Organic solvent recovery system

Abstract

An organic solvent recovery system (1) comprises two treatment tanks (101, 102), each containing a first adsorbent, a steam supply unit (110), and an extraction path (L31, L32), an organic solvent recovery device (100) having an adsorption unit (202) and a desorption unit (203) including a second adsorbent (201A), and a return path (400) for returning the concentrated gas to the organic solvent recovery device (100), wherein the second adsorbent (201A) comprises an activated carbon fiber nonwoven fabric. The activated carbon fiber nonwoven fabric has a fiber diameter of 11 μm or more and 120 μm or less, a toluene adsorption rate of 25 wt.% or more and 75 wt.% or less, and a total weight per unit area of ​​200 g / m² or more and 6000 g / m² or less.

Description

Technology Field

[0001] The present disclosure relates to an organic solvent recovery system. Background Technology

[0002] Conventionally, a system for recovering an organic solvent from a gas containing an organic solvent is known. For example, Japanese Patent Publication No. 2014-147863 (hereinafter referred to as “Patent Document 1”) discloses a gas treatment apparatus comprising three treatment tanks, a gas supply unit for the gas to be treated, a connecting flow path, a steam supply unit, and a diluted gas supply flow path.

[0003] The gas supply unit supplies the gas to be treated (raw gas) containing an organic solvent to each treatment tank. Each treatment tank has an adsorbent (such as activated carbon fiber) capable of adsorbing the organic solvent contained in the gas to be treated. The connecting flow path connects two of the three treatment tanks in series.

[0004] Specifically, the gas to be treated, which is processed in the treatment tank used in the first adsorption process, is introduced into the treatment tank used in the second adsorption process through a connecting channel, where the organic solvent is also recovered from the gas to be treated. The gas after processing in the second adsorption process is discharged out of the system as clean air. The steam supply unit supplies steam to each treatment tank to desorb the organic solvent adsorbed on the adsorbent from the adsorbent. The steam supply unit supplies steam to the remaining treatment tanks that are not used in the first and second adsorption processes.

[0005] That is, in the gas treatment device described in Patent Document 1, an adsorption process is carried out continuously in two treatment tanks, and during that time, a desorption process is carried out in the remaining treatment tank. The treatment tank in which the desorption process is carried out is then used in the second adsorption process, and subsequently used in the first adsorption process. The dilution gas supply path is a path for supplying dilution gas (such as ambient air or nitrogen gas) to the connecting path. The dilution gas is supplied to the treatment tank to dry the adsorbent material of the treatment tank used in the second adsorption process after the desorption process.

[0006] Japanese Patent Publication No. 2014-240052 (hereinafter referred to as “Patent Document 2”) discloses an organic solvent recovery system comprising a first adsorption / desorption device having two treatment tanks and a second adsorption / desorption device for recovering an organic solvent contained in a gas to be treated discharged from one of the first adsorption / desorption devices.

[0007] Each treatment tank has a first adsorption / desorption element (such as activated carbon fiber) capable of adsorbing organic solvents contained in the gas to be treated. In each treatment tank, the adsorption process and the desorption process are performed alternately. The second adsorption / desorption device has a second adsorption / desorption element capable of adsorbing organic solvents contained in the gas to be treated discharged from the treatment tank.

[0008] The second adsorption / desorption device has a first treatment unit that adsorbs an organic solvent contained in the gas to be treated by a second adsorption / desorption element, and a second treatment unit that desorbs the organic solvent adsorbed by the second adsorption / desorption element from the second adsorption / desorption element. The gas to be treated discharged from the second treatment unit returns to a flow path that supplies the gas to be treated (original gas) to each treatment tank of the first adsorption / desorption device. Prior art literature

[0009] Japanese Patent Publication No. 2014-147863 Japanese Patent Publication No. 2014-240052 The problem to be solved

[0010] In the gas treatment device described in Patent Document 1, the removal rate of organic solvents is increased by continuously performing an adsorption process in two treatment tanks. In the organic solvent recovery system described in Patent Document 2, the removal rate of organic solvents is increased by continuously performing an adsorption process in either the treatment tank of the first adsorption / desorption device and the first treatment section of the second adsorption / desorption device. However, there is a need to further increase the removal rate of organic solvents in such organic solvent recovery systems.

[0011] In response to such requirements, it is considered that, for example, an adsorption process is performed continuously in two treatment tanks as described in Patent Document 1, and then an additional adsorption process is performed using a second adsorbent as described in Patent Document 2. In this case, the gas to be treated containing organic solvent desorbed from the second adsorbent is returned to the flow path that supplies the gas to be treated (original gas) to the treatment tank.

[0012] However, in that case, since both the source gas and the gas to be treated, containing organic solvents desorbed from the second adsorbent, are supplied to the treatment tank used in the first adsorption process, and dilution gas is additionally supplied to the treatment tank used in the second adsorption process, the airflow supplied to each treatment tank increases. Because it is necessary to design each treatment tank to be larger to match this airflow, an overall increase in the size of the facility is inevitable.

[0013] The objective of the present disclosure is to provide an organic solvent recovery system capable of suppressing the overall increase in size of the facility when improving the removal rate of organic solvents. means of solving the problem

[0014] According to any aspect of the organic solvent recovery system of the present disclosure, the system comprises: two treatment tanks, each comprising a first adsorbent capable of adsorbing and desorbing an organic solvent contained in a gas to be treated, and alternately performing adsorption of the organic solvent onto the first adsorbent and desorption of the organic solvent from the first adsorbent by steam; a steam supply unit for introducing steam into one of the two treatment tanks selected from the two treatment tanks; an organic solvent recovery device having an extraction channel for discharging the gas to be treated introduced from the other treatment tank as a first treatment gas in which the organic solvent is adsorbed by the first adsorbent of the other treatment tank; an adsorption unit comprising a second adsorbent capable of adsorbing and desorbing the organic solvent, adsorbing the organic solvent contained in the first treatment gas from the extraction channel by the second adsorbent and discharging the second treatment gas; and a device for desorbing the organic solvent adsorbed by the second adsorbent from the second adsorbent and concentrating it. An organic solvent concentration device having a desorption section that discharges as gas, and a return path that returns the concentrated gas to the organic solvent recovery device, wherein the second adsorbent comprises an activated carbon fiber nonwoven fabric, and the activated carbon fiber nonwoven fabric has a fiber diameter of 11 μm or more and 120 μm or less, a toluene adsorption rate of 25 wt.% or more and 75 wt.% or less, and a total weight per unit area of ​​200 g / m² or more and 6000 g / m² or less.

[0015] The above organic solvent concentration device is configured such that the second adsorbent is placed on a disc-shaped adsorption rotor that rotates around a main axis.

[0016] The above organic solvent concentration device is configured such that the second adsorbent is arranged in multiple circumferential directions around the shaft of a hollow cylindrical rotor that rotates around the shaft.

[0017] The organic solvent recovery device comprises at least three treatment tanks, and the steam supply unit further comprises a connecting channel that introduces steam into a treatment tank selected from a plurality of treatment tanks and connects the remaining plurality of treatment tanks in series.

