JP7435934B1 - Organic solvent recovery system - Google Patents

Abstract

Provided is an organic solvent recovery system that can improve the quality of recovered organic solvents. The processed gas containing an organic solvent includes a first processed gas and a second processed gas containing a lower concentration of organic solvent than the first processed gas. The condensation recovery device (10) cools the first to-be-treated gas, condenses the organic solvent contained in the first to-be-treated gas, and discharges it as a cooled to-be-treated gas with a reduced concentration of the organic solvent contained therein. do. The confluence section (100) merges the cooling process gas and the second process gas to form a third process gas. The adsorption/desorption processing device (50) includes adsorption/desorption elements (52, 54) that adsorb and desorb the organic solvent contained in the third gas to be treated. The adsorption/desorption processing device (50) adsorbs organic solvents onto the adsorption/desorption elements (52, 54) by introducing a third gas to be treated, and absorbs organic solvents from the adsorption/desorption elements (52, 54) by introducing a desorption gas. Alternately desorbing and desorbing the solvent.

Description

The present disclosure relates to organic solvent recovery systems.

International Publication No. 2021/132071 (Patent Document 1) discloses that after a part of the organic solvent contained in the gas to be treated is condensed in a condensation recovery device, the uncondensed organic solvent is adsorbed by an adsorption/desorption element to be treated. An organic solvent recovery system is disclosed that recovers organic solvent from a process gas.

International Publication 2021/132071

When an organic solvent contained in a gas to be treated is recovered using an adsorption/desorption element, the quality of the recovered organic solvent may deteriorate due to the heat generated when the organic solvent is desorbed from the adsorption/desorption element.

The present disclosure proposes an organic solvent recovery system that can improve the quality of recovered organic solvents.

In the present disclosure, the following organic solvent recovery system is proposed.
(Section 1) The processed gas containing an organic solvent includes a first processed gas and a second processed gas containing a lower concentration of organic solvent than the first processed gas. An organic solvent recovery system that separates and recovers an organic solvent from a gas to be treated includes a condensation recovery device, a confluence section, and an adsorption/desorption processing device. The condensation recovery device cools the first to-be-treated gas, condenses the organic solvent contained in the first to-be-treated gas, and discharges it as a cooled to-be-treated gas in which the concentration of the organic solvent contained therein is reduced. The confluence section merges the cooling process gas and the second process gas to form a third process gas. The adsorption/desorption processing device includes an adsorption/desorption element that adsorbs and desorbs an organic solvent contained in the third gas to be treated. The adsorption/desorption processing device alternately adsorbs the organic solvent to the adsorption/desorption element by introducing the third gas to be treated, and desorbs the organic solvent from the adsorption/desorption element by introducing the desorption gas.

(Paragraph 2) In the organic solvent recovery system described in Paragraph 1, the quotient obtained by dividing the air volume of the second gas to be treated by the air volume of the first gas to be treated is defined as A, and the organic solvent contained in the first gas to be treated is The quotient obtained by dividing the concentration of the solvent by the concentration of the organic solvent contained in the second gas to be treated is designated as B, and the recovery rate of the organic solvent contained in the first gas to be treated in the condensation recovery device is designated as C (%). In this case, 0<(A÷B÷C)≦0.033 may be satisfied.

(Section 3) The organic solvent recovery system according to Item 1 or 2 includes a second condensation recovery device, and the second condensation recovery device cools the desorption gas discharged from the adsorption/desorption processing device. In this way, the organic solvent contained in the desorption gas may be condensed and recovered.

(Section 4) In the organic solvent recovery system described in Section 3, the desorption gas may be water vapor.

(Section 5) In the organic solvent recovery system according to any one of Items 1 to 3, the desorption gas may be an inert gas.

(Section 6) The organic solvent recovery system according to any one of Section 3, Section 4, or Section 5 citing Section 3 further includes a circulation path through which desorption gas circulates, and The desorption processing device and the second condensation recovery device may be provided in the circulation path.

(Section 7) The organic solvent recovery system according to Item 6 may further include a heating section that is provided in the circulation path and heats the desorption gas discharged from the second condensation and recovery device.

(Section 8) The organic solvent recovery system according to any one of Items 1 to 7 may further include a temperature transmitter that detects and transmits the temperature of the third gas to be treated.

According to the organic solvent recovery system of the present disclosure, the quality of the organic solvent to be recovered can be improved.

1 is a diagram schematically showing the configuration of an organic solvent recovery system according to a first embodiment. FIG. 2 is a diagram schematically showing the configuration of an organic solvent recovery system according to a second embodiment. It is a graph showing the energy reduction rate by the organic solvent recovery system of this disclosure.

Hereinafter, embodiments will be described based on the drawings. In the following description, the same parts and components are given the same reference numerals. Their names and functions are also the same. Therefore, detailed explanations thereof will not be repeated. It is also planned from the beginning that arbitrary configurations will be extracted from the embodiments and that they will be combined arbitrarily.

[First embodiment]
FIG. 1 is a diagram schematically showing the configuration of an organic solvent recovery system 1 according to the first embodiment. The organic solvent recovery system 1 is a system that separates and recovers organic solvents from a gas to be treated containing organic solvents.

