JP2011092871A - Organic solvent recovery system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic solvent recovery system which aims an energy saving and can recover an organic solvent from a gas to be treated at high concentrations and in good yield. <P>SOLUTION: The organic solvent recovery system 1A includes: an adsorption-desorption treatment apparatus 100 containing an adsorbent 111, 121 capable of sorbing and desorbing the organic solvent contained in the gas to be treated to discharge a treated gas and a desorption gas by treating the gas to be treated; a condensation-liquid separating apparatus 200 condensing and liquid-separating the desorption gas discharged from the adsorption-desorption treatment apparatus 100 and thereby separating a concentrate containing the organic solvent at high concentrations and separated water to discharge; a membrane-separating apparatus 330 membrane-separating the concentrate discharged from the condensation-liquid separating apparatus 200 based on a pervaporation separation method and separating into a recovery liquid containing the organic solvent at high concentrations and a permeation liquid to discharge; and a heat exchange part 400 carrying out a heat exchange of the desorption gas discharged from the adsorption-desorption treatment apparatus 100 and the concentrate discharged from the condensation-liquid separating apparatus 200 and introduced into the membrane-separating apparatus 330. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic solvent recovery system that recovers the organic solvent from the gas to be treated containing the organic solvent, and in particular, removes and purifies the organic solvent from industrial exhaust gas discharged from various factories, research facilities, etc. The present invention relates to an organic solvent recovery system that purifies and recovers a removed organic solvent.

  Conventionally, there has been known an organic solvent recovery system that removes the organic solvent from the gas to be processed containing the organic solvent, purifies and discharges the gas to be processed, and concentrates and recovers the removed organic solvent to a high concentration. ing. This type of organic solvent recovery system generally contains a high-concentration organic solvent by bringing the gas to be treated into contact with the adsorbent material to adsorb the organic solvent, and blowing high-temperature heating gas onto it to desorb the organic solvent. An adsorption / desorption treatment device that discharges as a desorption gas, and a desorption gas containing a high-concentration organic solvent discharged from the adsorption / desorption treatment device is condensed and separated in a separation tank so that water is a main component. And a condensing / recovering device that collects a liquid containing a high concentration organic solvent as a recovered liquid (for example, (See Japanese Utility Model Publication No. 7-2028 (Patent Document 1), Japanese Utility Model Publication No. 7-2029 (Patent Document 2), Japanese Utility Model Publication No. 7-2030 (Patent Document 3), etc.).

  In the recovery liquid mainly composed of the organic solvent recovered by using the organic solvent recovery system, in addition to the organic solvent, water or organic solvent derived from a heating gas such as water vapor used for desorption treatment is usually used. Decomposed products are included. Therefore, in general, the recovered liquid is separated by performing a distillation treatment in a distillation column using the boiling point difference of each component contained, thereby purifying the organic solvent. In many cases, the recovery liquid containing an organic solvent, water and a trace component dissolved in these is an azeotropic mixture, and the distillation treatment requires an azeotropic distillation operation.

  However, the distillation process using a distillation tower is not preferable as equipment attached to an organic solvent recovery system because it requires not only high capital investment but increases initial cost and also increases the installation area of the equipment. . In addition, the facility requires enormous energy for its operation, which increases running costs and causes air pollution, which is not preferable from the viewpoint of environmental conservation.

  From such a viewpoint, a membrane separation process based on a pervaporation separation method (pervaporation method) has attracted attention as a purification method that replaces the distillation treatment using a distillation column. The pervaporation separation method is a separation method suitable for separation of azeotropic mixtures, and as a separation membrane, a zeolite membrane as an inorganic membrane, a polysulfone membrane as a polymer membrane, a silicon membrane, a polyamide membrane, a polyimide membrane, etc. are generally used. Is used.

  As an organic solvent recovery system provided with a membrane separation apparatus based on such a pervaporation separation method, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-66530 (Patent Document 4). The organic solvent recovery system disclosed in Patent Document 4 has a configuration in which a membrane separation device based on a pervaporation separation method is further added to the downstream side of the condensation recovery device of the conventional organic solvent recovery system described above, The liquid containing the high-concentration organic solvent recovered by the condensation recovery apparatus is further introduced into the membrane separation apparatus based on the pervaporation separation method, and water is further added from the liquid containing the high-concentration organic solvent. By separating and removing the organic solvent, the organic solvent is purified. The organic solvent recovery system is configured to further increase the yield of the organic solvent by returning the permeate mainly containing a large amount of water separated by the membrane separator to the separation tank of the condensation recovery device. ing.

Japanese Utility Model Publication No. 7-2028 Japanese Utility Model Publication No. 7-2029 Japanese Utility Model Publication No. 7-2030 JP 2009-66530 A

  However, the organic solvent recovery system as disclosed in Patent Document 4 requires less energy than the case of using a distillation column, but is a facility in which a membrane separator is attached to the organic solvent recovery system. For some reason, it is inevitable that the power source (for example, heat source, drive source, etc.) required for transporting the treatment liquid etc. via the piping line while controlling the temperature will be increased. It is inevitable that the energy of the vehicle increases and the running cost increases.

