WO2001077499A1

WO2001077499A1 - Steam turbine and its moisture separating structure

Info

Publication number: WO2001077499A1
Application number: PCT/JP2000/002314
Authority: WO
Inventors: Tetsuaki Kimura; Yoshiharu Nakayama; Naoaki Shibashita
Original assignee: Hitachi, Ltd.
Priority date: 2000-04-10
Filing date: 2000-04-10
Publication date: 2001-10-18
Also published as: JPWO2001077499A1; AU2000236753A1

Abstract

A steam turbine capable of increasing a drain discharging efficiency, comprising an output stage formed of a stationary cascade and a moving cascade, characterized in that the stationary cascade is installed on the inner wall of a diaphragm outer ring (1), and draining holes (10) discharging a drain are formed in the inner wall of the diaphragm outer ring (1) located on the downstream side of the stationary cascade aslant in circumferential direction relative to the radial direction of a rotor.

Description

Specification

Technical field of steam turbine and its moisture separation structure

TECHNICAL FIELD The present invention relates to a steam tarpin used for a nuclear power plant, a geothermal power plant, a thermal power plant and the like, and a moisture separating structure thereof. Background art

Generally, in power plants equipped with axial flow turbines, condensers are installed to reduce the steam pressure at the turbine outlet to a pressure close to vacuum. For this reason, in a steam turbine where the steam temperature at the turbine inlet is high and superheated steam is used, the steam is driven by wet steam in the low-pressure stage near the outlet. For nuclear and geothermal turbines with low inlet steam temperature, most of the stages will be driven in wet steam.

In such a turbine stage operated in wet steam, the loss is larger than that in the case of dry steam, so not only performance is deteriorated, but also droplets (drain) in wet steam are deposited on the rotor blades. The collision could cause erosion, which could impair the reliability of the tarpin.

For this reason, various techniques have been proposed for suppressing the loss of moisture and the occurrence of erosion as described above. For example, Japanese Utility Model Laid-Open No. 59-116502 discloses a steam turbine. The total opening area of the drain holes provided in the outer ring of the nozzle diaphragm is 0.1% to 0.7% of the total opening area of the nozzle outlet. Japanese Patent Publication No. 4 (1995) discloses a honeycomb-type sealing device, in which a plurality of rows of honeycomb cells communicate moisture collected in each honeycomb cell to a moisture drainage channel installed in a cylindrical body. A hole is described.

By the way, the steam flow (drain flow) flowing out from the stationary blade in the turbine stage is approximately 70 to 80 in the turbine axial direction. Flows into the rotor blade at a turning angle of. On the other hand, the drain holes described in the prior art, for example, the above-mentioned Japanese Utility Model Application Laid-Open No. 59-116502, are installed radially in the radial direction along the inner wall of the diaphragm outer ring. When the drain flow having an angle flows into the drain hole, the flow is disturbed, and the resistance to the flow of the drain flow is increased. As a result, the efficiency of the drain to be discharged is reduced. ,.

An object of the present invention is to provide a steam turbine and a moisture separation structure that can improve drain discharge efficiency. Disclosure of the invention

In order to achieve the above object, the present invention provides the following steam turbine and its moisture separator.

That is, in the steam turbine of the present invention, in a steam turbine in which an output stage is composed of a stationary blade row and a moving blade row, the stationary blade row is installed on an inner wall of a diaphragm outer ring. A drain discharge hole for discharging drain is formed in the inner wall of the outer ring of the diaphragm on the downstream side so as to be inclined in the circumferential direction with respect to the radial direction of the rotor.

Further, the moisture separation structure of the present invention includes a plurality of output stages each including a stationary blade row installed on an inner wall of a diaphragm outer ring and a moving blade row installed on a turbine rotor. A drain discharge hole inclined in the circumferential direction with respect to the radial direction of the rotor is formed in the inner wall of the outer ring of the diaphragm on the flow side. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a partial cross-sectional view of a steam turbine according to one embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA of FIG.

Fig. 3 shows the steam flow between the stationary blade and the moving blade.

