JP2000018831A - Thermal decomposer and thermal decomposition method for used ion exchange resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the reduction of volume by thermal decomposition of a waste ion exchange resin, without needing hands for treatment of substance to be treated adhering to the inner face of a rotating cylinder. SOLUTION: Adhesion preventive mechanisms consisting of one sheet or plural sheets of flat plates 21 which are inserted in the axial direction of a rotating cylinder so that the end face of its one end may contact with the inner face of the rotating cylinder 1 and rotates relatively to the rotation of the rotating cylinder 1 are arranged at the section on the upstream side in the shifting direction of the ion exchange resin within the rotating cylinder 1 constituting a thermal decomposer for used ion exchange resin. Adhesion preventive mechanisms consisting of one piece or plural pieces of hexagonal or octagonal bars which are arranged in axial direction in contact with the inside periphery of the rotating cylinder 1 and are supported so that they can rotate freely around the bars themselves are provided downstream of it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyrolysis apparatus and a pyrolysis method for a spent ion exchange resin, particularly a spent ion exchange resin generated from a facility for handling radioactive materials such as a nuclear power plant. The present invention relates to an apparatus and a method for continuously pyrolyzing a used ion exchange resin using an externally heated rotary kiln.

[0002]

2. Description of the Related Art In radioactive substance handling facilities such as nuclear power plants, a large amount of ion exchange resin is used to purify water. Since the exchange capacity of the ion exchange resin is limited, the ion exchange resin used for a certain period
It becomes a waste ion exchange resin that can no longer be used, but since this waste ion exchange resin contains radioactive substances,
It is extremely difficult to reproduce and reuse this. For this reason, various methods for treating and disposing of waste ion exchange resin have been studied so far.

[0003] The most common treatment method currently performed is to solidify with cement or asphalt and store and manage it in a predetermined facility. However, in the solidification of cement, the volume of the solidified body increases several times with respect to the volume of the original waste resin. Asphalt solidification similarly increases the volume and becomes flammable, so it is necessary to consider the management method.
In the near future, it may become increasingly difficult to secure a storage place for radioactive waste, and a new treatment method that enables volume reduction and stabilization of waste ion exchange resin is required.

Heretofore, an acid decomposition method and an incineration method have been proposed as treatment methods for reducing and stabilizing the volume of a waste ion exchange resin. The acid decomposition method is a method in which a resin is dissolved and oxidized using concentrated sulfuric acid and nitric acid or hydrogen peroxide at a temperature of 200 to 350 ° C. The details thereof are described in, for example, JP-A-53-885.
No. 00 publication. The acid decomposition method is said to require a smaller apparatus than the incineration method. However, since concentrated sulfuric acid and the like are handled, there are many restrictions on the material side, and a large amount of waste acid is generated.

On the other hand, in the incineration method, waste ion exchange resin is incinerated, and incinerated ash containing radioactive substances is solidified by a solidifying agent and stored. Although incineration seems easy at first glance,
The waste ion exchange resin is styrene-based polymer particles or powder containing about 50% of water, and it is quite difficult to stably incinerate it. Fluidized beds are suitable for the incineration of such flame-retardant materials.
No. 2400 discloses a method for treating waste ion exchange resin using a fluidized bed incinerator.

However, fluidized bed incineration generates a large amount of combustion exhaust gas containing radioactive materials, and thus has a problem that the load on the exhaust gas filter is large and a large amount of secondary radioactive waste is generated by desulfurization and denitration of the exhaust gas. Yes, not yet in practical use.

As described above, both the acid decomposition method and the incineration method have unsolved problems. Therefore, a thermal decomposition method is being studied as an alternative method. The pyrolysis method is a method of pyrolyzing a waste ion exchange resin in a reducing atmosphere to form a pyrolysis residue mainly composed of carbon. The pyrolysis residue contains a radioactive substance, which is solidified with a solidifying agent and stored. The pyrolysis residue is reduced in volume to about 1/4 to 1/10 the volume of the original waste ion exchange resin, and 80 to 90% by weight of carbon is chemically very stable. Further, since the pyrolysis residue can be burned much more easily than waste ion exchange resin, incineration can be performed even in a combustion furnace other than a fluidized bed.

Japanese Patent Application Laid-Open No. 58-19600 discloses a processing method characterized in that waste ion exchange resin is liquefied by thermal decomposition, and the liquefied material is burned to be gasified. No. 155399 discloses a method in which a waste ion exchange resin is thermally decomposed in a furnace having a dispersing medium filling section therein, and then the pyrolysis residue is recovered from the filling section and incinerated. JP-A-59-1073
No. 00 discloses a method of thermally decomposing a waste ion exchange resin in two stages by changing the thermal decomposition temperature. JP-A-60-
No. 41000 describes a method in which a waste ion exchange resin is heated by infrared rays or a laser beam, carbonized, and then incinerated. Japanese Patent Application Laid-Open No. 60-162999 discloses a pyrolysis method characterized by performing pyrolysis at a temperature of 350 to 420 ° C. in an inert gas atmosphere.
JP-A-235100 discloses a pyrolysis method characterized in that the molar ratio of sulfur, nitrogen and hydrogen atoms in the residue to carbon atoms is in a specific range. JP 6
Japanese Patent Application Laid-Open No. 1-205899 discloses a processing method characterized in that after pyrolysis is performed at a specific temperature, a pyrolysis residue is solidified with a solidifying agent to which a surfactant is added. Japanese Patent Application Laid-Open No. 62-19798 describes a treatment method in which waste ion exchange resin is thermally decomposed and the residue is pelletized by hot pressing. JP-A-62-29
No. 7796, Japanese Patent Application Laid-Open No. 62-297797,
The present invention relates to a processing method and a processing apparatus characterized in that a waste ion exchange resin is thermally decomposed at a specific range of temperature and residence time, and then the residue is incinerated.
Japanese Patent Publication No. 98 relates to a processing method characterized in that pyrolysis tar is re-decomposed in a reducing atmosphere and then incinerated. JP-A-4-59600 describes a method in which the waste ion exchange resin is thermally decomposed in two stages by changing the thermal decomposition temperature, and then the residue is molded by hot pressing. JP-A-5-88440 discloses that after adding carbon to dried waste ion-exchange resin and thermally decomposing it by applying electric current,
A treatment method for incineration of residue and carbon is disclosed.

In the above invention, various types of pyrolysis devices have been proposed. JP-A-58-19600 proposes a continuous packed-bed reactor. JP-A-58-1
No. 55399 assumes a vertical incinerator having a dispersing medium filling section, and JP-A-59-107300 and JP-A-60-162999 state that a batch reactor is used. Japanese Patent Application Laid-Open No. 60-235100 states that a batch type reactor is desirable from the viewpoint of controlling the thermal decomposition, while it is possible to use a continuous apparatus such as a fluidized bed, a rotary kiln and a multistage furnace. JP-A-61-205899 and JP-A-62-19798 make it possible to use either a continuous rotary kiln or a batch reactor. JP-A-62-297796, 297797, 2
No. 97798 discloses a screw kiln as an example. JP-A-4-59600 proposes a batch-type reactor, and JP-A-5-88440 proposes a vertical flow reactor having electrodes for electric heating.

[0010]

As described above, many studies have been made on the thermal decomposition of waste ion exchange resin, and various methods have been proposed. Nevertheless, there has been no practical application of an apparatus for treating a radioactive waste ion exchange resin by a thermal decomposition method. There are several reasons for this, but the biggest reason is that it is difficult to handle the resin and the residue when implementing the apparatus.

The waste ion exchange resin is particles of 500 μm or more or fine powder of 400 mesh or more. The pyrolysis residue is also a granular or differential powder. Generally, handling of powder and granules has many difficulties as compared with handling of gas and liquid. Gases and liquids flow in pipes generally along a pressure gradient, whereas powders do not flow simply by applying pressure due to the large frictional force between particles and between particles and the pipe wall. Or a special conveyor such as a belt conveyor or a screw conveyor is required. In addition, in the granular material,
Troubles often occur such as clogging at narrow portions such as storage tank entrances or bent portions of pipes, or dead volume due to adhesion to wall surfaces.

