Organic Solvent Recovery System

Abstract

Provided is an organic solvent recovery system comprising a treatment tank in which there is accommodated an adsorbent material by which an organic solvent is adsorbed and removed from an organic-solvent-containing gas being treated. The organic solvent recovery system also comprises: an organic solvent recovery device that repeatedly carries out an adsorption treatment in which the gas being treated that is supplied to the treatment tank is brought into contact with the adsorbent material and a treatment gas is discharged, and a desorption treatment in which the organic solvent is desorbed from the adsorbent material by using water vapor for desorption that is supplied to the treatment tank and a desorption gas is discharged; a heat exchanger having a heating unit through which flows the desorption gas discharged from the organic solvent recovery device, and a heat-absorbing unit to which replenishment water is supplied, the heat exchanger indirectly heating the replenishment water in the heat-absorbing unit by using the desorption gas flowing through the heating unit to generate water vapor, and discharging the indirectly heated desorption gas; and a cooling unit that cools the desorption gas discharged from the heat exchanger and discharges a condensed liquid. The organic solvent recovery system additionally comprises a water vapor supply unit that supplies the water vapor to the heating unit of the heat exchanger. The heat exchanger supplies the water vapor generated from the replenishment water to the organic solvent recovery device as at least part of the water vapor for desorption.

Description

[Technical field]

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

[0002] The organic solvent recovery system is equipped with a pair of treatment tanks that use an adsorbent to adsorb the organic solvent in the gas to be treated, a treated gas supply device and a desorption gas supply device for each treatment tank, and employs a mechanism for switching between an adsorption process in which the gas to be treated is supplied to the treatment tank, and a desorption process in which the desorption gas is supplied.

[0003] For example, activated carbon fiber is used as an adsorbent for gas treatment equipment. Activated carbon fiber has excellent function of adsorbing low concentration organic solvent-containing gas and is used as an adsorbent. For example, JP 2014-147864 A (Patent Document 1) discloses a gas treatment equipment in which activated carbon fiber is fixed to a support or self-supported in a cylindrical shape and vertically arranged in a core material.

[0004] Furthermore, Japanese Utility Model Publication No. 58-161636 (Patent Document 2) discloses an activated carbon desorption device in which the condensation side of a heat exchanger is connected to the desorption steam outlet of an activated carbon adsorber (treatment tank), water is supplied to the evaporation side of the heat exchanger, a pressure reducing blower is installed in a line connecting the evaporation side of the heat exchanger and the desorption steam inlet of the activated carbon adsorber, and the heat of the desorption steam is used to evaporate the water on the evaporation side to generate desorption steam, thereby reducing the amount of steam used. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-147864 A [Patent Document 2] Japanese Utility Model Application Publication No. 58-161636 Summary of the Invention [Problem to be solved by the invention]

[0006] In the desorption process, the temperature of the desorption gas discharged from the treatment tank changes from time to time due to fluctuations in the outside air temperature, the organic solvent concentration in the gas to be treated, the humidity of the gas to be treated, etc., so when desorption steam is generated using the heat of the desorption gas via a heat exchanger as in Patent Document 2, there is a risk that the flow rate of the desorption steam cannot be sufficiently secured.

[0007] Furthermore, in the early stage of the desorption step, much of the heat of the desorption steam supplied to the treatment tank is consumed for heating the adsorbent, the treatment tank body, the piping, and the switching valve, resulting in a low temperature of the desorption gas discharged from the treatment tank. Therefore, when desorption steam is generated using the heat of the desorption gas via a heat exchanger as in Patent Document 2, there is a risk that almost no desorption steam can be generated in the early stage of the desorption step. As a result, there is a risk that a sufficient flow rate of the desorption steam cannot be ensured in the early stage of the desorption step.

[0008] Due to these problems, when considering an organic solvent recovery apparatus having a mechanism for generating desorption steam using the heat of the desorption gas, the flow rate of the desorption steam during the desorption process is not stable, which may reduce the desorption efficiency of the organic solvent and the recovery efficiency of the organic solvent.

