JP6600219B2 - Hazardous substance extraction equipment - Google Patents

Description

  The present invention relates to an extraction apparatus and extraction method for harmful substances such as radioactive substances contained in an object to be treated such as incineration fly ash.

  A large amount of radioactive cesium diffused due to the nuclear power plant accident caused by the Great East Japan Earthquake. When the rubble generated by the earthquake (earthquake rubble) is incinerated, the handling of the rubble contains a high concentration of radioactive cesium.

  That is, incineration ash containing high-concentration radioactive cesium is generated when the earthquake debris containing high-concentration radioactive cesium is incinerated. On the other hand, incineration ash exceeding the reference value of 8,000 Bq / kg for the radiation dose determined by the special law cannot be landfilled. However, the amount of radiation of incineration ash generated by incineration of earthquake debris actually exceeds the standard value, and serious problems such as how to handle it and how to secure storage space Has occurred.

  In addition, although the processing method and apparatus of a radioactive waste are disclosed by patent document 1, the radioactive waste is solidified with cement and is not suitable for the safe processing of a large amount of earthquake rubble.

  Incinerated ash is classified into main ash and fly ash, but when the earthquake rubble containing radioactive cesium is incinerated, more radioactive cesium is contained in the fly ash than in the main ash. Therefore, Patent Document 2 proposes an apparatus and method for efficiently extracting radioactive substances contained in incineration fly ash. However, this is a method of extracting radioactive cesium in fly ash by a heater-type extraction method, and when treating a small amount of incineration fly ash, it is possible to efficiently extract radioactive substances contained in incineration fly ash. Although it was possible, it was unsuitable for processing a large amount of incinerated fly ash.

JP-A-9-101398 JP 2014-16336 A

  Therefore, the present invention makes it possible to efficiently extract harmful substances such as radioactive substances contained in the processing object such as incineration fly ash in a short time, and to safely dispose of a large amount of the processing object. An object of the present invention is to provide an extraction apparatus and extraction method for harmful substances.

The hazardous substance extraction apparatus according to the present invention includes an extraction means for extracting a harmful substance from an object to be processed. The extraction means contains a plurality of extraction reactors through which water vapor or hot water can circulate, and an object to be processed. A cartridge housed in the extraction reactor, and configured to be able to select and supply only steam, hot water, or both steam and hot water to the object to be treated. A heating means is provided in the reactor, and a heating steam is supplied to a jacket of the extraction reactor .

  According to the hazardous substance extraction apparatus of the present invention, the extraction means for extracting the harmful substance from the object to be treated is provided, and the extraction means is configured to be able to supply water vapor or hot water to the object to be treated, thereby incineration. It is possible to efficiently extract harmful substances such as radioactive substances contained in the processing object such as fly ash in a short time.

  Further, since the extraction means includes a plurality of extraction reactors through which water vapor or hot water can flow, the extraction apparatus can be continuously operated by using a plurality of extraction reactors alternately.

In addition, since the extraction means includes a cartridge that accommodates the object to be treated and is accommodated in the extraction reactor, the object to be treated can be easily stored and removed from the extraction reactor .

It is a flowchart which shows one Example of the extraction apparatus of the harmful substance of this invention. It is a schematic diagram which shows the mechanism in which a radioactive substance is isolate | separated from incineration fly ash by hydrothermal treatment. It is a graph which shows the result of extraction experiment. It is a flowchart which shows another Example of the extraction apparatus of the harmful | toxic substance of this invention.

  The hazardous substance extraction apparatus of the present invention can extract a hazardous substance contained in a treatment object efficiently and in a short time by subjecting the treatment object to steam extraction or hot water extraction. The harmful substances targeted by the present invention are radioactive substances, phosphorus, boron, heavy metals and their salts, and are not limited to specific substances. The radioactive material is typically radioactive cesium such as cesium 134 and cesium 137, but is not limited to a specific radioactive material.

  Hereinafter, the hazardous substance extraction apparatus of the present invention will be described in detail with reference to the accompanying drawings.

  First, the configuration of the hazardous substance extraction apparatus of this embodiment will be described. In the following description, incineration fly ash containing radioactive substances as hazardous substances and radioactive substances as objects to be treated will be described as an example.However, the hazardous substance extraction apparatus of this embodiment uses hazardous substances other than radioactive substances and incineration fly ash. It can also be applied to non-treated objects such as sludge and soil.

  In FIG. 1 showing the flow of the harmful substance extraction apparatus of this embodiment, 1 is a first reactor, and 2 is a second reactor. The first reactor 1 and the second reactor 2 have a vertical and substantially cylindrical shape and are hollow. In the first reactor 1 and the second reactor 2, cartridges 3, 4, and 5 containing incinerated fly ash are accommodated.

  The cartridges 3, 4, and 5 are suspended by carriers 6, 7, and 8, respectively, and are configured to be able to be transported into and out of the first reactor 1 and the second reactor 2. The cartridges 3, 4, and 5 are configured to hold incinerated fly ash and allow water vapor to flow inside and outside. These first reactor 1, second reactor 2, cartridges 3, 4, 5 and carriers 6, 7, 8 constitute an extraction means.

  In addition, boilers 11 are connected to the side surfaces of the first reactor 1 and the second reactor 2 via pipes 12 and 13, respectively, from the boiler 11 to the first reactor 1 and the second reaction. Steam is supplied to the vessel 2. A water storage tank 14 is connected to the boiler 11 via a liquid feed pump 15, a fuel tank 16 is connected via a fuel pump 17, and an air fan 18 that supplies air for fuel combustion is generated by combustion. An exhaust line 19 for exhausting the gas to be connected is connected. Further, a pressure reducing valve 20 is provided at a connection portion with the pipes 12 and 13. The boiler 11, the pipes 12 and 13, the storage tank 14, the liquid feed pump 15, the fuel tank 16, the fuel pump 17, the air fan 18, the exhaust line 19, and the pressure reducing valve 20 constitute a water vapor supply means.

  Further, inside the first reactor 1 and the second reactor 2, a space is provided below the cartridges 3, 4 and 5 for retaining hot water generated by condensation of water vapor, and incineration fly ash It is also possible to operate under the condition that is not immersed in hot water.

  On the other hand, a cooler 31 is connected to the bottoms of the first reactor 1 and the second reactor 2 via pipes 32 and 33, respectively, and the first reactor 1 and the second reactor 2 are connected. The water or steam discharged from the water is cooled. The cooler 31 is connected to a receiver 34 that receives the water cooled by the cooler 31. The cooler 31, the pipes 32 and 33, and the receiver 34 constitute a cooling means. The receiver 34 is connected to an adsorption means (not shown). The water in the receiver 34 is sent to the adsorption means, and the radioactive substance dissolved in water is adsorbed and separated by the adsorption means. In addition, an adsorption | suction means is not limited to a specific thing, For example, it can comprise with the column with which the adsorbent which adsorb | sucks a radioactive substance was packed.

  Next, the function and effect of the harmful substance extraction apparatus of this embodiment will be described.

In the boiler 11, water is supplied from the storage tank 14 by the liquid feed pump 15, and fuel is supplied from the fuel tank 16 by the fuel pump 17. Air for burning the fuel is supplied from an air fan 18. Then, water is heated by the combustion heat of the fuel, and steam is generated. The gas generated by the combustion of the fuel is exhausted from the exhaust line 19. Further, the pressure of the water vapor is adjusted to a predetermined pressure or less by the pressure reducing valve 20.

  On the other hand, incinerated fly ash containing radioactive material is accommodated in the cartridge 3, and the cartridge 3 is accommodated in the first reactor 1. Then, steam is supplied from the boiler 11 to the first reactor 1 via the pipe 12. In the first reactor 1, the steam supplied from the boiler 11 or the hot water generated by the condensation of the steam acts on the incinerated fly ash contained in the cartridge 3, and the radioactive material contained in the incinerated fly ash. Material is extracted. The radioactive material is separated from the incineration fly ash by the hydrothermal treatment performed by supplying the water vapor.

  Here, in general, hydrothermal treatment is a technique used in various fields such as chemical synthesis and crystal growth by specific chemical reaction of water under high temperature and high pressure, and is performed in a subcritical state of 260 ° C. and 4.5 MPa. Often. On the other hand, in a present Example, a hydrothermal reaction is performed in water vapor | steam atmosphere on milder conditions (for example, 150-200 degreeC, 1.0-1.5 MPa), and a radioactive substance is extracted to water from incineration fly ash. Is.

  FIG. 2 shows an example of the case where the radioactive substance is radioactive cesium, and shows the mechanism by which the radioactive substance is separated from the incineration fly ash by the hydrothermal treatment of this embodiment in comparison with the conventional water cleaning. In washing with water, radioactive cesium is released with the dissolution of water-soluble components such as calcium chloride and sodium chloride that are soluble at the treatment temperature, but the radioactive cesium strongly adsorbed on the incineration fly ash cannot be extracted into water. On the other hand, according to the hydrothermal treatment of this example, the Si—O-based structure of the incineration fly ash changes, so in addition to radioactive cesium that is desorbed along with dissolution of water-soluble components such as calcium chloride and sodium chloride, incineration Extraction of radioactive cesium strongly adsorbed to fly ash is possible. The structural change of incinerated fly ash after hydrothermal treatment can be confirmed by XRD measurement. The sodium salt crystal peak confirmed in untreated incinerated fly ash disappears after hydrothermal treatment, but after hydrothermal treatment. A non-existing crystal peak is observed before treatment.

