JPS58180204A - Separation using osmotic evaporation membrane - Google Patents

Abstract

PURPOSE:To obtain high sepn. capacity with a low degree of evacuation in a separating method using an osmotic evaporation membrane by performing sucking operation while passing a gaseous carrier to the evaporation side of the osmotic evaporation membrane. CONSTITUTION:The raw liquid mixture to be separated is supplied through an inlet 9 into a high pressure chamber 7 in a device and, if necessary, steam is supplied through a steam inlet 14 into a jacket 13 for heating to maintain the raw liquid mixture at a prescribed temp. A valve 12 is throttled and a valve 11 is opened then a vacuum pump 16 is operated to evacuate the inside of a vacuum chamber 8 and to force the specified component in the raw liquid to permeate through tubes 2, whereby the vapor having much specific component is obtained. The vapor is sucked with a pump 17, is condensed with a condenser 18 and is recovered in a tank 19. The uncondensed gas is heated with a heater 20, and is blown as a gaseous carrier through the valve 12 into the chamber 8. According to this method, the 3-times higher sepn. capacity of the membrane is obtained even under about 100 Torr reduced pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a separation method using a permeation evaporation membrane,
More specifically, the present invention relates to improvements in increasing the liquid separation ability and yield by permeation evaporation membranes.

Conventionally, distillation has been widely used to separate components in a solution, taking advantage of the differences in boiling point and volatility of each component.
In a mixture of different types, such as a mixed system of alcohol and water, an azeotrope may be formed when the vapor and liquid have the same composition, and in this case, ordinary distillation can separate the components. There is a problem that separation is difficult and requires complicated operations such as azeotropic distillation and extractive distillation.

Recently, pervaporation techniques have been used to separate components in solutions.

This pervaporation method supplies the solution to be separated to one side of the membrane material, and by applying a pressure difference on both sides of the membrane material, vapor richer in a specific component than the original solution permeates through the membrane material. This is to evaporate from the other side of the membrane material, and the membrane material conventionally used here is a membrane of sulfur, nylon, Nafyon, or the like.

In this conventional permeation evaporation method, the desired separation capacity cannot be obtained unless the evaporation side of the membrane is brought to a fairly high vacuum of, for example, 1 torr, which requires high vacuum equipment, equipment costs, and operational costs. It is still unsuitable for industrial implementation due to its rather high cost and the fact that its separation capacity is still at a relatively small level.

The present inventors have discovered that when a suction operation is performed while passing a carrier gas through the evaporation side of the above-mentioned permeation evaporation membrane, a high separation capacity can be obtained at a significantly lower degree of vacuum than in conventional methods. .

That is, according to the present invention, the mixed stock solution to be separated is passed through one side of the permeation-evaporation membrane under a reduced pressure, and the other side is sucked under reduced pressure while directly under reduced pressure or with a gas flowing through the membrane. A separation method using a permeation evaporation membrane is provided, which is characterized in that the vapor is separated into a vapor richer in a specific component than the undiluted solution and a residual liquid richer in other components than the undiluted solution.

The invention will be described in detail below with reference to the accompanying drawings.

The first diagram showing the arrangement of devices suitably used for carrying out the present invention.
In the figure, inside a cylindrical main body shell 1, a large number of pervaporation membrane tubes 2 are installed and a pair of tube support tube plates! ,5
is kept airtight by. Flanges 4, 4 are provided at both open ends of the shell 1, and these 7 langes 4
The end plates 5 each having a pipe 6 are fastened to each other by bolts or the like, and the whole becomes a pressure-resistant structure container.

In the device shown in this specific example, the outer space 7 of the pervaporation membrane tube 2 serves as a high-pressure side chamber through which the mixed stock solution to be separated passes, while the inner tube space 8 serves as a reduced-pressure side chamber from which vapor is extracted. . In this connection, the side wall of the shell 1 is provided with a liquid inlet 9 and a liquid outlet 10, and a lower mirror plate 5
The vibro is provided with a gas outlet valve 11, and the vibro on the upper mirror plate 5 is provided with a gas population valve 12, respectively.

Further, a heating jacket 13 is provided on the outside of the shell 1 in order to heat the mixed stock solution to be separated, and a steam port 14 and a drain outlet 15 are provided in this.

The gas outlet robalp 11 has a pipe 16 for taking out the gas bow 1.
A vacuum pump 17, a condenser or cooling tank 18, and a condensate tank 19 are connected in this order.

