JPH0518634U - Rotary flat membrane separator - Google Patents

Abstract

(57) [Summary] [Purpose] The centrifugal force generated by rotation is used to supply and discharge the liquid to be treated from the rotary flat sheet membrane separator. [Structure] A large number of membrane leaves having separation membranes are laminated on both sides of a disk-shaped support at intervals and penetrated by a hollow rotating shaft,
A membrane element in which the inside of the membrane leaf communicates with the hollow portion of the hollow shaft, and the outside is fluid-tightly sealed, and a fluid passage hole is provided in the vicinity of the hollow shaft of the membrane leaf, which communicates in the axial direction, The membrane leaf and the flat plate-shaped partitions that are alternately laminated so as to keep the space therebetween are relatively rotated about the hollow shaft. [Effect] The liquid to be treated is sucked and discharged by the centrifugal force generated by the rotation, and the deterioration of the membrane performance is prevented.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is capable of relatively rotating a membrane leaf element composed of a large number of laminated flat plate-shaped membrane leaves and a flat plate-shaped partition element composed of a large number of flat plate-shaped partitions alternately sandwiched between the membrane leaves. The present invention relates to a rotary flat membrane separation device having a different structure.

[0002]

[Prior Art]

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

Conventionally, as a cross-flow filtration method of a stationary membrane module, a method of pumping a liquid to be treated to give a required flow velocity along a membrane surface has been put into practical use. For example, the effect of flow velocity on the membrane performance is remarkable in the improvement of the salt removal rate, mainly in desalination using reverse osmosis membrane of brine or seawater. In addition, the treatment of fruit juice containing high-molecular solutes or suspended solids, fermentation liquor, etc., or various effluents with ultrafiltration membranes or microfiltration membranes is mainly remarkable in improving the permeation flux.

In the ultrafiltration method and the microfiltration method, the resistance of the boundary layer is generally larger than the permeation resistance of the membrane itself, and it is not rare that the resistance is one digit or more. In order to reduce such a large boundary resistance by the cross flow, the supply flow rate of the liquid to be treated is inevitably enormous, and most of it is not permeated through the membrane and is discharged from the membrane module. Most of the input energy is wasted.

As a method of reducing this loss, a method of circulating and supplying most of the liquid to be treated discharged from the membrane module to the inlet of the membrane module without releasing the pressure through the back pressure regulating valve is adopted. As for this circulating fluid, the energy lost due to flow pressure loss should be replenished. However, even in this case, the pressure loss due to the high flow rate is large, and it is necessary not only to supply a large amount of energy but also to limit the flow length so that the inlet pressure does not exceed the pressure limit of the membrane module. Has a drawback that parallelization, that is, increase in power supply cost and equipment cost due to increase in supply flow rate.

As a method for solving this problem, instead of flowing the liquid to be treated at a high speed with respect to the stationary membrane surface, the membrane surface or an object facing the membrane surface, a wall surface, or the like is moved, so that the membrane surface and the treated surface are treated. A method of making the liquid relatively cross-flow has been mainly proposed.

As an apparatus and method using a flat membrane, for example, Japanese Patent Application Laid-Open No. 48-65179 discloses a hollow rotation for a cylindrical container 1 having a liquid inlet 2 and a concentrate outlet 3 as shown in FIG. A hollow rotating shaft 4 penetrates the center of a disk-shaped membrane leaf 9 having a shaft 4 and a partition 5 and coated with a separation membrane 8 on both surfaces, and the inside 7 of the membrane leaf and the hollow portion 10 of the rotating shaft communicate with each other through a small hole 6. There is disclosed a membrane separation device which is attached as described above, and a membrane separation method which causes a high velocity gradient on the membrane surface by rotating the membrane leaf via a rotating shaft.

By interposing a rotating partition between the stationary disk-shaped membrane leaves, it is expected that the reduction of the velocity gradient due to the co-rotation of the liquid to be treated is prevented and the shear rate of the membrane surface is increased. For example, in JP-A-49-74175, the center hole of the membrane leaf is liquid-tightly sealed, and the membrane permeate is taken out of the container from the outer peripheral portion of the membrane leaf, and the partition provided between the membrane leaves. Discloses a device which is fixed to a rotating shaft which penetrates the center hole of the membrane leaf in a non-contact manner and rotates to flow the liquid to be treated parallel to the membrane surface.