  Therefore, the present invention has been made to solve the above-described problems, and when recovering the organic solvent from the gas to be treated containing the organic solvent, the organic solvent can be recovered at a high concentration and in a high yield. An object of the present invention is to provide an organic solvent recovery system that saves energy.

  An organic solvent recovery system based on the present invention is an organic solvent recovery system for recovering an organic solvent from a gas to be treated containing an organic solvent, and an adsorption / desorption treatment device, a condensate separation device, a membrane separation device, A heat exchange part is provided. The adsorption / desorption treatment apparatus includes an adsorption element that adsorbs an organic solvent by contacting a gas to be treated and desorbs the adsorbed organic solvent by contacting a heated gas, and supplies the gas to be treated to the adsorption element. Then, the organic solvent is adsorbed on the adsorption element and discharged as a processing gas. By supplying a heating gas to the adsorption element, the organic solvent is desorbed from the adsorption element and discharged as a desorption gas containing the organic solvent. Is. The condensing / separating apparatus condenses by cooling the desorption gas discharged from the adsorption / desorption treatment apparatus, and separates the condensed liquid based on the difference in specific gravity, thereby concentrating liquid and water containing an organic solvent. Is separated into a separation liquid containing as a main component. The membrane separation device includes a separation membrane that selectively permeates and separates water contained in the concentrate or water mixed with acid by contacting the concentrate, and the concentration discharged from the condensate separator. By supplying a liquid to the said separation membrane, it isolate | separates into the collection | recovery liquid which contains an organic solvent in high concentration, and the permeation | transmission liquid which has water as a main component. The heat exchange unit exchanges heat between the desorption gas discharged from the adsorption / desorption treatment device and the concentrated liquid discharged from the condensation / separation device and introduced into the membrane separation device.

  In the organic solvent recovery system according to the present invention, the adsorbing element is preferably an activated carbon fiber.

  In the organic solvent recovery system according to the present invention, the heating gas is preferably water vapor.

  In the organic solvent recovery system according to the present invention, the membrane separation device is preferably based on a pervaporation separation method.

  In the organic solvent recovery system according to the present invention, the separation membrane is preferably a carbon membrane.

  In the organic solvent recovery system according to the present invention, the separation membrane preferably has a hollow fiber structure.

  The organic solvent recovery system according to the present invention is particularly preferably used when the gas to be treated contains an acid.

  The organic solvent recovery system based on the present invention is particularly preferably used when the gas to be treated contains a component that generates an acid by reacting with water as an organic solvent. Here, examples of the component that generates an acid by reacting with water include an acetate ester and a basic compound.

  According to the present invention, when recovering the organic solvent from the gas to be treated containing the organic solvent, an organic solvent recovery system capable of recovering the organic solvent in high concentration and high yield can be provided. it can.

It is a system configuration figure of an organic solvent recovery system in an embodiment of the invention. It is a schematic cross section of the membrane separator of the organic solvent collection | recovery system in embodiment of this invention. It is a system block diagram of the organic solvent collection | recovery system which concerns on a comparative example. It is a table | surface which shows the result of a verification test.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the same or corresponding parts are denoted by the same reference numerals in the drawings, and description thereof will not be repeated.

  FIG. 1 is a system configuration diagram of an organic solvent recovery system according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the membrane separation apparatus shown in FIG. First, with reference to these FIG. 1 and FIG. 2, the structure of the organic solvent collection | recovery system in this Embodiment is demonstrated.

  As shown in FIG. 1, the organic solvent recovery system 1A in the present embodiment includes an adsorption / desorption processing device 100, a condensing / separating device 200, a separation / recovery device 300 including a membrane separation device 330, a heat exchanging unit 400, It has. The organic solvent recovery system 1A in the present embodiment treats the gas to be treated by removing the organic solvent from the gas to be treated containing the organic solvent, and purifies and recovers the removed organic solvent. . The gas to be treated containing the organic solvent to be treated includes an acid-containing gas, an acid-free gas, an acid-free component that reacts with water as an organic solvent (for example, acetate ester, And those containing a basic compound).

  The adsorption / desorption treatment apparatus 100 includes a first treatment tank 110 and a second treatment tank 120 in which adsorbents 111 and 121 as adsorption elements are accommodated, respectively. The adsorbents 111 and 121 adsorb the organic solvent contained in the gas to be processed by contacting the gas to be processed. Therefore, in the adsorption / desorption processing apparatus 100, the organic solvent is adsorbed by the adsorbents 111 and 121 by supplying the gas to be treated to the adsorbents 111 and 121, whereby the gas to be treated is cleaned and discharged as the process gas. Will be. The adsorbents 111 and 121 desorb the adsorbed organic solvent by bringing water vapor as a heating gas into contact therewith. Therefore, in the adsorption / desorption processing apparatus 100, by supplying water vapor to the adsorbents 111 and 121, the organic solvent is desorbed from the adsorbents 111 and 121, whereby the water vapor is discharged as a desorption gas containing the organic solvent. become. Note that as the heated gas introduced into the adsorption / desorption treatment apparatus 100 for desorption of the organic solvent, a high-temperature inert gas or the like can be used in addition to water vapor.

