JP5498052B2 - Closed rotary incinerator - Google Patents

Description

The present invention relates to a closed rotary incinerator for incinerating radioactive waste .

  At present, the use of radioisotopes (hereinafter referred to as RI) is an essential means in the field of scientific research. Regarding the handling of RI, the “Act on the Prevention of Radioactive Disorders Caused by Radioisotopes” applies. Therefore, when disposing of radioactive waste such as instruments used in RI experiments, necessary measures must be taken to prevent radiation damage.

  Conventionally, radioactive wastes such as instruments used in RI experiments have been stored as they are, but from the viewpoint of storage space, there has been a demand for technology for incinerating combustible parts. The main premise as a characteristic that the radioactive waste incinerator should have is that no radioactive material leaks outside the furnace in all processes.

  In addition, although the equipment used for the RI experiment includes a syringe needle and a glass container, from the viewpoint of reducing the amount of exposure, these metal wastes and glass wastes are not separated and are incinerators as they are. It is preferable that it can be introduced into Moreover, it is preferable that the metallic waste and the glassy waste are discharged together with the incineration ash without melting in the incinerator, and further, the incineration ash in which these metallic waste and glass waste are mixed is used. It is preferable that it can be easily discharged.

  With respect to ordinary incinerators such as municipal waste, a technology of a rotary incinerator that has excellent combustion efficiency and can easily discharge incineration ash has been disclosed (Patent Document 1). The rotary incinerator heats and drys the incineration object charged from the incineration object input port provided at one end of the furnace while rotating in a state where the center line of the conical cylindrical furnace body is horizontal. The incineration object can be sufficiently dried by moving toward the other end and approaching the fire source of the burner through the drying process. Further, the rotary incinerator has a structure in which the other end opening of the incineration object inlet is rotatably fitted to the flue, and an ash outlet is provided at the bottom of the flue. Therefore, the ash which burned the incineration object and became ash can be discharged continuously, and the discharge property of the incineration ash is excellent.

  In a rotary incinerator, as a means to prevent the combustion gas from leaking from the openings at both ends of the conical cylindrical furnace body, the openings are covered with a heat-resistant cloth seal, etc. A method of keeping the inside of the furnace at a negative pressure is generally adopted. However, since this method does not completely seal the sealing portion, for example, when a large amount of alcohol or oil that burns rapidly is mixed, it may be difficult to maintain the negative pressure in the furnace. For this reason, as described above, it has been difficult to adopt a conventional rotary incinerator as a radioactive waste incinerator that is required as a major premise that no leakage of radioactive material occurs outside the furnace.

Japanese Patent Laid-Open No. 5-52314

  An object of the present invention is a sealed rotary incinerator that does not cause leakage of radioactive materials outside the furnace, and can be put into an incinerator as it is without separating metallic waste and glass waste. It is to provide a hermetic rotary incinerator excellent in discharging incineration ash mixed with metallic waste and glass waste.

A hermetic rotary incinerator according to the present invention, which has been made to solve the above problems, has a rotary drum whose outer periphery is rotatably supported by a rotary support means so that its central axis is horizontal, and a hermetically sealed outer periphery. The outer shell of the structure, a radioactive waste input part that penetrates the outer shell and reaches one end of the rotating drum, and an exhaust gas outlet connected to the other end of the rotating drum, the radioactive waste input part is radioactive It is equipped with a pusher that puts waste into the center axis position of the rotating drum, and a heat-shielding damper that opens the charging path only when radioactive waste is put in by the pusher. after passing through the use damper is configured to be supplied into the rotary drum, these radioactive wastes insertion portion and the exhaust gas outlet portion are flange connected hermetically to each shell, the lower portion of the exhaust gas outlet portion The radioactive waste combustion burners blowing flames into the rotary drum is provided, on the bottom of the exhaust gas outlet portion is characterized in the provision of the incineration residue 渣排 outlet.

