JP7802549B2 - Steam valve and power generation system - Google Patents

Description

This disclosure relates to a steam valve and a power generation system.

For example, in a power generation system that uses a steam turbine, a steam valve is used to adjust the amount of steam supplied to drive the steam turbine in response to load changes, and to stop the supply of steam to the steam turbine in the event of an abnormality. A steam valve typically comprises a valve seat with an opening, a valve stem that moves a valve disc located opposite the opening of the valve seat in a direction toward and away from the valve seat, and a cylindrical support member that slidably supports the valve stem. With a steam valve configured in this way, it is important to suppress wear caused by rotation and rattle of the valve disc due to steam.

An example of this type of steam valve structure is Patent Document 1. This document discloses a steam valve (main steam stop valve) for a steam turbine in which the flat surface of the valve disc (a surface parallel to the axial direction of the valve stem) and the flat surface of the valve stem (a surface parallel to the axial direction of the valve stem) are in surface contact at the fitting portion between the valve disc and the valve stem.

JP 2014-70513 A

Some steam valves have a stop valve that includes a valve stem, a daughter valve located at the tip of the valve stem, and a parent valve (a configuration corresponding to the valve element disclosed in Patent Document 1) with a through hole through which steam flows when the daughter valve opens. In such steam valves, the daughter valve connected to the actuator opens before the parent valve, thereby opening the through hole in the parent valve, thereby reducing the pressure difference between upstream and downstream of the parent valve and facilitating the opening operation of the parent valve.

In a steam valve having the above configuration, from the perspective of suppressing wear on the stop valve, it is important to support the parent valve so that it does not rotate or rattle relative to the valve stem when the daughter valve and parent valve are open. However, in the valve structure disclosed in the above-mentioned Patent Document 1, the valve stem and valve disc are engaged so that their flat surfaces come into contact at the fitting portion, making it difficult to support the parent valve so that it does not rotate or rattle relative to the valve stem when the daughter valve and parent valve are fully open. As a result, when the daughter valve and parent valve are fully open, the parent valve comes into contact with the valve stem, which can cause wear on the stop valve.

At least one embodiment of the present disclosure has been developed in consideration of the above circumstances, and aims to provide a steam valve and a power generation system that can suppress wear on the stop valve when the child valve and parent valve are fully open.

In order to solve the above problems, at least one embodiment of a steam valve according to the present disclosure comprises:
a valve body having a steam flow path through which steam flows and a valve seat provided midway along the steam flow path and having an opening;
a valve stem extending in an axial direction of an axis and capable of advancing and retreating in the axial direction; a daughter valve fixed to the tip of the valve stem at the tip; a parent valve including a through portion into which a portion of the tip of the valve stem located closer to the base end of the valve stem than the tip is inserted, the parent valve abutting against the valve seat to close the steam flow path and having a through hole through which the steam flows when the daughter valve is opened; and a stop valve at least partially covering the daughter valve from the upstream side of the steam flow path and having a cap fixed to the parent valve.
Equipped with
The parent valve functions as a valve seat for the child valve, is not fixed to the valve stem, and is configured to be movable forward and backward in the axial direction,
The cap is attached to the child valve such that movement away from the child valve is restricted.

In order to solve the above problems, a power generation system according to at least one embodiment of the present disclosure includes:
a steam valve according to at least one embodiment of the present disclosure;
a boiler for generating steam;
a steam turbine driven by the steam;
a steam supply pipe connecting the boiler and the steam turbine and supplying the steam to the steam turbine;
Equipped with
The steam valve is provided on the steam supply pipe.

At least one embodiment of the present disclosure provides a steam valve and a power generation system that can suppress wear on the stop valve when the child valve and parent valve are fully open.

1 is a schematic configuration diagram of a power generation system according to an embodiment. 2 is a cross-sectional view showing the configuration of the steam valve of FIG. 1 in a state where both the child valve and the parent valve are in a closed state. FIG. FIG. 3 is an enlarged view of area A in FIG. 2 . 4 is a schematic diagram showing a state in which the child valve in the steam valve shown in FIG. 3 is opened first while the parent valve is closed. FIG. 1 is a flowchart illustrating a method for assembling a stop valve according to one embodiment. 6A to 6C are explanatory diagrams corresponding to the steps in FIG. 5 . 6A to 6C are explanatory diagrams corresponding to the steps in FIG. 5 . 6A to 6C are explanatory diagrams corresponding to the steps in FIG. 5 . 6A to 6C are explanatory diagrams corresponding to the steps in FIG. 5 . 6A to 6C are explanatory diagrams corresponding to the steps in FIG. 5 . 6A to 6C are explanatory diagrams corresponding to the steps in FIG. 5 . This is a modification of FIG.

Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure and are merely illustrative examples.

(Overall configuration of the power generation system)
First, a power generation system 1 to which a steam valve 14 according to at least one embodiment of the present disclosure is applied will be described. Fig. 1 is a schematic configuration diagram of the power generation system 1 according to one embodiment. The power generation system 1 includes a steam turbine 10, a boiler 11, and a generator 26.

The steam turbine 10 is a turbine driven by steam generated in the boiler 11. The steam turbine 10 is connected to the boiler 11 via a first steam supply pipe 12, and is driven by the supply of high-pressure steam generated by burning fuel in the boiler 11. A steam valve 14 is provided on the first steam supply pipe 12 to adjust the flow rate of steam supplied to the steam turbine 10. The configuration of the steam valve 14 will be described in detail later, and includes a regulator valve 43 and a stop valve 45.

In this embodiment, a multi-stage turbine is exemplified as the steam turbine 10, and the steam turbine 10 includes, from upstream in the steam flow path, a high-pressure steam turbine 31, an intermediate-pressure steam turbine 32, and a low-pressure steam turbine 33. The high-pressure steam turbine 31 is driven by steam (high-pressure steam generated in the boiler 11) supplied from the first steam supply pipe 12. The steam that has completed its work in the high-pressure steam turbine 31 is supplied to the intermediate-pressure steam turbine 32 via the second steam supply pipe 16. A reheater 18 is provided on the second steam supply pipe 16.

The intermediate-pressure steam turbine 32 is driven by steam supplied from the second steam supply pipe 16 (steam that has completed its work in the high-pressure steam turbine 31). The steam that has completed its work in the intermediate-pressure steam turbine 32 is supplied to the low-pressure steam turbine 33 via the third steam supply pipe 25. The low-pressure steam turbine 33 is driven by steam supplied from the third steam supply pipe 25 (steam that has completed its work in the intermediate-pressure steam turbine 32).

Each turbine (high-pressure steam turbine 31, intermediate-pressure steam turbine 32, and low-pressure steam turbine 33) that makes up the steam turbine 10 shares a common rotating shaft 35. A generator 26 is connected to the rotating shaft 35, and the rotation of each turbine drives the generator 26, generating electricity.

(Configuration of steam valve 14)
Next, the configuration of the steam valve 14 according to the first embodiment will be described with reference to Figures 2 to 4. Figure 2 is a cross-sectional view showing the configuration of the steam valve 14 in Figure 1 with both the child valve 62 and the parent valve 64 in a closed state, Figure 3 is an enlarged view of area A in Figure 2, and Figure 4 is a schematic diagram showing the steam valve 14 shown in Figure 3 in a state where the child valve 62 opens first while the parent valve 64 remains closed.

In Figures 2 to 4, O1 is the axis of the valve stem 61 that constitutes the stop valve 45, and O2 is the axis of the valve stem 55 that constitutes the regulating valve 43. The direction in which the axes O1 and O2 extend (hereinafter referred to as the "axial direction Z") is, for example, approximately vertical.

First, as shown in FIG. 2, the steam valve 14 comprises a valve body 41, a regulating valve 43, a stop valve 45, and actuators 46A and 46B. The valve body 41 has a flow path partition section 47 and a valve seat 48. The flow path partition section 47 partitions the steam flow path 52 and accommodates a portion (tip side) of the regulating valve 43 and a portion (tip side) of the stop valve 45. The steam flow path 52 has an inlet section 52A and an outlet section 52B. The inlet section 52A is connected to the boiler 11 via one side of the first steam supply pipe 12, and high-pressure steam generated in the boiler 11 is introduced therein. The outlet section 52B is connected to the high-pressure steam turbine 31 via the other side of the first steam supply pipe 12. The amount of steam supplied from the boiler 11 to the high-pressure steam turbine 31 via the first steam supply pipe 12 can be adjusted by controlling the opening of the regulator valve 43 in the steam valve 14 provided on the first steam supply pipe 12 while the stop valve 45 is open.

