JP2003156598A - Method and system for preventing ozone from flowing out in electron beam irradiator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a system for preventing ozone from flowing out in an electron beam irradiator which keep ozone from flowing out to an accelerator chamber and can prevent devices in the accelerator chamber from corroding. SOLUTION: The system for preventing the ozone generated in an electron beam irradiation chamber where an object is irradiated with an electron beam from flowing out to the electron beam accelerator chamber is characterized in that the system includes a detection means 25 which detects the pressure or the concentration of ozone in the electron beam irradiation chamber 23 and a warning means 25 which produces warning signals in stages when the detected pressure is below a prescribed level or when the concentration of ozone is above a prescribed level, the detection means 25 has detection areas and a means 29 for controlling a wind flow which carries out either the increase in the wind flow (A) in the accelerator chamber or the swept volume (B) of ozone or the decrease in a wind flow (C) in the electron beam irradiation chamber or both of them so that the atmospheric pressure in the accelerator chamber 23 is higher than that in the electron beam irradiation chamber 24 on the basis of the detected value when the pressure or the concentration of ozone reaches a first prescribed level is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam irradiation apparatus which achieves a desired object by irradiating a product requiring sterilization such as medical equipment and foods with an electron beam. The present invention relates to an ozone outflow prevention method and system in an electron beam irradiation apparatus for preventing ozone from flowing out into an accelerator chamber equipped with an acceleration tube of the electron beam irradiation apparatus and corroded.

[0002]

2. Description of the Related Art Conventionally, for sterilization of drinking water containers, medical equipment, etc., which have been generally required to be sufficiently sterilized, high-pressure steam sterilization, ethylene oxide gas sterilization, γ-ray sterilization, etc. are performed. Has been done. Among them, the electron beam irradiation sterilization method makes it possible to sterilize medical equipment by increasing the acceleration voltage of the electron beam, and there is no concern about heat resistance or residual toxicity of the irradiated object, and the sterilization processing time It is an extremely short time, and irradiation can be stopped instantly by turning off the power.
It has become popular in recent years because of its advantages such as high environmental safety and low cost. Furthermore, γ
As a difference from the irradiation with rays, there is a possibility that the material deterioration is small and the range of material selection is expanded as compared with the case of the irradiation with γ rays.

However, even this technique has the following problems. For example, 5 to 10 Me for the irradiated object
When a high energy electron beam of V, 25 KW is irradiated, the electron beam synthesizes air (oxygen) in the device to significantly exceed the environmental standard (0.1 ppm) of 30 to 40 ppm.
Front and rear ozone is generated. The ozone is highly oxidative and may adversely affect the human body. Further, not only is it an extremely environmental problem, but there is a risk that a worker may inhale the ozone when exchanging an object to be irradiated which is conveyed to the irradiation conveyor and sent to the outside of the apparatus.

Therefore, in order to solve such a problem,
An electron beam irradiation system having an ozone discharge mechanism (example) as shown in FIG. 3 is used. Taking FIG. 3 as an example, such a system is provided with one or a plurality of ozone suction ports 15a in an electron beam irradiation chamber such as in the vicinity of an electron beam irradiation unit where the electron beam accelerated by the accelerator 10 is irradiated, The ozone generated by the electron beam irradiation is sucked from the ozone suction port 15a while controlling the suction amount by the damper 15c. Then, the sucked ozone is guided to the ozone processing apparatus 20 through the ozone exhaust pipe 15b buried underground, and is harmless by being contacted with the catalyst in the ozone processing apparatus 20, and is discharged to the outside. As a result, damage due to ozone leakage to the outside can be minimized.

