Organic Solvent Recovery System

Abstract

This organic solvent recovery system comprises: a circulation path for circulating a carrier gas; an adsorption / desorption processing device including an adsorption / desorption element for adsorbing an organic solvent contained in a treated gas from an introduction channel; a condensation recovery device that condenses the organic solvent in the carrier gas; a heating unit for heating the carrier gas; a cooling channel that introduces a portion of the treated gas flowing through the introduction channel, so as to cool the adsorption / desorption element; and a return channel that returns, to the introduction channel, the treated gas used to cool the adsorption / desorption element. The adsorption / desorption processing device performs adsorption with the adsorption / desorption element by introducing the treated gas from the introduction channel, and then performs desorption by introducing the heated carrier gas, and thereafter, cools the adsorption / desorption element by introducing the treated gas from the cooling channel. The device then performs adsorption again by introducing the treated gas from the introduction channel. The condensation recovery device includes a melting unit that temporarily heats and thereby melts a component that has been frozen by cooling the carrier gas.

Description

[Technical Field]

[0001] The present invention relates to an organic solvent recovery system that separates an organic solvent from a gas to be treated that contains the organic solvent and recovers the separated organic solvent using a carrier gas. [Background technology]

[0002] Conventionally, an organic solvent-containing gas treatment system has been known that uses an adsorbent to adsorb and desorb the organic solvent from the treated gas containing the organic solvent, thereby transferring the organic solvent from the treated gas to a carrier gas, thereby purifying the treated gas and recovering the organic solvent.

[0003] This type of organic solvent recovery system generally includes an adsorption / desorption treatment device that brings an organic solvent-containing gas to be treated and a high-temperature carrier gas into contact with an adsorbent alternately over time, and a condensation recovery device that cools the carrier gas discharged from the adsorption / desorption treatment device to condense and recover the organic solvent. As one such organic solvent recovery system, Patent Document 1 discloses an organic solvent-containing gas treatment system that uses water vapor as a carrier gas.

[0004] Recently, there has been a demand for organic solvent recovery systems with low wastewater volumes, with the aim of improving the quality of recovered organic solvents and simplifying wastewater treatment processes, and Patent Document 2 discloses an organic solvent recovery system that uses an inert gas heated to a high temperature as a carrier gas. Patent Document 3 also discloses an organic solvent recovery system that uses an inert gas heated to a high temperature as a carrier gas and circulates the inert gas within the organic solvent recovery system, thereby reducing the amount of inert gas used. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Publication No. 3-32924 [Patent Document 2] Japanese Patent Publication No. 7-68127 [Patent Document 3] Japanese Patent No. 5482776 Summary of the Invention [Problem to be solved by the invention]

[0006] In such an organic solvent recovery system, in order to improve the purification capacity for the gas to be treated and the recovery efficiency of the organic solvent, it is necessary to sufficiently desorb the organic solvent in the desorption process, i.e., to regenerate the adsorbent. In addition, in order to reduce the running costs of the organic solvent recovery system, it is preferable to configure the organic solvent recovery system so that the used carrier gas is circulated within the organic solvent recovery system and reused.

[0007] However, it is difficult to completely separate the organic solvent from the carrier gas in the condensation recovery device. Therefore, the carrier gas discharged from the condensation recovery device contains uncondensed organic solvent. Therefore, when the carrier gas is circulated and returned to the adsorption / desorption treatment device, the regeneration of the adsorbent is insufficient, which naturally limits the purification capacity of the treated gas and the improvement of the organic solvent recovery efficiency.

[0008] Incidentally, Patent Document 3 improves the purification capacity for the gas to be treated and the recovery efficiency of the organic solvent by providing a second adsorption / desorption treatment device that adsorbs and removes the organic solvent from the carrier gas containing uncondensed organic solvent discharged from the condensation / recovery device. However, it is necessary to provide, on the carrier gas circulation path, the second adsorption / desorption treatment device filled with the second adsorption / desorption element, and a temperature adjustment means that adjusts the carrier gas to a high temperature in order to desorb the organic solvent from the second adsorption / desorption element, which results in a problem of the system configuration becoming complicated and large in size.

[0009] Therefore, the present invention has been made to solve the above-mentioned problems, and aims to provide an organic solvent recovery system that can reduce running costs, improves the purification capacity of the gas to be treated and the recovery efficiency of the organic solvent, and further simplifies the system configuration and reduces its size. [Means for solving the problem]

[0010] As a result of extensive research, the present inventors have found that the above problems can be solved by the following means, and have arrived at the present invention. That is, the present invention has the following configuration.

[0011] 1. An organic solvent recovery system for separating and recovering an organic solvent from a gas to be treated that contains the organic solvent, comprising: a circulation path for circulating a carrier gas; an adsorption / desorption treatment device provided on the circulation path, having an adsorption / desorption element, and alternately adsorbing the organic solvent by introducing the gas to be treated from an introduction path and desorbing the organic solvent by introducing the carrier gas; and a condensation recovery device provided on the circulation path downstream of the adsorption / desorption treatment device, comprising a cooling unit for cooling the carrier gas discharged from the adsorption / desorption treatment device, and which condenses the organic solvent in the carrier gas in the cooling unit and recovers it as a condensed liquid. and a heating unit provided on the circulation path upstream of the adsorption / desorption treatment device, for heating the carrier gas in a low temperature state discharged from the condensation / recovery device; a cooling path for introducing a portion of the gas to be treated flowing through the introduction path into the adsorption / desorption treatment device for cooling the adsorption / desorption element; and a return path for returning the gas to be treated used for cooling the adsorption / desorption element and discharged from the adsorption / desorption treatment device to the introduction path, wherein the adsorption / desorption treatment device introduces the carrier gas heated by the heating unit after introducing the gas to be treated from the introduction path, and then introduces the gas to be treated from the cooling path. ,before The organic solvent recovery system is characterized in that the condensation recovery device has a melting section that temporarily heats and melts the components frozen by cooling the carrier gas.

