JPS6044481B2 - Extraction part structure of extraction turbine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an air bleed turbine, and particularly to the structure of an air bleed section.

[Background of the invention]

FIG. 1 shows an overall conceptual diagram of the extraction turbine.

High-temperature, high-pressure steam from the boiler B passes through the main steam stop valve 1 and the steam control valve 2 to the high-pressure turbine 4 of the extraction turbine 3.
is supplied to The steam that has done work in the high-pressure turbine 4 is divided into steam that is sent to the process steam system P from the extraction port 6 in the extraction section 5 and steam that is sent to the low-pressure turbine 7. In the process steam system P, steam is used for desalination of salt water, for example, so a certain fixed steam pressure is required.

For this reason, a method is used in which the amount of steam supplied to the low pressure turbine 7 is adjusted by opening and closing the extraction control valve 8 to obtain a constant pressure. A bleed partition plate 9 is provided between the high pressure turbine 4 and the low pressure turbine 7 to prevent direct steam from flowing into the low pressure turbine 7. The steam that has done work in the low pressure turbine 7 is discharged from the exhaust port 10 to the condenser C. The power received by the high pressure stage 11 of the high pressure turbine 4 and the low pressure stage 12 of the low pressure turbine 7 rotates a generator 14J directly connected to the rotor 13 to obtain electrical output. Next, regarding the structure of the bleed air turbine bleed section, in the prior art, as shown in FIG. 2, a bleed air control valve 8 of the type that can be operated up and down is disposed above the turbine casing 15. Therefore, as the maximum amount of steam flowing into the low-pressure turbine increases, it is necessary to increase the diameter d of the extraction control valve 8. Increasing the diameter d of the bleed air control valve 8 means increasing the length in the rotor direction when looking at the entire bleed air turbine 3, and therefore, the bleed air control valve 8 is often A large number of small valves are arranged perpendicular to the turbine axis to avoid increasing the axial length. However, even with the above structure, as shown in FIG.
The disadvantage is that it can cause Furthermore, when the amount of steam flowing into the low-pressure turbine increases, as shown in FIGS. 4 and 5, steam is taken out from the turbine casing 15 through the piping 17 and the amount of steam is controlled using the extraction control valve 8, and then the steam is returned to the low-pressure turbine 7. However, since the steam outlet 18 and the steam inlet 19 provided in the casing 15 are connected to the piping 17, they must have a circular shape. The disadvantage is that the free play portion 16 of the device becomes very long. [Object of the Invention] An object of the present invention is to provide a compact bleed turbine structure by minimizing the idle portion of the rotor in the bleed section of the bleed turbine.

[Summary of the Invention] The present invention is characterized in that a plurality of butterfly valve type bleed control valves are arranged in the steam passage extending in the radial direction of the casing in order to minimize the play area of the rotor in the bleed part. In this structure, the high-pressure side steam exhaust port and the low-pressure side steam inlet, which are air extraction parts, are provided over approximately half the circumference of the casing.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to the drawings.

Since the overall general structure is the same as that shown in FIGS. 1 to 3, the explanation will be omitted, and only the different parts will be described.

As shown in FIGS. 6 and 7, in the bleed part 5, the casing 15 is expanded in the radial direction on the opposite side of the bleed port 6 to form an enlarged part 20, and this part is defined as the high pressure side and the low pressure side of the exhaust part. This is the steam passage section 21.

Of the steam that has completed its work in the high-pressure stage 11, the steam required on the process side is extracted from the lower extraction port 6, and the steam flowing to the low-pressure turbine 7 is expanded in the radial direction of the casing 15 from the high-pressure turbine exhaust port 18. Steam flows parallel to the turbine axis toward the low-pressure turbine 7 through a high-low-pressure steam passage section 21 formed between the expanded portion 20 and the outer wall of the original casing 15 . There is a partition wall 24 in the middle of this high and low pressure communicating steam passage section 21, and valve ports 25 are formed in this partition wall 24, and a butterfly valve type bleed air adjustment valve 8 is arranged in each valve port 25. A control mechanism 22 adjusts the opening of a series of bleed control valves 8 via a valve-rod 23. As is clear from FIGS. 6 and 7, the opening of the steam inlet 19 on the low pressure side is provided over approximately half the circumference on an arc whose diameter is the diameter D of the low pressure turbine casing, regardless of the shape of the extraction control valve 8. Therefore, as is clear from the numerical study described below, it is possible to send a large amount of steam to the low pressure turbine 7 side by simply requiring a sufficiently short distance in the turbine axial direction. Let's consider this turbine axial distance by applying specific numerical values.