Figure 4 shows the steam flow in the output paragraph.

FIG. 5 shows the steam flow at the outlet shown in FIG.

FIG. 6 shows the steam flow at the output stage in this embodiment.

FIG. 7 shows a steam flow in the drain discharge hole in the present embodiment.

FIG. 8 shows the relationship between the inclination angle of the drain discharge hole and the drain flow.

FIG. 9 shows the relationship between the inclination angle of the drain discharge hole and the drain discharge efficiency. FIG. 10 shows an example of drain retention in the seal fin ring portion.

FIG. 11 is a partial sectional view of a steam turbine according to another embodiment of the present invention.

FIG. 12 is a detailed view of the drain removal groove shown in FIG.

FIG. 13 shows another embodiment of the drain removal groove.

Fig. 14 shows the relationship between the amount of steam leakage from the paragraph and the pressure difference at the tip of the bucket. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view of a steam turbine according to one embodiment of the present invention. The steam turbine bin shown in FIG. 1 includes a stationary blade 3, a diaphragm outer ring 1 and a diaphragm inner ring 2 for fixing each end of the stationary blade 3 in the radial direction, and a stationary blade 3 viewed from the flow direction of the steam 7. And a moving blade 5 installed on the wake side of the vehicle, and a paragraph structure is formed by these configurations. In addition, the blade root of the rotor blade 5 is fixed to a disk (not shown) of the rotor 4. A shroud cover 6 is provided at the blade tip of the moving blade 5, and a plurality of adjacent moving blades 5 are connected to each other by the shroud cover 6. Further, the diaphragm outer ring 1 holding one end of the stationary blade 3 is fixed to a casing 11 installed on the outer peripheral side thereof. Furthermore, a plurality of seal fin rings 9 are provided on the inner peripheral portion 1a of the diaphragm outer ring 1 at a position facing the shield cover 6 to form a seal, and a cylinder between the diaphragm outer ring 1 and the shroud cover 6 is formed. This prevents vapor 7 as the working fluid from leaking from the space. Further, in this embodiment, between the seal fin rings on the inner wall circumference of the diaphragm outer ring 1 and downstream of the first seal fin ring 9 (between the second and third seal fin rings in the example of FIG. 1). ) A drain discharge hole 10 for draining is installed. The discharge hole 10 is formed so as to communicate from the inner wall of the diaphragm outer ring 1 to an external space 12 formed between the diaphragm outer ring 1 and the casing 11. The drain guided to the external space 12 by the drain discharge hole 10 is supplied to a water heater or the like that is connected to the external space 11 by a bleed pipe (not shown). In FIG. 1, the drain discharge hole 10 is formed in the inner peripheral wall of the diaphragm outer ring facing the shroud cover 6 at the tip of the rotor blade, in other words, between the seal fin rings 9 in which a plurality of sheets are installed. However, the seal fin ring 9 may be formed at a position upstream of the steam flow, that is, at a position upstream of the seal fin ring 9.

FIG. 2 is a cross-sectional view taken along line AA of FIG. In the present embodiment, the discharge holes 10 provided on the inner wall circumference of the diaphragm outer ring 1 are formed so as to have an angle inclined in the circumferential direction with respect to the radial direction of the diaphragm outer ring 1 (rotor 3). ing. By inclining the discharge hole 10 in the circumferential direction in this way, the drain flow can be efficiently drained from the steam flow having a swirl angle flowing out of the stationary blade 3. Can be collected. Details will be described below with reference to the drawings.

Fig. 3 is a diagram showing the steam flow between the stationary blade and the moving blade, Fig. 4 is a diagram showing the steam flow at the output stage when the discharge hole is not inclined in the circumferential direction, Fig. 5 FIG. 5 is a view showing a steam flow of the discharge hole shown in FIG. 4.