The flow path partition 47 includes a first guide member 47A and a second guide member 47B. The first guide member 47A is arranged to cover the outer peripheral surface of the portion of the valve stem 55 that constitutes the regulating valve 43 that is not exposed to the steam flow path 52. The first guide member 47A functions as a guide that guides the valve stem 55 in the axial direction Z. The second guide member 47B is arranged to cover the outer peripheral surface of the rod-shaped portion 61B that constitutes the stop valve 45. The second guide member 47B functions as a guide that guides the valve stem 61 in the axial direction Z.

The valve seat 48 is provided in a flow path partition section 47 located midway through the steam flow path 52. The valve seat 48 has a ring shape centered on the axis O1, and is configured so that the axis of the valve seat 48 coincides with the axis O1. The valve seat 48 has a valve seat surface 48a exposed to the steam flow path 52. The valve seat surface 48a is, for example, a curved surface. The parent valve 64 that constitutes the stop valve 45 and the tip 56A of the regulating valve main body 56 that constitutes the regulating valve 43 can each abut against the valve seat surface 48a.

The control valve 43 is positioned upstream of the stop valve 45 in the steam flow direction. The control valve 43 has a valve stem 55 and a control valve body 56. The valve stem 55 extends in the axial direction Z, with its tip end positioned in the steam flow path 52. The axis O1 of the valve stem 55 is configured to coincide with the axis O2 of the valve stem 55 of the stop valve 45. The valve stem 55 is movable in the axial direction Z.

The regulating valve body 56 is provided on the tip side of the valve stem 55. The portion of the regulating valve body 56 located on the valve seat 48 side is cylindrical, with a tip 56A that can abut against the valve seat surface 48a of the valve seat 48. The regulating valve 43 having this configuration has the function of adjusting the flow rate of high-pressure steam supplied to the high-pressure steam turbine 31 in accordance with the load on the steam turbine 10 by controlling the distance between the tip 56A of the regulating valve body 56 and the valve seat 48 by moving the valve stem 55 along the axial direction Z using the actuator 46A.

The stop valve 45 is positioned inside the regulator valve 43. The stop valve 45 includes a valve stem 61, a sub-valve 62, a main valve 64, and a cap 65.

The valve rod 61 extends in the axial direction Z and has a tip portion 61A and a rod-shaped portion 61B. The tip portion 61A has a shape that can engage with the sub-valve 62 to secure the sub-valve 62. The rod-shaped portion 61B extends along the axial direction Z and has a constant outer diameter. The base end of the rod-shaped portion 61B is connected to the actuator 46B. In this way, the valve rod 61, which has the tip portion 61A and the valve rod portion 61B, is constructed as a single unit and can move back and forth in the axial direction Z.

As shown in FIG. 3 , the daughter valve 62 has a recess 62A and an abutment portion 62B. The recess 62A has a shape corresponding to the tip 61A of the valve stem 61, and by engaging with the tip 61A, the daughter valve 62 is fixed to the tip 61A of the valve stem 61. In this embodiment, the tip 61A of the valve stem 61 is configured as a threaded hole, and the recess 62A is configured as a screw hole corresponding to the tip 61A. The tip 61A of the valve stem 61 is inserted into the recess 62A of the daughter valve 62, thereby fixing the daughter valve 62 to the valve stem 61.

In this way, by fitting the recess 62A formed in the sub-valve 62 onto the tip 61A of the valve stem 61, the sub-valve 62 is fixed to the valve stem 61, preventing the sub-valve 62 from rattling or rotating relative to the valve stem 61. This reduces wear between the sub-valve 62 and the valve stem 61 (wear on the stop valve 45).

The abutment portion 62B forms the outer periphery of the child valve 62. The abutment portion 62B extends diagonally downward and is ring-shaped when viewed from the axial direction Z. When the child valve 62 is closed (the state shown in Figures 2 and 3), the abutment portion 62B abuts against the surface of the parent valve body 71 that constitutes the parent valve 64, located outside the through hole 71B. In this state, the inlet 71Ba of the through hole 71B is isolated from the steam flow path 52 through which high-pressure steam flows, and therefore high-pressure steam does not flow through the through hole 71B.

