JP2006142227A - Pcb decomposition equipment and pcb decomposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide PCB decomposition equipment which can prevent the pollution of a reaction medium due to contamination of a material to be treated, after completing the decomposition reaction of PCB, and a PCB decomposition method. <P>SOLUTION: The PCB decomposition equipment has a reaction tank for performing the decomposition reaction of PCB, and an injection pipe for injection of the material to be treated to the reaction tank. A washing medium feed part is installed in the injection pipe to enable the distribution of a washing medium to the injection pipe disposed between the feed part and an opening part toward the reaction tank. The PCB decomposition method employs the PCB decomposition equipment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a PCB decomposition processing facility for decomposing PCB by a chemical processing method, and a PCB decomposition processing method using this facility.

  Conventionally, only a method of incineration at a high temperature has been accepted as a PCB treatment method, but recently, in addition to this high temperature incineration treatment, a chemical treatment for newly decomposing PCB by a chemical reaction has been recognized, and various chemical treatments have been recognized. Legislation is being considered and implemented.

  PCB chemical treatment (decomposition treatment) is performed by a PCB decomposition treatment facility having a reaction tank for decomposing PCB and a pipe (injection pipe) for injecting a treatment object such as waste insulating oil into the reaction tank. Done. Then, PCB contained in the object to be processed at a concentration of% order is decomposed in the reaction medium (for example, insulating oil), and the concentration of PCB in the reaction medium is finally 0.5 μg / g or less. It is requested to be.

  In a normal chemical plant, the chemical solution is injected from the nozzle of an injection tube installed in the reaction tank, but the same injection method is also adopted in this PCB decomposition treatment facility. However, in this case, the processing object containing% order PCB remains in the injection tube after the injection. Since the final PCB concentration is required to be as low as 0.5 μg / g or less, if this remaining object to be processed is mixed into the reaction medium after completion of the decomposition treatment, the amount of mixing is small. However, there is a problem that the target PCB concentration cannot be achieved.

  For example, a concentration of 0.5 μg / g corresponds to a concentration in which 1000 g of reaction medium contains 1 drop (about 0.5 mg) of 100% PCB, so that when the amount of reaction medium is less than 1000 g, If even a single drop of 100% PCB enters the reaction vessel from the PCB injection tube after the decomposition is completed, a low concentration of 0.5 μ / g or less cannot be achieved.

  In addition, due to the splashing of the reaction solution during the decomposition reaction, the reaction solution containing a high concentration of PCB may adhere to the upper wall surface or adhere to the upper wall surface due to evaporation of the PCB. Similar problems arise when mixed into the reaction medium. Therefore, in the PCB decomposition processing facility, it is necessary to pay close attention to the equipment and the operation method in order to prevent contamination, and a PCB decomposition processing facility that does not cause such mixing is desired.

  Further, in order to confirm the end of the PCB decomposition process, analysis of the PCB concentration in the reaction medium is required after the decomposition reaction. Therefore, it is necessary to collect the liquid in the reaction tank, and the reaction tank is provided with a sampling line as equipment for collecting.

  However, there may be a case where the collected liquid at the previous sampling remains in the sampling line, and the processing target at the initial stage of the reaction containing PCB of% order is diffused in the line. Therefore, these may be mixed in the collected material at the time of sampling, and the PCB concentration may be different from the actual liquid in the reaction tank.

  In order to avoid this problem, conventionally, washing in the sampling line using the liquid in the reaction tank has been performed. However, there is a problem that a large amount of co-washing liquid is required to clean and replace the inside of the sampling line, and a sampling line free from such a problem has been desired.

  An object of the present invention is to provide a PCB decomposition processing facility and a PCB decomposition processing method capable of preventing contamination of a reaction medium due to mixing of an object to be processed after completion of a decomposition reaction.

  Another object of the present invention is to provide a PCB decomposition processing facility provided with a sampling means that enables accurate sampling without requiring a large amount of co-washing liquid.

  After completion of the decomposition reaction, the problem of preventing contamination of the reaction medium due to the mixing of the processing object etc. is a PCB having a reaction tank that performs a decomposition reaction of the PCB and an injection pipe for injecting the processing object into this reaction tank. A decomposition treatment facility, characterized in that a supply part of the cleaning medium is provided in the injection pipe, and the cleaning medium can be circulated through the injection pipe between the supply part and the opening into the reaction tank. This can be achieved by a PCB decomposition processing facility (claim 1).

