JP3326075B2 - Vacuum deaerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum degassing apparatus for removing gas dissolved in water under reduced pressure, and more particularly to a vacuum degassing apparatus suitable for removing trace amounts of dissolved oxygen used in a process of manufacturing an VLSI.

[0002]

2. Description of the Related Art In a manufacturing process of an ultra LSI, highly purified ultrapure water is used to prevent impurities from being mixed. For example, ultrapure water used for cleaning semiconductor wafers is required to remove dissolved oxygen (DO) to 10 μg / l (ppb) or less. Furthermore, LS
With the ultra-high degree of integration of I, ultra-highly degassed ultrapure water having a dissolved oxygen concentration of 2 μg / l or less is being demanded.

On the other hand, a vacuum deaerator has been widely used for removing dissolved gas in water. In this vacuum deaerator, the gas pressure in a degassing tower filled with a gas-liquid contact material for increasing the surface area of water is reduced by a vacuum pump, and pure water, which is water to be treated, is placed in a vacuum state and dissolved. It removes oxygen.

[0004] However, in order to reduce the dissolved oxygen to the above-mentioned concentration by the vacuum degassing device based on simple vacuum degassing, the filling height of the gas-liquid contact material of the vacuum degassing device increases.
In addition, the displacement of the vacuum pump becomes very large,
It is not practical because both initial cost and running cost are high and a large installation space is required.

[0005] Here, the dissolved oxygen is proportional to the oxygen partial pressure in the gas phase. For this reason, the degassing performance is improved by heating the treated water stored under the space below the packed bed in the vacuum degassing tower or by flowing an inert gas from the space below the packed bed. Has been proposed.

[0006]

However, when the above-mentioned conventional vacuum degassing apparatus is used, the original performance of the apparatus (the apparatus without the means for heating the stored treated water, or the lower degassing chamber) is used. The practical limit of the apparatus that does not allow the inflow of inert gas is 30 to 50 μg / l. For this reason,
In order to reduce the dissolved oxygen to 2 μg / l or less based on this vacuum deaerator, it is necessary to considerably reduce the oxygen partial pressure in the gas phase of the deaeration tower. In addition, there is a problem in that the amount of inert gas flowing into the chamber increases and the cost increases. In addition, it has been practically difficult to stably obtain high-quality treated water having a dissolved oxygen content of 2 μg / l or less.

[Related Art] Here, the present inventors have developed a vacuum deaerator capable of dramatically increasing the deaeration effect by substantially eliminating a gaseous space below a packed bed. Japanese Patent Application No. 8-58090 and Japanese Patent Application No. 8-58090
155315.

According to this apparatus, the dissolved oxygen in the treated water can be stably reduced to 10 μg / l or less.
However, in order to reduce the dissolved oxygen to 1 μg / l, some other means is required.

The present invention has been made in view of these problems, and it is possible to obtain treated water having an extremely low concentration such that the dissolved oxygen of the treated water is 2 μg / l or less, for example, by adding simple means. It is an object of the present invention to provide a vacuum deaerator capable of being used.

[0010]

[0011]

[0012]

[0013]

[0014]

According to the present invention, a packed layer of a gas-liquid contact material is formed in a plurality of stages in an airtightly formed degassing tower,
The water to be treated is supplied from above the degassing tower, the treated water is discharged from below the lowermost packed bed, and the gas in the degassing tower is discharged from at least above the uppermost packed bed by vacuum means. In the vacuum deaerator configured to set the treated water level in the gas tower at substantially the same position as the lower end of the lowermost packed bed or at a position slightly above the lower end of the packed bed, at least the lowermost packed bed Heated degassed water, heated steam, inert gas, and one or more fluids selected from degassed water in which the inert gas is dissolved are introduced, and at the bottom, A bottom plate with no hole is placed at the bottom of the step with no holes, and the bottom plate supports the packed layer of the gas-liquid contact material, and the bottom plate is provided with a water seal section. A process water having a concentration of 2 μg / l or less is obtained. .

Further, another vacuum pump is provided from above the packed bed of each stage.
While discharging gas, the degree of vacuum goes downward.
It is possible to change the degree of vacuum of the vacuum means in order to increase
It is suitable.

[0016]

As described above, the present invention is based on a vacuum degassing apparatus in which a gas phase space below a packed bed is substantially eliminated, thereby greatly increasing a degassing effect.

Then, heated degassed treated water, heated steam, inert gas, or treated water in which an inert gas is dissolved is introduced into the packed bed of the degassing tower,
Alternatively, in the gas phase of the packed bed, the partial pressure of the gas to be removed is reduced by heating the water to be treated supplied to the degassing tower and / or the treated water falling down the packed bed. The concentration can be further reduced significantly.

