Steam valves and steam turbines

Abstract

To provide a steam valve, etc., capable of effectively preventing generation of vibration.SOLUTION: In a steam valve, a valve body comprises a first valve body part and a second valve body part. The first valve body part is positioned in a closing direction and includes a first valve body part outer peripheral surface enclosing a valve rod in an axial direction. The second valve body part is positioned in an opening direction and includes a second valve body part outer peripheral surface enclosing the valve rod in the axial direction. The first valve body outer peripheral surface is a curved surface formed so as to make a diameter larger from one end in the closing direction to the other end in the opening direction. The second valve body part outer peripheral surface is a surface of which the shape is different from that of the first valve body outer peripheral surface. The diameter at the other end side of the first valve body part outer peripheral surface in the opening direction and a diameter at one end side of the second valve body part outer peripheral surface in the closing direction are equal with a seat diameter of a valve seat with which the valve body is in contact with the valve seat when bringing the steam valve into a fully closed state.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present invention relate to a steam valve and a steam turbine. [Background technology]

[0002] In a steam turbine that constitutes a steam turbine power plant, a steam valve is installed at the inlet of the steam turbine. The steam valve is configured to adjust the flow rate of steam by changing the area of ​​a flow passage between a valve body and a valve seat in a valve chest of a valve casing.

[0003] In a steam valve, high-pressure steam flows, and vibrations occur due to drift and vortexes, which may cause damage such as cracks to the valve body or valve stem.

[0004] In particular, in steam valves such as a steam control valve installed upstream of a high-pressure turbine or an intercept valve installed upstream of an intermediate-pressure turbine, the steam flowing between the valve body and the valve seat may reach a transonic state, generating shock waves. As a result, the flow becomes turbulent due to the shock waves, and the above-mentioned problems may become apparent.

[0005] For this reason, various techniques have been proposed to prevent the occurrence of vibration in the steam valve device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 58-44909 [Patent Document 2] Patent No. 4185029 [Patent Document 3] Patent No. 5535770 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the past, it was not easy to sufficiently reduce the vibration of the steam valve device. For example, the flow may be disturbed at the valve seat seat diameter portion due to the effect of oxide scale attached to the surface of the valve disc located upstream of the valve seat seat diameter portion where the valve disc and the valve seat come into contact, and the surface roughness at the time of manufacture.

[0008] Therefore, an object of the present invention is to provide a steam valve and a steam turbine capable of effectively preventing the occurrence of vibration. [Means for solving the problem]

[0009] The steam valve of the embodiment includes a valve casing having a valve chamber formed therein, a valve seat installed in the valve chamber, and a valve body connected to a valve rod in the valve chamber and moving along the axial direction of the valve rod. 、 In the axial direction The valve stem Move in the closing direction death The valve disc and the valve seat are close to each other. By closing , in the axial direction The valve stem Move in the open direction death, The valve disc and the valve seat are separated. By opening The valve body has a first valve body portion and a second valve body portion. The first valve body portion is located in the closing direction and includes a first valve body portion outer peripheral surface that surrounds the axial direction of the valve rod. The second valve body portion is located in the opening direction and includes a second valve body portion outer peripheral surface that surrounds the axial direction of the valve rod. The first valve body portion outer peripheral surface is a curved surface that is formed so that the diameter increases from one end in the closing direction to the other end in the opening direction. The second valve body portion outer peripheral surface is a surface that has a different shape from the first valve body portion outer peripheral surface. What? , The bell mouth curved surface is formed so that the diameter increases from one end located on the closing direction side toward the opening direction. The diameter of the other end side in the opening direction of the outer circumferential surface of the first valve body portion and the diameter of one end side in the closing direction of the outer circumferential surface of the second valve body portion are all This is the same as the valve seat diameter where the valve disc comes into contact with the valve seat when the valve is in the closed state. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 is a diagram illustrating a schematic diagram of a steam turbine plant according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing an example of the configuration of the steam valve according to the first embodiment. [Diagram 3] FIG. 3 is an enlarged cross-sectional view showing a portion of a valve seat 314 and a valve body 321 in the steam valve according to the first embodiment. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing a portion of a valve seat 314 and a valve body 321 in a steam valve according to the second embodiment. [Diagram 5] FIG. 5 is an enlarged cross-sectional view showing a portion of a valve seat 314 and a valve body 321 in a steam valve according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First Embodiment [A] Configuration of steam turbine power plant FIG. 1 is a diagram illustrating a schematic diagram of a steam turbine plant according to a first embodiment.