[0009] In addition, the patent document states that the condensed water of the desorbed gas in the heat exchanger may be acidic due to decomposition products of organic solvents contained in the treated gas. The high temperature state close to the steam temperature and the high concentration caused by repeated drying and wetting increase the corrosive effect, causing pitting corrosion of the heat exchanger members. As a result, there is a risk of accidents such as leakage of the desorbed gas due to corrosion of the heat exchanger members.

[0010] In view of the above problems, the present invention has an object to provide an organic solvent recovery system which has a mechanism for generating desorption steam using the heat of the desorption gas, ensures a sufficient flow rate of the desorption steam supplied to the treatment tank, improves the recovery efficiency of the organic solvent, and reduces corrosion of components due to decomposition products of the organic solvent. [Means for solving the problem]

[0011] The organic solvent recovery system of the present invention has the following configuration.

[0012] an organic solvent recovery apparatus including a treatment tank containing an adsorbent that adsorbs and removes an organic solvent from a gas to be treated that contains the organic solvent, and repeats an adsorption process in which the gas to be treated that is supplied to the treatment tank is brought into contact with the adsorbent to discharge a treated gas, and a desorption process in which the organic solvent is desorbed from the adsorbent by a desorption steam supplied to the treatment tank and a desorbed gas is discharged; a heat exchanger including a heat generating section through which the desorption gas discharged from the organic solvent recovery apparatus passes and a heat absorbing section to which makeup water is supplied, the heat exchanger indirectly heating the makeup water in the heat absorbing section with the desorption gas passing through the heat generating section to generate steam, and discharging the indirectly heated desorption gas; a cooling unit that cools the desorption gas discharged from the heat exchanger and discharges a condensate, a water vapor supply unit that supplies water vapor to the heat generating unit of the heat exchanger, The heat exchanger supplies the water vapor generated from the make-up water to the organic solvent recovery apparatus as at least a part of the desorption water vapor.

[0013] The organic solvent recovery system may further include a pressure measuring unit that measures the pressure of a gas phase portion of the heat absorption unit of the heat exchanger, and may control the flow rate of water vapor supplied to the heat generation unit based on the measurement result of the pressure measuring unit.

[0014] The organic solvent recovery system may further include a temperature measuring unit that measures a temperature of a liquid phase portion of the heat absorption unit of the heat exchanger, and may control a flow rate of water vapor supplied to the heat generation unit based on a measurement result of the temperature measuring unit.

[0015] The organic solvent recovery system described above includes a path for supplying the desorption gas discharged from the treatment tank to the heat exchanger, and a path for supplying the desorption gas discharged from the treatment tank to the cooling section, and in the early stage of the desorption treatment, water vapor is supplied to the heat generation section of the heat exchanger, and the desorption gas discharged from the treatment tank is supplied to the cooling section, and in the later stage of the desorption process, the desorption gas is supplied to the heat generation section of the heat exchanger, and the desorption gas after passing through the heat generation section is supplied to the cooling section.

[0016] In the above organic solvent recovery system, the organic solvent recovery apparatus may include a condensate reservoir section for storing condensate discharged from the cooling section, and the heat exchanger may include a desorption gas outlet receiving section in which the desorption gas accumulates after indirect heating, a piping path for supplying the uncondensed desorption gas from the desorption gas outlet receiving section to the cooling section, and a piping path for supplying the desorption gas that has become condensed liquid from the desorption gas outlet receiving section to the condensate reservoir section.

[0017] In the organic solvent recovery system, the heat exchanger may be a multi-tube heat exchanger including a tube portion, which is the heat generating portion, inside a container portion, which is the heat absorbing portion.

[0018] In the organic solvent recovery system, the water vapor supply unit may be connected to or may share a desorption water vapor supply unit which directly supplies the desorption water vapor to the organic solvent recovery apparatus. Effect of the Invention

[0019] According to the present invention, it is possible to provide an organic solvent recovery system which has a mechanism for generating desorption steam using the heat of the desorption gas, ensures a sufficient flow rate of the desorption steam supplied to the treatment tank, improves the recovery efficiency of the organic solvent, and reduces corrosion of the heat exchanger components due to decomposition products of the organic solvent. [Brief description of the drawings]

[0020] [Figure 1] 1 is a conceptual diagram showing a configuration of an organic solvent recovery device in a first embodiment. [Diagram 2] 4 is a time chart showing the time-dependent switching between an adsorption process and a desorption process in the organic solvent recovery apparatus in the first embodiment. [Diagram 3] FIG. 11 is a conceptual diagram showing a configuration of an organic solvent recovery device in a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An organic solvent recovery system according to an embodiment of the present invention will be described below with reference to the drawings. In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present invention is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. The same reference numbers are used for the same or corresponding parts, and duplicate descriptions may not be repeated. It is intended from the beginning that the configurations in the embodiments will be used in appropriate combinations.

[0022] In this specification, the organic solvent is methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, trichloroethylene, tetrachloroethylene, o-dichlorobenzene, m-dichlorobenzene, fluorocarbon-112, fluorocarbon-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, 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, decalin, benzene, toluene, m-xylene, p-xylene, o-xylene, ethylbenzene, 1,3,5-trimethylbenzene, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and dimethylsulfoxide.

[0023] [Embodiment 1] The organic solvent recovery system of the first embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the configuration of an organic solvent recovery system 1A of the first embodiment.

[0024] The organic solvent recovery system 1A includes an organic solvent recovery device 100, a heat exchanger 115, and a condenser 111 as a cooling section. The organic solvent recovery apparatus 100 includes a first treatment tank 104A and a second treatment tank 104B. The first treatment tank 104A includes a cylindrical first adsorbent 105A, and the second treatment tank 104B includes a cylindrical second adsorbent 105B. The first adsorbent 105A and the second adsorbent 105B are passed from the outside to the inside to perform an adsorption process (adsorption process), and water vapor is passed from the inside to the outside to perform a desorption process (desorption process). The first adsorbent 105A and the second adsorbent 105B are made of, for example, activated carbon fiber or activated carbon.

[0025] The first treatment tank 104A and the second treatment tank 104B are connected to a treated gas inlet line 103 and a desorption gas line 110. In order to open and close the connection to the treated gas inlet line 103 and the desorption gas line 110, the first treatment tank 104A and the second treatment tank 104B are provided with a first automatic lower damper 107A and a second automatic lower damper 107B, respectively.

[0026] A first automatic upper damper 106A and a second automatic upper damper 106B for controlling the flow of the gas I to be treated are provided above the first treatment tank 104A and the second treatment tank 104B, respectively.

[0027] A heat exchanger 115 is connected to the desorption gas line 110. The heat exchanger 115 has a desorption gas inlet chamber 115C to which the desorption gas line 110 is connected. The heat exchanger 115 also has a desorption gas outlet chamber 115D, which is a desorption gas outlet receiving section to which a heat exchanger outlet gas line 117 and a heat exchanger condensate line 118 are connected. Furthermore, makeup water VI is supplied to the makeup water storage section 115E. The makeup water VI is sent to the makeup water storage section 115E by, for example, a liquid delivery pump.

[0028] The heat exchanger 115 indirectly heats the make-up water VI in the make-up water storage section 115E with the desorption gas supplied from the desorption gas line 110, thereby evaporating the make-up water VI to generate water vapor.

[0029] The makeup water storage section 115E is decompressed so that the boiling point is, for example, 70°C to 97°C, preferably 75°C to 95°C, and the generated water vapor is supplied to the steam compressor 122 as regenerated water vapor through a regenerated water vapor line 119 connected to the heat exchanger 115. The steam compressor 122 is a mechanism that uses high-pressure water vapor as a driving source (hereinafter, driving water vapor) to draw in constant-pressure water vapor (hereinafter, sucked water vapor) in a reduced pressure state and boosts the pressure to medium-pressure water vapor (hereinafter, discharged water vapor). In the present invention, high-pressure water vapor VIII (a part of water vapor V) is supplied to the steam compressor 122 as driving water vapor through a steam line 121 for the steam compressor, so that the regenerated water vapor is sucked in through the regenerated water vapor line 119 as sucked water vapor, and the desorption water vapor, which is a mixture of water vapor VIII and regenerated water vapor, is discharged through the desorption water vapor line 108 as discharged water vapor. The desorption steam discharged from the steam compressor 122 is supplied to the first treatment tank 104A and the second treatment tank 104B in which the desorption step is performed through the desorption steam line 108. Note that the steam compressor 122 may be replaced by a compressor having a similar effect, such as a roots blower or a turbo blower.

[0030] A heat exchanger steam supply line 120, which is a steam supply unit for supplying steam VII, which is a part of the steam V, is connected to the makeup water storage unit 115E. By supplying the steam VII, the makeup water storage unit 115E can be kept at a predetermined pressure or higher (for example, at a gauge pressure of -0.099 MPa or higher), and the flow rate of the intake steam sucked into the steam compressor 122, i.e., the regenerated steam, can be sufficiently ensured. As a result, the flow rate of the discharged steam from the steam compressor 122, i.e., the desorption steam, can be sufficiently ensured, and the desorption efficiency of the organic solvent in the desorption step of the organic solvent recovery device 100 is maintained high. In addition, by supplying the steam VII during a time period when the temperature of the desorption gas supplied to the heat exchanger 115 is low, the makeup water VI in the heat exchanger 115 body and the makeup water storage unit 115E can be maintained at a high temperature, and the makeup water VI can be efficiently evaporated.

[0031] The makeup water storage section 115E is provided with a pressure sensor 115F, which is a pressure measuring section that measures the pressure inside the heat exchanger 115. In addition, an adjustment valve V4 that adjusts the flow rate of the water vapor VII is provided on the heat exchanger water vapor supply line 120.

[0032] A control unit 115G that adjusts the flow rate of the water vapor VII is provided in the heat exchanger 115. Specifically, the control unit 115G adjusts the opening of the adjustment valve V4 to supply the water vapor VII so that the pressure of the makeup water storage unit 115E detected by the pressure sensor 115F is maintained within a predetermined range (approximately −0.099 to −0.080 MPa in gauge pressure).

[0033] The heat exchanger 115 is preferably a multi-tube heat exchanger. The multi-tube heat exchanger is a heat exchanger in which a large number of tubes, which are tubes, are arranged in a cylinder, which is a container part, called a shell, and the surface of the tubes acts as a heat transfer surface, and heat is exchanged between a fluid flowing inside the tube 115B (hereinafter, the tube side) and a fluid flowing between the outside of the tube 115B and the inside of the shell 115A (hereinafter, the shell side). In other words, the tube 115B is a heat generating part that provides heat, and the shell 115A is a heat absorbing part that receives heat. The tube 115B connects the desorption gas inlet chamber 115C and the desorption gas outlet chamber 115D. Furthermore, in the heat exchanger 115 of the present invention, the tube 115B is arranged so as to face horizontally, and the tube side acts as a condensation side that supplies the desorption gas, and the shell side acts as an evaporation side that supplies the makeup water VI and the steam VII. It should be noted that other types of heat exchangers may be used instead as long as they have the same effect as the heat exchanger, such as plate type or spiral type structures.

[0034] The make-up water VI always remains in the shell 115A in an amount that contacts a part of the tube 115B. When the make-up water VI comes into contact with the tube 115B, the make-up water VI receives heat from the desorbed gas and evaporates. In addition, the tube 115B also serves to heat the make-up water to the evaporation temperature, so there is no need to provide a separate make-up water heating device for heating the make-up water VI.

[0035] It is preferable that the heat exchanger 115 adjusts the water level of the makeup water VI so that a part of the tube 115B does not come into contact with the makeup water VI in the makeup water storage section 115E. Specifically, a part of the tube 115B is located in a gas phase part in the shell 115A between the water level of the makeup water VI and the regenerated steam line 119. The tube 115B located in the gas phase part in the shell 115A heats the regenerated steam, and it is possible to prevent the regenerated steam from condensing before being sucked into the steam compressor 122. Note that, as a means for adjusting the water level of the makeup water VI, for example, a control method using a float type, a spacer type, a differential pressure type, or a capacitance type liquid level gauge can be considered.

[0036] A desorbed gas outlet chamber 115D of the heat exchanger 115 is connected to a heat exchanger outlet gas line 117 and is connected to the condenser 111. Inside the condenser 111, heat exchange occurs between the desorbed gas that has completed heat exchange in the heat exchanger 115 and cooling water, and the desorbed gas is cooled and condensed.

[0037] The condensate condensed in the condenser 111 is supplied to a separator 113, which is a condensate reservoir, through a condenser condensate line 112. The separator 113 separates the condensate sent from the condenser condensate line 112 into a layer of recovered solvent 113A and a layer of separated wastewater 113B. The separated wastewater 113B may be discharged after aeration by an aeration device.

[0038] A three-way on-off valve V3 is provided on the desorption gas line 110. One downstream side of the on-off valve V3 is connected to a desorption gas inlet chamber 115C of a heat exchanger 115, and the other downstream side is connected to a condenser 111 via a condenser line 116. The on-off valve V3 can switch between supplying the desorption gas to the heat exchanger 115 and supplying it to the condenser 111. Note that a similar switching operation may be performed by using a plurality of two-way on-off valves instead of the three-way on-off valve V3.

[0039] A heat exchanger condensate line 118 is connected to the desorbed gas outlet chamber 115D of the heat exchanger 115. The heat exchanger condensate line 118 is connected to the separator 113. The desorbed gas that has completed heat exchange in the tube 115B of the heat exchanger 115 is separated into uncondensed desorbed gas and condensed condensate, and supplied to the desorbed gas outlet chamber 115D. The condensate of the desorbed gas supplied to the desorbed gas outlet chamber 115D is directly supplied to the separator 113 through the heat exchanger condensate line 118. By not passing the condensate of the heat exchanger 115 through the condenser, the amount of cooling water used in the condenser can be reduced.

[0040] A return gas line 114 is connected to the gas phase portion of the condenser 111 and the gas phase portion of the separator 113. The return gas line 114 is introduced into the gas line 101 to be treated. The gas returned from the return gas line 114 to the gas line 101 to be treated is preferably introduced so as to form a counter flow to the flow direction of the gas I to be treated.

[0041] The treated gas line 101 is provided with a treated gas blower 102. The treated gas I sent out by the treated gas blower 102 is sent through a treated gas introduction line 103 to a first treatment tank 104A and a second treatment tank 104B.

[0042] The discharged water vapor from the steam compressor 122, i.e., the water vapor for desorption, is supplied to the first treatment tank 104A and the second treatment tank 104B through a water vapor line for desorption 108. The water vapor line for desorption 108 is connected to the first treatment tank 104A, and a first water vapor on-off valve V1 is provided in the water vapor line for desorption 108. The water vapor line for desorption 108 is connected to the second treatment tank 104B, and a second water vapor on-off valve V2 is provided in the water vapor line for desorption 108.

[0043] In the organic solvent recovery apparatus 100 having the above-mentioned configuration, the operation and opening / closing of the first automatic upper damper 106A, the second automatic upper damper 106B, the first automatic lower damper 107A, the second automatic lower damper 107B, the first water steam on-off valve V1, the second water steam on-off valve V2, the heat exchanger 115, the steam compressor 122, the condenser 111, the separator 113, and the treated gas blower 102 are appropriately controlled by a control device (not shown) so as to realize the gas treatment method described below.

[0044] (Gas treatment method) A gas treatment method using the organic solvent recovery system 1A having the above configuration will be described below. In Fig. 1, a first treatment tank 104A of an organic solvent recovery apparatus 100 is used for a desorption process, and a second treatment tank 104B is used for an adsorption process.

[0045] (Adsorption step in second treatment tank 104B) The treated gas I containing an organic solvent-containing gas is sent from the treated gas line 101 to the second treatment tank 104B, which is in an adsorption process, by the treated gas blower 102. The second automatic lower damper 107B is controlled to open the treated gas inlet line 103 and close the desorption gas line 110.

[0046] The second automatic upper damper 106B is controlled to an open state that allows the gas I to flow through the second adsorbent 105B.

[0047] The organic solvent is adsorbed in the second adsorbent 105B of the second treatment tank 104B, and the treated gas II is discharged to the outside of the system. The second water vapor on-off valve V2 of the water vapor line 108 for desorption is controlled to a closed state.

[0048] (Desorption process of first treatment tank 104A) The gas I to be treated is not sent to the first treatment tank 104A, and the first automatic lower damper 107A controls the gas to be treated introduction line 103 to be closed and the desorption gas line 110 to be open. The first automatic lower damper 107A blocks the flow of gas from the outside to the inside of the first adsorbent 105A. Water vapor for desorption is introduced through the water vapor line 108 for desorption so as to be able to flow from the inside to the outside of the first adsorbent 105A. The first water vapor on-off valve V1 of the water vapor line 108 for desorption is controlled to be open.