However, the influence of ozone may affect not only the outside but also the electron beam irradiation device. As shown in FIG. 1 which will be described in detail later, the electron beam irradiation apparatus has an accelerator chamber 23 in which apparatuses such as an accelerator 10 are arranged, an electron beam irradiation chamber in which an electron beam irradiation unit (scan horn) 13 and an irradiation conveyor 26 are present. 24 is separated by a shielding wall 18 (not shown in FIG. 1), and the devices arranged in the electron beam irradiation chamber 24 are made of corrosion-resistant SUS that is hard to corrode in consideration of ozone.
While a stainless steel material such as is used for the accelerator chamber 23, a material such as copper or iron is partially used for the accelerator chamber 23 due to problems of magnetic field and conductivity. Therefore, when ozone generated in the electron beam irradiation chamber 24 flows out into the accelerator chamber 23, the device using the material may be corroded, which causes a problem in durability. Further, an electric room 20 is provided as an external power source for an electric system such as an accelerator arranged in the accelerator room 23. However, ozone generated in the electron beam irradiation room 24 passes through the accelerator room 23 to generate electricity. When it flows into the room 20, there is a possibility that the equipment in the electric room may be corroded and the person working may be affected. Furthermore, when the ozone flows out in this way, the ozone will remain because the ozone suction port is not provided in the electric chamber 20 and the accelerator chamber 23.

Usually, the atmospheric pressure in the accelerator chamber 23 is kept slightly higher than the atmospheric pressure in the electron beam irradiation chamber 24. The atmospheric pressure adjustment is balanced by the ozone exhaust air volume (suction), the irradiation air conditioning air volume (discharge), and the accelerator room air conditioning air volume (discharge). However, even if there is no problem at the time of initial setting, there is a possibility that the air pressure balance may be lost due to the clogging of the filter of the air conditioning equipment, the speed change of the air conditioning fan, etc. over time. When the difference in atmospheric pressure is small, the ozone may flow out into the accelerator chamber 23 due to the rising airflow generated by the heat generated in the electron beam irradiation region 14 or the expansion of the air resulting from the temperature rise. There is also. For this reason, as the electron beam irradiation device is operated for a long time, the amount of ozone outflow increases, and the corrosion of the equipment in the accelerator chamber 23 made of a corrosive metal becomes a serious problem.

In order to solve the above problems, Japanese Patent Laid-Open No. 11-
In Japanese Patent No. 52907, it is proposed to separate the irradiation region for irradiating an irradiation object with an electron beam from a DC high-voltage power supply or the like by a barrier made of a material having high corrosion resistance such as stainless steel to prevent air from flowing. . According to this, the outflow of ozone can be prevented, and the durability of highly corrosive devices can be maintained.

[0008]

However, if such an apparatus is realized, the inflow of ozone can be blocked,
The earthquake resistance is low, and there is a risk that the device will be damaged by shaking such as an earthquake. Further, in the case of packing the connecting portion with a seal, durability may be deteriorated due to the influence of radiation such as braking X-rays generated by electron beam irradiation. Therefore, in view of such a technical problem, the present invention can prevent outflow of ozone generated in the electron beam irradiation chamber to the accelerator chamber without sealing the openings of the accelerator chamber and the electron beam irradiation chamber. An object of the present invention is to provide a method and system for preventing ozone outflow in an electron beam irradiation apparatus that can prevent corrosion of devices in the accelerator chamber and at the same time do not allow ozone to flow out through the accelerator chamber to the outside of an electrical room or the like. And

[0009]

In order to solve the above problems, the present invention provides an electron beam accelerator for ozone generated in an electron beam irradiation chamber for irradiating an irradiation object with an electron beam. In an ozone outflow prevention method for preventing outflow into a room, a detection means for detecting atmospheric pressure or ozone concentration in the room and one or a plurality of specified levels are provided in the accelerator chamber, and the atmospheric pressure or ozone concentration in the room (hereinafter referred to as detection) Signal) deviates from the specified level, the atmospheric pressure in the accelerator chamber is made higher than the atmospheric pressure in the electron beam irradiation chamber.

Further, according to a second aspect of the present invention, when the atmospheric pressure or ozone concentration in the accelerator chamber deviates from the specified level, it is stepwise according to the deviating state such as the number of deviating, the amount of deviating and the deviating cycle time. It is characterized by transmitting an alarm signal to. Further, as the method of adjusting the atmospheric pressure according to claim 1, the invention according to claim 3 is such that, at the time of the stepwise alarm transmission, the airflow in the accelerator chamber or the ozone exhaust amount is increased along with the emission of the first alarm signal. It is characterized in that the atmospheric pressure is adjusted by performing at least one air volume control among the reductions in the air volume of the radiation chamber.