  Returning to FIG. 1, in the cooler 31, water and water vapor discharged from the first reactor 1 via the pipe 32 are cooled, and the water cooled in the cooler 31 is guided to the receiver 34. The water in the receiver 34 is sent to an adsorption means (not shown), and the radioactive substance dissolved in the water is adsorbed and separated by the adsorption means.

  Before the hydrothermal treatment in the first reactor 1 is completed, the incinerated fly ash containing the radioactive substance is accommodated in the cartridge 4, and the cartridge 4 is accommodated in the second reactor 2. When the hydrothermal treatment of the radioactive material of the incinerated fly ash is completed in the first reactor 1, the hydrothermal treatment is started in the second reactor 2. The flow path of water vapor from the boiler 11 is switched from the pipe 12 to the pipe 13, and the flow path of water vapor to the cooler 31 is switched from the pipe 32 to the pipe 33.

  Before the hydrothermal treatment in the second reactor 2 is completed, the cartridge 3 of the first reactor 1 is replaced with a new cartridge 5 containing incinerated fly ash containing radioactive substances. When the hydrothermal treatment of the incinerated fly ash radioactive material is completed in the second reactor 2, the hydrothermal treatment is started in the first reactor 1.

  The cartridges 3, 4, 5 are suspended by carriers 6, 7, 8, respectively, and are transported into and out of the first reactor 1 and the second reactor 2.

  In this way, by performing switching between the first reactor 1 and the second reactor 2, hydrothermal treatment can be performed continuously.

  As described above, according to the hazardous substance extraction apparatus of the present embodiment, the first reactor 1 as the extraction means for extracting the radioactive substance as the harmful substance from the incinerated fly ash as the object to be treated, the second reactor 1 Reactor 2 and cartridges 3, 4 and 5 are provided, and this extraction means is configured to be able to supply water vapor to incineration fly ash as the object to be treated, so that it is included in the incineration fly ash as the object to be treated. It is possible to efficiently extract radioactive substances as harmful substances in a short time.

  Moreover, since the said extraction means was equipped with the 1st reactor 1 and the 2nd reactor 2 as a some extraction reactor which can distribute | circulate water vapor | steam, an extraction apparatus can be used by using several extraction reactors by turns. Can be operated continuously.

  The extraction means includes cartridges 3, 4, and 5 that contain incinerated fly ash as an object to be processed and are accommodated inside the first reactor 1 and the second reactor 2 as the extraction reactor. Since it was provided, the incineration fly ash as an object to be treated in the extraction reactor can be easily accommodated and detached.

  According to the hazardous substance extraction method of the present embodiment, a radioactive substance as a hazardous substance contained in the incinerated fly ash as the object to be treated is obtained by including a step of supplying water vapor to the incinerated fly ash as the object to be treated. Can be extracted efficiently in a short time. In addition, by treating the incineration fly ash as the object to be treated with water vapor, it is not necessary to dehydrate the incinerated fly ash as the object to be treated after the treatment. Furthermore, since it processes using water vapor | steam, it is not necessary to grind | pulverize the incineration fly ash as a to-be-processed object which the lump (for example, magnitude | size 1-10 cm) solidified beforehand.

  In addition, this invention is not limited to the said Example, A various deformation | transformation implementation is possible.

  A pilot plant having the configuration shown in FIG. Water vapor was supplied using a once-through small high-pressure steam boiler (2 MPa, 80 kg / H). The temperature inside the reactor was adjusted by a pressure reducing valve.

  An extraction experiment was conducted using actual fly ash from incineration facilities in A city and B city under Fukushima Prefecture. Here, the radioactive cesium residual rate was calculated by the following formula: radioactive cesium residual rate [%] = (radioactive Cs concentration of untreated fly ash / radioactive Cs concentration after treatment) × 100.

  The actual fly ash of City A is incineration fly ash generated in May 2012 from an incineration facility (fluidized bed type) in Fukushima Prefecture, and is chelated to prevent elution of heavy metals. As a result of treating incinerated fly ash containing radioactive cesium at 200 ° C. (1.5 MPa) for 2 hours, the concentration of radioactive cesium 5100 Bq / kg (Cs134, Cs137 combined) decreased to 309 Bq / kg. At this time, the residual ratio of radioactive cesium was 6%.

  The actual fly ash of B city had a higher radioactive cesium concentration than A city, which was 5910 Bq / kg. As a result of treating the incineration fly ash of B city under the same conditions as the incineration fly ash of A city, the radioactive cesium residual rate was 17%. For comparison, an extraction experiment was conducted using the conventional extraction method using the incineration fly ash of City B. The results are shown in FIG. The radioactive cesium residual rate when washed with water was 60%, and the radioactive cesium residual rate when treated with oxalic acid, phytoacetic acid, or ultrasonic waves was 60% or more. According to the method of the present invention, it was confirmed that radioactive cesium can be efficiently removed even for incinerated fly ash having a high concentration of radioactive cesium and a low water washing effect.