The organic solvent recovery system of the present disclosure is suitable for processing organic solvents that may be decomposed due to thermal history. More specifically, the organic solvents include methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, trichloroethane, trichloroethylene, tetrachloroethane, tetrachloroethylene, pentachloroethane, dichloropropane, o-dichlorobenzene, m-dichlorobenzene, trichlorobenzene, Halogenated organic solvents such as bromopropane, methyl bromide, Freon-112, Freon-113, hydrochlorofluorocarbon (HCFC), hydrofluorocarbon (HFC), hydrofluoroolefin (HFO), and methyl iodide may be used. Organic solvents include methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, vinyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, Ethyl butyrate, propyl butyrate, butyl butyrate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, 2-hydroxyethyl methacrylate, carbonic acid An ester organic solvent such as diethyl may also be used. The organic solvent may be a ketone organic solvent such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, diacetyl, or the like. The organic solvent may be an ether organic solvent such as diethyl ether, dipropyl ether, tetrahydrofuran, dibutyl ether, or epoxide. The organic solvent may be a nitrile organic solvent such as acrylonitrile.

Further, in addition to the organic solvents described above, a portion of the gas to be treated may include an organic solvent that is relatively difficult to decompose. More specifically, the organic solvent is an alcoholic organic solvent such as methanol, ethanol, isopropanol, n-butanol, 2-butanol, isobutanol, t-butanol, allyl alcohol, pentanol, heptanol, ethylene glycol, diethylene glycol, etc. There may be. The organic solvent may be a phenolic organic solvent such as phenol, o-cresol, m-cresol, p-cresol, or xylenol. The organic solvent may be a hydrocarbon organic solvent such as n-hexane, isohexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, n-nonane, isononane, decane, dodecane, undecane, tetradecane, decalin, etc. . The organic solvent may be an aromatic organic solvent such as benzene, toluene, m-xylene, p-xylene, o-xylene, ethylbenzene, or 1,3,5-trimethylbenzene. The organic solvent may be N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, or the like.

As shown in FIG. 1, the processed gas containing an organic solvent includes a first processed gas and a second processed gas. The first gas to be treated contains a relatively high concentration of organic solvent. The first gas to be treated is discharged from the first gas discharge facility 91 . The second gas to be treated contains a relatively low concentration of organic solvent. The concentration of the organic solvent contained in the second gas to be treated is lower than the concentration of the organic solvent contained in the first gas to be treated. The second gas to be treated is discharged from the second gas discharge facility 92 .

The first gas discharge facility 91 and the second gas discharge facility 92 are, for example, production facilities. The production equipment is, for example, a film coating machine. The first gas to be treated is, for example, exhaust gas from the upstream side of the film coating machine. The second gas to be treated is, for example, exhaust gas from the downstream side of the film coating machine. The organic solvent contained in the first gas to be treated and the organic solvent contained in the second gas to be treated may be the same or different. The organic solvent contained in the first gas to be treated and the organic solvent contained in the second gas to be treated are substances that are not dangerous even when mixed.

As shown in FIG. 1, the organic solvent recovery system 1 mainly includes a condensation recovery device 10 and an adsorption/desorption processing device 50.

The first to-be-treated gas discharged from the first to-be-treated gas discharge facility 91 is introduced into the condensation recovery device 10 via the first flow path F1. The first flow path F1 is a path for introducing the first gas to be processed into the condensation recovery device 10. The condensation recovery device 10 has a condensation section 20. The condensing section 20 includes a cooling section 21, a separating section 22, and a chamber 23.

The cooling unit 21 cools the first gas to be processed that passes through the cooling unit 21 . The cooling unit 21 cools the first gas to be treated, thereby condensing a part of the organic solvent contained in the first gas to be treated. Preferably, the cooling unit 21 condenses half or more of the organic solvent contained in the first gas to be treated. The separation unit 22 separates the condensed liquid organic solvent from the first gas to be treated.

The means by which the cooling unit 21 cools the first gas to be processed is not particularly limited. The cooling unit 21 may be, for example, a heat exchanger that cools the first to-be-treated gas by heat exchange between the first to-be-treated gas and a refrigerant such as cooling water, cold water, or brine. Cooling conditions such as the flow rate and temperature of the refrigerant can be appropriately determined depending on the organic solvent contained in the first gas to be treated.

The means by which the separation section 22 separates the liquid organic solvent is not particularly limited. For example, the separation unit 22 may use a network structure such as a demister, a filter, or a mesh that contacts and captures droplets.

Chamber 23 is a structure having a certain volume of space. The first treated gas from which the organic solvent has been separated in the separation section 22 passes through the chamber 23, which is a hollow space. A cooled processing gas containing a reduced concentration of organic solvent is discharged from the chamber 23 . The cooling process gas contains an uncondensed organic solvent. The cooled processing gas discharged from the condensation recovery device 10 flows through the third flow path F3. The third flow path F3 is a path for cooling processing gas from the condensation recovery device 10 to the confluence section 100.

The condensation recovery device 10 has a recovery tank 30. The recovery tank 30 is arranged below the separation section 22. The separation section 22 and the recovery tank 30 are connected by an eighth flow path F8. The liquid organic solvent condensed in the cooling unit 21 and captured in the separation unit 22 is collected in the recovery tank 30 via the eighth flow path F8 by the action of gravity. A liquid storage section 32 in which a liquid organic solvent is stored and an air layer section 31 above the liquid storage section 32 are formed in the recovery tank 30 . The diameter of the eighth flow path F8 may be smaller than the diameter of the third flow path F3.

