JP2002250205A - Droplet removing structure for steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide droplet removing structure for a steam turbine, in which removed droplets are not susceptible to returning a main flow passage portion. SOLUTION: The droplet removing structure for a turbine comprises: a casing; a rotor rotatably disposed to the inside of the casing; a moving blade row constituted of a plurality of moving blades arranged to extending radially on an outer periphery of the rotor; a stator blade row constituted of stator blades arranged to extending inward on an inner periphery of the casing and disposed to face a front side or a rear side of the moving blades; a hollow groove annually disposed to the inside of the casing to collect drain; and a passage for flowing the droplets, which are splashed from the moving blades or stator blades to the outer peripheral direction, into the hollow passage. In the droplet removing structure, high-pressure steam is flows in the casing in an axial direction of the rotor. A recessed groove is disposed on an inner peripheral face side to collect the droplets, and a guide plate is disposed in the hollow groove to change the direction of a flow of the droplets flowing from the passage into the hollow groove and then to guide the droplets in the recessed groove.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine, and more particularly to a structure for removing water droplets generated on the outer wall surface (inside a casing) of a steam turbine flow path by wet steam.

[0002]

2. Description of the Related Art In a steam turbine having a flow of wet steam, it is necessary to take measures against erosion caused by water droplets in the wet steam colliding with the moving blades and to reduce wet loss. Various measures have been proposed to reduce moisture. I have. As measures for reducing moisture in a steam turbine, there are JP-A-10-299410, JP-A-3093479, and the like.

[0003]

Among the measures for reducing wet loss, in the drain separator structure in which water droplets are removed from the outlet of the stationary cascade to the outside of the main flow passage, the removed water droplets return to the main flow passage again. May be lost.

An object of the present invention is to improve the thermal efficiency of a steam turbine by making it difficult for the removed water droplets to return, suppressing the reduction in wet loss.

[0005]

According to the present invention, there is provided a hollow groove for drain collection which is annularly arranged inside a casing, and a passage through which water droplets scattered in an outer peripheral direction from a moving blade or a stationary blade flow into the hollow groove. In the water drop removing structure of a steam turbine in which high-pressure steam flows in the axial direction of a rotor in the casing, a recess groove for collecting the water drops is provided on an inner peripheral surface side of the hollow groove, and the hollow is formed through the passage. A guide plate is provided in the hollow groove, in which the water drop flowing into the groove changes direction and is guided to the concave groove.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment illustrating an embodiment of the present invention.

A description will be given while also comparing with a conventional example.

FIG. 1 shows a stage structure of a steam turbine according to the present invention. The output stage includes a plurality of stationary blades formed by a plurality of stationary blades 4 disposed on a diaphragm such as a diaphragm outer ring 2 and an inner ring 3 supported by a casing 1, and a plurality of stationary blades disposed on a rotor 5. And a stationary blade row and a rotor blade row form a set to form one output stage.

In a steam turbine having a wet steam flow containing water droplets, it is effective to effectively eliminate the generated water droplets and reduce the collision speed of the coarse water droplets with the moving blades in order to reduce the wet loss. Among them, the present invention proposes a structure that more effectively eliminates generated water droplets and suppresses generation of coarse water droplets due to the elimination of water droplets.

Conventionally, as a water droplet removing mechanism generally employed, a drain catcher structure for effectively separating and removing water droplets blown to the outer peripheral wall surface by the centrifugal force of the moving blade 6 is provided. A slit structure that sucks a water film formed on the wing surface and wall surface of the stationary blade 4 to suppress generation of coarse water droplets; a drain separator structure that removes water droplets from the outlet of the stationary blade row to the outside of the main flow path portion 7; There is a grooved vane structure in which a groove is machined on the abdominal surface of the stationary blade 4 and a water film is sucked from the groove to remove the film out of the blade passage.

According to the present invention, a hollow groove 30 for drain collection which is annularly arranged inside the casing 1 and a passage 8 through which water droplets scattered from the moving blade 5 or the stationary blade 4 in the outer peripheral direction flow into the hollow groove 30 are formed. In the water drop removing structure of the steam turbine in which high-pressure steam flows in the casing 1 in the axial direction of the rotor 6, a hollow groove 9 for collecting water drops is provided on the inner peripheral surface side of the hollow groove 30, and the hollow groove is formed from the passage 8. The guide plate 10 in which the water drops flowing into the groove 30 turn and are guided to the recessed groove 9, is inserted into the hollow groove 30.
Is provided.

