JP2001293329A - Device and method for recovering organic solvent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the contamination of the gas discharged to the outside caused by steam and drain containing organic solvents generated after a desorption process by means of steam in a device and method for recovering organic solvents using activated carbon fibers(ACF). SOLUTION: In the organic solvent recovering device which has an activated carbon fiber adsorption element 12 formed into a cylindrical shape in an adsorption drum 1, an outer room drain groove 102 and an inner room drain groove 104 are formed on a bottom plate 100 to properly discharge drain to the outside, whereby the element 12 is prevented from being brought into contact with drains 106 and 108.

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 activated carbon fibers (abbreviation: ACF) formed in a cylindrical shape as an adsorption element is vertically arranged in an adsorption can, and the apparatus is provided. To a method for recovering an organic solvent in a gas to be treated using

[0002]

2. Description of the Related Art In the electronics industry, the chemical industry, and various other industries, alcohols such as methanol and ethanol discharged from washing and drying processes using solvents; ketones such as acetone and MEK; A gas to be treated (raw gas) containing various organic solvents such as a chlorine-based solvent is supplied to an adsorption element having ACF as an adsorption element to adsorb various organic solvents thereon, and the solvent passes through the adsorption element and the solvent passes therethrough. Discharge the removed cleaning gas outside the system,
On the other hand, organic solvent recovery methods for desorbing and recovering an organic solvent by supplying a heated gas (eg, air) or heated steam to an adsorption element that has adsorbed the organic solvent are widely known, and these methods are industrially adopted. (For example, Japanese Patent Publication No. 54-309)
No. 17, Japanese Patent Publication No. 4-66605, Japanese Utility Model No. 58
-37456 gazette).

A conventional apparatus used in the method for recovering an organic solvent from a gas to be treated containing the organic solvent includes an adsorbing element having a cylindrical ACF as an adsorbing element, and an inner wall of the adsorbing vessel. There is an organic solvent recovery device having a structure in which an outer chamber is formed outside the adsorbing element and an inner chamber is formed inside the adsorbing element. The organic solvent recovery device sequentially performs adsorption and desorption by alternately passing the gas to be treated containing an organic solvent and the desorption gas through the ACF.

Usually, two or more adsorbers (two units) are arranged side by side, and each adsorber is used for adsorption and desorption processing or at a different timing, and desorption processing and adsorption processing are continuously performed in parallel. It adopts a system that performs it.

[0005] The solvent recovery method and the recovery apparatus using ACF as an adsorption element utilize the characteristics of ACF, that is, the characteristics of being able to adsorb an organic solvent having a very low concentration and the characteristics of having a high adsorption speed, and are efficient online. Another advantage is that the treatment of the gas to be treated and the recovery of the solvent can be performed.

[0006]

However, the ACF
When the organic solvent is adsorbed by using a solvent recovery device using an adsorption element having an adsorption element as the adsorption element, and then steam is supplied to the adsorption element adsorbing the organic solvent to desorb the organic solvent, the adsorption element is Since it is a structure in which a thin ACF is formed into a felt shape at a high density, part of the steam used in the desorption step becomes steam or drain containing an organic solvent having a large specific gravity, and these are the lower part of the inner chamber, the lower part of the adsorption element, And it is easy to collect in the lower part of the outer room.

[0007] In particular, when a cylindrical ACF adsorption element is vertically mounted on an adsorption can, or when the temperature of an organic solvent-containing gas (raw gas) supplied as a gas to be treated is low, the adsorption in the desorption step. Water vapor containing an organic solvent and drain easily remain in the lower layer portion of the element and the lower portion of the inner chamber.

By the way, in the adsorption can of a conventional organic solvent recovery apparatus using 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. It is discharged from the exit. However, as for the gas discharge, since the cleaning gas outlet is located only at the upper part of the adsorption can, at the end of the desorption step, water vapor containing the organic solvent gas remains at the bottom of the adsorption can.
Similarly, as described above, the lower layer of the adsorption element contains water vapor and a drain containing an organic solvent.

[0009] After the above-mentioned desorption step, the water vapor and drain containing a large amount of organic solvent remaining in the bottom of the adsorption vessel and the lower layer of the adsorption element pass through the adsorption element in the subsequent adsorption step. Of the gas to be treated (raw gas). As a result, the organic solvent gas gasified from the water vapor and the drain containing the organic solvent in the lower part of the inner chamber may move to the upper part in the adsorber and be discharged from the cleaning gas outlet to the outside of the system. In particular, a large amount of organic solvent may be discharged out of the system in the early stage of the process immediately after switching to the adsorption process.

