JPH10296005A - Method for ultradeaeration of liquid and deaeration apparatus thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a great amount of ultradeaerated water by a vacuum pump of a small capacity by a method wherein a membrane module of a specific oxygen permeation rate, and a membrane module of the specific oxygen permeation rate and a steam permeation rate are combined, and a vacuum pressure to a gas phase side is specified. SOLUTION: A first membrane module group 9a wherein a film of which oxygen permeation rate at 25 deg.C (QO2 ) is 1×10<-5> to 10000×10<-5> [cm<3> (STP)/ cm<2> .sec.cmHg] is a diaphragm, and a second membrane module group 10a composed of a diaphragm of which oxygen permeation rate is 0.5×10<-5> to 40×10<-5> [cm<3> (STP)/cm<2> .sec.cmHg] and of which vapor permeation rate (QH2 O) is 0.5×10<-5> to 150×10<-5> [cm<3> (STP)/cm<2> .sec.cmHg] are connected in series. Then, deaeration is executed by passing water from the membrane module 9a side keeping a pressure of the air phase side of the membrane module group 9a at a reduced pressure of not more than a pressure exceeding saturated steam pressure of water to be deaerated and higher 10 cmHg than saturated steam pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deaeration method using a diaphragm to remove various gases present in a liquid, particularly in water, through a diaphragm.
The present invention relates to a method and apparatus for producing ultra-degasified water degassed to ppb or less, preferably 10 ppb or less, and most preferably 1 ppb or less with a compact device in a very efficient manner. The present invention is, for example, deoxygenated water for boiler supply, deoxidation in the ultrapure water production step of the semiconductor production process,
Super degassing of various dissolved gases typified by decarboxylation and denitrification, degassing of resist solution and developer in the lithography process, prevention of red water in buildings and condominiums, deoxygenation and decarbonation of power generation water, medical water It can be used for degassing and production of deoxidized water for food.

[0002]

2. Description of the Related Art Heat degassing, vacuum degassing, gas aeration, chemical using a reducing agent, diaphragm degassing, and the like have been known as water degassing methods. Among them, the diaphragm degassing method has excellent features such as a small and inexpensive degassing device, easy handling, extremely easy maintenance, and low energy required for degassing. .

As a membrane deaeration method, for example, Japanese Patent Application Laid-Open No. 59-2
Japanese Patent No. 16606 proposes a deaerator using a tubular film having an inner diameter of about 0.2 mm made of a synthetic resin such as silicone or polytetrafluoroethylene.

Japanese Patent Application Laid-Open No. 4-288710 discloses that the flow path interval of water to be degassed is 190 μm or less, preferably 60 μm.
By using a diaphragm-type degassed water production module having a size of μm to 150 μm, by flowing water to be degassed to the liquid phase side while reducing the gas phase side to a saturated vapor pressure of water flowing to the liquid phase side or less. It discloses that ultrapure water having a dissolved oxygen concentration of 10 ppb or less can be efficiently produced.

[0005] In addition, the electronic material Vol. 35, No. 3, P
63 (1996) includes poly (4-methylpentene-
External perfusion using a hollow fiber heterogeneous membrane made of the material 1), which can impart a stirring effect to the flow of deaerated water, and can reduce the space between the water flow paths and simultaneously increase the substantial area of the water flow path. Introducing an innovative membrane degassing membrane module that improves the processing efficiency of the membrane module and minimizes the flow pressure loss of water, which inevitably increases when processing large amounts of water, by using a mold module. Have been.

[0006]

The removal of various gases dissolved in liquids, especially water, has been actively performed in a wide range of industrial fields not only for the purpose of preventing corrosion of various corrosive metal pipes but also for many purposes. And its importance is increasing.
For example, in the semiconductor manufacturing field, dissolved gases in ultrapure water,
In particular, by removing oxygen or carbon dioxide gas, for example, the life of ion exchange resins, reverse osmosis membranes, ultrafiltration membranes and the like used in ultrapure water production equipment is shortened, and bacteria are propagated. Significant effects on slime generation and oxidative deterioration prevention have been recognized. Furthermore, it has been pointed out that dissolved oxygen in ultrapure water causes unnecessary oxidation of silicon wafers in the process of manufacturing semiconductor devices, and adversely affects device performance. Sex is growing. Next generation 16Mb and even 64MB
-In the manufacturing process of the D-RAM, the dissolved oxygen concentration is 1
0 ppb or less, preferably 1 ppb or less is required.

Further, in the field of electric power, it is required that the concentration of dissolved oxygen be 50 ppb or less and the concentration of dissolved carbon dioxide be 100 ppb or less as water for turbines for power generation. As described above, for degassing from liquids, especially water, development of degassing technology capable of obtaining a large amount of degassed water simply, efficiently and at low operating cost is urgently required.

However, the conventionally known heating degassing method, vacuum degassing method, nitrogen bubbling method, and chemical method have large equipments, high running costs, and are difficult to perform advanced degassing. None of them were satisfactory.

[0009] Further, the conventionally proposed diaphragm degassing method has excellent features such as a compact degassing device, easy handling and maintenance, and low running cost in a region where the throughput is small. However, in order to degas a large amount of water, the processing amount per module is small, and the running cost increases due to the increase in the size of the device. Upsizing was a very big problem.

