JP3758838B2 - Steam separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steam / water separator used in a steam generator, and more particularly to a structure of a steam / water separator suitable for being provided in a steam generator for a pressurized water reactor.
[0002]
[Prior art]
A vertical steam generator generally used in a pressurized water reactor generates saturated steam for driving a turbine, and a steam 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 that extends in the vicinity of the liquid surface in the steam generator (not shown) extends to the inside of the swirl vane 3. And receiving a mixed flow M of the steam S and hot water W from the lower boiling region and performing a centrifugal separation operation. As a result, the mixed flow M1 with a relatively large amount of hot water W is pressed against the inner surface of the steam riser 1 and rises while swirling, and the mixed flow M2 that is almost steam S rises in the center. A horizontal deck plate 5 is provided above the air / water riser 1, and the portion of the mixed flow M <b> 2 rises through an orifice 7 opened at the center of the air / water riser 1, and the moisture (not shown) Head to the separator.
[0003]
On the other hand, the mixed flow M1 rising along the inner surface of the air-water riser 1 collides with the lower surface of the deck plate 5 around the orifice 7, and then flows into the downcomer space 11 surrounded by the precipitation cylinder 9, Most of the hot water W falls in the downcomer space 11 due to gravity and returns to the heated boiling region in the steam generator. A part of the steam S of the mixed flow M2 receives a swirling force, so that it is entangled in the mixed flow M1 and enters the downcomer space 11 radially below the deck plate 5. It flows out as an air-water mixed flow through a tangential nozzle 13 provided in the air. Most of the air-water mixed flow is steam S, and goes upward through a vent pipe in the deck plate 5.
[0004]
[Problems to be solved by the invention]
In the conventional steam-water separator described above, the vapor S, which is a gas, is separated from the hot water W, which is a liquid, by the separation action of the swirl vane and the tangential nozzle, and the hot water W descends in the downcomer space. However, since the swirl flow is used for the separation action, the steam is entrained in the descending hot water by the gas / water shearing force and returns to the level below the liquid level in the steam generator. For this reason, a vapor bubble enters into the hot water in the upper part of a heating boiling region, and raises a liquid level. When such a rise in the liquid level occurs abruptly, the rising speed of the vapor containing the droplets increases, and there is a possibility that the steam and water separation function may be lowered as a result of blowing up from the vent pipe above the base plate.
In addition, when a large amount of mixed water flows into the steam riser pipe of the steam separator due to overload or boiling feed water flow in the steam generator, hot water rises over the orifice, Separation function may be reduced.
Accordingly, an object of the present invention is to provide a steam / water separator that can prevent the wake of steam from being separated into the separated hot water and that maintains the steam / water separation function even during overloading.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, according to the present invention, an air / water separator includes an air / water riser pipe having a swirl vane provided therein, and the air / water riser pipe provided around the air / water riser pipe. And an orifice that is opposed to the upper end of the air riser pipe and the upper part of the precipitation cylinder with a small gap and that is aligned with the center of the air riser pipe. A deck plate provided with a rotation preventing plate extending in the vertical direction in the downcomer space, and a vent pipe penetrating through the deck plate at a position radially outward of the precipitation cylinder, on the upper side of the orifice has a separate orifice which is fixed and supported on the ceiling wall so as to align the top of the orifice, an inner diameter larger than the orifice and the inner diameter of the orifice of said another, said further orifice and before A cylindrical portion disposed between the orifices, by separating the upper end of the cylindrical portion from the lower surface of the ceiling wall and separating the lower end from the upper surface of the deck plate, between the cylindrical portion and the ceiling wall, In addition, an air-water separation box that defines a flow path is provided between the tubular portion and the deck plate .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
Referring to FIGS. 1 and 2, a plurality of, for example, 18 to 20, steam / water separators 20 are usually provided in one steam generator. The lower part extends into the water supply in the steam generator, but the inside is provided with a swirl vane 23 to receive the rising air-water mixed flow (consisting of steam S and hot water W). . A precipitation cylinder 25 is provided so as to surround the air / water riser 21, and an annular downcomer space 27 is defined between the precipitation cylinder 25 and the air / water riser 21. In the upper part of the downcomer space 27, a turning prevention plate 29 is disposed at equal intervals in the circumferential direction, particularly as shown in FIG. Through the water supply space in the steam generator. A deck plate 33 is horizontally provided above the precipitation cylinder 25 and the air riser pipe 21 so as to cover the downcomer space 27. The deck plate 33 is aligned with the water riser pipe 21 and has a smaller inner diameter. An orifice 35 is provided through the deck plate 21. The vent pipe 37 penetrating the deck plate 33 is located on the radially outer side of the precipitation drum 25, and the lower end inlet thereof is located below the upper end of the precipitation drum 25. In addition, the drain pipe 45 is supported on the deck plate 33 so as to be separated from the precipitation cylinder 25, and a drain hole 47 is provided.
