JPS62279203A - Butterfly valve combined with elbow - Google Patents

Abstract

PURPOSE:To reduce the turbulence of steam flow at the downstream side of an elbow and to restrain pressure losses by providing a butterfly valve in close proximity to the downstream side of each elbow in a steam piping system. CONSTITUTION:Butterfly valves 1, 2 for turbine intermediate valves are provided in close proximity to the outlet part of elbows 3, 4 in a steam piping system. The valve shaft is so provided that the cross-sectional area perpendicular to the elbow axis is partioned into the inner side and the outer side portions. Further, full-open stoppers 5, 6 are provided, and each valve body is pressed against each stopper by the hydraulic force of a valve driving device. Thus, without providing a straightening member, the turbulence of steam flow at the downstream side of each elbow is reduced, and the pressure losses can be restrained.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a butterfly valve for a steam turbine, and particularly to a butterfly-type steam valve suitable for reducing pressure loss at a piping elbow. It is.

[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 lot of installation space, and that it has a large pressure loss.

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 conventionally been applied in PWR plants, and as shown in FIG. 5, a butterfly-type intermediate valve 14. 15 are provided.

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 type of rectifying means had to be provided to prevent the turbulence of the steam flow downstream of the elbow provided in the steam piping system (FIG. 6).

The present invention has been made in view of the above-mentioned circumstances, and is capable of reducing pressure loss due to turbulence in the steam flow downstream of the elbow in a steam piping system equipped with an elbow and a butterfly valve, without providing a separate rectifying means. This is an attempt to provide a butterfly valve combined with an elbow.

[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 performed by a butterfly valve.

Based on the above-mentioned principle, the present invention provides, on the downstream side of the elbow,
A butterfly valve is provided close to the elbow (at a location downstream of the elbow where there is a risk of turbulence in the steam flow).

If a butterfly valve is provided close to the elbow outlet to partition the flow path into inside and 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.

The intermediate steam stop valve 26 and the intercept valve 27 are interposed and connected between the moisture separation heater MSH and the low pressure turbine 25.

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

FIG. 3 shows the structural arrangement of the section ``■'' shown in FIG. 2.

Moisture separation heater (omitted in this figure 3, see figure 2)
and the low pressure turbine 25 is a cross-around pipe 16'.
Due to the arrangement of the equipment, elbows 3 and 4 are connected by
is necessary. Butterfly valves 1, 2 are provided adjacent to the elbow 3.4.

FIG. 1 is an explanatory diagram in which a steam flow velocity distribution vector (arrow) is added to a sectional view including Elbow 3 and 4 butterfly valves 1 and 2.

A butterfly valve 1.2 is installed close to the outlet of the elbows 3, 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.

The butterfly valves 1 and 2 for the turbine intermediate valve are used fully open during normal operation, and full-open stoppers 5 and 6 are installed to prevent the valve body from vibrating in the fully open state.
! The valve body is pressed against the fully open stopper by the hydraulic pressure (@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 valve 1.2 is installed so that the valve shaft is located between 1d from the elbow outlet to the downstream side, the butterfly valve also acts to rectify the steam flow, reducing pressure loss and improving thermal efficiency. The effect of improvement can be obtained.

〔Effect of the invention〕

As described in detail above, when the present invention is applied, the elbow can be adjusted by appropriately arranging the relative position between the elbow and the butterfly valve, which are the original constituent members, without adding a separate rectifying member. This has an excellent practical effect of reducing turbulence in the downstream steam material and suppressing pressure loss.

[Brief explanation of the drawing]

11th i! Figures 1 through 3 show an embodiment of the present invention, with Figure 1 being a vertical sectional view of the main parts, Figure 2 being a steam system diagram, and Figure 3 being 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... Fully open stopper.

Claims (1)

[Scope of Claims] 1. In a steam piping system provided with an elbow and a butterfly valve, a butterfly valve is provided close to the downstream side of the elbow at a location corresponding to a turbulent region of steam flow occurring downstream of the elbow. A butterfly valve combined with an elbow. 2. 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 item 1. 3. A butterfly valve combined with an elbow, characterized in that 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.