In the first conventional structure (FIGS. 2 and 3), the diameter of the n bleed control valves is d1, and in the second conventional structure (FIGS. 4 and 5)
In the example shown in Figs. 6 and 7, steam is introduced into the low-pressure turbine from an angle α at the inner diameter D of the casing. When the axial distance at the time of pressure is set as L, the area that allows each required amount of steam to pass is determined, so the following relationship is obtained.NXXXdl2=NX÷×D22=F×π×
DXL where each embodiment is as shown:
If n = 5, N = 2, α = 1800, d1 = 110" gourd, D = 1500 son, then D2 = 174W1In1L =
2h, and in the embodiment of the present invention, the turbine axial distance is
Only 2" is required compared to 4", and the play portion 16 of the rotor can be significantly shortened.

Furthermore, in the calculation example, α=180, but this is changed to 240
It is also possible to apply it by expanding it to the 0th position, and in that case, it is also possible to further shorten the L dimension. In the structure of this embodiment, the extraction control valve 8 is located in the high and low pressure communication steam passage section 21 that is expanded in the radial direction, and when controlling a large amount of steam, the casing is expanded in the radial direction, and the butterfly valve type is used. This can be dealt with by enlarging the bleed air control valve itself, and the effect on the axial distance L dimension is extremely small. Generally, when the amount of controlled steam increases, the casing diameter D is increased accordingly, so that the expanded portion 20 that expands in the radial direction of the casing does not become abnormally large compared to the overall casing structure. . [Effects of the Invention] According to the present invention, it is possible to minimize the rotor play portion of the extraction section of the extraction turbine, thereby achieving the effect that the entire extraction turbine can be made compact.

Another advantage of the embodiment is that the overall length of the rotor can be shortened, which improves the stability of the rotor shaft system.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the entire general extraction turbine;
Figure 2 is a sectional view showing the extraction section of a conventional extraction turbine;
3 is a cross-sectional view in the ■--■ direction in FIG. 2, FIG. 4 is a cross-sectional view showing the extraction section of another conventional bleed turbine, FIG. 5 is a cross-sectional view in the ■--■ direction in FIG. The figure is a sectional view showing an extraction part of an extraction turbine showing an embodiment of the present invention.
FIG. 7 is a sectional view in the direction ■--■ in FIG. 6. 4... High pressure turbine, 5... Air extraction part,
7...Low pressure turbine, 8...Bleed air control valve, 13...Rotor, 15...Casing, 16...Rotor play part, 18...
High pressure turbine exhaust port, 19...Low pressure turbine inlet, 20...Extended portion, 21...Steam passage portion, 22...Control mechanism, 23...・・・・・・
・Bleed air control valve stem.

Claims (1)

[Claims] 1 In the extraction part structure of an extraction turbine that has the function of adjusting the amount of steam flowing from the high-pressure turbine to the low-pressure turbine, the side opposite to the extraction port of the turbine casing is expanded in the radial direction, and the high-pressure turbine exhaust port and the low-pressure turbine are installed inside it. A steam passage connecting the inlets is formed, and a plurality of butterfly-type extraction control valves fixed to the same valve stem arranged perpendicular to the turbine axis are installed in the passage, and the steam passing through the control valves is installed. A bleed part structure of a bleed air turbine, characterized in that the bleed air is guided to a low pressure turbine through a low pressure turbine inlet that is formed over approximately half a circumference or more in the circumferential direction of a low pressure turbine casing.