[0018] The above organic solvent recovery device further comprises a dilution gas supply channel for supplying dilution gas to the above-mentioned connection channel. Effects of the invention

[0019] According to this disclosure, an organic solvent recovery system can be provided that can suppress the increase in the size of the entire facility when the recovery rate of organic solvents is improved. Brief explanation of the drawing

[0020] Figure 1 is a diagram schematically showing the configuration of an organic solvent recovery system of Embodiment 1. FIG. 2 is a diagram schematically showing the flow of gas in a state where the first adsorption process is performed in the first treatment tank and the desorption process is performed in the second treatment tank. Figure 3 is a diagram schematically showing the configuration of an organic solvent recovery system of Embodiment 2. FIG. 4 is a cross-sectional view of the adsorbent of Embodiment 2. Figure 5 is a cross-sectional view of an adsorbent following the VV line shown in Figure 4. Figure 6 is an enlarged cross-sectional view of the main part of the adsorption rotor shown in Figure 5. FIG. 7 is a schematic diagram showing the gas flow in the organic solvent recovery system of Embodiment 3. FIG. 8 is a schematic diagram showing the flow of gas in the organic solvent recovery system of Embodiment 4. Specific details for implementing the invention

[0021] Organic solvent recovery systems of each embodiment based on the present disclosure will be described below with reference to the drawings. In the embodiments described below, when referring to the number, quantity, etc., the scope of the present disclosure is not necessarily limited to such number, quantity, etc., unless specifically stated otherwise. Identical parts and equivalent parts are assigned the same reference numerals, and duplicate descriptions may not be repeated. It is intended from the outset to use appropriately combined configurations in the embodiments.

[0022] [Embodiment 1]

[0023] FIG. 1 is a schematic diagram showing the configuration of an organic solvent recovery system of Embodiment 1. As shown in FIG. 1, the organic solvent recovery system (1) comprises an organic solvent recovery device (100), an organic solvent concentration device (200), a transfer path (300), and a return path (400). The organic solvent recovery system (1) performs the removal and recovery of an organic solvent from a gas to be treated containing an organic solvent in the organic solvent recovery device (100). Afterward, the system performs the removal and concentration of an organic solvent in the organic solvent concentration device (200) for the first treated gas discharged from the organic solvent recovery device (100), and returns the concentrated gas discharged from the organic solvent concentration device (200) back to the organic solvent recovery device (100) through the return path (400).

[0024] Organic solvents include methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, trichloroethylene, tetrachloroethylene, O-dichlorobenzene, m-dichlorobenzene, Freon-112, Freon-113, HCFC, HFC, propyl bromide, butyl iodide, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, vinyl acetate, methyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, diethyl carbonate, ethyl formate, diethyl ether, dipropyl ether, tetrahydrofuran, dibutyl ether, anisole, methanol, ethanol, isopropanol, n-butanol, 2-butanol, isobutanol, t-butanol, allyl alcohol, pentanol, heptanol, ethylene glycol, diethylene glycol, phenol, O-cresol, It refers to m-cresol, p-cresol, xylenol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, poron, acrylonitrile, n-hexane, isohexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, n-nonane, isononane, decane, dodecane, undecane, tetradecane, decalin, benzene, toluene, m-xylene, p-xylene, o-xylene, ethylbenzene, 1,3,5-trimethylbenzene, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide, etc.

[0025] The organic solvent recovery device (100) is a facility for removing and recovering an organic solvent from a gas to be treated. The gas to be treated is supplied to the organic solvent recovery device (100) from a gas supply source (not shown) provided outside the system of the organic solvent recovery device (100). The organic solvent recovery device (100) has two treatment tanks (101, 102), a gas supply path (L10), an extraction path (L31, L32), a steam supply path (L41, L42), an organic solvent recovery path (L51, L52), a separator (120), and a re-supply path (L60).

[0026] Each treatment tank (101, 102) has a first adsorbent (101A, 102A) capable of adsorbing and desorbing an organic solvent. As the first adsorbent (101A, 102A), granular activated carbon, honeycomb-shaped activated carbon, zeolite, and activated carbon fiber are used, but it is preferable to use activated carbon fiber. Each treatment tank (101, 102) has an opening / closing damper (V101, V102) that switches the supply / non-supply of the gas to be treated to a supply port, and an opening / closing damper (V201, V202) that switches the discharge / non-discharge of the gas to be treated after passing through the first adsorbent (101A, 102A).

[0027] In each treatment tank (101, 102), the adsorption of an organic solvent by a first adsorbent (101A, 102A) and the desorption of an organic solvent from the first adsorbent (101A, 102A) are performed alternately. The details are as follows. In one of the two treatment tanks (101, 102), an adsorption process is performed in which an organic solvent is adsorbed by the first adsorbent from a gas to be treated supplied from a gas supply source to be treated, and in the other treatment tank, a desorption process is performed in which an organic solvent is desorbed from the first adsorbent. In each treatment tank (101, 102), the desorption process and the adsorption process are repeated sequentially. FIG. 1 illustrates a state in which the adsorption process is performed in the first treatment tank (101) and the desorption process is performed in the second treatment tank (102).

[0028] The gas supply path (L10) for the gas to be treated is a path for supplying the gas to be treated to each treatment tank (101, 102). The upstream end of the gas supply path (L10) for the gas to be treated is connected to a gas supply source. A blower (F1) is provided in the gas supply path (L10) for the gas to be treated. In the upstream portion of the gas supply path (L10) for the gas to be treated, a cooler (C1) and a heater (H1) are provided to adjust the temperature and humidity of the gas to be treated flowing into each treatment tank (101, 102) to a desired range. These devices can be installed appropriately according to the pressure, temperature, and humidity of the gas to be treated.

[0029] The gas supply path (L10) for the gas to be treated has branch paths (L11, L12) for supplying the gas to be treated to each treatment tank (101, 102). An opening / closing valve (V11) is provided in the branch path (L11). An opening / closing valve (V12) is provided in the branch path (L12).

[0030] The extraction passage (L31, L32) is a passage for extracting the first treatment gas, which is the gas to be treated after adsorption treatment in each treatment tank (101, 102). The extraction passage (L31, L32) is connected to the treatment gas outlet in each treatment tank (101, 102). An opening / closing valve (V31) is provided in the first extraction passage (L31). An opening / closing valve (V32) is provided in the second extraction passage (L32). Each extraction passage (L31, L32) has a merging passage (L30) that merges with each other.

[0031] The steam supply path (L41, L42) is a path for supplying steam to each treatment tank (101, 102) to desorb the organic solvent adsorbed on the first adsorbent (101A, 102A) from the first adsorbent (101A, 102A). The steam is supplied from the steam supply unit (110). The steam supply unit (110) may be provided within the organic solvent recovery device (100) or outside the system of the organic solvent recovery device (100).

[0032] The first steam supply path (L41) connects the steam supply unit (110) and the first treatment tank (101). An opening / closing valve (V41) is provided in the first steam supply path (L41). The second steam supply path (L42) connects the steam supply unit (110) and the second treatment tank (102). An opening / closing valve (V42) is provided in the second steam supply path (L42).

[0033] The organic solvent recovery channels (L51, L52) are channels for recovering water vapor (desorption gas) containing organic solvent desorbed from the first adsorbent (101A, 102A). Each organic solvent recovery channel (L51, L52) is connected to each treatment tank (101, 102). Each organic solvent recovery channel (L51, L52) has a merging channel (L50) that merges with each other. A condenser (122) is provided in the merging channel (L50). The condenser (122) condenses the desorption gas by cooling the desorption gas flowing through the merging channel (L50) and discharges the condensate (a mixture of water and liquid organic solvent generated by the condensation of the desorption gas).

[0034] A separator (120) is provided at the downstream end of the confluence channel (L50). Condensate flows into the separator (120). Subsequently, within the separator (120), the condensate is phase-separated into a liquid phase of separated wastewater (condensate of water vapor that may contain a small amount of organic solvent) and a liquid phase of recovered solvent, and the recovered solvent is discharged out of the system of the organic solvent recovery device (100). A space (vent gas) in which gaseous organic solvent exists is formed at the top of the separator (120).

[0035] The recirculation channel (L60) is a channel connecting the separator (120) and the gas supply channel (L10). The upstream end of the recirculation channel (L60) is connected to the upper part of the separator (120) (the part of the separator (120) where gaseous organic solvent exists). The downstream end of the recirculation channel (L60) is connected to the upstream part of the cooler (C1) in the gas supply channel (L10). Therefore, it is preferable that the gaseous organic solvent present in the separator (120) be supplied back to each treatment tank (101, 102) through the recirculation channel (L60) and the gas supply channel (L10).

[0036] The wastewater treatment facility (130) is a facility that removes organic solvents contained in the separated wastewater. It is supplied from the liquid phase of the separated wastewater of the separator (120), removes organic solvents from the separated wastewater, and discharges the treated water outside the system of the organic solvent recovery device (100). Specific wastewater treatment facilities (130) may include aeration facilities that volatilize organic solvents contained in the separated wastewater by aeration treatment of the separated wastewater and separate it into aeration gas containing organic solvents and treated water. The aeration gas is supplied through the aeration gas supply path (L61) to the upstream portion of the cooler (C1) in the gas supply path (L10). Although not illustrated, a dehumidification means may be provided in the aeration gas supply path for the purpose of removing moisture from the aeration gas.

[0037] Next, an organic solvent concentration device (200) will be described. The organic solvent concentration device (200) is a facility that also removes an organic solvent from a first treatment gas discharged from an organic solvent recovery device (100). The organic solvent concentration device (200) has an adsorbent (201).

[0038] The adsorbent (201) has a second adsorbent (201A) capable of adsorbing an organic solvent contained in a first treatment gas discharged through a confluence channel (L30). The adsorbent (201) has an adsorption section (202) that adsorbs the organic solvent contained in the first treatment gas by the second adsorbent (201A), and a desorption section (203) that desorbs the organic solvent adsorbed on the second adsorbent (201A) from the second adsorbent (201A). By passing the first treatment gas through the adsorption section (202), a second treatment gas, which is a clean gas from which the organic solvent has been removed, can be discharged. After adsorption is completed, a heated gas with a smaller volume than the first treatment gas is passed through the desorption section (203) to desorb the organic solvent adsorbed on the second adsorbent (201A), thereby discharging a concentrated gas in which the organic solvent is concentrated.

[0039] In this embodiment, the adsorbent (201) is a disc-shaped (disk-shaped) rotor. The adsorbent (201) rotates between the adsorption part (202) and the desorption part (203) to switch between adsorption and desorption. The structure of this adsorbent (201) is the same as that described in Patent Document 2.

[0040] The transfer path (300) is a path for sending the gas to be treated from the organic solvent recovery device (100) to the organic solvent concentration device (200). The upstream end of the transfer path (300) is connected to the confluence path (L30). The downstream end of the transfer path (300) is connected to the adsorption part (202) of the adsorbent (201). That is, the transfer path (300) is a path for sending the first treated gas to the adsorption part (202).

[0041] A blower (F3) is provided in the transfer path (300). In the upstream portion of the blower (F3) in the transfer path (300), a cooler (C2) and a heater (H2) are provided to adjust the humidity of the first treatment gas flowing into the adsorption section (202) to a desired range.

[0042] The return path (400) is a path for returning concentrated gas from the organic solvent concentration device (200) to the organic solvent recovery device (100). The return path (400) is connected to the desorption section (203) and the gas supply path (L10). Specifically, the downstream end of the return path (400) is connected to the upstream portion of the cooler (C1) and heater (H1) in the gas supply path (L10).

[0043] In the return path (400), a blower (F5) is provided. The airflow of the blower (F5) is set to about one-tenth of the airflow of the blower (F3).

[0044] In this embodiment, the organic solvent concentration device (200) discharges the second treatment gas (clean gas) discharged from the adsorption unit (202) to the outside through the clean gas discharge path (L202). The organic solvent concentration device (200) further has a connection path (L80) and a heater (H3).

[0045] The connecting channel (L80) connects the clean gas discharge channel (L202) and the desorption section (203), and allows a portion of the second treatment gas to be used for desorption in the desorption section (203). A blower (F4) is provided in the connecting channel (L80). The configuration may also utilize outside air for desorption in the desorption section (203).

[0046] A heater (H3) is provided in the connection path (L80). More specifically, the heater (H3) is provided in the downstream portion of the blower (F4) within the connection path (L80). For example, the heater (H3) heats the second treatment gas flowing through the connection path (L80) so that the temperature of the second treatment gas is approximately 130°C to 180°C. In this case, the temperature of the second treatment gas discharged from the desorption unit (203) is approximately 60°C to 80°C.

[0047] An activated carbon fiber nonwoven fabric is used as the second adsorbent (201A). As the first treatment gas passes through the interior of the activated carbon fiber nonwoven fabric, the collision efficiency with the material to be treated is improved, thereby improving the adsorption efficiency. Meanwhile, when supplying the heated second treatment gas to desorb the adsorbed material to be treated, the contact efficiency between the activated carbon fiber nonwoven fabric and the heated second treatment gas is improved, and since thermal energy is efficiently transferred to the activated carbon fiber nonwoven fabric, the volume of the heated second treatment gas can be reduced. In other words, by making the second adsorbent (201A) an activated carbon fiber nonwoven fabric, high removal performance can be achieved, making high concentration even more possible.

[0048] The fiber diameter of the activated carbon fiber constituting the activated carbon fiber nonwoven fabric is preferably 11㎛ or more and 120㎛ or less. If the fiber diameter is less than 11㎛, the pressure loss increases, making it impossible to sufficiently ventilate the gas. If the fiber diameter exceeds 120㎛, the collision efficiency with the material to be treated decreases, leading to a decrease in adsorption efficiency and a decline in adsorption performance. Since the contact efficiency with the heated second treatment gas decreases, it becomes difficult for thermal energy to be transferred to the activated carbon fiber nonwoven fabric, resulting in an increase in the airflow volume of the heated second treatment gas. Furthermore, the flexibility of the activated carbon fiber nonwoven fabric decreases, making processing difficult. From the perspective of the balance of pressure loss, adsorption performance, heated airflow volume, and processability, the fiber diameter is more preferably 15㎛ or more and 120㎛ or less.

[0049] The toluene adsorption rate of the activated carbon fiber nonwoven fabric is preferably 25 wt.% or higher and 75 wt.% or lower. If the toluene adsorption rate is 25 wt.% or lower, the adsorption performance deteriorates. Activated carbon fibers with a high toluene adsorption rate have a large total pore volume, resulting in a lower bulk density of the fibers. Consequently, if the toluene adsorption rate exceeds 75 wt.%, the tensile strength of the single filament decreases, and the tensile strength and compressive modulus of the activated carbon fiber nonwoven fabric decrease, leading to a decrease in shape stability. From the perspective of balancing adsorption performance and shape stability, the toluene adsorption rate is more preferably 30 wt.% or higher and 70 wt.% or lower.

[0050] The total weight per unit area of ​​the activated carbon fiber nonwoven fabric is preferably 200 g / m² or more and 6,000 g / m² or less. If the total weight per unit area is less than 200 g / m², the collision efficiency with the material to be treated deteriorates, resulting in reduced adsorption performance. If the total weight per unit area exceeds 6,000 g / m², the pressure loss increases, making it impossible to sufficiently ventilate the gas. From the perspective of the balance between adsorption performance and pressure loss, the total weight per unit area is more preferably 1,200 g / m² or more and 4,000 g / m² or less.

[0051] The bulk density of the activated carbon fiber nonwoven fabric is preferably 50 kg / m³ or more and 200 kg / m³ or less. If the bulk density is less than 50 kg / m³, the compression ratio of the nonwoven fabric increases, making processing difficult. If the bulk density exceeds 200 kg / m³, the pressure loss of the nonwoven fabric increases, making it impossible to sufficiently ventilate gas. From the perspective of the balance between processability and pressure loss, the bulk density is more preferably 60 kg / m³ or more and 150 kg / m³ or less.

[0052] The compression ratio of the activated carbon fiber nonwoven fabric is preferably 30% or less, and more preferably 25% or less. If the compression ratio exceeds 30%, processing becomes difficult. The lower limit of the compression ratio is typically 5% or more.

[0053] The compressive modulus of the activated carbon fiber nonwoven fabric is preferably 80% or higher, and more preferably 85% or higher. If the compressive modulus is less than 80%, the activated carbon fiber nonwoven fabric becomes misaligned over time due to repeated airflow with and without airflow or repeated airflow in the counter-flow direction, causing gas short-passing and premature decrease in the adsorption efficiency for the treated material. The upper limit of the compressive modulus is typically 99% or less.

[0054] The method for manufacturing the precursor nonwoven fabric of the activated carbon fiber nonwoven fabric is not particularly limited, and known methods may be appropriately adopted. Examples of methods for manufacturing the nonwoven fabric include the spunbond method, meltblow method, spunlace method, needle punch method, thermal bond method, chemical bond method, etc. Among these, the needle punch method is preferred.

[0055] Activated carbon fiber nonwoven fabric can be manufactured by carbonizing a precursor nonwoven fabric using a known method and then reactivating it. Specifically, methods such as gas reactivation and chemical reactivation may be used, but gas reactivation is preferred in terms of improving fiber strength and purity.

[0056] Alternatively, activated carbon fibers can be processed into a sheet shape using a wet papermaking method with a binder to produce an activated carbon fiber nonwoven fabric.

[0057] Examples of precursor fibers for activated carbon fibers include phenolic resin, cellulose fiber, polyphenylene ether fiber, polyacrylonitrile, pitch, lignin, bamboo, etc., but phenolic resin, cellulose fiber, and polyphenylene ether fiber are preferred in terms of improving fiber strength, compressive modulus, and purity.

[0058] Activated carbon fiber nonwoven fabric has the characteristic of having a high toluene adsorption rate and a fast adsorption / desorption rate compared to honeycomb-shaped activated carbon, zeolite, etc. Due to these characteristics, an organic solvent concentration device (200) using an activated carbon fiber nonwoven fabric has a high concentration ratio (a value obtained by dividing the amount of processing gas flow by the amount of concentration gas flow), so the amount of concentration gas flow can be reduced. As a result, the amount of concentration gas flow returned to the organic solvent recovery device (100) is reduced. Therefore, the amount of gas to be processed in the organic solvent recovery device (100) is reduced. Through this action, the organic solvent recovery system (1) can reduce operating energy by miniaturizing the entire system.

[0059] The activated carbon fiber nonwoven fabric has the characteristic of drying quickly when it contains moisture because it has a large outer surface area. The first treatment gas discharged from the organic solvent recovery device (100) contains moisture derived from water vapor. However, the organic solvent concentration device (200) can suppress the effect on performance caused by moisture because it uses an activated carbon fiber nonwoven fabric that dries quickly.

[0060] Here, the control unit not shown controls the opening and closing of each opening and closing valve and opening and closing damper so that each treatment tank (101, 102) sequentially performs the adsorption process and the desorption process as described above.

[0061] Next, the operation of the organic solvent recovery system (1) will be described. Here, with reference to FIG. 2, an example of the operation of the organic solvent recovery system (1) will be described. FIG. 2 is a schematic diagram showing the flow of gas in a state where an adsorption process is performed in the first treatment tank (101) and a desorption process is performed in the second treatment tank (102). In FIG. 2, the flow of gas that is adsorbed in the first treatment tank (101) and the adsorbent (201) is shown as a thick solid line, and the flow of gas containing water vapor supplied to the second treatment tank (102) and the organic solvent desorbed from the first adsorbent (102A) is shown as a line with hatching in the diagonal.

[0062] In the state shown in FIG. 2, the opening / closing valves (V11, V31, V42) and the opening / closing dampers (V101, V201) are open, and the opening / closing valves (V12, V32, V41) and the opening / closing dampers (V102, V202) are closed.

[0063] In the state illustrated in FIG. 2, the gas to be treated is supplied to the first treatment tank (101) from the gas supply source through the gas supply path (L10) and the branch path (L11), and the organic solvent contained in the gas to be treated is adsorbed on the first adsorbent (101A) of the first treatment tank (101) (adsorption process). After that, the first treatment gas, which is the gas to be treated discharged from the first treatment tank (101), is sent to the adsorbent (201) of the organic solvent concentration device (200) through the first extraction path (L31) and the transfer path (300), and the organic solvent contained in the first treatment gas is adsorbed in the adsorption section (202).

[0064] Next, the second treatment gas discharged from the adsorption unit (202) is discharged outside the system of the organic solvent recovery system (1), and a portion thereof is sent to the desorption unit (203) through the connection path (L80). At this time, the second treatment gas sent to the desorption unit (203) is heated by a heater (H3). The concentrated gas discharged from the desorption unit (203) is returned to the gas supply path (L10) of the organic solvent recovery device (100) through the return path (400).

[0065] Meanwhile, in the second treatment tank (102), steam is supplied from the steam supply unit (110) through the second steam supply path (L42), thereby desorbing the organic solvent from the first adsorbent (102A) (desorption process). The steam containing the organic solvent desorbed from the first adsorbent (102A) is condensed into the condenser (122) through the organic solvent recovery path (L52) and then introduced into the separator (120). The recovered solvent separated by phase in the separator (120) is discharged out of the system of the organic solvent recovery device (100), and the vent gas present in the separator (120) is returned to the gas to be treated supply path (L10) through the re-supply path (L60). Separated wastewater is treated in a wastewater treatment facility (130), treated water is discharged out of the system of the organic solvent recovery device (100), and aeration gas is returned to the gas supply path (L10) through the aeration gas supply path (L61).

[0066] In the organic solvent recovery system (1) of the present embodiment, since an activated carbon fiber nonwoven fabric is used as the second adsorbent (201A), it is possible to recover organic solvents contained in the treatment gas with high performance. Therefore, in the organic solvent recovery system (1), it is possible to improve the recovery rate of organic solvents while avoiding the enlargement of the equipment.

[0067] [Embodiment 2]

[0068] FIG. 3 is a schematic diagram showing the configuration of an organic solvent recovery system of Embodiment 2. As shown in FIG. 3, in Embodiment 2, an organic solvent concentration device (500) is used instead of the organic solvent concentration device (200) of FIG. 1. The organic solvent concentration device (500) has an adsorbent (501). The configuration other than the adsorbent (501) is the same as the configuration of the organic solvent concentration device (200) of FIG. 1. Details regarding the adsorbent (501) will be explained using FIG. 4 to 6.

[0069] FIG. 4 is a longitudinal cross-sectional view of the adsorbent of Embodiment 2. FIG. 5 is a cross-sectional view of the adsorbent along the VV line shown in FIG. 4. FIG. 6 is an enlarged cross-sectional view of the main part of the adsorption rotor shown in FIG. 5.

[0070] As illustrated in FIGS. 4 to 6, the adsorbent (501) is equipped with an adsorption rotor (90). The adsorption rotor (90) is installed within a processing chamber (51). The adsorption rotor (90) is configured to allow fluid to flow in the radial direction. The adsorption rotor (90) is configured to rotate around a shaft C by receiving rotational driving force from a motor (3). The adsorption rotor (90) is rotatably supported on a plurality of supporting members (6), such as a support column, with the shaft C direction facing vertically, but it may also be configured so that the shaft C direction faces horizontally. The curved arrows shown in FIGS. 5 and 6 indicate the rotational direction of the adsorption rotor (90).

[0071] The adsorption rotor (90) is composed of a pair of hollow discs (10), a plurality of partitions (20), and a plurality of adsorption units (30).

[0072] A pair of hollow discs (10) includes a first hollow disc (11) and a second hollow disc (12). The first hollow disc (11) and the second hollow disc (12) have a toroidal shape and are arranged so that their respective centers are on the through axis C. An opening (11a) is formed in the central portion of the first hollow disc (11). The first hollow disc (11) and the second hollow disc (12) are arranged parallel to each other at a distance so that a partition (20) and an adsorption unit (30) can be placed between them.

[0073] The adsorption rotor (90) is formed in a cylindrical shape by alternately arranging a plurality of partition portions (20) and a plurality of adsorption units (30) around a main axis C between a pair of hollow discs (10). The adsorption rotor (90) has an overall hollow cylindrical shape and has a main hole (90a) (central space) formed therein. The main hole (90a) is in communication with the opening (11a) of the first hollow disc (11).

[0074] A plurality of partition members (20) partition the space between a pair of hollow discs (10) into a plurality of independent space members (S) (see FIG. 6) in the circumferential direction around the main axis C. The partition members (20) are members that do not have air passages and are impassable to gas. The partition members (20) are installed between a pair of hollow discs (10) to be airtight and / or liquid-tight.

[0075] Each partition section (20) includes a main body section (21) and a seal section (22). The main body section (21) is formed of stainless steel or iron, etc., and constitutes the skeletal section of the partition section (20). The main body section (21) has a triangular cylindrical shape. The main body section (21) has a top edge section located on the inner side of the suction rotor (90) and a bottom section of the main body section (21) located on the outer side of the suction rotor (90). A plurality of partition sections (20) are arranged such that the center of gravity of the triangles viewed from the plane of the main body section (21) is arranged at equal intervals in the circumferential direction around the cylindrical axis C.

[0076] The seal portion (22) is provided around the main body portion (21). The seal portion (22) may be formed integrally with the main body portion (21) or may be formed as a separate component from the main body portion (21). If the seal portion (22) is formed as a separate component from the main body portion (21), the seal portion (22) may be joined to the main body portion (21) by means of adhesive, etc., or may be configured to be installable and removable from the main body portion (21).

[0077] The seal portion (22) of the present embodiment has an inner seal portion (23) and an outer seal portion (24). The inner seal portion (23) is located on the inner side (the side closer to the main axis C) relative to the main body portion (21) in the diameter direction of the adsorption rotor (90). The outer seal portion (24) is located on the outer side (the side spaced apart from the main axis C) relative to the main body portion (21) in the diameter direction of the adsorption rotor (90). The inner seal portion (23) is provided to protrude inward in the diameter direction of the adsorption rotor (90) from the top edge portion of the main body portion (21). The outer seal portion (24) is provided to protrude outward in the diameter direction of the adsorption rotor (90) from the bottom portion of the main body portion (21).

[0078] The inner side seal portion (23) and the outer side seal portion (24) of the present embodiment each have a rib-shaped form that extends in the axial direction (the direction in which the main axis C extends) of the adsorption rotor (90) and also extends in the diameter direction of the adsorption rotor (90). The inner side seal portion (23) has a seal surface (23a). The outer side seal portion (24) has a seal surface (24a). The seal surfaces (23a, 24a) intersect in the rotational direction of the adsorption rotor (90).

[0079] A sealing member (40) is installed in the inner sealing portion (23) and the outer sealing portion (24). The sealing member (40) is formed, for example, from an elastic rubber material and has airtightness and / or liquid tightness. The sealing member (40) may have the function of partitioning the adsorption area where an adsorption treatment is performed to adsorb the gas to be treated onto the adsorption unit (30) and the desorption area where a desorption treatment is performed to desorb the gas to be treated from the adsorption unit (30), and / or the function of preventing leakage of the gas to be treated between the adsorbent (501) and the treatment room (51).

[0080] The seal member (40) includes an inner seal member (41) located on the inner side of the adsorption rotor (90) and an outer seal member (42) located on the outer side of the adsorption rotor (90). The inner seal member (41) is installed on the seal surface (23a) of the inner side seal portion (23). The inner seal member (41) protrudes from the partition portion (20) toward the inner side in the diameter direction of the adsorption rotor (90).

[0081] The outer seal member (42) is installed on the seal surface (24a) of the outer circumference seal portion (24). The outer seal member (42) protrudes from the partition portion (20) toward the outer diameter direction of the adsorption rotor (90). The inner seal member (41) and the outer seal member (42) extend between a pair of hollow discs (10) from one hollow disc (first hollow disc (11)) to the other hollow disc (second hollow disc (12)).

[0082] The adsorption unit (30) is a member filled with an adsorption element that allows a gas, such as a gas to be processed, to pass through. In the embodiment, the adsorption unit (30) allows gas to pass from the outer surface of the adsorption rotor (90) toward the through hole (90a). Each adsorption unit (30) is housed in one of a plurality of independent spaces (S). The plurality of adsorption units (30) are arranged side by side with a gap in the circumferential direction of the adsorption rotor (90). A partition (20) is disposed between two adsorption units (30) adjacent in the circumferential direction of the adsorption rotor (90).

[0083] Each adsorption unit (30) has a rectangular shape. The adsorption unit (30) has four first sides extending in the axial direction of the adsorption rotor (90), four second sides extending in the radial direction of the adsorption rotor (90), and four third sides extending orthogonally to the first and second sides. In the adsorption unit (30) of the embodiment, the first side is significantly longer than the second and third sides. The adsorption unit (30) has a rectangular shape with the first side as the longer side. The cross-sectional shape of the adsorption unit (30) orthogonal to the main axis C is a square or a rectangle.

[0084] In this embodiment, the adsorption unit (30) is filled with one or more layers of activated carbon fiber nonwoven fabric as an adsorbent. The physical properties of the activated carbon fiber nonwoven fabric as an adsorbent are the same as the physical properties of the activated carbon fiber nonwoven fabric of the second adsorbent (201A) shown in Embodiment 1.

[0085] In the adsorbent (501), a part of the adsorption unit (30) forms an adsorption section that adsorbs an organic solvent included in a first treatment gas supplied from the outside to the inside of the adsorption unit (30), and the remainder of the adsorption unit (30) forms a desorption section that desorbs the organic solvent adsorbed on the adsorption unit (30) from the adsorption unit (30) by supplying heated air from the inside to the outside of the adsorption unit (30).

[0086] Again, referring to FIGS. 4 to 6, the adsorbent (501) further comprises a first flow path forming member (2), an inner flow path forming member (4), and an outer flow path forming member (5).

[0087] One end of the first flow path forming member (2) is configured to allow the adsorption rotor (90) to rotate around the through axis C while maintaining a hermetic seal between the interior of the first flow path forming member (2) and the through hole (90a) of the adsorption rotor (90). An annular seal member may be clamped by the first hollow disc (11) located at the periphery of the opening (11a) and the end of the first flow path forming member (2). The other end of the first flow path forming member (2) is drawn out of the processing chamber (51).

[0088] The inner side flow path forming member (4) is positioned in the through hole (90a) on the inner side of the adsorption rotor (90). The outer side flow path forming member (5) is positioned on the outer side of the adsorption rotor (90). The inner side flow path forming member (4) and the outer side flow path forming member (5) are positioned facing each other on the inner side and outer side of the adsorption rotor (90) so as to insert a part of the adsorption rotor (90) in the circumferential direction.

[0089] The inner circumferential flow path forming member (4) is provided to extend along the through hole (90a) and to extend outward from the opening (11a) toward the outside of the adsorption rotor (90). The inner circumferential flow path forming member (4) includes a portion that extends along the through axis C direction through the opening (11a) of the first hollow disc (11).

[0090] At one end of the inner circumferential flow path forming member (4), an inner circumferential opening end (4a) facing the inner circumferential surface of the adsorption rotor (90) is provided. The opening surface at the inner circumferential opening end (4a) is provided to face a portion of the inner circumferential surface of the adsorption rotor (90). The other end of the inner circumferential flow path forming member (4) protrudes to the outside of the first flow path forming member (2) from the opening (2a) provided in the first flow path forming member (2).

[0091] An inner circumferential curved surface (4b) is provided at the edge portion of the inner circumferential opening end (4a) located on the downstream side of the rotational direction of the adsorption rotor (90). An inner circumferential curved surface (4c) is provided at the edge portion of the inner circumferential opening end (4a) located on the upstream side of the rotational direction of the adsorption rotor (90). The inner circumferential curved surfaces (4b, 4c) are curved along the rotational direction of the adsorption rotor (90).

[0092] At one end of the outer circumferential flow path forming member (5), an outer circumferential opening end (5a) facing the outer circumferential side of the adsorption rotor (90) is provided. The outer circumferential opening end (5a) is provided to face a portion of the outer surface of the adsorption rotor (90). The other end of the outer circumferential flow path forming member (5) protrudes outside the processing chamber (51).

[0093] An outer circumferential curved surface (5b) is provided at the edge portion of the outer circumferential opening end (5a) located on the downstream side of the rotational direction of the adsorption rotor (90). An outer circumferential curved surface (5c) is provided at the edge portion of the outer circumferential opening end (5a) located on the upstream side of the rotational direction of the adsorption rotor (90). The outer circumferential curved surfaces (5b, 5c) are curved along the rotational direction.

[0094] As illustrated in FIGS. 5 and 6, the adsorption rotor (90) includes a desorption area (R1) and an adsorption area (R2) that are partitioned in the circumferential direction. A plurality of adsorption units (30) alternately move between the desorption area (R1) and the adsorption area (R2) as the adsorption rotor (90) rotates around the main axis C.

[0095] As illustrated in FIG. 6, a plurality of space portions (S) that rotate along with the rotation of the adsorption rotor (90) are connected to the inner circumferential flow path forming member (4) and the outer circumferential flow path forming member (5) in the detachment area (R1). As the adsorption rotor (90) rotates, the inner seal member (41) slides with respect to the inner circumferential curved surface (4b, 4c) and the outer seal member (42) slides with respect to the outer circumferential curved surface (5b, 5c), thereby hermetically connecting some of the space portions (S) to the inner circumferential flow path forming member (4) and the outer circumferential flow path forming member (5).

[0096] Specifically, a partition part (20) located between the inner circumferential curved surface (4b) and the outer circumferential curved surface (5b), and a space part (S) located between the partition part (20) located between the inner circumferential curved surface (4c) and the outer circumferential curved surface (5c) are hermetically connected to the inner circumferential flow path forming member (4) and the outer circumferential flow path forming member (5).

[0097] The adsorption region (R2) does not communicate with the inner circumferential flow path forming member (4) and the outer circumferential flow path forming member (5), and forms a flow path different from the desorption region (R1).

[0098] As illustrated in FIG. 4, fluid is introduced into the desorption region (R1) and the adsorption region (R2), respectively. In the adsorption region (R2), fluid is introduced from the outer side in the radial direction of the adsorption rotor (90) toward the inner side. The fluid passing through the adsorption region (R2) passes through the through hole (90a) of the adsorption rotor (90) and flows out to the outside of the adsorption rotor (90) from the opening (11a) of the first hollow disc (11). In the desorption region (R1), fluid passing through the interior of the inner circumferential flow path forming member (4) passing through the opening (11a) of one of the pair of hollow discs (10) is introduced from the inner side in the radial direction of the adsorption rotor (90) toward the outer side.

[0099] The fluid introduced into the adsorption area (R2) is a first treatment gas as the fluid to be treated. The first treatment gas contains an organic solvent as the substance to be treated. In the adsorption area (R2), the fluid to be treated is purified.

[0100] As illustrated in FIG. 4, during purification, a first treatment gas supplied by a blower (F3) into the treatment chamber (51) is introduced into the adsorption area (R2) from the outer surface of the adsorption rotor (90). The first treatment gas introduced into the adsorption area (R2) is purified by adsorbing an organic solvent to a plurality of adsorption units (30) located in the adsorption area (R2) as it passes through the adsorption rotor (90) from the outer surface to the inner surface along the diameter direction.

[0101] The second treatment gas, as a purified fluid to be treated, is discharged as a clean gas from the adsorption area (R2) to the through hole (90a) of the adsorption rotor (90). The clean gas passes through the through hole (90a) and flows out from the opening (11a) of the first hollow disc (11). The clean gas flowing out from the opening (11a) is discharged through the first flow path forming member (2) to the clean gas discharge path (L202) outside the treatment chamber (51).

[0102] In the desorption area (R1), a portion of the second treatment gas is introduced by a blower (F4). In the desorption area (R1), by desorbing the substance to be treated, such as an organic solvent adsorbed on the adsorption unit (30), the adsorption unit (30) is regenerated, and a concentrated gas with a higher concentration of organic solvent is generated.

[0103] In order to perform desorption of the organic solvent, a portion of the second treatment gas is introduced from the inner circumferential flow path forming member (4) into the desorption area (R1). As the portion of the second treatment gas introduced into the desorption area (R1) passes through the adsorption rotor (90), the organic solvent adsorbed on the plurality of adsorption units (30) located in the desorption area (R1) is desorbed by heat. The portion of the second treatment gas containing the organic solvent is discharged as a concentrated gas from the desorption area (R1) to the outer circumferential flow path forming member (5) using a blower (F5). The concentrated gas is discharged out of the treatment chamber (51) and returned to the return flow path (400).

[0104] In the adsorbent (501), an adsorption treatment of the material to be treated is performed on the adsorption unit (30) located in the adsorption area (R2), and after the adsorption treatment, a desorption treatment of the material to be treated is performed on the adsorption unit (30) located in the desorption area (R1). As the adsorption rotor (90) rotates around the main axis C, the adsorption unit (30) alternately moves between the desorption area (R1) and the adsorption area (R2), so that the adsorption treatment and desorption treatment of the material to be treated are performed continuously.

[0105] In the above-described embodiment, the partition part (20) has been described as having a roughly triangular shape, but it is not limited to this. As long as it has strength to support a pair of hollow discs (10) and can also install a seal member (40), its shape may be a plate shape or the like, and can be appropriately changed.

[0106] In the above-described embodiment, the through hole (90a) of the adsorption rotor (90) is opened only on one side (upward in FIG. 4) in the axial direction (direction in which the through axis C extends) of the adsorption rotor (90), and the clean gas purified by the adsorption rotor (90) flows upward in FIG. 4 and flows to the first flow path forming member (2), and an example of an adsorbent body (501) with a single-sided opening has been described. The adsorbent body (501) of the embodiment may have a double-sided opening structure in which the through hole (90a) is opened on both sides in the axial direction of the adsorption rotor (90), and the clean gas flows out from the through hole (90a) to both the upward and downward directions in FIG. 4.

[0107] [Embodiment 3]

[0108] FIG. 7 is a schematic diagram showing the flow of gas in the organic solvent recovery system of Embodiment 3. As shown in FIG. 7, in Embodiment 3, an organic solvent recovery device (600) is used instead of the organic solvent recovery device (100) of FIG. 1. The organic solvent recovery device (600) has three treatment tanks (101, 102, 103), a gas supply path (L10), a connecting path (L21, L22, L23), an extraction path (L31, L32, L33), a steam supply path (L41, L42, L43), an organic solvent recovery path (L51, L52, L53), a separator (120), a re-supply path (L60), and a control unit (150).

[0109] Each treatment tank (101, 102, 103) has a first adsorbent (101A, 102A, 103A) capable of adsorbing and desorbing an organic solvent. Each treatment tank (101, 102, 103) has an opening / closing damper (V101, V102, V103) for switching the supply / non-supply of the gas to be treated to a gas supply port, and an opening / closing damper (V201, V202, V203) for switching the discharge / non-discharge of the gas to be treated after passing through the first adsorbent (101A, 102A, 103A).

[0110] In each treatment tank (101, 102, 103), the adsorption of an organic solvent by the first adsorbent (101A, 102A, 103A) and the desorption of an organic solvent from the first adsorbent (101A, 102A, 103A) are performed alternately. The details are as follows.

[0111] In one of the three treatment tanks (101, 102, 103), a first adsorption process is performed to adsorb an organic solvent from a gas to be treated supplied from a gas supply source using a first adsorbent. At the same time, in another of the three treatment tanks (101, 102, 103), a second adsorption process is performed to adsorb an organic solvent from a gas to be treated (gas from the first adsorption process) after treatment in the treatment tank used in the first adsorption process using a first adsorbent and to discharge a first treatment gas. Meanwhile, in the remaining one treatment tank, a desorption process is performed to desorb an organic solvent from the first adsorbent.

[0112] In each treatment tank (101, 102, 103), the desorption process, the second adsorption process, the first adsorption process, and the desorption process are repeated in this order. FIG. 7 illustrates a state in which the first adsorption process is performed in the first treatment tank (101), the second adsorption process is performed in the second treatment tank (102), and the desorption process is performed in the third treatment tank (103).

[0113] The gas supply path (L10) for the gas to be treated is a path for supplying gas to be treated to each treatment tank (101, 102, 103). The gas supply path (L10) for the gas to be treated has branch paths (L11, L12, L13) for supplying gas to be treated to each treatment tank (101, 102, 103). An opening / closing valve (V11) is provided in the branch path (L11). An opening / closing valve (V12) is provided in the branch path (L12). An opening / closing valve (V13) is provided in the branch path (L13).

[0114] Each connecting channel (L21, L22, L23) connects one treatment tank to another treatment tank so that the gas to be treated after the organic solvent has been adsorbed in the first adsorbent of one of the three treatment tanks (101, 102, 103) is introduced into the gas supply port of another treatment tank (a treatment tank used in the second adsorption process) which is different from one of the three treatment tanks (101, 102, 103).

[0115] Specifically, the first connecting channel (L21) connects the treatment gas outlet in the first treatment tank (101) with the gas supply port to be treated in the second treatment tank (102). The second connecting channel (L22) connects the treatment gas outlet in the second treatment tank (102) with the gas supply port to be treated in the third treatment tank (103). The third connecting channel (L23) connects the treatment gas outlet in the third treatment tank (103) with the gas supply port to be treated in the first treatment tank (101).

[0116] Each connecting passage (L21, L22, L23) has a connecting passage (L20) that joins with each other. A blower (F2) is provided in the connecting passage (L20). A cooler (C3) and a heater (H4) are provided in the upstream portion of the connecting passage (L20) to adjust the temperature and humidity of the gas to be processed to a desired range. An opening / closing valve (V21) is provided in the portion of the first connecting passage (L21) that branches off from the connecting passage (L20). An opening / closing valve (V22) is provided in the portion of the second connecting passage (L22) that branches off from the connecting passage (L20). An opening / closing valve (V23) is provided in the portion of the third connecting passage (L23) that branches off from the connecting passage (L20).

[0117] The extraction passages (L31, L32, L33) are passages for extracting the first treatment gas, which is the gas to be treated after adsorption treatment in each treatment tank (101, 102, 103). The extraction passages (L31, L32, L33) are connected to the treatment gas outlets in each treatment tank (101, 102, 103). An opening / closing valve (V31) is provided in the first extraction passage (L31). An opening / closing valve (V32) is provided in the second extraction passage (L32). An opening / closing valve (V33) is provided in the third extraction passage (L33). Each extraction passage (L31, L32, L33) has a merging passage (L30) that merges with each other.

[0118] The first steam supply path (L41) connects the steam supply unit (110) and the first treatment tank (101). An opening / closing valve (V41) is provided in the first steam supply path (L41). The second steam supply path (L42) connects the steam supply unit (110) and the second treatment tank (102). An opening / closing valve (V42) is provided in the second steam supply path (L42). The third steam supply path (L43) connects the steam supply unit (110) and the third treatment tank (103). An opening / closing valve (V43) is provided in the third steam supply path (L43).

[0119] The organic solvent recovery channels (L51, L52, L53) are channels for recovering water vapor (desorption gas) containing organic solvent desorbed from the first adsorbent (101A, 102A, 103A). Each organic solvent recovery channel (L51, L52, L53) is connected to each treatment tank (101, 102, 103). Each organic solvent recovery channel (L51, L52, L53) has a merging channel (L50) that merges with each other.

[0120] The control unit (150) controls the temperature of the gas to be treated. Specifically, the control unit (150) controls the temperature of the cooler (C3) and heater (H4) so ​​that the temperature of the gas to be treated introduced into the treatment tank used in the second adsorption process (a treatment tank located on the downstream side in the flow of the gas to be treated among the three treatment tanks (101, 102, 103) connected in the connecting channel (L21, L22, L23)) is maintained in a predetermined range (e.g., 40°C to 80°C).

[0121] The temperature of the gas to be processed is detected by a temperature sensor (152). The temperature sensor (152) is provided in the confluence channel (L20).

[0122] Next, the operation of the organic solvent recovery system (1) will be described. FIG. 7 schematically illustrates the flow of gas in a state where a first adsorption process is performed in a first treatment tank (101), a second adsorption process is performed in a second treatment tank (102), and a desorption process is performed in a third treatment tank (103). In each treatment tank, the treatment is repeated in the order of first adsorption process → desorption process → second adsorption process → first adsorption process → …

[0123] In the state shown in FIG. 7, the opening / closing valves (V11, V21, V32, V43) and the opening / closing dampers (V101, V102, V201, V202) are open, and the opening / closing valves (V12, V13, V22, V23, V31, V33, V41, V42) and the opening / closing dampers (V103, V203) are closed.

[0124] In the state illustrated in FIG. 7, the gas to be treated is supplied to the first treatment tank (101) from the gas supply source through the gas supply path (L10) and the branch path (L11), and the organic solvent contained in the gas to be treated is adsorbed on the first adsorbent (101A) of the first treatment tank (101) (first adsorption process). After that, the gas to be treated is supplied to the second treatment tank (102), and the organic solvent contained in the supplied gas is further adsorbed on the first adsorbent (102A) of the second treatment tank (102) (second adsorption process).

[0125] In the second adsorption process (particularly the first step) in the second treatment tank (102), the first adsorbent (102A) is dried by the supplied gas. Since the second adsorption process is performed after the desorption process using steam, the first adsorbent (102A) contains moisture, so drying is required to improve adsorption performance. Even if the drying performed in this second adsorption process is a system separated as a drying process, that is, a system in which each treatment tank processes in the order of first adsorption process → desorption process → drying process → second adsorption process → first adsorption process → …, this system can be adapted.

[0126] The first treatment gas discharged from the second treatment tank (102) is sent to the adsorbent (201) of the organic solvent concentration device (200) through the second extraction path (L32) and the transfer path (300), and the organic solvent contained in the first treatment gas is adsorbed in the adsorption section (202). After that, the second treatment gas discharged from the adsorption section (202) is discharged outside the system of the organic solvent recovery system (1), and a portion thereof is sent to the desorption section (203) through the connection path (L80). At this time, the second treatment gas sent to the desorption section (203) is heated by a heater (H3). The concentrated gas discharged from the desorption section (203) is returned to the gas supply path (L10) of the organic solvent recovery device (100) through the return path (400).

[0127] Meanwhile, in the third treatment tank (103), steam is supplied from the steam supply unit (110) through the third steam supply path (L43), thereby desorbing the organic solvent from the first adsorbent (103A) (desorption process). The steam containing the organic solvent desorbed from the first adsorbent (103A) is condensed in the condenser (122) through the organic solvent recovery path (L53) and then introduced into the separator (120). The recovered solvent separated by phase in the separator (120) is discharged out of the system of the organic solvent recovery device (100), and the vent gas present in the separator (120) is returned to the gas supply path (L10) through the re-supply path (L60). Separated wastewater is treated in a wastewater treatment facility (130), treated water is discharged out of the system of the organic solvent recovery device (100), and aeration gas is returned to the gas supply path (L10) through the aeration gas supply path (L61).

[0128] In the organic solvent recovery system (1) of the present embodiment, since an activated carbon fiber nonwoven fabric is used as the second adsorbent (201A) as in the above-described embodiment, it is possible to recover organic solvents contained in the treatment gas with high performance. Therefore, in the organic solvent recovery system (1), it is possible to improve the recovery rate of organic solvents while avoiding the enlargement of the equipment.

[0129] In the organic solvent recovery system (1) of the present embodiment, an organic solvent concentration device (500) may be used instead of an organic solvent concentration device (200), as in the above-described embodiment.

[0130] [Embodiment 4]

[0131] FIG. 8 is a schematic diagram showing the flow of gas in the organic solvent recovery system of Embodiment 4. As shown in FIG. 8, in Embodiment 4, an organic solvent recovery device (700) is used instead of the organic solvent recovery device (100) of FIG. 7. The organic solvent recovery device (700) has three treatment tanks (101, 102, 103), a gas supply path (L10), a connection path (L21, L22, L23), an extraction path (L31, L32, L33), a steam supply path (L41, L42, L43), an organic solvent recovery path (L51, L52, L53), a separator (120), a resupply path (L60), a dilution gas supply path (L70), a heater (140), an opening / closing valve (V70), and a control unit (150).

[0132] The organic solvent recovery device (700) of Embodiment 4 differs from the organic solvent recovery device (600) of Embodiment 3 in that it has a dilution gas supply path (L70), etc. Below, the differences from the organic solvent recovery device (600) will be explained in detail.

[0133] The dilution gas supply path (L70) is a path for supplying dilution gas to the connecting paths (L21, L22, L23) to promote drying of the first adsorbent (101A, 102A, 103A) after the desorption process. The dilution gas consists of a gas including at least one of ambient air, instrumentation air, nitrogen gas, and argon gas. Additionally, the dilution gas is supplied from outside the system of the organic solvent recovery device (100).

[0134] A heater (140) is provided in the dilution gas supply path (L70). The heater (140) heats the dilution gas so that the temperature of the dilution gas becomes higher than the temperature (about 40°C) of the gas to be processed flowing through the connection paths (L21, L22, L23).

[0135] An opening / closing valve (V70) is provided in the dilution gas supply path (L70). The opening / closing valve (V70) can adjust the degree of opening.

[0136] The control unit (150) controls the temperature of the gas to be treated. Specifically, the control unit (150) controls the temperature of the heater (140) so that the temperature of the gas to be treated introduced into the treatment tank used in the second adsorption process (a treatment tank located on the downstream side in the flow of the gas to be treated among three treatment tanks (101, 102, 103) connected by connecting channels (L21, L22, L23)) is maintained in a predetermined range (e.g., 40°C to 80°C).

[0137] In the organic solvent recovery system (1) of the present embodiment, since an activated carbon fiber nonwoven fabric is used as the second adsorbent (201A) as in the above-described embodiment, it is possible to recover organic solvents contained in the treatment gas with high performance. Therefore, in the organic solvent recovery system (1), it is possible to improve the recovery rate of organic solvents while avoiding the enlargement of the equipment.

[0138] In the organic solvent recovery system (1) of the present embodiment, an organic solvent concentration device (500) may be used instead of an organic solvent concentration device (200), as in the above-described embodiment.

[0139] [Other embodiments]

[0140] The organic solvent recovery device (100) may have four or more treatment tanks. In that case, a desorption process is performed in one treatment tank, and in the meantime, a multi-stage adsorption process is performed in the remaining three or more treatment tanks connected in series in a connecting channel.

[0141] Instead of the organic solvent concentration device (200), the solvent treatment device disclosed in International Publication No. 2013 / 187274 may be used.

[0142] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of this disclosure is defined by the claims, not by the description above, and is intended to include all modifications within the meaning and scope equivalent to the claims. Explanation of the symbols

[0143] 1: Organic solvent recovery system 100: Organic solvent recovery device 101: First Treatment Tank 101A: First adsorbent 102: Second treatment tank 102A: First adsorbent 103: Third Treatment Tank 103A: First adsorbent 110: Steam supply unit 120: Separator 130: Wastewater treatment facilities 140: Heater 150 control unit 152: Temperature sensor 200: Organic solvent concentration device 201: Adsorbent 201A: Second adsorbent 202: Adsorption part 203: Detachable part 300: Transfer Euro 400: Return Euro 500: Organic solvent concentration device 501: Adsorbent L10: Gas supply path for treatment L21, L22, L23: Connecting Euros L31, L32, L33: Extraction path L40: Steam supply Euro L51, L52, L53: Organic solvent recovery path L60: Resupply Euro L70: Dilution gas supply path L80: Connect Euro V11, V12, V13, V21, V22, V23, V31, V32, V33, V41, V42, V43, V70: Open / close valves V101, V102, V103, V201, V202, V203: Opening / closing dampers

Claims

Claim 1 An organic solvent recovery device comprising: at least three treatment tanks, each including a first adsorbent capable of adsorbing and desorbing an organic solvent contained in a gas to be treated, and alternately performing adsorption of the organic solvent by the first adsorbent and desorption of the organic solvent from the first adsorbent by water vapor; a water vapor supply unit for introducing the water vapor to a treatment tank selected from the plurality of treatment tanks; a connecting channel for connecting the remaining plurality of treatment tanks in series in multiple stages; an extraction channel for discharging the gas to be treated introduced from a treatment tank located upstream of the plurality of treatment tanks connected in multiple stages in series, as a first treatment gas in which the organic solvent is adsorbed by the first adsorbent of the plurality of treatment tanks connected in multiple stages in series, from a treatment tank located downstream of the plurality of treatment tanks connected in multiple stages in series, and a dilution gas supply channel for supplying dilution gas to the connecting channel; and a second adsorbent capable of adsorbing and desorbing the organic solvent, wherein the first treatment gas from the extraction channel by the second adsorbent An organic solvent recovery system comprising: an adsorption unit for adsorbing the included organic solvent and discharging a second treatment gas; a desorption unit for desorbing the organic solvent adsorbed on the second adsorbent from the second adsorbent and discharging it as a concentrated gas; a return flow path for returning the concentrated gas to the organic solvent recovery device; wherein the second adsorbent comprises an activated carbon fiber nonwoven fabric, and the activated carbon fiber nonwoven fabric has a fiber diameter of 11 μm or more and 120 μm or less, a toluene adsorption rate of 25 wt.% or more and 75 wt.% or less, a total weight per unit area of ​​1200 g / m² or more and 4000 g / m² or less, and a heater for heating the diluted gas such that the temperature of the diluted gas becomes higher than the temperature of the gas to be treated flowing through the connecting flow path. Claim 2 In claim 1, the organic solvent concentration device is an organic solvent recovery system in which the second adsorbent is disposed on a disc-shaped adsorption rotor that rotates around a main axis. Claim 3 In claim 1, the organic solvent concentration device is an organic solvent recovery system in which the second adsorbent is arranged in a plurality of circumferential directions around the shaft of a hollow cylindrical rotor that rotates around the shaft. Claim 4 delete Claim 5 delete

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