JP3315319B2 - 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 VLSI, highly purified ultrapure water is used to prevent impurities from being mixed. In this ultrapure water, it is desired that the concentration of dissolved oxygen (DO) be as low as possible. For example, ultrapure water used for cleaning a semiconductor wafer is required to remove dissolved oxygen to 10 μg / l (ppb) or less.

[0003] A vacuum deaerator is used to remove dissolved oxygen from water. This vacuum deaerator introduces water to be treated into a hermetically formed deaeration chamber and exhausts the gas inside using a vacuum pump or the like. As a result, the pressure in the degassing chamber is reduced, and the oxygen partial pressure in the degassing chamber decreases. Therefore, dissolved oxygen in the water to be treated is removed until the reduced oxygen partial pressure equilibrates. The degassing chamber is filled with a gas-liquid contact material to increase the surface area of water.

[0004] Here, it has been difficult to reduce the dissolved oxygen to the above concentration using a conventional one-stage vacuum deaerator. For example, to obtain a dissolved oxygen concentration of 10 μg / l at 25 ° C., the oxygen partial pressure in the degassing chamber must be reduced to about 0.15 Torr or less. On the other hand, the saturated dissolved oxygen concentration at 25 ° C. is about 8500 μg-O ₂ / l,
In order to obtain a dissolved oxygen concentration of 10 μg / l in the stage, oxygen in the degassing chamber must be exhausted to this region. Therefore, a large-displacement exhaust device that can exhaust a large amount of oxygen originally existing as dissolved oxygen in the water to be treated is required, and the operating cost is increased, which cannot be realized with a practical device.

[0005] In order to solve this problem, a multistage vacuum deaerator has conventionally been used. This device has a configuration in which airtightly formed degassing chambers are connected in multiple stages in series. A water seal mechanism is provided between each degassing chamber so that treated water can flow but gas cannot flow, and each degassing chamber has an exhaust gas that discharges gas therein. The devices are each connected.

In this multi-stage vacuum deaerator, treated water is sequentially passed from an upstream deaeration chamber having a relatively high oxygen partial pressure to a downstream deaeration chamber having a relatively low oxygen partial pressure, and the dissolved water in the treated water is dissolved. Oxygen is gradually removed by a plurality of degassing chambers. As a result, the dissolved oxygen of the treated water flowing into the degassing chamber becomes lower in the later stage, and the exhaust gas can be relatively easily exhausted in the final stage to the oxygen partial pressure that achieves the dissolved oxygen concentration of 10 μg / l.

Further, the present applicant has previously proposed (Japanese Patent Application No.
As described above, if the gas phase space below the second packed bed in the two-stage vacuum degassing apparatus is substantially eliminated, the degassing effect is dramatically increased, and the two-stage vacuum degassing device can easily be used. It is possible to achieve a dissolved oxygen concentration of 10 μg / l.

[0008]

However, in the above-mentioned multistage vacuum deaerator, a lower oxygen partial pressure is required at a later stage, so that an exhaust device with a larger displacement is required at a later stage. Further, as a result, the lower the partial pressure of water other than water vapor such as oxygen becomes, the lower the suction pressure becomes. For these reasons, there is a problem that the later the exhaust device, the higher the initial cost and running cost.

Further, in recent years, with the ultra-high integration of LSI, ultra-pure water degassed to a higher degree such as dissolved oxygen of 1 μg / l or less has been demanded. It is possible to meet this demand by increasing the number of stages of the multi-stage vacuum deaerator and increasing the displacement of the exhaust device.

However, especially in the final stage, the dissolved oxygen 1
In order to obtain μg / l, the oxygen partial pressure in the degassing chamber is set to 0.015T.
In this region, the influence of a small amount of oxygen entering the degassing chamber from outside air via a flange joint or the like cannot be ignored.
Therefore, the exhaust device in the final stage needs to have a very large displacement, and both the initial cost and the running cost are high, and a practical device cannot be obtained.

The present invention has been made based on these recognitions, and has been made based on the exhaust energy in multistage vacuum degassing.
It is an object of the present invention to provide a vacuum deaerator with reduced cost.

