JPH02307513A - Liquid separator - Google Patents

Abstract

PURPOSE:To prevent deterioration of the velocity of permeation by providing the supporting plates to the secondary chamber side of the permselective membranes and forming the supporting plates of the sintered metallic bodies and providing a heating means to the insides of the sintered metallic bodies. CONSTITUTION:The mixed liquid of water and alcohol which is continuously supplied into a primary chamber 11a of a first feed side is allowed to slowly flow to the upper side from the lower side through the inside of the primary chamber 11a. The permselective membranes 18a-18c are formed of a water permselective amorphous high molecular membrane which allows only the aimed water component to selectively permeate therethrough. The water component corresponding to the selection characteristics is permeated to the secondary chambers 13a, 13b from the primary chambers 11a, 11b at the temp. of the mixed liquid at the velocity of permeation described hereunder. Thereby the excellent separation performance is obtained. This velocity of permeation is made proportional to the difference of the concn. of the selective component between the primary chambers 11a, 11b sides of the first and second feed sides of the mixed liquid and the secondary chambers 13a, 13b sides of the first and second takeout sides of separated liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a liquid separation device using pervaporation.

(Prior Art) Generally, in the field of chemical industry, so-called organic solvents such as alcohols, ketones, ethers, and esters are often used. All of these organic solvents have the property of easily dissolving water and of being easily dissolved in water. Therefore, even in its storage state, it is relatively mixed with water and forms an azeotrope with the water.

However, when the above-mentioned organic solvent is used in an actual chemical reaction, extremely high purity is required, and in most cases, severe restrictions are imposed on the mixing of the above-mentioned water.

For this reason, in actual use, it is common to employ a concentration system in which water is separated from the organic solvent to increase purity as a pretreatment step.

Conventionally, a distillation method has generally been employed as a method for separating water (pure water) from a mixture of water and an organic solvent such as alcohol as described above and concentrating the organic solvent.

However, in the case of distillation, azeotropic mixtures (mixtures of different substances with different boiling points but having azeotropic points),
It is difficult to separate near-boiling mixtures. The above-mentioned mixture of water and alcohol (ethanol) corresponds to the azeotropic mixture, and therefore cannot be separated by the above-mentioned conventional distillation method.

Therefore, in such cases, a so-called azeotropic distillation method is sometimes adopted, which enables separation by adding a predetermined tertiary component (benzene, trichlorethylene, etc.) as an entrainer (azeotropic agent). However, this method consumes an extremely large amount of steam, and there are many new problems such as contamination of the separated liquid due to contamination of tertiary components and complication of the equipment.

Against this background, research and development have been particularly active in recent years, such as the separation (dehydration) of water/organic liquid mixtures by pervaporation using water-selective permeable membranes.
There is a system (for example, see the specification and drawings of Japanese Patent Application Laid-Open No. 58-128107).

This liquid mixture separation system is generally called a "pervaporation system," and is, for example, a water-containing target mixed liquid (feed ) is supplied, and a secondary chamber where the permeated target separated component (gas) is condensed and stored is separated, and the secondary chamber side is evacuated by a pressure reducing means such as a vacuum pump. forming a partial pressure difference of a predetermined value or more between the primary chamber-side boundary surface and the secondary chamber-side boundary surface of the moisture selective permeable membrane by reducing the pressure to a state;
According to the partial pressure difference and the concentration difference of the selected component between the primary side and the secondary side, each step of adsorption-dissolution → diffusion → desorption is performed from the high-pressure side (primary chamber side) according to its permeation rate. Only the water molecules (Hlo) that permeate through the chamber are taken out in a gaseous state to the secondary chamber on the low pressure side.

Therefore, with the liquid mixture separation system having such a configuration, it is possible to separate and concentrate not only near-boiling liquid mixtures but also azeotropic liquid mixtures such as water and alcohol mentioned above without any problem. Furthermore, unlike azeotropic distillation, it does not use any tertiary components, so it is clean and has the advantage of being compact in size.

In an actual system, the combination of the primary chamber and the secondary chamber as described above is modularized as a single unit, and multiple pairs of these are combined in series to circulate the mixed liquid. It is often used as a plant.

