JPS647238B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a horizontally divided casing structure 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 and The present invention relates to a casing structure suitable for manufacturing a casing for use in a turbomachine such as a centrifugal blower by welding.

[Conventional technology]

In conventional single-shaft multi-stage centrifugal compressors, the casing generally has a cast structure.

Such a cast casing structure has the disadvantage that it is difficult to obtain a cast product, and it also takes a long time to manufacture in order to deal with casting defects.

Therefore, in recent years, welded casings have been used instead of cast casings.

As an example, as disclosed in Japanese Unexamined Patent Publication No. 1987-70097, which is an earlier invention of the applicant, a semi-cylindrical nozzle is formed on the outer peripheral surface of the exit scroll portion of the half casing on the side where the exit nozzle is not formed. A second casing is provided, and a passage corresponding to the width of the scroll is provided in the half casing portion to which the second casing is attached, and a scroll groove for forming an exit scroll is formed on the inner surface of the second casing. There is.

[Problem to be solved by the invention]

Although the above-mentioned prior art considers making the casing a welded structure, it requires mechanical cutting work to form the scroll portion, and is still not good from the viewpoint of manufacturing efficiency and man-hour reduction.

In addition, in recent years, there has been a trend in the demand for compressors to include multiple compressors of the same size and type in one plant due to the size of the plant, spare capacity, etc. We are in a situation where we have to produce multiple units.
Under such circumstances, there is a problem that the above-described manufacturing method cannot reduce the manufacturing cost and shorten the delivery time.

The present invention was made based on the above-mentioned circumstances, and an object of the present invention is to provide a horizontally split type welded structure casing that can improve the efficiency of a compressor and is inexpensive to manufacture.

[Means to solve the problem]

The above-mentioned object of the present invention is to provide a horizontally split structure casing for a multi-stage compressor, which is composed of an upper half casing and a lower half casing, and in which each of the casings is joined by a flange formed thereon, in which the scroll part is connected to the outer circumference of the upper half scroll. It consists of an upper roll part formed by welding a shell and a scroll side plate, and a lower scroll part formed by welding a lower scroll outer peripheral shell and a scroll side plate, and these upper scroll part and lower scroll This is accomplished by welding the outer circumferences of the half casings so as to be eccentric with respect to the half casing, and providing the lower scroll section with a rectifying plate forming the scroll section.

[Effect]

The outer peripheries of the upper scroll part and the lower scroll part, which are eccentrically provided on the outer periphery of the half casing, are formed as one circle, and the welded parts of the parts are arranged on one circle, making it easy to automate welding. , the workability can be improved and the manufacturing cost can be reduced. Further, by eccentrically mounting the scroll portion and attaching the rectifying plate to the half casing, the gas passage area of the scroll portion can be smoothly changed, so that the efficiency of the compressor can be improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 shows a centrifugal compressor equipped with an example of the casing of the present invention. In this figure, gas is sucked in from the suction section 1 of the low pressure stage and the pressure is increased sequentially by the impeller of each stage. The gas, which is pressurized by the rear impeller 2, flows in the gas passage section 5 in the circumferential direction, is guided to the scroll section 7 on the discharge side of the low-pressure stage, and flows out from the discharge nozzle to the outside of the cooler. The air is sucked in from the suction section 2 at the high pressure stage, is pressurized by the rear impeller 4, is guided to the scroll section 8 on the discharge side, and is discharged in a predetermined amount from the discharge nozzle.

As shown in FIGS. 2 and 3, the upper half casing 17,
The outer diameter of the lower half casing 18 is d ₁ , and the outer diameters of the upper half scroll outer shell 19 and lower half scroll outer shell 20 are set as D ₁ , and the centers O ₂ and O ₁ of each are on the center of the half plane. The center positions of the scroll parts 7, 8 and the center positions of the casings 17, 18 are spaced _l1 apart on the half plane.

