JP4977916B2 - Radioactive waste treatment equipment - Google Patents

Description

The present invention relates to an apparatus for incineration of combustible radioactive waste using a high-frequency heating furnace for reducing the volume by heating and melting noncombustible radioactive waste, and oxygen is sufficiently absorbed by a natural air flow. There is no need to attach additional equipment for incineration to the induction furnace so that it is supplied and burned completely, and unburned carbon does not remain in the incineration ash as much as possible. With respect to the volume reduction by heating and melting together with the waste, the melting process can be made easy and easy.
The above-mentioned “flammable radioactive waste” is mainly cloth, cotton, paper, wood, vinyl acetate, vinyl chloride, polyethylene, neopropylene rubber, acrylic resin, ion exchange resin, and the like.

  In order to reduce the volume of incombustible radioactive waste and combustible radioactive waste discharged from nuclear facilities such as nuclear power plants, separate them and incinerate combustible radioactive waste. Is generally melted by high-frequency heating (hereinafter, “radioactive waste” is abbreviated as “waste”). In contrast, combustible waste and incombustible waste are not separated, incinerated in combustible waste in a high-frequency furnace, and the incinerated ash is heated and melted together with incombustible waste, so that radioactive waste Are simplified (JP-A-7-260119 (Patent Document 1), JP-A-11-271495 (Patent Document 2)). In both Patent Document 1 and Patent Document 2, the canister is electrically conductive and itself is heated at a high frequency to become a high temperature, combusting the combustible waste put in it, and then The incombustible waste is put into the canister, and the incombustible waste is heated and melted together with the incinerated ash.

The thing of patent document 1 is equipped with the air supply nozzle, blows air in the said canister, burns flammable waste in a canister, and heat-melts nonflammable waste to reduce these volumes This is processed (hereinafter referred to as prior art 1). In this case, the air supply amount is controlled by the control device to an optimum amount corresponding to the state of the furnace such as the oxygen concentration, but the bottom of the canister is in a state where the air is not reachable and oxygen is insufficient. A large amount of unburned carbon remains in the incineration ash accumulated in the ash. For this reason, when the incinerated ash is mixed and the incombustible waste is heated and melted, the incinerated ash floats on the surface of the molten metal, and is melted and solidified while containing a large amount of unburned carbon. . The prior art of Patent Document 2 aims to completely burn unburned carbon in the incinerated ash when the incombustible waste is heated and melted (hereinafter referred to as Prior Art 2).
In the prior art 2, as shown in FIG. 3, a flame 104 a is radiated by a burner 104 on the upper surface of the molten metal in the canister 103.

Since the prior art 2 is incinerated in the canister 103, the combustion zone 114 is provided in the upper part of the high-frequency heating furnace 100, and the air supply nozzle is detected while detecting the oxygen concentration in the combustion zone 114. At 115, air is blown. On the other hand, when the canister 103 is mounted in the high-frequency heating furnace 100, combustible waste and non-combustible waste are respectively input from the input port 112. After the combustible waste is incinerated in the canister 103 and the incombustible waste is melted and solidified, the canister 103 is taken out from the high-frequency heating furnace 100.
Since the combustible waste is incinerated in the same canister 103 and the incombustible waste is heated and melted, the handling is simpler than those in which these incineration and heat melting are performed separately.

[Problems of the prior art]
Since both of the above prior art 1 and prior art 2 are provided with a combustion zone in the upper part of the high frequency heating furnace in order to incinerate combustible waste using a canister, the high frequency heating furnace is enlarged, In addition, equipment for blowing air into the canister from above, that is, an air supply nozzle and various equipment for air supply control are necessary. This is an inevitable problem as long as the canister is used as an incinerator. is there. Moreover, the problem that a large amount of unburned carbon remains in the incineration ash is due to the fact that the bottom of the canister is in an oxygen deficient state, so that it is inevitable as long as combustible waste is incinerated using the canister.
JP 7-260119 A Japanese Patent Laid-Open No. 11-271495

When combustible waste is separated and incinerated, if sufficient combustion is performed by supplying sufficient oxygen with a natural air flow so that unburned carbon components do not remain, the above-mentioned problems of the prior art are solved. .
The object of the present invention is to incinerate combustible waste in a high-frequency heating furnace, sufficiently supply oxygen by a natural air flow to completely burn the combustible waste, and heat and melt the incombustible waste together with the incineration ash. It is to be able to easily and easily melt the radioactive waste.