[0049] Steam for desorption is generated by mixing steam VIII and regenerated steam in a steam compressor 122. Steam VIII is a part of steam V. The steam compressor 122 is driven by steam VIII supplied through a steam line 121 for the steam compressor, sucks in regenerated steam in a reduced pressure state through a regenerated steam line 119, and discharges desorption steam, which is a mixture of steam VIII and regenerated steam, through a steam line 108 for desorption.

[0050] In the first treatment tank 104A, the desorption steam is ejected, and the organic solvent adsorbed to the first adsorbent 105A is desorbed from the first adsorbent 105A.

[0051] The desorption gas, which is a mixture of the desorbed organic solvent and water vapor, behaves differently in the first desorption step, which is the early stage of the desorption step, and in the second desorption step, which is the later stage. Fig. 2 is a time chart showing the time-dependent switching between the adsorption step and the desorption step in the organic solvent recovery apparatus 100 of the first embodiment shown in Fig. 1.

[0052] (First Desorption Step of First Treatment Tank 104A) In the first desorption step of the first treatment tank 104A (that is, between t0 and t1 shown in FIG. 2), the desorbed gas is supplied to the condenser 111 through the condenser line 116 by operating the three-way open / close valve V3.

[0053] In the condenser 111, heat exchange takes place between the desorbed gas and cooling water, and the desorbed gas is cooled and condensed. The condensate of the desorbed gas condensed in the condenser 111 is supplied to the separator 113 through a condenser condensate line 112. In the separator 113, the desorbed gas is separated into a layer of recovered solvent 113A and a layer of separated wastewater 113B.

[0054] (Second Desorption Step of First Treatment Tank 104A) In the second desorption step of the first treatment tank 104A (i.e., between t1 and t2 shown in FIG. 2), the desorbed gas is sent to the heat exchanger 115 through the desorbed gas line 110 by operating the three-way open / close valve V3.

[0055] The desorbed gas is supplied to the tube side of the heat exchanger 115 and exchanges heat with the make-up water VI residing on the shell side of the heat exchanger 115. Specifically, the make-up water VI is indirectly heated through the heat transfer surface.

[0056] The desorbed gas that has completed heat exchange with makeup water VI in the heat exchanger 115 is separated into uncondensed desorbed gas and condensed liquid. The uncondensed desorbed gas is supplied to the condenser 111 through a heat exchanger outlet gas line 117. Inside the condenser 111, heat exchange occurs between the desorbed gas and cooling water, and the desorbed gas is cooled and condensed. Meanwhile, the condensed liquid of the desorbed gas condensed in the heat exchanger 115 is supplied to the separator 113 through a heat exchanger condensate line 118.

[0057] The condensate of the desorbed gas condensed in the condenser 111 is supplied to the separator 113 through a condenser condensate line 112. In the separator 113, the condensate is separated into a layer of recovered solvent 113A and a layer of separated wastewater 113B.

[0058] In the first and second desorption steps, the return gas remaining in the condenser 111 and the separator 113 is pushed out by the desorbed gas, and is introduced into the treated gas line 101 through the return gas line 114, and mixed with the treated gas I. The treated gas I and the return gas introduced from the treated gas line 101 are sent to the second treatment tank 104B.

[0059] In the second desorption step, since the desorption gas is supplied to the tube side of the shell side of the heat exchanger 115, water vapor is generated by the evaporation of the makeup water VI. Meanwhile, in the first desorption step, water vapor VII, which is a part of the water vapor V, is supplied to the desorption gas inlet chamber 115C through the heat exchanger water vapor supply line 120, and water vapor is generated by the evaporation of the makeup water VI by the water vapor VII. Regenerated water vapor, which is a mixture of the water vapor generated by the evaporation of the makeup water VI and the water vapor VII, is sucked into the steam compressor 122 through the regenerated water vapor line 119. By supplying water vapor VII, the flow rate of the regenerated water vapor sucked into the steam compressor 122 is not insufficient even when the evaporation amount of the makeup water VI varies, and the desorption step of the first treatment tank 104A is efficiently performed.

