JP2018153761A - Dioxin removal method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a dioxin removal method for removing dioxins with a simple method.SOLUTION: A dioxin removal method for removing dioxins attached to a surface of a removal object includes: an adsorption solution coating step for coating, on a surface of the removal object, adsorption solution in which an adsorption agent is dispersed in solvent as impalpable powder having a particle diameter of 100 μm or less; an adsorption solution drying step for drying the adsorption solution coated on the removal object; a solvent coating step for coating the solvent used for dispersion of the adsorption agent on the adsorption solution after drying; and an adsorption agent removal step for removing by sucking, by a suction apparatus, the adsorption agent attached to the surface of the removal object after drying the solvent.SELECTED DRAWING: Figure 1

Description

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

  Conventionally, when dismantling an incinerator such as a waste incineration plant or maintaining an incinerator, pollutants including dioxins (hereinafter simply referred to as dioxins) generated during the incineration process and adhered to the wall surface of the incinerator Is removed. In removing such pollutants, the outer peripheral cover covers the injection nozzle and the rotating brush that inject high-pressure water, and the high-pressure water is injected toward the wall while rotating the rotating brush while pressing the outer cover against the wall. The adhering contaminants were removed, the water in the outer cover was sucked with a vacuum hose and collected in a tank, and the collected dioxin-containing wastewater was collected with a pump and sent to a wastewater treatment plant.

JP 2005-254156 A

However, when removing contaminants from the wall surface by injecting high-pressure water, even if the work area is covered with a cover, the work must be performed while the mist containing dioxin is dancing, I can't say that. In addition, in the work, it is necessary to prepare a water source for washing, a high-pressure water generator, a drainage facility, and the like, so that the work becomes large. In addition, there is a problem that after work, wastewater containing dioxins must be treated, which requires a lot of labor.
Then, in order to solve the said subject, it aims at proposing the dioxin removal method which removes a dioxin by a simple method.

The dioxin removal method according to the present invention is a dioxin removal method for removing dioxins adhering to the surface of an object to be removed, wherein an adsorption solution in which an adsorbent is dispersed as a fine powder having a particle size of 100 μm or less is removed. Adsorbing solution application process for applying to the surface of the object, Adsorbing solution drying process for drying the adsorbing solution applied to the object to be removed, and a solvent for applying the solvent used for dispersing the adsorbent on the adsorbing solution after drying An application step and an adsorbent removing step of removing the adsorbent adhering to the surface of the object to be removed by sucking with a suction device after the solvent is dried are included.
According to this embodiment, dioxins can be removed from the surface of the object to be removed by a simple process of applying an adsorbing solution, drying, applying a solvent, drying, and sucking an adsorbent by an adsorbing device.
Moreover, dioxins can be efficiently adsorbed by using activated carbon as the adsorbent.
In addition, by using a low-polar solvent as the solvent, it is possible to suppress the occurrence of unevenness in the dispersion of the adsorbent on the surface due to the reaction of the solvent of the adsorption solution applied to the surface of the removal target with water or the like.
Moreover, by mixing a dispersing agent with an adsorption solution, an adsorption agent can be uniformly disperse | distributed to a solvent in the adsorption solution before application | coating, and an adsorption agent can be uniformly disperse | distributed to a solvent after application | coating.

It is a figure which shows a 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 a dioxin removal process. It is a figure which shows the other form of a dioxin removal process. It is a figure which shows the other form of a dioxin removal process.

FIG. 1 is a process diagram of a dioxin removal method. As shown in the figure, in the dioxin removal method according to this embodiment, an adsorption solution in which an adsorbent is dispersed in a solvent is applied to the surface of a dioxin removal target (S202), and the adsorption solution is dried (S204). ). Examples of objects to be removed include the walls of incinerator walls, floors, ceilings, and other structures in waste incineration plants and sewage treatment plants, the inner and outer surfaces of plant equipment, and the surface of falling objects such as rubble. It is done. Thereby, dioxin adhering to the surface of the removal target can be suspended in the adsorption solution and adsorbed on the adsorbent contained in the adsorption solution. The adsorbent adsorbed with dioxin can be adhered to the wall surface by drying the adsorbed solution and vaporizing the solvent. The drying of the adsorbed solution includes a semi-dry state where the solvent is not completely evaporated.
Next, the solvent used for dispersing the adsorbent is applied onto the dried adsorption 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 by the solvent again and uniformly dispersed, so that dioxins remaining on the surface can be further dispersed. 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 removed by suction with a suction device (S210). The adsorbent adhering to the surface in this way is sucked with a vacuum suction device such as a vacuum cleaner and removed from the surface, and the adsorbent adsorbed with dioxin is scattered without being scattered around the surface. Dioxins adhering to the surface can be removed.
The adsorbent containing dioxin recovered by the suction device is stored in a sealed tank and incinerated at a temperature capable of decomposing dioxin in an incineration facility, and is rendered harmless.

  According to the present embodiment, high pressure water is not sprayed as in the prior art, so that it is not necessary to prepare a high pressure pump or secure a water source for the work. Moreover, since water containing dioxin by spraying high-pressure water does not scatter during work, the work range can be simplified and the protective clothing of the worker 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. Preferred are those having a low polarity such as n-heptane, n-hexane, cyclohexane and the like.
Adsorbents include activated carbon, perlite, silicon dioxide, magnesium oxide, magnesium carbonate, magnesium hydroxide, aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium carbonate, calcium oxide, calcium hydroxide, calcium carbonate fine powder, and these A mixture of fine powders can be used. Preferably, a fine powder having a particle size of 100 μm or less is preferable.

