JP5535768B2 - Steam valve - Google Patents

Description

  The present invention relates to a steam valve for adjusting the amount of steam supplied to, for example, a steam turbine of a thermal power plant or a nuclear power plant.

  Steam turbines such as thermal power plants and nuclear power plants move the valve stem with an actuator to change the flow path area between the valve seat and the valve body in order to adjust the amount of steam according to the load change. A number of steam valves for adjusting the amount of steam are provided.

  Some steam valves are configured to slide the valve body along the inner peripheral surface of a cylindrical valve body guide (muffler) for adjusting the amount of steam. Here, the valve body guide is a member having both a valve body guide function and a muffler function, and a plurality of openings and ribs are alternately arranged in the circumferential direction, and the ribs are connected to each other at the tip end side and provided on the valve seat. A ring portion that fits into the annular groove is provided. As a result, the valve body slides on the inner periphery of the valve body guide fixed to the valve seat by the ring portion, and the valve body moves away from the valve seat, so that the steam opens the opening portion by the differential pressure at the inlet and outlet of the steam valve. It passes through and flows into the flow path between the valve body and the valve seat.

In this type of steam valve, vibration of the steam valve flowing through the flow path between the valve body and the valve seat may cause vibration in each part of the steam valve, resulting in damage to the steam valve. In particular, the steam control valve disposed upstream of the high pressure chamber of the steam turbine and the intercept valve disposed upstream of the intermediate pressure chamber handle high-pressure and large-flow steam. The problem is how to suppress the vibration of each part.
Therefore, conventionally, attempts have been made to reduce the vibration of each part of the steam valve by devising the shape of the ring part of the valve element guide and the like. For example, Patent Document 1 discloses a steam valve in which a ring portion of a valve body guide is formed in a tapered shape to prevent turbulence of a steam flow flowing from an opening, and to suppress vibration of each part of the steam valve. ing.

Conventionally, a part of the steam flows through the gap between the ring part and the annular groove due to the pressure difference between the upstream and downstream of the ring part of the valve body guide (so-called gap flow). It was regarded as a problem as a cause of vibration.
Therefore, in Patent Document 2, fluid flow blocking means such as a seal ring or a wire mesh silencer is provided in the gap between the annular groove of the valve seat and the ring portion of the muffler (valve body guide), and the steam flow (gap in the gap) A steam valve is disclosed in which vibration of the valve body guide due to flow) is prevented.

Japanese Utility Model Publication No. 62-154203 Japanese Utility Model Publication No. 3-56802

  However, recent steam turbines have been developed to those capable of handling ultra-supercritical pressure, and with the steam valves described in Patent Documents 1 and 2, it may be difficult to sufficiently suppress vibration of the valve body guide. .

For this reason, the inventors of the present application tried to suppress the vibration of the valve body guide by increasing the cross-sectional area of the ring part that bundles the ribs of the valve body guide and strengthening the ring part. Even if the area was increased, the effect of suppressing the vibration of the valve body guide could not be sufficiently obtained.
Therefore, the inventors of the present application performed a simulation on the pressure distribution of the steam flow in the steam valve for the purpose of investigating the cause of the vibration of the valve body guide, and due to the interference between the steam flow and the ring portion, In addition to obtaining the knowledge that the steam flow is separated on the downstream side and the wake is generated, it has been recognized that the excitation of the ring part by the wake is a cause of the vibration of the valve body guide.

  This invention is made | formed in view of the above-mentioned situation, and it aims at providing the steam valve which can suppress the vibration of a valve body guide reliably.

The steam valve according to the present invention includes a seat portion and a valve seat having an annular groove formed on the upstream side of the seat portion, a plurality of openings and ribs arranged alternately in the circumferential direction, A cylindrical valve body guide having a ring portion that is connected to each other on the side and that fits into the annular groove of the valve seat, and is disposed inside the valve body guide, with respect to the seat portion of the valve seat A steam valve that is capable of adjusting the amount of steam flowing between the valve seats by being separated from the valve seat, wherein the annular groove has an inner peripheral edge formed on the upstream side of the seat portion, The ring part of the valve element guide is formed between the outer peripheral edge located on the outer peripheral side and positioned in the valve opening direction of the valve body, and the ring part of the valve body guide is directed to the seat part through the opening part. so as not to interfere with the main flow, of the valve body than the inner peripheral edge of the annular groove Characterized in that it is formed fully seated in the valve direction.

  Here, the ring part "does not interfere with the main steam flow" means that the steam flow is not separated by the ring part on the downstream side of the ring part. The determination can be made based on the simulation result of the pressure distribution of the steam flow in the steam valve.