That is, by the introduction of the fluid or the heating of the water to be treated, in the gas phase of the packed bed, the steam pressure, the inert gas partial pressure, or both pressures increase. For this reason, the oxygen partial pressure in the packed bed of the degassing tower relatively decreases. As a result, highly degassed treated water having a dissolved oxygen concentration of 2 μg / l or less can be stably obtained without increasing the height of the packed bed and increasing the displacement of the vacuum pump.

In particular, the present inventors have disclosed in Japanese Patent Application No. 8-58090.
As disclosed in Japanese Patent Application Laid-Open No. H10-260, the disadvantage caused by the presence of the gas phase space can be eliminated only by substantially eliminating the gas phase space below the packed bed, and as a result, in the vacuum deaerator of this application, The dissolved oxygen can be stably reduced to 10 μg / l or less.

The capacity of the vacuum degassing apparatus which substantially eliminates the gas phase space below the packed bed is to reduce dissolved oxygen to 10 μg / l or less. In order to further reduce the dissolved oxygen to 2 μg / l or less, it is only necessary to slightly reduce the oxygen partial pressure in the gas phase of the degassing tower.

[0022]

Further, by completely separating the plurality of stages of the packed layers by the water sealing portion, more reliable processing can be performed.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

[ Basic Configuration 1 ] FIG. 1 is a view showing the overall configuration of a vacuum deaerator according to the basic configuration 1 , and has a cylindrical deaeration tower 10. The degassing tower 10 is formed in an airtight manner, and a packed layer 12 is formed in an intermediate portion inside the degassing tower 10. The filling layer 12 is filled with a porous material such as Lahiscilling. Note that the filling layer 12 is formed by supporting a porous substance such as lahiscilling with a perforated plate 12a having a large number of holes. Above the packed bed 12 in the degassing tower 10, a degassing chamber 14,
A treated water storage chamber 16 is formed below the packed bed 12.

In the upper part of the degassing chamber 14, the treated water supply pipe 1 is provided.
A spraying device 20 for spraying the water to be treated supplied from 8 toward the packed layer 12 is provided. Further, a drain pump 24 is connected to the bottom of the treated water storage chamber 16 via a treated water discharge pipe 22 for discharging treated water.

The deaeration chamber 1 above the packed bed 12
4, a vacuum pump 26 is connected via an exhaust pipe 28, and pressure detection nozzles 30a and 30b are additionally provided between the treated water storage chamber 16 and the deaeration chamber 14,
A differential pressure gauge 30 is provided for detecting the treated water level in the treated water storage chamber 16 via both nozzles 30a and 30b. The output of the differential pressure gauge 30 is
And the flow rate of the water to be treated is controlled via a control valve 33 attached to the water supply pipe 18.

That is, the differential pressure gauge 30 communicates with the inside of the degassing chamber 14 and the treated water storage chamber 16 at two points, and detects the water level from the pressure difference between these two points. Therefore, the lower communication end of the differential pressure gauge 30 is set below the water surface of the treated water storage chamber 16, that is, below the eye plate 12a, and the upper communication end is set above the water surface, that is, above the eye plate 12a. In the illustrated example, the upper communication end is located in the degassing chamber 14, but may be in the packed bed 12 if it is above the water surface. As a method of detecting and controlling the level of the treated water, it goes without saying that other methods such as a float type, a capacitance type, and a photoelectric type may be used.

In such an apparatus, pure water, which is water to be treated, is supplied to a spraying device 20 via a water supply pipe 18. The spraying device 20 has a large number of holes formed on the lower surface thereof, and sprays the water to be treated toward the packed bed 12 in the degassing chamber 14. The sprinkled water to be treated falls due to gravity and travels along the surface of the filler in the packed layer 12,
It accumulates in the treated water storage chamber 16. Then, the water is introduced into the subsequent device by the drainage pump 24 through the treated water discharge pipe 22.

On the other hand, by the operation of the vacuum pump 26, the gas in the degassing chamber 14 is discharged to the outside via the exhaust pipe 28. Therefore, the inside of the degassing chamber 14 is in a high vacuum state. For example, the pressure is reduced to about 24 Torr (approximately only the water vapor pressure) at an air temperature of 25 ° C.

Therefore, dissolved oxygen is released from the water to be treated sprayed from the spraying device 20. And the filling layer 12
When falling, the surface area of the water to be treated is increased by transmitting along the surface of the filler, and the release of dissolved oxygen from the water to be treated is further promoted.

As described above, according to the present apparatus, the packed bed 12
There is virtually no gaseous space below the. With this configuration, the efficiency of removing dissolved oxygen is dramatically increased, and the concentration of dissolved oxygen in the treated water can be stably reduced to 10 μg / l or less.

Although this has been experimentally confirmed,
The principle is considered as follows. First, oxygen discharged from the water to be treated can be efficiently discharged by performing the exhaust from the degassing chamber 14 which is the upper space of the packed bed 12. That is, since the amount of dissolved oxygen released into the gas phase is larger in the upper part of the degassing chamber, more preferable degassing treatment is performed.

