JP2003010604A - Degassing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a degassing apparatus usable in inflammable gas atmosphere, scarcely corroded even in corrosive gas atmosphere, and operable at a low maintenance cost. SOLUTION: This apparatus is an apparatus for degassing using a membrane by reducing pressure, and when a vacuum pump is used for fluid operation as a pressure reducing means, since no electric motive power is required, the apparatus can be used even in inflammable gas atmosphere. Further, when a gas, especially air, is used for the fluid for operation, such a gas is commonly available, so that the apparatus is excellent in handling easiness. In the case the members of the vacuum pump to be brought into contact with a degassing liquid are made of a tetrafluoro resin, or the like, the apparatus can be used preferably for degassing a solvent, or the like.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to degassing and / or liquid
Alternatively, it relates to a treatment device and a treatment method for a liquid to be defoamed.

[0002]

2. Description of the Related Art As a method for reducing the concentration of dissolved gas dissolved in a liquid, for example, so-called vacuum deaeration, heating deaeration, ultrasonic deaeration, other than oxygen / nitrogen, which decompresses the inside of a packed tower or a spray tower. The method of bubbling the gas, the method of utilizing centrifugation, the method of pressurizing, the method of adding an antifoaming agent, etc. are known. Among them, the membrane-type vacuum degassing method, in which the liquid is passed through one of the membranes through which the gas is permeable and the liquid is not permeable, and the other side is depressurized, the device is small, easy to handle, and highly degassed. It is possible to analyze in various fields such as chemicals, food, medical care, semiconductors, etc.
It is widely used for deaeration and / or defoaming of liquids used for cleaning and manufacturing.

[0003] As a vacuum pump used for reducing the pressure of vacuum deaeration, an oil rotary vacuum pump, a water ring vacuum pump, a roots blower vacuum pump, a diaphragm vacuum pump, a scroll vacuum pump, and the like are known. Japanese Patent Laid-Open No. 06-2738
In JP 97, a diaphragm type vacuum pump is disclosed in
Japanese Patent Laid-Open No. 9-45615 discloses a water-sealed vacuum pump.

[0004]

There is a solvent-based cleaning agent as a field requiring deaeration, but when the conventional technique is applied to a flammable liquid such as IPA (isopropyl alcohol), the driving source is electricity. There was a risk of ignition and explosion due to short circuit of the vacuum pump contacts. As a countermeasure, it is possible to use a vacuum pump with an explosion-proof structure that can be used even in an atmosphere of flammable gas, but the pump will be a large size equipped with a large capacity motor,
The shape is large, it is difficult to handle, it takes up a lot of space, and a great deal of construction and maintenance costs are required.

[0005] Further, there is also a method of decompressing the deaerator by connecting the deaerator piping of the deaerator to a vacuum pump in another place in the factory, but the length of the pipe to the vacuum pump becomes long and complicated. There will be a cost. Furthermore, in order to avoid a decrease in suction capacity due to an increase in pipe resistance, it is necessary to increase the pipe diameter to reduce the pipe resistance and to select a vacuum pump with a high pumping speed, which leads to large equipment and Cost was required. Further, there is a case where the exhaust capacity is reduced due to a leak in the pipe, which requires a great maintenance cost of the pipe.

[0006] Further, when the oil rotary vacuum pump is used, an oil mist is generated during exhaust, so an oil mist trap is required. In addition, there is a problem of oil deterioration due to the reaction with the cleaning agent and oil emulsification due to water suction, and an oil / water separator must be provided separately from the vacuum pump, which requires great cost for installation and maintenance. There's a problem.

[0007] Further, when the water-sealed vacuum pump is used, the vacuum capacity is lower than that of other pumps, and there is a problem that water temperature control is required. Further, when sucking harmful gas or liquid other than water vapor and water, it is necessary to carry out closed circulation of the sealed water because they dissolve in the sealed water and cannot drain the sealed water as it is. Further, when the sealed water is drained, there is a problem that a device for separating the components dissolved in the sealed water is required, which requires a great deal of cost for installation and maintenance.

