JP6946730B2 - Organic solvent recovery system - Google Patents

Description

The present invention purifies and discharges the gas to be treated by separating the organic solvent from the gas to be treated containing an organic solvent (organic substance), and recovers the organic solvent separated from the gas to be treated by using a carrier gas. Regarding the organic solvent recovery system.

In recent years, with the tightening of emission concentration regulations for harmful air pollutants, the demand for organic solvent-containing gas treatment systems has increased. Among them, the organic solvent recovery system that liquefies and recovers the organic solvent has advantages that the amount of carbon dioxide emitted is smaller than that of the combustion device that burns and detoxifies the organic solvent, and that the recovered organic solvent can be reused.

This type of organic solvent recovery system is generally discharged from an adsorption / desorption treatment device for contacting a gas to be treated and a carrier gas in a high temperature state with an adsorbent alternately in time and the suction / desorption treatment device. It is equipped with a condensation recovery device that condenses and recovers the organic solvent by cooling the carrier gas in a high temperature state.

As one of such systems, Patent Document 1 discloses an organic solvent-containing gas treatment system using water vapor as a carrier gas. Recently, there has been a demand for an organic solvent recovery system with a low amount of wastewater for the purpose of improving the quality of the recovered organic solvent and simplifying the wastewater treatment process. Therefore, Patent Document 2 discloses an organic solvent-containing gas treatment system using an inert gas heated to a high temperature as a carrier gas. Further, Patent Document 3 has a configuration in which an inert gas heated to a high temperature is used as a carrier gas, and the inert gas is circulated and used in the organic solvent recovery system to reduce the amount of the inert gas used. It is disclosed.

By the way, it is difficult to completely separate the organic solvent from the carrier gas only by the operation of cooling and condensing, and the carrier gas discharged from the condensing recovery device contains a certain amount of the unconcentrated organic solvent. Therefore, if a carrier gas containing an unconcentrated organic solvent is circulated as it is and an attempt is made to desorb the organic solvent from the adsorbent, the regeneration of the adsorbent becomes insufficient and the purification ability for the gas to be treated is significantly reduced. ..

Therefore, the system disclosed in Patent Document 3 has a first adsorption / desorption processing device having a first adsorption / desorption element, a condensation recovery device, and a second adsorption / desorption device on a circulation path through which the carrier gas circulates. A second suction / desorption processing device having an element is provided. The suction / desorption treatment device includes a first temperature control means for adjusting the temperature of the carrier gas discharged from the second suction / desorption treatment device to a high temperature state, and the second suction / desorption treatment device is discharged from the condensation recovery device. A second temperature adjusting means for alternately adjusting the temperature of the carrier gas to either a high temperature state or a low temperature state is provided. With such a system, in Patent Document 3, the purification ability for the gas to be treated and the recovery efficiency of the organic solvent are improved. Further, even when an inert gas such as nitrogen gas is used as the carrier gas, an energy saving effect capable of significantly suppressing the amount of the inert gas used is also obtained.

Further, Patent Document 4 discloses a system in which outside air is introduced into the first suction / desorption tank immediately after the desorption stroke to cool the first suction / desorption element, and the organic solvent at the initial stage of the adsorption stroke is efficiently adsorbed.

Jikkenhei No. 3-32924 Japanese Unexamined Patent Publication No. 7-68127 Japanese Patent No. 5482776 Japanese Unexamined Patent Publication No. 2014-117638

However, in the system disclosed in Patent Document 3, when the gas to be treated is introduced into the first suction / desorption element immediately after the desorption stroke, the first suction / desorption element is cooled by the temperature of the gas to be treated, but the initial temperature remains high. Is. In the conventional method of desorbing an organic solvent with water vapor, condensed water adheres to the first adsorption / desorption element immediately after the desorption process. However, in the method of desorption using a carrier gas such as an inert gas, the amount of water is small, and the first adsorption / desorption element is not sufficiently cooled. For this reason, the organic solvent is less likely to be adsorbed at the initial stage of the adsorption process in which the organic solvent of the gas to be treated is adsorbed, and the purification capacity is lowered.

Further, in the system disclosed in Patent Document 4, a huge amount of energy is required to completely desorb the organic solvent from the first adsorption / desorption element in the desorption stroke, and practically, a certain amount of the organic solvent is used as the first. The organic solvent is repeatedly adsorbed and desorbed while remaining in the adsorption / desorption element. Therefore, the gas discharged by cooling the first adsorption / desorption element with the outside air contains a large amount of the organic solvent desorbed from the first adsorption / desorption element, and is discharged to the outside of the system as it is, resulting in the result. Requires a treatment device that reduces the purification capacity and recovery rate of the organic solvent with respect to the gas to be treated, or separately removes the organic solvent from the gas discharged to the outside of the system.

Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an organic solvent recovery system in which the purification ability for the gas to be treated and the recovery rate of the organic solvent are improved.

As a result of diligent studies to solve the above problems, the present inventors have finally completed the present invention. That is, the present invention is as follows.

