JP2001108800A - Electron beam irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably prevent ozone produced due to electron beam irradiation in an irradiation chamber from leaking out of the irradiation chamber without being affected by external factors. SOLUTION: This device is equipped with a pressure sensor 30 for detecting pressure in the irradiation chamber 10, and a control device 32 for controlling the speed of an exhaust blower 24 in response to a signal from the pressure sensor 30 so that the pressure in the chamber 10 can be kept at a specified negative pressure during the irradiation of an electron beam 6.

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 system for irradiating an object to be irradiated with an electron beam emitted from an electron beam accelerator in an irradiation chamber, and subjecting the object to treatments such as crosslinking, polymerization, curing and sterilization. More specifically, the present invention relates to an improvement in means for preventing ozone generated in an irradiation chamber due to electron beam irradiation from leaking out of the irradiation chamber.

[0002]

2. Description of the Related Art A conventional example of this type of electron beam irradiation apparatus is shown in FIG.
Shown in The electron beam irradiation apparatus irradiates the object 8 with the electron beam 6 emitted from the electron beam accelerator 2 while conveying the belt-shaped object 8 through the irradiation chamber 10 as shown by arrows A, B, and C. Then, the irradiation object 8 is configured to be subjected to processing such as crosslinking, polymerization, curing, and sterilization.

[0003] X-rays (brake X-rays) are generated from the irradiated object 8 and the like in accordance with the irradiation of the electron beam 6. In order to shield the X-rays, the irradiation chamber 10 is provided with a box having an X-ray shield such as lead. The body is formed. Slits 12 and 14 are provided at the entrance and exit of the irradiation object 8, respectively. In addition, an air supply pipe 20 and an exhaust pipe 26 which will be described later.
Actually meanders near the portion penetrating the wall of the irradiation chamber 10 to prevent X-ray leakage.

The electron beam accelerator 2 is of a scanning type in this example, and scans the electron beam 6 in a direction (in this example, the front and back sides of the paper) orthogonal to the conveying direction of the irradiation object 8 (the direction of arrow B). Inject while doing. An irradiation window 4 for separating the vacuum atmosphere inside the electron beam accelerator 2 and the air atmosphere outside the electron beam accelerator 2 and having a window foil for transmitting the electron beam 6 is provided at an emission portion of the electron beam 6. ing. This type of irradiation window
For example, it is described in JP-A-11-95000.

The window foil of the irradiation window 4 generates heat due to the transmission loss of the electron beam 6. For this measure, a cooling blower (blower) 18 is provided outside the irradiation chamber 10, and the air 16 sucked by the cooling blower 18 is guided to the vicinity of the irradiation window 4 through an air supply pipe 20. Air 16 is blown from the provided nozzle 21 to the irradiation window 4 (more specifically, the window foil; the same applies hereinafter) to cool the irradiation window 4.

When the object 8 is irradiated with the electron beam 6, the electron beam 6 collides with oxygen molecules in the air, so that ozone is generated from the passage of the electron beam 6. This ozone is undesirable for the human body. Further, it may be a cause of causing a chemical change in the irradiation object 8. For this measure,
An exhaust blower (blower) 24 is provided outside the irradiation chamber 10, and the ozone-containing air 22 in the irradiation chamber 10 is discharged to a predetermined place (ie, even if the ozone-containing air 22 is discharged) via the exhaust pipe 26. (Where it does not matter).

The exhaust capacity of the exhaust blower 24 (more specifically, the amount of blown air; the same applies hereinafter) is made somewhat larger than the air supply capacity (blowing amount) of the cooling blower 18, whereby the irradiation chamber is exposed. 10 is evacuated to a somewhat negative pressure (eg, 99.8 kPa or more and less than 101 kPa). The reason for making the pressure somewhat negative is that the slits 12 and 14
This is to prevent ozone from leaking to the surroundings.

Each of the blowers 18 and 24 includes blades and a motor for rotating the blades. Conventionally, these two blowers 18 and 24 are
It is driven by AC power of commercial frequency.

In some cases, an ozone treatment device 28 having an ozone adsorbent and removing ozone is provided in the exhaust pipe 26.

[0010]

The layout of the electron beam irradiation apparatus and the piping system for supplying and exhausting gas are usually different between the time of adjustment in the factory and the time of installation at the actual installation location.

In such a case, for example, the exhaust pipe 26
The pressure drop at is greater than initially expected,
It is possible that the exhaust capacity of the irradiation chamber 10 by the exhaust blower 24 becomes low, and the inside of the irradiation chamber 10 becomes a positive pressure. Then, from the irradiation room 10, the slits 12, 14
Ozone leaks to the surroundings through a gap between a maintenance inspection door (not shown) and the like. This is undesirable for the human body.

Also, when the ozone treatment device 28 is provided on the exhaust side, pressure loss in the exhaust system increases due to clogging of the filter in the ozone treatment device 28 and aging of the ozone adsorbent. Problems similar to the above can occur.

Therefore, the present invention is to prevent ozone generated in the irradiation chamber from leaking out of the irradiation chamber due to electron beam irradiation.
It is a main object of the present invention to provide an electron beam irradiation device that can stably prevent the irradiation without being influenced by external factors.

[0014]

An electron beam irradiation apparatus according to the present invention controls a pressure sensor for detecting a pressure in the irradiation chamber, and controls the exhaust blower in response to a signal from the pressure sensor. A control device for controlling the number of revolutions of the exhaust blower so that the pressure in the irradiation chamber becomes a negative pressure during the line irradiation.