[0009]

[Problems to be solved by the device]

 The conventional rotary flat-bed membrane separation device has the advantage that it is not necessary to supply the liquid to be treated at a high flow rate as described above, but on the other hand, as is clear from FIG. The flow path is long because it flows in series between the leaves, and the pressure loss is significantly larger than when flowing in parallel between the membrane leaves even at the same supply flow rate. Therefore, the supply pressure must be increased in order to secure an effective filtration pressure, and the required energy increases accordingly.

[0010]

[Means for Solving the Problems]

 When the inflow and outflow of the liquid to be treated into the membrane separation device are given, the method of minimizing the flow pressure loss is to distribute the liquid to be treated so that the flow paths between each membrane leaf and the partition are all in parallel. That is.

That is, the present invention comprises a separation membrane on both sides of a flat plate-shaped support having a permeate flow passage therein, and a large number of membrane leaves, which are liquid-tightly sealed at their peripheral portions, are spaced from each other. Membrane leaf elements that are stacked and integrated, and that have an outflow part that discharges permeate from multiple membrane leaves, or flat plate-shaped partitions that are sandwiched alternately with the membrane leaves and stacked in multiple layers, The center of one of the flat plate-shaped partition elements, which is separate from the membrane leaf element, is passed through by the rotation axis, and these elements are arranged so that they can rotate relative to each other. In the case where the rotary shaft is penetrated, the rotary shaft is a hollow shaft through which the permeate flows out, and the permeate flow path of the membrane leaf and the hollow part of the hollow shaft communicate with each other through a small hole in the hollow shaft wall. In addition, the rotary flat membrane separation device is liquid-tightly sealed from the outside. Further, the rotary flat membrane separation device is characterized in that at least one of the membrane leaf group or the partition group is provided with a liquid passage hole at a portion close to the rotation axis.

According to the constitution of the present invention, the liquid to be treated is supplied in parallel to each membrane leaf through the liquid passage hole at a low pressure loss, and is caused by the relative rotational movement between the membrane leaf and the partition or between two sets of membrane leaves. Accelerated by centrifugal force, it can be carried to the outer periphery of the membrane leaf while being subjected to the membrane treatment, and can be discharged with a low pressure loss through the outer periphery of the membrane leaf and the partition and / or the liquid passage provided outside the periphery. ..

A further advantage of the present invention is that by providing parallel liquid supply paths to the respective membrane leaves near the center of rotation of the relative rotary motion, supply and discharge of the liquid to be treated are accelerated by centrifugal force. ..

When the membrane element is not housed in a compact pressure-resistant container and is directly immersed in the liquid to be treated, which has a larger capacity than the membrane element and has a small volume fluctuation, each membrane leaf is It seems that there are no obstacles to the supply and discharge. However, if the liquid to be treated is not forcibly supplied or discharged by external power, the AC portion between the liquid to be treated inside the membrane element and the liquid to be treated outside is only the outer peripheral portion of the membrane leaf, so the membrane surface In addition to the so-called concentration polarization that normally occurs in the normal direction of the membrane, concentration polarization also occurs in the radial direction of the membrane leaf. Relative rotary motion is effective in reducing the former, but almost insignificant in the latter. The only force acting to reduce the concentration polarization is diffusion with the concentration gradient in the radial direction as the driving force, and the degree of reduction in membrane performance due to concentration polarization is greater than in the case where there is flow in the radial direction. The larger the value, the more remarkable it becomes.

On the other hand, in the membrane element according to the present invention, the liquid passage hole provided in the vicinity of the hollow shaft and penetrating the membrane leaf substantially parallel to the hollow shaft acts as an inlet for the liquid to be treated by centrifugal force. It is expected that the flow in the circumferential direction of the leaf and the flow in the radial direction will be generated at the same time, and the concentration polarization in the radial direction will be effectively reduced.