-By the way, the pervaporation operation in such a liquid separation device is a separation operation that essentially involves a phase change (liquid phase - gas phase), as is clear from the above explanation, so the progress of the separation state is , the permeating molecule (in the above example, the water molecule H3
0) The temperature of the feed liquid around the permeable membrane gradually decreases due to the latent heat of vaporization. The permeation rate in the permeable membrane section is proportional to the temperature of the primary chamber side supply liquid, and the higher the temperature and the more active the molecular activity, the higher the permeation rate (for example, the third
(see figure). Therefore, as mentioned above, when the temperature of the feed liquid decreases, there is a problem that the permeation rate of the target liquid decreases and the separation efficiency deteriorates, which has been an important technical problem to be solved.

(Problems to be Solved by the Invention) In order to solve such technical problems, for example, in the above-mentioned conventional example, an independent heating heat exchanger is installed in the middle of the external mixed liquid passage of the module, and the mixed liquid is heated at a lower temperature. This is countered by a configuration in which the liquid is sequentially reheated and supplied to the next separation module, but this method creates a considerable temperature difference in the mixed liquid between the intake side and the outlet side of the separation module. However, the problem has not yet been fully resolved. It also has the disadvantage of complicating the passage structure and increasing passage resistance.

The amount of decrease in temperature that causes the decrease in permeation rate as described above is ultimately proportional to the amount of permeation (vaporization) of the target component, so
This becomes a particular problem when the concentration of the target component (water) in the feed side mixed liquid is high compared to when the concentration of the target component (water) is low.

(Means for Solving the Problems) The inventions of claims 1 to 3 of the present application have been made for the common purpose of solving the above-mentioned conventional problems, and each of them is based on the following techniques. The system is equipped with practical problem-solving means.

(1) Means for solving the problem of the first invention In the liquid separation device of the first invention, predetermined mixed liquids F ir++ and F int containing the liquid to be separated and other liquids are used.
mixed liquid supply side primary chambers 11a, 11b to which the mixture is supplied;
The mixed liquid supply side primary chamber 11a.

Selective permeable membrane 18a for pervaporation with respect to zb.

The separation side secondary chamber 13a is in contact with each other via 18b and 18c.

13b, and a predetermined pressure difference forming means connects the primary chambers 11a, 11b on the mixed liquid supply side and the second chamber on the separation/liquid extraction side.
The selectively permeable membrane 18a between the next chambers 13a and 13b,
In a liquid separation device that separates a target liquid by forming a predetermined pressure difference necessary for pervaporation separation action through the selectively permeable membranes 18a, 18b, L8c, The selectively permeable membrane 18a is provided on the side surface of the second chamber.

Support plates 9, 10.12 for reinforcing and supporting 18b, 18c are provided, and the support plates 9, 10.12 are made of a porous metal sintered body, and a heating means 17a is provided inside the metal sintered body.
, 17b, and 17c.

(2) Means for solving the problem of the second invention: In the configuration of the liquid separation device according to the second invention, the heating means 17a, 17b in the configuration of the liquid separation device according to the first invention.
, 17c are constituted by hot water circulation pipes.

(3) Means for Solving the Problem of the Third Invention The liquid separation device of the third invention includes the heating means 17a, 17b, l in the structure of the liquid separation device of the first invention.
7c is constituted by an electric heater.

(Function) (1) In the liquid separation device of the first invention, the primary chamber side to which the mixed liquid is supplied and the separated liquid adjacent to the primary chamber via the selective permeation membrane. By forming a predetermined pressure difference between the secondary chambers on the extraction side by a pressure difference forming means, a partial pressure difference necessary for pervaporation separation action is created, and the target liquid component (verminiite) is separated. In the liquid separation device, since the selective permeation membrane is supported by a porous support plate made of a metal sintered body, a sufficient reinforcing effect of the permeation membrane can be obtained without impairing the permeation function. The durability can be improved.

