JP2010259681A - Method and apparatus for detoxification treatment of pcb-containing oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detoxification treatment of PCB-containing oil which detoxifies PCB on mild operating conditions and obtains a high detoxification ratio of the PCB using a small amount of chemical. <P>SOLUTION: The PCB-containing oil, ethanol, isopropanol, and metal calcium are continuously supplied to a treatment tank 41 by supply devices 11, 13, 15, and 17, respectively. In the treatment tank 41, they are agitated and mixed at 60°C using an agitator 45 and the PCB-containing oil and a solvent are rendered compatible, so that the PCB is detoxified while the PCB-containing oil and the solvent are rendered compatible. Thus, a high detoxification ratio of the PCB is achieved with a small amount of the solvent. The matter having been detoxified in the treatment tank 41 is cooled down to 20-30°C by a cooler 53 and thereafter sent to a phase separation tank 55. In the phase separation tank 55, the treated matter is left at rest to phase-separate into a solvent phase and an oil phase. Thus, a treated oil and the solvent are simply recovered. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a detoxification treatment method for PCB-containing oil such as insulating oil containing PCB, and a detoxification treatment apparatus for PCB-containing oil.

  PCB (polychlorinated biphenyl) is nonflammable and excellent in chemical stability and electrical insulation, so it was conventionally used as an insulating oil for electrical equipment, but its use is now prohibited and stored due to its harmfulness. PCBs and waste oils containing PCBs are also required to be detoxified.

  Many methods have been developed and disclosed for PCB detoxification technology. For example, as a dechlorination decomposition treatment method, an alkali catalytic decomposition method using KOH to detoxify insulating oil containing low concentration PCB, or a chemical extraction decomposition using NaOH to detoxify insulating oil containing low concentration PCB And metal sodium-dispersed oil dechlorination method that uses metal sodium to render the insulating oil containing low-concentration PCBs harmless. Further, as a method of detoxifying PCB by hydrothermal oxidative decomposition, there is a supercritical hydrolytic decomposition method in which insulating oil containing high-concentration PCB is detoxified using supercritical water (for example, see Non-Patent Document 1). . In addition, many methods other than the detoxification treatment method have been proposed as detoxification treatment methods for organic halogen compounds such as PCBs and dioxins.

  However, it has been pointed out that conventional methods for detoxifying PCBs or dioxins need to be performed under high-temperature or high-pressure conditions, require large-scale equipment, and are complicated in operation. It is hard to say that it is an easy method. On the other hand, as a method of detoxifying waste oil containing low-concentration PCBs with a simple device in a safe and simple operation, PCBs are separated and concentrated from waste oil when chemically treating waste oil containing low-concentration PCBs. Then, a method of dechlorinating PCB has been proposed (see, for example, Patent Document 1). The present inventors have also established a treatment method capable of detoxifying organic halogen compounds including dioxins under simple operation conditions compared to conventional detoxification treatment methods, and have obtained patents (for example, patent documents). 2 (for example, see Patent Document 3).

JP 2006-223345 A Japanese Patent No. 3533389 Japanese Patent No. 3785556

Industrial Waste Treatment Business Foundation, “PCB Technology Guidebook (Revised) Based on New Waste Treatment Law New Treatment Standards”, Gyosei Corporation, 2005, P478-P519

  The method described in Patent Document 1 is a method in which PCB is dechlorinated after separating and concentrating PCB from waste oil when chemically treating waste oil containing low-concentration PCB. Many processes are required before the chemical conversion treatment, and it is difficult to say that it is a simple method. The metal calcium catalyst method, which is a detoxification treatment method for organic halogen compounds described in Patent Document 3 developed by the present inventors, is roughly a method of treating an organic halogen compound with metal calcium and a reduction catalyst in ethanol. The operation is a simple method as long as it is carried out at atmospheric pressure or slightly under pressure at room temperature. The same applies to the metallic calcium method that does not contain a reduction catalyst developed by the present inventors. Although it is possible to detoxify waste oil containing low concentrations of PCB using the metal calcium catalyst method and metal calcium method, in order to detoxify waste oil containing PCB at a lower cost, the amount of chemicals used must be reduced. Further improvements such as reduction are necessary.

  An object of the present invention is to provide a detoxification method for PCB-containing oil that can detoxify PCB under mild operating conditions and can obtain a high detoxification rate with a small amount of chemicals used, and a simple apparatus configuration. An object of the present invention is to provide a detoxification treatment apparatus for PCB-containing oil, which can obtain a high detoxification rate.

