JP2005066473A - Membrane separation method, membrane separation apparatus and membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane separation method in which a vapor-liquid fluid mixture can be controlled easily and problems such as concentration polarization and temperature drop can be solved, and to provide a membrane separation apparatus and a membrane module. <P>SOLUTION: A liquid mixture 1a is made to be the vapor-liquid fluid mixture 1d having a vapor phase the temperature of which is higher than that of a liquid phase. the vapor-liquid fluid mixture 1d is supplied to the primary side of a separation membrane 31 and the pressure of the secondary side is made negative so that an impure component in the liquid mixture 1a can be permeated into the secondary side of the separation membrane 31. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a membrane separation method, a membrane separation apparatus, and a membrane module for separating contaminant components from a liquid mixture, and more specifically, for example, by purifying ethanol by separating and removing water as a contaminant component from a water-ethanol mixture. The present invention relates to a membrane separation method, a membrane separation apparatus, and a membrane module that can perform the above.

  A membrane separation method using pervaporation is known as a method for separating contaminant components from a liquid mixture (see, for example, Patent Document 1). This membrane separation method is a liquid mixture that has conventionally been difficult to separate by a simple method, such as an azeotropic mixture, a mixture having a boiling point close to a low relative volatility, a mixture containing components that cause polymerization or modification by heating, etc. It is attracting attention as a separation method, concentration method, and purification method.

  Conventionally, when separating a liquid mixture by pervaporation, the characteristics of the separation membrane used, especially when the separation membrane used is a polymer membrane made of polyimide, etc., prevents membrane adhesion or membrane breakage in the membrane module From this viewpoint, the mixture is constituted by a single-phase flow consisting only of a liquid phase or a vapor phase (gas phase). In particular, permeation vaporization involves a phase change from the liquid phase to the gas phase when passing through the membrane, so that the latent heat of vaporization is replenished from the supply liquid. As a result, the temperature of the feed liquid was lowered, and the permeation flux (membrane separation ability) was lowered. From the viewpoint of avoiding a decrease in the permeation flux resulting from this temperature decrease, in the conventional pervaporation process, an intermediate heat exchanger for heating the supply liquid is provided at the entrance and exit of each membrane module, thereby improving the membrane performance. .

  In recent years, in addition to high separation membranes, inorganic membranes such as zeolite membranes have been put into practical use as a separation membrane, and even though problems such as membrane adhesion in membrane modules have been resolved, A single-phase flow was used, and the membrane performance could not be fully exhibited.

  When the separation membrane is a polymer membrane, since the permeation flux is relatively low, the difference in the supply liquid temperature at the inlet / outlet of the membrane module and the concentration polarization on the membrane surface did not become a big problem. However, in the case of a zeolite membrane having a permeation flux higher by one order or more than that of a polymer membrane, it is necessary to consider not only the difference in the supply liquid temperature at the entrance and exit of the membrane module but also the concentration polarization.

  In Japanese Patent Application Laid-Open No. 11-156167, the liquid mixture is pressurized to a pressure slightly lower than the saturated vapor pressure at a predetermined temperature with respect to the concentration polarization on the film surface, and then heated to the predetermined temperature to thereby form the gas phase and the liquid phase. A gas-liquid mixed fluid that is in a two-phase flow state is generated, and this gas-liquid mixed fluid is dealt with by the stirring action of the gas (bubbles), but no consideration is given to a decrease in the supply liquid temperature. In addition, in the method for generating a gas-liquid mixed fluid by adjusting the pressure, it is not always clear from where in the membrane module the two-phase flow state is configured, and further, the heat of the latent heat of evaporation is deprived. As a result, the gas phase may be condensed into a liquid phase and returned to a single-phase flow, so that it is difficult to control the gas-liquid mixing state, leaving room for improvement.

U.S. Pat. No. 2,953,502 JP-A-11-156167

  The present invention has been made in view of the above circumstances, and the problem is that the gas-liquid mixed fluid can be easily controlled, and the membrane separation method and the membrane separation apparatus that can solve the problems such as concentration polarization and temperature decrease. And providing a membrane module.

