JP4578256B2 - Electron beam sterilizer and electron beam irradiation method of electron beam sterilizer - Google Patents

Description

  The present invention relates to an electron beam sterilization apparatus and an electron beam irradiation method for an electron beam sterilization apparatus, and more particularly to an electron beam sterilization apparatus having a transport path surface fixed and an electron beam irradiation method for an electron beam sterilization apparatus.

  Containers that enclose beverage liquids, such as PET bottles, are used in large quantities. The container flow in the sterilization process is extremely accelerated. Cleaning with cleaning water containing a disinfectant and disinfectant is a barrier to increasing the flow rate and makes it difficult to solve environmental problems. A known technique for speeding up and solving environmental problems is electron beam irradiation sterilization.

As one of the problems of electron beam irradiation sterilization, a problem is known that it is difficult to uniformly irradiate the inner and outer surfaces of the container with an electron beam (see Patent Document 1). The cause of the difficulty is non-uniformity and diffusivity of the electron beam absorbed dose. The PET bottle is disposed directly below the medium energy electron beam irradiation apparatus. The electron beam is diffusely attenuated when passing through the atmosphere and the PET bottle. The amount of attenuation increases depending on the transmission distance. Due to the physical properties of such electron beams, there are the following problems.
(1) Dose on the outer side of the lower neck The PET bottle has a neck region. The thickness of the neck portion is designed to be structurally thick. In particular, the dose of the electron beam reaching the outer side of the neck that is the shadow of the thickest neck feature is extremely reduced.
(2) Dose of the bottom part The bottom part is far away from the electron beam irradiation device and enters the shadow of the upper part of the bottle. The electron beam dose reaching the bottom is extremely low. In particular, the occupation reaching the bottom outer surface, which is a shadow of the bottle bottom portion, is even less than the bottom inner surface.
(3) A transport device part that transports the PET bottle, in particular, a part that directly contacts the surface of the bottle container (example: gripping finger) blocks the electron beam. The dose of the electron beam in the area that falls into the shadow of such a contact site is extremely reduced.
(4) The electron beam irradiation area is not evacuated. Electron beams collide with the atmosphere and diffuse. Diffusion extremely reduces the dose of electron beam that irradiates the bottle.

  Increasing the energy of the electron beam (energy per one electron) in opposition to the attenuation and diffusion of the electron beam that is the cause of such a problem, or increasing the amount of the electron beam (ampere) The cost of devices such as electron beam generation sources and cooling equipment is extremely increased.

JP 2004-67233 A

  An object of the present invention is to provide an electron beam sterilization apparatus that suppresses an increase in apparatus cost by uniform irradiation of an electron beam by effectively using a diffusion electron beam, and an electron beam irradiation method of the electron beam sterilization apparatus.

  In the electron beam sterilization apparatus according to the present invention, an electron beam is applied to the conveyance path surface. A container placed on the conveyance path surface is given a propulsive force to the conveyance path surface. The reflector (11 or 11 ') is provided to reflect the electron beam. Among the electron beams, the center plane region electron beam (7) of the center plane region and the crossing region (5) where the transport road surface intersects and the transport center line (1) of the transport road surface intersect at an appropriate angle (θ). . This crossing makes the electron beam irradiation uniform to the container. A gap (8 ′) is provided between the reflector and the container on the conveyance path surface in the direction perpendicular to the conveyance direction orthogonal to the conveyance direction (A), and the center plane region electron beam (7) has a gap (8 ′). Passed through. The drive device (2) that drives the container in the transport direction is disposed on the opposite side of the container perpendicular to the transport direction with respect to the reflector (11).

  The conveying device forms a shadow on the container. The electron beam reflected by the reflecting plate disposed on the side where the conveying device does not exist is irradiated without shadow on an approximately half of one side of the container. In order to reduce shading, the drive device is preferably provided as a helical pipe that contacts the container and provides a pushing force. Since one (one-axis) spiral pipe basically contacts the container at two points, the shadow shaping effect is thin. Such a spiral pipe is composed of a first spiral pipe (see FIG. 5) and a second spiral pipe. The first spiral pipe and the second spiral pipe are separated from each other in the vertical direction. Since the container receives a pressing force at at least two points that are separated in the vertical direction, a rotational moment in the falling direction is not applied to the container that slides on the conveyance path surface.