Examples of the membrane leaf used in the present invention include polyolefins such as polyethylene and polypropylene, vinyl polymers such as polyvinyl chloride, polymethylmethacrylate and polystyrene, polyamides, polyimides, polyesters, polycarbonates, polysulfones and polyethers. A flat plate-shaped molded product made of plastic such as a condensation polymer of sulfone or the like with a permeated liquid channel formed on the surface or the inner layer, or a flat plate-shaped molded product made of these materials in a porous mesh such as a screen mesh or a nonwoven fabric. Flat plate with pressure and fluid flow paths such as stacked sheets, sintered plastic or metal granules, screen mesh, resin-processed woven fabric, woven fabric made of bristles, and non-woven fabric The membrane-shaped support was used as a membrane support, and polyacryloniton was applied to both surfaces of this membrane support. Use ultrafiltration membranes or microfiltration membranes such as rill-based, polysulfone-based, polyamide-based, polyolefin-based, etc. reverse osmosis membranes such as cellulose acetate-based, cross-linked polyamide-based, etc. and other flat plate-shaped separation membranes with selective permeation function. Examples thereof include those that are laminated and the outer periphery is sealed with an adhesive such as a polyurethane-based or epoxy-based adhesive.

Next, the case of forming the membrane element by penetrating the membrane leaf with the rotating shaft will be described.

The membrane leaf thus manufactured is fitted to a hollow rotating shaft, and the contact surface thereof is liquid-tightly sealed with an elastic O-ring, a spacer, an adhesive or the like. On the other hand, the inner space of the hollow rotating shaft and the permeate liquid flow path of the support are made to communicate with each other by a small hole provided in the rotating shaft wall.

In the present invention, a lightweight and flexible partition is preferably used. Examples of the material include polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyvinylidene chloride and polytetrafluoro. Examples thereof include, but are not limited to, vinyl polymers such as ethylene and polyvinylidene fluoride, condensation polymers such as polyamide, polyimide and polyester, and organic polymer films or sheets such as cellulose ester. ..

The partition according to the present invention has a concentric circular shape with a hole having a diameter larger than the outer diameter of the rotary shaft at the center thereof, and has a protrusion for engaging or the like on the outer periphery, or is not limited to a circular shape. The polygon may be a curve or a straight line connecting the protrusions.

A membrane element consisting of a membrane leaf and a hollow rotating shaft is usually formed by stacking 100 or more membrane leaves, and the membrane element length is suitably 1 to 3 m and is practical.

[0022]

【Example】

 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Embodiment 1 Embodiment 1 of the present invention is shown in FIGS. FIG. 1 is a vertical sectional view showing an embodiment of the present invention. FIG. 2 is a cross sectional view thereof. The outer peripheral portion of FIG. 2 shows the cylindrical container 1, the left half of the inner circular portion shows the membrane leaf surface, and the right half shows the partition surface.

In FIG. 1, separation membranes 8 are stacked on both sides of a disk-shaped membrane support 7, and disk-shaped separation membrane leaves 9 in which outer peripheral portions are bonded and sealed with an adhesive are stacked at regular intervals via an annular spacer 11. The hollow rotary shaft 4 is fitted and fixed. Grooves are radially provided on both surfaces of the disk-shaped support 7, and the permeated liquid flow path formed between the disc-shaped support 7 and the separation membrane 8 lined with the non-woven fabric has the small holes 6 provided in the hollow rotary shaft 4. It communicates with the hollow portion 10 of the rotary shaft. The membrane element consisting of the membrane leaf 9 and the hollow rotary shaft 4 is liquid-tightly connected by the annular spacer 11. A partition 5 punched out from a flexible film sheet is inserted between each membrane leaf 9, and rotation is suppressed by inserting and fixing between the rings of the cylindrical container 1 formed by stacking ring-shaped units. It

The liquid to be treated is supplied from the liquid inlet 2 provided at one end of the cylindrical container 1 to the liquid passage holes 12 provided in the inner peripheral portion of the respective membrane leaves 9 as supply channels for the liquid to be treated. Flow through between the surface of the rotating membrane leaf and the non-rotating partition 5 and lose the membrane permeate, and the liquid passage hole 13 provided in the outer periphery of the partition 5 discharges the liquid to be treated. As a flow path, it reaches the concentrate outlet 3 and flows out of the container.

The hollow rotary shaft 4 is supported by a bearing 14, and is rotated by a motor via a pulley 15 by a drive belt (not shown) or the like.