In the steam valve, the ring portion of the valve body guide is formed so as to be completely contained in the valve closing direction of the valve body rather than the inner peripheral edge of the annular groove so as not to interfere with the main steam flow. The main stream of steam is not separated on the downstream side of the valve, and the vibration of the valve body guide due to the wake can be prevented.
In addition, since the ring part of the valve body guide does not interfere with the main steam flow, there is almost no pressure difference between the upstream and downstream of the ring part, and the steam flow (gap flow) flows through the gap between the ring part and the annular groove. Therefore, the vibration of the valve body guide due to the gap flow can be prevented without providing a member for preventing the gap flow such as a seal ring or a wire mesh silencer.

According to the present invention, the annular groove is formed between an inner peripheral edge formed on the upstream side of the seat portion and an outer peripheral edge located on the outer peripheral side of the inner peripheral edge and in the valve opening direction of the valve body. In order to prevent the ring part of the valve body guide from interfering with the main steam flow, it is formed so as to be completely contained in the valve closing direction of the valve body rather than the inner peripheral edge of the annular groove . Steam mainstream separation does not occur, and vibration of the valve body guide due to wake can be prevented.
In addition, since the ring part of the valve body guide does not interfere with the main steam flow, there is almost no pressure difference between the upstream and downstream of the ring part, and the steam flow (gap flow) flows through the gap between the ring part and the annular groove. Therefore, the vibration of the valve body guide due to the gap flow can be prevented without providing a member for preventing the gap flow such as a seal ring or a wire mesh silencer.

It is sectional drawing which shows the structural example of the steam valve which concerns on this embodiment. It is sectional drawing along the II line in FIG. It is an expanded sectional view around the ring part of a valve element guide.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

  First, the overall configuration of the steam valve according to the present invention will be described. FIG. 1 is a cross-sectional view showing a configuration example of a steam valve according to the present embodiment, and FIG. 2 is a cross-sectional view taken along line II in FIG.

  As shown in FIG. 1, the steam valve 1 includes a valve body casing 4 having a valve seat 2, a cylindrical valve body guide (muffler) 6, a valve body 8 disposed inside the valve body guide 6, A valve rod 10 connected to the valve body 8 and a bonnet 12 provided on the valve body casing 4 are configured.

A bonnet 12 is fixed to the upper portion of the valve body casing 4 by bolts 3, and an opening of the valve body casing 4 is closed by the bonnet 12. That is, in a state where the cylindrical cylindrical portion 12A of the bonnet 12 is inserted into the valve body casing 4, the cover plate 12B of the bonnet 12 and the valve body casing 4 are fastened by the bolt 3, and the internal space of the steam valve 1 is Forming.
Further, the valve body casing 4 is formed with a steam inlet 14 and a steam outlet 16, and as shown by arrows in the figure, the steam flowing into the internal space of the steam valve 1 from the steam inlet 14 flows out of the steam outlet 16. The steam valve 1 is supplied to a steam turbine or the like (not shown) disposed in the subsequent stage.

  The valve seat 2 of the valve body casing 4 is provided as a part of the inner surface of the valve body casing 4 between the steam inlet 14 and the steam outlet 16. An annular groove 20 is formed on the upstream side of the seat portion 18 of the valve seat 2.

The valve body guide (muffler) 6 is a cylindrical member provided for guiding and silencing the valve body 8, and as shown in FIG. 2, a plurality of openings 6A through which steam passes and a plurality of ribs 6B. Are alternately arranged in the circumferential direction. As shown in FIGS. 1 and 2, the valve body guide 6 is provided with a ring portion 6C, and a plurality of ribs 6B are connected to each other by the ring portion 6C.
On the lower end side of the valve element guide 6, the ring portion 6 </ b> C is fitted in the annular groove 20 and is fixed to the valve seat 2. On the other hand, the upper end side of the valve element guide 6 is fixed to the cylindrical portion 12 </ b> A of the bonnet 12 by a pin 22.

In addition, in order to separate the annular groove 20 of the valve seat 2 from the seat portion 18 as much as possible, the diameter of the valve body guide 6 increases as the portion formed by the rib 6B approaches the lower end side, as shown in FIGS. It is preferable that the ring portion 6C is provided only on the outer peripheral side of the portion constituted by the rib 6B.
As will be described later, when the ring portion 6C is completely accommodated in the annular groove 20 to prevent the main steam flow and the ring portion 6C from interfering with each other, the annular groove 20 is made larger (wider) than that of the conventional ring portion 6C. It is necessary to ensure strength. However, if such a wide annular groove 20 exists in the vicinity of the seat portion 18, the valve seat 2 may be deformed around the seat portion 18 when the valve is opened and closed. In this regard, if the valve body guide 6 has the above shape, the annular groove 20 of the valve seat 2 exists at a position relatively distant from the seat portion 18, so that the valve seat 2 is deformed around the seat portion 18 when the valve is opened and closed. There is no end.

