Liquid separating apparatus

Abstract: The present invention is directed to a liquid separating apparatus comprising a primary chamber (111) on the high pressure side to which the given mixed liquids containing the liquid to be separated and the other liquid are fed, and a secondary chamber (113) on a low side which comes into contact with the primary chamber (111) through the selective transmission separation membrane (107) for liquid separating use, and heating pipes (106) which heats the mixed liquids to be fed so as to raise the temperature thereof, and simultaneously, and interrupts the flow of the mixture liquids.

Description: The present invention generally relates to a liquid separating apparatus using a permeation evaporating method. Generally, in the field of a chemical industry, so-called organic solvents such as alcohol and its kind, kent and its kind, ether and its kind, ester and its kind, and so on are often used. All these organic solvents are likely to dissolve in water. Accordingly, they are likely to become generally mixed with water even in the preserving condition so as to form an azeotropic mixture with respect to the water. However, when the organic solvent is used in actual chemical reaction, an extremely high purity is demanded, with a strict limit being imposed upon the mixture of the water. Thus, in the actual use, a concentration system is generally adopted of increasing the purity through the separation of the water from the organic solvent as the prior treatment step. Also, in a step of washing precision components such as semiconductors or the like, the product is washed with pure water, thereafter with, for example, isopropanol (namely, alcohol group washing liquid) so as to completely remove the moisture adhered in the former step. At this time, the isopropanol as the washing liquid is diluted by the repeated use thereof through the moisture of the former step. When the washing operation is effected by the use of the isopropanol diluted into the concentration of 90 % or lower, the moisture remains on the product, which may cause defects in the portion thereof. Therefore, there is required a regenerating system which separates the water from the isopropanol diluted by the use in the precision washing operation so as to increase the purity for the reuse thereof. Conventionally a distillation method was generally used as a method of separating the water (pure water) from the mixed liquid between water and organic solvent such as alcohol or the like so as to concentrate the organic solvent. However, in the case of the distillation method, it is difficult to separate azeotropic mixture, approximate boiling point mixture or the like in terms of the principle thereof. As the mixture between the above-described water and alcohol (ethanol, isopropanol or the like) corresponds to the azeotropic mixture, the separating operation cannot be effected by the conventional general distillation method. In such a case as described hereinabove, although a so-called azeotropic distillation method which makes it possible to effect an separating operation through the addition of the given tertiary component such as benzene, trichloroethylene or the like may be adopted, the method consumes an extreme large quantity of steam consumed in this method, with many problems that the separation liquid is polluted by the tertiary component mixture, the apparatus is complicated, and so on. In recent years a separation (dehydration) system for water/organic liquid mixtures has been proposed using, for example, moisture selective transmission membranes (for example, as disclosed in Japanese Patent Application No. 62-35401). In the liquid mixture separating system, a primary chamber and a secondary chamber are partitioned, in the primary chamber a separating operation is effected by a moisture selective transmission membrane composed of a non-porous amorphous high molecular membrane. The mixture containing the water is fed into the primary chamber and in the secondary chamber the transmitted separation component is condensed and stored. The secondary chamber side is pressure-reduced by pressure reducing means such as a vacuum pump or the like so as to form a partial pressure difference of the given value between the primary chamber side boundary face of the water selective transmission membrane and the secondary chamber side boundary face. The water molecule (H₂O) only transmitted through each step of adsorption → resolution → diffusion → disconnection is adapted to take out in a gaseous condition onto the side of the secondary chamber of lower pressure from the the primary chamber side of higher pressure in accordance with the partial pressure difference and the concentration difference of the selection component between the primary side and the secondary side. Accordingly, according to the mixed liquid separating system of such a construction as described hereinabove, not only approximate boiling point mixed liquids, but also azeotropic mixed liquids such as the above-described water and alcohol may be separated, concentrated without any questions. Furthermore, as the tertiary component as in the azeotropic distillation method is not used at all, with the advantage that the operation is clean, and the apparatus is also compact. In the actual system, the construction through the combination between the primary chamber and the secondary chamber as described hereinabove uses modules as a single unit, and a plurality of pair combinations with them are often used as plant. As the permeation evaporating operation in the liquid separating apparatus is a separating operation substantially accompanying a phase variation (liquid phase → gas phase) as clear from the above-described explanation, the temperature of the feed liquid around the permeation membrane is gradually lowered due to the evaporation latent heat of the transmission material as the separating condition advances. The transmission speed in the transmission membrane portion has an exponential function relation with respect to the temperature of the fed liquid, and is higher as the molecular activity becomes active with the temperature being higher. Accordingly, when the temperature of the feed liquid is lowered as described hereinabove, the transmission speed of the object liquid is lowered deteriorating the separation efficiency. EP-A-0 118 760 discloses a liquid separating device comprising a membrane which allows a vapour to pass but which holds back liquids. The chamber on the vapour side of the membrane is held under a lower pressure