  According to this PCB decomposition processing facility, it is possible to circulate (flush) the cleaning medium through the injection pipe up to the opening to the reaction tank after the processing object is injected into the reaction tank. Thus, the processing object remaining in the injection tube can be washed and removed. Therefore, even if a back flow of the liquid remaining in the injection tube occurs after the decomposition reaction is finished, this liquid is not a processing object containing PCB at a high concentration. Does not occur.

  The cleaning medium used for flushing the injection pipe is not particularly limited as long as it is a fluid for efficiently removing the processing object remaining in the injection pipe, but the processing object is obtained by using a reaction medium such as insulating oil. Is efficiently removed, and other components are not mixed into the decomposition reaction. Therefore, a reaction medium such as insulating oil is preferably exemplified.

  The injection pipe has a check valve for preventing the liquid in the reaction tank from flowing back into the injection pipe. The supply section for injecting the cleaning medium into the injection pipe is provided on the side farther from the check valve than the check valve, and is provided so that the entire area between the check valve and the opening into the reaction tank is cleaned. Yes. If provided on the reaction tank side from the check valve, the processing object remaining between the supply unit and the check valve is not cleaned and removed, and may be mixed into the reaction medium after the reaction is completed.

  The opening into the reaction vessel of the injection tube is preferably provided so as to be below the liquid surface of the reaction liquid (a mixture of the reaction medium and the object to be treated) during the PCB decomposition reaction. By providing the opening below the surface of the reaction liquid during the decomposition reaction, it is possible to suppress the splashing of the reaction liquid during the reaction and evaporation of the PCB to reduce contamination on the upper wall of the reaction tank. Claim 2 corresponds to this preferable mode.

  In addition, when the boiling point of the agent for treating the excess dechlorinating agent (for example, water) is lower than the temperature of the reaction medium, in order to prevent contamination by the agent on the reaction vessel upper wall surface due to boiling, Similarly to the opening of the injection tube, it is desirable that the opening be provided below the surface of the reaction solution.

  Examples of the object to be treated in the present invention include a high-purity PCB enclosed in a capacitor, a transformer, and the like, and a product recovered from a washing solution of an object contaminated by the capacitor, the transformer, and other PCBs.

  The injection pipe for the object to be treated is preferably an insert pipe system so as to protrude 5 to 50 mm from the inner wall surface of the reaction tank. Here, the insert tube system refers to a system in which an injection tube is inserted as it is into a hole opened in the reaction tank, and its tip protrudes into the reaction tank. In the vicinity of the opening, a portion that becomes a liquid pool and is difficult to be cleaned is likely to be generated, but this method is preferable because such a portion can be reduced. If the tip of the injection tube is provided so as to protrude from the inner wall surface of the reaction vessel, the portion that is difficult to be cleaned can be further reduced. If the protruding length is less than 5 mm, there is a possibility that unreacted PCB may stay between the insert pipe and the hole opened in the reaction tank due to the influence of vortex flow in the reaction tank. Since this portion is susceptible to deterioration due to vibration, the protruding length is preferably in the range of 5 to 50 mm. Claim 3 corresponds to this preferable mode.

  The cleaning medium supply unit preferably includes a processing object injection line, a cleaning medium supply line, and a three-way valve for connecting an injection pipe between the supply unit and the reaction tank. The three-way valve can clean the pool from the line branch point to the valve, and prevents the processing object containing high-concentration PCB from remaining in this supply section and mixing it after the decomposition process. Can do. Claim 4 corresponds to this preferred embodiment. As the three-way valve, a three-way ball valve with little liquid accumulation in the valve is particularly preferable.

  If there is a liquid pool in the connection portion of the injection pipe for the object to be processed, unreacted PCB may stay and contaminate the reaction medium after completion of the decomposition reaction. In view of this, it is preferable to employ a joint, for example, a Swagelok joint, in which the flange portion has little liquid accumulation, for example, as the connection portion. Further, as a pipe material used for the injection pipe, a BA pipe (bright annealing pipe) or an inner surface buffing pipe is preferably used in order to perform cleaning with a cleaning medium more reliably.