As a result, as shown in FIG. 2, the scroll outer peripheral shell 19 and the intermediate diaphragm support member 14
The groove portion 23 is located inside the upper half scroll outer circumferential shell 19 and the lower half scroll outer circumferential shell 20, and is located inside the scroll side plates 12, 13.
The outer grooves 21 and 22 are on the outer diameter _D1 formed by the upper half scroll outer shell 19 and the lower half scroll outer shell 20, and the inner grooves 24,
25 is the upper half casing 17 and the lower half casing 18
It is located on the outer diameter d ₁ formed by and.

That is, the processing and welding work of the grooves 21, 22, 23 is performed on a circle with the center at _O1 , and the grooves 24, 2
The processing and welding operations in step 5 are performed on a circle with the center _O2 .

In this case, when manufacturing multiple units, there will be no problem even if the beveling work, welding work, and internal processing of the casing are performed in combinations of upper half casing and upper half casing, or lower half casing and lower half casing. None.

The double suction type discharge scroll structure of the welded casing of the present invention is no different from the conventional scrollless type welded structure casing in terms of manufacturing cost and strength, and furthermore, in order to improve efficiency, a half-suction type discharge scroll structure is used. The center O ₂ of the casings 17, 18,
The center _O1 of the scroll outer circumferential shells 19, 20 is eccentric to the half plane.

The embodiment shown in FIG. 4 is a cross section of the low-pressure stage scroll portion 71, where the outer diameter dimension of the upper half casing 171 and the lower half casing 172 is _d2 , and the center thereof is
O ₄ , and upper half scroll outer shell 191
The outer diameter dimension of the lower half scroll outer peripheral shell and 192 is assumed to be D ₂ , and its center is assumed to be O ₃ , and the eccentricity between the two centers O ₃ and O ₄ on the half-section plane is assumed to be l ₂ .

In this way, in the circumferential structure of the scroll portion on the discharge side, the grooves 21 and 2 shown in FIG.
The processing and welding operations 2 and 23 can be performed at a position on the same circle with the center _O3 .

Further, the processing and welding operations of the grooves 24 and 25 shown in FIG. 2 are performed at positions on the same circle with the center _O4 . Therefore, by providing the aforementioned centers O ₃ and O ₄ on the center line of the half casing half surface, the sixth
As shown in the figure, if the outer periphery of the casing C is placed on the roller R and rotated, the grooves 24, 25 can be welded, and if the scroll outer periphery shell is placed on the roller R and rotated, the grooves 21, 22, 23 welding operations can be performed. Alternatively, as shown in Fig. 7, on the turntable T, there may be a
Place the casing C so that O ₃ and O ₄ match,
By rotating the casing C, it can be easily automated. Note that Y is a welding torch.

Moreover, the embodiment shown in FIG.
1, the outer diameter dimension of the upper half casing 173 and the lower half casing 174 is d ₃ , the center is O ₄ , and the upper half scroll outer circumference shell 193
and the outer diameter dimension of the lower half scroll outer shell 194
Let D ₂ be the center, and let O ₃ be the center, and let the eccentricity between the center position of the two be l ₂ on the half-divided surface.

This means that the design dimensions are the same as in the case of the low-pressure stage scroll described above, and the welding work can be easily automated in manufacturing the high-pressure stage scroll by means as shown in FIGS. 6 and 7.

However, the outer diameter d ₃ of half casings 173, 174
is the outer diameter d ₂ of the low-pressure stage side casings 171, 172
There are cases where it is the same and cases where it is different, but there is no problem in either case when working on the grooves 21 to 25.

Center of half casing on half casing surface
The reason why the O ₄ position and the center O ₃ position of the scroll outer shell are made eccentric is simply to improve production efficiency when multiple units are manufactured. This is because the welding work and rough machining of the inside of the casing are performed by combining the half casing with the half casing.

