JP2001190922A - Method and apparatus for recovering organic solvent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and economical method and apparatus capable of effectively and efficiently recovering a solvent from a waste solvent, especially, a solvent waste liquid discharged from an electrophotographic photosensitive member manufacturing apparatus. SOLUTION: The organic solvent recovering method consists of a process for controlling a waste liquid within a predetermined temperature range to evaporate a solvent, a process for adsorbing the evaporated solvent by an adsorbent, a process for bringing the adsorbent into direct contact with steam to desorb solvent vapor to obtain desorbed gas, a process for condensing the desorbed gas to obtain a mixture of the liquefied solvent and water and a process for separating the solvent from the mixture. An organic solvent recovering apparatus consists of a container 1 for storing the waste liquid, a heater 3 for controlling the waste liquid to the predetermined temperature range to evaporate the solvent, adsorbing zones 5a, 5b having adsorbents 6a, 6b for adsorbing the evaporated solvent, a steam conduit 14 for desorbing the solvent vapor from the adsorbents, a condenser 7 for condensing the desorbed gas and a separation zone 8 for separating the solvent from the mixture of the liquefied solvent and water from the condenser.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for recovering an organic solvent.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic photosensitive member, a photosensitive member provided with a photosensitive layer using an inorganic photoconductive material or a photosensitive layer using an organic photoconductive material on a plate-like or drum-like conductive substrate. It has been known. Aluminum and aluminum alloys are widely used as conductive substrates. It has been pointed out that the electrophotographic performance is greatly affected not only by the properties of the photosensitive layer but also by the material properties of the substrate and the surface properties of the substrate. In particular,
Organic substances such as oils and fats, metal dust from polishing, and various types of dust in the air may cause image defects if they adhere to the surface of the substrate. Conventionally, the substrate should be cleaned by immersion using an organic solvent. Is commonly done. Organic solvents used in these washing methods include, for example, chlorinated solvents such as methylene chloride, ethylene chloride, dichloromethane, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, perchlorethylene, and chlorofluorocarbons. Examples thereof include fluorinated solvents such as 112, chlorofluorocarbon 113 and other chlorofluorocarbon-based mixed solvents, benzene, toluene, methanol, ethanol, isopropyl alcohol, petroleum hydrocarbons and the like, and mixtures thereof. Chlorinated hydrocarbons are excellent in degreasing ability, incombustibility, quick drying, etc., but have the problem that the diffused vapor destroys the ozone layer. Therefore, it is desired to recover the organic solvent from the washing waste liquid. In addition, other than chlorinated hydrocarbons, when using a chlorofluorocarbon or a hydrocarbon-based solvent containing hydrogen, which is called next-generation fluorocarbon, as a cleaning solution, it is needless to say that its recovery is desirable from the viewpoint of reducing industrial waste. There is no. Conventionally, when recovering an organic solvent from such a washing waste liquid, a large-scale recovery apparatus having a distillation column is usually employed, but there are technical and economic problems in terms of equipment, transportation, installation place, and the like. .

[0003]

SUMMARY OF THE INVENTION The present invention provides a simple and economical method and apparatus capable of effectively and efficiently recovering a solvent from a waste solvent, particularly a solvent waste liquid discharged from an electrophotographic photosensitive member manufacturing apparatus. The task is to provide.

[0004]

A first aspect of the present invention is a method for recovering an organic solvent from a waste liquid containing an organic solvent incompatible with water, wherein the waste liquid is stored in a container and the waste liquid is recovered. A step of vaporizing the solvent by controlling the temperature to a predetermined temperature range, a step of adsorbing the vaporized solvent to an adsorbent, and a step of desorbing the solvent vapor by directly contacting the adsorbent adsorbing the solvent vapor with steam to obtain a desorbed gas. A method of condensing the desorbed gas to obtain a mixture of a liquefied solvent and water, and a step of separating the solvent from the mixture.

A second invention is the method according to the first invention, wherein the temperature of the waste liquid in the container is controlled by a band heater provided on an outer peripheral portion of the container.

