JPH07209132A - Steam generator - Google Patents

Abstract

(57) [Abstract] [Purpose] Even in a steam generator that employs acoustic detection means, this type of steam is highly safe because the component loss signal can be promptly detected as a sufficient signal with little attenuation. Provide a generator. A waveguide 18 is provided on the inner wall of the body 2 at or near the position where the acoustic sensor 14 is installed, for connecting the body and the outer cylinder 5 arranged in the body. did.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved steam generator, and more particularly to a steam generator suitable for a liquid metal fast breeder reactor.

[0002]

2. Description of the Related Art Generally, a helical coil type steam generator has been generally used in a fast breeder reactor. FIG. 7 shows an example of the large helical coil steam generator.

In the figure, reference numeral 1 denotes a helical coil type steam generator, which is provided on a heating barrel 2, a sodium inlet nozzle 3 provided on the upper portion of the barrel 2, and a lower portion of the barrel 2. A sodium outlet nozzle 8 and a helical coil tube bundle portion 7 formed by winding a plurality of heat transfer tubes 6 in a helical coil inside the body portion.

In the steam generator thus formed, high-temperature liquid metal sodium, which is a heating medium (fluid in the body), flows into the body 2 of the steam generator 1 from the upper sodium inlet nozzle 3. This sodium descends outside the helical coil tube bundle portion 7 provided in the annulus space surrounded by the cylindrical inner cylinder 4 and the outer cylinder 5, and flows out of the body portion 2 from the sodium outlet nozzle 8.

On the other hand, the water that becomes steam flows into the water supply inlet chamber 10 from the water supply inlet nozzle 9 provided below the body portion 2, is guided into the plurality of heat transfer tubes 6, and rises in the helical coil tube bundle portion 7. To do. At this time, the water flowing in at a low temperature is transferred to the heat transfer tube 6
Heat exchange with high temperature sodium flowing outside, preheating, boiling,
It is overheated and becomes high-temperature and high-pressure superheated steam. Steam outlet water chamber 1
To 1. The superheated steam is sent from the steam outlet nozzle 12 to a turbine casing (not shown) to drive the turbine.

In the steam generator 1 thus formed, thorough design, manufacture and inspection are carried out in order to ensure safety, but in the unlikely event that the heat transfer tube 6 or the like is damaged. , High-temperature and high-pressure water and steam flow out into sodium, causing a chemical reaction with sodium, resulting in a sodium-water reaction accident that produces hydrogen gas and the like.

For this reason, generally, even if the heat transfer tube 6 is damaged, detection is performed at a small-scale sodium-water reaction stage, and measures are taken such as safely stopping the plant.

In a conventional fast breeder reactor plant, a chemical leak detector 15 for monitoring hydrogen concentration in sodium in order to promptly detect breakage of a heat transfer tube or the like in a small-scale sodium-water reaction stage. Is provided.

However, as the scale of the fast breeder reactor plant becomes larger and larger recently, the steam generator 1
Further, the capacity (not shown) of the other secondary system is also increased, and the amount of secondary system sodium is increased accordingly. For this reason, the change in the hydrogen concentration in sodium becomes slow, and it becomes difficult for the leak detection device 15 of the chemical formula described above to quickly detect damage to the heat transfer tube.

In order to improve this, the sound generated when the heat transfer tube 6 in the body 2 of the steam generator 1 is broken recently is attached to the waveguide rod 13 installed outside the body 2. An acoustic detector that immediately detects by the sensor 14 appears,
Is expected.

FIG. 8 shows a part of a helical coil type steam generator equipped with the acoustic detector.
An acoustic sensor 14 is attached to the body part 2 of FIG.

When the heat transfer tube 6 in the helical coil tube bundle 7 is damaged in this structure, sound is generated by jetting water or steam into sodium. This sound propagates through the sodium 21 in the outer cylinder 5 in which the heat transfer tubes 6 forming the helical coil tube bundle 7 are present, and reaches the outer cylinder 5.

The propagated sound penetrates the outer cylinder 5, and further reaches the body 2 through the sodium 23 in the region formed by the body 2 and the outer cylinder 5. After that, the acoustic sensor 14 is reached via the waveguide rod 13.

The sound thus reached is distinguished from the sound of sodium flow or the sound of boiling on the water side generated during the operation of the steam generator 1, and the breakage of the heat transfer tube 6 is immediately detected.

As a steam generator equipped with these detectors, there is JP-A-4-331339.

[0016]

The acoustic detection of damage to parts as described above can detect damage regardless of the size of the fast breeder reactor plant, and is effective in this respect. However, in this case, the sound generated by the breakage reaches the acoustic sensor 14 through the outer cylinder 5 or by being reflected.