The water droplets flow from the main flow passage 7 through which the steam flows into the hollow groove 30 through the passage 8 and are collected in the recessed grooves 9, so that the water droplets are prevented from returning to the main flow passage 7 again. In addition, the water droplets flowing into the hollow groove 30 are
Since the direction is changed at 0 and guided to the concave groove 9, it is easy to collect in the concave groove 9, and the return of water droplets to the main flow path portion 7 is more effectively suppressed. The improvement in the thermal efficiency of the steam turbine by suppressing the reduction of the wet loss is further improved.

The water droplets collected in the recessed groove 9 are removed from the recessed groove 9.
The water naturally flows downward along the inside, and is collected from the hollow groove 30 by a condenser (not shown) provided outside the casing 1.

This will be described in more detail.

The casing 1 has a rotatable rotor 6 inside. The casing 1 and the rotor 6 are placed horizontally so as to be horizontal. The casing 1 is composed of an upper casing part and a lower casing part which are divided into upper and lower parts.

The rotor 6 has a moving blade 5. The rotor blades 5 have a large number of blades and are arranged at equal pitches so as to extend radially around the outer periphery of the rotor 6. A moving blade row is constituted by the plurality of moving blades 5.

A stationary blade 4 provided inside the casing 1 has a diaphragm outer ring 2 on the outer periphery and a diaphragm inner ring 3 on the inner periphery.
Having. The stationary blades 4 have a large number of blades and are arranged at equal pitches so as to extend from the diaphragm outer ring 2 toward the center (center) of the rotor 6. A stationary blade cascade is constituted by the plurality of stationary blades 4.

Such a stationary blade row and a moving blade row form a set, and a set of output stages is arranged in multiple stages in the axial direction of the rotor 6 to constitute a main part of the steam turbine.
The output stage (a set of stationary blade rows and moving blade rows) is configured such that its diameter gradually increases from upstream to downstream of the main flow path 7 through which high-pressure steam flows.

A hollow groove 30 for collecting drain provided inside the casing 1 is provided between the inner periphery of the casing 1 and the outer periphery of the diaphragm outer ring 2 and is connected in an annular manner.

A passage 8 formed so as to penetrate the outer ring 2 communicates the inner peripheral side of the outer ring 2 with the hollow groove 30. The passages 8 are provided so as to be located between the stationary blade row and the moving blade row that are arranged so as to face each other in the axial direction, and are arranged in large numbers at intervals. The hollow groove 30 is provided with a gap groove 31. This gap groove 31 is 5 m
It is a continuous annular groove of about m to 10 mm.

The gap groove 31 is provided in the casing 1 as a separate part.
And the diaphragm outer ring 2 are required to be combined.
Since the outer periphery of the diaphragm outer ring 2 is fitted into the casing 1, if the gap groove 31 is not present, the outer race 2 collides with a slight dimensional error, so that the gap groove 31 is indispensable as a relief.

A recessed groove 9 is provided on the inner peripheral surface side of the hollow groove 30 (the outer peripheral surface of the diaphragm outer ring 2). This hollow groove 9
Is formed in an annular shape and is disposed so as to be located on the upstream side when viewed from the flow of the high-pressure steam. The depression groove 9 is formed by machining. In order to reduce the time and labor required for machining, the recessed groove 9 may be merely provided in the diaphragm outer ring 2 on the upper casing portion side. Since the water droplets flowing down in the concave groove 9 of the upper casing part flow outside the concave groove 9 at the lower casing part, the necessity of the concave groove 9 on the lower casing part side is small.

The guide plate 10 is provided on the inner peripheral surface side of the hollow groove 30. The guide plate 10 is provided so as to be attached to the side of the passage 8, and has a curved shape such that the front end side is inclined toward the concave groove 9. It is desirable to extend the tip of the guide plate 10 to such an extent that it covers the recessed groove 9 to some extent. The guide plate 10 may be provided only on the upper casing part side. It may be provided only where the passage 8 is provided. It is desirable to attach the guide plate 10 by welding or the like.

