JP3453339B2 - Degassing device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a deaerator,
More specifically, the present invention relates to a degassing device that uses an ejector to degas a gas dissolved in the liquid.

[0002]

2. Description of the Related Art Usually, when degassing a gas dissolved in a liquid, first, the liquid is atomized, and the gas for degassing is brought into contact with the atomized liquid to form a gas from the atomized liquid. A degassing device for degassing is used.

FIG. 7 is a block diagram showing the outline of a conventionally used deaerator of this type.

This type of deaerator is equipped with a cylindrical deaerator 2 and a liquid tank 3 arranged below it. A spray section 12 is provided above the degassing tower 2, and a water supply pipe 4 for introducing the liquid to be treated a is connected to the spray section 12.

The water supply pipe 4 is provided with a compression pump (not shown) for supplying the liquid a to be treated into the degassing tower 2 at high pressure. In the spray unit 12, a spray nozzle 13 is arranged directly above the packed bed 6 at the center of the degassing tower 2.

The spray nozzle 13 is capable of spraying the liquid a to be treated in a wide-angle mist (fine particle form) and supplying it to the entire surface of the filling layer 6.

A packing 7 is provided below the packed bed 6, and the gas and the liquid can flow through the packing 7.

A gas disperser 8 is provided inside the liquid tank 3, and a gas supply pipe 9 for introducing the degassing gas b into the gas disperser 8 is further connected to the gas disperser 8. . A drain pipe 10 for discharging treated water is provided on the side of the liquid tank 3. Furthermore, in the upper part of the degassing tower 2,
An exhaust pipe 11 is provided.

With this structure, the liquid a to be treated is
When taken into the deaerator through the water supply pipe 4, it is sprayed into a wide-angle mist by the spray nozzle 13 and supplied to the entire surface of the filling layer 6.

The filling layer 6 is filled with a filling material (for example, one of A to H) as shown in FIG.
The liquid to be treated a sprayed in the form of mist flows down to the surface of this filling material.

On the other hand, a degassing gas b (for example, when removing oxygen dissolved in the liquid a to be treated from the liquid a to be treated, a nitrogen gas or the like is used as the gas b for degassing).
Flows through the gas disperser 8 in opposition to the liquid to be treated a flowing from the upper side to the lower side, that is, flows upward in the void portion formed by the filling material of the filling layer 6.

A liquid to be treated a flowing down the surface of the filling,
When gas-liquid contact with the degassing gas b rising in the void portion of the filling material occurs, the dissolved gas is removed from the liquid to be treated a by using the gas partial pressure difference due to the dissolved gas in each fluid as a driving force. . This will be described with reference to FIG. 9 as an example in which the liquid a to be treated is water, the degassing gas b is nitrogen gas, and oxygen dissolved in water is degassed using nitrogen gas.

As shown in FIG. 9A, oxygen is dissolved in water which is the liquid a to be treated, and the oxygen partial pressure (pressure of oxygen in water) is P ₁ . On the other hand, degassing gas b
Is pure nitrogen, it does not contain oxygen, and the oxygen partial pressure P ₂ in the nitrogen gas is P ₂ = 0. When the oxygen-dissolved water and the nitrogen gas come into contact with each other in this manner, the oxygen dissolved in the water moves from a high concentration location to a low concentration location, as shown in FIG. 9B. This movement amount Q is proportional to the oxygen partial pressure difference (P ₁ -P ₂ ) as shown in the following formula (1).

Q∝ (P ₁ -P ₂ ) ... (1) As described above, by moving the oxygen gas into the nitrogen gas, the dissolved oxygen is removed and the water is removed as shown in FIG. 9C. Degassed.

The liquid a to be treated is degassed by the packed bed 6 as described above, and then drops into the liquid tank 3, and the drainage pipe 10
Be drained through. On the other hand, the gas degassed from the degassing gas b and the liquid a to be treated is exhausted through the exhaust pipe 11.

[0016]

However, such a conventional deaerator has the following problems.

That is, in such a conventional deaerator, in order to enhance the deaerating efficiency, which is the efficiency of deaerating the dissolved gas from the liquid to be treated a, it is necessary to promote the gas-liquid contact effect. This is (the sum of the height _{Z b} of the filling layer 6 and the height _{Z s} of the spray unit 12) column high _{Z t} of the degassing tower 2 and increases,
This results in an increase in the surface area of the packing material packed in the packing layer 6.

