JPH04252808A - Control valve for reducing temperature and pressure - Google Patents

Abstract

PURPOSE:To prevent generation of cracking by supplying cooling water from a cooling water supplying pasage to a mixture chamber between an inner gauge which surrounds a seat surface and a valve seat of a valve body, and an outer gauge, and thereby preventing the cooling water from sprinkling to the seat surface of the valve seat of the valve body. CONSTITUTION:A valve body 18 integrated with a valve stem 17 is slidably supported to a valve casing 13 having an inlet flow passage 11 and an outlet flow passage 12. Lower valve body guides 14, 15 are fixed thereto, and also a valve seat 16 is provided at the lower valve body guide 15. A portion slidably supports the valve body 18 of the lower valve body guide 15 serves as an inner gauge 21, while a portion continuous to a lower portion which supports slidably the valve body 18 of the upper valve body guide serves as a cylindrical outer gauge 23 coaxially arranged around the inner gauge and the valve body 18 through a circular mixture chamber 22. A cooling water supplying passage 31 is formed on the valve body 18, while cooling water is supplied from a cooling water suppying passage 32 thereto through a water passage 36. The water is charged from a charging hole 39 formed on an outer peripheral part surrounded by the mixture chamber 22 of the valve body 18.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam temperature and pressure reducing control valve for temperature and pressure reduction of high temperature, high pressure steam in a turbine bypass system of a commercial boiler.

0002

2. Description of the Related Art Conventionally, there is a temperature reducing and pressure reducing regulating valve as described in Japanese Patent Publication No. 35361/1983. This prior art technology includes a valve casing having an inlet flow path and an outlet flow path, a valve seat formed within the valve casing, and a valve body movable toward and away from the valve seat. In a pressure reducing control valve, a cage is provided around the valve stem, a mixing chamber is provided between the cage and the valve stem guide, and a valve shut-off is formed between the valve body provided at the lower end of the valve stem and the valve seat. The inlet steam flowing into the lower region of the mixing chamber from the upper end of the mixing chamber is mixed with the cooling water supplied to the upper region of the mixing chamber from the cooling water supply path formed between the upper end of the cage and the upper end of the valve stem guide. Mix indoors. As a result, the high-temperature, high-pressure inlet steam is depressurized at the constriction between the valve body and the valve seat, mixed with cooling water and cooled, and passes through the cage to the outlet flow path side. be discharged.

0003

However, the prior art has the following problems (1) to (4).

■The structure is such that the cooling water supplied into the mixing chamber from the cooling water supply path falls directly onto the seat surface of the valve body and the valve seat, and the surface hardening of the seat surface and valve seat of the valve body due to erosion and thermal stress. Cracks occur in layers, etc., impairing valve shutoff performance.

■ Regarding the inlet position of the inlet steam to the mixing chamber,
Since the opening position of the cooling water supply path to the mixing chamber is remote, the cooling water is not immediately mixed with the high temperature inlet steam jet immediately after flowing into the mixing chamber, resulting in poor mixing. This poor mixing means that coarse water particles pass through the cage and are discharged to the side of the outlet flow path, and as a result, coarse water particles that impinge on the valve casing cause a large thermal shock to the casing, causing erosion. and thermal stress will impair the life of the casing.

(2) Improper mixing of the inlet steam and cooling water as described in (2) above makes the temperature distribution of the outlet steam non-uniform, impairing the controllability of temperature reduction of the steam.

[0007] The inlet steam flows out to the mixing chamber side from the wide-opening valve constriction formed between the valve body and the valve seat, and the flow tends to be uneven around the valve body. , easy to generate vibration and noise due to self-excited vibration.

(2) In the above (2), the valve seat, which is prone to cracking, is integrally formed with the valve casing, making it difficult to repair and having poor maintainability.

An object of the present invention is to ensure stable temperature and pressure reduction operations without thermal damage to valve components.

The present invention aims to improve maintainability.

[0011]

[Means for Solving the Problems] The present invention as set forth in claim 1 provides a valve casing having an inlet flow path and an outlet flow path, a valve seat formed in the valve casing, and a valve seat that moves into and out of contact with the valve seat. In a steam temperature reduction pressure reducing control valve having a valve body that is movable in the direction of an inner cage provided with a plurality of small holes to enable communication between the inlet flow path and the outlet flow path; and a mixing chamber arranged around the valve body and the inner cage, with a mixing chamber between the valve body and the inner cage. an outer cage having a plurality of small holes that enable communication between the mixing chamber and the outlet flow path; a cooling water supply path extending inside the valve body; The valve body is provided with a water injection hole that opens at the outer periphery of the valve body surrounded by the chamber and supplies cooling water to the mixing chamber.