A third invention is the method according to the first or second invention, wherein the adsorbent is an activated carbon fiber filter.

A fourth invention is the method according to any one of the first to third inventions, wherein the organic solvent is a hydrocarbon having at least one halogen atom.

A fifth invention is the method according to any one of the first to fourth inventions, wherein the waste liquid is discharged from an electrophotographic photosensitive member manufacturing process.

A sixth aspect of the present invention is an apparatus for recovering an organic solvent from a waste liquid containing an organic solvent incompatible with water, comprising: a container for storing the waste liquid; A heater for controlling the range to evaporate the solvent, an adsorption zone connected to the container and having an adsorbent for adsorbing the vaporized solvent in the container, and an adsorption zone connected to the adsorption zone, and A steam introduction pipe for introducing steam for desorbing steam, a condenser connected to the adsorption zone, for condensing desorbed gas from the adsorption zone, and a liquefied solvent from the condenser connected to the condenser. An organic solvent recovery device comprising a separation zone for separating the solvent from a mixture with water.

A seventh aspect of the present invention is the apparatus according to the sixth aspect, wherein the heater comprises a band heater provided on an outer peripheral portion of the container.

An eighth invention is the apparatus according to the sixth or seventh invention, wherein the adsorbent is an activated carbon fiber filter.

In a ninth aspect of the present invention, the adsorbing zone comprises at least two adsorbents arranged in parallel and switching valves provided upstream and downstream of each adsorbent, and the adsorption and desorption of the solvent are continuously performed. An apparatus according to any one of the sixth to eighth aspects, characterized in that:

A tenth invention is characterized in that a decompression suction pipe is provided which is connected to the adsorption zone and sucks a vaporized solvent in the container and adsorbs the solvent on the adsorbent. It is any apparatus of the invention.

An eleventh invention is characterized in that a flow control damper is provided between the container and the adsorption zone and controls a flow rate of the vaporized solvent from the container to the adsorption zone. An apparatus according to the tenth aspect.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows an apparatus suitably used for carrying out a method for recovering a solvent from a waste liquid according to the present invention. In the drawing, reference numeral 1 denotes a waste liquid storage container; Band heater, 4 is a flow control damper, 5a and 5b are adsorption zones, 6a and 6b are adsorbents, 7 is a condenser, and 8 is a separation zone.

The waste liquid storage container 1 stores a waste liquid 2 containing an organic solvent. The waste liquid 2 may be any waste liquid containing an organic solvent incompatible with water according to the present invention. Can be used for any purpose. A waste liquid discharged from a manufacturing process of an electrophotographic photosensitive member used for an image forming apparatus such as a copying machine, a facsimile, and a printer, particularly a waste liquid discharged from a washing process of a metal conductor of the electrophotographic photosensitive member is preferably used. Examples of water-insoluble organic solvents include, for example, chlorinated solvents such as methylene chloride, ethylene chloride, dichloromethane, carbon tetrachloride, 1,1,1-trichloroethane, trichlorethylene, perchlorethylene, and Freon-112. Fluorinated solvents such as Freon 113 and other Freon-based mixed solvents, benzene,
Examples thereof include aromatic hydrocarbons such as toluene, and chlorofluorocarbons containing hydrogen. Boiling point 35 ° C ~ 1
Organic solvents at 25 ° C., in particular hydrocarbons having at least one halogen atom, are preferred.

The waste liquid storage container 1 is provided with a heater 3 for controlling the waste liquid in the container 1 to a predetermined temperature range to vaporize the solvent in the waste liquid. The heater 3 is composed of a band heater directly mounted on the outer peripheral portion of the container 1, and a connection wire between an appropriate temperature controller and a power supply (not shown).

The upper part of the container 1 is connected to an adsorption zone having an adsorbent for adsorbing the solvent vaporized in the container 1. In the example shown in the figure, a pair of adsorption zones 5a and 5b in which the adsorbents 6a and 6b are loaded are provided, and the switching valves V1a and V1b, the line 12,
It is connected to the upper part of the container 1 via the damper 4 and the line 11. The damper 4 is moved from the container 1 to the adsorption zone 5
The flow rate of the vaporized solvent to a and 5b is controlled automatically or manually.

