JPH08906A - Degassing device - Google Patents

Abstract

PURPOSE:To develop an equipment simply performing a novel degassing method to separate gas from a fluid by using a degassing membrane and an exhaust device. CONSTITUTION:In a degassing device containing a degassing membrane 1 permitting a fluid to be degassed to pass and an exhaust means 5 for reducing the pressure outside the degassing membrane 1, a cooling means 6 cooling the exhausted matter from the degassing membrane 1 is provided between the degassing membrane 1 and the exhaust means 5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a degassing method and apparatus. More particularly, the present invention relates to a novel degassing method for separating gas from liquid and the construction of an apparatus for carrying out this method.

[0002]

2. Description of the Related Art Ultrapure water used for cleaning in the manufacturing process of semiconductor integrated circuits is required to have an extremely low dissolved oxygen concentration of 50 ppb or less. Therefore, the manufacturing process of ultrapure water includes a process of reducing the dissolved oxygen concentration. As a typical method for reducing dissolved oxygen, a method of using a degassing membrane having breathability and hydrophobicity,
A method of bubbling with nitrogen gas is known.

In the method of degassing by bubbling nitrogen gas, a desired dissolved oxygen concentration can be easily achieved by adding a bubble column having a simple structure as needed. However, a large amount of nitrogen gas is used for its operation,
There is a problem that running cost and maintenance cost are increased.

Therefore, the deaerator actually used has a structure in which a deaerator using a deaerating membrane described later and a deaerator by bubbling nitrogen gas are combined. That is, in this type of deaerator, 100 ppb is obtained by the deaerator using the deaerating membrane.
After reducing the dissolved oxygen concentration to a certain degree, the dissolved oxygen concentration is reduced to 50 p with a degassing device that performs bubbling with countercurrent nitrogen gas.
It is configured to reduce it to pb or less.

The method using a degassing membrane is such that a degassed fluid is circulated through a fluid path formed by a degassing membrane composed of hollow fibers and the like, while depressurizing the outside of the degassing membrane. It is a method of separating oxygen and the like from the fluid to be degassed. This method has the advantage that the degassing membrane as a member of the degassing device requires almost no maintenance and the running cost is low.

However, the degassing membrane allows water vapor to permeate, and water itself slightly leaks due to manufacturing defects and the like. Therefore, the water vapor pressure inside the degassing membrane controls the degree of vacuum of the exhaust system. Therefore, in order to reduce the dissolved oxygen concentration to 50 ppb or less only by using the degassing membrane, the amount of degassing membrane used should be 3 to 5 times as much as when using nitrogen gas bubbling together. As the number increases, the scale of the exhaust device used to reduce the pressure outside the degassing membrane also increases up to several times. Therefore, there is a problem that the initial device cost increases. In particular, in order to obtain ultrapure water having strict specifications such as used in the cleaning process of semiconductor integrated circuits, it is necessary to use a degassing device including a degassing membrane and an exhaust means in multiple stages. As for the exhaust device, a higher degree of vacuum is required as it becomes a degassing device at the subsequent stage. Therefore, there is a problem that the scale of the degassing apparatus as a whole becomes significantly large.

[0007]

As described above, the degassing apparatus using nitrogen gas bubbling and the degassing apparatus using the degassing membrane have their respective drawbacks, and are used in the manufacturing process of semiconductor integrated circuits. In order to produce ultrapure water of excellent quality, none of them has sufficient performance. In addition, in a device that uses both of them, the advantages of each are utilized and at the same time, the disadvantages of both are incurred, and it is difficult to reduce any of the scale of the device, the initial equipment cost, the running cost, and the maintenance cost. There is.

Therefore, the present invention solves the above-mentioned problems of the prior art, and is capable of efficiently degassing with a simple device configuration, and a new degassing that does not increase running costs or maintenance costs. It is an object of the present invention to provide a deaeration method and a novel deaeration device for carrying it out.

[0009]

That is, according to the present invention,
A method for removing a gas component contained in the degassed fluid by causing the degassed fluid to flow inside the hollow degassing membrane and simultaneously depressurizing the outside of the degassing membrane. A degassing method is provided, which comprises a process of directly contacting a cooling medium with a discharge discharged from a membrane for cooling to cool the cooling medium.