[0010] As a countermeasure in such a case, after supplying steam as a desorption gas, the supply amount of the organic solvent-containing gas to be treated is kept low in the early stage of the adsorption step, and the supply amount after the adsorption vessel is sufficiently cooled. And a second method in which a sufficient amount of water vapor is supplied to the adsorption element in the desorption step to completely remove the remaining water vapor containing a large amount of the organic solvent.

However, in the first method, the discharge of the organic solvent can be suppressed to some extent, but it is not perfect.
Further, the process becomes complicated. Further, the second method has a problem that the time required for the desorption step is long because excess steam is supplied, and a large amount of steam is consumed, so that the running cost is increased.

According to the present invention, there is provided a solvent recovery apparatus and a solvent recovery method having such an adsorption element having an ACF as an adsorption element, wherein a water vapor / drain containing an organic solvent contained in the adsorption element after performing a desorption step with water vapor. Solves the problem by contaminating the cleaning gas discharged out of the system by the organic solvent-containing steam / drain remaining in the lower part of the solvent recovery device, and by simply improving the process and the device. It is an object of the present invention to provide an organic solvent recovery method and a recovery apparatus.

[0013]

The present invention to achieve the above object is as follows.

[1] By arranging an activated carbon fiber adsorption element formed in a cylindrical shape vertically in an adsorption can closed up and down with a top plate and a bottom plate, separated from the inner wall of the adsorption can,
An outer chamber outside the adsorbing element, an inner chamber formed inside the adsorbing element, and a gas supply port for supplying an organic solvent-containing gas to the adsorber to the outer chamber; A cleaning gas outlet for discharging a cleaning gas from the top of the chamber, a steam supply port for supplying desorbing steam from a lower portion of the inner chamber, and a steam outlet for discharging the desorbed organic solvent together with the steam from the outer chamber. In the organic solvent recovery device having the above, the bottom plate of the absorber can has an annular outer chamber drain groove and an outer chamber drain outlet protruding downward in the outer chamber, and an inner chamber drain groove protruding downward in the inner chamber, An internal chamber drain outlet, wherein the drain is made to flow down in each of the drain grooves so that the adsorption element is configured to avoid contact with the drain to avoid a wet state. apparatus.

[2] The organic solvent recovery apparatus according to [1], further comprising a bottom gas outlet at a lower portion of the inner chamber, and returning the organic solvent-containing gas staying at the bottom of the inner chamber to the gas to be treated.

[3] Using the organic solvent recovery apparatus according to [2], the organic solvent contained in the gas to be processed is passed through the adsorption element by passing the gas containing the organic solvent through the adsorption element. While adsorbing and purifying the cleaning gas from which the organic solvent has been removed through the adsorption element and discharged out of the system, and the organic solvent adsorbed on the adsorption element is desorbed with water vapor. In an organic solvent recovery method including a desorption / recovery step of recovering an organic solvent, an organic solvent-containing gas to be treated is supplied to an adsorption element that has been regenerated by desorption, and the organic element is passed through a part other than a lower layer of the adsorption element. An organic solvent, wherein the cleaning gas from which the solvent has been removed is discharged from the cleaning gas outlet, and the organic solvent-containing gas passing through the lower layer of the adsorption element is returned to the gas to be treated. Collection method.

[4] The method for recovering an organic solvent according to [3], wherein the organic solvent-containing gas that has passed through the lower part of the adsorption element is refluxed to the gas to be treated at the beginning of the adsorption / cleaning step.

[5] The organic solvent-containing gas which always passes through the lower part of the adsorption element is returned to the gas to be treated [3]
3. The method for recovering an organic solvent according to item 1.

[6] The ratio of the gas containing the organic solvent to be recirculated to the gas to be treated is 0.1 to 10 vol% with respect to the supply amount of the gas to be supplied to the adsorption vessel [3] to [5]. The method for recovering an organic solvent according to any one of the above.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing one example of the organic solvent recovery apparatus of the present invention.

FIG. 2 is a schematic diagram showing an example of an organic solvent recovery apparatus of the present invention in which two adsorption cans are provided side by side, and adsorption and desorption are alternately performed in each adsorption can. In practice, it is usually desirable to provide two or more adsorption cans in parallel and to continuously perform a cycle of alternately performing adsorption and desorption while shifting the operation time of each adsorption can.

