JPH038433B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high differential pressure control valve suitable for use in a startup bypass system of a commercial boiler, etc.

[Prior Art] High differential pressure control valves are used in startup bypass systems and the like of commercial boilers. This high differential pressure control valve is
In particular, as typified by heater bypass valves, when starting up a boiler, the flow rate and pressure of a wide range of ultra-high-temperature, high-pressure fluids, from high-pressure cold water to sub-critical or supercritical pressure steam through a temperature and pressure raising process, are controlled. ,moreover,
During normal operation of the boiler, it is also required to function as a stop valve to shut off the main steam pipe system on the high-pressure side of the boiler and the flash tank or condenser side on the low-pressure side, and is therefore exposed to extremely harsh operating conditions. It is something that can be done.

By the way, startup bypass valves that have been widely used for many years are generally variable throttle valves as shown in Fig. 4, in which fluid flows into the valve chamber 2 from the inlet channel 1 on the side of the valve, and It has a so-called flow-to-close type angle valve structure in which the flow rate and pressure are controlled in the throttle section 3 inside the chamber 2, and the jet stream is then discharged from the outlet passage 4 below. Therefore, the valve casing 5 is small and simple, has a thin wall thickness, and has a shape that is favorable in terms of thermal stress.It also has high erosion resistance due to its flow direction, and also has reliable valve closing performance due to the fluid primary pressure. ing.

[Problems to be Solved by the Invention] However, when high-pressure cold water is controlled by a high differential pressure regulating valve such as in the conventional start-up bypass valve, a water vaporization phenomenon occurs immediately below the throttle part.
Extremely unstable cavities that have grown considerably locally appear and disappear instantaneously, resulting in intense cavitation vibrations. For this reason, the current situation is to strengthen the support for the valve outlet piping, or to surround the valve with vibration and soundproof walls.

In addition, in order to reduce the cavitation vibration mentioned above,
Devices that provide high resistance to fluid through a narrow winding labyrinth as described in Japanese Patent Publication No. 48-25333, and multi-stage decompression orifice type control devices as described in Japanese Patent Application Publication No. 47-2480. is proposed. However, although each of these devices can reduce cavitation vibration, the loss in the control section is very large and the fluid itself has difficulty flowing, so in order to control the same amount of fluid, It is necessary to increase the size of the valve itself. Therefore, the valve casing becomes thicker, which is unfavorable in terms of thermal stress for start-up bypass valves, etc., which are subject to frequent temperature changes.Furthermore, due to its complicated structure, manufacturing of the valve is extremely difficult and maintenance is difficult. It is not easy to use, and is not suitable for high differential pressure control valves such as starting bypass valves that involve frequent starting and stopping.

The present invention provides high differential pressure control that allows the valve casing to be small and simple in shape, greatly reduces the occurrence of severe vibrations during control, and provides a reliable shut-off state with no leaks when the valve is fully closed. The purpose is to provide a valve.

[Means for Solving the Problems] The present invention includes a casing including an inlet flow path, an outlet flow path, and a valve chamber, a valve seat supported by the casing, and a valve seat formed in the valve chamber of the casing. In a high differential pressure regulating valve, the valve body is movable in a direction toward and away from a valve seat, and a seat surface provided on the valve body is moved toward and away from the valve seat. , a cage is provided coaxially around the valve body, a small hole is bored in the cage through which a fluid flow line forms a downward outflow angle, and an upper part of the seat surface of the valve body is provided with a cage that forms a downward outflow angle of the fluid streamline. A jet guide surface is formed to project downward toward the inner surface of the cage and guide the fluid jet flowing out from the small hole downward, and a concave surface is formed at the lower part of the seat surface of the valve element toward the valve center axis side from the seat surface. A rectifying surface is formed that protrudes in a reduced diameter state to form a shape, and guides the fluid flowing out from the small hole and guided to the jet flow guide surface toward the exit side of the outlet flow path. It is.

[Operation] According to the present invention, the flow rate of the fluid flowing into the valve casing is controlled in the small hole of the cage that is not blocked by the valve body, and the jet direction from the small hole is controlled by the action of the jet flow guide surface. The liquid is bent downward from the horizontal, does not hit the seat surface of the valve body, and furthermore, a smooth flow is formed along the rectifying surface and is discharged to the outlet flow path side. That is, in the present invention, even if water vaporizes directly under the small hole of the cage, it is diffused by the small hole, and the inclination angle of the small hole, the jet flow guide surface of the valve body, and the rectifying surface Because it is smoothly discharged downward,
Very short period cavity growth phenomenon, which is the cause of severe cavitation vibration, does not occur. This makes it possible to significantly reduce severe vibrations during control.