[0008] When degassing by membrane vacuum degassing,
When the pressure is reduced at a pressure lower than the saturated vapor pressure of the liquid, vaporization of the liquid is promoted, and a large amount of the vapor of the liquid may be discharged to the outside of the system. The material of the vacuum pump is iron, aluminum or NB
When R (nitrile butadiene rubber) or the like is used, there is a problem in that the inside of the pump comes into contact with the sucked solvent or water to cause corrosion, resulting in failure of the vacuum pump.

[0009] The present invention has been made in view of such a problem, and can be used even in a flammable gas atmosphere,
Moreover, it is an object of the present invention to provide a deaerator that does not cause corrosion even in a corrosive gas atmosphere and has a low maintenance cost.

[0010]

The summary of the present invention is as follows.
An apparatus for degassing by performing a depressurization process using a membrane, characterized in that a fluid-driven vacuum pump is used as depressurizing means.

[0011] The member of the vacuum pump that comes into contact with the degassed liquid is made of at least one material of tetrafluororesin, fluororubber, and stainless steel, or tetrafluororesin coating, Ni.
It is preferable that at least one of surface treatments such as plating and cationic coating is performed because it has excellent durability. It is preferable that the vacuum pump is of a reciprocating type or a rotating type because the depressurizing process can be efficiently performed. When the vacuum pump is driven by air, it is preferable because it can be used in any place. It is preferable that the membrane is a three-layer hollow fiber membrane in which both sides of the non-porous membrane are sandwiched by porous support layers, because efficient degassing is possible. A casing containing the membrane and the vacuum pump and having a through-hole is provided, and driving air exhausted from the vacuum pump is once exhausted inside the casing and exhausted outside the casing through the through-hole. With this configuration, the solvent does not enter the apparatus when the solvent is degassed, which is preferable.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The deaerator of the present invention will be described below with reference to the drawings. FIG. 1 is a flow chart showing an example of the degassing apparatus of the present invention, and FIGS. 2 and 3 are cross-sectional views showing one mode of the degassing membrane used in the present invention. Figure 1
In, the liquid is introduced through the liquid introduction port 6 of the degassing device 1, degassed by the degassing film 2, and led out through the liquid derivation port 7.

[0013] Here, the decompression means shown in FIG. 1 may be any as long as it can reduce the pressure on the gas phase side of the film below the pressure on the liquid phase side of the film. It is necessary to use a fluid-driven vacuum pump having no special contact point, and by using the degassing device of the present invention, degassing can be performed in a flammable atmosphere.

[0014] The fluid-driven vacuum pump in the present invention refers to one that uses a fluid as a motive force for decompressing, and refers to one that moves or rotates a piston, a diaphragm, a screw, or the like by the force of a liquid or gas. As a matter of course, any type similar to these can be used as long as it can be depressurized, and examples thereof include a water flow aspirator, a Venturi tube, and other depressurizing means using a flow of liquid or gas.

The operation system of the fluid-driven vacuum pump is not particularly limited, but a reciprocating type or a rotating type is preferably used. Here, the reciprocating system is a system in which the pressure is reduced by reciprocating motion, and for example, a piston system or a diaphragm system is applicable. The rotary type is a method of reducing the pressure by a rotary motion, and for example, a scroll method and a screw method are applicable.

As the driving fluid, gas is preferable, and it is not necessary to prepare the liquid in the tank in advance as compared with the case of a liquid such as water, and it is necessary to install a drainage pipe to drain the liquid. Nor. Further, among the gases, air is particularly preferable because it is universally present and has excellent handleability, and it can be easily supplied from the atmosphere using a compressor or the like and can be directly exhausted to the atmosphere. Therefore, it is preferable to use an air-driven vacuum pump in the deaerator of the present invention.