In FIG. 1 and FIG. 2, reference numerals 1 and 2 denote adsorbers in which adsorbing elements are arranged. The adsorbers have a substantially cylindrical shape whose upper and lower ends are closed by a top plate and a bottom plate. 3 to 10, 13 and 14
Denotes a valve, 11 denotes a condenser, and 12 denotes an adsorption 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. Thus, an outer chamber 15 is formed outside the suction element 12 and an inner chamber 16 is formed inside the suction element 12.

The adsorption cans 1 and 2 are provided with a gas supply port 17 for supplying an organic solvent-containing gas (raw gas) into the outer chamber 15, and an organic gas supplied to the gas supply port 17. A valve 3 for controlling the flow rate of the solvent-containing gas to be treated;
And a cleaning gas outlet 18 for discharging the treated cleaning gas that has passed through the adsorption element 12 and moved to the inner chamber 16 to the outside of the system.
And valves 5 and 6 for controlling the amount of the cleaning gas discharged from the cleaning gas discharge port 18, and an organic solvent adsorbed on the adsorption element 12 at a supply port provided at the bottom of the inner chamber 16. A steam supply port 19 for supplying steam S1 for desorbing water, valves 7 and 8 for controlling the amount of steam flowing into the steam supply port 19, and for discharging steam containing a high concentration of an organic solvent desorbed by steam. Outside room 15
, A valve 10 for controlling the amount of water vapor containing organic solvent discharged from the water vapor discharge port 20, and an organic solvent-containing gas (organic solvent vapor, water vapor) retained at the bottom of the inner chamber 16. , A gas containing a gas to be treated, etc.) and drain, and valves 13 and 14 for controlling the discharge of the high-concentration organic solvent-containing gas and drain.

A gas-liquid separator 23 is disposed downstream of the valves 13 and 14 for receiving the organic solvent-containing gas and the drain discharged from the bottom of the inner chamber 16 and separating the liquid and the gas. Further, there is provided a recirculation path 22 for recirculating the gas separated by the gas-liquid separator 23 to the gas supply side. Further, the liquid discharged from the gas-liquid separator 23 is transferred to the condenser 11 described later, where the organic solvent is recovered.

The water vapor supply port 19 is provided so that water vapor is supplied to the inner chamber 16 inside the adsorption element 12, and 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 a direction opposite to the flowing direction of the water vapor, and the gas to be treated is directed toward the center of the adsorption element 12. ACF that can be passed
It is preferable from the viewpoint of improving the desorption efficiency.

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 11 condenses and separates the organic solvent-containing steam discharged from the outer chamber 15 into an organic solvent and water to recover the organic solvent.

The disc-shaped bottom plates 100 of the adsorption cans 1 and 2 each have an annular outer chamber drain groove 102 in which the lower end of the outer chamber 15 projects downward, and an inner chamber that projects downward in the lower part of the inner chamber 16. A drain groove 104 is formed. Outer room 15 and inner room 16
Is drained down into the outer chamber drain groove 102 and the inner chamber drain groove 104, and is stored in each groove as the outer chamber drain 106 and the inner chamber drain 108. Therefore, the adsorption element 1
2 can prevent the drains 106 and 108 from impregnating and becoming wet. The shape and dimensions of the drain groove are appropriately determined in consideration of operating conditions, drain amount, and the like.

The outer chamber drain outlet 110 is provided with a valve 112,
It is connected to the gas-liquid separator 23 via 113. The inner chamber drain outlets 114 and 115 are provided with a valve 116,
It is connected to the gas-liquid separator 23 via 117.

The ACF used for the adsorption element of the organic solvent recovery device of the present invention is acrylonitrile fiber, rayon,
ACF produced using phenolic fibers, pitch fibers and the like as raw materials can be used. ACF used for adsorption element
The ACF layer may be formed by winding an ACF fabric, a mat or the like around a permeable support to form an ACF layer, or by providing a self-supporting property by increasing the layer thickness to form a cylindrical shape.

An organic solvent recovery method using the above-described organic solvent recovery apparatus of the present invention will be described with reference to FIG. 1 by taking an example of a single adsorber in order to simplify and explain the present invention.

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 desorption steam supply port 19
7 and an organic solvent-containing steam outlet 20
Is closed.

The gas to be treated G1 supplied to the outer chamber 15 passes through the layer of the adsorption element 12, and at this time, the organic solvent contained in the gas to be treated G1 is adsorbed and removed by the adsorption element 12. Of the adsorbed gas that has passed through the adsorption element 12, the inner chamber 1
The cleaning gas G2 existing in the upper and middle portions of 6 is discharged out of the system through the cleaning gas discharge port 18 and the valve 5 sequentially.