than the liquid side of the membrane. Vapour passing through the membrane is fed to a condensor. The temperature reduction of the liquid fed into the primary chamber is already mentioned as to accompany the phase variations of one of the components of the mixed liquids. To prevent the mixed liquids from underheating due to the vaporization latent heat, heating elements are proposed which are in contact with the primary chamber, the heating medium being separated from the mixed liquids by a heat transfer plate. Additionally, as the liquid separating system by the liquid separating method using the selective transmission membrane is adapted to efficiently transmit only the selection component, a so-called concentration boundary membrane (concentration boundary layer) is formed, because the number of selection molecules which become separation objects is decreased in the mixed liquids near the selective molecule adsorption face of the transmission membrane as the flow of the mixed liquids on the primary chamber side is slow, so that the necessary concentration difference may not be retained, with a problem that the transmission speed and transmission efficiency are deteriorated. Accordingly, an object of the present invention is to provide a liquid separating apparatus, wherein the liquid separation from a mixed liquid may be effected efficiently, and the dirt from the concentrated liquid may be efficiency removed. Another important object of the present invention is to provide a liquid separating apparatus, wherein the mixture dilution of feed liquid within a primary chamber is prevented, the temperature reduction in the temperature reduction of the feed liquid within the primary chamber is prevented, furthermore the concentration boundary membrane near the primary chamber side surface of the selective transmission membrane may be prevented from being grown. Still another object of the present invention is to provide a liquid separating apparatus, wherein the low concentration liquid on the entrance side within the primary chamber does not mix, dilute the high concentration liquid on the exit side so as to prevent the separating performance from being lowered. The above objects are solved by a liquid separating apparatus comprising a primary chamber on a high pressure side to which a given mixture of liquids containing the liquid to be separated and another liquid is fed, a secondary chamber on a low pressure side which receives the liquid to be separated in vapour form, an amorphous, high molecular selective transmission membrane through which the secondary chamber comes into contact against the primary chamber, for selectively transmitting the liquid to be separated to the secondary chamber, and at least one heating pipe disposed within the primary chamber on the high pressure side to heat the mixture of liquids flowing in the primary chamber from an inlet to an outlet of the primary chamber to compensate for the lost latent heat of evaporation through the phase change of the separated liquid and also create turbulence in the flowing mixture of liquids. In a preferred embodiment a plurality of fins are provided on an outer periphery of the at least one heating pipe. In a further preferred embodiment the interior of the primary chamber is partitioned by a plurality of partition walls which are alternately projecting from the mutually opposite inner walls of the primary chamber and are confronted in the positions away at given intervals from the inner walls opposite at the respective tip ends to form a series of flow passages continuous towards the exit side from the entrance side among these partition walls and the at least one heating pipe is disposed within the flow passages. In still a further preferred embodiment the flow passage is formed between a pair of partition walls in a spiral shape towards the central portion from the inner walls in the primary chamber. The temperature reduction amount by the evaporation latent heat to be caused through the progress of the transmission separating action of the selection molecule may be sufficiently compensated by a temperature raising operation through the heating by the at least one heating pipe, and the stable transmission speed as desired may be retained, with a superior effect that the transmission efficiency may be improved. Also, the at least one heating pipe causes a turbulent flow in the mixed liquids to be fed, with a superior effect that the concentration boundary membrane to be caused near the adsorption face of the selective transmission separating membrane may be effectively reduced, and the transmission efficiency may be improved even from this point. Also, in the liquid separating apparatus of the invention, many fin members are provided on the outer peripheries of the heating pipe, the fin members retain a wide contact area to come into contact against the feed mixed liquids within the primary chamber on the high pressure side, so that the heat capacity from the thermal source medium passing through the heating pipe may be transmitted into the mixed liquids with more efficiency. Also, simultaneously with it, when many fin members are provided as described hereinabove, so that the stirring force of the mixed liquids becomes larger than in a case of a heating pipe only so as to increase a concentration boundary membrane removing function. The present invention will be better understood from the following description taken in conjunction the accompanying drawings, in which; Fig. 1 is a dismantled perspective view of the major construction portions showing the module construction of a liquid separating apparatus in the embodiment 1 of the present invention; Fig. 2 is a longitudinal sectional view of the liquid separating apparatus shown in Fig. 1; Fig. 3 is an enlarged sectional view of the liquid portion apparatus shown in Fig. 1; Fig. 4 is a characteristic chart showing the variation characteristics in the transmission efficiency through the temperature fall of the feed mixed liquids by the evaporation latent heat with the concentration density (dehydration density) of alcohol and the feed flow amount as parameters; Fig. 5 is a characteristic chart showing the relation between the concentration difference of the water molecule component among the separating membrane boundary faces, and the water component transmission amount; Fig. 6 is a view corresponding to Fig. 1 of the liquid separating apparatus in the embodiment 2 of the present invention; Fig. 7 is a sectional view corresponding to Fig. 3 of the liquid separating apparatus in