When adjusting the steam flow rate using the regulating valve 43 in the steam valve 14, the stop valve 45 is opened before the regulating valve 43 is opened. At this time, the stop valve 45 opens the child valve 62 before the parent valve 64, as shown in Figures 2 and 3, from a state in which both the child valve 62 and the parent valve 64 are closed (the parent valve 64 remains closed), as shown in Figure 4. At this time, the abutment portion 62B of the child valve 62 moves away from the valve seat surface 71a, creating a gap between the child valve 62 and the parent valve 64, allowing high-pressure steam to flow into the inlet 71Ba of the through-hole 71B. The high-pressure steam that has flowed into the inlet 71Ba of the through-hole 71B is then discharged from the outlet 71Bb of the through-hole 71B to the steam flow path 52. This reduces the pressure difference between the upstream and downstream sides of the parent valve 64, facilitating the subsequent opening of the parent valve 64.

The parent valve 64 is inserted into the valve stem 61 and is positioned between the child valve 62 and the rod-shaped portion 61B. The parent valve 64 has a parent valve body 71 and a bushing 72. The parent valve body 71 has a generally V-shape when viewed in vertical cross section. The parent valve body 71 has a through portion 71A, a valve seat surface 71a, an abutment surface 71b, an inner circumferential surface 71c, and multiple through holes 71B.

The through-portion 71A is formed to penetrate the center of the parent valve body 71 in the axial direction Z. The through-portion 71A is a cylindrical hole defined by an inner circumferential surface 71c. The valve stem portion 61 and bushing 72 are disposed in the through-portion 71A. The inner diameter of the through-portion 71A is large enough to accommodate the valve stem 61 and bushing 72.

The valve seat surface 71a is a curved surface located on the side of the sub-valve 62 (the tip side of the valve stem 61). The surface of the valve seat surface 71a located outside the inlets 71Ba of the multiple through-holes 71B is designed to be in contact with the abutment portion 62B of the sub-valve 62 when the sub-valve 62 is closed (see Figures 2 and 3).

The abutment surface 71b is a curved surface located on the base end side of the valve stem 61. When the parent valve 64 is fully closed, the outer periphery of the abutment surface 71b abuts against the valve seat surface 48a of the valve seat 48. In this state, high-pressure steam does not flow downstream of the valve seat 48. On the other hand, when the parent valve 64 is open, the abutment surface 71b and the valve seat surface 48a are separated, forming a gap between them, allowing high-pressure steam to flow downstream of the valve seat 48 in accordance with the opening of the regulating valve 43.

Multiple through-holes 71B are formed through the parent valve body 71, extending from the valve seat surface 71a to the abutment surface 71b. The multiple through-holes 71B are arranged circumferentially around the parent valve body 71. Each through-hole 71B has an inlet 71Ba and an outlet 71Bb. The inlet 71Ba is formed in the valve seat surface 71a, located inward of the abutment position between the abutment portion 62B and the valve seat surface 71a. As shown in Figure 4, when the child valve 62 opens before the parent valve 64 and a gap is formed between the child valve 62 and the parent valve 64, high-pressure steam flows into the through-hole 71B via the inlet 71Ba.

The outlet 71Bb is formed on the abutment surface 71b, which is located radially outward of the axis O1 from the position where the inlet 71Ba is formed. The outlet 71Bb is connected to the steam flow path 52, which is located downstream of the valve seat 48. In this embodiment, the through hole 71B is inclined in the direction from the inlet 71Ba toward the outlet 71Bb.

The bushing 72 has a cylindrical shape that surrounds the outer surface of the valve stem 61 inside the parent valve body 71. The inner surface 72a of the bushing 72 is in contact with the outer surface of the valve stem 61 while the bushing 72 is movable in the axial direction Z.

The cap 65 at least partially covers the daughter valve 62 from the upstream side of the steam flow path 52 and is fixed to the parent valve 64. In this embodiment, when viewed from the axial direction Z, the cap 65 extends beyond the daughter valve 62 and is fixed by bolt members 80 to the valve seat surface 71a of the parent valve 64, outside the position where the abutment portion 62B of the daughter valve 62 abuts. Multiple bolt members 80 are provided circumferentially, and each is inserted from a through hole 65a provided in the cap 65 to a stop hole 71a1 provided in the valve seat surface 71a of the parent valve 64.