Normally, such troubles are dealt with manually, but when dealing with radioactive waste, it is necessary to avoid handling them manually as much as possible. For this reason, in the design of the treatment process of the waste ion exchange resin, a structure that is more maintenance-free than in the case of the ordinary powder process is required.

In many cases, the waste ion exchange resin is stored in the form of a slurry in a state of solid-liquid separation. The ion-exchange resin in such a state has a very strong adhesive force between particles, and has a property of easily adhering to the inner wall of a container or a pipe. The inventors of the present invention performed thermal decomposition tests many times using several types of ion exchange resins, and all of the ion exchange resins showed strong adhesion between particles and to containers and pipes. It is not uncommon for a water-containing ion exchange resin to have a repose angle of 90 degrees. In particular, in the case of a powdery ion-exchange resin, the properties in a water-containing state only by draining are very similar to clay, and are very difficult to handle.

On the other hand, the properties of the thermal decomposition residue are completely different from those of the waste ion exchange resin, and the same thermal decomposition residue is considerably different in the thermal decomposition residue of the cation exchange resin and the thermal decomposition residue of the anion exchange resin. different. Although the thermal decomposition residue of the cation exchange resin is reduced in volume, it generally retains the shape of the original particles, and does not have strong adhesion between the particles and to containers and pipes. On the other hand, the thermal decomposition residue of the anion exchange resin significantly decreases in density and becomes a porous powder. Adhesion between particles is relatively strong and may form pumice-like lumps. In addition, it easily adheres to the wall surface of the device and does not easily peel off. The residue may further adhere to the adhered residue, and the wall surface may be coated with the residue.

Nevertheless, a wide variety of devices have been developed for storing and transferring powders. Even if the powder has the above-mentioned properties, proper devices can be selected for storing and transferring without trouble. It is possible. The problem is in the interior of the pyrolysis apparatus, where the properties of the granular material change significantly with the progress of the pyrolysis. In the case of a batch type apparatus, the properties of the granular material to be handled change with time, and in the case of the continuous type, the properties of the granular material to be handled vary depending on the parts of the apparatus.

For example, Japanese Patent Laying-Open No. 54-7971 discloses an apparatus in which a substance attached to the inner peripheral surface of a rotary kiln is scraped off by a basket-like body arranged inside the kiln.
Japanese Patent Application Laid-Open No. 9-279161 discloses an apparatus in which a deposit on an inner peripheral surface of a rotary kiln is scraped off by rotating a paddle or a screw blade disposed inside the kiln. However, none of these devices take into account that the properties of the powder fluid to be processed change with the progress of thermal decomposition, and the same configuration from the upstream end to the downstream end of the kiln applies , The adherence of the processing object to the scraping device is unavoidable, and human labor is required to remove it.

The thermal decomposition apparatus proposed so far does not take this problem into account, so that it becomes difficult to handle the powder or granular material in actual equipment.

An object of the present invention is to reduce the volume of waste ion-exchange resin by thermal decomposition without requiring any manpower to treat the object adhered to the inner surface of the rotating cylinder.

[0019]

Means for Solving the Problems The inventors of the present invention conducted many experiments on the thermal decomposition of waste ion exchange resin, and found that the structure of a thermal decomposition apparatus capable of continuously and stably pyrolyzing waste ion exchange resin was developed. I came up with the idea.

The pyrolysis apparatus according to the present invention is a continuous operation pyrolysis apparatus for pyrolyzing a used ion exchange resin in a reducing atmosphere to reduce the volume thereof. A rotary cylinder for heating while moving to a rotating cylinder, and a plurality of types of adhesion preventing mechanisms arranged in the rotary cylinder, and an externally heated rotary kiln comprising: It is a pyrolysis device. In other words, by using an anti-adhesion mechanism suitable for each of the properties of the granular material that greatly changes due to thermal decomposition, it has become possible to continuously and stably thermally decompose the waste ion exchange resin. .