[0012] The present invention as set forth in claim 2 provides the steam temperature reduction and pressure reduction control valve as set forth in claim 1, further comprising a cooling water supply path provided in the valve body that is connected to an upstream cooling water introduction path and a cooling water introduction path. It consists of a valve body interior separated from the water introduction path by a perforated plate, and a communication port for introducing inlet side steam into the valve body interior on the side opposite to the inlet flow path from the seat surface of the valve body with the valve seat. established,
The cooling water introduced into the valve body is configured to be heated and atomized by steam and then supplied to the mixing chamber from the water injection hole.

[0013] The present invention as set forth in claim 3 provides the steam temperature reduction and pressure reduction control valve as set forth in claim 1 or 2, further comprising a steam streamline of the small hole of the inner cage and a water injection hole of the valve body. The cooling water streamlines intersect with each other at outflow angles with opposite slopes.

[0014] The present invention according to claim 4 is based on claims 1 to 3.
In the steam temperature reduction and pressure reduction regulating valve according to any one of the above, reinforcing ribs are further provided along the circumferential direction of the outer cage.

[0015] The present invention according to claim 5 is based on claims 1 to 4.
In the steam temperature reduction and pressure reduction control valve according to any one of the above, the valve body further has a small diameter between the inner diameter portion of the valve seat and the inner diameter portion of the valve seat on the inlet flow path side from the seat surface of the valve body with respect to the valve seat. A projecting portion that can form a gap is provided, and a steam rectifying surface is provided that projects from the projecting edge of the projecting portion toward the inlet flow path in a concave shape with a reduced diameter around the valve body axis. This is what I did.

[0016] The present invention as set forth in claim 6 is the steam temperature reduction and depressurization control valve as set forth in claim 5, further comprising: a steam streamline of the small hole of the inner cage along a steam rectifying surface of the valve body. It is designed so that it can be installed in the direction.

[0017] The present invention according to claim 7 is based on claims 1 to 6.
In the steam temperature reduction and pressure reduction control valve according to any one of the above, a labyrinth groove is further provided in a portion of the outer periphery of the valve body that is guided in sliding contact with the inner cage.

[0018] The present invention according to claim 8 is based on claims 1 to 7.
In the steam temperature reduction and pressure reduction control valve according to any one of the above, the valve seat ring provided with the valve seat is connected to the valve casing in a freely exchangeable manner.

[0019]

[Operation] According to the present invention as set forth in claim 1, the following (1) is achieved.
~(4) There is an effect as follows.

(1) Cooling water supplied from a cooling water supply path provided in the valve body is supplied to a mixing chamber between an inner cage that covers the seat surface of the valve body and the valve seat, and an outer cage. Therefore, the cooling water supplied to the mixing chamber does not fall on the seat surface of the valve body or the valve seat, and cracks do not occur in the hard surface layer of the seat surface of the valve body or the valve seat due to erosion or thermal stress. This ensures high valve shutoff performance.

(2) The opening position of the cooling water supply path into the mixing chamber, defined by the water injection hole of the valve body, can be arranged close to the inlet position of the inlet steam into the mixing chamber defined by the small hole of the inner cage. Therefore, cooling water can be immediately mixed with the high-speed inlet steam jet immediately after it flows into the mixing chamber, resulting in good mixing and atomization. Therefore, the coarse water particles will not pass through the outer cage and be discharged to the outlet flow path side, and as a result, the coarse water particles will not collide with the valve casing and cause a large thermal shock. Its service life is less likely to be impaired by erosion or thermal shock.

(3) Due to the good mixing of the inlet steam and the cooling water in the above (2), the temperature distribution of the outlet steam becomes uniform, and the temperature reduction controllability of the steam is improved.

(4) The inlet steam flows out from the small hole in the inner cage around the valve body to the mixing chamber side, and as a result of being able to divide and subdivide the flow into equal parts around the valve body, the fluid energy is reduced. It is possible to obtain a large depressurizing effect due to friction loss, and also to prevent vibrations and noise caused by self-excited vibrations due to generation of large vortices and separation.