In order to super-degas the dissolved oxygen concentration to 50 ppb or less, preferably 10 ppb or less, more preferably 1 ppb or less, it is necessary to keep the gaseous phase side of the membrane at a very low pressure. In particular, in order to efficiently perform ultra-degassing with a dissolved oxygen concentration of 1 ppb or less, it is necessary to maintain the pressure on the gas phase side of the membrane at or below the saturated water vapor pressure of degassed water. Under these conditions, a large amount of water vapor permeates the membrane together with the gas to be degassed. Therefore, the conventionally known diaphragm degassing method required an extremely large-capacity vacuum pump to eliminate the water vapor. Further, the type of vacuum apparatus that can be used is limited by the large amount of water vapor that permeates, and the shortening of the service life is also a serious problem.

In view of the demands from various industries regarding the degassing of various gases from liquids, particularly water-based liquids, which have become increasingly demanded in recent years, the present invention provides a membrane degassing system with many advantages, particularly when the dissolved oxygen concentration is reduced to 50 ppb. Below, preferably 1
It is an object of the present invention to propose a degassing method and a degassing device capable of economically and efficiently producing super-degasified water of 0 ppb or less, most preferably 1 ppb or less.

[0012]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a membrane module using a membrane having a high gas permeation rate and a high degassing performance as a membrane, and having a moderate oxygen permeability and Combining a membrane module with excellent steam barrier properties,
Surprisingly, by appropriately controlling the vacuum pressure on the gas phase side, respectively, the amount of super-degasified water having a dissolved oxygen concentration of 50 ppb or less, more preferably 10 ppb or less, and most preferably 1 ppb can be obtained in a large amount, efficiently and It was found that it was feasible to use a very small capacity vacuum pump, which was difficult.

The present invention will be described in more detail. That is, the present invention
Is to (1) remove gas dissolved in water through a diaphragm
Oxygen permeation rate at 25 ° C.
(Hereinafter sometimes abbreviated as QO2) is 1 × 10^-Five[Cm
^Three(STP) / cm^Two・ Sec ・ cmHg] ~ 10000 × 1
0^-Five[Cm^Three(STP) / cm^Two· Sec · cmHg]
First membrane module group with membrane as membrane and oxygen permeation rate
Is 0.5 × 10^-Five[Cm^Three(STP) / cm^Two・ Sec ・ cm
Hg] to 40 × 10^-Five[Cm^Three(STP) / cm^Two・ Sec ・
cmHg] and the water vapor transmission rate of the membrane (hereinafter Q
0.5 × 10)^-Five[Cm^Three(S
TP) / cm^Two・ Sec ・ cmHg] ~ 150 × 10^-Five[C
m^Three(STP) / cm^Two· Sec · cmHg]
Second group of membrane modules are connected substantially in series.
To degas the pressure on the gas phase side of the first membrane module group.
Exceeds the saturated water vapor pressure of water and is 10c above the saturated water vapor pressure
The second membrane module is kept at a reduced pressure below mHg high pressure.
While maintaining the gas phase pressure of the group below the saturated steam pressure,
Water is passed from the membrane module side, and then the second membrane module
Super degassing method of liquid, characterized by passing water through group and degassing,
(2) The membranes of the first and second membrane module groups are blind sheets
(1) Dv = 4 × (volume of effective hollow fiber membrane winding part) / (effective
The equivalent diameter of the hollow fiber gap calculated from the total outer surface area of the hollow fiber membrane (hereinafter abbreviated as Dv)
May be 50 μm to 400 μm
With a structure built into the case in a state of being stacked on
And circulates the liquid in contact with the outside of the cord-shaped hollow fiber,
It is specially designed to perform deaeration using an external perfusion method that degass inside the empty yarn.
(3) The method of degassing a liquid according to (1) above,
The diaphragm of the first and second membrane module groups has an outer diameter of 70 μm or more.
370 μm and inner diameter is 30 μm to 310 μm
The deaeration according to the above (2), which is a hollow fiber membrane
Method, (4) at least the diaphragm of the second membrane module group is
Hollow fiber heterogeneous made of poly (4-methylpentene-1)
(1), (2) or (3) above, which is a film.
And (5) the oxygen permeation rate is 1 × 10
^-Five[Cm^Three(STP) / cm^Two・ Sec ・ cmHg】 ~ 100
00 × 10^-Five[Cm^Three(STP) / cm^Two・ Sec ・ cmH
g], a first group of membrane modules using the membrane as a diaphragm, and an acid
0.5 × 10^-Five[Cm^Three(STP) / cm^Two・ S
ec · cmHg] to 40 × 10^-Five[Cm^Three(STP) / cm^Two
.Sec.cmHg] and the water vapor transmission rate of the membrane
Degree 0.5 × 10^-Five[Cm^Three(STP) / cm ^Two・ Sec ・ c
mHg] to 150 × 10^-Five[Cm^Three(STP) / cm^Two・ Se
c · cmHg]
A series of degassing modules connected in series,
Means for supplying deaerated water from one membrane module group side
And the pressure on the gas phase side of the first and second membrane module groups is reduced.
Incorporating a conductance valve as a means to pressurize
A diaphragm type deaerator comprising:
The pressure on the gas phase side of the membrane modules
In excess of the saturated steam pressure at
cmHg high pressure or less, and the second
The pressure on the gas phase side of the membrane modules
That the pressure is adjusted below the saturated steam pressure
The present invention relates to a liquid super deaerator for liquid.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The typical and best modes of the embodiment of the present invention will be specifically shown in the examples described later, and the outline thereof is as follows.