The present invention relates to a radioactive waste processing apparatus in which combustible waste is incinerated by high-frequency heating using a conductive incinerator, and the incinerated ash and incombustible waste are melted by high-frequency heating using a ceramic canister. Based on the following, it is based on the following (a) to (c).
(B) The incinerator is a combination of an ash tray and an incinerator that can be separated from each other,
(B) There is a grate below the incinerator, and an air passage is formed between the incinerator and the ash tray below the grate,
(C) In the state where the incinerator is mounted in a high-frequency heating furnace, the upper space in the incineration cylinder is a combustion zone, and the space above the incineration cylinder is a combustion zone.

[Action]
A conductive incinerator is attached to a high-frequency heating furnace to incinerate combustible waste, and a canister is attached to the high-frequency heating furnace to melt incombustible waste. The incineration process and the melting process are alternately performed at predetermined time intervals (for example, every day).

  The incinerator cylinder and ash tray of the incinerator are heated at high frequency, and the combustible waste is incinerated. At this time, since there is an air hole in the lower part of the sleeve of the high-frequency heating furnace, outside air flows into the lower part of the sleeve from this air hole, passes through the annular gap between the lower end of the incineration cylinder and the ash tray, and the upper and lower sides of the ash tray and the incineration cylinder It flows into the gap in the direction, and passes through the grate from the lower side to the upper side, rises in the incinerator, and rises in the upper space of the sleeve. This air flow is an updraft that is naturally generated by the air heated in the incinerator. And as mentioned above, air is supplied from the lower side to the combustible waste on the grate, and further supplied in the upper space in the incinerator. When the combustion gas rises from the incineration cylinder to the upper space in the sleeve of the high-frequency heating furnace, the air rising between the sleeve and the incinerator is supplied. And the incinerated ash of combustible waste falls and is collected in the ash tray, but this incinerated ash is supplied with oxygen by the air flow while it is dropped on the ash tray, and even after falling into the ash tray Since oxygen flows into the ash tray, oxygen is supplied. In this way, from when it burns on the grate to when it becomes incinerated ash and is collected in the ash tray, sufficient oxygen is supplied and completely burned, so the incinerated ash in the ash tray is unburned. No carbon remains.

When the incineration operation is completed, the pedestal is lowered, the incinerator is taken out of the high-frequency heating furnace, and conveyed to the vicinity of a predetermined ash collection device by a conveyor. The incinerator cylinder main body and the ash tray are separated by the ash collector outside the furnace, and the incineration ash, ash tray, and incinerator in the ash tray are sucked and cleaned by the ash collector's suction device. Is transferred to the input container (flammable container), and then reassembled for repeated use.
The charging container containing the incinerated ash in the ash tray is charged together with non-combustible waste into a canister mounted in a high-frequency heating furnace and is heated at high frequency. Since the canister is inserted with non-combustible waste such as conductive metal, it does not need to be conductive and generate heat.

As described above, air flows from the lower side to the upper side of the grate provided at the lower part of the incinerator, and further flows upward. And sufficient oxygen is supplied. Therefore, these spaces become active combustion zones. Therefore, by using the incinerator according to the present invention, combustible waste can be completely burned in a high-frequency heating furnace that does not have a special combustion zone.
In addition, since the incinerator is a separable combination of the ash tray and the incineration cylinder at the bottom of the incinerator, it is easy to take out the incinerated ash collected at the bottom of the incinerator (inside the ash tray). Incineration of combustible waste can be performed by repeatedly using the vessel.

Embodiment
When the incineration work of combustible waste is completed, the incinerator is taken out from the heating furnace, and the incineration ash is collected and used again. In this case, the incinerator must be cleaned. This is because if the incineration ash adheres, it will scatter and contaminate the inside of the cell. And this cleaning work is done remotely in the cell using a suction cleaning device, so if the internal structure is complicated, the suction port will not reach every corner, and therefore the incinerator will be pushed to every corner. It will not be possible to clean cleanly.
From the above, if the incinerator is a split type having a lower part with a grate and a simple cylindrical upper part, it is easier and easier to clean the lower part with the grate.

Incidentally, in the case where the incineration cylinder is of an integrated type and has a structure with a grate attached to the lower end thereof, it is difficult to sufficiently clean the corners of the incineration cylinder by remote control, so that the split type is desirable.
In addition, when the incineration cylinder is divided, the separation and connection (assembly) is performed by a manipulator (remotely operated robot arm) in the cell, so that the divided structure can be easily separated and easily assembled. Desirably, the incineration cylinder is divided into a lower part and an upper part, and these parts are fitted to each other so that the upper part and the lower part can be easily separated and joined, and the joining state can be stabilized. .

