JPH11276840A - Method and device for recovering organic solvent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an organic solvent recovery device and a method having an adsorption element whose adsorption component is composed of activated carbon fiber(ACF) exhibit a similar organic solvent discharge preventing effect with less adsorption element as compared with conventional methods. SOLUTION: An organic solvent recovery device formed by vertically arranging adsorption elements 12 composed of cylindrically formed activated carbon fiber in an adsorption can 1 is used to pass an organic solvent-containing gas G1 to be treated through the adsorption elements 12. Next, the organic solvent adsorbed on the adsorption elements 12 is desorbed by a water vapor. The water vapor and a drain remaining in the lower layer of the adsorption element 12 and containing the organic solvent are discharged in an adsorption process, at this time, a gas containing the organic solvent is refluxed to a supply side of the gas to be treated through a reflux passage 22. On the other hand, the treated gas passed through the adsorption elements 12 besides the lower layer thereof is exhausted to the outside of the system as a clean gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solvent recovery apparatus in which an adsorption element having an activated carbon fiber (abbreviation: ACF) formed into a cylindrical shape as an adsorption element is vertically arranged in an adsorption can and a solvent recovery apparatus. The present invention relates to a method for recovering an organic solvent from a used gas containing an organic solvent.

[0002]

2. Description of the Related Art In various industries, alcohols such as methanol and ethanol discharged from washing and drying processes; ketones such as acetone and MEK; and various organic solvents such as chlorinated solvents such as tricrene and perchrene are contained. The exhaust gas (raw gas) is supplied to and adsorbed to an adsorption element using ACF as an adsorption element, and the purified processing gas passing through the adsorption element is discharged out of the system, and the organic solvent is adsorbed. The step of supplying a heated gas (eg, air) or heated steam to the adsorption element to desorb and recover the organic solvent is widely known and industrially employed (for example, Japanese Patent Publication No. 54-3091).
No. 7, Japanese Patent Publication No. 4-66605, Japanese Utility Model Publication No. 58-
No. 37456).

In a conventional apparatus used for the method for recovering an organic solvent from an exhaust gas containing an organic solvent, an adsorbing element having an ACF as an adsorbing element formed into a cylindrical shape is provided in an adsorbing vessel with an inner wall separated from an inner wall. There is an organic solvent recovery device which is vertically arranged to form an outer chamber outside the adsorbing element and an inner chamber inside the adsorbing element. In the organic solvent recovery device, adsorption and desorption are sequentially performed by passing an organic solvent-containing exhaust gas and a desorption gas alternately. Normally, two or more adsorbers are arranged in parallel (two units), and each adsorber is used for adsorption and desorption, or the timing of the treatment is shifted, and the desorption process and the adsorption process are continuously performed in parallel. The method is adopted.

A solvent recovery method and a recovery apparatus using ACF as an adsorption element utilize the characteristics of ACF, that is, the characteristics of being capable of adsorbing even an organic solvent having a very low concentration and the characteristics of high adsorption speed, to efficiently and efficiently online. There is an advantage that exhaust gas treatment and solvent recovery can be performed.

[0005]

However, the ACF
When the organic solvent is adsorbed using a solvent recovery device provided with an adsorption element having an adsorption element, and then steam is supplied to the adsorption element adsorbing the organic solvent to desorb the organic solvent, the adsorption element is Because the ACF with a small diameter is shaped like a felt with a high density, the water vapor used in the desorption process tends to accumulate as water vapor or drain containing organic solvent in the lower part of the adsorption element and the bottom of the adsorption can. There is.

[0006] In particular, when a cylindrical ACF adsorption element is vertically disposed in an adsorption can, or when the temperature of an organic solvent-containing exhaust gas (raw gas) supplied as a gas to be treated is low, the desorption step is performed. Water vapor and drain containing an organic solvent easily remain in the lower part of the adsorption element and the lower part of the adsorption vessel.

By the way, in the adsorption can of a conventional organic solvent recovery apparatus provided with an adsorption element having an ACF as an adsorption element, the drain remaining in the bottom of the adsorption can in the desorption step is usually discharged to the bottom of the adsorption can. Although the gas is discharged from the outlet, there is only a treated gas discharge port in the upper part of the adsorption can for discharging the gas, so that at the end of the desorption step, water vapor containing the organic solvent gas remains at the bottom of the adsorption can. At the same time, as described above, water vapor and drain containing an organic solvent remain in the lower part of the adsorption element.

[0008] Even after the completion of the desorption step, water vapor and drain containing a large amount of organic solvent remaining at the bottom of the adsorption vessel and the lower part of the adsorption element are removed in the subsequent adsorption step. Is pushed out to the lower part of the processed side by the gas to be processed (raw gas) passing through. As a result, the organic solvent gas may be discharged to the outside of the system from the treated gas discharge port in the upper part of the adsorption vessel due to the water vapor and the drain containing the organic solvent in the lower part of the treated side. A large amount of organic solvent may be discharged out of the system.

As a countermeasure in such a case, after supplying steam as a desorption gas, the air volume of the organic solvent-containing gas to be treated is reduced in the early stage of the adsorption process, and after the adsorption can is sufficiently cooled, the air volume is reduced. A method of releasing the water, a method of supplying an excessive amount of water vapor, and completely replacing the water vapor with a large amount of an organic solvent can be considered.

[0010] However, the above-mentioned method has a problem that the discharge of the organic solvent is suppressed but insufficient, and the process becomes complicated and cannot be used at the time of adsorption. Further, the above-mentioned method has a problem that the supply of excess steam temporarily hinders the discharge of clean gas, and also increases running costs.

Therefore, the present invention provides a solvent recovery apparatus and a solvent recovery method having an adsorption element having an ACF as an adsorption element, wherein the organic solvent-containing water vapor contained in the adsorption element after the desorption step with the water vapor is performed. Drain,
In addition, it is possible to improve the pollution of the gas discharged to the outside of the system by the organic solvent-containing water vapor / drain remaining in the lower part of the solvent recovery device, and to solve the above problem by improving the simple process and the device. An object of the present invention is to provide an organic solvent recovery method and a recovery apparatus.

[0012]

In order to solve the above-mentioned problems, an organic solvent recovery apparatus according to the present invention comprises an adsorbing element having activated carbon fibers formed into a tubular shape as adsorbing elements. An organic solvent recovery apparatus having an outer chamber outside the adsorbing element and an adsorbing can having an inner chamber formed inside the adsorbing element by vertically disposing the adsorbing element from the inner wall, and the adsorbing can is (1) a treated gas supply port for supplying a treated gas containing an organic solvent to the outer chamber, (2) a treated gas outlet for discharging a clean gas from the top of the inner chamber, 3) a bottom outlet and a reflux path for refluxing the organic solvent-containing gas from the bottom of the inner chamber to the gas supply side, and (4) a steam supply for supplying desorption steam from a lower portion of the inner chamber. A mouth and (5) the desorbed organic solvent together with water vapor in the outer chamber. It characterized by having a steam outlet for al discharged.

Further, the organic solvent recovery method of the present invention uses an organic solvent recovery apparatus in which an adsorption element having activated carbon fibers formed into a tubular shape as an adsorption element is vertically arranged in an adsorption can. An adsorption method in which the gas to be treated is passed through the adsorption element, whereby the organic solvent contained in the gas to be treated is adsorbed on the adsorption element, and the treated gas passing through the adsorption element is discharged out of the system. In a cleaning step, and in an organic solvent recovery method including a desorption / recovery step of recovering the organic solvent by desorbing the organic solvent adsorbed on the adsorption element with water vapor, the adsorption element regenerated by desorption,
A gas containing an organic solvent discharged from the lower layer of the adsorption element by supplying an organic solvent-containing gas to be processed, discharging the purified processed gas passing through a portion other than the lower layer of the adsorption element to the outside of the system. Is refluxed to the gas supply side.

