JP2019100243A - Steam valve and steam turbine - Google Patents

Abstract

To provide a steam valve capable of suppressing a leakage amount of steam and easily securing normal operation of a valve rod.SOLUTION: A steam valve 10 comprises a valve casing 1, a stop valve 2 having a valve rod 21 and a valve body, and a guide cylinder 4. The guide cylinder 4 takes on a cylindrical shape of inserting the valve rod 21 therein and guiding the valve rod 21 toward an axis direction. The valve rod 21 has a shoulder part 26, and a main outer peripheral surface 27a connected to the shoulder part 26. An inner peripheral surface of the guide cylinder 4 has a large-diameter inner peripheral surface 45 corresponding to a movement range R1 of the shoulder part 26, and a small-diameter inner peripheral surface 47 opposite to the main outer peripheral surface 27a. The large-diameter inner peripheral surface 45 has a clearance with respect to the valve rod 21 larger than that of the small-diameter inner peripheral surface 47.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a steam valve and a steam turbine.

  Steam turbines, such as a thermal power plant and a nuclear power plant, are equipped with a steam valve (see, for example, Patent Document 1). The steam valve regulates the amount of steam in response to a change in load, or shuts off the steam supply at the time of abnormality. The pressure loss at the steam valve affects the efficiency of the steam turbine. Therefore, it is desirable to reduce pressure loss. As a steam valve capable of reducing pressure loss, there is a steam valve having the following structure.

  The steam valve includes, for example, a valve casing, a stop valve, an adjustment valve, and a guide portion. The valve casing has a steam flow path. The stop valve comprises a valve stem and a valve plug provided at the end of the valve stem. The guide portion guides the valve stem in the axial direction. The guide projects into the steam flow path of the valve casing.

  For example, when the steam turbine starts up, the steam flow increases the temperature of the steam valve. Therefore, radial deformation may occur in the guide portion. When the guide portion is deformed, contact between the valve stem and the guide portion is likely to occur. When the valve stem and the guide portion come into contact, when the stop valve is rapidly closed due to an emergency stop of the steam turbine, seizing occurs between the valve stem and the guide portion, and the stop valve operates normally. It may be difficult. For example, if seizing between the valve stem and the guide portion occurs at an intermediate position of the stroke of the valve stem, it becomes difficult to close the stop valve, and the steam turbine tends to overspeed. If the inner diameter of the guide portion is increased, it is easy to ensure the normal operation of the valve rod, but in such a case, the amount of steam leakage increases, so the performance of the steam valve decreases.

Unexamined-Japanese-Patent No. 2006-105130

  The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a steam valve and a steam turbine which can suppress the amount of steam leakage and easily ensure normal operation of a valve rod.

In order to solve the above-mentioned subject, the present invention adopts the following means.
A steam valve according to one aspect of the present invention includes a valve casing having an introduction flow passage into which steam is introduced and a discharge flow passage from which the steam is discharged, and is externally inserted into the valve casing from the outside and axially movable. A valve stem, a stop valve provided at one axial end of the valve stem and having a valve body capable of abutting on a valve seat in the valve casing, and fixed to the valve casing, A cylindrical guide cylinder for inserting the valve stem inside and guiding the valve stem in the axial direction, the valve stem having a shoulder portion whose diameter increases toward the other axial side of the valve stem And a main outer peripheral surface connected to the other axial side of the shoulder, the inner peripheral surface of the guide cylinder having a large diameter inner peripheral surface corresponding to the movement range of the shoulder, and A small diameter inner circumferential surface located on the other side of the large diameter inner circumferential surface in the axial direction and facing the main outer circumferential surface; Diameter inner peripheral surface gap is large between the valve stem than the small diameter inner peripheral surface.

According to this configuration, since the inner circumferential surface of the guide cylinder has the small diameter inner circumferential surface, the gap with the valve rod can be made smaller in the small diameter inner circumferential surface. Therefore, the amount of steam leaking to the outside of the valve casing can be suppressed through the gap between the guide cylinder and the valve rod. Since the inner peripheral surface of the guide cylinder has a large diameter inner peripheral surface corresponding to the movement range of the shoulder portion of the valve rod, a sufficient gap can be secured between the guide cylinder and the valve rod. Therefore, even when the guide cylinder is deformed in the radial direction, it is easy to ensure the normal operation of the valve rod.
According to this configuration, since the normal operation of the valve rod can be secured, seizing of the guide cylinder and the valve rod can be prevented at the time of emergency stop of the steam turbine or the like, and rapid closing of the stop valve can be reliably performed.

  The guide cylinder includes a cylindrical guide cylinder main body and an adjustment member provided on the inner peripheral surface of the guide cylinder main body, and the small diameter inner peripheral surface is preferably the inner peripheral surface of the adjustment member .

  According to this configuration, installation and replacement of the adjustment member on the guide cylinder main body is easy, so adjustment of the gap between the small diameter inner peripheral surface and the valve rod is easy.

  The valve rod further includes an abutment step which abuts the inner surface of the guide cylinder when the valve body is separated from the valve seat, and the abutment step is in one of the axial directions more than the shoulder portion. Preferably, it is formed on the side.

  According to this configuration, when the abutment step abuts on the inner surface of the guide cylinder, the shoulder portion does not easily abut on the guide cylinder.