  In order to solve the above-mentioned problem, the membrane separation method according to the first aspect of the present invention is characterized in that a liquid mixture is a gas-liquid mixed fluid containing a gas phase having a temperature higher than the liquid phase, and the gas-liquid mixed fluid is used as a separation membrane. The contaminant component in the liquid mixture is allowed to permeate the secondary side of the separation membrane by making the secondary side negative pressure on the secondary side.

  According to this feature, since the liquid mixture is present on the primary side of the separation membrane in the state of a gas-liquid mixed fluid, concentration polarization on the separation membrane can be eliminated by the stirring action of gas (bubbles). Further, since the temperature of the gas phase is higher than the temperature of the liquid phase, it is possible to replenish latent heat of vaporization when contaminant components (for example, moisture) permeate from the primary side to the secondary side of the separation membrane, and the temperature of the liquid mixture Decreasing can be avoided. Therefore, it is possible to maintain the gas-liquid mixed state in the process of being in contact with the separation membrane, and to avoid the separation capability of the separation membrane from being lowered due to the temperature drop.

  Further, the invention of the membrane separation apparatus according to the second aspect of the present invention includes a vapor generator that converts a part of the liquid mixture into a gas phase having a temperature higher than the liquid phase, and a gas-liquid mixed liquid containing the gas phase. And a membrane module having a separation membrane for separating contaminant components in the mixture.

  According to this feature, a steam generator is provided, and by introducing the steam generated by the steam generator, the liquid mixture can be easily brought into a gas-liquid mixed state, so that control thereof is possible. Easy.

  Moreover, since the liquid mixture in a gas-liquid mixed state including the gas phase can be processed by the membrane module, concentration polarization on the separation membrane can be eliminated by the stirring action of the gas (bubbles). Further, since the temperature of the gas phase is higher than the temperature of the liquid phase, it is possible to supplement the latent heat of vaporization when separating impurities (for example, moisture), and to avoid the temperature of the liquid mixture from being lowered. Therefore, it is possible to maintain the gas-liquid mixed state in the process of being in contact with the separation membrane, and to avoid the separation capability of the separation membrane from being lowered due to the temperature drop.

  Further, the invention of the membrane separation apparatus according to the third aspect of the present invention is characterized in that, in the second aspect, the vapor generating device includes a heating device that heats the liquid mixture to form a vapor. And According to this feature, a part of the liquid mixture can be reliably brought into a vapor (gas phase) state with a simple configuration.

  Further, in the invention of the membrane separation apparatus according to the fourth aspect of the present invention, in the third aspect, the steam generator further includes a steam superheater that superheats the steam generated by the heating device. It is characterized by that. According to this feature, the temperature of the vapor (gas phase) generated by the heating device can be reliably made higher than the liquid phase.

  Further, the invention of the membrane module according to the fifth aspect of the present invention includes a heating means for boiling a part of the liquid mixture to bring it into a gas-liquid mixed state containing a gas phase having a temperature higher than the liquid phase, and the gas-liquid mixing And a separation membrane for separating contaminant components in the liquid mixture in a state.

  According to this feature, since the liquid mixture in a gas-liquid mixed state including the gas phase can be present on the separation membrane, concentration polarization on the separation membrane can be eliminated by the stirring action of gas (bubbles). Further, since the temperature of the gas phase is higher than the temperature of the liquid phase, it is possible to supplement the latent heat of vaporization when separating impurities (for example, moisture), and to avoid the temperature of the supply liquid from being lowered. Therefore, it is possible to maintain the gas-liquid mixed state in the process of being in contact with the separation membrane, and to avoid a reduction in the separation performance of the separation membrane due to a temperature drop.

  Moreover, the invention of the membrane module according to a sixth aspect of the present invention is characterized in that, in the fifth aspect, the heating means is disposed in the vicinity of the primary side surface of the separation membrane. According to this feature, heat can be supplied more directly in the vicinity where the latent heat of vaporization occurs, so that the latent heat of vaporization can be replenished more efficiently and reliably.

