Organic Solvent Recovery System

Abstract

An organic solvent recovery system according to the present invention comprises: a circulation path which circulates a carrier gas; an adsorption / desorption processing device; a condensing and recovering device which condenses an organic solvent in the carrier gas; a heating unit which heats the carrier gas; and a cooling inlet path for introducing the carrier gas from the condensing and recovering device to an adsorption / desorption element without going through the heating unit. The adsorption / desorption processing device performs adsorption with the adsorption / desorption element by introducing a gas to be treated, and then performs desorption by introducing the heated carrier gas, afterwards the carrier gas in a low temperature state is introduced from the cooling inlet path to cool the adsorption / desorption element, and thereafter the gas to be treated is introduced to perform adsorption again. The condensing and recovering device has a melting part which temporarily heats and melts a component that has been frozen by the cooling of 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, and 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 containing 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 and desorbing the organic solvent by introducing the carrier gas; a condensation recovery device provided on the circulation path downstream of the adsorption / desorption treatment device, having a cooling unit for cooling the carrier gas discharged from the adsorption / desorption treatment device, and condensing the organic solvent in the carrier gas in the cooling unit to recover it as a condensate; 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; and a cooling inlet path provided on the circulation path, for introducing the carrier gas in a low-temperature state discharged from the condensation recovery device into the adsorption / desorption element without passing through the heating unit. Escape and a condensation recovery device that includes a melting section that temporarily heats and melts 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 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, heated carrier gas is introduced into the adsorption and desorption element to perform desorption. The adsorption and desorption element is then cooled by introducing carrier gas through the cooling inlet path, and then adsorption is performed again by the adsorption and desorption element. Therefore, since the adsorption and desorption element, which is heated by the introduction of carrier gas, can be cooled, adsorption by the adsorption and desorption element can be efficiently adsorbed, improving the purification capacity of the treated gas.

[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 during the melting by the melting section, a carrier gas is supplied to the condensation recovery device through the cooling inlet path without passing through the heating section.

[0021] According to the above configuration, by introducing a carrier gas into the condensation recovery device through the cooling inlet 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 the carrier gas heated by the heating section and the carrier gas from the cooling inlet path contact the adsorption / desorption element in a countercurrent direction.

[0025] According to the above configuration, the adsorption / desorption element can be effectively heated to desorb the adsorption / desorption element, and the adsorption / desorption element can be effectively cooled. It is possible to do so. [Effects of the Invention]

[0026] 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 in 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 using the adsorption and desorption element, heated carrier gas is introduced into the adsorption and desorption element to perform desorption. The adsorption and desorption element is then cooled by introducing carrier gas through the cooling inlet path, and then adsorption is performed again using the adsorption and desorption element. Therefore, since the adsorption and desorption element, which is heated by the introduction of carrier gas, can be cooled, adsorption in the adsorption and desorption element can efficiently adsorb organic solvents in the treated gas, improving the purification capacity of the treated gas. 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]

[0027] [Figure 1] 1 is a diagram showing a structure of an organic solvent recovery system according to an embodiment. [Figure 2] 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

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the 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.

[0029] (Embodiment) 1, the organic solvent recovery system 100A in this embodiment includes a circulation path L1 through which a carrier gas flows so as to circulate, an adsorption / desorption treatment device 10, a condensation recovery device 20, and a circulation blower 40, which are provided on the circulation path L1. The organic solvent recovery system 100A further includes a treated gas blower 50 that supplies the treated gas to the adsorption / desorption treatment device 10.

[0030] 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.

[0031] The circulation path L1 includes piping lines L4 to L7, a cooling inlet path L12, and a cooling outlet path L13, as shown in the figure. The circulation fan 40 is a blowing means for circulating the carrier gas through the circulation path L1, and the treated gas blower 50 is a blowing means for blowing the carrier gas through the circulation path L1. Reason This is a blowing means for introducing the gas to be treated into the device 10.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] Piping lines L2 and L3 are connected to the adsorption / desorption treatment device 10. Piping line 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 piping line 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.

[0039] 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, or for discharging carrier gas from the adsorption / desorption tank A11 or the adsorption / desorption tank B12. 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, or for supplying carrier gas to the adsorption / desorption tank A11 or the adsorption / desorption tank B12 via a cooling inlet path L12. The piping line L6 is switched between connected and disconnected to the adsorption / desorption tank A11 by a valve V6, and is switched between connected and disconnected to the adsorption / desorption tank B12 by a valve V8.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] Also, a cooling inlet 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 cooling inlet path L12 is switched between connected and disconnected states with the piping lines L4 and L6 by a valve V9. The branch point between the cooling inlet path L12 and the piping line L4 is located downstream of the condensation recovery device 20 and upstream of the heater 30, and the branch point between the cooling inlet path L12 and the piping line L6 is located downstream of the adsorption / desorption treatment device 10 and upstream of the condensation recovery device 20.