As shown in FIG. 3, the steam flowing out of the trailing edge of the stationary blade 3 has a predetermined swirl angle with respect to the axial direction, for example, an angle of 70 to 80 °. The angled steam flow is guided to the leading edge of the bucket 5. At this time, in the prior art in which the discharge hole 10 is not inclined, as shown in FIGS. 4 and 5, the angle between the drain discharge flow and the discharge hole 10 is inconsistent. Drain can not be discharged. That is, as shown in FIG. 5 showing the details of the steam flow in the discharge hole 10, particularly at the inlet of the discharge hole 10, a strong vortex is generated due to the turbulence of the steam flow. As a result, drainage could not be efficiently collected, and erosion could occur.

Next, the steam flow of the present embodiment in which the discharge holes 10 are inclined in the circumferential direction will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 is a diagram showing a steam flow in an output paragraph section in the present embodiment, and FIG. 7 is a diagram showing a steam flow in a discharge hole in the present embodiment. 6 and 7 show the case where the discharge hole 10 is inclined 45 ° in the circumferential direction.

In the present embodiment, in consideration of the inflow steam having a swirl angle, the discharge hole 10 is formed in a structure inclined in the circumferential direction as described above. As a result, compared with the structure in which the discharge holes 10 are not inclined in the circumferential direction shown in FIGS. 4 and 5, the present embodiment allows the drain to be discharged effectively. For example, in Fig. 5, a vortex is generated due to the turbulence of the steam flow at the inlet of the discharge hole 10. However, in this embodiment, the inclination angle of the discharge hole 10 in the circumferential direction is formed so as to match the inflow angle of the steam (drain), so that the shroud force bar 6 and the seal fin ring 9 It is possible to reduce the resistance of the drain flow guided to the discharge hole 10 from the gap. Further, as is apparent from FIG. 7, the generation of the vortex can be suppressed at the inlet of the drain discharge hole 10 without disturbing the drain flow. Therefore, according to the present embodiment, the drain can be efficiently collected, and the occurrence of erosion can be reduced.

Next, the relationship between the inclination angle of the drain discharge hole and the drain flow will be described with reference to FIGS. 8 and 9. FIG. FIG. 8 is a diagram showing the state of the drain discharge flow depending on the inclination angle of the discharge hole, and FIG. 9 is a diagram showing the relationship between the inclination angle of the drain discharge hole and the drain discharge efficiency.

The dotted line in FIG. 8 indicates the radial direction 17 from the center of the evening pin rotor, and indicates the angle of inclination of the turbine rotor in the circumferential direction with respect to the radial direction 17. The inclination angle α is based on the radial direction 17 indicated by the dotted line as the reference, and the positive direction is the same direction (right direction in the figure) as the swirl flow direction of steam (drain). In the figures, (Α) to (Ε) show the drain discharge flow when the inclination angle α of the discharge hole 10 is formed at 130 °, 0 °, 30 °, 45 °, and 60 °. FIG.

First, the configuration shown in (Α) in the figure will be described. (Α) shows a state in which the inclination angle a of the discharge hole 10 is inclined at 130 °, that is, in the direction opposite to the swirl angle of the drain flow. As described above, in the configuration of (Α), since the inclination angle α of the discharge hole 10 greatly impedes the flow 8 of the drain to be discharged, it can be said that the drain discharge efficiency is extremely poor. Also, (Β) in the figure indicates that the inclination angle of the exhaust hole 10 is 0 °, that is, the turbine A discharge hole 10 is formed in a direction perpendicular to the rotor axis. As shown in Fig. 5 (B), in the case of a configuration in which the discharge hole 10 is formed not perpendicularly to the turbine rotor but in the vertical direction with respect to the turbine rotor, the discharge hole 10 Vortex is generated at the inlet of 10 and drainage cannot be said to be efficient.

FIGS. 8 (C) to (E) are diagrams showing the drain flow state when the discharge hole 10 is formed by inclining the inclination angle α in the circumferential direction. (C) shows an inclination angle a of the discharge hole 10 of 30 °, (D) shows an inclination angle α of 45 °, and (Ε) shows an inclination angle of 60 °. As shown in (C) to (Ε), the larger the inclination angle of the discharge hole 10 in the circumferential direction, that is, the more the discharge hole 10 is inclined in the same direction as the swirl component of the drain flow, the more the discharge hole 1 0 It is possible to suppress the generation of vortices at the inlet and its vicinity or the occurrence of turbulence in the drain flow, and it is possible to effectively discharge the drain.

