JP6953152B2 - Dioxin removal method - Google Patents

Description

The present invention relates to a dioxin removing method, and more particularly to a dioxin removing method for removing dioxin adhering to the surface of a structure such as a wall or ceiling.

Conventionally, when dismantling an incinerator such as a waste incinerator or when maintaining an incinerator, a pollutant containing dioxins (hereinafter, simply referred to as dioxins) generated in the incinerator process and adhering to the wall surface of the furnace. Is removed. To remove such pollutants, the injection nozzle for injecting high-pressure water and the rotating brush are covered with an outer peripheral cover, and the rotating brush is rotated while pressing the outer peripheral cover against the wall surface to inject high-pressure water toward the wall surface. The adhering pollutants were removed, the water in the outer cover was sucked by a vacuum hose and collected in a tank, and the collected wastewater containing dioxin was collected by a pump or the like and sent to a wastewater treatment plant for treatment.

Japanese Unexamined Patent Publication No. 2005-254156

However, when removing pollutants from the wall surface by injecting high-pressure water, even if the work is done while covering the work area with a cover, the work must be done while mist containing dioxin is flying, which is a preferable work environment. I can't say. In addition, the work becomes large-scale because it is necessary to secure a water source for cleaning, prepare a high-pressure water generator, a drainage facility, and the like. In addition, after the work, it is necessary to treat the wastewater containing dioxin, which causes a problem that a lot of labor is required.
Therefore, in order to solve the above problems, it is an object of the present invention to propose a dioxin removing method for removing dioxin by a simple method.

The dioxin removing method according to the present invention is a dioxin removing method for removing dioxin adhering to the surface of an object to be removed, and an adsorbed solution in which an adsorbent is dispersed in a solvent as a fine powder having a particle size of 100 μm or less is removed. Adsorption solution to be applied to the surface of the object Adsorption solution to attach the adsorbent adsorbed by dioxin to the surface of the object to be removed by drying the adsorption solution applied to the object to be removed and vaporizing the solvent. By applying the solvent used to disperse the adsorbent to the adsorbent adsorbed by the dioxin adsorbed on the surface of the object to be removed in the drying step, the adsorbent adsorbed on the surface of the object to be removed is removed. It includes a solvent coating step of suspending and dispersing with a solvent again, and an adsorbent removing step of sucking and removing the adsorbent adhering to the surface of the object to be removed by a suction device after the solvent is dried. ..
According to this embodiment, dioxins can be removed from the surface of the object to be removed by a simple step of applying an adsorbent solution, drying, applying a solvent, drying, and sucking an adsorbent by an adsorbing device.
Further, by using activated carbon as the adsorbent, dioxins can be efficiently adsorbed.
Further, by using a low-polarity solvent as the solvent, it is possible to prevent the solvent of the adsorbent solution applied to the surface of the object to be removed from reacting with water or the like to cause uneven dispersion of the adsorbent on the surface.
Further, by mixing the dispersant with the adsorbent solution, the adsorbent can be uniformly dispersed in the solvent in the adsorbent solution before coating, and the adsorbent can be uniformly dispersed in the solvent even after coating.

It is a figure which shows the dioxin removal process. It is a graph which shows the test result of dioxin removal in a cleaning factory. It is a figure which shows the other form of the dioxin removal process. It is a figure which shows the other form of the dioxin removal process. It is a figure which shows the other form of the dioxin removal process.

