Organic solvent recovery system

Abstract

An organic solvent recovery system is provided with: a plurality of organic solvent recovery devices each provided with a water vapor supply unit, an extraction flow path, and a plurality of treatment tanks having a first adsorption material capable of adsorbing and desorbing an organic solvent; and alternately performing an adsorption treatment in which the organic solvent contained in the introduced gas to be treated is adsorbed by the first adsorption material and the first treated gas is discharged, and a desorption treatment in which the organic solvent is desorbed from the first adsorption material by the introduced water vapor and the desorbed gas is discharged. A water vapor supply unit that introduces water vapor into a treatment tank selected from the plurality of treatment tanks; and an extraction flow path for discharging the first processing gas from the processing tank. And an organic solvent concentration device that has a second adsorption material capable of adsorbing and desorbing an organic solvent, adsorbs the organic solvent contained in the first treatment gas discharged from the organic solvent recovery device to discharge a second treatment gas, desorbs the adsorbed organic solvent from the second adsorption material, and discharges the adsorbed organic solvent as a concentrated gas. The organic solvent recovery system operates in such a manner that the adsorption treatment and the desorption treatment of the treatment tank in one organic solvent recovery device are not simultaneously switched in the remaining organic solvent recovery devices when the adsorption treatment and the desorption treatment of the treatment tank are switched in one organic solvent recovery device.

Description

Technical Field

[0001] The invention relates to an organic solvent recovery system. Background Art

[0002] As a system for recovering an organic solvent from a gas containing an organic solvent, for example, Patent Document 1 discloses a gas treatment device, which includes: three treatment tanks; a treated gas supply unit; a connecting flow path; a water vapor supply unit; and a dilution gas supply path. In addition, Patent Document 2 discloses an organic solvent recovery system, which includes: a first adsorption-desorption device having two treatment tanks; and a second adsorption-desorption device that recovers an organic solvent contained in a treated gas discharged from any treatment tank of the first adsorption-desorption device.

[0003] In the gas treatment device described in Patent Document 1, the removal rate of the organic solvent is improved by continuously implementing the adsorption process in two treatment tanks. In the organic solvent recovery system described in Patent Document 2, the removal rate of the organic solvent is improved by continuously implementing the adsorption process in any treatment tank of the first adsorption-desorption device and the first treatment section of the second adsorption-desorption device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-147863

[0007] Patent Document 2: Japanese Patent Application Publication No. 2014-240052 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In recent years, there is a demand for further improving the removal rate of organic solvents in organic solvent recovery systems. In response to this demand, for example, a system is considered in which an adsorption process is continuously performed in two treatment tanks as described in Patent Document 1, and then an adsorption process is further performed using a second adsorption and desorption device as described in Patent Document 2. In this case, the treated gas containing the organic solvent desorbed from the second adsorption and desorption device is returned to the flow path that supplies the treated gas (raw gas) to the treatment tank.

[0010] However, in such a system, sometimes, in the treated gas discharged from the treatment tank of the first adsorption and desorption device and supplied to the second adsorption and desorption device, the vapor mist (hereinafter referred to as white smoke) generated just after the switching of the adsorption process and the desorption process of the treatment tank is mixed in a few tens of seconds just after the switching. When the high-temperature and high-humidity treated gas contained in the white smoke is supplied to the second adsorption and desorption device in a state where the adsorbent of the second adsorption and desorption device adsorbs a certain amount of organic solvent in the treated gas (that is, the adsorption process of the second adsorption and desorption device has been carried out for several minutes), the rise in the temperature of the treated gas and the adsorption of moisture to the adsorbent of the second adsorption and desorption device cause the adsorption rate of the organic solvent to slow down, and the organic solvent gas with a concentration higher than the designed outlet concentration of the second adsorption and desorption device is discharged into the treated gas. In addition, the adsorption of moisture caused by the white smoke also causes an increase in the necessary heat energy required for the desorption process of the second adsorption and desorption device. As a countermeasure against such an influence caused by white smoke, cooling and dehumidification of the treated gas can be cited, but in this case, the cooling equipment is large-scale, and therefore the device is large-scale.