the embodiment 2; Fig. 8 is a block diagram showing a precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 3 of the present invention is applied; Fig. 9 is a block diagram showing the precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 4 of the present invention is applied; Fig. 10 is a block diagram showing the precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 5 of the present invention is applied; Fig. 11 is a block diagram showing a precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 6 of the present invention is applied; Fig. 12 is a decomposed perspective view showing the module construction of the liquid separating apparatus in the embodiment 7 of the present invention; Fig. 13 is a lateral sectional view of the liquid separating apparatus shown in Fig. 12; Fig. 14 is a decomposed perspective view showing the module construction of the liquid separating apparatus in the embodiment 8 of the present invention; Fig. 15 is a lateral sectional view of the liquid separating apparatus shown in Fig. 14; Fig. 16 is a characteristic chart showing the variation characteristics in the transmission efficiency through the existence, absence of the mixed dilution within the primary chamber in the relation between the flow amount of the mixed liquid (which is an alcohol aqueous solution) to be fed into the primary chamber and the concentration of a concentrated liquid (which is alcohol) on the exist side; Fig. 17 is a decomposed perspective view showing the module construction of the liquid separating apparatus in the embodiment 9 of the present invention; and Fig. 18 is a decomposed perspective view showing the module construction of the liquid separating apparatus in the embodiment 10 of the present invention, respectively. Referring now to the drawings, there are shown some preferred embodiments of the present invention as liquid separating apparatuses. (Embodiment 1) Fig. 1 and Fig. 2 show a liquid separating apparatus in the embodiment 1 of the present invention. The liquid separating apparatus of the present embodiment is provided to separate the water (H20) from the alcohol aqueous solution to obtain the concentrated alcohol, and is a permeation evaporation module unit A of a plate and frame type. In each drawing, reference character 101 is a first frame having a given width for forming the primary chamber 111 on the high pressure side for feeding the mixed liquids. A mixed liquid feed opening 104 which is communicated into a feed tank FT through a feed pipe 103 is provided under, for example, the front end portion in the first frame 101. Also, an exhaust opening 105 for exhausting the concentrated alcohol after the water (H20) which is a separation liquid as an object has been transmitted, removed is provided above the rear end side thereof. Furthermore, reference characters 106, 106 ... are a plurality of heating pipes which are provided in parallel at given intervals in the longitudinal direction between the upper and lower frame members 101A, 101B of the first frame 101, and are connected with a U-shaped pipe on the outer end side so that they are continuously communicated with each other. One end side 106a thereof is adapted to be connected with, for example, a warm water feeding source as a thermal source, so that the warm water of the given temperature is adapted to flow in the arrow direction. Reference character 107 is a selective transmission membrane or a selective transmission separation membrane composed of, for example, a water selective amorphous high molecular membrane (described later) which is mounted on the right, left opening face side of the first frame 101, and blockades the space within the frame (the primary chamber 111). The secondary frame 102 adjacent to the first frame 101 is integrated with the first frame 101 through the selective transmission separation membrane 107 on one side, so that the secondary chamber 113 on the pressure side for drawing out the moisture (H₂O) through the selective transmission separating membrane 107 is formed on the inner side thereof. The secondary chamber 113 is connected with a pressure reducing means not shown such as a vacuum pump or the like through a suction opening 114. The interior of the secondary chamber 113 is adapted to be reduced in pressure into an approximate vacuum condition by the operation of the pressure reducing means. Accordingly, according to the liquid separating apparatus A of the construction of the embodiment, the mixed liquids of water (H₂O) and alcohol (for example, ethyl alcohol:C2H5OH) to be continuously fed, introduced into the primary chamber 111 from the mixed liquid feed opening 104 through, for example, the feed pump FP from the feed tank FT, flows slowly into the primary chamber 111 for the given time in accordance with the feed thereof and the exhaust speed thereof. In the condition, the side of the secondary chamber 113 is reduced in pressure into an approximate vacuum condition so as to realize the partial pressure difference more than the given value between the selection molecule adsorption face 107a of the selective transmission separating membrane 107 and the selection molecule disconnection face 107b on the secondary chamber side. The selective transmission separating membranes 107, 107 in the present embodiment as described hereinabove selectively transmit only the water (H₂O) component as the object. They are formed of a water transmission amorphous high molecular membrane (for example, as disclosed in the specification of Japanese Patent Application No. 62-35401) composed of, for example, "α - fluoro acrylate copolymer". The water component (H₂O molecule) corresponding to the selection characteristics thereof is transmitted from the primary chamber 111 on the high pressure side into the secondary chamber 113 at the transmission speed proportional to the temperature of the mixed liquids themselves, and the concentration difference of the selection component (H₂O) between the primary chamber 111 side and the secondary chamber 113 side. In this case, in the transmission of the water component (H₂O), the water molecule H₂O in the mixed liquids within the primary chamber 111 on the high pressure side is absorbed on the adsorption surfaces 107a of the selective transmission separation membrane 107 at first by the material (molecule) moving energies accompanied by the concentration difference of the selection molecule from the high pressure side onto the low pressure side. Thereafter, the water molecule H₂O is evaporated, diffused in the separation membrane 107 by the molecule