KR20020013036A - Gas separation membraines for dehumidifying module - Google Patents

Abstract

PURPOSE: A membrane filter for dehumidifying membrane module is provided, which does not need any recycling of dry air to the system by using bundle of hollow polymer membrane wrapped with hydrophilic porous polymer sheet, so that waste of dry air is prevented, thus enabling continuous dehumidifying. The dehumidifying efficiency exhibits zero % of relative humidity at -40 deg.C. CONSTITUTION: The membrane filter comprises a bundle of hollow polymer thread membrane(100) and a porous polymer sheet. The bundle of hollow polymer membrane(100) that is made of polyimide, polysulfone and polyacrylonitrile and has selective permeability to at least gas mixture or moisture in wet air to separate gas of a fixed amount is wrapped with a hydrophilic porous polymer sheet(200) that is made of polyvinylalcohol, polyacrylonitrile, polypyrrolidone, polyethyleneimine and polybutylacrylate and has porosity of 40-99% and pore size of 10-10000μm.

Description

Membrane filter structure for dehumidification membrane module and dehumidification membrane module using the same {GAS SEPARATION MEMBRAINES FOR DEHUMIDIFYING MODULE}

The present invention relates to a membrane filter structure for a dehumidification membrane module for removing moisture in a humid air or gas mixture and a dehumidification membrane module using the same.

In general industrial processes such as chemical processes, the separation of water vapor from air, natural gas and other organic solvents has attracted much attention. In particular, the necessity of removing or controlling moisture in storage, machinery, electronics, chemistry, and other processes of various chemicals, chemicals, etc. is gradually increasing, and devices for dehumidification are commonly used in daily life.

Currently, various methods are used to remove water vapor. Firstly, there is a method of using a hygroscopic agent such as molecular sieve such as silica gel, and secondly, water vapor in a gas using a thermodynamic cycle such as compression or cooling. There is a way to remove it.

However, since there is a need to regenerate or dispose of the absorbent used in the former method, continuous dehumidification is impossible and the latter method consumes a large amount of energy and dehumidification to low humidity is impossible.

One of the recently developed methods is the removal of water vapor using the membrane, which is made possible by the membrane itself having better permeability to water vapor in the gas mixture containing water, which has the advantage of being able to continuously dehumidify. It's going on.

In a known technique related to membrane dehumidification, U.S. Patent No. 4,783,201 was used to remove water in a mixed gas including water vapor using a membrane disclosed in U.S. Patent No. 4,871,494. The membrane is prepared by casting or spinning a polymer solution composed of a polysulfone polymer, a Lewis acid, a base complex, and a solvent to prepare a flat membrane or a hollow fiber membrane. In Patent No. 4,783,201, the dehumidification membrane is a non-coated, graded density skin near the surface of the membrane, and at the same time, a membrane having an asymmetric structure without macropores throughout the membrane is used, and the oxygen / nitrogen selectivity is 1.05 to 2.0 by adjusting the porosity. Mentions the use of membranes. In addition, in order to reduce the hollow on the surface of the membrane, a liquid such as methanol, isopentane, silicon oil, etc. is contacted and then a post-treatment process such as drying and annealing is applied. It discloses to improve the performance of the dehumidification membrane and discloses a reflowing process in which a part of the dry body is introduced into the permeation part of the module in order to remove moisture condensed on the membrane surface. However, in the above patent, the dehumidification performance shows a dew point temperature of -13.5 ^° C., which is not very good, and uses a high pressure of 7 atmospheres, and there is a problem of applying a post-treatment process to improve performance.