Fig. 9 shows the results of analyzing drainage efficiencies in the configurations shown in (Α) to (Ε) in Fig. 8. As shown in Fig. 9, when the inclination angle α of the drain discharge hole is negative (α less than 0 °), the discharge hole 10 is inclined in the direction that impedes the drain flow as shown in Fig. 8 (Α). Therefore, the drain discharge efficiency is extremely reduced as compared with the case where the inclination angle is positive ((0 <0 °)).

On the other hand, when the inclination angle α is positive, as can be seen from this figure, the drain discharge efficiency is remarkably improved around the point where the inclination angle α exceeds about 20 °. And the angle of inclination exceeds about 45 °, about 60. Emission efficiency is most improved up to the vicinity. If the inclination angle α exceeds about 75 °, the angle becomes too acute with respect to the circumferential direction, and consequently, the flow of the drain flow flowing into the discharge hole 10 is hindered, and the discharge efficiency is reduced. Let me do it. · In addition, although it depends on the tip diameter of the bucket and the number of rotations, in the middle stage of a general turbine adopting the structure of this embodiment, the leakage flow around the drain discharge hole 10 at the tip of the bucket is assumed. The velocity component in the direction is about 100 mZs to 200 m / s, and the velocity component in the radial direction is about 50 m / s to 150 m / s. From the synthesis of this velocity component, the inclination angle of the general drain flow with respect to the radial direction is about 30 to 75 °. Furthermore, in actual manufacturing, when drilling the drain discharge hole 10 with a tool, if the inclination angle is too large, it is not possible to take a sufficient angle to the machined surface and the machining work The upper limit of the inclination angle α of the drain discharge hole is about 70 °, because it becomes difficult to drill the hole and the drilling distance from the inner wall to the outer wall of the diaphragm outer ring becomes extremely long.

As described above, first, considering the drain discharge efficiency, the inclination angle of the drain discharge hole is the circumferential direction of the turbine rotor with respect to the radial direction, that is, the same direction as the velocity component of the drain flow (swirl flow). It may be formed so as to be within the angle range of 20 to 75 °.

Considering that the angle of inclination of the general drain flow in the radial direction is 30 ° or more, and considering the workability of machining the drain discharge hole, the upper limit of the inclination angle of the drain discharge hole is 70 °. For this reason, it is desirable to form the inclination angle α of the drain discharge hole in the range of 30 ° to 70 °.

Further, from the viewpoint of maximizing drain discharge efficiency, it is most effective to form the drain discharge hole with an inclination angle α in the range of 45 ° to 60 °.

According to the present embodiment described above, the drain discharge hole is formed to be inclined in the circumferential direction in accordance with the leaked steam flow flowing in at a swirl angle. For example, in the example of FIG. Shroud cover and seal fin It is possible to reduce the resistance when the drain flow that has flowed from the gap between the drain and the drain flows into the drain discharge hole that discharges the drain, and as a result, it is possible to improve the drain discharge efficiency. In addition, the turbulence of the flow at the drain discharge port entrance is reduced, so that the erosion due to the turbulence can be reduced.

FIG. 10 is a diagram showing an example of drain retention at the blade tip and seal fin ring. The shroud cover 6 of the present embodiment is provided on the blade tip side of the rotor blade 5 and has a stepped portion so that the central portion 6b of the outer peripheral surface of the shroud cover has a larger diameter than the end portion 6a. Is formed.

Next, the seal structure will be described. In this embodiment shown in FIG. 10, seal fin rings 9a and 9b are installed on the diagram outer ring 1 facing the upstream and downstream ends 6a with respect to the steam flow of the shroud cover 6. I have. Further, the seal outer ring 1 is provided between the seal fin rings 9a and 9b and at a position facing the central portion 6b of the shroud cover formed to have a larger diameter than the end 6a of the shroud cover. 9 c and 9 d are installed. The seal fin rings 9c and 9d are formed to have a smaller diameter than the seal fin rings 9a and 9b installed on the one end 6a side of the shroud force bar. Thus, in the present embodiment, the seal structure adopts the multiple fin seal structure.