  According to the present invention, the liquid mixture can be easily controlled as a gas-liquid mixed state, and problems such as concentration polarization and temperature drop in membrane separation of the liquid mixture can be solved, and high-performance membrane separation can be achieved. Can be implemented.

  In the membrane separation method according to the present invention, the liquid mixture is a gas-liquid mixed fluid containing a gas phase having a temperature higher than the liquid phase, the gas-liquid mixed fluid is present on the primary side of the separation membrane, and the secondary side is set to a negative pressure. By doing so, the contaminant component contained in the liquid mixture is permeated to the secondary side of the separation membrane. That is, when the liquid mixture is present on the primary side of the separation membrane, the liquid mixture is a gas-liquid mixed fluid containing a gas phase having a temperature higher than that of the liquid phase.

  Hereinafter, a membrane separation method according to the present invention and a membrane separation apparatus suitable for carrying out the method will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a membrane separation apparatus 100 according to an embodiment of the present invention. The membrane separation device 100 includes a vapor generating device 15 that converts a part of the liquid mixture supplied from the liquid mixture tank 10 storing the liquid mixture 1a to a gas phase state at a temperature higher than the liquid phase, and the gas phase. The main component is the membrane module 14 that processes the gas-liquid mixed fluid 1d that has been in a gas-liquid mixed state to separate impurities (for example, moisture).

  Examples of the liquid mixture 1a to be separated by the membrane separation apparatus 100 include a liquid mixture of water and alcohols such as methanol, ethanol, propanol, and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, carbon tetrachloride, Liquid mixtures of organic liquids such as halogenated hydrocarbons such as trichlorethylene and alcohols such as methanol, etacol, propanol, isopropyl alcohol, liquid mixtures of the alcohols and aromatics such as benzene and cyclohexane, and Mention may be made of a mixture in which two or more of the liquid mixtures are mixed. Examples of the liquid mixture in which the membrane separation apparatus 100 according to the present invention exhibits particularly excellent selectivity include water-alcohol mixtures such as a water-ethanol mixture and a water-isopropyl alcohol mixture.

  The liquid mixture 1a fed from the liquid mixture tank 10 by the feed pump 11 is preheated by the regenerator 12, and then supplied to the heater 13 to be heated to a predetermined temperature. A part 1b of the heated liquid mixture 1a is introduced into a steam generator 15 to be described later to be in a gas phase state 1c having a temperature higher than that of the liquid phase, and the gas phase 1c is introduced into the liquid phase liquid mixture 1a. A liquid mixed fluid 1d is generated, and this gas-liquid mixed fluid 1d is supplied to the membrane module 14.

  The membrane module 14 is not particularly limited, but a known one having a separation membrane can be used. For example, a cylindrical membrane module disclosed in Japanese Patent Laid-Open No. 8-131781 or Japanese Patent Laid-Open No. It is possible to use a cylindrical membrane module inserted from both tube plates so that one end sealed cylindrical separation membrane fixed to the tube plate has a predetermined pitch as shown in Japanese Patent No. 1311782. The “membrane module” means a part or a unit of the apparatus, which includes a separation membrane and has a substance separation function.

  Further, the separation membrane incorporated in the membrane module 14 is not particularly limited, but for example, as shown in FIG. 3, the zeolite membrane 31a is formed on the outer surface of the cylindrical porous support base 31b. The interior can be maintained in a negative pressure state by a vacuum pump 18 (see FIG. 1). The type of the zeolite membrane 31a can be appropriately selected depending on the components to be separated, and is described in, for example, the A-type zeolite membrane described in JP-A-8-318141 and JP-A-8-257302. ZSM-5 type zeolite membrane, Y type zeolite membrane described in JP-A No. 8-257301, NaX type zeolite membrane described in JP-A No. 10-212117, described in JP-A No. 2000-42386 The T-type zeolite membrane etc. which have been mentioned can be mentioned. In particular, the separation membrane 31 in which the seed crystal is supported on the porous support base 31b and the zeolite membrane 31a is deposited is preferable.