As another example, US Pat. Nos. 5,002,590 and 5,108,464 disclose dehumidification membranes to which a coating process is applied using interfacial polymerization inside a hollow fiber membrane. In the above patent, the coating liquid is coated with a hydrophilic polymer such as two reactive species, amine and alcohol, or acyl halide and isocyanate, using interfacial polymerization on the inner surface of the hollow fiber membrane. The dehumidification membrane was prepared, and the support of the membrane included PVDF, Polyimide, Polyethersulfone, Polysulfone, porous glass, and the like. However, there is no description on the structure, shape, etc. of the support itself, and there is a disadvantage in that a vacuum pump is installed in the permeation part to show excellent dehumidification ability up to a dew point temperature of -40 ^o C. The patent also removes water condensed on the membrane surface. For this purpose, a part of the dryer named “SWEEP” was used by resupply to one side of the module.

U.S. Patent No. 4,718,921 discloses a method for removing water vapor from a water-containing gas. In the above patent, an aromatic imide polymer is used as a membrane material, and the water-containing gas is used as a permeation part of the membrane module. And other types of dry gases such as N ₂ , Ar, Ne, etc. into the membrane module, ie hollow fiber, to remove the water condensed on the surface of the hollow fiber membrane and to maintain partial pressure on water vapor acting on the membrane surface. Dehumidification was possible. However, the above patent also has the disadvantage of adding a new process by purging any dry gas and the dehumidification performance is not very good.

U.S. Patent No. 5,525,143 and European Patent 0709123A1 condense the membrane surface by inserting a tube into the epoxy layer inside the module and allowing a part of the dehumidifying gas to flow through the tube in reverse, regardless of the amount of dehumidified gas. Disclosed is a content for removing water. The film used in the above patent is not specifically mentioned, but the silicon coated film is shown through the examples. In a similar patent, U.S. Patent 5,605,564 attaches a constant pressure / valve combination to the outside of the membrane module so that a part of the dehumidified air flows into the permeate of the module by a certain amount, regardless of the pressure of the supply air and the flow rate of the dryer. A patent is disclosed.

Accordingly, an object of the present invention is to provide a dehumidifying membrane module membrane filter structure for removing moisture in the gas mixture or air, and a dehumidifying membrane module using the same.

The membrane filter structure of the present invention is a form in which a polymer hollow fiber membrane is enclosed with a hydrophilic polymer material, and has a very good water removal performance, and the dehumidification membrane module employing the same is used in the conventional art to remove condensed water. It does not require the process of re-introducing a part of air to one end of the module, which provides the advantage that the dehumidification gas can be used more efficiently and continuous dehumidification is possible.

On the other hand, the present invention utilizes the wet gas of the discharge part even within an appropriate range because a gas containing a large amount of moisture permeated from the surface of the (hollow fiber) passes through the sheet of the hydrophilic material and a certain amount of moisture is removed to the wet air discharge part. It provides additional advantages.

1A and 1B are cross-sectional views and side views schematically showing a membrane filter structure for a dehumidification membrane module according to the present invention.

Figure 2 is an embodiment of a dehumidification membrane module employing the membrane filter structure of the present invention

3 is another embodiment of FIG.

4 is a schematic view showing a conventional dehumidification membrane module

Description of the main parts of the drawing

1, 10: wet air inlet 2, 20: wet air outlet

3: dry air inlet 4, 40: first control valve

5: 2nd control valve 6, 60: dry air outlet

15, 150: dehumidification membrane module 100: polymer hollow fiber membrane

200: hydrophilic polymer sheet

300: membrane filter (polymer hollow fiber membrane bundle / hydrophilic polymer sheet)

The membrane filter structure for a dehumidifying membrane module of the present invention as described above is a membrane filter structure for a dehumidifying membrane module for discharging moisture in a gas mixture or wet air to the outside of the membrane by a partial pressure difference between moisture inside and outside the membrane. A certain amount of gas-separated polymer hollow fiber membrane bundles having selective permeability to moisture in wet air are surrounded by a hydrophilic and porous polymer sheet.

Further, the membrane filter is a flat membrane or tubular sheet structure that surrounds the bundle of polymer hollow fiber membranes, and the hydrophilic polymer sheet has a hollow size of 10 to 10,000 µm, preferably 30 to 6,000 µm, Porosity) includes 40 to 99%, preferably 70 to 98%.