In order to achieve a degassing efficiency of 95% (95% of dissolved gas is degassed) in the conventional degassing apparatus, the tower height Z _t is about 2.5 m and the tower diameter D is about. 1.
It will be 6m. As described above, when the tower height _Zt becomes high, there is a problem that the location of the deaerator is limited.

Further, the conventional degassing apparatus is used in a nuclear facility, and the liquid a to be treated containing radioactive fine particles (clads) is treated.
In the case of handling, there is a problem in that the clad adheres to the surface of the filling material and accumulates, resulting in an increase in the radiation dose in the filling layer 6.

The present invention has been made in view of the above circumstances. A first object of the present invention is to remove the packed bed and add an ejector, thereby reducing the degassing efficiency by removing the packed bed. The purpose of the present invention is to provide a degassing device capable of reducing the tower height without reducing the degassing efficiency.

The second object is to remove the packed bed and to add an ejector to which the clad does not adhere when applied to a nuclear facility, thereby reducing the tower height without reducing the degassing efficiency. Another object of the present invention is to provide a deaerator capable of suppressing an increase in radiation dose.

[0022]

In order to achieve the above object, the present invention takes the following means.

That is, according to the invention of claim 1, the radioactive material is
Taking in the cooling water of the reactor containing quality and transferring it to the downstream side
The transfer means and the transfer means provided on the downstream side of the transfer means.
Take in the cooling water transferred and discharge it from the nozzle.
And is dissolved in the cooling water discharged from the nozzle.
The degassing gas that degasses the cooling water from the cooling water
The gas is cooled by blowing it into the cooling water discharged from
The ejector that degass the wastewater and the degassing gas are blown
Spraying means for spraying the cooling water
From the direction opposite to the spray direction
Blowing degassing gas into sprayed cooling water Degassing gas blowing
The charging means, the spraying means and the degassing gas blowing means are housed inside.
It is equipped with a degassing tower. And by the ejector
Most of the gas is degassed from the cooling water by the ejector.
Therefore, the gas that has not been degassed from the cooling water is degassed.
In the air column, to the cooling water sprayed by the spraying means,
The degassing gas blown by the degassing gas blowing means
By degassing by blowing into the degassing tower
The amount of radioactive substances attached is reduced.

[0024]

According to a second aspect of the invention, in the deaerator according to the first aspect , the gas is oxygen and the degassing gas is nitrogen gas.

[0026]

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

It is to be noted that the reference numerals in the drawings used in the description of each of the following embodiments are designated by the same reference numerals as those in FIG.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a configuration diagram showing an example of the overall configuration of the deaerator according to the first embodiment.

That is, the deaerator according to this embodiment is different from the deaerator according to the prior art shown in FIG.
The plate 7 and the water supply pipe 4 are deleted, and the water supply pipe 14, the pump 15, the ejector 16, the air supply pipe 17, and the supply pipe 18 are added.

Therefore, only the part different from FIG. 7 will be described here.

The water supply pipe 14 is a pipe for supplying the liquid to be treated a to the ejector 16.

The pump 15 is provided in the water supply pipe 14,
The liquid a to be treated is taken in and discharged to the ejector 16 side.

The ejector 16 introduces the liquid to be treated a discharged by the pump 15 via the water supply pipe 14 and the degassing gas b introduced via the air supply pipe 17 to the liquid a to be treated. Blow in.

FIG. 2 is a sectional view showing the structure of a general ejector.

The ejector 16 includes the nozzle 20 and the outer case 2.
1, a throat 22, and a diffuser 23.

The nozzle 20 is connected to the water supply pipe 14 and has a substantially conical shape that tapers toward the tip. Therefore, the nozzle 2 is connected via the water supply pipe 14.
The to-be-processed liquid a introduced to 0 is made to increase in pressure inside the nozzle 20 while moving to the tip portion N of the nozzle 20. Then, the liquid a to be treated, which has become high-pressure water in this way, is jetted from the tip portion N of the nozzle 20 to the throat 22 side.

On the other hand, the ejector 16 is provided with an outer case 21 which surrounds the nozzle 20 and is connected to the throat 22. The outer case 21 is provided with a through hole R, and the through hole R is connected to the air supply pipe 17.

The air supply pipe 17 is a pipe for supplying the degassing gas b to the ejector 16. As the degassing gas b, the same gas as the degassing gas b supplied from the gas supply pipe 9 to the gas disperser 8 is used.