[0012]

SUMMARY OF THE INVENTION A vacuum deaerator of the present invention is formed in a hermetically sealed manner, and a plurality of degassers connected in series for sequentially circulating treated water therein and degassing dissolved gases in the treated water. A water seal provided between the air chamber and the plurality of deaeration chambers to block gas flow between the deaeration chambers and to flow treated water from the upstream deaeration chamber to the downstream deaeration chamber. Mechanism and upstream
A first exhaust device for exhausting gas in the deaeration chamber on the side,
A second exhaust device for exhausting gas from the degassing chamber on the side.
The outlet pipe of the second exhaust device is connected to the first exhaust device.
To the deaeration chamber on the upstream side where the pressure is reduced .

In a conventional multi-stage vacuum deaerator, an outlet pipe of an exhaust device for exhausting each deaeration chamber is opened to the atmosphere.
In this case, each of the exhaust devices changes from the deaeration chamber pressure near the saturated steam pressure at that temperature (20 to 40 Torr) to the atmospheric pressure (7 to 40 Torr).
The pressure must be exhausted up to 60 Torr, that is, against a pressure difference of 720 to 740 Torr. Therefore, a large amount of energy is required, and the running cost increases drastically as the displacement increases.

The present invention relates to a multi-stage vacuum deaerator ,
A first exhaust device that exhausts gas in an upstream deaeration chamber;
A second exhaust device that exhausts gas in the downstream degassing chamber;
And the outlet pipe of the second exhaust device is connected to the first exhaust device.
Therefore , the above-mentioned problem is solved by connecting to the degassing chamber on the upstream side where the pressure is reduced . That is,
For example, in a vacuum deaerator having two deaeration chambers, a gas outlet of a second exhaust device that exhausts a downstream deaeration chamber is provided by a first exhaust device that exhausts an upstream deaeration chamber. By being sucked, for example, a pressure of 20 to 40 Torr
By opening the degassing chamber on the upstream side where the pressure is reduced, the pressure difference between the front and rear of the second exhaust device can be made extremely small, thereby installing a vacuum pump as an exhaust device to be used. Costs and running costs can be significantly reduced.

[0015]

In the case where the gas outlet of the second exhaust device is connected to the upstream deaeration chamber, the connection point is the first exhaust gas.
If it is provided below the connection point of the inlet pipe of the exhaust device, the partial pressure of oxygen in the lower part of the upstream degassing chamber is reduced, and the degassing efficiency can be further improved.

[0017]

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.

[0018] "Basic Configuration Example" 1, shows the basic structure of the vacuum degassing apparatus according to the present invention
An example of a basic configuration is conceptually shown. For the sake of simplicity, the figure shows a two-stage vacuum degassing tower as an example,
It goes without saying that the present invention is also effective in a multistage vacuum degassing column such as a four-stage type.

In FIG. 1, the interior of a vacuum degassing tower 1 is partitioned into a first-stage degassing chamber 4 and a second-stage degassing chamber 5, and the respective degassing chambers 4 and 5 are brought into gas-liquid contact. A filling layer 6 of the member is provided. A water seal / water spray mechanism 7 is provided between the first-stage deaeration chamber 4 and the second-stage deaeration chamber 5, and a first-stage deaeration chamber 4 is provided.
Although the treated water flows toward the second-stage degassing chamber, the gas in the degassing chamber 5 cannot flow to the degassing chamber 4 via the water sealing / sprinkling mechanism. The first-stage degassing chambers 4 and 2
The second-stage deaeration chamber 5 is partitioned by a non-porous bottom plate 72, and a perforated plate 73 is provided below the packed layer 6 of the second-stage deaeration chamber.
Is attached.

The first-stage degassing chamber 4 is provided with a sprinkling mechanism 3 for sprinkling the water to be treated supplied through the water introduction pipe 2. In the upper space of the first-stage degassing chamber 4, a first-stage bleed pipe 13 connected to the first-stage vacuum pump 10 is opened, and the exhaust of the vacuum pump 10 is open to the atmosphere. In the upper space of the second-stage degassing chamber 5, a second-stage bleed pipe 14 connected to the second-stage vacuum pump 11 is opened. The other end of the outlet pipe 15 which is a gas outlet of the second-stage vacuum pump 11 is connected to a first-stage bleed pipe 13 at a connection point 12. Therefore, the second-stage vacuum pump 11 supplies the exhaust gas from the second-stage vacuum chamber 5 to the inlet side of the first-stage vacuum pump 10. Therefore, the second stage vacuum pump 11
Since the pressure difference between the inlet side and the outlet side is very small, the second stage vacuum pump 11 can use a pump with a low head. A pump 9 is connected to the bottom of the second-stage degassing chamber 5 through a treated water extraction pipe 8, and the degassed treated water is pumped out of the system through the treated water extraction pipe 8. It is extracted. As the first-stage vacuum pump 10 and the second-stage vacuum pump 11, both positive displacement pumps are preferable.

