JPS6235802B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to an improvement of a liquid separation device using a semipermeable membrane, and more particularly, to a liquid separation device that improves the separation performance and durability of a liquid separation device using a reverse osmosis membrane. . [Prior Art] Conventionally, many liquid separation devices using semipermeable membranes are known that utilize principles such as dialysis, ultrafiltration, and reverse osmosis. In particular, devices based on principles such as reverse osmosis pressure have the disadvantage that the durability of the device is low due to the large pressure applied to the stock solution (liquid to be treated) compared to other devices. Figure 4 shows a conventional device (for example, JP-A-54-
31087) is a cross-sectional view of a mechanism for separating the stock solution. As shown in FIG. 4, when the stock solution is brought into contact with the reverse osmosis membrane under pressure as shown by the arrow from the upper surface of the reverse osmosis membrane 13 supported by the permeate channel material 14, a portion of the stock solution will pass through the reverse osmosis membrane. Transmits through the membrane 13,
The remaining stock solution will be concentrated. The permeated liquid then flows along the grooves 21 of the permeated liquid channel material 14 and is collected. In this case, a tricot knitted fabric is usually used as the permeate channel material 14,
Protrusions 25 and grooves 21 formed on the surface are utilized. However, in the device of this type, as a result of the reverse osmosis membrane 13 being pressed against the channel material 14 under high pressure, the reverse osmosis membrane 13 is shaped to follow the unevenness of the surface of the channel material 14 as shown in the figure. deformed, stretched,
As a result, this has the adverse effect of reducing the salt removal rate of the membrane. Furthermore, in the case of highly deformed membranes or membranes with low fracture elongation, this deformation often has the disadvantage of partially cracking or tearing, which reduces the quality of the permeate. ,
Further, the defect that the above-mentioned phenomenon progresses over time during long-term operation cannot be avoided. Another known example uses a plate (Japanese Unexamined Patent Publication No. 57-209603), but this is inconvenient because it lacks flexibility and can only be used as a plate-like module. [Problems to be Solved by the Invention] In order to improve the above-mentioned deficiencies of the prior art, the present invention uses a calendered fabric as a flow channel material, so that the semipermeable membrane can be maintained for a long period of time without being damaged. Therefore, it is an object of the present invention to provide a liquid separation device that can exhibit excellent performance. [Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. "A semipermeable membrane is interposed between the stock solution flow path and the permeate flow path, and the stock solution is brought into contact with the semipermeable membrane under pressure to separate it into a concentrated liquid and a permeate that passes through the semipermeable membrane. In the liquid separation device configured as follows,
A liquid separation characterized in that a fabric in which grooves and protrusions are formed by calendering and the surface of the protrusions is smoothed is used as a channel material for the permeate interposed between two semipermeable membranes. Device. In the present invention, it is preferable that the calendered fabric is a tricot knitted fabric using polyester fibers from practical aspects such as cost and shape stability. FIG. 1 is an axial sectional view of the device according to the present invention, and FIG. 2 is a sectional view taken along line XX in FIG. In FIGS. 1 and 2, a cylindrical container 1 contains a liquid separation element 4 and is sealed by side lids 2 and 3. Further, the cylindrical container 1 is provided with a stock solution supply pipe 5 for supplying the stock solution as the liquid to be separated and a stock solution discharge pipe 6 for discharging the stock solution, and the liquid separation element 4 is further provided with a permeated liquid discharge pipe. 7 is connected. Further, a sealing portion 17 is provided between the liquid separation element 4 and the cylindrical container in order to smoothly guide the concentrate into a spirally configured concentrate passage 20 of the liquid separation element 4 as described later. As shown in FIG. 2, the liquid separation element 4 has a hollow tube 8 in which a large number of small holes 9 arranged in rows in the axial direction of the tube is arranged on the wall surface of the center part, and the liquid separation element 4 has a hollow tube 8 in which a large number of small holes 9 are arranged in rows in the tube axis direction. A permeate discharge pipe 7 for guiding the permeate to the outside is connected to the hollow tube 8. Two reverse osmosis membranes 13 and 13' are attached to the hollow tube 8 with one end thereof glued so as to cover the small hole 9, and the reverse osmosis membrane 1
A permeate flow path 24 is formed between 3 and 13', and a porous permeate flow path material 14 having grooves 21 on the surface is inserted into the flow path 24, and the end thereof is connected to the blockage part 1.
0 and is liquid-tightly bonded. Then, glue one end to the hollow tube 8 as described above,
Reverse osmosis membrane 13, 1 whose other end is bonded with a closing part 10
A channel material is inserted between 3' and wound spirally around the hollow tube, and the ends of the wound material are fixed by end seals 16 and 16', and the permeated liquid in the stock liquid passage 20 is Each of the flow channels 24 is sealed liquid-tightly. For the liquid separation device having the structure described above, the stock solution is supplied from the stock solution supply pipe 5 by the solvent, solute type, concentration, etc. of the stock solution.
The vortex is fed at a pressure higher than the osmotic pressure determined by the type, thickness, etc. of the reverse osmosis membrane, and after filling the space 18 of the cylindrical container 1, the vortex opens on the outer circumferential generatrix 12 of the liquid separation element 4. It is led to a stock solution passage 20 that is configured linearly. The concentrated liquid that has entered the interior of the liquid separation element 4 along the concentrated liquid passage 20 changes its flow direction to the direction along the hollow tube 8 in the vicinity of the hollow tube 8, and passes through the transparent tube provided in the end seal 16'. Hole 2
3, and is discharged out of the system from the stock solution outlet 6 through an empty tube 19 in a space surrounded by the side cover 3 of the cylindrical container 1 and the end seal 16' of the liquid separation element 4. In this process, the permeate that has passed through the reverse osmosis membranes 13 and 13' passes through the porous pores of the permeate channel material 14 and is collected in the grooves 21 of the channel material 14, forming a spiral-shaped permeate channel. 24 to the tube wall of the hollow tube 8, and is taken out of the system from the permeate discharge tube 7 through a small hole 9 provided in the tube wall. FIG. 3 is a sectional view showing the structure of the permeate flow path 24. As is clear from FIG. 3, reverse osmosis membranes 13, 13'
The permeated liquid that has passed through is further guided to the hollow tube 8 through the groove 21 provided on the surface of the channel material 14. In order for the solvent to be separated from the stock solution through the reverse osmosis membrane, as described above, a high pressure exceeding the osmotic pressure in the system is applied to the stock solution. pressed strongly against the surface of For example, when separating water from seawater, this pressure is 40 kg/kg, depending on the type of membrane.
cm ² (G), or as high as 70Kg/cm ² (G), and this pressure forces the semipermeable membrane against the channel material as shown in Figure 4, causing so-called emboss deformation. . In the device according to the present invention, minute irregularities on the surface of the channel material shown in FIG. 3 are crushed by calendering, and
It has a very smooth surface. Therefore, as shown in FIG. 5, the embossed deformation of the membrane occurs only in the grooves of the channel material and is suppressed to a minimum. In addition, since the thickness of the channel material decreases during calendering,
The membrane packing density can be increased, and the amount of permeate per unit volume of the separation device can be increased. This tendency becomes especially noticeable when the product is used for a long period of time. That is, the device of the present invention can operate stably for a long period of time. The conditions for calendering applied in the present invention are as follows:
Depending on the physical properties of each channel material, the best liquid separation device can be selected, taking into account the effect of preventing membrane deformation and the effect of reducing the cross-sectional area of the permeate channel due to the thinning of the channel material. It is necessary to configure settings to maximize performance. Generally, load is 20 to 50 tons/full width, temperature is 30
The optimum point can be selected within the range of ~180℃ and feed rate of 5~20m/min. [Examples] Example 1 As a permeate flow channel material, a tricot knitted fabric was produced by knitting a yarn mainly made of polyethylene terephthalate into a double-density structure and hardening it by heat treatment. Calendared product of the above channel material (3rd
With the shape shown in number 14 in the figure, the thickness of the tricot knitted fabric is 220 μm, the depth of the groove is 90 μm, and the width of the groove is 200 μm.
m, the width of the smooth surface on the protrusion is 420 μm,
A spiral-type liquid separator with a diameter of 8 inches was manufactured using a non-calendered product (grooves in a stripe shape) and a non-calendered product as a comparative example, and their performances were compared. Table 1 shows the results of operation using 3.5% saline as the stock solution at a pressure of 56 Kg/cm ² (G) and a temperature of 25°C. Calendering improves the salt removal rate of the liquid separator and reduces the water quality of the permeate by 25%
Improved. Also, the membrane area per unit volume is approximately 10%
The amount of permeate increased almost correspondingly.