Used for the first membrane module according to the present invention
Membrane is substantially liquid under normal conditions of use
It is impermeable to water and the oxygen transmission rate of the membrane is 1 × 10
^-Five[Cm ^Three(STP) / cm^Two・ Sec ・ cmHg】 ~ 100
00 × 10^-Five[Cm^Three(STP) / cm^Two・ Sec ・ cmH
g]. The oxygen permeation rate of the membrane
Depending on conditions such as type, water temperature, operating pressure, etc.
You can choose one. Preferably 8 × 10^-Five[Cm^Three(STP)
/ Cm^Two・ Sec ・ cmHg] ~ 3000 × 10^-Five[C
m^Three(STP) / cm^Two· Sec · cmHg],
More preferably, 10 × 10^-Five[Cm^Three(STP) / cm^Two
・ Sec ・ cmHg] ~ 100 × 10^-Five[Cm^Three(STP) /
cm^Two.Sec.cmHg].

A membrane having a high oxygen transmission rate is generally a microporous membrane, but has an oxygen transmission rate of 10,000 × 10 ^-5 [cm].
³ (STP) / cm ² · sec · cmHg], water leaks as a liquid depending on degassing conditions, such as degassing of pressurized water and degassing from water containing a surfactant. It is not preferable because it may come out.

The material, structure and form of the diaphragm used in the first membrane module group are not limited, but the material of the membrane is preferably a highly hydrophobic material. For example, polyethylene (hereinafter PE
Resin), polypropylene (hereinafter sometimes abbreviated as PP) resin, various fluororesins such as polytetrafluoroethylene, perfluoroalkoxy fluororesin, polyhexafluoropropylene, polybutene resin, silicone Materials such as resin-based resins and poly (4-methylpentene-1) -based resins are preferred. The membrane structure may be any of a microporous membrane, a homogeneous membrane, a heterogeneous membrane, a composite membrane, and the like. As the membrane shape, a hollow fiber membrane capable of obtaining a large membrane area with a compact membrane module is preferable.

The second group of membrane modules according to the present invention comprises:
The oxygen transmission rate of the diaphragm is 0.5 × 10 ⁻⁵ to 40 × 10
^-5 [cm ³ (STP) / cm ² · sec · cmHg], preferably 1.0 to 40 × 10 ^-5 [cm ³ (STP) / cm ² · sec]
c · cmHg] and the water vapor transmission rate of the membrane is 0.1 cm.
5 × 10 ^{-5 to} 150 × 10 ^-5 [cm ³ (STP) / cm ² · s
ec · cmHg], preferably 0.5 × 10 ⁻⁵ to 50 ×
10 ^-5 [cm ³ (STP) / cm ² · sec · cmHg]. Water vapor transmission rate of 150 × 10
^If it exceeds -5 [cm ³ (STP) / cm ² · sec · cmHg], not only is a large vacuum pump with extremely high evacuation capacity required, but also, for example, a module using a hollow fiber membrane as a diaphragm is used. In the case of trying to deaerate by so-called external perfusion method in which the inside of the hollow fiber is depressurized while flowing water to the outside of the hollow fiber and deaerated, even if a large vacuum pump having a sufficient exhaust capacity is used, It is difficult to degas the dissolved oxygen concentration in water to several ppb or less.

The degassing performance of the module generally improves as the oxygen permeation rate of the membrane increases, but the permeation rate of water vapor also increases accordingly. It is important to select a diaphragm that has a good balance of both properties.

According to the present invention, a membrane having an oxygen permeation rate and a water vapor permeation rate according to the present invention can be appropriately selected and used, if necessary. The membrane used for the second membrane module group is not particularly limited as long as it satisfies the conditions of the present invention, but a membrane made of a material having high hydrophobicity is preferable, for example, a PE-based resin, a PP-based resin, and polytetrafluoroethylene. Suitable materials include various fluororesins such as perfluoroalkoxy fluororesins and polyhexafluoropropylene, polybutene resins, silicone resins, and poly (4-methylpentene-1) resins. The film structure is not limited, and any of a microporous film, a homogeneous film, a heterogeneous film, a composite film, a thin film of urethane or the like as a polypropylene microporous film layer, and a sandwich film, a so-called sandwich film, can be used. As the membrane form, a hollow fiber membrane that can obtain a large membrane area with a compact membrane module is preferable.

In particular, a heterogeneous hollow fiber membrane made of a poly (4-methylpentene-1) -based resin is most preferable because it has excellent gas permeability for oxygen, nitrogen, carbon dioxide and the like, and has high water vapor barrier properties. Regarding this heterogeneous film, for example,
No. 8250, Japanese Patent Publication No. 2-54377, Japanese Patent Publication No. 4-15014, Japanese Patent Publication No. 4-50053, and Japanese Patent Application Laid-Open No. H5-6656 are described in detail.

As in the case of PE resin, PP resin and polyvinylidene fluoride resin, the material has low gas permeability,
Therefore, in order to apply to liquid degassing, a microporous structure is taken and compared with these membranes which have to be degassed by the porous part, the poly (4-methylpentene-1) -based resin is used as a material. The hollow fiber heterogeneous membrane itself has a sufficiently high gas permeability and the dense layer is made sufficiently thin, so that the entire membrane surface can contribute to degassing, and as a result, substantially It is extremely preferable because the film area becomes large.