The liquid organic solvent stored in the liquid storage section 32 is recovered as a recovery liquid L3. A pump (not shown) may be provided in the flow path of the recovery liquid L3. The recovery tank 30 may be provided with a liquid level gauge (not shown). When the liquid level gauge detects that the liquid level of the organic solvent in the recovery tank 30 has reached the upper limit, the pump may be activated to start collecting the recovery liquid L3. When the liquid organic solvent flows out of the recovery tank 30, the liquid level of the organic solvent in the recovery tank 30 decreases. When the liquid level gauge detects that the liquid level of the organic solvent has reached the lower limit, the pump may be stopped and collection of the collected liquid L3 may be stopped.

A cooling process gas blower 40 is provided in the third flow path F3. The cooled processing gas is sent out by the cooled processing gas blower 40 and sent into the merging section 100 .

The second to-be-treated gas discharged from the second to-be-treated gas discharge facility 92 is introduced into the confluence section 100 via the second flow path F2. The second flow path F2 is a path for introducing the second to-be-processed gas into the merging section 100, which is the merging point with the cooled processing gas. The merging section 100 merges the cooled processing gas after a portion of the organic solvent contained in the first processing gas has been condensed and recovered, and the second processing gas to form a third processing gas. .

A filter 101 is arranged at the outlet of the confluence section 100. The filter 101 is a filter for collecting relatively coarse dust contained in the gas before it is introduced into a third gas blower 42, which will be described later. A housing housing the filter 101 may be used as the merging section 100. The merging section 100 may have a box-like shape. A third flow path F3 is connected to a first surface (for example, an end surface) of the box-shaped merging section 100, and a second flow path F2 is connected to a second surface (for example, a ceiling surface) of the box-shaped merging section 100. Good too. The cooling processing gas and the second processing gas may join together on the upstream side of the filter 101 in the gas flow direction. By connecting the second flow path F2 and the third flow path F3 to form the merging portion 100 in a box-shaped housing, the merging portion 100 can be easily processed.

A third to-be-treated gas, which is a mixture of the cooling process gas and the second to-be-treated gas, is discharged from the confluence section 100 . The third to-be-treated gas discharged from the confluence section 100 flows through the fourth flow path F4. The fourth flow path F4 is a path for the third gas to be processed from the confluence section 100 to the adsorption/desorption processing device 50.

A gas heater 41 that heats the third gas to be processed is provided in the fourth flow path F4. If the humidity of the third gas to be processed is too high, the adsorption/desorption processing device 50 may not be able to exhibit sufficient performance. By raising the temperature of the third gas to be processed using the gas heater 41, the humidity of the third gas to be processed can be lowered, and the performance of the adsorption/desorption processing device 50 can be improved. A third gas blower 42 is provided in the fourth flow path F4. The third gas to be treated is sent out by the third gas blower 42 and sent to the adsorption/desorption processing device 50 .

The temperature transmitter 70 detects the temperature of the third gas to be processed flowing through the fourth flow path F4. The temperature transmitter 70 detects the temperature of the third gas to be processed upstream of the gas heater 41 (closer to the merging section 100). The temperature transmitter 70 transmits the detected temperature of the third gas to be processed to a control device (not shown). Based on the temperature of the third processed gas detected and transmitted by the temperature transmitter 70, feedback control is performed to adjust the flow rate and temperature of the refrigerant supplied to the cooling unit 21.

The saturation concentration of the organic solvent contained in the gas is determined by the temperature of the gas. The lower the temperature of the gas, the lower the concentration of organic solvent that may be contained in the gas. By monitoring the temperature of the third gas to be treated, it can be determined whether the concentration of the organic solvent contained in the third gas to be treated is below the lower explosive limit temperature. Controlling the cooling of the first to-be-treated gas in the cooling unit 21 based on the temperature of the third to-be-treated gas so that the concentration of the organic solvent contained in the third to-be-treated gas is below the lower explosive limit temperature. Can be done. This reduces the possibility that the third to-be-treated gas containing the organic solvent at a concentration exceeding the lower explosive limit concentration will be sent to the third to-be-treated gas blower 42, and the third to-be-treated gas will ignite in an air atmosphere. can.

The adsorption/desorption processing device 50 has a first processing tank 51 . The first processing tank 51 accommodates a hollow cylindrical adsorption/desorption element 52 . A damper 55 is provided at the bottom of the first processing tank 51. A damper 56 is provided above the adsorption/desorption element 52 in the first processing tank 51 . The adsorption/desorption processing device 50 has a second processing tank 53. The second processing tank 53 accommodates a hollow cylindrical adsorption/desorption element 54 . A damper 57 is provided at the bottom of the second processing tank 53. A damper 58 is provided in the second processing tank 53 above the adsorption/desorption element 54 .