Further, since there is no space below the filling layer 12, the space is only the inside of the filling layer 12 above the perforated plate 12a and the degassing chamber 14 communicating therewith. Therefore, the gas separated in the packed bed 12 is discharged to the outside via the degassing chamber 14 as it is. That is, since deaeration is performed in substantially one space, effective deaeration is performed.

Here, in the conventional deaerator, the eye plate 12a
There was a space below the space. The filling layer 12 has a structure in which the gas-liquid contact material is supported by the eye plate 12a, and a certain amount of pressure loss may occur due to a water film or the like at the eye plate 12a. Therefore, it is presumed that the pressure in the lower space of the filling layer 12 tends to be relatively high, and there is a possibility that oxygen remains there. In addition,
In theory, oxygen is only generated from the water to be treated,
It is considered that even if a space is provided below the packed layer 12, the dissolved oxygen that has once dropped does not rise again. However, the existence of the two rooms separated by the eyeboard 12a and the water film falling from it means that the load on the vacuum pump 26 increases, and for example, the pressure value tends to fluctuate. It is supposed that the degassing effect will not be sufficient as a whole. Further, although the degassing tower 10 is airtight, the penetration by the leak of the outside air is not completely zero, but since the lower part of the packed layer 12 is filled with the liquid, the leak of the outside air is reduced. The effect of prevention is also exhibited.

In the first basic configuration , such a defect is eliminated by substantially eliminating the space of the gaseous phase below the packed layer 12, so that efficient degassing can be performed.

By setting the water level exactly equal to the position of the eye plate 12a, treated water with the lowest dissolved oxygen can be obtained.
If the water level is such that a very slight gas phase exists below the eye plate 12a, the dissolved oxygen amount of the treated water is not significantly affected.

In the first basic configuration , the deaeration chamber 1
Although the exhaust pipe 28 is communicated with the inside 4, the exhaust pipe 28 may be communicated with the packed layer 12. However, in this case, the exhaust pipe 28 may be connected to the upper part of the packed bed 12 from the viewpoint that the effective height of the gas-liquid contact of the packed bed 12 is not reduced.

In the basic configuration 1 , the treated water storage chamber 16
Although the water level in the inside is set to be substantially the same as the position of the eye plate 12a, the present invention is not limited to this, and the water level may be set in the packed layer 12 above the position of the eye plate 12a. However, in this case, as the water level in the packed bed 12 rises, the effective height of the packed bed 12 for bringing into gas-liquid contact decreases, so that it may be set at a position slightly above the lower end of the packed bed 12.

Further, in the basic configuration 1 , when the water level is controlled by the differential pressure gauge 30 and the controller 32,
Although the flow rate of the control valve 33 attached to 8 was adjusted,
A control valve (not shown) may be attached to the treated water discharge pipe 22 to adjust the flow rate of the control valve.

As the vacuum means, a combination of a steam ejector and a barometric condenser can be used instead of the vacuum pump 26. As described above, the dissolved oxygen can be reduced to 10 μg / l or less only by substantially eliminating the gaseous phase below the packed layer 12, but the present invention further requires the dissolved oxygen to be 2 μg / l or less. Means as described below are added.

That is, a part of the treated water drained by the drain pump 24 is supplied to the heat exchanger 62. The heat exchanger 62 heats a part of the treated water supplied from the drain pump 24.

A part of the treated water heated by the heat exchanger 62 is mixed with an inert gas supplied through a valve 66, that is, a nitrogen gas.
Through the filling layer 12. Here, the nitrogen gas may be completely dissolved or may be partially dissolved.

As described above, a part of the treated water after the degassing treatment is heated and then mixed with nitrogen gas to form the packed bed 1.
It is returned in 2. This return treated water is heated,
In addition, since a large amount of nitrogen gas is mixed, the nitrogen gas is returned to the packed bed 12, thereby increasing the saturated steam pressure and the nitrogen partial pressure in the gas phase in the packed bed 12. Therefore,
Removal of oxygen from the water flowing through the packed bed 12 is promoted accordingly.

Then, by heating and returning the treated water (partial pressure reducing fluid) in which the nitrogen gas is dissolved and mixed into the packed bed 12, the oxygen partial pressure in the gas phase in the packed bed 12 is reduced. The deaeration effect can be further enhanced. In particular, in the basic configuration 1 , the gas phase space is substantially eliminated below the packed bed 12, and the partial pressure reducing fluid is introduced into the packed bed 12, so that the deaeration action is actually performed. The oxygen partial pressure at the place where the offense is occurring is reduced, the treatment efficiency is increased, and the space below is reduced, so that the deaeration efficiency can be prevented from being deteriorated due to the space.