Water droplets scattered from the stationary cascade or the rotor cascade pass through the passage 8 from the inside of the diaphragm outer ring 2 and pass through the hollow groove 30.
Flows into. Further, the water droplets guided by the guide plate 10 and collected in the concave groove 9 naturally fall down along the concave groove 9. On the lower casing portion side, the water droplets exit from the recessed groove 9 and flow along the outer peripheral surface side of the hollow groove 30 at a lower portion of the lower casing portion, and are collected by a condenser or the like provided outside the steam turbine. Because

As described above, the water droplets flowing into the hollow groove 30 are guided by the guide plate 10 and are well collected in the concave groove 9, so that the water does not flow back to the main flow path portion 7 through the passage 8 or the gap groove 31. Absent. Since the return of the water droplets to the main flow path portion 7 is more effectively suppressed, the improvement of the thermal efficiency of the steam turbine by suppressing the reduction of the wet loss is further improved.

In another embodiment of the present invention shown in FIG. 2, a recessed groove 9 is provided on the downstream side of the passage 8 when viewed from the flow of steam. The direction of the guide plate 10 is also directed to the recessed groove 9. Even with such a configuration, the same goodness as the embodiment shown in FIG. 1 can be expected.

Another embodiment of the invention shown in FIG.
In accordance with the curvature of the guide plate 10 which is curved by bending the guide plate 10. This makes it easier for water droplets to be guided to the depression groove 9 more reliably, and the effect of collecting water in the depression groove 9 is improved.

[0028]

As described above, according to the present invention, a water droplet removing structure for a steam turbine in which the removed water droplets are difficult to return to the main flow path can be provided.

[Brief description of the drawings]

FIG. 1 is an embodiment employing the present invention.

FIG. 2 is another embodiment employing the present invention.

FIG. 3 is another embodiment employing the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Casing, 2 ... Diaphragm outer ring, 3 ... Diaphragm inner ring, 4 ... Static blade, 5 ... Blade, 6 ... Rotor, 7 ... Main flow path part, 8 ... Passage, 9 ... Depression groove, 10 ... Guide plate.

Claims (6)

[Claims] 1. A casing comprising: a casing; a rotor rotatably provided inside the casing; a plurality of moving blades arranged radially around the outer periphery of the rotor; A stationary cascade composed of stationary blades arranged to extend inward on the inner periphery of the rotor and facing the front side or the rear side of the rotor blade, and annularly disposed inside the casing; A hollow groove for drain collection, and a passage for flowing water droplets scattered in an outer peripheral direction from the moving blade or the stationary blade into the hollow groove, and high-pressure steam is supplied in the casing in the axial direction of the rotor. In the structure for removing water droplets of a flowing steam turbine, a concave groove for collecting the water droplet is provided on the inner peripheral surface side of the hollow groove, and the water droplet flowing into the hollow groove from the passage changes direction and is guided to the concave groove. information Is provided in the hollow groove. 2. The structure for removing water droplets of a steam turbine according to claim 1, wherein said guide plate is formed in a curved shape. 3. The structure for removing water droplets of a steam turbine according to claim 1, wherein the recessed groove is located upstream of the passage as viewed from the flow of the steam. 4. The structure for removing water droplets of a steam turbine according to claim 1, wherein the recessed groove is located downstream of the passage as viewed from the flow of the steam. 5. A rotor blade row including a casing, a rotor rotatably provided inside the casing, a plurality of rotor blades arranged to extend radially around the rotor, and the casing. A stationary cascade composed of stationary blades arranged to extend inward on the inner periphery of the moving blade and arranged so as to face the front side or the rear side of the rotor blade, and provided on the outer periphery of the stationary blade row. A diaphragm outer ring attached to the inner periphery of the casing, a hollow groove for drain collection formed between the inner periphery of the casing and the outer peripheral side of the diaphragm outer ring, and a hole formed through the diaphragm outer ring. And a passage through which water droplets scattered in an outer peripheral direction from the moving blade or the stationary blade flow into the hollow groove, and wherein a high-pressure steam flows in the casing in the axial direction of the rotor. In the droplet removing structure, a concave groove for collecting the water droplets is provided on the inner peripheral surface side of the hollow groove, and a guide plate in which the water droplets flowing into the hollow groove from the passage change direction and are guided to the concave groove is provided. A water drop removing structure for a steam turbine, which is provided in a hollow groove. 6. The casing according to claim 1, wherein the casing comprises an upper casing part and a lower casing part which are vertically divided, and wherein the recessed groove is provided on the upper casing part side. A structure for removing water droplets from a steam turbine.