[0012] 1, in the steam turbine power plant 100 of this embodiment, steam heated in a superheater 111 of a boiler 110 is introduced as a working fluid into a high-pressure turbine 141 via a main steam pipe P10 in which a main steam stop valve V10a and a steam control valve V10b are installed, and work is performed in the high-pressure turbine 141. Then, steam discharged from the high-pressure turbine 141 is supplied to a reheater 112 of the boiler 110 via a low-temperature reheat steam pipe P11 in which a check valve V11 is installed, and is heated again in the reheater 112.

[0013] The steam heated in the reheater 112 is introduced as a working fluid into the intermediate-pressure turbine 142 through a high-temperature reheat steam pipe P12 in which a reheat steam stop valve V12a and an intercept valve V12b are installed, and performs work in the intermediate-pressure turbine 142. Then, the steam discharged from the intermediate-pressure turbine 142 is introduced as a working fluid into the low-pressure turbine 143 through a crossover pipe P13, and performs work in the low-pressure turbine 143. Then, the steam discharged from the low-pressure turbine 143 is condensed in the condenser 150.

[0014] The water condensed in the condenser 150 (condensed water) is pressurized in the feed water pump 151. The water pressurized in the feed water pump 151 (feed water) is returned to the superheater 111 of the boiler 110.

[0015] In the steam turbine power plant 100, a turbine rotor is connected between a high-pressure turbine 141, an intermediate-pressure turbine 142, and a low-pressure turbine 143, and the turbine rotor rotates by the work of steam. The rotation of the turbine rotor drives a generator (not shown), generating electricity.

[0016] In addition, in the steam turbine power plant 100, a high-pressure turbine bypass pipe BP1 with a high-pressure turbine bypass valve BV1 and a low-pressure turbine bypass pipe BP2 with a low-pressure turbine bypass valve BV2 are provided so that the boiler 110 system can operate independently of the turbine operation. One end of the high-pressure turbine bypass pipe BP1 is connected to a portion of the main steam pipe P10 located upstream of the main steam stop valve V10a, and the other end is connected to a portion of the low-temperature reheat steam pipe P11 located downstream of the check valve V11. One end of the low-pressure turbine bypass pipe BP2 is connected to a portion of the high-temperature reheat steam pipe P12 located upstream of the reheat steam stop valve V12a, and the other end is connected to the condenser 150.

[0017] [B] Steam valve configuration Fig. 2 is a cross-sectional view showing an example of the configuration of a steam valve according to the first embodiment. In Fig. 2, the longitudinal direction is the vertical direction z, the horizontal direction is the first horizontal direction x, and the direction perpendicular to the paper surface is the second horizontal direction y perpendicular to the vertical direction z and the first horizontal direction x. Fig. 2 shows a vertical plane (xz plane) along the vertical direction z and the first horizontal direction x. Fig. 2 also shows a state in which the steam valve is at an arbitrary opening degree.

[0018] 2, in the steam valve of this embodiment, a valve seat 314 and a valve disc 321 installed at one end of a valve stem 320 are housed in a valve chamber 331 of a valve casing 312. When the steam valve is closed, the valve stem 320 moves together with the valve disc 321 in a closing direction downward in the vertical direction z, thereby bringing the valve disc 321 closer to the valve seat 314. When the steam valve is opened, the valve stem 320 moves together with the valve disc 321 in an opening direction upward in the vertical direction z, thereby moving the valve disc 321 away from the valve seat 314.