The multiple fin seal structure described above can drastically reduce the amount of steam leaking from the blade tip, so it is operated in a dry steam region such as a steam turbine for thermal power from the viewpoint of improving efficiency. Used for middle paragraphs that do not have them. However, in a turbine stage operated in a wet steam region such as a nuclear steam turbine, as described above, seal fin rings having different diameters are combined, and a step is formed in the shroud cover. As shown in FIG. 10, the drain 16 tends to stay between the seal fin rings more easily than the normal seal structure. In addition, since a large amount of drain stays between the seal fin rings, erosion may occur in the seal fin ring 9 itself.

On the other hand, in the present embodiment, as shown in FIG. 1 described above, a drain discharge hole 10 is formed in the circumferential direction between seal fin rings 9 installed on the diagram outer ring 1 facing the cover 16. It is formed inclined. In other words, in the example shown in Fig. 1, between the second and third seal fin rings from the upstream side in the axial direction with respect to the steam flow (in Fig. 10, between 9c and 9d). A plurality of drain holes 10 are provided on the inner wall circumference of the diaphragm outer ring 1.

With the above-described configuration, most of the drain 16 stagnated between the seal fin rings described with reference to FIG. 10 can be removed from the drain discharge hole 10. Thus, it is possible to suppress the occurrence of erosion.

Therefore, even in a turbine stage operated in a wet steam range, the above-described drain discharge hole is provided between the seal fin rings at the upstream and downstream ends in the outer peripheral axial direction of the shroud cover of the multiple fin seal structure described in this embodiment. By installing the seal fin, it is possible to remove most of the drain that remains between the seal fin rings, and a large amount of drain stays between the seal fin rings, which may cause erosion of the seal fin ring itself. Can be solved. Therefore, even in a turbine stage operated in a wet steam range, it is possible to adopt a multiple fin seal structure that has a remarkable effect of reducing leaked steam. As a result, the above-mentioned drain discharge hole is not provided. As compared with the conventional seal fin structure, it is possible to achieve an effect that leakage steam can be reduced by about 20%.

Drain mixed with the steam flow having a swirl component from the stator blade outlet and flowing to the tip of the rotor blade is leaked steam flowing through the extremely small gap flow path between the seal fin ring at the tip of the rotor blade and the shroud cover. Is mixed into a two-phase flow, and is discharged to the external space through the drain discharge hole 10. At this time, since the leaked steam discharged to the external space accompanying the drain discharge is the leaked steam flowing through the seal fin at the blade tip, a drain discharge hole is provided before the seal structure at the blade tip. Unlike the prior art described in Japanese Unexamined Patent Publication No. 59-1-16502, there is no need to leak the mainstream steam in the paragraph extra, and the effect of reducing the amount of leaked steam accompanying this drainage is eliminated. As a result, efficiency can be improved. Further, in the case where the drain discharge hole is provided in front of the seal structure at the tip of the bucket, the accumulated drain is discharged from the drain discharge hole along with the steam flow. Since the two-phase mixed gas of steam and drain passes through the extremely small gap flow path formed by the seal fin ring and the shroud force bar, the energy consumption for accelerating the drain increases. As a result, the flow resistance is larger and the amount of steam leakage is smaller than when only steam passes through the gap flow path between the shield fin ring and the shroud cover, which contributes to the improvement of turbine stage efficiency. Can be.