[0012] According to the above configuration, components frozen by cooling the carrier gas are temporarily heated and melted by the melting unit, thereby eliminating the gas flow problem caused by the adhesion of frozen components. This allows the carrier gas to be cooled at a lower temperature than conventional systems, thereby improving the condensation and recovery efficiency of organic solvents. This also reduces the concentration of organic solvents in the carrier gas discharged from the condensation and recovery device, improving the desorption efficiency of the carrier gas in the adsorption treatment device, eliminating the need for a separate second adsorption and desorption treatment device downstream of the condensation and recovery device. Furthermore, after adsorption is performed by the adsorption and desorption element using the gas to be treated introduced through the introduction path, heated carrier gas is introduced into the adsorption and desorption element to perform desorption. The adsorption and desorption element is then cooled by introducing the gas to be treated through the cooling path, and the gas to be treated is then introduced again through the introduction path to perform adsorption by the adsorption and desorption element. Therefore, the heated adsorption and desorption element can be cooled by introducing the gas to be treated through the cooling path, thereby efficiently adsorbing the organic solvent in the gas to be treated during adsorption in the adsorption and desorption element, improving the purification capacity of the gas to be treated.

[0013] As described above, the organic solvent recovery system of the present invention can reduce running costs, improve the purification capacity of the gas to be treated and the recovery efficiency of the organic solvent, and further simplify and downsize the system configuration.

[0014] 2. The organic solvent recovery system described in 1 above, characterized in that the condensation recovery device has a refrigerant / heat medium supply unit that selects and supplies a refrigerant and a heat medium, the cooling unit and the melting unit are configured as the same cooling / melting unit, and the cooling / melting unit is supplied with a refrigerant from the refrigerant / heat medium supply unit to function as the cooling unit, and is supplied with a heat medium from the refrigerant / heat medium supply unit to function as the melting unit.

[0015] According to the above configuration, a heat medium can be temporarily supplied to the cooling and melting section, which serves as a cooling source, to efficiently heat the frozen components, thereby melting the frozen components in a short period of time.

[0016] 3. The condensation recovery device is provided with a static pressure difference measuring unit that measures the difference in static pressure between the inlet side and the outlet side of the carrier gas, and the refrigerant / heat medium supply unit is provided with the ... difference 3. The organic solvent recovery system according to item 2 above, wherein the supply of the heat medium is selected when the difference in static pressure measured by the measuring unit exceeds a predetermined value.

[0017] According to the above configuration, problems with gas flow caused by the adhesion of frozen components can be detected based on the measurement results of the static pressure difference measurement unit, and by switching to the supply of a heat transfer medium, the frozen components can be automatically heated and melted.

[0018] 4. An organic solvent recovery system described in any one of 1 to 3 above, characterized in that it includes a vapor pressure measuring unit that measures the vapor pressure of the organic solvent contained in the carrier gas discharged from the condensation recovery device, and a temperature adjusting unit that adjusts the temperature of the cooling unit so that the vapor pressure of the organic solvent measured by the vapor pressure measuring unit is below a predetermined value.

[0019] According to the above configuration, the temperature of the cooling section is adjusted to Yari The concentration of the organic solvent in the gas can be reduced to a certain level or less, and the organic solvent adsorbed on the adsorption / desorption element can be efficiently desorbed.

[0020] 5. An organic solvent recovery system described in any one of 1 to 4 above, characterized in that it is provided with a bypass path through which the carrier gas discharged from the condensation recovery device is introduced into the condensation recovery device without passing through the heating section and the adsorption / desorption treatment device, and during the melting by the melting section, the carrier gas is supplied to the condensation recovery device through the bypass path.

[0021] According to the above configuration, by introducing a carrier gas into the condensation recovery device through the bypass path during melting, the melted components can be efficiently liquefied and recovered by being carried by the carrier gas.

[0022] 6. An organic solvent recovery system described in any one of 1 to 5 above, characterized in that the adsorption / desorption treatment device performs a purging process on the adsorption / desorption element after the adsorption and before the desorption, and the melting section performs the melting during the purging process period.

[0023] According to the above configuration, by performing melting during the purging process period, the adsorption / desorption process does not need to be stopped to perform melting, and therefore the system can be operated efficiently.

[0024] 7. An organic solvent recovery system described in any one of 1 to 6 above, characterized in that a confluence point between the introduction path and the return path is provided downstream of the branch point between the introduction path and the cooling path in the flow path of the treated gas.

[0025] According to the above-described configuration, the gas to be treated, which has been heated to a high temperature when used to cool the adsorption / desorption element, does not enter the cooling path, so that the adsorption element can be cooled efficiently.

[0026] 8. The cooling path is for 7. The organic solvent recovery system according to any one of items 1 to 6, characterized in that it is configured identically to the route and further includes a pre-introduction treatment device for adsorbing and desorbing organic solvents between the junction of the introduction route and the return route and the adsorption / desorption treatment device. Te Hmm.

[0027] According to the above configuration, by providing a pre-introduction treatment device, even if the treated gas returning from the return path contains a high concentration of organic solvents, the treated gas can be treated by the pre-introduction treatment device, and the treated gas can be leveled and used to cool the adsorption / desorption element. [Effects of the Invention]

[0028] According to the present invention, components frozen by cooling the carrier gas are temporarily heated and melted by the melting unit, thereby eliminating gas flow problems caused by the adhesion of frozen components. This allows the carrier gas to be cooled at a lower temperature than conventional systems, thereby improving the condensation and recovery efficiency of organic solvents. This also reduces the concentration of organic solvents in the carrier gas discharged from the condensation and recovery device, improving the desorption efficiency of the carrier gas in the adsorption treatment device, eliminating the need for a separate second adsorption and desorption treatment device downstream of the condensation and recovery device. Furthermore, after adsorption is performed by the adsorption and desorption element using the gas to be treated introduced through the introduction path, heated carrier gas is introduced into the adsorption and desorption element to perform desorption. The adsorption and desorption element is then cooled by introducing the gas to be treated through the cooling path, and the gas to be treated is then introduced again through the introduction path to perform adsorption by the adsorption and desorption element. Therefore, since the heated adsorption and desorption element can be cooled by introducing the gas to be treated through the cooling path, adsorption by the adsorption and desorption element can be efficiently performed, improving the purification capacity of the gas to be treated.

