JPH0444801Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to the structure of a steam valve such as a main steam stop valve and a steam control valve provided at a steam inlet of a steam turbine.

[Prior art and its problems]

A main steam stop valve and a steam control valve are installed just before the steam inlet of the steam turbine supplied from a boiler, etc. The former valve is opened and closed to supply and cut off the steam, and the latter valve is opened and closed. The amount of steam supplied is controlled by adjusting the temperature. In these steam valves, the shape of the valve chamber inside the valve casing through which steam flows and the shape of the steam exhaust passage connected to the valve seat are each formed into independent shapes, and the shape of the connecting portion between the two is not smooth. This will be explained below based on the drawings.

FIG. 2 is a sectional view showing the structure of a conventional steam stop valve. In the figure, reference numeral 1 denotes a valve casing having a T-shaped appearance from which a portion (details not shown) protruding from the side includes a steam inlet passage connected to a steam supply pipe (not shown). That is, a space serving as a valve chamber 10 is provided inside the T-shaped base, and an opening portion above which is closed by attaching a valve cover 4, which will be described later, communicates with the valve chamber 10 and forms a steam exhaust path 12. An opening is arranged coaxially below the opening, and an opening that becomes the steam inlet passage 11 is arranged on the right side, perpendicular to a common longitudinal center line of both openings. .

The shape of the valve chamber 10 is a deformed spherical space in which a spherical shape is pushed from below toward the center and the lower side of the spherical shape is bulged out to the side, and the valve lid 4 is attached as described above. A circular opening (steam exhaust passage 12) extends downward from the lower part of the valve chamber 10 coaxially with the opening, and a circular opening (steam inflow passage 12) extends laterally. 11). This valve chamber 1
A valve seat 6 on which a valve body 5 is seated and closes the steam exhaust passage 12 is arranged as the center line of the steam exhaust passage 12, and the steam exhaust passage 12 is connected to the valve seat 6 and has a circular cross section. It is extended downward. Furthermore, valve seat 6
A strainer seat 10a, on which a steam strainer 3 (described later) is mounted, is provided on the outside of the valve seat 6 substantially horizontally to the position.

The steam strainer 3 has a cylindrical shape with both ends open, and is made by laminating a large number of corrugated plate rings and flat plate rings alternately, and supporting rings 3a and 3b are arranged at both ends. The steam flows through a large number of small gaps formed in the side wall portion 3c, thereby removing water droplets and foreign matter from the steam and preventing them from flowing into the steam turbine (not shown).

The valve lid 4 has a hanging part in the shape of a right circular cone with the top removed, and the bottom corner of the valve lid 4 is rounded. A through hole is provided concentrically through which a valve rod 2 holding a valve body 5 at its lower portion is guided so as to be freely raised and lowered. Furthermore, a cylindrical recess in which a valve body is accommodated is provided below the hanging portion. Further, an annular notch 4a into which the upper support ring of the steam strainer 3 is fitted is provided on the outer periphery of the lower end surface of the valve lid 4 that defines the upper part of the valve chamber 10.

On the other hand, the steam inlet passage 11 has a diameter at its terminal end (connection part to the valve chamber 10) approximately corresponding to the height of the side wall 3c of the steam strainer 3; The diameter of the steam supply pipe (not shown) is the same as that of the steam supply pipe (not shown).

In the steam valve configured as described above, steam sent from a boiler (not shown) is sent to the steam valve via a steam supply pipe (not shown), and then passes through the steam inflow path 11. Foreign matter is removed by entering the valve chamber 10 and passing through the steam strainer 3 disposed inside the valve chamber 10, and then flowing into the steam exhaust path 12.
The steam entering the valve chamber 10 passes through the side wall 3c of the steam strainer 3 and connects the lower end of the hanging portion 4b of the valve cover 4 with the valve seat 6. The flow passes through the gap and exits to the steam exhaust passage 12, bypasses the hanging portion 4b, passes through the side wall 3c, hits the inner wall surface of the valve chamber 10, and then enters the steam strainer 3 through the side wall 3c again and enters the steam exhaust passage 12. Various steam flows, such as a flow to be sent out, are collected in the valve chamber 10 and sent to the steam turbine.