[Example]
In order to verify the effect of the dioxin removal method according to the present embodiment, a dioxin removal test was conducted at a total of four locations: an incinerator, a drain pit, an incentive blower, and a chimney in a cleaning factory.

For the adsorption solution, a fine powder of activated carbon having a particle size of 100 μm or less is used as an adsorbent, and a mixture of alcohol and n-heptane is used in the solvent. A dispersant (surfactant) is used to uniformly disperse the adsorbent in the solvent. ) Was added to form an activated carbon adsorption solution.
The mixing 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%. The activated carbon adsorbing solution was filled in a spray can and applied by spraying.
Moreover, the solvent used for a solvent application | coating process filled the spray can only with n-heptane of the solvent which comprises adsorption solution, and apply | coated with the spray.

A test range of 30 cm × 30 cm was set on each wall of the incinerator, drain pit, incentive blower, and chimney, and the activated carbon adsorbed solution was applied and the activated charcoal adsorbed solution was dried, followed by drying the solvent consisting of n-heptane The activated carbon adsorption solution was overcoated, 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.
And the dioxin density | concentration in the test range before work was compared with the dioxin density | concentration after work.
FIG. 2 is a graph summarizing the test results. In addition, the toxicity equivalent (TEQ) on the vertical axis is divided by the test area, and the unit is pg-TEQ / L · cm 2. Toxicity equivalent is the measured concentration multiplied by the toxicity equivalent factor (TEF). It can be seen that dioxins are removed in any of the incinerator, drain pit, incentive blower, and chimney.
Note that the mixing ratio of the adsorbent, the solvent, and the dispersant constituting the adsorbing solution is an example, and can be appropriately changed according to, for example, the amount of dioxin adhering to the wall surface.

As another embodiment of the dioxin removal 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 repeated is set. (S104) may be used.
Then, one cycle including the application of the adsorbing solution, the drying of the adsorbing solution, the application of the solvent, the drying of the solvent, and the removal of the adsorbent shown in S202 to S210 is executed the number of times set in S104. That is, after S210, it is executed while confirming how many times the steps S202 to S210 have been repeated as S211.

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

For example, when the amount of activated carbon contained in the adsorption solution applied for the first time in S202 is set to 6.9% and S202 and S204 are repeated three times, 6.9% of the amount of the activated carbon for the first time is 3 times the number of repetitions. Prepare an adsorption solution so as to decrease by 2.3% of the value divided by 1. In the first time, prepare an adsorption solution containing 6.9% activated carbon, 4.6% in the second time, 2.3% in the third time, and 2.3% activated carbon in the third time. You may make it apply | coat.
In this way, by reducing the amount of activated carbon contained in the adsorption solution every time the adsorption solution is repeatedly applied, while dispersing the adsorbent adhering to the wall surface in a dry state with the newly applied adsorption solution, Since the density of the adsorbent adhering to the wall surface can be gradually increased, more dioxin including dioxin adhering to concave portions such as fine holes formed on the wall surface can be adsorbed to the adsorbent. That is, the recovery rate of dioxin from the wall surface can be improved.

Also, in the step of S210 in FIGS. 1, 3 and 4, a step of applying a resin-based paint on the wall surface after the processing of S210 (S302) and a step of drying it (S304). After drying the resin-based paint, a step of removing the dried resin-based paint from the wall surface and removing it from the wall surface (S306) may be added. By processing in this way, dioxins adhering to the wall surface can be efficiently removed.
For example, phenol resin, alkyd resin, melamine resin, epoxy resin, urethane resin, silicon resin, vinyl chloride resin, vinyl acetate resin, fluororesin, cellulose, etc. can be used as the resin-based paint. Is preferred.
Application | coating of a resin-type coating material can be performed using a painting roller etc., for example.

As described above, according to the dioxin removal method according to the present embodiment, the operator can work in a dry environment without requiring water or a large-scale device, and thus the work environment can be improved.
In addition, since the adsorption solution or solvent is only sprayed on the wall surface during the work, the work can be performed without causing the dioxin adhering to the wall surface to float in the atmosphere.
And since the adsorbent adhering to the wall surface with the dioxin adsorbed is sucked and collected by the suction device, the work can be performed without scattering the adsorbent adsorbed dioxin to the surroundings.

Claims (4)

A dioxin removal method for removing dioxins adhering to the surface of an object to be removed,
An adsorbent solution coating step in which an adsorbent solution in which a solvent is dispersed as a fine powder having a particle size of 100 μm or less in a solvent is applied to the surface of the removal object;
An adsorption solution drying step of drying the adsorption solution applied to the object to be removed;
A solvent application step of applying the solvent used for dispersing the adsorbent on the adsorbed solution after drying;
A dioxin removal method comprising: an adsorbent removal step of removing the adsorbent adhering to the surface of the object to be removed by suction with a suction device after the solvent is dried.   2. The dioxin removal method according to claim 1, wherein the adsorbent is activated carbon.   The dioxin removal method according to claim 1 or 2, wherein the solvent is a low polarity solvent.   The dioxin removal method according to any one of claims 1 to 3, wherein a dispersing agent is mixed in the adsorption solution.

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