[0011] In addition, in the first adsorption-desorption device, the concentration of organic solvent gas contained in the processing gas immediately before switching from the adsorption process to the desorption process is generally higher than the concentration of organic solvent gas contained in the processing gas at the beginning of the adsorption process. This is because the adsorption material of the first adsorption-desorption device fully adsorbs the organic solvent gas and the unused adsorption capacity gradually decreases, and the adsorption rate decreases accordingly. Therefore, a design capable of handling this higher organic solvent gas concentration is required, which leads to the problem of large-scale device.

[0012] In addition, there is a need to use an organic solvent recovery system to process a large amount of gas. However, in this case, a plurality of the organic solvent recovery systems are required, resulting in a problem of large-scale equipment.

[0013] In view of the above problems, an object of the present invention is to provide an organic solvent recovery system that can suppress an increase in the size of the system without reducing the processing performance.

[0014] Solutions to Solve Problems

[0015] As a result of intensive research, the inventors have found that the above-mentioned problems can be solved by the following means, and have arrived at the present invention. That is, the present invention is constituted by the following structure.

[0016] The organic solvent recovery system of the present invention has:

[0017] a plurality of organic solvent recovery devices, each of which has a water vapor supply unit, an extraction flow path, and a plurality of treatment tanks, wherein the plurality of treatment tanks have a first adsorbent capable of adsorbing and desorbing an organic solvent, and alternately perform an adsorption process of using the first adsorbent to adsorb the organic solvent contained in an introduced gas to be treated and discharge the first treatment gas, and a desorption process of using the introduced water vapor to desorb the organic solvent from the first adsorbent and discharge the desorbed gas, wherein the water vapor supply unit introduces the water vapor into a treatment tank selected from the plurality of treatment tanks, and the extraction flow path discharges the first treatment gas from the treatment tank; and

[0018] an organic solvent concentrating device having a second adsorbing material capable of adsorbing and desorbing the organic solvent, adsorbing the organic solvent contained in the first processing gas discharged from the organic solvent recovery device to discharge the second processing gas, and desorbing the adsorbed organic solvent from the second adsorbing material to discharge the concentrated gas,

[0019] in,

[0020] The organic solvent recovery system is operated so that when the adsorption treatment and the desorption treatment of the treatment tank are switched in one of the organic solvent recovery devices, the adsorption treatment and the desorption treatment of the treatment tank are not switched simultaneously in the remaining organic solvent recovery devices.

[0021] In the above-mentioned organic solvent recovery system, it can also be that the organic solvent recovery system has more than three treatment tanks and a connecting flow path that connects a plurality of the treatment tanks selected from all the treatment tanks in series in multi-stages, the adsorption treatment is carried out in the plurality of treatment tanks connected in series in multi-stages to discharge the first treatment gas, and the desorption treatment is carried out using the water vapor in the remaining treatment tanks, and the organic solvent recovery system also has a dilution gas supply flow path that supplies dilution gas to the connecting flow path.

[0022] The organic solvent recovery system may include a return flow path for returning the concentrated gas desorbed from the second adsorbent to the dilution gas supply flow path.

[0023] The organic solvent recovery system may include a return flow path for returning the concentrated gas desorbed from the second adsorbent to a to-be-treated gas supply flow path for introducing the to-be-treated gas into the organic solvent recovery device.

[0024] In the above-mentioned organic solvent recovery system, the second adsorbent may be composed of a material including at least one of granular activated carbon, activated carbon fibers, and zeolite.

[0025] The organic solvent recovery system may also use heated air for desorption of the second adsorbent.

[0026] The organic solvent recovery system may further include a connecting flow path for introducing a portion of the second process gas to the second adsorbent for desorption of the organic solvent from the second adsorbent, and a heating unit provided in the connecting flow path.

[0027] Effects of the Invention

[0028] According to the present invention, by setting a system structure in which the treated gases of multiple organic solvent recovery devices are treated in an organic solvent concentrating device, the organic solvent recovery system can be miniaturized. In addition, by operating in a manner in which the adsorption and desorption process switching of the treatment tank in one organic solvent recovery device and the adsorption and desorption process switching of the treatment tank in the other organic solvent recovery device are not performed simultaneously, when the organic solvent recovery device on one side discharges the treated gas containing white smoke, the other side discharges the treated gas not containing white smoke, and the treated gases merge with each other and are introduced into the organic solvent concentrating device. Therefore, the large amount of water contained in the white smoke and the rise in the temperature of the treated gas can be balanced, not only the cooling device for cooling the white smoke can be miniaturized, but also when the organic solvent gas concentration contained in the treated gas of one organic solvent recovery device is discharged at a relatively high concentration, the organic solvent gas concentration in the treated gas of the other organic solvent recovery device is discharged at a low concentration, so that the treated gas of the organic solvent recovery device introduced into the organic solvent concentrating device merges and is balanced, thereby stabilizing the concentration of the treated gas, thereby miniaturizing the organic solvent concentrating device and miniaturizing the organic solvent recovery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a diagram showing an example of the configuration of an organic solvent recovery system according to an embodiment of the present invention.

