JP2005321061A - Valve for high temperature - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve for high temperature ideal for high temperature fluid with which high temperature fluid can be surely shut off at closing. <P>SOLUTION: A valve element 10 has a spherical surface 21 having a projecting spherical shape coming into line contact with the entire circumference of a valve seat 8 at closing. The lower end of a valve rod 9 is inserted into a supporting space of the valve element 10. A valve supporting part 9b formed in the lower end of the valve rod 9 supports the valve element 10 in the supporting space by engaging with an engaging part 20b formed in the valve element 10 from below. The bottom surface 24 in the supporting space is formed in a recessing spherical shape. The lower end spherical surface 9d of the valve rod 9 is brought into point contact with the bottom surface 24 in the supporting space at one position with the valve seat 8 closed by the valve element 10. A belleville spring 26 for thrusting the valve element 10 in the closing direction is provided in the supporting space. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-temperature valve used when, for example, a high-temperature fluid such as a high-temperature gas is shut off.

  Conventionally, as this type of valve, for example, as shown in FIG. 7, when opening and closing, there is a valve body 61 that moves up and down along the axis 63 of the valve rod 62 and contacts and separates from the valve seat 64 ( For example, see Patent Document 1).

  That is, the valve seat 64 is provided in the lower part in the casing 65, the valve rod 62 passes through the cylindrical bonnet 66 provided on the casing 65, and is inserted into the valve chamber 67 in the lower part of the bonnet 66. A valve guide 68 is provided. The valve body 61 is provided at the lower end portion of the valve rod 62 and is moved up and down by being guided by the valve guide 68 to open and close the opening 69 of the valve seat 64. A spherical portion 70 that can be brought into contact with and separated from the valve seat 64 is formed in the lower portion of the valve body 61.

  Further, a valve body support portion 72 having a spherical portion 71 at the lower portion is formed at the lower end of the valve rod 62. As shown in FIG. 8, a support space 73 that opens to the upper end portion is formed in the valve body 61. The valve body support portion 72 is inserted into the support space 73 from above, and a valve nut 74 is externally fitted to the lower end of the valve rod 62, and the valve nut 74 is screwed into the upper portion of the valve body 61. A bottom surface 75 in the support space 73 is formed as a flat surface.

According to this, as shown in FIG. 7, the valve body 61 is brought into contact with the valve seat 64 to close the opening 69 by lowering the valve rod 62 when closed.
However, in the above conventional type, as shown in FIG. 8, the bottom surface 75 in the support space 73 of the valve body 61 is formed flat. Therefore, when closed, the bottom surface 75 and the inner peripheral surface 76 in the support space 73 There is a problem that stress tends to concentrate on the boundary portion C (corner portion).

  Further, since the thickness T from the bottom surface 75 to the lower end of the valve body 61 is thickest at the central portion in the radial direction and decreases toward the end from the central portion, such a thickness difference causes a difference in thickness at the time of use. There is a possibility that temperature unevenness occurs in the lower part of the valve body 61, the thermal stress generated in the lower part of the valve body 61 increases, and the valve body 61 breaks.

  Further, when closed, as shown in FIG. 9, the axial center 63 of the valve stem 62 is in the radial direction with respect to the center line 64 a of the valve seat 64 due to the influence of thermal expansion, processing error and tolerance, or eccentricity due to long-term use. When the valve body 61 is displaced, the valve body 61 may come into contact with the edge of the valve seat 64. At this time, since the spherical surface portion 71 of the valve body support portion 72 comes into contact with the flat bottom surface 75 in the support space 73, the valve body 61 is inclined, whereby the spherical surface portion 70 of the valve body 61 is aligned with the edge of the valve seat 64. It adheres to the entire circumference.

  However, in this case, there is a problem in that the contact pressure between the valve body 61 and the valve seat 64 is insufficient in the surface pressure of the valve body 61 with respect to the valve seat 64 at a location B on the opposite side to the displacement direction of the valve body 61. Get up. If the surface pressure is insufficient, the fluid may leak and cannot be reliably shut off.