[0019] The steam valve is, for example, a steam control valve V10b installed at the inlet of the high-pressure turbine 141 (steam turbine). The intercept valve V12b installed at the inlet of the intermediate-pressure turbine 142 (steam turbine) may be configured in a similar manner (see FIG. 1).

[0020] Each component of the steam valve of this embodiment will be described in turn.

[0021] [B-1] Valve casing 312 In the steam valve, the valve casing 312 includes a first valve casing portion 312A and a second valve casing portion 312B, as shown in FIG.

[0022] Of the valve casing 312, the first valve casing portion 312A has a valve chamber 331 formed therein. Although not shown, the valve chamber 331 communicates with an inlet through which the steam F flows in, and also communicates with an outlet through which the steam F flows out. In addition, the first valve casing portion 312A has an opening 312K formed above the valve chamber 331 in the vertical direction z.

[0023] Of the valve casing 312, the second valve casing part 312B is located above the first valve casing part 312A in the vertical direction z and closes the opening 312K of the first valve casing part 312A. The second valve casing part 312B is fixed to the first valve casing part 312A by using a bolt 3120.

[0024] [B-2] Valve stem 320 In the steam valve, the valve rod 320 is, for example, a cylindrical rod-shaped body, and has a central axis AX along the vertical direction z. The valve rod 320 is inserted into the bush 319 so as to be movable in the vertical direction z, and penetrates the second valve casing portion 312B.

[0025] [B-3] Valve seat 314 In the steam valve, the valve seat 314 is installed in the valve chest 331. The valve seat 314 is, for example, a ring-shaped tubular body, and is axially symmetric with respect to the central axis AX of the valve stem 320, and is fixed to the first valve casing part 312A so as to be disposed coaxially with the valve stem 320 in the valve chest 331. The detailed configuration of the valve seat 314 will be described later.

[0026] [B-4] Valve body 321 In the steam valve, the valve disc 321 is accommodated in the valve chamber 331. The valve disc 321 is, for example, disk-shaped and axially symmetrical with respect to the central axis AX of the valve stem 320. The valve disc 321 is coaxially connected to one end (lower end) of the valve stem 320 inside the valve chamber 331, for example, by using a pin 321P. The valve disc 321 is also installed so as to be movable in the vertical direction z (axial direction) along the central axis AX of the valve stem 320. A detailed configuration of the valve disc 321 will be described later together with the valve seat 314.

[0027] [B-5] Other In addition to the above configuration, the steam valve has an upper end of valve stem 320 connected to oil cylinder 500 via lever 502. One end of lever 502 is supported by fulcrum 501, and valve stem 320 moves in vertical direction z by the operation of oil cylinder 500. As a result, in the steam valve, the distance between valve body 321 and valve seat 314 varies to adjust the opening degree, thereby controlling the flow of steam.

[0028] Specifically, in the oil cylinder 500, the valve rod 320 is moved in the vertical direction z in a closing direction to close the steam valve, thereby bringing the valve body 321 and the valve seat 314 closer together. As a result, the flow rate of the steam F passing between the valve body 321 and the valve seat 314 in the steam valve decreases.

[0029] In addition, in the oil cylinder 500, by moving the valve rod 320 in the vertical direction z in the opening direction to open the steam valve, the valve body 321 and the valve seat 314 are separated from each other. As a result, the flow rate of the steam F passing between the valve body 321 and the valve seat 314 in the steam valve increases.

[0030] [C] Detailed configuration of valve body 321 The detailed configuration of the valve body 321 will be described with reference to FIG. 3 in addition to FIG.

