JP2003311103A - Solvent regeneration method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solvent regeneration method for regenerating a cleaning waste liquid or the like from which a harmful substance or the like is removed. <P>SOLUTION: A mixing tank 16 for mixing a contaminated cleaning solvent 14 containing a harmful substance 12 by cleaning treatment with dimethyl sulfoxide (DMSO) 15 is provided and, after the mixed solvent 17 is allowed to stand after mixing, the solvent layer of the upper layer 18 is separated from the DMSO layer being a lower layer 19 and the solvent of the upper layer 18 is reutilized as a washing solvent 13. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning solvent regenerating method for regenerating a cleaning waste liquid or the like from which harmful substances and the like adhering to an object to be treated are removed.

[0002]

2. Description of the Related Art In recent years, PCB (Polychlorinated bi
phenyl, polychlorinated biphenyl: a generic term for chlorinated isomers of biphenyl) is highly toxic and its manufacture and import are prohibited. Although this PCB was first manufactured in Japan around 1954, its adverse effects on the living body and environment became clear after the Kanemi Yusho incident.
In 2 years, there was a history of instructions to discontinue production and collection (duty of storage) by administrative guidance.

PCB has 1 to 1 chlorine in the biphenyl skeleton.
It has 0 substitutions, and theoretically there are 209 kinds of isomers depending on the number and position of the substituted chlorine.
About 100 or more isomers have been confirmed in CB products. In addition, the physical and chemical properties among these isomers, the in vivo stability, and the environmental dynamics are so diverse that the chemical analysis of PCB and the mode of environmental pollution are complicated at present. Further, PCB is one of the persistent organic pollutants, is not easily decomposed in the environment, is fat-soluble, has a high bioconcentration rate, and is semi-volatile, and is capable of being transferred through the atmosphere. In addition, it has been reported that it widely remains in the environment such as water and living things.

This PCB was an abandoned PC in 1997.
B, waste oil containing PCB, and PCB pollutants are designated as specially controlled wastes based on the law on waste treatment and cleaning. In addition, wood chips and fiber scraps were added as PCB pollutants in 1997. Designated.

There are high-voltage transformers, high-voltage capacitors, low-voltage transformers / capacitors, pole transformers as electric equipment to be treated with PCBs, and as waste PCBs, those used as a heat medium used as insulating oil, In addition, there are kerosene and the like used for cleaning these, and as the pressure-sensitive waste paper, there is capsule oil used for carbonless paper, and further, use of these PCBs or replacement of heat medium, regeneration of insulating oil, leakage. There are PCB pollutants such as activated carbon used in the purification of the above, the treatment of PCB-containing substances, waste white clay, waste waste, work clothes and the like. Currently, these are strictly stored, but urgent PCB treatment is desired.

In recent years, various cleaning treatment techniques have been proposed as techniques for treating the PCB used in such transformers.

That is, in the present situation, P of a transformer or the like is
In the treatment of CB contaminants, insulators, iron cores, copper wires, aluminum foil, etc., which have been disassembled and cut after the PCB oil has been removed, are used as cleaning agents, for example, in organic solvents such as hexane, acetone, or strong sodium hydroxide. The mainstream is to wash with an alkali.

However, when an organic solvent is used among these cleaning solvents, the property after use is a mixture of PCB, insulating oil and paint. In this case, each organic solvent reduces the concentration of contaminants such as PCB to the extent that it can be used as a cleaning liquid regenerated by distillation means.

Therefore, there is a problem that the distillation apparatus requires a large number of distillation stages (the number of washing stages is about 10 to 15), and the cost and operating cost of the distillation equipment increase. In particular,
When using a large amount of cleaning solvent, it is urgently necessary to reduce the cost of the distillation equipment. Further, when the number of distillation stages is high, the distillation equipment becomes large in size, and there is a problem of installation space.

In view of the above, an object of the present invention is to provide a solvent regeneration method capable of removing harmful substances such as PCB and regenerating as a cleaning solvent without distilling the solvent.

[0011]

A first invention for solving the above-mentioned problems is a solvent regeneration method for regenerating a cleaning solvent in which harmful substances adhering to an object to be treated are washed, and containing a harmful substance. Washing solvent and dimethyl sulfoxide (DMS
O) is mixed and allowed to stand, and then the solvent layer is separated.

