JPH0457841B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a butterfly valve for a steam turbine, and more particularly to a butterfly-type steam valve suitable for reducing pressure loss at an elbow portion of a pipe.

[Conventional technology]

Regarding a combination type valve installed in a steam piping system of a steam turbine, a technique described in Japanese Patent Application Laid-open No. 1304/1983 is known.

In a conventional BWR nuclear power turbine, a combination intermediate valve 11 as shown in FIG. 4 has been used. The combination intermediate valve 11 of this conventional example is interposed and connected to piping on the upstream side of the low pressure turbine 12. 13
is a pedestal.

The steam valve of the type shown in the conventional example (FIG. 4) has problems in that it is large and requires a large amount of installation space, and that the pressure loss is large.

For this reason, butterfly type intermediate valves have come to be used. In this case, in the prior art, no particular consideration was given to the arrangement of the elbow of the piping system and the butterfly valve. Butterfly-type intermediate valves have traditionally been used in PWR plants, but as shown in FIG. ing.

That is, conventional valves are generally arranged to avoid drifting of the flow at the elbow.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, no particular consideration was given to the pressure loss at the elbow portion of the piping, and there was a problem in terms of thermal efficiency.

The steam flow at the elbow of the pipe is biased as shown in FIG. 6, and a swirling flow also occurs in the circumferential direction. This causes pressure loss.

In the prior art, some sort of rectifying means had to be provided to prevent the turbulence of the steam flow (FIG. 6) occurring downstream of the elbow provided in the steam piping system.

The present invention was made in view of the above circumstances, and
To provide a butterfly valve combined with an elbow that can reduce pressure loss due to turbulence of steam flow downstream of the elbow without providing a separate rectifying means in a steam piping system provided with an elbow and a butterfly valve.

[Means for solving problems]

In the prior art, a steam guide was provided on the downstream side of the elbow to rectify the flow and prevent pressure loss due to turbulence in the steam flow, but in the present invention, the role of the steam guide is fulfilled by a butterfly valve. Close.

Based on the above-mentioned principle, the present invention provides a butterfly valve on the downstream side of the elbow, in close proximity to the elbow (corresponding to an area where there is a possibility of turbulence of steam flow downstream of the elbow).

If a butterfly valve is provided close to the elbow outlet to partition the flow path into an inside and an outside, the steam flow will be rectified and pressure loss will be reduced.

In order to prevent the vibration of the valve body of the butterfly valve, it is desirable to provide a fully open stopper and press the valve body against the stopper using hydraulic pressure to prevent vibration caused by the steam flow.

〔Example〕

Next, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 2 shows the overall configuration of a steam system to which this example is applied.

Intermediate steam stop valve 26 and intercept valve 27
is interposedly connected between the moisture separation heater MSH and the low pressure turbine 25.

In this example, the intermediate steam stop valve 26 and the intercept valve 27 are configured with butterfly valves.

FIG. 3 shows the structural arrangement of the parts shown in FIG. 2. The moisture separation heater (omitted in Fig. 3, see Fig. 2) and the low pressure turbine 25 are connected by a cross-around pipe 16', and elbows 3 and 4 are required due to the arrangement of the equipment. be. Butterfly valves 1 and 2 are provided adjacent to the elbows 3 and 4.

Figure 1 shows elbows 3 and 4 and butterfly valves 1 and 2.
FIG. 2 is an explanatory diagram in which a flow velocity distribution vector (arrow) of a steam flow is added to a cross-sectional view including the above.

Butterfly valves 1 and 2 are installed close to the outlet portions of elbows 3 and 4. The valve stem is provided so as to divide the cross section perpendicular to the elbow axis into an inner side and an outer side.

These butterfly valves 1 and 2 for turbine intermediate valves are
During normal operation, the valve is fully open, and in order to prevent the valve body from vibrating in the fully open state, full-open stoppers 5 and 6 are provided, and the valve body is pressed against the full-open stopper by the hydraulic pressure of a bypass valve driving device (not shown).

If no special measures are taken, the steam flow downstream from the elbows 3 and 4 will be disturbed by drifting and swirling, resulting in pressure loss, as shown in FIG.

The turbulence in the steam flow at the elbow outlet is greatest in a range of 1 d from the elbow outlet to the downstream side, where d is the inner diameter of the pipe.

Therefore, if the butterfly valves 1 and 2 are installed so that the valve shafts are positioned between 1d from the elbow outlet to the downstream side, the butterfly valves also perform a steam flow rectification function, reducing pressure loss and improving thermal efficiency. This has the effect of improving.

〔Effect of the invention〕

As described in detail above, when the present invention is applied, the elbow can be downstream of the This has an excellent practical effect of reducing turbulence in the steam flow and suppressing pressure loss.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention,
FIG. 1 is a vertical sectional view of the main parts, FIG. 2 is a steam system diagram, and FIG. 3 is a structural layout diagram. FIG. 4 is an explanatory diagram of a conventional combination intermediate valve, FIG. 5 is an explanatory diagram of a conventional butterfly valve type intermediate valve, and FIG. 6 is an explanatory diagram of steam flow downstream of an elbow. 1, 2... Butterfly valve, 3, 4... Elbow,
5, 6... Full stop.

Claims (1)

[Scope of Claims] 1. In a steam piping system provided with an elbow and a butterfly valve, the valve is placed close to the downstream side of the elbow,
A butterfly valve combined with an elbow, characterized in that the butterfly valve is provided at a location corresponding to the turbulent region of steam flow that occurs downstream of the elbow. 2. Claim 1, characterized in that the valve shaft of the butterfly valve is provided in a direction perpendicular to a plane including the center line of the elbow and perpendicular to the center line near the outlet of the elbow. A butterfly valve combined with an elbow, as described in section. 3. A butterfly combined with an elbow according to claim 1, wherein the inner diameter of the steam piping system is d, and the distance between the outlet of the elbow and the butterfly valve shaft is smaller than d. valve.