[0029] As described above, the organic solvent recovery system of the present invention can reduce running costs, improve the purification capacity of the gas to be treated and the recovery efficiency of the organic solvent, and further simplify and downsize the system configuration. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a diagram showing the structure of an organic solvent recovery system according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing the structure of an organic solvent recovery system in a second embodiment. [Figure 3] FIG. 3 is a time chart showing the temporal switching between adsorption processing and desorption processing using a pair of adsorption / desorption elements in the organic solvent recovery system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0031] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the same or common parts are designated by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0032] (Embodiment 1) As shown in Fig. 1, the organic solvent recovery system 100A of this embodiment includes a circulation path L1 through which a carrier gas flows so as to circulate, an adsorption / desorption treatment device 10, and a condensation recovery device 20 provided on the circulation path L1. Furthermore, a circulation blower 40 is provided on the circulation path L1. The organic solvent recovery system 100A also includes an introduction path L2 through which the gas to be treated is introduced into the adsorption / desorption treatment device 10, and a treated gas blower 50 provided on the introduction path L2. Furthermore, the organic solvent recovery system 100A also includes a cooling path L13 through which a portion of the gas to be treated flowing through the introduction path L2 is introduced into the adsorption / desorption treatment device 10, a cooling blower 60 provided on the cooling path L13, and a return path L14 through which the gas to be treated used to cool the adsorption / desorption elements A13 and B14 and discharged from the adsorption / desorption treatment device 10 is returned to the introduction path L2.

[0033] Various types of gases can be used as the carrier gas, such as water vapor, heated air, an inert gas heated to a high temperature, etc. In particular, if an inert gas that does not contain moisture is used, the organic solvent recovery system 100A can be configured more simply.

[0034] The circulation path L1 includes piping lines L4 to L7 and a bypass path L12 as shown in the figure. The circulation blower 40 is a blowing means for circulating the carrier gas through the circulation path L1, the treated gas blower 50 is a blowing means for introducing the treated gas from the introduction path L2 into the adsorption / desorption treatment device 10, and the cooling blower 60 is a blowing means for introducing a portion of the treated gas flowing through the introduction path L2 into the adsorption / desorption treatment device 10.

[0035] The adsorption / desorption treatment device 10 includes an adsorption / desorption tank A11 and an adsorption / desorption tank B12, and a heater 30. The adsorption / desorption tank A11 is filled with adsorption / desorption elements A13 that adsorb and desorb organic solvents, and the adsorption / desorption tank B12 is filled with adsorption / desorption elements B14 that adsorb and desorb organic solvents. In this embodiment, two adsorption / desorption tanks are provided, but the number of adsorption / desorption tanks may be one or three or more.

[0036] The heater 30 adjusts (heats) the temperature of the carrier gas supplied to the adsorption / desorption tank A11 or the adsorption / desorption tank B12 to a high temperature. More specifically, the heater 30 adjusts the temperature of the carrier gas discharged from the condensation / recovery device 20 and passed through the circulation blower 40 to a high temperature and supplies it to the adsorption / desorption tank A11 or the adsorption / desorption tank B12. Here, the heater 30 adjusts the temperature of the carrier gas introduced into the adsorption / desorption tank A11 and the adsorption / desorption tank B12 so that the adsorption / desorption elements A13 and B14 are maintained at a predetermined desorption temperature.

[0037] The adsorption / desorption elements A13 and B14 adsorb the organic solvents and some of the moisture contained in the gas to be treated by contacting them. Therefore, in the adsorption / desorption treatment device 10, when the gas to be treated is supplied to the adsorption / desorption tank A11 or the adsorption / desorption tank B12, the organic solvents and trace amounts of moisture are adsorbed by the adsorption / desorption elements A13 or B14, and the organic solvents are removed from the gas to be treated, purifying the gas to be treated, and the gas to be treated is discharged as purified gas from the adsorption / desorption tank A11 or the adsorption / desorption tank B12.

[0038] Furthermore, the adsorption / desorption elements A13 and B14 desorb the adsorbed organic solvent and trace moisture by contacting them with a carrier gas in a high temperature state. Therefore, in the adsorption / desorption treatment device 10, when a carrier gas in a high temperature state is supplied to the adsorption / desorption tank A11 or the adsorption / desorption tank B12, the organic solvent and trace moisture are desorbed from the adsorption / desorption element A13 or the adsorption / desorption element B14, and the carrier gas containing the organic solvent and moisture is discharged from the adsorption / desorption tank A11 or the adsorption / desorption tank B12.

[0039] The adsorption / desorption elements A13 and B14 are made of an adsorbent material including any one of granular activated carbon, activated carbon fiber, zeolite, silica gel, porous polymer, and metal-organic framework. Granular, powdery, honeycomb-shaped activated carbon and zeolite are preferably used, with activated carbon fiber being more preferred. Activated carbon fiber has a fibrous structure with micropores on its surface, which allows for high gas contact efficiency and achieves higher adsorption efficiency than other adsorbents.

[0040] Furthermore, activated carbon fiber has higher adsorption selectivity for organic solvents than granular, powdered, honeycomb-shaped activated carbon, and therefore adsorbs almost no moisture contained in the gas to be treated. Therefore, the carrier gas discharged from the adsorption / desorption tank A11 or adsorption / desorption tank B12 of the adsorption / desorption treatment device 10 contains only trace amounts of moisture, allowing the organic solvent recovery system 100A to be configured more simply and downsized. If an adsorption / desorption element with low adsorption selectivity for organic solvents were used, a large amount of moisture contained in the gas to be treated would be adsorbed. Therefore, the carrier gas discharged from the adsorption / desorption tank A11 or adsorption / desorption tank B12 of the adsorption / desorption treatment device 10 also contains a large amount of moisture, resulting in the discharge of wastewater containing organic solvents from the organic solvent recovery system 100A, which requires separate wastewater treatment.