10A and 10B are graphs of the surface pressure of the valve body 61 with respect to the valve seat 64. FIG. 10A is a graph showing the axial center 63 of the valve stem 62 as the center of the valve seat 64 as shown in FIG. FIG. 9B shows a case where the axis 63 of the valve stem 62 is aligned with the line 64a, as shown in FIG. In the graph of (a), at the time of closing, the surface pressure of the valve body 61 against the valve seat 64 is higher than the minimum required surface pressure P at any location. However, when the displacement occurs, the surface pressure at the location A on the displaced side of the valve body 61 is higher than the minimum required surface pressure P as shown in the graph of (b), but on the side opposite to the displacement of the valve body 61. The surface pressure at the location B is lower than the minimum required surface pressure P, and the surface pressure at the location B may be insufficient.
JP-A-11-280411

  The present invention solves a specific problem caused by a high-temperature valve. Specifically, even when the center of the valve stem and the valve seat is displaced due to thermal expansion or the like, the valve body is closed when closed. In contact with the entire circumference of the valve body, further reducing the stress concentration generated in the valve body, reducing the thermal stress generated in the lower part of the valve body, and preventing the surface pressure of the valve body against the valve seat from being insufficient. Provided is a high temperature valve that is possible and has a structure more suitable for high temperature fluids.

In order to achieve the above object, the first invention is a high temperature valve in which the valve element moves in the axial direction of the valve stem and contacts and separates from the valve seat when opening and closing,
The valve seat is formed in a shape in which the diameter of the opening gradually decreases as the valve body closes,
The valve body has a convex spherical surface that contacts the valve seat over the entire circumference when closed,
In the valve body, a support space that opens at the end opposite to the valve seat is formed,
The lower end of the valve stem is inserted into the support space;
The valve body support portion formed at the lower end of the valve stem engages with the engagement portion formed on the valve body to support the valve body,
A gap is formed between the valve body support portion and the engagement portion and between the outer peripheral surface of the valve stem and the inner peripheral surface of the valve body,
The bottom surface in the support space is formed in a concave spherical shape,
In a state where the opening of the valve seat is closed by the valve body, the lower end of the valve stem is configured to make point contact with the bottom surface in the support space at one location.

  According to this, at the time of closing, by moving the valve stem in the closing direction, the spherical portion of the valve body contacts the valve seat over the entire circumference, and the opening of the valve seat is closed by the valve body. In addition, if the center of the valve stem is displaced radially from the center of the valve seat due to thermal expansion, processing error, tolerance, or eccentricity due to long-term use, the valve stem moves in the closing direction when closed. Along with this, the position on the side where the valve body has shifted comes into contact with the valve seat first, and immediately after that, the valve body tilts and reliably contacts the valve seat over the entire circumference. Thereby, a clearance gap does not arise between a valve body and a valve seat, and sealing performance is maintained.

  At this time, since the lower end of the valve stem makes point contact with the concave spherical bottom surface in the support space at one point, the lower end of the valve rod is guided to the center side of the valve seat by the bottom surface, thereby Can be suppressed.

In addition, since the bottom surface in the support space is formed in a concave spherical shape, the stress concentration at the boundary between the bottom surface in the support space and the inner peripheral surface is alleviated when closed.
In addition, the wall thickness from the bottom of the support space to the lower end of the valve body is almost uniform in the radial direction. By reducing the thickness difference, the uneven temperature of the valve body during high temperature use is alleviated. Is reduced.

Furthermore, machining of the bottom surface in the support space is easy during manufacturing. From the above, it is possible to provide a high temperature valve more suitable for a high temperature fluid.
The second aspect of the invention is a high temperature valve in which the valve element moves in the axial direction of the valve stem and contacts and separates from the valve seat during opening and closing.
The valve seat is formed in a shape in which the diameter of the opening gradually decreases as the valve body closes,
The valve body has a convex spherical surface that contacts the valve seat over the entire circumference when closed,
In the valve body, a support space that opens at the end opposite to the valve seat is formed,
The lower end of the valve stem is inserted into the support space;
The valve body support portion formed at the lower end of the valve stem engages with the engagement portion formed on the valve body to support the valve body,
A gap is formed between the valve body support portion and the engagement portion and between the outer peripheral surface of the valve stem and the inner peripheral surface of the valve body,
A pressing member that presses the valve body in the closing direction is provided in the support space.

  According to this, when the center of the valve stem deviates radially from the center of the valve seat due to thermal expansion, machining error, tolerance, or eccentricity due to long-term use, the valve stem moves in the closing direction when closed. As a result, the portion of the valve body on the shifted side first comes into contact with the valve seat. Immediately thereafter, the valve body tilts and reliably makes contact with the valve seat over the entire circumference. At this time, since the valve body is pressed in the closing direction by the pressing member, the surface pressure to the valve seat of the valve body is ensured, and the lack of the surface pressure at the position opposite to the displacement direction of the valve body is prevented. be able to. From the above, it is possible to provide a high temperature valve more suitable for a high temperature fluid.