1. 1. By separating the organic solvent from the gas to be treated containing the organic solvent introduced from the introduction route, the gas to be treated is cleaned and discharged, and the organic solvent separated from the gas to be treated is recovered by using the carrier gas. An organic solvent recovery system, a first suction / desorption treatment device having a first suction / desorption element for sucking / desorbing an organic solvent in a carrier gas circulation path, and a condensation recovery device that condenses the organic solvent and recovers it as a condensate. A first temperature adjusting means for adjusting the temperature of the carrier gas to be introduced into the first adsorption / desorption processing apparatus to a high temperature, comprising a second adsorption / desorption processing apparatus having a second adsorption / desorption element for adsorbing / desorbing an organic solvent. A second temperature adjusting means for adjusting the temperature of the carrier gas to be introduced into the second adsorption / desorption treatment apparatus to a low temperature or a high temperature, and a part of the gas to be processed passing through the introduction path for cooling the first adsorption / desorption element. comprising a cooling path for introducing into the first desorption apparatus, and a return for the path in which the returning the treated gas used in cooling the introduction path is discharged from the first desorption processing device, In the first adsorption / desorption treatment apparatus, the gas to be treated from the introduction path, the carrier gas heated to a high temperature by the first temperature adjusting means, and the gas to be treated from the cooling path are sequentially arranged in the first state. By repeating contacting with the adsorption / desorption element, the organic solvent is moved from the gas to be treated to the carrier gas heated to a high temperature, and the first adsorption / desorption element after contacting with the carrier gas heated to a high temperature is described. After cooling with the gas to be treated introduced from the cooling path, the gas to be treated introduced from the introduction path is brought into contact again, and the condensation recovery device uses the carrier gas discharged from the first suction / desorption treatment device. The organic solvent contained in the carrier gas is condensed by adjusting the temperature to a low temperature state, and the second adsorption / desorption treatment device heats the carrier gas discharged from the condensation recovery device to a high temperature or a low temperature by the second temperature control means. An organic solvent recovery system characterized in that an organic solvent is moved from a low-temperature carrier gas to a high-temperature carrier gas by alternately contacting the second adsorption / desorption element by adjusting the temperature.
2. The above 1 is characterized in that, in the flow path of the gas to be treated, a confluence point of the introduction path and the return path is provided downstream of the branch point of the introduction path and the cooling path. The organic solvent recovery system described in.
3. 3. The cooling path is configured to be the same as the introduction path, and a third suction / desorption element that adsorbs and desorbs an organic solvent between the confluence point of the introduction path and the return path and the first suction / desorption treatment device. The organic solvent recovery system according to 1 above, which comprises a third adsorption / desorption treatment apparatus having the above 1.
4. The organic solvent recovery system according to any one of 1 to 3 above, wherein the second adsorption element has a larger adsorption capacity than the first adsorption element.
5. The organic solvent recovery system according to 4 above, wherein the BET specific surface area of the second adsorption / desorption element is larger than the BET specific surface area of the first adsorption / desorption element.
6. The organic solvent recovery system according to any one of 1 to 5 above, wherein the carrier gas is an inert gas.
7. The organic solvent recovery system according to any one of 1 to 6 above, wherein the first adsorption / desorption element is made of activated carbon fiber.
8. The organic solvent recovery system according to any one of 1 to 7 above, wherein the second adsorption / desorption element is made of activated carbon fiber.

Further, the control method and control program for controlling the organic solvent recovery system according to any one of 1 to 8 above are also included in the category of the present invention.

According to the present invention having the above configuration, it is possible to provide an organic solvent recovery system in which the purification capacity for the gas to be treated and the recovery rate of the organic solvent are improved.

It is a system block diagram of the organic solvent recovery system in Embodiment 1 of this invention. It is a system block diagram of the organic solvent recovery system in Embodiment 2 of this invention. It is a time chart of the organic solvent recovery system in the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are designated by the same reference numerals in the drawings, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a conceptual diagram of the organic solvent recovery system 100A according to the first embodiment of the present invention. First, the configuration of the organic solvent recovery system 100A will be described with reference to FIG.

The organic solvent recovery system 100A purifies and discharges the gas to be treated by separating the organic solvent from the gas to be treated containing the organic solvent, and recovers the organic solvent separated from the gas to be treated by using a carrier gas. It is a system. As shown in FIG. 1, the organic solvent recovery system 100A has a circulation path L1 composed of piping lines L4 to L7 arranged so as to circulate carrier gas, and a first suction / desorption system provided on the circulation path L1. It mainly includes a processing device 10, a condensation recovery device 20, and a second adsorption / desorption processing device 30. It also includes a circulation blower 40. A gas to be treated containing an organic solvent is introduced into the organic solvent recovery system 100A from the piping line L1.

Examples of the organic solvent recovered by the organic solvent recovery system 100A include methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, trichloroethylene, tetrachloroethylene, O-dichlorobenzene, m-dichlorobenzene, Freon-112, Freon-113, HCFC, and 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, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, holon, acrylonitrile, n-hexane, isohexane, cyclohexane, methylcyclohexane, n-heptane, n-octane, n-nonane , Isononane, decane, dodecane, undecane, tetradecane, decalin, benzene, toluene, m-xylene, p-xylene, o-xylene, ethylbenzene, 1,3,5-trimethylbenzene, N-methylpyrrolidone, dimethylformamide, dimethylacetamide And dimethyl sulfoxide and the like, but are not limited thereto. In addition, a plurality of types of organic solvents may be recovered.