Further, the inner diameter of the ash tray is made larger than the outer diameter of the lower end of the incineration cylinder, a support leg is provided at the lower end of the incineration cylinder, the height of the support leg is substantially equal to the height of the ash tray, and the incineration cylinder is mounted on the support leg. An air inflow path to a space below the grate is configured by supporting the ash tray via the bottom of the ash tray.
The height of the support legs need not be equal to the height of the ash tray, but in order for the incinerator to fit in the induction furnace, it should be as low as possible and the combustion ash falling from the grate in the combustion cylinder. It is preferable that the support legs are not higher than the ash tray in order to prevent the ash from being scattered outside the ash tray. On the other hand, even if the height of the support leg is about 10 to 20 mm lower than the height of the ash tray, there is no particular disadvantage in constructing the air inflow path, but the ash capacity of the ash tray is reduced accordingly.
From the above, it is preferable that the height of the support leg is substantially equal to the height of the ash tray.

  It is also possible to fit the ash tray and the incineration cylinder, provide an air hole in the upper portion of the side wall of the ash tray, and allow air to flow into the ash tray from the air hole. In this case, incineration ash spills out from the air holes, so the side walls need to be raised so that the required capacity of the ash tray is secured, and there are no support legs for the incineration cylinder, The lower end is fitted to the upper end of the ash tray. This structure has the merit that it is not necessary to provide support legs at the lower end of the incineration cylinder, but the side wall of the ash tray is raised and an air hole is provided in the upper part, so the structure of the ash tray is complicated. There is a demerit that In this case, it is inevitable that the capacity of the ash tray is reduced.

Next, an embodiment will be described with reference to FIGS. 1, 2, and 3.
The incinerator 10 of this embodiment has a height of 400 mm and an incineration cylinder having an inner diameter of 250 mm. The incineration capacity of the incinerator depends on the material of the waste. For example, in the case of normal waste such as gloves, waste and wood, about 7 kg per hour, resin such as ion exchange resin. In the case of a product, it is about 10 kg per hour. The incinerator may be made of stainless steel, but may be a metal such as a highly corrosion resistant metal or iron. However, the metal must be able to withstand a combustion temperature of about 900 ° C. and be conductive, and is preferably a metal that is relatively inexpensive and has high corrosion resistance.

The lower part of the incinerator 10 is an ash tray 11 having an inner diameter of about 340 mm and a height of about 120 mm. The incineration cylinder 12 is further divided into an incineration cylinder upper part 12a and an incineration cylinder lower part 12b, and a metal knitted grate 13 is detachably provided at the lower end of the incineration cylinder lower part 12b. Note that the grate 13 is assumed to be worn out and is replaced with a new one when worn out.
The upper portion 12a of the incineration cylinder is a cylindrical body, has a conical flange 12f that opens upward, and has a tapered outer surface at the lower end that is a tapered surface 12t. The conical flange 12f at the upper end is for facilitating the introduction of waste into the incineration cylinder 12, and the lower end is the tapered surface 12t to facilitate fitting into the incineration cylinder lower part 12b. Because.

The incineration cylinder lower part 12b has a two-stage structure having an upper part with an inner diameter of about 260 mm and a lower part with an outer diameter of about 260 mm, and a support part for the grate 13 is provided at the lower part.
There are four support legs 14 at the lower part 12b of the incineration cylinder. And the height of this support leg 14 is equal to the height of about 120 mm of the ash tray 11. The plate thickness of the ash tray 11 and the incineration cylinder 12 is about 10 mm.
When the inner diameter of the ash tray 11 is about 80 mm larger than the outer diameter of the lower end of the incineration cylinder, and the incineration cylinder 12 is combined with the ash tray 11, an annular gap having a width of about 40 mm is formed therebetween.

In addition, there is a conical flange 12g that opens outward at the upper end of the incineration cylinder lower part 12b. With the conical flange 12g, the incineration cylinder upper part 12a can be more easily fitted. Moreover, since the taper surface 12t exists in the outer periphery of the lower end of the incineration cylinder upper part 12a, the fitting to the incineration cylinder lower part 12b is comparatively easy.
And from the viewpoint of the cleaning work in the cell by the suction cleaning device, it is desirable that the structure of each divided part is simple. Therefore, from the above, the conical flange 12g is not necessarily required. .