In the above method, the drain remaining in the bottom of the adsorption vessel is withdrawn from the bottom of the adsorption vessel by ordinary means and separated into a recovered solvent and condensed water via a condensation system.

It is desirable that the time when the treated gas that has passed through the lower part of the adsorption element be recirculated and supplied to the supply side of the gas to be treated is at the beginning of the adsorption / cleaning step. However,
The processed gas may be constantly supplied to the gas supply side under reflux.

According to the present invention, regardless of the temperature of the gas to be treated, regardless of the temperature of the gas to be treated, the drain of the water vapor used for desorption collected at the bottom of the adsorption vessel and the water vapor containing organic solvent collected at the lower part of the adsorption element (high humidity gas)・ The organic solvent gas due to the drain is discharged from the opening at the bottom of the adsorption can without being mixed into the treated gas system discharged outside the system at the start of the adsorption step, and the gas containing the organic solvent is supplied to the gas to be treated. Refluxed to Therefore, the present invention can suppress a large amount of the organic solvent from being discharged out of the system in the early stage of the adsorption step.

Further, the mechanism of the organic solvent recovery apparatus of the present invention is simply provided with an opening at the bottom of the adsorption vessel and connected to the existing pipe on the supply side of the gas to be treated. It can be realized at low cost, and the device configuration is simple.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

FIG. 1 is a conceptual view showing a simplified organic solvent recovery apparatus of the present invention.

FIG. 2 is a conceptual diagram showing a simplified organic solvent recovery apparatus of the present invention in which two adsorption cans are provided in parallel and adsorption and desorption can be alternately performed in each adsorption can. . For practical use, usually, it is desirable to install a plurality of adsorption cans in two or more stations and to continuously perform a cycle of alternately performing adsorption and desorption while shifting the operation time of each adsorption can.

In FIGS. 1 and 2, reference numerals 1 and 2 denote an adsorber in which an adsorbing element is disposed, 3 to 10, 13 and 14 denote valves, 11 denotes a condenser, and 12 denotes an adsorbing element.

In the adsorption cans 1 and 2, a cylindrical adsorption element 12 is provided.
Are vertically arranged at a certain distance from the inner walls of the adsorption cans 1 and 2, and an outer chamber 15 is formed outside the adsorption element 12 and an inner chamber 16 is formed inside the adsorption element 12.

A gas supply port 17 for supplying a gas to be treated containing an organic solvent into the outer chamber 15 is provided in the adsorption vessels 1 and 2.
And a valve 3 for controlling the flow of the organic solvent-containing gas into the gas supply port 17 to be processed, and the purified processed gas that has passed through the adsorption element 12 and moved to the inner chamber 16 to the outside of the system. A treated gas discharge port 18 for discharging, a valve 5 for controlling the discharge of the treated gas from the treated gas discharge port 18, and a water vapor for desorbing the organic solvent adsorbed on the adsorption element 12. A steam supply port 19 provided at a lower portion of the supply inner chamber 16, a valve 7 for controlling the flow of steam into the steam supply port 19, and a steam containing a high concentration of an organic solvent desorbed by the steam is discharged. A steam outlet 20 provided below the outer chamber 15, a valve 10 for controlling the discharge of the organic solvent-containing steam from the steam outlet 20, and an organic solvent-containing gas remaining at the bottom of the inner chamber 16. Drain Bottom outlet 21 and the organic solvent-containing gas and a valve 13 to control the discharge of the drain for discharging is provided.

A gas-liquid separator 23 is disposed downstream of the valve 13 for separating a liquid and a gas from the organic solvent-containing gas and the drain discharged from the bottom of the inner chamber 16. Further, a recirculation path 22 for recirculating the gas separated by the gas-liquid separator 23 to the side of the gas to be treated is provided. The liquid discharged from the gas-liquid separator 23 is transferred to the condensing device 11 described later so that the organic solvent can be recovered.

