KR100779528B1 - A practical method and apparatus for disposing pcbs in oil - Google Patents

Abstract

A method and an apparatus for treating oil contaminated with polychlorinated biphenyls in oil are provided to separate the polychlorinated biphenyls from the oil, by treating the oil chemically using alkaline reagent, alkaline material, and aluminum. A reactant mixture is prepared by adding a 5-25 w/w% of alkaline reagent, a 2-5 w/w% of alkaline material, and a 0.1-0.3 w/w% of aluminum into a 100 w/w% of oil contaminated with polychlorinated biphenyls in a reacting tank(110). The reactant mixture is heated to a predetermined temperature, and the heated reactant mixture is stirred by a stirring member(115). When the reactant mixture is passed through a filtering material of a filtering unit(120) during stirring the reactant mixture, the reactant is adsorbed to the filtering material.

Description

Polychlorinated biphenyls contaminated oil processing method and polychlorinated biphenyls contaminated oil processing apparatus used therein {A practical method and apparatus for disposing PCBs in oil}

1 is a schematic configuration diagram of a reactor unit in the PCBs contaminated oil treatment apparatus according to the present invention,

Figure 2 is a schematic configuration diagram of a combustor unit in the PCBs contaminated oil treatment apparatus according to the present invention.

<Description of Signs of Major Parts of Drawings>

100 ... reactor unit 110 ... reactor

111 ... first line 112 ... second line

115 ... Agitator 120 ... Filter

130 ... pump 140 ... reactor heater

150 ... nitrogen injection line 200 ... combustor unit

210 ... tube body 220 ... first connection

221 ... oxygen injection line 230 ... second connection

231 ... Exhaust gas line 240 ... Carbon fiber

The present invention relates to a practical method for treating contaminated oil of polychlorinated biphenyls (PCBs) and PCBs contaminated oil treatment apparatus used therefor.

Polychlorinated biphenyls (PCBs) are generic terms for 209 individual compounds, called analogues, which include from 1 to 10 chlorine atoms in two phenyl rings. Are combined. These polychlorinated biphenyls (PCBs) have been commercialized for over 40 years from 1930 to 1977, and are estimated to have produced 1.1x10 ⁹ kg worldwide, 93% of which were produced by Monsanto, USA. Complex compounds of PCBs manufactured by Monsanto were sold under the trade name Aroclor.

PCBs are not only chemically and thermodynamically stable, but also have high dielectric properties, making them mostly used as insulating oils in electrical appliances such as transformers and capacitors. However, PCBs have emerged as a representative environmental pollutant due to their enormous usage, indiscriminate form of disposal and their persistent environmental resistance. These PCBs are found in body organisms in marine life, fish, algae, terrestrial animals and, of course, humans, and in recent years have disrupted the transformation of natural hormones in living organisms, reducing the amount of sperm in males or males in females. It is known to act like a pseudo-hormone, which is replaced with.

As this environmental manifestation became evident, the US Federal Code of Toxic Substance Control Act (TSCA) was enacted in 1976 to regulate the PCBs, and similar legislation was enacted in the European Union. These laws prohibit the production, processing, commercial sale, or use of open systems in PCBs.

However, there are still many equipments that use PCBs, and it is reported that the United States and the European Community have about half a million transformers containing askarel (a dielectric fluid designated by the International Electrochemical Committee containing PCBs / Thenyl Trichloride). It is also estimated that more than 2 million transformers contain mineral oil or dielectric fluid containing PCBs concentrations above the content limits (25-50 ppm), which would be much higher if all of them were combined worldwide. will be.

Substances contaminated with PCBs are cross-contaminated in the manufacture of specific equipment and are generated by the process of treating, filling services, maintenance work, disposal and collection of dielectric fluids. And almost all (99%) of mineral oil contaminated with PCBs is 50-2,000 ppm, significantly exceeding the 25-50 ppm limit imposed by regulatory bodies. Therefore, contaminated oil on PCBs is a serious environmental problem. The most common method for removing these PCBs is high temperature incineration, in which transformer oil (polluted oil) contaminated with PCBs is poured into a rotary furnace and incinerated at high temperatures.