  While the gas-liquid mixed fluid 1 d supplied to the membrane module 14 flows along the primary side of the separation membrane 31, impurities 2 a (for example, moisture) permeate the separation membrane 31 from the liquid mixture in the gas-liquid mixed state 1 d. The secondary component 2a reaches the secondary side and is condensed by the condenser 19 and collected in the permeate tank 20 as the permeate 2b.

  In this process, the gas-liquid mixed fluid 1d flowing along the surface on the primary side of the separation membrane 31 has a gas phase as bubbles, so the separation membrane primary side along the flow of the gas phase (bubbles). A stirring action is generated on the surface, and concentration polarization on the separation membrane can be eliminated. Furthermore, since the temperature of the gas phase is set higher than that of the liquid phase, it is possible to replenish latent heat of vaporization of contaminant components (for example, moisture), and it is possible to avoid a decrease in the temperature of the supply liquid. Therefore, while flowing along the primary side surface of the separation membrane 31, it is possible to reliably maintain the liquid mixture in a gas-liquid mixed state and to avoid a reduction in separation performance of the separation membrane due to a temperature drop. . As a result, high resolution can be expressed.

  The gas-liquid mixed fluid 1e separated and concentrated with the contaminated components is cooled by the regenerator 12 and collected in the product tank 17 as a highly concentrated solution.

  Next, the configuration of the steam generator 15 according to the present embodiment will be described with reference to the drawings. Here, FIG. 2 is a block diagram of the steam generator 15 usable in the membrane separation apparatus of the present invention.

The steam generator 15 includes a supply device 21 and a heating device 22 as main components.
The supply device 21 can be constituted by a liquid feed pump, for example, and pressurizes a part 1b of the liquid mixture so as to be higher than the saturated vapor pressure at a predetermined temperature.

  The heating device 22 supplies heat to the liquid mixture 1b to evaporate or boil it to a gas phase (vapor) state 1c. The heating device 22 is preferably provided with adjusting means (not shown) for adjusting the amount of gas phase (steam) generated by adjusting the amount of heat supplied.

  A steam superheater (superheater) 23 that supplies heat to the gas phase (steam) 1 c generated by the heating device 22 is preferably provided between the heating device 22 and the steam supply unit 29. By heating the gas phase (steam) 1c with the steam superheater 23, the temperature of the gas phase can be reliably adjusted to be higher than the temperature of the liquid phase.

  The temperature of the gas phase is not particularly limited as long as it is higher than the temperature of the liquid phase, and can be appropriately set depending on the type of the liquid mixture, the amount of the gas phase, the type of the separation membrane, the nature of the contaminant component, etc. The temperature is preferably about 0.1 to 20 ° C. higher than the liquid phase, more preferably about 1 to 10 ° C., and most preferably about 3 to 5 ° C. As described above, when the temperature of the gas phase is higher than the temperature of the liquid phase, the liquid mixture can be easily controlled as a gas-liquid mixed state, and the latent heat of evaporation derived from the separation of the contaminated components can be reliably replenished. it can.

  The gas phase (steam) 1c adjusted to a temperature higher than the liquid phase temperature is supplied from the vapor supply unit 29 to the liquid phase liquid mixture 1a to generate the gas-liquid mixed fluid 1d. The vapor supply unit 29 is preferably provided with adjusting means (not shown) that can adjust the size, abundance, degree of dispersion, and the like of the gas phase (bubbles) in the gas-liquid mixed fluid. By this adjusting means, the state of the gas-liquid mixed fluid 1d can be easily controlled. The gas phase preferably has a suitable size and abundance in the gas-liquid mixed fluid, and is preferably in a uniformly dispersed state.