  Piping lines L1, L2, L3, and L4 are connected to the first processing tank 110 and the second processing tank 120, respectively. The piping line L1 is a piping line for supplying a gas to be processed containing an organic solvent to the first processing tank 110 and the second processing tank 120, and the first processing tank 110 and the second processing tank by valves V101 and V102. The connection / disconnection state for 120 is switched. The piping line L2 is a piping line for supplying water vapor to the first processing tank 110 and the second processing tank 120, and is connected / disconnected to the first processing tank 110 and the second processing tank 120 by valves V103 and V104. Is switched. The piping line L3 is a piping for discharging the processing gas from the first processing tank 110 and the second processing tank 120, and is connected / disconnected to the first processing tank 110 and the second processing tank 120 by valves V105 and V106. Is switched. The piping line L4 is a piping line for discharging desorption gas from the first processing tank 110 and the second processing tank 120, and is connected / disconnected to the first processing tank 110 and the second processing tank 120 by valves V101 and V102. The state is switched.

  The first treatment tank 110 and the second treatment tank 120 function alternately as an adsorption tank and a desorption tank by operating the above-described opening and closing of the valves V101 to V106. Specifically, the first treatment tank 110 is adsorbed. When functioning as a tank, the second processing tank 120 functions as a desorption tank, and when the first processing tank 110 functions as a desorption tank, the second processing tank 120 functions as an adsorption tank. . That is, the adsorption / desorption processing apparatus 100 according to the present embodiment is configured such that the adsorption tank and the desorption tank are alternately switched over time. The piping line L1 is connected to a tank functioning as an adsorption tank among the first processing tank 110 and the second processing tank 120 and supplies a gas to be processed to the adsorption tank. Among the 1 treatment tank 110 and the 2nd treatment tank 120, it connects with the tank which is functioning as a desorption tank, and supplies water vapor | steam to the said desorption tank. The piping line L3 is connected to a tank functioning as an adsorption tank among the first processing tank 110 and the second processing tank 120 and discharges the processing gas from the adsorption tank. The piping line L4 is connected to the first processing tank 110 and the second processing tank 120. The processing tank 110 and the second processing tank 120 are connected to a tank functioning as a desorption tank and discharge the desorption gas.

  The adsorbents 111 and 121 are made of a member containing at least one of activated carbon, activated carbon fiber, and zeolite. Preferably, the adsorbents 111 and 121 are activated carbon or zeolite in the form of particles, granules or honeycombs, but more preferably activated carbon fibers. Since the activated carbon fiber has a fibrous structure having micropores on the surface, the activated carbon fiber has high contact efficiency with gas and is a member that can realize high adsorption efficiency as compared with other adsorption elements.

  The condensing and separating apparatus 200 includes a condenser 210 and a separation tank 220. The condenser 210 is an apparatus that condenses and liquefies the desorption gas discharged from the adsorption / desorption treatment apparatus 100 using cooling water or the like, and the separation tank 220 divides the liquid obtained by liquefying the desorption gas with a specific gravity difference. Is separated into a concentrated liquid containing an organic solvent at a high concentration and a separating liquid containing water as a main component.

  The condenser 210 is connected to the piping lines L4 and L5, and the separation tank 220 is connected to the piping lines L5, L6 and L7, respectively. The piping line L4 is a piping line for supplying the desorption gas discharged from the above-described adsorption / desorption processing apparatus 100 to the condenser 210, and the piping line L5 supplies the liquid obtained in the condenser 210 to the separation tank 220. It is a piping line for supplying. The piping line L6 is a piping line for discharging the separation liquid separated in the separation tank 220 from the separation tank 220, and the piping line L7 is for discharging the concentrated liquid separated in the separation tank 220 from the separation tank 220. It is a piping line to do. Note that a valve V107 is provided in the piping line L7, and the valve V107 switches a connection / disconnection state between the separation tank 220 and a buffer tank 310 described later via the piping line L7.

  The separation / recovery device 300 includes a buffer tank 310, a heater 320, a membrane separation device 330, a condenser 340, and a recovery tank 350. The buffer tank 310 is a tank for temporarily storing the concentrated liquid discharged from the condensing / separating apparatus 200, and the heater 320 needs the concentrated liquid discharged from the buffer tank 310 using high-temperature steam or the like. It is an apparatus for heating according to. The membrane separation device 330 is a device that selectively permeates and separates moisture contained in the concentrate or moisture mixed with an acid based on a so-called pervaporation separation method. The condenser 340 is a device for condensing the permeated component discharged from the membrane separation device 330 using cooling water or the like and discharging it as a permeate, and the recovery tank 350 is a high-pressure device discharged from the membrane separation device 330. It is a tank for storing a liquid containing an organic solvent having a concentration as a recovered liquid.

  The buffer tank 310 is connected to the piping lines L7, L8, and L13, and the heater 320 is provided in the middle of the piping line L8. The membrane separator 330 is connected to the piping lines L8, L9, L11, and L13, respectively. The condenser 340 is connected to the piping lines L9 and L10, respectively, and the recovery tank 350 is connected to the piping lines L11 and L12.