In the organic solvent recovery system 100A, various types of gases such as steam, heated air, and an inert gas heated to a high temperature can be used as the carrier gas. In particular, if an inert gas, which is a gas that does not contain water, is used, the organic solvent recovery system 100A can be configured more simply and safely. The circulation blower 40 is a blowing means for passing the carrier gas through the circulation path L1. The flow velocity of the carrier gas is appropriately set by the circulation blower 40. A plurality of circulation blowers may be provided in the circulation path L1.

The circulation path L1 is connected to an introduction line L9 that introduces the carrier gas from outside the circulation path L1. The introduction line L9 is used to introduce the carrier gas into the circulation path L1 at the time of initial installation of the organic solvent recovery system 100A, and to replenish the carrier gas to the circulation path L1 as needed at the time of maintenance or the like.

The first suction / desorption processing device 10 includes a first suction / desorption tank A11, a first suction / desorption tank B12, and a first suction / desorption element desorption heater 13. The first suction / desorption element desorption heater 13 may be provided outside the first suction / desorption processing device 10.

The first suction / desorption tank A11 includes a first suction / desorption element A14, and the first suction / desorption tank B12 includes a first suction / desorption element B15. The first suction / desorption element A14 and the first suction / desorption element B15 adsorb the organic solvent contained in the gas to be treated by bringing the gas to be treated introduced from the piping line L2 into contact with the gas to be treated. Therefore, in the first adsorption / desorption treatment apparatus 10, the organic solvent in the gas to be treated is released by supplying (introducing) the gas to be treated to either the first suction / desorption tank A11 or the first suction / desorption tank B12. 1 The suction / desorption element A14 or the first suction / desorption element B15 is adsorbed and removed, and the clean gas is discharged from the first suction / desorption tank A11 and the first suction / desorption tank B12 to the outside through the piping line L3.

The first adsorption / desorption element A14 or the first adsorption / desorption element B15 desorbs the adsorbed organic solvent by bringing the carrier gas in a high temperature state into contact with the first adsorption / desorption element attachment / detachment heater 13, which will be described later. Therefore, in the first adsorption / desorption treatment apparatus 10, the organic solvent is released to the first adsorption / desorption element A14 or the first adsorption / desorption element A14 or the first by supplying the carrier gas in a high temperature state to the first adsorption / desorption tank A11 or the first adsorption / desorption tank B12. It is desorbed from the suction / desorption tank B12, moves to the carrier gas, and is discharged from the first suction / desorption tank A11 and the first suction / desorption tank B12 via the piping line L5.

The first adsorption / desorption element A14 and the first adsorption / desorption element B15 are composed of an adsorbent containing any one of granular activated carbon, activated carbon fiber, zeolite, silica gel, activated alumina and a porous organic compound. It is preferably an adsorbent composed of activated carbon fibers. Activated carbon fiber has a very large outer surface area due to its fiber structure, and since micropores are directly opened on the fiber surface, it has high contact efficiency with gas and can exhibit higher adsorption / desorption efficiency than other adsorbents. ..

The first suction / desorption processing device 10 is connected to the piping lines L2 and L3, respectively. The piping line L2 is a piping line for introducing the gas to be treated containing an organic solvent into the first suction / desorption tank A11 and the first suction / desorption tank B12 via the blower 60, and the first suction / desorption tank is provided by a valve. The connected state and the non-connected state with respect to A11 and the first suction / detachment tank B12 are switched. The piping line L3 is a piping line for discharging clean gas from the first suction / desorption tank A11 and the first suction / desorption tank B12, and is connected to the first suction / desorption tank A11 and the first suction / desorption tank B12 by a valve. It can be switched from the disconnected state.

Further, the first suction / desorption processing device 10 is connected to the piping lines L4 and L5, respectively. The piping line L4 is a piping line for supplying the carrier gas to the first suction / desorption tank A11 and the first suction / desorption tank B12 via the first suction / desorption element desorption heater 13, and the first suction / desorption by a valve. The connected state and the non-connected state with respect to the tank A11 and the first suction / detachment tank B12 are switched. The piping line L5 is a piping line for discharging the carrier gas from the first suction / desorption tank A11 and the first suction / desorption tank B12, and is connected to the first suction / desorption tank A11 and the first suction / desorption tank B12 by a valve. It can be switched from the disconnected state. In the present embodiment, "discharge from the first suction / desorption tank A11" and "discharge from the first suction / desorption element A14" are used interchangeably. Similarly, "discharge from the first suction / desorption tank B12" and "discharge from the first suction / desorption element B15" are used interchangeably.

Further, the first suction / desorption processing device 10 is connected to the piping lines L11 and L12, respectively. The piping line L11 is a piping line for supplying a part of the gas to be processed passing through the piping line L2 to the first suction / desorption tank A11 and the first suction / desorption tank B12 by the cooling blower 70, and is the first suction line by the valve. The connected state and the non-connected state to the desorption tank A11 and the first suction / desorption tank B12 are switched. The piping line L12 is a piping line for merging a part of the gas to be processed discharged from the first suction / desorption tank A11 and the first suction / desorption tank B12 into the piping line L2, and the first suction / desorption tank A11 by a valve. The connection state and the non-connection state with respect to the first suction / detachment tank B12 are switched.

In each of the first suction / desorption tank A11 and the first suction / desorption tank B12, the gas to be processed from the piping line L2 and the first suction / desorption element desorption heater 13 are used by operating the opening and closing of the valve described above. The carrier gas whose temperature is controlled and is in a high temperature state and the gas to be processed from the piping line L11 are alternately supplied in time. As a result, the first suction / desorption tank A11 and the first suction / desorption tank B12 function as an adsorption tank, a desorption tank, and a cooling tank alternately in time. Accordingly, the organic solvent moves from the gas to be treated to the carrier gas. Specifically, when the first suction / desorption tank A11 functions as an adsorption tank, the first suction / desorption tank B12 functions as a desorption tank or a cooling tank, and the first suction / desorption tank A11 is a desorption tank. Alternatively, when functioning as a cooling tank, the first suction / desorption tank B12 functions as an adsorption tank.

Here, the piping line L2 is connected to a processing tank functioning as an adsorption tank among the first suction / desorption tank A11 or the first suction / desorption tank B12, and supplies the gas to be processed to the processing tank. Further, the piping line L3 is connected to a treatment tank functioning as an adsorption tank among the first suction / desorption tank A11 or the first suction / desorption tank B12, and discharges clean gas from the treatment tank. Further, the piping line L4 is connected to a processing tank functioning as a desorption tank among the first suction / desorption tank A11 or the first suction / desorption tank B12, and supplies carrier gas to the processing tank. The piping line L5 is connected to a treatment tank functioning as a desorption tank among the first suction / desorption tank A11 or the first suction / desorption tank B12, and discharges carrier gas from the treatment tank. Further, the piping line L11 is connected to a processing tank functioning as a cooling tank of the first suction / desorption tank A11 or the first suction / desorption tank B12, and supplies a part of the gas to be processed to the processing tank. .. The piping line L12 is connected to a processing tank functioning as a cooling tank in the first suction / desorption tank A11 or the first suction / desorption tank B12, and discharges a part of the gas to be processed from the processing tank.

The condensation recovery device 20 includes a condenser 21 and a recovery tank 22. The condenser 21 is a device that cools and condenses the organic solvent contained in the carrier gas by adjusting the temperature of the carrier gas to a low temperature state. The recovery tank 22 is a container for storing the organic solvent liquefied by the condenser 21 as a condensate. The carrier gas remaining without being aggregated in the condensing recovery device 20 is discharged from the piping line L6.

The condenser 21 is kept at a constant low temperature set temperature, and the carrier gas discharged from the condenser 21 contains an organic solvent having a saturated vapor concentration at the set temperature. That is, in the condensation recovery device 20, the difference between the concentration of the organic solvent in the carrier gas supplied to the condenser 21 and the concentration of the organic solvent in the carrier gas discharged from the condenser 21 is recovered.

The condensation recovery device 20 is connected to the piping lines L5 and L6. The piping line L6 is a piping line that supplies the carrier gas discharged from the condensation recovery device 20 to the second suction / desorption processing device 30. Further, the condensation recovery device 20 is connected to a discharge line L9 for discharging the condensed liquid of the organic solvent stored in the recovery tank 22 to the outside.

The second adsorption / desorption processing apparatus 30 includes a second adsorption / desorption tank 31 having a second adsorption / desorption element 32 and a second temperature controller 50, adsorbs the organic solvent contained in the carrier gas, and adsorbs the adsorbed organic solvent. It is a device that desorbs with a high-temperature carrier gas. The second temperature controller 50 is a device that regulates the temperature of the carrier gas discharged from the condensation recovery device 20 to a high temperature or low temperature state and supplies it to the second adsorption / desorption tank 31. The second temperature controller 50 may be provided outside the second suction / desorption processing device 30. In the present embodiment, "discharge from the second suction / desorption tank 31", "discharge from the second suction / desorption element 32", and "discharge from the second suction / desorption processing device 30" are used interchangeably.

The second adsorption / desorption processing device 30 cools the carrier gas discharged from the condensation recovery device 20 to a low temperature by the second temperature controller 50 and introduces it into the second adsorption / desorption tank 31, and turns the carrier gas into the second adsorption / desorption element 32. The contained organic solvent is adsorbed, and the carrier gas having a reduced concentration of the organic solvent is discharged from the second adsorption / desorption tank 31. Further, the carrier gas heated to a high temperature by the second temperature controller 50 is introduced into the second adsorption / desorption tank 31, the organic solvent is desorbed from the second adsorption / desorption element 32, and the carrier gas containing the organic solvent is desorbed from the second adsorption / desorption. Discharge from the tank 21.

The second adsorption / desorption element 32 is composed of an adsorbent containing any one of granular activated carbon, activated carbon fiber, zeolite, silica gel, activated alumina and a porous organic compound. It is preferably an adsorbent composed of activated carbon fibers. Activated carbon fiber has a very large outer surface area due to its fiber structure, and since micropores are directly opened on the fiber surface, it has high contact efficiency with gas and exhibits higher adsorption / desorption efficiency than other adsorbents. ..