In the basic structure 1 shown in FIG. 1, a part of the treated water is heated and a mixture of the heated water and nitrogen gas is supplied into the packed bed 12, but a part of the treated water is supplied. The partial pressure of the gas dissolved in the water can be reduced only by heating and supplying only the heated water into the packed bed 12, thereby promoting the removal of oxygen. On the other hand, even if a mixture of the treated water and the nitrogen gas is supplied into the packed bed 12 without heating part of the treated water, the partial pressure of the oxygen gas dissolved in the water is similarly increased. Since it can be lowered, the removal of oxygen is promoted. Also, by supplying heated steam or nitrogen gas itself directly to the packed bed 12 instead of superheated water or treated water mixed with nitrogen gas, the partial pressure of oxygen dissolved in water can be reduced. Removal is promoted. When supplying the heated water or the heated steam into the degassing tower, not into the packed bed 12, but into the treated water storage chamber 16, the saturated vapor in the gas phase in the packed bed 12 can be increased to some extent. The removal of oxygen from the water is thus facilitated. However, if heating water or heating steam is supplied into the degassing tower, it is preferable to supply the inside of the packed bed 12 rather than the inside of the treated water storage chamber 16.

[ Basic Configuration 2 ] FIG. 2 shows a configuration of the basic configuration 2 . In the basic configuration 2 , the heater 100 is attached to the treated water supply pipe 18 to heat the treated water itself supplied to the degassing tower.

The other parts are the heat exchanger 62, the spray nozzle 72, the gas cylinder 68, the valve 70,
66, 64, etc. are not installed.
The description is omitted.

By heating the water to be treated itself in this way, the saturated vapor pressure in the gas phase in the packed bed 12 increases, and the removal of oxygen from the water is accelerated accordingly.

As the heater 100, an electric heater or a heat exchanger is used.

[ Basic Configuration 3] FIG. 3 shows a configuration of the basic configuration 3 . In this basic configuration 3 , a heater 100a is provided in the packed layer 12, and
The water to be treated that falls through the packed bed is directly heated.

The other parts are the heat exchanger 62, the spray nozzle 72, the gas cylinder 68, the valve 70,
66, 64, etc. are not installed.
The description is omitted.

By heating the water to be treated falling through the packed bed 12 as described above, the saturated vapor pressure in the gas phase in the packed bed 12 is increased, and the removal of oxygen from the water is accelerated accordingly.

As the heater 100a, an electric heater, hot water, a coiled tube through which heated steam flows, or the like is used.

In this basic configuration , the heater 100a is the
2, the heater 100a may be provided in the treated water storage chamber 16 to heat the treated water. Thus, even if the treated water is heated, the saturated vapor pressure in the gas phase in the packed bed 12 can be increased to some extent, and the removal of oxygen from the water is accelerated accordingly. However, heater 100
If a is provided, it is preferable to provide the inside of the packed bed 12 rather than the treated water storage chamber 16.

The heater 100 is connected to the water supply pipe 18 to be treated.
It is needless to say that the heater 100a may be additionally provided in the filling layer 12 in addition to the above.

[ First Embodiment ] FIG. 4 shows the configuration of the first embodiment. In the first embodiment, two packed beds are provided in one degassing tower 10 and 2
It has a stage configuration.

That is, a first packed bed 34 and a second packed bed 36 are provided inside the degassing tower 10. Then, the upper space of the first packed layer 34 is the first degassing chamber 38,
The upper part of the filling layer 36 is a second degassing chamber 40.

The spraying device 20 is arranged in the first degassing chamber 38 and sprays the water to be treated to the first packed bed 34.

Further, the second filling layer 36 is made of a porous mesh plate 3.
6a, the first packed layer 34 is supported by a bottom plate 34a without holes. In addition, this bottom plate 34
A water sealing device 42 is provided at the center of “a”, and water seals the bottom of the first filling layer 34. Further, the water sealing device 42
Is connected to a spraying device 44 disposed in the second degassing chamber 40, and the first treated water flowing out from the water sealing device 42 is treated as second water through the second degassing chamber 40. 36.

A first vacuum pump (VP1) 46 is connected to the first deaeration chamber 38 via an exhaust pipe 48, and a second vacuum pump (VP2) is connected to the second deaeration chamber 40. 5
0 is connected via the exhaust pipe 52. The first and second vacuum pumps 46 and 50 depressurize the first and second deaeration chambers 38 and 40, respectively.

FIG. 5 is a view showing a schematic configuration of the water sealing device 42, which comprises a pipe 42a penetrating the bottom plate 34a and a cup 42b inside the first filling layer 34, which covers the upper end of the pipe 42a. . And cup 42b
Has an opening at its lower end, so that the first filling layer 34
The primary treated water flowing down the inside enters the cup 42b from the lower end of the cup 42b, and overflows and flows into the pipe 42a. Therefore, below the first filling layer 34,
A water layer W is formed, whereby the first degassing chamber 38 and the second
The deaeration chamber 40 is completely sealed with water.