[0017] As the type of pump, it is preferable to use a so-called dry type vacuum pump such as a piston type vacuum pump, a diaphragm type vacuum pump, a scroll type vacuum pump, a screw type vacuum pump, etc., and an oil rotary type vacuum pump is used. In this case, problems such as oil mist measures, pump oil deterioration and emulsification measures, and temperature control of sealed water and water quality of sealed water when using a water-sealed vacuum pump are eliminated, and maintenance costs can be reduced.

[0018] The form of the membrane used in the present invention is not necessarily limited, and a flat membrane, a hollow fiber membrane, a tubular membrane or the like can be used, but the membrane area per unit volume can be increased and the apparatus can be made compact. It is more preferable to use a hollow fiber membrane which is easy to form. The hollow fiber membrane used in the present invention has an inner diameter of 50 to 50.
It is preferable to use a hollow fiber membrane having a thickness of 0 μm and a thickness of 10 to 150 μm. When the inner diameter is smaller than this range, the pressure loss becomes too large when the liquid is passed through the hollow fiber membrane, and when the inner diameter is large, the efficiency of defoaming and deaeration decreases. Further, if the film thickness is thinner than this range, the mechanical strength will be low, the hollow fiber membrane will vibrate due to pressure fluctuations and the hollow fiber membrane will be easily damaged, and if it becomes thicker, gas permeability will decrease and degassing, Degassing efficiency decreases.

[0019] The structure of the hollow fiber membrane is more preferably a composite hollow fiber membrane having a three-layer structure in which a porous layer is arranged on both surfaces of a non-porous layer. When such a composite hollow fiber membrane is used, it is difficult for the liquid to come into direct contact with the non-porous layer, the non-porous layer is less likely to be attacked by the liquid, and the liquid can be efficiently degassed and defoamed. As a composite hollow fiber membrane, the thickness of the non-porous layer is 0.3.
˜3 μm, and the thickness of the porous layer is 5 to 100, respectively.
When the composite hollow fiber membrane having a thickness of μm is used, the mechanical strength is high and the amount of gas permeation during degassing and defoaming can be improved.

[0020] Examples of the polymer constituting the non-porous layer of such a composite hollow fiber membrane include polydimethylsiloxane, a silicone rubber-based polymer such as a copolymer of silicon and polycarbonate, poly (4-methylpentene-1), Polyolefin polymers such as low density polyethylene, fluorine-containing polymers such as perfluoroalkyl polymers, cellulosic polymers such as ethyl cellulose, polyphenylene oxide, poly (4-vinylpyridine), and urethane polymers are listed. Copolymers or blend polymers can also be used.

[0021] In particular, among these, as a material of the non-porous layer capable of efficiently performing degassing and defoaming of the liquid, a urethane polymer or a material composed of a styrene thermoplastic elastomer and a polyolefin is preferable. In particular, a combination of a styrene-based thermoplastic elastomer and a polyolefin is preferable because it has excellent durability against chemicals and is less likely to damage the raw material or deteriorate in performance even when contacted with chemicals.

[0022] Specific materials for the styrene-based thermoplastic elastomer include a copolymer of styrene and butadiene, a copolymer of styrene and ethylene-butylene, a copolymer of styrene and isoprene, and a copolymer of styrene and ethylene-propylene. Examples include coalescence. These polymers and elastomers may be used alone or in combination of a plurality of materials.

[0023] As the polymer material forming the porous layer of the composite hollow fiber membrane, polyethylene, polypropylene, poly (3
-Methylbutene-1), poly (4-methylpentene-)
Polyolefin-based polymers such as 1), polyvinylidene fluoride, fluorine-based polymers such as polytetrafluoroethylene, polystyrene, polyether ether ketone, polyether ketone, and other polymers can be used. The combination of the polymer material forming the non-porous layer and the polymer material forming the porous layer is not particularly limited, and different kinds of polymers or the same kind of polymers may be used.

