JP2000254486A - Device and method for electron beam irradiation and material to be treated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sterilize granular substances by containing a conveying mechanism for floating granular substances to convey them and an electron beam generating mechanism fixed outside a easing surrounding the conveying mechanism and for generating electron beams to accelerate them, holding the granular substances in a floated state by gas, and irradiating the electron beams while mixing and agitating. SOLUTION: Granular substances H are fed from a feeding hopper 11 and are introduced into a conveying path 10, and are advanced while they are energized forward by conveying gas jetted from a pre-gas chamber 25 to float them. After electron beams 'e' are irradiated to the granular substances H below an irradiation window 4 to sterilize them, they are brought out to the outside from a discharge hopper 12. At this time, since when a filament 3 is energized and heated, the filament 3 is negatively biased and an electrode 2 is positively biased to discharge thermions from the filament 3, they are made electron beams 'e' accelerated to irradiate them into the easing 8 through a window foil 5 of the irradiation window 4. The conveying gas is pressurized by a blower 30 to feed it to the conveying mechanism 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for irradiating an amorphous or distorted solid or a granular material with an electron beam. Its purpose is resin curing, coating film curing, sterilization and the like. For example, it is desirable to sterilize foods such as tea leaves, rice, wheat, soybeans, and red beans. Further, there is a case where it is desired to apply a coating to a plastic pellet or the like and to cure it.

The purpose of irradiating such amorphous solids and powders with an electron beam is novel. This is because these amorphous solids have been treated by some method other than electron beam irradiation. Domestic tea leaves and grains are often not sterilized. This is because it is a domestic crop, and the time from harvest to consumption is short and there is little risk of deterioration during the storage period. However, imported grains and legumes are often sterilized. This is because they may be contaminated by bacteria and the like. Even domestically produced agricultural products that have a long shelf life may be sterilized. The present invention meets that objective.

[0003]

2. Description of the Prior Art Sterilization of foods has hitherto been performed by chemical means. In the case of cereals, gasses such as ethylene oxide gas (EOG) and methyl bromide are used. The fumigation method sterilizes food by sterilizing toxic gas. A gas having a bactericidal action comes into contact with the periphery of the granular material and penetrates from the surface to the inside to kill bacteria on and near the surface. Since a fluid gas is used, it can be in contact with the entire surface of the granular material and can process the entire surface. That is an advantage. However, the treatment itself is dangerous because it is a toxic gas. Also, these gases must not remain in food. After the treatment, these gases do not remain and must be below the allowable residual concentration. There is an increasing sense of resistance to using gas sterilization for food even below the permissible concentration. In addition, some of them are altered when sterilized by these gases. Smell, taste, etc. may deteriorate.

[0004] In the case of tea leaves, sterilization is often not performed, but sterilization may be required in some cases. In that case, it is sterilized by heated steam. The heated steam contacts the entire surface of the tea leaves and heats them to kill bacteria. No odor remains because no chemical gas is used. However, the components may fluctuate or the color may change due to heating. Heating can affect the quality of tea leaves and is not the best method.

An object of the present invention is to provide a method and an apparatus for sterilizing irregular-shaped foods such as tea leaves and grains with an electron beam. INDUSTRIAL APPLICABILITY The present invention can also be used for curing treatment of pellet-shaped plastic and coating film curing treatment. Therefore, curing of plastic and coating film by irradiation with an electron beam are also one of the objects of the present invention.

The electron beam irradiator takes out an electron beam accelerated in a vacuum into the atmosphere through a window foil, irradiates the solid object to be processed, and performs processes such as polymer crosslinking, coating film hardening, and sterilization. Is what you do. The electron beam irradiator heats a filament that is negatively biased in vacuum to generate thermoelectrons, a thermoelectron generator that accelerates by applying voltage to the electrons,
It is a heavy device consisting of an irradiation window part, a part for transporting an object to be processed in the atmosphere, and the like. Although the present invention relates to the invention of a transport system, the entire electron beam irradiation apparatus will be briefly described in order to clarify the overall relationship.