[0030] Figure 2 It is a diagram showing an example of the configuration of an organic solvent recovery system according to an embodiment of the present invention.

[0031] Figure 3 This is a table showing the difference between the temperature of the gas to be treated including white smoke introduced into the organic solvent concentrator and the temperature required for cooling in Examples and Comparative Examples.

[0032] Figure 4 This is a table showing the methylene chloride concentration in the gas to be treated introduced into the organic solvent concentrator in Examples and Comparative Examples and the methylene chloride concentration in the treated gas of the organic solvent concentrator. DETAILED DESCRIPTION

[0033] Below, refer to Figure 1 Embodiments of the present invention will be described in detail.

[0034] (Implementation method 1)

[0035] Figure 1 as well as Figure 2 The figures schematically show the structures of organic solvent recovery systems 1A and 1B according to one embodiment of the present invention. The following description is made in the case of having two organic solvent recovery devices 100. The organic solvent recovery systems 1A and 1B include an organic solvent recovery device 100, an organic solvent concentrating device 200 (200A, 200B), a feed flow path 300, and a return flow path 400. The organic solvent recovery systems 1A and 1B are systems in which, after the organic solvent is removed and recovered from the treated gas containing the organic solvent in the organic solvent recovery device 100, the organic solvent is further removed and concentrated in the organic solvent concentrating device 200 (200A, 200B) from the first treated gas discharged from the organic solvent recovery device 100, and the concentrated gas discharged from the organic solvent concentrating device 200 (200A, 200B) is returned to the organic solvent recovery device 100 again through the return flow path 400.

[0036] Each structure is described below.

[0037] The organic solvent recovery device 100 is a device for removing and recovering an organic solvent from a treated gas. The treated gas is supplied to the organic solvent recovery device 100 from a treated gas supply source provided outside the system of the organic solvent recovery device 100. The organic solvent recovery device 100 includes three treatment tanks 101 to 103, a treated gas supply flow path L110, a connecting flow path L121 to L123, a take-out flow path L131 to L133, a water vapor supply flow path L141 to L143, an organic solvent recovery flow path L151 to L153, ​​a separator 120, a resupply flow path L160, and a dilution gas supply flow path L170.

[0038] Each treatment tank 101~103 has a first adsorbent 101A~103A capable of adsorbing and desorbing an organic solvent. As the first adsorbent 101A~103A, there are granular activated carbon, zeolite, honeycomb activated carbon, zeolite, activated carbon fiber, but an adsorbent composed of activated carbon fiber is preferred. Each treatment tank 101~103 has an opening and closing damper V101~V103 for switching the supply / non-supply of the treated gas to the treated gas supply port, and an opening and closing damper V104~V106 for switching the discharge / non-discharge of the treated gas discharge port after the first adsorbent 101A~103A passes.

[0039] In each of the processing tanks 101 to 103, the adsorption of the organic solvent by the first adsorbent 101A to 103A and the desorption of the organic solvent from the first adsorbent 101A to 103A are alternately performed. That is, in one of the three processing tanks 101 to 103, the first adsorption process of adsorbing the organic solvent from the processed gas supplied from the processed gas supply source by the first adsorbent is performed, and in another of the three processing tanks 101 to 103, the second adsorption process of adsorbing the organic solvent from the processed gas (hereinafter referred to as the first adsorption process gas) treated in the processing tank used in the first adsorption process and discharging the first processing gas by the first adsorbent is performed, and during this period, in the remaining processing tank, the desorption process of desorbing the organic solvent from the first adsorbent is performed. In each of the processing tanks 101 to 103, the desorption process, the second adsorption process, the first adsorption process, and the desorption process are repeated in sequence.