The third gas to be treated passes through the adsorption/desorption elements 52, 54 from the outside in the radial direction toward the inside, so that the third gas to be treated comes into contact with the adsorption/desorption elements 52, 54. At this time, the organic solvent contained in the third gas to be treated is adsorbed by the adsorption/desorption elements 52 and 54. This cleans the third gas to be treated. The purified clean gas G9 is discharged to the outside from the fifth flow path F5. The fifth flow path F5 is a path for discharging to the outside of the organic solvent recovery system 1 the clean gas G9 that has been purified by adsorption processing of the organic solvent in the adsorption/desorption processing device 50.

A desorption gas G8 is introduced into the adsorption/desorption processing device 50 from outside the system. The sixth flow path F6 is a path for supplying the desorption gas, which is a heated gas, to the adsorption/desorption processing device 50. The desorption gas G8 may be water vapor. Alternatively, the desorption gas G8 may be an inert gas or heated air.

The switching valves 63 and 64 switch between supplying and stopping the desorption gas to the first processing tank 51 and supplying and stopping the desorption gas to the second processing tank 53. The switching valve 63 is provided in the path of the desorption gas to the first processing tank 51 . The switching valve 63 switches the path of the desorption gas to the first processing tank 51 to open or close. The switching valve 64 is provided in the path of the desorption gas to the second processing tank 53. The switching valve 64 switches the path of the desorption gas to the second processing tank 53 to open or close. The switching valves 63 and 64 are on-off valves. The switching valves 63 and 64 may be electromagnetic valves or electric valves.

The organic solvent adsorbed by the adsorption/desorption elements 52, 54 is desorbed from the adsorption/desorption elements 52, 54 by the desorption gas passing through the adsorption/desorption elements 52, 54 from the inside to the outside in the radial direction.

The third processing gas is supplied to either the first processing tank 51 or the second processing tank 53, and a process of adsorbing the organic solvent contained in the third processing gas is performed. At this time, a desorption gas is supplied to the other of the first treatment tank 51 and the second treatment tank 53 to perform a process of desorbing the organic solvent adsorbed on the adsorption/desorption elements 52 and 54. Adsorption of the organic solvent to the adsorption/desorption elements 52, 54 and desorption of the organic solvent from the adsorption/desorption elements 52, 54 are performed alternately.

Specifically, the damper 55 switches the path of the third gas to be processed to the first processing tank 51 to be opened or closed. The damper 56 switches the path of clean gas discharged from the first processing tank 51 to open or close. The damper 57 switches the path of the third gas to be processed to the second processing tank 53 to be opened or closed. The damper 58 switches the path of clean gas discharged from the second processing tank 53 to open or close. The opening and closing of the paths by the dampers 55 to 58 and the opening and closing of the switching valves 63 and 64 are linked to each other.

The damper 55 opens the path for the third gas to be processed to the first processing tank 51, and the damper 56 opens the path for the clean gas from the first processing tank 51. At this time, the damper 57 blocks the path of the third gas to be processed to the second processing tank 53, and the damper 58 blocks the path of the clean gas from the second processing tank 53. In addition, the switching valve 63 is closed to block the desorption gas path to the first processing tank 51, and the switching valve 64 is opened to open the desorption gas path to the second processing tank 53. As a result, the third processing gas is passed through the first processing tank 51 and the organic solvent contained in the third processing gas is adsorbed by the adsorption/desorption element 52, and the desorption gas is passed through the second processing tank 53. At the same time, the organic solvent is desorbed from the adsorption/desorption element 54 by passing through the organic solvent.

The damper 57 opens the path for the third gas to be processed to the second processing tank 53, and the damper 58 opens the path for the clean gas from the second processing tank 53. At this time, the damper 55 blocks the path of the third gas to be processed to the first processing tank 51, and the damper 56 blocks the path of the desorption gas to the first processing tank 51. In addition, the switching valve 64 is closed to block the desorption gas path to the second processing tank 53, and the switching valve 63 is opened to open the desorption gas path to the first processing tank 51. As a result, the third processing gas is passed through the second processing tank 53 and the organic solvent contained in the third processing gas is adsorbed by the adsorption/desorption element 54, and the desorption gas is passed through the first processing tank 51. At the same time, the organic solvent is desorbed from the adsorption/desorption element 52 by passing through the organic solvent.

As the adsorbent contained in the adsorption/desorption elements 52 and 54, for example, granular, powdered, fibrous, or honeycomb-shaped activated carbon, zeolite, silica gel, activated alumina, etc. can be used. In particular, it is preferable to use activated carbon fiber (ACF). For example, the adsorption/desorption elements 52 and 54 can be formed by fixing the ACF to a support or self-supporting it into a cylindrical shape and arranging it vertically within the core material.

A seventh flow path F7 is connected to the adsorption/desorption processing device 50. The desorption gas after the process of desorbing the organic solvent from the adsorption/desorption elements 52 and 54 is discharged from the adsorption/desorption processing device 50 via the seventh flow path F7. A second condensation recovery device 80 is provided in the seventh flow path F7. The second condensation and recovery device 80 is provided downstream of the adsorption/desorption processing device 50 in the flow direction of the desorption gas. The second condensation and recovery device 80 condenses and recovers a portion of the organic solvent contained in the desorption gas. The second condensation recovery device 80 has a second condensation section 81 and a second recovery tank 82.