According to the above construction, the pressure loss in the piping system for supplying / exhausting air to / from the irradiation chamber is not affected by external factors such as the magnitude of the pressure loss in the piping system and the magnitude of the pressure loss in the case where the ozone treatment apparatus is provided. It is possible to stably maintain the pressure in the irradiation chamber during electron beam irradiation at a predetermined negative pressure. Therefore, it is possible to stably prevent the ozone generated in the irradiation chamber from leaking out of the irradiation chamber due to the electron beam irradiation, without being influenced by external factors.

[0016]

FIG. 1 is a schematic view showing an example of an electron beam irradiation apparatus according to the present invention. Parts that are the same as or correspond to those of the conventional example shown in FIG. 2 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.

This electron beam irradiation apparatus controls a pressure sensor 30 for detecting the pressure in the irradiation chamber 10 and an exhaust blower 24 in response to a signal from the pressure sensor 30, so that the irradiation object 8 can be irradiated. During the irradiation of the electron beam 6, the pressure in the irradiation chamber 10 is always a predetermined negative pressure (for example, 99.8 kPa or more and 101 k
And a control device 32 that controls the number of revolutions of the exhaust blower 24 so as to control the exhaust capacity of the exhaust blower 24 so as to be less than Pa.

As in the case of the conventional example, the exhaust capacity of the exhaust blower 24 is made larger than the air supply capacity of the cooling blower 18, but the difference in performance between the two blowers 18, 24 differs from that of the conventional example. It is preferable to make it larger than the case. By doing so, there is a margin in the exhaust capacity of the exhaust blower 24, so that control of the pressure in the irradiation chamber 10 by controlling the exhaust capacity of the exhaust blower 24 by the control device 32 becomes easier.

In this example, the control device 32 includes a rotation speed control unit 34 for controlling the rotation speed of the exhaust blower 24 (more specifically, its motor), and the rotation speed control unit 34 in response to a signal from the pressure sensor 30. And a control unit 36 for controlling the number control unit 34 and, consequently, controlling the rotation speed of the exhaust blower 24.

The rotation speed control unit 34 includes, for example, a rectifier circuit that receives AC power AC having a commercial frequency and converts the AC power into DC power, converts the DC power from the rectifier circuit into AC power, and converts the DC power from the rectifier circuit into AC power. And an inverter that supplies the power to the inverter. The control unit 36 controls the rotation speed of the exhaust blower 24, for example, by controlling the frequency of the AC power output from the inverter.

According to this electron beam irradiation apparatus, the irradiation room 10
Even if the pressure loss in the piping system changes from what was initially anticipated due to differences in the piping system for supply and exhaust air to the plant between adjustment at the factory and installation at the actual installation location, such external The pressure in the irradiation chamber 10 during electron beam irradiation can be stably maintained at a predetermined negative pressure without being influenced by factors.

When the ozone treatment device 28 is provided on the exhaust side, even if the pressure loss in the ozone treatment device 28 changes due to aging or the like, the ozone treatment device 28 is stably not affected by such external factors. , Irradiation room 1 during electron beam irradiation
The pressure within 0 can be kept at a predetermined negative pressure.

If the inside of the irradiation chamber 10 is maintained at a negative pressure, that is, if the inside of the irradiation chamber 10 is prevented from becoming a positive pressure, ozone leaks out of the irradiation chamber 10 from the slits 12 and 14 and gaps between the doors. Can be prevented. All ozone generated in the irradiation chamber 10 is discharged to a predetermined place by the exhaust blower 24. Therefore, according to this electron beam irradiation apparatus,
Leakage of ozone generated in the irradiation chamber 10 due to electron beam irradiation to the outside of the irradiation chamber 10 can be stably prevented without being influenced by external factors.

Further, the exhaust fan 24 is always operated with an appropriate output under the control of the control device 32, so that wasteful power consumption is suppressed and the exhaust fan 2 is controlled.
4 can save power consumption.

[0025]

As described above, according to the present invention, external factors such as the magnitude of the pressure loss in the piping system for supplying and exhausting air to and from the irradiation chamber and the magnitude of the pressure loss in the case where an ozone treatment apparatus is provided. It is possible to stably maintain the pressure in the irradiation chamber during electron beam irradiation at a predetermined negative pressure without being affected by the pressure. Therefore, it is possible to stably prevent the ozone generated in the irradiation chamber from leaking out of the irradiation chamber due to the electron beam irradiation, without being influenced by external factors.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an electron beam irradiation apparatus according to the present invention.

FIG. 2 is a schematic view showing an example of a conventional electron beam irradiation device.

[Explanation of symbols]

 2 electron beam accelerator 4 irradiation window 6 electron beam 8 irradiation object 10 irradiation room 16 air 18 cooling blower 22 air 24 exhaust blower 30 pressure sensor 32 controller

Claims (1)

[Claims] 1. An apparatus for irradiating an object to be irradiated with an electron beam emitted from an electron beam accelerator in an irradiation chamber, wherein air is blown onto an irradiation window provided in an electron beam emission section of the electron beam accelerator. In the electron beam irradiation apparatus including a cooling blower that cools the air and an exhaust blower that discharges air in the irradiation chamber to a predetermined location, a pressure sensor that detects a pressure in the irradiation chamber, and a signal from the pressure sensor. A controller that controls the number of revolutions of the exhaust blower in response to controlling the exhaust blower so that the pressure in the irradiation chamber becomes negative during electron beam irradiation. Electron beam irradiation device.