However, the above-mentioned high temperature incineration method is a simple method, but the processing cost is expensive, and because it destroys pollutants and even renewable materials (mineral oil, etc.), it is uneconomical due to the loss of resources that can be recycled. Furthermore, there was a problem that toxic substances such as dioxin or furan were generated as by-products during incineration.

The present invention has been made to solve the above problems, PCBs that can effectively separate (process and destroy) the PCBs from contaminated oil contaminated with the PCBs, PCBs that can recover renewable useful materials such as mineral oil It is an object of the present invention to provide a contaminated oil treatment method and a PCBs contaminated oil treatment apparatus used therefor.

Another object of the present invention is to provide a PCBs contaminated oil treatment method and a PCBs contaminated oil treatment apparatus used therein, which can prevent toxic substances such as dioxins and furans from occurring during the processing of PCBs.

In order to achieve the above object, the PCBs contaminated oil treatment method according to the present invention,

Preparing an reaction mixture by adding an alkaline reagent, an alkaline substance, and aluminum to the contaminated oil contaminated with PCBs (S11); Stirring the reaction mixture in a state where it is heated to a predetermined temperature (S12); And adsorbing PCBs to the filter medium by passing the reaction mixture through which the stirring is performed (S13).

In the present invention, the alkaline reagent is polyethylene glycol (PEG), lower alkyl ether of polyethylene glycol, trimethylene glycol, butylene glycol, lower alkyl ether of butylene glycol, 1,3-dimethyl-2-imide At least one selected from the group consisting of zolidinone, ethylene glycol, diethylene glycol, triethylene glycol; The alkaline substance is at least one selected from the group consisting of potassium hydroxide (KOH), sodium hydroxide and sodium alcoholate, potassium alcoholate and calcium hydroxide.

In the present invention, the content of the alkaline reagent is 5 to 25 w / w% with respect to the contaminated oil; The content of the alkaline substance is 2 to 5 w / w% based on the contaminated oil; The content of aluminum is 0.1 to 0.3 w / w% with respect to the contaminated oil.

In the present invention, the agitation is performed while the reaction mixture is heated in a range of 50 ° C to 150 ° C.

In the present invention, the chemical PCBs separation step (S10) is carried out in a nitrogen atmosphere in order to prevent the reaction mixture from being oxidatively decomposed by oxygen in the air.

In the present invention, the step of destroying and removing PCBs by using oxygen from the filter medium adsorbed PCBs, the oxygen flows through the filter medium from the upper side to the lower side, in this state the lower side of the filter medium Further comprising a countercurrent oxidation step (S20) for igniting.

In order to achieve the above object, the PCBs contaminated oil processing apparatus according to the present invention,

A reaction tank 110 in which a stirrer 115 is installed; A filter 120 filled with a filter for filtering the reaction mixture introduced from the reactor 110; A pump 130 for circulating the reaction mixture via the filter 120 into the reactor 110; A reactor heating unit 140 installed in the reactor 110 to heat the reaction mixture; And a nitrogen injection line 150 for injecting nitrogen into the reactor 110.

In the present invention, the filter is implemented by filling the container with at least one selected from activated carbon, nano carbon tube, zeolite.

In the present invention, from the filter medium taken out from the filter 120, to burn and destroy and remove the PCBs adsorbed to the filter medium, the tube body 210 is accommodated the filter medium adsorbed the PCBs, The first connection portion 220 is connected to the oxygen injection line 221 is injected into the upper portion of the tube body 210 and the exhaust gas is discharged as installed in the lower portion of the tube body 210 It includes a second connector 230 to which the exhaust gas line 231 is connected.

Hereinafter, a PCBs contaminated oil processing method and a PCBs contaminated oil processing apparatus used therein according to the present invention will be described in detail.

1 is a schematic configuration diagram of a reaction tank unit in the PCBs contaminated oil treatment apparatus according to the present invention, Figure 2 is a schematic configuration diagram of a combustor unit in the PCBs contaminated oil treatment apparatus according to the present invention.

PCBs contaminated oil treatment apparatus according to the present invention, the reaction tank unit 100, and a combustor unit 200.