The treated water storage chamber 16 is provided below the second packed bed 36, and the drainage pump 24 is connected to the treated water storage chamber 16 through the discharge pipe 22, and the control device 32 is controlled by the output of the differential pressure gauge 30. The control of the valve 33 to maintain the treated water level in the treated water storage chamber 16 substantially the same as that of the eye plate 36a is the same as in the basic configuration 1 described above.

According to such an apparatus, the water to be treated containing a large amount of dissolved oxygen is firstly subjected to rough removal of the dissolved oxygen in the first degassing chamber 38 and the first packed bed 34. Then, the primary treated water from which the dissolved oxygen has been roughly removed is supplied to the second degassing chamber 40 via the spraying device 44. This second deaeration chamber 40
After that, the dissolved oxygen is removed by the same operation as in the basic configuration 1 described above.

As described above, the first deaeration chamber 38 and the first packed bed 3
In order to roughly remove dissolved oxygen, effective treatment is performed in the second degassing chamber 40 and the second packed bed 36, and the dissolved oxygen concentration in the treated water can be made sufficiently low. .

In particular, in this embodiment, since the water sealing device 42 is provided and the second deaeration chamber 40 and the first deaeration chamber 38 are completely separated, the processing becomes a complete multi-stage processing, and a short circuit occurs. Nothing to do. Further, as will be described later, the degree of vacuum and the like of the first degassing chamber 38 and the second degassing chamber 40 can be set separately, and effective degassing processing can be performed.

In the first embodiment described above, the packed bed is provided in two stages inside the degassing tower 10, but the number of packed beds is not limited to two, but may be three or more. it can. In the case where the packed layer is formed in a plurality of stages as described above, it is preferable that the porous mesh plate 36a is used only below the final packed layer, and the lower portion of the upper packed layer is water-sealed by the water sealing device 42.

In the first embodiment in which the packed layers are provided in two stages, the vacuum pumps 46 and 50 are connected to the first deaeration chamber 38 and the second deaeration chamber 40, respectively. Air chamber 3
A vacuum pump 46 may be provided via an exhaust pipe 48 in the inside 8 or at one location above the packed bed 34.

When a plurality of vacuum pumps are used,
It is preferable that the degree of vacuum of the vacuum pump be changed sequentially so that the degree of vacuum increases downward.

The position of the water level is not limited to substantially the same position as the lower end of the eye plate 36a. The water level may be slightly above the eye plate 36a, or an ejector may be used instead of the vacuum pump. Is as described above.

In the present embodiment, the spray nozzle 72 is provided in the second packed bed 36 for supplying the partial pressure reducing fluid, and the treated water in which the nitrogen gas is mixed and dissolved while being heated is provided. Supplied here.

That is, similarly to the basic configuration 1 , a part of the treated water drained by the drain pump 24 is
The nitrogen gas supplied via the valve 66 is mixed (partially dissolved) with this gas and introduced into the packed bed 12 via the valve 70 and the spray nozzle 72.

As a result, when the oxygen concentration in the second stage of the two-stage treatment becomes low, the dissolved oxygen is removed by reducing the partial pressure of oxygen, and the dissolved oxygen in the treated water is reduced to a low concentration of 2 μg / l or less. Can be removed stably.

It should be noted that the heating of the treated water and the mixing of the nitrogen gas may be performed alone or that the heated steam or the nitrogen gas may be directly supplied into the second packed layer 36 as described above. It is on the street.

[ Second Embodiment ] FIG. 6 shows an apparatus according to a second embodiment. In this device, the first
A spray nozzle 74 is also provided in the packed layer 34, and heated and nitrogen-treated water is supplied to the spray nozzle 74. Therefore, even in the gas phase in the first packed layer 34, the oxygen partial pressure is reduced, and the degassing effect can be increased.

As described above, in the present embodiment, the heating of the treated water and the mixing of the nitrogen gas may be performed independently, or heated steam may be used.

[ Third Embodiment] In the above-described basic structures 1 to 3, the first and second embodiments, the perforated plate 12a or the bottom plate 34a and the perforated plate 36a are provided, and the filling layer 12 or the first filling The layer 34 and the second packed layer 36 were formed, and the treated water storage chamber 16 was formed below the layer 34 and the second packed layer 36. However, this eye plate can be omitted.

FIG. 7 is a view showing the configuration of the third embodiment in which the face plate is omitted from the configuration shown in the basic configuration 1. The filler is directly filled in the degassing tower 10, and the packed layer 12 is formed. Have been. It is also preferable to increase the particle size of the filler at the lowermost portion of the filler layer 12 so that the filler functions as a support material layer.

In such an apparatus, the treated water level L
Is located below the packed bed 12, no gaseous space is created below the packed bed 12, so that a suitable deaeration can be performed as in the above-described apparatus. If the water level rises more than necessary, the effective volume for degassing decreases and the degassing effect deteriorates, as in the case described above.

As described above, in the present embodiment, the heating of the treated water and the mixing of the nitrogen gas may be performed independently, or heated steam may be used.