In a second aspect of the invention, in the first aspect, the washing solvent is an organic solvent such as benzene, toluene, xylene, acetone, normal-hexane, iso-octane, trichloroethylene, tetrachloroethylene, C8.
The solvent regeneration method is characterized in that it is at least one of hydrocarbon solvents of Nos. 15 to 15.

A third aspect of the present invention is the solvent regeneration method according to the first aspect, wherein the harmful substance is at least one of PCB, waste paint, waste fuel, and harmful chemicals.

[0014]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments.

[First Embodiment] An embodiment of a cleaning solvent regeneration method according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a cleaning device.

As shown in FIG. 1, the cleaning / regenerating apparatus according to the present embodiment is a solvent regenerating apparatus for regenerating a cleaning solvent 13 which has cleaned harmful substances 12 adhering to an object 11 to be treated. The mixing tank 16 for mixing the contaminated cleaning solvent 14 containing the harmful substance 12 with the dimethyl sulfoxide (DMSO) 15 is provided, and after mixing, the mixed solvent 1
7 was allowed to stand, and then the solvent layer of the upper layer 18 was replaced with the DMS of the lower layer 19.
The O layer is separated, and the solvent of the upper layer 18 is reused as the cleaning solvent 13 again.

In the mixing tank 16, the solvent and DMSO are mixed and stirred by the stirring means 20 or the like, so that the dimethyl sulfoxide (DMSO) dissolves the PCB oil contained in the contaminated cleaning solvent 14 and the dimethyl sulfoxide ( By moving to the DMSO side, harmful substances are removed from the contaminated cleaning solvent 14. As a result, the concentration of harmful substances in the contaminated cleaning solvent 14 is reduced, and the regeneration processing of the contaminated cleaning solvent 14 is completed.

Dimethyl sulfoxide (DMSO) has a structure shown in the following "Chemical formula 1", has a high polarity and functions as an aprotic solvent having a large dissolving power, and therefore has a high affinity with harmful substances in the contaminated detergent 14. This is because it has a property and can exhibit high solubility.

[0019]

[Chemical 1]

Therefore, it is possible to remove harmful substances from organic solvents such as hexane and toluene.

Further, dimethyl sulfoxide (DMS
Since O) has a high boiling point (189 ° C.), it has a small amount of solvent volatilization and is easy to handle.

The process of regenerating the cleaning liquid after cleaning the transformer containing PCB as the object to be processed will be described below.

<PCB Processing Method> A case where the cleaning solvent regenerating apparatus as described above is incorporated in, for example, a PCB processing system to detoxify the capacitor 20 will be described below with reference to FIG.

First, as shown in FIG.
PCB oil of Densa 30 is removed (S101) and attached
PCB level 50g / m²From 10 to 100mg
/ M ²Because it has low environmental toxicity,
Non-flammable long-chain aliphatic hydrocarbons (eg NS-1
00 or kerosene) as the cleaning solvent 13
And rough cleaning is performed (S102). This rough cleaning is
Finish cleaning process by reducing the inflow of PCB into the top cleaning process
By keeping the PCB contamination level of equipment used in
This is to prevent deterioration of cleaning performance. Then, rough cleaning
The disassembled capacitor 30 is used to disassemble organic matter such as paper and wood.
2, element 33, and metal 34 and insulator 35 other than these
And the like are separated into inorganic substances and the like (S103). This capacitor
The elements are generally aluminum foil electrodes, plastic
It has a structure in which a laminate of film and insulating paper is wound.

Next, the separated elements 33 are heated and carbonized (S104). Carbonization by heating is performed in vacuum or Ar, N ₂
The temperature is 200 ~.
It is preferable to set the temperature to about 600 ° C. and the heating time to about 3 to 12 hours. By heating and carbonizing the element 21 in this manner, it is possible to remove the PCB or reduce the concentration thereof, and it is also possible to embrittle the organic substances such as the plastics film and the insulating paper, thereby decomposing and separating the element 33. Make it easier.

The element 33 thus heated and carbonized is
It is separated into an organic substance (embrittlement) such as a piece of paper and an aluminum foil (S106).

Then, the organic substances separated from the element 33 and other organic substances such as paper and film generated at the time of disassembling are finely pulverized by a fine pulverizing mill to be slurried (S1).
07). On the other hand, the aluminum foil separated from the element 33 and other metals generated during disassembly and inorganic substances such as insulators are
It is cleaned by a cleaning device and then discarded or reused (S
108).

Then, the slurried organic matter is hydrothermally decomposed together with the extracted insulating oil to become NaCl, CO ₂ and H ₂ O, and discharged (S109). As a result, the capacitor 20 including the PCB can be safely and reliably processed.