accompanied by the resolution action. The evaporated and diffused amount of the water molecule H₂O at this time largely depends upon the temperature of the mixed liquids, and the partial pressure difference between both the boundary faces of the separation membranes 107, the concentration difference of the selection molecule H₂O, or the like. In this case, the partial pressure difference may be comparatively easily controlled into an ideal value by the constant control of the feed pressure through the feed pump FP on the mixed liquid feed side, and also, by the constant control of the reduced pressure value through the pressure reducing means. But the temperature of the mixed liquids on the side of the primary chamber 111 on the high pressure side and the concentration difference of the selection component (H₂O molecule) may not be easily maintained at a desired value, considering the following situation. Namely, as described hereinabove, the transmission action at the selective transmission membranes 107, 107 is a liquid separating one, and naturally accompanies the phase variation (liquid phase → gaseous phase) of the water component H₂O which is a selection molecule. Thus, as the separation action is advanced, the evaporation latent heat amount is increased to lower the temperature on the mixed liquid side. But, as described hereinabove, the transmission speed of the water molecule (H₂O) for transmitting through the selective transmission separating membranes 107, 107 becomes higher when the temperature of the mixed liquids is higher (under ideal conditions) as described from the alcohol concentration degree characteristics of Fig. 4, and is superior in transmission performance. Accordingly, in the construction of the present embodiment, the mixed liquids within the primary chamber 111 on the high pressure side are adapted to be equally heated, raised in temperature from the entrance side thereof onto the exit side thereof by a plurality of heating pipes 106, 106 ... as described hereinabove with the warm water passing therethrough. Therefore, the temperature fall of the mixed liquids through the evaporation latent heat, especially the reduction in the transmission speed of the water molecule is compensated for (the ideal temperature conditions of Fig. 4 are maintained). As the selective transmission separating membranes 107, 107 are constructed as water selective ones as described already, a continuous layer with the water molecule H₂O component being short is formed inevitably on the side of the adsorption face 107a by the continuous transmission of the water molecule H₂O. This is generally called concentration boundary membrane, with a problem that the concentration difference is largely reduced if it is formed to deteriorate the transmission speed, the transmission efficiency of the water component (see Fig. 5). But, as described hereinabove, in the present embodiment, a plurality of heating pipes 106, 106 ... are vertically extended as described at the given intervals from the side of the mixed liquid feed opening 104 of the central portion within the primary chamber 111 onto the side of the exhaust opening 105, and are disposed orthogonal with respect to the direction along which the mixed liquids flow. Thus, as shown in Fig. 3, the liquid flowing from the side of the mixed liquid feed opening 104 onto the side of the concentrated liquid exhaust opening 105 is spread right and left, forming the turbulence sequentially in each of the heating pipes 106, 106 ... portions, so that the above-described concentration boundary membrane is destroyed, removed by the stirring action. As a result, the concentration difference of the desired value may be maintained, thus realizing higher transmission speed and transmission efficiency of the water component even in terms of this point. (Embodiment 2) Fig. 6 and Fig. 7 show a liquid separating apparatus in the embodiment 2 of the present invention. The present embodiment, as described in Fig. 6, is characterized in that many fin members 131, 131 are provided in parallel in the longitudinal direction on each outer peripheral face of a plurality of heating pipes 106, 106 ... in the construction of the above-described embodiment 1, with the other construction being completely similar to the construction in the case of the embodiment 1. In such a construction, as shown in Fig. 7, the mixed liquids flowing around the heating pipes 106, 106 ... come into contact with the heating pipes 106, 106 by the wider contact areas so as to considerably improve the heating efficiency as compared with the construction of the embodiment 1. Also, simultaneously with it, as the fin members 131, 131 ... are adapted to stir the flow of the mixed liquids more effectively and complicatedly, the above-described concentration boundary membrane removing function is improved. (Embodiment 3) Fig. 8 shows a precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 3 of the present invention is applied. The liquid separating apparatus in the present embodiment is applied to a regenerating system for isopropanol to be used in the precise washing for semiconductors and so on with a permeation evaporation module unit A (which is illustrated in the above-described embodiments 1, 2) for separating, removing the moisture from the isopropanol to concentrate it, and a filter unit 141 for filtering the concentrated liquid to be guided from the permeation evaporation module unit A being provided as the major construction portion. In the case of the present embodiment, a used washing liquid tank 143 wherein the used isopropanol to be flowed back from the precise washing machine 142 is stored, a used washing liquid feeding pump 144, a primary chamber 111 of the permeation evaporation module unit A, a buffer tank 145, a regenerated washing liquid feeding pump 146, a filter unit 141 and a regenerated washing liquid tank 147 are sequentially connected to constitute the precise washing liquid regenerating system. The reference character 148 is a condenser for condensing the moisture separated from the primary chamber 111 into the secondary chamber 113 in the permeation evaporation module unit A, and the reference character 149 is a condensed liquid tank. The filter unit 141 is a precise filtration filter made of fluorine-resin macaroni yarn type or plane membrane type. The precise washing machine 142 is adapted to wash with isoporpanol the precise parts such as semiconductor and so on after they have been washed with pure water. The used washing water feeding pump 144 and the regenerated washing