  As described above, according to the first aspect of the present invention, even when the center of the valve stem is displaced from the center of the valve seat due to thermal expansion or the like when closed, there is no gap between the valve body and the valve seat. , Sealability is maintained. Moreover, expansion of the displacement of the valve stem can be suppressed, stress concentration at the boundary between the bottom surface and the inner peripheral surface in the support space is alleviated, and thermal stress generated in the valve body is reduced.

  Further, according to the second aspect of the invention, even when the center of the valve stem is deviated from the center of the valve seat, the surface pressure to the valve seat of the valve body is ensured, and at the location opposite to the direction of displacement of the valve body. Insufficient surface pressure can be prevented.

  According to the first and second inventions, a high temperature valve more suitable for a high temperature fluid can be provided.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 to 3, reference numeral 1 denotes a high-temperature valve used for a high-temperature fluid (for example, a gas of 1000 ° C. or lower), which is configured as follows.

  A cylindrical bonnet 4 is provided in the upper part of the valve box 3, and a flow path 7 extending from the inlet 5 to the outlet 6 and a valve seat 8 are formed in the valve box 3. A valve stem 9 is inserted from the bonnet 4 into the valve box 3, and a valve body 10 is provided at the lower end of the valve stem 9. The shaft center 11 of the valve stem 9 is set in the vertical direction, and when opening and closing, the valve body 10 moves up and down in the direction of the shaft center 11 of the valve stem 9 and contacts and separates from the valve seat 8.

  A plurality of gland packings 12 that seal between the outer peripheral surface of the valve stem 9 and the inner peripheral surface of the bonnet 4 are built in the upper portion of the bonnet 4. Note that a graphite-based packing is used as the gland packing 12. A packing presser 13 for holding the gland packing 12 is attached to the upper end of the bonnet 4 via bolts 14 and nuts 15. A plurality of upper and lower fins 16 for heat dissipation are attached to the outer periphery of the bonnet 4. The fins 16 are disposed between the gland packing 12 and the valve box 3.

Above the bonnet 4, valve opening / closing means (not shown) such as an air cylinder is provided to open and close the valve body 10 by moving the valve rod 9 up and down.
The valve box 3, the bonnet 4, the valve stem 9, and the valve body 10 are made of nickel-molybdenum age-resistant hydrochloric acid alloy (for example, Hastelloy X of Highness Stellite, USA).

As shown in FIG. 4, the valve seat 8 is formed so as to be inclined in a conical shape in which the diameter of the opening 17 gradually decreases in the closing direction (that is, downward) of the valve body 10.
As shown in FIG. 3, the valve body 10 includes a valve body main body member 19 and a valve body engaging member 20. A convex spherical surface 21 is formed in the lower part of the valve body member 19. Further, in the valve body main body member 19, a support space 22 is formed that opens to the upper end (that is, the end opposite to the valve seat 8). An internal thread portion 23 is formed on the upper inner peripheral surface of the valve body main member 19. The bottom surface 24 in the support space 22 is formed in a concave spherical shape. The spherical surface portion 21 and the bottom surface 24 are formed as spherical surfaces having the same center O.

  The valve body engaging member 20 is an annular member provided with a through hole 20a penetrating in the direction of the axis 11, and has a cylindrical engaging portion 20b protruding downward. A male screw portion 25 is formed on the outer peripheral surface of the engaging portion 20b. By engaging the male screw portion 25 with the female screw portion 23, the engaging portion 20b is inserted into the upper portion of the support space 22, and the valve body engaging member 20 is attached to the upper portion of the valve body main body member 19. .

  As shown in FIG. 2, the valve stem 9 includes a valve stem body 9a, a valve body support portion 9b formed at the lower end of the valve stem body 9a and having a larger diameter than the valve stem body 9a, and the valve body. It has a small diameter rod portion 9c which is formed at the lower end portion of the support portion 9b and has a smaller diameter than the valve rod main body 9a. A convex spherical lower end spherical surface portion 9d is formed at the lower end of the small-diameter bar portion 9c so as to make point contact with the bottom surface 24 in the support space 22 at one place when the small diameter rod portion 9c is closed.

  A plurality of disc springs 26 (an example of a pressing member) that press the valve body 10 in the closing direction are provided between the bottom surface 24 in the support space 22 and the valve body support portion 9b. The disc springs 26 are extendable in the direction of the axis 11 and are fitted on the small-diameter bar portion 9c.