According to the present invention as set forth in claim 2, the following (
5) It has the following effect.

(5) The cooling water that reaches the inside of the valve body through the cooling water supply path of the valve body is mixed with the inlet steam introduced from the communication port of the valve body, heated, boiled and evaporated, and then released into the valve body. The water is supplied to the mixing chamber through the water injection hole in the body and mixed with the inlet steam supplied to the mixing chamber through the small hole in the inner cage. Therefore, the mixing of the inlet steam and cooling water in the mixing chamber is better, and coarse water particles are less likely to pass through the outer cage and be discharged to the outlet flow path side, thereby preventing the water particles from causing thermal shock to the valve casing. It is possible to reliably prevent this and discharge the temperature-reduced and pressure-reduced steam whose temperature has been reduced uniformly to the outlet flow path.

According to the present invention as set forth in claim 3, the following (
6) It has the following effect.

(6) The inlet steam flowing out from the small hole of the inner cage and the cooling water supplied from the water injection hole of the valve body collide with each other in the mixing chamber with opposite velocity components, so that the high-speed inlet steam and the cooling water The collision speed difference is made larger, and the mixture and atomization can be made more complete.

According to the present invention as set forth in claim 4, the following (
7) It has the following effect.

(7) As a result of reinforcing the outer cage with reinforcing ribs, the outer cage can be made thinner, and as a result, the thermal stress caused by the temperature difference between the inner and outer surfaces of the outer cage can be reduced. Further, when forming reinforcing ribs by making the wall thickness of the outer cage curved, thermal expansion of the outer cage can be absorbed and thermal stress can be reduced.

According to the present invention as set forth in claim 5, the following (
8) It has the following effect.

(8) Foreign matter in the steam moves with the flow of steam along the steam rectifying surface of the valve body, and due to the presence of the overhang, it is allowed to flow down to the small hole side of the inner cage without colliding with the valve body seat surface. It will be done. In addition, when the valve body is closed from the open position, the protrusion of the valve body traps foreign objects around the valve seat.
No foreign matter gets caught between the seat surface of the valve body and the valve seat. This can prevent damage to the seat surface of the valve body and the valve seat.

According to the present invention as set forth in claim 6, the following (
9) It has the following effect.

(9) The inlet steam flows smoothly into the small hole of the inner cage from the steam rectifying surface of the valve body, and there is no sudden change in the direction of steam flow around the valve body, so the vibration is caused by self-excited vibration due to turbulence in the steam flow. This can prevent vibration and noise.

According to the present invention as set forth in claim 7, the following (
10).

(10) The steam flowing through the gap between the outer circumference of the valve body and the inner cage generates vortices due to the unevenness of the gap between the outer circumference of the valve body and the inner cage during valve body assembly, and is self-excited by separation. When there is a risk of vibration, the steam flow is accumulated in the labyrinth groove, and the dynamic pressure is converted into high static pressure. As a result, the pressure is equalized around the entire circumference of the labyrinth groove, and the valve body is placed in the inner cage. Self-excited vibration of the valve body can be prevented by aligning the valve body.

According to the present invention as set forth in claim 8, the following (
11).

(11) Maintainability can be improved by making the valve seat ring freely replaceable with respect to the valve casing.

[0038]

[Embodiment] Fig. 1 is a sectional view showing a steam temperature reduction and pressure reduction control valve according to an embodiment of the present invention, Fig. 2 is an enlarged view of the main part of Fig. 1 when the valve is opened, and Fig. 3(A) is FIG. 3B is a schematic diagram showing the valve in the closed state, and FIG. 3B is a schematic diagram showing the valve in FIG. 1 in the open state.

The steam temperature reduction pressure reduction control valve 10 has an inlet flow path 11
, has a valve casing 13 with an outlet passage 12. An upper valve body guide 14 and a lower valve body guide 15 are fixedly arranged in the valve casing 13 .

The lower valve body guide 15 is provided with a valve seat 16 that communicates the inlet passage 11 and the outlet passage 12.

The upper valve body guide 14 and the lower valve body guide 15 slidably support a valve body 18 integral with the valve stem 17. The valve body 18 is arranged so as to face the valve seat 16.
The valve body 18 moves upward from the base point to bring the seat surface 18A provided on the valve body 18 into contact with and away from the valve seat 16.