liquid feeding pump 146 are both an estimation type (for example, bellows pump) made of fluorine resin. The operation of the precise washing liquid regenerating system shown in Fig. 8 will be described hereinafter. In the precise washing machine 142, diluted isopropanol as the used washing liquid which is used in precise parts washing is fed into the primary chamber 111 of the permeation evaporation module unit A by the operation of the used washing liquid feeding pump 144 after it has been stored in the used washing liquid tank 143, and the water (H₂O) only is permeated, separated onto the side of the secondary chamber 113, and is concentrated by the action of the selective permeation separating membrane 107 disposed between the primary chamber 111 and the secondary chamber 113. The water which has transmitted through the selective transmission separating membrane 107 is concentrated by a condenser 148, thereafter is stored in the concentrated liquid tank 149, and is exhausted periodically. The isopropanol condensed in the permeation evaporation module unit A is once stored in the buffer tank 145, thereafter is fed under pressure into the filter unit 141 by the regenerating washing liquid feeding pump 146, wherein the dirt to be mixed in the precise washing machine 142, the pumps 144, 146, the permeation evaporation module unit A and so on is filtered and is provided as clean concentration isopropanol. The condensed isopropanol thus provided is fed into the precise washing machine 142 through the regeneration washing liquid tank 147 and is provided again for washing the precise parts. (Embodiment 4) Fig. 9 shows the precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 4 of the present invention has been applied. In the case the present embodiment, the used washing liquid feeding pump 144 is adapted to be used as the regeneration washing liquid feeding pump, with the buffer tank 145 and the regenerating washing liquid feeding tank 146 on the exit side of the permeation evaporation module unit A being omitted from the precise washing liquid regenerating system shown in Fig. 8 and the regenerating washing liquid feeding tank 146. In this case, the discharge pressure of the pump 144 is set to a pressure exceeding the total sum of the pressure loss in the permeation evaporation module unit A and the pressure loss in the filter unit 141. (Embodiment 5) Fig. 10 shows the precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 5 of the present invention is applied is shown. In the case of the present embodiment, in the precise washing liquid regenerating system shown in Fig. 9, a heating exchanger 150 for cooling use which cools the condensed isopropanol to the normal temperature in the module unit A is additionally provided on the exit side of the permeation evaporation module unit A. In the case of the present embodiment, in the permeation evaporation module unit A, the isopropanol which has been concentrated and heated by the heating pipes 106, 106 ... disposed within the primary chamber 111 is cooled down to the normal temperature by the heat exchanger 150 for cooling use so as to be fed into the filter unit 141. (Embodiment 6) Fig. 11 shows the precise washing liquid regenerating system to which the liquid separating apparatus in the embodiment 6 of the present invention has been applied. In the case of the present embodiment, in the precise washing liquid regenerating system shown in Fig. 10, a heat exchanger 151 for heat recovery use which thermally exchanges the used isopropanol to be fed into the module unit A with the concentrated isopropanol to be guided from the module unit A, and recovers the heat the concentrated isopropanol retains as the preheating use of the used isopropanol. In the case of the present embodiment, the used isopropanol is preheated by the concentrated isopropanol, and also, the concentrated isopropanol cooled by the preheating operation is fed into the filter unit 141 after the temperature has been cooled to the normal temperature by the heat exchanger 150 for cooling use. (Embodiment 7) Fig. 12 and Fig. 13 show a liquid separating apparatus in the embodiment 7 of the present invention. The liquid separating apparatus of the present embodiment is of a module construction of a plate and frame type, with the liquid separating apparatus shown showing a simple member of the module. Also, the liquid separating apparatus of the present embodiment is used as an apparatus for concentrating the alcohol through the separation of the water (H₂O) which is the separating object component from the alcohol water solution by the permeation evaporation method, with the alcohol water solution diluted by the water being provided as an object mixed liquid. The liquid separating apparatus (concretely a simple member module for separating the liquid) is composed of a first frame 201 for forming the primary chamber 211 on the high pressure side for feeding the mixed liquid (namely, alcohol water solution), second frames 202, 202 which are adjacently disposed on both the sides of the first frame 201, and form the secondary chambers 221, 221 on the low pressure side, selective transmission members 203, 203 disposed between the first frames 201 and the second frames 202, 202. The first frame 201 is composed of rectangular frame member, with a mixed liquid feeding opening 212 which is communicated with the feed tank 205 through the feed pipe 204 being provided in the upper portion of the front frame 201a. The reference character 206 is a feed pump. Also, an exhaust opening 213 for exhausting the product alcohol, whose water (H₂O) as a separating object component is transmitted, removed and condensed is provided in the upper portion of the rear frame 201b of the first frame 201. A plurality of alternately adjacent partition walls 207, 207... are projected from the inner faces of upper, lower frames 201c, 201d of the first frame 201, with the tip ends of these partitioned walls 207, 207 ... being confronted in the positions away at given intervals from the inner faces of the mutually opposite frames 201c, 201c. A series of slender, folded flow passages 8 towards the exhaust opening 213 from the feed opening 212 are formed among the partitioned walls 207, 207 ... . Namely, within the primary chamber 211 to be formed within the first frame 201, the mixed liquids are adapted to be circulated along the flow passage 208 as shown in an arrow towards the exhaust opening 213 from the feed opening 212, with a flow passage construction that a liquid for circulating onto the entrance side is not