A predetermined heating means is disposed within the porous support plate made of the metal sintered body, and the heating means heats the entire surface of the selectively permeable membrane and the opposite side thereof through the entire surface of the support plate. The mixed liquid near the temperature boundary layer near the surface is heated and heated effectively and uniformly. As a result, a temperature boundary layer due to latent heat of vaporization is also less likely to occur.

(2) Furthermore, in the liquid separation apparatus according to the second aspect of the invention, since the above-mentioned heating means is constituted by a hot water circulation pipe, the heat source is inexpensive and clean.

(3) Further, in the liquid separation apparatus of the third aspect of the invention, since the heating means is formed by an electric heater as described above, thermal efficiency is high and temperature control is easy.

(Effects of the Invention) Therefore, according to the inventions of the above-mentioned claims of the present application, it is possible to provide a liquid separation device with high separation efficiency, excellent durability, and high precision.

(Embodiment) FIGS. 1 and 2 show a module structure of, for example, a plate-and-frame liquid separation device according to an embodiment of the present invention.

In FIG. 1, reference numerals 1a and 1b denote predetermined widths that form first and second mixed liquid supply side primary chambers 11a and 11b for supplying the mixed liquid, respectively, as shown in FIG. First, the first frame 1a has a first mixed liquid supply port 4a connected to the feed tank FT via the feed pipe 3, for example. It is located at the upper part of the front end (front side). In addition, at the lower part of the rear end side (rear side), there is a channel for discharging concentrated alcohol (C*HsOH), for example, after the target separation liquid (permeate), water (8,0), has permeated and been removed. One concentrated liquid outlet 5a (shown by broken lines) is provided. Further, the second frame tb is provided with a second mixed liquid supply port 4b corresponding to the position (lower rear side) of the first concentrated liquid outlet 5a of the first frame la. The second mixed liquid supply port 4b is connected to the first concentrated liquid discharge port 5a via a U-shaped connecting pipe 7. Therefore, the first mixed liquid supply port 4a
The mixed liquid (feed) F in, supplied from the ? The liquid mixture is led from the discharge port 5a to the second mixed liquid supply port 4b through the U-shaped connecting pipe 7, and then supplied into the second primary chamber zb as a second mixed liquid F ins. 2nd above
A second concentrated liquid outlet 5b is similarly provided at the upper part of the other end of the frame lb, and the second concentrated liquid outlet 5b is connected to the first
The supplied mixed liquid P int in the firebox 11b is discharged from the second concentrated liquid discharge port 5b via the pipe 8 to the next processing chamber.

On the other hand, symbols 1 c and 1 d indicate the fifth frame l located between the first and second frames la and l b.
The third and fourth parts of a predetermined width are integrally joined and fixed via e.
This is a frame, and a plate-shaped porous plate metal sintered body 9.10 is fitted and fixed inside each of the third and fourth frames 1c and 1d. On the other hand, reference numerals 18a and 18b are integrally bonded to the side surfaces of the respective primary chambers of the third and fourth frames lc and ld in which the metal sintered bodies 9 and 10 are fitted, respectively. ．． The eleventh and second selectively permeable membranes (described later) are supported by lO.

As shown in the figure, hot water circulation pipes 17a and 17b are buried inside the metal sintered body 9.10.

Further, a first and second fire chamber 13a for taking out the separated liquid is formed in the fifth frame ie interposed between the third and fourth frames lc and ld. Firebox 1
3a has a vacuum pump connection port 14b formed at the lower rear end of the fifth frame 1e. and,
The gaseous separated liquid that has been permeated and separated is drawn out together with air through the vacuum pump connection port 14b. Also, in line with the second frame tb, a third selectively permeable membrane 18c, each of the seventh and sixth frames 1g+
1 f are installed in parallel. The seventh frame tg includes the 3.14th frame L/-frame 1c.

As in the case of ld, a plate-shaped metal sintered body 12 is fitted, and a hot water pipe 17c is buried therein.

Therefore, as a result, inside the sixth frame If,
A second secondary chamber 13b for taking out the separated liquid is formed, and the separated liquid is taken out through the connection port 15b.