In this case, the shape of the valve chamber 10 and the steam inflow path 1
The cross-sectional shapes of the valve chamber 10 and the steam exhaust passage 12 are determined independently, and therefore, the connecting portion between the valve chamber 10 and the steam exhaust passage 12 is at a right angle, creating a portion that disturbs the steam flow. In other words, the diameter of the circular cross section of the steam inlet passage 11 increases as it approaches the valve chamber 10.
The connection is relatively smooth because it is gradually enlarged to approach the height of the steam strainer 3 and connected to the valve chamber 10, but the shape of the valve chamber 10 deforms into a bulge as described above. Since it has a spherical shape, the bottom surface including the valve seat 6 is nearly horizontal, and the steam exhaust path 12 is shaped to continue to the valve seat 6 as a straight pipe so as to be perpendicular to the bottom surface. , the connecting surface between the valve chamber 10 and the steam exhaust passage 12 has a cross-sectional shape bent at right angles, and the steam flow is directed to the steam exhaust passage 1.
2, and as shown in the figure, a large number of vortices are generated around the outlet of the steam exhaust passage 12, increasing the pressure loss in the valve chamber and generating vibrations and noise, especially vibrations. There were problems such as fatigue damage caused by

[Purpose of invention]

The present invention was devised in view of the above-mentioned problems, and aims to provide a steam valve that smoothes the steam flow inside the valve casing, reduces steam pressure loss, and generates less vibration and noise. .

[Key points of the idea]

According to the present invention, the above object is achieved by forming the space forming the valve chamber into a substantially spherical shape, and furthermore, making the longitudinal center line of the space coincide with the axial center lines of the valve stem and the steam exhaust passage. Further, a valve seat is provided perpendicularly to the axis center line around the point of contact between the center line and the spherical surface of the valve chamber to form an outlet section to the steam exhaust passage, and to form an outlet section for the steam exhaust passage connected to the outlet section. The cross-sectional shape of the passage is slightly constricted at the part immediately following the outlet, and after passing that part, it expands little by little to form a cylindrical shape that widens at the end. This is achieved by providing a rectifier plate extending vertically on the chamber wall surface.

[Example of idea]

Embodiments to which the present invention is applied will be described below based on the drawings. FIG. 1 is a cross-sectional view showing the internal structure of a steam valve according to an embodiment, and the same parts as those in the embodiment shown in FIG. 2 are given the same reference numerals, and explanations of duplicated explanations will be omitted.

In the figure, the shape of the valve chamber 10 forming the internal space of the valve casing 1 is spherical (the arc PQRS is 1/2
2), the upper opening of which is closed by the aforementioned valve lid 4, and the steam inflow path 11 connected to the side thereof has its axial center line aligned with the valve chamber 1.
The opening is perpendicular to the longitudinal center line at a position slightly higher than the center point O of the valve chamber 10, and its cross-sectional shape is slightly enlarged so that the connection with the valve chamber 10 is smooth. It is designed to connect to 10 spherical surfaces. The position of the valve seat 6 is the valve chamber 10.
The valve chamber is defined based on the contact point S between the longitudinal centerline of the valve body 10 and the spherical surface of the valve chamber 10, and is formed at a predetermined depth according to the diameter of the valve body 5 as a part of the outlet section of the steam exhaust passage 12, which will be described later. It is engraved on the wall of 10.

In addition, the steam strainer 3 has an upper support ring 3a and a lower support ring 3b fitted into the notch 4a of the valve lid 4 and the steam strainer seat 10a carved on the lower spherical surface of the valve chamber 10, respectively. Although it is fixedly placed vertically within the valve chamber 10, the inner circumferential surface of the lower support ring 3b is cut obliquely to form part of the connection surface between the valve chamber 10 and the valve seat 6. Valve chamber 1
0 and the valve seat 6 are arranged in a substantially straight line.