[0047] Furthermore, on the circulation path L1, a cooling outlet path L13 is provided which connects a branch point provided on the piping line L5 to a branch point provided on the piping line L6. The cooling outlet path L13 is switched between connection and disconnection with the piping lines L5 and L6 by a valve V11. Exit The branch point of the path L13 and the piping line L5 is located downstream of the heater 30 and upstream of the adsorption / desorption treatment device 10. Exit The branch point of the path L13 and the piping line L6 is located downstream of the branch point of the cooling inlet path L12 and the piping line L6 and upstream of the condensation recovery device 20.

[0048] In addition, a valve V10 is provided between the branch point between the piping line L4 and the cooling inlet path L12 and the branch point between the piping line L5 and the cooling outlet path L13, and the valve V10 switches between a connected / disconnected state of the branch point between the piping line L4 and the cooling inlet path L12 and the branch point between the piping line L5 and the cooling outlet path L13.

[0049] In addition, a valve V12 is provided between the branch point between the piping line L6 and the cooling inlet path L12 and the branch point between the piping line L6 and the cooling outlet path L13, and the valve V12 switches between a connected / disconnected state of the branch point between the piping line L6 and the cooling inlet path L12 and the branch point between the piping line L6 and the cooling outlet path L13.

[0050] By opening and closing the valves V9 to V12, the carrier gas is alternately supplied at high or low temperature to either the adsorption / desorption tank A11 or the adsorption / desorption tank B12. More specifically, when valves V10 and V12 are open and valves V9 and V11 are closed, the carrier gas is supplied at high temperature to either the adsorption / desorption tank A11 or the adsorption / desorption tank B12 via the heater 30. When valves V9 and V11 are open and valves V10 and V12 are closed, the carrier gas is supplied at low temperature to either the adsorption / desorption tank A11 or the adsorption / desorption tank B12 via the cooling inlet path L12.

[0051] As can be seen from the above, the gas to be treated, the high-temperature carrier gas, and the low-temperature carrier gas are sequentially supplied to the adsorption / desorption tanks A11 and B12 by opening and closing the valves V1 to V8. This causes the adsorption / desorption tanks A11 and B12 to function as adsorption and desorption tanks, respectively, and organic solvents and trace amounts of moisture migrate 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.

[0052] Here, the carrier gas heated by the heater 30 and the carrier gas from the cooling inlet path come into contact with the adsorption / desorption element A13 or the adsorption / desorption element B14 in a counterflow direction, thereby effectively heating and desorbing the adsorption / desorption element A13 or the adsorption / desorption element B14, and cooling the adsorption / desorption element A13 or the adsorption / desorption element B14.

[0053] Fig. 2 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. 2, 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. 2 as a unit period.

[0055] In the first half of the cycle (between times t0 and t3 in FIG. 2), 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. 2) 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. 2) is carried out, and thereafter, a cooling process (between times t2 and t3 in FIG. 2) 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. 50It is preferable to connect the adsorption / desorption tank B12 to the upstream side of the tank B12, and to pipe the tank B12 so that the treated gas (gas remaining in the adsorption / desorption tank B12) that has been replaced with an inert gas and discharged is supplied together with the treated gas to the adsorption / desorption tank A11 where the adsorption / desorption tank B12 is undergoing adsorption treatment. This is because piping the tank B12 so that the treated gas is subjected to adsorption treatment again can increase the recovery rate of the organic solvent. In this embodiment, as described above, the downstream side of the adsorption / desorption tank during barge treatment is connected to the upstream side of the treated gas blower 40, but is disconnected from the condenser 21 (not shown). This connection / disconnection can also be switched by a valve.

[0056] In the second half of the cycle (between times t3 and t6 in FIG. 2), 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. 2) 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. 2), followed by a cooling process of adsorption / desorption element A13 (between times t5 and t6 in FIG. 2).

[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. 2) is performed to condense the organic solvent, and the organic solvent and trace amounts of moisture are recovered.