In particular, at this time, the outer cylinder 5 is vibrated by the sodium sound wave in the outer cylinder, and the vibration of the outer cylinder is transmitted to the sodium in the region 23 surrounded by the outer cylinder and the body portion 2. In a transmission path in which a liquid region and a solid region having a large difference in density coexist, the sound pressure level is greatly attenuated by the time the sound wave reaches the body portion 2, and a range in which damage of the heat transfer tube 6 can be detected is detected. I hate being restricted.

Further, when the vibration of the outer cylinder 5 propagates into sodium in the region 22 surrounded by the outer cylinder 5 and the body 2, the sound pressure level reaching each waveguide bar 13 due to sound diffusion is increased. If they are equal, it may be difficult to identify abnormal noise in the signal processing process from each sensor 14, and the safety of the steam generator may be impaired.

The present invention has been made in view of the above, and it is an object of the present invention to provide a well-identified signal promptly with little attenuation even in this type of steam generator employing acoustic detection means. The purpose is to provide a steam generator of this kind that is regarded as highly safe.

[0020]

That is, according to the present invention, a solid body for connecting the body portion and an outer cylinder arranged in the body portion to the inner wall portion of the body portion at or near the position where the acoustic sensor is installed. The above-mentioned waveguide is provided to achieve the intended purpose.

[0021]

In other words, with the steam generator thus formed, the sound generated when the heat transfer tube of the steam generator is damaged is as in the conventional case in the transfer path from the sound source to the acoustic sensor. Since the liquid region and the solid region having a large density difference do not coexist and the transmission path from the outer cylinder to the acoustic sensor is only the solid region (solid body, for example, metal), the attenuation of the sound pressure level can be suppressed to a small level. Of.

The sound generated when the heat transfer tube of the steam generator is broken propagates from the sound source through the sodium region of the bundle of helical coil tubes, and then directly in the solid transfer path to the acoustic sensor in the inner surface area of the outer cylinder. Since it propagates, a large sound pressure can be received at the end of the transmission path, and a large detection signal can be obtained.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the steam generator in cross section. The same parts as those in the conventional example described above are designated by the same reference numerals, and detailed description thereof will be omitted.

A waveguide rod 13 is installed outside the body 2 of the steam generator as in the conventional case, and an accelerometer as an acoustic sensor 14 is attached to the outer end of the waveguide rod 13. The acoustic sensor 14 is connected to a signal processing facility 17 that processes a signal from the acoustic sensor to identify abnormal noise during operation of the steam generator.

What is important here is that although the waveguide rod 13 is installed outside the body of the steam generator, this waveguide rod 1
As shown in FIG. 2, a rod-shaped inner waveguide 18 is attached to the end of the body 3 on the body side, that is, on the inner surface side of the body 2 of the installation portion where the waveguide rod is installed by welding. Of.

In this case, the length of the internal waveguide 18 is
The outer cylinder 5 is formed by forming a cylindrical spacer slightly smaller than the gap width between the body 2 and the outer cylinder 5 and in the vicinity of the inner waveguide 18 so as to be slightly longer than the inner waveguide 18. It is fixed to the internal waveguide 18 via a stopper 19. With this configuration, when the steam generator 1 is manufactured, the body 2 and the outer cylinder 5 are
It is very effective because the gap width can be easily adjusted.

In this case, the outer cylinder 5 is provided with a notch, and the outer cylinder 5 is attached to the internal waveguide 18 by the notch.
Fixed at 9. The notch is covered and sealed by a stopper 19, and the sodium region 21 inside the outer cylinder 5 and the outer cylinder 5 are covered by the stopper 19 like the other outer cylinder 5 parts.
The boundary of the outer sodium region 22 is formed. Of course,
The stopper 19 is in contact with the sodium region 21 inside the outer cylinder 5.

In this embodiment, the internal waveguide 18 has been described as a rod-shaped member, but it does not have to be always a rod-shaped member, and it may be, for example, a protrusion, that is, a cylinder, a prism, or a plate. Of course, it is also good.

In the above embodiment, the structure in which the internal waveguide 18 is attached to the body 2 by welding has been described. However, the waveguide rod 18 is attached to the body 2 by screws or a combination of screws and welding. Alternatively, the protrusion-shaped waveguide may be cut out from the body 2 and formed.

FIG. 3 shows one embodiment of this. That is, in this case, the internal waveguide 18 is connected to the body 2
It is formed integrally with, or is cut out from, and FIG. 4 shows that the internal waveguide 18 is connected to the outer cylinder 5 by welding without using the above-mentioned stopper 19. To do.