The water to be treated is supplied from the sprinkling mechanism 3 onto the packed bed 6 in the first-stage deaeration chamber 4. In the first stage degassing chamber 4,
Since the first-stage vacuum pump 10 is in a vacuum state, the first-stage dissolved gas is removed here. Then, the treated water is supplied into the second-stage deaeration chamber 5 via the water sealing / sprinkling mechanism 7. The inside of the second-stage degassing chamber 5 is brought into a high vacuum state by the second-stage vacuum pump 11. So 2
Dissolved gas remaining in the treated water supplied from the stage degassing chamber 4 is further removed.

In this embodiment, since the outlet pipe 15 of the second-stage vacuum pump 11 is connected to the first-stage bleeding pipe 13 at the connection point 12, it is possible to use a low-lift vacuum pump as described above. The power energy required in the second stage vacuum pump 11 can be drastically reduced.

That is, the pressure in the second-stage deaeration chamber of the two-stage vacuum deaerator for aiming at a dissolved oxygen concentration of 10 μg / l is about 20 Torr. In the conventional apparatus, the outlet pipe 15 of the second-stage vacuum pump 11 is open to the atmosphere at a pressure of about 760 Torr, and energy for maintaining this difference is required. However, in this example, the second-stage vacuum pump 11
Outlet pipe 15 is the first-stage bleed pipe 1 with a pressure of about 40 Torr.
Open at 3. Therefore, the energy required to obtain the same second stage displacement is drastically reduced.

First Embodiment FIG. 2 shows an example of a vacuum deaerator according to the present invention ( first embodiment).
Is shown. In this example, the outlet pipe 15 of the second-stage vacuum pump 11 is opened directly to the first-stage degassing chamber 4 instead of in the middle of the first-stage bleeding pipe 13. For the sake of simplicity, this figure shows a two-stage vacuum degassing column as an example,
It goes without saying that the present invention is also effective in a multistage vacuum degassing tower such as a three-stage or four-stage vacuum degassing column.

As described above, by opening the outlet pipe 15 of the second-stage vacuum pump directly to the first-stage degassing chamber 4 at the connection point 16, the power of the second-stage vacuum pump 11 can be changed in the same manner as in the example of FIG. Energy can be saved.

In particular, in the example of FIG.
Connection point 16 at which the outlet pipe 15 is opened to the first-stage degassing chamber 4
Are located below the connection point 17 of the first-stage bleed tube 13. By employing this arrangement, the degassing effect of the first-stage degassing chamber 4 is greatly improved by the effects described below.

Considering in detail the phenomenon occurring in each of the deaeration chambers 4 and 5 of the multistage vacuum deaerator, the treated water sprinkled from the sprinkling mechanism 3 gradually deaerates in the packed bed 6. Then, in the optimally designed apparatus, the dissolved oxygen concentration reaches the equilibrium with the oxygen partial pressure in the degassing chamber just near the bottom of the packed bed 6. Here, assuming that the gas-liquid contact efficiency in the packed bed 6 is constant in the vertical direction, a gas that is hardly soluble in water, such as oxygen, has a sufficiently high dissolution equilibrium speed between the gas phase / liquid phase (water). The amount of dissolved oxygen in the treated water released at a unit height into a vacuum is almost proportional to the dissolved oxygen concentration at that height.

Accordingly, the dissolved oxygen concentration is higher at the upper portion of the packed layer 6, and more oxygen is released from the treated water at the upper portion of the packed layer 6, and the released amount is smaller at the lower portion. It is ideal if the oxygen partial pressure can be kept higher in the upper part of the packed bed 6 and lower in the lower part. Will be exhausted preferentially.

However, the moving speed of oxygen in a vacuum is high. Therefore, it is considered that the oxygen partial pressure in the filling layer 6 becomes substantially constant in the vertical direction.