Further, as an apparatus for carrying out the method according to the present invention, according to the present invention, a degassing membrane in which a fluid to be degassed is circulated, and an exhaust means for depressurizing the outside of the degassing membrane. And a cooling means including a means for directly contacting a sufficiently cooled cooling medium with the exhaust discharged from the degassing membrane, between the degassing membrane and the exhaust means. A degassing device is provided.

[0011]

The main feature of the present invention is that the degassing apparatus comprises a degassing membrane and an exhaust device, and further has a cooling means for directly cooling the exhaust gas extracted by the degassing membrane. There is.

That is, it is generally known that the degassing membrane formed of hollow fibers or the like has a high degassing performance when the temperature thereof is high. However, in this type of degassing membrane, it is unavoidable that water vapor having a water vapor partial pressure of the water inside the hollow fiber is permeated, and a slight water leak occurs due to its own defects, etc. These vapor pressures increase the load on the exhaust system. Therefore, in the conventional deaerator, the temperature of the supply water is suppressed within a predetermined range in order to make the scale of the exhaust system an appropriate range, and the original performance of the deaerator membrane has not been sufficiently exerted. .

On the other hand, the degassing method according to the present invention is provided with the cooling means for directly cooling the discharged matter extracted from the degassing membrane. Therefore, since the partial pressure of water vapor can be reduced outside the degassing membrane, even if the temperature of the degassing membrane is set high, the load on the exhaust device does not increase.

Here, one of the important features of the degassing method according to the present invention is that the cooling medium is brought into direct contact with the discharged matter discharged from the degassing membrane. That is,
In a degassing device in operation, the gas present outside the degassing membrane has a very low density. Therefore, the general indirect cooling means has a low cooling efficiency, and the partial pressure of water vapor cannot be sufficiently reduced. Therefore, the exhaust gas having a low density can be effectively cooled by directly contacting the exhaust from the degassing membrane with the cooling medium.

According to a preferred embodiment of the present invention, in the apparatus for carrying out the degassing method according to the present invention, a water-sealed vacuum pump is used as an exhaust device, and a cooling means is provided outside the degassing membrane. A device for spraying cooled water can be used in each case. According to such a configuration, it is possible to efficiently cool the gas having a low density by spraying the cooled water on the outer side of the degassing membrane. Further, since the water-sealed vacuum pump uses water for sealing itself, it can also fulfill the function of draining cooling water at the same time as exhausting air for pressure reduction.

Further, according to a preferred aspect of the present invention, the cooling water is sprayed in the vicinity of the degassing membrane. As a result, the partial pressure of water vapor is sufficiently reduced even in the vicinity of the degassing membrane, and the efficiency of degassing treatment by the degassing membrane is further improved.

When a water-sealed vacuum pump is used, it is preferable to provide an air ejector on the upstream side of the vacuum pump. The reason is that the water-sealed vacuum pump has a limit in the degree of vacuum that can be generated by the vapor pressure of its own sealing water. However, by using the air ejector together, it becomes possible to easily realize a higher degree of vacuum.

The deaerator according to the present invention can be used not only for deoxygenating ultrapure water but also for deaerating any fluid that can be degassed by a degassing membrane. Further, depending on the type of fluid to be degassed, other cooling means such as a Peltier effect element and other exhaust means such as an oil-sealed rotary pump can be arbitrarily selected to configure the degassing device.

Hereinafter, the present invention will be described more specifically with reference to the drawings, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram schematically showing the basic structure of a deaerator according to the present invention.

As shown in the figure, this degassing apparatus comprises a degassing membrane 1 and a liquid flow path 2 having a part of the degassing membrane 1 for passing a degassed fluid.
And a gas discharge part 4 defined by a container 3 that hermetically covers the outside of the degassing 1-blend 1, and an exhaust device 5 connected to the gas discharge part 4. Also, container 3
A nozzle 6 for spraying cooled water is attached to the top of the. The bottom of the container 3 is inclined toward the outside so that the cooling water does not stay.