Piping lines L6 and L7 are connected to the second suction / desorption processing device 30, respectively. The piping line L6 is a piping line for supplying the carrier gas discharged from the condensing recovery device 20 to the second suction / desorption tank 31 in either a high temperature or a low temperature state via the second temperature controller 50. The piping line L7 is a piping line for discharging the carrier gas from the second suction / desorption tank. The second temperature controller 50 has a path (high temperature path) for supplying the carrier gas discharged from the condensation recovery device 20 to the second suction / desorption tank 31 in a high temperature state via the second suction / desorption element desorption heater 33. It has a path (direct path) for directly supplying the second suction / detachment element to the second suction / detachment tank 31 in a low temperature state without passing through the second suction / detachment element attachment / detachment heater 33. Which of these paths the carrier gas passes through is switched by the valve.

The carrier gas discharged from the second suction / desorption processing device 30 is supplied to the circulation blower 40. The circulation blower 40 is a device for circulating and passing the carrier gas on the circulation system path L1. The carrier gas discharged from the circulation blower 40 is supplied to the first suction / desorption processing device 10 via the first suction / desorption element desorption heater 13.

The first suction / desorption element desorption heater 13 is a device that adjusts the temperature of the carrier gas supplied to the first suction / desorption processing device 10 to a high temperature state. The first suction / detachment element desorption heater 13 is a carrier gas supplied to the first suction / desorption tank A11 and the first suction / desorption tank B12 so that the first suction / desorption elements A14 and B15 are maintained at a predetermined desorption temperature. To heat. The first suction / detachment element desorption heater 13 may be built in the first suction / desorption tank A11 and the first suction / desorption tank B12.

FIG. 3 is a time chart showing the temporal switching of the adsorption stroke and the desorption step in the pair of first adsorption / desorption elements A14, B15 and the second adsorption / desorption element 32 of the organic solvent recovery system 100A shown in FIG. In FIG. 3, t0 to t6 indicate the time, and the time elapses toward the right. Hereinafter, the details of the treatment of the gas to be treated in the organic solvent recovery system 100A of the present embodiment will be described with reference to FIGS. 1 and 3.

The organic solvent recovery system 100A shown in FIG. 1 is an organic solvent to be treated by repeatedly carrying out the one cycle shown in FIG. 3 (between times t0 to t6 shown in FIG. 3) as a unit period. The solvent-containing gas is continuously treated.

In the first half of the above one cycle (between times t0 to t3 shown in FIG. 3), in the first adsorption / desorption processing apparatus 10, the first adsorption / desorption tank A11 was subjected to the adsorption treatment by the first adsorption element A14. At the same time, the first suction / desorption tank B12 carries out a desorption treatment by the first suction / desorption element B15 and a subsequent cooling treatment.

In the first stage of the desorption process by the first desorption element B15 (between times t0 to t1 shown in FIG. 3), the second desorption processing device 30 carries out the desorption process by the second desorption element 32. Further, in the latter stage of the desorption treatment by the first suction / desorption element B15 (between times t1 to t2 shown in FIG. 3), the second suction / desorption processing device 30 carries out the adsorption treatment by the second suction / desorption element 32.

Further, in the cooling process (between times t2 to t3 shown in FIG. 3) after the desorption process by the first suction / desorption element B15 is completed, a part of the gas to be processed is passed through the cooling blower 70 to the piping line L11. It is supplied to the first suction / desorption tank B12 through the structure and cools the first suction / desorption element B15. On the other hand, a part of the gas to be treated discharged from the first suction / desorption tank B12 joins the gas to be treated in the piping line 1 through the piping line L12.

Further, in the latter half of the above one cycle (between times t3 and t6 shown in FIG. 3), in the first adsorption / desorption processing apparatus 10, the first adsorption / desorption tank B12 is subjected to the adsorption treatment by the first adsorption / desorption element B15. In parallel with this, the first suction / desorption tank A11 carries out a desorption treatment by the first suction / desorption element A14 and a subsequent cooling treatment. As shown in FIG. 3, the operation of the second adsorption / desorption processing device 30 in the latter half of the first cycle is the same as that in the first half of the first cycle.

Next, the recovery of the organic solvent, the flow of the carrier gas, and the cooling treatment in the organic solvent recovery system 100A according to the embodiment of the present invention will be described in detail with reference to FIG. The following description is based on a state in which the first suction / desorption tank A11 of the first suction / desorption processing device 10 functions as a suction tank and the first suction / desorption tank B12 functions as a desorption tank. The same applies when the desorption tank and the desorption tank are replaced.

In the organic solvent recovery system 100A, in the first stage of the desorption treatment period by the first adsorption / desorption element B15 (that is, between t0 to t1 shown in FIG. 3), the uncondensed organic solvent discharged from the condensation recovery device 20 is collected. The low-temperature carrier gas contained is adjusted to a high temperature by the second temperature controller 50, supplied to the second adsorption / desorption tank 31 of the second adsorption / desorption processing device 30, and comes into contact with the second adsorption / desorption element 32.

As a result, the organic solvent adsorbed on the second adsorption / desorption element 32 is desorbed from the second adsorption / desorption element 32 by the carrier gas in a high temperature state, discharged from the second adsorption / desorption tank 31, and the concentration of the organic solvent in the carrier gas. Is supplied to the circulation blower 40 in an increased state. The temperature of this carrier gas is adjusted to a high temperature by the heater 13 for the first adsorption / desorption processing device, and is supplied to the first adsorption / desorption element B15 of the first adsorption / desorption processing device 10. As a result, the organic solvent adsorbed on the first adsorption / desorption element B15 is desorbed, and the organic solvent is introduced into the condensation recovery device 20 in a state where the concentration of the organic solvent in the carrier gas is further increased.