  The piping line L7 is a piping line for supplying the concentrated liquid discharged from the condensing / separating apparatus 200 to the buffer tank 310, and the piping line L8 is a membrane separating apparatus for concentrating the liquid stored in the buffer tank 310. This is a piping line for supplying to 330. The piping line L9 is a piping line for supplying the permeated component separated and discharged by the membrane separator 330 to the condenser 340, and the piping line L10 is a permeation obtained by condensing in the condenser 340. It is a piping line for discharging the liquid from the condenser 340. The piping line L11 is a piping line for supplying the recovered liquid separated and discharged by the membrane separation device 330 to the recovery tank 350, and the piping line L12 is configured to supply the recovered liquid stored in the recovery tank 350 to the outside. It is a piping line for discharging. The piping line L <b> 13 is a piping line for returning the non-permeated liquid separated and discharged by the membrane separation device 330 to the buffer tank 310. In addition, the valve V108 is provided in the piping line L11, and the valve V108 switches the connection / disconnection state between the membrane separation device 330 and the recovery tank 350 via the piping line L11. In addition, a valve V109 is provided in the piping line L13, and the valve V109 switches a connection / disconnection state between the membrane separation device 330 and the buffer tank 310 via the piping line L13. The membrane separation device 330 may be constituted by a single unit as shown in the figure, but may be constituted by arranging a plurality of units in parallel or in series.

  As shown in FIG. 2, the membrane separation device 330 is connected so as to communicate with a shell 331 serving as an outer shell, an inner hollow separation membrane 332 accommodated in the shell 331, and an inner hollow of the separation membrane 332. The suction pipe 334 is mainly provided. Here, the separation membrane 332 is a membrane that selectively permeates moisture contained in the concentrate or moisture mixed with the acid by contacting the concentrate to separate it from other components contained in the concentrate. .

  The shell 331 is connected to the piping line L8 and connected to the inlet 335 for introducing the concentrated liquid discharged from the condensing and separating apparatus 200 into the shell 331 and the piping lines L11 and L13. It has an outlet 336 for leading the concentrated liquid after passing through the inside of the shell 331 from the shell 331 as a non-permeate liquid or a recovered liquid. One end of the separation membrane 332 is supported by the support member 333 a and the other end is supported by the support member 333 b and connected to the suction pipe 334. The suction pipe 334 is connected to a vacuum pump and a condenser 340 (not shown) by being connected to the piping line L9.

  Here, as the separation membrane 332, for example, various inorganic membranes and polymer membranes can be used, and a carbon membrane is particularly preferably used. This is because the concentrated liquid is a relatively high-temperature liquid and there is a possibility that the concentrated liquid may contain a small amount of acid. By using a carbon film having excellent heat resistance, acid resistance, etc. This is because the lifetime of the membrane separation device 330 is increased. For example, when a polymer membrane is used as the separation membrane 332, since the treatment target is a liquid, the polymer membrane swells to cause deformation, and there is a concern that the membrane may be damaged or leaked. It ’s hard to be. In addition, when a zeolite membrane that is an inorganic membrane is used as the separation membrane 332, there is a concern that the concentrated liquid to be treated may contain an acid, so that the structure may be destroyed by touching the acid, It is hard to be preferable.

  Even when a carbon membrane is used as the separation membrane 332, an acid may be generated due to a reaction with moisture in the membrane separation device 330 due to the metal contained in the carbon membrane. Therefore, it is preferable to suppress the generation of acid by appropriately adjusting the metal species and amount in the carbon film. Specifically, by selection of raw materials and adjustment of carbon film manufacturing conditions, F, P, S, Cl, K, Ca, Cr, Fe, Zn, Na, Mg, Cu, Co, Mn, Ni, etc. It is preferable to suppress each content to 500 ppm or less. Furthermore, it is also possible to reduce the amount of metal in the carbon film by washing the metal in the carbon film with an inorganic acid such as hydrochloric acid, for example, during the manufacturing process or post-treatment of the carbon film.

  The separation membrane 332 preferably has a hollow fiber structure. This makes it possible to increase the surface area per unit volume of the separation membrane by using the separation membrane 332 having a hollow fiber structure as compared with the case of using a separation membrane having another tube structure or the like. This is because the separation performance of the membrane separation device 330 can be increased. As a result, the membrane separation device 330 can be reduced in size, cost, and energy saving.

  Examples of the raw material for the carbon membrane having a hollow fiber structure include acrylic resins, polyimide resins, cellulose resins, polyphenylene oxide resins, polyfurfuryl alcohol, and phenol resins, but the raw materials are particularly limited. It is not a thing.

  The above-mentioned carbon membrane having a hollow fiber structure is obtained by processing the above-mentioned resin raw material or the like into a hollow shape and further heat-treating it in an inert atmosphere. The heat treatment temperature is equal to or higher than the thermal decomposition start temperature of the resin, and is generally 250 ° C. or higher. Since the heat treatment temperature in the inert atmosphere is directly related to the performance of membrane separation, an optimum temperature can be selected. However, if the temperature is too high, the pores of the carbon film are blocked by heat shrinkage, so the upper limit is desirably up to about 1300 ° C.