In order to lower the partial pressure of oxygen in the lower portion of the packed layer 6 from the upper portion, the partial pressure of gas other than oxygen in the lower portion of the packed layer 6 may be increased. For this purpose, means for increasing the water vapor pressure by heating the treated water stored in the lower part of the degassing chamber 4 or by flowing an inert gas from the lower part of the degassing chamber 4 to improve the degassing performance. It is possible. However, new costs such as an initial cost for providing a heating mechanism, a heating cost, and a cost of an inert gas occur.

However, with the configuration shown in FIG. 2,
The partial pressure of oxygen at the lower part of the first-stage packed bed 6 is reduced by the direct expelling effect by the steam forcibly supplied from the second-stage degassing chamber 5 or the heating effect by the heat generated when the steam condenses. Can be done. And this is 2
This is an effect associated with the exhaust cost reduction effect of the present invention in which the outlet pipe 15 of the first-stage vacuum pump is connected to the first-stage degassing chamber 4, and does not cause a new increase in cost as in other methods.

In the first and second embodiments, the treated water level in the second-stage degassing chamber 5 is controlled so as to be substantially equal to the lower end of the packed bed 6. As described in Japanese Patent Application No. 8-155315 previously filed by the present applicant, the effect of the degassing treatment can be further enhanced by substantially eliminating the gas phase space below the packed bed. Because. In the present invention, it is not an essential requirement that the treated water level in the second-stage degassing chamber 5 substantially coincides with the lower end of the packed bed 6, for example, a conventional space having a water surface by forming a space below the packed bed 6. It may be a vacuum deaerator.

FIG. 3 is a view showing a schematic configuration of a water seal portion 70 of the water seal / sprinkler device 7. This water seal part 70
Is a bottom plate 72 that separates the first-stage deaeration chamber 4 and the second-stage deaeration chamber 5
And the packed layer 6 of the first-stage degassing chamber 4
Inside the cup 7 that covers the upper end of the pipe 70a
0b. Since the cup 70b has an opening at its lower end, the filling layer 6 of the first-stage degassing chamber 4 is formed.
The primary treated water flowing down enters the cup 70b from the lower end of the cup 70b, and overflows and flows into the pipe 70a. Therefore, a water layer W is formed below the packed layer 6 in the first-stage degassing chamber 4, whereby the first-stage degassing chamber 4 and the second-stage degassing chamber 5 are completely sealed with water. become.
A water sealing mechanism shown in FIG. 3 is a water sealing mechanism that can cut off the gas flow between the degassing chambers and allow the treated water to flow from the upstream degassing chamber to the downstream degassing chamber. It is not limited to the mechanism.

Further, in the first embodiment, the connection point 16 of the outlet pipe 15 of the second-stage vacuum pump 11 to the first-stage degassing chamber 4 is formed as an opening in the tower wall of the vacuum degassing tower 1. However, it is also preferable to set the connection point 16 in the filling layer 6 so that the exhaust gas from the second-stage vacuum pump 11 can come into contact with the entire filling layer 6, and to provide a spraying device there.

Further, heated treated water or treated water in which an inert gas such as nitrogen gas is dissolved can be circulated in the second-stage degassing chamber 5. Thereby, the dissolved oxygen concentration in the treated water can be further reduced. Alternatively, nitrogen gas may be supplied to the second-stage degassing chamber 5 or the room may be directly heated.

Particularly, in the first embodiment, the second-stage degassing chamber 5
Is supplied into the first-stage degassing chamber 4. Therefore, effects such as heating and nitrogen introduction can be obtained also in the first-stage degassing chamber 4, and more effective degassing can be performed.

[0037] shows a modification of the vacuum degassing apparatus related to the present invention the "modification" FIG.

In this example, a three-stage degassing chamber is provided, and a first-stage degassing chamber 104 is provided inside the vacuum degassing tower 101.
And a second-stage deaeration chamber 105 and a third-stage deaeration chamber 106. Each of the deaeration chambers is provided with a filling layer 107 of a gas-liquid contact member. The first-stage degassing chamber 104 and the second-stage degassing chamber 10
5, the second-stage deaeration chamber 105 and the third-stage deaeration chamber 10
6, a water seal / sprinkler mechanism 108 is provided, and the treated water flows down sequentially from the first-stage deaeration chamber 104 to the third-stage deaeration chamber 106. Are not circulated to the second-stage degassing chamber 105, and the gas in the second-stage degassing chamber 105 is not circulated to the first-stage degassing chamber 104. The first-stage deaeration chamber 104 and the second-stage deaeration chamber 105, and the second-stage deaeration chamber 105 and the third-stage deaeration chamber 106 are partitioned by a non-porous bottom plate 172. A perforated plate 173 is provided below the packed layer 107 in the third-stage degassing chamber 106.
Is attached.