  The reflector reflects the diffused electron beam to the first part (12) that reflects the scattered electron beam scattered among the electron beams to the neck of the container and the inner surface of the body and the bottom of the container. It is particularly effective in terms of uniform electron beam irradiation to include the second part (13) to be applied and the third part (14) to reflect the diffused electron beam to the outer surface of the bottom of the container.

  More specifically, the following geometric arrangement structure is preferable. The drive device is formed by a first drive device (3) positioned forward in the transport direction and a second drive device (2) positioned rearward in the transport direction, and the reflection plate is positioned rearward in the transport direction. The first reflector (11) and a second reflector (11 ′) positioned forward in the transport direction are formed, and the second reflector (11 ′) is a second driver (2) on one side of the transport path. ), The first reflector (11) is located behind the first driver (3) on the other side of the conveyance path surface, and the gap (8 ′) between the first reflector (11) and the container. ) Is disposed on the other side described above, and the gap (8) between the second reflector (11 ′) and the container is disposed on the one side described above. Such a point-symmetric arrangement ensures the uniformity of electron beam irradiation over the entire container.

  In order to further increase the uniform effect of electron beam irradiation, it is preferable that at least one of the current of the center plane region electron beam (7) and the acceleration voltage used for generation thereof is variably controlled.

  The electron beam irradiating method of the electron beam sterilization apparatus according to the present invention irradiates the electron beam to the side of the container transported on the transport path surface, the transport direction from the central region of the electron beam to the reflector disposed on the side It is formed by a plurality of steps of reflecting the diffused electron beam diffused in the orthogonal direction and irradiating the container.

  The electron beam sterilization apparatus and the electron beam irradiation method of the electron beam sterilization apparatus according to the present invention can suppress an increase in apparatus cost by uniform irradiation of an electron beam by effective use of a diffusion electron beam.

  The best mode for carrying out the electron beam sterilization apparatus according to the present invention will be described in detail with reference to the drawings. The conveyance center line 1 of the conveyance path is defined by conveyance devices on the left and right sides as shown in FIG. The conveying device is formed of a first pipe screw 2 and a second pipe screw 3. The first pipe screw 2 and the second pipe screw 3 are each made of a pipe 4 wound in a spiral. The PET bottle P to be sterilized is transported in the same transport direction A while being sandwiched between adjacent pipe portions in the transport direction. The pipe portion and the plastic bottle P are in point contact or point area contact, and more specifically in contact at two or four points.

  The electron beam (beam) is irradiated in a fan shape. The electron beam has an effective width that is appropriate in a direction orthogonal to the fan-shaped surface. Hereinafter, the electron beam is described as being fan-shaped in the vertical plane region. A cross line 5 where such a fan-shaped surface and a reference plane S including a transport surface (eg, transport horizontal surface) of the transport path intersect has an appropriate crossing angle θ with respect to the transport center line 1. The conveyance center line 1 and the intersection line 5 intersect at the intersection point 6. The transport center line 1, the first pipe screw 2, and the second pipe screw 3 are arranged in a point-symmetric manner with respect to the intersection point 6. The distribution of the electron beam applied to the crossing line 5 is controlled point-symmetrically with respect to the intersection 6. The electron beam is scanned in a certain direction in such a distribution range.

  The first pipe screw 2 is located rearward in the transport direction and is disposed on one side of the transport center line 1. The second pipe screw 3 is positioned forward in the transport direction and is disposed on the other side of the transport center line 1. Among the three plastic bottles P illustrated in FIG. 1, the plastic bottle P located rearward in the transport direction A from the crossing point 6 has an electron beam distribution region (electron beam central region) 7 as shown in FIG. It exists on one side (example: left side when viewed in the transport direction). The electron beam distribution region 7 is generated by an electron beam scanning device 9 that is a set of an electron beam generation source and an electron beam deflector.