  The abundance of the gas phase contained in the gas-liquid mixed fluid can be appropriately set depending on the type of the liquid mixture, the temperature of the gas phase, the type of the separation membrane, the nature of the contaminant component, etc. The volume ratio is about 1 to 100 times, preferably about 1 to 10 times, and most preferably about 3 times. The volume ratio of the gas phase contained in the gas-liquid mixed fluid can be selected from the range of 1 to 70% by volume, preferably 10 to 50% by volume. In particular, when the gas phase temperature is about 4 ° C. higher than the liquid phase, the amount of the gas phase is preferably about 30% by volume. Note that the volume ratio of the gas phase may vary depending on the pressure in the membrane module 14.

  When the liquid mixture is pressurized to a predetermined pressure by the supply device and then heated to be in a vapor state, the vapor superheater may be omitted. Moreover, when a steam superheater is provided to superheat steam, the supply device may be omitted.

  Next, FIG. 4 is a schematic configuration diagram of a membrane separation apparatus 101 according to another embodiment of the present invention. The same components as those in FIG. In the embodiment shown in FIG. 4, a gas g that does not react with the liquid mixture 1a from the outside (for example, an inert gas such as a rare gas or nitrogen gas) is used as a gas corresponding to the steam superheater 23 in the embodiment shown in FIG. After the superheater 23a is heated to a temperature higher than the liquid phase of the introduction destination, it is introduced into the liquid mixture 1a to constitute the gas-liquid mixed fluid 1d.

  The temperature of the gas g is not particularly limited as long as it is higher than the temperature of the liquid phase, and can be appropriately set depending on the type of liquid mixture, the amount of gas phase, the type of separation membrane, the nature of contaminant components, etc. The temperature is preferably about 0.1 to 50 ° C. higher than the liquid phase, and more preferably about 0.1 to 30 ° C. As described above, when the temperature of the gas g is higher than the temperature of the liquid phase, the liquid mixture can be easily controlled as a gas-liquid mixed state, and the latent heat of evaporation derived from the separation of contaminant components can be reliably replenished. it can.

  Also in this embodiment, the gas supply unit 29a that supplies the gas g to the liquid mixture 1a to generate the gas-liquid mixed fluid 1d includes the size, abundance of the gas phase (bubbles) in the gas-liquid mixed fluid, It is preferable to provide an adjusting means (not shown) capable of adjusting the degree of dispersion and the like. By this adjusting means, the state of the gas-liquid mixed fluid 1d can be easily controlled. The gas phase is preferably in a uniformly dispersed state so as to have a suitable size and abundance in the gas-liquid mixed fluid.

  The amount of gas g contained in the gas-liquid mixed fluid can be appropriately set according to the type of liquid mixture, the type of gas, the temperature of the gas, the type of separation membrane, the nature of the contaminating component, etc. The volume ratio is about 1 to 100 times, preferably about 1 to 10 times, and most preferably about 3 times. The volume ratio of the gas contained in the gas-liquid mixed fluid can be selected from the range of 1 to 80% by volume, preferably 10 to 50% by volume. The gas volume ratio may vary depending on the pressure in the membrane module 14.

  Next, a membrane module provided with heating means for boiling a part of the liquid mixture to bring it into a gas-liquid mixed state containing a gas phase having a temperature higher than the liquid phase will be described.

Here, FIG. 5 is a schematic cross-sectional view of the membrane module 141 provided with heating means.
As shown in FIG. 5, the membrane module 141 is composed mainly of a separation membrane 31, a flow path 40, a casing 48, a decompression unit 34, and a heat supply unit 50 as a heating means. For example, the membrane 31 (see FIG. 3) can be preferably used when water is separated from a water-ethanol mixture.

  The decompression section 34 covered with the decompression section shell cover 35 and the inside (secondary side) of the separation membrane 31 communicating with the decompression section 34 are kept in a decompressed state by a vacuum pump, thereby enabling material separation. . Further, a part of the liquid mixture is boiled by the heat supply unit 50, and further, heat is supplied to the gas phase generated by the boiling, so that a gas-liquid mixed fluid containing a gas phase having a temperature higher than the liquid phase is generated. When this gas-liquid mixed fluid passes through the flow path 40, it comes into contact with the primary side of the separation membrane 31, so that only contaminant components such as moisture selectively pass through the separation membrane 31 and become secondary. The contaminant component contained in the liquid mixture is removed by moving to the pressure side and being sent to the decompression unit 34 in a gaseous state.