The thermoelectron generating portion generates thermoelectrons by energizing the filament to which a negative voltage is applied. The accelerating portion accelerates the electron beam by applying a high voltage, but the accelerating voltage differs depending on the purpose. In some cases, the acceleration may be accelerated to MeV or more, but in some cases, it may be accelerated to MeV or less to several hundred keV. The beam current also depends on the purpose. The electron beam irradiation apparatus includes a scanning type that scans a beam and a non-scanning type that does not scan a beam. The scanning type device distributes an electron beam over a wide range by deflecting a thin electron beam right and left by an alternating magnetic field. The scanning type requires a sufficient distance for acceleration and scanning, and thus is a large device. This is a device suitable for high acceleration energy. The non-scanning type (area type) generates an electron beam having a large cross-sectional area from a meandering filament and only accelerates the beam without scanning. Since the non-scanning type does not require a distance for scanning, it is a small device. Many have low electron beam energies.

The part that generates and accelerates an electron beam is a vacuum. The object is at atmospheric pressure. The irradiation window is the part that separates the vacuum from the atmosphere. A rectangular window frame is covered with a foil of Ti, Al, or the like. Window foil is indispensable for separating vacuum and atmosphere. A force equal to atmospheric pressure × area is applied to the window foil. The window foil is held down by several bars to prevent damage. There is an energy loss when the electron beam passes through the window foil and the window foil is heated by the heat. To take the heat, the window foil is cooled by means such as air cooling or water cooling. The upper part of the window foil is the electron beam generation and acceleration part, and the lower part is the transport part. The transport section is composed of an endless orbiting conveyor and a heavy casing surrounding the conveyor and having an entrance and an exit. The solid workpiece is carried in from the entrance. The object to be processed is placed on the conveyor and reaches right below the irradiation window, where it is exposed to an electron beam. The workpiece is conveyed to the conveyor and discharged from the outlet. The entire transport mechanism is surrounded by a heavy metal plate case because X-rays are generated when an electron beam hits a workpiece or a conveyor. Harmful X-rays are emitted and must be enclosed in a box.

The atmosphere of the transport mechanism may be air, but may be nitrogen or argon. In the case of air, oxygen changes to ozone by X-rays, which may affect the environment and the object to be treated. When the atmosphere is air, an air supply / exhaust system for exhausting ozone is provided so that ozone does not escape to the outside. If the ozone itself reacts with the material to be treated without going outside, air should not be used.
In that case, nitrogen or argon gas is used as the atmosphere.

[0010] Processing of a fixed object to be processed by the electron beam irradiation apparatus as described above has been frequently performed so far. The fixed object is carried on the conveyor, and only the surface facing the window foil is irradiated with the electron beam.

However, with such an apparatus, it is difficult to treat irregularly shaped powders or granular materials (granules). In the case of grains and the like, as described above, the chemical sterilization method using methyl bromide or ethylene oxide was effective and the electron beam treatment was not performed.

[0012] The reason is that it is difficult to apply an electron beam equally to the whole of the granular material. For example, if the material is thick, such as a bean, it will not be turned over on the conveyor, so it is necessary to apply an electron beam of high energy enough to penetrate the entire thickness. In the case of beans, wheat or rice, only the surface needs to be sterilized, but only one side faces up,
Since the other surface is shadowed by the electron beam, a high-energy electron beam penetrating the entire surface is required. A single bean is good, but a few meters if there are many layers
An electron beam penetrating a thickness of m to several tens mm is required.

[0013] In the case of powder, it can be conveyed by a conveyor and irradiated with an electron beam from above.
Since it varies from m to several tens of mm, it is necessary to give the electron beam energy that can penetrate even the thickest part. Although depending on the physical properties of the object to be processed, an electron beam penetrating through a thickness of several mm to several tens mm requires high energy of about MeV. Such a device for applying a high energy electron beam has to be a large and expensive device.

The problem is not limited to this. In the case of foods, when an electron beam penetrates the inside, the flavor and quality may be reduced because chemical bonds are broken. In the case of sterilizing cereals and the like, the electron beam only needs to be irradiated near the surface. On the other hand, I want to prevent the electron beam from entering inside. For that purpose, the object to be processed may be rotated so that all surfaces face the electron beam irradiation direction. However, there is no transport mechanism for rotating the workpiece. For that reason, it can be said that the processing of the amorphous workpiece with the electron beam irradiation apparatus has not been implemented yet.