[0040] The processed gas supply flow path L110 is a flow path for supplying the processed gas to each processing tank 101 to 103. The upstream end of the processed gas supply flow path L110 is connected to the processed gas supply source. The processed gas supply flow path L110 is provided with a cooler C1 and a heater H1 for adjusting the temperature and humidity of the processed gas flowing into each processing tank 101 to 103.

[0041] The processed gas supply flow path L110 has branch flow paths L111 to L113 for supplying processed gas to each processing tank 101 to 103. An on-off valve V111 is provided in the branch flow path L111. An on-off valve V112 is provided in the branch flow path L112. An on-off valve V113 is provided in the branch flow path L113. The branch flow paths L111 to L113 are connected to the processed gas supply ports of each processing tank 101 to 103.

[0042] Each exhaust flow path L181~L183 is connected to the three processing tanks 101~103 respectively. The processed gas introduced into the processing tank 101 is discharged from the exhaust flow path L181 as the first adsorption process gas through the first adsorption process. The discharged first adsorption process gas is transported to the connecting flow path L121 through the dilution gas supply flow path L170 and the converging path L120. The connecting flow path L121 is connected to the branch flow path 112, and the connecting flow path L121 introduces the first adsorption process gas to the processed gas supply port of the processing tank 102 to perform the second adsorption process. Similarly, when the first adsorption process is performed in the processing tank 102, the first adsorption process gas is discharged from the exhaust flow path L182, and the second adsorption process is performed in the processing tank 103 through the connecting flow path L122. When the first adsorption process is performed in the processing tank 103, the first adsorption process gas is discharged from the exhaust flow path L183, and the second adsorption process is performed in the processing tank 101 through the connecting flow path L123.

[0043] Each of the connecting flow paths L121 to L123 has a merging path L120 that merges with each other. An on-off valve V121 is provided at a location in the connecting flow path L121 that branches off again from the merging path L120. An on-off valve V122 is provided at a location in the connecting flow path L122 that branches off again from the merging path L120. An on-off valve V123 is provided at a location in the connecting flow path L123 that branches off again from the merging path L120.

[0044] The extraction flow paths L131 to L133 are flow paths for extracting the first processing gas which is the processing gas after adsorption processing in each processing tank 101 to 103. The extraction flow paths L131 to L133 are connected to the processing gas exhaust ports in each processing tank 101 to 103. An opening and closing valve V131 is provided in the extraction flow path L131. An opening and closing valve V132 is provided in the extraction flow path L132. An opening and closing valve V133 is provided in the extraction flow path L133. Each extraction flow path L131 to L133 has a merging flow path L130 which merges with each other.

[0045] The water vapor supply flow paths L141 to L143 are flow paths for supplying water vapor for desorbing the organic solvent adsorbed to the first adsorbents 101A to 103A from the first adsorbents 101A to 103A to the respective treatment tanks 101 to 103 .

[0046] The water vapor supply flow path L141 connects the water vapor supply source to the treatment tank 101, and an on-off valve V141 is provided on the water vapor supply flow path. The water vapor supply flow path L142 connects the water vapor supply source to the treatment tank 102, and an on-off valve V142 is provided on the water vapor supply flow path. The water vapor supply flow path L143 connects the water vapor supply source to the treatment tank 103, and an on-off valve V143 is provided on the water vapor supply flow path. Each of the water vapor supply flow paths L141 to L143 has a water vapor supply flow path L140 that merges with each other.

[0047] The organic solvent recovery flow paths L151 to L153 are flow paths for recovering water vapor (desorbed gas) containing the organic solvent desorbed from the first adsorbent 101A to 103A. Each organic solvent recovery flow path L151 to L153 is connected to each treatment tank 101 to 103. Each organic solvent recovery flow path L151 to L153 has L150 that merges with each other. A condenser 122 is provided in the merged flow path L150. The condenser 122 condenses the desorbed gas by cooling the desorbed gas flowing in the merged flow path L150, and discharges the condensate (a mixed liquid of water and a liquid phase organic solvent generated by condensation of the desorbed gas).

[0048] The separator 120 is disposed on the downstream side of the merged flow path L150. After the condensate flows into the separator 120, the condensate is phase-separated into a liquid phase of the separation wastewater and a liquid phase of the recovery solvent in the separator 120, and the recovery solvent is taken out of the system of the organic solvent recovery device 100. A space (exhaust) in which a small amount of organic solvent exists is formed at the upper part of the separator 120.