The first stage deaeration chamber 104 has a water spray mechanism 1 for spraying the water to be treated supplied through the water introduction pipe 102.
03 is provided. In the upper space of the first-stage degassing chamber 104, a first-stage bleeding tube 113 connected to the first-stage vacuum pump 110 is opened.
Exhaust is open to the atmosphere.

In the upper space of the second-stage degassing chamber 105,
Second-stage bleed tube 114 connected to second-stage vacuum pump 111
And the exhaust of the vacuum pump 111 is also open to the atmosphere.

Further, in the upper space of the third-stage degassing chamber 106, the third-stage bleeding tube 1 connected to the third-stage vacuum pump 115
16 is open and this third stage vacuum pump 1
The other end of the outlet pipe 117, which is the 15 gas outlet, is connected to the second-stage bleed pipe 114 at a connection point 118.

A pump 130 is connected to the bottom of the third-stage degassing chamber 106 via a treated water extracting pipe 120, and the degassed treated water is supplied to the pump 130 via a treated water extracting pipe 120. Is pulled out of the system.

The water to be treated is supplied from the water spray mechanism 103 to the first-stage deaeration chamber 104, the second-stage deaeration chamber 105, and the third-stage deaeration chamber 106.
Flows down sequentially and is degassed in each degassing chamber.

Also in this example, since the outlet pipe 117 of the third-stage vacuum pump 115 is connected to the second-stage bleeding pipe 114 at the connection point 118, the pressure difference before and after the third-stage vacuum pump 115 is extremely small. Therefore, a vacuum pump having a low head can be obtained, and the power energy required for the third-stage vacuum pump can be drastically reduced.

In the modification shown in FIG. 4, the outlet pipe 117 of the third-stage vacuum pump 115 is connected to the second-stage bleed pipe 114 of the second-stage vacuum pump . However, as shown in FIG. 2, this outlet pipe 117 is connected to the second stage deaeration chamber 10.
5, the configuration of the embodiment of the present invention is obtained.

In FIG. 4, the exhaust of the second stage vacuum pump 111 is open to the atmosphere.
Also, the gas outlet pipe of the first vacuum pump 1
Even if it is connected to the ten bleeding tubes or the first-stage degassing chamber 104, it may be acceptable.

As described above, according to the present invention, in a vacuum degassing tower having a plurality of degassing chambers connected in series, one or more of the gas outlets of the second and subsequent vacuum pumps are connected to the upstream side thereof. By connecting to the deaeration chamber on the upstream side, which is depressurized by the vacuum pump, the required power energy of the second and subsequent vacuum pumps connected to the decompression area can be reduced, and the initial cost and running cost can be reduced. Can be reduced.

[0048]

EXAMPLE Here, a device operable as both the basic configuration example and the device of the first embodiment was actually manufactured and operated, and the results of the operation will be described below.

FIG. 5 shows an outline of the experimental apparatus. The vacuum degassing tower 1 has a diameter of 400 mmφ, a height of 12000 mm, a first-stage degassing chamber height of 700 mm, a first-stage packed bed height of 3500 mm,
2nd stage deaeration chamber height 900mm, 2nd stage packed bed height 350
A 0 mm one was manufactured. The gas-liquid contact material of the first-stage and second-stage packed layers 6 is a combination of a coil and a ring having an outer diameter of 51 mm, a height of 19 mm, a surface area of 180 m ² per m ³ , and a space ratio of 89% ( Teralet packing (trade name: Nippon Steel Chemical Co., Ltd.) was filled so that the number of filling per 2 m ³ was 25,000.

The second-stage bleed pipe 14 is partitioned by valves 18 and 19, and the second-stage dry vacuum pumps 20 and 2 are respectively provided.
The stage was connected to a mechanical booster pump 21. The outlet pipe 22 of the mechanical booster pump is connected to the valve 2
The cells were partitioned at 3 and 24, respectively, and connected to the first-stage degassing chamber at a connection point 25 and to the first-stage bleed pipe 13 at a connection point 26, respectively. The vacuum pumps 20 and 21 used were capable of arbitrarily adjusting the shaft power by inverter control.