The water vapor supply port 19 supplies water vapor to the inner chamber 16 inside the adsorption element 12, and is provided so that the water vapor passes through the adsorption element 12 toward the outer chamber 15 outside the adsorption element 12. This is preferable in preventing the temperature of steam from lowering.

The gas to be treated supply port 17 is provided so that the gas to be treated can be supplied to the outer chamber 15 in the opposite direction to the flow of water vapor and the gas to be treated can pass through the adsorption element 12 toward the center of the adsorption element 12. Is preferable in order to improve the desorption efficiency of ACF.

A valve 10 is provided in the outer chamber 15 of the adsorption cans 1 and 2.
The condenser 11 is connected via the. The condenser 1
Reference numeral 1 has a function of condensing the organic solvent-containing steam discharged from the outer chamber 15 and discharging the separated organic solvent and water to recover the organic solvent.

The ACF used for the adsorption element used in the organic solvent recovery apparatus of the present invention is an ACF derived from acrylonitrile fiber, rayon, phenolic fiber, pitch fiber, or the like as a general adsorption element material. Can be used. The ACF used for the adsorption element in the organic solvent recovery device of the present invention is formed by winding a sheet material such as an ACF fabric or a mat around a gas-permeable support to form an ACF layer, or increasing the layer height to increase the self-supporting property. A cylindrical bag shaped into a cylindrical shape is used.

The method for recovering an organic solvent using the apparatus for recovering an organic solvent according to the present invention will be described below with reference to FIG. I do.

The organic solvent-containing gas (gas to be treated) G1 is
Through the valve 3, the gas is supplied from the gas supply port 17 into the outer chamber 15 of the adsorption can 1. At this time, the valve 7 on the steam supply side for desorption and the valve 9 on the steam discharge side containing organic solvent are closed. The gas to be processed G supplied to the adsorption element 12
1 passes through the layer of the adsorption element 12, and the organic solvent contained in the gas to be treated G1 is fixed by adsorption to the adsorption element 12. Of the adsorbed gas that has passed through the adsorption element 12, the purified processed gas G <b> 2 existing outside the lower layer of the inner chamber 16 is discharged out of the system by opening the valve 5 from the processed gas discharge port 18. Is done.

On the other hand, due to the supply pressure of the gas to be treated G1, the organic solvent is extruded together with the water vapor and the drain in the lower layer of the adsorption element 12, and remains in the lower layer of the inner chamber 16. Further, a large amount of the organic solvent is dissolved in the residual water vapor and the drain, and since the temperature is high, the organic solvent is gradually vaporized.
6, the organic solvent, water vapor and drain accumulated in the adsorption element 12 gradually decrease with the lapse of time in the adsorption step.

Of the steam and drain remaining in the adsorption can 1,
The drain collected at the bottom is discharged from the bottom of the can at a stretch when the pressure inside the can is temporarily increased by the raw gas at the start of the adsorption process, and the water vapor and the drain remaining in the lower part of the adsorption element are gradually removed from the can. The organic solvent contained in the water vapor and the drain is discharged simultaneously from the bottom.

When the valve 13 is opened, the bottom discharge component containing such an organic solvent is supplied to the bottom discharge port 2 in the lower part of the adsorber 1.
1 and is separated into a liquid and a gas by a gas-liquid separator 23, the liquid is transferred to the condenser 11 to recover the organic solvent, and the gas containing the organic solvent is supplied to the processing gas supply side through the reflux path 22. The gas is recirculated to the recirculation gas G3, merges with the gas to be treated, and is treated again in the adsorption vessel 1. The gas-liquid separator 23 is preferably provided with a cooling mechanism to remove as much moisture as possible in the exhaust gas and to lower the gas temperature from the viewpoint of increasing the efficiency of adsorption of the reflux gas.

