JPH04349925A - Rotary type flat membrane separation module - Google Patents

Abstract

PURPOSE:To make a rotary type flat membrane separation module compact and to enhance the transmission flow velocity thereof by forming at least one of membrane leaves and partition plates in the module from a material having flexibility. CONSTITUTION:Membrane leaves 4 formed by arranging separation membranes 3 to both surfaces of plate-shaped supports 2 and plate-shaped partition plates 9 are alternately laminated so as hold intervals to constitute a flat membrane separation module 1 wherein the group of the membrane leaves 4 and the group of the partition plates 9 are relatively rotated. In this case, at least one of the membrane leaves 4 and the partition plates 9 is formed from a flexible substance. The transmitted liquid flow passages in the membrane leaves 4 communicate with the hollow part 8 of a hollow pipe 6 through the small holes 7 bored in the pipe wall of the hollow pipe 6 and the gaps of the bonded parts of the membrane leaves 4 and the hollow pipe 6 are sealed in a liquidtight state by annular spacers 5. Since the membrane leaves 4 or the partition plates can be formed from the flexible substance, the thickness of said membrane leaves or the partition plates can be made thin as compared with that of rigid ones and, since laminating intervals are reduced, the apparatus can be made compact.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating flat membrane separation module having a flat separation membrane and a flat partition plate.

0002

[Prior Art] In membrane separation, a so-called cross-flow filtration method in which the fluid to be treated flows along the membrane surface is used to reduce performance deterioration caused by accumulation of solutes and solids that do not pass through the membrane on the membrane surface. It is commonly used.

[0003] As a cross-flow filtration method using a stationary membrane module, a method in which the liquid to be treated is pumped under pressure to provide a required flow rate along the membrane surface has been put into practical use. The effect of flow rate on membrane performance is noticeable, for example, in the improvement of the salt rejection rate when desalting brine or seawater using a reverse osmosis membrane. Furthermore, in the treatment of fruit juices, fermented liquors, etc. containing polymeric solutes and suspended solids, or various waste liquids, etc., using ultrafiltration membranes or microfiltration membranes, the improvement in permeation flux is mainly noticeable.

[0004] In ultrafiltration and microfiltration, the resistance of the boundary layer is generally greater than the permeation resistance of the membrane itself, and it is not uncommon for it to be one order of magnitude or more. In order to reduce such a large boundary resistance by crossflow, the supply flow rate of the liquid to be treated will inevitably be enormous, and most of it will be discharged from the membrane module without passing through the membrane, resulting in an enormous amount of flow. Most of the input energy will be wasted.

[0005] As a method for reducing this loss, a method has been adopted in which most of the liquid to be treated discharged from the membrane module is circulated and supplied to the membrane module inlet without releasing the pressure through the back pressure regulating valve. Regarding this circulating fluid, it is sufficient to replenish the energy lost due to flow pressure loss. but,
Even with this method, the pressure drop due to high flow rate is large, and not only does it require a large amount of energy supply, but also if it becomes necessary to limit the flow length so that the inlet pressure does not exceed the pressure limit of the membrane module, parallel This has the disadvantage that power costs and equipment costs increase due to an increase in supply flow rate.

[0006] As a method to solve this problem, instead of flowing the liquid to be treated at high speed against a stationary membrane surface, by moving the membrane surface or an object, a wall surface, etc. facing the membrane surface, the membrane surface and the coating are moved. Mainly proposed are methods in which the processing liquid is brought into a relatively cross-flow state.

[0007] Examples of devices and methods using flat membranes include:
JP-A-48-65179 discloses that a hollow rotating shaft 6 and a partition plate 9 are provided in a cylindrical container 30, as shown in FIG.
A membrane separation device in which membrane leaves coated with a separation membrane 3 are attached to both surfaces of a disc-shaped membrane support 2 having a through hole in the center so that the inside 31 of the membrane leaf and the hollow part 8 of the rotating shaft communicate with each other through a small hole 7; A membrane separation method is disclosed in which a high velocity gradient is generated on the membrane surface by rotating membrane leaves through a rotating shaft.

