JP3622132B2 - Treatment method of PCB mixed oil - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for treating oil mixed with PCB (polychlorinated biphenyl is simply abbreviated as PCB in the present application), and in particular, detoxifies the mixed PCB and additionally suppresses the generation of dioxins during incineration and treatment. The present invention relates to a method for treating PCB mixed oil.
[0002]
Since PCB is toxic, its production and use are currently limited, but a large amount of PCB-mixed oil such as waste transformer oil that has already been produced and used is stored. Of course, this PCB-mixed oil is combustible, so it is the easiest to incinerate, but in fact it is widely known that harmful dioxins are generated if it is simply incinerated. It cannot be incinerated.
[0003]
Various methods for decomposing PCB while suppressing the generation of dioxins have been proposed, and recent reports indicate that the generation of dioxins can be suppressed by high-temperature incineration under strict temperature control.
[0004]
However, the high-temperature incineration method for PCBs described above is very complicated in temperature control and requires a large amount of energy to maintain a high-temperature reaction atmosphere using an electric melting furnace or the like. There is a problem that the processing cost becomes too high in the processing of the PCB mixed oil whose volume is increased.
[0005]
Therefore, as a method of incinerating the PCB mixed oil in a normal incinerator by self-combustion or adding some auxiliary fuel, water is supplied to the combustion site in the state of steam or the like, and further hydroxide is supplied. In addition to ionizing chlorine contained in PCB, a method of neutralizing this chlorine with a hydroxide and fixing it as a salt has been proposed and tried.
[0006]
However, although the above water addition neutralization reaction method has a corresponding dioxin generation inhibiting effect, it still generates a considerable amount of dioxin, and at this time it cannot be said that it is completely safe and will be put into practical use. Not reached.
[0007]
[Problems to be solved by the invention]
Therefore, the present invention makes it possible to incinerate without generating dioxins by detoxifying the PCB-mixed oil and further precipitating chlorine as a dioxin-causing substance during decomposition from the PCB mixed oil as a salt by a neutralization reaction. An object of the present invention is to provide a method for treating PCB mixed oil.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned problems, the invention of claim 1 is the first step in which water and surfactant are mixed in the PCB-mixed oil and stirred to form an emulsion, and the second step is emulsification. After mixing the aqueous hydroxide solution with the mixed PCB mixed oil, technical means were taken to inject it into the incinerator and incinerate.
[0009]
Therefore, in the method for treating PCB-mixed oil according to the present invention, the PCB-mixed oil particles (small droplets) are surrounded by finer water particles in the first step, and the PCB-mixed oil and water are not easily separated. Thus, an effect is obtained in which an emulsion mixed substantially uniformly is obtained. Of course, the PCB-mixed oil is hydrophobic and hardly dissolves in water, so that it can be emulsified by adding a surfactant. Then, when water and a surfactant are added to the PCB-mixed oil to form an emulsion, the contact efficiency between the PCB (particularly chlorine contained in the PCB) and water is improved. Furthermore, since an aqueous solution of hydroxide is used, the hydroxide is uniformly mixed with PCB and exhibits an effect of improving the frequency of contact with chlorine of the PCB.
[0010]
And since it is now incinerated, the PCB is oxidatively decomposed by incineration, so that the salt is dissolved again, preventing chlorine from being re-incorporated into the PCB molecules, and the chlorine and hydroxide ionized by the heat during combustion. It is precipitated as a stable solid-state salt by the neutralization reaction, and exhibits the action of preventing the formation of dioxins.
[0011]
Next, in the invention of “Claim 2”, as a first step, after mixing water with a volume ratio of 50 to 80% and an appropriate amount of a surfactant into oil mixed with PCB, stirring is performed to obtain an emulsion. As a second step, emulsified PCB-mixed oil and a saturated aqueous solution of hydroxide with a volume ratio of 50 to 200% are mixed with this emulsion and injected into an incinerator to be incinerated at 800 ° C. or higher. The technical measures taken are taken.