[0041] An inlet path L2 and a piping line L3 are connected to the adsorption / desorption treatment device 10. The inlet path L2 is a piping line for supplying the gas to be treated containing organic solvents and moisture to the adsorption / desorption tank A11 or the adsorption / desorption tank B12 via the gas to be treated blower 50. The inlet path L2 is switched between connected and disconnected to the adsorption / desorption tank A11 by a valve V1, and is switched between connected and disconnected to the adsorption / desorption tank B12 by a valve V3. The piping line L3 is a piping line for discharging the purified gas from the adsorption / desorption tank A11 or the adsorption / desorption tank B12. The piping line L3 is switched between connected and disconnected to the adsorption / desorption tank A11 by a valve V2, and is switched between connected and disconnected to the adsorption / desorption tank B12 by a valve V4.

[0042] Furthermore, piping lines L5 and L6 are connected to the adsorption / desorption treatment device 10. The piping line L5 is a piping line for supplying carrier gas to the adsorption / desorption tank A11 or the adsorption / desorption tank B12 via a heater 30. The piping line L5 is switched between connected and disconnected to the adsorption / desorption tank A11 by a valve V5, and is switched between connected and disconnected to the adsorption / desorption tank B12 by a valve V7. The piping line L6 is a piping line for discharging carrier gas from the adsorption / desorption tank A11 or the adsorption / desorption tank B12. The piping line L6 is switched between connected and disconnected to the adsorption / desorption tank A11 or the adsorption / desorption tank B12 by a valve V7. Detachment The connection / disconnection state to the deposition tank A11 is switched, and the connection / disconnection state to the adsorption / desorption tank B12 is switched by V8.

[0043] In addition, a cooling path L13 and a return path L14 are connected to the adsorption / desorption treatment device 10. The cooling path L13 branches off from the introduction path L2 and is a piping line for supplying a portion of the gas to be treated to the adsorption / desorption tank A11 or the adsorption / desorption tank B12 via a cooling blower 60. The cooling path L13 is switched between connected and disconnected to the adsorption / desorption tank A11 by a valve V10, and is switched between connected and disconnected to the adsorption / desorption tank B12 by a valve V12. The return path L14 is a piping line for discharging the gas to be treated, which has been used to cool the adsorption / desorption elements A13 and B14, from the adsorption / desorption tank A11 or the adsorption / desorption tank B12. The return path L14 is switched between connected and disconnected to the adsorption / desorption tank A11 by a valve V11, and is switched between connected and disconnected to the adsorption / desorption tank B12 by a valve V13. The gas to be treated that is discharged from the adsorption / desorption treatment device 10 and has been used to cool the adsorption / desorption elements flows through the return line L14 and merges with the gas to be treated from the outside that flows through the introduction line L2.

[0044] By opening and closing the valves V1 to V8 and V10 to V13, the adsorption / desorption tank A11 and the adsorption / desorption tank B12 are sequentially supplied with the gas to be treated, the high-temperature carrier gas, and a portion of the gas to be treated used to cool the adsorption / desorption element. As a result, the adsorption / desorption tank A11 and the adsorption / desorption tank B12 function as an adsorption tank and a desorption tank, respectively, and organic solvents and trace amounts of moisture are transferred from the gas to be treated to the high-temperature carrier gas. Specifically, while the adsorption / desorption tank A11 functions as an adsorption tank, the adsorption / desorption tank B12 functions as a desorption tank, and while the adsorption / desorption tank A11 functions as a desorption tank, the adsorption / desorption tank B12 functions as an adsorption tank.

[0045] The condensation recovery device 20 includes a condenser 21, a recovery tank 22, and a refrigerant / heat medium supply unit 23. The condenser 21 adjusts the temperature of the high-temperature carrier gas discharged from the adsorption / desorption tank A11 or the adsorption / desorption tank B12 to a low temperature, thereby condensing the organic solvent and trace amounts of moisture contained in the carrier gas. Specifically, the condenser 21 liquefies the organic solvent and trace amounts of moisture by indirectly cooling the carrier gas using a refrigerant such as antifreeze. The recovery tank 22 stores the organic solvent and trace amounts of moisture liquefied by the condenser 21 as a condensate. The recovery tank 22 and the refrigerant / heat medium supply unit 23 may be provided outside the condensation recovery device 20.

[0046] The refrigerant / heat medium supply unit 23 is for supplying the refrigerant or the heat medium alternately to the condenser 21. PlaceIn 20, a condensation process (refrigerant supply) is performed in which a refrigerant is supplied from a refrigerant / heat medium supply unit 23 to indirectly cool the carrier gas containing the organic solvent and trace moisture discharged from the adsorption / desorption treatment device 10 in a condenser 21, adjusting the temperature to a low state to condense the organic solvent and trace moisture, and a melting process (heat medium supply) is performed in which a heat medium is supplied from the refrigerant / heat medium supply unit 23 to indirectly heat and melt the moisture and organic solvent (frozen components) solidified in the condenser 21. The melting process allows the heat medium to be temporarily supplied to the condenser, which serves as a cooling source, to efficiently heat the frozen components, allowing the frozen components to melt in a short period of time.

[0047] Here, the refrigerant and heat transfer medium may be any of water, ethanol, ethylene glycol, propylene glycol, chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, or mixtures thereof, but are not particularly limited thereto. Furthermore, the heat transfer medium refers to a medium in a state where the temperature is higher than that of the refrigerant. The refrigerant and heat transfer medium are preferably liquids, and if the refrigerant and heat transfer medium are stored in tanks, respectively, the switching from condensation to melting and from melting to condensation can be performed smoothly and in a short time.