On the other hand, by the supply pressure of the gas to be treated G1, the organic solvent is extruded together with the water vapor and the drain impregnated and held in the lower part of the adsorption element 12, and these are extruded.
Move to the bottom of 6. Since a large amount of organic solvent is dissolved in the residual steam and drain, and the temperature is high,
If the state continues, the organic solvent is gradually vaporized, and the gas containing the high-concentration organic solvent stays in the lower part of the inner chamber 16. It gradually decreases with the lapse of time in the adsorption step.

Of the water vapor and the drain remaining in the adsorption can 1, the drain quickly flows into drain grooves 102 and 104 formed in the bottom plate 100 of the adsorption can 1, and is quickly separated from the adsorption element 12. For this reason, the adsorption element 12 is prevented from being wet with the drain.

When the pressure inside the can is temporarily increased by the raw gas at the start of the adsorption step, the drains 106 and 108 collected in the drain grooves 102 and 104 are discharged at once at the outer chamber drain outlet 110 and the inner chamber drain. It is discharged from the outlet 114. The water vapor remaining in the lower part of the adsorption element is discharged from the bottom discharge port 21 of the adsorption can 1 by opening the valve 13 and then sent to the gas-liquid separator 23, where it is converted into liquid and gas. Separated. The separated liquid is transferred to the condenser 11 where the organic solvent is recovered. At the same time, the gas containing the organic solvent is returned to the supply side of the gas to be treated through the reflux path 22 as the reflux gas G3. It repeats that it joins and is processed again in the adsorption can 1.

It is preferable that the gas-liquid separator 23 is provided with a cooling mechanism, whereby the water in the exhaust gas can be efficiently removed, and the gas temperature is lowered to adsorb the organic solvent in the reflux gas. The efficiency of adsorption to the element can be increased.

Reflux gas G recirculated to the supply side of the gas to be treated
The amount of 3 (the amount of gas discharged from the bottom outlet 21) is preferably 0.1 to 10% by volume of the supplied gas G1, and more preferably 0.5 to 5% by volume.

As described above, the lower layer of the adsorption element 12 immediately after the completion of the desorption step is in a wet state with the water vapor used for the desorption. For this reason, the concentration of the organic solvent in the gas to be processed that has passed through the lower layer of the adsorption element 12 is relatively high in the early stage of the adsorption step. However, the adsorbing element 12 dries with time, and the concentration of the organic solvent decreases accordingly.

When the adsorption element 12 is completely dried,
Since there is no adsorption inhibition that causes an organic solvent to be mixed in the cleaning gas, and there is no longer a need for reflux, the reflux path 2
By closing the valve 13 interposed in 2, the entire amount of gas in the inner chamber 16 can be discharged from the cleaning gas outlet 18 to the outside as a cleaning gas.

However, the period of reflux to the gas to be treated may be not only the period in which the relatively high concentration of the organic solvent stays at the bottom of the inner chamber 16 at the beginning of the adsorption process, but also the entire period of the adsorption process. , An arbitrary period can be appropriately selected. During the adsorption step of supplying the gas to be treated, the valve 13 of the recirculation path 22 is opened, and a fixed amount of the gas in the lower part of the inner chamber 16 of the treated gas that has passed through the layer of the adsorption element 12 is constantly returned to the recirculation system. When driving with the program to return to
This is preferable because the simplification of the apparatus and the operation can be achieved.

The timing of closing the valve 13 of the recirculation path 22 and the ratio of the outgassing gas to the recirculation gas G3 are appropriately determined based on the actual operation data of the apparatus. However, it is also possible to install a concentration sensor at the cleaning gas outlet 18 and control the opening and closing of the valve 13 automatically or manually while monitoring the progress.

By providing the above-mentioned reflux path, the solvent can be recovered without reliably mixing the organic solvent into the cleaning gas without providing a drying mechanism or a drying step for the adsorption element. However, the present invention does not necessarily exclude the drying mechanism, and it is possible to use a drying step in combination.

For example, after the desorption step is completed, before the next adsorption step, a sufficiently clean air is passed through the adsorption element to dry and cool the adsorption element wet by the desorbed steam. Recommended as That is, when supplying the drying gas after desorption, similarly to the gas to be processed after passing through the adsorption element 12, the gas that has passed through the middle layer above the adsorption element 12 is out of the system, and the gas that has passed through the lower layer is Valve 13
Can be opened and returned to the reflux path 22, and the reflux can be continued until the adsorption element 12 is dried.