[0049] The resupply flow path L160 is a flow path connecting the separator 120 and the processed gas supply flow path L110. The exhaust gas in the separator 120 is supplied again to each of the processing tanks 101 to 103 through the resupply flow path L160 and the processed gas supply flow path L110.

[0050] The drainage treatment equipment 130 is a device for removing the organic solvent contained in the separated wastewater. It is supplied from the liquid phase of the separated wastewater of the separator 120, the organic solvent is removed from the separated wastewater, and the treated water is discharged to the outside of the system. Specific examples of the drainage treatment equipment 130 include an aeration device that performs aeration treatment on the separated wastewater, thereby volatilizing the organic solvent contained in the separated wastewater and separating it into aeration gas containing the organic solvent and treated water. It should be noted that the aeration gas is connected to the upstream side of the cooler C1 of the treated gas supply flow path L110 via the aeration gas supply flow path L161. A target dehumidification mechanism that removes moisture from the aeration gas may also be provided in the aeration gas supply flow path.

[0051] The dilution gas supply passage L170 is a passage for supplying dilution gas for promoting drying of the first adsorbents 101A to 103A after the desorption process to the connection passages L121 to L123. The dilution gas is composed of at least one of external air, measurement air, nitrogen, and argon.

[0052] use Figure 1 200A and Figure 2 200B illustrates the organic solvent concentration device 200.

[0053] Figure 1 The organic solvent concentrator 200A provided in the organic solvent recovery system 1A shown is a device for further removing the organic solvent from the first processing gas discharged from the organic solvent recovery device 100. The organic solvent concentrator 200A has a rotor-type adsorption-desorption treatment device including a second adsorbent 201C for adsorbing and desorbing the organic solvent, and the second adsorbent 201C is divided into an adsorption area for adsorbing the organic solvent and a desorption area for desorbing the adsorbed organic solvent.

[0054] The first process gas discharged from the two organic solvent recovery devices 100 is fed through the flow path 300, the cooler C2 and the heater H2, and passes through the adsorption area of ​​the second adsorbent 201C, so that the second process gas as the clean gas from which the organic solvent is further removed can be discharged. At the same time, in the desorption area, the heated gas with a smaller air volume than the first process gas is passed through the desorption area to desorb the organic solvent adsorbed to the adsorbent, so that the concentrated gas with concentrated organic solvent is discharged. The concentrated gas is returned to the organic solvent recovery device 100 from the dilution gas supply flow path L170 connected to the return flow path 400.

[0055] The second adsorbent 201C is composed of an adsorbent having a substantially cylindrical shape, or an adsorbent configured in a substantially cylindrical shape. For example, a motor is attached to the organic solvent concentration device 200A, and the motor drives the second adsorbent 201C to rotate in a tangential direction, and an arbitrary part of the second adsorbent 201C moves alternately between the adsorption zone and the desorption zone in time to perform adsorption and desorption processing.

[0056] The second adsorbent 201C is composed of an adsorbent material including any one of activated alumina, silica gel, activated carbon, and zeolite, and preferably activated carbon or zeolite in a granular, powdery, or honeycomb shape.

[0057] The organic solvent concentrating device 200A discharges the second process gas exhausted from the adsorption region of the second adsorbent 201C to the outside through the clean gas exhaust flow path L220 .

[0058] The organic solvent concentrating device 200A includes a connecting flow path L230 and a heater H3.

[0059] The connecting flow path L230 connects the cleaning gas exhaust flow path L220 to the downstream of the adsorption zone, and uses part of the second process gas in desorption. It should be noted that a structure in which external gas is used in desorption is also possible.

[0060] Figure 2The organic solvent concentrating device 200B provided in the organic solvent recovery system 1B shown is a device for further removing organic solvent from the first process gas discharged from the organic solvent recovery device 100. The organic solvent concentrating device 200B has at least two process tanks. When two are described, the process tanks 201 and 202 have second adsorbents 201A and 202A capable of adsorbing the organic solvent contained in the first process gas discharged from the branch flow paths L211 and L212 through the merged flow path L130. In the process tank 201, the organic solvent contained in the first process gas is adsorbed by the second adsorbent 201A, and on the other hand, the organic solvent in the first process gas adsorbed by the second adsorbent 202A is desorbed in the process tank 202. The process tanks 201 and 202 are sequentially performed while alternating the adsorption process and the desorption process. The second process gas, which is a cleaning gas from which the organic solvent is further removed by passing the first process gas through the process tank, can be discharged from the connecting flow paths L221 and 222 respectively connected to the process tanks 201 and 202. After the adsorption is completed, a heated gas with a smaller volume than the first processing gas is passed to desorb the organic solvent adsorbed to the adsorbent, thereby discharging the concentrated gas containing the organic solvent. The concentrated gas is returned to the organic solvent recovery device 100 from the dilution gas supply flow path L170 connected to the return flow path 400.