The throat 22 is provided on the downstream side of the nozzle 20 and has a cylindrical structure integrated with the outer case 21. The liquid to be treated a jetted from the tip portion N of the nozzle 20 and the air supply pipe 17 are provided. The degassing gas b introduced into the outer case 21 through the above is mixed here to form a mixed flow c.

The diffuser 23 has a substantially conical shape integrally connected to the throat 22.
The inner diameter of the end connected to is the thinnest. The other end is connected to the supply pipe 18, and the inner diameter is increased toward the supply pipe 18 side.

Such a shape of the diffuser 23 promotes bubble dispersion of the mixed flow c generated in the throat 22. That is, since the flow path of the mixed flow c becomes wider toward the downstream side, as shown in FIG. 3, the bubbles of the degassing gas b in the mixed flow c go toward the downstream side of the diffuser 23 and have a particle size. Becomes smaller and is dispersed in the liquid a to be treated. As a result, the contact area between the liquid to be treated a and the degassing gas b becomes larger on the downstream side of the diffuser 23. When the contact area between the liquid to be treated a and the gas for degassing b becomes large, the gas dissolved in the liquid to be treated a easily moves to the side of the gas for degassing b, so that the degassing efficiency increases.

The supply pipe 18 connects the diffuser 23 and the degassing tower 2, and supplies the mixed flow c discharged from the diffuser 23 to the spray nozzle 13 of the degassing tower 2.

The spray nozzle 13 sprays the mixed flow c toward the inside of the degassing tower 2 in the form of mist. As a result, the mixed flow c becomes the liquid to be treated a from which the dissolved gas has been degassed.
And the gas dissolved in the liquid to be treated a are separated into the degassing gas b, and the gas inside the spray section 12 is lowered.

The gas disperser 8 supplies the degassing gas b to the spray section 12 from the lower side to the upper side of the degassing tower 2. As a result, gas-liquid contact between the liquid to be processed a descending the spray unit 12 and the degassing gas b rising to the spray unit 12 occurs, and the dissolved gas not removed by the ejector 16 is removed from the liquid a to be processed. I am trying to do it.

The liquid a to be treated is degassed as described above, then drops into the liquid tank 3 and is drained through the drainage pipe 10. On the other hand, the gas degassed from the degassing gas b and the liquid a to be treated is exhausted through the exhaust pipe 11.

Next, the operation of the deaerator according to the present embodiment configured as described above will be described by taking the case of removing dissolved oxygen from cooling water of a nuclear power plant as an example.

In a nuclear power plant, when oxygen is dissolved in the reactor cooling water, this oxygen causes corrosion of pipes and equipment. Therefore, in the periodic inspection performed between operation cycles, the reactor cooling water is Deaeration work is performed to deaerate oxygen from the.

In this deaeration work, first, the pump 1
5, the reactor cooling water is continuously supplied to the nozzle 20 of the ejector 16 through the water supply pipe 14.

The reactor cooling water supplied to the nozzle 20 is
The pressure is increased toward the tip portion N side of the nozzle 20, and is jetted from the tip portion N of the nozzle 20 to the throat 22 side.

On the other hand, the ejector 16 is supplied with nitrogen gas which is the degassing gas b from the air supply pipe 17 through the through hole R. This nitrogen gas, at the throat 22,
The mixed water is mixed with the reactor cooling water injected from the tip portion N of the nozzle 20, and is transferred to the diffuser 23.

In this mixed water, nitrogen gas exists as bubbles. The bubbles are made finer toward the downstream side of the diffuser 23 and are dispersed in the mixed water. As a result, the contact area between the reactor cooling water and the nitrogen gas increases toward the downstream side of the diffuser 23. When the contact area between the reactor cooling water and the nitrogen gas becomes large, oxygen dissolved in the reactor cooling water easily moves to the nitrogen gas side, and the degassing efficiency is improved.

The mixed water is supplied from the diffuser 23 to the spray nozzle 13 of the degassing tower 2 through the supply pipe 18.

The mixed water is sprayed in the form of mist toward the inside of the degassing tower 2 by the spray nozzle 13, whereby
Dissolved oxygen is separated into degassed reactor cooling water and nitrogen gas that has captured oxygen dissolved in the reactor cooling water, and descends inside the spray section 12, respectively.