In addition, as in the honeycomb-type seal structure proposed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 4-259604, each one is constituted by a honeycomb cell having only a small expansion space. Instead of a seal structure, the seal is made up of a plurality of seal fin rings as in the present embodiment, and a structure that ensures a sufficiently large thermal expansion space around the entire periphery of the seal fin rings provides a seal. The mixed flow of drain and steam that is saturated before fin ring When passing through the very small gap flow path formed by the ruffin ring and the shroud cover and flowing into the thermal expansion space downstream of the seal fin ring, the pressure is reduced on the downstream side of the seal fin ring to generate flushing, and the leaked fluid is generated. It expands rapidly in the thermal expansion space. At this time, the flow resistance increases due to an increase in the volume flow rate passing through the seal portion, and the turbine stage efficiency is improved by reducing the amount of steam leakage.

FIG. 11 is a partial cross-sectional view of a steam turbine according to another embodiment of the present invention, and FIG. 12 is a detailed view of the drain removal groove shown in FIG. In this embodiment, a drain removal groove 15 is formed on the outer ring 1 of the diaphragm between the seal fin rings in order to further improve the effect of collecting the drain accumulated between the seal fin rings. As shown in FIG. 12, the drain removal groove 15 is formed on the inner wall circumference of the diaphragm outer ring 1 along the circumferential direction along a plurality of drain discharge holes provided on the inner wall circumference. An inclined surface or a step is formed so as to guide the drain to the inlet portion of the 10.

That is, the drain removal groove 15 shown in FIGS. 11 and 12 is provided with the seal fin ring 9 c installed on the upstream side as viewed from the drain discharge hole 10, and also installed on the downstream side. The inner wall of the diaphragm outer ring 1 is configured to be inclined from the seal fin ring 9 d toward the drain discharge hole 10 side. In FIG. 11, the drain removal groove 15 has an inclined shape, but a step may be formed. By forming the drain removal groove 15 on the inner surface of the diaphragm outer ring in the circumferential direction in this manner, there is an effect of accumulating the drain flowing on the inner surface of the diaphragm outer ring 1.

FIG. 13 is a view showing another embodiment of the drain removal groove. In FIG. 11, the drain removal groove 15 is formed along the circumferential direction on the inner wall of the diaphragm outer ring, but in the embodiment shown in this figure, the leakage steam at the blade tip In consideration of the turning component, a drain removal groove 15 is formed on the inner wall of the diaphragm outer ring 1 so as to have an angle with respect to the circumferential direction. Furthermore, in this embodiment, a drain discharge hole 10 is provided on the downstream side in the axial direction of the drain removal groove 15 with respect to the steam flow so as to discharge the accumulated drain most efficiently.

With the above configuration, the blade tip leakage flow 8 having a swirl component causes the drain removal grooves 15 formed so as to be in the same direction as the swirl component to collect the drainage flowing on the inner surface of the diaphragm outer ring 1. It will be easier. Further, by providing the drain discharge hole 10 on the downstream side of the drain removal groove 15, the drain accumulated in the drain removal groove 15 can be discharged most efficiently.

The total area of the drain discharge holes 10 where a plurality of drain holes are installed is about 10% of the entire peripheral area in the gap between the seal fin ring 9 and the shroud cover 6, and the performance is the most efficient.

FIG. 14 is a diagram showing the relationship between the amount of steam leakage from the paragraph and the pressure difference at the tip of the moving blade. The hatched area in the figure shows the effect of the present embodiment. Although the amount of steam leakage increases in proportion to the pressure difference at the tip of the rotor blade, it is clear from this figure that the multiple fin seal structure of the present embodiment using the above-mentioned drain discharge hole should be applied. As a result, it has become possible to reduce the amount of steam leakage by about 30 to 40% compared to the conventional technology.

Further, according to the conventional technique described in Japanese Utility Model Application Laid-Open No. 59-116650, it is possible to discharge most of the scattered water droplets to the external space from the drain discharge hole, Since the drain discharge hole is provided in front of the seal structure, a large amount of the mainstream steam flowing in the paragraph is leaked to the external space at the same time as the drain is discharged. The steam leakage due to drainage is originally caused by turbine stage Steam, which should work effectively to rotate the mouth inside, leaks to the outside without doing work, which reduces turbine efficiency. As described above, the conventional drain discharge structure can remove the wet component in the paragraph by drain discharge and reduce the wet loss of the paragraph.However, the leakage of the mainstream steam causes a decrease in the paragraph efficiency. Was gone. On the other hand, in the present embodiment, since the drain discharge hole is provided downstream of the first seal fin ring, the leakage amount of the mainstream steam can be reduced, and the drain discharge efficiency described above can be reduced. Combined with the improvement in the efficiency, the efficiency of tarpin paragraph can be improved by 1.0%. Industrial applicability

INDUSTRIAL APPLICABILITY The steam turbine and the moisture separation device of the present invention are used in the field of generating electricity by driving a turbine by generated steam.