  As shown in FIGS. 2 and 3, the lower end portion of the valve stem 9 penetrates the through hole 20a and is inserted into the support space 22, and the valve body support portion 9b is engaged with the engagement portion 20b in the support space 22. The valve body 10 is supported by engaging from below. In addition, between the outer peripheral surface of the valve stem main body 9a and the inner peripheral surface of the valve body engaging member 20, and between the outer peripheral surface of the valve body support portion 9b and the inner peripheral surface of the valve body main body member 19, respectively. A gap 27 is formed. Further, when the valve rod 9 is closed, a predetermined gap 28 is also formed between the valve body support portion 9b and the engaging portion 20b in a state where the lower end spherical portion 9d of the valve rod 9 is in point contact with the bottom surface 24 in the support space 22. Is done.

  In addition, the inclined surface of the valve seat 8 and a part of the spherical portion 21 of the valve body 10 are each made of a cobalt-molybdenum-chromium material (for example, Trivalloy T-Nikkoshi Co., Ltd.), which is an example of a heat and wear resistant material. 800 and the like are formed by depositing (overlay welding), and when closed, the seal portion 30 of the valve body 10 is in line contact with the seal portion 29 of the valve seat 8 over the entire circumference.

Hereinafter, the operation of the above configuration will be described.
At the time of closing, the valve stem 9 is moved in the closing direction, so that the spherical portion 21 of the valve body 10 is in line contact with the valve seat 8 over the entire circumference, as shown in FIG. Closed by the body 10. At this time, the disc spring 26 is compressed by the downward pressing force of the valve stem 9, the lower spherical surface portion 9d of the valve stem 9 contacts the bottom surface 24 in the support space 22 at one point, and the valve body support portion 9b. A gap 28 is formed between the engagement portion 20b and the engagement portion 20b.

  Further, at the time of closing, as shown in FIG. 4, the shaft center 11 of the valve stem 9 is in the radial direction with respect to the center line 8 a of the valve seat 8 due to thermal expansion, processing error / tolerance, or eccentricity due to long-term use. 5, as the valve rod 9 moves in the closing direction, as shown in FIG. 5, the position A on the side of the valve body 10 that has been displaced first comes into contact with the valve seat 8, and immediately thereafter, As shown in FIG. 6, the valve body 10 is inclined with the location A as a fulcrum, and the spherical surface portion 21 of the valve body 10 reliably makes line contact with the valve seat 8 over the entire circumference. Thereby, a clearance gap does not arise between the valve body 10 and the valve seat 8, and a sealing performance is maintained.

  At this time, the disc spring 26 is compressed at the location A and at the location B opposite to the location A, and the disc 10 is pressed in the closing direction by the disc spring 26. The surface pressure to the valve seat 8 is ensured, and the shortage of the surface pressure at the location B opposite to the location A where the valve body 10 is shifted can be prevented. Thereby, the leakage of the high temperature fluid can be reliably prevented, and the high temperature fluid can be reliably shut off.

  10 (c) shows a case where the shaft center 11 of the valve stem 9 is displaced in the radial direction with respect to the center line 8a of the valve seat 8 as shown in FIG. 6 in the high temperature valve 1 of the present embodiment. It is a graph of the surface pressure of the valve body 10 with respect to the valve seat 8. FIG. According to this, since the pressing force F by the disc spring 26 is added to the downward pressing force by the valve stem 9, the surface pressure at the point B on the opposite side to the displacement of the valve body 10 is higher than the minimum required surface pressure P. Become. Thereby, the lack of the surface pressure in the location B on the opposite side to the location A on the shifted side of the valve body 10 can be prevented.

  Further, as shown in FIG. 6, when the bottom end spherical portion 9d of the valve stem 9 is in point contact with the concave spherical bottom surface 24 in the support space 22 at one point when closed, the bottom end spherical portion 9d is It is guided to the center line 8a of the valve seat 8, and thereby, the expansion of the deviation of the valve stem 9 can be suppressed.

  Further, as shown in FIG. 3, since the bottom surface 24 in the support space 22 is formed in a concave spherical shape, the stress at the boundary portion C (corner portion) between the bottom surface 24 and the inner peripheral surface 32 in the support space 22 when closed. Concentration is eased.

  Further, the wall thickness T from the bottom surface 24 in the support space 22 to the lower end of the valve body 10 is almost uniform in the radial direction, and the temperature unevenness of the valve body 10 at the time of high temperature use is mitigated by reducing the thickness difference. Thus, the thermal stress generated in the valve body 10 is reduced.

Furthermore, machining of the bottom surface 24 in the support space 22 is easy at the time of manufacture.
Further, as shown in FIG. 2, when the valve is closed, the seal portions 29 and 30 made of a cobalt-molybdenum-chromium material having excellent heat resistance and wear resistance come into contact with each other. 10 can be prevented from being damaged.