The desorption gas introduced into the second condensation and recovery device 80 contains the organic solvent desorbed from the adsorption/desorption elements 52 and 54. The second condensing section 81 cools the desorption gas discharged from the adsorption/desorption processing device 50, thereby condensing a part of the organic solvent contained in the desorption gas. The condensed liquid organic solvent is collected in the second recovery tank 82 . The liquid organic solvent stored in the second recovery tank 82 is recovered as recovery liquid L4.

Although the adsorption/desorption processing device 50 has been described above as having two processing tanks in which hollow cylindrical adsorption/desorption elements are accommodated, there is no limitation on the number of processing tanks included in the adsorption/desorption processing device 50. Further, as the adsorption/desorption processing device 50, for example, a disk-type adsorption/desorption processing device as shown in JP-A No. 61-167430, or a vertical cylinder-type adsorption/desorption processing device as shown in JP-A-63-84616, for example. Alternatively, the system may include a horizontal cylinder type adsorption/desorption processing device as shown in WO2016/189958 and WO2017/170207, for example.

Return gas containing a reduced concentration of organic solvent is discharged from the second condensation recovery device 80 . The seventh flow path F7 is connected to the fourth flow path F4. The return gas is returned to the fourth flow path F4 via the seventh flow path F7 and mixed with the third gas to be processed.

[Second embodiment]
FIG. 2 is a diagram schematically showing the configuration of an organic solvent recovery system 1 according to the second embodiment. In the first embodiment, an example has been described in which the desorption gas is returned to the fourth flow path F4 as a return gas after condensing and recovering the organic solvent it contains. Instead of this example, as shown in FIG. 2, the organic solvent recovery system 1 may include a circulation path C1 through which the desorption gas G8 circulates.

The adsorption/desorption processing device 50 and the second condensation recovery device 80 (specifically, the second condensation section 81) are provided in the circulation path C1. The second condensation and recovery device 80 is provided downstream of the adsorption/desorption processing device 50 in the flow direction of the desorption gas G8 flowing through the circulation path C1. In this case, the desorption gas G8 may be an inert gas. For example, the desorption gas G8 may be nitrogen gas.

The circulation path C1 is also provided with a desorption gas blower 61 and a desorption heater 62. The desorption gas blower 61 is provided upstream of the adsorption/desorption processing device 50 in the flow direction of the desorption gas G8 flowing through the circulation path C1. The desorption gas G8 is sent out by the desorption gas blower 61 and sent to the adsorption/desorption processing device 50. In the flow direction of the desorption gas G8, the desorption heater 62 is provided downstream of the desorption gas blower 61 and upstream of the adsorption/desorption processing device 50. The desorption heater 62 heats the desorption gas G8 before being introduced into the adsorption/desorption processing device 50. The desorption heater 62 heats the low-temperature desorption gas G8 discharged from the second condensation recovery device 80.

The adsorption/desorption processing device 50 of the second embodiment is not provided with a damper. Switching valves 65A and 66A are provided in the fourth flow path F4, which is a path for the third gas to be processed introduced into the adsorption/desorption processing device 50. Switching valves 65B and 66B are provided in the fifth flow path F5, which is a path for the clean gas G9 from which the organic solvent has been removed from the third gas to be treated. Switching valves 63A and 64A are provided in the path of the desorption gas G8 introduced into the adsorption/desorption processing device 50. Switching valves 63B and 64B are provided in the path of the desorption gas G8 discharged from the adsorption/desorption processing device 50. The switching of opening and closing of the path by opening and closing of each switching valve is linked.

The switching valve 66A is opened to open the path for the third gas to be processed to the second processing tank 53, and the switching valve 66B is opened to open the path for the clean gas from the second processing tank 53. At this time, the switching valve 65A is closed to block the path of the third processed gas to the first processing tank 51, and the switching valve 65B is closed to block the path of the clean gas from the first processing tank 51. . In addition, the switching valve 63A is opened to open a path for introducing the desorption gas into the first processing tank 51, and the switching valve 63B is opened to open a path for discharging the desorption gas from the first processing tank 51. The switching valve 64A is closed to block the path for introducing the desorption gas into the second processing tank 53, and the switching valve 64B is closed to block the path for discharging the desorption gas from the second processing tank 53.

As a result, the third processing gas is passed through the second processing tank 53 and the organic solvent contained in the third processing gas is adsorbed by the adsorption/desorption element 54, and the desorption gas is passed through the first processing tank 51. At the same time, the organic solvent is desorbed from the adsorption/desorption element 52 by passing through the organic solvent.

The switching valve 65A is opened to open the path for the third gas to be processed to the first processing tank 51, and the switching valve 65B is opened to open the path for the clean gas from the first processing tank 51. At this time, the switching valve 66A is closed to block the path of the third gas to be processed to the second processing tank 53, and the switching valve 66B is closed to block the path of the clean gas from the second processing tank 53. . In addition, the switching valve 64A is opened to open a path for introducing the desorption gas into the second processing tank 53, and the switching valve 64B is opened to open a path for discharging the desorption gas from the second processing tank 53. The switching valve 63A is closed to block the path for introducing the desorption gas into the first processing tank 51, and the switching valve 63B is closed to block the path for discharging the desorption gas from the first processing tank 51.