The hydrophilic polymer sheet of the present invention includes one selected from the group consisting of polyvinyl alcohol, polyacrylonitrile, polypyrrolidone, polyethyleneimine and polybutyl acrylate.

In addition, the unit bundle of the membrane filter (polymer hollow fiber bundle / hydrophilic polymer sheet) includes the number of the hollow fiber membrane is 100 to 2,000 strands.

In another aspect, the present invention provides a dehumidifying membrane module having a desirable water removal ability employing the membrane filter structure. Such a dehumidifying membrane module of the present invention comprises a membrane filter (polymer hollow fiber bundle / hydrophilic polymer sheet) of the substrate capable of permeating moisture in a gas mixture or wet air; and at least one membrane filter of the substrate. A housing having a fluid inlet and outlet; compressed air supply means for supplying compressed air to the membrane filter; And a flow control valve for controlling the flow rate of the dry air flowing out of the housing, and a part of the dry air flowing out of the housing flows directly into the wet air outlet without circulating into the membrane filter.

The hollow fiber membrane of the present invention may be prepared by a conventional method, but is not particularly limited, and is filed on August 3, 2000 by Korean Patent Publication No. 97-033000, Patent Application No. 97-27692, or the inventor of the present invention. It can be prepared according to the patent pending No. 2000-44959 pending in the source, the constituent material includes polyimide, polysulfone or polyacrylonitrile and more preferably polysulfone in the present invention.

Indeed, in the dehumidification membrane module, the membrane filter surrounds a certain amount of hollow fiber bundles with a sheet-like flat or tubular membrane made of hydrophilic material, and then constructs a bundle of hollow fiber membrane bundles / hydrophilic polymer sheets of this type in a housing. Is inserted. The number of hollow fiber membranes in the bundle of hollow fiber membranes / hydrophilic polymer sheets is usually composed of 100-2,000 strands of hollow fiber membranes. More preferably, the hollow fiber membrane in the sheet is preferably configured to contact the sheet as much as possible, and it is even more advantageous to maximize the insertion of the bundle of the hollow fiber membrane / hydrophilic polymer sheet into the housing. However, the present invention does not specifically limit the number of hollow fiber membrane bundles / hydrophilic polymer sheet bundles inserted into the housing and the hollow fiber membranes inserted in the housing. The use of the sheet made of the hydrophilic material of the present invention increases the packing density of the membrane by minimizing the spacing between the membranes, and maintains the distribution of the hollow fiber membranes uniformly, and at the same time, due to the hydrophilic nature of the sheet, Removal is made even easier to provide features that maintain the driving force to allow moisture to continue to permeate the membrane.

In the manufacture of the membrane filter in the dehumidification membrane module, the packing density is preferably packed so that the gap between the membranes is minimal, and when inserted into the housing, the packing density is a ratio of the area occupied by the hollow fiber with respect to the housing cross-sectional area so as to be at least 0.85 to 0.98. It is advantageous to. The present invention does not limit the number and arrangement of the membrane filters in the present invention in a process for removing water in the gas mixture or air.

The hydrophilic material used in the present invention may be a synthetic polymer material, a flat membrane or tubular membrane in shape, and a material capable of enclosing a certain amount of hollow fiber membrane, and the shape thereof is not limited to the present invention. In order to minimize the resistance to gas flow, the membrane composed of the hydrophilic material preferably has a sheet having a porous structure of 10 to 10,000 micrometers and a porosity of 44 to 99%. And more advantageously a hollow size of 30-6,000 micrometers and a porosity of 70-90%. As the polymer material, polyvinyl alcohol, polyacrylonitrile, polypyrrolidone, polyethyleneimine, polybutyl acrylate, or the like is used, and preferably polyvinyl alcohol.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1A and 1B are cross-sectional views and side views schematically illustrating a membrane filter structure for a dehumidification membrane module according to the present invention.