[0060] Since the heat of the desorption steam supplied to the first treatment tank 104A in the first desorption step is consumed in large amounts for heating the first adsorbent 105A, the first treatment tank 104A main body, the first automatic upper damper 106A, the first automatic lower damper 107A, and each piping line, the temperature of the desorbed gas discharged from the first treatment tank 104A becomes low. Therefore, it is preferable to supply steam VII to the desorbed gas inlet chamber 115C of the heat exchanger 115 in the first desorption step and control the supply of steam VII not to the desorbed gas inlet chamber of the heat exchanger 115 in the second desorption step in which the desorbed gas discharged from the first treatment tank 104A becomes in a high-temperature state (about 70 to 120°C), because this can ensure a sufficient flow rate of the regenerated steam in the early stage of the desorption step and reduce the amount of steam VII used.

[0061] The timing of switching from the first desorption step to the second desorption step may be determined by measuring in advance the time required for the temperature of the desorbed gas discharged from the treatment tank to reach a high temperature in the first desorption step. In addition, when the time required for the temperature of the desorbed gas discharged from the treatment tank to reach a high temperature varies due to fluctuations in the outside air temperature, etc., a temperature sensor for measuring the temperature of the desorbed gas discharged from the treatment tank may be provided, and the first desorption step may be automatically switched to the second desorption step when the temperature of the desorbed gas detected by the temperature sensor reaches a high temperature.

[0062] In addition, in the first desorption step, by supplying water vapor VII to the desorption gas inlet chamber 115C, the water vapor VII condensed in the heat exchanger becomes water and flows through the tube 115B of the heat exchanger 115. By washing away / diluting the decomposition products of corrosive organic solvents contained in the condensed water of the desorption gas, the corrosiveness of the condensed water can be reduced, and the life of the heat exchanger 115 can be extended.

[0063] After a certain time has passed, the adsorption process and the desorption process are switched over, with the first treatment tank 104A performing the adsorption process and the second treatment tank 104B performing the desorption process. In this way, the organic solvent recovery apparatus 100 continuously recovers the recovered solvent 113A by a continuous process in which the adsorption process and the desorption process are alternately performed.

[0064] [Embodiment 2] An organic solvent recovery system according to the second embodiment will be described with reference to Fig. 3. Fig. 3 is a diagram showing the configuration of an organic solvent recovery system 1B according to the second embodiment.

[0065] The basic configuration of the organic solvent recovery system 1B of the embodiment 2 is the same as that of the organic solvent recovery system 1A described above in the embodiment 1. The difference is that the organic solvent recovery system 1B of the embodiment 2 is provided with a temperature sensor 115H, which is a temperature measurement unit that measures the temperature of the makeup water VI in the heat exchanger 115, in the makeup water storage unit 115E.

[0066] Specifically, the control unit 115G adjusts the opening of the adjustment valve V4 to supply steam VII so that the temperature of the make-up water VI in the make-up water storage unit 115E detected by the temperature sensor 115H is maintained within a predetermined range (approximately 70°C to 97°C).

[0067] The organic solvent recovery system 1B according to the second embodiment can also provide the same advantageous effects as those of the organic solvent recovery system 1A according to the first embodiment.

[0068] The above-disclosed embodiments should be considered as illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0069] In the organic solvent recovery apparatus 100 disclosed above, the first treatment tank 104A and the second treatment tank 104B are used as treatment tanks to alternately perform an adsorption process and a desorption process. However, the organic solvent recovery process is not limited to using these two treatment tanks, and the number of treatment tanks may be three or more. [Industrial Applicability]

[0070] The present invention makes it possible to provide an organic solvent recovery system that is energy-saving and improves the efficiency of recovering organic solvents while reducing corrosion of the mechanism that generates water vapor, thereby making a great contribution to the industrial world. [Explanation of symbols]

[0071] 1A, 1B Organic solvent recovery system, 100 Organic solvent recovery device, 101 Treated gas line, 102 Treated gas blower, 103 Treated gas introduction line, 104A First treatment tank, 104B Second treatment tank, 105A First adsorbent, 105B Second adsorbent, 106A First automatic upper damper, 106B Second automatic upper damper, 107A First automatic lower damper, 107B Second automatic lower damper, 108 Desorption water vapor line, 110 Desorption gas line, 111 Condenser (cooling section), 112 Condenser condensate line, 113 Separator (condensate reservoir section), 113A Recovered solvent, 113B Separation wastewater, 114 Return gas line, 115 Heat exchanger, 115A Shell (heat absorption section, container section), 115B Tube (heat generating section, pipe section), 115C desorption gas inlet chamber, 115D desorption gas outlet chamber (desorption gas outlet receiving section), 115E makeup water storage section, 115F pressure sensor (pressure measuring section), 115G control section, 115H temperature sensor (temperature measuring section), 116 condenser line, 117 heat exchanger outlet gas line, 118 heat exchanger condensate line, 119 regenerated steam line, 120 heat exchanger steam supply line (steam supply section), 121 steam line for steam compressor, 122 steam compressor, V1 first steam on-off valve, V2 second steam on-off valve, V3 on-off valve, V4 adjustment valve, I gas to be treated, II treated gas, III recovered solvent, IV separated wastewater, V, VII, VIII steam, VI makeup water

Claims

1. an organic solvent recovery apparatus including a treatment tank containing an adsorbent that adsorbs and removes an organic solvent from a gas to be treated that contains the organic solvent, and repeats an adsorption process in which the gas to be treated that is supplied to the treatment tank is brought into contact with the adsorbent to discharge a treated gas, and a desorption process in which the organic solvent is desorbed from the adsorbent by a desorption steam supplied to the treatment tank and a desorbed gas is discharged; a heat exchanger including a heat generating section through which the desorption gas discharged from the organic solvent recovery apparatus passes and a heat absorbing section to which makeup water is supplied, the heat exchanger indirectly heating the makeup water in the heat absorbing section with the desorption gas passing through the heat generating section to generate steam, and discharging the indirectly heated desorption gas; a cooling unit that cools the desorption gas discharged from the heat exchanger and discharges a condensate, a water vapor supply unit that supplies water vapor to the heat generating portion of the heat exchanger and indirectly heats the makeup water with the water vapor to generate water vapor; the heat exchanger supplies the water vapor generated from the make-up water to the organic solvent recovery device as at least a part of the water vapor for desorption.

2. 2. The organic solvent recovery system according to claim 1, further comprising a pressure measuring unit for measuring a pressure of a gas phase portion of the heat absorbing unit of the heat exchanger, and controlling a flow rate of the water vapor supplied to the heat generating unit based on a measurement result of the pressure measuring unit.

3. 2. The organic solvent recovery system according to claim 1, further comprising a temperature measuring unit for measuring a temperature of a liquid phase portion of the heat absorption unit of the heat exchanger, and controlling a flow rate of the water vapor supplied to the heat generation unit based on a measurement result of the temperature measuring unit.

4. a path for supplying the desorption gas discharged from the treatment tank to the heat exchanger; a passage for supplying the desorption gas discharged from the treatment tank to the cooling section, In the early stage of the desorption treatment, water vapor is supplied to the heat generating section of the heat exchanger, and the desorbed gas discharged from the treatment tank is supplied to the cooling section; 4. The organic solvent recovery apparatus according to claim 1, wherein, in a later stage of the adsorption treatment, the desorption gas is supplied to the heat generating section of the heat exchanger, and the desorption gas after passing through the heat generating section is supplied to the cooling section.

5. the organic solvent recovery apparatus includes a condensate reservoir that accumulates the condensate discharged from the cooling unit, 4. The organic solvent recovery system according to claim 1, wherein the heat exchanger comprises: a desorbed gas outlet receiving portion in which the desorbed gas after indirect heating accumulates; a piping path for supplying the uncondensed desorbed gas from the desorbed gas outlet receiving portion to the cooling portion; and a piping path for supplying the desorbed gas that has become a condensed liquid from the desorbed gas outlet receiving portion to the condensed liquid reservoir portion.

6. 4. The organic solvent recovery system according to claim 1, wherein the heat exchanger is a multi-tube heat exchanger having a tube portion as the heat generating portion inside a container portion as the heat absorbing portion.

7. 4. The organic solvent recovery system according to claim 1, wherein the water vapor supply unit is connected to or shared with a desorption water vapor supply unit that directly supplies the desorption water vapor to the organic solvent recovery apparatus.

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