  In addition, before heat treatment in an inert atmosphere, heat treatment in air (also referred to as flame resistance, infusibilization, or thermal stabilization) or a flame retardant can be imparted to the resin. Further, after heat treatment in an inert atmosphere, chemical treatment or surface treatment such as heat treatment may be added. The carbon film is composed of elements such as carbon, hydrogen, oxygen, nitrogen, sulfur, and the above-described metal components, the main component is carbon, and the content is 60% or more. The upper limit of the carbon content is not particularly limited, but about 99.9% is a practical upper limit.

  The heat exchanging unit 400 is configured by bringing the piping line L4 and the piping line L7 into thermal contact. Specifically, the heat exchanging unit 400 is a part that applies latent heat and sensible heat of the desorption gas that passes through the piping line L4 by exchanging heat to the concentrate that passes through the piping line L7, and the heat exchanger is It is composed by using. Here, as a usable heat exchanger, those having various configurations can be used. For example, a heat exchanger using a meandering tube, a straight tube, a finned tube, or the like can be used.

  Next, the details of the processing performed in the organic solvent recovery system 1A in the present embodiment will be described with reference to FIG. The following description is based on the state in which the first treatment tank 110 of the adsorption / desorption treatment apparatus 100 functions as an adsorption tank and the second treatment tank 120 functions as a desorption tank. The same process is also performed when the desorption tank is replaced.

  As shown in FIG. 1, the gas to be treated is introduced into the adsorption / desorption treatment apparatus 100 via a piping line L1. The introduced gas to be treated is sent to the first treatment tank 110 and comes into contact with the adsorbent 111, and the organic solvent contained in the gas to be treated is adsorbed by the adsorbent 111. The gas after the organic solvent is adsorbed by the adsorbent 111 is introduced into the piping line L3 and discharged from the adsorption / desorption processing apparatus 100 as a processing gas.

  On the other hand, water vapor is introduced into the adsorption / desorption treatment apparatus 100 via the piping line L2 in parallel with the introduction of the gas to be treated. The introduced water vapor is sent to the second treatment tank 120 and comes into contact with the adsorbent 121 to desorb the organic solvent adsorbed on the adsorbent 121. The water vapor containing the organic solvent desorbed from the adsorbent 121 is introduced into the piping line L4 and discharged from the adsorption / desorption processing apparatus 100 as a desorption gas. Here, the temperature of the desorption gas discharged from the adsorption / desorption treatment apparatus 100 is about ˜110 ° C.

  The desorption gas discharged from the adsorption / desorption processing apparatus 100 is sent to the condensing / separating apparatus 200 via the piping line L4. At that time, the desorption gas is cooled to a predetermined temperature by exchanging heat with the concentrate in the heat exchanging unit 400. The desorption gas cooled in the heat exchanging unit 400 and sent to the condensing / separating apparatus 200 is condensed by being introduced into the condenser 210 and cooled, and the condensed liquid passes through the piping line L5. It is sent to the separation tank 220. The liquid introduced into the separation tank 220 is separated in the separation tank 220 based on the specific gravity difference, and separated into a concentrated liquid containing an organic solvent at a high concentration and a separation liquid containing water as a main component. The separation liquid mainly composed of water is introduced into the piping line L6 and discharged from the condensing / separating apparatus 200, and the concentrated liquid containing the organic solvent at a high concentration is introduced into the piping line L7 by opening the valve V107. And discharged from the condensate / separation apparatus 200. Here, the temperature of the concentrated liquid discharged from the condensing and separating apparatus 200 is approximately 30 ° C. to 40 ° C.

  The concentrated liquid discharged from the condensing / separating apparatus 200 is sent to the separation and recovery apparatus 300 via the piping line L7. At that time, the concentrated liquid is heated to a predetermined temperature by exchanging heat with the desorption gas in the heat exchanging section 400. The concentrated liquid heated in the heat exchanging section 400 and sent to the separation / recovery device 300 is temporarily stored in the buffer tank 310, and then introduced into the piping line L8 and heated by the heater 320 as required to be predetermined. The temperature is raised to a temperature of 1 and introduced into the membrane separator 330. Here, the reason why the concentrated liquid introduced into the membrane separation device 330 is heated to a predetermined temperature is to increase the separation performance of the membrane separation process in the membrane separation device 330 described later, and thereby the membrane can be efficiently formed. Separation processing is performed. The temperature of the concentrated liquid introduced into the membrane separation device 330 is generally about 50 ° C. to 130 ° C., although it depends on the components and composition of the organic solvent contained.