2 is an embodiment of a dehumidification membrane module employing the membrane filter structure of the present invention.

3 is another embodiment of FIG.

4 is a schematic view showing a conventional dehumidification membrane module.

As shown in Figure 1a and 1b is a membrane filter structure for a dehumidification membrane module of the present invention is a form surrounding the polymer hollow fiber bundle with a hydrophilic polymer material.

The present invention is based on the finding that the dehumidification performance is improved compared to the same hollow fiber membrane under the same conditions by presenting a form surrounding the hollow fiber membrane bundle with a hydrophilic polymer material. It should be understood that it is not the subject of limitation. However, according to the experiments of the present inventors, it was confirmed that the larger the contact area between the hollow fiber membranes and the hydrophilic polymer material surrounding the hollow fiber membrane bundles having the same number, the higher the desired dehumidification performance. For example, rather than tying a bundle of hollow fiber membranes composed of 100 hollow fiber membranes and enclosing them with hydrophilic polymers, n becomes larger when n (100 / n) bundles of 100 hollow fiber membrane bundles are provided. Dehumidification performance is improved.

4 is a schematic view of a conventional dehumidification membrane module, which is a view schematically showing a dehumidification membrane module disclosed in Korean Patent Publication No. 1997-81175. Referring to the dehumidification process with reference to the drawings, the moisture-containing gas is supplied to the humid air inlet 1 of the dehumidification membrane module 15, and as the gas comes into contact with the surface of the hollow fiber membrane, the moisture quickly permeates the membrane and simultaneously the module. The dry air (6) is discharged to the dry air outlet (6) located at one end of the. At this time, the wet gas containing a large amount of moisture, which has permeated the membrane, is discharged into the atmosphere through the wet air discharge unit 2. In addition, by installing a first control valve 4 in front of the wet air discharge unit 2 to adjust the flow rate of the gas discharged from the wet air discharge unit 2 to maintain the dehumidification performance, the first control valve (4) Moisture generated on the surface of the membrane by adjusting a second control valve (5) located at the other end of the side) so that a part of the dry body discharged from the wet air discharge unit (2) flows into the dry air inlet unit (3) of the module. After the removal is configured to be discharged into the atmosphere through the wet air discharge (2). This process has the disadvantage that the efficiency is greatly reduced as part of the dry gas is re-introduced into the module. In addition, the flow direction of the feed gas and the flow direction of the gas flowing back into the wet air discharge unit 2 of the module is characterized by using a countercurrent (countercurrent) flow.

Unlike the prior art as described above, the invention disclosed and claimed in the present application is a method of drying a dry air discharged from the dry air outlet 2 through the conventional second control valve 5 as shown in FIGS. It is characterized in that it does not require a step of reflowing a part into the dry air inlet 3. That is, the gas mixture or air containing moisture at one end of the membrane filter is supplied to the wet air inlet 10, and the dry air outlet 20 is installed at one end of the membrane filter to discharge the dehumidifying gas. On the other hand, the first control valve 40 is attached to the front end of the dry air outlet 20 to control the dehumidification performance. Accordingly, the present invention provides an advantage that the desiccant used in the prior art is not re-introduced into the module, and thus the desiccant can be continuously dehumidified while using the desiccant more efficiently. On the other hand, according to the present invention, since the gas containing a large amount of water permeated and discharged from the membrane surface passes through a sheet of hydrophilic material and a certain amount of water is removed, the gas of the wet air discharge unit 60 can be used within an appropriate range. It provides a merit.

Advantages and effects of the present invention will become more apparent from the following examples.