  In this process, since the gas phase contained in the gas-liquid mixed fluid exists as bubbles, a stirring action occurs on the primary surface of the separation membrane 31 along the flow of the gas phase (bubbles) and Concentration polarization can be eliminated. Furthermore, since the temperature of the gas phase is set higher than that of the liquid phase, it is possible to replenish latent heat of vaporization of contaminant components (for example, moisture), and it is possible to avoid a decrease in the temperature of the supply liquid. Therefore, it is possible to avoid a reduction in separation performance of the separation membrane due to a temperature drop, and to express a high separation performance.

  The flow path 40 is configured such that the liquid mixture passes from the introduction part 41 toward the discharge part 42 while being in contact with the surface of the separation membrane 31. The separation membrane 31 is attached to the separation membrane circular tube plate 33 with a fastener 32.

  The heat supply unit 50 is disposed near the primary surface of the separation membrane 31. Then, the heat medium is filled so as to cover the outer tube, and heat is supplied to the liquid mixture passing through the flow path 40, and a part of the liquid is boiled, whereby steam (gas phase) having a temperature higher than the liquid phase is generated. It is comprised so that the gas-liquid mixed state containing can be produced | generated. In addition, it is preferable that the heat supply part 50 is the structure which can supply heat to a gaseous phase by directly contacting with the vapor | steam (gas phase) produced | generated by boiling. The heat medium is configured to flow from the medium introduction unit 52 toward the medium discharge unit 53, so that the heat supply amount can be accurately adjusted. The heat medium is not particularly limited, and examples thereof include steam and heat medium oil.

  Next, regarding the membrane module provided with the heating means, the configuration of the membrane module 142 different from FIG. 5 will be described with reference to FIG. Here, FIG. 6 is a schematic cross-sectional view of the membrane module 142 provided with heating means, and the same components as those in FIG.

  In the membrane module 142 shown in FIG. 6, the heat supply unit 50 as a heating unit is disposed so as to surround the casing 48, and a part of the heat supply unit 50 is supplied by supplying heat to the liquid mixture from the periphery of the casing 48. It is configured to generate a gas-liquid mixed state by boiling.

  Moreover, the flow path 40 can be provided with a turbulent flow promoting body 45 having a turbulent flow promoting effect so that the liquid mixture efficiently contacts the separation membrane 31. The heat supply unit can also be configured inside the casing 48. In this case, for example, the heat supply unit can be disposed along the inner peripheral surface of the casing 48 or can be disposed so as to surround the separation membrane 31.

  Although not shown, the liquid mixture in the membrane module is heated after heating a gas that does not react with the liquid mixture from the outside (for example, an inert gas such as a rare gas or nitrogen gas) to a temperature higher than the liquid phase in the gas superheater. The gas-liquid mixed fluid may be generated by introducing into the gas. In this case, the liquid mixture existing at least on the primary side of the separation membrane can be used as the gas-liquid mixed fluid, and the above-described effects can be obtained in the same manner. Specifically, for example, a gas diffusion tube or the like may be provided in the membrane module so that gas whose temperature is adjusted is supplied as bubbles to the primary side of the separation membrane.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1 and Comparative Examples 1-2
When a water-isopropyl alcohol (IPA) mixture containing 5 wt% of water is used as the liquid to be treated, the supply liquid flow rate is 10 L / h, and a NaA-type zeolite membrane is used as the separation membrane, steam at a temperature 5 ° C. higher than the liquid phase Example 1 according to the present invention in which the liquid to be treated in a gas-liquid mixed state by supplying (gas phase) was supplied to the separation membrane surface, and the liquid to be treated in a gas-liquid mixed state under reduced pressure on the surface of the separation membrane Membrane separation was performed for the supplied Comparative Example 1 and for Comparative Example 2 in which the liquid to be treated was supplied to the surface of the separation membrane in a liquid state under pressure. The implementation conditions and results are shown in Table 1.