The hot water circulation pipes 17a, 17b, and 17c uniformly heat the selectively permeable membranes 18a, 18b, and 18a themselves via the metal sintered bodies 9, 10.12, and further heat the selectively permeable membranes 18a, 18b, and 18a themselves. Selective permeable membranes 18a, 18b,
The selectively permeable membrane 18a via 18c.

It also heats the mixed liquid near the separation surface of the tab to prevent the generation of the temperature boundary layer as described above and to maintain the separation performance as high as possible.

That is, the hot water circulation pipes 17a, 17b, 17C pass through the first and second selectively permeable membranes 18a, 18b, respectively, via the porous metal sintered bodies 9, 10.12.

18c, the selectively permeable membranes 18a, 18b, 18c pass through the entire surface of the highly thermally conductive porous metal sintered body 9, 10° 12. and the selectively permeable membranes 1, 8a, l 8b
, 18c, the heat is transferred to each mixed liquid F int in the first firebox 11a, 11'b on the first and second mixed liquid supply side.
, Fins, and the mixed liquid Find.

Fint will be effectively heated.

Therefore, according to the liquid separation apparatus using the pervaporation method having the configuration of the present embodiment, first, the feed tank FT is connected to the first mixed liquid supply port 4a via the feed pump FP.
A mixed liquid (feed) of water (Hlo) and alcohol (ethyl alcohol: C!H60H) is continuously supplied and introduced into the first firebox 11a on the first mixed liquid supply side. The first mixed liquid flows slowly from the upper side to the lower side within the first firebox 11a on the supply side within a predetermined time depending on the speed (see FIG. 1).

On the other hand, in this state, the operation of the vacuum pump (not shown) causes the first and second separated liquid extraction side second fire chambers 13a to
, 13b side, air is sucked and led out so that it is almost vacuum and humidity-free, and the air is drawn out to the first and second selectively permeable membranes 1.
A pressure difference (partial pressure difference) of a predetermined value or more is realized between the selective molecule adsorption surface on the primary chamber side and the selective molecule desorption surface on the secondary chamber side of each of 8a, l 8b, and 18c. . As described above, the selectively permeable membrane 18a in this embodiment
, 18b and 18c are both intended water (i-ito)
It is formed of a water-selective permeable amorphous polymer membrane made of, for example, [α-fluoroacrylic acid copolymer] that selectively permeates only the components (see, for example, Japanese Patent Application No. 62-35401). Water components corresponding to their selection characteristics (
830 molecules), the temperature of the mixed liquid Fin, Fi, the temperature of the mixed liquid itself, the 11th second mixed liquid supply side (high pressure side), the first firebox 11a, 11b side, and the 11th second separated liquid take-out side ( (low pressure side) second firebox 13a, 13b side
) from the primary chambers 11a, 11b on the mixed liquid supply side (high pressure side) to the second fireboxes 13a, 13b on the second separated liquid extraction side (low pressure side). Transmit.

In this case, the permeation of the water components (H, O) is caused by the water molecules H2O in the mixed liquid flowing in the first firebox 11a, 11b on the first and second mixed liquid supply sides from the high pressure side to the low pressure side. First, the selective permeable membrane 1
It is adsorbed on the surfaces of 8a, l 8b, and 18c. and,
Thereafter, the water molecules H10 are dissolved and diffused into the permeable membranes 18a, 18b, and 18C due to molecular movement accompanying the dissolution action.

The amount of dissolution and diffusion of water molecules H30 at this time depends on the temperature of the liquid mixture and the partial pressure difference between the interfaces of the permeable membranes 18a, 18b, and 18c (if the concentration is the same, the material molecules have a higher pressure). move from the lower side to the lower side).

Also, the concentration difference between the selected molecules H, 0 (if the pressures are equal, the substance molecules move from the higher concentration side to the lower concentration side...4th
(see figure). In this case, the partial pressure difference can be relatively easily controlled to an ideal value by keeping the supply pressure by the mixed liquid supply side feed pump FP constant and by keeping the reduced pressure value by the vacuum pump, which is the pressure reducing means, constant. can do.