[0024] When using the hollow fiber membrane, a method may be used in which liquid is passed through the hollow portion of the hollow fiber membrane to depressurize the outside of the hollow fiber membrane, or liquid is passed through the outside of the hollow fiber membrane to depressurize the hollow portion. Either method can be adopted. FIG. 2 shows an example of a hollow fiber membrane module when a liquid is passed through the inside of the hollow fiber membrane. While holding the open state at both ends of the hollow fiber membrane 1, the side where the liquid flows through the fixing member 2 and the side where the pressure is reduced are shown. Is liquid-tightly sealed. FIG. 3 is an example of a hollow fiber membrane module when a liquid is passed through the outside of the hollow fiber membrane, and is the same as the configuration of FIG. 2 except that a liquid inlet 4 and a liquid outlet 5 are provided in the case 3. However, the depressurizing ports 6 do not necessarily have to be present at both ends, and it is possible to depressurize from only one side. In that case, it is preferable that the hollow fiber end on the non-depressurizing side is closed.

[0025] When the vapor of the liquid to be used has a property of permeating the membrane, the lower limit of the degree of pressure reduction is preferably about the vapor pressure of the liquid. When the degree of pressure reduction is lower than the vapor pressure of the liquid, the vapor of the liquid permeates through the membrane and is easily guided to the vacuum pump, which may cause deterioration of the performance of the vacuum pump. Therefore, although not shown in FIG. 1, it is preferable to provide a trap between the hollow fiber membrane module 2 and the vacuum pump 9. Even in a normal state, a very small amount of liquid may exude from the degassing module 2 to the vacuum pump side, and dew condensation may occur in the vacuum pipe. This is a preferable method because it is possible to prevent the liquid from flowing into the inside of the.

[0026] When a corrosive liquid such as a solvent is deaerated, if a vacuum pump made of a material such as iron, aluminum or NBR (nitrile butadiene rubber) is used, the inside of the pump may be corroded and cause a failure. Therefore, a member made of at least one of tetrafluoride resin, fluororubber, and stainless steel is used as the member of the vacuum pump 9 that contacts the degassed liquid, or the surface of the member that contacts the degassed liquid of the vacuum pump. It is preferable to perform at least one surface treatment such as coating with a tetrafluororesin, Ni plating, and cationic coating. Further, the material is not limited to this, and it is preferable to select a material according to the properties such as corrosiveness of the liquid to be degassed.

[0027] Further, although the liquid feeding means is not shown, the arrangement and method of the liquid feeding means are not particularly limited. For example, a liquid tank and a feeding means installed separately from the degassing device. The untreated liquid sent from the liquid pump is introduced into the liquid introduction port 6 of the deaerator, and the deaerated liquid deaerated by the deaerator is piped from the liquid outlet 7 to a supply destination such as an ultrasonic cleaning tank. There is a method of supplying via. In addition, there is a method of circulating a liquid between a liquid tank and a deaerator by a circulation pump.

[0028] In the deaerator of the present invention, the sluice valve 11 and the leak valve 12 are provided between the hollow fiber membrane module 2 and the vacuum pump 9.
It is preferable to interpose. When performing the deaeration operation, by opening the sluice valve 11 and closing the leak valve 12, the hollow fiber membrane module 2 and the vacuum pump 9 communicate with each other, and the pressure inside the hollow fiber membrane module is reduced. Here, the sluice valve 11 and the leak valve 12 are preferably of a manual type or an air-driven type, and there is no risk of ignition and explosion when an electrically driven valve is used. The type of valve is not particularly limited, but for example, a ball valve, a diaphragm valve, or a needle valve can be used. In the deaerator of the present invention, it is preferable to open the leak valve 12 before starting the vacuum pump to introduce the atmosphere so that the suction side of the vacuum pump becomes atmospheric pressure, and the suction side of the vacuum pump is in a negative pressure state. It is possible to reduce the starting power compared to the case of starting from the above, and it is possible to select a small vacuum pump with low power. In addition, it is preferable to provide a filter 13 in front of the leak valve 12, and it is possible to prevent damage to the hollow fiber membrane module or the vacuum pump due to dust inflow into the module.