  If there is a part that becomes a liquid pool in the nozzle of the liquid contact part of the reaction tank, when the reaction efficiency deteriorates due to lack of stirring, etc., there is a possibility that unreacted PCB stays in this part and flows backward during discharge. is there. Therefore, in order to prevent this problem, it is desirable that the liquid contact portion of the reaction tank has a structure that eliminates a portion of the liquid reservoir as much as possible, such as using a pad flange as a nozzle.

  After completion of the PCB decomposition reaction, the problem of preventing contamination of the reaction medium due to mixing of objects to be processed is the use of the PCB decomposition processing facility of the present invention, and a cleaning medium supply section provided in the injection pipe. This is achieved by a method in which a cleaning medium is circulated through an injection tube between the reaction vessel and the reaction vessel. Claim 5 corresponds to this embodiment, and is a PCB decomposition processing method in which a processing object containing PCB is supplied to a reaction tank from an injection tube having a check valve, and a decomposition reaction of PCB is performed in the reaction tank. In addition, before the completion of the decomposition reaction, the cleaning medium is circulated through the injection pipe between the reaction tank and the supply section of the cleaning medium provided on the side far from the check valve from the reaction tank of the injection pipe. The PCB decomposition processing method characterized by the above is provided.

  Since the processing object remaining in the injection tube is cleaned and removed by circulation of the cleaning medium, contamination of the reaction medium due to mixing of the processing object after completion of the decomposition reaction can be prevented. The processing object remaining in the injection tube is mixed in the reaction tank together with the cleaning medium, and the contained PCB is decomposed in the reaction tank. Accordingly, the circulation of the cleaning medium needs to be performed before the end of the decomposition reaction. However, in order to increase the efficiency of the decomposition reaction, the cleaning medium is preferably performed before the start of the decomposition reaction in which the PCB concentration in the reaction tank is high. . Further, in order to prevent contamination due to the backflow of the decomposition reaction solution (PCB concentration is not sufficiently reduced) during the reaction into the injection tube, washing may be performed during the reaction.

  The flow of the cleaning medium is preferably performed using a cleaning medium whose amount is 40 times or more the volume of the pipe (injection pipe) from the check valve to the reaction tank, and at a flow rate at which the Re number is 1000 or more. If the flow rate is less than 40 times or the flow rate is such that the Re number is less than 1000, sufficient cleaning may not be performed. In addition, if it is carried out with a large amount of cleaning medium, there is no problem with cleaning, but problems such as a decrease in the reaction tank temperature occur, so the flow rate may be less than 500 times the piping volume from the check valve to the reaction tank. desirable.

  Claim 6 corresponds to this preferred embodiment, and is the above PCB decomposition method, wherein the flow of the cleaning medium is 40 times or more and less than 500 times the volume of the injection pipe from the check valve to the reaction tank. The present invention provides a PCB decomposition method characterized by using a cleaning medium and performing at a flow rate at which the Re number is 1000 or more.

  Examples of the PCB decomposition reaction performed in the PCB decomposition treatment method of the present invention include a reaction in which PCB is dechlorinated and decomposed. In particular, a reaction in which PCB is dechlorinated using metallic sodium and decomposed is preferably exemplified.

  The problem of providing a PCB decomposition treatment facility provided with a sampling means that enables accurate sampling without requiring a large amount of co-washing solution is a reaction tank in which a PCB decomposition reaction is performed, and a treatment object in this reaction tank A PCB decomposition treatment facility having an injection tube for injecting gas and a sampling line for collecting a reactant in the reaction tank, wherein the sampling line is provided with a gas purge line This is achieved by a decomposition treatment facility (claim 7).

  That is, the sampling line is preferably provided with a gas purge line. Before collecting the sample, flush the gas into the sampling line from the gas purge line, so that residual liquid in the sampling line, for example, the collected liquid at the previous sampling, or the processing target at the initial stage of the reaction diffused in the line Things can be removed and the required amount of co-wash solution can be reduced. Nitrogen is illustrated as a gas used for gas purge.