  In the membrane separator 330, the concentrate is introduced from the piping line L 8 through the inlet 335 provided in the shell 331, and the introduced concentrate contacts the separation membrane 332 when passing through the inside of the shell 331. To do. At this time, moisture contained in the concentrate or moisture mixed with acid permeates through the separation membrane 332 by the action of a vacuum pump (not shown) and is introduced into the hollow interior of the separation membrane 332, and further, the suction pipe is obtained by the action of the vacuum pump. It is discharged to the outside of the membrane separation device 330 via 334. The permeated component discharged from the membrane separation device 330 is supplied to the condenser 340 via the piping line L9, and is condensed by being cooled by the condenser 340, and becomes a permeated liquid, via the piping line L10. Discharged. On the other hand, the non-permeated liquid after passing through the inside of the shell 331 is discharged from the outlet 336 provided in the shell 331, is introduced into the piping line L13 by opening the valve V109, and is discharged from the membrane separator 330. The The non-permeated liquid discharged from the membrane separation device 330 is returned to the buffer tank 310 via the piping line L13.

  In the separation and recovery apparatus 300, the above-described operation is continued for a predetermined time. As a result, impurities other than the organic solvent are gradually separated and removed by the membrane separator 330 from the concentrated liquid temporarily stored in the buffer tank 310. Then, after a predetermined time has elapsed, the valve V109 is closed, and instead the valve V108 is opened, so that the concentrated liquid discharged from the outlet 336 provided in the shell 331 is introduced into the piping line L11 and collected. The liquid is discharged from the membrane separation device 330 and stored in the recovery tank 350. Thereafter, the recovered liquid stored in the recovery tank 350 is discharged to the outside of the organic solvent recovery system 1A via the piping line L12 when a predetermined amount is stored.

  By adopting the organic solvent recovery system 1A in the present embodiment described above, the desorption gas discharged from the adsorption / desorption treatment apparatus 100 and introduced into the condensing / separating apparatus 200 and the desorbing gas discharged from the condensing / separating apparatus 200 are discharged. The concentrated liquid before being introduced into the membrane separation device 330 can be heat-exchanged in the heat exchanging unit 400, and energy required for the operation of the organic solvent recovery system 1A can be saved. Specifically, by performing the heat exchange, energy required for condensing the desorption gas in the condensing / separating apparatus 200 (for example, energy required for adjusting the temperature of the cooling water, energy required for transporting the cooling water, etc.) ) And the energy (for example, high-temperature water vapor) required to raise the concentrate to a predetermined temperature in order to efficiently perform membrane separation of the concentrate in the membrane separator 330. The amount of energy required for temperature adjustment, energy required for transporting high-temperature steam, etc.) can be reduced. Therefore, by using the organic solvent recovery system 1A in the present embodiment described above, an organic solvent recovery system that can recover the organic solvent at a high concentration and high yield and that has a low running cost can be obtained.

  In the following, the verification test conducted to verify the effect of the present invention will be described in detail. In this verification test, the organic solvent recovery system 1A in the present embodiment described above as an example is prototyped, and the amount of energy used when the organic solvent is recovered using the system is measured, and as a comparative example The above-described conventional organic solvent recovery system was manufactured, and the amount of energy used when the organic solvent was recovered using the system was measured, and the effect of the present invention was verified by comparing these measured values.

  FIG. 3 is a system configuration diagram of the organic solvent recovery system according to the comparative example, and FIG. 4 is a table showing the results of the verification test. In the following, first, the configuration of the organic solvent recovery system according to the comparative example will be described in detail with reference to FIG. 3, and then the result of the verification test will be described with reference to FIG.

  The organic solvent recovery system 1B according to the comparative example is different from the organic solvent recovery system according to the embodiment (organic solvent recovery system 1A shown in FIG. 1) only in the presence or absence of the heat exchange unit 400. That is, in the organic solvent recovery system 1B according to the comparative example, heat exchange is not performed between the desorption gas passing through the piping line L4 and the concentrated liquid passing through the piping line L7, and cooling of the desorption gas is performed by the condenser 210. Only the cooling is performed, and the concentrated liquid is heated only by the heating by the heater 320.

In this verification test, a gas to be treated at 40 ° C. containing ethyl acetate at a concentration of 2000 ppm was used as the organic solvent, and this was applied to the organic solvent recovery system 1A according to the example and the organic solvent recovery system 1B according to the comparative example, respectively. Processing was performed by introducing. Here, the same adsorption / desorption treatment apparatus 100 is used in any organic solvent recovery system, and the adsorbents 111 and 121 have an average pore diameter of 17.4 mm, a BET specific surface area of 1650 m ² / g, Activated carbon fibers having a pore volume of 0.66 cm ³ / g were used.

First, the gas to be treated is adsorbed by blowing air for 9 minutes at a flow rate of 100 Nm ³ / min to one treatment tank of the adsorption / desorption treatment apparatus 100 using a blower (not shown), and the gas to be treated is cleaned and treated. It was discharged as gas. In this case, the concentration of ethyl acetate contained in the processing gas discharged from the adsorption / desorption processing apparatus 100 is 20 ppm in both the organic solvent recovery system 1A according to the example and the organic solvent recovery system 1B according to the comparative example. It was confirmed that the ethyl acetate was removed by the adsorption / desorption treatment apparatus 100 at a removal rate of 99%.

  After the above-mentioned 9 minutes of blowing, the valves V101 to V106 were switched to switch the one processing tank to the desorption tank, and the remaining processing tank was used as an adsorption tank. In the desorption tank, the adsorbent was desorbed by introducing water vapor, and in the adsorption tank, the adsorption process was performed under the same conditions as described above. This operation of adsorption treatment and desorption treatment was repeated alternately in each treatment tank.