Example 2 Instead of the cylindrical container formed by stacking the ring-shaped units in Example 1, an integral cylinder was used as a cylindrical container. A cross section of this device is shown in FIG. The outer peripheral portion of FIG. 3 shows the cylindrical container 1, the left half of the inner circular portion shows the membrane leaf surface, and the right half shows the partition surface.

The outer diameter of the partition 5 is smaller than the inner diameter of the cylindrical container 1, and a plurality of protrusions (ears) 17 are provided on the outer peripheral portion. The liquid to be treated is supplied to the membrane leaf 9 through the liquid passage holes 12 provided in the inner peripheral portion of the membrane leaf 9, reaches the outer peripheral portion by the acceleration of centrifugal force while undergoing the membrane treatment, and passes through the gap 16. And is discharged to the outside of the container from the concentrated liquid discharge port 3 at the other end. The co-rotation of the partition 5 is prevented by forming a hole in the projecting portion 17 provided on the outer peripheral portion of the partition 5 and penetrating the co-rotation preventing rod 18 and fixing it to both ends of the upper and lower walls of the cylindrical container 1.

Example 3 An example in which the membrane element is fixed and the partition 5 is rotated is shown in FIG. As the membrane leaf and the partition, the same ones as in FIG. 3 were used.

In FIG. 4, the separation membranes 8 are stacked on both sides of the disk-shaped membrane support 7, and the disk-shaped separation membrane leaves 9 whose outer peripheral portions are bonded and sealed with an adhesive are stacked at regular intervals via the annular spacer 11. , Are fitted and fixed to the hollow shaft 41.

The disc-shaped support 7 is cut out from a screen mesh to form a permeate flow path of the separation membrane 8 lined with a non-woven fabric, and through the small hole 6 provided in the hollow shaft 41, the shaft hollow portion 10 Is in communication with. The membrane element 9 including the membrane leaf 9 and the hollow shaft 41 is liquid-tightly coupled by the annular spacer 11. An annular partition 5 with ears shown in the right half of FIG. 3 punched out from the flexible film sheet is arranged between the membrane leaves, and is fixed to the outer frame 21 outside the membrane leaf. The outer frame 21 is rotatably arranged via a hollow shaft 41 and a bearing 14, and is composed of upper and lower wheels 19 and a plurality of partition engagement rods 20 that connect the outer peripheral portions of these to the hollow shaft 41 in parallel. By passing through the hole provided in the ear portion 17 of the partition 5, the rotary motion of the outer frame rotated by the external power (not shown) via the pulley 15 and the drive belt (not shown) is transmitted to the partition 5. To do.

The liquid to be treated is promoted by the centrifugal force generated by the rotation of the partition 5, and passes through the holes (not shown) provided between the axles of the upper and lower wheels 19 or near the bearing 14 to the inner circumference of the partition 5. It is supplied to each membrane leaf through the gap between the ring spacer 11 and the annular spacer 11 and the liquid passage hole 12 provided in the inner peripheral portion of the membrane leaf 9, and is discharged to the outer periphery through the gap between the membrane leaf and the partition while losing the membrane permeated water. It

For the purpose of demonstrating the effect of the liquid passage hole 12, a disk-shaped membrane support 7 having an outer diameter of 130 mm and an inner diameter of 20 mm is cut out from a screen mesh having a wire diameter of 0.32 mm and an opening of 0.95 mm, and is cut on both sides thereof. Acrylonitrile-based ultrafiltration membrane DUY-L (manufactured by Daicel Chemical Industries, Ltd.) 8 was overlaid with the active layer facing outward, and the outer peripheral portion was sealed with an adhesive to prepare a membrane leaf 9-1. The membrane leaf 9-1 was provided with four liquid passage holes 12 having a diameter of 10 mm 5 mm outside from the outer circumference of the annular spacer 11 having an O-ring, and the periphery was sealed with an adhesive. For comparison, a membrane leaf 9-2 was produced in exactly the same manner except that the liquid passage hole 12 was not provided. For partition 5, a polyethylene film having a thickness of 0.3 mm was cut out from a film having an outer diameter of 130 mm and an inner diameter of 45 mm and having four protruding ears every 90 °. The manufacture using the membrane leaf 9-1 and the device using the membrane leaf 9-2 were assembled to the same size using the same parts except the membrane leaf.