  A gap 8 is provided between the reflecting plate and the plastic bottle P on the conveyance path surface in a direction orthogonal to the conveyance direction A, and an electron beam projected from the electron beam scanning device 9 passes through the gap 8. Is done. In detail, the 1st electron beam reflector 11 is fixed and arrange | positioned at one side (example: right side) of the PET bottle P, without contacting the PET bottle P. As shown in FIG. The first electron beam reflector 11 is provided as a combination of a first upper swash plate 12, a first vertically extending plate 13, a first lower swash plate 14, and a first horizontal plate 15. The first vertical swash plate 13 is connected to the first upper swash plate 12 at the lower end portion of the first upper swash plate 12, and the first lower swash plate 14 is the first vertical at the lower end portion of the first vertical swash plate 13. The first horizontal plate 15 is connected to the first lower swash plate 14 at the lower end portion of the first lower swash plate 14. The upper part of the first upper swash plate 12 is more distant from the electron beam distribution region 7 than the lower part of the first upper swash plate 12. The lower part of the first lower swash plate 14 extending downward is extended to the first pipe screw 2 side with respect to the upper part of the first lower swash plate 14. The first horizontal plate 15 extends toward the first pipe screw 2 in the horizontal direction. It is effective that the first vertically extending plate 13 is bent into a cylindrical shape, an elliptical shape, or a parabolic shape so as to surround the plastic bottle P.

  The electron beam distribution region 7 of the electron beam projected from the electron beam scanning device 9 collides with air (atmosphere) and diffuses and diffuses, and the scattering orthogonal direction orthogonal to the transport direction A or the scattering orthogonal to the cross line 5 is scattered. Spread in the orthogonal direction. Such diffusion indirectly contributes to the uniformity of irradiation density. The electron beam that diffuses and travels toward the first upper swash plate 12 is reflected by the first upper swash plate 12 and travels toward the neck portion of the plastic bottle P. The neck portion is thickly formed, or the shadow portion is formed by being threaded, but the reflection line 16 reflected by the first upper swash plate 12 is irradiated from the diagonally lower side to the almost right half of the neck portion. The The reflection line 17 reflected by the first vertically extending plate 13 is irradiated on the side wall of the plastic bottle P and enters the inside, and a part of the electron beam entering the inside is a side wall on the opposite side or the bottom inner surface of the plastic bottle P. Is irradiated. The electron beam traveling vertically downward on the electron beam distribution region 7 passes through the gap 8 and is reflected by the first lower swash plate 14, and the reflection line 18 is irradiated to the bottom surface of the plastic bottle P, and enters the inside. It enters and irradiates the inner outer surface of the bottom. The electron beam that passes through the plastic bottle P and exits from the plastic bottle P is reflected by the first horizontal plate 15 and further irradiated to the plastic bottle P.

  Of the three plastic bottles P illustrated in FIG. 1, the plastic bottle P positioned in the transport direction A from the crossing point 6 is on the other side of the electron beam distribution region 7 (illustrated), as shown in FIG. 3. : Present on the right side when viewed in the transport direction.

  As shown in FIG. 3, the second electron beam reflector 11 ′ is fixed and arranged on one side (example: left side) of the PET bottle P without contacting the PET bottle P. The second electron beam reflecting plate 11 ′ is provided as a combination of a second upper swash plate 12 ′, a second vertically extending plate 13 ′, a second lower swash plate 14 ′, and a second horizontal plate 15 ′. ing. The second vertically extending plate 13 'is connected to the second upper swash plate 12' at the lower end portion of the second upper swash plate 12 ', and the second lower swash plate 14' is the lower end of the second vertically extending plate 13 '. The second horizontal plate 15 ′ is connected to the second lower swash plate 14 ′ at the lower end portion of the second lower swash plate 14 ′. The upper part of the second upper swash plate 12 ′ is farther away from the electron beam distribution region 7 than the lower part of the second upper swash plate 12 ′. The lower part of the second lower swash plate 14 ′ extending toward the lower side extends toward the second pipe screw 3 with respect to the upper part of the second lower swash plate 14 ′. The second horizontal plate 15 ′ extends to the second pipe screw 3 side in the horizontal direction. The electron beam irradiation function relating to the second electron beam reflector 11 ′ is point-symmetrically equivalent to that of the first electron beam reflector 11 described above.

  FIG. 4 shows an arrangement form of overlapping sections in which the front part of the first pipe screw 2 and the rear part of the second pipe screw 3 overlap in a direction orthogonal to the transport direction A. In the region near the intersection point 6, the electron beam is applied to the plastic bottle P at the same time in point symmetry.