From the gas disperser 8 to the spray unit 12,
Nitrogen gas is supplied as the degassing gas b. In addition, the degassing gas b supplied to the spray unit 12 is the ejector 1
It must be of the same type as the degassing gas b supplied to 6.

This nitrogen gas rises in the spray section 12 from the lower side to the upper side. This causes gas-liquid contact between the reactor cooling water that descends in the spray section 12 and the nitrogen gas that rises in the spray section 12, and the dissolved oxygen that has not been removed by the ejector 16 is removed from the reactor cooling water.

FIG. 4 is a diagram showing the relationship between the flow rate of nitrogen gas supplied to the degassing tower 2 and the degassing efficiency. This data was acquired when the flow rate of nitrogen gas supplied to the ejector 16 through the air supply pipe 17 was 15.6 Nm ³ / h and the water temperature was 30 ° C. In this case, the degassing efficiency means a ratio of dissolved oxygen degassed from water, and when the dissolved oxygen is completely degassed from water, the degassing efficiency becomes 1.

As shown in FIG. 4, it can be seen that the degassing efficiency increases as the flow rate of the nitrogen gas supplied to the degassing tower 2 increases.

When there is no flow rate of the nitrogen gas supplied to the degassing tower 2, it corresponds to the degassing efficiency of the ejector 16 alone.
When the flow rate of the nitrogen gas supplied to the degassing tower 2 is increased, the dissolved oxygen that has not been degassed by the ejector 16 is degassed in the degassing tower 2, so that the degassing efficiency is improved.

The water from which the dissolved oxygen has been degassed in this way falls into the liquid tank 3 and is drained through the drainage pipe 10. On the other hand, nitrogen gas and oxygen degassed from water are
The gas is exhausted through the exhaust pipe 11.

As described above, in the degassing apparatus according to the present embodiment, the ejector 16 is provided in the preceding stage of the degassing tower 2 by the above-described action, so that the degassing efficiency can be reduced without being reduced. Layer 6 can be deleted.

In order to achieve a degassing efficiency of 95% using the degassing apparatus according to this embodiment, the total length is about 1 m.
And of the ejector 16, tower height _{Z t} degassing tower of about 1.7m 2
It is realized by combining and. When the deaerator according to the prior art is used, the tower height Z _t of the deaerator 2 needs to be about 2.5 m in order to obtain a deaerating efficiency of 95%. When used, the total length can be reduced by about 80 cm.

Further, when the deaerator according to this embodiment is used in a nuclear facility to deaerate oxygen dissolved in the reactor cooling water containing the clad which is radioactive fine particles, the reactor cooling water remains. The clad does not accumulate in one place. Therefore, the radiation dose is reduced as compared with the conventional deaerator.

As a result, the deaerator can be arranged even in a place where the floor height is low, where the deaerator could not be arranged in the past, and the degree of freedom in arrangement can be increased. In addition, when the reactor cooling water containing the clad is degassed, the radiation dose is reduced as compared with the degassing apparatus according to the related art.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a configuration diagram showing an example of the overall configuration of the deaerator according to the second embodiment.

The deaerator according to the second embodiment is designed so that the ejector 16 alone deaerates, and the deaerator 2 is removed from the deaerator according to the first embodiment. ,
The recovery pipe 25 connected to the diffuser 23 of the ejector 16 is provided with a steam separator 26, and the steam separator 2 is further provided.
6 is provided with an exhaust pipe 11.

The steam separator 26 separates liquid and gas from the mixed water flowing in the recovery pipe 25, sends the separated liquid to the downstream side of the recovery pipe 25, and separates the separated gas from the exhaust pipe 11 side. Send to.

The exhaust pipe 11 is provided from the upper side of the recovery pipe 25 so that the gas in the recovery pipe 25 can be discharged.

Next, the operation of the degassing device according to this embodiment having the above-described structure will be described.

The mixed water produced in the diffuser 23 as described in the first embodiment is discharged to the recovery pipe 25.

The mixed water flowing in the recovery pipe 25 is taken into the steam-water separator 26, and separated in the steam-water separator 26 into nitrogen gas in which dissolved oxygen is captured and water in which dissolved oxygen is degassed. . And the nitrogen gas that captured the dissolved oxygen is
It is sent to the exhaust pipe 11 side and discharged. The water from which dissolved oxygen has been degassed is sent to the downstream side of the recovery pipe 25.