A portion of the lower valve body guide 15 that slidably supports the valve body 18 is a cylindrical inner cage 21 . Further, a portion of the upper valve body guide 14 that is connected to the lower part of the part that slidably supports the valve body 18 is a cylinder that is coaxially arranged around the inner cage 21 and the valve body 18 via an annular mixing chamber 22. The outer cage 23 has a shape.

That is, the inner cage 21 is arranged so as to slide around the outer periphery of the valve body 18 and partition the inlet passage 11 and the outlet passage 12 together with the valve body 18, and is opened and closed by the valve body 18 to open and close the inlet. A large number of small holes 24 that enable communication between the flow path 11 and the mixing chamber 22, and furthermore, between the inlet flow path 11 and the outlet flow path 12.
It is equipped with

The outer cage 23 is arranged around the valve body 18 and the inner cage 21, and forms the above-mentioned mixing chamber 22 between the valve body 18 and the inner cage 21, and also forms a connection between the mixing chamber 22 and the outlet. It is provided with a large number of small holes 25 that allow communication with the flow path 12 .

At this time, the outer cage 23 is provided with a plurality of small holes 25 in the circumferential direction at each of a plurality of stages in the vertical axis direction, and the steam flow line direction θ of each small hole 25 is set to the radius of the outer cage 23. The steam line is inclined with respect to the line, and the force exerted on the casing 13 by the steam line ejected from the small hole 25 and colliding with the casing 13 is alleviated. Then, between the vertically adjacent small holes 25, the steam streamline direction θA given to the small hole 25A on the upper stage side and the steam streamline direction θB given to the small hole 25B on the lower stage side are set to the radius line of the outer cage 23. , and the moments of reaction force exerted on the outer cage 23 by the steam flows ejected from the upper and lower small holes 25A and 25B are mutually canceled out, so that rotational force due to the steam flow is not generated on the outer cage 23. .

A cooling water supply path 31 is provided in the valve body 18 . The cooling water supply path 31 includes an upper valve body guide 1.
Cooling water supplied from a cooling water supply pipe 32 connected to the upper end of 4 is passed through a water-permeable porous sleeve 35 sandwiched between upper and lower packings 33 and 34 between the upper valve body guide 14 and the valve body 18; The water is supplied through a water passage 36 bored in a portion of the valve body 18 that faces the inner surface of the sleeve 35 when the valve is opened.

The upper and lower packings 33 and 34 prevent the cooling water filled around the water-permeable sleeve 35 from leaking, and the lower packing 34 prevents the above-mentioned leakage inside the casing 13. The packings 33 and 34 are held by a packing retainer 38 that is tightened into the upper valve body guide 14 by a bolt 37.

A water injection hole 39 communicating with the cooling water supply path 31 is opened in the outer peripheral portion of the valve body 18 surrounded by the mixing chamber 22 . The water injection hole 39 supplies the cooling water supplied to the cooling water supply path 31 to the mixing chamber 22 .

At this time, the cooling water supply path 31 provided in the valve body 18 is connected to an upstream cooling water introduction path 41 and a valve body interior 43 that is partitioned from the cooling water introduction path 41 by a perforated plate 42.
A communication port 44 for introducing inlet side steam into the valve body interior 43 is provided on the side opposite to the inlet flow path 11 from the seat surface 18A of the valve body 18. Thereby, the cooling water introduced from the porous plate 42 into the valve body interior 43 is heated and atomized by the steam introduced from the communication port 44, and is heated to the water injection hole 43.
9 to the mixing chamber 22.

The communication port 44 for introducing the inlet steam into the valve body interior 43 of the valve body 18 is provided on the side opposite to the inlet flow path 11 from the seat surface 18A of the valve body 18, as described above. When the valve is fully closed, in which the valve is in contact with the valve seat 16, the valve can be shut off reliably without using any special means for closing the communication port 44 (see FIG. 3(A)). The communication port 44 communicates with the inlet channel 11 when the valve is opened, and can introduce high-temperature, high-pressure inlet steam into the valve body interior 43 (FIG. 3(B)
reference).

[0051] Note that the steam streamline of the small hole 24 of the inner cage 21 and the cooling water streamline of the water injection hole 39 of the valve body 18 may intersect on the same plane including the valve body axis. . According to this, the inlet steam flowing out from the small hole 24 of the inner cage 21 and the cooling water supplied from the water injection hole 39 of the valve body 18 coaxially collide with each other without shifting within the mixing chamber 22, resulting in a high speed. As a result of being able to impingely mix the cooling water in the central portion of the inlet steam, more complete mixing and atomization can be achieved.