[0008] By interposing a rotating partition plate between the stationary disk-shaped membrane leaves, it is expected that the effect of preventing a decrease in velocity gradient due to co-rotation of the liquid to be treated and increasing the membrane surface shear rate is expected. For example, Japanese Patent Application Laid-Open No. 49-74175 discloses that the center hole of the membrane leaf is liquid-tightly sealed, the permeated liquid is taken out of the container from the outer periphery of the membrane leaf, and a partition plate provided between the membrane leaves is used. discloses an apparatus in which the liquid to be treated flows parallel to the membrane surface by being rotated by a rotating shaft passing through the center hole of the membrane leaf in a non-contact manner.

[0009]

Problems to be Solved by the Invention The shear rate of the surfaces of parallel flat plates that move relatively increases in proportion to the reciprocal of the distance between the flat plates if the relative speed is the same, so the smaller the distance, the better. However, there is a risk that the membrane leaf and the partition plate, which rotate at high speed, will come into contact due to fluctuations in the normal direction due to rotation, and in order to avoid this, a high degree of mechanical precision or the spacing between the membrane leaf and the partition plate must be needs to be large enough.

[0010] For this reason, in conventional membrane modules, not only does the equipment cost become high and it is difficult to sufficiently increase the space efficiency (compactness) of the membrane module, but in addition, in order to obtain a high shear rate, This has the disadvantage that the rotational speed must be high in accordance with the large spacing.

[0011]

[Means for Solving the Problems] In order to efficiently increase the membrane surface shear rate in an element in which a large number of membrane leaves are laminated at regular intervals, the present inventors have developed a system in which a partition plate is used as a partition plate interposed between membrane leaves in order to efficiently increase the membrane surface shear rate. Even if the membrane leaf moves in the normal direction due to mechanical rotation, the partition plate can be used as the element described above, as long as it can be displaced in a corresponding manner to avoid contact and collision, and will not damage each other even if they come into contact. We have learned that it is no longer necessary to manufacture a product with a particularly precise structure so that there is no variation in the linear direction, and that the disadvantage of high costs due to precision molding and precision machining can be solved.

[0012] Furthermore, if such a partition plate is realized, there is no need to increase the distance between the membrane leaf and the partition plate, so the distance between the membrane leaves and the partition plate will be inversely proportional to that of the method of increasing the distance, and the It was also found that the problem of reduced shear rate and space efficiency can be solved.

[0013] Furthermore, the same holds true when the membrane leaf is made flexible, and it has been found that at least one of the membrane leaf and the partition plate needs to be flexible.

As a result of intensive research based on the above knowledge, we have completed the present invention. That is, the present invention
Membrane leaves comprising separation membranes on both sides of a flat support and flat partition plates are stacked alternately at intervals, and the membrane leaf group and the partition plate group rotate relative to each other. The present invention relates to a rotary flat membrane separation module having a structure in which at least one of the membrane leaf and the partition plate is flexible. In addition, the membrane leaf is laminated at regular intervals and integrated into a hollow tube that penetrates the membrane leaf, and furthermore, the hollow part of the hollow tube and the inner layer of the membrane leaf are in communication, and the joint part is liquid. The partition plate is tightly sealed, and the partition plate engages with the structure outside the integrated body, the direction of rotation is regulated by the structure, and the direction perpendicular to the rotation (normal direction of the partition plate) is displaceably engaged. The present invention relates to the rotating flat membrane separation module. Furthermore, the partition plate is made of a flexible material, has a protruding portion approximately in the outer circumferential direction, and the protruding direction of the protruding portion is opposite to the relative rotation direction, and the stress is distributed to the root of the protruding portion. The present invention relates to the rotary flat membrane separation module described above, which is characterized in that it has a smoothly curved notch for allowing the separation to occur. In the case where the partition plate is flexible in the present invention, the materials used for the partition plate include polyolefins such as polyethylene and polypropylene, vinyl polymers such as polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, and polyvinylidene fluoride. Light and flexible films or sheets of organic polymers such as polyamides, polyamides, polyimides, polyesters, etc., and cellulose esters are suitable, but are not limited thereto.