  A steam valve according to one aspect of the present invention includes a valve casing having an introduction flow passage into which steam is introduced and a discharge flow passage from which the steam is discharged, and is externally inserted into the valve casing from the outside and axially movable. A valve stem, a stop valve provided at one axial end of the valve stem and having a valve body capable of abutting on a valve seat in the valve casing, and fixed to the valve casing, And a cylindrical guide cylinder which accommodates the valve stem and guides the valve stem in the axial direction, and the valve stem has a shoulder that expands in diameter toward the other axial side of the valve stem. Portion and a main outer peripheral surface connected to the other axial side of the shoulder, the inner peripheral surface of the guide cylinder corresponding to the movement range of the shoulder being biased with respect to the valve rod I have a heart.

  According to this configuration, even when the guide cylinder is deformed in the radial direction, it is easy to ensure normal operation of the valve rod.

  In the inner peripheral surface of the guide cylinder corresponding to the movement range of the shoulder when viewed in parallel with the axial direction of the valve rod, a gap with the valve rod at a portion closest to the discharge passage is the discharge Preferably, it is larger than the gap with the valve stem at a portion farthest from the flow path.

  According to this configuration, when the guide cylinder is deformed to the side opposite to the discharge flow path side, it is easy to ensure the normal operation of the valve rod.

  The guide cylinder includes a cylindrical guide cylinder main body and an adjustment member provided on the inner peripheral surface of the guide cylinder main body, and the adjustment member is provided at a position including a portion closest to the discharge flow channel Is preferred.

  According to this configuration, it is possible to suppress the amount of steam leaking to the outside of the valve casing through the gap between the guide cylinder and the valve rod.

  The valve rod further includes an abutment step which abuts the inner surface of the guide cylinder when the valve body is separated from the valve seat, and the abutment step is in one of the axial directions more than the shoulder portion. Preferably, it is formed on the side.

  According to this configuration, when the abutment step abuts on the inner surface of the guide cylinder, the shoulder portion does not easily abut on the guide cylinder.

  A steam turbine according to an aspect of the present invention includes any of the above-described steam valves.

  This steam turbine is excellent in reliability because it has a steam valve that suppresses the amount of steam leakage and easily ensures the normal operation of the valve stem.

  According to one aspect of the present invention, normal operation of the valve rod can be secured. According to one aspect of the present invention, the leak amount of steam can be suppressed.

It is a schematic diagram of the steam valve concerning a 1st embodiment. It is a partial cross section figure of the steam valve of FIG. It is a partial cross section explaining the operation | movement of the steam valve of FIG. (A) shows a state in which the valve stem is at the lowest position. (B) shows the state where the valve stem is at the highest position. It is a partial cross section explaining the operation | movement of the guide cylinder of the steam valve of a comparison form. (A) shows an undeformed guide cylinder and a valve stem. (B) shows the guide cylinder and valve rod which deform | transformed to radial direction. It is a flowchart which shows the example of the design method of the clearance gap between the guide cylinder in the steam valve of FIG. 1, and a valve stem. It is a figure which shows the example of the design method of the adjustment member in the steam valve of FIG. (A) shows an undeformed guide cylinder and a valve stem. (B) shows the guide cylinder and valve rod which deform | transformed to radial direction. It is a schematic diagram of the steam valve concerning a 2nd embodiment. It is a partial cross section figure of the steam valve concerning a 2nd embodiment. It is AA sectional drawing of FIG. It is a partial cross section explaining the operation | movement of the steam valve of FIG. It is a partial cross section figure of the modification of the steam valve concerning a 2nd embodiment. It is BB sectional drawing of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First Embodiment
FIG. 1 is a schematic view of a steam valve 10 (main steam valve) according to a first embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the steam valve 10. In the following description, the vertical direction is determined in accordance with FIG. 1 and FIG. Viewing from a direction parallel to the vertical direction is referred to as plan view. The upward direction is also called the height direction.

As shown in FIG. 1, the steam valve 10 includes a valve casing 1, a stop valve 2, an adjustment valve 3, a guide cylinder 4, a lid member 5, a stop valve drive mechanism 6, and an adjustment valve drive mechanism 7. Is equipped.
The valve casing 1 includes a main body portion 11, an introduction conduit 12, and a discharge conduit 13.
Inside the main body portion 11, a valve chamber 11a and a main flow passage 11b communicating with the valve chamber 11a are formed. A first valve seat 14 and a second valve seat 15 are formed at the outlet of the valve chamber 11a. An attachment hole 17 for attaching the guide cylinder 4 is formed in the main body portion 11 at a location facing the main flow passage 11b. The code | symbol A11 is a central axis of the main-body part 11. As shown in FIG. The central axis A11 is along the vertical direction.

  The introduction conduit 12 protrudes from the main body portion 11. An introduction passage 12 a into which the steam S is introduced is formed in the introduction pipe 12. The introduction flow passage 12a is a linear flow passage leading to the valve chamber 11a. The inlet pipe 12 has an inlet 12 b into which the steam S is introduced. Reference numeral 12a1 is a central axis of the introduction channel 12a. The central axis 12a1 is, for example, perpendicular to the central axis A11 of the main body 11.

  The discharge conduit 13 protrudes from the main body 11. In the inside of the discharge pipe line 13, a discharge flow path 13a to which the steam S is discharged is formed. The discharge flow channel 13a is a linear flow channel that leads to the main flow channel 11b. The discharge pipeline 13 has a discharge port 13 b from which the steam S is discharged. The code | symbol 13a1 is a central axis line of the discharge flow path 13a. The central axis 13a1 is, for example, perpendicular to the central axis A11 of the main body 11.

  The introduction conduit 12 and the discharge conduit 13 may be in rotational symmetry with respect to the central axis A11 of the main body 11 in a plan view. The relative position between the introduction conduit 12 and the discharge conduit 13 in plan view is not particularly limited. The introduction conduit 12 and the discharge conduit 13 may be formed in directions in which the introduction channels 12a and 13an central axes 12a1 and 13a1 cross each other (for example, directions orthogonal to each other) in plan view.