  As shown in FIGS. 2 and 3, the first electron beam reflector 11 and the second electron beam reflector 11 ′ have crossing lines 5, respectively, in comparison with the first pipe screw 2 and the second pipe screw 3. And the first pipe screw 2 and the second pipe screw 3 are respectively crossed lines in comparison with the first electron beam reflector 11 and the second electron beam reflector 11 ′. It is arranged on the farther side than 5. In such an arrangement, the reflection effects of the first electron beam reflecting plate 11 and the second electron beam reflecting plate 11 'existing on the side where the first pipe screw 2 and the second pipe screw 3 do not exist are large. However, if there is a space, it is not prohibited to arrange the reflectors on both sides. In this sense, the reflectors disposed on both sides are disposed asymmetrically with respect to the transport center line 1.

  The reflector is made of an element material having a high reflectivity and a large atomic number. In order to improve the reflectance, the reflecting surface of the reflecting plate is preferably finished by mirror polishing. Forming a film of an element that is toxic but inexpensive and has a high reflectance on an element that is expensive but not toxic and has a high reflectance further harmonizes the improvement in reflectance with cost and safety. FIG. 5 illustrates such film formation. The second electron beam reflecting plate 11 ′ is formed of a bent support structure portion 19, the above-described second upper swash plate 12 ′, the second vertically extending plate 13 ′, and the other reflecting plates described above. . FIG. 5 shows the second upper swash plate 12 ′ and the second vertically extending plate 13 ′ supported by the support structure part 19. The second upper swash plate 12 ′ and the second vertically extending plate 13 ′ are respectively coated with a toxic expression preventing coating film 21 on the entire surface. The second upper swash plate 12 'and the second vertically extending plate 13' are made of atoms that are toxic but inexpensive and have an optimally large atomic number (eg, lead). The toxic expression-preventing coating film 21 is made of an atom (eg, gold) that is non-toxic and has a high reflectance, and is formed thin.

Other forms of implementation:
In order to make the irradiation amount of the electron beam in the PET bottle P more uniform, the electron beam current and / or the acceleration voltage used to generate the electron beam are controlled according to the scanning position of the electron beam. Is preferred. Specifically, at a scanning position where the irradiation efficiency to a part where the dose of the electron beam tends to decrease (eg, the outer surface below the neck, the outer surface of the bottom) is high, the current of the electron beam and / or the electron beam The acceleration voltage used for generation is preferably increased.

In order to realize such control, for example, as shown in FIG. 6A, the electron gun pulse current corresponding to the output of the electron beam source 22 is used for the deflection scanning of the main scanning deflector 23. It is preferably controlled so as to have a waveform such that the current at the scan start timing T ₁ and the scan end timing T ₃ is set larger than the current at the scan intermediate period T ₂ ; Is synchronized with the deflection scanning of the main scanning deflector 23 by synchronizing the current supplied to the scanning magnet of the main scanning deflector 23 with the electron gun pulse current.

In the scanning start time T _1, as shown in FIG. 2, the scanning position of the electron beam is in the neck under the outer surface and the bottom outer surface of the plastic bottle P in a position such that the electron beam is irradiated. However, the electron beam irradiation efficiency to these parts is low. In the scanning start time T _1, as shown in FIG. 6 (a), an electron gun pulse current is increased. Increasing the electron gun pulse current at the scanning start timing T ₁ makes it possible to irradiate a sufficient amount of electron beam on the lower neck outer surface and the bottom outer surface of the PET bottle P.

The same applies to the scanning end timing T _3. In the scanning end timing T _3, as shown in FIG. 3, in the scanning position such that the electron beam is an electron beam in the neck under the outer surface and the bottom outer surface of the plastic bottle P is irradiated. In the scanning end timing T _3, as shown in FIG. 6 (a), an electron gun pulse current is increased. Increasing the electron gun pulse current to the scanning end timing T ₃ is fired under the outer surface and the bottom outer surface of the plastic bottle P, and allows the electron beam irradiation of sufficient dose.