Specifically, the plurality of types of adhesion preventing mechanisms are sequentially arranged in the axial direction of the rotating cylinder. For example,
The anti-adhesion mechanism disposed on the upstream side in the axial direction of the rotary cylinder has a configuration in which a position facing the inner peripheral surface of the rotary cylinder does not change. The position facing the inner peripheral surface of the cylinder is configured to change with the rotation of the rotary cylinder.

As the adhesion preventing mechanism, one or more sheets, which are inserted in the axial direction of the rotating cylinder such that one end face thereof is in contact with the inner surface of the rotating cylinder and rotate relatively in reverse to the rotation of the rotating cylinder, are provided. In the form of a plurality of flat plates or a helical shape that rotates relatively opposite to the rotation of the rotating cylinder, inserted along the axial direction of the rotating cylinder so that one end surface is in contact with the inner surface of the rotating cylinder, One or more hexagonal or octagonal rolls, one or more hexagonal or octagonal, which are arranged along the axial direction in contact with the inner peripheral surface of the rotating cylinder and are rotatable around the axis of the rod itself There is a rod, a single or plural chains or a bead-shaped connecting body that is sagged in contact with the inner peripheral surface of the rotating cylinder and stretched along the axial direction of the rotating cylinder. .

These anti-adhesion mechanisms may be combined in accordance with the nature of the waste ion exchange resin which changes depending on the position in the rotating cylinder. For example, relative to the rotation of the rotating cylinder, the one end face is inserted along the axial direction of the rotating cylinder such that one end surface is in contact with the inner surface of the rotating cylinder in an upstream portion of the ion-exchange resin moving direction in the rotating cylinder. The anti-adhesion mechanism, which is one or more flat plates that rotate in the reverse direction, or the rotation of the rotating cylinder, which is inserted along the axial direction of the rotating cylinder such that one end surface is in contact with the inner surface of the rotating cylinder, The anti-adhesion mechanism, which is a spirally wound plate that rotates in the opposite direction, is disposed.On the downstream side, the anti-adhesion mechanism is disposed along the axial direction in contact with the inner peripheral surface of the rotating cylinder. One or more hexagonal or octagonal sticks, which are supported so that they can rotate freely around the axis, and an anti-adhesion mechanism, or slack so as to be in contact with the inner peripheral surface of the rotating cylinder, along the axial direction of the rotating cylinder. One or more chains Or arranging the adhesion preventing mechanism is a beaded coupling body.

The used ion exchange resin is thermally decomposed in a reducing atmosphere to reduce the volume by using the apparatus having the above-described structure. Specifically, in a continuous operation pyrolysis method in which the used ion-exchange resin is axially moved in a rotating cylinder in a reducing atmosphere while being continuously heated and pyrolyzed to reduce the volume, an upstream side of the rotating cylinder is provided. The ion exchange resin is scraped from the inner peripheral surface of the rotating cylinder by an adhesion preventing mechanism that does not change its own contact position with the inner peripheral surface of the rotating cylinder, and is located on the downstream side of the rotating cylinder. The ion exchange resin is scraped off from the inner peripheral surface of the rotating cylinder by an adhesion preventing mechanism whose contact position with the inner peripheral surface of the rotating cylinder changes as needed.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to an embodiment of the present invention will be described below with reference to the drawings. The thermal decomposition apparatus according to the embodiment of the present invention is an external heat type rotary kiln as shown in FIGS. The rotary kiln includes a rotating cylinder 1 as a reaction part for heating and thermally decomposing the waste ion exchange resin while moving the waste ion exchange resin in the axial direction, a gantry 3 supporting the rotating cylinder, a motor 5 for rotating the rotating cylinder, and a shaft of the rotating cylinder 1. Parts 7, 9 which are connected to the upper and lower ends in the direction so as to be relatively rotatable, a powder supply hopper and a feeder which are connected to the fixed part 7 and supply waste ion exchange resin to the rotary cylinder 1 via the fixed part 7. 11, a residue receiver 13 provided in the fixed part 9, a pyrolysis gas outlet 15, and a heating source 17 arranged on the outer periphery of the rotary cylinder 1. The adhesion preventing mechanism provided inside the rotary cylinder 1 will be described later. Use of an electric heater, steam, combustion gas, or the like as a heating source does not affect the manifestation of the effects of the present invention, but an electric heater is most preferable in terms of simplicity of operation. The control device for controlling the device is not shown.