mixed with the liquid for circulating on the exit side. Heating pipes 209, 209 ... which extend through the central portion among the partitioned walls 209, 209 ... are respectively disposed between the upper, lower frames 201c, 201d in the first frame 201. These heating pipes 209, 209 ... are adapted to heat the feeding liquid into the given temperature, and are connected by U-shaped connecting pipe portions 209a, 209a ... on the outer side of the first frame 201 for mutual communicating condition, and are adapted to constitute a series of heating pipe passage P. One end side P1 of the heating pipe passage P is connected with, for example, the warm water feeding source (not shown), so that the warm water of the given temperature is adapted to flow in an arrow G direction which becomes opposite in current with respect to the circulating direction of the feeding liquid in the flow passage 208. Also, when the pressure difference between the primary chamber 211 and the secondary chamber 221 is not too much as in the start operation or the stop operation of the liquid separating apparatus, the selective transmission membranes 203, 203 on both the sides of the primary chamber 211 may be oscillated due to the circulation of the feeding liquid, but both the selective transmission membranes 203, 203 are prevented from coming into contact against each other by the existence of the partitioned walls 207, 207 ... . Namely, these partitioned walls 207, 207 ... serve as spacers for retaining the interval between both the selective transmission membranes 203, 203. As the flowing passage 208 is effective if it is made as slender as possible, the number of the partitioned walls 207, 207 ... to be formed is desired to be more in a range, wherein the inner pressure loss does not exceed the tolerance range, and the space for allowing the arrangement of the heating pipes 209, 209 ... is retained. Also, the contact portion between each partitioned wall 207 and the selective transmission membrane 203 is desired to be made as thin as possible in the thickness of the partitioned wall 207, as the contact portion thereof becomes a portion where the membrane separating action can not be exhibited. The second frame 202 is composed of the first frame 201 and a rectangular frame of the same shape. The secondary chamber 221 to be formed within it is partitioned from the primary chamber 211 within the first frame 201 by the selective transmission membrane 203. The secondary frame 202 has a suction opening 222 therein to be connected with a vacuum pump (not shown) which serves as a pressure reducing means for reducing the pressure within the secondary chamber 221 into an approximately vacuum condition. The selective transmission membrane 203 is composed of an amorphous high molecular membrane having a quality through which only a particular component molecule (in the case of the present embodiment, water molecule) to be contained in the feed mixed liquids is selectively transmitted. The selective transmission membrane has an action of transmitting into the secondary chamber 221 the water molecule only from the feed liquid circulating through the primary chamber 211. For example, α - fluoro acrylic interpolymer or ethylene unsaturated compound (for example, styrene, vinyl chloride, acrylonitrile, hydroxy ethyl acrylate, acrylic acid or the like) is copolymerized with the α - fluoro acrylic interpolymer to mold a membrane shape, and is used as the selective transmission membrane 203. The operation of the shown liquid separating apparatus will be described hereinafter. An alcohol water solution (namely, alcohol diluted with water) to be continuously fed into the mixed liquid feeding opening 212 through the feed pump 206 from the feed tank 205 flows slowly along the flow passage 208 formed within the primary chamber 211 in accordance with the feed thereof and the exhaust speed thereof. The secondary chamber 221 is reduced in pressure so that the pressure may become an approximately vacuum condition by the operation of the pressure reducing means, simultaneously with the feeding of the alcohol water solution into the primary chamber 211. As a result, the pressure difference more than the given value is adapted to be realized between the primary chamber 211 side and the secondary chamber 221 side in the selective transmission membrane 203. As described hereinabove, the selective transmission membrane 203 in the present embodiment is composed of an amorphous high molecular membrane having characteristics which allow only the water molecule as the separating object component to be transmitted therethrough. The water molecule corresponding to the selective characteristics is transmitted from the primary chamber 211 to the secondary 221 at a transmission speed proportional to the partial pressure difference of the water molecule between the primary chamber 211 and the secondary chamber 221. Thus, the alcohol water solution flowing through the flow passage 208 is gradually condensed by the transmission separation of the water molecule from the primary chamber 211 to the secondary chamber 221 into the high concentration of alcohol and is exhausted from the exhaust opening 213. In this process, as the feed mixed liquids F are flowed along a slender flow passage 208 partitioned by the partitioned walls 207, 207 ..., the lower concentration liquid near the entrance side (namely, feed opening 212) and the higher concentration liquid near the exit side (namely, the exhaust opening 213) do not effect the mixed dilution any more, the separation performance is considerably improved as compared with the case where the partitioned walls 207, 207 ... are not formed. This description is clear from the characteristic graph showing the variation in the alcohol concentration in the primary chamber 211 exit with respect to the flow amount of the alcohol water solution shown in Fig. 16. Namely, the comparison between a characteristics curve g in a case (namely, under ideal conditions) where the mixed dilution between the low concentration liquid and the high concentration liquid is not effected within the primary chamber 211, and a characteristics curve g' in a case (namely, under the mixed conditions) where the mixed dilution between the low concentration liquid and the high concentration liquid is effected within the feed liquid chamber 211 shows that although the reduction in the separation performance of the module cannot be denied through the increase in the flow amount, the separation performance under the ideal conditions where the mixed dilution