[Structure of Eyepiece] In the basic structures 1 to 3 and the first to third embodiments,
Although the eye plates 12a and 36a are flat, the eye plates 12a and 3a
It is also preferable that 6a be corrugated.

FIG. 8 shows an example of the structure of the corrugated eye plates 12a and 36a. In this example, the punching metal is formed in a corrugated shape. In a large-sized apparatus, a disk-shaped corrugated plate may be formed by connecting a horizontally long plate (a single plate) having a width indicated by d in the figure. Also, using a punching metal having holes formed at equal intervals,
a and 36a may be formed, but holes may be provided only on the slopes of the mountain indicated by S in the figure.

As described above, by forming the eye panels 12a and 36a in a corrugated shape, the substantial area of the eye panels 12a and 36a can be increased. Therefore, the treated water that has passed through the packed layers 12 and 36 can be more effectively discharged downward.

Incidentally, such corrugated plates are connected to the eye plates 12a, 36.
When used as a, it is preferable to set the treated water level in the treated water storage section at the lower ends of the eye panels 12a and 36a. However, it can be said that the space between the upper ends of the eye plates 12a and 36a is the inside of the eye plate.
When using 36a, the best degassing effect can be obtained if the treated water level is maintained between the downstream part and the upstream part.

[Other Configurations] In the present invention, the temperature of degassed treated water is raised by 1 ° C. or more, and the heated treated water is introduced into the vacuum degassing tower at a ratio of 0.01 or more with respect to the amount of water to be treated. Good.

When nitrogen gas is mixed with a part of the treated water, the rate of vacuum is set to 0.1 or more with respect to the displacement of 1, depending on the scale of the vacuum deaerator and the specification and capacity of the vacuum pump. Preferably, it is introduced into a degassing tower.

In the above embodiment, heated deaerated water or nitrogen gas or deaerated water in which nitrogen gas is dissolved is supplied from the spray nozzle 72 provided below the packed layer 12 to the filling layer 1.
Although the structure is such that it flows upward in the interior 2, a perforated pipe may be provided in the tower so that it can be injected into the entire packed bed 12. FIG. 9 shows a configuration example of a pipe-shaped spray nozzle 72 inserted and arranged in the packed bed. In this example, the spray nozzle 72 is formed in a vertical pipe shape. A large number of holes are formed around the pipe-shaped spraying nozzle 72, and the supplied heated and / or nitrogen-containing treated water is blown out from the holes to form the packed bed 12.
Inside is distributed and supplied.

As described above, by dispersing and supplying the introduction fluid to the entire inside of the packed bed 12, the partial pressure of oxygen in the gas phase in the packed bed 12 can be uniformly reduced, and more stable processing is performed. . Moreover, such a pipe-shaped spraying nozzle does not necessarily have to be provided at the center.

FIG. 10 shows a configuration of still another fourth embodiment. In this example, a spray nozzle 74 is disposed in the treated water storage chamber 16, from which aeration by nitrogen gas is performed. . The nitrogen gas thus introduced into the treated water storage chamber rises and reaches inside the packed bed 12.
Thus, the oxygen partial pressure of the gas phase in the packed layer 16 is reduced, and the removal of dissolved oxygen is promoted.

Note that the above-described configurations shown in FIGS.
It can be applied to any of the above embodiments.

Further, in the above embodiment, the purpose is to remove dissolved oxygen, but it can be widely used for removing any dissolved gas such as carbon dioxide gas and nitrogen. At this time, the kind of gas introduced into the degassing tower 10 may be anything (other than oxygen) as long as it is not for the purpose of removal.

For the purpose of removing oxygen, an inert gas (argon, helium) other than nitrogen, or a gas other than oxygen that is hardly soluble in water, such as hydrogen, may be used.

Although the outlet water of the vacuum deaerator is used as the deaerated water to be heated, the invention is not limited to this, and any deaerated water after the treatment by the vacuum deaerator may be used. Further, the tank at the latter stage of the vacuum deaerator is usually sealed with nitrogen for the purpose of preventing the re-dissolution of oxygen, and thus is nitrogen-saturated water. Therefore, when deoxygenation is intended by supplying such a nitrogen-saturated water to the packed bed, the partial pressure of oxygen can be reduced, which is very effective.

FIG. 11 shows the configuration of the fifth embodiment. In this example, instead of removing the heat exchanger 62, gas cylinder 68, spray nozzle 72, and valves 64, 66, and 70 in FIG. FIG. 12 shows a configuration of a sixth embodiment in which a heater 100 is attached to a pipe 18. In this example, a heat exchanger 62, a gas cylinder 68, a spray nozzle 72, valves 64 and 66 in FIG. , 70
Instead of removing the heater 100 in the second packed bed 36.
a is added, and the other configuration is the same as that of FIG.

As described above, by heating the water to be treated by the heater 100 or by heating the water to be dropped falling through the second packed bed 36 by the heater 100a, the saturated steam in the gas phase in the packed bed 12 can be also heated. The pressure can be increased, which facilitates the removal of oxygen from the water.