A heater 20 is connected to the exhaust side of the condensate tank 19, and the exhaust gas that has passed through the heater 20 reaches the gas population valve 12 via a pipe 21.

It should be noted that the permeation evaporation membrane constituting the tube 2 has various characteristics. Now, the weight fraction of the specific component in the stock solution (
If the relationship between the two is plotted with J) as the horizontal axis and the weight fraction (y) of the above components in the permeating vapor as the vertical axis, this plot will be a convex curve above the straight line of y = x. In some cases, it becomes a concave curve below this straight line.

Inventor! 1$ is an organopolysiloxane elastomer membrane in a mixed system of water and a water-miscible organic solvent.
It is a membrane that exhibits a permeation-evaporation curve that is convex on the upper side, while a polyphenylene oxide membrane and a cellulose acetate membrane are membranes that exhibit a permeation-evaporation curve that is concave on the lower side.

It has been found that when the former membrane is used, a vapor enriched in extra-solvent compared to the undiluted solution is recovered, whereas when the latter membrane is used, a liquid fraction enriched in extra-solvent compared to the undiluted solution is recovered. ing.

The tJg2 diagram shows the alcohol weight fraction CX of the original solution for aqueous solutions of various alcohols, methanol (・), ethanol (○), and isopropanol (mu).
The results of permeation and evaporation separation are shown with the t-horizontal axis and the alcohol weight fraction (y) in the vapor as the vertical axis. In the figure, the symbol SR indicates the organopolysiloxane membrane, and the symbol PPO indicates the polyphenylene membrane. The symbol CA indicates an oxide membrane, and the symbol CA indicates a cellulose acetate membrane.

Returning to FIG. 1 again, when carrying out the method of the present invention, the mixed stock solution to be separated from the liquid inlet 9 is transferred to the high pressure chamber 7 in the device.
If necessary, steam is supplied from the steam inlet 14 into the heating jacket 16 to maintain the mixed stock solution at a predetermined temperature.

Next, the gas inlet valve 12t-throttle (preferably 12 is a pressure reducing valve) is opened, the gas outlet valve 11 is opened, the vacuum pump 16 is operated, and the reduced pressure 1i18 of the permeation evaporation membrane tube 2 is kept under a constant reduced pressure. maintain. This results in
Certain components in the raw material solution seep through the tube 2 from the solution side to the vacuum chamber side, and J! from the surface. Takashi and pressure! 8 is filled with steam richer in specific components than the Fi mixed stock solution.

This vapor is drawn into the vacuum pump 17 through the gas outlet 11 and the pipe 16. The exhaust side of the vacuum pump 17 is at near atmospheric pressure, and this exhaust gas is sent to the condenser 1.
8, the vapor in the exhaust gas is collected in liquid form in a condensate tank 19. The uncondensed gas is heated by the heater 20 and passed through the pipe 21 and the throttled gas inlet valve 12 to the reduced pressure m8 in the pervaporation membrane tube 2 as a carrier gas.
is blown into.

According to the present invention, by passing a carrier gas to the vacuum chamber side of the pervaporation membrane where the vapor fluorifies, very significant advantages are achieved as shown in the examples below. That is, in the conventional permeation evaporation method, an extremely high vacuum of about 1 Torr (1 ml') is required in order to obtain a certain level of membrane separation ability.
It is inevitable that the cost of the equipment and the operating cost will increase.

On the other hand, according to the present invention, even when the degree of vacuum in the vacuum chamber is reduced to a low level such as 100 torr by a simple operation of passing a carrier gas through the vacuum chamber of the permeation evaporation membrane, For example, a membrane separation capacity of up to three times can be obtained, and it is clear that the present invention achieves significant advantages in terms of membrane separation capacity, equipment cost, and operating cost. .

Furthermore, according to a preferred embodiment of the present invention, the sucked gas is cooled to condense and recover the vapor of a specific component in the gas, and the uncondensed gas is injected into the evaporation side of the permeation evaporation membrane as a carrier gas. Circulating soybeans makes it possible to perform all separation operations in a closed system (closed toner kit), achieving remarkable advantages in terms of separation recovery rate and prevention of warrants, and all operations run smoothly. It becomes possible to do so.