Each of the adsorption zones 5a and 5b is provided with a switching valve V
Via 2a and V2b, it is connected to a reduced-pressure suction line 13 connected to a not-shown reduced-pressure pump and the like. Therefore,
By appropriately controlling the switching valves V1a, V1b, V2a, V2b, the solvent gas vaporized in the vessel 1 is introduced into desired adsorption zones 5a, 5b, and the adsorbents 6a, 6b
Can be adsorbed. Note that the solvent gas vaporized in the container 1 usually exists as a part of mist and
a and 5b, and are absorbed. As the adsorbent, any substance can be used as long as it can adsorb the vaporized solvent vapor, but an activated carbon carbon fiber filter is preferably used in terms of adsorption performance and cost.

Steam is introduced into each of the adsorption zones 5a and 5b through the switching valves V3a and V3b and the steam introduction pipe line 14 so that the solvent vapor is desorbed from the adsorbents 6a and 6b. In addition, the adsorption zones 5a, 5a
b is connected to the condenser 7 via the switching valves V4a, V4b and the line 15. Accordingly, the desorbed solvent gas and steam from the adsorption zones 5a and 5b are condensed in the condenser 7 to generate a mixed liquid.

Downstream of the condenser 7, a separation zone 8 for separating the solvent from the liquid mixture of the liquefied solvent and water from the condenser is provided via a line 16. Since the solvent is incompatible with water, the separation zone 8 may be a stationary vessel. That is, the mixture naturally separates into an aqueous phase 9 and a solvent phase 10 by standing.

In the above example, two adsorption zones are provided.
The number of adsorption zones may be one or three or more. By providing two or more adsorption zones and appropriately providing a switching valve, adsorption and desorption can be performed continuously and efficiently.

The recovery of the organic solvent from the waste liquid containing the water-insoluble organic solvent by the above-mentioned solvent recovery apparatus is performed as follows. The waste liquid is stored in a container, and the solvent is vaporized by controlling the waste liquid in a predetermined temperature range, for example, 0 to 200 ° C. Valves V1a, V1b, V2a, V2
b, V3a, V3b, V4a, and V4b are operated as shown in the table below to cause the solvent vaporized in the container 1 to be adsorbed on the adsorbent (adsorption step), and the adsorbent adsorbing the solvent vapor is steamed. A step of desorbing a solvent vapor by directly contacting with a solvent to obtain a desorbed gas (desorption step);
A step of condensing the desorbed gas to obtain a mixture of a liquefied solvent and water (condensing step) and a step of separating the solvent from the mixture (separating step) can be continuously performed. That is,
In the illustrated example, the two adsorption zones 5a and 5b are
And by alternately setting the state to II, adsorption and desorption are continuously performed, and solvent recovery from waste liquid is continuously performed. In Table 1,-indicates that the valve is closed, and + indicates that the valve is open.

[0024]

[Table 1]

[0025]

Next, the present invention will be further described with reference to examples.

Example 1 Before dipping and coating an electrophotographic photosensitive member coating solution on a drum-shaped conductive substrate formed of an aluminum alloy, the conductive substrate was washed with dichloromethane. This washing waste liquid was stored in a metal container. A band heater was attached to the outer periphery of the container, and the waste liquid was kept in a range of 30 to 50 ° C. by a temperature controller connected to the band heater. The upper part of the vessel is filled with an activated carbon carbon fiber filter (100 kg).
It was connected to an adsorption tower having a length of 1,700 mm and a length of 2500 mm via an air volume control damper. The suction tower is suctioned under reduced pressure, the air volume control damper is operated, and suction is performed at a flow rate of 3 to 20 m / min.
The solvent vapor generated in the container was absorbed by a filter. Next, steam was introduced into the adsorption tower to desorb the adsorption solvent vapor, which was supplied to a condenser (refrigerant: water at 7 ° C.) to condense. By allowing the condensed mixture to stand still, 150 kg
130 kg or more of dichloromethane was recovered from the washing waste liquid of the above.