Although the heater 100a is provided in the second filling layer 36 in FIG. 12, the heater 100a may be provided in the first filling layer 34, or the first filling layer 3 may be provided.
4 and the second filling layer 36.

The heater 100 used in FIG.
The heater 100a used for the basic structure 2 and the basic structure 2
As described in the third section .

[0098]

EXAMPLE Here, the result of actually manufacturing and operating the device of the first embodiment will be described below.

[Conditions] First, the degassing tower 10 has a diameter of 400
mmφ, height 12000mm, first degassing chamber 38 height 70
0 mm, the height of the first packed layer 34 is 3500 mm, the height of the second degassing chamber 40 is 900 mm, and the height of the second packed layer 36 is 3500 mm.
And The gas-liquid contact material of the first and second packed layers 34 and 36 is a combination of a coil and a ring. One material has an outer diameter of 51 mm, a height of 19 mm, and 1 m ³
25,000 pieces per unit, a surface area of 180 m ² per 1 m ³ , and a space ratio of 89% were used (trade name: Terralet packing (Nippon Steel Chemical Co., Ltd.)).

Then, the water to be treated was supplied at 10 m ³ / H. The temperature of the supplied water to be treated was 23 ± 1 ° C., and the dissolved oxygen was 8 to 9 mg / l. The first and second deaeration chambers 3
The pressures of 8 and 40 are 33 Torr and 22 Torr, respectively.
r.

[Experimental Result 1] Under the above experimental conditions, all valves 64, 66, and 70 in FIG. 4 were closed, and the operation was performed without returning the treated water to the packed bed 36. The dissolved oxygen concentration of the resulting treated water was 5 μg / l.

[Experimental Result 2] Next, the valve 70 of FIG.
Open valve 64, close valve 66, pass through heat exchanger at 28 ° C
(Heated by 5 ± 1 ° C. with respect to the temperature of the water to be treated) Degassed water was continuously introduced from the spray nozzle 72 into the second packed bed 36 at a flow rate of 0.5 m ³ / H to operate. went. The obtained dissolved oxygen concentration was 1 μg / l. At this time, almost no increase in the temperature of the treated water discharged from the degassing tower 10 was observed.

[Experimental Result 3] Under the above experimental conditions, the valves 70 and 66 in FIG. 4 were opened, the valve 64 was closed, and nitrogen gas was continuously filled from the spray nozzle 72 at the flow rate of 0.1 Nm ³ / H. The operation was performed by introducing into the layer 36. The obtained dissolved oxygen concentration was 1 μg / l.

[Experimental Result 4] Under the above experimental conditions, all of the valves 64, 66, and 70 in FIG. 4 were opened, and degassing was performed at 28 ° C. through the heat exchanger 62 at a flow rate of 0.5 m ³ / H. The operation was performed by dissolving nitrogen gas in water at a flow rate of 0.1 Nm ³ / H, and continuously introducing the gas into the second packed bed 36 from the spray nozzle 72. The resulting dissolved oxygen concentration is 0.5μ
g / l.

"Comparative Example" The vacuum deaerator shown in the embodiment was modified as shown in FIG. A lower degassing chamber 88 is provided as in the conventional method, a space is formed in the lower degassing chamber 88, and heated degassed water or inert gas can be introduced into the lower degassing chamber 88. As described above, the supply pipe 92 provided with the valve 90 was connected to the spray nozzle 94 provided in the lower degassing chamber 88. The supply pipe 92 receives a supply of deaerated water mixed with heating or nitrogen. Other than that, the experiment was performed under the same conditions as above.

[Comparative result 1] Under the above experimental conditions, FIG.
The valves 64, 66, 70, and 90 were all closed to operate. The obtained dissolved oxygen concentration was 25 μg / l.

[Comparative result 2a] Under the above experimental conditions, FIG.
The valves 70 and 66 of No. 3 are closed, the valves 64 and 90 are opened, and the degassed water heated to 28 ° C. through the heat exchanger is continuously degassed in the lower part at a flow rate of 0.5 m ³ / H from the spray nozzle 94. It was introduced into the room and operated. The resulting dissolved oxygen concentration is 10μ
g / l.

[Comparative result 2b] Under the above experimental conditions, FIG.
The valves 70 and 64 of No. 3 are opened, the valves 66 and 90 are closed, and the deaerated water heated to 28 ° C. through the heat exchanger 62 is continuously supplied from the spray nozzle 72 at a flow rate of 0.5 m ³ / H. The operation was performed by introducing into the packed bed 36. The obtained dissolved oxygen concentration was 20 μg / l.

[Comparative result 3a] Under the above experimental conditions, FIG.
3, the valves 70 and 64 are closed, and the valves 66 and 90 are opened, and nitrogen gas is sprayed from the spray nozzle 94 at a flow rate of 0.1 Nm ³ /
H was continuously introduced into the lower degassing chamber 88 for operation.
The obtained dissolved oxygen concentration was 10 μg / l.