  The present invention according to claim 1 is a method for removing PCB by mixing PCB-containing oil, a protic solvent, and a metal having at least a part dissolved in the protic solvent and having a reducing power by electron transfer. In the method for detoxifying PCB-containing oil, which is detoxified by halogenation and / or reduction treatment, an auxiliary solvent having affinity for the oil and the protic solvent is added, and the oil and the oil are produced without causing an emulsion. Detoxification of PCB-containing oil, wherein PCB is dehalogenated by dehalogenating and / or reducing treatment in a state where oil is mixed with protic solvent and oil and protic solvent are made compatible It is a processing method.

  The present invention according to claim 2 is characterized in that, in the method for detoxifying PCB-containing oil according to claim 1, the protic solvent is ethanol and the auxiliary solvent is isopropyl alcohol. .

  The present invention according to claim 3 is the detoxification treatment method for PCB-containing oil according to claim 1 or 2, wherein the PCB is dehalogenated and / or reduced under heating, and the heating temperature is an emulsion. It is a temperature at which the oil and the protic solvent can be compatibilized without generating water, and a temperature at which the dissolution rate of the metal in the protic solvent becomes a predetermined rate.

  The present invention according to claim 4 is capable of quantitatively supplying an oil supply apparatus capable of quantitatively supplying an oil containing PCB, a protic solvent, and an auxiliary solvent having affinity for the oil and the protic solvent. A solvent supply device, a metal powder supply device capable of quantitatively supplying metal particles having at least a portion dissolved in the protic solvent and having a reducing power by electron transfer, an oil containing the PCB, and the proton A treatment tank for receiving a neutral solvent, the auxiliary solvent and the metal, mixing them, compatibilizing the oil and the protic solvent without producing an emulsion, and dehalogenating and / or reducing the PCB A detoxifying device for PCB-containing oil, comprising: a stirring means for stirring and mixing the contents of the treatment tank.

  The present invention according to claim 5 is the detoxification treatment apparatus for PCB-containing oil according to claim 4, wherein the protic solvent is further removed from the contents of the treatment tank in which PCB is dehalogenated and / or reduced. Or a solvent recovery device for separating and recovering the protic solvent and the auxiliary solvent.

  By using the method for detoxifying PCB-containing oil of the present invention, PCB can be sufficiently detoxified while using a small amount of chemicals and mild operating conditions. Moreover, the detoxification treatment method for PCB-containing oil of the present invention can detoxify PCB in one step, and the detoxification treatment method is also simple. Furthermore, the PCB-containing oil detoxification apparatus of the present invention has a simple structure and can be manufactured at low cost without requiring special equipment.

1 is a process flow diagram showing a schematic configuration of a PCB-containing oil continuous detoxification treatment apparatus 1 as one embodiment of the present invention.

  The PCB-containing oil detoxification treatment method of the present invention comprises mixing a PCB-containing oil, a protic solvent, and a metal having at least a portion dissolved in the protic solvent and having a reducing power by electron transfer. In a method for detoxifying PCB-containing oils, which is dehalogenated and / or detoxified to detoxify PCBs, an auxiliary solvent having affinity for the oil and the protic solvent is added to the oil and the proticity without causing an emulsion. The PCB is dehalogenated and / or reduced in a state in which the solvent is compatibilized and the oil and the protic solvent are compatibilized to render the PCB harmless. Hereinafter, the method for detoxifying a PCB-containing oil according to the present invention will be described in detail. PCB dehalogenation and / or reduction treatment may be referred to as PCB detoxification treatment, and PCB detoxification and detoxification rate may be referred to as PCB decomposition and decomposition rate. Further, the protic solvent and the auxiliary solvent may be collectively referred to as a solvent. In addition, the suspension refers to a metal salt produced by dissolving a metal having at least a part in a protic solvent and having a reducing power by electron transfer dissolved in the protic solvent, or particles containing the metal salt. Say the liquid.

  Examples of the PCB-containing oil that is the object to be treated include insulating oil for transformers, but the oil is not limited to a specific oil as long as it contains PCB. Further, the concentration of PCB contained in the PCB-containing oil is not limited to a specific concentration. Although it does not exclude the mixing of a small amount of moisture, it is preferable that the PCB-containing oil does not contain moisture. If the PCB-containing oil contains a lot of moisture, a high decomposition rate cannot be obtained.