[0015] Various rubber sheets can also be suitably used as flexible partition plates in the same manner as described above, but those with too small Young's modulus need to be made thick to counteract high shear stress, and the mass increases accordingly. may become large and impair the high com-pliance (displacement followability) in the normal direction, so a thin film with a high Young's modulus such as stretched polyester may be preferable because it will warp. In this case, the method for holding the partition plate is preferably a method that does not impair high com-preliance (displacement followability) in the normal direction over the entire area where the partition plate overlaps the membrane leaf.

First, the membrane leaf is disk-shaped, and a hollow tube, that is, a hollow rotating shaft that also serves as a permeate water collection tube, passes through the center of the membrane leaf in the normal direction to integrate the two, and the integrated body is a hollow rotating shaft. To explain a membrane module that rotates around an axis and the partition plate does not rotate, the method of holding the partition plate is to engage the partition plate with its outer periphery to a structure outside the above-mentioned integrated body, such as a container or support, and fix it (hold it). ) However, if the diameter of the partition plate cannot be made sufficiently larger than the diameter of the membrane leaf, do not use any ingenuity in the fixing method. Compliance (displacement followability) in the normal direction is greatly limited.

[0017] In order to alleviate the above-mentioned limitations due to the fixation of the outer periphery of the partition plate, it is desirable that the fixed part of the partition plate be sufficiently separated from the outer periphery projection of the membrane leaf. However, in order to maintain high spatial efficiency in a membrane module with a cylindrical container, it is necessary to make the gap between the outer diameter of the membrane leaf and the inner diameter of the container as narrow as possible. It is difficult to maintain a sufficient distance in the radial direction from the outer peripheral projection of the membrane leaf.

However, as shown in FIG. 4, for example, the stress dispersion hole 10, which is a smoothly curved notch for dispersing stress, the positioning pin hole 22, and the inner diameter Dv of the cylindrical container
The partition plate 9 has an arcuate notch 23 corresponding to the difference between the outer diameter of the membrane leaf and the outer diameter Dm of the membrane leaf, and a through hole 24 larger than the outer diameter of the hollow tube. ), a partition plate is produced in which a plurality of protrusions 11 are provided on the outside, and the protrusions are extended in the circumferential direction opposite to the rotational direction of the membrane leaf by an amount that satisfies the above conditions. This can be solved by fixing it to a stacked cylindrical container.

The distance from the projected portion of the outer periphery of the membrane leaf of the partition plate to the fixed position of the tip of the protrusion may be at least 3 times the stacking interval between the membrane leaf and the partition plate, but is preferably 1
It should be 6 times or more.

[0020] In the case where a flexible partition plate is used, the membrane leaf does not need to be flexible, and in this case, as a support member for the membrane leaf, for example, polymethyl methacrylate,
Vinyl polymers such as polystyrene, polyamides, polyimides, polyesters, polycarbonates, polysulfones,
A flat molded body made of a hard plastic such as a condensation polymer such as polyether sulfone, with a permeate flow path on the surface or inner layer, or a flat molded body made of these materials with a screen mesh, nonwoven fabric, etc. Examples include stacked porous sheets, woven fabrics, nonwoven fabrics, paper, etc. hardened by resin processing, and sintered bodies of plastic particles or metal particles.

On the other hand, if the membrane leaf is flexible and has high com- pliance (displacement followability) in the normal direction, the partition plate does not necessarily have to be flexible, and in this case, the above-mentioned No special retention measures are required.

On the other hand, the flexible membrane leaf may be supported by, for example, a screen mesh, resin-treated tricot woven fabric, nonwoven fabric, etc., or a diaphragm having a differential pressure of 0.3.
A low pressure of Kg/cm2 or less can be achieved by using a foam sheet made of polyurethane, polyamide, or the like.