  According to the PCB decomposition treatment facility of the present invention, the cleaning medium can be circulated (flushed) through the injection pipe to the opening to the reaction tank, and the processing object remaining in the injection pipe is washed and removed. can do. Therefore, if PCB decomposition processing is performed by the PCB decomposition processing facility and the PCB decomposition processing method of the present invention, even if a reverse flow of the liquid remaining in the injection pipe occurs after the decomposition reaction, this liquid has a high concentration of PCB. Since it is not a processing object to be contained, the PCB concentration in the reaction medium does not increase due to the mixing. As a result, contamination of the reaction medium can be prevented, and PCB decomposition processing can be performed stably.

  According to the PCB decomposition processing facility of the present invention, in which the gas purge line is provided in the sampling line, residual liquid in the sampling line can be removed by flushing from the gas purge line before sampling. The required amount of washing liquid is reduced, and accurate sampling is possible.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to this mode.

  FIG. 1 is a schematic diagram showing an example of a PCB decomposition processing facility of the present invention. A processing object including PCB passes through the injection line 2 and the injection tube 3 and is injected into the reaction tank 1 through the opening 4 of the injection tube. In the reaction tank 1, a reaction medium such as the object to be treated and insulating oil is supplied, and a PCB decomposition reaction is performed.

  In the example of FIG. 1, the opening 4 is provided at a position lower than the liquid level of the reaction medium or the like in the reaction tank 1. As a result, it is possible to suppress the splashing of the reaction liquid during the reaction and the evaporation of PCB, and to reduce the contamination of the upper wall surface of the reaction tank.

  The reaction tank 1 is provided with stirring means 6, heating means (not shown), cooling means (not shown), temperature adjusting means, and the like. While making adjustments, the PCB decomposition reaction is performed.

  The injection pipe 3 is provided with a cleaning medium supply line 5, and after supplying the processing object into the reaction tank 1 through the injection pipe 3, the cleaning medium is supplied from the cleaning medium supply line 5 into the injection pipe 3. It is distributed and the inside of the injection tube 3 is cleaned. As a result, the processing object remaining in the injection tube 3 is removed, and contamination due to this backflow can be prevented.

  The part connecting the supply line 5 and the injection pipe 3, that is, the supply part of the cleaning medium, is constituted by a three-way ball valve 7 in which the liquid pool in the valve is small. An injection line 2, an injection pipe 3 and a cleaning medium supply line 5 are connected to the three-way ball valve 7.

  1 is further provided with a drug injection line 8 for injecting another drug. The opening of the chemical injection line 8 to the reaction tank 1 is also provided below the surface of the reaction liquid in order to prevent the chemical reaction on the upper wall surface of the reaction tank.

  Note that a Swagelok joint is employed to reduce the liquid pool in the flange portion. A pad flange is used as a nozzle in the wetted part of the reaction tank in order to eliminate the liquid pool as much as possible. In addition, since the piping is thin in this example, measures against deterioration (FIV) due to vibration are taken by suppressing the protrusion of the piping from the reaction vessel wall surface.

  The PCB decomposition processing apparatus in the example of FIG. 1 is further provided with sampling means for collecting an analysis sample for confirming the end of the decomposition reaction. The sampling means is a sampling line 9 having one end in the reaction solution, through which the reaction solution is sampled and used for analysis.

  The sampling line 9 is provided with a gas purge line 10 so that nitrogen can be flushed into the sampling line. By flushing before the sample is collected, the residual liquid in the sampling line 9 can be removed, and the required amount of the co-washing liquid can be reduced.

  FIG. 2 is a partially enlarged schematic view showing the injection tube 3 and its periphery in the example of FIG. The injection line 2, the injection pipe 3 and the cleaning medium supply line 5 are connected to the three-way ball valve 7 by connection means using a nut 21 or the like. After supplying the processing object through the injection line 2, the inside of the injection pipe 3 is cleaned by switching the three-way ball valve 7 and circulating the cleaning medium from the cleaning medium supply line 5 into the injection pipe 3. .

  A check valve 24 for preventing a backflow from the reaction tank is provided in the middle of the injection pipe 3 and is connected to the injection pipe 3 by connection means using a nut 21 or the like. One end of the injection tube 3 is connected to a nozzle 25 formed on the wall portion 23 of the reaction tank 1 by connecting means using a nut 21 and a flange 22. The injection tube 3 is inserted into the nozzle 25 (insert method), and the opening 4 at the tip thereof protrudes into the reaction tank 1. Note that an inner surface buffing pipe is used for the piping material forming the injection pipe 3 in order to improve the cleaning performance.