Further, the steam streamline of the small hole 24 of the inner cage 21 is given an upward slope, and the water injection hole 3 of the valve body 18
The cooling water streamlines 9 are given a downward slope, and as a result, both streamlines intersect with each other at outflow angles with opposite slopes.

At this time, the valve body 18 is provided with a plurality of water injection holes 39 in the circumferential direction at each of the two positions in the vertical axis direction, and the cooling water flow line direction θ' of each water injection hole 39 is aligned with the radius line of the valve body 18. It is also possible to reduce the force exerted on the outer cage 23 by the cooling water that is ejected from the water injection hole 39 and collides with the outer cage 23 . Then, between the vertically adjacent water injection holes 39, the flow line direction θA' of the cooling water applied to the water injection hole 39A on the upper stage side and the flow line direction θB' of the cooling water applied to the water injection hole 39B on the lower stage side are set in the valve body 18. The directions are opposite to the radial line, so that the moment of reaction force exerted on the valve body 18 by the cooling water flows ejected from the upper and lower water injection holes 39A and 38B is mutually canceled out, and rotational force due to the cooling water flow is not generated on the valve body 18. You can also.

Further, the outer cage 23 is provided with reinforcing ribs 51 along the circumferential direction, which are formed by curvedly deforming the wall thickness of the outer cage 23.

[0055] The valve body 18 is also provided with a tension member on the side of the inlet flow path 11 from the seat surface 18A, which has a smaller diameter than the inner diameter portion of the valve seat 16 and can form a minute gap between the valve body 18 and the inner diameter portion of the valve seat 16 when the valve is closed. The steam rectifying surface 18C is provided with a projecting portion 18B and protruding from the projecting edge of the projecting portion 18B toward the inlet flow path 11 side in a concave diameter-reduced state around the valve body axis.

At this time, the steam streamlines of the small holes 24 of the inner cage 21 are provided in a direction along the steam rectifying surface 18C of the valve body 18.

The valve body 18 also has an inner cage 21 on the outer periphery.
A labyrinth groove 18D is provided in a portion that is guided in sliding contact with the.

Furthermore, the steam temperature reduction and pressure reduction control valve 10 uses the lower valve body guide 15 provided with the inner cage 21 as a valve seat ring, and the lower valve body guide 15 is provided with the valve seat 16 as described above. This lower valve body guide 15 is attached to the lock nut 5.
2, it is connected to the casing 13 in a freely exchangeable manner.

Next, the operation of the above embodiment will be explained.

In the steam temperature reduction and pressure reduction control valve 10, the steam that has entered the inlet flow path 11 has its flow rate controlled and its pressure reduced in the small hole 24 of the inner cage 21 which is not blocked by the valve body 18, and is sloped upward. and is ejected into the mixing chamber 22.

The other part of the steam that has entered the inlet channel 11 is introduced into the valve body interior 43 through the communication port 44 of the valve body 18 . At this time, the cooling water supplied from the cooling water supply path 31 is ejected from the perforated plate 42 into the valve body interior 43, mixed with the steam introduced from the communication port 44, and heated.
In the boiling and evaporating state, it becomes fine particles and is sprayed into the mixing chamber 22 from the water injection hole 39.

The steam ejected from the small hole 24 of the inner cage 21 and the cooling water sprayed from the water injection hole 39 of the valve body 18 collide and mix in the mixing chamber 22, thereby uniformly reducing the steam temperature. . This steam is rectified by the small hole 25 of the outer cage 23 and discharged from the outlet channel 12.

However, according to the above embodiment, the following (1)
There is the effect of ~(11).

(1) The cooling water supplied from the cooling water supply path 31 provided in the valve body 18 is supplied to the seat surface 18 of the valve body 18.
A and a mixing chamber 22 between an inner cage 21 covering the valve seat 16 and an outer cage 23 are supplied. Therefore, the cooling water supplied to the mixing chamber 22 does not fall on the seat surface 18A of the valve body 18 and the valve seat 16, and the surface hardened layer of the seat surface 18A of the valve body 18 and the valve seat 16 is prevented from being caused by erosion and thermal stress. Ensures high valve closing performance without causing any cracks.