In this embodiment, a biasing member 82 that is expandable and contractible along the axial direction Z is provided between the cap 65 and the subsidiary valve 62 in a state compressed from its natural length. The subsidiary valve 62 has a first receiving surface 84 that extends in a direction intersecting the axial direction Z, and the cap 65 has a second receiving surface 86 that faces the first receiving surface 84. The biasing member 82 is provided between the first receiving surface 84 provided on the subsidiary valve 62 and the second receiving surface 86 provided on the cap 65 in a state compressed from its natural length.

When the steam valve 14 is opened, as described above, the stop valve 45 opens the child valve 62 and then the parent valve 64, and the steam flow rate is then adjusted by adjusting the opening of the regulator valve 43. When the child valve 62 and parent valve 64 are open and the closed regulator valve 43 is opened, the steam inflow rate into the stop valve 45 increases, particularly if the opening of the regulator valve 43 is small. If the open parent valve 64 is left free at this time, it may vibrate due to the inflowing steam, resulting in wear.

In contrast, in this embodiment, the first and second receiving surfaces 84 and 86 receive a biasing force from the biasing member 82, which is compressed from its natural length. As a result, the cap 65 is fixed to the parent valve 64 by the bolt member 80 and is restricted from moving in a direction away from the child valve 62. As a result, the child valve 62 and parent valve 64 are stably supported by the valve stem fixed to the actuator, and are therefore not excited by the inflowing steam, effectively suppressing wear.

(Assembling method)
Next, a method for assembling the stop valve 45 having the above configuration will be described. Fig. 5 is a flowchart showing a method for assembling the stop valve 45 according to one embodiment, and Figs. 6A to 6F are explanatory views corresponding to the steps in Fig. 5.

First, as shown in Figure 6A, the master valve 64 is installed on the valve stem 61 (step S1). As described above, the master valve 64 has a generally ring shape when viewed from the axial direction Z, and the master valve 64 is installed by passing the valve stem 61 through the through-hole 71A provided at the center. In this embodiment, the bushing 72 is first inserted into the valve stem 61, and the master valve 64 is installed on its outer periphery.

Next, as shown in Figure 6B, the sub-valve 62 is fixed to the tip 61A of the valve stem 61 (step S2). As described above, the sub-valve 62 is fixed to the valve stem 61 by engaging the recess 62A with the tip 61A of the valve stem 61.

Next, as shown in Figure 6C, the biasing member 82 is placed against the first abutment surface 84 provided on the sub-valve 62 fixed to the valve stem 61 in step S2 (step S3). Because the sub-valve 62 fixed to the valve stem 61 is in an orientation with the first abutment surface 84 facing upward, in step S3 the biasing member 82 can be placed by inserting it from above along the axial direction Z.

Next, as shown in Figure 6D, the cap 65 is installed from above onto the biasing member 82 installed in step S3 (step S4). In step S4, the cap 65 is inserted from above along the axial direction Z onto the valve stem 61 in an orientation that allows the second bearing surface 86 to be exposed, thereby installing the cap 65 so that the second bearing surface 86 comes into contact with the biasing member 82. As a result, the biasing member 82 is installed so that it is interposed between the first bearing surface 84 and the second bearing surface 86.

6E, a positioning bolt 95 is inserted into a positioning hole (not shown) provided across the cap 65 and parent valve 64 installed in step S4 (step S5). At least one positioning hole is provided along the circumferential direction of the axis, and by inserting the positioning bolt 95 into this hole, the circumferential positions of the cap 65 and parent valve 64 are fixed relative to one another.
In addition, since Figure 6E shows a cross section corresponding to the through hole 65a of the cap 65 and the stop hole 71a1 of the parent valve 64, the positioning bolt 95 inserted into the positioning hole located in a different cross section is shown transparently.

Next, as shown in Figure 6F, a jig 97 is attached from above the cap 65 (step S6). The jig 97 has a jig body 97a for pressing the cap 65 and an engagement portion 97b for engaging the jig body 97a with the sub-valve 62. The engagement portion 97b is threaded, and by rotating the jig body 97a while engaging it with a hole 97c provided in the sub-valve 62, the position of the jig body 97a can be adjusted along the axial direction Z.

As shown in Figure 6F, in step S6, a washer 98 may be interposed between the cap 65 and the jig 97. The washer 98 prevents the jig 97 from coming into direct contact with the cap 65, thereby protecting the cap 65 when the jig 97 is rotated.