The flow of ozone into the accelerator chamber is
Since the atmospheric pressure in the accelerator chamber is lower than the atmospheric pressure in the electron beam irradiation chamber, the pressure or ozone concentration in the accelerator chamber is detected and the accelerator signal in the accelerator chamber is detected by the detection signal. When it is determined that the atmospheric pressure is low, an alarm signal is transmitted according to a plurality of preset levels set in advance, and different processing is performed based on the alarm signal. As a result, appropriate processing can be performed according to the ozone concentration. Moreover, as described in claim 2,
The specified level is preferably set on the basis of the number of deviations of the detection signal, the deviation amount, the deviation cycle time, etc. at which the change in the ozone concentration in the accelerator chamber is most noticeable. Is possible.

Further, as the atmospheric pressure adjustment performed at the same time as the first alarm signal, 1. The air volume of the cooling air discharged into the accelerator chamber is increased. 2. Increase the amount of ozone exhausted from the electron beam irradiation chamber. 3. Reduce the air volume of the cooling air discharged into the electron beam irradiation chamber. Among these, at least one of the air flow rates is to be controlled. By these methods, the atmospheric pressure in the accelerator chamber can be constantly kept higher than the atmospheric pressure in the electron beam irradiation chamber, and it becomes possible to almost certainly prevent the outflow of ozone into the accelerator chamber, and by extension, the accelerator chamber. It is possible to maintain the durability of devices that are easily corroded.

In the above-mentioned air volume control method, the increase of the ozone exhaust volume may increase the system cost because the catalyst for the ozone treatment in the subsequent step is expensive, and the air volume of the electron beam irradiation chamber may decrease. However, it is impossible to make a large adjustment because the minimum air flow required to cool the equipment has been determined.
Therefore, the most preferable method is to increase the air flow rate in the accelerator chamber, but when a large pressure adjustment is required, it is preferable to appropriately control these methods by combining two or more methods. Further, the transmission of an alarm signal serving as a signal at the time of switching the atmospheric pressure adjustment based on the detection means includes a visual element such as a warning display in addition to a voice alarm signal.

According to a fourth aspect of the present invention, the specified level has a plurality of stepwise specified levels, and the detection signal reaches a second specified level, or the first alarm signal. Is transmitted continuously for a predetermined number of times or more, a second alarm signal for prompting cleaning or regeneration processing of each air conditioning facility is transmitted. This is a method to be adopted when the air pressure control by the air volume control reaches its limit, and when the pressure or ozone concentration does not return to the specified value even after the air volume control, or the first alarm signal is short-term. A second alarm signal is emitted if the alarm is repeatedly transmitted during the period. Then, the air conditioner is returned to the initial state by performing cleaning such as cleaning of the air conditioner filter, cleaning such as adjustment of the air fan, and regeneration processing in accordance with the second alarm signal, and the atmospheric pressure balance is returned to the normal operation state. Can be recovered. In this way, by performing maintenance by detecting the pressure or ozone concentration, it becomes unnecessary to stop the electron beam irradiation device for inspection, and the influence on the production line can be suppressed to a small level.

Further, as the invention according to claim 5, when the detection signal reaches the third specified level, or when the second alarm signal is continuously transmitted a predetermined number of times or more, The third that encourages the replacement of filters in air conditioning equipment
It is characterized by transmitting the warning signal of. According to this invention, similarly to the invention described in claim 4, even if the second alarm signal is transmitted many times in a short period of time or the air conditioning equipment is cleaned, the pressure or ozone concentration is still initially set. When the level does not recover, a third alarm signal is transmitted and parts of the air conditioning equipment are replaced according to the third alarm signal, whereby the same effect as in claim 4 can be obtained. .