FIG. 1 is a process chart of a dioxin removing method. As shown in the figure, in the dioxin removing method according to the present embodiment, an adsorbent solution in which an adsorbent is dispersed in a solvent is applied to the surface of an object to be removed of dioxin (S202), and the adsorbed solution is dried (S204). ). The removal target, for example, the wall of the incinerator in waste incineration plants and sewage treatment plants, etc., floor, front surface of the structure such as a ceiling, the inner and outer surfaces of plant equipment, or surfaces, such as falling objects rubble etc. Can be mentioned. As a result, the dioxin adhering to the surface of the object to be removed can be suspended in the adsorbent solution and adsorbed by the adsorbent contained in the adsorbent solution. Then, the adsorption solution is dried, by vaporizing the solvent, the adsorbent dioxin is adsorbed can be attached on the front surface. The drying of the adsorption solution includes a semi-dry state in which the solvent has not completely evaporated.
Next, the solvent used for dispersing the adsorbent is applied onto the dried adsorbent solution (S206) and dried (S208). By applying the solvent toward the adsorbent adhering to the surface in this way, the adsorbent adhering to the surface can be suspended again by the solvent and uniformly dispersed, so that the dioxin remaining on the surface can be further reduced. It can be adsorbed with an adsorbent, and the adsorbent can be adhered to the surface by drying the applied solvent.
Next, the adsorbent adhering to the surface is sucked and removed by a suction device (S210). By sucking the adsorbent adhering to the surface with a device such as a vacuum cleaner that generates negative pressure and sucking it, and removing and collecting it from the surface, the adsorbent adsorbing dioxin is not scattered around. , Dioxins adhering to the surface can be removed.
The adsorbent containing dioxin recovered by the suction device is stored in a closed tank and incinerated at a temperature at which dioxin can be decomposed in an incinerator to be detoxified.

According to this embodiment, since high-pressure water is not sprayed as in the conventional case, it is not necessary to prepare a high-pressure pump or secure a water source for the work. In addition, since water containing dioxin due to spraying high-pressure water does not scatter during work, curing of the work range can be simplified and protective clothing for workers can be simplified, so that the work environment can be improved.

As the solvent used for the adsorption solution, other volatile organic solvents (liquefied hydrocarbons) such as alcohol and n-heptane can be used alone or in combination. Preferably, low polarity ones such as n-heptane, n-hexane, cyclohexane and the like are preferable.
Adsorbents include activated charcoal, pearlite, silicon dioxide, magnesium oxide, magnesium carbonate, magnesium hydroxide, aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium carbonate, calcium oxide, calcium hydroxide, fine powder of calcium carbonate, and these. A mixture of fine powders and the like can be used. Preferably, it is a fine powder having a particle size of 100 μm or less.

[Example]
In order to verify the effect of the dioxin removal method according to the present embodiment, dioxin removal tests were conducted at a total of four locations, an incinerator, a drainage pit, an incentive blower, and a chimney in a cleaning plant.

The adsorbent solution uses a fine powder of activated carbon having a particle size of 100 μm or less as an adsorbent, and a mixture of alcohol and n-heptane in a solvent is used. ) Was added to construct an activated carbon adsorption solution.
The blending ratio (% by weight) of the activated carbon adsorption solution was activated carbon adsorption solution: activated carbon 6.9%, alcohol 68.3%, n-heptane 22.8%, and dispersant 1.9%. Then, the activated carbon adsorption solution was filled in a spray can and applied by spraying.
Further, as the solvent used in the solvent coating step, only n-heptane among the solvents constituting the adsorption solution was filled in a spray can and coated by spraying.

A test range of 30 cm x 30 cm was set on each wall surface of the incinerator, drainage pit, incentive blower, and chimney, an activated carbon adsorption solution was applied, the activated carbon adsorption solution was dried, and then a solvent consisting of n-heptane was dried. The activated carbon was overcoated with the activated carbon adsorption solution, and after the solvent was dried, the activated carbon adhering to the wall surface was sucked by a suction device and removed from the wall surface.
Then, the dioxin concentration in the test range before the work was compared with the dioxin concentration after the work.
FIG. 2 is a graph summarizing the test results. The toxic equivalent (TEC) on the vertical axis is divided by the test area, and the unit is pg-TEC / L · cm2. The toxicity equivalent is the measured concentration multiplied by the toxicity equivalence factor (TEF). It can be seen that dioxins are removed in all of the incinerator, drainage pit, incentive blower, and chimney.
The blending ratio of the adsorbent, the solvent, and the dispersant constituting the adsorbent solution is an example, and can be appropriately changed depending on, for example, the amount of dioxin adhering to the wall surface.