Next, as shown in Figure 6F, the jig 97 attached in step S6 is tightened so that the biasing member 82 is compressed from its natural length (step S7). As described above, by rotating the jig body 97a of the jig 97, the engaging portion 97b enters the engaging portion 97b provided on the sub-valve 62, pushing the cap 65 and compressing the biasing member 82 located between the sub-valve 62 and the cap 65.

Next, with the jig tightened in step S7, the cap 65 is fixed to the parent valve 64 using the bolt member 80 (step S8). This positions the biasing member 82 between the cap 65 and the child valve 62 in a state compressed from its natural length. The positioning bolt 95 inserted in step S5 is then removed (step S9). Even after removing the positioning bolt 95 in this way, the parent valve 64 and cap 65 remain fixed by the bolt member 80.

As a result, the stop valve 45 having the configuration shown in Figures 2 to 4 is assembled. By carrying out the above assembly method in this manner, the stop valve 45 having the aforementioned configuration can be efficiently assembled.

(Modification)
Next, a modification of the steam valve 14 having the above configuration will be described. Fig. 7 shows a modification of Fig. 4.

The cap 65 at least partially covers the daughter valve 62 from the upstream side of the steam flow path 52 and is fixed to the parent valve 64. In this modified example, when viewed from the axial direction Z, the cap 65 extends beyond the daughter valve 62 and is fixed by a bolt member 80 to the valve seat surface 71a of the parent valve 64, outside the position where the abutment portion 62B of the daughter valve 62 abuts. Multiple bolt members 80 are provided circumferentially, and each is inserted from a through hole 65a provided in the cap 65 to a stop hole 71a1 provided in the valve seat surface 71a of the parent valve 64.

A negative pressure chamber 90, to which negative pressure can be applied, is located between the sub-valve 62 and the cap 65. The negative pressure chamber 90 is configured as a gap formed between a protrusion 90a that protrudes toward the cap 65 in the axial direction Z of the sub-valve 62 and a recess 90b provided in the cap 65 to correspond to the protrusion 90a.

The negative pressure chamber 90 is connected to an external gland capacitor 94 via a negative pressure line 92 formed in the sub-valve 62 and valve stem 61. The sub-valve 62 and valve stem 61 have a hollow cavity at their center that forms the negative pressure line 92 along the axial direction Z, and negative pressure from the gland capacitor 94 is applied to the negative pressure chamber 90 via this negative pressure line 92.

The cap 65 also surrounds the negative pressure chamber 90 in the circumferential direction relative to the axial direction Z and has a convex seal portion 96 that protrudes toward the sub-valve 62. By providing the seal portion 96 to surround the negative pressure chamber 90 to which negative pressure is applied in this manner, it is possible to prevent steam from entering the negative pressure chamber 90 from the surrounding area and to effectively apply negative pressure to the negative pressure chamber 90.

In this modified example, the cap 65, to which the parent valve 64 is fixed by the bolt member 80, is attached to the child valve 62 fixed to the valve stem 61 so that movement away from the child valve 62 is restricted by the negative pressure applied to the negative pressure chamber 90. This takes a different approach from the embodiment described above, which uses a biasing member 82, and restricts the movement of the cap 65 relative to the child valve 62 fixed to the valve stem 61. This prevents the stop valve 45 from vibrating due to the steam that flows in when adjusting the opening of the regulator valve 43, effectively suppressing wear.

In addition, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate, without departing from the spirit of this disclosure.

The contents described in each of the above embodiments can be understood, for example, as follows:

(1) A steam valve (14) according to one aspect includes:
a steam flow path (52) through which steam flows, and a valve body (41) provided midway along the steam flow path and having a valve seat with an opening;
a valve stem (61) extending in an axial direction along which an axis extends and capable of advancing and retreating in the axial direction; a daughter valve (62) fixed to the tip end (61A) of the valve stem; and a parent valve (64) including a through-portion (71A) into which a portion of the tip end of the valve stem located closer to the base end of the valve stem than the tip end is inserted, the parent valve abutting against the valve seat to close the steam flow path and having a through-hole (71B) through which the steam flows when the daughter valve is opened; and a stop valve (45) at least partially covering the daughter valve from the upstream side of the steam flow path and having a cap (65) fixed to the parent valve.
Equipped with
The parent valve functions as a valve seat for the child valve, is not fixed to the valve stem, and is configured to be movable forward and backward in the axial direction,
The cap is attached to the child valve such that movement away from the child valve is restricted.