The degassing apparatus 1 of the present invention includes a membrane 2 and a vacuum pump 9.
And housing a casing 18 having a through-hole 17,
It is preferable that the air supplied from the drive air inlet 14 to the vacuum pump 9 and exhausted from the drive air outlet 15 is temporarily exhausted to the inside of the casing 18 and exhausted to the outside of the casing 18 through the through hole 17. With such a configuration, the deaerator 1 is placed in an atmosphere of vapor such as solvent.
It is possible to prevent solvent vapor from flowing into the equipment when installed and operated, and it is possible to significantly reduce the number of times the interior of the equipment comes into contact with vapor such as solvent, so the life of various components inside the equipment is reduced. Can be extended and maintenance can be reduced. Also, for the same reason,
It is preferable that the gas or the mixture of the gas and the liquid that is sucked and discharged by the vacuum pump is directly discharged from the degassing gas discharge port 16 to the outside of the apparatus by using a pipe. Also, the through hole 17
Is preferably used as a through hole for releasing the internal pressure by the driving air discharged from the air-driven vacuum pump, from the viewpoint of simplifying the structure of the deaerator. Further through hole 17
Also has an effect of releasing internal heat storage due to heat generation of a vacuum pump or the like.

[0030] Hereinafter, the present invention will be specifically described based on Examples. Example 1 A deaerator was manufactured based on the configuration shown in the flow chart of FIG. The vacuum pump used an air-driven diaphragm type, and no electric parts were used. Further, a stainless steel casing is used, a through-hole is provided in the casing, and the air is exhausted from the drive portion of the air-driven vacuum pump into the casing once and then out through the through-hole to the outside of the casing. Further, the gas or the mixture of the gas and the liquid discharged from the vacuum pump is provided with a degassing gas outlet so that the gas is directly discharged from the degassing gas outlet to the outside of the casing. For the hollow fiber membrane module, a three-layer hollow fiber membrane (MHF200TL, manufactured by Mitsubishi Rayon Co., Ltd.) having an inner diameter of 200 μm and an outer diameter of 254 μm (film thickness of 27 μm) was used. It was fixed and a hollow fiber membrane module having a membrane area of 0.64 m ² was manufactured and used.

[0031] The manufactured degassing apparatus was installed indoors, and an 88% aqueous solution of ethanol was degassed continuously for 48 hours. At this time, the flow rate of the liquid was 300 ml / min, and the dissolved oxygen removal rate was measured from the dissolved oxygen concentration before degassing and the dissolved oxygen concentration after degassing. In addition, the concentration of ethanol vapor in the vicinity of the apparatus was measured by Gastec GV-100 manufactured by Gastec.
The measurement was performed at intervals of 10 minutes using a detector tube for S and ethanol. The liquid temperature was 25 ° C.

[0032] As a result, it was confirmed that the dissolved oxygen removal rate was always 80% or more, and stable operation was possible. Further, the ethanol vapor concentration inside the device, which was measured by inserting the detector tube into the inside of the device through the through hole, was always 0% from the start to the end of the operation. On the other hand, the ethanol vapor concentration measured at the degassing gas outlet was about 5% on average due to the ethanol vapor contained in the exhaust of the vacuum pump. In the observation after the end of the operation, wetting of ethanol or water inside the device was not observed, and no appearance of corrosion of the constituent members was observed. As described above, it can be confirmed that operation can be performed by preventing contact with corrosive gas inside the device by purging the inside of the device with air exhausted from the drive part of the air-driven vacuum pump and constantly filling it with new air. It was