is not effected is considerably improved as compared with the separation performance under the mixed conditions where the mixed dilution is caused. As the separation of the water molecule by the selective transmission membrane 203 depends upon the permeation evaporation accompanying the phase variation of the water molecule as the selection transmission component, the separation causes the temperature fall on the side of the feed liquid, because the evaporation latent heat amount is also increased as the separating action is advanced. In the case of the present embodiment, as the feed liquid flowing through the flow passage 208 is adapted to be heated through the heating action by the heating pipes 209, 209 ..., the temperature fall of the feed liquid by the evaporation latent heat is compensated to prevent the transmission speed of the water molecule from being lowered. This description is clear from the characteristic graph showing the variation in the alcohol concentration in the exit of the primary chamber 211 with respect to the flow amount of the alcohol water solution shown in Fig. 4. Namely, the comparison between a characteristic curve h in a case (where the means for heating the feed liquid is taken) where the temperature fall of the feed liquid is adapted not to be effected within the primary chamber 211 and a characteristic curve h' in a case (namely, where a means for heating the feed liquid is not taken) where the temperature fall of the feed liquid is adapted to be effected within the primary chamber 211 shows that although the fall in the separating performance of the module cannot be denied through the increase in the flow amount, the separation performance under the ideal conditions where the temperature fall of the feed liquid is not caused is considerably improved as compared with the separating performance under the temperature fall conditions where the temperature fall of the feed liquid is caused. The transmission of the water molecule in the case of the present embodiment is sequentially effected through the steps of melting into the selective transmission membrane 203 of the water molecule by the molecule movement through adsorption, resolution actions of the water molecule onto the surfaces of the selective transmission membrane 203 by the suction energies onto the low pressure side from the high pressure side, and diffusing onto the low pressure side of the water molecule in the selective transmission membrane 203, and disconnecting the water molecule from the low pressure side surface of the selective transmission membrane 203. Although it is known that the transmission speed in the mechanism of such water molecule transmission as described hereinabove depends upon the various factors, there is, as an important factor for controlling the transmission speed, a partial pressure difference of separation object components (in the case of the present embodiment, water molecule) on the high pressure side and the low pressure side of the selective transmission membrane 203. It is a known fact that the partial pressure difference is determined by the concentration difference of the separation object components on the high pressure side and the low pressure side of the selective transmission membrane 203. When the selection transmission of the water molecule through the selective transmission membrane 203 is continuously effected, a layer (in other words, a layer high in alcohol concentration) wherein water molecule is short is produced on the primary chamber 211 side (namely, on high pressure side) of the selective transmission membrane 203. This is generally called concentration boundary membrane, the concentration difference between the separating object components (water molecule) on the high pressure side and the low pressure side of the selective transmission membrane 203 becomes extremely small by the production of the concentration boundary membrane, with a problem that the transmission speed of the water molecule is considerably lowered (see Fig. 5). The production of such concentration boundary membrane as described hereinabove is conspicuous in a case where the circulating fluid is in layer flow. The production of the concentration boundary membrane is prevented through the promotion of the turbulence of the circulating fluid. Accordingly, when the interior of the primary chamber 211 is partitioned by many partitioned walls 207, 207 ... and a series flow passages 208 towards the exhaust opening 213 from the side of the feed opening 212 have been formed as described in the present embodiment, the flow speed of the feed liquid circulating through the flow passages 208 becomes relatively faster as compared with a case where the feed liquid is circulated through the primary chamber 211 in a condition where the interior of the primary chamber 211 is not partitioned by the partitioned walls 207, 207 ... . Thus, the turbulence is promoted by the increase in the flow speed near the surface on the side of the primary chamber 211 of the selective transmission membrane 203. The production of the concentration boundary membrane on the high pressure side (in other words, on the side of the primary chamber 211) of the selective transmission membrane 203 by the promotion of the turbulence is prevented, and the supply of the separation object component (water molecule) onto the high pressure side surface of the selective transmission membrane 203 is continuously effected. Accordingly, the concentration difference of the separation object component on the high pressure side and the low pressure side of the selective transmission membrane 203 may be maintained normally at the given value or more, so that the transmission speed and the transmission efficiency may be improved. As described hereinabove, when the high, low pressure difference between the primary chamber 211 and the secondary chamber 221 is not too much as at the start of the apparatus, the stop thereof or the like, the selective transmission membranes 203, 203 on both the sides of the primary chamber 211 may be oscillated due to the circulation of the feed liquid, but the partitioned walls 207, 207 ... serve as spacers for preventing the contact of both the selective transmission membranes 203, 203, thus greatly contributing towards the improvement in the durability of the selective transmission membranes 203, 203. (Embodiment 8) Fig. 14 and Fig. 15 show such a liquid separating apparatus as in the embodiment 8 of the present invention. In the liquid separating apparatus of the present embodiment, many disc-shaped