  The stop valve 2 includes a valve rod 21 and a valve body 22. The valve rod 21 is inserted into the main flow passage 11 b from the outside of the valve casing 1. The valve rod 21 extends in the vertical direction. The central axis A21 of the valve rod 21 extends in the vertical direction. The direction of the central axis A21 of the valve rod 21 is also referred to as "axial direction". The valve rod 21 is movable in the vertical direction (axial direction).

As shown in FIG. 2, the valve rod 21 includes, from top to bottom, a small diameter portion 23, a tapered portion 24 (a contact step), an intermediate portion 25, a shoulder 26, and a main portion 27. .
The outer diameter of the small diameter portion 23 is constant in the axial direction. The tapered portion 24 is an enlarged diameter portion formed by the difference in outer diameter between the small diameter portion 23 and the middle portion 25. The tapered portion 24 expands in diameter downward from the lower end of the small diameter portion 23 to the upper end of the middle portion 25. The tapered portion 24 is formed on the upper side of the shoulder portion 26. The tapered portion 24 abuts on the tapered surface 44 of the guide cylinder 4 when the valve body 22 is separated from the first valve seat 14 (see FIG. 1).
The outer diameter of the intermediate portion 25 is larger than the outer diameter of the small diameter portion 23 and is constant in the axial direction.

The shoulders 26 expand in diameter downward from the lower end of the middle portion 25 to the upper end of the main portion 27. The shoulder portion may be a step portion whose diameter increases discontinuously from the lower end of the middle portion to the upper end of the main portion. Since the shoulder portion 26 is formed at a distance from the tapered portion 24 (contact stepped portion), the valve rod 21 has a shape having two stages of enlarged diameter portions (the tapered portion 24 and the shoulder portion 26). .
The outer diameter of the main portion 27 is larger than the outer diameter of the middle portion 25 and is constant in the axial direction. The outer peripheral surface of the main portion 27 is referred to as a main outer peripheral surface 27 a.

  As shown in FIG. 1, the valve body 22 is provided at an upper end (an end on one side in the axial direction) of the valve rod 21. The valve body 22 is provided in the valve chamber 11a. The valve body 22 can abut on the first valve seat 14. The valve body 22 can close the opening 16 facing the main flow passage 11 b by abutting on the first valve seat 14.

The control valve 3 includes a valve rod 31 and a valve element 32.
The valve rod 31 is inserted into the valve chamber 11 a from the outside through the insertion hole 5 a of the lid member 5. The valve rod 31 extends in the vertical direction. The valve rod 31 is movable in the vertical direction (axial direction).
The valve body 32 is provided at the lower end of the valve rod 31. The valve body 32 includes a top plate portion 33 and a cylindrical portion 34 depending from the periphery of the top plate portion 33. The valve body 32 is provided in the valve chamber 11a. The lower end portion of the cylindrical portion 34 can abut on the second valve seat 15. The valve body 32 can close the outlet opening of the valve chamber 11 a by abutting on the second valve seat 15.

  The lid member 5 includes a main body 51 and a guide 52. The main body 51 closes the upper opening of the valve chamber 11a. The guide 52 protrudes downward from the lower surface of the main body 51. The guide portion 52 is formed in a tubular shape surrounding the valve body 32. The guide portion 52 guides the vertical movement of the valve body 32.

  The stop valve drive mechanism 6 includes a piston 61, a cylinder 62 and a spring 63. The piston 61 is provided at the lower end of the valve rod 21 of the stop valve 2. The cylinder 62 accommodates the piston 61 and the spring 63. The spring 63 biases the piston 61 downward.

  The adjustment valve drive mechanism 7 includes an operation lever 71, a cylinder mechanism 72, and a spring 73. The operating lever 71 is connected to the valve rod 31 of the control valve 3. The cylinder mechanism 72 vertically moves the valve rod 31 by rotating the operation lever 71. The spring 73 biases the valve rod 31 downward.

  The guide cylinder 4 (guide portion) is formed in a cylindrical shape (for example, a cylindrical shape having a circular cross section orthogonal to the central axis A4) having the insertion hole 4a. The guide cylinder 4 is fixed to the main body 11 in a state where the lower portion is inserted into the mounting hole 17. The guide cylinder 4 protrudes from the inner surface of the main flow passage 11b into the main flow passage 11b.

  As shown in FIG. 2, the guide cylinder 4 is provided with the central axis A4 directed in the vertical direction. The valve rod 21 is inserted through the insertion hole 4 a of the guide cylinder 4. The guide cylinder 4 guides the valve rod 21 in the direction (axial direction) of the central axis A4. The central axis A4 of the guide cylinder 4 coincides with the central axis A21 of the valve rod 21. The guide cylinder 4 includes a guide cylinder main body 41 and an adjustment member 42 (bush).

The guide cylinder main body 41 is formed in a cylindrical shape (for example, a cylindrical shape having a circular cross section orthogonal to the central axis A41) having a central axis A41 along the vertical direction. The inner peripheral surface of the guide cylinder main body 41 has a tip end inner peripheral surface 43, a tapered surface 44, and a large diameter inner peripheral surface 45 from the top to the bottom. The central axis A41 coincides with the central axis A4.
The adjusting member 42 is formed in a cylindrical shape having a central axis A42 extending in the vertical direction. The adjustment member 42 is provided on the inner peripheral surface of the guide cylinder main body 41 (large diameter inner peripheral surface 45). The central axis A42 coincides with the central axis A4. The inner diameter of the adjustment member 42 is smaller than the inner diameter of the large diameter inner circumferential surface 45 of the guide cylinder main body 41. Therefore, the upper end portion of the adjustment member 42 forms the diameter reducing step 46. The inner circumferential surface of the adjustment member 42 forms a small diameter inner circumferential surface 47. For example, the adjustment member 42 is separate from the guide cylinder main body 41.