The reactor unit 100, as shown in Figure 1, the stirrer 115 is installed, the reaction tank 110, the reaction mixture is accommodated; A filter 120 filled with a filter for filtering the reaction mixture introduced and installed in the first line 111 extending from the reactor 110; A pump 130 installed in the second line 112 between the filter 120 and the reaction tank 110 to circulate the reaction mixture via the filter 120 to the reaction tank 110; A reactor heating unit 140 installed in the reactor 110 to heat the reaction mixture; It includes; a nitrogen injection line 150 for injecting nitrogen into the reactor (110).

The material of the reactor 110 is not particularly limited, and glass such as pyrex, stainless steel, or the like is preferable.

The stirrer 115 serves to uniformly mix the reaction mixture accommodated in the reactor 110. Here, the stirrer 115 may be implemented in various ways such as a magnetic stirrer or a stirrer driven by the motor (M).

The filter 120 is a cylindrical container filled with a porous filter, for example, at least one selected from activated carbon, nano carbon tubes, and zeolites that can withstand high temperatures, and the lid can be filled in or taken out of the filter. Has The filter agent filled in the filter 120 adsorbs PCBs from a reaction mixture containing contaminated oil.

The reactor heating unit 140 is for heating the reaction mixture in the reactor 110. The reactor heating unit 140 may be variously implemented. For example, the reactor heating unit 140 may have a structure in which hot water flows around the reactor 110, and may be implemented by winding a heating wire outside the reactor 110. The reactor heating unit 140 is controlled by a temperature controller to control the temperature inside the reactor (110).

The nitrogen injection line 150 injects nitrogen into the reaction tank 110 to prevent oxidative decomposition of the reaction mixture, strictly contaminated oil. Nitrogen injected into the reactor 110 maintains the reactor 110 in a nitrogen atmosphere while the reaction is in progress, thereby preventing the reaction mixture from being oxidized in contact with oxygen in the air.

As shown in FIG. 2, the combustor unit 200 burns and processes (destroys and removes) PCBs adsorbed on the filter medium from the filter medium taken out from the filter 120 of the reaction tank unit 100. will be. To describe this in more detail, the combustor unit 200 is a tube main body 210 in which the PCBs adsorbed filter medium is accommodated, and an oxygen injection line 221 in which oxygen is injected as installed on the upper part of the tube main body 210. The first connection portion 220 is connected to the second connection portion 230, which is installed in the lower portion of the tube body 210, the exhaust gas line 231 to discharge the discharge gas is connected, and the tube body 210 inside As installed on the lower side in the carbon fiber 240 for supporting the activated carbon.

Here, the tube body 210 has an elongated tube shape made of quartz, and the first and second connection parts 220 and 230 connected to the upper and lower parts of the tube body 210 are made of stainless steel.

In the oxygen injection line 221, a pressure regulator 221a having a needle valve is installed to control the amount of oxygen injected into the tube body 210, and a rotational flow meter (not shown) is installed so that oxygen is constantly injected. It is. At this time, the flow rate of the injected oxygen is preferably about 60 ~ 600mL / min range. By this structure, oxygen injected into the oxygen injection line 221 flows from the upper side to the lower side of the tube body 210.

Next, the PCBs contaminated oil treatment method according to the present invention.

PCBs contaminated oil treatment method according to the present invention, chemical PCBs separation step (S10) for chemically separating the PCBs from the contaminated oil, and countercurrent oxidation step (S20) (COP-Counterflow to remove and destroy the chemically separated PCBs) Oxidation Process).

Chemical PCBs separation step (S10), the step of adding an alkaline reagent, an alkaline substance and aluminum to the contaminated oil contaminated with PCBs to prepare a reaction mixture (S11); Stirring the heated reaction mixture to a predetermined temperature (S12); It includes a step (S13) to adsorb the PCBs to the filter medium by passing the reaction mixture is agitated through the filter medium. This chemical PCBs separation step (S10) is carried out in a nitrogen atmosphere to prevent the reaction mixture, strictly contaminated oil, from being oxidized by oxygen in the air.