[0031] Fig. 3 is an enlarged cross-sectional view showing a portion of the valve seat 314 and the valve body 321 in the steam valve according to the first embodiment. Like Fig. 2, Fig. 3 shows a vertical plane (xz plane) along the vertical direction z and the first horizontal direction x.

[0032] In this embodiment, the valve body 321 includes a first valve body portion 321A and a second valve body portion 321B, as shown in Figures 2 and 3. In the valve body 321, the first valve body portion 321A is a portion located on the closing direction side (lower side) that closes the steam valve in the vertical direction z (axial direction). The second valve body portion 321B is a portion located on the opening direction side that opens the steam valve in the vertical direction z.

[0033] The first valve body portion 321A includes a first valve body portion outer peripheral surface S321A that surrounds the axial periphery of the valve rod 320. The first valve body portion outer peripheral surface S321A is a curved surface formed so that the diameter increases from one end (lower end) in the closing direction to the other end (upper end) in the opening direction. Specifically, the first valve body portion outer peripheral surface S321A is an arc shape with a radius of curvature R1 centered on a center of curvature O1 located on the line of the central axis AX.

[0034] The second valve body portion 321B includes a second valve body portion outer peripheral surface S321B that surrounds the axial periphery of the valve rod 320. The second valve body portion outer peripheral surface S321B has a shape different from that of the first valve body portion outer peripheral surface S321A, and is configured to include a surface along the vertical direction z (axial direction) from one end (lower end) to the other end (upper end) in the closing direction. Specifically, the second valve body portion outer peripheral surface S321B has a cylindrical shape that is symmetrical with respect to the central axis AX.

[0035] In this embodiment, the diameter D1 of the other end side (upper end side) in the opening direction of the first valve body portion outer peripheral surface S321A and the one end side (lower end side) in the closing direction of the second valve body portion outer peripheral surface S321B are the same as the valve seat seat diameter Do at which the valve body 321 contacts the valve seat 314 when the steam valve is in a fully closed state. In other words, the diameter D1 of the boundary position between the first valve body portion 321A and the second valve body portion 321B in the valve body 321 is the valve seat diameter Do and has a corner.

[0036] [D] About the recess T321 In this embodiment, a recess T321 is formed on a surface (lower surface in the drawing) of the first valve body portion 321A of the valve body 321 located on the opening direction side in the vertical direction z (axial direction). The recess T321 has an orthogonal surface (xy surface) perpendicular to the vertical direction z (axial direction) and an inclined surface extending from the periphery of the orthogonal surface toward the closing direction side, and has an edge E321 on the closing direction side of the inclined surface. The flow of steam F flowing along the curved surface of the first valve body portion 321A is cut by the edge E321 of the recess T321.

[0037] In FIG. 3, h is the depth (height) of the recess T321 of the valve body 321. θ1 is the inclination angle of the inclined surface of the recess T321 with respect to the vertical direction z (axial direction), and is, for example, 45°. Di is the diameter of the edge E321. Dth is the inner diameter of the valve seat 314 that is in contact with the radius of curvature R2 of the valve seat 314. O1 is the center of curvature of the first valve body portion outer peripheral surface S321A that is configured with the radius of curvature R1 in the first valve body portion 321A. O2 is the center of curvature of the curved surface that is configured with the radius of curvature R2 in the valve seat 314. B is the pivot line that connects the center of curvature O1 of the first valve body portion 321A and the center of curvature O2 of the valve seat 314.

[0038] 3, Ath is the minimum steam passage area, and it shows a schematic representation of the minimum value of the area of ​​the steam passage through which steam F passes between the valve seat 314 and the valve disc 321 when the steam valve is at an arbitrary opening degree. The area of ​​the steam passage through which steam F passes between the valve seat 314 and the valve disc 321 decreases along the flow of steam F until it becomes the minimum steam passage area Ath. Thereafter, the area of ​​the steam passage through which steam F passes between the valve seat 314 and the valve disc 321 increases from the minimum steam passage area Ath along the flow of steam F.