  From Table 1, the permeate flow rate indicating the membrane separation performance is 70 g / h in Example 1 according to the present invention, 60 g / h in Comparative Example 1, and 32 g / h in Comparative Example 2, It can be seen that the separation effect is significant in the membrane separation method of the present invention. In addition, the permeate flow rate is improved compared to Comparative Example 1 in which the supply state of the supply liquid is the same gas-liquid mixed state. In Comparative Example 1, when a gas mixture of 50 vol% or less is contained in the liquid mixture in a state slightly lower than the saturated vapor pressure to form a gas-liquid mixed state, the gas-liquid mixed state is configured from the film supply inlet. This is presumed to be because the stirring action by the gas was inadequate because it was not possible. In Comparative Example 1, it is presumed that no gas-liquid mixed state is formed from the membrane supply inlet.

Examples 2-4 and Comparative Examples 3-4
Next, the supply liquid flow rate is set to 80 L / h, and the supply liquid is supplied to the separation membrane surface by supplying steam (gas phase) at a temperature 5 ° C. higher than the liquid phase to a gas-liquid mixed state. When the amount of steam contained (steam supply liquid flow rate) is changed stepwise to 0.5 L / h, 1 L / h, and 2 L / h (Examples 2 to 4), The membrane separation was performed when the treated liquid was supplied to the separation membrane surface (Comparative Example 3) and when the treated liquid was supplied to the separation membrane surface in a liquid state under pressure (Comparative Example 4). The implementation conditions and results are shown in Table 2.

  From Table 2, the permeate flow rate is 760 g / h in Example 2 where the steam feed liquid flow rate is 0.5 L / h, confirming a slight decrease in membrane performance compared to 816 g / h in Comparative Example 3. Yes, but better than Comparative Example 4. This is presumed to be because, in Example 2, the replenishment of latent heat of vaporization required when water permeates the membrane was insufficient and the concentration polarization was not sufficiently eliminated.

  More specifically, Comparative Example 3 is a boiling operation (reduced pressure boiling) with the outlet of the membrane module being in a reduced pressure state. There is little bubble generation at the inlet of the membrane module, and it boils violently as it flows toward the outlet of the membrane module. Bubbles are generated, and the flow becomes a gas-liquid mixed state. As a result, it is presumed that the concentration polarization in the vicinity of the inlet is not eliminated so much and the concentration polarization is eliminated to some extent by boiling toward the outlet. Thus, in Comparative Example 3, it is not clear from where in the membrane module the gas-liquid mixture state is configured, and control is difficult. The operating temperature in Comparative Example 3 is the liquid temperature at the inlet of the membrane module, and the operating pressure is the outlet of the membrane module when the temperature at the outlet of the membrane module is set to be lower by several degrees (for example, about 5 degrees) than the operating temperature. Pressure.

  On the other hand, in Example 2, although the gas-liquid mixed state is configured from the membrane module inlet, it is an implementation condition that the amount of gas phase is small, so that concentration polarization is relatively eliminated compared to Comparative Example 3. It is presumed that this has not been done.

  About Examples 3 and 4 in which the amount of steam is 1 L / h or more, a sufficient stirring effect is obtained, and it can be presumed that Comparative Example 3 has an intermediate stirring effect. As a result, it is considered that the film performance of Comparative Example 3 is improved as compared with the execution conditions according to Example 2.

  Further, in Example 3 where the steam supply liquid flow rate is 1 L / h, the permeate flow rate is 950 g / h, and the membrane performance is improved by about 20% compared to Comparative Example 3. From this, under the present conditions, the vapor supply liquid flow rate is 1 L / h or more, so that the latent heat of vaporization of the membrane permeate (water) can be sufficiently replenished and concentration polarization can be eliminated. It is guessed. Furthermore, in Example 4 where the steam supply liquid flow rate was 2 L / h, a permeate flow rate comparable to that in Example 3 was obtained. Thus, it can be seen that, under the present operating conditions, by setting the steam supply liquid flow rate to 1 L / h or more, the latent heat of vaporization can be sufficiently replenished and the concentration polarization can be eliminated. In Comparative Example 3, it is presumed that no gas-liquid mixed state is formed from the membrane supply inlet.