[Comparative result 3b] Under the above experimental conditions, FIG.
3 and the valves 64 and 90 are closed, and nitrogen gas is sprayed from the spray nozzle 72 at a flow rate of 0.1 Nm ³ /
H was continuously introduced into the second packed bed 36 to perform the operation.
The obtained dissolved oxygen concentration was 20 μg / l.

[Comparative result 4a] Under the above experimental conditions, FIG.
3 valve 70 was closed, valves 64, 66, and 90 were opened, and the flow rate of 0.5 m heated to 28 ° C. through heat exchanger 62
Nitrogen gas is supplied at a flow rate of 0.1 Nm ³ with respect to ³ / H degassed water.
/ H and then continuously introduced from the spray nozzle 94 into the lower degassing chamber 88 for operation. The obtained dissolved oxygen concentration was 5 μg / l.

[Comparative result 4b] Under the above-described experimental conditions, FIG.
The valves 70, 64, 66 of No. 3 were opened, the valve 90 was closed, and the flow rate of 0.5 m heated to 28 ° C. through the heat exchanger 62
Nitrogen gas is supplied at a flow rate of 0.1 Nm ³ with respect to ³ / H degassed water.
/ H, and continuously introduced from the spray nozzle 72 into the second packed bed 36 to perform the operation. The obtained dissolved oxygen concentration was 15 μg / l.

[0113]

As described above, according to the present invention,
In a vacuum degassing apparatus in which the degassing effect is increased by substantially eliminating a gas phase space below the packed bed, degassed treated water heated in the packed bed, heated steam, an inert gas, or By introducing deaerated water in which an inert gas is dissolved, or by heating the water to be supplied to the deaeration tower or the water to be dropped in the packed bed, the deaeration effect can be further improved. Can rise.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a basic configuration 1. FIG.

FIG. 2 is a diagram showing a configuration of a basic configuration 2 .

FIG. 3 is a diagram showing a configuration of a basic configuration 3 .

FIG. 4 is a diagram showing a configuration of the first embodiment.

FIG. 5 is a diagram showing a configuration of a water sealing device.

FIG. 6 is a diagram illustrating a configuration of a second embodiment.

FIG. 7 is a diagram illustrating a configuration example of a third embodiment.

FIG. 8 is a diagram showing a configuration of an eyeboard.

FIG. 9 is a diagram showing a configuration of a spray nozzle.

FIG. 10 is a diagram illustrating a configuration of a fourth embodiment.

FIG. 11 is a diagram showing a configuration of a fifth embodiment.

FIG. 12 is a diagram illustrating a configuration of a sixth embodiment.

FIG. 13 is a diagram illustrating a configuration of a comparative example.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 10 degassing tower, 12 packed bed, 14 degassing chamber, 16 treated water storage chamber, 20 spraying device, 24 drainage pump, 26
Vacuum pump, 30 differential pressure gauge, 32 controller, 34
1st packed bed, 36 2nd packed bed, 38 1st deaeration chamber, 4
0 second degassing chamber, 42 water sealing device, 44 spraying device, 4
6 1st vacuum pump, 50 2nd vacuum pump, 62 heat exchangers, 64, 66, 70 valves, 68 gas cylinders, 72 spray nozzles, 100 heaters.

Continuation of the front page (56) References JP-A-6-210272 (JP, A) JP-A-6-246259 (JP, A) JP-A-53-43677 (JP, A) JP-A-61-230781 (JP, A) (A) JP-A-4-330905 (JP, A) JP-A-61-132007 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/20 B01D 19/00

Claims (2)

(57) [Claims] 1. A gas-liquid contact material packed layer is formed in a plurality of stages in an airtightly formed degassing tower, and water to be treated is supplied from above the degassing tower, and from below the lowermost packed bed. Drains the treated water,
The gas in the degassing tower is discharged by vacuum means from at least the uppermost packed bed, and the treated water level in the degassing tower is substantially the same as the lower end of the lower packed bed or from the lower end of the packed bed. In a vacuum deaerator that is set at a slightly higher position, a deaeration process that dissolves heated deaeration water, heated steam, inert gas, and inert gas in at least the lowermost packed bed While introducing one or more fluids selected from water, a bottom plate without holes is placed at the bottom of the stage other than the bottom,
The bottom plate supports a packed layer of a gas-liquid contact material, and the bottom plate is provided with a water seal portion. The bottom of the packed layer is sealed with water to obtain treated water having a dissolved oxygen concentration of 2 μg / l or less. Vacuum deaerator. The apparatus according to the claim 1, as well as discharging gas in a separate vacuum pump from the filling layer above each stage, the degree of vacuum sequentially vacuum means such that a vacuum degree is higher downward A vacuum deaerator characterized by being changed.