(Comparative Example)

The hollow fiber membrane used was prepared according to Korean Patent Laid-Open Publication No. 97-033000 as a membrane produced from polysulfone. The hollow fiber membrane 300 strands were inserted into the tube-shaped housing, and the membrane filter was prepared after potting the space between the hollows with epoxy at the sock end portion of the tube. Dehumidification performance was measured based on the process shown in FIG. 2 and compressed air was used as a gas containing moisture. Referring to FIG. 2, air having an air temperature of 22 ^o C, a dew point temperature of 0 ^o C (relative humidity of 23%), and a pressure of 5 kg / cm ² is supplied to the supply portion 10 of the membrane filter and is placed on one side of the membrane filter. In the process of being discharged to the air outlet 60, the dehumidification performance can be adjusted by reducing the discharge flow rate by adjusting the first control valve 40 located at the top of one side. Dew point temperature and relative humidity were measured using a TH550 (Dickson) dew point and relative humidity meter, and the results are shown in Table 1 below.

Table 1.

Comparative example Discharge flow rate (l / min) Dew point ( ^o C) / relative humidity (%) of the discharge fluid Dehumidification flow rate (l / min) Dew point of dehumidifying fluid ( ^o C) / relative humidity (%) One 66 -2 ^o C / 21% 5 -17 ^o C / 8%

* Discharge flow rate and discharge fluid: flow rate and fluid in the wet air outlet (20) (the same)

* Dehumidification flow rate and dehumidification fluid: flow rate and fluid in the dry air outlet 60 (the same)

The result of Table 1 above is a case where a sheet made of a hydrophilic polymer material is not inserted into the membrane filter. In the measurement, the wet air was supplied to the supply unit 10 of the membrane filter based on FIG. 2 and the dry gas flow rate discharged to the dehumidification unit 60 was fixed at 5 l / min and the discharge flow rate was set at 66 l / min. The result is that there is no process to reflow some of the dry air into the other end of the module.

(Examples 1 and 2)

300 bundles of hollow fiber membranes used in the above comparison were surrounded by a hydrophilic polymer sheet, and then 1 bundle and 3 bundles were prepared and inserted into the tube-shaped housing, respectively, and the space between the hollows was ported with epoxy at the sock end of the tube. . As a polymer sheet, a sheet made of polyvinyl alcohol was used, and the dehumidification performance was measured using the apparatus shown in FIG. 3.

Table 2.

Example Discharge flow rate (l / min) Dew point ( ^o C) / relative humidity (%) of the discharge fluid Dehumidification flow rate (l / min) Dew point of dehumidifying fluid ( ^o C) / relative humidity (%) Bundle One 66 -18 ^o C / 7% 5 -40 ^o C / 0% 3 2 66 -14 ^o C / 10% 5 -34 ^o C / 1% One

As shown in the results of Table 2, when the polymer hollow fiber bundle / hydrophilic polymer sheet bundle is inserted, the dew point temperature of the dehumidifying part (dry air outlet 60) shows excellent performance compared to the result of the comparative example. It can be seen that as the number of bundles is increased, the dehumidification performance is improved as the sheet is easily contacted with moisture. In addition, the dew point temperature of the discharge part (wet air outlet part 20) is also discharged with a gas having a significantly lower moisture than when the sheet is not inserted, and this tendency is the same even if the number of bundles is increased Indicates.

(Examples 3, 4, 5, 6)

Examples 3, 4, 5, and 6 below are results of measuring dehumidification performance in the case of using a sheet made of various polymers. The number of bundles of hollow fiber bundles / hydrophilic polymer sheets was 3, and the dehumidification performance was measured according to the process of FIG. 2.

Table 3.