[0061] The branch flow path L211 is provided with an on-off valve V211. The branch flow path L212 is provided with an on-off valve V212.

[0062] The connecting flow path L221 is provided with an on-off valve V221. The connecting flow path L222 is provided with an on-off valve V222.

[0063] Each treatment tank 201, 202 has a second adsorbent 201A, 202A capable of adsorbing and desorbing an organic solvent. The second adsorbent 201A, 202A includes granular activated carbon, zeolite, honeycomb activated carbon, zeolite, activated carbon fiber, but preferably is made of activated carbon fiber. Each treatment tank 201, 202 has an opening and closing damper V201, V202 for switching the supply / non-supply of the treated gas to the treated gas supply port, and an opening and closing damper V203, V204 for switching the discharge / non-discharge of the treated gas discharge port after the second adsorbent 201A, 202A passes.

[0064] The organic solvent concentrating device 200B discharges the second processing gas exhausted from the processing tank to the outside through the clean gas exhaust flow path L220.

[0065] The organic solvent concentrating device 200B includes a connecting flow path L230 and a heater H3.

[0066] The connecting flow path L230 connects the clean gas exhaust flow path L220 to the processing tank, and uses a portion of the second processing gas in desorption. It should be noted that it is also possible to use a structure that uses external gas in desorption. The connecting flow path L230 branches into connecting flow paths L231 and L232, and is connected to the processing tanks 201 and 202 respectively. An on-off valve V231 is provided in the connecting flow path L231. An on-off valve V232 is provided in the connecting flow path L232.

[0067] The organic solvent recovery flow paths L241 and L242 are flow paths for recovering water vapor (desorbed gas) containing the organic solvent desorbed from the second adsorbents 201A and 202A. Each organic solvent recovery flow path L241 and L242 is connected to each treatment tank 201 and 202. Each organic solvent recovery flow path L241 and L242 has a return flow path 400 that merges with each other.

[0068] The supply passage 300 is a passage for supplying the treated gas from the organic solvent recovery device 100 to the organic solvent concentration device 200. The supply passage 300 is provided with a cooler C2 and a heater H2 for adjusting the temperature and humidity of the first treatment gas introduced into the organic solvent concentration device 200.

[0069] The return flow path 400 is a flow path for returning the concentrated gas from the organic solvent concentrating device 200 to the organic solvent recovery device 100. The return flow path 400 is connected to the dilution gas supply flow path L170.

[0070] It is preferable that the two organic solvent recovery devices 100 be appropriately provided with a damper control device required so as not to cause mutual switching of the treatment tanks at the same time, as necessary.

[0071] The organic compound contained in the treated gas to be treated by the organic solvent recovery system 1A, 1B of the present embodiment is not particularly limited, but as an example, aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and acrolein, ketones such as methyl ethyl ketone, diacetyl, methyl isobutyl ketone, and acetone, 1,4-oxane, 2-methyl-1,3-dioxolane, 1,3-dioxolane, tetrahydrofuran, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, esters such as ethanol, n- Alcohols such as propanol, isopropanol, butanol, glycols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, organic acids such as acetic acid and propionic acid, aromatic organic compounds such as phenols, toluene, xylene, cyclohexane, ethers such as diethyl ether and allyl glycidyl ether, nitriles such as acrylonitrile, chlorine organic compounds such as dichloromethane, 1,2-dichloroethane, trichloroethylene, epichlorohydrin, N-methyl-2-pyrrolidone, dimethylacetamide, N, N-dimethylformamide, etc. The treated gas may also contain one or more of them.

[0072] Example

[0073] The details of the solvent recovery system of the present invention described in the above embodiment will be further described using the following examples. However, the present invention is not limited to the following examples.