Since the inner peripheral surface of the guide cylinder 4 includes the inner peripheral surface of the guide cylinder main body 41 and the inner peripheral surface of the adjustment member 42, the tip inner peripheral surface 43, the tapered surface 44, and the large diameter from top to bottom. It has an inner circumferential surface 45, a diameter reducing step 46, and a small diameter inner circumferential surface 47.
The inner diameter of the tip end inner circumferential surface 43 is constant in the axial direction. The tapered portion 44 is an enlarged diameter portion formed by the difference in inner diameter between the distal end portion inner circumferential surface 43 and the large diameter inner circumferential surface 45. The tapered portion 44 expands in diameter downward from the lower end of the tip end inner circumferential surface 43 to the upper end of the large diameter inner circumferential surface 45.

  FIGS. 3A and 3B are partial cross-sectional views for explaining the operation of the steam valve 10. FIG. 3A shows a state in which the valve rod 21 is at the lowest position. FIG. 3B shows a state in which the valve rod 21 is at the highest position. As shown in FIG. 3B, the valve rod 21 in the highest position is in contact with the tapered surface 44 of the valve rod 21 so that the valve rod 21 is restricted from rising. The movement range R1 is a range in which the shoulder portion 26 can move in the vertical direction, and more specifically, is a range from the lowest position (see FIG. 3A) to the highest position (see FIG. 3B). .

As shown in FIG. 2, the inner diameter of the large diameter inner circumferential surface 45 is larger than the inner diameter of the tip end inner circumferential surface 43 and is constant in the axial direction. The large diameter inner circumferential surface 45 includes a range corresponding to the movement range R1. The large diameter inner circumferential surface 45 forms a cylindrical surface.
The diameter reducing step 46 is a step which reduces in diameter from the lower end of the large diameter inner peripheral surface 45 to the upper end of the small diameter inner peripheral surface 47.

The small diameter inner circumferential surface 47 is located below the large diameter inner circumferential surface 45 (the other side in the axial direction). The inner diameter of the small diameter inner circumferential surface 47 is smaller than the inner diameter of the large diameter inner circumferential surface 45 and is constant in the axial direction. The small diameter inner circumferential surface 47 faces the main outer circumferential surface 27 a of the valve rod 21.
In the steam valve 10, the small diameter inner circumferential surface 47 is an inner circumferential surface of the adjustment member 42 which is separate from the guide cylinder main body 41, but the small diameter inner circumferential surface is integrally formed on the inner surface of the guide cylinder. It may be the inner peripheral surface of the bulging portion. The bulging portion is formed, for example, by bulging radially inward on the inner peripheral surface of the guide cylinder.

  The large diameter inner circumferential surface 45 has a larger inner diameter than the small diameter inner circumferential surface 47, so the gap with the valve rod 21 is larger than the small diameter inner circumferential surface 47. That is, the gap C1 between the large diameter inner peripheral surface 45 and the valve rod 21 (main outer peripheral surface 27a) is larger than the gap C2 between the small diameter inner peripheral surface 47 and the valve rod 21 (main outer peripheral surface 27a).

The gap C1 can be determined, for example, as follows.
The clearance C1 can be set so that the guide cylinder 4 and the valve rod 21 do not contact with each other. If the guide cylinder 4 and the valve rod 21 do not come in contact with each other, the operation of the valve rod 21 is not impeded, so that the normal operation of the valve rod 21 can be secured. The clearance C1 can also be defined so that the guide cylinder 4 and the valve rod 21 may come in contact with each other. In that case, the valve rod 21 is normally operated even in the state where the guide cylinder 4 and the valve rod 21 contact. It is necessary to operate. Therefore, the clearance C1 can be determined in accordance with either of the following policies (1) and (2).

(1) When the Contact between the Guide Cylinder 4 and the Valve Rod 21 is Not Permitted FIGS. 4A and 4B are partial sectional views showing the guide cylinder 104 of the steam valve of the comparative embodiment and the valve rod 21. It is. FIG. 4A shows the guide cylinder 104 and the valve rod 21 which are not deformed. In FIG. 4A, the central axis A104 of the guide cylinder 104 coincides with the central axis A21 of the valve rod 21. The inner circumferential surface of the guide cylinder 104 differs from the inner circumferential surface of the guide cylinder 4 shown in FIG. 2 in that the diameter reducing step 46 and the small diameter inner circumferential surface 47 are not provided.

The guide cylinder 104 of the comparative form may be deformed by the temperature rise due to the flow of steam. FIG. 4 (B) shows the guide cylinder 104 deformed in the radial direction and the valve rod 21 (see arrow). Here, it is assumed that the guide cylinder 104 is inclined in the arrow direction (left direction in FIG. 4B) with the proximal end 104b as a fulcrum. The central axis A104 and the central axis A21 do not match. The inner circumferential surface of the guide cylinder 104 is in contact with the shoulder 26 of the valve rod 21.
In addition, in FIG. 4 (B), although the deformation | transformation which the guide cylinder 104 tilts by making the base end 104b into a fulcrum was assumed, the deformation | transformation of the guide cylinder 104 may be deformation including a bending deformation.