Example Discharge flow rate (l / min) Dew point of discharge fluid ( ^o C) / relative humidity (%) Dehumidification flow rate (l / min) Dew point of dehumidifying fluid ( ^o C) / relative humidity (%) Hydrophilic Sheet 3 66 -18 ^o C / 7% 5 -40 ^o C / 0% Polyvinyl alcohol 4 66 -14 ^o C / 10% 5 -34 ^o C / 1% Polyacrylonitrile 5 66 -15 ^o C / 9% 5 -38 ^o C / 0% Polyethyleneimine 6 66 -17 ^o C / 8% 5 -38 ^o C / 0% Polyvinylpyrrolidone

From the above results, it can be seen that when the polyvinyl alcohol porous sheet is inserted, it exhibits the best dehumidification performance, and all of the used sheets exhibit significantly superior dehumidification performance than when the sheet is not inserted.

(Example 7)

Example 7 below is a case in which the number of bundles of hydrophilic polymer sheet / hollow fiber membrane bundle is 3, using the same membrane material used in the above example, and using polyvinyl alcohol as the polymer sheet. Dehumidification performance is measured using the measurement conditions shown in FIG.

Table 4.

Example Discharge flow rate (l / min) Dew point ( ^o C) / relative humidity (%) of the discharge fluid Dehumidification flow rate (l / min) Dew point of dehumidification flow rate ( ^o C) / relative humidity (%) 7 66 -14 ^o C / 10% 5 -38 ^o C / 0%

When the results of Example 7 of Table 4 and the results of Tables 2 and 3 are compared, it can be seen that the dehumidification performance is similar, but the dew point temperature of the discharge fluid 20 is somewhat higher than that of the dehumidification process based on FIG. 2.

As described above, the present invention uses a method, a process, and a device different from the conventional art, and shows that the water removal performance in the gas mixture or the air is very excellent, and does not require the reflow of the dry gas in the process. Not only can the efficiency of the dry gas be further improved, but also the gas discharged from the discharge part 60 can provide additional uses by discharging the gas containing moisture lower than that of the water-containing feed gas. .

Claims (7)

In the membrane filter structure for the dehumidification membrane module for discharging moisture in the gas mixture or wet air to the outside of the membrane by the partial pressure difference of the moisture inside and outside the membrane, A membrane filter structure for a dehumidifying membrane module, characterized by enclosing a certain amount of the gas separation polymer hollow fiber membrane bundle having a selective permeability to moisture in the gas mixture or wet air with a hydrophilic and porous polymer sheet. The membrane filter structure for a dehumidification membrane module according to claim 1, wherein the polymer hollow fiber membrane bundle is made of polyimide, polysulfone or polyacrylonitrile. The hydrophilic polymer sheet surrounding the polymer hollow fiber membrane bundle has a hollow size of 10 to 10,000 µm, preferably 30 to 6,000 µm, and a porosity of 40 to 99%. Membrane filter structure for a dehumidification membrane module, characterized in that 70 to 98%. The membrane filter structure as claimed in claim 1, wherein the hydrophilic polymer sheet is one selected from the group consisting of polyvinyl alcohol, polyacrylonitrile, polypyrrolidone, polyethyleneimine, and polybutyl acrylate . The membrane filter structure for a dehumidification membrane module according to claim 1, wherein the unit bundle of the membrane filter (polymer hollow fiber bundle / hydrophilic polymer sheet) has a number of hollow fiber membranes of 100 to 2,000 strands. The membrane filter (polymer hollow fiber bundle / hydrophilic polymer sheet) according to any one of claims 1 to 5, which can permeate moisture in a gas mixture or wet air; A housing 150 including at least one membrane filter 300 and provided with a fluid inlet and outlet; Compressed air supply means for supplying compressed air to the membrane filter 300; It includes a flow control valve 40 for adjusting the flow rate of the dry air flowing out of the housing 300, A part of the dry air flowing out of the housing (150) is dehumidified membrane module, characterized in that flows directly to the wet air outlet (60) without circulating into the housing (150). The dehumidification membrane of claim 6, wherein the packing density of the membrane filter 300 in the housing 150 is 0.85 or more and 0.98 or less as a ratio of the cross-sectional area of the polymer hollow fiber membrane bundle to the housing 150 cross-sectional area. module