The rotary kiln is installed so that the axis of the rotary cylinder 1 is inclined from the horizontal so that the downstream side becomes lower, and the powder supplied into the rotary cylinder 1 by the feeder 11 gradually rotates by the rotation of the rotary cylinder 1 and the action of gravity. It moves downstream, and finally falls from the end of the rotating cylinder 1 and is collected in the receiver 13. Generally, in an actual apparatus, the inclination angle of the axis of the rotating cylinder 1 is in the range of 0.5 degrees to 2 degrees.

However, in the thermal decomposition of the waste ion exchange resin, as described above, stable movement of the granular material cannot be realized merely by the action of the rotation of the cylinder and the action of gravity. For this reason, it is necessary to use an optimal anti-adhesion mechanism for each of the properties of the granular material which greatly changes due to thermal decomposition.

The water-containing waste ion exchange resin upstream of the rotary cylinder 1 is relatively heavy and adheres to the inner peripheral surface, but has a relatively small adhesive force to the adhesion preventing mechanism itself. On the other hand, waste ion exchange resin that has undergone thermal decomposition has a significantly reduced density and lighter weight, but is more likely to adhere to the adhesion prevention mechanism itself,
If the substance is attached as it is, it tends to solidify with the substance attached.

The waste ion exchange resin in a hydrated state, that is,
For transporting the waste ion exchange resin to the upstream portion of the rotating cylinder 1,
As shown in FIG. 1, one or a plurality of ones, which are inserted in the axial direction of the rotating cylinder such that one end surface is in contact with the inner surface of the rotating cylinder, rotate relatively counter to the rotation of the rotating cylinder. An adhesion prevention mechanism composed of a flat plate is effective. The flat plate 21 extends in the axial direction with its end face in contact with the inner wall of the rotating cylinder, and maintains a cage-like structure by a support column 23 that supports the flat plate 21. The upstream side is connected to the fixed part 7, and the flat plate 21 is stationary. Therefore, when viewed from the rotating cylinder 1, the flat plate 21 relatively rotates in the reverse direction, and functions to scrape off the waste ion exchange resin attached to the inner wall of the rotating cylinder 1.

Although six flat plates are drawn in the AA cross section in FIG. 1, one or two flat plates are effective when stationary. Further, the flat plate may be rotated in the opposite direction to the cylinder, and in that case, it is more effective to have 4 to 6 flat plates.

Further, as shown in FIG. 2, the one end face is inserted along the axial direction of the rotary cylinder 1 so as to be in contact with the inner surface of the rotary cylinder 1, and rotates relatively in reverse to the rotation of the rotary cylinder 1. The anti-adhesion mechanism constituted by the spirally wound plate 25 is also effective for transporting the water-containing waste ion exchange resin. The spirally wound plate 25 extends in the axial direction with its end face in contact with the inner wall of the rotary cylinder 1, and is supported by a support column 27. The upstream side is connected to the fixed part 7, and the plate 25 is stationary. Therefore, when viewed from the rotary cylinder 1, the plate 25 relatively rotates reversely, and functions to scrape the waste ion exchange resin adhered to the inner wall of the rotary cylinder 1. In addition, the plate 25 has a function of transporting the resin downstream along the spiral, and has an effect of preventing the resin from staying upstream.

In FIG. 2, the column 27 is fixed, but if a mechanism for rotating the plate 25 is provided and the relative speed of the plate 25 to the rotating cylinder 1 is changed, the resin conveying speed can be freely adjusted. be able to. That is, the transport speed on the downstream side and the transport speed on the upstream side can be set to different values.