According to aspect (1) above, a cap that at least partially covers the child valve is attached to the child valve, which is fixed to the valve stem, so that movement away from the child valve is restricted while the cap is fixed to the parent valve. By fixing the parent valve to such a cap, when the child valve and parent valve are fully open, the parent valve is prevented from swinging relative to the valve stem to which the child valve is fixed, effectively preventing wear on the stop valve due to contact of the parent valve with the valve stem.

(2) In another aspect, in the above aspect (1),
Between the cap and the sub-valve, a biasing member (82) expandable and contractible along the axial direction is provided in a state compressed from its natural length.

According to the above aspect (2), a biasing member is provided between the cap and the sub-valve. The biasing member is positioned in a state compressed from its natural length, and a biasing force is applied to the cap and sub-valve by the biasing member, thereby restraining the parent valve to the valve stem via the cap and sub-valve.

(3) In another aspect, in the aspect (2),
The sub-valve has a first receiving surface (84) extending in a direction intersecting the axial direction,
The cap has a second abutment surface (86) that faces the first abutment surface via the biasing member.

According to the above aspect (3), by providing a biasing member that is compressed from its natural length between the first receiving surface provided on the child valve and the second receiving surface provided on the cap, it is possible to obtain a biasing force that restrains the parent valve to the valve stem via the cap and child valve.

(4) In another aspect, in the aspect (1),
A negative pressure chamber (90) capable of applying negative pressure is provided between the sub-valve and the cap.

According to the above aspect (4), by applying negative pressure to the negative pressure chamber provided between the sub-valve and the cap, the master valve, which is fixed to the cap, can be restrained to the valve stem via the sub-valve.

(5) In another aspect, in the aspect (4),
The negative pressure chamber is formed between a protrusion (90a) that protrudes toward the cap portion in the axial direction of the sub-valve and a recess (90b) that is provided in the cap portion to correspond to the protrusion.

According to the above aspect (5), the negative pressure chamber to which negative pressure is applied to restrain the cap against the sub-valve is formed as a gap between a convex portion provided on the sub-valve and a concave portion provided on the cap portion.

(6) In another aspect, in the aspect (5),
The cap has a sealing portion (96) that surrounds the negative pressure chamber along the circumferential direction of the axis and is formed in a convex shape so as to protrude toward the sub-valve.

According to aspect (6) above, by providing a convex seal portion surrounding the negative pressure chamber, it is possible to prevent steam from entering the negative pressure chamber from the surrounding area and effectively apply negative pressure to the negative pressure chamber to restrain the cap against the sub-valve.

(7) In another aspect, in any one of the above (4) to (6),
The negative pressure chamber is connected to a gland capacitor (94) via a negative pressure line formed in the sub-valve and the valve stem.

According to the above aspect (7), by applying negative pressure from the ground capacitor to the negative pressure chamber via the negative pressure line, it is possible to apply negative pressure to the negative pressure chamber to restrain the cap against the sub-valve with an efficient structure.

(8) In another aspect, in any one of the above (1) to (7),
The cap is fixed to the parent valve by a plurality of bolt members (80) extending in the axial direction and arranged along the circumferential direction of the axis.

According to the above aspect (8), the cap can be stably fixed to the parent valve by multiple bolt members arranged circumferentially around the axis.

(9) In another aspect, in any one of the above (1) to (8),
The valve has a regulator valve (43) that is arranged opposite the stop valve in the axial direction and can abut against the valve seat at a position outside the position of the valve seat where the parent valve abuts.

According to the above aspect (9), in a steam valve in which the regulator valve is arranged outside the stop valve, wear on the stop valve can be effectively suppressed when the child valve and parent valve are fully open.

(10) A power generation system according to one aspect includes:
A steam valve according to any one of the above (1) to (9),
a boiler (11) for generating steam;
a steam turbine driven by the steam;
a steam supply pipe (12) that connects the boiler and the steam turbine and supplies the steam to the steam turbine;
Equipped with
The steam valve is provided on the steam supply pipe.

According to the above aspect (10), by providing the power generation system with a steam valve that can suppress wear on the stop valve, it is possible to reduce the frequency of maintenance of the steam valve, thereby improving the operating efficiency of the power generation system.