<Example 2> A degassing process was performed in the same manner as in Example 1 except that the casing was not provided. As a result, the dissolved oxygen removal rate was always 80% or more, and it was confirmed that stable operation was possible. The ethanol vapor concentration near the vacuum pump gradually increased due to the diffusion of ethanol vapor contained in the exhaust of the vacuum pump, showing 4.4% after 10 hours, and the degassing gas exhaust of the vacuum pump was reduced. Although the ethanol vapor concentration at the outlet showed about 5%, there was no concern about ignition and explosion because it was an air-driven vacuum pump. Further, in the observation after the operation was completed, wetting by ethanol or water was recognized inside the apparatus, and corrosion due to wetting was observed in a part of the constituent members. As described above, it was confirmed that stable operation can be performed even in an atmosphere of flammable gas by using an air-driven vacuum pump, except for corrosion of constituent members.

[0034]

As described above, since the deaerator of the present invention uses the fluid-driven vacuum pump, the apparatus can be used in a flammable gas atmosphere. Also,
By purging the inside of the casing with the air exhausted from the drive part of the air-driven vacuum pump and constantly filling it with new air, it is possible to significantly reduce the number of contacts with corrosive gas, and to prevent the equipment from corroding. It is difficult for failures to occur,
Maintenance costs can be reduced. Further, since the device can be downsized, it is possible to install the device in the vicinity of the device to which the product is supplied and significantly reduce the piping construction cost and the maintenance cost.

[Brief description of drawings]

FIG. 1 is a flow chart showing an example of a deaerator of the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a hollow fiber membrane module used in the present invention.

FIG. 3 is a cross-sectional view showing an embodiment of the hollow fiber membrane module used in the present invention.

[Explanation of symbols]

1 deaerator 2 Hollow fiber membrane module 3 hollow fiber membranes 4 fixing members 5 containers 6 Liquid inlet 7 Liquid outlet 8 decompression port 9 Vacuum pump 10 pressure gauge 11 gate valve 12 Leak valve 13 filters 14 Air inlet for driving 15 Drive air outlet 16 Degassing gas outlet 17 through 18 casing

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroshi Tasaka             4-1-1 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi               Mitsubishi Rayon Co., Ltd. Product Development Laboratory (72) Inventor Hitoshi Takayama             4-1-1 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi               Mitsubishi Rayon Co., Ltd. Product Development Laboratory F-term (reference) 4D006 GA32 HA02 HA18 HA19 JA03A                       JA53A JA53C JA54A JA54C                       JA63A KA12 KB17 MA01                       MA09 MA31 MA33 MB03 MC16                       MC22 MC30 MC53 MC65 MC68                       PA01 PB12 PB70 PC11 PC41                 4D011 AA17 AC04 AC10                 4D037 AA11 AB11 BA23 BB07 CA03

Claims (7)

[Claims] 1. A degassing apparatus for degassing by performing a depressurization process using a membrane, characterized in that a fluid-driven vacuum pump is used as the depressurizing means. 2. The degassing apparatus according to claim 1, wherein the member of the vacuum pump that comes into contact with the degassing liquid is made of at least one material of tetrafluoride resin, fluororubber, and stainless steel. 3. The surface of a member of the vacuum pump, which is in contact with the degassed liquid, is subjected to at least one surface treatment of tetrafluoride resin coating, Ni plating, and cationic coating. Deaerator. 4. The deaerator according to claim 1, wherein the vacuum pump is a reciprocating type or a rotating type. 5. The degassing device according to claim 1, wherein the vacuum pump is driven by air. 6. The degassing apparatus according to claim 1, wherein the membrane is a three-layer hollow fiber membrane in which both sides of a non-porous membrane are sandwiched by porous support layers. 7. A casing for accommodating the membrane and the vacuum pump and having a through-hole is provided, driving air exhausted from the vacuum pump is once exhausted into the casing, and the casing outside through the through-hole. The degassing device according to claim 5 or 6, wherein the degassing device is configured to exhaust the air.