Although not implemented, some suggestions have been made to the extent of the idea. JP-A-1-192362 "Powder radiation processing apparatus"
Inventors Seiichi Wada, Masakazu Ishihara, Noriyuki Kamiyama, applicant Mitsubishi Kakoki Co., Ltd. `` a powder floating chamber that stands up in a room surrounded by a shielding wall and blows gas from the bottom upward to float powder, A powder radiation processing apparatus provided with a radiation irradiation device facing the powder floating chamber. " This is a method for irradiating powders such as flour and spices (γ-ray, X-ray, electron beam)
A new device for sterilization is proposed. When the powder is transported by the conveyor, irradiation unevenness occurs on the surface layer and the inner layer, which is undesirable. Therefore, the powder is floated and transported by the gas, and the floating powder is irradiated with radiation such as γ-rays, X-rays, and electron beams. That is. Vertically `` stand '' a duct with a vertical part inside the room, pump air and powder from the bottom and fly up from the bottom, and radiate radiation from the side to the powder sealed in the duct. Hit it. The powder that has been irradiated is discharged upward through a filter. Radiation is applied to the powder that rises from the bottom up, so that the radiation hits the entire surface of the powder and irradiation unevenness (irradiation dose non-uniformity) does not occur.

Japanese Patent Application Laid-Open No. 8-52201, "Electron Beam Sterilizer for Powder" Inventors Seiichi Wada, Masakazu Ishihara, Hideo Kurihara, Patent Applicant Mitsubishi Kakoki Co., Ltd. has a slightly inclined processing chamber with a thick concrete wall. A perforated plate is provided in parallel with the middle of the tube, air is blown underneath, the powder is dropped on the perforated plate, and the powder is lifted diagonally downward by air ejected from many micro holes. (4 degrees to 10 degrees)
The powder is carried (air slide conveyor), and electron beams can be exposed from the side along the way. The powder and the air are commonly extracted from the terminal outlet, and the powder and the air are separated by the cyclone. Since the powder is sowed by air and pneumatically transported diagonally downward, the powder rotates,
An electron beam hits all surfaces.

[0017]

In the case of sterilizing an object to be treated which has to be treated in its entirety in an irregular shape such as a granular material, it has hitherto been brought into contact with ethylene oxide or methyl bromide gas. However, these gases are toxic because of their bactericidal action. Residual gas in foods is harmful to the human body. Flavor and quality may be degraded by contact with gas. Toxic gases are becoming increasingly difficult to use for sterilization. Sterilization using heated steam can also impair the aroma and flavor of the tea leaves.

If sterilization treatment can be performed by electron beam irradiation which is completely different from these methods, such a problem should be eliminated. However, an apparatus for disinfecting powder and granules by an electron beam irradiation apparatus has not been actually used yet. There are various reasons. First, you'll need a large device. When the object is statically transported by the conveyor, it is necessary to penetrate the electron beam to the bottom. Therefore, high energy is required. Large devices are required to generate high energy electron beams. The price is high, the installation area is large, and the cost is high. In addition, there is a sorrow that quality is lost if an electron beam penetrates into the inside. It is best if the object to be treated, which is a powdery substance, is rotated and stirred so that an electron beam is applied to the entire surface. But this is difficult. It is difficult to carry out rotary stirring while transporting the powder and granules on a conveyor.

In the case of irradiating radiation while transporting powder by air, the flow of air is only an upward flow. The powder is pneumatically transported inside the tube, and γ-rays, X-rays, and electron beams are irradiated from outside the tube. The first problem with this device is that the radiation loss becomes too great as the radiation passes through the tube wall. In the case of a duct for pneumatic transportation, a thickness of about 2 mm to 5 mm is required even for plastic. A metal tube would require a thickness of about 1 mm. In such a case, high energy gamma rays without mass or charge may be able to penetrate the tube wall. Since X-rays also have no charge mass, they can be transmitted through the tube wall. However, an electron beam is a beam of electrons and has both mass and charge. It is difficult for an electron beam to pass through a tube wall of 2 mm to 5 mm. I can hardly get through. This method can be used for gamma rays, but not for electron beams. Although the electron beam can barely pass through a window foil of several μm to several tens of μm, it is almost impossible to pass through a wall as large as several mm.

The powder is conveyed by an air slide conveyor which blows up air from the perforated plate at the bottom and soars the powder, and irradiates an electron beam from the side. This is because air is blown under the perforated plate provided on the conveyor tube to blow up the powder, so that controllability is poor. Even powders vary in bulk specific gravity, particle size, composition, viscosity, and the like. Only adjusts the amount of air sent below the perforated plate, so it is difficult to handle powders of various properties and specific gravities. It is not only that the airflow distribution cannot be freely adjusted.