The cleaning waste liquid 14 from the above-mentioned rough cleaning (S102) and finish cleaning (S108) can be reused as the cleaning solvent 13 by regenerating the solvent using dimethyl sulfoxide (DMSO) (S110).

In such a PCB processing system, among the constituent materials of electric power equipment such as capacitors, organic waste such as paper and wood contaminated by PCB is separated and taken out from the other constituent materials, and this organic waste is disposed. Since the material is hydrothermally decomposed, it is possible to safely and surely treat the PCB including the organic matter.

At this time, since the organic waste such as paper and wood is slurried and the slurried organic waste is hydrothermally decomposed, the PCB should be treated safely and reliably and continuously. You can

In addition, among the constituent materials of electric power equipment such as capacitors, inorganic waste such as metal and insulator contaminated by PCB is separated from other constituent materials and taken out, and after cleaning with a cleaning agent, the cleaning agent is removed. Since it is hydrothermally decomposed, PC
The cleaning agent contaminated with B can be safely and surely rendered harmless.

FIG. 3 shows a detailed process of regenerating the cleaning solvent in the cleaning solvent regeneration process (S110). First, P
Contaminated cleaning solvent contaminated with CB (C10 hydrocarbon solvent)
Dimethyl sulfoxide (DMSO) was added to 14
Mix and extract PCB to the dimethylsulfoxide (DMSO) side (S201). Mixing is performed by stirring or ultrasonic vibration means.

Next, it is left to stand until completely separated (S2
02). Then, the cleaning solvent of the upper layer 18 is separated from the dimethyl sulfoxide (DMSO) layer of the lower layer 19 (S20).
3). The recycled cleaning solvent is reused for cleaning the container and the like. On the other hand, dimethyl sulfoxide (DMSO) containing PCB is used in the hydrothermal oxidative decomposition treatment device 120 described later.
(See FIG. 5) and disassembled together with PCB.

Further, by adding a large amount of water to dimethylsulfoxide (DMSO) containing PCB, it is hydrolyzed as shown in the following "Chemical formula 2" to dissolve the PCB in water, and the PCB is dissolved. Water is decomposed in the hydrothermal oxidative decomposition treatment device and other treatment devices described later,
The cleaning liquid can be easily treated.

This is dimethyl sulfoxide (DMS
Since the polarity of water is larger than that of O), the PCB will be transferred into water. Since the solubility of PCB in water is 400 ppb, it is necessary to hydrolyze it with a large amount of water.

[0037]

[Chemical 2]

Therefore, according to the present embodiment, it is possible to easily wash and remove the PCB even if it is the object to be treated 1 in which the PCB has entered and adsorbed in the minute gaps on the surface.

Further, since sodium sulfate (Na ₂ SO ₄ ) which is a hydrolyzate is not corrosive, deterioration of the treatment equipment due to corrosion does not occur.

<Toxic Substance Treatment System> Further, the cleaning and recycling apparatus 10 can be used more effectively by incorporating it into a hazardous substance treatment system as shown in FIG.

As shown in FIG. 4, the harmful substance treatment system is a harmful substance treatment system for detoxifying an object to be treated on which harmful substances are attached, contained or stored. Etc.) 1001 is a first separating means 1004 for separating the harmful substance 1002 from a container 1003 for storing the harmful substance (eg PCB) 1002 and the constituent materials 1001a, b, ... Pretreatment means having one or both of the disassembling means 1005
1006 and constituent materials (core, capacitor element portion, etc.) 1001a constituting the object processed by the pretreatment means 1006,
Second separation means 1009 for separating organic matter 1007 such as paper, wood, resin, etc. and inorganic matter 1008 such as metal from b, ..., Metal container 1003 separated by the pretreatment means 1006, or the separation means 1009 The cleaning means 1011 for cleaning the inorganic substance 1008 such as the metal separated by the cleaning solution 1010, the cleaning waste liquid 1012 after cleaning, and the harmful substance 1001 separated by the pretreatment means. 1013 and are provided.

In such a harmful substance treatment system, the cleaning solvent regeneration device 10 is used as the cleaning means 1011.

According to such a harmful substance treatment system, the PCB concentration of the transformer, the condenser, etc.
The emission standard value of CB (3 ppb) or less can be reduced to 0.5 ppb or less, and the transformer 10 including the PCB, the capacitor 20, and the like can be safely and reliably processed. Therefore, the PCB-containing article can be completely processed, and the PCB can be completely extinguished.