In addition, the hollow fiber heterogeneous membrane has extremely small gas diameter and open area of the communicating pores penetrating the membrane wall while having high degassing performance. Has extremely excellent barrier properties.

Further, a so-called non-porous heterogeneous membrane made of a poly (4-methylpentene-1) -based resin having substantially no communicating pores substantially penetrating the membrane can be applied to the deaeration membrane if necessary. This non-porous heterogeneous membrane can be suitably used for degassing various liquids that may leak in a liquid state even if there are only a few communication holes in the membrane. For example, it is preferably applied as a deaeration film from a liquid containing a surfactant and a solvent that wets the film, such as a developing solution or a resist solution used for semiconductor manufacturing, or a deaeration film from a working oil or an edible oil. it can.

According to the present invention, the above-mentioned first membrane module group and the second membrane module group are connected in series substantially, and the pressure of the gas phase side of the first membrane module group is deaerated. While maintaining a reduced pressure of not more than the saturated steam pressure and 10 cmHg higher than the saturated steam pressure and maintaining the gas phase side pressure of the second membrane module group at a reduced pressure of not more than the saturated steam pressure, the first degassing module group side From the second degassing module group, and then degassed.

The pressure reducing means may be evacuated simply by a vacuum pump or the like, or may be evacuated by a vacuum pump while flowing an appropriate sweep gas. When removing specific dissolved gases,
A method using a sweep gas in combination is effective. For example, when it is important to remove only dissolved oxygen and carbon dioxide,
Nitrogen gas, argon gas or the like is effectively used as a sweep gas.

The pressure on the gaseous phase side of the first membrane module group may be higher than the saturated steam pressure at the temperature of the degassed water and not more than 10 cmHg higher than the steam pressure. The pressure range is preferably from 0.1 cmHg to 5 cmHg higher, more preferably from 0.1 cmHg to 0.7 cmHg higher than the saturated steam pressure. The gas-phase side pressure of the second membrane module group may be equal to or lower than the saturated steam pressure of the deaerated water at that temperature, but is preferably 0.1 cmHg to 1.5 cmHg lower than the saturated steam pressure, More preferably, 0.3 to 1 cmH
g lower pressure.

The first membrane module group and the second membrane module group only need to be configured substantially in series, and the liquid degassed by the first membrane module group is once subjected to degassing such as oxygen. The gas may be stored in a tank or the like having a structure in which the gas does not redissolve, and may be deaerated by passing water through the second membrane module group if necessary.

According to the present invention, even in the case of performing a very large volume degassing, the first and second membrane module groups are combined and the vacuum pressure on the gas phase side is adjusted.
Achieving a desired high degree of deaeration with a more efficient and smaller vacuum system than when using a large module with a membrane area that is the sum of the first and second membrane modules it can.

The temperature of the water to be degassed is not particularly limited, but the higher the temperature, the better. By increasing the water temperature, not only can a large amount of water be efficiently degassed, but also the saturated water vapor pressure naturally increases due to the increase in the water temperature, and therefore the vacuum pressure on the gas phase side of the membrane can be increased. Thereby, the load on the vacuum apparatus can be reduced, which is extremely preferable. The temperature of the deaerated water is preferably from 10C to 50C, more preferably from 20C to 50C.

The form of the first and second membrane modules of the present invention is not limited, and the form can be selected as required, such as a hollow fiber membrane module, a flat membrane type module, a spiral type module, and a tubular membrane module. Among them, the hollow fiber membrane module is most preferable because the membrane area per unit volume of the module can be increased.

There is no limitation on the way of flowing water into the hollow fiber membrane module. An internal perfusion system may be used in which water flows inside the hollow fiber and the outside is kept at a reduced pressure to deaerate the water. An external perfusion system may be used in which the pressure is reduced and degassing is performed.

The external perfusion method is compared with the internal perfusion method,
It is excellent in deaeration efficiency and can suppress the flow pressure loss of water to an extremely low level, and is most preferable particularly when a large amount of water is to be deaerated.

The structure of the external perfusion type module and the method of filling the hollow fiber membrane may be configured so as not to cause turbulence in the water to be degassed.
Some suitable module structures are disclosed in, for example, Japanese Patent Application Laid-Open No. 4 (1994) -104.

According to the present invention, when the external perfusion method, which is the most preferable method for the deaeration treatment of a large amount, is carried out particularly as the diaphragm deaeration method, the diaphragms of the first and second membrane modules according to the present invention are used. A hollow fiber blind formed in a sheet form, wherein Dv = 4 × (volume of effective hollow fiber membrane winding part) / (total outer surface area of effective hollow fiber membrane) The equivalent diameter of the gap is 50 μm-40
0 μm, preferably 140 μm to 300 μm has a structure incorporated in the case in a state of being laminated in a multilayer, liquid flows in contact with the outside of the cord-like hollow fiber membrane,
It is characterized in that degassing is performed by an external perfusion method in which degassing is performed inside the hollow fiber. Here, the effective hollow fiber membrane refers to a hollow fiber portion in contact with degassed water. A smaller Dv value, that is, a denser packing of hollow fiber cords is preferable because the deaeration efficiency is improved, but if the Dv value is 50 μm or less, the flow pressure loss of water in the cord portion becomes extremely large, which is not preferable. On the other hand, if it exceeds 400 μm, the efficiency of deaeration of water is greatly reduced, which is also undesirable.