  The protic solvent is a solvent capable of donating hydrogen ions, and alcohols are exemplified as such a solvent. Alcohols that can be used here are lower alcohols such as methanol, ethanol, propanol, and isopropyl alcohol (isopropanol). Of these, ethanol is preferred. The amount of the protic solvent is preferably large in order to increase the decomposition rate of PCB, but on the other hand, the consumption is increased and the processing cost of the PCB-containing oil is increased. Furthermore, since it is necessary to enlarge the detoxification processing apparatus, it is preferable that the amount of the protic solvent is small. In the method for detoxifying a PCB-containing oil of the present invention, the amount of the protic solvent can be set to ¼ to 1 by volume ratio with respect to the PCB-containing oil.

  The auxiliary solvent is a solvent for compatibilizing the oil and the protic solvent. At this time, by making the oil, the protic solvent, and the auxiliary solvent uniform without generating an emulsion, the PCB decomposition rate is increased and the PCB decomposition rate is increased. Such solvents are generally solvents that have an affinity for both oil and protic solvents. What is necessary is just to select an auxiliary | assistant solvent suitably according to the kind of protic solvent to be used. When ethanol is used as the protic solvent, the auxiliary solvent is preferably isopropanol. Isopropanol functions not only as a compatibilizer for compatibilizing oil and a protic solvent, but also as a protic solvent. Compatibilization of the oil and the protic solvent does not necessarily need to be compatibilized at room temperature, and may be in a heated state. Addition of auxiliary solvent to compatibilize oil and protic solvent is intended to increase the decomposition rate of PCB and increase the decomposition rate, so oil and protic solvent can be compatibilized Needless to say, an auxiliary solvent that inhibits the decomposition of PCB is not preferable even if it is a simple solvent.

  The amount of the auxiliary solvent added is not limited to a specific amount as long as the oil and the protic solvent can be made compatible. However, as the amount of the auxiliary solvent added is increased, the detoxification treatment apparatus is enlarged. Since the necessity arises, it is preferable that the addition amount is small. In the method for detoxifying PCB-containing oil of the present invention, when the combination of the protic solvent and the auxiliary solvent is ethanol and isopropanol, the amount of isopropanol may be set to 1/4 to 1 by volume with respect to ethanol. it can.

  In the method for detoxifying a PCB-containing oil of the present invention, it is not necessary to add a catalyst, but it is preferable that no catalyst is added. In the conventional metal calcium catalyst method, a reduction catalyst such as a rhodium carbon catalyst coexists in the decomposition of dioxins (see Patent Document 3). However, the method for detoxifying a PCB-containing oil according to the present invention is described later. As can be seen from the examples and comparative examples, the decomposition rate of PCB could be increased without adding the reduction catalyst.

  A metal that is at least partially dissolved in a protic solvent and has a reducing power by electron transfer is a substance that can be dissolved in a protic solvent and donate electrons. Such metals are alkali metals, alkaline earth metals such as metallic calcium, Group 3 elements such as aluminum, iron, zinc and alloys containing these elements, among which metallic calcium is preferred. Metallic calcium is a reducing agent that is extremely easy to handle as compared with metallic sodium, because the surface layer is oxidized in air and forms an oxide film, so that internal deterioration is difficult to occur. On the other hand, in the case of calcium metal, in the protic solvent such as ethanol, the oxide film on the surface is peeled off relatively easily and the active surface appears. The shape of the metal calcium is not particularly limited, but a shape of a powder having a small particle diameter is preferable. Even if the amount of metal calcium added is increased more than necessary, the decomposition rate and decomposition rate of PCB will not increase, but conversely, the amount used will be increased and the pressure of the system will be increased. Should not. On the other hand, if the amount is too small, sufficient electron transfer reduction does not occur, and the PCB decomposition rate does not increase. If an example of the addition amount of metallic calcium is shown, when the density | concentration of PCB contained in PCB containing oil is 50-200 ppm, it will be 8-12 g with respect to 1L of PCB containing oil.