[0023] In addition to the above, the fact that the partition plate and/or the membrane leaf is flexible and has high comb compliance (displacement followability) in the normal direction brings about favorable effects on the membrane performance. That is, by vibrating in the normal direction as the membrane leaf rotates, in addition to the effect of reducing concentration polarization due to the high shear rate on the membrane surface, the effect of reducing concentration polarization due to disturbance in the normal direction is added. Furthermore, even if foreign matter or suspended components that tend to cause channel blockage flow in, the channel has the advantage of being easily deformed so that they can pass through easily and are unlikely to cause blockage.

[0024] Above, a configuration has been described in which the membrane leaf is rotated by a hollow rotating shaft in which the inner layer of the membrane leaf and the hollow part of the hollow tube are in communication and are integrated in a liquid-tight manner, and the partition plate does not rotate. Considering that the high shear rate on the membrane surface is caused by the relative movement of the membrane leaf and the partition plate, it is possible to
Even if the partition plate is rotated, the above effects can be achieved in substantially the same way.

For example, when the membrane leaf 4 is fixed to the inner wall surface of the container as shown in FIG. The joint is liquid-tightly sealed, and the membrane leaf has a central hole 28.
is provided, the end of the center hole is liquid-tightly sealed to be a free end, and the partition plate 9 fixed to a rotating shaft 29 passing through the membrane leaf center hole 28 without contacting the membrane leaf is rotated. It can also be a structure.

[0026]

【Example】

Example 1 Figure 1 shows a membrane separation module 1 which is an example of the present invention.
FIG. 2 is a plan view showing the flexible partition plate, FIG.
is a schematic diagram of the equipment used to measure the performance of the membrane separation module,
FIG. 4 is a plan view showing another flexible partition plate, and FIG. 5 is a longitudinal sectional side view showing another membrane separation module. Note that the arrows in FIGS. 2 and 4 indicate the rotation direction of the flexible partition plate.

[0027] Outer diameter 13 cm with a hole in the center is made from a screen mesh with a wire diameter of 0.32 mm and an opening of 0.95 mm.
A disc-shaped membrane support 2 was prepared, and an acrylonitrile ultrafiltration membrane DUY-L (manufactured by Daicel Chemical Industries, Ltd.) was layered on both sides of the membrane as a separation membrane 3, and the outer periphery was sealed with adhesive to form a membrane leaf. 4 are stacked at regular intervals with annular spacers 5 interposed therebetween, and their center holes are fitted into the hollow tube 6.

The permeate flow path in the membrane leaf communicates with the hollow part 8 of the hollow tube 6 through a small hole 7 bored in the tube wall of the hollow tube 6, and connects the membrane leaf 4 and the outside of the hollow tube 6. The gap between the surface joints is liquid-tightly sealed by an annular spacer 5.

Partition plates 9 punched from a polyethylene film having a thickness of 0.3 mm are placed between adjacent membrane leaves and on the outer sides of the top and bottom, respectively. The partition plate 9 having the shape shown in FIG. 2 has a protrusion 11 and a stress dispersion hole 10 in a disk having the same outer diameter of 13 cm as the membrane leaf. It engages with an outer frame (structure) 13 that is rotatable. The movement of the partition plate 9 in the rotational direction is restricted by the outer frame 13, but the displacement of the partition plate in the normal direction is not restricted.

The outer frame 13 is supported by a bearing 14, an outer cylinder 15, and a support plate 16. The hollow tube 6 integrated with the membrane leaf group is fixed (not shown) and external power (
(not shown) allows the outer frame 13 integrated with the partition plate group to be rotated.

The membrane separation module 1 constructed as described above was mixed with 30 g of ovalbumin (manufactured by Wako Pure Chemical Industries, Ltd.), 75 g of water-soluble starch (manufactured by Wako Pure Chemical Industries, Ltd.), and 15 liters of a phosphate buffer solution of pH 6.7. As shown in FIG. A membrane separation experiment was conducted with negative pressure on the permeate side. The results are shown in Table 1.