[0048] Piping lines L6 and L7 are connected to the condensation recovery device 20. The piping line L6 is a piping line for supplying the carrier gas discharged from the adsorption / desorption treatment device 10 to the condenser 21. The piping line L7 is a piping line for discharging the carrier gas from the condenser 21.

[0049] A piping line L9 is connected to the condenser 21. The piping line L9 is a piping line for introducing the organic solvent and trace amounts of water condensed in the condenser 21 into the recovery tank 22.

[0050] Furthermore, piping lines L10 and L11 are connected to the condenser 21. The piping line L10 is a piping line for supplying the refrigerant or heat medium from the refrigerant / heat medium supply unit 23 to the condenser 21. The piping line L11 is a piping line for discharging the refrigerant or heat medium from the condenser 21 to the outside. In this embodiment, the piping line L11 is connected to the refrigerant / heat medium supply unit 23 and is used to circulate the refrigerant or heat medium. By circulating the refrigerant or heat medium, heat can be recovered and the condensation recovery device 20 can be operated in an energy-saving manner.

[0051] In addition, a bypass path L12 is provided on the circulation path L1, connecting a branch point provided on the piping line L4 with a branch point provided on the piping line L6. The bypass path L12 is switched between connection and disconnection between the piping lines L4 and L6 by a valve V9. The bypass path L12 guides the carrier gas discharged from the condensation recovery device 20 to a heater 30 The other is a route for introducing the refrigerant back into the condensation recovery device 20 without passing through the adsorption / desorption treatment device 10.

[0052] By operating the opening and closing of the above-mentioned valves V5 to V9, the carrier gas is supplied alternately in time to either the adsorption / desorption tank A11 or the adsorption / desorption tank B12 and the bypass line L12.

[0053] Fig. 3 is a time chart showing the temporal switching between adsorption processing and desorption processing using adsorption / desorption element A13 and adsorption / desorption element B14 in the organic solvent recovery system 100A shown in Fig. 1. Next, with reference to Fig. 3, the details of the treatment of the gas to be treated using the organic solvent recovery system 100A of this embodiment will be described using an example in which an inert gas is used as the carrier gas.

[0054] The organic solvent recovery system 100A can continuously treat the gas to be treated by repeatedly performing one cycle shown in FIG. 3 as a unit period.

[0055] In the first half of the cycle (between times t0 and t3 in FIG. 3), an adsorption process is carried out in the adsorption / desorption tank A11 filled with the adsorption / desorption element A13. In parallel with this, a purging process (between times t0 and t1 in FIG. 3) is carried out in the adsorption / desorption tank B12 filled with the adsorption / desorption element B14, in which the inside of the adsorption / desorption tank B12 is replaced with an inert gas. Thereafter, a desorption process (between times t1 and t2 in FIG. 3) is carried out, and thereafter, a cooling process (between times t2 and t3 in FIG. 3) is carried out to cool the adsorption / desorption element B14. The inert gas and carrier gas used in the purging process are the same. A blower for the gas to be treated is provided downstream of the adsorption / desorption tank B12 during the purging process. 50 It is preferable to connect the adsorption / desorption tank B12 to the upstream side of the adsorption / desorption tank B12, and to pipe the treated gas (gas remaining in the adsorption / desorption tank B12) that has been replaced with an inert gas and discharged together with the treated gas to the adsorption / desorption tank A11 where adsorption treatment is being performed. This is because by piping the treated gas to be subjected to adsorption treatment again, the recovery rate of the organic solvent can be increased. In this embodiment, as described above, downstream of the adsorption / desorption tank during barge treatment is 50 and is not connected to the capacitor 21 side (not shown). This switching between the connected and not connected states can also be performed by a valve.

[0056] In the second half of the cycle (between times t3 and t6 in FIG. 3), an adsorption process is carried out in adsorption / desorption tank B12 filled with adsorption / desorption element B14. Concurrently, in adsorption / desorption tank A11 filled with adsorption / desorption element A13, a purging process (between times t3 and t4 in FIG. 3) is carried out to replace the atmosphere in adsorption / desorption tank A11 with an inert gas, followed by a desorption process (between times t4 and t5 in FIG. 3), and then a cooling process (between times t5 and t6 in FIG. 3) of adsorption / desorption element A13.

[0057] In the condensation recovery device 20, a refrigerant is supplied from the refrigerant / heat medium supply unit 23, and the carrier gas containing the organic solvent and trace amounts of moisture discharged from the adsorption / desorption treatment device 10 is indirectly cooled in the condenser 21. The temperature is adjusted to a low temperature, and a condensation process (between times t0 and t2 shown in FIG. 3) is performed to condense the organic solvent, and the organic solvent and trace amounts of moisture are recovered.

[0058] The condensation recovery device 20 may include a vapor pressure measuring unit (not shown) that measures the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21, and may also include a temperature adjusting unit (not shown) that adjusts the temperature of the condenser 21 so that the vapor pressure of the organic solvent measured by the vapor pressure measuring unit is equal to or lower than a predetermined value. Yari The concentration of the organic solvent in the gas can be reduced to a certain level or less, and the organic solvent adsorbed on the adsorption / desorption element A13 and the adsorption / desorption element B14 can be efficiently desorbed.

[0059] The temperature of the carrier gas can be adjusted by controlling the amount or temperature of the refrigerant from the refrigerant / heat medium supply unit 23. Specifically, the relationship between temperature and vapor pressure is stored as data, and the temperature of the carrier gas is adjusted using the refrigerant to achieve the desired vapor pressure. The relationship between temperature and vapor pressure differs depending on the type of organic solvent, but this can be confirmed in literature, etc. The vapor pressure of organic solvents can be measured using a VOC concentration meter, gas chromatography, etc.

[0060] Furthermore, if the condensation recovery device 20 adjusts the temperature of the carrier gas so that the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21 is below a predetermined value, there is no need to install an adsorption / desorption element between the condenser 21 and the adsorption / desorption treatment device 10 to adsorb and remove the organic solvent in the carrier gas, and the organic solvent recovery system 100A can be simplified in configuration and made smaller.