  According to a second aspect of the present invention, in the sealed rotary incinerator according to the first aspect, the outer shell is provided with a combustion air inlet, and is introduced into the outer shell from the combustion air inlet, so that heat from the surface of the rotary drum can be obtained. Combustion air flow means for introducing air heated by absorption into the rotating drum is provided.

  According to a third aspect of the present invention, in the sealed rotary incinerator according to the first aspect of the present invention, the outer shell pressure detecting means and the outer shell pressure adjusting means are provided.

  According to a fourth aspect of the present invention, in the sealed rotary incinerator according to any one of the first to third aspects, the rotary drum electric drive means is provided outside the outer shell.

  The invention according to claim 5 is the sealed rotary incinerator according to any one of claims 1 to 4, characterized in that the radioactive waste input part has a double damper structure.

A sixth aspect of the present invention is the sealed rotary incinerator according to any one of the first to sixth aspects, wherein the radioactive waste charging section is provided with a water spray nozzle for supplying spray water into the rotary drum. The exhaust gas outlet is provided with a temperature measuring nozzle and a water spray nozzle that opens in the direction of the rotating drum.

  In the sealed rotary incinerator according to the present invention, the outer shell that houses the rotary drum is connected to the radioactive waste input part and the exhaust gas outlet part by flanges, respectively, and the outer shell has a sealed structure. Even if alcohol or oil that burns rapidly is mixed in, it becomes difficult to maintain the negative pressure inside the rotating drum, and even if combustion gas leaks outside the rotating drum, There is no worry about leakage of radioactive material.

Further, the sealed rotary incinerator according to the present invention is a radioactive waste combustion burner provided at the lower part of the exhaust gas outlet part while rotating the radioactive waste introduced from the radioactive waste input part in the rotary drum. Since it can be sufficiently heated and dried before it approaches the fire source, the radioactive waste can be burned efficiently without causing the problem of dust scattering due to external stirring. Furthermore, the closed rotary incinerator according to the present invention is provided with a bottom incineration residue discharge port at the exhaust gas outlet and is excellent in incineration ash discharge, so that incineration ash mixed with metallic waste and glass waste Can be easily discharged. Therefore, radioactive metallic waste and glass waste can be put into the incinerator without being separated, and the amount of exposure of workers in the incinerator process can be reduced. Furthermore, according to the present invention, the temperature in the radioactive waste input unit is increased by the radiant heat from the inside of the rotating drum, by providing a heat shield damper that opens the input path only when the radioactive waste is input by the pusher. The risk of flammable substances such as solvents igniting in the radioactive waste input section can be avoided .

  According to the second aspect of the present invention, the air introduced into the outer shell from the combustion air inlet provided in the outer shell absorbs heat from the surface of the rotating drum. The thickness of the refractory material lined inside the rotating drum can be reduced, and the rotating drum can be downsized. In addition, since air heated by heat absorption from the surface of the rotating drum can be introduced into the rotating drum as combustion air, it has excellent thermal efficiency and contributes to reduction of carbon dioxide emissions.

  According to the third aspect of the invention, the outer shell pressure detecting means and the outer shell pressure adjusting means enable negative pressure management of the sealed rotary incinerator, and leakage of radioactive material to the outside of the sealed rotary incinerator. Can be prevented more reliably.

  According to the invention described in claim 4, by providing the rotary drum electric drive means outside the outer shell, the maintainability is improved, and the amount of exposure of the worker during maintenance can be reduced.

  According to the fifth aspect of the present invention, since the radioactive waste charging section has a double damper structure, it is possible to maintain a negative pressure inside the outer shell even when the waste is charged, and the outside of the rotary rotary incinerator is closed. It is possible to prevent leakage of radioactive material to

According to the sixth aspect of the present invention, the radioactive waste input part is provided with a water spray nozzle for supplying spray water into the rotary drum, and the exhaust gas outlet part has a temperature measurement nozzle and a rotary drum direction. By providing the opened water spray nozzle, the temperature distribution can be controlled so that the inlet portion and the outlet portion in the rotating drum have preferable temperatures. In addition, it is possible to prevent overheating of the temperature inside the rotating drum, prevent melting of glass waste contained in the waste, and extend the life of the refractory.