Preparing the reaction mixture (S12) is a step of mixing the alkaline reagent, the alkaline substance and aluminum to the PCBs contaminated oil.

The alkaline reagent may be polyethylene glycol (PEG), lower alkyl ether of polyethylene glycol, trimethylene glycol, butylene glycol, lower alkyl ether of butylene glycol, 1,3-dimethyl-2-imidazolidinone, ethylene glycol, At least one selected from the group consisting of diethylene glycol, triethylene glycol.

The alkaline substance consists of at least one selected from the group consisting of potassium hydroxide (KOH), sodium hydroxide, sodium alcoholate, calcium alcoholate, and calcium hydroxide.

Aluminum is used in the form of a powder, which can be spherical or plate-like. The average particle size of the spherical aluminum powder is between several microns and several hundred microns, and the size of the plate-shaped aluminum powder has an average length, width, and thickness of between several microns and several hundred microns, respectively. Since aluminum is chemically stable against substances containing active hydrogen such as water and alcohol, it is easy to handle and lowers operating costs during chemical treatment of contaminated oils including PCBs such as waste transformer oil.

Here, the alkaline reagent content depends on the degree of contamination of the PCBs contaminated oil, which is 5-25 w / w% when the PCBs are less than 1000 PPM. In addition, the content of alkaline substances is 2 to 5 w / w% with respect to the contaminated oil, and the content of aluminum is 0.1 to 0.3 w / w% with respect to the contaminated oil.

The alkaline reagent serves as a nucleophilic group that separates chlorine by attacking partially charged carbon of benzene in PCBs contaminated oil. Alkaline substances are used to make chemical reaction conditions basic. Aluminum (Al) is used as a dechlorination accelerator to increase the reaction rate of PCBs contaminated oil and is preferably in powder form. Aluminum is chemically stable with respect to substances containing active hydrogen such as water and alcohol, and thus is easy to handle, thereby lowering operating costs when chemically treating contaminated oils including PCBs such as waste transformer oil.

In the chemical PCBs separation step (S10), the stirring is performed while the reaction mixture is heated in a range of 50 ° C to 150 ° C. At this time, if the heating temperature of the reaction mixture is less than 50 ° C., the dechlorination reaction hardly occurs, and if it is above 150 ° C., the contaminated oil itself is heat-modified, which is not preferable. Specifically, the heating temperature is most preferably between 80 and 150 ℃.

The countercurrent oxidation step (S20) is a step of destroying and removing PCBs by using oxygen from the filter medium to which the PCBs are adsorbed. The oxygen flows through the filter medium from the upper side to the lower side, and the lower portion of the filter medium in this state. It is a step to light the side. In this case, the flame propagates in a direction opposite to the flow of oxygen, and the process destroys and removes PCBs adsorbed on the filter medium.

PCBs are thermally stable and require high temperatures for removal. Some researchers have found that PCBs are thermodynamically unstable above 800 ° C, both experimentally and theoretically. Therefore, to destroy the PCBs should be maintained at a temperature of at least 800 ℃, by the countercurrent oxidation step (S20) it is possible to implement a high temperature of 800 ℃ or more, thereby enabling the complete removal of the PCBs.

Meanwhile, a representative method of regenerating carbon adsorbed by pollutants is wet air oxidation (WAO). Moisture oxidation is mainly used when carbon contaminants evaporate below 150 ° C. However, this method of moisture oxidation is a method that consumes a lot of energy and is not practical when carbon has a very strong adsorption force or a toxic pollutant is adsorbed.

As such, moisture oxidation is not suitable for removing PCBs that are highly stable and toxic to heat. Applicant has invented the countercurrent oxidation step 20 (COP) to effectively remove the PCBs.

Hereinafter, the present invention will be described with reference to the following examples, and the scope of the present invention is not limited by the following examples.

EXAMPLE

Used PCBs Contaminated Oil, Alkaline Reagents, Alkaline Materials And Aluminum

In this embodiment, PCBs contaminated oil was extracted from a lung transformer and used the name Aroclor 1260 (PCBs mainly having 5 or 6 chlorine bound to a biphenyl frame). Here, the PCBs concentration of the used contaminated oil is 700 ppm.