[0061] During the cooling process (times t2 to t3 shown in FIG. 3), a portion of the gas to be treated flowing through the introduction path L2 is introduced into the adsorption / desorption tank B12 via the cooling path L13 to cool the adsorption / desorption element B14. If the cooling of the adsorption / desorption element B14 is insufficient, the adsorption process (times t2 to t3 shown in FIG. 3) of the adsorption / desorption tank B12 is stopped. t3 During the cooling process of the adsorption / desorption element A13 (times t5 to t6 shown in FIG. 3), a portion of the gas to be treated flowing through the introduction path L2 is introduced into the adsorption / desorption tank A11 via the cooling path L13.

[0062] During the cooling process (times t2 to t3 in FIG. 3), the gas to be treated that was used for cooling and discharged from the adsorption / desorption tank B12 is merged with the gas to be treated flowing through the introduction line L2 via the return line L14 and supplied to the adsorption / desorption tank A11 where the adsorption process is being performed. Because the gas to be treated that was used for cooling and discharged from the adsorption / desorption tank B12 contains a large amount of organic solvent, piping it to supply to the adsorption / desorption tank A11 prevents the organic solvent from being discharged outside the system. Similarly, during the cooling process of the adsorption / desorption element A13 (times t5 to t6 in FIG. 3), the gas to be treated that was used for cooling and discharged from the adsorption / desorption tank A11 is merged with the gas to be treated flowing through the introduction line L2 via the return line L14 and supplied to the adsorption / desorption tank B12 where the adsorption process is being performed.

[0063] Here, the confluence of the inlet path L2 and the return path L14 is preferably located downstream of the branch point between the inlet path L2 and the cooling path L13. Because the gas to be treated used to cool the adsorption / desorption elements is in a high-temperature state, if the confluence of the inlet path L2 and the return path L14 is located upstream of the branch point between the inlet path L2 and the cooling path L13, some of the gas to be treated in a high-temperature state will be supplied again to the adsorption / desorption tanks A11 and B12 via the cooling path L13, which will result in insufficient cooling of the adsorption / desorption elements and reduced system performance.

[0064] Furthermore, when the condensation recovery device 20 adjusts the temperature of the carrier gas so that the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21 is below a predetermined value, the temperature of the carrier gas must be adjusted to 0°C or below depending on the type of organic solvent. As a result, the organic solvent and trace moisture contained in the carrier gas solidify within the condenser 21, blocking the carrier gas flow path, increasing the airflow resistance of the condenser 21, and preventing the carrier gas from flowing. Therefore, the refrigerant / heat medium supply unit 23 switches from supplying a refrigerant to supplying a heat medium, thereby performing a melting process (between times t2 and t4 in FIG. 3) in which the solidified organic solvent and trace moisture are indirectly heated and melted so as not to block the flow path within the condenser 21. The melted organic solvent and trace moisture are discharged to the recovery tank 22 through piping line L9.

[0065] Furthermore, during the melting process of the condenser 21, it is preferable to supply the carrier gas discharged from the condensation recovery device 20 to the condenser 21 through the bypass path L12. This is because supplying the carrier gas to the condenser 21 during the melting process facilitates the movement of the melted organic solvent and trace amounts of moisture to the piping line L9, allowing for efficient liquefaction and recovery. It is preferable to supply the carrier gas to the condenser 21 and perform the melting process during the purge process, when the adsorption / desorption element A13 or the adsorption / desorption element B14 is not performing the desorption process. In this embodiment, as described above, during the purge process, the adsorption / desorption tank B12 is not connected to the condenser 21, but is instead connected upstream of the treated gas blower 50. Therefore, the treated gas (gas remaining in the adsorption / desorption tank B12) that was replaced with an inert gas and discharged during the purge process is not supplied to the condenser 21.

[0066] In addition, condensation recovery device 20 continues until the organic solvent and trace amounts of moisture in condenser 21 are completely melted, at which point refrigerant / heat medium supply unit 23 switches from supplying heat medium to supplying refrigerant. As a result, condenser 21 indirectly cools the carrier gas, adjusts the temperature to a low temperature, and again performs the condensation process (between times t4 and t6 shown in FIG. 3) to condense the organic solvent and trace amounts of moisture.

[0067] 3 shows an example in which the melting process is performed between times t2 and t4, but the melting process of capacitor 21 does not have to be performed in every cycle. It may be performed periodically or irregularly. Furthermore, it does not have to be limited to the period from the cooling process of adsorbing / desorbing element B14 to the purging process of adsorbing / desorbing element A13 as shown in FIG. 3, but may be performed between the cooling process of adsorbing / desorbing element A13 and the purging process of adsorbing / desorbing element B14.

[0068] Furthermore, if the melting process cannot be completed between the cooling process and the purging process of the adsorption / desorption element A13 or the adsorption / desorption element B14, several condensers may be installed, and while the melting process continues in one condenser, the condensation process may be performed in the other condenser. In this case, a configuration in which the condenser performing the melting process and the condensation process are switched by valve operation may be considered, but is not particularly limited to this.

[0069] Another possible method for melting the condenser 21 is to supply heated gas into the condenser 21 to heat the solidified organic solvent and trace components. However, this method requires a huge amount of energy to heat the entire interior of the condenser 21 to a high temperature, and it takes a long time to completely melt them. Since the solidification of the organic solvent and trace components occurs in a concentrated manner on the coil through which the refrigerant passes, by applying a method to heat only the coil in the condenser 21 with a heat medium, as in this embodiment, the energy required for the melting process can be minimized and melting can be completed in a short time. Therefore, it is possible to establish a system with only one condenser.