  In the organic solvent recovery system 1A according to the embodiment, the desorption gas discharged at 100 ° C. from the desorption tank of the adsorption / desorption treatment apparatus 100 described above is introduced into the condensate / separation apparatus 200 via the heat exchange unit 400, and 30 Cooling in the condenser 210 using cooling water at 0 ° C., followed by liquid separation in the separation tank 220, thereby obtaining a concentrated liquid containing high-concentration ethyl acetate and a separated liquid mainly composed of water. . Subsequently, the concentrated liquid discharged from the condensing and separating apparatus 200 is introduced into the separation and recovery apparatus 300 via the heat exchange unit 400, temporarily stored in the buffer tank 310, and then the concentrated liquid is removed using the heater 320. The mixture was heated to 75 ° C. and introduced into a membrane separation apparatus 330 having a carbon membrane having a hollow fiber structure as the separation membrane 332, and membrane separation treatment was performed. At this time, the permeated component separated by the membrane separator 330 is condensed by the condenser 340 and discharged as a permeated liquid, and the non-permeated liquid is returned to the buffer tank 310. After a predetermined time, the non-permeate discharged from the membrane separator 330 was introduced into the recovery tank 350 as a recovery liquid.

  In the said Example, it was confirmed that the ethyl acetate density | concentration of the concentrate separated in the separation tank 220 is 96.5 wt%, and the quantity is 60 kg / hr. Further, it was also confirmed that the concentration of ethyl acetate in the recovered liquid separated and purified by the membrane separator 330 was 99.9 wt%, and the concentration of water in the recovered liquid was 0.1 wt%. This result can be said to be a sufficiently high concentration and high yield as the concentration and yield of the recovered liquid obtained by recovering the organic solvent from the gas to be treated.

Here, as shown in FIG. 4, in the above embodiment, the temperature of the desorption gas at the inlet of the condensate separator 200 (here, strictly speaking, the desorption gas is liquefied) is 70 ° C. As well as being confirmed, it was confirmed that the temperature of the concentrated liquid at the inlet of the separation and recovery apparatus 300 was stable at 70 ° C. This result shows that the desorption gas and the concentrate are sufficiently exchanging heat in the heat exchanging section 400. That is, in the embodiment, it means that the desorption gas only needs to be slightly lowered in the condenser 210, and the temperature of the concentrate needs only to be slightly raised in the heater 320. In addition, as shown in FIG. 4, the utility usage-amount in an Example was confirmed by actual measurement that it is 9 m < ³ > / hr about cooling water, and is 4 m < ³ > / hr about water vapor | steam.

  On the other hand, in the organic solvent recovery system 1B according to the comparative example, the desorption gas discharged at 100 ° C. from the desorption tank of the adsorption / desorption treatment apparatus 100 described above is directly introduced into the condensing / separating apparatus 200, and cooling water at 30 ° C. is supplied. The resulting mixture was cooled in the condenser 210 and then separated in the separation tank 220 to obtain a concentrated liquid containing high-concentration ethyl acetate and a separated liquid mainly composed of water. Subsequently, the concentrated liquid discharged from the condensing and separating apparatus 200 is directly introduced into the separation and recovery apparatus 300, temporarily stored in the buffer tank 310, and then the concentrated liquid is heated to 75 ° C. using the heater 320, The separation membrane 332 was introduced into a membrane separation apparatus 330 having a carbon membrane having a hollow fiber structure, and membrane separation treatment was performed. At this time, the permeated component separated by the membrane separator 330 is condensed by the condenser 340 and discharged as a permeated liquid, and the non-permeated liquid is returned to the buffer tank 310. After a predetermined time, the non-permeate discharged from the membrane separator 330 was introduced into the recovery tank 350 as a recovery liquid.

  In the comparative example, it was confirmed that the concentration of the ethyl acetate in the concentrated liquid separated in the separation tank 220 was 96.5 wt%, and the amount was 60 kg / hr. Further, it was also confirmed that the concentration of ethyl acetate in the recovered liquid separated and purified by the membrane separator 330 was 99.9 wt%, and the concentration of water in the recovered liquid was 0.1 wt%. This result can be said to be a sufficiently high concentration and high yield as the concentration and yield of the recovered liquid obtained by recovering the organic solvent from the gas to be treated.

However, as shown in FIG. 4, in the comparative example, it is confirmed that the temperature of the desorption gas at the inlet of the condensate separator 200 is 100 ° C., and the concentrated liquid at the inlet of the separation and recovery device 300. It was confirmed that the temperature was stable at 39 ° C. This result shows that the required energy is increased as compared with the example because no heat exchange part is provided as in the example. That is, in the comparative example, it is necessary to greatly decrease the temperature of the desorbed gas in the condenser 210, and it is necessary to increase the temperature of the concentrate in the heater 320. As shown in FIG. 4, the utility usage amount in the comparative example was confirmed to be 26 m ³ / hr for cooling water and 28 m ³ / hr for water vapor. This value is about 3.5 times that of the example for the amount of cooling water used, and 7 times that of the example for the amount of water vapor used, indicating that a very large amount of energy was required compared to the example. Yes.