[0039] The minimum steam passage area Ath is a truncated cone with the pivot line B as a generating line, and can be calculated from the radius of the valve element 321, the radius of the valve seat 314, and the height of the truncated cone based on a general formula. According to a pressure distribution line (not shown) of an isentropic flow in an ideal state when a steam passage consisting of the valve seat 314 and the valve element 321 is replaced with a Laval tube, when the pressure ratio (P2 / P1) of the steam pressure P2 on the outlet side of the valve element 321 to the steam pressure P1 on the inlet side of the valve element 321 is lowered, the pressure becomes a critical pressure at the minimum steam passage area Ath on the pivot line B. In the steam passage through which the steam F passes between the valve seat 314 and the valve element 321, the flow of the steam F becomes a subcritical flow (subsonic flow) from the inlet side until it reaches the minimum steam passage area Ath. Furthermore, when the steam pressure P2 on the outlet side of the valve element 321 is lowered, the flow of the steam F becomes a supercritical flow (supersonic flow). Generally, when the flow of steam F becomes a supercritical flow, shock waves are generated perpendicular to the steam flow, causing an increase in pressure. The steam flow with increased pressure cannot maintain a stable state by itself, and so becomes unstable, generating noise and vibration.

[0040] Taking such fluid characteristics into consideration, in this embodiment, the edge E321 of the recess T321 is provided upstream of the position where the steam flowing along the valve body 321 separates, in the steam passage through which the steam F passes between the valve seat 314 and the valve body 321. This causes the steam F to become a subcritical flow (subsonic flow) that does not generate shock waves, and a stable flow is maintained, making it possible to further suppress the generation of noise and vibration.

[0041] Specifically, by satisfying the relationship shown in the following formula for each part, it is possible to more effectively suppress the generation of noise and vibration.

[0042] Di≧0.90Do···Formula (1) Dth ≧ 0.80Do Equation (2) 0.52Do≦R1≦0.6Do Equation (3) R2 ≧ 0.6Do Equation (4)

[0043] As explained above, the state of the steam passage, which is made up of the valve seat 314 and the valve element 321 through which the steam F passes, is very sensitive, and therefore it is clear that it has a large effect on the fluid characteristics.

[0044] Here, the shape of a conventional valve body 321 will be described with reference to FIG.

[0045] The first valve body portion 321A includes a first valve body portion outer peripheral surface S321A that surrounds the axial direction of the valve rod 320. The first valve body portion outer peripheral surface S321A is a curved surface formed so that the diameter increases from one end (lower end) in the closing direction to the other end (upper end) in the opening direction. Specifically, the first valve body portion outer peripheral surface S321A is an arc shape with a curvature radius R1 centered on a curvature center O1 located on a line of the central axis AX. The arc portion of the first valve body portion outer peripheral surface S321A passes through a valve seat diameter Do at which the valve body 321 contacts the valve seat 314 when the steam valve is in a fully closed state, and reaches a diameter (e.g., Dx) twice the curvature radius R1 toward the other end (upper end) in the opening direction (the shape shown by the dashed line in FIG. 3).

[0046] The second valve body portion 321B includes a second valve body portion outer peripheral surface S321B that surrounds the axial direction of the valve rod 320. The second valve body portion outer peripheral surface S321B has a different shape from the first valve body portion outer peripheral surface S321A, and is configured to include a surface along the vertical direction z (axial direction) from one end (lower end) to the other end (upper end) in the closing direction. Specifically, the second valve body portion outer peripheral surface S321B has a cylindrical shape that is symmetrical with respect to the central axis AX. The diameter of this second valve body portion outer peripheral surface S321B is twice the radius of curvature R1 (for example, Dx).