In the degassing device constructed as described above, at the same time as operating the exhaust device 5, the degassed fluid is circulated in the liquid flow path 2 while spraying sufficiently cooled water from the nozzle 6. As a result, the gas component can be efficiently separated from the degassed fluid. That is, in this deaerator,
Since the temperature of the gas discharge part 4 is sufficiently lowered by the water sprayed from the nozzle 6, the vapor pressure of the leaked water generated from the degassing membrane 1 is sufficiently low. Therefore, as the exhaust device 5, as will be described later in detail, a small device having a small output can be used. Further, since the temperature of the degassing membrane 1 can be set arbitrarily, the gas component can be efficiently separated from the degassed fluid.

[Embodiment 1] FIG. 2 is a diagram schematically showing an example of a configuration in which the deaerator according to the present invention is implemented as an ultrapure water deoxidizer.

As shown in the figure, this deaerator comprises a cartridge 12 containing a deaeration membrane 11 and a container 13 communicating with the inside of the cartridge 12 and provided with a spray nozzle 14 at the top. 15, an air executor 16 attached to the bottom of the cooling chamber 15, a water-sealed vacuum pump 17 connected to the cooling chamber 14 via the air executor 16, and a water-sealed vacuum pump 17 for sealing and cooling water. And a cooling system 18 for supplying cooling water to the spray nozzle 14 at the same time.

The cooling system 18 circulates the refrigerant among the cooler 21, the control valve 22, the heat exchanger 25 and the circulation pump 23.
It is mainly composed of a secondary side fluid passage 24 and a secondary side fluid passage 26 for supplying cooling water supplied from the outside to the spray nozzle 17 and the water-sealed vacuum pump 17 via the heat exchanger 25. . Two
After exiting the heat exchanger 25, the secondary fluid passage 26 is branched into a fluid passage 26a connected to the spray nozzle 14 and a fluid passage 26b connected to the water-sealed vacuum pump 17.

The deaerator having the above-described structure can depressurize the outside of the deaerating membrane 11 by operating the water-sealed vacuum pump 17. Further, the discharged matter discharged from the degassing membrane 11 is cooled by the cooling water sprayed from the spray nozzle 14. Therefore, leakage water and the like generated from the degassing membrane 11 are also condensed, and the vapor pressure in the cooling chamber 15 does not rise. Therefore, the load applied to the water-sealed vacuum pump 17 is small, and as described later in detail, it is possible to use a small pump having a small output. Further, since the deaerator is provided with the air ejector 16, the inside of the cooling chamber 15 can be depressurized to the water vapor pressure in the water-sealed vacuum pump 17 or less.

The deaerator having the above-mentioned structure was actually manufactured by using a commercially available deaerator membrane cartridge. The deaeration membrane cartridge used was two FH10 type modules manufactured by Daicel Industries, Ltd. using polypropylene hollow fibers. As the air ejector and the water-sealed vacuum pump, a 20SKD6-07 type manufactured by Nikuni Machinery Co., Ltd., which is integrated with a motor having an output of 0.75 kW (200 V), was used together with a 20NE1 type air ejector.

Ultrapure water was supplied at a rate of 1500 liters / minute to the deaerator constituted by the above components, while make-up water of 15 ° C. was supplied to the cooling chamber to the water-sealed pump. Was degassed by spraying cooling water cooled to 2 ° C.
The performance of this deaerator is shown in the graph of FIG.

As shown in the same figure, this deaerator was able to reduce the amount of dissolved oxygen to 20 ppb or less only by the treatment with the degassing membrane without performing the treatment with nitrogen bubbling. In this deaerator, even if the temperature of the degassed fluid supplied to the deaerating membrane was raised to 60 ° C, the vapor pressure in the cooling chamber could be maintained at 20 mmHg or less.

For comparison, when the degassing device was constituted only by the degassing membrane and the exhaust device without using the spray nozzle as the cooling device, 10 same degassing membrane modules were used. Only for the first time was it possible to reduce the amount of dissolved oxygen to the same extent. In the case of this deaerator,
In order to maintain the water vapor pressure outside the degassing membrane, it is necessary to limit the temperature of the degassed fluid to 35 ° C. or lower, which is considered to have reduced the efficiency of the degassing membrane. In addition, even if the temperature of the degassing membrane is limited, it still operates as a water-sealed vacuum pump for exhausting at 3.4 kW (200
V) had to be used.