As another embodiment of the dioxin removing method, for example, as shown in FIG. 3, before performing S202 to S208, the adhesion concentration of dioxin on the wall surface is measured (S102), and the number of times S202 to S210 is repeatedly performed is set. (S104) may be used.
Then, one cycle consisting of application of the adsorbent solution shown in S202 to S210, drying of the adsorbent solution, application of the solvent, drying of the solvent, and removal of the adsorbent is executed a number of times set in S104. That is, after S210, the process is executed while confirming how many times the steps S202 to S210 have been repeated as S211.

Further, as shown in FIG. 4, the steps of applying the adsorption solution and drying the adsorption solution shown in S202 and S204 may be executed as many times as the number of times set in S104. For example, the number of repetitions shown in FIGS. 3 and 4 can be set by measuring the adhesion concentration of dioxins on the wall surface (S102) and setting based on the adhesion concentration (S104).
The number of repetitions may be determined in advance by an experiment or the like regarding the relationship between the wall material, the type of adsorbent, and the concentration of the adsorbent in the adsorbent solution.

For example, when the amount of activated carbon contained in the adsorption solution applied for the first time in S202 is 6.9% and S202 and S204 are repeated three times, 6.9% of the amount of the first activated carbon is repeated for 3 times. Prepare an adsorption solution so that the value divided by is decreased by 2.3%, and add an adsorption solution containing activated carbon of 6.9% for the first time, 4.6% for the second time, and 2.3% for the third time. It may be applied.
In this way, by reducing the amount of activated charcoal contained in the adsorbent solution each time the adsorbent solution is repeatedly applied, the adsorbent adhering to the wall surface in a dry state is dispersed by the newly applied adsorbent solution. Since the density of the adsorbent adsorbing on the wall surface can be gradually increased, more dioxin including the dioxin adsorbing on the recesses such as fine holes formed on the wall surface can be adsorbed on the adsorbent. That is, the recovery rate of dioxins from the wall surface can be improved.

Further, in the steps of S210 of FIGS. 1, 3 and 4, a step of applying a resin-based paint to the wall surface after the treatment of S210 (S302) and a step of drying the resin-based paint (S304). After the resin-based paint is dried, a step (S306) of peeling the dried resin-based paint from the wall surface and removing it from the wall surface may be added. By treating in this way, dioxin adhering to the wall surface can be efficiently removed.
As the resin-based paint, for example, phenol resin, alkyd resin, melamine resin, epoxy resin, urethane resin, silicon resin, vinyl chloride resin, vinyl acetate resin, fluororesin, cellulose and the like can be used, and an aqueous vinyl resin paint can be used. Is preferable.
The resin-based paint can be applied using, for example, a painting roller or the like.

As described above, according to the dioxin removing method according to the present embodiment, the working environment can be improved because the worker can work in a dry environment without the need for water or a large-scale device.
In addition, since the adsorption solution or solvent is only sprayed on the wall surface during the work, the work can be performed without suspending the dioxin adhering to the wall surface in the atmosphere.
Then, since the adsorbent adsorbed on the wall surface with the dioxin adsorbed is sucked by the suction device and recovered, the work can be performed without scattering the adsorbent adsorbing the dioxin to the surroundings.

Claims (4)

It is a dioxin removal method that removes dioxins adhering to the surface of the object to be removed.
An adsorption solution coating step of applying an adsorption solution in which an adsorbent is dispersed in a solvent as a fine powder having a particle size of 100 μm or less is applied to the surface of the object to be removed.
An adsorption solution drying step of drying the adsorption solution applied to the object to be removed and vaporizing the solvent to attach the adsorbent adsorbed by dioxin to the surface of the object to be removed.
By applying the solvent used for dispersing the adsorbent to the adsorbent adsorbed by the dioxins adsorbed on the surface of the object to be removed, the adsorption adsorbed on the surface of the object to be removed. A solvent application process in which the agent is suspended and dispersed again with a solvent,
After the solvent has dried, the adsorbent removing step of sucking and removing the adsorbent adhering to the surface of the object to be removed by a suction device, and
Dioxin removal method including. The dioxin removing method according to claim 1, wherein the adsorbent is activated carbon. The dioxin removing method according to claim 1 or 2, wherein the solvent is a low-polarity solvent. The dioxin removing method according to any one of claims 1 to 3, wherein a dispersant is mixed with the adsorption solution.

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