[0047] In other words, in the shape of the conventional valve body 321, the diameters (e.g., Dx) of the other end side (upper end side) of the first valve body portion outer surface S321A in the opening direction and the diameters (e.g., Dx) of one end side (lower end side) of the second valve body portion outer surface S321B in the closing direction are the same, but are larger than the valve seat diameter Do at which the valve body 321 contacts the valve seat 314 when the steam valve is in the fully closed state, and the diameter (e.g., Dx) of the boundary position between the first valve body portion 321A and the second valve body portion 321B in the valve body 321 is connected as a tangent with a curvature radius R1, so there are no corners.

[0048] However, as described above, in the conventional steam valve, the surface of the steam passage from the valve seat diameter Do to the outer peripheral surface S321B of the second valve body including the outer peripheral surface S321A of the first valve body on the upstream side, i.e., the inlet side, is prone to adhesion of oxide scale (slight convexity) due to long-term operation and erosion (slight concavity) due to foreign matter flying in during operation (the surface of the steam passage is prone to become finely rough). For this reason, in the conventional steam valve, even if the edge E321 is provided on the closing direction side of the valve body 321 located on the downstream side of the steam passage, the slight unevenness of the steam passage surface located on the inlet side initially disturbs the flow of the steam F at the inlet when it passes through. As a result, the conventional valve has a problem of triggering the generation of unnecessary shock waves during the passage of the steam F.

[0049] In this embodiment, the upstream side of the valve seat diameter Do at which the valve disc 321 contacts the valve seat 314 in the fully closed state is the valve chamber 331 which is a large space, so there is no steam passage, and therefore no adhesion or erosion of oxide scale physically occurs. Therefore, this embodiment can suppress turbulence in the steam flow, making it possible to effectively prevent the generation of noise and vibration. Furthermore, by providing the edge E321 on the closing direction side of the valve disc 321 located downstream of the steam passage, a stable flow of steam F is maintained without generating shock waves, making it possible to further suppress the generation of noise and vibration.

[0050] <Second embodiment> FIG. 4 is a cross-sectional view showing an enlarged part of the valve seat 314 and the valve body 321 in the steam valve according to the second embodiment. In FIG. 4, as in FIG. 3, a vertical plane (xz plane) along the vertical direction z and the first horizontal direction x is shown.

[0051] As shown in FIG. 4, the valve body 321 of the present embodiment is the same as in the case of the first embodiment (see FIG. 3). The diameter D1 of the other end side (upper end side) in the opening direction of the outer peripheral surface S321A of the first valve body portion and the diameter D1 of one end side (lower end side) in the closing direction of the outer peripheral surface S321B of the second valve body portion are the same as the valve seat sheet diameter Do. However, the shape of the outer peripheral surface S321B of the second valve body portion of the valve body 321 in the present embodiment is different from that in the case of the first embodiment. Except for this point and related points, the present embodiment is the same as in the case of the first embodiment. Therefore, regarding overlapping matters, the description will be omitted as appropriate.

[0052] In the present embodiment, as shown in FIG. 4, the outer peripheral surface S321B of the second valve body portion of the valve body 321 includes a tapered surface formed such that the diameter increases as it goes from one end (lower end) located on the closing direction side toward the opening direction. On the outer peripheral surface S321B of the second valve body portion, the tapered surface changes at a constant rate from the diameter D1 to the diameter D2 as it goes in the opening direction (D1 < D2). The diameter D2 is preferably not more than twice the radius of curvature R1 of the outer peripheral surface S321A of the first valve body portion (D2 ≦ 2·R1). Also, the inclination angle θ2 at which the tapered surface is inclined with respect to the central axis AX of the valve rod 320 is preferably 6° or less (θ2 < 6°) in order to smoothly guide the steam through the steam passage formed by the valve seat 314 and the valve body 321 through which the steam F passes.

[0053] And, on the outer peripheral surface S321B of the second valve body portion of the valve body 321, the portion located on the opening direction side of the tapered surface in the vertical direction z is composed of a surface along the vertical direction z (axial direction).