Reflux gas G recirculated to the supply side of the gas to be treated
3 (the amount of exhaust gas from the bottom outlet 21) is 0.1 to 10 vol% of the supply gas amount, preferably 0.5 to 5 vol.
% May be sufficient.

The concentration of the organic solvent in the treated gas in which the gas to be treated passes through the lower layer of the adsorption element 12 is relatively high at the beginning of the adsorption step, but the adsorption step proceeds and the adsorption element 12 dries. Decrease. When the adsorption element 12 is completely dried, there is no inhibition of adsorption and there is no need for reflux any more. At this point, the valve 13 of the reflux path 22 is closed and the inner chamber 1 is closed.
The entire amount of the gas in 6 can be discharged out of the system from the treated gas outlet 18 as a purified treated gas.

However, the timing of reflux supply to the supply side of the gas to be treated is not limited to the time when the organic solvent having a relatively high concentration accumulates at the bottom of the inner chamber 16 at the beginning of the adsorption process, but also during the entire period of the adsorption process. Any time, any time can be appropriately selected. In addition, during the adsorption step of supplying the gas to be treated, the valve 13 of the return path 22 is opened, and a certain amount of the gas in the lower layer of the inner chamber 16 out of the treated gas that has passed through the layer of the adsorption element 12 is constantly returned to the reflux system. Driving with the program that returns to
This is preferable in terms of simplification of the device and operation.

The timing of closing the valve 13 of the recirculation passage 22 and the ratio of the outgassing gas to the recirculation gas G3 can be determined based on the actual operation data of the apparatus. It can also be done automatically or manually while monitoring the progress.

By doing so, the solvent can be recovered by a simple mechanism without requiring a special drying mechanism. However, in the present invention, the drying mechanism is not necessarily excluded, and a drying step can be used in combination. It is also recommended as a preferable example that after the desorption is completed, the adsorbing element wet by the desorbed steam is dried and cooled by blowing sufficiently fresh air before the next adsorption. That is, when supplying a gas for drying after desorption, the gas after passing through the adsorption element 12 is also
The gas that has passed through the upper layer of the adsorption element 12 can be returned to the system, and the gas that has passed through the lower layer can be returned to the return path 22 with the valve 13 opened with the valve 13 opened and returned to dryness.

After the end of the adsorption step, the valve 3 of the gas supply system to be treated is
Is closed, the desorption system valve 7 is opened, and the water vapor as the desorption medium passes through the adsorption element 12 to desorb the organic solvent adsorbed and fixed to the adsorption element 12 by the water vapor. An organic solvent-containing steam is supplied to a condenser 11 through a valve 10 from a steam outlet 20 for discharging the solvent, separated into water as the desorbing medium and the organic solvent, and the organic solvent is recovered.

The above operation has been described with reference to the organic solvent recovery apparatus shown in FIG. 1 in the case where the number of adsorption cans is one, but in a practical organic solvent recovery apparatus in the case where there are two or more adsorption cans. Also, the same operation procedure can be applied.

For example, in the organic solvent recovery apparatus shown in FIG. 2 in which the number of the adsorption vessels 1 and 2 is two (two units), the valves 3, 5 and 13 are opened on one adsorption vessel 1 side, and the valve is opened. 7
Is closed, the gas containing the organic solvent flows through the reflux path 22, the adsorption is performed again in the adsorption vessel 1, and the purified treated gas is discharged out of the system. At this time, if the valves 8 and 10 are opened and the valves 4, 6 and 14 are closed on the adsorption can 2 side, desorption by steam is performed in the S1 and S2 flows, and the desorbed gas is condensed by the condensing device 11. And is condensed to recover the organic solvent. After a certain period of time, the opening and closing of each of the valves are all reversed, the desorption is performed in the adsorption can 1, and the adsorption is performed in the adsorption can 2.

[0042]

EXAMPLE An example was carried out as follows using an organic solvent recovery apparatus having the two adsorption cans shown in FIG.