[0012]
Therefore, according to the present invention, the volume ratio of water to PCB-mixed oil is 50 to 80%, the surfactant is an appropriate amount (the amount necessary for emulsification, and greatly changes depending on the type of surfactant or the property of PCB-mixed oil. As an embodiment, when a commercially available polyoxyethylene type nonionic surfactant was used as the surfactant, an appropriate amount was about 20% by volume with respect to the PCB-mixed oil). By doing so, an action is obtained in which a gel-like substance in which PCB-mixed oil and water are uniformly mixed is obtained.
[0013]
Then, by mixing the emulsified PCB-mixed oil and a saturated aqueous solution of hydroxide having a volume ratio of 50 to 200% with respect to this emulsion, the gel-like substance is diluted and the viscosity is lowered to make the sol easy to fluidize. In addition to exhibiting the action of becoming a self-combustible state in the state, the action of making the chlorine and hydroxide of the PCB easily ionized or ionized in the presence of water as described above.
[0014]
When the sol-formed PCB-mixed oil is incinerated at a temperature of 800 ° C. or higher, the neutralization reaction between the chlorine and the hydroxide occurs during the incineration, and the action of reliably suppressing the generation of dioxins is exhibited.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described in detail. First, in the present invention, as a first step, water and a surfactant are mixed in PCB-mixed oil, and then stirred to form an emulsion.
[0016]
The PCB-mixed oil is assumed to be a PCB-mixed waste transformer oil that is currently stored in large quantities. Of course, other PCB-mixed oil may be used.
[0017]
Then, the above-mentioned PCB contaminated oil mixed and water _(H 2 O) and surfactant. Water may be tap water, and various known substances such as the polyoxyethylene nonionic surfactant described above may be used as the surfactant.
[0018]
The mixing amount of the water and the surfactant may be appropriately selected so that a uniform emulsion can be formed. In one embodiment, the amount of water added is 50% or more by volume, and the surfactant is oil mixed with PCB. On the other hand, when the volume ratio was 20% or more, a cloudy and uniform emulsion could be produced. In addition, when mixing water with a volume ratio of 100% or more, mixing water and a surfactant with a volume ratio of about 50 to 80% and stirring to emulsify, then adding the remaining water and stirring. It is easy to obtain a uniform emulsion. However, the amount of water mixed here is preferably 50 to 80% by volume with respect to the oil mixed with PCB in order to obtain an emulsion easily and reliably.
[0019]
Of course, the amount of water may be 80% or more, but if a large amount of water is added at one time, a large amount of power is required for stirring, and a conventional stirrer is used for water addition with a volume ratio of 50 to 80%. Thus, an emulsion can be obtained easily and reliably, and when it is further hydrated, it was efficient to hydrate it.
[0020]
When a surfactant and water having a volume ratio of 50 to 80% with respect to the PCB-mixed oil are mixed in the PCB-mixed oil and then stirred, a gel-like emulsion is obtained. Therefore, in the present invention, as a second step, the aqueous hydroxide solution is mixed with the gelled PCB-mixed oil, and then injected into the incinerator and incinerated.
[0021]
That is, in the second step, by mixing the aqueous hydroxide solution, firstly the hydroxide that removes the chlorine of the PCB by the neutralization reaction is mixed, and secondly, it is added to the gelled PCB mixed oil. Intended to sol. The mixing of the hydroxide is the same as that in “Claim 1”. However, by using a hydroxide aqueous solution, the hydroxide can be mixed uniformly.
[0022]
And by adding the hydroxide aqueous solution, the gel-like emulsion is diluted and the viscosity is lowered to form a sol, but the amount of water here is such that it is easy to transport the PCB-mixed oil through the pipeline. Try to get viscosity. However, if the amount of water is increased too much, transportation becomes easier, but self-combustion is not possible during incineration. If the self-combustion is not possible, auxiliary fuel is required for the leg. Therefore, the minimum amount of water that can be injected into the in-line furnace and in the incinerator described below is desirable, and a water amount of 40 to 200% by volume is suitable for the emulsion of the PCB-mixed oil obtained in the first step. Met.