  The detoxification temperature of the PCB-containing oil can be determined as appropriate from the compatibility of the oil and the solvent and the dissolution rate of the metal in the protic solvent. However, the oil and the protic solvent are compatible with each other without forming an emulsion. The temperature is preferably a temperature at which the metal can be solubilized, and the temperature at which the metal is dissolved in the protic solvent at a predetermined rate. For example, when ethanol is used as the protic solvent and isopropanol is used as the auxiliary solvent, the temperature may be set to 50 to 80 ° C. Here, the temperature at which the dissolution rate of the metal in the protic solvent becomes a predetermined rate means that, when metal calcium is used as the metal, the metal calcium salt generated by dissolution of the metal calcium is used as suspended particles. It is a temperature at which the amount of hydrogen gas generated from the surface of metallic calcium is not excessive because it is difficult to form a turbid liquid. If the temperature is increased more than necessary and the dissolution rate of metallic calcium in the protic solvent becomes too fast, it becomes easier to form a suspension in which the metallic calcium salt produced by dissolution of metallic calcium is suspended, and the metal The amount of hydrogen gas generated from the calcium surface is too large. The formation of a suspension and a large amount of hydrogen gas generated from the surface of the calcium metal are not preferable because it is presumed to inhibit the contact between the calcium metal and the PCB. If the temperature is too high, the generated hydrogen gas increases the pressure of the system and also increases the viscosity of the solution, so the temperature should not be higher than necessary.

  The detoxification treatment pressure of the PCB-containing oil is basically determined by the volume of the treatment tank for detoxifying the PCB-containing oil and the amount of generated hydrogen gas. From the viewpoint of increasing the PCB decomposition rate, a higher pressure is preferable, but even if the pressure is increased more than necessary, the PCB decomposition rate does not increase. On the other hand, it is preferable that the pressure is low from the viewpoint of device implementation and operability. For example, when ethanol is used as the protic solvent and isopropanol is used as the auxiliary solvent, the PCB detoxification treatment pressure can be 0.25 MPa (abs) or less.

  The present inventor is able to obtain the decomposition rate of PCB-containing oil of the present invention as quick and high as that of conventional metal calcium method and metal calcium catalyst method, despite the small amount of chemicals used. The reason is as follows. In general, PCB-containing oil has a strong affinity between PCB and oil. In the conventional metal calcium method and metal calcium catalyst method, simply reducing the amount of protic solvent and metal calcium added, emulsions and suspensions Since the PCB is not easily transferred to the protic solvent side, a high decomposition rate and a high decomposition rate cannot be obtained. On the other hand, in the method for detoxifying PCB-containing oil of the present invention, an auxiliary solvent is added to compatibilize the oil and the protic solvent. Although it is a protic solvent and metallic calcium, the contact opportunity of PCB, a protic solvent, and metallic calcium increases, and a quick decomposition rate and a high decomposition rate are obtained.

  As described above, the method for detoxifying PCB-containing oil according to the present invention can greatly reduce the amount of chemicals used compared to the conventional metal calcium method and metal calcium catalyst method, and is also an expensive reduction. Since no catalyst is required, the PCB-containing oil can be processed at low cost. Moreover, since the operation conditions are mild, the manufacturing cost for the device can be reduced.

  Next, another embodiment of the method for detoxifying PCB-containing oil according to the present invention will be described. In the following PCB-containing oil detoxification method, the temperature dependence of the compatibility between the protic solvent containing the auxiliary solvent and the PCB-containing oil is positively utilized, and the treated oil is recovered after detoxifying the PCB. To simplify the process.

  The following solvent is used as an auxiliary solvent. In a low temperature state, for example, a room temperature state, even if an auxiliary solvent is added, the PCB-containing oil and the protic solvent are in a phase-separated state, and even if they are stirred and mixed, an emulsion state is obtained. On the other hand, when these are heated, for example, at about 50 to 80 ° C., the PCB-containing oil and the protic solvent including the auxiliary solvent become compatible and uniform. Such an auxiliary solvent differs in relation to the protic solvent. However, when ethanol is used as the protic solvent, when isopropanol is used as the auxiliary solvent, the PCB-containing oil and the solvent are phase-separated at room temperature, When the temperature is raised to about 60 ° C., they become uniform, and then when the temperature is brought to room temperature, the PCB-containing oil and the solvent are phase-separated.

  When such a solvent is used as an auxiliary solvent, the PCB is detoxified at an elevated temperature, and then the temperature is lowered and left to stand to phase-separate the treated oil from which the PCB has been rendered harmless and the solvent. To do. Such a method does not require a special operation for separating the treated oil and the solvent, can easily recover the treated oil from which PCB is rendered harmless, and easily recycles the solvent. be able to. When the phase separation tank is used to separate the oil phase and the solvent phase, the metal calcium and the reaction product of metal calcium precipitate at the bottom due to the specific gravity, so they can be disposed of together with the treated oil. Metal calcium and the reaction product of metal calcium and the treated oil can be separated and recovered.