4 kg of ACF derived from phenolic fiber is wound around a breathable support in a 0.35 m ³ adsorber and shaped into a cylinder, and the adsorber having an adsorbent layer is arranged upright to form an adsorber. did. The adsorption cans were arranged in two rows, and adsorption and desorption were alternately repeated.

5 Nm ³ / min of air containing about 5,000 ppm of methylene chloride as a raw gas containing a reflux gas
The adsorption was performed at a flow rate of The concentration of methylene chloride discharged from the treated gas outlet at the top of the adsorber began to gradually increase after the start of adsorption, and reached 20 ppm at the peak, but then continued to decrease and exceeded the lower limit of measurement of the measuring device 8 minutes after the start of adsorption. As a result, it could not be measured.

Further, the amount of the recirculated gas which discharged the processed gas in the lower layer of the inner chamber from the valve 13 and returned to the original gas was 0.9% of the original gas flow rate. The methylene chloride concentration of this reflux gas is 1
It was 0000 ppm. FIG. 3 shows the methylene chloride concentration of the treated gas discharged from the treated gas discharge port (curve A) and the methylene chloride concentration of the reflux gas discharged from the bottom discharge port (curve B) in this embodiment. The graph is shown with the time (minutes) on the axis and the methylene chloride concentration (ppm) on the vertical axis.

After the raw gas is supplied to the adsorption element at a flow rate of 5 Nm ³ / min for 8 minutes to perform the adsorption treatment, the raw gas valve 3 of the adsorber 1 is closed, and the desorption valve 7 is opened to open the adsorber 140. ° C
Is supplied for 6 minutes at a steam amount of 0.52 kg / ACF kg to desorb the organic solvent fixed on the adsorption element.
The organic solvent was condensed by a condenser and collected. As a result, the recovery of methylene chloride was 99.8%.

FIG. 5 shows the peak concentration (ppm) of the methylene chloride discharge of the treated gas from the treated gas outlet at the upper part of the adsorption vessel, with the horizontal axis representing the amount of the recirculated gas (% of the lower layer gas extracted from the inner chamber gas). ) Is a graph with the ordinate as the vertical axis.

Comparative Example Using the apparatus of the above embodiment,
It carried out by the method which closed all the circuits of the reflux system.

About 5,000 methylene chloride was used as a raw gas.
The air containing ppm was adsorbed at a flow rate of 5 Nm ³ / min. The concentration of methylene chloride discharged from the treated gas outlet at the top of the adsorption vessel began to gradually increase after the start of adsorption, and reached 250 ppm at the peak, but continued to decrease thereafter, but even 8 minutes after the start of adsorption, 85 ppm of solvent-containing gas Was discharged. FIG. 4 shows the methylene chloride concentration of the treated gas discharged from the treated gas outlet in this comparative example.
Time (min) on the horizontal axis, methylene chloride concentration (ppm) on the vertical axis
This is shown in the graph.

The raw gas is supplied to the adsorption element at a flow rate of 5 Nm ³ / min for 8 minutes, and after the adsorption treatment, the raw gas valve of the adsorption can is closed, the desorption valve is opened, and steam at 140 ° C. is supplied for 6 minutes. The organic solvent fixed to the adsorption element was desorbed, and the organic solvent was condensed and collected by a condenser. As a result, the recovery of methylene chloride was 98.0%.

[0051]

According to the conventional organic solvent recovery apparatus, an excessive amount of adsorption element is used to suppress the concentration of the organic solvent in the treated gas discharged outside the system. Thus, the same organic solvent discharge prevention effect can be exhibited with a smaller amount of the adsorption element, and an efficient organic solvent recovery apparatus and method can be provided.

According to the present invention, the diffusion into the atmosphere can be almost eliminated, and this greatly contributes to the prevention of air pollution.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a simplified organic solvent recovery apparatus of the present invention.

