JPH02218421A - Spiral type liquid separation unit - Google Patents

Abstract

PURPOSE:To exhibit an excellent separation performance by using a net made of a mesh-type textile as a material for permeating liquid path of a liquid separation unit. CONSTITUTION:A liquid separation unit is fitted to a center tube 1 and has the first semi-permeable membrane 2 and a material 4b for permeating liquid path. Thickness (a) of a net is determined by a fineness (b) of monofilament and, therefore, it is possible to set up its thickness optionally by changing the thickness of monofilament. A minimum mesh size is restricted by a rigidity of fiber and the fineness (b) of the monofilament. As for a type of yarn, either multifilament or monofilament is usable. By using this construction, it is possible to improve a separation performance and durability of a spiral type liquid separation unit.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to improvement of a spiral type liquid separation element, and more specifically, to the structure of a permeate side channel material, which is one of the members of the spiral type liquid separation element. and regarding improvements in materials.

[Prior Art] Traditionally, spiral-type camphor separation elements using reverse osmosis membranes or ultrafiltration membranes have been mainstream. - A spiral type liquid separation element using a general reverse osmosis membrane has a central tube with a large number of water collection holes arranged in two rows in the tube axis direction, a first semipermeable membrane, a permeate side flow It is formed by winding a single set or multiple sets of units each including a channel material, a second semipermeable membrane, and a supply liquid side channel material. In liquid separation using a reverse osmosis membrane, a differential pressure of 5 kg/kg is usually applied between the feed liquid side and the permeate side in order to improve the separation performance of the reverse osmosis membrane and allow the process fluid to flow smoothly.
Operating pressures from about at to about 60 kg/cnf are applied, but among the channel materials mentioned above, especially the channel materials on the permeate side, the membrane can be maintained without impairing the function of the reverse osmosis membrane against the operating pressure. However, sufficient rigidity is required to properly maintain the flow path of the permeate. Also.

In order to improve the separation performance of the reverse osmosis membrane, it is desirable that the resistance of the channel formed by the channel material on the permeate side be kept as low as possible. In order to reduce the channel resistance, it is necessary to increase the porosity in the cross section of the channel material in the channel direction. In order to increase the membrane packing density, it is basically desirable that the channel material be as thin as possible.

This contradicts the requirement of low flow path resistance, and in reality, the optimum thickness is set by balancing the effects of each on performance.

In response to these characteristics, conventionally knitted fabrics have been used as the channel material on the permeate side of spiral-type liquid separation elements using reverse osmosis membranes.9 A typical example is tricot knitted fabrics made of polyester fibers knitted in a double-density structure. The tricot knitted fabric is made rigid by resin impregnation or heat fusion processing, or the tricot knitted fabric is further calendered to make the surface smooth, and the thickness is about 0°2 to 0.3 m+a. There is (
For example, Japanese Patent Application Laid-Open No. 62-35802). FIG. 3 shows a cross-sectional view of a tricot knitted fabric 4a as a channel material on the permeate side. Grooves 8, which are flow paths for permeated liquid, and protrusions 9, which hold the reverse osmosis membrane and secure the flow paths, are formed on its surface.

In recent years, as the degree of integration of semiconductors has increased, the required quality of ultrapure water used as cleaning water has also become stricter. Fifth
The figure shows a typical ultrapure water production system. In the primary pure water system (11-19), flocculant 11. A disinfectant 12 is injected, passed through a sand filtration 13, processed in a liquid separation device 16 using a reverse osmosis membrane, and further processed in an ion exchange resin column 19 to obtain primary pure water. Secondary pure water system (20~2
3. In the subsystem), the primary pure water is subjected to ultraviolet sterilization 21 and then subjected to Polylasha 22 (ion exchange treatment).
Process it with.

Thereafter, the water is processed in a module 23 using an ultrafiltration membrane to remove ionic substances, TOC, fine particles, etc., and produce ultrapure water.