FIG. 6 is a diagram showing the relationship between the flow rate of nitrogen gas supplied to the ejector 16 and the degassing efficiency of the ejector 16. This data was acquired when the flow rate of the water supplied to the ejector 16 was 30 m ³ / h and the water temperature was 30 ° C.

As shown in FIG. 6, when the flow rate of the nitrogen gas supplied to the ejector 16 is increased, the contact area between the water and the nitrogen gas is increased, so that the degassing efficiency is improved.
Therefore, even if the degassing tower 2 is deleted and the degassing efficiency is reduced, the degassing efficiency is complemented by increasing the flow rate of the nitrogen gas supplied to the ejector 16.

As described above, in the deaerator according to this embodiment, by removing the deaerator 2,
In addition to achieving the same effects as those of the embodiment described above, it is possible to further simplify the configuration and downsize the entire device.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such configurations. Within the scope of the technical idea described in the claims, those skilled in the art can contemplate various modifications and modifications, and the modifications and modifications are also within the technical scope of the present invention. Be understood to belong to.

[0078]

As described above, according to the deaerator of the present invention, the ejector can supplement the deaerating efficiency reduced by removing the packed bed and adding an ejector. .

As described above, the tower height can be reduced without reducing the degassing efficiency. Further, since the clad does not accumulate, it is possible to suppress an increase in radiation dose even when applied to a nuclear facility.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of the overall configuration of a degassing device according to a first embodiment.

FIG. 2 is a cross-sectional view showing the configuration of a general ejector.

FIG. 3 is a schematic diagram for explaining a mechanism of dispersion of a degassing gas in a mixed flow.

FIG. 4 is a diagram showing a relationship between a flow rate of nitrogen gas supplied to a degassing tower and degassing efficiency.

FIG. 5 is a configuration diagram showing an example of the overall configuration of a degassing device according to a second embodiment.

FIG. 6 is a diagram showing the relationship between the flow rate of nitrogen gas supplied to the ejector and the degassing efficiency of the ejector.

FIG. 7 is a schematic diagram showing the outline of a conventionally used deaerator of this type.

FIG. 8 is a perspective view showing an example of a filling material.

FIG. 9 is a schematic diagram for explaining a state in which dissolved oxygen is captured by nitrogen gas.

[Explanation of symbols]

2 ... Degassing tower, 3 ... liquid tank, 4 ... Water supply piping, 6 ... packed bed, 7 ... 8 ... Gas disperser, 9 ... Air supply piping, 10 ... drainage pipe, 11 ... Exhaust pipe, 12 ... Spray part, 13 ... Spray nozzle, 14 ... Water supply piping, 15 ... Pump, 16 ... Ejector, 17 ... Air supply piping, 18 ... Supply piping, 20 ... Nozzle, 21 ... Outer body, 22 ... throat, 23 ... Diffuser, 25 ... Recovery piping, 26 ... Air-water separator.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-318138 (JP, A) JP-A-8-290007 (JP, A) JP-A-6-15107 (JP, A) JP-A-6- 178971 (JP, A) JP-A-6-190360 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 1/20 B01D 19/00 G21D 1/02

Claims (2)

(57) [Claims] 1. A transfer means for taking in cooling water of a nuclear reactor containing a radioactive substance and transferring it to a downstream side; and a cooling means, which is provided at a downstream side of the transferring means and takes in the cooling water transferred by the transferring means, While discharging from the nozzle, a degassing gas for degassing the gas dissolved in the cooling water discharged from the nozzle from the cooling water, by blowing into the cooling water discharged from the nozzle, An ejector for degassing gas from the cooling water, a spraying unit for spraying the cooling water in which the degassing gas is blown, and a spraying unit from a side opposite to the spraying direction of the cooling water. A degassing gas blowing means for blowing the degassing gas into the cooling water sprayed by, and a degassing tower containing the spraying means and the degassing gas blowing means therein. The degassing of the gas from the cooling water is mostly performed by the ejector, and the gas that has not been degassed from the cooling water by the ejector is sprayed by the spraying means in the degassing tower. For cooling water,
Degassing by blowing the degassing gas blown by the degassing gas blowing unit to reduce the amount of the radioactive substance attached to the degassing tower. apparatus. 2. The deaerator according to claim 1, wherein the gas is oxygen and the deaerating gas is nitrogen gas.