An upper half casing, a lower half casing,
an outlet nozzle provided in either of the upper and lower half casings, the upper and lower half casings are coupled to each other by an axially extending flange formed therein; has a scroll groove formed on the inner surface of its half casing to form an exit scroll;
One of the upper and lower half casings has a through groove formed on the inner surface of the half casing, which connects to the scroll groove of the one half casing and corresponds to an exit scroll, and a scroll groove that fits into the through groove. In a horizontally split casing for a turbomachine, a horizontally split casing for a turbomachine is provided with another half casing having an inner surface on the outer periphery of the other half casing such that the scroll groove fits into the through groove of the other half casing, The width of the through groove provided in the through groove is formed to increase along the radial direction, the width of the scroll groove on the inner surface of the another casing is formed to be large to match the width of the through groove, and A horizontally split casing characterized by one casing attached and fixed to the outer periphery of the other casing. 2 The width of the scroll groove formed in the flange portion is configured to gradually increase toward the exit nozzle side, and the scroll groove formed in one half casing and the scroll groove formed in another casing are connected to the flange portion. Claim 1 characterized in that the parts are configured to be connected smoothly at the parts.
Horizontally split type casing as described in section.