Polyethylene glycol (PEG) was selected as the alkaline reagent, and potassium hydroxide was selected as the alkaline substance. In this case, the polyethylene glycol used is 10 w / w% with respect to the contaminated oil, potassium hydroxide is 3 w / w, aluminum is 0.2 w / w%.

Performing chemical PCBs separation step (S10)

In order to perform the chemical PCBs separation step, a reaction mixture was prepared by mixing PCB contaminated oil, polyethylene glycol (PEG), potassium hydroxide, and aluminum. After the reaction mixture was placed in the reactor 110, the reactor heating unit 140 was operated to inject nitrogen into the reactor 110 in a state in which the reaction mixture was heated to 80 ° C to 150 ° C to form a nitrogen atmosphere. Thereafter, the reaction mixture was stirred with the stirrer 115, and the pump 130 was operated to circulate the reaction mixture, which was stirred, through the filter 120 filled with activated carbon as a filter, to the reaction tank 110 again.

In the above state, stirring of the reaction mixture proceeds, and as the stirring proceeds, the reaction mixture gradually changes into a homogeneous mixture while homogeneously reacting. During this stirring process, the pump 130 circulated the reaction mixture 25 times per hour to pass through the filter 120. At this time, since the mineral oil constituting the contaminated oil is not dissolved, most (= 95%) is recovered from the reaction mixture. Through this series of processes, PCBs are adsorbed to the filter agent (activated carbon) filled in the filter 120.

Perform of countercurrent oxidation step (S20)

The combustor unit 200 performing the countercurrent oxidation step (S20) has a quartz tube having an inner diameter of 5 cm and a length of 45 cm, and the amount of oxygen injected into the oxygen injection line 221 is in the range of 60-600 mL / min. In the example, it was 100 mL / min.

In order to perform the countercurrent oxidation step (S20), take out the activated carbon adsorbed by the PCBs from the filter 120 and fill it in the tube body 210, while injecting oxygen from the oxygen injection line 221 tube body 210 with a thermal ignition mechanism Ignite the lower side of the Then, the flame combusted from the lower side of the tube body 210 rides up in the direction opposite to the flow direction of oxygen and destroys and removes the PCBs adsorbed to the filter medium.

Analysis of PCBs in Reactor Units

In performing the chemical PCBs separation step (S10), when the reaction mixture is circulated once through the filter 120, the contaminated oil is extracted from the reaction tank 110 for each process, and activated carbon is extracted from the filter 120 to remove PCBs. Was analyzed. As a result, the amount of PCBs detected in activated carbon and the amount of PCBs contained in the contaminated oil before circulating the contaminated oil from the reactor 110 were almost identical. This suggests that activated carbon is very effective in adsorbing PCBs from contaminated oil in the reaction mixture.

Analysis of PCBs in Combustor Units

When the countercurrent oxidation step (S20) was performed for the first time, 95.56% of PCBs adsorbed on activated carbon were removed (destroyed). This is due to the fact that the amount of PCBs adsorbed on the activated carbon did not burn in a constant manner. Subsequently, when the reverse flow oxidation step (S20) is performed again, the removal (destruction) efficiency of the PCBs becomes 97.59%, and when the reverse flow oxidation step (S20) is performed again, the removal (destruction) efficiency of the PCBs is considerably high, which is 99.99%. Appeared. According to these results, it was confirmed that PCBs can be completely removed (destroyed) in three repeated countercurrent oxidation steps (S20), and this countercurrent oxidation step (S20) proved to be a very effective heat treatment method for processing PCBs. .

On the other hand, there are reports that dioxins / furans were generated when incineration of PCBs in the presence of air. In the present invention, since the reverse flow oxidation step (S20) is combusted at 800 ° C. or higher, the dioxins / furans are separated from the exhaust gas. The same other toxic substances were not detected above the detection limit of 5 ppb. This is due to the very high flame temperatures and the presence of some amount of hydrogen that binds to the produced chlorine.