1 Power generation system 10 Steam turbine 11 Boiler 12 First steam supply pipe 14 Steam valve 16 Second steam supply pipe 18 Reheater 25 Third steam supply pipe 26 Generator 31 High-pressure steam turbine 32 Medium-pressure steam turbine 33 Low-pressure steam turbine 35 Rotating shaft 41 Valve body 43 Regulating valve 45 Stop valve 46A, 46B Actuator 47 Flow path partition portion 47A First guide member 47B Second guide member 48 Valve seat 48a Valve seat surface 52 Steam flow path 52A Inlet portion 52B Outlet portion 55 Valve stem 56 Regulating valve body 56A Tip 61 Valve stem 61A Tip portion 61B Rod-shaped portion 62 Child valve 62A Recess 62B Abutment portion 64 Parent valve 65 Cap 65a Through hole 71 Parent valve body 71A Through portion 71B Through hole 71Ba Inlet 71Bb Outlet 71a1, stop hole 71a, valve seat surface 71b, contact surface 71c, inner circumferential surface 72, bushing 80, bolt member 82, biasing member 84, first receiving surface 86, second receiving surface 90, negative pressure chamber 90a, convex portion 90b, concave portion 92, negative pressure line 94, ground capacitor 95, positioning bolt 96, seal portion 97, jig 97a, jig body 97b, engagement portion 97c, hole portion 98, washer

Claims (9)

a valve body having a steam flow path through which steam flows and a valve seat provided midway along the steam flow path and having an opening;
a valve stem extending in an axial direction of an axis and capable of advancing and retreating in the axial direction; a daughter valve fixed to the tip of the valve stem at the tip; a parent valve including a through portion into which a portion of the tip of the valve stem located closer to the base end of the valve stem than the tip is inserted, the parent valve abutting against the valve seat to close the steam flow path and having a through hole through which the steam flows when the daughter valve is opened; and a stop valve at least partially covering the daughter valve from the upstream side of the steam flow path and having a cap fixed to the parent valve.
Equipped with
The parent valve functions as a valve seat for the child valve, is not fixed to the valve stem, and is configured to be movable forward and backward in the axial direction,
A steam valve, wherein a biasing member that is expandable and contractible along the axial direction is provided between the cap and the sub-valve in a state compressed from its natural length. The sub-valve has a first receiving surface extending in a direction intersecting the axial direction,
The steam valve according to claim 1 , wherein the cap has a second abutment surface that faces the first abutment surface via the biasing member. a valve body having a steam flow path through which steam flows and a valve seat provided midway along the steam flow path and having an opening;
a valve stem extending in an axial direction of an axis and capable of advancing and retreating in the axial direction; a daughter valve fixed to the tip of the valve stem at the tip; a parent valve including a through portion into which a portion of the tip of the valve stem located closer to the base end of the valve stem than the tip is inserted, the parent valve abutting against the valve seat to close the steam flow path and having a through hole through which the steam flows when the daughter valve is opened; and a stop valve at least partially covering the daughter valve from the upstream side of the steam flow path and having a cap fixed to the parent valve.
Equipped with
The parent valve functions as a valve seat for the child valve, is not fixed to the valve stem, and is configured to be movable forward and backward in the axial direction,
A steam valve having a negative pressure chamber capable of applying negative pressure between the sub-valve and the cap. 4. The steam valve according to claim 3, wherein the negative pressure chamber is formed between a convex portion of the sub-valve that protrudes toward the cap in the axial direction and a concave portion provided in the cap to correspond to the convex portion. The steam valve described in claim 4, wherein the cap surrounds the negative pressure chamber along the circumferential direction of the axis and has a convex sealing portion formed to protrude toward the sub-valve. A steam valve as described in any one of claims 3 to 5, wherein the negative pressure chamber is connected to a gland condenser via a negative pressure line formed in the sub-valve and the valve stem. A steam valve as described in any one of claims 1 to 6, wherein the cap is fixed to the parent valve by a plurality of bolt members extending in the axial direction and arranged circumferentially around the axis. A steam valve as described in any one of claims 1 to 7, further comprising a regulator valve disposed opposite the stop valve in the axial direction and capable of contacting the valve seat at a position outside the valve seat where the master valve contacts. A steam valve according to any one of claims 1 to 8;
a boiler for generating steam;
a steam turbine driven by the steam;
a steam supply pipe connecting the boiler and the steam turbine and supplying the steam to the steam turbine;
Equipped with
The power generation system, wherein the steam valve is provided on the steam supply pipe.