FIG. 2 is a conceptual diagram showing a simplified solvent recovery apparatus of the present invention in which two adsorption cans are provided in parallel and adsorption and desorption can be alternately performed in each adsorption can.

FIG. 3 is a graph showing the methylene chloride concentration of a treated gas discharged from a treated gas outlet (curve A) and the methylene chloride concentration of a reflux gas discharged from a bottom outlet (curve B) in an embodiment, on the horizontal axis. Is a time (minutes), and the vertical axis is a graph showing the methylene chloride concentration (ppm).

FIG. 4 is a graph showing the methylene chloride concentration of a treated gas discharged from a treated gas outlet in a comparative example, with the horizontal axis representing time (minutes) and the vertical axis representing methylene chloride concentration (ppm).

FIG. 5 is a graph showing the amount of recirculated gas (% of lower layer gas extracted from the inner chamber gas) on the horizontal axis, and the peak concentration (ppm) of methylene chloride discharge of the treated gas from the treated gas outlet at the upper part of the adsorption vessel.
Is a graph with the vertical axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2 Adsorption can, 3-10, 13, 14 Valve 11 Condenser, 12 Adsorption element 15 Outer room 16 Inner room 17 Gas supply port to be treated 18 Treated gas discharge port 19 Steam supply port 20 Steam discharge port 21 Bottom discharge Outlet 22 Reflux path 23 Gas-liquid separator

Claims (5)

[Claims] 1. An adsorbing element having activated carbon fibers formed into a tubular shape and having an adsorbing element is vertically disposed in an adsorbing vessel at a distance from an inner wall, so that an outer chamber is provided outside the adsorbing element and the adsorbing element is provided. An organic solvent recovery device having an adsorption can having an inner chamber formed inside an element, wherein the adsorption can comprises: (1) a supply of a gas to be treated for supplying a gas to be treated containing an organic solvent to the outer chamber; (2) a treated gas discharge port for discharging clean gas from the top of the inner chamber; and (3) an organic solvent-containing gas for recirculating the gas containing the organic solvent from the bottom of the inner chamber to the gas supply side. (4) a steam supply port for supplying desorbing steam from the lower portion of the inner chamber; and (5) steam for discharging the desorbed organic solvent from the outer chamber together with the steam. An organic solvent recovery device having a discharge port. 2. An organic solvent recovery device comprising an adsorption element having activated carbon fibers formed into a tubular shape and having an adsorption element disposed vertically in an adsorption vessel, and applying a gas to be treated containing an organic solvent to the adsorption element. An adsorbing / cleaning step of adsorbing an organic solvent contained in the gas to be treated by the adsorbing element by passing through the adsorbing element and discharging a treated gas passing through the adsorbing element to the outside of the system; and the adsorbing element In the organic solvent recovery method including the desorption / recovery step of recovering the organic solvent by desorbing the organic solvent adsorbed on the water vapor, the gas to be treated containing the organic solvent is supplied to the adsorption element regenerated by the desorption. Discharging the purified treated gas that has passed through other than the lower part of the adsorption element to the outside of the system, and refluxing the gas containing the organic solvent discharged from the lower part of the adsorption element to the supply side of the gas to be treated. Characterized by Organic solvent recovery method. 3. The method according to claim 1, wherein the gas containing the organic solvent, which has passed through the lower part of the adsorption element, is refluxed to the supply side of the gas to be treated, at an early stage of the adsorption / cleaning step. 3. The method for recovering an organic solvent according to 2. 4. The method for recovering an organic solvent according to claim 2, wherein the time when the treated gas passing through the lower layer portion of the adsorption element is refluxed and supplied to the gas to be treated is supplied. 5. A ratio of a gas containing an organic solvent to be supplied back to the supply side of the gas to be treated is 0.1 to 10 vol% with respect to a supply amount of the gas to be supplied to the adsorption vessel. 5. The method for recovering an organic solvent according to 3 or 4.