  As shown in FIG. 1, also in the steam valve 10 according to the embodiment, the temperature rises due to the flow of the steam S at the start of the steam turbine or the like. Therefore, the guide cylinder 4 shown in FIG. 2 may be deformed in the radial direction due to the temperature increase, similarly to the guide cylinder 104 of the comparative embodiment shown in FIG. 4 (B). Therefore, when the policy (1), that is, when the contact between the guide cylinder 4 and the valve rod 21 is not allowed, the clearance C1 is the maximum radial deformation amount of the guide cylinder 4 at the height position of the shoulder portion 26. It can be set to exceed. As a result, the guide cylinder 4 is less likely to contact the valve rod 21, so the valve rod 21 can operate normally.

(2) When allowing the contact between the guide cylinder 4 and the valve rod 21 If the contact between the guide cylinder 4 and the valve rod 21 is allowed, the valve rod 21 may be in contact with the guide cylinder 4 and the valve rod 21. Is required to work properly.
FIG. 5 is a flowchart showing an example of a design method of the gap C1 in the policy (2). As shown in FIG. 5, first, the amount of deformation of the guide cylinder 4 due to the temperature rise is calculated (STEP 1). For example, an FEM (Finite Element Method) can be used to calculate the amount of deformation of the guide cylinder 4.

  The contact PV value between the guide cylinder 4 and the valve rod 21 is an index that gives the limit of the normal operation of the valve rod 21. The contact PV value is affected by the frictional force between the guide cylinder 4 and the valve rod 21. The frictional force between the guide cylinder 4 and the valve rod 21 varies with the amount of deformation of the guide cylinder 4. Therefore, based on the amount of deformation of the guide cylinder 4, it is possible to calculate a reference value of the contact PV value for causing the valve rod 21 to operate normally.

  Next, the contact PV value of the guide cylinder 4 and the valve rod 21 at the time of trip of the steam turbine (at the time of rapid closing of the stop valve 2) is calculated (STEP 2). FEM, MBD (Model Based Development) or the like can be used to calculate the contact PV value.

Then, the obtained contact PV value at the time of trip is compared with the reference value described above. If the contact PV value is lower than the reference value (STEP 3: Yes), the examination is ended.
If the contact PV value is equal to or higher than the reference value (STEP 3: No), the inner diameter of the guide cylinder 4 is decreased or the outer diameter of the valve rod 21 is decreased to increase the gap C1 (STEP 4). The PV value is calculated (STEP 2). Thus, the clearance C1 where the contact PV value falls below the reference value is derived. Thereby, the clearance C1 in which the valve rod 21 can operate normally is obtained.

The installation position of the adjustment member 42 shown in FIG. 2 can be determined as follows.
FIGS. 6A and 6B are diagrams showing an example of a design method of the adjustment member 42 in the steam valve 10. FIG. FIG. 6A shows the guide cylinder 104 and the valve rod 21 which are not deformed. FIG. 6 (B) shows the guide cylinder 104 deformed in the radial direction and the valve rod 21 (see arrow).

As shown in FIG. 6A, the height of the shoulder 26 relative to the proximal end 104b (lower end) of the guide cylinder 104 is "H". “C0” is a gap between the guide cylinder 104 and the valve rod 21.
As shown in FIG. 6 (B), it is assumed that the guide cylinder 104 is inclined with the proximal end 104b as a fulcrum due to thermal deformation (see arrow). Here, it is assumed that the guide cylinder 104 is inclined in the radial direction (leftward in FIG. 6 (B)). “Δ” is the amount of radial displacement of the guide cylinder 104 at the height position of the shoulder 26.

In the guide cylinder 104 in the deformed state shown in FIG. 6B, the minimum gap between the guide cylinder 104 and the valve rod 21 at the height position X1 is “Cx”. The clearance Cx can be calculated by the following equation (1). “X” is the height difference between the height position X1 and the shoulder 26.
Cx = (C0−δ) + x / H · δ (1)

From the equation (1), “x” capable of securing the gap a (= Cx) (minimum gap) between the guide cylinder 104 and the valve rod 21 can be obtained by the following equation (2).
x = H / δ · (a−C0 + δ) (2)

  The installation position of the adjustment member 42 shown in FIG. 1 can be determined based on Formula (2). For example, first, a gap a which can sufficiently suppress the leak amount of the steam passing through the gap between the guide cylinder 104 and the valve rod 21 is determined. Based on the gap a, “x” is calculated using equation (2). In the steam valve 10 shown in FIG. 1, the adjusting member 42 can be installed at a position where the height difference between the upper end (diameter reducing step 46) and the shoulder 26 of the valve rod 21 is “x”.

Next, the operation of the steam valve 10 will be described with reference to FIG. In FIG. 1, the stop valve 2 and the regulator valve 3 are in the closed state.
As shown in FIG. 1, when the control oil is supplied to the cylinder 62 of the stop valve drive mechanism 6, the piston 61, the valve rod 21 and the valve body 22 rise. Thereby, the valve body 22 is separated from the first valve seat 14, and the stop valve 2 is opened. When the control oil is supplied to the cylinder mechanism 72 of the adjustable valve drive mechanism 7, the valve rod 31 and the valve body 32 are raised by the operation of the operation lever 71. Thereby, the valve body 32 separates from the 2nd valve seat 15, and the control valve 3 is open | released.