[0054] As described above, in the steam valve of the present embodiment, the valve disc 321 has the diameter D1 at the boundary between the first valve disc portion 321A and the second valve disc portion 321B, which is the same as the valve seat diameter Do, as in the first embodiment. Therefore, in the present embodiment, the upstream of the valve seat seat diameter Do at which the valve disc 321 contacts the valve seat 314 in the fully closed state is the valve chamber 331, which is a large space, and therefore no steam passage exists, and therefore no adhesion or erosion of oxide scale physically occurs. Therefore, this embodiment not only can suppress turbulence in the flow of steam, but also, since the second valve disc portion outer peripheral surface S321B of the valve disc 321 includes a tapered surface as described above, the steam F is smoothly guided to the steam passage consisting of the valve seat 314 and the valve disc 321 through which the steam F passes, the generation of noise and vibration can be effectively prevented. Furthermore, by providing an edge E321 on the closing side of the valve body 321 located downstream of the steam passage, a stable flow of steam F is maintained without generating shock waves, thereby further suppressing the generation of noise and vibration.

[0055] <Third embodiment> Fig. 5 is an enlarged cross-sectional view showing a portion of a valve seat 314 and a valve body 321 in a steam valve according to a third embodiment. Like Fig. 3, Fig. 5 shows a vertical plane (xz plane) along the vertical direction z and the first horizontal direction x.

[0056] As shown in Fig. 5, in the valve body 321 of this embodiment, as in the first embodiment (see Fig. 3), the diameter D1 of the other end side (upper end side) in the opening direction of the first valve body portion outer peripheral surface S321A and the one end side (lower end side) in the closing direction of the second valve body portion outer peripheral surface S321B are the same as the valve seat diameter Do. However, in the valve body 321 of this embodiment, the shape of the second valve body portion outer peripheral surface S321B is different from that of the first embodiment. Except for this point and related points, this embodiment is similar to the first embodiment. Therefore, explanations of overlapping matters will be omitted as appropriate.

[0057] In this embodiment, as shown in FIG. 5, the outer peripheral surface S321B of the second valve body portion of the valve body 321 includes a bellmouth curved surface formed such that the diameter increases as it goes from one end (lower end) located on the closing direction side toward the opening direction. On the outer peripheral surface S321B of the second valve body portion, the bellmouth curved surface changes so as to draw a bellmouth curve from diameter D1 to diameter D2 as it goes toward the opening direction (D1 < D2). The center of curvature O3 of the bellmouth curved surface of the outer peripheral surface S321B of the second valve body portion is at a position corresponding to the boundary position between the first valve body portion 321A and the second valve body portion 321B in the vertical direction z (the position of the valve seat sheet diameter Do). The outer peripheral surface including the bellmouth curved surface of the valve body 321 is axisymmetric with respect to the central axis AX of the valve rod 320. Here, it is preferable that the diameter D2 is not more than twice the radius of curvature R1 of the outer peripheral surface S321A of the first valve body portion (D2 ≤ 2·R1). Also, the radius of curvature R3 of the bellmouth curved surface is preferably not more than the radius of curvature R2 of the valve seat 314 (R3 ≤ R2) as long as it does not become a steam throttle portion with a minimum steam passage area Ath smaller than the minimum steam passage area Ath. Note that on the outer peripheral surface S321B of the second valve body portion, the bellmouth curved surface may have the same diameter D1 on the closing direction side and diameter D2 on the opening direction side (that is, D1 ≤ D2).

[0058] And, on the outer peripheral surface S321B of the second valve body portion of the valve body 321, the portion located on the opening direction side of the bellmouth curved surface in the vertical direction z is composed of a surface along the vertical direction z (axial direction).