  The method for detoxifying a PCB-containing oil according to the present invention can be suitably used for detoxifying not only PCB-containing oil but also POPs such as DDT (Persistent Organic Pollutants).

  The above-described method for detoxifying PCB-containing oil can be realized using the following detoxification processing apparatus. FIG. 1 is a process flow diagram showing a schematic configuration of a PCB-containing oil continuous detoxification treatment apparatus 1 as one embodiment of the present invention. Needless to say, the continuous detoxification treatment apparatus for PCB-containing oil of the present invention is not limited to this embodiment. Hereinafter, a case where ethanol is used as the protic solvent, isopropanol is used as the auxiliary solvent, and calcium metal powder is used as the metal having at least a part of the protic solvent and having a reducing power by electron transfer will be described.

  The continuous detoxification treatment apparatus 1 is a raw material supply system that supplies PCB-containing oil, a solvent, and the like to be processed, a treatment tank that decomposes the PCB, and a separation and recovery system that separates and collects the treatment oil and solvent from the treatment. Broadly divided.

  The raw material supply system supplies a PCB-containing oil supply device 11 that supplies PCB-containing oil, an ethanol supply device 13 that supplies ethanol as a protic solvent, an isopropanol supply device 15 that supplies isopropanol as an auxiliary solvent, and metal calcium. A metallic calcium supply device 17 is included.

  The PCB-containing oil supply device 11 includes a storage tank 19 that stores the PCB-containing oil, and continuously supplies the PCB-containing oil to the treatment tank 41 through the fixed supply pump 21. Each of the ethanol supply device 13 and the isopropanol supply device 15 also includes storage tanks 23 and 27, and continuously supplies ethanol and isopropanol to the treatment tank 41 via the fixed supply pumps 25 and 29, respectively. The metallic calcium supply device 17 includes a storage tank 31 that stores powdered metallic calcium, and continuously supplies the stored metallic calcium powder to the processing tank 41 via the screw feeder 33. Since the activity of metallic calcium decreases when it reacts with oxygen, the storage tank 31 for storing metallic calcium is provided with an inert gas introduction pipe 35 and a gas discharge pipe 37 for introducing an inert gas such as nitrogen gas. Yes. For PCB-containing oil, ethanol, etc., heating means are provided in the storage tanks 19, 23, 27, or a heater (not shown) is provided in the middle of the pipe line connecting the fixed supply pumps 21, 25, 29 and the processing tank 41. These may be heated in advance and supplied to the treatment tank 41.

  The processing tank 41 receives PCB-containing oil, solvent, etc., dehalogenates and / or reduces the PCB to render the PCB harmless, and discharges the processed material through the discharge pipe 43 connected to the processing tank 41. The processing tank 41 is equipped with a stirrer 45. The shape of the stirring blade 47 used here is not particularly limited as long as the contents of the treatment tank 41 can be uniformly stirred and mixed. Since the solution containing metallic calcium is not high in viscosity, a stirring blade for low viscosity such as an inclined blade or a propeller blade can be used. At this time, since the contents in the processing tank 41 include solids and liquids, it is desirable to stir at a stirring speed equal to or higher than the minimum floating speed so that the solids do not precipitate.

  The treatment tank 41 has a heater (not shown) attached to the outer wall, and heats the contents to a predetermined temperature. The processing tank 41 has a gas line 49 at the top, and a pressure control valve (not shown) is attached to the outlet of the gas line 49 to adjust the inside of the processing tank 41 to a predetermined pressure. A reflux condenser 51 is provided in the middle of the gas line 49 and upstream of the pressure control valve. Thereby, the gas generated in the reaction process in the treatment tank 41 can be discharged through the gas line 49 as necessary. At this time, the solvent that has become vapor is condensed by the reflux condenser 51 so that the solvent does not escape from the system. The condensed solvent is returned to the processing tank 41 and stirred and mixed with the contents.

  The heating method of the processing tank 41 includes a method of mounting a heater on the outer wall of the processing tank 41, a method of mounting a heater in the processing tank 41, a heating coil in the processing tank 41, hot water and steam in the heating coil. Alternatively, a method of supplying a heat medium, a method of providing a jacket outside the processing tank 41, and supplying warm water, steam, or a heat medium to the jacket may be used.