The valve body 8 shown in FIG. 1 is provided inside the valve body guide 6, and moves along the cylindrical portion 12 </ b> A of the bonnet 12 and the valve body guide 6 as the valve rod 10 connected to the valve body 8 moves up and down. To move up and down. Here, since the pressure seal ring 24 is provided in the outer peripheral side wall of the valve body 8, the vertical sliding of the valve body 8 with respect to the cylindrical part 12A of the bonnet 12 is performed smoothly. As shown in FIGS. 1 and 2, a balance hole 8A is provided at the top of the valve body 8 so that the inner space 26 surrounded by the valve body 8 and the cylindrical portion 12A of the bonnet 12 can be separated from the outside. The valve body 8 can be moved up and down with a small driving force while maintaining a pressure balance.
When the valve body 8 is in contact with the seat portion 18 of the valve seat 2, the area of the flow path between the valve body 8 and the valve seat 2 is increased and decreased, and the amount of steam flowing through the flow path is adjusted. .

  The valve rod 10 has one end connected to the valve body 8 and the other end connected to an actuator (not shown). Thereby, the driving force of the actuator is transmitted to the valve body 8. The valve stem 10 is guided by a sleeve 28 that penetrates the cover plate 12B of the bonnet 12.

Next, a specific configuration of the valve element guide 6 of the steam valve 1 according to the present embodiment will be described. FIG. 3 is an enlarged cross-sectional view of the periphery of the ring portion 6 </ b> C of the valve element guide 6. As shown in the figure, the ring portion 6C of the valve element guide 6 is formed so as not to interfere with the main steam flow (in the direction of the arrow in the figure) toward the seat portion 18 through the opening 6A.
As described above, in the steam valve 1 of the present embodiment, the steam main flow does not interfere with the ring portion 6C, and therefore, the steam main flow is not separated on the downstream side of the ring portion 6C. Can be prevented. Further, since the steam main flow does not interfere with the ring portion 6C, there is almost no pressure difference between the upstream and downstream of the ring portion 6C, and the steam flow (gap flow) flows through the gap between the ring portion 6C and the annular groove 20. The vibration of the valve element guide 6 due to the gap flow can be prevented without providing a member for preventing the gap flow such as a seal ring or a wire mesh silencer.

As shown in FIG. 3, it is preferable that the ring portion 6 </ b> C of the valve body guide 6 is completely contained in the annular groove 20 of the valve seat 2.
Thereby, the vibration of the valve body guide 6 caused by the wake on the downstream side of the ring portion 6C and the vibration of the valve body guide 6 caused by the gap flow between the ring portion 6C and the annular groove 20 are more reliably prevented. can do.

  Although an example of the present invention has been described in detail above, the present invention is not limited to this, and it goes without saying that various improvements and modifications may be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the steam valve 1 having the entire configuration illustrated in FIG. 1 has been described. However, the entire configuration of the steam valve 1 is formed so that the ring portion 6C of the valve element guide 6 does not interfere with the main steam flow. As long as they are not particularly limited, various configurations can be adopted.

DESCRIPTION OF SYMBOLS 1 Steam valve 2 Valve seat 4 Valve body casing 6 Valve body guide 6A Opening part 6B Rib 6C Ring part 8 Valve body 8A Balance hole 10 Valve rod 12 Bonnet 12A Cylindrical part 12B Cover plate 14 Steam inlet 16 Steam outlet 18 Seat part 20 Ring Groove 22 Pin 24 Pressure seal ring 26 Internal space 28 Sleeve

Claims (1)

A valve seat having a seat portion and an annular groove formed on the upstream side of the seat portion;
A cylindrical valve body guide having a ring portion in which a plurality of openings and ribs are alternately arranged in the circumferential direction, and the ribs are connected to each other on the tip side and fitted into the annular groove of the valve seat;
A steam valve provided on the inside of the valve body guide and having a valve body capable of adjusting an amount of steam flowing between the valve seat by being separated from and contacting the seat portion of the valve seat;
The annular groove is formed between an inner peripheral edge formed on the upstream side of the seat portion and an outer peripheral edge located on the outer peripheral side of the inner peripheral edge and in the valve opening direction of the valve body,
The ring portion of the valve body guide is completely contained in the valve closing direction of the valve body rather than the inner peripheral edge of the annular groove so as not to interfere with the main steam flow toward the seat portion through the opening. A steam valve characterized by being formed.

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