The increased concentration of the organic solvent in the carrier gas is recovered by the condenser 21 of the condensation recovery device 20, and the unrecovered organic solvent is contained in the carrier gas discharged from the condenser 21 and supplied to the second adsorption / desorption treatment device 30. NS.

Next, in the latter stage of the desorption treatment period by the first adsorption / desorption element B15 (that is, between t1 to t2 shown in FIG. 3), a low temperature state containing an uncondensed organic solvent discharged from the condensation recovery device 20. The carrier gas in the above is adjusted to a high temperature state by the second temperature controller 50, is supplied to the second suction / desorption tank 31 of the second suction / desorption processing device 30, and comes into contact with the second suction / desorption element 32.

As a result, the organic solvent contained in the carrier gas is adsorbed and removed by the second adsorption / desorption element 32, and the concentration of the organic solvent in the carrier gas discharged from the second adsorption / desorption tank 31 is gradually reduced. NS. Along with this, the concentration of the organic solvent contained in the carrier gas supplied to the first adsorption / desorption element B15 of the first adsorption / desorption treatment device 10 is gradually reduced, and the desorption treatment of the first adsorption / desorption element B15 is further performed. It will be promoted.

Next, in the cooling process (between t2 and t3 shown in FIG. 3) after the desorption process of the first adsorption / desorption element B15 is completed, a part of the gas to be processed passes through the piping line L11 and is first adsorbed / desorbed. It is supplied to the tank B12 and comes into contact with the first suction / desorption element B15 to cool the first suction / desorption element B15. As a result, in the subsequent early stage of the adsorption treatment of the first adsorption / desorption element B15 (between t3 and t4 shown in FIG. 3), the organic solvent in the gas to be treated is efficiently adsorbed and removed by the first adsorption / desorption element B15. Therefore, the purification capacity for the gas to be treated is improved.

Further, in the cooling treatment of the first adsorption / desorption element B15, the concentration of the organic solvent of the gas to be treated used for cooling discharged from the first adsorption / desorption tank B12 is such that the organic solvent desorbed from the first adsorption / desorption element B15 is used. It is expensive because it contains a lot. That is, the concentration of the organic solvent is higher than that of the gas to be treated for cooling through the pipe line L11. The gas to be treated for cooling is discharged from the first suction / desorption tank B12 through the pipe line L12. However, the gas to be treated used for cooling through the pipe line L12 merges with the gas to be treated in the pipe line L2, and after the concentration of the organic solvent in the gas to be treated becomes high, the adsorption treatment is carried out. 1 The organic solvent supplied to the adsorption / desorption tank A11 and in the gas to be treated is adsorbed and removed by the first adsorption / desorption element A14. Therefore, it is not discharged to the outside of the system, and as a result, the recovery rate for the gas to be treated is improved.

From the above, it is not necessary to separately install an organic solvent treatment device for removing the organic solvent from the gas to be treated used for cooling discharged from the first suction / desorption tank B12. Therefore, without increasing the size of the system

Further, on the piping line L2, the branch point between the piping line L2 and the piping line L11 is preferably installed on the upstream side of the confluence point between the piping line L2 and the piping line L12. The reason is as follows, but it is not necessary to limit it to the upstream side. When the branch point between the piping line L2 and the piping line L11 is installed on the downstream side of the confluence of the piping line L2 and the piping line L12, the concentration of the organic solvent is high in the cooling process of the first adsorption / desorption element B15. The gas to be treated is supplied to the first adsorption / desorption tank B12 and comes into contact with the first adsorption / desorption element B15, so that the adsorption of the organic solvent on the first adsorption / desorption element B15 is promoted, followed by the first adsorption / desorption element B15. In the adsorption treatment (that is, between t3 and t6 shown in FIG. 3), the adsorption capacity of the first adsorption / desorption element B15 may decrease, and the purification capacity and recovery rate for the gas to be treated may decrease.

If the adsorption capacity of the second adsorption / desorption element 32 is set higher than the adsorption capacity of the first adsorption / desorption element A14 and the first adsorption / desorption element B15, the purification capacity for the gas to be treated and the recovery rate of the organic solvent can be improved. It is realized stably. This is because the concentration of the organic solvent in the carrier gas supplied to the second adsorption / desorption element 32 is supplied to the first adsorption / desorption element A14 in the latter stage of the desorption treatment of the first adsorption / desorption element B15 described above. This is because it is higher than the concentration of the organic solvent in the processing gas. Here, as a method of setting the suction capacity of the second suction / desorption element 32 to be higher than that of the first suction / desorption element A14 and the first suction / desorption element B15, for example, the BET specific surface area of the second suction / desorption element 32 is set to the first suction. It is effective to make it larger than the desorption element A14 and the first desorption element B15.