In order to satisfy the water quality requirements for ultrapure water, which are becoming stricter with the increase in the degree of integration of semiconductors, recently, instead of ultrafiltration membranes in subsystems, liquid separation devices using reverse osmosis membranes have been used immediately before the point of use. is being considered.

In this case, the required characteristics of a spiral type liquid separation element using a reverse osmosis membrane include not only separation performance but also the absence of elution of ionic substances and TOC components from the element itself, and the absence of shedding of fine particles. It is important that no abnormal liquid accumulation occurs inside the liquid separation element. In order to satisfy these characteristics, the parts of the liquid separation element that come into contact with the permeated liquid must be made of materials that have extremely low elution of ionic substances and TOC components, and must have a structure that does not allow particulates to fall off or abnormally accumulate. There is a need.

Examples of the member that comes into contact with the permeated liquid include the aforementioned permeated liquid side channel material. Traditionally used tricot knitted fabrics made of polyester fibers are heat-sealed and calendered, so although they satisfy water quality for fine particles and TOC within the range of current measurement technology,
There was a problem with resistivity, which is a water quality indicator related to more sensitive ionic substances. In other words, the elution of ionic substances is small from the initial stage, but this elution rate is maintained for a long period of time.
This is due to the occurrence of an abnormal stagnation part in the permeate flow path.

Therefore, the efficiency of cleaning the components was also very low. Furthermore, even when using a conventional spiral liquid separation element that uses this channel material and using ultrapure water as the feed water, the specific resistance of the permeate reaches the same level as the feed water. It took a lot of time and the so-called rise characteristics were extremely poor. Poor rise characteristics lead to a decrease in water yield.

In turn, this becomes a factor that increases the manufacturing cost of ultrapure water.

Here, the abnormal tricot retention part will be explained using the drawings. FIG. 2 shows a first semipermeable membrane 2. attached to the central tube 1. FIG. 3 is a plan development view of one embodiment of the permeate side channel material 4 (tricot knitted fabric) and the second semipermeable membrane 3. FIG. In the process of manufacturing a spiral type liquid separation element, the first and second
The semipermeable membrane is opened only in the central canal 1, and the other three sides are sealed with adhesive 6 to form an envelope. However, since it is wrapped around the central canal before the adhesive hardens, the adhesive near the central canal is The range of agents becomes wider. FIG. 3 is a sectional view taken along line XX in FIG. 2. As shown in the figure, water flows well in the direction of the grooves of the tricot knitted fabric (towards the center tube), but there is more than 10 times the resistance in the direction perpendicular to the grooves. Therefore, if the flow path of the permeated liquid collected in the central pipe through the tricot groove is blocked by the adhesive as described above, the entire area becomes an abnormal stagnation area 7 as shown in Fig. 2. . Due to the phenomenon described above.

In addition to the decrease in specific resistance, the effective membrane area of the spiral liquid separation element becomes smaller than the actual membrane area (the area where adhesive is not applied), which reduces the amount of permeated liquid and even causes abnormalities. There was also concern that microorganisms would proliferate in the retention area.

[Problems to be Solved by the Invention] In order to improve the deficiencies of the prior art as described above, the present invention uses a mesh-like woven fabric net as the channel material on the permeate side, thereby improving the inside of the channel material on the permeate side. Eliminate abnormal retention area
It exhibits excellent performance in specific resistance, TOC, and particle rise characteristics in the ultrapure water subsystem, and can demonstrate and maintain excellent separation performance over a long period of time without damaging the reverse osmosis membrane. The present invention aims to provide a spiral type liquid separation element.

[Means for Solving the Problems] The present invention provides a first semipermeable membrane, a permeate channel material, a second semipermeable membrane, and a feed liquid channel around a hollow central tube having holes on its surface. A spiral type liquid separation element formed by winding a single set or multiple sets of units made of material, characterized in that a net made of a mesh-like fabric is used as the permeate channel material of the unit. This invention relates to a spiral type liquid separation element.

The net may be any mesh-like fabric, but preferably a sieve screen (porting cloth) and/or a filter cloth.