heating fins 210, 210 ... are formed on the outer peripherally of each heating pipe 209 in the liquid separating apparatus of the embodiment 7. The heating fins 210, 210 ... have heating operations by the heating pipes 209, 209 ... and an operation for furthermore promoting the turbulence of the feed liquid. As the other construction and operations are similar to those of the embodiment 7, the description thereof will be omitted. In the above-described illustration, although the present embodiment is applied to a case where the water component is separated from the alcohol water solution to obtain the alcohol of the high concentration, the present invention is, needless to say, applied to a case where the particular component from the other mixed liquids (for example, azeotropic mixed liquids, approximate boiling point mixed liquids, and so on) may be separated by the proper selection of the material quality of the selective transmission membrane. (Embodiment 9) Fig. 17 shows a liquid separating apparatus in the embodiment 9 of the present invention. In the case of the liquid separating apparatus of the present embodiment, the first frame 301 constituting the primary chamber 311 and the second frame 302 constituting the secondary chamber 321 are both ring-shaped in the same diameter, with the selective transmission membrane 303 being disc-shaped. The partitioned walls 307, 307 ... which are alternately projected in the vertical direction are formed on the inner wall of the first frame 301, and the tip ends of these partitioned walls 307, 307 ... are confronted in positions away at the given intervals from the opposite inner wall. Namely, even in the present embodiment, as in the embodiment 1, the interior of the primary chamber 311 is partitioned by the partitioned walls 307, 307 ..., with a series of slender flow passage 8 directed from the entrance side (namely, the feed opening 312) to the exit side (namely, the exhaust opening 313) being formed. Within the primary chamber 311 of the first frame 301, there provides a pipe of sheathed wire heater 351 which is passed through between the partitioned walls 307, and is connected with an electric power source (not shown) provided at the outside of the first frame 301 so as to generate a heat for heating the mixed liquid flowing within the primary chamber 311 of the first frame 301. As the other constructions and the operations are similar to those of the embodiment 1, the description will be omitted to avoid the repetition thereof. (Embodiment 10) Fig. 18 shows a liquid separating apparatus in the embodiment 10 of the present invention. In the case of the liquid separating apparatus of the present embodiment, the first frame 301 constituting the primary chamber 311 and the second frame 302 constituting the secondary chamber 321 are ring-shaped as in the embodiment 10 with the selective transmission membrane 303 being disc-shaped. A pair of spiralled-shaped partitioned 307, 307 ... extending along the inner wall shape towards the central portion of the first frame 301 from the inner wall are projected from the inner wall of the first frame 301, with a series of slender flow passage 308 directed from the entrance side (namely, the feed opening 312) to the exit side (namely, the exhaust opening 313) being formed between the partitioned walls 307 and 307. Within the primary chamber 311 of the first frame 301, there provides a pipe 352 for hot water which is passed through between the partitioned walls 307, and is adapted to circulate hot water therein so as to exchange a heat for heating the mixed liquid flowing within the primary chamber 311 of the first frame 301. As the other constructions and the operations are similar to those of the embodiment 1, the description will be omitted to avoid the repetition thereof. In the above-described illustration, although the present embodiment is applied to a case where the water component is separated from the alcohol water solution to obtain the alcohol of the high concentration, the present invention is, needless to say, applied to a case where the particular component from the other mixed liquids (for example, azeotropic mixed liquid, approximate boiling point mixed liquids, and so on) may be separated by the proper selection of the material quality of the selective transmission membrane.

Claims: A liquid separating apparatus comprising a primary chamber (111; 211; 311) on a high pressure side to which a given mixture of liquids containing the liquid to be separated and another liquid is fed, a secondary chamber (113; 221; 321) on a low pressure side which receives the liquid to be separated in vapour form, an amorphous, high molecular selective transmission membrane (107; 203; 303) through which the secondary chamber comes into contact against the primary chamber, for selectively transmitting the liquid to be separated to the secondary chamber, and at least one heating pipe (106; 209; 351) disposed within the primary chamber on the high pressure side to heat the mixture of liquids flowing in the primary chamber from an inlet (104; 212; 312) to an outlet (105; 213; 313) of the primary chamber to compensate for the lost latent heat of evaporation through the phase change of the separated liquid and also to create turbulence in the flowing mixture of liquids. The liquid separating apparatus as defined in claim 1, wherein a plurality of fins (131; 210) are provided on an outer periphery of the at least one heating pipe (106; 209). The liquid separating apparatus as defined in claim 1 or 2, wherein the interior of the primary chamber (211; 307) is partitioned by a plurality of partition walls (207; 307) which are alternately projecting from the mutually opposite inner walls of the primary chamber and are confronted in the positions away at given intervals from the inner walls opposite at the respective tip ends to form a series of flow passages (208; 308) continuous towards the exit side from the entrance side among these partition walls and the at least one heating pipe (209; 351) is disposed within the flow passages. The liquid separating apparatus as defined in claim 3, wherein the flow passage (308) is formed between a pair of partition walls (307) in a spiral shape towards the central portion from the inner walls in the primary chamber (311).

Inventors: IZUTANI NAOAKI, SUGIOKA KAYOKO, WATANABE YUJI, YASUHARA TAKASHI, IZUTANI, NAOAKI, SUGIOKA, KAYOKO, WATANABE, YUJI, YASUHARA, TAKASHI
Applicants: DAIKIN IND LTD, DAIKIN INDUSTRIES, LIMITED
Application year: 1989
Main classification: B01D61
IPC codes: B01D61