  From the results of the verification test described above, the organic solvent recovery system 1A as in the present embodiment described above can save energy significantly compared to the conventional case, and the running cost for operating the equipment. It was confirmed that can be reduced.

  In the organic solvent recovery system 1A according to the present embodiment described above, the description has been made without necessarily showing all the components such as the fluid transfer means such as the pump and the fan and the fluid storage means such as the storage tank. What is necessary is just to arrange | position a component in an appropriate position as needed.

  Further, in the organic solvent recovery system 1A in the present embodiment described above, the case where the heater 320 is provided in the separation / recovery device 300 has been described as an example. However, the membrane separation device 330 efficiently performs the membrane separation. If the concentrated liquid can be heated by the heat exchanging unit 400 to such a temperature that can be performed, it is not necessary to provide the heater 320 in the separation and recovery device 300.

  Further, in the organic solvent recovery system 1A in the present embodiment described above, a pipe that connects the separation tank 220 and the buffer tank 310 of the condensate / separation apparatus 200 with the heat exchange unit 400 that makes the desorption gas and the concentrated liquid in thermal contact with each other. The case where it is provided in the middle of the line L7 has been described as an example, but the heat exchanging unit 400 may be provided in the buffer tank 310, or a piping line that connects the buffer tank 310 and the membrane separation device 330. It may be provided at L8.

  Moreover, in the organic solvent collection | recovery system 1A in this Embodiment mentioned above, as the adsorption / desorption processing apparatus 100, two treatment tanks in which the adsorbent is accommodated are provided, and these adsorption tanks and desorption tanks alternately with time. However, if it is not always necessary to process the gas to be processed, the adsorption / desorption process is performed. You may comprise the apparatus 100 with what comprised the single processing tank. Further, when it is necessary to continuously process the gas to be treated, a part of the adsorbent is used as an adsorption treatment zone instead of the above-described switching type adsorption / desorption treatment apparatus 100, and the remaining portion of the adsorbent is used. Is used as a desorption treatment zone, and an adsorption / desorption treatment device equipped with a rotary adsorbent configured such that the adsorption treatment zone and the desorption treatment zone gradually move as the adsorbent rotates. Also good.

  Thus, the one embodiment disclosed this time is illustrative in all respects and is not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1A Organic solvent recovery system, 100 Adsorption / desorption treatment device, 110 First treatment tank, 111 Adsorbent, 120 Second treatment tank, 121 Adsorbent, 200 Condensation separator, 210 Condenser, 220 Separation tank, 300 Separation / recovery device , 310 buffer tank, 320 heater, 330 membrane separator, 331 shell, 332 separation membrane, 333a, 333b support member, 334 suction pipe, 335 inlet, 336 outlet, 340 condenser, 350 recovery tank, 400 heat exchanger , L1-L13 piping line, V101-V109 valve.

Claims (9)

An organic solvent recovery system for recovering the organic solvent from the gas to be treated containing the organic solvent,
It includes an adsorbing element that adsorbs an organic solvent by contacting a gas to be treated, and desorbs the adsorbed organic solvent by bringing a heated gas into contact with the organic solvent. An adsorption / desorption treatment apparatus that adsorbs the adsorption element and discharges it as a processing gas, and supplies a heating gas to the adsorption element to desorb the organic solvent from the adsorption element and discharge it as a desorption gas containing the organic solvent;
The desorption gas discharged from the adsorption / desorption treatment device is condensed by cooling, and the condensed liquid containing the organic solvent and the separation liquid mainly composed of water are separated by separating the condensed liquid based on the specific gravity difference. A condensate separator that separates into
A separation membrane that selectively permeates and separates water contained in the concentrate or water mixed with an acid by contacting the concentrate, and the concentrate discharged from the condensate separator is applied to the separation membrane. A membrane separation device that separates a recovered liquid containing an organic solvent at a high concentration and a permeated liquid containing water as a main component by supplying;
An organic solvent recovery system comprising: a heat exchanging unit for exchanging heat between the desorption gas discharged from the adsorption / desorption treatment device and the concentrated liquid discharged from the condensate separator and introduced into the membrane separation device.   The organic solvent recovery system according to claim 1, wherein the adsorption element is activated carbon fiber.   The organic solvent recovery system according to claim 1, wherein the heated gas is water vapor.   The organic solvent recovery system according to any one of claims 1 to 3, wherein the membrane separation device is based on a pervaporation separation method.   The organic solvent recovery system according to any one of claims 1 to 4, wherein the separation membrane is a carbon membrane.   The organic solvent recovery system according to claim 1, wherein the separation membrane has a hollow fiber structure.   The organic solvent recovery system according to claim 1, wherein the gas to be treated contains an acid.   The organic solvent recovery system according to any one of claims 1 to 7, wherein the gas to be treated includes a component that generates an acid by reacting with water as an organic solvent.   The organic solvent recovery system according to claim 8, wherein the component is an acetate ester or a basic compound.

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