The rotary flat membrane separation device 101 having the above-mentioned structure was used in 15 g of ovalbumin (manufactured by Wako Pure Chemical Industries, Ltd.) and 37 g of water-soluble starch (manufactured by Wako Pure Chemical Industries, Ltd.) in a 30-liter phosphate buffer solution. It is immersed in a solution dissolved in (pH 6.7), and as shown in FIG. 5, the upper end of the hollow shaft 41 is connected to a decompression line 106 via a valve 102, a permeated liquid amount measuring trap 103, a pressure gauge 104, and a three-way valve 105. Then, a membrane separation experiment was carried out with a negative pressure of 0.8 kg / cm ² on the permeate side. The results are shown in Table 1.

[0035]

[Table 1]

From the results of Table 1, the effect of the liquid passage hole 12 is clear. It is expected that this effect will increase as the outer diameter of the membrane leaf increases. That is, when there is no liquid passage hole, the driving force for reducing the concentration polarization in the radial direction is only the concentration gradient and is inversely proportional to the radius, whereas the eccentric force increases with the square of the radius.

[0037]

[Effect of the device]

 According to the present invention, a set of flat plate-shaped membrane leaves and a set of partitions or membrane leaves are alternately stacked, and the membrane leaves and the partitions or the second set of membrane leaves are relative to each other. In a rotatable rotary flat membrane separator, at least the membrane leaf fixed to the shaft located at the center of rotation or the inner periphery of the partition should be provided with a liquid passage hole so as to communicate preferably substantially parallel to the shaft. The liquid to be treated can be promoted by the centrifugal force generated by the rotation and supplied to the inner peripheral portion of the membrane leaf, and the film surface can be carried to the outer peripheral portion and discharged to the outside of the device. It is possible to provide a rotary flat membrane separation device that can sufficiently exhibit the membrane performance without being forcibly supplied and discharged by external power.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an apparatus according to a first embodiment showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a cross section of the device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a cross section of the device according to the second embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing an apparatus of embodiment 3 which is another embodiment of the present invention.

FIG. 5 is a schematic view showing an apparatus used for measuring the performance of the rotary flat membrane separation apparatus of the present invention.

FIG. 6 is a vertical cross-sectional view of a conventional rotary flat sheet membrane separator.

[Explanation of symbols]

 1 Cylindrical Container 2 Liquid Inlet 3 Concentrate Outlet 4 Hollow Rotating Shaft 5 Partition 6 Small Hole 7 Discoid Membrane Support 8 Separation Membrane 9 Membrane Leaf 10 Rotating Shaft Hollow 11 Ring Spacer 12 Liquid Passing Hole 13 Liquid Passing Hole 14 Bearing 15 Pulley 16 Gap 17 Protrusion (ear) 18 Co-rotation preventive rod 19 Outer frame wheel portion 20 Partition engaging rod 21 Outer frame 41 Hollow shaft 101 Rotary flat membrane separation device 102 Valve 103 Permeate measurement trap 104 Pressure gauge 105 three-way valve 106 decompression line

Claims (2)

[Scope of utility model registration request] 1. A flat plate-shaped support having a permeated liquid flow path inside thereof is provided with separation membranes on both sides, and a plurality of membrane leaves, which are liquid-tightly sealed at the periphery, are laminated at intervals from each other. The membrane leaf element is a membrane leaf element that is integrated and has an outflow portion that discharges permeated liquid from a large number of membrane leaves, or a flat plate-shaped partition that is sandwiched alternately with the membrane leaves and stacked in large numbers. One of the flat plate-shaped partitioning elements which is separate from the above is passed through the center of one of the rotating shafts, and these elements are arranged so that they can rotate relative to each other. In this case, the rotating shaft is a hollow shaft through which the permeate flows out, and the permeate flow path of the membrane leaf and the hollow portion of the hollow shaft communicate with each other through a small hole in the hollow shaft wall, and to the outside. Is a liquid-tight rotary flat membrane separation device, Is a rotary flat membrane separation device, characterized in that at least one of the partition groups is provided with a liquid passage hole near a rotation axis thereof. 2. The rotary flat membrane separation device according to claim 1, wherein the respective liquid passage holes provided in a portion close to the rotation shaft are communicated with each other substantially in parallel with the rotation shaft.