  The incinerator 10 as described above is mounted on the pedestal 3 and pushed up into the sleeve 2 so as to be mounted on the high-frequency heating furnace 1 and combustible waste is put into it for incineration. Since the entire vessel is heated to a high temperature (about 900 ° C.), an ascending airflow is generated inside and outside thereof, thereby causing the outside air to flow along the illustrated arrow. A large amount of oxygen is supplied into the incinerated ash in the ash tray 11, the combustible material on the grate 13, the upper space in the incineration cylinder, and the upper space in the combustion cylinder by the air flow A.

  When the combustible waste incineration operation is completed, the pedestal 3 is lowered, the incinerator 10 on the pedestal is transferred to the conveyor, and is conveyed to the vicinity of the incineration ash collection device by the conveyor. The incineration cylinder upper part 12 a and the incineration cylinder lower part 12 b are sequentially separated in the vicinity of the incineration ash collection device, and the incineration cylinder 12 is separated from the ash tray 11. The incineration ash T accumulated in the ash tray 11 is collected by the suction cleaning machine of the incineration ash collection device and transferred to the charging container, and the ash tray 11, the incineration cylinder upper part 12a, and the incineration cylinder lower part 12b are cleaned by the suction cleaning machine. Is done. Incinerated ash collected by this cleaning is also transferred to the charging container. The incinerator 10 that has been cleaned is reassembled and prepared for reuse.

A ceramic canister is attached to the high-frequency heating furnace 1, and an input container containing incinerated ash is introduced into the canister together with incombustible waste, and these are heated and melted.
When the heating and melting operation is completed and the canister is removed from the high-frequency heating furnace, one work cycle of incineration and heating and melting ends. Then, when the next work cycle starts, the incinerator that has been waiting is attached to the high-frequency heating furnace again.
As described above, the incineration of the combustible waste and the melting treatment of the incombustible waste are repeatedly performed in the same high-frequency heating furnace while repeatedly using the incinerator.

The side view of the incinerator of the embodiment Is a cross-sectional view of the incinerator installed in a high-frequency furnace Figure 2 is a cross-sectional view of prior art 2

Explanation of symbols

1: High-frequency heating furnace 2: Sleeve 3: Pedestal 10: Incinerator 11: Ash tray 12: Incineration cylinder 12a: Incineration cylinder upper part 12b: Incineration cylinder lower part 13: Grate 14: Support legs
T: Incineration ash

Claims (6)

Radioactively incinerate flammable waste by high-frequency heating using a conductive incinerator, and heat and melt the resulting incinerated ash together with non-combustible waste using a ceramic canister instead of the above incinerator In waste treatment equipment,
The incinerator is placed on the ash tray so that the incinerator can be separated from each other, and there is a grate below the incinerator, and between the incinerator and the side wall of the ash tray below the grate . Thus the air passage in a gap provided between is constituted,
A radioactive waste characterized in that the upper space in the incineration cylinder is a combustion zone and the space above the incineration cylinder is a combustion zone in a state where the incinerator is mounted in a high-frequency heating furnace. Processing equipment.   2. The radioactive waste treatment apparatus according to claim 1, wherein the incineration cylinder is a split type divided into a lower part and an upper part provided with a grate. The incineration cylinder and the ash tray are cylindrical, the inner diameter of the ash tray is larger than the outer diameter of the lower end of the incineration cylinder, the lower end of the incineration cylinder has a support leg, and the height of the support leg is the height of the ash tray. The incineration cylinder is almost equal to the height and is supported on the bottom surface of the ash tray via the support legs, and the air inflow path to the space below the grate between the lower end of the incineration cylinder and the upper end of the ash tray 3. A radioactive waste disposal apparatus according to claim 1 or claim 2.   A conductive incinerator for incineration of flammable waste by high frequency heating,
  An incineration cylinder having a flow path penetrating inside and outside at the bottom;
  A grate provided in the interior above the flow path of the incinerator,
  Mounted with the incinerator, and having an ash tray with a side wall,
  An incinerator characterized in that a gap is provided between the outer surface of the lower end of the incineration cylinder and the inner surface of the side wall of the ash tray. The incinerator according to claim 4, wherein the incinerator is a split type divided into a lower part and an upper part provided with a grate. The incineration cylinder and the ash tray are cylindrical, the inner diameter of the ash tray is larger than the outer diameter of the lower end of the incineration cylinder, the support leg is at the lower end of the incineration cylinder, and the height of the support leg is the height of the ash tray. The incineration cylinder is supported on the bottom surface of the ash tray via the support legs, and an air inflow path to a space below the grate is provided between the lower end of the incineration cylinder and the upper end of the ash tray. An incinerator according to claim 3 or claim 4.

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