The dimensions of the hollow fiber membrane applied to the external perfusion module according to the present invention are such that the smaller the outer diameter of the hollow fiber membrane is,
It is more preferable because a large membrane area can be obtained even if the diameter of the cord is small, so that the module can be reduced in size and, surprisingly, the degassing efficiency per membrane area is improved. The outer diameter is preferably 70 μm to 370 μm, more preferably 150 μm to 280
μm. The inner diameter of the hollow fiber membrane is 30 μm to 310 μm.
m is preferred, and more preferably 80 μm to 220 μm
It is.

The external perfusion type module according to the present invention comprises:
It is characterized by being able to easily suppress the circulating flow of deaerated water, has excellent pressure resistance, has a simple structure, and is easy to manufacture. There is no restriction on the form of the hollow fiber mat-like sheet, and a non-woven fabric,
There is no particular limitation on the knitted or woven fabric, but a knitted or woven fabric in which the hollow fiber membrane is a weft or a warp and another yarn such as a monofilament or multifilament yarn made of polyester or the like is a warp or a weft.

FIG. 1 shows a model diagram of an example of a preferred embodiment of the external perfusion module structure according to the present invention. In carrying out the method of the present invention, there is no limitation on the method of adjusting the pressure on the gas phase side of the first membrane module group and the pressure on the gas phase side of the second membrane module group. The phase side pressure may be reduced by separate vacuum devices. Preferably, a single vacuum device is used to depressurize the gas phase sides of both module groups.

The present invention also provides the most preferred deaerator. FIG. 2 shows a model diagram of this device. In FIG. 2, 9a is a first membrane module group described in the present invention, and 10a is a second module group. The number of modules to be used may be appropriately selected depending on the amount of liquid to be processed and the like, and the connection of the modules in each group may be either parallel or series. If the flow pressure loss of the water to be degassed is within an acceptable range, it is more preferable to connect all of them in series because degassing efficiency per membrane area can be further increased.

In FIG. 2, reference numerals 12a and 12b denote conductance valves. The pressure on the gas phase side of the first membrane module group exceeds the saturated vapor pressure of deaerated water and is higher than the saturated vapor pressure by 10 cmHg by the valve 12a. The pressure is adjusted to the following reduced pressure, and the pressure on the gas phase side of the second membrane module group is maintained at a reduced pressure atmosphere equal to or lower than the saturated steam pressure by the valve 12b. The type of valve is not particularly limited, but a non-bleed type is preferable. Reference numeral 13 in FIG. 2 is a decompression device. The pressure reducing device used in the present invention is not particularly limited as long as the pressure on the gas phase side of the first and second membrane module groups can be reduced to the predetermined pressure described in the present invention below, and the oil rotary pump is used. There are no particular restrictions, such as a diaphragm type pump, a water aspirator, a water ring type vacuum pump, a water ring type vacuum pump with a booster, a dry type vacuum pump such as a roots type and a scroll type. Also, an oil / water separator may be attached to the oil rotary pump, or the water of the water ring pump may be cooled with a chiller or the like, or a liquid with a low vapor pressure may be used.
Further, it can be carried out as appropriate, for example, by using an air ejector attached to a water ring vacuum pump.

Here, the measurement of the gas permeation rate of the membrane itself is performed by A
It is easily performed in accordance with STM-D1434. The water vapor transmission rate of the membrane according to the present invention is determined by flowing water on one side of the membrane, reducing the pressure on the other side of the membrane, capturing the permeated water in a cold trap, and measuring the amount.
At this time, the pressure difference between the water vapor on both sides of the membrane was a value obtained by subtracting the vacuum pressure on the reduced pressure side from the saturated water vapor pressure at that temperature for convenience.

[0042]

【Example】

Example 1 QO ₂ made of polypropylene is about 860 × 10-
⁵ [cm ³ (STP) / cm ² · sec · cmHg] with an outer diameter of about 2
A hollow fiber microporous membrane having an inner diameter of about 210 μm and an inner diameter of about 210 μm is used as a weft, and a 30-denier polyester multifilament is used as a warp. It is wound spirally around a rigid vinyl chloride pipe having a nominal diameter of 30 with a membrane area of 90 m ² and a number of holes opened so that the Dv of the cord layer becomes about 255 μm.
It is loaded into a module case of about 50 cm in length consisting of 50 hard vinyl chloride pipes, and has a structure shown in FIG. 1 by a known centrifugal sealing method using a urethane resin and an epoxy resin as a sealing resin. An external perfusion module 1 was manufactured.

Next, poly (4-methylpentene-1)
Is referred to as material, QO ₂ is about ^{5 × 10- 5 [cm 3 (} STP) / cm
² · sec · cmHg], QH20 is about 8 × 10- ⁵ [cm
³ (STP) / cm ² · sec cmHg] with an outer diameter of about 255 μm
The hollow fiber heterogeneous membrane having an inner diameter of about 170 μm
A denier polyester multifilament is used as a warp, and a hollow-fiber-shaped sheet having a hollow fiber driving number of about 63 / inch is used. With a hollow fiber outer diameter reference membrane area of 90 m ² , the hollow fiber winding layer has a Dv of about 230 μm. An external perfusion module 2 having the same structure as the above-mentioned external perfusion module 1 except that it was spirally wound on a perforated pipe as described above was manufactured.