On the other hand, the pyrolysis residue, that is, the rotating cylinder 1
In order to prevent the adhesion of the waste ion-exchange resin on the downstream side of the rod, as shown in FIG. 3, the rod can be freely rotated around the axis of the rod itself, which comes into contact with the inner peripheral surface of the rotary cylinder 1 and is inserted along the axial direction. An adhesion preventing mechanism composed of one or a plurality of hexagonal or octagonal rods 29 is effective. The rod 29 is connected to the fixing portion 9 by a chain so as not to slip down. At this time stick 2
360 so that 9 can rotate freely about the axis of the rod itself.
It is indispensable to provide a joint which rotates at an angle in order to obtain an adhesion preventing effect. When the rod 29 rotates with the rotation of the rotary cylinder 1, and different surfaces of the rod 29 come into contact with the inner surface of the rotary cylinder 1, the pyrolysis residue that has once adhered to the rod 29 is peeled off and the rod 29 itself is removed. Adhesion of residues can be prevented.

As shown in FIG. 4, the inner wall of the rotary cylinder 1 is bent along the axial direction of the rotary cylinder 1 and in contact with the inner peripheral surface of the rotary cylinder 1 so that the inner wall of the rotary cylinder 1 can be scraped off. An anti-adhesion mechanism composed of one or more chains 31 or beads in a stretched configuration is also effective for transporting the pyrolysis residue. The chain 31 extends diagonally from the upstream side to the downstream side of the rotary cylinder 1, but must have sufficient slack so as to contact the inner wall of the rotary cylinder 1. Depending on the nature of the pyrolysis residue, the chain 31 may not have the necessary weight to scrape the inner wall of the rotating cylinder 1. In this case, it is preferable to use an iron ball or a short prism connected in a rosary instead of a chain.

In the apparatus according to the present invention, the anti-adhesion mechanism shown in FIG. 1 or FIG.
The anti-adhesion mechanism shown in the figure below is provided on the downstream side, and by using the anti-adhesion mechanism suitable for each of the properties of the granular material that greatly changes by thermal decomposition, the waste ion exchange resin can be continuously and stably This is a pyrolysis device that can perform pyrolysis. As an example, FIG. 5 shows a pyrolysis apparatus according to the present invention in which the anti-adhesion mechanism shown in FIG. 1 is provided on the upstream side and the anti-adhesion mechanism shown in FIG. 3 is provided on the downstream side.

In the apparatus of the present invention, the upstream side mainly indicates a portion where drying and dehydration of the hydrated ion exchange resin are performed, and the downstream side mainly indicates a portion where thermal decomposition of the ion exchange resin proceeds. Which part of the thermal decomposition apparatus corresponds to the upstream side can be estimated from the amount of heat required for drying and dehydrating the hydrated ion exchange resin, the heat transfer coefficient in the rotating cylinder, and the surface area per unit length of the inner wall.

The use of the pyrolysis apparatus of the present invention makes it possible to continuously pyrolyze radioactive waste ion-exchange resins and to stably obtain pyrolysis residues. FIG. 6 shows an example of a flow chart of a radioactive waste ion exchange resin pyrolysis process using the pyrolysis apparatus of the present invention. The waste ion exchange resin is transferred from the storage container to the receiving hopper 51, and then sent to the dehydrator 53. After being dewatered to a draining state by the dehydrator 53, it is transferred to the feed hopper 57 by the conveyor 55. The waste ion exchange resin stored in the feed hopper 57 is quantitatively sent to the rotary kiln 61 by the feeder 59.
The rotary kiln 61 is a pyrolysis device of the present invention,
Here, the waste ion exchange resin is thermally decomposed in a reducing atmosphere, and is converted into a pyrolysis residue and a pyrolysis gas. The pyrolysis residue is once received by the residue hopper 63, cooled, and then sent to a solidification process.
The pyrolysis gas containing tar is guided to the afterburner 65 and is completely burned. The combustion exhaust gas is removed by a filter 67 to remove fly ash containing a radioactive substance, then sucked by an exhaust blower 69, further purified by a desulfurization and denitration device 71, and discharged to the outside of the system. In the pyrolysis treatment, most of the ash in the waste ion exchange resin is retained in the residue, so that the load on the filter 67 is very light.

Hereinafter, the effects of the present invention will be clarified using examples.