Side surface sectional drawing in one Embodiment of the enclosed rotary incinerator which concerns on this invention AA sectional view in FIG. Side sectional view of a closed rotary incinerator in another embodiment Sectional drawing which shows the sealing structure of a rotating drum and a radioactive waste input part Sectional drawing which shows the sealing structure of a rotating drum and an exhaust gas exit part

  FIG. 1 shows a side cross-sectional view of an embodiment of a sealed rotary incinerator according to the present invention, and FIG. 2 shows a cross-sectional view taken along line AA in FIG. FIG. 3 shows a side sectional view of a closed rotary incinerator in another embodiment.

The configuration of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the sealed rotary incinerator of the present invention includes a radioactive waste input unit 1, an exhaust gas outlet unit 2, a rotary drum 3, and an outer shell 4.

  The rotating drum 3 has a structure in which a refractory material is lined on the inner surface of SUS or carbon steel, and is rotatably supported so that the center line is horizontal between the radioactive waste input part 1 and the exhaust gas outlet part 2. Has been. The gap 5 between the rotary drum 3 and the radioactive waste input part 1 is covered with a seal member 7 as shown in FIG. 4, and the gap 6 between the rotary drum 3 and the exhaust gas outlet part 2 is sealed as shown in FIG. The member 7 is covered.

  The seal member 7 is a heat-resistant cloth seal or the like, and the rotary drum 3 is slidably in contact therewith. The electric drive means 14 is provided outside the outer shell 4 from the viewpoint of maintainability, and the portion where the rotary drum electric drive means 14 penetrates the outer shell 4 is secured with an oil seal to ensure the hermeticity of the outer shell 4. ing.

  The outer shell 4 is made of carbon steel and has a structure in which the rotary drum 3 is rotatably mounted by the rotary support means 20 as shown in FIG. Of the openings 8 provided at both ends of the outer shell 4, the radioactive waste input portion 1 is flange-connected at one end, and the exhaust gas outlet portion 2 is flange-connected at the other end, and the inside of the outer shell 4 has a sealed structure. . The outer shell 4 includes a combustion air inlet 12 and a combustion air flow means 13, and further includes an outer shell internal pressure detection means 15, an outer shell internal pressure adjustment means, and a relief valve mounting nozzle 16.

The radioactive waste input unit 1 is provided with a double stack of radioactive waste input dampers 9a and 9b at the input port, and a pusher 10 for inputting the radioactive waste into the central axis position of the rotary drum at the bottom. ing.

  The radioactive waste charging unit 1 further includes a heat shielding damper 21 for shielding radiant heat from the inside of the rotary drum 3 on the lower tip side. It is preferable that the heat-shielding damper 21 is provided on the rotating drum 3 side as much as possible in the radioactive waste charging unit 1 to prevent a temperature rise in the radioactive waste charging unit 1. The heat shield damper 21 is provided with an opening / closing mechanism, and is normally opened only when the radioactive waste is put into the rotating drum 3 so that the temperature inside the radioactive waste throwing portion 1 is prevented from rising. doing.

  Further, a water spray nozzle 22 for supplying spray water into the rotary drum 3 is provided on the outer periphery of the lower end of the radioactive waste input unit 1. The water spray nozzle 22 is stored in a water spray nozzle storage box portion 23 fixedly formed on the outer peripheral side of the lower end of the radioactive waste input portion 1.

  At the lower part of the exhaust gas outlet 2, a radioactive waste combustion burner 11 having a nozzle opened in the direction of the rotary drum 3 is provided, and an incineration residue outlet 17 is provided at the bottom. Further, the exhaust gas outlet portion includes a temperature measuring nozzle 18 and a water spray nozzle 19 opened in the direction of the rotating drum.

  Hereinafter, the operation of the above configuration will be described.