As a result, the third processing gas is passed through the first processing tank 51 and the organic solvent contained in the third processing gas is adsorbed by the adsorption/desorption element 52, and the second processing tank 53 is supplied with the desorption gas. At the same time, the organic solvent is desorbed from the adsorption/desorption element 54 by passing through the organic solvent.

The condensation recovery device 10 has an L-shaped structure in which the direction in which the first gas to be processed flows from the cooling section 21 to the separation section 22 and the direction in which the first gas to be processed flows from the separation section 22 to the chamber 23 intersect. It may have. At this time, a funnel-shaped receiving part may be provided below the separation part 22 to receive the condensed organic solvent. Thereby, it is possible to suppress the condensed organic solvent droplets from flowing out from the condensing section 20 to the second flow path F2 and reaching the adsorption/desorption processing device 50.

[Action and effect]
Although some descriptions overlap with the above description, the characteristic configuration and effects of this embodiment are summarized as follows.

As shown in FIGS. 1 and 2, the gas to be treated by the organic solvent recovery system 1 includes the first gas to be treated discharged from the first gas exhaust facility 91 and the second gas to be treated gas discharged from the second gas exhaust facility. 92. The concentration of the organic solvent contained in the second gas to be treated is lower than the concentration of the organic solvent contained in the first gas to be treated. The first gas to be treated containing a high concentration of organic solvent is supplied to the condensation and recovery device 10, and most of the organic solvent contained in the first gas to be treated is condensed and recovered by the condensation and recovery device 10. The cooled processing gas containing uncondensed organic solvent is discharged from the condensation recovery device 10. The confluence section 100 merges the cooling process gas and the second process gas containing a low concentration organic solvent to form a third process gas. The third gas to be treated is supplied to the adsorption/desorption processing device 50, and the organic solvent contained in the third gas to be treated is adsorbed and removed from the third gas to be treated by the adsorption/desorption elements 52, 54, and clean gas is discharged. .

The organic solvent is recovered from the first gas to be treated containing a high concentration of organic solvent by condensing it. The organic solvent recovered by the condensation recovery device 10 is not decomposed because it is not heated. If the first to-be-treated gas contains a large amount of organic solvents that may decompose due to thermal history, it is possible to suppress the coloring and changes in physical properties of the recovered organic solvents. quality can be improved. Therefore, the recovered organic solvent can be effectively reused.

Furthermore, by removing a part of the organic solvent from the first gas to be treated and then combining it with the second gas to be treated, the concentration of the organic solvent contained in the third gas to be treated that is supplied to the adsorption/desorption processing device 50 can be reduced. reduced. Therefore, the weight of the adsorption/desorption elements 52 and 54 filled in the adsorption/desorption processing device 50 can be reduced, and the adsorption/desorption processing device 50 can be downsized. Furthermore, since the second condensation recovery device 80 is also downsized, space saving can be achieved for the organic solvent recovery system 1 as a whole.

In conventional systems, after a first gas to be treated and a second gas to be treated are combined, an organic solvent is adsorbed and recovered by an adsorption/desorption element, and then exhausted. In conventional systems, the concentration of organic solvent contained in the mixed gas of the first to-be-treated gas and the second to-be-treated gas is lower than a predetermined concentration that allows efficient condensation and recovery of the organic solvent, so Organic solvents cannot be condensed and recovered. In the conventional system, it is necessary to adsorb and remove the entire amount of organic solvent contained in the first gas to be treated and the second gas to be treated using an adsorption/desorption element. Therefore, the weight of the adsorption/desorption element increases.

In the organic solvent recovery system 1 of the embodiment, after a part of the organic solvent contained in the first gas to be treated is condensed and recovered by the condensation recovery device 10, the uncondensed organic solvent is adsorbed by the adsorption/desorption elements 52 and 54. It will be removed. In the organic solvent recovery system 1 of the embodiment, the weight of the adsorption/desorption elements 52 and 54 is significantly reduced compared to conventional systems. Therefore, the energy required to desorb the organic solvent from the adsorption/desorption elements 52 and 54 is significantly reduced, so that energy saving can be achieved.

Here, operating conditions of the organic solvent recovery system 1 for realizing energy reduction compared to conventional systems will be explained. FIG. 3 is a graph showing the energy reduction rate by the organic solvent recovery system 1 of the present disclosure. Let A be the quotient obtained by dividing the air volume of the second gas to be treated by the air volume of the first gas to be treated. B is the quotient obtained by dividing the concentration of the organic solvent contained in the first gas to be treated by the concentration of the organic solvent contained in the second gas to be treated. The recovery rate of the organic solvent contained in the first gas to be treated in the condensation recovery device 10 is assumed to be C (unit: %). The recovery rate C indicates the proportion of the organic solvent recovered in the condensation recovery device 10 among the organic solvents contained in the first gas to be treated.

The horizontal axis in the graph of FIG. 3 indicates the value of (A÷B÷C) expressed in logarithm. The vertical axis in the graph of FIG. 3 indicates the energy reduction rate (unit: %). Organic solvent recovery in an embodiment in which the organic solvent in the first gas to be treated is condensed and recovered, then combined with the second gas to be treated to form a third gas to be treated, and the organic solvent in the third gas to be treated is removed by adsorption. Let E be the amount of energy input into the system 1 for the process of recovering the organic solvent. E shall be. In this case, the energy reduction rate is expressed as (1-E/E0)×100.