Further, as a system for effectively implementing the above-mentioned invention, the invention according to claim 6 is a system for irradiating an object to be irradiated with an electron beam into an electron beam accelerator chamber of ozone generated in the electron beam irradiation chamber. In an ozone outflow prevention system for preventing outflow, a detection means for detecting the pressure or ozone concentration in the electron beam irradiation chamber, and when the detected pressure is below a specified level or when the ozone concentration exceeds a specified level An alarm means for transmitting an alarm signal in a stepwise manner, wherein the prescribed level has a plurality of stepwise prescribed levels, and is emitted when the pressure or ozone concentration reaches a first prescribed level. Based on the first alarm signal, an increase in the air volume in the accelerator chamber or an ozone exhaust amount, an electron beam, so that the atmospheric pressure in the accelerator chamber becomes higher than the atmospheric pressure in the electron beam irradiation chamber. Characterized by providing the air volume control means for performing at least one air volume control of the reduction of Ishitsu air volume.

Further, as the invention according to claim 7, when the detection signal level reaches the second specified level in the detection region, or when the first alarm signal is continuously transmitted a predetermined number of times or more. Further, it is characterized in that it is provided with an alarm means for transmitting a second alarm signal urging the maintenance of each air conditioner. Furthermore, as the invention according to claim 8, when the detection signal level reaches a third specified level, or when the second alarm signal is continuously transmitted a predetermined number of times or more, It is characterized in that it has an alarm means for transmitting a third alarm signal for prompting the replacement of the filter and the like. By systematizing the invention described in claims 1 to 5, an effective ozone outflow prevention system as described above becomes possible.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto unless specifically stated otherwise, and are merely illustrative examples. Not too much. FIG. 1 is an overall schematic configuration diagram of an ozone outflow prevention system according to an embodiment of the present invention, and FIG. 2 is a flowchart diagram showing an ozone outflow prevention procedure in the present embodiment.

In FIG. 1, 10 is an accelerator, 13 is a scan horn for irradiating an electron beam, and 15 is an ozone suction port 15.
a, ozone exhaust pipe 15b and damper 15c, ozone discharge means 16, 16 accelerator room air conditioner, 17 electron beam irradiation room air conditioner, 18 shield wall made of concrete or the like for blocking X-rays, 19 accelerator And the like, an electric chamber for supplying power to the device, 20 an ozone treatment device, 23 an accelerator chamber, 24 an electron beam irradiation chamber, 25 an ozone detection sensor, 29 an air volume control device, and 30 an electron beam irradiation device. In this embodiment, since the irradiation object 22 is irradiated with the electron beam from above, the accelerator chamber 23 is located above the electron beam irradiation chamber 24, but the electron beam is irradiated from the lateral direction of the irradiation object. Then, the accelerator chamber 23 and the electron beam irradiation chamber 24 may be adjacent to each other.

The electron beam irradiation device 30 includes a pulse transformer 11a and a klystron 11b for generating an electron beam, a deflection magnet 12 for determining the direction of the electron beam, an accelerator 10 for accelerating the electron beam, and a scan horn for irradiating the electron beam. 13, and the electron beam irradiation device 30 and the irradiation object 2
Since the conveyer 26 or the like which conveys 2 has heat during irradiation of the electron beam, it is cooled by passing cooling water inside. Further, in consideration of the influence of radiation such as X-rays generated from the electron beam irradiation region 14, the irradiation conveyor 26, the beam stopper 28, etc. located in the electron beam irradiation chamber 24 are made of stainless steel material such as SUS. Has been. On the other hand, iron and copper are mainly used for the accelerator 10, the deflection magnet 12, etc. in the accelerator chamber 23 from the viewpoint of magnetic field and conductivity.

Furthermore, since ozone is generated from the electron beam irradiation region 14 by the synthesis of air (oxygen), one or a plurality of ozone suction ports 15a are provided in the vicinity of the electron beam irradiation region 14. . Further, since the accelerator chamber 23 and the electron beam irradiation chamber 24 are heated by the electron beam irradiation, air conditioning equipments 16 and 17 are provided respectively. The main bodies of the air conditioning equipment 16 and 17 are arranged outside, and are configured so that cool air is supplied from the shielding wall 18 to the room through a filter.