  The sealed rotary incinerator according to the present invention is an incinerator for incineration of radioactive waste such as instruments used in RI experiments. Instruments used for RI experiments include injection needles and glass containers, but from the viewpoint of reducing the amount of exposure, do not separate these metal wastes and glass wastes and put them directly into the incinerator. Is preferred. In general, radioactive wastes are stored in bags or containers in RI facilities and the like, and the sealed rotary incinerator according to the present invention directly stores them (without sorting and in bags and containers). Can be introduced into

  Since the radioactive waste input dampers 9a and 9b are provided in two stages at the input port of the radioactive waste input unit 1, when the waste is input, the radioactive waste input damper 9a is first opened, and the radioactive waste is input. The damper 9b is closed and charged with radioactive waste, and then the radioactive waste charging damper 9a is closed, and then the radioactive waste charging damper 9b is opened and the radioactive waste is placed below the radioactive waste charging unit 1. throw into.

When the radioactive waste charging damper 9b is opened and the amount of radioactive waste charged into the lower portion of the radioactive waste charging unit 1 reaches a predetermined amount, the heat shielding damper 21 is opened and the pusher 10 is used to open the center of the rotary drum 3 . Put radioactive waste into the shaft position .

  Thus, by providing the radioactive waste input dampers 9a and 9b in two stages in the radioactive waste input part 1, it is possible to keep the outer shell 4 and the inside of the rotary drum 3 at a negative pressure even when the radioactive waste is input. Thus, leakage of radioactive material can be effectively prevented, and the amount of exposure to the worker can be reduced.

  Furthermore, by providing a heat-shielding damper 21 at the lower tip side of the radioactive waste input unit 1, the temperature in the radioactive waste input unit 1 rises due to the radiant heat from the rotating drum 3, and the radioactive waste is disposed. It is possible to avoid a danger that a flammable substance such as a solvent is ignited in the material input unit 1.

  The rotary drum 3 is rotatably supported so that the center line is horizontal between the radioactive waste input part 1 and the exhaust gas outlet part 2, and the gaps 5 and 6 are covered with the seal member 7, The seal member 7 is a heat-resistant cloth seal or the like and has a structure in which the rotary drum 3 is slidably contacted. Although the sealing performance of the portion is not perfect, during normal operation, the air in the rotary drum 3 is kept at a negative pressure by the exhaust gas fan connected to the exhaust gas outlet portion 2, and the radioactive material is released from the gap of the seal member 7. There is no leakage. However, for example, when a large amount of volatile components such as alcohol and oil are mixed in the rotating drum 3 and runaway occurs due to fluctuations in combustion conditions, it becomes difficult to maintain the air in the rotating drum 3 at a negative pressure. There is a possibility that leakage of radioactive material may occur from the gap between the seal members 7. Therefore, in the present invention, the outer shell 4 is provided so as to cover the entire rotating drum 3 and the inside of the outer shell 4 has a sealed structure, so that the structure can cope with the above-described fluctuations in combustion conditions.

  The radioactive waste introduced into the rotary drum 3 is heated and dried while moving toward the other end of the rotary drum 3 as the rotary drum 3 rotates, and the radioactive waste provided at the lower part of the exhaust gas outlet portion 2. It burns near the fire source of the product combustion burner 11.

Combustion air is mainly supplied from the lower end of the burner 11. In addition, combustion air introduced from a combustion air introduction port 12 provided in the outer shell 4 is supplied into the rotary drum 3 through a pipe 13 a connected to the radioactive waste charging unit 1. In addition, although the heat insulation damper 21 is provided in the lower front end side of the radioactive waste injection | throwing-in part 1, this heat insulation damper 21 is not the objective of ensuring the sealing property of partition space, and heat insulation. Any effect can be obtained, and a gap is provided to ensure the flow of combustion air from the pipe 13a into the rotary drum 3. The combustion air supplied into the rotary drum 3 through the pipe 13 a passes through the heat insulation damper 21 and is supplied into the rotary drum 3.

  Further, as shown in FIG. 3, the combustion air introduced from the combustion air introduction port 12 provided in the outer shell 4 is inserted into the rotary drum 3 from the vicinity of the fire source of the burner 11 through the pipe 13b with the ejection nozzle. A method of feeding into the rotating drum 3 can also be adopted.