Claims

The scope of the claims

1. In a steam turbine having an output stage composed of a stationary blade row and a moving blade row, the stationary blade row is installed on an inner wall of a diaphragm outer ring, and a diaphragm downstream of the stationary blade row is provided. A steam turbine, characterized in that a drain discharge hole for discharging drain is formed on an inner wall of an outer ring so as to be inclined in a circumferential direction with respect to a radial direction of the mouth.

2. A row of stationary blades in which a plurality of stationary blades are arranged on the inner wall of the diaphragm outer ring in the circumferential direction of the inner wall of the outer ring of the diaphragm, and a row of rotor blades in which a plurality of rotor blades are arranged in the circumferential direction of the evening bin rotor. In the steam turbine in which an output stage is formed by the stationary blade row and the rotor blade row,

A plurality of drain discharge holes for discharging drain are provided on the inner wall of the diaphragm on the downstream side of the steam flow from the stationary blade row along the circumferential direction of the inner wall of the diaphragm, and the drain discharge holes are formed in the radial direction of the rotor. A steam turbine characterized in that it is formed so as to be inclined in the circumferential direction with respect to.

3. A plurality of stator vanes are arranged on the inner wall of the diaphragm outer ring in the circumferential direction of the inner wall of the diaphragm outer ring, and are sequentially engaged with the outer peripheral portion of the disk of the turbine rotor. A steam cascade in which a plurality of moving blades are arranged, and wherein a stationary blade row and a moving blade row form an output stage;

The moving blade is provided with a shroud cover at a tip thereof, and is installed so that a shroud on the abdominal side of one moving blade and a shroud on the back side of the adjacent moving blade are in contact with each other. A seal structure is formed on the inner wall of the opposed diaphragm outer ring, and a drain discharge hole for discharging drain is formed in the inner wall of the diaphragm outer ring on the downstream side of the stationary blade row in a circumferential direction with respect to a radial direction of the rotor. It is characterized by being formed to be inclined Steam evening bottle.

4. A plurality of stationary blades are arranged on the inner wall of the diaphragm outer ring in the circumferential direction of the inner wall of the diaphragm, and are sequentially engaged with the outer peripheral portion of the disk of the evening bin rotor. A plurality of moving blades arranged in a row, and a steam turbine bin in which an output paragraph is formed by the stationary blade row and the moving blade row;

The moving blade is provided with a shroud cover at a tip thereof, and is installed such that a shroud on the abdominal side of one moving blade and a shroud on the back side of the blade adjacent to the other moving blade come into contact with each other. A seal structure is formed on the inner wall of the opposed diaphragm outer ring, and a drain discharge hole inclined in the circumferential direction with respect to the radial direction of the rotor is formed on the inner wall of the diaphragm outer ring having the seal structure. A steam turbine characterized by being installed.

5. A plurality of stator vanes are arranged on the inner wall of the diaphragm outer ring in the circumferential direction of the inner wall of the diaphragm outer ring, and are sequentially engaged with the outer peripheral portion of the disk of the turbine rotor. A rotor blade row in which the rotor blades are arranged, and in a steam bin where an output paragraph is formed by the stator blade row and the rotor blade row,

The moving blade is provided with a shroud cover at a tip thereof, and is installed so that a shroud on the abdominal side of one moving blade and a shroud on the back side of the adjacent moving blade are in contact with each other. A seal is formed by installing a plurality of seal fin rings on the inner wall of the opposed diaphragm outer ring, and is located between the seal fin rings downstream of the first seal fin ring with respect to the steam flow. A steam turbine characterized by a drain discharge hole that is inclined in the circumferential direction with respect to the radial direction of the rotor on the inner wall of the outer ring of the diaphragm.