(Embodiment 2)
FIG. 2 is a block diagram of the organic solvent recovery system 100B according to the second embodiment of the present invention. The organic solvent recovery system 100B basically has the same configuration as the organic solvent recovery system 100A. However, in the organic solvent recovery system 100A, the gas to be treated for cooling was supplied to the first suction / desorption tank A11 and the first suction / desorption tank B12 through the piping line L11, whereas in the organic solvent recovery system 100B. The piping line L11 is not provided. Instead, in the organic solvent recovery system 100B, in the cooling process of the first adsorption / desorption element A14 and the first adsorption / desorption element B15, the piping line L2 and the first adsorption / desorption tank A11 and the piping line L2 and the first adsorption / desorption tank B12 By opening both valves connecting the above, the gas to be processed is brought into contact with the first suction / desorption element A14 and the first suction / desorption element B15 at the same time. Further, the organic solvent recovery system 100B has a third adsorption / desorption processing device 80 between the confluence point of the piping line L2 and the piping line L12 and the first adsorption / desorption processing device 10. In the present embodiment, the third suction / desorption treatment device 80 is provided upstream of the gas blower device 60 to be treated.

The third adsorption / desorption treatment device 80 includes a third adsorption / desorption element 81 that absorbs / desorbs the organic solvent in the gas to be treated. The third adsorption / desorption element 81 is composed of an adsorbent containing any one of granular activated carbon, activated carbon fiber, zeolite, silica gel, activated alumina and a porous organic compound, but is not particularly limited.

In the organic solvent recovery system 100B, in the cooling treatment of the first adsorption / desorption element A14 and the first adsorption / desorption element B15, the concentration of the organic solvent discharged from the first adsorption / desorption tank A11 and the first adsorption / desorption tank B12 is high. When the gas to be treated used for the cooling comes into contact with the third adsorption / desorption element 81, the third adsorption / desorption element 81 adsorbs the organic solvent. Further, except for the cooling treatment of the first adsorption / desorption element A14 and the first adsorption / desorption element B15, the gas to be treated in a state where the concentration of the organic solvent is relatively low comes into contact with the third adsorption / desorption element 81, thereby causing the third adsorption / desorption element 81. The element 81 desorbs the organic solvent. Therefore, the third adsorption / desorption element 81 equalizes the concentration of the organic solvent in the gas to be treated, so that the gas to be treated having a high concentration of the organic solvent is supplied to the cooling tank, and the organic solvent in the cooling tank is supplied. Adsorption of solvent can be suppressed.

Further, the organic solvent recovery system 100B of the second embodiment simplifies the organic solvent recovery system of the present invention because the number of piping lines L11, valves on the piping line L11, and cooling blower can be reduced as compared with the organic solvent recovery system 100A. And space can be saved.

Further, in the second embodiment, by reducing the number of cooling blowers, the effect of suppressing the noise of the organic solvent recovery system of the present invention can be obtained.

The organic solvent was recovered using the organic solvent recovery systems 100A and 100B described above as follows.

<Example 1>
In Example 1, an organic solvent recovery system 100A was used. As the gas to be treated by this organic solvent recovery system 100A, a gas at 35 ° C. containing 2000 ppm of ethyl acetate was used. Further, in the organic solvent recovery system 100A, nitrogen gas is used as the carrier gas, and ^{activated carbon fibers having a BET specific surface area of 1500 m 2} / g are used as the first adsorption / desorption elements A14 and B15 as the second adsorption / desorption element 32. Activated carbon fibers with a BET specific surface area of 2000 m ^{2 / g were used.}

While the adsorption process is performed by supplying the gas to be treated to one first adsorption / desorption element at an air volume of 7 Nm ³ / min for 15 minutes, the carrier gas is supplied to the other first adsorption / desorption element at 1.5 Nm ³ / min. Then, the desorption process was performed. The carrier gas temperature in the condenser 21 of the condensation recovery device 20 was set to be 10 ° C. Further, the carrier gas temperature adjusted to the low temperature state in the second temperature controller 50 was set to 10 ° C., and the carrier gas temperature adjusted to the high temperature state was set to 120 ° C. Further, the carrier gas temperature in the first suction / detachment element attachment / detachment heater 13 was set to be 120 ° C.

<Example 2>
In Example 2, the organic solvent recovery system 100B was used. As the gas to be treated by the organic solvent recovery system 100B, a gas at 35 ° C. containing 2000 ppm of ethyl acetate was used. Further, nitrogen gas is used as the carrier gas used in the organic solvent recovery system 100B, ^{and activated carbon fibers having a BET specific surface area of 1500 m 2} / g are used as the first adsorption / desorption elements A14 and B15, as the second adsorption / desorption element 32. Activated carbon fibers having a BET specific surface area of 2000 m ² / g were used, and coconut shell granular activated carbon having a ^{BET specific surface area of 1100 m 2} / g was used as the third adsorption / desorption element 81.

While the adsorption process is performed by supplying the gas to be treated to one first adsorption / desorption element at an air volume of 7 Nm ³ / min for 15 minutes, the carrier gas is supplied to the other first adsorption / desorption element at 1.5 Nm ³ / min. Then, the desorption process was performed. The carrier gas temperature in the condenser 21 of the condensation recovery device 20 was set to be 10 ° C. Further, the carrier gas temperature adjusted to the low temperature state in the second temperature controller 50 was set to 10 ° C., and the carrier gas temperature adjusted to the high temperature state was set to 120 ° C. Further, the carrier gas temperature in the first suction / detachment element attachment / detachment heater 13 was set to be 120 ° C.