If the energy reduction rate is greater than 0%, the amount of energy input is reduced compared to the conventional system, and energy saving can be achieved, which means that the system is more advantageous than the conventional system. As shown in the graph of FIG. 3, energy saving can be achieved within a range where the value of (A÷B÷C) is greater than 0 and less than or equal to 0.033.

In other words, as shown in FIG. 3, when the organic solvent is recovered from the gas to be treated including the first gas to be treated and the second gas to be treated by the organic solvent recovery system 1 of the embodiment, the calculation formula 0 By setting the operating condition to satisfy <(A÷B÷C)≦0.033, the amount of energy used can be reduced, and the energy consumption can be suppressed more than in the conventional system. Note that the conventional system does not include the condensation recovery device 10 and the recovery rate C in the condensation recovery device 10 is 0%, so the above calculation formula cannot be used.

As shown in FIGS. 1 and 2, the organic solvent recovery system 1 cools the desorption gas discharged from the adsorption/desorption processing device 50 to condense and recover the organic solvent contained in the desorption gas. , a second condensation recovery device 80 may be provided. The organic solvent contained in the third gas to be treated is adsorbed and removed by the adsorption/desorption elements 52 and 54, and a desorption gas is introduced into the adsorption/desorption processing device 50 to desorb the organic solvent from the adsorption/desorption elements 52 and 54. The organic solvent contained in the desorption gas discharged from the adsorption/desorption processing device 50 is condensed and recovered by the second condensation and recovery device 80 . Thereby, the recovery rate of the organic solvent by the organic solvent recovery system 1 can be improved.

When the organic solvent contained in the gas to be treated contains components that are easily decomposed due to thermal history, the second condensation and recovery device 80 is provided to remove the organic solvent desorbed from the adsorption/desorption elements 52 and 54. It can be condensed and recovered as is. The easily decomposed components can be condensed and recovered by the second condensation recovery device 80 without returning them to the first flow path F1 at the system inlet.

The desorption gas may be water vapor. By introducing high temperature water vapor into the adsorption/desorption processing device 50, the organic solvent adsorbed on the adsorption/desorption elements 52, 54 can be reliably desorbed from the adsorption/desorption elements 52, 54. When the organic solvent contained in the gas to be treated contains components that are easily decomposed due to thermal history, the structure is equipped with the second condensation recovery device 80 and uses water vapor as the desorption gas, so that the water vapor can be adsorbed and desorbed. The organic solvent desorbed from the elements 52 and 54 can be condensed and recovered as is. The easily decomposed components can be condensed and recovered by the second condensation recovery device 80 without returning them to the first flow path F1 at the system inlet.

The desorption gas may be an inert gas. As shown in FIG. 2, by heating the inert gas with the desorption heater 62 and introducing it into the adsorption/desorption treatment device 50, the organic solvent adsorbed on the adsorption/desorption elements 52, 54 is reliably transferred to the adsorption/desorption elements 52, 54. , 54. When the to-be-treated gas contains an organic solvent with a component that is relatively difficult to thermally decompose, an inert gas is used as the desorption gas, so that the desorption gas discharged from the adsorption/desorption processing device 50 is removed from the system. The organic solvent contained in the desorption gas can be returned to the first flow path F1 at the inlet and condensed and recovered by the condensation recovery device 10.

As shown in FIG. 2, an adsorption/desorption processing device 50 and a second condensation recovery device 80 may be provided in the circulation path C1 through which the desorption gas G8 circulates. The organic solvent can be desorbed from the adsorption/desorption elements 52 and 54 by the desorption gas G8 circulating through the circulation path C1, and the desorption gas G8 can be condensed and recovered in the second condensation and recovery device 80 without returning to the system inlet. can.

As shown in FIG. 2, a desorption heater 62 that heats the desorption gas G8 discharged from the second condensation recovery device 80 may be provided in the circulation path C1. By heating the desorption gas G8 with the desorption heater 62 and introducing it into the adsorption/desorption treatment device 50, the organic solvent adsorbed on the adsorption/desorption elements 52, 54 can be reliably desorbed from the adsorption/desorption elements 52, 54. can.

As shown in FIGS. 1 and 2, the temperature transmitter 70 may detect and transmit the temperature of the third gas to be processed. By performing feedback control that adjusts the flow rate and temperature of the refrigerant supplied to the cooling unit 21 based on the temperature of the third gas to be treated, the concentration of the organic solvent contained in the third gas to be treated can be reduced to an explosive level. The temperature can be reliably maintained below the critical temperature.

Examples will be described below. First, a first gas to be treated containing a highly concentrated organic solvent and a second gas to be treated containing an organic solvent at a lower concentration than the first gas to be treated were prepared. Table 1 shows the conditions for the first gas to be treated and the second gas to be treated in the organic solvent recovery systems of Examples and Comparative Examples.

The organic solvent recovery system of the example was as in the embodiment described above. That is, the organic solvent contained in the first to-be-treated gas is condensed and recovered by a condensation recovery device, and the cooled to-be-treated gas containing the uncondensed organic solvent and the second to-be-treated gas containing a low concentration of organic solvent are combined. A mode in which the organic solvents are combined and supplied to an adsorption/desorption processing device, the organic solvent is adsorbed and removed by an adsorption/desorption element, and the organic solvent contained in the desorption gas discharged from the adsorption/desorption processing device is recovered by a second condensation recovery device. did.