  The size of the processing tank 41 may be any size as long as the residence time necessary for PCB decomposition can be ensured, and may be determined as appropriate from the supply rate of the object to be processed and the decomposition rate of the object to be processed. The processing tank 41 is not necessarily a tank-type processing tank, and it goes without saying that a tube-type processing device can be used. Even when a tank-type treatment tank is used, the treatment tank 41 does not have to be a single tank, and the treatment tanks can be arranged in multiple stages in series. Thus, the object to be processed can be made harmless efficiently.

  The processed material is continuously discharged from the processing tank 41 through the discharge pipe 43 together with an excess solvent and sent to the separation and recovery system. The separation and recovery system is a system that separates and recovers the processing oil and the solvent from the processed product, and mainly includes a cooler 53, a phase separation tank 55, and a distillation apparatus 57.

  The cooler 53 is a device for cooling the processed product sent through the discharge pipe 43, and cools the processed product to a temperature at which phase separation can be performed between the processing oil and the solvent. It is not always necessary to cool the processed product to a temperature at which phase separation can be performed between the processing oil and the solvent by using only the cooler 53. A cooling means is provided in the downstream phase separation tank 55, and the cooler 53 and the phase separation tank 55 The treated product may be cooled to a temperature at which phase separation can be performed between the treated oil and the solvent. Examples of the cooler 53 that can be used include indirect coolers such as a multi-tube cooler and a coil cooler that have been generally used. In addition, a double tube type cooler can be used. The cooling medium may be appropriately selected depending on the cooling temperature, and in the case of the present embodiment, cooling water such as industrial water can be used.

  In the phase separation tank 55, the processed product cooled by the cooler 53 is allowed to stand, and is separated into a processing oil and a solvent by a specific gravity difference. The phase separation tank 55 has a size that can secure the time required to separate the oil phase and the solvent phase. In addition, metal calcium and a metal calcium reactant are precipitated at the bottom of the phase separation tank 55. The phase separation tank 55 may be provided with a cooling means. For example, a jacket may be provided in the phase separation tank 55, or a cooling coil may be provided therein. By providing a cooling means in the phase separation tank 55, the load on the cooler 53 can be reduced. However, in order to increase the degree of separation between the treated oil and the solvent, it is preferable that the liquid is less disturbed in the phase separation tank 55, and it is preferable to cool with the cooler 53 as much as possible in consideration of heat convection.

  The distillation device 57 separates and recovers ethanol and isopropanol from the solvent phase-separated in the phase separation tank 55 by distillation operation. Such a distillation apparatus 57 does not need to be a special distillation apparatus, and a known distillation apparatus can be used.

  In the above-mentioned continuous detoxification treatment apparatus 1, when a predetermined amount of PCB-containing oil, ethanol, isopropanol, and metallic calcium are sent to the treatment tank 41, the temperature in the treatment tank 41 is about 60 ° C. The oil and solvent are homogenized and the PCB is dehalogenated and / or reduced and rendered harmless. By making the PCB-containing oil and the solvent uniform, the decomposition rate of PCB is fast and the decomposition rate becomes very high. The processed product from which PCB is rendered harmless is continuously sent to the cooler 53 through the discharge pipe 43, where the processing oil and the solvent are cooled to a temperature capable of phase separation. The processed product that has been cooled by the cooler 53 and phase-separated from the processing oil and the solvent is phase-separated into an oil phase and a solvent phase by the phase separation tank 55. The phase-separated process oil is continuously discharged from the lower part of the phase separation tank 55 and the solvent is continuously discharged from the upper part of the phase separation tank 55. Since the metal calcium and the metal calcium reactant are settled at the bottom of the phase separation tank 55, they can be appropriately discharged. As for the solvent phase-separated in the phase separation tank 55, ethanol and isopropanol are separated and recovered by the distillation device 57, and are returned to the storage tanks 23 and 27, respectively.