[0070] Here, a static pressure difference measurement unit (not shown) is provided to measure the difference between the static pressure of the carrier gas at the inlet of the condenser 21 and the static pressure at the outlet of the condenser 21. Switching from the condensation process to the melting process when this static pressure difference reaches a predetermined value or greater can constantly prevent an increase in the airflow resistance of the condenser 21. Measurement results from the static pressure difference measurement unit can detect gas flow problems caused by the adhesion of frozen components, and switching to the melting process (heat medium supply) can automatically heat and melt the frozen components. Here, the "predetermined value" is determined as the limit of the pressure loss (differential pressure) in the condenser 21 that does not significantly reduce the airflow rate of the circulation blower 40. The correlation between the pressure loss in the condenser 21 and the reduction in airflow rate of the circulation blower 40 is determined by the discharge pressure capacity of the circulation blower 40. A pressure gauge is used as a means for measuring the static pressure difference, and the static pressure difference can be measured by connecting the positive pressure measurement port of the pressure gauge to the inlet (L6 side) of the condenser 21 and the negative pressure measurement port to the outlet (L7 side) of the condenser 21.

[0071] Furthermore, if the concentrations of organic solvents and water contained in the gas to be treated are known in advance, these data may be stored and the refrigerant / heat medium supply unit 23 may switch between condensation and melting processes at regular time intervals.

[0072] Here, if activated carbon fiber is used for the adsorption / desorption elements A13 and B14, they will hardly adsorb any moisture contained in the gas to be treated, and therefore only a trace amount of moisture will be contained in the carrier gas supplied to the condenser 21. As a result, the amount of moisture that solidifies in the condenser 21 is extremely small, the frequency with which the condenser 21 performs the melting process is significantly reduced, the energy required for the melting process can be reduced, and the organic solvent recovery system 100A can be configured more simply.

[0073] By using the organic solvent recovery system 100A of the present embodiment described above, components frozen during the condensation process for cooling the carrier gas are temporarily heated and melted by the condenser 21 supplied with a heat medium, thereby eliminating the problem of gas flow due to the adhesion of frozen components. This allows the carrier gas to be cooled at a lower temperature than in conventional systems, thereby improving the condensation and recovery efficiency of the organic solvent. This also reduces the concentration of organic solvent in the carrier gas discharged from the condensation and recovery device 20, improving the desorption efficiency of the carrier gas in the adsorption treatment device, eliminating the need for a separate second adsorption and desorption treatment device downstream of the condensation and recovery device 20. Furthermore, after adsorption by the adsorption and desorption element A13 or the adsorption and desorption element B14 is performed by introducing the gas to be treated through the introduction path L2, heated carrier gas is introduced into the adsorption and desorption element A13 or the adsorption and desorption element B14 to perform desorption. Thereafter, the adsorption / desorption element A13 or the adsorption / desorption element B14 is cooled by introducing the gas to be treated from the cooling path L13, and then the gas to be treated is again introduced from the introduction path to be adsorbed by the adsorption / desorption element A13 or the adsorption / desorption element B14. Therefore, the introduction of the gas to be treated from the cooling path L13 can cool the heated adsorption / desorption element A13 or the adsorption / desorption element B14, so that the organic solvent in the gas to be treated can be efficiently adsorbed in the adsorption by the adsorption / desorption element A13 or the adsorption / desorption element B14, and the purification capacity for the gas to be treated is improved.

[0074] Therefore, by using the organic solvent recovery system 100A, running costs can be reduced, and the purification capacity for the gas to be treated and the recovery efficiency of the organic solvent can be improved, resulting in a system with higher performance and a simpler configuration than conventional systems.

[0075] Furthermore, the organic solvent recovery system 100A of this embodiment is also economical because the carrier gas can be reused by constructing a circulation path, and therefore, when an inert gas such as nitrogen gas is used as the carrier gas, the running cost can be particularly reduced.

[0076] Here, in the desorption process, if a heat exchanger (not shown) is installed that can exchange heat between the carrier gas discharged from the adsorption / desorption tank A11 and the adsorption / desorption tank B12 and the carrier gas discharged from the condensation recovery device 20, it is possible to reduce both the amount of refrigerant required for the condensation process in the condensation recovery device 20 and the thermal energy required for the heater 30, resulting in an even more economical configuration.

[0077] (Embodiment 2) 2 is a configuration diagram of an organic solvent recovery system 100B according to Embodiment 2 of the present invention. The organic solvent recovery system 100B basically has the same configuration as the organic solvent recovery system 100A described in Embodiment 1. Therefore, the same components as those in the organic solvent recovery system 100A are denoted by the same reference numerals, and their description will be omitted.

[0078] In the organic solvent recovery system 100A, the cooling path L13 branches off from the introduction path L2 to supply a portion of the gas to be treated to either the adsorption / desorption tank A11 or the adsorption / desorption tank B12 undergoing cooling treatment. In contrast, in the organic solvent recovery system 100B, the cooling path is configured identically to the introduction path L2, and a pre-introduction treatment device 70 is provided on the introduction path (which also serves as a cooling path) L2, between downstream of the junction of the introduction path L2 and the return path L14 and upstream of the adsorption / desorption treatment device 10. The pre-introduction treatment device 70 is equipped with an adsorption / desorption element 71 that adsorbs and desorbs the organic solvent.

[0079] A time chart showing the temporal switching between adsorption treatment and desorption treatment using adsorption / desorption element A13 and adsorption / desorption element B14 in organic solvent recovery system 100B is similar to the time chart in organic solvent recovery system 100A and is shown in Fig. 3. In organic solvent recovery system 100B, during the period after desorption treatment in adsorption / desorption element A13 (times t5 to t6 shown in Fig. 3), valves V1, V11, V3, and V4 are opened, whereby the gas to be treated is supplied to both adsorption / desorption tank A11 and adsorption / desorption tank B12, and a cooling treatment is performed in adsorption / desorption element A13 and an adsorption treatment is performed in adsorption / desorption element B14. Furthermore, during the period after the desorption process in the adsorption / desorption element B14 (times t2 to t3 shown in FIG. 3), the valves V1, V2, V3, and V13 are opened, whereby the gas to be treated is supplied to both the adsorption / desorption tank A11 and the adsorption / desorption tank B12, where the adsorption process is performed in the adsorption / desorption element A13 and the cooling process is performed in the adsorption / desorption element B14. In the organic solvent recovery system 100B, the cooling path is configured identically to the introduction path L2, thereby simplifying the piping configuration.