Using the external perfusion type module 1 as the first membrane module according to the present invention and the external perfusion type module 2 as the second membrane module according to the present invention, FIG.
The degassing system shown in the model diagram was constructed. In the figure, reference numeral 13 denotes a pumping speed of about 48 m ³ / h for keeping the pressure on the gas phase side of the film at reduced pressure.
This oil rotary vacuum pump is equipped with a membrane type oil / water separator to separate the water vapor discharged with various dissolved gases in the water and the vacuum oil of the pump. did. By the conductance valves shown in 11a and 12b, the gas-phase side pressure of the first membrane module shown by 9a in the figure is maintained at 2.5 cmHg, and the gas-phase side pressure of the second membrane module shown by 10a in the figure is made 2 cmHg. After adjustment, air-saturated water at a water temperature of 25 ° C. was introduced from the raw water inlet of the first membrane module at various flow rates, and the dissolved oxygen concentration (Do value) at the treated water outlet of the second membrane module 10a in FIG. It was measured with a polarographic oximeter. About 12 t / hr (ton / hour) of water degassed to a Do value of about 1 ppb was obtained. Further, by increasing the supply amount of 25 ° C. air-saturated water flowing from the membrane module group 1 side, the Do value becomes approximately 47 p.
About 30 t / hr of water degassed to pb was obtained.

[0045] As Example 2 second membrane modules, poly (4-methylpentene-1) as a raw material, QO ₂ is about ^{10 × 10- 5 [cm 3 (} ST
^{P) / cm 2 · sec ·} cmHg], water vapor transmission rate of about ^{12 × 10- 5 [cm 3 (} STP) / cm 2 · sec · cmH
g], a hollow fiber heterogeneous membrane having an outer diameter of about 215 μm and an inner diameter of about 136 μm was used, and the blinds were spirally wound around a perforated pipe so that the Dv of the blind winding layer was about 210 μm. The same deaeration test as in Example 1 was performed except that a membrane module having the following was used.

About 15 t / hr of water degassed to a Do value of about 1 ppb was obtained. By further increasing the supply of water, 39 t / hr of degassed water having a Do value of about 50 ppb could be obtained.

[0047] Example 3 Poly (4-methylpentene-1) as a raw material, QO ₂ is about ^{30 × 10- 5 [cm 3 (} STP) / cm 2 · sec · cmH
g], water vapor transmission rate of about ^{28 × 10- 5 [cm 3 (} STP) /
cm ² · sec · cmHg] in the hollow fiber outside diameter of about 215μm,
Using a hollow fiber heterogeneous membrane with an inner diameter of about 130 μm as the weft, a 30-denier polyester multifilament as the warp, and a hollow fiber mat-like sheet in which the number of hollow fiber heterogeneous membranes is about 63 / inch by Russell knitting. Prepared and wound spirally around a rigid vinyl chloride pipe with a nominal diameter of 30 with a number of holes opened so that the hollow fiber winding layer has a Dv of about 210 μm with a hollow fiber outer diameter reference membrane area of 90 m ^2. The winding body is loaded into a module case of about 50 cm in length made of a hard vinyl chloride pipe with a nominal diameter of 250, and a urethane resin and an epoxy resin are used as a sealing resin. An external perfusion type module 1 having the structure shown in the figure was manufactured.

[0048] Then, QO ₂ of film of approximately 12 × 10- ⁵ [cm
³ (STP) / cm ² · sec · cmHg], QH2O is about 14 ×
In ^{10- 5 [cm 3 (STP)} / cm 2 · sec · cmHg] outside diameter of about 200μm of the hollow fiber membrane, using a hollow fiber heterogeneous membrane inner diameter of about 120 [mu] m, the 20 denier polyester multifilament Using a hollow fiber mat-like sheet in which the number of hollow fiber heterogeneous membranes is about 66 / inch as the warp, and spirally wound on a perforated pipe so that the Dv of the hollow fiber winding layer is about 200 μm. An external perfusion type module 2 having the same structure as that of the above external perfusion type module 1 was manufactured.

The same degassing system as in Example 1 except that the external perfusion type module 1 was used as the first membrane module according to the present invention and the external perfusion type module 2 was used as the second membrane module. A degassing experiment was performed by changing the supply amount of the configured and degassed 25 ° C. air-saturated water to the module group. The obtained deaeration characteristic curve is shown in graph (1) of FIG. About 19 t / hr of water degassed to a Do value of 1 ppb was obtained, and about 53 t / hr of water degassed to a Do value of 50 ppb or less.

Embodiment 4 A degassing system was constructed in which three modules shown in the model diagram of FIG. 3 were connected in series. In the figure, reference numerals 9b and 9c denote a first membrane module group, in which two hollow fiber microporous membrane modules made of PP used in Example 1 were connected in series. In the figure, reference numeral 10b denotes a second membrane module group, in which the poly (4-methylpentene-1) hollow fiber heterogeneous membrane module used in Example 2 was used.