However, on the other hand, the temperature of the liquid mixture itself on the side of the high-pressure primary chamber and the concentration difference of the selected component (HtO molecules) cannot be easily maintained at desired values due to the following reasons. That is, first, as described above, the permeation effect in the selectively permeable membrane 18a is a pervaporation effect, which naturally accompanies a phase change (liquid phase → gas phase) of the water components H and O, which are selective molecules. . Therefore, as the separation action progresses, the amount of latent heat of vaporization also increases, and the temperature of the mixed liquid side decreases. This situation is exactly the same on the second high-pressure side primary chamber itb side.

However, as mentioned earlier, each of the selectively permeable membranes 18
As is clear from the alcohol concentration characteristics in FIG. 3, the permeation rate of water molecules passing through a and 18b is higher when the temperature of the mixed liquid is higher (under ideal conditions), and the permeation performance is excellent. Therefore, in the configuration of this embodiment, the selectively permeable membranes 18a and 18b are connected to the porous metal sintered body 9.
The system is configured to indirectly heat the liquid mixture by hot water circulation vibrators 17a, 17b, and 17c via lO, thereby reducing the temperature of the mixed liquid due to the latent heat of vaporization, and in particular, reducing the permeation rate of water molecules HtO. (maintaining the ideal temperature conditions shown in Figure 3).

Note that in the configurations shown in FIGS. 1 and 2 above, a hot water circulation pipe is used as a heating means for the selectively permeable membrane and the mixed liquid, but the heating means may also be an electric heater, for example. Needless to say.

When an electric heater is employed as a heating means, it has high thermal efficiency and easy temperature control, making it possible to provide a liquid separation device with even better separation performance.

Further, in each of the eleventh and second embodiments, water (ttto) is used as the separated liquid, but it goes without saying that the object of liquid separation of the present invention is not limited to this.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the module configuration of a liquid separation device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the device, and FIG. A graph showing the change characteristics of permeation efficiency using alcohol concentration concentration (dehydrated concentration) and supply flow rate as parameters,
FIG. 4 is a graph showing the relationship between the concentration difference of water molecule components between the permeable membrane interfaces and the amount of water component permeation. la...First frame lb...Second frame 1c...Third frame 1d...Fourth frame le...Fifth frame tr...・Sixth frame 3 ...Feed pipe 4a ...First mixed liquid supply port 4b ...Second mixed liquid supply port 5a ...First concentrated liquid discharge Outlet 5b...Second concentrated liquid outlet 9, to, 12...Metal sintered body 11a...First mixed liquid supply side primary chamber 11b
...Second mixed liquid supply side primary chamber 13a...
...First separated liquid extraction side primary chamber 13b ...Second separated liquid extraction side primary chamber 17a, 17b, 17c.
・Hot water circulation pipe 18a...First selectively permeable membrane tab...Second selectively permeable membrane 18c...Third selectively permeable membrane 313Figure 1M4 figure

Claims (1)

[Claims] 1. Primary chambers (11a) and (11b) on the mixed liquid supply side to which predetermined mixed liquids (Fin_1) and (Fin_2) containing the liquid to be separated and other liquids are supplied; , selectively permeable membranes (18a), (18b), (18c) for pervaporation for the mixed liquid supply side primary chambers (11a), (11b).
Separated liquid extraction side secondary chamber (13a), (1
3b) is provided between the mixed liquid supply side primary chambers (11a), (11b) and the separated liquid extraction side secondary chambers (13a), (13b) by a predetermined pressure difference forming means. In a liquid separation device that separates a target liquid by forming a predetermined pressure difference necessary for pervaporation separation action through selectively permeable membranes (18a), (18b), and (18c), The selectively permeable membranes (18a) and (18b)
), (18c) are provided with supporting plates (9), (10), (12) for reinforcing and supporting the selectively permeable membranes (18a), (18b), (18c) on the side surfaces of the secondary chambers. The support plates (9), (10), and (12) are formed of porous metal sintered bodies, and heating means (17a) are provided inside the metal sintered bodies.
A liquid separation device characterized in that (17b) and (17c) are provided. 2. The liquid separation device according to claim 1, wherein the heating means is a hot water circulation pipe. 3. The liquid separation device according to claim 1, wherein the heating means is an electric heater.