  FIG. 4 shows a flow of another embodiment of the hazardous substance extraction apparatus of the present invention. In addition, the same code | symbol is attached | subjected to the same part as the Example shown in FIG. 1, and the detailed description is abbreviate | omitted.

  In this embodiment, in addition to the configuration of the embodiment shown in FIG. 1, hot water can be supplied from the hot water supply means to the first and second reactors 1 and 2.

  Hereinafter, the hot water supply means will be described.

  The hot water supply means includes a hot water tank 41, and the hot water tank 41 is provided with a steam inlet valve 42 for taking in steam from the boiler 11. And the water in the hot water tank 41 is heated by the steam taken in from the steam inlet valve 42 to produce hot water. Further, the hot water tank 41 is provided with a hot water outlet main valve 43, which is provided from the hot water tank 41 via the pipes 44 and 45 and above the first and second reactors 1 and 2, respectively. Hot water is supplied to the first and second reactors 1 and 2 through hot water inlet valves 46 and 47.

  Further, the hot water tank 41 is provided with a pressure equalizing original valve 48, and this pressure equalizing original valve 48 is provided above the first and second reactors 1 and 2 via pipes 49 and 50, respectively. The pressure equalizing valves 51 and 52 are connected. An air vent valve 53 is connected to the pipes 49 and 50 connecting the pressure equalizing source valve 48 and the pressure equalizing valves 51 and 52. Thereby, the pressure of the hot water tank 41 and the pressure of the hot water in the first and second reactors 1 and 2 are kept substantially constant, respectively.

  In addition, the hot water tank 41 is provided with a liquid level meter 54 and a plurality of thermometers 55 and 56. Water is supplied from the water storage tank 57 to the hot water tank 41. In addition, heating steam is supplied from the boiler 11 to a steam pipe 58 provided in the hot water tank 41.

  In this embodiment, in addition to the configuration of the embodiment shown in FIG. 1, the first and second reactors 1 and 2 are provided with heating means. That is, from the boiler 11 via the pipes 61 and 62, through the steam inlet valves 63 and 64 provided at the lower portions of the first and second reactors 1 and 2, respectively, the first and second reactors 1, 2 is supplied with steam for heating. The heating steam is supplied to the jackets of the first and second reactors 1 and 2, and is supplied into the first and second reactors 1 and 2 in which the cartridges 3 and 4 are accommodated. Not to be.

  Next, the function and effect of the harmful substance extraction apparatus of this embodiment will be described.

  Steam is taken into the hot water tank 41 from the boiler 11 via the steam inlet valve 42, and the water in the hot water tank 41 is heated to produce hot water. The hot water produced in the hot water tank 41 passes from the hot water outlet main valve 43 via the pipe 44 and through the hot water inlet valve 46 provided on the upper part of the first reactor 1, respectively. 1 is supplied.

  In the first reactor 1, hot water supplied from the hot water tank 41 acts on the object to be processed accommodated in the cartridge 3, and harmful substances contained in the object to be processed are extracted. By the hydrothermal treatment performed by supplying this hot water, harmful substances are separated from the object to be treated. Also in this example, the hydrothermal reaction is performed under mild conditions of, for example, 150 to 200 ° C. and 1.0 to 1.5 MPa. The pressure of hot water in the first reactor 1 is kept substantially constant by the pressure equalizing valve 51. Further, the steam for heating is supplied to the first reactor 1 from the boiler 11 through the pipe 61 and through the steam inlet valve 63 provided at the lower part of the first reactor 1.

  Instead of supplying hot water from the hot water tank 41, or simultaneously with supplying hot water from the hot water tank 41, steam is supplied from the boiler 11 to the first reactor 1 via the pipe 12. May be. Temperature or pressure can be easily adjusted by supplying hot water and steam in combination, or by supplying either hot water or steam.

  As described above, according to the harmful substance extraction apparatus of the present embodiment, the extraction means can select and supply only water vapor, only hot water, or both water vapor and hot water to the object to be processed. As a result, the temperature and pressure can be easily adjusted.

1 First reactor (extraction means, extraction reactor)
2 Second reactor (extraction means, extraction reactor)
3, 4, 5 cartridge (extraction means)

Claims (1)

Extraction means for extracting harmful substances from the object to be treated is provided. The extraction means contains a plurality of extraction reactors through which water vapor or hot water can circulate, and contains the object to be treated and is accommodated in the extraction reactor. A cartridge, and configured to be able to select and supply only water vapor, only hot water, or both water vapor and hot water to the object to be processed, and the extraction reactor is provided with heating means, An apparatus for extracting harmful substances, characterized in that heating steam is supplied to a jacket of an extraction reactor .