On the other hand, the steam exhaust passage 12 following the valve seat 6 narrows the outlet portion immediately following the valve seat 6 so that its cross-sectional area is smaller than the diameter of the valve body 5, and the narrowed portion 12a
The opening is formed into a cylindrical shape that widens toward the end and gradually expands after passing the valve chamber 10, and the connecting surface from the valve chamber 10 to the narrow portion is a gently curved surface.

Further, on the wall surface of the valve chamber on the opposite side of the connection between the valve chamber 10 and the steam inlet passage 11, a rectifying plate 13 made of a thin plate with a U-shaped recess in the center is installed along the longitudinal center line of the valve chamber 10. The steam strainer 3 is protruded and erected so that the longitudinal center line of the protruding surface is parallel to the steam strainer 3, and the steam that has passed through the steam strainer 3 is distributed to the left and right and guided to flow along the wall surface of the valve chamber 10. .

As explained above, the valve chamber 10 is made spherical, and the connection surfaces between the valve chamber 10 and the steam inflow passage 11 and between the valve chamber 10 and the steam discharge passage 12 are formed into a spherical surface and a circular arc, or a curved line with a straight portion in between. By smoothing the air by smoothing the air and by arranging the rectifying plate 13, the steam sent into the valve chamber 10 through the steam inflow path 11 flows along the spherical surface of the valve chamber 10 and the side wall 3c of the steam strainer 3. The flow that is guided downward through the steam exhaust passage 12 and the flow that bypasses the hanging part 4b of the valve cover 4 in the steam strainer 3 and is distributed to the left and right by the rectifying plate 13 and the flow that flows into the valve chamber 10. Steam strainer 3 is guided again by the spherical surface
The steam enters and flows through the valve chamber 10 after being sent to the steam exhaust passage 12 below, but in either case, the passage path is configured with a curve or a straight line, so there are no factors that inhibit the steam flow. The flow will be carried out smoothly.

[Effect of idea]

As explained above, according to the present invention, the shape of the valve chamber is made spherical, and the connection surfaces between the steam inflow path and the valve chamber, and between the valve chamber and the steam exhaust path are formed using straight lines or curved surfaces so as not to have any angularity. At the same time, by providing a rectifying plate and forming the shape of the steam exhaust passage into a diffuser shape, the steam flow inside the valve chamber is smoothed, and in particular, turbulence derived from the outlet between the valve chamber and the steam exhaust passage is reduced, and the In addition to reducing pressure loss, the generation of noise and vibration was also reduced, and the effect of obtaining a long-life steam valve without fatigue damage was achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the internal structure of a steam valve according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the internal structure of a conventional steam valve. DESCRIPTION OF SYMBOLS 1... Valve casing, 2... Valve stem, 3... Steam strainer, 4... Valve lid, 5... Valve body, 6... Valve seat, 10... Valve chamber, 11... Steam inflow path, 12 …
...Steam exhaust path, 13...Brightening plate, S...Contact.

Claims (1)

[Scope of utility model registration request] It is closed with a valve lid that has a space inside that forms a valve chamber, and has a through hole in the center through which a valve stem holding a valve body is guided so as to be able to rise and fall at the lower end above the space. In addition, in a steam valve having a valve casing arranged such that a steam exhaust passage communicating with the space is opened downward and a steam inflow passage is opened on one side, the shape of the space is approximately spherical. The longitudinal center line of the space is aligned with the axis center line of each of the valve stem and the steam exhaust passage, and the center is centered at the point of contact between the axis center line and the spherical surface of the space. A valve seat is provided perpendicularly to the center line of the shaft to form an outlet to the steam exhaust passage, and the cross-sectional shape of the steam exhaust passage connected to the outlet is slightly different from the portion immediately after the outlet. After passing through that part of the throttle, the valve gradually expands to form a cylindrical shape that widens at the end, and a rectifying plate that extends vertically is provided on the wall of the valve chamber on the opposite side of the connection between the valve chamber and the steam inlet pipe. A steam valve structure featuring: