Gas treatment device and gas treatment method

Abstract

In the gas treatment device of the present invention, the treatment tank has a downstream chamber of the treatment tank into which the treated gas, i.e., the processing gas, after being adsorbed by the adsorbent member is introduced. Connected to the downstream chamber of the treatment tank are: a take-out flow path for discharging the processing gas, a purge gas supply flow path for supplying purge gas for purging the downstream chamber of the treatment tank, and a purge gas take-out flow path for discharging the purge gas from the downstream chamber of the treatment tank.

Description

Technical Field

[0001] The present invention relates to a gas treatment apparatus and a gas treatment method. Background Art

[0002] Conventionally, a gas treatment apparatus for recovering an organic solvent from a gas to be treated has been known. For example, Patent Document 1 discloses a gas treatment apparatus including a recovery mechanism unit having a plurality of treatment tanks, each treatment tank having an adsorbent capable of adsorbing and desorbing an organic solvent, and being alternately supplied with a gas to be treated containing an organic solvent and a heating steam for desorbing the organic solvent from the adsorbent. The recovery mechanism unit introduces the heating steam into one of the plurality of treatment tanks selected, introduces the gas to be treated into the remaining treatment tanks, and recovers the organic solvent from the desorbed gas discharged from the treatment tank when the heating steam is supplied.

[0003] The adsorbent is, for example, as shown in Patent Document 2, a shape in which a plurality of turns are wound concentrically in a layer state having a predetermined thickness, and is fixed inside the treatment tank via a sealing material.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open Gazette "JP-A-2014-147863"

[0007] Patent Document 2: Japanese Patent Laid-Open Gazette "JP-A-2001-179029" Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] In the gas treatment apparatus described in Patent Document 1, the adsorption tank in which the process of desorbing the organic solvent is performed closes the extraction flow path through an on-off valve between the adsorption tank and the extraction flow path, and the water vapor for desorbing the organic solvent does not flow into the extraction flow path side. However, for example, when the organic solvent to be treated has a high affinity with the sealing material, in the process of desorbing the organic solvent, there is a problem that the organic solvent penetrates into the sealing material and the organic solvent leaks into the space between the adsorption tank and the on-off valve. However, there is no sealing material that has solvent resistance for all types of organic solvents and also has properties such as heat resistance that can withstand a temperature of 100°C or higher. In addition, even if the tightening force changes due to vibration during long-term operation, deterioration of the sealing material occurs.

[0010] For these reasons, in the adsorption process after the desorption process, the leaked organic solvent is contained in the gas at the outlet of the adsorption process, and the organic solvent is discharged into the atmosphere via the extraction flow path. As a result, the removal rate of the gas treatment apparatus deteriorates.

[0011] Therefore, in view of the above problems, an object of the present invention is to provide a gas treatment device with an improved removal rate of organic solvents.

[0012] Means for Solving the Problems

[0013] The present invention provides the following gas treatment device. Specifically, the gas treatment device of the present invention includes a treatment tank, the treatment tank has an adsorbent capable of adsorbing and desorbing organic solvents, and the treatment tank alternately performs adsorption treatment and desorption treatment. The adsorption treatment is to make the gas to be treated containing the organic solvent contact with the adsorbent to adsorb the organic solvent by the adsorbent, and the desorption treatment uses steam to desorb the organic solvent from the adsorbent. It is characterized in that the treatment tank has a downstream chamber of the treatment tank, and the downstream chamber of the treatment tank is for introducing the treated gas, that is, the treatment gas, after the adsorption treatment by the adsorbent. A take-out flow path for discharging the treatment gas, a purge gas supply flow path for supplying a purge gas for purging the downstream chamber of the treatment tank, and a purge gas take-out flow path for discharging the purge gas from the downstream chamber of the treatment tank are connected to the downstream chamber of the treatment tank.

[0014] Based on the above structure, it is possible that during the supply of the steam to the treatment tank, the purge gas is supplied to the downstream chamber of the treatment tank.

[0015] Based on the above structure, it is possible that the end of the purge gas take-out flow path is connected to the gas to be treated supply flow path for supplying the gas to be treated to the treatment tank.

[0016] Based on the above structure, it is possible that at least a part of the take-out flow path and the purge gas supply flow path are shared.

[0017] Based on the above structure, it is possible that the end of the purge gas supply flow path is connected to the take-out flow path.

[0018] Based on the above structure, it is possible that the gas treatment device includes a plurality of the treatment tanks, and the adsorption treatment is performed in a part of the plurality of treatment tanks, and the desorption treatment is performed in the remaining treatment tanks.

[0019] Based on the above structure, it is possible that the gas treatment device includes three or more of the treatment tanks, and the desorption treatment is performed in a part of the three or more treatment tanks, and the remaining treatment tanks are connected in series in multiple stages through a connection flow path to perform the adsorption treatment.

[0020] Based on the above structure, in the present invention, it is possible that at least a part of the connection flow path and the purge gas extraction flow path is shared.

[0021] Based on the above structure, in the present invention, it is possible that the end of the purge gas extraction flow path is connected to the connection flow path.

[0022] Advantages of the Invention

[0023] According to the present invention, a gas treatment device with an improved removal rate of organic solvents can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a diagram schematically showing the structure of a gas treatment device when there are two adsorption tanks in one embodiment of the present invention.

[0025] Figure 2 It is a diagram schematically showing the structure of a gas treatment device when there are three adsorption tanks in another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] Embodiments of the present invention will be described with reference to the drawings. It should be noted that in the following drawings referred to, the same or corresponding components are labeled with the same reference numerals.

[0027] Figure 1 It is a diagram schematically showing the structure of a gas treatment device 1 according to one embodiment of the present invention. As Figure 1 shown, the gas treatment device 1 is a device for removing and recovering organic solvents from a gas to be treated. It should be noted that the gas to be treated is supplied to the gas treatment device 1 from a gas to be treated supply source (not shown) provided outside the system of the gas treatment device 1. The gas treatment device 1 includes two treatment tanks 101a, 102a, a gas to be treated supply flow path L10a, extraction flow paths L31a, L32a, a steam supply flow path L41a, L42a, organic solvent recovery flow paths L51a to L52a, a separator 120a, a re-supply flow path L60a, and a control unit 150a.

[0028] In this specification, the organic solvents contained in the gas to be treated refer to dichloromethane, chloroform, carbon tetrachloride, vinyl chloride, trichloroethylene, tetrachloroethylene, o-dichlorobenzene, m-dichlorobenzene, Freon-112, Freon-113, HCFC, HFC, bromopropyl, iodobutyl, 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, tert-butanol, allyl alcohol, pentanol, heptanol, ethylene glycol, diethylene glycol, phenol, o-cresol, m-cresol, p-cresol, xylenol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, phorone, acrylonitrile, n-hexane, isohexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, n-nonane, isononane, decane, dodecane, undecane, tetradecane, decahydronaphthalene, benzene, toluene, m-xylene, p-xylene, o-xylene, ethylbenzene, 1,3,5-trimethylbenzene, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc. However, it is not limited to these.

[0029] Each treatment tank 101a, 102a has adsorbents 101Aa, 102Aa capable of adsorbing and desorbing organic solvents. As the adsorbents 101Aa, 102Aa, granular activated carbon, honeycomb activated carbon, zeolite, activated carbon fiber, etc. can be used, but activated carbon fiber is preferably used. It should be noted that, in Figure 1 the treatment tanks 101a, 102a shown, it is configured that one adsorbent is filled in each treatment tank, but the adsorbent can also be multiple. Each treatment tank 101a, 102a includes: baffles V101a, V102a for switching the supply / non-supply of the gas to be treated to the gas supply port; and baffles V201a, V202a for switching the discharge / non-discharge of the treated gas after passing through the adsorbents 101Aa, 102Aa. In addition, each treatment tank 101a, 102a has a downstream chamber 101Ca, 102Ca of the treatment tank that retains during the period before the treated gas from which the organic solvent has been removed by the adsorbents 101Aa, 102Aa is supplied to the extraction flow paths L31a, L32a.

[0030] The adsorption of organic solvents by the adsorbents 101Aa and 102Aa and the desorption of organic solvents from the adsorbents 101Aa to 102Aa are alternately performed in the respective treatment tanks 101a and 102a. The details are as follows. That is, in one of the two treatment tanks 101a and 102a, an adsorption process is performed in which organic solvents are adsorbed from the gas to be treated supplied from the gas to be treated supply source by the adsorbent, and in the remaining adsorption tank, a desorption process is performed in which organic solvents are desorbed from the adsorbent. The adsorption process and the desorption process are repeatedly performed in the two treatment tanks 101a and 102a. It should be noted that Figure 1 represents a state in which the adsorption process is performed in the adsorption tank 101a and the desorption process is performed in the adsorption tank 102a.

[0031] The gas to be treated supply flow path L10a is a flow path for supplying the gas to be treated to the treatment tanks 101a and 102a. The upstream end of the gas to be treated supply flow path L10a is connected to the gas to be treated supply source. A blower F1a is provided in the gas to be treated supply flow path L10a. A cooler C1a and a heater H1a for adjusting the temperature and humidity of the gas to be treated flowing into the treatment tanks 101a and 102a to a desired range are provided at a position upstream of the blower F1a in the gas to be treated supply flow path L10a. These devices and equipment can be appropriately set according to the pressure, temperature, and humidity of the gas to be treated.

[0032] The gas to be treated supply flow path L10a has branch flow paths L11a and L12a for supplying the gas to be treated to the respective treatment tanks 101a and 102a. An on-off valve V11a is provided in the branch flow path L11a. An on-off valve V12a is provided in the branch flow path L12a.

[0033] The extraction flow paths L31a and L33a are flow paths for extracting the gas to be treated, i.e., the treated gas, which has been adsorbed and treated in the respective treatment tanks 101a and 102a. The extraction flow paths L31a and L32a are connected to the treated gas discharge ports in the respective treatment tanks 101a and 102a. An on-off valve V31a is provided in the first extraction flow path L31a. An on-off valve V32a is provided in the second extraction flow path L32a. The respective extraction flow paths L31a and L32a have a confluence flow path L30a that converges with each other. The front end of the confluence flow path L30a is outside the system of the gas treatment device 1. The front end can be external air, and in the case where it is desired to further improve the removal rate of organic solvents, it can also be connected to a device (not shown) for treating organic solvents.

[0034] The steam supply flow paths L41a and L42a are flow paths for supplying steam to the respective treatment tanks 101a and 102a. The steam is used to desorb the organic solvents adsorbed on the adsorbents 101Aa and 102Aa from the adsorbents 101Aa and 102Aa. Each of the steam supply flow paths L41a and L42a has a confluent flow path L40a where they converge. The steam is supplied from the steam supply section 110a. It should be noted that the steam supply section 110a can be provided inside the gas treatment device 1 or outside the system of the gas treatment device 1.

[0035] The steam supply flow path L41a connects the steam supply section 110a to the first treatment tank 101a. An on-off valve V41a is provided in the steam supply flow path L41a. The steam supply flow path L42a connects the steam supply section 110a to the second treatment tank 102a. An on-off valve V42a is provided in the steam supply flow path L42a.

[0036] The organic solvent recovery flow paths L51a and L52a are flow paths for recovering the steam (desorption gas) containing the organic solvent desorbed from the adsorbents 101Aa and 102Aa. Each of the organic solvent recovery flow paths L51a and L52a is connected to the respective treatment tanks 101a and 102a. Each of the organic solvent recovery flow paths L51a and L52a has a confluent flow path L50a where they converge. A condenser 122a is provided in the confluent flow path L50a. The condenser 122a cools the desorption gas flowing in the confluent flow path L50a to condense the desorption gas and discharges the condensate (a mixture of water and organic solvent generated by the condensation of the desorption gas).

[0037] A separator 120a is provided at the downstream end of the confluent flow path L50a. The condensate flows into the separator 120a. Then, inside the separator 120a, the condensate is phase-separated into a liquid phase of separated drainage (sometimes slightly containing condensed water of the organic solvent-containing steam) and a liquid phase of recovered solvent, and the recovered solvent is taken out of the system of the gas treatment device 1. It should be noted that a space (exhaust gas) for the organic solvent in the gas phase is formed in the upper part of the separator 120a.

[0038] The re-supply flow path L60a is a flow path that connects the separator 120a to the gas to be treated supply flow path L10a. The upstream end of the re-supply flow path L60a is connected to the upper part of the separator 120a (the part where the organic solvent in the gas phase exists in the separator 120a). The downstream end of the re-supply flow path L60a is connected to the part upstream of the cooler C1a in the gas to be treated supply flow path L10a. Therefore, it is preferable that the organic solvent in the gas phase existing in the separator 120a is re-supplied to the respective treatment tanks 101a and 102a through the re-supply flow path L60a and the gas to be treated supply flow path L10a.

[0039] The drainage treatment device 130a is a device for removing the organic solvents contained in the above-mentioned separated drainage. It is supplied with the liquid phase of the separated drainage from the separator 120a, removes the organic solvents from the separated drainage, and discharges the treated water outside the system of the gas treatment device 1. Specific examples of the drainage treatment device 130a include an aeration device that volatilizes the organic solvents contained in the separated drainage by subjecting the separated drainage to aeration treatment, separating it into aeration gas containing organic solvents and treated water. It should be noted that the aeration gas is connected to a portion upstream of the cooler C1a in the treated gas supply flow path L10a via the aeration gas supply flow path L61a. Although not shown, a dehumidification unit may also be provided in the aeration gas supply flow path for the purpose of removing moisture in the aeration gas.

[0040] The purge gas supply flow paths L81a and L82a are flow paths for supplying the treated gas flowing in the confluence flow path L30a as purge gas to the downstream chambers 101Ca and 102Ca of the treatment tank. Each of the purge gas supply flow paths L81a and L82a has a confluence flow path L80a where they converge. The purge gas supply flow path L81a is connected to the adsorption tank 101a and has an on-off valve V81a. The purge gas supply flow path L82a is connected to the adsorption tank 102a and has an on-off valve V82a. It should be noted that for the purge gas, external air, measurement air, nitrogen, argon, etc. may also be supplied from outside the gas treatment device 1.

[0041] The purge gas extraction flow paths L91a and L92a are flow paths for returning the purge gas after purging the downstream chambers 101Ca and 102Ca of the treatment tank to the upstream side of the blower F1a in the treated gas supply flow path L10a.

[0042] The purge gas extraction flow path L91a is connected to the adsorption tank 101a and has an on-off valve V91a. The purge gas extraction flow path L92a is connected to the adsorption tank 102a and has an on-off valve V92a. It should be noted that the purge gas may also be discharged outside the system of the organic solvent treatment device 1. However, in the case of discharging to the outside of the system of the organic solvent treatment device 1, another organic solvent treatment device needs to be provided to treat the organic solvents contained in the purge gas.

[0043] The control unit 150a controls the opening and closing of the on-off valves V41a, V42a, V81a, V82a, V91a, V92a and the on-off baffles V101a, V102a, V201a, V202a so that each treatment tank 101a, 102a is used in the order of the adsorption process and the desorption process as described above.

[0044] Next, the operation of the gas treatment device 1 will be described. Here, refer toFigure 1 An example of the operation of the gas treatment device 1 will be described. In addition, in Figure 1 , a state where the adsorption process is performed in the first treatment tank 101a and the desorption process is performed in the second treatment tank 102a will be described.

[0045] It should be noted that in each treatment tank, the treatment is repeated in the order of adsorption process → desorption process → adsorption process →...

[0046] Among the respective on-off valves and on-off baffles, the on-off valves V42a, V82a, V92a and the on-off baffles V101a, V201a are opened, and the on-off valves V41a, V81a, V91a and the on-off baffles V102a, V202a are closed.

[0047] The gas to be treated is supplied from the gas-to-be-treated gas supply source to the first treatment tank 101a through the gas-to-be-treated gas supply flow path L10a and the branch flow path L11a, and the organic solvent contained in the gas to be treated is adsorbed by the adsorbent 101Aa in the first treatment tank 101a (adsorption process). Then, the treated gas is discharged to the outside of the system of the gas treatment device 1 through the extraction flow path L31a and the converging flow path L30a.

[0048] On the other hand, steam is supplied from the steam supply unit 110a to the second treatment tank 102a through the steam supply flow path L42a, whereby the organic solvent is desorbed from the adsorbent 102Aa (desorption process). Then, the steam containing the organic solvent desorbed from the adsorbent 102Aa passes through the organic solvent recovery flow path L52a, is condensed in the condenser 122a, and then flows into the separator 120a. The recovered solvent separated by the separator 120a is taken out to the outside of the system of the gas treatment device 1, and the exhaust gas present in the separator 120a returns to the gas-to-be-treated gas supply flow path L10a through the re-supply flow path L60a. The separated drainage is treated by the drainage treatment device 130a, the treated water is taken out to the outside of the system of the gas treatment device 1, and the aeration gas returns to the gas-to-be-treated gas supply flow path L10a through the aeration gas supply flow path L61a.

[0049] In this desorption process, the treatment gas serves as the purge gas and is sucked by the blower F2a and conveyed to the confluence flow path L10a through the confluence flow path L80a, the purge gas supply flow path L82a, the downstream chamber 102Ca of the treatment tank, and the purge gas extraction flow path L92a. By using the treatment gas as the purge gas, the amount of the clean gas discharged as the clean gas can be reduced compared with the case of supplying external air or the like as the purge gas from outside the system of the gas treatment device 1. Therefore, the gas treatment device can be further miniaturized. In addition, when another gas treatment device is connected in series at the rear stage of the gas treatment device to improve the removal rate, the treatment air volume of the gas treatment device at the rear stage can be reduced, and miniaturization can be achieved.

[0050] In addition, a blower for blowing the purge gas may be provided separately, but when the suction of the blower F1a is used, the initial cost of the gas treatment device 1 can be reduced.

[0051] As described above, the purge gas is always in a state of being supplied to the downstream chambers 101Ca and 102Ca of the treatment tank during the desorption process. When the desorption water vapor containing the organic solvent leaks into the downstream chamber of the treatment tank, the desorption water vapor containing the organic solvent is pushed by the purge gas and conveyed to the confluence flow path L10a. Therefore, the desorption water vapor containing the organic solvent does not stay in the downstream chambers 101Ca and 102Ca of the treatment tank. Therefore, when switching from the desorption process to the adsorption process, the desorption water vapor containing the organic solvent in the downstream chamber of the treatment tank does not discharge outside the system of the gas treatment device 1 through the extraction flow paths L31a and L32a. Therefore, the gas treatment device 1 can improve the removal rate of the organic solvent.

[0052] Next, a gas treatment device according to another embodiment of the present invention will be described.

[0053] Figure 2 It is a diagram schematically showing the structure of a gas treatment device 2 according to another embodiment of the present invention. As Figure 2 shown, the gas treatment device 2 is a device for removing and recovering an organic solvent from the gas to be treated. It should be noted that the gas to be treated is supplied to the gas treatment device 2 from a gas to be treated supply source (not shown) provided outside the system of the gas treatment device 2. The gas treatment device 2 includes three treatment tanks 101b to 103b, a gas to be treated supply flow path L10b, connection flow paths L21b to L23b, extraction flow paths L31b to L33b, a water vapor supply flow path L41b to L43b, an organic solvent recovery flow path L51b to L53b, a separator 120b, a re-supply flow path L60b, a dilution gas supply flow path L70b, a heater 140b, an on-off valve V70b, and a control unit 150b. It should be noted that in Figure 2In [the figure], the gas treatment device 2 is shown to have three treatment tanks, but the adsorption tank may also have four or more.

[0054] Each of the treatment tanks 101b to 103b has adsorbents 101Ab to 103Ab capable of adsorbing organic solvents and desorbing organic solvents. As the adsorbents 101Ab to 103Ab, granular activated carbon, honeycomb activated carbon, zeolite, activated carbon fiber, etc. can be used, but activated carbon fiber is preferably used. It should be noted that in Figure 2 the shown treatment tanks, it is configured that each treatment tank is filled with one adsorbent, but multiple adsorbents can also be filled. Each of the treatment tanks 101b to 103b is equipped with baffles V101b to V103b for switching the supply / non-supply of the gas to be treated to the gas to be treated supply port, and baffles V201b to V203b for switching the discharge / non-discharge of the treated gas after passing through the adsorbents 101Ab to 103Ab. In addition, each of the treatment tanks 101b to 103b has a treatment tank downstream chamber 101Cb to 103Cb inside, where the treated gas from which the organic solvent has been removed by the adsorbents 101Ab to 103Ab is retained until it is supplied to the extraction flow paths L31b to L33b.

[0055] In each of the treatment tanks 101b to 103b, the adsorption of organic solvents by the adsorbents 101Ab to 103Ab and the desorption of organic solvents by the adsorbents 101Ab to 103Ab are alternately performed. The details are as follows. That is, in one of the three treatment tanks 101b to 103b, a first adsorption process of adsorbing organic solvents from the gas to be treated supplied from the gas to be treated supply source by the adsorbent is performed, and in the other treatment tanks among the three treatment tanks 101b to 103b, a second adsorption process of adsorbing organic solvents from the treated gas (first adsorption process outlet gas) in the treatment tank used in the first adsorption process by the adsorbent and discharging the treated gas is performed, and during this period, a desorption process of desorbing organic solvents from the adsorbent is performed in the remaining one adsorption tank. In each of the treatment tanks 101b to 103b, it is repeated in the order of desorption process, second adsorption process, first adsorption process, and desorption process. It should be noted that in Figure 2 [the figure], the first adsorption process is performed in the first treatment tank 101b, the second adsorption process is performed in the second adsorption tank 102b, and the desorption process is performed in the third adsorption tank 103b.

[0056] The gas to be treated supply flow path L10b is a flow path for supplying the gas to be treated to each of the treatment tanks 101b to 103b. The upstream end of the gas to be treated supply flow path L10b is connected to the gas to be treated supply source.

[0057] A blower F1b is provided in the process gas supply flow path L10b. A cooler C1b and a heater H1b for adjusting the temperature and humidity of the process gas flowing into each of the processing tanks 101b to 103b to a desired range are provided at a position upstream of the blower F1b in the process gas supply flow path L10b. These devices and equipment can be appropriately set according to the pressure, temperature, and humidity of the process gas.

[0058] The process gas supply flow path L10b has branch flow paths L11b to L13b for supplying the process gas to each of the processing tanks 101b to 103b. An on-off valve V11b is provided in the branch flow path L11b. An on-off valve L12b is provided in the branch flow path L12b. An on-off valve V13b is provided in the branch flow path L13b.

[0059] Each of the connection flow paths L21b to L23b connects one processing tank to another processing tank in such a way that the process gas adsorbed with the organic solvent in the adsorbent of one processing tank (the processing tank used in the first adsorption process) among the three processing tanks 101b to 103b is introduced into the process gas supply port of another processing tank (the processing tank used in the second adsorption process) different from the one processing tank. Specifically, the first connection flow path L21b connects the processing gas discharge port of the first processing tank 101b to the process gas supply port of the second processing tank 102b. The second connection flow path L22b connects the processing gas discharge port of the second processing tank 102b to the process gas supply port of the third processing tank 103b. The third connection flow path L23b connects the processing gas discharge port of the third processing tank 103b to the process gas supply port of the first processing tank 101b.

[0060] Each of the connection flow paths L21b to L23b has on-off valves V24b to V26b for switching the supply / non-supply in order to selectively supply the processing gas from the adsorption tank used in the first adsorption process to the adsorption tank used in the second adsorption process. An on-off valve V24b is provided in the connection flow path L21b. An on-off valve V25b is provided in the connection flow path L22b. An on-off valve V26b is provided in the connection flow path L23b.

[0061] Each of the connection flow paths L21b to L23b has a converging flow path L20b where they converge. A blower F2b is provided in the converging flow path L20b. An on-off valve V21b is provided at a position where the first connection flow path L21b branches again from the converging flow path L20b. An on-off valve V22b is provided at a position where the second connection flow path L22b branches again from the converging flow path L20b. An on-off valve V23b is provided at a position where the third connection flow path L23b branches again from the converging flow path L20b.

[0062] The extraction flow paths L31b to L33b are flow paths for extracting the processed gas after adsorption treatment in each treatment tank 101b to 103b, that is, the first processed gas. The extraction flow paths L31b to L33b are connected to the processing gas discharge ports in each treatment tank 101b to 103b. An on-off valve V31b is provided in the first extraction flow path L31b. An on-off valve V32b is provided in the second extraction flow path L32. An on-off valve V33b is provided in the third extraction flow path L33b. Each of the extraction flow paths L31b to L33b has a converging flow path L30b that converges with each other. It should be noted that the on-off valve V31b and the on-off valve V24b, the on-off valve V32b and the on-off valve V25b, and the on-off valve V33b and the on-off valve V26b can be respectively a three-way valve or the like, and a single valve can also be used to control the flow path. The front end of the converging flow path L30b is outside the system of the gas treatment device 2. The front end can be external air, and in the case where it is desired to further improve the removal rate of the organic solvent, it can also be connected to a device (not shown) for treating the organic solvent.

[0063] The steam supply flow paths L41b to L43b are flow paths for supplying steam to each treatment tank 101b to 103b, and this steam is used to desorb the organic solvent adsorbed on the adsorbents 101Ab to 103Ab from the adsorbents 101Ab to 103Ab.

[0064] The steam is supplied from the steam supply unit 110b. It should be noted that the steam supply unit 110b can be provided inside the gas treatment device 2 or outside the system of the gas treatment device 2.

[0065] The first steam supply flow path L41b connects the steam supply unit 110b to the first treatment tank 101b. An on-off valve V41b is provided in the first steam supply flow path L41b. The second steam supply flow path L42b connects the steam supply unit 110b to the second treatment tank 102b. An on-off valve V42b is provided in the second steam supply flow path L42b. The third steam supply flow path L43b connects the steam supply unit 110b to the third treatment tank 103b. An on-off valve V43b is provided in the third steam supply flow path L43.

[0066] The organic solvent recovery flow paths L51b to L53b are flow paths for recovering the water vapor (desorbed gas) containing the organic solvent desorbed from the adsorbents 101Ab to 103Ab. Each of the organic solvent recovery flow paths L51b to L53b is connected to each of the treatment tanks 101b to 103b. Each of the organic solvent recovery flow paths L51b to L53b has a confluent flow path L50b that converges with each other. A condenser 122b is provided in the confluent flow path L50b. The condenser 122b cools the desorbed gas flowing in the confluent flow path L50b to condense the desorbed gas, and discharges the condensate (a mixed liquid of water and organic solvent generated by the condensation of the desorbed gas).

[0067] A separator 120b is provided at the downstream end of the confluent flow path L50b. The condensate flows into the separator 120b. Then, inside the separator 120b, the condensate is phase-separated into a liquid phase of separated drain water (sometimes slightly containing condensed water of water vapor of the organic solvent) and a liquid phase of recovered solvent, and the recovered solvent is taken out of the system of the gas treatment device 2. It should be noted that a space (exhaust gas) for the organic solvent in the gas phase is formed in the upper part of the separator 120b.

[0068] The re-supply flow path L60b is a flow path that connects the separator 120b and the gas to be treated supply flow path L10b. The upstream end of the re-supply flow path L60b is connected to the upper part of the separator 120b (the part where the organic solvent in the gas phase exists in the separator 120b). The downstream end of the re-supply flow path L60b is connected to the upstream part of the cooler C1b in the gas to be treated supply flow path L10b. Therefore, it is preferable that the organic solvent in the gas phase existing in the separator 120b is re-supplied to each of the treatment tanks 101b to 103b through the re-supply flow path L60b and the gas to be treated supply flow path L10b.

[0069] The drainage treatment device 130b is a device for removing the organic solvent contained in the above-mentioned separated drain water. It is supplied from the liquid phase of the separated drain water of the separator 120b, removes the organic solvent from the separated drain water, and discharges the treated water out of the system of the gas treatment device 2. As a specific drainage treatment device 130b, an aeration device that volatilizes the organic solvent contained in the separated drain water by subjecting the separated drain water to aeration treatment and separates it into aeration gas containing the organic solvent and treated water can be cited. It should be noted that the aeration gas is connected to the upstream part of the cooler C1b in the gas to be treated supply flow path L10b via the aeration gas supply flow path L61b. Although not shown, a dehumidification unit may also be provided in the aeration gas supply flow path for the purpose of removing moisture in the aeration gas.

[0070] The dilution gas supply flow path L70b is a flow path for supplying dilution gas for promoting the drying of the first adsorbents 101Ab to 103Ab after the desorption process to the connection flow paths L21b to L23b. The dilution gas is composed of a gas containing at least one of external air, measurement air, nitrogen, and argon.

[0071] The heater 140b is provided in the dilution gas supply flow path L70b. The heater 140b heats the dilution gas so that the temperature of the dilution gas is higher than the temperature of the gas to be processed (about 40 °C) flowing in the connection flow paths L21b to L23b.

[0072] The on-off valve V70b is provided in the dilution gas supply flow path L70b. The on-off valve V70b can adjust the opening degree.

[0073] The purge gas supply flow paths L81b to L83b are flow paths for supplying the processing gas flowing in the converging flow path L30b as purge gas to the downstream chambers 101Cb to 103Cb of the processing tank. The purge gas supply flow path L81b is connected to the adsorption tank 101b and has an on-off valve V81b. The purge gas supply flow path L82b is connected to the adsorption tank 102b and has an on-off valve V82b. The purge gas supply flow path L83b is connected to the adsorption tank 103b and has an on-off valve V83b. It should be noted that for the purge gas, external air, measurement air, nitrogen, argon, etc. can also be supplied from outside the organic solvent treatment device 2.

[0074] The purge gas extraction flow paths L91b to L93b are flow paths for returning the purge gas after purging the inside of the downstream chambers 101Cb to 103Cb of the processing tank to the upstream side of the blower F2b on the connection flow path L20b. The purge gas extraction flow path L91b is connected to the adsorption tank 101b and has an on-off valve V91b. The purge gas extraction flow path L92b is connected to the adsorption tank 102b and has an on-off valve V92b. The purge gas extraction flow path L93b is connected to the adsorption tank 103b and has an on-off valve V93b. It should be noted that the purged purge gas can be returned to the upstream side of the blower F1b on the gas to be processed supply flow path L10b, or can also be discharged to the outside of the system of the organic solvent treatment device 2. However, in the case of discharging to the outside of the system of the organic solvent treatment device 2, another organic solvent treatment device needs to be provided to treat the organic solvent contained in the purge gas.

[0075] For the purpose of miniaturizing the device, the purge gas extraction flow paths L91b to L93b can also be used in combination with the connection flow paths L21b to L23b.

[0076] The control unit 150b controls the opening degree of the on-off valve V70b. Specifically, the control unit 150b controls the opening degree of the on-off valve V70b such that the temperature of the gas to be processed flowing into the adsorption tank (the processing tank disposed on the downstream side in the flow of the gas to be processed among the three processing tanks 101b to 103b connected by the connection flow paths L21b to L23b) used in the second adsorption process is maintained within a specified range (for example, 40°C to 80°C).

[0077] It should be noted that the temperature of the mixed gas flowing into the adsorption tank used in the second adsorption process is detected by the temperature sensor 152b. The temperature sensor 152b is provided in the converging flow path L20b.

[0078] The control unit 150b controls the opening and closing of the on-off valves V11b to V13b, V21b to V26b, V31b to V33b, V41b to V43b, V81b to V83b, V91b to V93b, and the on-off baffles V101b to V103b, V201b to V203b so that the respective processing tanks 101b to 103b are used in the order of the second adsorption process, the first adsorption process, and the desorption process as described above.

[0079] Next, the operation of the gas treatment device 2 will be described. Here, refer to Figure 2 An example of the operation of the gas treatment device 2 will be described. In addition, in Figure 2 it is assumed that the first adsorption process is performed in the first processing tank 101b, the second adsorption process is performed in the second processing tank 102b, and the desorption process is performed in the third processing tank 103b for the description.

[0080] It should be noted that in each processing tank, the processing is repeated in the order of the first adsorption process → desorption process → second adsorption process → first adsorption process →....

[0081] Among the on-off valves and the on-off baffles, the on-off valves V11b, V21b, V24b, V32b, V43b, V83b, V93b, and the on-off baffles V101b, V102b, V201b, V202b are opened, and the on-off valves V12b, V13b, V22b, V23b, V25b, V26b, V81b, V82b, V91b, V92b, V31b, V33b, V41b, V42b, and the on-off baffles V103b, V203b are closed.

[0082] A gas to be treated is supplied from a gas-to-be-treated supply source to the first treatment tank 101b through a gas-to-be-treated supply flow path L10b and a branch flow path L11b, and an organic solvent contained in the gas to be treated is adsorbed by an adsorbent 101Ab in the first treatment tank 101b (first adsorption step). Then, the gas to be treated is supplied to the second treatment tank 102b through a first connection flow path L21b, and an organic solvent contained in the gas supplied to the adsorbent 102Ab in the second treatment tank 102b is further adsorbed (second adsorption step). Then, the treated gas discharged from the second treatment tank is discharged to the outside of the system of the gas treatment device 2 through a converging flow path L30b. In the second adsorption step (especially in the initial stage) in the second treatment tank 102b, the second adsorbent 102Ab is dried using the supplied gas. Since the second adsorption step is carried out after a desorption step using water vapor, the adsorbent 102Ab contains moisture, and drying is required to improve the adsorption performance. Drying will be described again in the later stage. It should be noted that the drying carried out in this second adsorption step can also be handled by this system even in a system separated as a drying step, that is, a system in which each treatment tank is processed in the order of first adsorption step → desorption step → drying step → second adsorption step → first adsorption step →....

[0083] On the other hand, water vapor is supplied from a water vapor supply unit 110b to a third treatment tank 103b through a third water vapor supply flow path L43b, whereby an organic solvent is desorbed from an adsorbent 103Ab (desorption step). Then, the water vapor containing the organic solvent desorbed from the adsorbent 103Ab passes through an organic solvent recovery flow path L53b, is condensed in a condenser 122b, and then flows into a separator 120b. The recovered solvent separated by the separator 120b is taken out of the system of the gas treatment device 2, and the exhaust gas present in the separator 120b is returned to the gas-to-be-treated supply flow path L10b through a re-supply flow path L60b. The separated drainage is treated by a drainage treatment device 130b, the treated water is taken out of the system of the gas treatment device 2, and the aeration gas is returned to the gas-to-be-treated supply flow path L10b through an aeration gas supply flow path L61b.

[0084] In this desorption process, the processing gas serves as the purge gas and is sucked by the blower F2b and conveyed to the converging flow path L20b through the converging flow path L80b, the purge gas supply flow path L83b, the downstream chamber 103Cb of the processing tank, and the purge gas extraction flow path L93b. By using the processing gas as the purge gas, the amount of the clean gas discharged as the clean gas can be reduced compared with the case of supplying external air or the like as the purge gas from outside the system of the gas processing device. Therefore, the gas processing device can be further miniaturized. In addition, when a gas processing device is further connected in series at the rear stage of the gas processing device to improve the removal rate, the processing air volume of the gas processing device at the rear stage can be reduced, and miniaturization can be achieved.

[0085] In addition, a blower for blowing the purge gas may be provided separately. However, when the suction of the blower F2b is used, the initial cost of the gas processing device 2 can be reduced.

[0086] As described above, a state is formed in which the purge gas is always supplied to the downstream chambers 101Cb to 103Cb of the processing tank during the desorption process. When the desorption water vapor containing the organic solvent leaks into the downstream chamber of the processing tank, the desorption water vapor containing the organic solvent is pressed by the purge gas and conveyed to the converging flow path L20b. Therefore, the desorption water vapor containing the organic solvent does not stay in the downstream chambers 101Cb to 103Cb of the processing tank. Therefore, when switching from the desorption process to the second adsorption process, the desorption water vapor containing the organic solvent in the downstream chamber of the processing tank does not discharge to the outside of the system of the gas processing device 2 through the extraction flow paths L31b to L33b. Therefore, the gas processing device 2 can improve the removal rate of the organic solvent.

[0087] In addition, for example, the gas processing device 2 may have four or more processing tanks. In this case, the desorption process is performed in one processing tank, and during this period, the adsorption process is performed in multiple stages in the remaining three or more processing tanks connected in series in the connection flow path.

[0088] In the gas processing device 2, the adsorbents 101Ab to 103Ab cannot obtain sufficient adsorption performance in a state containing moisture. Therefore, both the first adsorption process and the second adsorption process require sufficient drying of the first adsorbents 101Ab to 103Ab. In the desorption process, since water vapor is used, the first adsorbents 101Ab to 103Ab after the desorption ends contain moisture from the water vapor. Therefore, the adsorbents 101Ab to 103Ab that are particularly required to be dried are those after the desorption ends, that is, the adsorbents 101Ab to 103Ab that perform the second adsorption process.

[0089] In the second adsorption step, drying is carried out simultaneously with adsorption by passing the gas discharged in the first adsorption step, but sometimes sufficient drying cannot be achieved. Therefore, in this gas treatment apparatus 2, a dilution gas is supplied and used as an auxiliary gas for drying. In order to obtain sufficient drying of the adsorbents 101Ab to 103Ab, the heater 140b described above may sometimes be used in combination. If sufficient drying can be achieved using the gas at the outlet of the first adsorption step and the purge gas, the dilution gas may not be added.

[0090] Hereinafter, embodiments using the above-described gas treatment apparatus will be described.

[0091] <Example 1>

[0092] Using the Figure 1 The gas treatment apparatus 1 shown above was used to perform the following treatment. In an organic solvent-containing gas as an example of the gas to be treated, the flow rate of the gas to be treated at 25°C containing 5000 ppm of dichloromethane was set to 4.0 Nm 3 / min. In addition, each pipe was connected using a circular pipe. The adsorbent used was activated carbon fiber.

[0093] First, the gas to be treated was supplied to the gas-to-be-treated gas supply flow path L10a of the gas treatment apparatus 1. It was blown from the blower F1a to the first treatment tank 101a that became the adsorption step at a flow rate of 8.0 Nm 3 / min. The gas treated by the first treatment tank 101 was discharged outside the system of the gas treatment apparatus 1 as a treated gas.

[0094] During the adsorption step in the first treatment tank 101a, the second treatment tank 102a was introduced with desorption steam to perform a desorption step. At this time, 0.5 Nm of the treated gas on the converging flow path L30a was supplied as a purge gas to the downstream chamber 102Ca of the treatment tank located in the second treatment tank 102b at a flow rate of 3 / min. The purge gas was introduced into the gas-to-be-treated gas supply flow path L10a.

[0095] The process was switched at the moment when the dichloromethane concentration in the adsorption step outlet gas discharged from the first treatment tank 101a reached 50 ppm. The treatment was carried out until the first adsorption tanks 101a and 102a repeated the adsorption step and the desorption step 2100 times, respectively.

[0096] The average dichloromethane concentration of the treated gas at the moment when the adsorption step and the desorption step were carried out 2100 times was 7 ppm.

[0097] <Example 2>

[0098] Using the Figure 2The gas treatment device 2 shown below performs the following treatment. In the organic solvent-containing gas, which is an example of the gas to be treated, the flow rate of the gas to be treated at 25°C containing 27,000 ppm of dichloromethane is set to 2.2 Nm 3 / min. In addition, each pipe is connected using a circular pipe. The adsorbent used is activated carbon fiber.

[0099] First, the gas to be treated is supplied to the gas supply flow path L10b of the gas treatment device 2. It is blown from the blower F1b at a flow rate of 2.2 Nm 3 / min into the first treatment tank 101b in the first adsorption process. Next, for the gas at the outlet of the first adsorption process discharged from the first treatment tank 101b, it is blown into the second treatment tank 102b, which becomes the second adsorption process, as the inlet gas for the second adsorption process by the blower F2b. At this time, the inlet gas for the second adsorption process is adjusted to 2.9 Nm 3 / min and 50°C using the dilution gas and the purge gas. The gas treated in the second treatment tank 102 is discharged outside the system of the gas treatment device 2 as the treated gas.

[0100] During the period when the first adsorption process is carried out in the first treatment tank 101b and the second adsorption process is carried out in the second treatment tank 102b, the third treatment tank 103b is introduced with desorption steam to perform the desorption process. At this time, 0.5 Nm of the treated gas on L30b is supplied as the purge gas to the downstream chamber 103Cb of the treatment tank located in the third treatment tank 103b via L80b and L83b. 3 / min.

[0101] The process is switched at the moment when the concentration of dichloromethane in the outlet gas of the first adsorption process discharged from the first treatment tank 101b reaches 1300 ppm. The treatment is carried out until the first adsorption tanks 101b, 102b, and 103b respectively repeat the first adsorption process, desorption process, and second adsorption process 2100 times.

[0102] The average concentration of dichloromethane in the treated gas at the moment when the first adsorption process, desorption process, and second adsorption process are treated 2100 times is 8 ppm.