  Further, as shown in FIG. 1, heat from the high temperature fluid is transmitted from the valve box 3 to the bonnet 4 and dissipated by the fins 16 in front of the gland packing 12, thereby preventing the gland packing 12 from becoming high temperature. The sealing performance by the gland packing 12 is maintained.

  In addition, when opened, the valve body 9 is moved away from the valve seat 8 by moving the valve stem 9 in the opening direction, the disc spring 26 is extended, and the valve body support portion 9b is engaged. The valve body 10 is supported on the lower end portion of the valve stem 9 by engaging with the portion 20b from below.

  In the above embodiment, as shown in FIG. 2, the lower end spherical portion 9d is provided at the lower end of the valve stem 9, but instead of the lower end spherical portion 9d, for example, a conical lower end conical portion is provided. The tip of the conical portion may be brought into point contact with the bottom surface 24 in the support space 22 at one location.

In the above embodiment, the disc spring 26 is used as an example of the pressing member, but a coil spring or the like may be used.
In the above embodiment, as shown in FIG. 3, the spherical surface portion 21 of the valve body 10 and the bottom surface 24 in the support space 22 are formed as spherical surfaces having the same center O. And the center of the bottom surface 24 may be different.

It is a side view of the valve for high temperature in the embodiment of the present invention. FIG. 4 is an enlarged view of the valve seat and the valve body of the high temperature valve, showing a case where the valve body is closed in a state where the center of the valve body coincides with the center of the valve seat. FIG. 3 is an exploded view of the valve body of the high temperature valve. It is a figure which shows the state from which the valve body of the valve for high temperature was spaced apart above the valve seat, and shows the case where the center of the valve body has shifted | deviated with respect to the center of a valve seat. FIG. 4 is a view when the valve body contacts the valve seat in a state where the center of the valve body of the high temperature valve is shifted from the center of the valve seat. FIG. 6 is a view when the valve body closes the opening of the valve seat in a state where the center of the valve body of the high temperature valve is deviated from the center of the valve seat. It is sectional drawing of the conventional valve. It is a figure of the valve body of a valve. FIG. 6 is a view when the valve body closes the opening of the valve seat in a state where the center of the valve body of the valve is deviated from the center of the valve seat. It is a graph of the surface pressure of the valve body with respect to a valve seat, (a) shows the case where the center of a valve body corresponds with the center of a valve seat in a conventional valve, (b) shows the valve body of a conventional valve. The case where the center has shifted | deviated with respect to the center of a valve seat is shown, (c) has shown the case where the center of a valve body has shifted | deviated with respect to the center of a valve seat in the valve of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High temperature valve 8 Valve seat 9 Valve stick 9b Valve body support part 10 Valve body 11 Axle center 17 Opening part 20b Engagement part 21 Spherical part 22 Support space 24 Bottom face 26 Disc spring (pressing member)
27, 28 Clearance

Claims (2)

When opening and closing, the valve body moves in the axial direction of the valve stem, and is a high temperature valve that contacts and separates from the valve seat,
The valve seat is formed in a shape in which the diameter of the opening gradually decreases as the valve body closes,
The valve body has a convex spherical surface that contacts the valve seat over the entire circumference when closed,
In the valve body, a support space that opens at the end opposite to the valve seat is formed,
The lower end of the valve stem is inserted into the support space;
The valve body support portion formed at the lower end of the valve stem engages with the engagement portion formed on the valve body to support the valve body,
A gap is formed between the valve body support portion and the engagement portion and between the outer peripheral surface of the valve stem and the inner peripheral surface of the valve body,
The bottom surface in the support space is formed in a concave spherical shape,
A high-temperature valve characterized in that the lower end of the valve stem is in point contact with the bottom surface in the support space at a single location in a state in which the opening of the valve seat is closed by the valve body. When opening and closing, the valve body moves in the axial direction of the valve stem and contacts and separates from the valve seat.
The valve seat is formed in a shape in which the diameter of the opening gradually decreases as the valve body closes,
The valve body has a convex spherical surface that contacts the valve seat over the entire circumference when closed,
In the valve body, a support space that opens at the end opposite to the valve seat is formed,
The lower end of the valve stem is inserted into the support space;
The valve body support portion formed at the lower end of the valve stem engages with the engagement portion formed on the valve body to support the valve body,
A gap is formed between the valve body support portion and the engagement portion and between the outer peripheral surface of the valve stem and the inner peripheral surface of the valve body,
A high-temperature valve, wherein a pressing member that presses the valve body in the closing direction is provided in the support space.

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