[0074] [Example 1]

[0075] Use the above instructions Figure 1 The organic solvent recovery system 1A shown in the figure performs the following treatment. The gas to be treated at 25° C. containing 26000 ppm of dichloromethane in the organic solvent-containing gas as an example of the gas to be treated is set to an air volume of 5.3 Nm 3 / min (for each organic solvent recovery device), the designed concentration of dichloromethane discharged outside the organic solvent recovery system is set to be below 5ppm.

[0076] First, the treated gas was treated using two organic solvent recovery devices 100. Activated carbon fiber was used as the first adsorbent. 3 / min (per organic solvent recovery device) to the treatment tank 101 which is the first adsorption process. Then, the first adsorption process gas discharged from the treatment tank 101 is sent to the treatment tank 102 which is the second adsorption process. At this time, the first adsorption process gas is 9.5Nm 3 / min, 45°C, using dilution gas and concentrated gas. The gas treated by the treatment tank 102 is discharged as the first treatment gas and is sent to the organic solvent concentrator 200 through the delivery channel 300. When the methylene chloride concentration of the first adsorption process gas discharged from the treatment tank 101 reaches 100ppm, each process is switched. At this time, the switching of each process of the two organic solvent concentrators is adjusted in such a way that the switching timing is offset by half the time of the adsorption process.

[0077] While the first adsorption process was being performed in the treatment tank 101 and the second adsorption process was being performed in the treatment tank 102, the desorption process was performed by introducing the desorption vapor into the treatment tank 103. At this time, white smoke was contained one minute after the adsorption tank was switched, the gas temperature after the two first treatment gases merged was 50°C, the humidity was 100%, and the maximum concentration of dichloromethane in the first treatment gas was 50 ppm.

[0078] Activated carbon fibers are used as the second adsorbent 201A of the organic solvent concentrator 200A.

[0079] The first process gas discharged from the organic solvent recovery device 100 is passed into the adsorption zone, and the second process gas is discharged. In addition, a part of the second process gas is supplied from L230 to the heater H3, superheated to 130° C., supplied to the desorption zone, and the concentrated gas is discharged. The entire amount of the concentrated gas is supplied to the dilution gas supply flow path L170 of the organic solvent recovery device 100 through the return flow path 400. At this time, the dichloromethane concentration in the second process gas is 5 ppm or less.

[0080] It should be noted that the activated carbon fiber used in the first adsorbent of the organic solvent recovery device 100 was 3.8 kg / tank, and the activated carbon fiber used in the first adsorbent of the organic solvent concentration device 200A was 0.8 kg / device.

[0081] [Comparative Example]

[0082] The same gas to be treated as in the example was treated by the organic solvent recovery device 100 and the organic solvent concentration device 200A in the same manner as in the example. However, at this time, the switching of the steps of the two organic solvent recovery devices 100 was adjusted so as to be performed at the same timing.

[0083] At this time, one minute after the adsorption tank switching, white smoke was contained, the gas temperature after the two first processing gases merged was 60°C, the humidity was 100%, and the maximum concentration of dichloromethane in the first processing gas was 100ppm. In addition, the dichloromethane concentration in the second processing gas at this time was less than 5ppm.

[0084] The difference between the temperature of the first processing gas containing white smoke introduced into the organic solvent concentrator in the embodiment and the comparative example and the temperature required for cooling is Figure 3 As shown in FIG. 1 , the maximum concentration of dichloromethane in the second process gas is Figure 4 Shown in.

[0085] Compared with the comparative example using the conventional technology, the embodiment of the present invention does not switch the treatment tanks of the two organic solvent concentrators at the same time, thereby suppressing the rise in gas temperature caused by the inflow of white smoke, thereby suppressing the temperature required for cooling the gas, and realizing the miniaturization of the cooling equipment. In addition, the maximum concentration of dichloromethane in the first treatment gas can be suppressed by balancing, thus showing that the miniaturization of the organic solvent concentrator can also be realized.

[0086] The above disclosed embodiments, variations and examples are all illustrative and non-restrictive. In addition, modes obtained by appropriately combining the embodiments, variations and examples are also included in the scope of the present invention. That is, the technical scope of the present invention is effective through the technical solution, and includes all changes, corrections, substitutions, etc. within the meaning and scope equivalent to the description of the technical solution.