The woven structure of the net may be any structure as long as it has a structure that ensures a flow path for the permeated liquid and allows the permeated liquid to disperse and flow in all directions. Plain weave structures are common, but there are also special weave structures such as twill weave, herring twill weave, and satin weave, as well as paper structures.The fabric materials (fibers) retain their shape under operating pressure. Any material may be used as long as it has sufficient mechanical strength, but polyamide fibers (such as nylon), polyester fibers, polyacrylonitrile fibers, and polyolefin fibers such as polyethylene and polypropylene are preferable.

Polyvinyl chloride fibers, polyvinylidene chloride fibers, fluorine fibers (polyfluoroethylene, etc.).

Examples include carbon fiber. Especially when applying liquid separation elements to ultrapure water subsystems, specific resistance and TOC
Polypropylene fibers and/or fluorine-based fibers are more preferable because they have low elution of ionic substances and organic substances in consideration of the rise characteristics of the fibers, have sufficient heat resistance to withstand hot water sterilization, and are economical. .

The type of yarn is generally multifilament, monofilament, or a mixture of both, but monofilament is more preferable when it is applied to an ultrapure water subsystem, considering the cleaning efficiency of the nine members and the rising characteristics of fine particles.

Next, a detailed explanation will be given using figures. Similar to FIG. 3, FIG. 4 shows a first semipermeable membrane 2. A cross-sectional view of the permeate channel material 4b (monofilament plain weave net) and the second semipermeable membrane 3 in the XX direction as shown in FIG. 2 is shown.

The thickness a of the net is determined by the size b of the monofilament, and can be arbitrarily set by changing the thickness b of the monofilament. The pitch (pitch) C can also be set arbitrarily, but
The minimum value of rotation is limited by the stiffness of the fiber and the thickness b of the monofilament.

The thickness of the net is a, and the thickness of the monofilament is.

The setting of the filament ratio C depends on the operating conditions of the element (operating pressure, amount of water produced), the rigidity or mechanical strength of the monofilament, the flow path resistance depending on the fabric structure, the membrane packing density, and the function of the semipermeable membrane. It is necessary to consider that the permeate flow path can be maintained stably for a long period of time. Considering the above-mentioned required functions, the net used in the spiral type liquid separation element used in the ultrapure water subsystem should have a net thickness a of 0.1 to 2.0 mm and a filament ratio C of 0.15. A range of 3.0 mm is desirable.

Because the net made of mesh-like fabric has the above-mentioned advantages, it is possible to provide a liquid separation element with extremely excellent rise characteristics in an ultrapure water subsystem, and it can also be used in a conventional spiral type liquid separation element. It is possible to improve the separation performance and durability of the device, and also make it easier to clean and sterilize the device.

[Examples] Example 1 Monofilament made from polypropylene was plain-woven as a channel material on the permeate side. A tricot knitted fabric made by knitting a monofilament mesh of 50 x 50 mesh/1 nch with a thickness of 0゜2M and a multifilament polyester fiber, which has been used conventionally as a comparative example, into a double-density structure, and then hardening it by heat treatment is further calendered. Using each processed material, a spiral type liquid separation element with an outer diameter of 4 inches was manufactured. In the ultrapure water production system shown in FIG. 5, a spiral type liquid separator was installed after the polyrusher subsystem, and the rising characteristics of the resistivity of the separation elements were compared. The specific resistance of the supply water is 18.20MΩ・country, and the operating pressure is 10K.
g/a/, temperature 25℃, launch amount 4T/day9 recovery rate 90%
Figure 6 shows the results of the operation. In a spiral type liquid separation element manufactured using a conventionally used channel material, the resistivity did not reach the level of the feed water even after approximately 100 hours of operation, and 18. In contrast, the spiral type liquid separation element manufactured using monofilament plain weave net as the channel material reached the supply water level (18, 20 MΩ cm) within 2 hours after starting operation. We were able to significantly reduce the rise time. After another 10 hours, the theoretical specific resistance value of pure water reached 18.25 MΩ.