[0058] Condensation recovery device 20 includes a vapor pressure measuring unit (not shown) that measures the vapor pressure of the organic solvent contained in the carrier gas discharged from condenser 21, and may also include a temperature adjusting unit (not shown) that adjusts the temperature of 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. By adjusting the temperature of the condenser, the concentration of the organic solvent in the discharged carrier gas can be kept below a certain level, and the organic solvent adsorbed on adsorption / desorption element A13 and 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. 2), the carrier gas is introduced into the adsorption / desorption tank B12 via the cooling inlet path L12 to cool the adsorption / desorption element B14. If the adsorption / desorption element B14 is not sufficiently cooled, the adsorption process (times t2 to t3 shown in FIG. 2) 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. 2), the adsorption / desorption element B14 is at a high temperature, making it difficult to sufficiently adsorb the organic solvent, resulting in a decrease in performance of the system. a Gas is introduced into the adsorption / desorption tank A11 via the cooling inlet path L12.

[0062] During the cooling process (times t2 to t3 shown in FIG. 2), the carrier gas discharged from the adsorption / desorption tank B12 is merged with the carrier gas flowing through the piping line L6 via the cooling outlet path L13 and is supplied to the condensation recovery device 20. The carrier gas discharged from the adsorption / desorption tank B12 contains a large amount of organic solvent, and the organic solvent is recovered by the condensation recovery device 20. Similarly, during the cooling process of the adsorption / desorption element A13 (times t5 to t6 shown in FIG. 2), the carrier gas discharged from the adsorption / desorption tank A11 is merged with the carrier gas flowing through the piping line L6 via the cooling outlet path L13 and is supplied to the condensation recovery device 20. a The gas is mixed with the carrier gas flowing through the piping line L6 via the cooling outlet path L13 and is supplied to the condensation recovery device 20.

[0063] 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. 2) in which the solidified organic solvent and trace moisture are indirectly heated and melted so that the flow path within the condenser 21 is not blocked. The melted organic solvent and trace moisture are discharged to the recovery tank 22 through piping line L9.

[0064] Furthermore, during the melting process of the condenser 21, it is preferable to open the valves V9 and V12 and close the valves V10 and V11 to supply carrier gas to the condenser 21 via the cooling inlet path L12. This is because supplying carrier gas to the condenser 21 during the melting process makes it easier for the melted organic solvent and trace amounts of moisture to move to the piping line L9, allowing for efficient liquefaction and recovery. It is preferable to supply carrier gas to the condenser 21 to perform the melting process during the purging 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, the adsorption / desorption tank 21 during the purging process is B 12 is not connected to the condenser 21, but instead is connected to the upstream of the treated gas blower 50, so that the treated gas (gas remaining in the adsorption / desorption tank B12) that is replaced with inert gas and discharged during the purging process is not supplied to the condenser 21.

[0065] 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. 2) to condense the organic solvent and trace amounts of moisture.

[0066] 2 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. 2, but may be performed between the cooling process of adsorbing / desorbing element A13 and the purging process of adsorbing / desorbing element B14.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Here, adsorption / desorption element A 13 Furthermore, if activated carbon fiber is used for the adsorption / desorption element B14, it 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, which significantly reduces the frequency with which the condenser 21 performs the melting process, thereby reducing the energy required for the melting process and further simplifying the configuration of the organic solvent recovery system 100A.

[0072] 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, 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 a carrier gas from the cooling inlet path L12, and then the gas to be treated is introduced again to perform adsorption by the adsorption / desorption element A13 or the adsorption / desorption element B14. Therefore, the heated adsorption / desorption element A13 or the adsorption / desorption element B14 can be cooled by introducing the carrier gas from the cooling inlet path L12, and therefore 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.

[0073] 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.

[0074] 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. Therefore, when an inert gas such as nitrogen gas is used as the carrier gas, the running cost can be particularly reduced.

[0075] Furthermore, 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.

[0076] 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]

[0077] 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]

[0078] 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 100A Organic Solvent Recovery System L1 Circulation Route L2~L11 piping lines L12 Cooling inlet path L13 Cooling outlet path V1~V12 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 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 inlet path that is provided on the circulation path and that introduces the low-temperature carrier gas discharged from the condensation recovery device into the adsorption / desorption element without passing through the heating unit; the adsorption / desorption treatment device introduces the carrier gas heated by the heating unit into the adsorption / desorption element after introducing the gas to be treated, then introduces the carrier gas in a low temperature state from the cooling inlet path, and then introduces the gas to be treated again; 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. 5. The organic solvent recovery system according to claim 1, wherein, during the melting by the melting section, a carrier gas is supplied to the condensation recovery device through the cooling inlet path without passing through the heating 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 the carrier gas heated by the heating section and the carrier gas from the cooling inlet path contact the adsorption / desorption element in counterflow directions.

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