JPH11141803A - Steam separator - Google Patents

Abstract

(57) [Problem] To improve the efficiency of steam-water separation in a swirling steam-water separator by preventing steam from flowing into the separated liquid. SOLUTION: The steam separator 20 has an annular downcomer space between a steam riser pipe 21 having a swirl vane provided therein and a steam riser pipe 21 provided surrounding the steam riser pipe 21. 27, and a deck plate provided with an orifice 33 that is opposed to the steam-water riser 21 and the upper end of the body 25 at a small interval and is aligned with the center of the steam- riser 21. And a turning prevention plate 37 extending vertically in the downcomer space 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam / water separator used for a steam generator, and more particularly to a structure of a steam / water separator suitably provided in a steam generator for a pressurized water reactor.

[0002]

2. Description of the Related Art A vertical steam generator generally used in a pressurized water reactor generates saturated steam for driving a turbine. A steam-water separator and a moisture separator are provided above the steam generator. The structure of the steam-water separator will be described with reference to FIGS. 3 to 5. The steam-water riser pipe 1, which is located near the liquid level in a steam generator (not shown) and extends upward, has a swirl vane 3 inside. And a centrifugal separation operation is performed by receiving a mixed flow of steam S and hot water W from the lower boiling region. As a result, the mixed flow M1 having a relatively large amount of hot water W rises while being swirled by being pressed against the inner surface of the steam rising pipe 1, and the mixed flow M2, which is almost steam S, rises at the center. A horizontal deck plate 5 is provided above the water / water riser 1, and a portion of the mixed flow M <b> 2 rises through an orifice 7 opened at the center of the water / water riser 1, and a wet (not shown) Head to the separator.

On the other hand, the mixed flow M 1 rising along the inner surface of the steam riser 1 collides with the lower surface of the deck plate 5 around the orifice 7 and then enters the downcomer space 11 surrounded by the downcomer 9. Most of the hot water W flows in the downcomer space 11 due to gravity and returns to the heating and boiling region in the steam generator. A part of the steam S of the mixed stream M2 is swirled by the mixed stream M1 and is entrained in the mixed stream M1 to enter the downcomer space 11 radially outward below the deck plate 5. Through the tangential nozzle 13 provided at the air outlet. Most of the steam-water mixture is steam S, and passes upward through a vent pipe in the deck plate 5.

[0004]

In the above-described conventional steam-water separator, the steam S as a gas is separated from the hot water W as a liquid by the separating action of the swirl vane and the tangential nozzle, and the hot water W is separated. Although it descends in the downcomer space, since the swirling flow is used for the separation action, steam is entrained in the descending hot water by the gas / water shearing force and the liquid level in the steam generator Return to the bottom. For this reason, vapor bubbles enter into the hot water above the heating boiling region, and the liquid level rises. If such a rise in the liquid level occurs rapidly, the rising flow velocity of the vapor containing the droplets increases, and the vapor rises above the base plate from the vent pipe, and as a result, the steam-water separation function may be reduced. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a steam generator steam / water separator capable of minimizing an amount of a steam component entrained by a separated hot water flow and preventing a rise in a feedwater level in the steam generator. .

[0005]

According to the present invention, there is provided, in accordance with the present invention, a steam / water riser having a swirl vane therein and a steam / water riser surrounding the steam / water riser. A downcomer which defines an annular downcomer space with the air-water riser, and which is opposed to the upper end of the air-water riser and the upper end of the downdraft at a narrow interval, and And a deck plate having an orifice aligned with the center of the downcomer space, and provided with a turning prevention plate extending vertically in the downcomer space.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIGS. 1 and 2, a steam riser 21 having a swirl vane (not shown) therein
The lower part is immersed in the liquid level 23 of the in-can supply water in the steam generator, and a downcomer 25 is provided coaxially with and surrounds the steam riser pipe 21. Lower end is steam rising pipe 21
A downcomer 25 connected to the upper surface defines an annular downcomer space 27 having an open upper portion, and has a discharge port 29 opened below the liquid level 23. Steam riser 21 and precipitation body 2
An orifice 33 having a diameter smaller than the inner diameter of the water / water riser pipe 21 is provided on the deck plate 31 which is disposed substantially horizontally at a distance d from the upper end of the pipe 5, and defines an outlet for a mixed flow mainly composed of steam. ing. An appropriate number, for example, two, of the vent pipes 35 are provided outside the precipitation drum 25 so as to penetrate the deck plate 31 in the vertical direction. Further, at the upper part of the downcomer space 27, eight turning prevention plates 37 of a predetermined height are provided in an arrangement as shown in FIG. Of course, the number and position of the turning prevention plates 37 are not limited to those shown in the figure, but can be increased, decreased, or changed as appropriate. The above-described numbers and the like are merely examples for explanation.

In the steam / water separator 20 having the above-described structure, the steam / water mixed flow generated in the heating and boiling region where the heat transfer tube bundle of the steam generator is present rises in the steam / water riser 21 and is not shown. The swirling flow is guided by the swirling vanes. Due to the centrifugal force generated by the swirling flow, the hot water portion having a large mass is pressed against the inner surface of the water / water riser pipe 21 and rises while swirling. Since the steam in the steam-water mixture flow has a relatively small mass, the centrifugal force does not increase so much and rises in the center, and rises through the orifice 33. This ascending steam flow also contains fine droplets, but the moisture is further reduced by a separately provided moisture separator or the like and guided to a steam turbine. The above-described hot water-based gas-water mixed stream A contains a considerable amount of steam, but at the entrance of the downcomer space 27, the steam-water mixed stream B having a relatively large hot water component and the steam-water mixed stream B have a relatively large steam component. The mixture is divided into a large air-water mixed flow C, and the latter flows outside the downcomer 25, enters the vent pipe 35, and flows out above the deck plate 31.

On the other hand, the air-water mixed flow B having a relatively large hot water component tends to flow down in the downcomer space 27 with a swirl velocity component, but the swirl prevention plate 37 attenuates the swirl force, Reduces shear forces acting on the air / water interface. This prevents the steam component from flowing into the steam-water mixed flow B flowing down in the downcomer space 27, and flows out from the outlet 29 into the water supply in the can as almost only a liquid portion.

[0009]

As described above, according to the present invention,
An anti-swirl plate is provided in the downcomer space defined by the steam riser and the downcomer, which reduces the swirling force of the downdraft mixed flow and reduces entrained steam.
It is possible to prevent a sudden rise in the level of the water supply in the steam generator, thereby preventing a decrease in the separation efficiency of the steam separator.

[Brief description of the drawings]

FIG. 1 is a partial vertical sectional view showing a main part of an embodiment of the present invention.

FIG. 2 is a plan sectional view taken along the line II-II in FIG.

FIG. 3 is a partially cutaway perspective view of a conventional device.

FIG. 4 is a top view of the device shown in FIG.

FIG. 5 is a sectional view taken along line VV in FIG. 4;

[Explanation of symbols]

 Reference Signs List 20 steam separator 21 steam riser 23 liquid level 25 downcomer 27 downcomer space 29 outlet 31 deck plate 33 orifice 35 vent pipe 37 rotation prevention plate

Claims (1)

[Claims] 1. A steam riser having a swirl vane provided therein, and a downcomer provided surrounding the steam riser and defining an annular downcomer space between the steam riser and the steam riser. A deck plate having an orifice opposed to the upper end of the water riser and the downcomer at a small interval and aligned with the center of the water riser, and having a vertical position in the downcomer space. A steam-water separator provided with a turning prevention plate extending in the direction.