In addition, the efficiency of the countercurrent oxidation step (S20) may vary depending on how much the adsorption capacity of the activated carbon is restored while repeating the adsorption process of the PCBs. Therefore, we compared and observed the adsorption efficiency of PCBs when using new activated carbon to compare the adsorptive change of activated carbon and when using activated carbon regenerated by countercurrent oxidation (S20). As a result, the adsorption efficiency of fresh activated carbon and regenerated activated carbon was 95%. This indicates that the adsorption efficiency of the regenerated activated carbon was not significantly different compared to that of the new activated carbon, and further supported by the fact that there was no significant change in the surface area measured in the regenerated activated carbon after three consecutive cycles in the measurement of the surface area of the activated carbon. I'm doing it.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

As described above, the PCBs can be effectively separated from the contaminated oil through the chemical PCBs separation step (S10), and then the PCBs separated by the countercurrent oxidation step (S20) will completely remove and destroy the PCBs from the adsorbed filter medium. Could. In this process, toxic substances such as dioxin / furan have been proved to be very safe by detecting below the detection limit. In addition, by effectively separating the PCBs from contaminated oil, useful materials such as mineral oil can be recovered.

Claims (9)

Preparing an reaction mixture by adding an alkaline reagent, an alkaline substance, and aluminum to the contaminated oil contaminated with PCBs (S11); Stirring the reaction mixture in a state where it is heated to a predetermined temperature (S12); And The reaction mixture of the PCBs contaminated oil comprising a; (S13) to adsorb the PCBs to the filter by passing the reaction mixture through the filter. The method of claim 1, The alkaline reagent may be polyethylene glycol (PEG), lower alkyl ether of polyethylene glycol, trimethylene glycol, butylene glycol, lower alkyl ether of butylene glycol, 1,3-dimethyl-2-imidazolidinone, ethylene glycol, At least one selected from the group consisting of diethylene glycol, triethylene glycol; The alkaline substance is at least one selected from the group consisting of potassium hydroxide (KOH), sodium hydroxide, sodium alcoholate, potassium alcoholate and calcium hydroxide; PCBs contaminated oil treatment method. The method of claim 1, The alkaline reagent content is 5-25 w / w% with respect to the contaminated oil; The content of the alkaline substance is 2 to 5 w / w% based on the contaminated oil; The content of aluminum is PCBs contaminated oil treatment method, characterized in that 0.1 to 0.3 w / w% with respect to the contaminated oil. The method of claim 1, The stirring is PCBs contaminated oil treatment method characterized in that the reaction mixture is carried out in a heated state in the range of 50 ℃ ~ 150 ℃. The method of claim 1, The chemical PCBs separation step (S10), PCBs contaminated oil processing method characterized in that the reaction mixture is carried out in a nitrogen atmosphere to prevent the oxidative decomposition by oxygen in the air. 2. The method of claim 1, wherein the PCBs are destroyed and removed by using oxygen from the filter medium adsorbed thereon, wherein oxygen is flowed from the upper side to the lower side via the filter medium, and in this state, the lower portion of the filter medium. PCBs contaminated oil treatment method further comprising a countercurrent oxidation step (S20) for igniting the side. A reaction tank 110 in which a stirrer 115 is installed; A filter 120 filled with a filter for filtering the reaction mixture introduced from the reactor 110; A pump 130 for circulating the reaction mixture via the filter 120 into the reactor 110; A reactor heating unit 140 installed in the reactor 110 to heat the reaction mixture; And PCB contaminated oil processing apparatus comprising a; nitrogen injection line for injecting nitrogen into the reactor (110). The method of claim 7, wherein the filter agent, PCBs contaminated oil processing apparatus, characterized in that the container is filled with at least one selected from activated carbon, nano carbon tube, zeolite. The method of claim 7, wherein From the filter medium taken out from the filter 120, to burn, destroy and remove the PCBs adsorbed to the filter medium, the tube body 210 is accommodated for the filter medium adsorbed the PCBs and the tube body 210 The first connection portion 220 is connected to the oxygen injection line 221 is injected into the upper portion of the oxygen injection line 221, and the discharge gas line 231 is discharge gas is discharged as installed in the lower portion of the tube body 210 PCBs contaminated oil processing apparatus, characterized in that it comprises a second connecting portion 230 is connected.

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