Example 2 Regarding the permeate side channel materials used in Example 1, 300
Table 1 shows the results of measuring the flow resistance over time at a pressure of 15 kg/car. Although the thickness of the channel material of the conventionally used tricot knitted fabric is 0.25 mm, and the thickness of the plain weave net is 20% thinner, the initial value of flow resistance can be reduced by 10%. did it. Also,
The rate of change in flow resistance after 300 hours was 5%, indicating durability comparable to that of tricot knitted fabrics.

Table 1 Table 2 Example 3 A spiral type liquid separation element was manufactured in the same manner as in Example 1, and the temperature was 0.15 at an operating pressure of 15 kg/car and a temperature of 25°C.
% saline separation performance was compared. The results are shown in Table 2. The separation element using a plain weave net increased the amount of water produced by about 10% compared to the one using a tricot knitted fabric, and the water quality of the permeated liquid was also improved by about 40%.

[Effects of the Invention] The present invention improves the prior art as described above and has the following effects.

(1) The surface ratio of the channel material is improved, and the deformation of the membrane is minimized, thereby preventing the performance of the liquid separation element from deteriorating and significantly extending its life.

(2) It is possible to make the channel material thinner, increasing the membrane packing density accordingly, and by eliminating the reduction in effective membrane area due to spread of adhesive, the Permeate volume increases.

(3) Due to the elimination of abnormal stagnation in the permeate side flow path and the use of low elution type fibers for the flow path material, the start-up characteristics are extremely high when applied to ultrapure water subsystems. This contributes to improved water quality and yield of ultrapure water.

(4) By using monofilament.

When applied to ultrapure water subsystems, it becomes possible to reduce the number of falling particles to below the detection limit of current measurement technology, improving the quality of ultrapure water.

(5) The propagation of microorganisms in the permeate side flow path can be prevented, and hot water sterilization and cleaning are also facilitated.

It can also be suitably used in the food field.

Note that the device according to the present invention can be applied not only to spiral type liquid separation elements applied to ultrapure water subsystems but also to all spiral type liquid separation elements, and the field of use thereof is extremely wide.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a spiral type liquid separation element according to the present invention. FIG. 2 is a developed plan view of one embodiment of a spiral-type liquid separation element according to the prior art, showing an abnormal stagnation part of the conventional element. FIG. 3 is a sectional view taken along line XX in FIG. 2 when a tricot knitted fabric is used as a permeate channel material in a liquid separation element according to the prior art. Figure 4 shows the X of the liquid separation element when monofilament plain weave net is used as the permeate channel material according to the present invention.
-X sectional view. FIG. 5 is an example of a schematic diagram of an ultrapure water production system. FIG. 6 is a diagram showing the rising characteristics of resistivity in the ultrapure water subsystem of the spiral type liquid separation element according to the present invention and the spiral type liquid separation element according to the prior art. 1: Center pipe 1b = Water collection hole 2: First semipermeable membrane 4: Permeated liquid side channel material 4a Mini tricot fabric 4b: Permeated liquid channel material 5: Supply liquid side channel material 6: Adhesive 7: Abnormal retention area 8
: Groove 9: Protrusion 10: Fabric 11: Coagulant 12: Disinfectant 13: Sand filtration 14: Security filter. 15: High pressure pump 16: Liquid separation device 17: Permeated water tank 18: Deaeration tower 19: Ion exchange resin tower 20:
Primary pure water tank patent applicant Azuma Shi Co., Ltd. Factor 5 Figure 6 Operating time [hr]

Claims (1)

[Claims] A single set or multiple sets of units each including a first semipermeable membrane, a permeate channel material, a second semipermeable membrane, and a supply fluid channel material around a hollow central tube having holes on its surface. What is claimed is: 1. A spiral-type liquid separation element comprising a spiral-type liquid separation element in which a permeate channel material of said unit is a net made of a mesh-like fabric.