  When the detoxification treatment apparatus 1 uses ethanol as the protic solvent and isopropanol as the auxiliary solvent, the temperature of the treatment tank 41 may be about 60 ° C. and the pressure may be about 0.21 MPa (abs), and the operation conditions are mild. Since the specification of the apparatus does not need to be strict, it can be manufactured at low cost. Furthermore, since the equipment and devices constituting the continuous detoxification processing apparatus can be used as general-purpose equipment and equipment, they can be easily obtained and can be realized relatively easily. In the above-described continuous detoxification treatment apparatus 1, an example in which the treatment oil separated from the phase separation tank 55, metal calcium, and metal calcium reactant is separated and discharged has been shown, but these are discharged together without being separated. Of course, you may. A distillation apparatus 57 may be provided as necessary. In the above embodiment, an example in which the protic solvent and the auxiliary solvent are separately supplied has been described. However, these may be mixed in advance and supplied by a single solvent supply device. When the protic solvent and the auxiliary solvent are mixed in advance and supplied to the treatment tank 41 with a single solvent supply device, the solvent supply device is used to remove the solvent separated in the phase separation tank 55 without providing the distillation device 57. You may return it to At this time, the solvent returned from the phase separation tank 55 is analyzed, the ratio of the protic solvent to the auxiliary solvent is obtained, and the ratio of the protic solvent to the auxiliary solvent to be sent to the processing tank 41 is set to a predetermined ratio. In addition, a protic solvent and an auxiliary solvent may be replenished as necessary. In addition to the continuous detoxification processing apparatus, it is needless to say that a batch processing apparatus or a semi-batch processing apparatus can be used.

Example 1
A PCB-containing trans oil prepared as follows was used as an object to be treated. 0.044 g of KC500 was added to 500 ml of new transformer oil and stirred for about 12 hours. The PCB concentration in the transformer oil was measured and found to be 75 ppm. The PCB concentration was measured using GC-MS. For the decomposition tank, a stirrable sealed processing container (made of stainless steel, internal volume 84 ml) having a stirring bar (φ6 × 20) inside was used. The processing container includes a thermometer that measures the temperature of the contents and a pressure gauge that measures the internal pressure. An oil bath was used for heating.

  In the processing container, 29 ml of PCB-containing trans oil having a PCB concentration of 75 ppm, 6 ml of isopropanol, and 24 ml of ethanol were added in this order, and finally, 0.2855 g of granular metallic calcium was added, and the processing container was sealed. This is immersed in an oil bath, the stirrer is rotated at 600 rpm with a stirrer installed under the oil bath, the internal temperature in the processing vessel is adjusted to 60 ° C. while stirring the contents, and the PCB is decomposed for 3 hours. It was. After 3 hours, the contents in the processing container were taken out into a beaker. Furthermore, the processing container after taking out the contents was washed with 6 to 10 ml of 2N hydrochloric acid, and this washing solution was transferred to a beaker containing the contents to treat the remaining metallic calcium. After separating into two phases of a transformer oil phase and a solvent phase, the transformer oil phase was taken out and the PCB concentration was measured.

  As a result of the experiment, the PCB concentration after the decomposition treatment was 0.3 ppm, and the decomposition rate of PCB was 99.6%. The pressure in the processing container during the decomposition process increased almost linearly with respect to the elapsed time, and the pressure in the processing container at the end of the decomposition process was 0.21 MPa (abs).

Comparative Example 1
In a processing vessel, 29 ml of PCB-containing transformer oil with a PCB concentration of 115 ppm, 0.0144 g of Pd / C catalyst supporting 10 wt% of palladium on activated carbon, 6 ml of isopropanol, and 24 ml of ethanol were put in this order, and finally powdered metallic calcium 0.2828 g was added, and the internal temperature in the processing vessel was adjusted to 80 ° C. while stirring, and the PCB was decomposed for 3 hours. Other experimental procedures are the same as in Example 1.

  As a result of the experiment, the PCB concentration after the decomposition treatment was 27 ppm, and the PCB decomposition rate was 76.5%. The pressure in the processing container during the decomposition treatment is 0.21 MPa (abs) 1 hour after the start of the decomposition treatment, 0.55 MPa (abs) 2 hours after the start of the decomposition treatment, and 0.63 MPa (abs) at the end of the decomposition treatment. there were.

Comparative Example 2
In a processing vessel, 29 ml of PCB-containing trans oil with a PCB concentration of 75 ppm, 0.0143 g of Pd / C catalyst supporting 10 wt% of palladium on activated carbon, 6 ml of isopropanol, and 24 ml of ethanol were put in this order, and finally powdered metallic calcium 0.2854g was thrown in, the internal temperature in a processing container was adjusted to 60 degreeC, stirring, and PCB decomposition | disassembly was performed for 3 hours. Other experimental procedures are the same as in Example 1.