One or a plurality of ozone detection sensors 25 are installed in the accelerator chamber 23, and an alarm device 31 connected to the sensor 25 when the ozone concentration in the accelerator chamber 23 exceeds a specified level. It is designed to work.
A signal is transmitted to the air volume control device 29 according to the type of the alarm signal, and the accelerator air conditioning equipment 16, the electron beam irradiation room air conditioning equipment 17, and the ozone exhaust equipment 15 are controlled. this is,
For example, the amount of air discharged or sucked by a fan (not shown) provided in each facility can be adjusted by a damper similarly provided in each facility.

In the alarm device 31, for example, an ozone concentration detection range in which the alarm device 31 reacts is set in advance in three stages, and the ozone concentration transmitted from the ozone detection sensor is set to the set value. In the case of indicating, the first alarm signal is transmitted at the first specified level and the air volume control device 29 is activated accordingly, and the second alarm signal is transmitted at the second specified level. Prompt cleaning of the third
At the specified level, the third alarm signal is transmitted to prompt replacement of the filter of the air conditioning equipment. Such alarm device 31
Is set to react with ozone concentration only when the first prescribed level is reached, and the second prescribed level and the third prescribed level are set to the first when the warning signal of the preceding stage is transmitted a predetermined number of times. It may be configured to issue the second and third alarm signals. The switching of the atmospheric pressure adjustment based on the detection means, the cleaning of the filter, etc., and the signal of the replacement may be a visual alarm display in addition to the sound alarm signal transmission.

An example of such an embodiment will be described with reference to the flow chart shown in FIG. The ozone detection sensor 25 is preset when the electron beam irradiation device 30 is in operation.
When the ozone concentration of the specified level is detected (S1), the detection signal is transmitted to the alarm device 31 and the first alarm signal is transmitted (S2). At the same time, the detection signal is transmitted to the air volume control device 29, and is operated so as to increase the discharge air volume A of the accelerator room air conditioner 16 based on the detected value (S3), and as a result, the air pressure in the accelerator room 23 is increased. Is higher than the internal pressure of the electron beam irradiation chamber 24. At this time, the air volume control device 29 is configured not only to control the discharge air volume A, but also to control the discharge air volume B of the electron beam irradiation chamber air conditioning equipment 17 and the suction air volume C of the ozone discharging means 15 depending on the situation. However, they may be controlled in appropriate combination. In particular, when the ozone concentration is relatively high, the discharge air volume A,
By controlling B and the suction air volume C together, it is possible to adjust the atmospheric pressure to a greater extent.

On the other hand, when the ozone detection sensor 25 detects the ozone concentration at the second specified level (S4), the second alarm signal is transmitted (S5), and the system administrator is informed of the cleaning of the air conditioning equipment such as the filter. It is notified that the time has come (S6). Further, when the detection sensor 25 detects the ozone concentration of the third specified level (S7), a third alarm signal is transmitted (S8) and prompts replacement of air conditioning equipment such as a filter (S9). Is done. In this way, when problems such as clogging are solved by cleaning and replacing the air conditioning equipment, the air conditioning air volume can be returned to a substantially initial state for operation. By repeating the above procedure, the atmospheric pressure in the system is constantly adjusted so that the atmospheric pressure in the accelerator is higher than the atmospheric pressure in the electron beam irradiation apparatus when the electron beam irradiation apparatus is in operation. Even if a pressure sensor is used instead of the ozone detection sensor, the atmospheric pressure can be adjusted by substantially the same operation.

As a result, the internal pressure of the accelerator chamber 23 is always kept higher than the internal pressure of the electron beam irradiation chamber 24, so that the ozone generated by the electron beam irradiation does not flow out into the accelerator chamber 23 and the accelerator is discharged. The durability of equipment that is susceptible to corrosion in the room is maintained. Furthermore, from the accelerator room to the electrical room 2
It is possible to prevent the outflow of ozone to the outside such as 0, prevent the harm to the human body, and become a system with little environmental impact.

[0027]

The ozone generated in the electron beam irradiation region can be prevented from flowing out to the accelerator chamber without sealing the openings of the accelerator chamber and the electron beam irradiation chamber, and the corrosion of the device in the accelerator chamber can be prevented. In addition, it is possible to prevent ozone from flowing out of the accelerator room to the outside of the electric room or the like, and to prevent harm to the human body and to make the system environmentally less affected.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram of an ozone outflow prevention system according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an ozone outflow prevention procedure in the present embodiment.