  The combustion air introduced from the combustion air inlet 12 provided in the outer shell 4 also has an action of absorbing heat from the surface of the rotating drum 3 and the surface of the outer shell 4. The surface temperature of the rotating drum 3 is preferably 350 to 400 ° C. or less from the viewpoint of allowable stress, and the surface temperature of the outer shell 4 is preferably 80 ° C. or less from the viewpoint of preventing damage. As a means for setting such a surface temperature, there is a method of using a material excellent in heat insulation, such as constructing a heat insulating material on the inner surface of the outer shell 4, thickening a refractory material lining on the inner surface of the rotating drum 3, Either of these is not desirable because it leads to an increase in the size and cost of the incinerator. In this regard, according to the heat exchange method using combustion air as in the present invention, the above-described disadvantages can be avoided, and the incinerator can be reduced in size and cost. Part of the combustion air after heat absorption enters the rotary drum 3 through the gap between the seal members 7, and the rest is supplied into the rotary drum 3 through the pipes 13a and 13b.

  The closed rotary incinerator according to the present invention is an incinerator for incineration of radioactive waste such as instruments used in RI experiments, and the waste may contain a lot of flammable substances such as solvents. . In such a case, it is possible to control the inlet side 3a of the rotary drum 3 to have a temperature distribution of 300 to 400 ° C. and the outlet side 3b to have a temperature distribution of 700 to 800 ° C. to prevent rapid combustion of the flammable substance. preferable. In the present invention, as means for realizing the temperature distribution, a water spray nozzle 22 for supplying spray water into the rotary drum 3 is provided on the outer periphery of the lower end of the radioactive waste input unit 1. The liquid sprayed from the water spray nozzle 22 can lower the refractory temperature on the inlet side 3a of the rotary drum 3. In addition, as a liquid sprayed from the water spray nozzle 22, a waste liquid used in the RI experiment can be used to treat the RI experimental waste liquid at the same time. However, the means for obtaining the temperature distribution is not limited to water spraying, and means such as supply of compressed air can also be employed.

  The outlet side 3b of the rotary drum 3 has a temperature inside the rotary drum 3 of about 800 ° C. due to the energy from the heat source of the radioactive waste combustion burner 11 provided at the lower part of the exhaust gas outlet portion 2 and the combustion energy of the radioactive waste. Is maintained. When the temperature in the rotating drum 3 exceeds about 900 ° C., the viscosity of the glass mixed in the radioactive waste increases. From the viewpoint of the refractory life, it is preferable to prevent the melting of the glass. As the glass melting prevention means, when the exhaust gas outlet portion 2 is provided with a temperature measuring nozzle 18 and a water spray nozzle 19 and the temperature inside the rotating drum 3 is overheated to exceed about 900 ° C. even when the burner 11 is stopped. The water can be sprayed so that the temperature on the outlet side 3b of the rotary drum 3 is about 800 ° C.

  The incineration residue remaining after the waste incineration in the rotary drum 3 is discharged from an incineration residue discharge port 17 provided at the bottom of the exhaust gas outlet portion 2. The incineration residue discharge port 17 is connected to a vibration conveyor or screw driver conveyor having a sealed structure, and is sent to the next process while keeping the sealed state. Therefore, in the incineration residue discharge process of the present invention, the radioactive substance leaks to the outside. It is a structure that can be processed safely without doing.

  The outer shell pressure detection means 15 provided in the outer shell 4 detects the pressure in the outer shell 4, and the pressure in the outer shell 4 is -0.5 to -5 kPa, preferably -1 to -2 kPa. In this way, it is adjusted by the outer pressure control means. For example, an exhaust gas blower and a pressure control valve can be employed as the pressure control means in the outer shell. In addition, the outer shell 4 is provided with a relief valve mounting nozzle 15 and connected to the relief valve and the HFPA filter, so that a large amount of volatile substances are mixed in the waste and burnt rapidly, and the inside of the rotary drum 3 and Even when the pressure in the outer shell 4 becomes a positive pressure, the radioactive substance can be safely processed without leaking out of the outer shell 4.