  As a result of the experiment, the PCB concentration after the decomposition treatment was 10 ppm, and the PCB decomposition rate was 86.7%. The pressure in the processing container during the decomposition treatment is 0.11 MPa (abs) 1 hour after the start of the decomposition treatment, 0.125 MPa (abs) 2 hours after the start of the decomposition treatment, and 0.22 MPa (abs) at the end of the decomposition treatment. there were.

Reference example 1
The compatibility experiment between the trans oil and the solvent was conducted as follows. At room temperature, 4.8 ml of trans oil was put into a test tube pressure-resistant glass container. The height of the liquid at this time was 27 mm. Next, 1 ml of isopropanol was added, stirred and allowed to stand. As a result, a uniform phase was obtained, and the height of the liquid was 30 mm. This height is almost the same as the sum of the liquid levels. Subsequently, 4 ml of ethanol was added, stirred and allowed to stand, and then separated into two phases. The lower phase was trans oil and the upper phase was solvent. At this time, the height of the transformer oil was 25 mm, which was 2 mm less than the initial liquid height. The height of the solvent phase was 21 mm, and the total liquid height was 46 mm. This was heated to 80 ° C., stirred, and then cooled to 50 ° C. while being allowed to stand, and the whole was a transparent single phase. The mixture was further stirred at 80 ° C. and allowed to stand for 12 hours and cooled to room temperature. As a result, it was separated into two phases as before heating. The height of each phase at this time was the same as before heating.

Reference example 2
The experiment was performed in the same manner as in Reference Example 1 except that isopropanol was not added. When trans oil and ethanol were mixed and allowed to stand at room temperature, they were separated into two phases. The lower phase was trans oil and the upper phase was solvent. At this time, the height of the transformer oil was 25 mm, which was 2 mm less than the height of the liquid before addition of ethanol. The height of the solvent phase was 18 mm, and the total liquid height was 43 mm. This was heated to 80 ° C., stirred, and then allowed to cool to 50 ° C. while being left still. The mixture was further stirred at 80 ° C. and allowed to stand for 12 hours and cooled to room temperature. As a result, it was separated into two phases as before heating. The height of each phase at this time was the same as before heating, and each phase was transparent.

DESCRIPTION OF SYMBOLS 1 Continuous detoxification processing apparatus 11 PCB containing oil supply apparatus 13 Ethanol supply apparatus 15 Isopropanol supply apparatus 17 Metal calcium supply apparatus 41 Processing tank 45 Stirrer 53 Cooler 55 Phase separation tank 57 Distillation apparatus

Claims (5)

An oil containing PCB, a protic solvent, and a metal having at least a part dissolved in the protic solvent and having a reducing power by electron transfer are mixed, and the PCB is dehalogenated and / or reduced to obtain a PCB. In the detoxification processing method of the PCB-containing oil to be detoxified,
An auxiliary solvent having affinity for the oil and the protic solvent is added, the oil and the protic solvent are made compatible without causing an emulsion, and the oil and the protic solvent are made compatible with each other. A method for detoxifying PCB-containing oil, comprising dehalogenating and / or reducing PCB to detoxify PCB. The protic solvent is ethanol;
The method for detoxifying PCB-containing oil according to claim 1, wherein the auxiliary solvent is isopropyl alcohol. The PCB is dehalogenated and / or reduced under heating,
The heating temperature is a temperature at which the oil and the protic solvent can be compatibilized without producing an emulsion, and the dissolution rate of the metal in the protic solvent is a predetermined temperature. The method for detoxifying PCB-containing oil according to claim 1 or 2. An oil supply device capable of quantitatively supplying oil containing PCB;
A solvent supply device capable of quantitatively supplying a protic solvent and an auxiliary solvent having affinity for the oil and the protic solvent;
A metal powder supply device capable of quantitatively supplying metal powder having at least a portion dissolved in the protic solvent and having a reducing power by electron transfer;
Accept the oil containing the PCB, the protic solvent, the co-solvent and the metal, mix them, make the oil and the protic solvent compatible without causing an emulsion, and dehalogenate the PCB And / or a treatment tank for reduction treatment;
Stirring means for stirring and mixing the contents of the treatment tank;
A PCB-containing oil detoxification treatment apparatus comprising:   The apparatus further comprises a solvent recovery device for separating and recovering the protic solvent, or the protic solvent and the auxiliary solvent from the contents of the processing tank in which PCB has been dehalogenated and / or reduced. 4. The PCB-containing oil detoxifying apparatus according to 4.

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