JPH0315892Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention particularly relates to a valve used for controlling the flow rate of high-temperature, high-pressure steam, air, and the like. [Prior Art] Flow control valves for high-temperature, high-pressure gases are often used in piping systems of thermal power plants, etc., but regular valves generate a lot of noise when gas passes through the valve section at high speed, so Valves with low-noise measures are commonly used. Fig. 3 is a vertical cross-sectional view of a conventional flow control valve, Fig. 4 is an external view of the valve stem, Fig. 5 is a cross-sectional view of the valve stem, and Figs. 6 and 7 are explanations of the flow in the groove. It is a diagram. In FIG. 3, 1 is a valve body, and 2 is a valve stem, both ends of which are supported by sleeves 6, 6' of the valve body 1. 3 is an intermediate support portion of the valve stem 2, and 4 is a valve seat, which is integrated with the intermediate support portion 3. A porous cylinder 5 is fitted into the lower end of the valve seat 4 and surrounds the lower part of the valve stem 2. In FIGS. 4 and 5, 7,
8 and 9 are grooves through which gas passes, and 7 is 3.
Among the seed grooves, the large groove is the largest in terms of width, length, and depth, 8 is the medium groove, and 9 is the small groove, each of which is provided in several grooves around the circumference of the valve stem 2. 10 is a valve seat.

Figure 3 shows the flow in the entire valve, Figure 6 shows the flow in the large groove and medium groove when the flow control valve is slightly open, and Figure 7 shows the flow in the same small groove. ing. In Figure 3, gas is indicated by arrow A.
It flows into the valve in the direction of arrow B, passes through the groove of the valve stem in the direction of arrow B, flows out in the direction of arrow C, passes through the perforated cylinder 5, and is discharged in the direction of arrow D. At this time, the flow of gas at the groove end of the valve stem is shown in FIG. 6, but the large groove 7 and the middle groove 8 are open and the gas freely flows out. However, as shown in FIG. 7, the small groove 9 has not opened yet, and gas leaks from the gap between the valve seat portion 4 and the small groove 9, becomes a jet stream, and is blown onto the valve seat. Since this gap is usually small, 0.2 to 0.4 mm, the amount of leakage from the gap is small, but since the pressure difference between the small groove 9 and the valve stem outlet is large, the flow velocity of the ejected gas is close to the speed of sound. Furthermore, since the flow velocity of the gas ejected from the large groove 7 and the medium groove 8 is close to the speed of sound, a perforated cylinder 5 is installed downstream thereof to reduce the flow noise by a resonance damping method.

[Problem that the invention attempts to solve]

The conventional flow control valve as described above has the following problems. In other words, when the valve stem is slightly opened, the small groove 9
The accumulated gas flows through the gap between the valve stem 2 and the valve seat portion 4 and hits the valve seat seat 10 as a jet stream. For this reason, when small scales or droplets flow into the small groove 9, they are blown onto the valve seat seat 10 by the jet stream through the gap described above, and the valve seat seat 10
damage 10' occurs in actual plants. Due to this damage to the valve seat 10,
There is a problem in that gas leaks from the damaged area when the valve is fully closed, resulting in a loss of sealing performance.

[Means for solving problems]

The flow control valve according to the present invention aims to solve the above problems, and includes a cylindrical valve seat held within the valve body, and a valve fitted within the valve seat so as to be movable coaxially with the valve seat. The valve seat includes a rod and a valve seat seat which is located downstream of the valve seat outlet and is formed in the shape of a flange on the outer periphery of the valve stem and has a larger diameter than the inner diameter of the valve seat outlet, and the valve seat is closed by the engagement of the valve seat and the valve seat seat. In a valve that controls the flow rate of gas passing through the seat, a plurality of grooves are carved in the axial direction on the outer periphery of the valve stem upstream of the valve seat, all of which extend in the same vicinity to the valve seat. Features a composition.

[Effect]

In other words, the multiple axial grooves provided on the valve stem are extended in the same way to the very vicinity of the valve seat, so even when the valve is slightly opened, all the grooves remain close to the valve seat regardless of their size. Opens downstream.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to an embodiment of the present invention shown in Figs. 1 and 2. Items with the same reference numerals as in Figs. 3 to 7 have the same structure and function, and will therefore be explained. omitted. FIG. 1 is an external view of a valve stem of a flow control valve according to an embodiment of the present invention, and FIG.
The figure is a longitudinal sectional view of FIG. 1.

In FIG. 1, 21 is a medium groove, and 22 is a small groove, and these grooves have the same length in the axial direction of the valve stem as the length of the large groove 7, and extend as far as the valve seat seat 10.

Therefore, as shown in FIG. 2, even when the valve is slightly opened, the downstream ends of the large groove 7, medium groove 21, and small groove 22 are open downstream from the valve seat 4. Therefore, the gas flows out from each groove in the direction of arrow E in FIG. 2, so there is no jet flow toward the valve seat seat 10, and even if scale and droplets are mixed in the gas, the valve seat seat 10 will not be damaged. can be avoided.

[Effect of idea]

The flow control valve according to the present invention has a groove for a gas flow path provided in the valve stem, which has approximately the same length for the large groove, medium groove, and small groove, and extends to the very vicinity of the valve seat, thereby controlling the flow rate. Even when the valve is slightly opened, no gas jet is generated from the minute gap between the valve stem and valve seat, which prevents damage to the valve seat surface due to scale spray.
Valve sealing performance can be ensured.

[Brief explanation of drawings]

Fig. 1 is an external view of a valve stem of a flow control valve according to an embodiment of the present invention, Fig. 2 is a vertical sectional view of Fig. 1, and Fig.
The figure is a vertical cross-sectional view of a conventional flow control valve, Figure 4 is an external view of the valve stem, Figure 5 is a cross-sectional view of Figure 4, and Figure 6 is a cross-sectional view of the conventional flow control valve.
FIG. 7 and FIG. 7 are explanatory diagrams of the flow in the groove. 1... Valve body, 2... Valve stem, 4... Valve seat, 7...
...Large groove, 10...Valve seat seat, 21...Middle groove, 2
2...Small groove.

Claims (1)

[Scope of utility model registration request] A cylindrical valve seat held within the valve body, a valve stem movably mounted within the valve seat coaxially with the valve seat, and a valve seat outlet inner diameter located downstream of the valve seat outlet and attached to the outer periphery of the valve stem. In a valve comprising a valve seat formed in the shape of a brim with a diameter larger than that of the valve seat, the valve seat of the valve stem controls the flow rate of gas passing through the valve seat by engagement between the valve seat and the valve seat. A flow control valve characterized in that a plurality of grooves are carved in the outer periphery of the upstream side in the axial direction, all of which extend to the same vicinity with respect to the valve seat.