  The steam S flows from the inlet 12 b into the main flow passage 11 b through the introduction flow passage 12 a, the control valve 3, and the stop valve 2. The steam S is discharged from the main flow passage 11b through the discharge flow passage 13a and then through the discharge port 13b. If necessary, when the control oil is supplied to or discharged from the cylinder mechanism 72, the valve rod 31 and the valve element 32 move up or down, and the opening degree of the control valve 3 is adjusted. Therefore, the flow rate of the steam S to be discharged is adjusted.

  At the time of trip of the steam turbine or the like, control oil is discharged from the cylinder 62 of the stop valve drive mechanism 6. By the elastic force of the spring 63, the piston 61, the valve rod 21 and the valve body 22 are lowered. Thereby, the valve body 22 reaches the first valve seat 14 and the stop valve 2 is closed. When control oil is supplied to the cylinder mechanism 72 of the adjustable valve drive mechanism 7, the valve rod 31 and the valve body 32 are lowered by the elastic force of the spring 73. Thereby, the valve body 32 reaches the 2nd valve seat 15, and the control valve 3 is closed. By the stop valve 2 and the control valve 3 being closed, the flow of the steam S is stopped and the steam turbine is stopped.

  In the steam valve 10 of the embodiment, since the inner peripheral surface of the guide cylinder 4 has the small diameter inner peripheral surface 47, the clearance between the small diameter inner peripheral surface 47 and the valve rod 21 can be reduced. Therefore, the amount of steam leaking to the outside of the valve casing 1 through the gap between the guide cylinder 4 and the valve rod 21 can be suppressed. The inner circumferential surface of the guide cylinder 4 has a large diameter inner circumferential surface 45 corresponding to the movement range R1 of the shoulder 26 of the valve rod 21. The steam valve 10 can secure a sufficient gap between the guide cylinder 4 and the valve rod 21 on the large diameter inner circumferential surface 45. Therefore, even when the guide cylinder 4 is deformed in the radial direction, the guide cylinder 4 does not contact the valve rod 21 or contacts the valve rod 21 to such an extent that the normal operation of the valve rod 21 becomes possible. Therefore, it is easy to ensure the normal operation of the valve rod 21.

  In the steam valve 10, as described above, the guide cylinder 4 does not contact the valve rod 21 or contacts the valve rod 21 to such an extent that the valve rod 21 can operate normally. Therefore, at the time of emergency stop of the steam turbine or the like, the seizing of the guide cylinder 4 and the valve rod 21 can be prevented, and the rapid closing of the stop valve 2 can be reliably performed.

  The steam valve 10 includes a guide cylinder main body 41 and an adjustment member 42 which is separate from the guide cylinder main body 41. Since the adjustment member 42 is separate from the guide cylinder main body 41, installation and replacement to the guide cylinder main body 41 is easy. Therefore, adjustment of the clearance C2 between the small diameter inner peripheral surface 47 and the valve rod 21 (main outer peripheral surface 27a) is easy.

  The valve rod 21 is provided with the tapered portion 24 at a position higher than the shoulder portion 26, and thus has a shape having a two-stage enlarged diameter portion. Therefore, as shown in FIG. 3B, when the tapered portion 24 abuts on the tapered surface 44 of the guide cylinder 4, the shoulder portion 26 is positioned low (that is, positioned closer to the other in the axial direction). Therefore, the shoulder portion 26 is difficult to abut on the guide cylinder 4.

Second Embodiment
FIG. 7 is a schematic view of a steam valve 210 according to a second embodiment of the present invention. FIG. 8 is a partial cross-sectional view of the steam valve 210. FIG. 9 is a cross-sectional view taken along line A-A of FIG. FIG. 9 is a view seen in parallel to the central axis A21 of the valve rod 21. As shown in FIG. FIG. 10 is a partial cross-sectional view for explaining the operation of the steam valve 210. As shown in FIG. In addition, about the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 7, the steam valve 210 includes a valve casing 1, a stop valve 2, an adjustment valve 3, a guide cylinder 204, a lid member 5, a stop valve drive mechanism 6, and an adjustment valve drive mechanism 7. Is equipped. The steam valve 210 has the same configuration as the steam valve 10 (see FIG. 1) of the first embodiment except that the guide cylinder 204 is used instead of the guide cylinder 4.

  As shown in FIG. 8, the guide cylinder 204 is formed in a cylindrical shape (for example, a cylindrical shape having a circular cross section orthogonal to the central axis A 204) having an insertion hole 204 a. The central axis A 204 of the guide cylinder 204 extends in the vertical direction. The guide cylinder 204 guides the valve rod 21 in the direction (axial direction) of the central axis A 204. In FIG. 8, a central axis A 204 is a central axis of a main inner circumferential surface 245 (described later).

The inner circumferential surface of the guide cylinder 204 has a tip inner circumferential surface 43, a tapered surface 44, and a main inner circumferential surface 245 from the top to the bottom.
The inner diameter of the main inner circumferential surface 245 is larger than the inner diameter of the tip inner circumferential surface 43 and is constant in the axial direction. The main inner circumferential surface 245 includes a range corresponding to the movement range R1. The main inner circumferential surface 245 forms a cylindrical surface.

  As shown in FIGS. 8 and 9, the central axis A 204 (the central axis of the main inner peripheral surface 245) of the guide cylinder 204 does not coincide with the central axis A 21 of the valve rod 21. As shown in FIG. 9, the central axis A 204 of the guide cylinder 204 is offset from the central axis A 21 of the valve rod 21 toward the discharge flow path 13 a. That is, the main inner circumferential surface 245 of the guide cylinder 204 is eccentric to the valve rod 21 on the side of the discharge flow passage 13 a.