(2) The opening position of the cooling water supply path 31 into the mixing chamber 22 defined by the water injection hole 39 of the valve body 18 relative to the inlet position of the inlet steam into the mixing chamber 22 defined by the small hole 24 of the inner cage 21 can be placed close together. Therefore, the cooling water can be immediately mixed with the high-speed inlet steam jet immediately after it flows into the mixing chamber 22, resulting in good mixing and atomization. Therefore, coarse water particles will not pass through the outer cage 23 and be discharged to the outlet flow path 12 side, and as a result, the coarse water particles will not collide with the valve casing 13 and cause a large thermal shock. ,
The life of the valve casing 13 is less likely to be impaired by erosion or thermal shock.

(3) Due to the good mixing of the inlet steam and the cooling water in the above (2), the temperature distribution of the outlet steam becomes uniform, and the temperature reduction controllability of the steam is improved.

(4) The inlet steam flows out from the small hole 24 of the inner cage 21 around the valve body 18 to the mixing chamber 22 side, and the flow is divided and subdivided into equal parts around the valve body 18. As a result, it is possible to obtain a large pressure reduction effect due to frictional loss of fluid energy, and to prevent vibrations and noise caused by self-excited vibrations due to the generation of large vortices and separation.

(5) The cooling water that has reached the valve body interior 43 through the cooling water supply path 31 of the valve body 18 flows through the communication port 4 of the valve body 18.
The mixture is mixed with the inlet steam introduced from 4, heated, boiled and evaporated, and then flows from the water injection hole 39 of the valve body 18 to the mixing chamber 22.
The steam is supplied to the mixing chamber 22 through the small hole 24 of the inner cage 21 and mixed with the inlet steam supplied to the mixing chamber 22 . Therefore, the mixing of the inlet steam and the cooling water in the mixing chamber 22 is even better, and coarse water particles are less likely to pass through the outer cage 23 and be discharged to the outlet flow path 12 side.
It is possible to reliably prevent thermal shock from being applied to the air, and to discharge the temperature-reduced and pressure-reduced steam whose temperature has been uniformly reduced to the outlet flow path 12.

(6) The inlet steam flowing out from the small hole 24 of the inner cage 21 and the cooling water supplied from the water injection hole 39 of the valve body 18 collide with each other in the mixing chamber 22 with opposite velocity components, thus creating a high-speed inlet. The collision speed difference between steam and cooling water is increased, and mixing and atomization can be more complete.

(7) As a result of reinforcing the outer cage 23 with the reinforcing ribs 51, the outer cage 23 can be made thinner, and as a result, the thermal stress caused by the temperature difference between the inner and outer surfaces of the outer cage 23 can be reduced. Furthermore, when forming the reinforcing ribs 51 by making the wall thickness of the outer cage 23 curved, thermal expansion of the outer cage 23 can be absorbed and thermal stress can be reduced.

(8) Foreign matter in the steam moves along with the steam flow along the steam rectifying surface 18C of the valve body 18, and
8B allows the valve element to flow down toward the small hole 24 side of the inner cage 21 without colliding with the valve element seat surface 18A. Further, when the valve body 18 is closed from the open position, the protruding portion 18B of the valve body 18 captures foreign matter around the valve seat 16, and as a result, foreign matter is caught between the seat surface 18A of the valve body 18 and the valve seat 16. It doesn't get too crowded. As a result, the seat surface 18 of the valve body 18
Damage to A and the valve seat 16 can be prevented.

(9) The inlet steam flows smoothly into the small hole 24 of the inner cage 21 from the steam rectifying surface 18C of the valve body 18, and there is no sudden change in the direction of steam flow around the valve body 18, so that no turbulence in the steam flow occurs. Vibration and noise caused by self-excited vibration can be prevented.

(10) The steam flowing through the gap between the outer periphery of the valve body 18 and the inner cage 21 is caused by the unevenness of the gap between the outer periphery of the valve body 18 and the inner cage 21 when the valve body 18 is assembled, or by peeling. When there is a risk of generating excited vibrations, the steam flow is retained in the labyrinth groove 18D, and the dynamic pressure is converted into high static pressure. As a result, the pressure is equalized around the entire circumference of the labyrinth groove 18D, and the valve body 18 By aligning the valve body 18 with respect to the inner cage 21, self-excited vibration of the valve body 18 can be prevented.