After the end of the adsorption step, the gas supply valve 3 is closed, and the steam supply valve 7 is opened to allow the desorbed steam to pass through the adsorption element 12.
The organic solvent that is adsorbed and fixed on the substrate is desorbed. Then
The steam containing the desorbed organic solvent is discharged to the steam outlet 20.
And supplied to the condenser 11 through the valve 10,
Here, water and an organic solvent are separated to recover the organic solvent.

Although the above operation has been described with reference to the organic solvent recovery apparatus shown in FIG. 1 where the number of adsorption cans is one, the same operation can be applied to an organic solvent recovery apparatus using two or more adsorption cans. .

For example, in the case of an organic solvent recovery apparatus using two (two units) adsorption cans 1 and 2 shown in FIG. 2, the valves 3, 5 and 13 of one adsorption can 1 are opened. ,
If the valve 7 is closed, the gas containing the organic solvent will be
2 and is returned to the adsorption can 1 again to perform adsorption.
The purified gas is discharged out of the system.

During the above period, when the valves 8 and 10 are opened and the valves 4, 6 and 14 are closed on the adsorption can 2 side, the adsorption element is desorbed by the steam S1, and the desorbed gas is controlled by the valve. 1
2 to a condenser 11 where it is condensed and the organic solvent is recovered. The steam S2 after the recovery of the organic solvent is discharged out of the system. Thereafter, when a predetermined time elapses, the opening and closing of each valve are all reversed, so that desorption is performed in the adsorption can 1 and adsorption is performed in the adsorption can 2.

[0051]

EXAMPLES Example 1 A gas to be treated was treated as follows using an organic solvent recovery apparatus having one adsorption vessel shown in FIG.

In a substantially cylindrical airtight can having a capacity of 0.35 m ³ , an adsorption element formed by winding 4 kg of ACF derived from phenolic fiber around a gas-permeable support and being formed into a cylindrical shape was attached with its axial direction vertical. An adsorption can was formed.

The bottom plate of the adsorbing can has an annular outer chamber drain groove (width 5c) projecting downward along the periphery of the bottom plate.
m, depth 5 cm) and a hemispherical inner chamber drain groove (diameter 1) bulging downward formed inside the outer chamber drain groove.
5 cm, depth 10 cm).

Air containing about 5,000 ppm of methylene chloride was used as the gas to be treated (raw gas) containing an organic solvent.
It was sent to the adsorption vessel 1 at a flow rate of Nm ³ / min. The concentration of methylene chloride discharged from the cleaning gas outlet at the top of the adsorber 1 gradually started to increase after the start of adsorption, and peaked at 10 pp.
However, the measurement continued to decrease, and after 8 minutes from the start of the adsorption, the measurement became lower than the lower limit of measurement by the measuring device, so that the measurement could not be performed.

Further, the amount of recirculated gas discharged from the valve 13 at the lower portion of the inner chamber and returned to the raw gas was set to 0.9% of the flow rate of the raw gas. The methylene chloride concentration of this reflux gas is 1
It was 0000 ppm.

After supplying the raw gas to the adsorption vessel 1 at a flow rate of 5 Nm ³ / min for 8 minutes to perform the adsorption treatment, the raw gas valve 3 of the adsorption vessel 1 is closed, and the desorption system valve 7 is opened. 140 ° C
Is supplied for 6 minutes at a vapor amount of 0.52 kg / ACF kg to desorb the organic solvent adsorbed on the adsorption element,
The organic solvent was condensed and recovered by the condenser.

In the latter half of the desorption step, the valves 112 and 116 were opened, and the drain collected in the drain grooves 102 and 104 was sent to the gas-liquid separator 23. The total amount of drain accumulated in each drain groove was l.

As a result, the recovery of methylene chloride was 9
9.8%.

Comparative Example 1 The same operation as in the above example was performed using the same apparatus as in the above example. However, the bottom plate of the adsorption can 1 was formed of a flat plate and had no drain groove. Further, unlike the operation of Example 1, in the latter half of the desorption process, the valves 112 and 116 were opened, and the operation of sending the drain collected in the drain grooves 102 and 104 to the gas-liquid separator 23 was not performed.

In the case of the comparative example, the concentration of methylene chloride discharged from the cleaning gas outlet at the top of the adsorption vessel gradually started to increase after the start of the adsorption, and reached 250 ppm at the peak.
Since then it has been decreasing. However, even after 8 minutes from the start of adsorption, 85
ppm of solvent-containing gas was discharged.