  “C11”, when viewed parallel to the central axis A21, at the portion P1 of the main inner circumferential surface 245 closest to the discharge flow passage 13a, between the guide cylinder 204 (main inner circumferential surface 245) and the valve rod 21 It is a gap. “C12” is a gap between the guide cylinder 204 (main inner circumferential surface 245) and the valve rod 21 at a portion P2 farthest from the discharge flow passage 13a when viewed in parallel with the central axis A21. Since the central axis A 204 is shifted toward the discharge flow channel 13 a with respect to the central axis A 21, the gap C 11 is larger than the gap C 12.

  As shown in FIG. 7, in the portion of the valve casing 1 where the guide cylinder 204 is provided, the portion close to the discharge flow passage 13a is unlikely to affect the strength of the entire valve casing 1 even when the structure is simple. , May be formed thin. On the other hand, in order to secure the rigidity of the main body portion 11, the portion far from the discharge flow passage 13a is easily formed thick. For example, in FIG. 7, the main body side portion P3 on the left side of the guide cylinder 204 is likely to be thicker than the discharge side portion P4 on the right side of the guide cylinder 204. Therefore, the main body side portion P3 tends to be difficult to be deformed because the rigidity is high and the temperature rise is hard to occur. Therefore, as shown in FIG. 10, the guide cylinder 204 may be easily deformed to the main body side portion P3 side (left side in FIG. 10) when the temperature rises.

Next, the operation of the steam valve 210 will be described with reference to FIG. In FIG. 7, the stop valve 2 and the regulator valve 3 are in the closed state.
As shown in FIG. 7, when the control oil is supplied to the cylinder 62 of the stop valve drive mechanism 6, the piston 61, the valve rod 21 and the valve body 22 rise. Thereby, the valve body 22 is separated from the first valve seat 14, and the stop valve 2 is opened. When the control oil is supplied to the cylinder mechanism 72 of the adjustable valve drive mechanism 7, the valve rod 31 and the valve body 32 are raised by the operation of the operation lever 71. Thereby, the valve body 32 separates from the 2nd valve seat 15, and the control valve 3 is open | released.

  The steam S flows from the inlet 12 b into the main flow passage 11 b through the introduction flow passage 12 a, the control valve 3, and the stop valve 2. The steam S is discharged from the main flow passage 11b through the discharge flow passage 13a and then through the discharge port 13b. If necessary, when the control oil is supplied to or discharged from the cylinder mechanism 72, the valve rod 31 and the valve element 32 move up or down, and the opening degree of the control valve 3 is adjusted. Therefore, the flow rate of the steam S to be discharged is adjusted.

  At the time of trip of the steam turbine or the like, control oil is discharged from the cylinder 62 of the stop valve drive mechanism 6. By the elastic force of the spring 63, the piston 61, the valve rod 21 and the valve body 22 are lowered. Thereby, the valve body 22 reaches the first valve seat 14 and the stop valve 2 is closed. Control oil is supplied to the cylinder mechanism 72 of the control valve drive mechanism 7. By the elastic force of the spring 73, the valve rod 31 and the valve body 32 are lowered. Thereby, the valve body 32 reaches the 2nd valve seat 15, and the control valve 3 is closed. By the stop valve 2 and the control valve 3 being closed, the flow of the steam S is stopped and the steam turbine is stopped.

  As shown in FIG. 9, in the steam valve 210 of the embodiment, the inner circumferential surface (main inner circumferential surface 245) of the guide cylinder 204 is eccentric to the valve rod 21. Therefore, for example, as shown in FIG. 10, even when the guide cylinder 204 is deformed in the radial direction, the guide cylinder 204 does not contact the valve rod 21 or a degree to which the valve rod 21 can operate normally. Contact the valve rod 21. Therefore, it is easy to ensure the normal operation of the valve rod 21.

  In the steam valve 210 of the embodiment, the gap C11 between the portion P1 closest to the discharge flow passage 13a and the valve rod 21 in the inner peripheral surface of the guide cylinder 204 is the portion P2 farthest from the discharge flow passage 13a and the valve rod 21 The clearance C12 is larger than the clearance C12. Therefore, as shown in FIG. 10, even when the guide cylinder 204 is deformed in the radial direction on the opposite side (left side in FIG. 10) to the discharge flow path 13a side, the guide cylinder 204 contacts the valve rod 21. Otherwise, it contacts the valve rod 21 to such an extent that the normal operation of the valve rod 21 is possible. Therefore, it is easy to ensure the normal operation of the valve rod 21.

  In the steam valve 210, as described above, the guide cylinder 204 does not contact the valve rod 21 or contacts the valve rod 21 to such an extent that normal operation of the valve rod 21 is possible. Therefore, at the time of emergency stop of the steam turbine or the like, seizing of the guide cylinder 204 and the valve rod 21 can be prevented, and the rapid closing of the stop valve 2 can be reliably performed.

  In the steam valve 210, the guide cylinder 204 has a clearance C12 smaller than the clearance C11 at a portion far from the discharge flow passage 13a, so the steam leaking from the valve cylinder 1 to the outside through the clearance between the guide cylinder 204 and the valve rod 21 The amount can be reduced.

  The valve rod 21 is provided with the tapered portion 24 at a position higher than the shoulder portion 26, and thus has a shape having a two-stage enlarged diameter portion. Therefore, as shown in FIG. 3B, when the tapered portion 24 abuts on the tapered surface 44 of the guide cylinder 4, the shoulder portion 26 is positioned low (that is, positioned closer to the other in the axial direction). Therefore, the shoulder portion 26 is difficult to abut on the guide cylinder 4.