  The outer shell 4 has a combustion air inlet 12, and a part of the combustion air is introduced into the outer shell 4 from the combustion air inlet 12 to absorb heat from the surface of the rotating drum 3 and the surface of the outer shell 4. I let you. Thereby, the surface of the rotating drum 3 and the surface of the outer shell 4 can be cooled. The surface temperature of the rotating drum 3 is preferably 350 to 400 ° C. or less from the viewpoint of allowable stress, and the surface temperature of the outer shell 4 is preferably 80 ° C. or less from the viewpoint of preventing damage. As a means for setting such a surface temperature, there is a method of using a material excellent in heat insulation, such as constructing a heat insulating material on the inner surface of the outer shell 4, thickening a refractory material lining on the inner surface of the rotating drum 3, Either of these is not desirable because it leads to an increase in the size and cost of the incinerator. In this regard, according to the heat exchange method using combustion air as in the present invention, the above-described disadvantages can be avoided, and the incinerator can be reduced in size and cost. Part of the combustion air after heat absorption enters the rotary drum 3 through the gap between the seal members 7, and the rest is sent into the rotary drum 3 by the combustion air flow means.

DESCRIPTION OF SYMBOLS 1 Radioactive waste input part 2 Exhaust gas outlet part 3 Rotary drum 3a Inlet side 3b Outlet side 4 Outer shell 5 Gap between rotary drum and radioactive waste input part 6 Gap between rotary drum and exhaust gas outlet part
7 Seal member 8 Openings 9a and 9b Damper 10 for loading radioactive waste Pusher 11 Burner 12 for burning radioactive waste Combustion air inlet 13 Combustion air flow means 13a and 13b Piping 14 Rotating drum electric drive means 15 Pressure detection in outer shell Means 16 Relief valve mounting nozzle 17 Incineration residue outlet 18 Temperature measurement nozzle 19 Water spray nozzle 20 Rotary support means 21 Heat shield damper 22 Water spray nozzle 23 Water spray nozzle storage box

Claims (6)

A rotating drum whose outer periphery is rotatably supported by a rotary support means so that the central axis is horizontal, a sealed outer shell that covers the outer periphery, and a radioactive waste that penetrates the outer shell and reaches one end of the rotating drum An object input part, and an exhaust gas outlet connected to the other end of the rotating drum,
The radioactive waste charging unit includes a pusher for charging the radioactive waste into the central axis position of the rotary drum, and a heat shield damper that opens the charging path only when the radioactive waste is charged by the pusher.
The air introduced into the outer shell is configured to be supplied into the rotary drum after passing through the heat shield damper,
These radioactive waste input part and exhaust gas outlet part are airtightly flange-connected to the outer shell,
At the lower part of the exhaust gas outlet part, a burner for radioactive waste combustion that blows flame into the rotating drum is installed,
A closed rotary incinerator characterized in that an incineration residue discharge port is provided at the bottom of the exhaust gas outlet. The outer shell has a combustion air inlet,
2. The combustion air flow means for introducing the air introduced into the outer shell from the combustion air inlet and heated up by heat absorption from the surface of the rotating drum into the rotating drum. Closed rotary incinerator.   2. The hermetic rotary incinerator according to claim 1, further comprising outer shell internal pressure detecting means and outer shell pressure adjusting means.   The hermetic rotary incinerator according to any one of claims 1 to 3, wherein the rotary drum electric drive means is provided outside the outer shell.   The sealed rotary incinerator according to any one of claims 1 to 4, wherein the radioactive waste charging section has a double damper structure.   The radioactive waste input part was equipped with a water spray nozzle for supplying spray water into the rotating drum, and the exhaust gas outlet part was provided with a temperature measuring nozzle and a water spray nozzle opened in the direction of the rotating drum. A sealed rotary incinerator according to any one of claims 1 to 5.

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