FIG. 3 is a schematic configuration diagram showing an ozone exhaust system in a conventional technique.

[Explanation of symbols]

10 accelerator 14 Electron beam irradiation area 15 Ozone suction port 16 Accelerator room air conditioner 17 Electron beam irradiation room air conditioning equipment 18 Shielding wall 19 Electric room 20 Ozone treatment equipment 21 Ozone exhaust pipe 23 Accelerator room 24 Electron beam irradiation room 25 Ozone detection sensor 29 Air flow controller 30 electron beam irradiation device 31 Alarm device

Claims (8)

[Claims] 1. An ozone outflow prevention method for preventing ozone generated in an electron beam irradiation chamber for irradiating an irradiation object with an electron beam from flowing into an electron beam accelerator chamber, wherein atmospheric pressure or ozone in the chamber is provided in the accelerator chamber. A detection means for detecting the concentration and one or more specified levels are provided, and when the atmospheric pressure in the room or the ozone concentration (hereinafter referred to as a detection signal) deviates from the specified level, the electron pressure is applied to the atmospheric pressure in the accelerator room. A method for preventing ozone outflow in an electron beam irradiation apparatus, characterized in that the pressure is made higher than the atmospheric pressure in the room. 2. When the atmospheric pressure or ozone concentration in the accelerator chamber deviates from the specified level, a warning signal is transmitted stepwise according to the deviating state such as the number of deviating, the amount of deviating, and the deviating cycle time. The method for preventing ozone outflow in an electron beam irradiation apparatus according to claim 1, which is characterized in that. 3. When the stepwise alarm is issued, the first
The air pressure is adjusted by performing at least one air volume control of increasing the accelerator air volume or ozone exhaust air volume and decreasing the electron beam irradiation chamber air volume in addition to the transmission of the alarm signal. Method for preventing ozone outflow in electron beam irradiation device. 4. The specified level has a plurality of stepwise specified levels, and when the detection signal reaches a second specified level, or the first alarm signal is transmitted continuously a predetermined number of times or more. In the case of being caused, a second alarm signal for prompting cleaning or regeneration processing of each air conditioning equipment is transmitted, and the ozone outflow prevention method in the electron beam irradiation apparatus according to claim 3, characterized in that. 5. When the detection signal reaches a third specified level, or when the second alarm signal is continuously transmitted a predetermined number of times or more, the filters of the air conditioning equipment should be replaced. The ozone outflow prevention method in an electron beam irradiation apparatus according to claim 4, wherein a third alarm signal for prompting is transmitted. 6. An ozone outflow prevention system for preventing outflow of ozone generated in an electron beam irradiation chamber for irradiating an object to be irradiated with an electron beam into an electron beam accelerator chamber, wherein pressure or ozone concentration in the electron beam irradiation chamber. And a warning means for gradually outputting a warning signal when the detected pressure does not reach the specified level or the ozone concentration exceeds the specified level. Based on a first alarm signal that is output when the pressure or the ozone concentration reaches a first specified level, the atmospheric pressure in the accelerator chamber is set to a level within the electron beam irradiation chamber. An air volume control means for controlling at least one of the increase in the air volume in the accelerator chamber or the exhaust gas in the ozone chamber and the decrease in the air volume in the electron beam irradiation chamber so that the air pressure is higher than the atmospheric pressure is provided. An ozone outflow prevention system in an electron beam irradiation device, comprising: 7. The detection signal level is second in the detection region.
When the first warning signal has been reached, or when the first warning signal has been continuously sent a predetermined number of times or more, a warning means for sending a second warning signal for urging the maintenance of each air conditioner is provided. The ozone outflow prevention system in the electron beam irradiation apparatus according to claim 6. 8. When the detection signal level reaches a third prescribed level, or when the second alarm signal is continuously transmitted a predetermined number of times or more, it is urged to replace the filter or the like of each air conditioning facility. 8. An ozone outflow prevention system for an electron beam irradiation apparatus according to claim 7, further comprising an alarm means for transmitting a third alarm signal.