(11) Since the lower valve body guide 15 serving as the valve seat ring can be freely replaced with respect to the valve casing 13, maintainability can be improved.

The steam temperature reduction and pressure reduction control valve 10 has a flow direction in which the steam supplied from the inlet channel 11 pushes up the valve body 18, and has a so-called flow open structure (main plug structure). Therefore, the downstream side of the valve shutoff part becomes reduced pressure steam, and the casing wall thickness on the outlet flow path side can be reduced. Therefore, the occurrence of thermal stress caused by the temperature difference between the inner and outer surfaces of the casing can be alleviated, and the life of the valve can be extended.

[0076]

As described above, according to the present invention, stable temperature and pressure reduction operations can be ensured without thermal damage to valve components.

Furthermore, according to the present invention, maintainability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a steam temperature reduction and pressure reduction control valve according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the main parts of FIG. 1 when the valve is open.

FIG. 3(A) is a schematic diagram showing the valve closed state in FIG. 1;
FIG. 3(B) is a schematic diagram showing the valve in FIG. 1 in an open state.

[Explanation of symbols]

10 Steam temperature reduction pressure reduction control valve 11 Inlet flow path 12 Outlet flow path 13 Valve casing 15 Lower valve body guide (valve seat ring) 16 Valve seat 18 Valve body 18A Seat surface 18B Overhang 18C Steam rectification surface 18D Labyrinth groove 21 Inner cage 22 Mixing chamber 23 Outer cage 24, 25 small hole 31 Cooling water supply route 39 Water injection hole 41 Cooling water introduction channel 42 Porous plate 43 Valve body interior 44 Communication port 51 Reinforcement rib

Claims (8)

[Claims] Claim 1: A steam cooling device comprising a valve casing having an inlet flow path and an outlet flow path, a valve seat formed within the valve casing, and a valve body movable in directions toward and away from the valve seat. In a pressure reducing control valve, the valve body is arranged so as to slide around the outer periphery of the valve body and partition the inlet flow path and the outlet flow path together with the valve body, and is opened and closed by the valve body to enable communication between the inlet flow path and the outlet flow path. A mixing chamber is formed between the valve body and the inner cage, and a mixing chamber is formed between the valve body and the inner cage, and the mixing chamber and the outlet flow path can communicate with each other. an outer cage equipped with a plurality of small holes, a cooling water supply path extending inside the valve body, and an outer cage that communicates with the cooling water supply path and opens on the outer periphery of the valve body surrounded by the mixing chamber; and a water injection hole for supplying water to the mixing chamber. 2. A cooling water supply path provided in the valve body,
It consists of an upstream cooling water introduction path and a valve body interior partitioned from the cooling water introduction path by a perforated plate, and the valve body directs the inlet side steam to the side opposite to the inlet flow path from the seat surface of the valve body and the valve seat. The steam according to claim 1, wherein a communication port is provided for introducing the valve body into the body chamber, and the cooling water introduced into the valve body is heated and atomized by steam and is supplied to the mixing chamber from the water injection hole. Temperature reduction pressure reduction control valve. 3. The steam flow line of the small hole of the inner cage and the cooling water flow line of the water injection hole of the valve body intersect with each other at outflow angles of opposite slopes. Steam temperature reduction pressure reduction control valve. 4. The steam temperature reduction and pressure reduction control valve according to claim 1, wherein reinforcing ribs are provided along the circumferential direction of the outer cage. 5. Provided on the inlet flow path side of the valve body from the seat surface with the valve seat, an overhang portion having a smaller diameter than the inner diameter portion of the valve seat and capable of forming a minute gap between the inner diameter portion of the valve seat, Claims 1 to 3 further include a steam rectifying surface projecting from the protruding edge of the protruding portion toward the inlet flow path in a concave diameter-reduced state around the valve body axis.
4. The steam temperature reduction and pressure reduction control valve according to any one of 4. 6. The steam temperature reduction and pressure reduction control valve according to claim 5, wherein steam streamlines of the small holes of the inner cage are provided in a direction along a steam rectification surface of the valve body. 7. The steam temperature reduction and pressure reduction control valve according to claim 1, wherein a labyrinth groove is provided in a portion of the outer periphery of the valve body that is guided in sliding contact with the inner cage. 8. The steam temperature reduction and pressure reduction control valve according to claim 1, wherein a valve seat ring provided with the valve seat is connected to the valve casing in a freely exchangeable manner.