The experiments of the following Examples and Comparative Examples were performed using a bench-scale rotary kiln test apparatus. This test apparatus is an external heater with an electric heater, and has a rotating cylinder with an inner diameter of 150 mm and a length of 2000 mm. The thermal decomposition temperature is 500 ° C. Since the pyrolysis gas is sucked by the exhaust pump, the inside of the kiln is 50 m above the atmospheric pressure with a water column.
m is maintained at a negative pressure of about m. Also, a fixed part on the downstream side,
The receiver and the pyrolysis gas outlet are kept at 200 ° C. to prevent condensation of tar and steam generated by the pyrolysis.

EXAMPLE Using a test apparatus provided with the anti-adhesion mechanism shown in FIG. 1 on the upstream side and the anti-adhesion mechanism shown in FIG. A pyrolysis test of a strongly basic ion exchange resin was performed.
However, the number of the flat plates 21 constituting the upstream-side adhesion prevention mechanism is one, which is fixed to the fixing portion 7. Further, the rod 29 on the downstream side is a hexagonal stainless steel rod having a length of 20 mm across flats. The water content of the resin is 60% by weight. Resin supply speed is 1kg
/ H, the angle of inclination of the rotating cylinder was 2 degrees, and the number of revolutions was 1 rpm.

A total of 5 kg of resin is supplied and 0.28 kg
Was recovered. The shape of the pyrolysis residue is several mm
It was a small piece of corner. On the upstream side, the ion exchange resin was smoothly conveyed, and no adhesion of the residue was observed on the downstream side.

COMPARATIVE EXAMPLE 1 The same ion exchange resin as in the example was subjected to a thermal decomposition test using a kiln in which the adhesion preventing mechanism shown in FIG. 1 was provided over the entire length of the rotating cylinder. However, the number of the flat plates 21 constituting the adhesion preventing mechanism is one. On the upstream side, the ion exchange resin was smoothly transported, but on the downstream side, the pyrolysis residue adhered to the flat plate 21 and grew, and a large lump was formed on one side of the flat plate 21.

COMPARATIVE EXAMPLE 2 The same ion exchange resin as in the example was subjected to a thermal decomposition test using a kiln provided with the adhesion preventing mechanism shown in FIG. 3 over the entire length of the rotary cylinder. The inserted rod 29 is a hexagonal stainless steel rod having a length of 20 mm across flats. The flow of the ion-exchange resin stayed on the upstream side, and a part of the flow returned. No residue was observed on the downstream side, and most of the residues were collected as small pieces of several mm square.

[0044]

As is clear from the examples, the use of the pyrolysis apparatus of the present invention makes it possible to continuously and stably pyrolyze the ion exchange resin. The thermal decomposition apparatus of the present invention has solved the problem of resin handling remaining in the thermal decomposition treatment of the radioactive waste ion exchange resin, and has enabled the practical use of the thermal decomposition treatment.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a mechanism effective for preventing adhesion of a hydrated ion exchange resin of the present invention.

FIG. 2 is a cross-sectional view showing another example of a mechanism effective for preventing adhesion of the hydrated ion exchange resin of the present invention.

FIG. 3 is a cross-sectional view illustrating an example of a mechanism effective for preventing adhesion of a pyrolysis residue according to the present invention.

FIG. 4 is a cross-sectional view showing another example of a mechanism effective for preventing adhesion of a pyrolysis residue according to the present invention.

FIG. 5 is a sectional view showing an embodiment of the thermal decomposition apparatus according to the present invention.

FIG. 6 is a flow chart of a waste ion exchange resin pyrolysis process using the pyrolysis apparatus of the present invention.