<Comparative example 1>
In Comparative Example 1, the configuration of the organic solvent recovery system 100A does not use the piping line L11, the cooling blower 70, and the piping line L12, that is, the cooling treatment of the first suction / desorption element A14 and the first suction / desorption element B15. An organic solvent recovery system was used in which the above was not carried out. Other than this, the same operation as in Example 1 was performed.

As can be seen from Table 1, in each of Examples 1 and 2, the efficiency of removing the organic solvent with respect to the gas to be treated was improved as compared with Comparative Example 1. That is, it was experimentally confirmed that the purification ability for the gas to be treated and the recovery rate of the organic solvent can be improved by using the organic solvent recovery system of the present invention.

It should be noted that each of the above-disclosed embodiments and examples is merely an example and is not restrictive. The present invention also includes embodiments and examples in which the configurations disclosed in each embodiment and the configurations disclosed in each embodiment are appropriately combined. That is, the technical scope of the present invention is valid depending on the scope of claims, and includes the description of the claims and the meaning equivalent to the description and all changes, modifications, replacements, etc. within the scope.

10 First suction / desorption processing device 11 First suction / desorption tank A
12 First suction / desorption tank B
13 1st suction / detachment element attachment / detachment heater 14 1st suction / detachment element A
15 First adsorption / desorption element B
20 Condensation recovery device 21 Condenser 22 Recovery tank 30 Second suction / desorption treatment device 31 Second suction / desorption tank 32 Second suction / desorption element 33 Second suction / desorption element Desorption heater 40 Circulation blower 50 Second temperature controller 60 Processed gas Blower 70 Cooling blower 80 Third suction / desorption processing device 81 Third suction / desorption element L1 Circulation path L2 Piping line (introduction path)
L3 to L9 Piping line L11 Piping line (cooling path)
L12 piping line (return line)

Claims (8)

By separating the organic solvent from the gas to be treated containing the organic solvent introduced from the introduction route, the gas to be treated is purified and discharged, and the organic solvent separated from the gas to be treated is recovered by using the carrier gas. Organic solvent recovery system
A first adsorption / desorption treatment device having a first adsorption / desorption element for adsorbing / desorbing an organic solvent in a carrier gas circulation path, a condensing / recovery device that condenses the organic solvent and recovers it as a condensate, and an organic solvent is adsorbed / desorbed. A second suction / desorption processing device having a second suction / desorption element is provided.
A first temperature controlling means for controlling the temperature of the carrier gas to be introduced into the first suction / desorption processing apparatus to a high temperature, and
A second temperature control means for controlling the temperature of the carrier gas to be introduced into the second adsorption / desorption treatment apparatus to a low temperature or a high temperature, and
A cooling path for introducing a part of the gas to be treated passing through the introduction path into the first suction / desorption treatment device for cooling the first suction / desorption element, and the discharge from the first suction / desorption treatment device. It is provided with a return route for returning the gas to be treated used for cooling to the introduction route.
In the first adsorption / desorption treatment apparatus, the gas to be treated from the introduction path, the carrier gas heated to a high temperature by the first temperature adjusting means, and the gas to be treated from the cooling path are sequentially arranged in the first state. By repeatedly contacting the adsorption / desorption element, the organic solvent is moved from the gas to be treated to the carrier gas heated to a high temperature, and the first adsorption / desorption element after contacting with the carrier gas heated to a high temperature is described. After cooling with the gas to be treated introduced from the cooling path, the contact is made with the gas to be treated introduced from the introduction path again.
The condensation recovery device condenses the organic solvent contained in the carrier gas by adjusting the temperature of the carrier gas discharged from the first adsorption / desorption treatment device to a low temperature state.
The second adsorption / desorption treatment device is organic by alternately contacting the second adsorption / desorption element by adjusting the temperature of the carrier gas discharged from the condensation recovery device to a high temperature or a low temperature by the second temperature adjusting means. An organic solvent recovery system characterized by moving a solvent from a low temperature carrier gas to a high temperature carrier gas. The claim is characterized in that, in the flow path of the gas to be treated, a confluence point of the introduction path and the return path is provided downstream of the branch point of the introduction path and the cooling path. The organic solvent recovery system according to 1. The cooling path is configured to be the same as the introduction path.
A third suction / desorption treatment device having a third suction / desorption element that adsorbs and desorbs an organic solvent between the confluence point of the introduction path and the return path and the first suction / desorption treatment device is provided. The organic solvent recovery system according to claim 1. The organic solvent recovery system according to any one of claims 1 to 3, wherein the second adsorption element has a larger adsorption capacity than the first adsorption element. The organic solvent recovery system according to claim 4, wherein the BET specific surface area of the second adsorption / desorption element is larger than the BET specific surface area of the first adsorption / desorption element. The organic solvent recovery system according to any one of claims 1 to 5, wherein the carrier gas is an inert gas. The organic solvent recovery system according to any one of claims 1 to 6, wherein the first adsorption / desorption element is made of activated carbon fiber. The organic solvent recovery system according to any one of claims 1 to 7, wherein the second adsorption / desorption element is made of activated carbon fiber.

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