[0007]
A slot 39 is formed at the end of the precipitation drum 25 on the deck plate 33 side, and an inner rod 41 is fixed to the lower surface of the deck plate 33 so as to cover the front surface of the slot 39. Further, a steam / water separation box 50 is provided above the orifice 35 by a connection fitting 43 erected on the upper surface of the deck plate 33.
The detailed structure of the steam-water separation box 50 will be described. An orifice 51 aligned with the cylindrical orifice 35 is fixedly supported on a disk-like ceiling wall 53, and a side wall 55 is formed on the outer periphery of the ceiling wall 53 so as to hang down. . A cylinder 59 is supported by a connection fitting 57 that hangs downward from the ceiling wall 53. The inner diameter of the cylinder 59 is larger than the inner diameters of the cylindrical orifice 35 and the orifice 51, and the upper end thereof is separated from the lower surface of the ceiling wall 53, and a flow path is formed between them.
[0008]
In the steam / water separator 20 having the above-described configuration, the steam / water mixed flow (consisting of the steam S and the hot water W) is swirled by the swirl vane 23, and the hot water having a large specific gravity is 21 is pushed into the liquid film flow, rises, flows into the downcomer space 27 as indicated by the solid arrow, falls and returns to the water supply in the steam generator from the discharge port 31. At that time, the vapor component entrained in the liquid film flow flows outwardly through the slot 39 of the precipitation cylinder 25 and flows out of the deck plate 33 through the vent pipe 37 as indicated by the white arrow. . Most of the steam component of the gas-water mixed flow is small in mass, so that the swirl vane 23 does not give a swirl motion, but rises straight and flows through the cylindrical orifice 35 and the orifice 51 of the steam-water separation box 50. Then rise.
[0009]
Thus, when the rising feed water flow generated in the steam generator is biased or the ratio of the hot water component of the steam-water mixed flow rising into the steam-water riser pipe 21 due to overload increases. The liquid film flow generated by the swirl vane 23 overflows and enters the cylindrical orifice 35. In this state, the separated liquid membrane flow rises along the inner surface, but since centrifugal force is acting, first, it climbs over the upper end of the cylindrical orifice 35, collides with the inner surface of the inner cylinder 59, and is shown by a filled arrow. Falls onto the top surface of the deck plate 33. Further, the liquid film flow over the upper end of the inner cylinder 59 collides with the inner surface of the side wall 55 and similarly falls on the deck plate 33. As described above, the hot water dropped on the deck plate 33 returns to the lower water supply space through the drain hole 47 and the drain pipe 45. In addition, the vapor component which was wake up at the time of collision of the liquid film flow is separated and rises.
[0010]
【The invention's effect】
As described above, according to the present invention, the entrained steam is removed by the swirl prevention plate from the hot water-based gas-water mixed flow that is separated and flows through the downcomer space, and only the hot water is returned downward to the liquid level. Variations can be suppressed. Furthermore, even if there is a relatively large amount of hot water flowing into the air / water riser due to overloading etc., hot water and steam are separated by the collision action in the air / water separation box. Can be maintained.
[Brief description of the drawings]
FIG. 1 is an elevational sectional view showing a main part of an embodiment of the present invention.
2 is a plan sectional view taken along line II-II in FIG.
FIG. 3 is a partially cutaway perspective view of a conventional device.
4 is a top view of the apparatus shown in FIG.
5 is a cross-sectional view taken along line VV in FIG.
[Explanation of symbols]
20 Steam separator 21 Steam water riser pipe 23 Swivel vane 25 Precipitation drum 27 Downcomer space 29 Swivel prevention plate 31 Drain port 33 Deck plate 35 Orifice 37 Vent pipe 39 Slot 41 Inner flange 43 Connection fitting 45 Drain pipe 47 Drain hole 50 Air-water separation box 51 Orifice 53 Ceiling wall 55 Side wall 57 Connection fitting 59 Inner cylinder

Claims (1)

The air-water mixed flow introduced into the cylindrical riser is centrifuged, and the separated water is a gap provided between the lower surface of the deck plate disposed above the riser and the upper end of the riser. To the downcomer space formed annularly between the outer peripheral surface of the riser and the inner peripheral surface of the precipitation cylinder coaxially disposed on the outer periphery of the riser, while the separated steam is discharged to the deck plate In the steam separator which is discharged to the outside through an orifice formed as a steam outlet,
A rotation preventing plate extending vertically in the downcomer space;
A vent pipe penetrating into the deck plate at a position radially outward of the raindrop,
An air-water separation box disposed on the upper portion of the orifice of the deck plate disposed on the upper surface of the riser ;
The steam-water separation box includes another orifice fixedly supported on the ceiling wall so as to align above the orifice;
The other orifice and an inner diameter larger than the inner diameter of the orifice, the another orifice and a cylindrical portion disposed between the orifices,
By separating the upper end of the tubular portion from the lower surface of the ceiling wall and separating the lower end of the tubular portion from the upper surface of the deck plate, the tubular portion and the ceiling wall, and the tubular portion and the A steam separator that defines each flow path between deck plates .

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