Using an oil rotary vacuum pump with a pumping speed of 48 m ³ / hr shown in FIG. 13 and a conductance valve shown in 11c and 11d, the gas phase side of the first membrane module group shown in 9b and 9c in FIG. The pressure is 2.5cmHg each
And the gas-pressure side pressure of the second membrane module 10b in the figure was adjusted to 2 cmHg by the conductance valve shown in the figure 11e, and air-saturated water with a water temperature of 25 ° C. was supplied from the raw water inlet of the first membrane module 9b. The flow rate and Do value of the water flowing out from the treated water outlet of the second membrane module 10b in FIG. 3 were measured. The Do value was measured by a polar graphic oxygen meter. Do value is about 0.8pp
About 30 t / hr of degassed water was obtained.

Example 5 As the first membrane module and the second membrane module, QO ₂ made of poly (4-methylpentene-1) was about 2%.
^{7 × 10- 5 [cm 3 (} STP) / cm 2 · sec · cmH
g], QH2O is about ^{26 × 10- 5 [cm 3 (} STP) / cm 2 · s
ec · cmHg], the outer diameter of the hollow fiber is about 215 μm,
Using a 30 μm hollow fiber heterogeneous membrane as a weft and a 30-denier polyester multifilament as a warp, a hollow fiber heterogeneous membrane with a driving number of about 63 / inch was prepared, and the hollow fiber outer diameter reference membrane area was 90 m ^2. An external perfusion type having the same structure as that of the membrane module used in Example 1 except that it is wound spirally on a perforated pipe so that the equivalent diameter of the hollow fiber cord winding layer is about 190 μm. The same deaeration test as in Example 1 was performed except that the membrane modules were connected in series and used. The deaeration characteristics are shown in graph (3) of FIG. About 18 t / hr of water degassed to a Do value of about 1 ppb could be obtained.

Example 6 (Enhancing degassing performance at a water temperature of 40 ° C.) Using air-saturated water at a water temperature of 40 ° C., an exhaust speed of about 36 m ³ /
Example 5 except that the vacuum pressure on the gas phase side of the first membrane module group was set to 5.8 cmHg and the vacuum pressure on the gas phase side of the second membrane module group was set to 4.6 cmHg using a vacuum pump of hr. The same degassing experiment was performed. The deaeration characteristics are shown in graph (5) of FIG. About 25 t / hr of water degassed to about 0.8 ppb could be obtained.

Comparative Example 1 A degassing experiment was performed in the same manner as in Example 1 except that the first membrane module and the second membrane module were replaced with each other. 2. It becomes difficult to keep the vacuum pressure on the gaseous phase side of the second membrane module using the microporous polypropylene hollow fiber membrane shown in FIG. It was impossible.

Comparative Example 2 Using the first membrane module and the second membrane module used in Example 3, a deaeration system shown in a model diagram in FIG. 2 was constructed in the same manner as in Example 1, and a valve 11a and a valve 11a were used. 12a was adjusted, and the vacuum pressure on the gas phase side of both modules was adjusted to 2 cmHg.
It was adjusted to become. As the water flow rate is increased, the vacuum pressure on the gas phase side of the module groups 1 and 2 gradually increases, and when the flow rate exceeds about 20 t / hr, the saturated steam pressure of water that degass the vacuum pressure on the gas phase side About 2.37c
It cannot be maintained below mHg. The deaeration characteristics are shown in graph (2) of FIG. About 16 t / hr of water degassed to a Do value of about 1 ppb can be obtained.
About 32 t / hr of water degassed to b was obtained.

Comparative Example 3 The second membrane module shown at 10b in FIG.
Methyl pentene-1), QO ₂ is about 17 × 1
^{0- 5 [cm 3 (STP)} / cm 2 · sec · cmHg], QH2O
Water vapor transmission rate of about ^{18 × 10- 5 [cm 3 (} STP) / cm 2
[Sec · cmHg], outer diameter about 270 μm, inner diameter about 19
A hollow fiber non-homogeneous membrane of 0 μm is used as a weft, a multi-filament of 50 denier polyester is used as a warp, and a hollow fiber outer diameter standard membrane is used. in the area of 90m ^2,
Except for changing the membrane module having the same structure as the external perfusion type module used in Example 1, except that the hollow-fiber-shaped sheet wound layer was wound spirally on a perforated pipe so that Dv was about 410 μm. The same degassing test as in Example 1 was performed. About 5 t / hr of water degassed to a Do value of about 0.8 ppb was obtained. Furthermore, Do value is about 49
About 18 t / hr of water degassed to ppb was obtained.

Comparative Example 4 A hard vinyl chloride pipe having a nominal diameter of 300 was used as a module case, the diameter of the hollow fiber membrane was increased, and the membrane area based on the outer diameter of the hollow fiber membrane was changed to 180 m ^2.
A single-stage perfusion module having substantially the same structure as that of Example 1 was used, and a single-stage degassing test was performed using an oil rotary vacuum pump with a pumping speed of 48 m ³ / hr. As the flow rate of water increases, the pressure on the vacuum side on the gas phase side of the membrane module gradually increases, and when the flow rate exceeds about 12 t / hr, the saturated steam pressure of water that degass the vacuum pressure on the gas phase side Of about 2.37 cmHg or less.
The deaeration characteristics are shown in graph (4) of FIG. Do value is about 1p
Water degassed to pb could only be obtained up to about 10 t / hr. Next, a similar deaeration test was conducted by changing the vacuum pump to be used to a large oil rotary pump having an evacuation speed of about 78 m ³ / hr. As a result, the same deaeration performance as in the case of Example 5 was obtained. Was.