In particular, with this configuration, the gap between the outer cylinder 5 and the inner waveguide 18 is sealed, and the boundary formation between the sodium region 21 inside and the sodium region 22 outside the outer cylinder 5 is further strengthened. .

That is, since the high temperature sodium flowing down inside the outer cylinder 5 does not flow out to the stagnant sodium region 22 outside the outer cylinder 5, the sodium drift and flow rate in the helical coil region 7 resulting from this. It is possible to form a stable stagnant sodium region 22 in the region between the outer cylinder 5 and the body portion 2 without lowering the heat transfer performance and soundness. It is excellent in detecting damage to the heat transfer tube.

In the case of FIG. 5, the outer cylinder 5 and the inner waveguide 1 are arranged.
In the case where the fixing with 8 is made by welding, and the internal waveguide 1
This is the case where 8 is formed in a tubular shape. With this configuration,
The sound generated when the heat transfer tube 6 of the steam generator 1 is damaged is from the sound source to the sodium region 2 of the helical coil tube bundle part 7.
After propagating 1, the signal propagates directly to the end of the internal waveguide 18 which is the starting point of the solid transmission path to the acoustic sensor 14, so that a large sound pressure is received at the end of the transmission path and a large detection signal is obtained. This makes it possible to provide a steam generator excellent in acoustic damage detection of heat transfer tubes.

FIG. 6 shows still another embodiment,
This is the case when applied to the heat shield plate 24 of the body 2. In this case, the damage detection of the heat transfer tube 6 from the helical coil tube bundle portion 7 to the portion where the heat transfer tube 6 penetrates the body portion 2 is also targeted, and the heat shield plate 24 installation region also includes the waveguide rod 13. The internal waveguide rod 18 is attached in the gap region between the body portion 2 on the inner surface side of the body portion 2 of the installation portion and the heat shield plate 24 with the same structure as that of FIG. 1 described above.

As described above in various ways, in the steam generator having such a structure, the sound generated when the heat transfer tube 6 of the steam generator 1 is damaged is from the sound source to the sound sensor 14. In the transmission path of, the liquid area and the solid area having a large density difference do not coexist, and the transmission path from the outer cylinder 5 to the acoustic sensor 14 is only the solid area (metal). It is possible to obtain the steam generator 1 which is excellent in detecting damage to the heat transfer tube by the acoustic method.

Since the outer cylinder and the heat shield are fixedly supported on the body via the waveguide 18 inside the body 2, the outer cylinder 5 is fixedly supported on the body 2. Therefore, it is possible to obtain the steam generator 1 which is excellent in the detection of damage to the heat transfer tube by the acoustic method, which is expected to increase the rigidity of the whole and improve the earthquake resistance.

[0037]

As described above, according to the present invention, the body portion and the outer cylinder arranged in the body portion are coupled to the inner wall portion of the body portion at or near the position where the acoustic sensor is installed. Since a solid waveguide is provided, the sound generated when the heat transfer tube of the steam generator is damaged causes a large density difference as in the past in the transfer path from the sound source to the acoustic sensor. The liquid and solid areas that it has are not mixed,
This type of steam generator is capable of suppressing the attenuation of the sound pressure level to a small level, and therefore, even with a steam generator that employs acoustic detection means, it is capable of capturing a sufficient signal promptly and with little attenuation, and is highly safe. Can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing an embodiment of a steam generator of the present invention.

FIG. 2 is a vertical sectional side view showing a main part of the steam generator of the present invention.

FIG. 3 is a vertical cross-sectional side view showing an essential part of another embodiment of the steam generator of the present invention.

FIG. 4 is a vertical cross-sectional side view showing an essential part of another embodiment of the steam generator of the present invention.

FIG. 5 is a vertical cross-sectional side view showing an essential part of another embodiment of the steam generator of the present invention.

FIG. 6 is a vertical cross-sectional side view showing an essential part of another embodiment of the steam generator of the present invention.

FIG. 7 is a vertical sectional side view showing a conventional steam generator.

FIG. 8 is a vertical cross-sectional side view showing a main part of a conventional steam generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steam generator, 2 ... Body part, 3 ... Sodium inlet nozzle, 4 ... Inner cylinder, 5 ... Outer cylinder, 6 ... Heat transfer tube, 7 ... Helical coil tube bundle part, 8 ... Sodium outlet nozzle, 9 ... Water supply inlet nozzle 10 ... Water inlet chamber, 11 ... Steam outlet chamber, 12 ...
Vapor outlet nozzle, 13 ... Waveguide rod, 14 ... Sensor, 15 ...
Chemical-type heat transfer tube breakage detection equipment, 16 ... Support beam, 18 ... Internal waveguide, 19 ... Stopper, 20 ... Spacer, 21 ... Outer cylinder inner sodium area, 22 ... Outer cylinder outer sodium area, 23 ...
Heat shield-sodium between the bodies, 24 ... Heat shield.