On the other hand, in the organic solvent recovery system of the comparative example, after mixing the first to-be-treated gas and the second to-be-treated gas according to the conventional system, the same adsorption/desorption treatment device and the second condensation and recovery device as in the example The organic solvent was recovered in this manner.

The set temperature for condensing the organic solvent in the condensation recovery device was -19°C. Water vapor was used as a desorption gas for desorbing the organic solvent from the adsorption/desorption element in the adsorption/desorption processing device. The temperature of the steam was 120° C. at normal pressure, and the amount of steam used was 34 kg/min. The set temperature for condensing the organic solvent in the second condensation recovery device was 32°C. Table 2 shows the amount of energy consumed by each device when performing the process of recovering organic solvents using the organic solvent recovery systems of Examples and Comparative Examples under these conditions.

In this example, the quotient A obtained by dividing the air volume of the second gas to be treated by the air volume of the first gas to be treated is 30, and the concentration of the organic solvent contained in the first gas to be treated is equal to the concentration of the organic solvent contained in the second gas to be treated. The quotient B divided by the concentration of the organic solvent to be treated is 100, the recovery rate C of the organic solvent contained in the first gas to be treated in the condensation recovery device 10 is 90, and A÷B÷C=0.003. Ta.

As shown in Table 2, compared to the total amount of energy consumed by each device in the organic solvent recovery system of the example, the total amount of energy consumed by each device in the organic solvent recovery system of the comparative example was 2.5 times or more. Therefore, it was shown that the organic solvent recovery system of the example can recover high-quality organic solvents while using significantly less energy than the comparative example that follows the conventional system.

The embodiments and examples disclosed herein are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated not by the above description but by the claims, and it is intended that equivalent meanings and all changes within the scope of the claims are included.

1 organic solvent recovery system, 10 cooling condensation device, 20 condensation section, 21 cooling section, 22 separation section, 23 chamber, 30 recovery tank, 31 gas layer section, 32 liquid storage section, 40 cooling processing gas blower, 41 gas heater, 42 Third processing gas blower, 50 Adsorption/desorption processing device, 51 First processing tank, 52, 54 Adsorption/desorption element, 53 Second processing tank, 55 to 58 Damper, 61 Desorption gas blower, 62 Desorption heater, 63 , 63A, 63B, 64, 64A, 64B, 65A, 65B, 66A, 66B switching valve, 70 temperature transmitter, 80 second condensation recovery device, 81 second condensation section, 82 second recovery tank, 91 first to be treated Gas discharge equipment, 92 second gas discharge equipment to be treated, 100 merging section, 101 filter, C1 circulation flow path, F1 first flow path, F2 second flow path, F3 third flow path, F4 fourth flow path.

Claims (8)

An organic solvent recovery system that separates and recovers an organic solvent from a gas to be treated containing an organic solvent, the system comprising:
The to-be-treated gas includes a first to-be-treated gas and a second to-be-treated gas containing a lower concentration of the organic solvent than the first to-be-treated gas,
Condensation recovery in which the organic solvent contained in the first gas to be treated is condensed by cooling the first gas to be treated and is discharged as a cooled gas in which the concentration of the organic solvent contained therein is reduced. a device;
a merging section that merges the cooling processing gas and the second processing gas to form a third processing gas;
an adsorption/desorption element that adsorbs and desorbs the organic solvent contained in the third gas to be treated, and adsorption of the organic solvent to the adsorption/desorption element by introducing the third gas to be treated, and a desorption gas; An organic solvent recovery system, comprising: an adsorption/desorption processing device that alternately desorbs the organic solvent from the adsorption/desorption element by introducing a. A is the quotient obtained by dividing the air volume of the second gas to be treated by the air volume of the first gas to be treated, and the concentration of the organic solvent contained in the first gas to be treated is the concentration of the organic solvent contained in the second gas to be treated. When the quotient divided by the concentration of the organic solvent is B, and the recovery rate of the organic solvent contained in the first gas to be treated in the condensation recovery device is C (%),
0<(A÷B÷C)≦0.033
The organic solvent recovery system according to claim 1, which satisfies the following. Claim 1 or claim 1, further comprising a second condensation recovery device that cools the desorption gas discharged from the adsorption/desorption processing device to condense and recover the organic solvent contained in the desorption gas. The organic solvent recovery system according to item 2. The organic solvent recovery system according to claim 3, wherein the desorption gas is water vapor. The organic solvent recovery system according to claim 1 or 2, wherein the desorption gas is an inert gas. The organic solvent recovery system according to claim 3, further comprising a circulation path through which the desorption gas circulates, and wherein the adsorption/desorption processing device and the second condensation recovery device are provided in the circulation path. The organic solvent recovery system according to claim 6, further comprising a heating unit provided in the circulation path and heating the desorption gas discharged from the second condensation recovery device. The organic solvent recovery system according to claim 1 or 2, further comprising a temperature transmitter that detects and transmits the temperature of the third gas to be treated.

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