Since organic compounds other than PCB can also be treated, dioxins contained in PCB, organic substances such as paper, wood, cloth, etc. contaminated by PCB, and cleaning agents used for cleaning the case are also used. It can be decomposed similarly.

FIG. 5 shows a PCB hydrothermal decomposition treatment system 1.
It is a block diagram of 20.

As shown in FIG. 5, the cylindrical primary reactor 1
22 and oil 123a for combustion, drained PCB123
b, sodium hydroxide (NaOH) 123c and water 12
Pressurizing pumps 124a to 124d for pressurizing 3d respectively,
Preheater 12 for preheating a mixed solution of water and sodium hydroxide
5, and a secondary reactor 126 having a structure in which piping is wound, for example,
The cooler 127 and the pressure reducing valve 128 are provided. Also,
A steam separator 129 and an activated carbon tank 130 are arranged downstream of the pressure reducing valve 127, and exhaust gas (CO ₂ ) 131 is discharged from a chimney 132 to the outside, and waste water (H ₂ O, NaC) is discharged.
l) 133 is separately treated as waste water as required. The oxygen pipe 135 is directly connected to the primary reactor 125. As for the reactor, for example, a plurality of primary reactors may be arranged in parallel, or the secondary reactor 126 may be omitted as necessary.

In the above apparatus, the pressure pumps 124a ...
The pressure in the primary reactor 122 is 26
The pressure is increased to MPa. Further, the preheater 125 uses water and N
The mixed treatment solution of aOH is preheated to about 300 ° C. Also,
Oxygen is ejected into the primary reactor 122,
Heat up to 380 ℃ -400 ℃ subcritical range
It Sodium carbonate precipitated in this subcritical hot water
(Na₂CO₃) Crystal reacts with PCB, dechlorination reaction
Reaction and oxidative decomposition reaction, resulting in NaCl, CO ₂And
And H₂It is decomposed into O. Next, in the cooler 127
Cools the fluid from the secondary reactor 126 to about 100 ° C.
At the same time, the pressure is reduced to atmospheric pressure by the pressure reducing valve 128 in the subsequent stage.
It Then, by the steam separator 129, CO₂And water vapor
CO and treated water are separated, CO₂And steam is active
It passes through the charcoal tank 130 and is discharged into the environment. Also drain
Sodium chloride is mixed in 133, but separate
After salt treatment, re-use the water 28 used in the hydrothermal decomposition device.
Can be used.

Here, the primary reaction vessel 122 which is a reaction tower
The hydrothermal decomposition reaction of PCB in the secondary reactor 122 will be described.

First, at the start of the reaction, oil, organic solvent, etc. are acidified.
The oxidant supplied from the agent supply source into the tower (in the present embodiment,
Uses oxygen) to produce carbon dioxide
It For example, use oil (such as toluene) as a combustion material.
For example, if you use ₆H_FiveCH₃+ 9O₂→ 4
H₂O + 7CO₂Due to the reaction of₂Is generated. this
The oxidation reaction is an exothermic reaction, which increases the temperature inside the system.
Rises and the pressure rises accordingly. In this embodiment,
The temperature and pressure inside the primary reaction vessel 122 are 380 and 380, respectively.
Decomposition of PCB most when maintained at ℃ and 26MPa
The rate has been found to improve.

The CO ₂ produced as described above reacts with sodium hydroxide supplied together with PCB in the primary reaction vessel 122 to produce sodium carbonate (Na ₂ CO ₃ ). 2NaOH + CO ₂ → Na ₂ CO ₃ + H ₂ O (A) Next, Na ₂ CO produced by the reaction of the above (A)
₃ reacts with PCB, desalting and oxidatively decomposing PCB. C ₁₂ H ₆ Cl ₄ + 12.5O ₂ + 2Na ₂ CO ₃ → 4NaCl + 3H ₂ O + 14CO ₂ (B) In the case of the above-mentioned PCB having a chlorine number of 4, the same reaction is obtained for other chlorine numbers. Occurs, PCB is H ₂
It is decomposed into O, CO ₂ , and NaCl. The CO ₂ generated by the above reaction (B) is further converted into N ₂ by the above reaction (A).
Na ₂ CO that reacts with aOH and is required for the reaction of (B)
_Will generate ₃ . By the way, the above (B) PC
In the B decomposition reaction, sodium carbonate (Na ₂ C
O ₃ ) acts not only as a reaction agent but also as a catalyst for promoting the decomposition reaction of (B). Further, it has been found that the decomposition reaction of the above (B) is promoted in an alkaline atmosphere (for example, pH 10 or higher).