【table】

[Table] Example 2 A module was made in the same manner as in Example 1, and the pressure
Changes in the thickness of the channel material (tricot knitted fabric) after 100 hours of operation at 60 kg/cm ² were measured. As a result, the thickness of the calendered material changed by 5%, while the thickness of the non-calendered material changed by 15% and became thinner. Table 2 shows the changes in salt rejection rate and amount of water produced, and the calendered products had excellent durability.

[Table] [Effects of the Invention] The present invention improves the prior art as described above and has the following effects. (1) The surface smoothness of the channel material is improved and the deformation of the membrane is minimized, thereby preventing a drop in the performance of the liquid separation device and significantly extending its life. (2) Since the channel material becomes thinner, the membrane packing density can be increased accordingly, which increases the amount of permeated liquid per unit volume of the liquid separation device. The device according to the present invention can be applied to not only the spiral type but also the tubular type and all other liquid separation devices having a structure using a permeate channel material, and its field of use is extremely wide.

[Brief explanation of the drawing]

FIG. 1 is an axial cross-sectional view of the device according to the invention, and FIG. 2 is a cross-sectional view taken along line XX in FIG. FIG. 3 is a cross-sectional view showing the structure of the permeate flow path in the device according to the present invention, and FIG. 4 is a cross-sectional view showing the state of the permeate flow path during pressurization in the conventional device. FIG. 5 shows a situation in which membrane deformation is reduced by employing the present invention in comparison with FIG. 4. 4: liquid separation element, 13, 13': reverse osmosis membrane,
14: Permeate channel material, 15: Raw solution channel material, 20:
Raw solution passage.

Claims (1)

[Scope of Claims] 1. A semipermeable membrane is interposed between the stock solution flow path and the permeate flow path, and the stock solution is brought into contact with the semipermeable membrane under pressure, so that the concentrate passes through the semipermeable membrane. In a liquid separation device configured to separate into permeate and permeate,
A liquid separation characterized in that a fabric in which grooves and protrusions are formed by calendering and the surface of the protrusions is smoothed is used as a channel material for the permeate interposed between two semipermeable membranes. Device. 2. The liquid separation device according to claim 1, wherein the calendered fabric is a tricot knitted fabric using polyester fibers.