In such an apparatus, the water to be treated is
Feed at m ³ / H. The temperature of the supplied treated water is 23 ±
In pure water at 1 ° C., the dissolved oxygen was 8 to 9 mg / l. During the operation, the pressures in the first-stage deaeration chamber 4 and the second deaeration chamber 5 were 33 Torr and 22 Torr, respectively.

[Experimental Result 1] The valve 19 shown in FIG.
Close the valves 18, 23 and 24 and open the vacuum pumps 10 and 2
0 was driven. The vacuum pump 20 whose outlet side is open to the atmosphere was used for exhausting the second-stage degassing chamber 5. And 1
The pressure of the stage degassing chamber 4 and the pressure of the second degassing chamber 5 are each 33 To.
When adjusted to rr and 22 Torr, the dissolved oxygen concentration in the outlet water of the second-stage degassing chamber 5 became 5 μg / l. At this time, the shaft power of the vacuum pump 20 was 9 kW.

"Experimental Result 2" The vacuum pumps 10 and 21 were operated with the valves 18 and 24 shown in FIG. This configuration corresponds to the configuration of the basic configuration example . Then, when the inverter of the vacuum pump 21 was adjusted such that the dissolved oxygen concentration of the outlet water of the second-stage degassing chamber 5 became 5 μg / l, the shaft power was 1.2 kW.

[Experimental Result 3] The vacuum pumps 10 and 21 were operated with the valves 18 and 23 shown in FIG. This configuration corresponds to the configuration of the first embodiment. Then, the vacuum pump 21 is controlled so that the dissolved oxygen concentration of the outlet water of the second-stage degassing chamber 5 becomes 5 μg / l.
When the inverter was adjusted, the shaft power was 1.0 kW.

[Experimental Result 4] The vacuum pumps 10 and 21 were operated with the valves 18 and 23 shown in FIG. This configuration corresponds to the configuration of the first embodiment. When the shaft power was adjusted to 2.2 kW by adjusting the inverter of the vacuum pump 21, the dissolved oxygen concentration in the outlet water of the second-stage degassing chamber became 0.5 μg / l.

[0056]

As described above, according to the present invention,
By connecting the outlet pipe of the vacuum exhaust device of the second-stage deaeration chamber in the multistage deaerator to the decompression area of the first-stage deaeration chamber,
It is possible to provide treated water with low dissolved oxygen at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a basic configuration example .

FIG. 2 is a diagram illustrating a configuration of a first embodiment.

FIG. 3 is a diagram showing a configuration of a water sealing device.

FIG. 4 is a diagram showing a configuration of a modification .

FIG. 5 is a diagram showing a configuration of an experimental apparatus.

[Explanation of symbols]

1 vacuum degassing tower, 2 treated water inlet pipe, 3 water sprinkling mechanism,
4 1st-stage degassing chamber, 52nd-stage degassing chamber, 6 packed bed, 7
Water seal / water spray mechanism, 8 treated water drainage pipe, 9 pump, 1
0 1st stage vacuum pump, 11 2nd stage vacuum pump, 12
Connection point, 13 1st stage bleed tube, 14 2nd stage bleed tube,
15 2nd stage vacuum pump outlet piping, 16 connection point, 17
Connection point.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 1/20 B01D 19/00

Claims (2)

(57) [Claims] 1. A plurality of degassing chambers which are formed in an airtight manner, sequentially flow treated water therein, and degas dissolved gas in the treated water, and are provided between the plurality of degassing chambers connected in series. is, discharged with the blocking the flow of gas between the degassing chambers, a water sealing mechanism for circulating degassed chamber downstream treated water upstream from the degassing chamber, a degassing chamber gas on the upstream side And a second exhaust device for exhausting the gas in the downstream degassing chamber, wherein the outlet pipe of the second exhaust device is depressurized by the first exhaust device on the upstream side. A vacuum deaerator connected to a deaeration chamber of the vacuum cleaner. 2. The device according to claim 1 , wherein a connection point of the deaeration chamber on an upstream side of an outlet pipe of the second exhaust device is lower than a connection point of an inlet pipe of the first exhaust device. A vacuum deaerator characterized by being provided.