Claims (11)

[Claims] 1. A heat transfer tube group that performs heat conversion, an outer cylinder that covers the heat transfer tube group and guides a superheat medium, and a body that encloses the heat transfer tube group and the outer cylinder. In a steam generator including an acoustic sensor for detecting breakage of an internal member, a solid waveguide is interposed between the body inner wall and the body outer wall at or near the sensor installation position. A steam generator characterized in that 2. A heat transfer tube group that performs heat conversion, an outer cylinder that covers the heat transfer tube group and guides a superheat medium, and a body that encloses the heat transfer tube group and the outer cylinder. In, in the steam generator provided with an acoustic sensor for detecting the breakage of the internal member, the sensor installation position or the body inner wall portion in the vicinity thereof,
A steam generator comprising a waveguide for connecting the body and the outer cylinder. 3. A heat transfer tube group that performs heat conversion, an outer cylinder that covers the heat transfer tube group and guides a superheat medium, a body that encloses the heat transfer tube group and the outer cylinder, and is disposed inside the body. And a heat shield layer that blocks heat transfer to the body portion side of the overheating medium, and a steam generator that includes an acoustic sensor that detects damage to the internal member on the outside of the body portion, wherein the sensor At the installation position or on the inner wall of the body near it,
A vapor generator provided with a waveguide for coupling the body and the outer cylinder or the heat shield layer. 4. A spiral shape in which a plurality of heat transfer tubes, through which a medium to be heated flows, are formed in a spiral layer having a constant diameter, and further a plurality of heat transfer tubes are wound up outside or inside the spiral layer. A heat transfer tube group in which the layers are concentrically combined, a tube header to which the ends of the heat transfer tube group are connected, a cylindrical inner cylinder concentrically installed at the spiral center of the heat transfer tube group, An outer cylinder concentrically installed outside the heat tube group, and a body section that encloses the inner tube, the heat transfer tube group, and the outer tube, and an acoustic sensor for detecting damage to the heat transfer tube is provided outside the body section. In the steam generating device, in the inner wall portion of the body portion at or near the sensor installation position,
A steam generator comprising: a waveguide for connecting the body and a heat shield attached to the outer cylinder or the inside of the body. 5. A spiral shape in which a plurality of heat transfer tubes in which a medium to be heated flows is formed in a spiral layer having a constant diameter, and further a plurality of heat transfer tubes are wound up outside or inside the spiral layer. A group of heat transfer tubes in which layers are concentrically combined, a pipe head to which end portions of the group of heat transfer tubes are connected, a cylindrical inner cylinder concentrically installed at a spiral center of the group of heat transfer tubes, An outer cylinder concentrically installed outside the heat tube group, and a body portion that encloses the inner cylinder, the heat transfer tube group, and the outer cylinder. The heat transfer tube breakage detection is performed outside the body portion via a waveguide rod. In a steam generator provided with an acoustic sensor for use in a body inner wall portion at or near the installation position of the waveguide rod, a heat shield attached to the body portion and the outer cylinder or the inner portion of the body portion. A steam generator, characterized in that a waveguide for coupling with each other is provided. 6. The waveguide is formed such that one side thereof is welded and fixed to an inner wall surface of a body portion, and the other side is detachably coupled to an outer cylinder or a heat shield with a fixing stopper. The steam generator described. 7. The steam generator according to claim 6, wherein the fixing stopper is formed so as to be exposed in a body-side fluid region composed of an outer cylinder, an inner cylinder, a heat transfer tube and a heat shield. . 8. The steam generator according to claim 6, wherein the fixing stopper is formed so as to form a boundary between fluid inside and outside the outer cylinder. 9. The steam generator according to claim 6, wherein a cylindrical spacer is provided around the waveguide so as to surround the waveguide. 10. The waveguide is formed of a cylindrical member, and its ends are fixed to the outer cylinder and the body by welding, and the hollow portion of the cylindrical member is the outer cylinder. 10. The steam generator according to claim 6, 7, 8 or 9, which is formed so as to open inside. 11. The steam according to claim 6, wherein the outer cylinder and the heat shield are formed so as to be fixedly supported by the body via the waveguide inside the body. Generator.