[0027]

According to the present invention, a solvent can be recovered from a waste liquid discharged from the electrophotographic photoreceptor used in an image forming apparatus such as a copying machine, a facsimile, a printer, etc., and recycled to the process as it is. .

[Brief description of the drawings]

FIG. 1 is a flowchart showing an outline of an example of an apparatus of the present invention suitably used for carrying out a method for recovering a solvent from a waste liquid.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waste liquid storage container 2 Solvent waste liquid 3 Band heater 4 Flow rate adjustment damper 5a, 5b Adsorption zone 6a, 6b Adsorption material 7 Condenser 8 Separation zone 9 Water phase 10 Solvent phase 11, 12, 13, 14, 15, 16 Connection line V1a, V2a, V3a, V4a switching valve V1b, V2b, V3b, V4b switching valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/04 C02F 1/04 D 4G066 G03G 5/00 101 G03G 5/00 101 5/10 5/10 B F-term (reference) 2H068 EA14 4D012 CA11 CB16 CD02 CE01 CF02 CF10 CG01 CG04 CH10 CJ10 CK10 4D020 AA08 CA05 4D034 AA20 CA12 CA21 4D076 AA12 BA01 BC01 BC11 CD22 DA22 EA08Y EA12Y EA16 CA31 DA03 JA03 CA03 DA03

Claims (11)

[Claims] 1. A method for recovering an organic solvent from a waste liquid containing an organic solvent that is incompatible with water, comprising: storing the waste liquid in a container and controlling the waste liquid to a predetermined temperature range to remove the solvent. Vaporizing, adsorbing the vaporized solvent onto the adsorbent, bringing the adsorbent, which has adsorbed the solvent vapor, into direct contact with steam to desorb the solvent vapor to obtain a desorbed gas, and condensing and liquefying the desorbed gas. A method for recovering an organic solvent, comprising: a step of obtaining a mixture of a solvent and water; and a step of separating the solvent from the mixture. 2. The method according to claim 1, wherein the temperature of the waste liquid in the container is controlled by a band heater provided on an outer peripheral portion of the container. 3. The method according to claim 1, wherein the adsorbent is an activated carbon fiber filter. 4. The method according to claim 1, wherein the organic solvent is a hydrocarbon having at least one halogen atom. 5. The method according to claim 1, wherein the waste liquid is discharged from an electrophotographic photosensitive member manufacturing process.
5. The method according to any one of 4. 6. An apparatus for recovering an organic solvent from a waste liquid containing an organic solvent incompatible with water, comprising: a container for storing the waste liquid; and controlling the waste liquid in the container to a predetermined temperature range. A heater for evaporating the solvent, an adsorption zone connected to the container and having an adsorbent for adsorbing the vaporized solvent in the container, and a desorption of solvent vapor from the adsorbent connected to the adsorption zone. A steam introduction pipe for introducing steam, a condenser connected to the adsorption zone for condensing desorbed gas from the adsorption zone, and a mixture of liquefied solvent and water from the condenser connected to the condenser A recovery zone for separating the solvent from the organic solvent. 7. The apparatus according to claim 6, wherein said heater comprises a band heater provided on an outer peripheral portion of said container. 8. The apparatus according to claim 6, wherein the adsorbent is an activated carbon fiber filter. 9. The adsorption zone comprises at least two parallel adsorbents and switching valves provided upstream and downstream of each adsorbent, and continuously adsorbs and desorbs the solvent. Item 10. The apparatus according to any one of Items 6 to 8. 10. A vacuum suction pipe connected to the adsorption zone and provided for sucking a solvent vaporized in the container and adsorbing the solvent on the adsorbent. Equipment. 11. A flow rate adjusting damper provided between said container and said adsorption zone, for controlling a flow rate of said vaporized solvent from said container to said adsorption zone. The described device.