In this case, what must be considered from the fluid design perspective is to smoothly change the gas passage area of the scroll parts 71 and 72 on the discharge side in order to improve the efficiency of the compressor. The gas passage area change in the circumferential direction of the low-pressure stage scroll shown in FIG.
The outer diameter center O ₄ and the scroll outer circumference shell 191,
192, the outer diameter center O ₃ and the eccentricity of l ₂ on the half-section surface are only a combination of two circular shapes. No.

Therefore, in the present invention, a current plate 240 is provided for the non-smooth portion.

Therefore, it was decided that the current plate 240 also follows the following concept in consideration of manufacturing man-hours.

That is, the center of the half casings 171, 172
It is made to be formed from an arc of radius r ₁ centered on a part that is eccentric by l ₃ from O ₄ and eccentric upwards by l ₄ on the half-split surface, and its plate thickness only forms the gas passage area. Therefore, it is made into a thin plate of approximately 15 to 20 mm, and is installed only on the side of the casing where the discharge nozzle _N1 is provided, and is attached by welding between the scroll side plate 12 and the intermediate diaphragm support member 14 shown in Fig. 1. .

Also, regarding the high pressure stage scroll section shown in FIG. 5, the rectifier plate 2
40 into a half casing 17 according to the above idea.
3,174, shifted by _l5 from the center _O4 , formed from an arc with radius _r2 having the center at position _l6 above the half-divided surface, and made a thin plate with a thickness of about 15 to 20 mm, and the discharge nozzle N ₂ is provided only on the side of the casing where the discharge scroll is provided, and is attached by welding between the scroll side plate 13 and the intermediate diaphragm support member 14 shown in FIG. It is possible to reliably ensure a change in gas passage area and improve efficiency.

〔Effect of the invention〕

According to the above explanation, in the welded casing structure of the compressor, the center position of the outer diameter of the half casing and the center position of the outer diameter of the scroll outer shell are two circular circles eccentrically located on the upper and lower half surfaces of the half casing. By using only combinations, the following effects can be obtained.

In other words, since the welding groove processing and welding work when manufacturing the scroll can be mechanized and automated, the scroll can be manufactured in the same number of man-hours as the conventional scroll-less welded structure casing, and therefore the number of man-hours is reduced. The excellent effect is that there is no increase in time, no increase in man-hours, and no increase in cost.

Furthermore, in terms of performance, compared to conventional scroll-less welded structure casings, the compressor as a whole has an excellent effect of improving efficiency by several percent.

Furthermore, it does not look bad and has a good effect in terms of industrial design.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a multi-stage compressor to which the casing of the present invention is applied, Fig. 2 is a longitudinal cross-sectional view showing the main parts of the casing of the present invention, Fig. 3 is a cross-sectional view thereof, and Fig. 4 is the main part of the casing of the present invention. FIG. 5 is a cross-sectional view of the low-pressure stage scroll part in the casing of the invention, FIG. 5 is a cross-sectional view of the high-pressure stage scroll part in the casing of the invention, and FIGS. 6 and 7 are welding of the scroll part in the casing of the invention. It is an explanatory diagram showing work. 12, 13...Scroll side plate, 14
... intermediate diaphragm support member, 17 ... upper half casing, 18 ... lower half casing, 19 ... upper half scroll outer circumference shell, 20 ... lower half scroll outer circumference shell.

Claims (1)

[Claims] 1. In a horizontally split structure casing of a multi-stage compressor, which is composed of an upper half casing and a lower half casing, and in which each of the casings is joined by a flange formed thereon, the scroll part is connected to the outer periphery of the upper half scroll. It consists of an upper scroll part formed by welding a shell and a scroll side plate, and a lower scroll part formed by welding a lower half scroll outer peripheral shell and a scroll side plate. A horizontally divided multistage compressor, characterized in that a lower scroll part is welded to the outer periphery of the half casing so as to be eccentric with respect to the half casing, and a rectifying plate forming the scroll part is provided in the lower scroll part. Shaped welded structure casing. 2. The horizontally split welded structure casing for a multi-stage compressor according to claim 1, wherein the center position of the casing and the center position of the scroll portion are eccentric at a position on the casing half surface.