According to the hot water decomposing device 120, it is possible to decompose to 0.5 ppb or less, which is less than the current PCB discharge standard value (3 ppb), and complete decomposition is possible. This allows PCB
It becomes possible to completely treat the contained article and completely eliminate the PCB.

As described above, the hydrothermal decomposition system 120
By using, it becomes possible to surely decompose the PCB in hot water. In addition, organic compounds other than PCB can also be decomposed, and dioxins contained in PCB, organic substances such as paper, wood, cloth, etc. contaminated by PCB, and cleaning agents used for cleaning the case can also be decomposed. It will be possible. The above hydrothermal decomposition method has already been disclosed by the applicant of the present application, and for details, refer to JP-A Nos. 11-639 and 11-253795. According to the PCB processing method described above, it is possible to safely and reliably process a transformer or the like including a PCB.

[Other Embodiments] <Other Cleaning Devices> In addition to the cleaning devices of the above-described embodiments, for example, the object 1 to be processed can be cleaned in a CO ₂ supercritical fluid. is there.

<Toxic substance> In addition to the above-mentioned PCB, examples of the harmful substance which can be treated in the present invention include waste paint, waste fuel, harmful chemicals, untreated explosives and the like. However, the present invention is not limited to these, and any harmful substance such as an environmental hormone caused by environmental pollution can be treated in the same manner.

[0055]

As described above, a method of regenerating a cleaning solvent in which harmful substances adhering to an object to be treated are cleaned, wherein a cleaning solvent containing harmful substances and dimethyl sulfoxide (DMSO) are used. After mixing and standing, the solvent layer is separated, so it is possible to regenerate the cleaning solvent contaminated with harmful substances with the dimethylsulfoxide (DMSO) cleaning liquid by a simple method, and the conventional large-scale distillation equipment can be used. It is not necessary and the system can be simplified.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a cleaning / regenerating apparatus according to the present embodiment.

FIG. 2 is a process diagram of a PCB contaminated capacitor according to the present embodiment.

FIG. 3 is a process diagram of a recycling process of a contaminated solvent according to the present embodiment.

FIG. 4 is an overall configuration diagram of a hazardous substance processing system according to the present embodiment.

FIG. 5 is a configuration diagram of a hydrothermal oxidative decomposition treatment apparatus according to the present embodiment.

[Explanation of symbols]

11 Processing object 12 Hazardous substances 13 Cleaning solvent 14 Contamination washing solvent 15 Dimethyl sulfoxide (DMSO) 16 mixing tank 17 Mixed solvent 18 upper layers 19 Lower layer 30 capacitors 31 PCB 32 organic matter 33 elements 34 metal 35 insulator 1002 Hazardous substances (eg PCB) 1003 containers 1004 Separation means 1005 Dismantling method 1006 Pretreatment means 1007 organic matter 1008 inorganic 1009 Separation means 1010 cleaning solution 1011 Cleaning means 1012 Wash waste liquid 1013 Hazardous substance decomposition processing means 1014 slurry 1015 Slurrying means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinori Fukunaga             Nagasaki Prefecture Nagasaki City Fukahori Town 5 chome 717 1             Ryo Engineering Co., Ltd. (72) Inventor Soichiro Masaki             Nagasaki Prefecture Nagasaki City Fukahori Town 5 chome 717 1             Ryo Engineering Co., Ltd. F-term (reference) 4D056 AB11 AB17 AB18 AC13 BA04                       CA39

Claims (3)

[Claims] 1. A solvent regeneration method for regenerating a cleaning solvent in which harmful substances adhering to an object to be treated are washed, wherein a cleaning solvent containing harmful substances and dimethyl sulfoxide (DMSO) are mixed and allowed to stand. And a solvent regeneration method comprising separating the solvent layer. 2. The cleaning solvent according to claim 1, wherein the cleaning solvent is, for example, benzene, toluene, xylene,
Organic solvents such as acetone, normal-hexane, iso-octane, trichloroethylene, tetrachloroethylene,
A solvent regeneration method, which is at least one of C8 to C15 hydrocarbon solvents. 3. The solvent regeneration method according to claim 1, wherein the harmful substance is at least one of PCB, waste paint, waste fuel, and harmful chemicals.