[0032]

[Table 1]

The permeation flux increased with increasing rotational speed of the partition plate. When the partition plate was at rest, it was in contact with the upper membrane leaf, but when it was rotating, it was located in the middle of the membrane leaf.

Example 2 A disk-shaped membrane support with an outer diameter of 13 cm and a hole in the center was prepared from a polymethyl methacrylate resin sheet with a thickness of 2 mm, and the screen used as the membrane support in Example 1 was attached to one side of the disc-shaped membrane support. The mesh is stacked, and an acrylonitrile ultrafiltration membrane DUY-L is stacked on top of the mesh as a separation membrane. Membrane leaves whose outer periphery is sealed with adhesive are stacked at regular intervals via annular spacers, and the center hole is The same procedure as in Example 1 was carried out except that the tube was fitted into the hollow tube. The results are shown in Table 2.

[0035]

[Table 2]

Similar to Example 1, the permeation flux increased as the rotation speed of the partition plate increased.

[0037]

Effects of the Invention According to the present invention, in a flat membrane module in which flat membrane leaves and partition plates are stacked alternately at intervals, and the membrane leaves and partition plates are relatively rotatable, and/or by making the partition plate flexible, preferably by having a structure in which the partition plate can be freely displaced in the normal direction, compared to the case where both the membrane leaf and the partition plate are made of rigid bodies. Since high precision is not required, the thickness of the membrane leaf or partition plate is thinner.
The space between the stacked layers is narrowed, making it more compact, and the high shear rate at the same rotation speed increases the permeation flux, and the addition of the disturbance effect derived from flexibility further increases the permeation flux. A rotary flat membrane separation module can be provided.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing a membrane separation module that is an embodiment of the present invention.

FIG. 2 is a plan view showing a flexible partition plate used in the present invention.

FIG. 3 is a schematic diagram showing an apparatus used to measure the performance of the separation membrane module of the present invention.

FIG. 4 is a plan view showing another flexible partition plate used in the present invention.

FIG. 5 is a longitudinal side view showing another separation membrane module of the present invention.

FIG. 6 is a longitudinal side view showing a conventional separation membrane module.

[Explanation of symbols]

1 Separation membrane module 2 Membrane support 3 Separation membrane 4 Membrane leaf 5 Annular spacer 6 Hollow tube 7 Small hole 8 Hollow part 9 Partition plate 10 Stress dispersion hole 11 Protruding part 12 holes 13 Outer frame 14 Bearing 15 Outer cylinder 16 Support plate 17 Valve 18 Trap 19 Pressure gauge 20 Three-way valve 21　Decompression line 22 Pin hole 23 Notch 24 Through hole 25 Projection section 26 Built-in part 27 Outlet 28 Center entrance 29 Rotation axis 30 Cylindrical container 31 Inside the membrane leaf (layer)

Claims (3)

[Claims] [Claim 1] Membrane leaves comprising separation membranes on both sides of a flat support and flat partition plates are stacked alternately at intervals, and the membrane leaf group and the partition plate group are stacked alternately. 1. A rotating flat membrane separation module having a relatively rotating structure, wherein at least one of the membrane leaf and the partition plate has flexibility. 2. A membrane leaf is integrally formed with a hollow tube that passes through the membrane leaf by being laminated at regular intervals, and the hollow part of the hollow tube and the inner layer of the membrane leaf are in communication with each other. The joint is liquid-tightly sealed, and the partition plate is attached to a structure outside the integrated structure, the direction of rotation is regulated by the structure, and the direction perpendicular to the rotation (normal direction of the partition plate) is movable. 2. The rotating flat membrane separation module according to claim 1, wherein the rotating flat membrane separation module is engaged in the following manner. 3. The partition plate is made of a flexible material, and has a protruding portion approximately in the outer circumferential direction, the protruding direction of the protruding portion is opposite to the relative rotation direction, and the protruding portion has a protruding portion at the base of the protruding portion. 3. The rotary flat membrane separation module according to claim 2, further comprising a smoothly curved notch for dispersing stress.