In addition, even if cavitation occurs due to local fluid vaporization, if the volume of the fluid is not restricted so that it is ejected from a small hole, if the structure is such that the jet does not hit the object directly, erosion will not occur. The results of various erosion tests have already shown that this can be almost avoided. Therefore, according to the structure of the present invention, the jet flow is prevented from directly hitting the seat surface by the inclination angle of the small hole provided in the cage and the action of the jet flow guide surface provided in the valve body. The seat surface is less likely to be damaged, and it is possible to obtain a reliable shut-off state without leakage when the valve is fully closed.

[Embodiment] FIG. 1 is a cross-sectional view showing a high differential pressure regulating valve 10 according to an example of the present invention, and FIG. 2 is a cross-sectional view showing a main part of FIG. 1.

The high differential pressure regulating valve 10 includes a casing 1 that includes an inlet flow path 11, an outlet flow path 12, and a valve chamber 13.
It has 4. An upper valve body guide 15 and a lower valve body guide 16 are fixedly arranged in the casing 14 . The lower valve body guide 16 includes a valve seat 17 that connects the inlet flow path 11 and the outlet flow path 12. The upper valve body guide 15 and the lower valve body guide 16 slidably support a valve body 19 that is integrated with the valve rod 18 . Valve body 1
9 is provided opposite to the valve seat 17 and moves upward from the valve seat 17 to bring the seat surface 20 provided on the valve body 19 into contact with and away from the valve seat 17. There is.

A portion of the lower valve body guide 16 that slidably supports the valve body 19 is a cylindrical inner cage 21 . Further, a portion of the upper valve body guide 15 that is continuous below the portion that slidably supports the valve body 19 is a cylindrical outer cage that is coaxially arranged around the inner cage 21 via an annular flow path 22. It is said to be 23.

The outer cage 23 includes a valve chamber 13 from the inlet flow path 11.
A large number of small holes 24 are provided to guide the fluid flowing into the annular flow path 22 . The small holes 24 can rectify the flow of fluid toward the inner cage 21 with the fluid ejecting direction being in the horizontal direction.

The inner cage 21 is also provided with a large number of small holes 25. This small hole 25 is opened and closed by the valve body 19, and in its open state, allows fluid flowing into the annular flow path 22 to be guided to the outlet flow path 12.
The small hole 25 is given an inclination angle state such that the streamline of the fluid is ejected with an outflow angle having a downward slope with respect to the central axis of the valve.

Further, a jet flow guide surface 26 is formed on the upper part of the seat surface 20 of the valve body 19 in a state that protrudes from the seat surface 20 toward the inner surface side of the inner cage 21 and guides the jet flow flowing out from the small hole 25 downward. has been done.

Further, in the lower part of the seat surface 20 of the valve body 19, a small hole 25 is formed in a concave shape and has a diameter reduced toward the valve center axis side from the seat surface 20, and protrudes downward.
A rectifying surface 27 is formed to smoothly guide the fluid flowing out from the jet flow guide surface 26 toward the exit side of the outlet flow path 12 .

The entire surface of the valve body 19 is reinforced with a hardened metal material such as Stellite.

Next, the operation of the above embodiment will be explained.

According to the above embodiment, the fluid flowing into the inside of the casing 14 and rectified by the many small holes 24 of the outer cage 23 flows through the small holes 24 of the inner cage 21 that are not closed by the valve body 19. At the same time, the flow rate is controlled by the action of the jet guide surface 26, and the jet direction from the small hole 25 is bent from horizontal to the downward outlet flow path direction, and the seat surface 20 of the valve body 19
It never hits. This fluid further contains the valve body 1
A smooth flow is formed along a concave rectifying surface 27 provided at the lower part of the sheet surface 20 at 9, and the fluid is discharged toward the exit side of the outlet channel 12. That is, in the above embodiment, even if water evaporates directly under the small holes 25 provided in the inner cage 21, it is diffused by the small holes 25 and the water vaporized directly below the small holes 25 provided in the inner cage 21 is dispersed by the small holes 25. Due to the inclined angle and the jet guide surface 26, the air is smoothly discharged downward, so that very short-period cavity growth phenomenon, which is the cause of severe cavitation vibration, does not occur. This makes it possible to significantly reduce severe vibrations during control.