The recovery of methylene chloride was 98.0%.

[0062]

According to the present invention, a drain groove is formed in the bottom plate of the adsorption can, and the drain remaining in the lower part of the adsorption element is guided to the drain groove in the process of attaching and detaching the adsorption element and drying. Can be prevented from being absorbed and kept in a wet state. Therefore, in the adsorption step, it is possible to effectively prevent the organic solvent from being mixed in the cleaning gas and increasing the concentration of the organic solvent in the cleaning gas. Further, the time required for drying the adsorption element, the amount of steam, and the like can be reduced, and the operating cost can be reduced.

When a reflux path is provided to return the reflux gas to the gas to be treated, the concentration of the organic solvent in the cleaning gas can be further reduced.

[Brief description of the drawings]

FIG. 1 is a schematic flowchart showing one configuration example of the present invention.

FIG. 2 is a schematic flowchart showing another configuration example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 2 Adsorption cans 3-10, 13, 14 Valve 11 Condenser 12 Adsorption element 15 Outer room 16 Inner room 17 Gas supply port for processing 18 Purification gas discharge port 19 Steam supply port 20 Steam discharge port 21 Bottom discharge port 22 Reflux path 23 gas-liquid separator 100 disc-shaped bottom plate 102 outer chamber drain groove 104 inner chamber drain groove 106 outer chamber drain 108 inner chamber drain 110 outer chamber drain outlet 112, 113 valve 114, 115 inner chamber drain outlet 116, 117 valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D002 AA21 AB03 AC07 AC10 BA04 CA07 DA44 EA08 FA01 GA01 GB01 GB02 4G066 AA05B BA01 BA16 CA04 CA33 DA02 DA05 GA07

Claims (6)

[Claims] 1. An activated carbon fiber adsorption element formed into a tubular shape in an adsorption can closed vertically by a top plate and a bottom plate, and is vertically arranged at a distance from an inner wall of the adsorption can. An outer chamber, an inner chamber formed inside the adsorbing element, and a gas supply port for supplying an organic solvent-containing gas to the adsorber to the outer chamber; and a cleaning section from the top of the inner chamber. An organic solvent having a cleaning gas outlet for discharging gas, a steam supply port for supplying desorbed steam from a lower portion of the inner chamber, and a steam outlet for discharging the desorbed organic solvent from the outer chamber together with the steam. In the recovery apparatus, an annular outer chamber drain groove and an outer chamber drain outlet in which a bottom plate of the absorber can project downward in the outer chamber, and an inner chamber drain groove and an inner chamber drain outlet projecting in the inner chamber downward direction. And each of the above dresses An organic solvent recovery device characterized in that the drainage is caused to flow down to the drain groove so as to prevent the adsorption element from coming into contact with the drainage and becoming wet. 2. The organic solvent recovery apparatus according to claim 1, further comprising a bottom gas outlet at a lower portion of the inner chamber, wherein the organic solvent-containing gas staying at the inner chamber bottom is returned to the gas to be treated. 3. An organic solvent contained in the gas to be treated is adsorbed on the adsorption element by passing the gas to be treated containing an organic solvent through the adsorption element using the organic solvent recovery apparatus according to claim 2. And an adsorption / purification step of discharging the cleaning gas from which the organic solvent has been removed through the adsorption element to the outside of the system, and desorbing the organic solvent adsorbed on the adsorption element with water vapor to remove the organic solvent. In an organic solvent recovery method including a desorption / recovery step of recovering the organic solvent-containing gas to be treated, the organic solvent-containing gas to be treated is supplied to the adsorption element that has been regenerated by desorption, and the organic solvent passes through a part other than the lower part of the adsorption element. An organic solvent recovery method, comprising: discharging a removed cleaning gas from a cleaning gas outlet, and refluxing an organic solvent-containing gas passing through a lower portion of the adsorption element to a gas to be processed. . 4. The organic solvent recovery method according to claim 3, wherein the organic solvent-containing gas that has passed through the lower part of the adsorption element is returned to the gas to be treated in the initial stage of the adsorption / cleaning step. 5. The organic solvent recovery method according to claim 3, wherein the organic solvent-containing gas that always passes through the lower layer of the adsorption element is returned to the gas to be treated. 6. The gas according to claim 3, wherein the ratio of the gas containing the organic solvent to be refluxed to the gas to be treated is 0.1 to 10 vol% with respect to the supply amount of the gas to be treated supplied to the adsorption vessel. 3. The method for recovering an organic solvent according to item 1.