[Brief description of the drawings]

FIG. 1 is a model diagram of an external perfusion type hollow fiber membrane module used in Examples.

FIG. 2 shows Examples 1 to 3 and Comparative Examples 1 to 3 of the present invention.
It is a conceptual diagram of the deaeration system used in FIG.

FIG. 3 is a conceptual diagram of a deaeration system used in Embodiment 4 of the present invention.

FIG. 4 is a graph showing deoxidation characteristics obtained in Example 3 and Comparative Example 2 of the present invention. In FIG. 4, (1) shows deoxidation characteristics obtained in Example 3. (2) shows the deoxidation characteristics obtained in Comparative Example 2.

FIG. 5 is a graph showing deoxidation characteristics obtained in Examples 5 and 6 of the present invention and Comparative Example 4. In FIG. 5, (3) shows the deoxidation characteristics obtained in Example 5. Yes, (4) is the deoxidizing property obtained in Comparative Example 4, and (5) is the deoxidizing property obtained in Example 6.

[Explanation of symbols]

1: Cap, 2: Deaeration port, 3: Hollow fiber membrane, 4: Housing, 5: Raw water inlet, 6: Resin seal, 7: Deaerated water outlet, 8: Perforated pipe, 9a to 9c: First membrane module group, 10a to 10b: second membrane module group, 11
a to 11e: vacuum pressure gauge, 12a to 12e: conductance valve, 13: vacuum pump.

Claims (5)

[Claims] In a diaphragm degassing method for degassing gas dissolved in water through a diaphragm, the oxygen permeation rate is 1 × 1.
0 ^-5 [cm ³ (STP) / cm ² · sec · cmHg] -10
000 × 10 ^-5 [cm ³ (STP) / cm ² · sec · cmH
g], and a first membrane module group having a membrane as a diaphragm, and an oxygen transmission rate of 0.5 × 10 ⁻⁵ [cm ³ (STP) / cm ² · s]
ec · cmHg] to 40 × 10 ⁻⁵ [cm ³ (STP) / cm ²
· Sec · cm · Hg] and the water vapor transmission rate of the membrane is 0.5 × 10 ⁻⁵ [cm ³ (STP) / cm ² · sec · c].
mHg] to 150 × 10 ^-5 [cm ³ (STP) / cm ² · se]
c · cmHg] are substantially connected in series, and the gas-phase side pressure of the first membrane module group exceeds the saturated vapor pressure of water to be degassed. While maintaining a reduced pressure of 10 cmHg or more higher than the saturated steam pressure and maintaining the gas phase pressure of the second membrane module group at a saturated steam pressure or less, water is passed from the first membrane module side,
Next, a method of super degassing a liquid, characterized by passing water through the second group of membrane modules and degassing. 2. A hollow fiber curtain in which the diaphragms of the first and second membrane module groups are formed in a blind sheet shape, wherein: (Formula 1) Dv = 4 × (volume of an effective hollow fiber membrane winding part) The equivalent diameter of the hollow fiber gap calculated by // (total outer surface area of the effective hollow fiber membrane) is 50 μm to 40 μm
It has a structure in which it is incorporated in a case in a state of being stacked in multiple layers so as to have a thickness of 0 μm, and a liquid is circulated in contact with the outside of the cord-shaped hollow fiber, and degassing is performed by an external perfusion method of degassing inside the hollow fiber. The degassing method according to claim 1, wherein air is removed. 3. The diaphragm of the first and second membrane modules has an outer diameter of 70 μm to 370 μm and an inner diameter of 30 μm.
3. The degassing method according to claim 2, wherein the hollow fiber membrane has a diameter of about 310 [mu] m. 4. The degassing method according to claim 1, wherein at least the membrane of the second group of membrane modules is a heterogeneous hollow fiber membrane made of poly (4-methylpentene-1). Method. 5. An oxygen transmission rate of 1 × 10 ⁻⁵ [cm ³ (STP)]
/ Cm ² · sec · cmHg] to 10000 × 10
^-5 [cm ³ (STP) / cm ² · sec · cmHg] as a first membrane module group having a membrane as a membrane, and an oxygen transmission rate of 0.5 × 10 ^-5 [cm ³ (STP) / cm] ² · sec · cmH
g] to 40 × 10 ^-5 [cm ³ (STP) / cm ² · sec · c]
mHg], and the water vapor transmission rate of the membrane is 0.5 ×
10 ^-5 [cm ³ (STP) / cm ² · sec · cmHg] ~ 1
50 × 10 ^-5 [cm ³ (STP) / cm ² · sec · cmH
g], a series of deaeration modules in which a second membrane module group comprising a diaphragm is connected in series, means for supplying deaerated water from the first membrane module group side, first and second A diaphragm deaerator incorporating a conductance valve as a means for reducing the pressure on the gas phase side of the second membrane module group, the pressure on the gas phase side of the first membrane module group by the pressure reducing means, The deaerated water is adjusted to a pressure exceeding the saturated steam pressure at that temperature and not more than 10 cmHg higher than the saturated steam pressure, and the pressure on the gas phase side of the second membrane module group is adjusted to the degassed water. A liquid super-degassing apparatus characterized in that the pressure is adjusted to be equal to or lower than the saturated steam pressure at that temperature.