[Embodiment 2] FIG. 4 is a diagram schematically showing another configuration example of the deaerator according to the present invention. The feature of this embodiment is mainly in the configuration of the cooling chamber, and the other components have the same specifications as the embodiment shown in FIG. Therefore, common components are given common reference numbers.

As shown in the figure, in this deaerator, a cooling chamber 15a is incorporated inside a cartridge 12a containing a deaerating membrane 11. That is, in this deaerator, the cartridge 12a has a larger inner diameter than the deaerating membrane 11, and the gap formed between the two is used as the cooling chamber 15a. Therefore, a plurality of spray nozzles 14a for spraying the cooling water are provided at the top of the cartridge 12a. In addition, in order to prevent the cooling water sprayed from the spray nozzle 14a from directly contacting the degassing membrane 11 and lowering the temperature of the degassing membrane 11, the outer periphery of the degassing membrane 11 is directed downward toward the outside. An inclined eave-shaped cover 11a is attached.

In the deaerator having the above-described structure, since the exhaust matter discharged from the degassing membrane 11 is cooled immediately after being discharged from the degassing membrane 11, the cooling chamber
The exhaust system including 15a is depressurized more effectively.

[0034]

As described above in detail, the apparatus for carrying out the degassing method according to the present invention can be simply constructed by a small amount of degassing membrane and a small-sized and low-power exhaust device. At the same time, it has an extremely efficient degassing capacity. Therefore, it is possible to obtain ultrapure water with a small amount of dissolved oxygen that can be used for manufacturing semiconductor devices and the like with simple equipment. In addition to the production of ultrapure water, the features of the deaerator according to the present invention can be utilized for deaerating boiler water and food processing water (tofu production, boiled bean production, etc.).

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a deaerator according to the present invention.

FIG. 2 is a diagram schematically showing a specific configuration example of the degassing device according to the present invention.

FIG. 3 is a graph showing the performance of a degasser constructed in accordance with the present invention.

FIG. 4 is a diagram schematically showing another specific configuration example of the deaerator according to the present invention.

[Explanation of symbols]

1, 11 ... Degassing membrane, 2 ... Liquid channel, 3 ... Container, 4 ... Gas discharge part, 5 ... Exhaust device, 6 ...
Nozzle 12, 12a ... Cartridge, 13 ... Container, 1
4, 14a ... Spray nozzle, 15, 15a ... Cooling chamber, 16 ... Air ejector, 17 ... Water-sealed vacuum pump, 18 ... Cooling system,
21 ... cooler, 22 ... control valve,
23 ... Circulation pump, 24, 26, 26a, 26b ... Fluid path, 25 ... Heat exchanger

Claims (8)

[Claims] 1. A method of circulating a fluid to be degassed inside a hollow membrane for degassing and at the same time depressurizing the outside of the membrane for degassing to remove gas components contained in the fluid to be degassed. 2. A degassing method, which comprises the step of directly contacting a cooling medium with the discharged matter discharged from the degassing membrane to cool it. 2. The degassing method according to claim 1, further comprising a degassing membrane in which a fluid to be degassed is circulated, and an exhaust means for depressurizing the outside of the degassing membrane. And a cooling means including means for directly contacting a sufficiently cooled cooling medium with the exhaust discharged from the degassing membrane between the degassing membrane and the exhaust means. A degassing device comprising: 3. A degassing device according to claim 2, further comprising an air ejector provided between the degassing membrane and the discharging means. 4. The deaerator according to claim 2 or 3, wherein the discharging means is a water-sealed vacuum pump. 5. The deaerator according to any one of claims 2 to 4, wherein the cooling means sprays cooled cooling water to the outside of the deaerating membrane. A deaerator characterized by being present. 6. A deaerator according to claim 5,
The degassing device is configured so that the cooling water is sprayed near the outside of the degassing membrane. 7. The degassing device according to claim 6,
A deaerator, wherein a breathable cover is attached to the outside of the degassing membrane so that the cooling water does not directly come to the outside of the degassing membrane. 8. The degassing apparatus according to any one of claims 2 to 7, wherein the liquid flowing through the inside of the degassing membrane is ultrapure water. Qi device.