Next, the effects of the present invention will be described more specifically based on reference examples and examples. The scope of the invention is not limited by the examples.
Reference example

  1 and FIG. 2, the same structure as the apparatus shown in FIG. 1 and FIG. 2 is used, and a PCB decomposition treatment facility in which the inner volume from the check valve 24 to the opening 4 of the injection tube 3 is about 25 ml is used. Then, it was supplied into the reaction tank 1 through the injection tube 3, and then flushing was performed in the injection tube 3 at a flow rate such that Re was about 1100, using insulating oil as a cleaning medium in the amount shown in Table 1. Table 1 shows the PCB concentration in the insulating oil in the pipe after flushing.

  Assuming that the amount of insulating oil in the reaction tank 1 is 1000 kg, it is assumed that all the insulating oil in the pipe from the check valve 24 to the opening 4 after flushing flows back into the reaction tank and contaminates the reaction tank. In this case, the PCB concentration in the reaction tank 1 was calculated. The calculated values are shown in Table 1. When washed with 1 L of insulating oil (ie, 40 times the pipe volume), the PCB concentration in the reaction tank 1 is 0.05 μg / g, which is negligible compared to the PCB standard value of 0.5 μg / g. .

  1 and FIG. 2, the same structure as that of the apparatus shown in FIG. 1 and FIG. 2, and using a PCB decomposition processing facility in which the internal volume from the check valve 24 of the injection pipe 3 to the opening 4 is about 25 ml, The reaction oil is supplied into the reaction tank 1 through the injection pipe 3, and then the inside of the injection pipe 3 is circulated at a flow rate of about 1100 with a Re number of about 5 L (about 200 times the pipe volume) as the cleaning medium. It was supplied into the tank 1. Thereafter, the PCB was decomposed, the reaction solution after the treatment was discharged, and the PCB concentration was reanalyzed, but no contamination was confirmed.

It is a schematic diagram which shows an example of the PCB decomposition processing equipment of this invention. FIG. 2 is a partially enlarged schematic view showing an injection tube 3 and its periphery in the example of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Injection line 3 Injection pipe 4 Opening part 5 Washing medium supply line 6 Stirring means 7 Three-way ball valve 8 Chemical injection line 9 Sampling line 10 Gas purge line 23 Wall part 24 Check valve 25 Nozzle

Claims (7)

  A PCB decomposition treatment facility having a reaction tank for decomposing PCBs and an injection pipe for injecting a processing object into the reaction tank, wherein a supply part for a cleaning medium is provided in the injection pipe, A PCB decomposition treatment facility, characterized in that a cleaning medium can be circulated through an injection pipe between the opening into the reaction tank.   The PCB decomposition treatment facility according to claim 1, wherein the opening of the injection tube into the reaction tank is provided so as to be below the surface of the reaction solution during the PCB decomposition reaction.   The PCB decomposition treatment facility according to claim 1 or 2, wherein the injection pipe for the object to be treated is provided so as to protrude 5 to 50 mm from the inner wall surface of the reaction tank by an insert pipe method.   The cleaning medium supply section includes a processing object injection line, a cleaning medium supply line, and a three-way valve for connecting a processing object injection pipe located between the supply section and the reaction tank. The PCB decomposition processing facility according to any one of claims 1 to 3.   A PCB decomposition treatment method for supplying a treatment object containing PCB to a reaction vessel from an injection pipe having a check valve, and performing a decomposition reaction of PCB in the reaction vessel, A PCB decomposition treatment method, wherein a cleaning medium is circulated through an injection pipe between a reaction tank and a supply part of a cleaning medium provided on a side farther from the reaction tank of the injection pipe than the check valve.   The flow of the cleaning medium is performed using a cleaning medium in an amount of 40 times or more and less than 500 times the volume of the injection pipe from the check valve to the reaction tank, and at a flow rate at which the Re number is 1000 or more. Item 6. The PCB decomposition processing method according to Item 5. A PCB decomposition treatment facility having a reaction vessel in which a PCB decomposition reaction is performed, an injection pipe for injecting a treatment object into the reaction vessel, and a sampling line for collecting a reaction product in the reaction vessel, A PCB decomposition treatment facility characterized in that a gas purge line is provided in the sampling line.

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