During operation of the apparatus shown in Figure 1, the vapor in the decompression chamber 8 is rich in specific components, and as a converse result, the liquid remaining in the high pressure [7] has a dilute concentration of specific components. This residual liquid is taken out from the liquid outlet 10 continuously or intermittently to the outside of the apparatus. Correspondingly, the mixed stock solution to be separated is continuously or intermittently supplied into the high pressure chamber 7 from the liquid inlet 9. In this specification, high pressure [7 is referred to as reduced pressure ii! It should be understood that the mixed raw liquid pressure supplied into the high pressure chamber 7 is the liquid supply pump pressure. The liquid is also taken out of the system continuously or intermittently.

In one preferred embodiment of the present invention, in the permeation evaporation membrane 11 plotting the weight fraction (-) of the mixed stock solution versus the weight fraction (y) of the vapor, the permeation evaporation film 11 exhibits a convex curve or a concave m-. A plurality of units having permeation evaporation membranes exhibiting the same kind of permeation tendency are connected in series, and the vapor condensate or residual concentrate recovered from the first stage unit is transferred to the first stage unit. It is supplied as a liquid to the high pressure chambers of the second and subsequent units, and permeation and evaporation operations are performed.

In Fig. 6 showing the arrangement of the apparatus used in this embodiment, in order to avoid tedious explanation, parts common to those of the apparatus in Fig. 1 are indicated by common reference numerals, and The members are marked with a - suffix, and the members of the second stage unit are marked with a suffix.

In each of these units, when the permeation evaporation membrane tube 2a used in the first stage unit is made of a membrane showing an upwardly convex permeation evaporation curve in FIG. 2, for example, an organopolysiloxane membrane, the second stage unit The permeation evaporation membrane tube 2h used in the unit is also made of the same or similar type of membrane.

In the apparatus shown in FIG. 5, the configuration and operation of each w knit are as follows:
It is similar to that shown in FIG. 1, but the concentration is such that the condensate collected in the condensate tank 19a of the first stage unit is supplied to the liquid inlet 9k of the second unit through the piping 26 by the liquid supply pump 22. is different from that in Figure 1.

That is, in FIG. 3, the vapor condensate collected in the condensate tank 19g has specific components concentrated compared to the mixed stock solution supplied to the high pressure chamber 7gK of the first stage unit. is supplied to the high pressure 874 of the second stage unit, and the permeation evaporation operation is also performed in the second stage unit, thereby producing a chain condensate in which the constant components in the condensate tank 19hK% of the second stage unit are concentrated to a higher concentration. It becomes possible to collect.

According to this aspect of the invention, significant advantages are achieved not only in terms of high concentration, but also in terms of membrane separation capacity. For example, as shown in FIG. 2, when sRH is used in a water-alcohol mixed system, the vapor concentrate becomes one in which the alcohol content is concentrated. - On the other hand, referring to Figure 4, which shows the relationship between the alcohol weight fraction (-) in the mixed stock solution, the unit membrane area of steam, and the yield per unit time Q (1/m" AT), it is found that It can be seen that the vapor yield increases monotonically as the alcohol weight fraction (x) increases.Thus, according to the embodiment shown in FIG. It will be appreciated that significant advantages can also be achieved.

Furthermore, an advantage of the pervaporation method is that even when liquid components are combined to form an azeotrope, a concentrate containing a certain component at a concentration higher than the azeotropic point concentration can be obtained. For example, in an isopropanol water system, the negative degree of water is 28.5-1, that is, the concentration of isopropanol is 71.
．． 71i, but according to the present invention, as shown in FIG. In an isopropanol-water system with a lower concentration, a vapor with a higher alcohol concentration than the azeotrope concentration is recovered in a two-stage pervaporation operation. will be collected.

As shown in Figure 2, the components to be recovered are K in the residual liquid.
In the case of a P2O membrane or a CI membrane that is to be condensed, the residual concentrated liquid discharged from the liquid outlet 1041 of the first unit may be supplied to the liquid inlet 9k of the second unit to perform the permeation JIJ1 operation.

According to still another aspect of the present invention, one of the permeation evaporation films exhibiting a convex curve or a concave curve in the permeation evaporation line plotting the weight fraction of the mixed stock solution versus the weight fraction of the vapor. The first unit equipped with a permeation evaporation membrane exhibiting a permeation evaporation curve is used to carry out the first stage permeation M operation, and the residual liquid after nuclear separation is transferred to a permeation 111 membrane having an opposite permeation H rate tendency. The residual liquid of the second unit is circulated to the high pressure chamber of the first unit for permeation and evaporation.

In Fig. 5 showing this uniformity, the structure and operation of the first unit and the second unit are the same as those in Fig. 3,
The member of the S-th knit is given the same reference numeral and the subscript C as each member of the S-th and second units.