On the other hand, as shown in FIG. 4, in the scanning intermediate period T < _b > ₂ , the scanning position of the electron beam is at a position where the electron beam is irradiated on the bottom inner surface of the plastic bottle P. The irradiation efficiency to the inner surface of the bottom of the PET bottle P is high. For such scanning positions, the electron gun pulse current is relatively reduced, thereby improving the uniformity of electron beam irradiation.

Instead of controlling the electron gun pulse current or in addition to controlling the electron gun pulse current, the acceleration voltage can also be controlled. It is preferable that the acceleration voltage at the scan start timing T ₁ and the scan start timing T ₃ is relatively increased as compared with the acceleration voltage at the scan intermediate period T ₂ in order to achieve uniform sterilization capability.

FIG. 1 is a plan view showing a preferred embodiment of an electron beam sterilizer according to the present invention. FIG. 2 is a side view of the left end position of FIG. FIG. 3 is a side view seen from a side cross-section at a front position from the center position in FIG. 1. FIG. 4 is a side view seen from the center position of FIG. FIG. 5 is a side sectional view of a part of FIG. FIG. 6A is a timing chart showing the waveform of the electron gun pulse current, and FIG. 6B is a timing chart showing the waveform of the scanning magnet current.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conveyance center line 2 ... Driver (2nd drive device)
3 ... 1st drive device 5 ... Crossing area | region 7 ... Center plane area | region electron beam 8 '... Crevice 11, 11' ... Reflector plate 12 ... 1st site | part 13 ... 2nd site | part 14 ... 3rd site | part θ ... Appropriate angle θ '" ... Scanning angle A ... Conveying direction

Claims (6)

A conveyance road surface on which the container is placed ;
Before SL vessel giving promote force, a drive device for transporting the transport direction of the containers on the transport road,
An electron beam irradiator that irradiates a fan-shaped electron beam with respect to the conveyance path surface;
A reflector for reflecting the electron beam;
The fan-shaped surface of the electron beam and the transport center line of the transport road surface intersect at an appropriate angle θ,
Given gap in the transport direction orthogonal direction orthogonal to the transport direction between the container on the conveyor road and the reflective plate,
Some of the electron beam is passed through the gap,
The drive device is disposed on the opposite side of the reflector perpendicular to the transport direction with respect to the container ,
The reflector is
A first portion that reflects a portion of the electron beam to the neck of the container;
A second part that reflects a portion of the electron beam to the body of the container;
A third part that reflects a part of the electron beam that has passed through the gap to the bottom of the container.
And an electron beam sterilizer. The electron beam sterilizer according to claim 1, wherein the driving device is provided as a spiral pipe that contacts the container and applies a pressing force. The spiral pipe is
A first spiral pipe;
With a second spiral pipe,
The electron beam sterilizer according to claim 2, wherein the first spiral pipe and the second spiral pipe are separated from each other in the vertical direction. The drive device is
A first drive device located forward in the transport direction;
A second drive device located rearward in the transport direction,
The reflector is
A first reflector located rearward in the transport direction;
A second reflector located forward in the transport direction,
The second reflector is positioned forward of the second driver on one side of the transport path;
The first reflector is located behind the first driver on the other side of the conveyance path surface,
The gap between the first reflector and the container is disposed on the other side;
The electron beam sterilizer according to claim 1, wherein the gap between the second reflector and the container is disposed on the one side. And current of the electron beam, at least one of an electron beam sterilizer according to claim 1 which is variably controlled between the acceleration voltage used to generate the electron beam. Transport the container in the transport direction on the transport road surface,
Irradiating a fan-shaped electron beam to the transporting road surface;
Irradiating the container with a part of the electron beam reflected by a reflector,
The fan-shaped surface of the electron beam and the transport center line of the transport road surface intersect at an appropriate angle θ ,
A gap is provided between the reflecting plate and the container on the conveyance path surface in a direction perpendicular to the conveyance direction perpendicular to the conveyance direction,
A part of the electron beam is passed through the gap,
The reflector is
A first portion that reflects a portion of the electron beam to the neck of the container;
A second part that reflects a portion of the electron beam to the body of the container;
An electron beam irradiating method for an electron beam sterilizer, comprising: a third portion that reflects a part of the electron beam that has passed through the gap with respect to a bottom of the container.

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