[0023]
In addition, even if surfactant is mixed, the solated PCB-mixed oil is separated from water if left for a very long time, or repeatedly collides in the conveyance path or is subjected to external force such as centrifugal force. Since there is a tendency, it is desirable to mix the hydroxide aqueous solution immediately before incineration.
[0024]
And this invention injects the said sol-ized PCB mixing oil in an incinerator, and incinerates. As this incinerator, a conventionally known ordinary one can be used. That is, the solbed PCB mixed oil is ejected from the nozzle and ignited by the auxiliary burner. After ignition, combustion can be continued even if the auxiliary burner is stopped, but if the combustion atmosphere is 400 ° C or lower, a considerable amount of hydrocarbons and some dioxins are mixed in the exhaust, so the combustion here is 800 ° C or higher. As a matter of course, it is desirable to carry out more reliable oxidative decomposition of hydrocarbons. For this reason, it is of course possible to continue the operation of the auxiliary burner if necessary.
[0025]
That is, the PCB-mixed oil is oxidatively decomposed by incineration, but not all benzene nuclei of the PCB-mixed oil can be decomposed by incineration in this kind of normal incinerator. And, when benzene nuclei containing chlorine that could not be decomposed by incineration are recombined, dioxins are generated. In the present invention, combustion is performed in an atmosphere where water and hydroxide exist. And the hydroxide are neutralized, and chlorine is precipitated as a salt to prevent the generation of dioxins.
[0026]
Next, the invention of “Claim 2” performs safe processing for each nucleus by limiting the conditions of the invention of “Claim 1”. That is, in the first step, water with a volume ratio of 50 to 80% and an appropriate amount of surfactant are mixed into the PCB-mixed oil, and then stirred to form an emulsion.
[0027]
In order to mix the surfactant into the PCB-mixed oil evenly with water, it is difficult to mix evenly when a large amount of water is mixed at once. The most uniform emulsion was obtained easily and reliably.
[0028]
And as a 2nd process, this invention mixes the emulsified PCB mixing oil and the saturated aqueous solution of the hydroxide of 50-200% of volume ratio with respect to this emulsion, and injects in 800 incinerator. Incinerate above ℃.
[0029]
As described above, the mixing amount of the saturated aqueous solution of hydroxide and the incineration temperature are limited as described above. The combustion temperature of 800 ° C. or higher (actually 1000 ° C. or higher) was obtained continuously by incinerating the PCB mixed oil mixed with a saturated aqueous solution of hydroxide without auxiliary fuel. The higher the combustion temperature is, the more desirable it is that hydrocarbons do not remain. In practice, it is desirable to secure a combustion atmosphere of 1500 ° C. using auxiliary fuel.
[0030]
In the inventions of "Claim 1" and "Claim 2", after incineration of PCB-mixed oil, exhaust gas is removed by post-treatment, and incineration residue is subjected to conventionally known post-treatment such as landfill treatment. is there.
[0031]
【The invention's effect】
Since the present invention is as described above, it is possible to provide a method for treating PCB-mixed oil that can render the PCB-mixed oil, which is currently strictly stored and managed so as not to flow into the natural world, to be harmless or incinerated.
[0032]
In particular, the inventions of "Claim 1" to "Claim 2" use a conventional well-known incinerator and use auxiliary fuel for ignition only at the beginning of incineration. It is possible to provide a method for treating PCB-mixed oil that can be incinerated at an extremely low cost and that can prevent the natural release of dioxins.

Claims (2)

As the first step, water and surfactant are mixed in the PCB mixed oil and stirred to form an emulsion.
As a second step, a method for treating PCB-mixed oil, in which hydroxide is mixed with emulsified PCB-mixed oil and then injected into an incinerator and incinerated. As a first step, after mixing water with a volume ratio of 50 to 80% and an appropriate amount of surfactant into the oil mixed with PCB, stirring to make an emulsion,
As the second step, emulsified PCB-mixed oil and a saturated aqueous solution of hydroxide with a volume ratio of 50 to 200% are mixed with this emulsion and injected into an incinerator to be incinerated at 800 ° C. or higher. The processing method of the PCB mixed oil made.