For example, the permeation evaporation film tube 2C of the third unit has a permeation evaporation tendency opposite to that of the permeation evaporation film '1m and 2b of the first and second units. is an SR membrane, while the permeation evaporation membrane 2c of the third unit is a PPO membrane or a CA membrane, so a combination of both membranes is selected.

In FIG. 5, the liquid outlet 10α of the first unit is connected to the liquid inlet 9c of the third unit through a pipe 24, and the liquid outlet 10A of the third unit is connected to the liquid inlet 9c of the third unit through a pipe 25. Further, the liquid outlet 10C of the third unit is connected to the liquid inlet 94 of the first unit via the pipe 26. Of course, these pipings 24, 25 and 26 can be attached with mechanisms necessary for liquid supply, such as a liquid supply pump, a valve, a flow rate regulating valve, a pressure controller, or a liquid storage tank, although not shown.

In the first and third units, the specific components to be recovered are concentrated in the vapor condensate, while the components are diluted in the residual liquid remaining in the high pressure chambers 7α and 7h after the evaporation operation. There is. The residual liquid in which the specific component is diluted is transferred from the liquid outlet 10α of the first unit to the pipe 2.
4, and from the liquid outlet 10b of the third unit to the pipe 2.
5, and is sent from the liquid inlet 9C of the 13th unit to the high pressure W17C of the 3rd unit.

Contrary to the permeation evaporation membranes 2α and 2b of the first and second units, the permeation evaporation membrane 2C of the third unit concentrates specific components in the stock solution into the residual liquid, and other components in the stock solution are concentrated. It exhibits permeation-evaporation properties as if it were absorbed into steam. As a result, the residual liquid from the high pressure chamber 7C of the third unit has a specific component concentrated to a higher concentration, and this concentrated liquid is passed through the liquid outlet 10C1 piping 26 to the liquid inlet 9 of the first unit.
By circulating to α, specific components can be separated and recovered more efficiently. Note that liquid in which other components are highly condensed is collected in the condensate tank 19C of the third unit. ＼ The perivaporization separation method of the present invention can be used to separate an organic liquid and water from a solution containing water and a solid organic liquid, and can also be used to separate an organic liquid from a solution containing multiple types of organic liquids. It can be advantageously used to separate these components.

In addition, when supplying the mixed stock solution continuously into the pervaporation device, instead of supplying the carrier gas from a separate source, the supplied mixed stock solution is saturated with air or a threatening gas.
This saturated gas can also be used as a carrier gas.

The invention is illustrated by the following example.

In this example, snow was used in the apparatus shown in Fig. 1 with a shell diameter of 100 m and the number of permeation evaporation membranes approximately 630 pieces/-. Separation ability was measured.

The operating conditions and results are shown below.

The membrane separation ability is expressed by the unit membrane area of the permeation evaporation membrane and the yield of worms per unit time (I/A).

(1) Vacuum degree 100) - Gas flow rate in the tank 5QNL/wx Heating gas temperature 50℃ Cooling gas temperature 25℃ Separated liquid - degree Ethanol 48 - Water
51- Membrane separation capacity 909/ga・hr (2) Vacuum degree 1 torr Carrier gas None Temperature 25°C Membrane separation ability 28I/ga・hr From the results above, it is better to apply heat rather than simply suctioning to a vacuum degree of 1 torr. It has been shown that the separation capacity is approximately three times higher even when a vacuum level of 100 Torr is applied while passing a warm carrier gas.

Example 2 Example 1 except that the device shown in FIG. 5 is used! I! The permeation evaporation operation was carried out in the same manner as in Example 1, the concentration of the separated liquid was measured, and the membrane separation ability was evaluated.

The operating conditions and results are shown below.