Example 5 and Comparative Example 5
Next, when the supply liquid flow rate is 10 L / h and a T-type zeolite membrane is used as a separation membrane, a gas-liquid mixed state is obtained by blowing steam (gas phase) at a temperature 2 to 5 ° C. higher than the liquid phase. Membrane separation was performed when the liquid to be treated was supplied to the separation membrane surface (Example 5) and when the liquid to be treated was supplied to the separation membrane surface under pressure (Comparative Example 5). The separation conditions and results are shown in Table 3.

  From Table 3, the permeate flow rate (permeation flux) is about 1.5 times higher in Example 5 than in the case of saturated vapor blowing (see Comparative Example 1 in Table 1) when the separation membrane is NaA type. It was. That is, by blowing steam at a temperature higher than the liquid phase, concentration polarization formed on the membrane surface due to the stirring action of the gas is eliminated, and the latent heat of evaporation of the membrane permeate (water) can be sufficiently replenished. This is presumed to be due to this. Moreover, since a high permeate flow rate is obtained as compared with Comparative Example 5, it can be seen that even if the separation membrane is a T-type zeolite membrane, high membrane performance can be exhibited by the membrane separation method of the present invention.

  The present invention can be used for separation of a contaminated component from a liquid mixture that is difficult to separate, such as a water-ethanol mixture, or concentration and purification by separating and removing the contaminated component.

BRIEF DESCRIPTION OF THE DRAWINGS Drawing used for description of the membrane separator which concerns on one Embodiment of this invention. Drawing used for description of a steam generator. Drawing used for description of separation membrane. The figure which uses for description of the membrane separator which concerns on another embodiment of this invention. The drawing which shows the membrane module which concerns on one Embodiment of this invention. Drawing which shows the membrane module which concerns on another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid mixture tank 11 Liquid feed pump 12 Regenerator 13 Heater 14, 141, 142 Membrane module 15 Steam generator 17 Product tank 18 Vacuum pump 19 Condenser 20 Permeate tank 21 Supply device 22 Heating device 23 Steam superheater (Super heater)
23a Gas superheater 29 Steam supply unit 29a Gas supply unit 31 Separation membrane 31a Zeolite membrane 31b Porous support base 32 Fastener 33 Separation membrane circular tube plate 34 Decompression unit 35 Decompression unit shell cover 40 Channel 45 Turbulence promoter 48 Casing 50 Heat supply unit 100, 101 Membrane separation device

Claims (6)

The liquid mixture is a gas-liquid mixed fluid containing a gas phase having a temperature higher than the liquid phase, the gas-liquid mixed fluid is present on the primary side of the separation membrane, and the secondary side has a negative pressure. A membrane separation method characterized in that contaminant components are allowed to permeate the secondary side of the separation membrane. A steam generator that converts a portion of the liquid mixture into a gas phase having a temperature higher than the liquid phase;
A membrane separation apparatus comprising: a membrane module having a separation membrane for separating contaminant components in the gas-liquid mixed liquid mixture containing the gas phase. 3. The membrane separation device according to claim 2, wherein the vapor generating device includes a heating device that heats the liquid mixture to form a vapor. 4. The membrane separator according to claim 3, wherein the steam generator further includes a steam superheater that superheats the steam generated by the heating device. A heating means for boiling a part of the liquid mixture into a gas-liquid mixed state containing a gas phase having a temperature higher than the liquid phase;
A membrane module comprising: a separation membrane that separates contaminant components in the liquid mixture in the gas-liquid mixed state. 6. The membrane module according to claim 5, wherein the heating means is disposed in the vicinity of the primary surface of the separation membrane.

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