Furthermore, even if cavitation occurs due to local vaporization of the fluid, if the volume of the fluid is not restricted so that it is ejected from the small holes 25, if the structure is such that the jet does not hit the object directly, erosion may occur. The results of various erosion tests have already shown that this can be largely avoided. Therefore, due to the inclination angle of the small hole 25 provided in the inner cage 21 and the action of the jet flow guide surface 26 provided in the valve body 19, the jet flow is prevented from directly hitting the seat surface 20. According to the structure of the embodiment, the seat surface 20 is not easily damaged, and it is possible to obtain a reliable closing state without leakage when the valve is fully closed.

In addition, since the surface of the valve body 19 is reinforced with a hardened metal material such as Stellite, the jet guide surface 26 and the rectifying surface 27 along which the jet flow from the small hole 25 flows will not be easily eroded.

FIG. 3 is a diagram showing the effect of the present invention. Third
In the figure, the horizontal axis shows the differential pressure index √△1 (P1: fluid pressure on the inlet side, △P: the difference between the fluid pressure on the inlet side and the fluid pressure on the outlet side), and the vertical axis shows the flow rate Q, noise level N, Vibration level V (Vx: x-direction vibration level,
Vy: y-direction vibration level, Vz: z-direction vibration level). The solid line shows the results according to the present invention, and the broken line shows the results according to the conventional example. This third
According to the figure, it is recognized that noise and vibration can be significantly reduced without substantially reducing the flow rate under the same differential pressure condition, especially at intermediate valve openings during high-pressure cold water control.

[Effects of the Invention] As described above, the present invention includes a casing that includes an inlet flow path, an outlet flow path, and a valve chamber, a valve seat that is supported by the casing, and that is formed in the valve chamber of the casing. In a high differential pressure regulating valve, the valve body is movable in a direction toward and away from a valve seat, and a seat surface provided on the valve body is moved toward and away from the valve seat. , a cage is provided coaxially around the valve body, a small hole is bored in the cage through which a fluid flow line forms a downward outflow angle, and an upper part of the seat surface of the valve body is provided with a cage that forms a downward outflow angle of the fluid streamline. A jet guide surface is formed in a state that protrudes more toward the inner surface of the cage and guides the fluid jet flowing out from the small hole downward, and at the lower part of the seat surface of the valve body,
A rectifier that protrudes from the seat surface toward the valve center axis in a concave shape with a reduced diameter, and guides the fluid flowing out from the small hole and guided to the jet flow guide surface toward the exit side of the outlet flow path. It is designed so that a surface is formed.

Therefore, the severe vibration during control can be significantly reduced while keeping the valve casing shape small and simple.
Moreover, when fully closed, it is possible to obtain a reliable shut-off state with no leaks.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a high differential pressure regulating valve according to an embodiment of the present invention, FIG. 2 is a sectional view showing the main parts of FIG. 1, and FIG. 3 is a line showing the effects of the present invention. figure,
FIG. 4 is a sectional view showing a conventional control valve. 10... High differential pressure control valve, 14... Casing,
17... Valve seat, 19... Valve body, 20... Seat surface, 21... Inner cage, 25... Small hole, 26...
Jet guide surface.

Claims (1)

[Claims] 1. A casing including an inlet flow path, an outlet flow path, and a valve chamber, a valve seat formed in the valve chamber of the casing, and a valve seat supported by the casing and movable in the direction toward and away from the valve seat within the valve chamber of the casing. In a high differential pressure regulating valve, the valve body has a valve body, and a seat surface provided on the valve body is moved toward and away from the valve seat, and a cage is provided coaxially around the valve body. The cage is provided with a small hole through which the fluid flow line forms a downward outflow angle, and the small hole is formed in the upper part of the seat surface of the valve body in such a manner that it protrudes from the seat surface toward the inner surface of the cage. A jet guide surface is formed to guide the fluid jet flowing out from the valve body downward, and a jet guide surface is formed at the lower part of the seat surface of the valve body in a concave diameter state and protrudes from the seat surface toward the center axis of the valve. A high differential pressure regulating valve characterized in that a rectifying surface is formed to guide the fluid flowing out from the hole and guided to the jet flow guide surface toward the exit side of the outlet flow path.