(1) Degree of vacuum: 100 Torr Carrier gas flow rate: 5 Q ML/Shoulder heating Heating gas temperature: 50°C Gas cooling temperature: 25°C Separated liquid concentration From the above results, by performing permeation-evaporation operations in series in multiple stages, membrane separation capacity can be improved. Significant advantages are achieved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the arrangement of an apparatus suitably used in carrying out the present invention, and FIG. 2 is a diagram showing the results of permeation-evaporation separation by the method of the present invention. FIG. 6 is a diagram showing another embodiment of the apparatus suitably used in carrying out the present invention. FIG. 4 is a diagram showing the alcohol weight fraction (-) and vapor when added to permeation evaporation separation by the method of the present invention. Figure 5 is a diagram showing the relationship between the nest position membrane area and the yield Q of insects per unit time. The reference numbers are: 1 is the main body shell, 2 is the permeable M membrane tube, 6 is the permeable evaporative membrane tube support tube plate, 4 is the 7 cylinder, 5 is the end plate, 6 is the gas inlet vibrator, 7 is the liquid high pressure side house, 8 is the inside of the permeation evaporation membrane tube, 9 is the liquid inlet, 10 is the liquid outlet, 11 is the gas outlet Roharp, 12 is the gas inlet valve,
13 is the shell, 14 is the steam inlet, 15 is the drain outlet, 16 is the gas outlet vibe, 17 is the vacuum pump, 18 is the condenser, 19#'i condensate tank, 20 is the heater, 1g, 1.6 is the main body shell, 2a, 2 are permeable evaporative membrane tubes, sa, sbu permeable evaporative membrane tube support tube plates,
7m, 7 is the liquid high pressure chamber side, f3g, 8h is the inside of the permeation evaporation membrane tube, 9m, 9 is the liquid inlet, 1041.1 (l is the liquid outlet, 111.11b is the gas outlet valve, 12a, 1
27 is a gas inlet valve, 16g, 16h is a gas outlet vibe, 17α, 17h is a vacuum pump, 18α, 18AU condenser, 19@, 19 roaring condensate tank, 208.
20h is a heater, 211! , 21 is a circulating gas pipe,
22 is a pump, 26 is a pipe, 1a, 1, 1c is a main body shell, 2a, 2, 2c is a permeation evaporation membrane tube, 7g
, 7, 7c is the liquid high pressure chamber side, 8α. f3h, f3c are inside the permeation evaporation membrane tube, 9g, 9A
, qcld liquid inlet, 10a, 11, 10C liquid outlet, 11
G, 11 b, 11 eB gas output Robulp, 1?
, 12A, 1? is a gas inlet valve, 16a. 16h, 16C are gas outlet vibes, 17tl, 17k. 17C is a vacuum pump, 18a, 18b, 18c are condensers, 19g, 19h, 1? Fi condensate tank, 20
a, 20As20C is a heater, 21a, 21.2IC
is a circulating gas pipe, 22 is a pump, 2M, 24.25.
26 indicates a pipe. Sae 11 Su 2 figure - Methanol I Shi 1 qb

Claims (6)

[Claims] (1) The mixed stock solution to be separated is passed through one side of the permeation-evaporation membrane under high pressure, and the pressure is directly reduced on the other side, or the mixture is suctioned to a reduced pressure while flowing a carrier gas, and the mixture permeates through the membrane and evaporates. A separation method using a permeation evaporation membrane, characterized in that the vapor is separated into a vapor richer in a specific component than the stock solution and a residual solution richer in other components than the stock solution. (2) The Wk subtracted gas is cooled to condense and recover the vapor of a specific component in the gas, and the uncondensed gas is left as it is or after being heated, and is added to the evaporation side of the permeation evaporation film. The separation method according to claim 1, characterized in that the gas is circulated as Yarya gas. (3) Among the pervaporation films that show a convex curve or a concave curve on the pervaporation line plotting the weight fraction of the mixed stock solution versus the weight fraction of the vapor, the pervaporation film that shows the same type of permeation generation tendency is selected. using a plurality of units equipped with a plurality of values connected in series, supplying the vapor condensate or residual concentrate recovered from the first stage unit as a liquid to the pressure chamber of the second stage and subsequent units, The method according to claim 1, which is carried out in a pervaporation operation facility. (4) Among the permeable evaporative membranes that show a convex curve or a concave curve in the permeable evaporation operation in which the weight fraction of the mixed stock solution versus the weight fraction of the vapor is plotted, the permeable evaporative membrane exhibits one of the permeable evaporative membranes that exhibits a permeable nuclear tendency. The first unit is used to perform a one-stage permeation evaporation operation, and the residual liquid after evaporation separation is supplied to the high-pressure chamber of the second unit equipped with a permeation evaporation membrane that exhibits the opposite tendency to permeation. Claim 1: Performing an evaporation operation and circulating the residual liquid in the second unit to the high-pressure vehicle side of the first unit.
The method according to paragraph 111. (5) The method according to claim 1, wherein the permeation evaporation membrane used is an organopolysiloxane elastomer membrane. (6) The method according to claim 1, wherein the permeation evaporation membrane used is a polyphenylene oxide membrane or a cellulose acetate membrane.