[Explanation of symbols]

 Reference Signs List 1 rotating cylinder 3 gantry 5 motor 7 fixing part 9 fixing part 11 feeder 13 receiver 15 pyrolysis gas outlet 17 heating source 21 flat plate 23 support 25 spirally wound plate 27 support 29 rod 31 chain 51 receiving hopper 53 dehydrator 55 conveyor 57 feed hopper 59 feeder 61 rotary kiln 63 residue hopper 65 afterburner 67 filter 69 exhaust blower 71 desulfurization and denitration equipment

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Katakura 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Engineering & Shipbuilding Co., Ltd. (72) Inventor Satoshi Nagahara 5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui Shipbuilding Co., Ltd. F term (reference) 4H012 HB03 HB04 HB09 4K061 AA08 BA07 DA03 DA05 EA03 EA06 FA01 GA09 HA07

Claims (10)

[Claims] 1. A continuous operation pyrolysis apparatus for thermally decomposing a used ion exchange resin in a reducing atmosphere to reduce its volume, wherein the ion exchange resin is heated while moving in the axial direction inside the resin. An apparatus for thermally decomposing a used ion exchange resin, which is an externally heated rotary kiln having a rotating cylinder and a plurality of types of adhesion preventing mechanisms disposed in the rotating cylinder. 2. The apparatus for thermally decomposing a used ion exchange resin according to claim 1, wherein a plurality of types of adhesion preventing mechanisms are arranged in order in the axial direction of said rotary cylinder. 3. The adhesion preventing mechanism disposed on the upstream side in the axial direction of the rotary cylinder has a configuration in which the position facing the inner peripheral surface of the rotary cylinder does not change, and the adhesion preventing mechanism disposed on the downstream side thereof. The apparatus according to claim 2, wherein the mechanism is configured such that a position facing the inner peripheral surface of the rotary cylinder changes with rotation of the rotary cylinder. 4. One of a plurality of types of anti-adhesion mechanisms in the rotating cylinder is adapted to rotate the rotating cylinder inserted along the axial direction of the rotating cylinder such that one end surface is in contact with the inner surface of the rotating cylinder. 2. The thermal decomposition apparatus for a used ion exchange resin according to claim 1, wherein the apparatus comprises one or a plurality of flat plates which rotate relatively in reverse. 5. One of a plurality of types of anti-adhesion mechanisms in the rotating cylinder, wherein one of the plurality of types of anti-adhesion mechanisms is provided along the axial direction of the rotating cylinder such that one end surface is in contact with the inner surface of the rotating cylinder. 2. The apparatus for pyrolyzing used ion exchange resin according to claim 1, wherein the apparatus is a spirally wound plate that rotates relatively in reverse. 6. One of a plurality of types of anti-adhesion mechanisms in the rotating cylinder is disposed along the axial direction in contact with the inner peripheral surface of the rotating cylinder, and is supported so as to be freely rotatable around the axis of the rod itself. The apparatus for pyrolyzing a used ion exchange resin according to claim 1, wherein the apparatus is one or a plurality of hexagonal or octagonal rods. 7. One or a plurality of ones of a plurality of types of adhesion preventing mechanisms in the rotating cylinder, which are slackened in contact with the inner peripheral surface of the rotating cylinder and stretched along the axial direction of the rotating cylinder. The apparatus for thermally decomposing a used ion exchange resin according to claim 1, wherein the apparatus is a chain or a bead-like connected body. 8. The anti-adhesion mechanism according to claim 4 or 5, wherein the anti-adhesion mechanism according to claim 4 is disposed at an upstream portion in the direction of movement of the ion-exchange resin in the rotary cylinder, and at a downstream side thereof.
The apparatus for thermally decomposing a used ion-exchange resin according to claim 2, wherein the adhesion preventing mechanism is disposed. 9. Thermal decomposition of a used ion exchange resin, wherein the volume of the used ion exchange resin is reduced by thermal decomposition in a reducing atmosphere using the apparatus according to claim 1. Method. 10. A continuous operation pyrolysis method in which a used ion exchange resin is continuously heated and thermally decomposed and reduced in volume while being moved in a rotating cylinder in a reducing atmosphere in an axial direction. The ion exchange resin is scraped off from the inner peripheral surface of the rotating cylinder by an adhesion preventing mechanism that does not change its own contact position with the inner peripheral surface of the rotating cylinder, and on the downstream side of that of the rotating cylinder. The used ion exchange resin is characterized in that the ion exchange resin is scraped off from the inner peripheral surface of the rotating cylinder by an adhesion preventing mechanism whose contact position with the inner peripheral surface of the rotating cylinder changes at any time. Thermal decomposition method.