  The steam valve 10 (see FIG. 1) and the steam valve 210 (see FIG. 7) can be applied to a steam turbine. The steam turbine includes, for example, a high pressure steam turbine, an intermediate pressure steam turbine, and a low pressure steam turbine. The steam valves 10, 210 can be provided, for example, in the main steam supply piping that supplies high pressure steam from the boiler to the high pressure steam turbine. This steam turbine is excellent in reliability because it includes the steam valve 10 or the steam valve 210 which can easily suppress the amount of steam leakage and ensure the normal operation of the valve rod.

The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like within the scope of the present invention are also included. .
For example, although the adjusting member is not used in the steam valve 210 shown in FIG. 7, the adjusting member may be used as in the steam valve 10 of the first embodiment.
FIG. 11 is a partial cross-sectional view of a steam valve 310 which is a modification of the steam valve 210 shown in FIG. 7. 12 is a cross-sectional view taken along the line B-B of FIG.
As shown in FIGS. 11 and 12, in the steam valve 310, an adjustment member 242 is provided on the inner circumferential surface of the guide cylinder 204 at a position including the portion P1 (see FIG. 12) closest to the discharge flow passage 13a. There is. The adjusting member 242 has an arc-shaped cross section orthogonal to the central axis A 204. The adjusting member 242 is shaped so as to increase in thickness closer to the portion P1 (see FIG. 12).

  Since the steam valve 310 includes the adjusting member 242, the amount of steam leaking to the outside of the valve casing 1 through the gap between the guide cylinder 204 and the valve rod 21 can be suppressed.

  Although the valve rod 21 shown in FIG. 2 is shaped to have two stages of enlarged diameter portions (a tapered portion 24 and a shoulder portion 26), the shape of the valve rod is not limited to this. The valve stem may be shaped to have, for example, a single-stage enlarged diameter portion (shoulder portion).

Reference Signs List 1 valve casing 2 stop valve 4, 204 guide cylinder 10, 210 steam valve 12a introduction channel 13a discharge channel 14 first valve seat (valve seat)
21 Valve rod 22 Valve body 26 Shoulder 27a Main outer circumferential surface 42, 242 Adjustment member 44 Tapered surface (contact step)
45 Large diameter inner circumferential surface 47 Small diameter inner circumferential surface C1 Clearance C2 between the large diameter inner circumferential surface and the valve rod Clearance C1 between the small diameter inner circumferential surface and the valve rod Clearance C12 gap with the valve rod at the portion closest to the discharge flow path Clearance P1 with the valve stem at the part farthest from the flow path Part P2 closest to the discharge flow path Part R1 farthest from the discharge flow path Moving range S Steam

Claims (8)

A valve casing having an introduction flow passage through which steam is introduced and a discharge flow passage through which the steam is discharged;
An externally moveable valve rod inserted from the outside into the valve casing, and a valve provided at one axial end of the valve rod and capable of abutting on a valve seat in the valve casing A stop valve having a body,
A cylindrical guide cylinder fixed to the valve casing and having the valve stem inserted therein and guiding the valve stem in the axial direction;
Equipped with
The valve rod is
A shoulder that increases in diameter toward the other axial side of the valve rod;
A main outer peripheral surface connected to the other axial side of the shoulder;
Have
The inner circumferential surface of the guide cylinder is
A large diameter inner circumferential surface corresponding to the range of movement of the shoulder;
And a small diameter inner circumferential surface located on the other side in the axial direction of the large diameter inner circumferential surface and facing the main outer circumferential surface,
The steam valve, wherein the large diameter inner circumferential surface has a larger gap with the valve rod than the small diameter inner circumferential surface. The guide cylinder includes a cylindrical guide cylinder main body, and an adjustment member provided on the inner peripheral surface of the guide cylindrical main body,
The steam valve according to claim 1, wherein the small diameter inner circumferential surface is an inner circumferential surface of the adjusting member. The valve rod further includes a contact step that contacts the inner surface of the guide cylinder when the valve body is separated from the valve seat,
The steam valve according to claim 1, wherein the contact step is formed on one side in the axial direction with respect to the shoulder. A valve casing having an introduction flow passage through which steam is introduced and a discharge flow passage through which the steam is discharged;
An externally moveable valve rod inserted from the outside into the valve casing, and a valve provided at one axial end of the valve rod and capable of abutting on a valve seat in the valve casing A stop valve having a body,
A tubular guide cylinder fixed to the valve casing and accommodating the valve stem inside and guiding the valve stem in the axial direction;
Equipped with
The valve rod is
A shoulder that increases in diameter toward the other axial side of the valve rod;
A main outer peripheral surface connected to the other axial side of the shoulder;
Have
The steam valve, wherein an inner circumferential surface of the guide cylinder corresponding to a movement range of the shoulder portion is eccentric to the valve rod.   In the inner peripheral surface of the guide cylinder corresponding to the movement range of the shoulder when viewed in parallel with the axial direction of the valve rod, a gap with the valve rod at a portion closest to the discharge passage is the discharge The steam valve according to claim 4, which is larger than a gap with the valve stem at a portion farthest from the flow path. The guide cylinder includes a cylindrical guide cylinder main body, and an adjustment member provided on the inner peripheral surface of the guide cylindrical main body,
The steam valve according to claim 5, wherein the adjustment member is provided at a position including a portion closest to the discharge flow channel. The valve rod further includes a contact step that contacts the inner surface of the guide cylinder when the valve body is separated from the valve seat,
The steam valve according to any one of claims 4 to 6, wherein the contact step is formed on one side in the axial direction with respect to the shoulder.   A steam turbine comprising the steam valve according to any one of claims 1 to 7.

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