[0103] <Comparative Example 1>

[0104] The same gas to be treated as in Example 1 is treated using the gas treatment device 1 in the same manner as in Example 1. However, the purge in the downstream chamber of the treatment tank in the desorption process is not carried out, and the purge gas supply flow paths L81a, L82a, and the purge gas extraction flow path are closed. As a result, the average concentration of dichloromethane in the treated gas is 36 ppm.

[0105] <Comparative Example 2>

[0106] In the same manner as in Example 2, the gas treatment apparatus 2 was used to treat the same gas to be treated as in Example 2. However, the purge in the downstream chamber of the treatment tank in the desorption step was not performed, and the purge gas supply flow paths L81b to L83b and the purge gas extraction flow path were closed. As a result, the average concentration of dichloromethane in the treatment gas was 30 ppm.

[0107] As can be seen from the above, the example has a flow path for performing purging with respect to the comparative example. Therefore, by performing purging, the removal performance of the gas treatment apparatus can be further improved.

[0108] It should be noted that the above-described embodiments and each example are illustrative and not restrictive. In addition, embodiments and examples formed by appropriately combining the structures disclosed in the embodiments and each example are also included in the present invention. In other words, the technical scope of the present invention is effective according to the technical solution, including meanings equivalent to the description of the technical solution and all changes, corrections, substitutions, etc. within the scope.

[0109] Industrial Applicability

[0110] With the gas treatment apparatus of the present invention, the removal rate of the organic solvent can be increased, which is useful industrially.

[0111] Description of Reference Numerals:

[0112] 1 Gas treatment apparatus

[0113] 101a First treatment tank

[0114] 101Aa First adsorbent

[0115] 102a Second treatment tank,

[0116] 102Aa First adsorbent

[0117] 101Ca, 102Ca Downstream chamber of the treatment tank

[0118] 110a Steam supply unit

[0119] 120a Separator

[0120] 130a Drainage treatment device

[0121] 150a Control unit

[0122] L10a Gas to be treated supply flow path

[0123] L31a, L32a Extraction flow path

[0124] L41a, L42a Steam supply flow path

[0125] L51a, L52a Organic solvent recovery flow path

[0126] L60a Re - supply flow path

[0127] L81a, L82a Purge gas supply flow path

[0128] L91a, L92 Purge gas extraction flow path

[0129] V41b, V42a, V81a, V82a, V91a, V92a On - off valves

[0130] V101a, 102a, V201a, 202a On - off baffles

[0131] F1a Blower (gas to be treated supply section)

[0132] 2 Gas treatment device

[0133] 101b First treatment tank

[0134] 101Ab First adsorbent

[0135] 102b Second treatment tank

[0136] 102Ab First adsorbent

[0137] 103b Third treatment tank

[0138] 103Ab First adsorbent,

[0139] 101Cb~103Cb Chambers downstream of the treatment tank

[0140] 110b Steam supply section

[0141] 120b Separator

[0142] 130b Wastewater treatment equipment

[0143] 140b Heater

[0144] 150b Control section

[0145] 152b Temperature sensor

[0146] L10b Gas to be treated supply flow path

[0147] L21b~L23b Connecting flow paths

[0148] L31b~L33b Extraction flow paths

[0149] L41b, L42b Steam supply flow paths

[0150] L51b - L53b Organic solvent recovery flow path

[0151] L60b Re - supply flow path

[0152] L70b Dilution gas supply flow path

[0153] L81a - L82b Purge gas supply flow path

[0154] L91b - L93b Purge gas extraction flow path

[0155] V11b - V13b, V21b - V26b, V31b - V33b, V41b - V43b On - off valves

[0156] V70b, V81b - V83b, V91b - V93b On - off valves

[0157] V101b - V103b, V201b - V203b On - off baffles

[0158] F1b Blower (gas to be treated supply section).

Claims

1. A gas treatment device, which includes a treatment tank having an adsorbent capable of adsorbing and desorbing an organic solvent, and the treatment tank alternately performs an adsorption treatment and a desorption treatment. The adsorption treatment is to make the gas to be treated containing the organic solvent contact the adsorbent to adsorb the organic solvent by the adsorbent, and the desorption treatment is to desorb the organic solvent from the adsorbent using steam. It is characterized in that, the treatment tank has a downstream chamber of the treatment tank, and the downstream chamber of the treatment tank is for introducing the gas to be treated, i.e., the treated gas, which has been subjected to the adsorption treatment by the adsorbent, connected to the downstream chamber of the treatment tank are: a take-out flow path for discharging the treated gas, a purge gas supply flow path for supplying a purge gas for purging the downstream chamber of the treatment tank, and a purge gas take-out flow path for discharging the purge gas from the downstream chamber of the treatment tank, the end of the purge gas supply flow path is connected to the take-out flow path.

2. The gas treatment device according to claim 1, characterized in that, during the period of supplying the steam to the treatment tank, the purge gas is supplied to the downstream chamber of the treatment tank.

3. The gas treatment device according to claim 1, characterized in that, the end of the purge gas take-out flow path is connected to the gas to be treated supply flow path for supplying the gas to be treated to the treatment tank.

4. The gas treatment device according to claim 1, characterized in that, at least a part of the take-out flow path is shared with the purge gas supply flow path.

5. The gas treatment device according to any one of claims 1 to 4, characterized in that, the gas treatment device includes a plurality of the treatment tanks, and in a part of the plurality of treatment tanks, the adsorption treatment is performed, and in the remaining treatment tanks, the desorption treatment is performed.

6. The gas treatment device according to any one of claims 1 to 4, characterized in that, the gas treatment device includes three or more of the treatment tanks, and in a part of the three or more treatment tanks, the desorption treatment is performed, and the remaining treatment tanks are connected in series in multiple stages through a connection flow path to perform the adsorption treatment.

7. The gas treatment device according to claim 6, characterized in that, at least a part of the connection flow path is shared with the purge gas take-out flow path.

8. The gas treatment device according to claim 6, characterized in that, the end of the purge gas take-out flow path is connected to the connection flow path.

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