[0087] Industrial Applicability

[0088] The present invention controls the switching of various processes of multiple organic solvent recovery devices in the organic solvent recovery system without performing the switching at the same time, thereby not only achieving the miniaturization of the cooling equipment used for white smoke prevention, but also achieving the miniaturization of the organic solvent concentration device in the system, thereby being of great benefit to the industrial sector.

[0089] Description of Reference Numerals

[0090] 1A, 1B: organic solvent recovery system, 100: organic solvent recovery device, 101~103: treatment tank, 101A~103A: first adsorbent, 120: separator, 122: condenser, 130: wastewater treatment equipment, 200, 200A, 200B: organic solvent concentration device, 201, 202: treatment tank, 201A, 202A, 201C: second adsorbent, 300: supply flow path, 400: return flow path, H1~H3: heater (heating unit), C1, C2: cooler, L110: treated gas supply flow path, L111~L113, L211, L212: branch flow path, L120, L130, L150: confluence path, L121~L123, L22 1. L222: connecting flow path, L131~L133: extraction flow path, L140~L143: water vapor supply flow path, L151~L153, ​​L241, L242: organic solvent recovery flow path, L160: re-supply flow path, L161: aeration gas supply flow path, L170: dilution gas supply flow path, L181~L183: exhaust flow path, L220: clean gas exhaust flow path, L230~L232: connecting flow path, V111~V113, V121~V123, V131~V133, V141~V143, V211, V212, V221, V222, V231, V232: opening and closing valves, V101~V106, V201~V204: opening and closing baffles.

Claims

1. An organic solvent recovery system, comprising: a plurality of organic solvent recovery devices, each of which has a water vapor supply unit, an extraction flow path, and a plurality of treatment tanks, wherein the plurality of treatment tanks have a first adsorbent capable of adsorbing and desorbing an organic solvent, and alternately perform an adsorption process of using the first adsorbent to adsorb the organic solvent contained in an introduced gas to be treated and discharge the first treatment gas, and a desorption process of using the introduced water vapor to desorb the organic solvent from the first adsorbent and discharge the desorbed gas, wherein the water vapor supply unit introduces the water vapor into a treatment tank selected from the plurality of treatment tanks, and the extraction flow path discharges the first treatment gas from the treatment tank; and an organic solvent concentrating device having a second adsorbing material capable of adsorbing and desorbing the organic solvent, adsorbing the organic solvent contained in the first processing gas discharged from the organic solvent recovery device to discharge the second processing gas, and desorbing the adsorbed organic solvent from the second adsorbing material to discharge the concentrated gas, in, The organic solvent recovery system is operated so that when the adsorption treatment and the desorption treatment of the treatment tank are switched in one of the organic solvent recovery devices, the adsorption treatment and the desorption treatment of the treatment tank are not switched simultaneously in the remaining organic solvent recovery devices.

2. The organic solvent recovery system according to claim 1, wherein: The organic solvent recovery system comprises three or more treatment tanks and a connecting flow path connecting a plurality of selected treatment tanks in series in multiple stages among all the treatment tanks, the adsorption treatment is performed in the plurality of treatment tanks connected in series in multiple stages to discharge the first treatment gas, and the desorption treatment is performed using the water vapor in the remaining treatment tanks, The organic solvent recovery system further includes a dilution gas supply flow path for supplying a dilution gas to the connection flow path.

3. The organic solvent recovery system according to claim 2, wherein: The organic solvent recovery system includes a return flow path for returning the concentrated gas desorbed from the second adsorbent to the dilution gas supply flow path.

4. The organic solvent recovery system according to claim 1, wherein: The organic solvent recovery system includes a return flow path for returning the concentrated gas desorbed from the second adsorbent to a to-be-treated gas supply flow path for introducing the to-be-treated gas into the organic solvent recovery device.

5. The organic solvent recovery system according to any one of claims 1 to 4, wherein: The second adsorbent is made of a material including at least one of granular activated carbon, activated carbon fibers, and zeolite.

6. The organic solvent recovery system according to any one of claims 1 to 4, wherein: Heated air is used for desorption of the second adsorbent.

7. The organic solvent recovery system according to any one of claims 1 to 4, wherein: The organic solvent recovery system includes a connecting flow path for introducing a portion of the second process gas to the second adsorbent for desorption of the organic solvent from the second adsorbent, and a heating unit provided in the connecting flow path.

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