[0059] As described above, in the steam valve of this embodiment, the valve body 321 is the same as in the case of the first embodiment, and the diameter D1 at the boundary position between the first valve body portion 321A and the second valve body portion 321B is the same as the valve seat sheet diameter Do. For this reason, in this embodiment, upstream of the valve seat sheet diameter Do where the valve body 321 contacts the valve seat 314 in the fully closed state, there is a valve chamber 331 with a large space and no steam passage, so physically, adhesion and erosion of oxidation scale do not occur. Therefore, in this embodiment, it is possible to suppress the disturbance of the steam flow. Also, in this embodiment, the outer peripheral surface S321B of the second valve body portion of the valve body 321 is as described above Since it includes a bellmouth curved surface,Since the steam F is smoothly guided to the steam passage consisting of the valve seat 314 and the valve element 321 through which the steam F passes, it is possible to effectively prevent the generation of noise and vibration. Furthermore, in this embodiment, since the edge E321 is provided on the closing direction side of the valve element 321 located on the downstream side of the steam passage, a stable flow of the steam F is maintained without generating shock waves, so that the generation of noise and vibration can be further suppressed.

[0060] <Other> Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0061] 100: steam turbine power plant, 110: boiler, 111: superheater, 112: reheater, 141: high pressure turbine, 142: intermediate pressure turbine, 143: low pressure turbine, 150: condenser, 151: feed water pump, 312: valve casing, 312A: first valve casing part, 312B: second valve casing part, 312K: opening, 314: valve seat, 319: bush, 320: valve stem, 321: valve body, 321A: first valve body part, 321B: second valve body part, 321P: pin, 331: valve chamber, 500: oil cylinder, 501: fulcrum, 502: lever, 3120: bolt, Ath: minimum steam passage area, AX: central axis, B: pivot line, BP1: high pressure turbine bypass pipe, BP2: Low pressure turbine bypass pipe, BV1: high pressure turbine bypass valve, BV2: low pressure turbine bypass valve, D1: diameter, D2: diameter, Do: valve seat diameter, E321: edge, F: steam, O1: center of curvature, O2: center of curvature, O3: center of curvature, P10: main steam pipe, P11: low temperature reheat steam pipe, P12: high temperature reheat steam pipe, P13: crossover pipe, R1: radius of curvature, R2: radius of curvature, R3: radius of curvature, S321A: outer periphery of valve body, S321B: outer periphery of valve body, T321: recess, V10a: main steam stop valve, V10b: steam control valve, V11: check valve, V12a: reheat steam stop valve, V12b: intercept valve, x: first horizontal direction, y: second horizontal direction, z: vertical direction

Claims

1. a valve casing having a valve chamber formed therein; A valve seat disposed in the valve chamber; a valve body connected to a valve stem in the valve chamber and moving along an axial direction of the valve stem; a valve stem moving in a closing direction in the axial direction to close the valve body and the valve seat, and a steam valve opening when the valve stem moves in an opening direction in the axial direction to separate the valve body and the valve seat, The valve body is A first valve body portion is located in the closing direction and includes a first valve body portion outer peripheral surface that surrounds the axial direction of the valve rod; a second valve body portion including a second valve body portion outer circumferential surface that is located in the opening direction and surrounds the valve rod in the axial direction; having The first valve body outer peripheral surface is a curved surface formed so that a diameter increases from one end in the closing direction to the other end in the opening direction, the second valve body outer peripheral surface is a surface having a different shape from the first valve body outer peripheral surface, and includes a bell-mouth curved surface formed so as to have a larger diameter from one end located on the closing direction side toward the opening direction, a diameter of the outer circumferential surface of the first valve body portion at the other end in the opening direction and a diameter of the outer circumferential surface of the second valve body portion at one end in the closing direction are equal to a valve seat diameter at which the valve body contacts the valve seat when the valve body is in a fully closed state; Steam valve.

2. The first valve body portion has a recess formed on a surface located on the opening direction side. The steam valve of claim 1 .

3. A steam turbine into which steam flows as a working medium through the steam valve according to claim 1 or 2.

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