6. The drain discharge hole according to any one of claims 1 to 5, wherein the drain discharge hole is formed so as to be inclined at an angular range of 20 to 75 ° in a circumferential direction with respect to a radial direction. Steam turbine.

7. The drain hole according to claim 1, wherein the drain discharge hole is desirably formed to be inclined at an angle of 30 to 70 ° in a circumferential direction with respect to a radial direction. The steam turbine as described.

8. The drain discharge hole is more desirably formed so as to be inclined at an angle of 45 to 60 ° in a circumferential direction with respect to a radial direction. Steam one bottle described in.

9. The steam turbine according to any one of claims 1 to 5, wherein a drain removal groove is formed in the inner wall of the diaphragm outer ring along a circumferential direction thereof, and an inlet of the drain discharge hole is located in the drain removal groove. The steam bottle according to any one of the above.

10. The steam turbine, wherein the opening of the drain discharge hole is formed at a position facing the shroud cover so as to be 10% of a total peripheral area in a gap between the seal fin rings. The steam turbine according to claim 5, wherein:

1 1. A multistage output stage consisting of a stationary blade row installed on the inner wall of the diaphragm outer ring and a moving blade row installed over the turbine port is provided, and the diaphragm outer ring downstream of the stator blade row is provided. A moisture separation structure for a steam turbine, characterized in that a drain discharge hole that is inclined in the circumferential direction with respect to the radial direction of the rotor is formed on the inner wall.

1 2. Equipped with a plurality of output stages composed of a row of stationary blades installed on the inner wall of the diaphragm outer ring, and a row of moving blades installed on the turbine rotor, facing the shroud cover installed on the tip of the moving blade On the inner wall of the diaphragm outer ring A moisture separation structure for a steam turbine, comprising: a sealing device; and a drain discharge hole inclined in a circumferential direction with respect to a radial direction of the rotor, formed on an inner wall of a diaphragm outer ring in which the sealing device is installed.

1 3. In a moisture separation structure of a steam bin with an output stage composed of a stationary blade row installed on the inner wall of the diaphragm outer ring and a moving blade row installed on the turbine rotor,

The moving blade is provided with a shroud cover at a tip thereof, and is installed such that a shroud on the abdominal side of one moving blade and a shroud on the back side of the blade adjacent to the other moving blade come into contact with each other. A plurality of seal fin rings are installed on the inner wall of the facing diaphragm outer ring to form a seal, and the seal fin ring on the downstream side of the seal fin ring on the most upstream side with respect to the steam flow and on the downstream side A moisture separation structure for a steam turbine, wherein a drain discharge hole inclined in a circumferential direction with respect to a radial direction of a rotor is provided on an inner wall of a diaphragm outer ring located further upstream.

14. The drain discharge hole is 20 to 75 in the circumferential direction with respect to the radial direction. The moisture separation structure for a steam turbine according to any one of claims 11 to 13, wherein the moisture separation structure is formed so as to be inclined at an angle range of:

15. The drain hole is desirably in the circumferential direction with respect to the radial direction.

The moisture separating structure for a steam bin according to any one of claims 11 to 13, wherein the steam separating bottle is formed so as to be inclined in an angle range of 30 to 70 °.

16. The drain hole according to claim 11, wherein the drain discharge hole is more desirably formed so as to be inclined at an angle of 45 to 60 ° in a circumferential direction with respect to a radial direction. 4. The moisture separation structure for a steam bottle according to any one of 3.

17. The moisture separation structure of the steam turbine has a drain removal groove formed in the inner wall of the diaphragm outer ring along a circumferential direction thereof, and the drain removal groove has the drain removal groove formed therein. The moisture separation structure for a steam bin according to any one of claims 11 to 13, wherein an inlet portion of the drain hole is located.