[0080] The adsorption / desorption element 71 is composed of an adsorbent material including any one of granular activated carbon, activated carbon fiber, zeolite, silica gel, porous polymer, and metal-organic framework. Granular, powdery, honeycomb-shaped activated carbon and zeolite are preferably used, but are not particularly limited to, the adsorption / desorption element A13 or the adsorption / desorption element B14. In the organic solvent recovery system 100B, during the cooling process in the adsorption / desorption element A13 or the adsorption / desorption element B14 (times t5 to t6 or t2 to t3 shown in FIG. 3), even if the organic solvent concentration of the treated gas used for cooling and flowing through the return path L14 is momentarily high, this is equalized by the pre-introduction treatment device 70 equipped with the adsorption / desorption element 71, and the adsorption / desorption element A13 or the adsorption / desorption element B14 is cooled efficiently.

[0081] The embodiments disclosed above are illustrative in all respects and are not restrictive. The technical scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims. [Industrial Applicability]

[0082] The present invention can be effectively used in a system for treating a gas containing an organic solvent discharged from a factory or a building, for example. [Explanation of symbols]

[0083] 10. Adsorption / desorption treatment device 11 Adsorption / desorption tank A 12 Adsorption / desorption tank B 13 Adsorption / Desorption Element A 14 Adsorption / Desorption Element B 20 Condensation recovery device 21 Condenser (melting section, cooling section, cooling and melting section) 22 Recovery Tank 23 Refrigerant / heat medium supply section (refrigerant heat medium supply section) 30 Heater (heating part) 40 Circulating blower 50 Treated gas blower 60 Cooling blower 70 Pre-introduction treatment equipment 71 Adsorption / Desorption Element 100A, 100B Organic Solvent Recovery System L1 Circulation Route L2 introduction route L3~L11 piping lines L12 bypass route L13 Cooling path L14 Return Route V1~V13 valves

Claims

1. An organic solvent recovery system that separates and recovers an organic solvent from a gas to be treated that contains the organic solvent, a circulation path for circulating the carrier gas; an adsorption / desorption treatment device provided on the circulation path, having an adsorption / desorption element, and alternately adsorbing the organic solvent by introducing the gas to be treated from the introduction path and desorbing the organic solvent by introducing the carrier gas; a condensation recovery device that is provided on the circulation path downstream of the adsorption / desorption treatment device, and that includes a cooling unit that cools the carrier gas discharged from the adsorption / desorption treatment device, and that condenses the organic solvent in the carrier gas in the cooling unit and recovers it as a condensed liquid; a heating unit provided on the circulation path upstream of the adsorption / desorption treatment device, which heats the carrier gas in a low temperature state discharged from the condensation recovery device; a cooling path for introducing a portion of the gas to be treated flowing through the introduction path into the adsorption / desorption treatment device for cooling the adsorption / desorption element; a return path for returning the gas to be treated, which is used to cool the adsorption / desorption element and is discharged from the adsorption / desorption treatment device, to the introduction path; the adsorption / desorption treatment device introduces the carrier gas heated by the heating unit after introducing the gas to be treated from the introduction path, then introduces the gas to be treated from the cooling path, and then introduces the gas to be treated again from the introduction path; the condensation recovery device has a melting section that temporarily heats and melts the components frozen by cooling the carrier gas, An organic solvent recovery system, characterized in that no adsorption / desorption treatment device is provided downstream of the condensation recovery device on the circulation path.

2. the condensation recovery device has a refrigerant / heat medium supply unit that selectively supplies a refrigerant and a heat medium, 2. The organic solvent recovery system according to claim 1, wherein the cooling section and the melting section are configured as a single cooling and melting section, and the cooling and melting section functions as the cooling section when supplied with a refrigerant from the refrigerant / heat medium supply section, and functions as the melting section when supplied with a heat medium from the refrigerant / heat medium supply section.

3. a static pressure difference measuring unit for measuring a difference in static pressure between an inlet side and an outlet side of the carrier gas in the condensation recovery device, 3. The organic solvent recovery system according to claim 2, wherein the refrigerant / heat medium supply unit selects the supply of the heat medium when the static pressure difference measured by the static pressure difference measurement unit exceeds a predetermined value.

4. a vapor pressure measuring unit for measuring the vapor pressure of the organic solvent contained in the carrier gas discharged from the condensation recovery device; 4. The organic solvent recovery system according to claim 1, further comprising a temperature adjusting unit that adjusts the temperature of the cooling unit so that the vapor pressure of the organic solvent measured by the vapor pressure measuring unit is equal to or lower than a predetermined value.

5. a bypass path through which the carrier gas discharged from the condensation recovery device is introduced into the condensation recovery device without passing through the heating unit and the adsorption / desorption treatment device, 5. The organic solvent recovery system according to claim 1, wherein a carrier gas is supplied to the condensation recovery device through the bypass path during the melting by the melting section.

6. the adsorption / desorption treatment device performs a purging process on the adsorption / desorption element after the adsorption and before the desorption; 6. The organic solvent recovery system according to claim 1, wherein the melting unit performs the melting during the purging treatment period.

7. 7. The organic solvent recovery system according to claim 1, wherein a confluence of the introduction path and the return path is provided downstream of a branch point between the introduction path and the cooling path in the flow path of the treated gas.

8. The cooling path is configured identically to the introduction path, 7. The organic solvent recovery system according to claim 1, further comprising a pre-introduction treatment device for adsorbing and desorbing the organic solvent between the junction of the introduction path and the return path and the adsorption / desorption treatment device.

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