Is a structure which must be surrounded by a thick concrete wall. According to FIG. 1, the concrete wall has a thickness of at least twice the height of the air slide conveyor. An air slide conveyor, a powder inlet, a powder outlet, an air supply port, and an electron beam generating accelerated irradiation device are all housed in a wall-partitioned interior. This equipment has extremely heavy armor that completely surrounds a large processing room with concrete. Heavy walls prevent radiation leakage. Although safe, construction costs are extremely high due to the need for thick concrete walls. A large installation area will be required. This results in a high-cost processing device. At such a high cost, conventional chemical treatment methods using methyl bromide or ethylene oxide gas cannot be replaced.

It is a first object of the present invention to provide an apparatus capable of sterilizing powders and granules by an electron beam.
It is a second object of the present invention to provide an apparatus capable of treating the entire surface of irregular shapes, powders, and granules with a low energy electron beam. It is a third object of the present invention to provide an electron beam irradiation apparatus provided with a transport mechanism capable of transporting the powder while rotating the powder. It is a fourth object of the present invention to provide an electron beam irradiation apparatus which is excellent in controllability and can cope with powders having various forms and specific gravities.

[0023]

The electron beam irradiation apparatus according to the present invention has a perforated plate provided at the entrance of the granular material, the transfer path, the discharge port of the object to be processed, the start end of the transfer path, and the upper and lower parts. A transport mechanism for floating and transporting the granular material by blowing gas in three directions by a mechanism capable of independently controlling the flow rate from the holes of the perforated plates at the start, upper, and lower sides, and a housing surrounding the transport mechanism. And an electron beam generating mechanism fixed to the outside of the housing for generating and accelerating an electron beam, wherein the powder is suspended in a gas in a transport mechanism, and the electron beam is irradiated while mixing and stirring.

The perforated plate is at least three sides of the transport path (starting end,
It is important to have a transport mechanism that blows gas from three perforated plates by a mechanism that can be controlled independently at the top and bottom. The gas blown from the perforated plate at the beginning mainly determines the transport speed. When the processing amount per unit time is large, the starting end inflow amount is increased. When the processing amount is small, the starting end inflow amount is reduced. The gas blown from the lower portion has an action of lifting the powdery material as the object to be processed. For an object having a large bulk specific gravity, the lower inflow gas amount is increased. For an object having a small bulk specific gravity, the lower inflow gas amount is reduced. The gas blown from the upper part prevents scattering of the granular material.
By adjusting the distribution and flow rate of the upper inflow gas and the lower inflow gas, the powder can be carried in a state of floating in the space of the conveyance path without contacting the wall surface.

In order to independently control the flow rate of the gas blown from three sides, three blowers themselves can be provided independently. An independent flow control valve may be attached to the branching three-way piping system even if the blower is common. Further, when the transport path is long, the upper and lower perforated plates become longer, and the pressure may become uneven depending on the location. In that case, a plurality of blowers for the lower gas and the upper gas may be provided. It is said that only the lower gas supply system is used for the upstream part, the middle part, and the downstream part. The same applies to the upper gas supply system. The traveling direction of the transport path is the z direction,
The direction of the electron beam is defined as the −y direction. The gas flow blown from the starting end perforated plate flows in the z direction. The gas flow blown from above flows in the -y direction. The gas blown from below flows in the + y direction.

Since gas is blown in from three directions, it is thin in the vertical direction (y direction) and spread laterally (x direction) in a forward (z
Direction). An irradiation window is provided close to the middle of the transport path. An electron beam generation and acceleration mechanism for generating and accelerating an electron beam is provided above the irradiation window. The electron beam is applied to a part of the transport path through the irradiation window. The powder passing directly below the irradiation window receives an electron beam.

Since the particles are conveyed while floating in the air, the particles of the particles are constantly rotating microscopically. Even when the particle is exposed to an electron beam just below the irradiation window, the particle rotates, so that the entire surface of the particle is irradiated with the electron beam. In the case of sterilization, it is very convenient because the electron beam only needs to be irradiated near the surface. In the case of foods, the purpose is sterilization, so that the present invention, in which the particles can be rotated and the entire surface is irradiated with an electron beam, is effective.

In addition to food, the present invention is also effective for granular materials such as plastic pellets. It can be used for hardening treatment of flexible pellets by electron beam. Further, when a coating film is formed on the pellet surface, it can be used for coating film curing treatment by electron beam irradiation.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION An electron beam irradiation apparatus may be a non-scanning type or a scanning type. The electron beam acceleration energy depends on the purpose, but may be low as long as the purpose is to sterilize the surface of the granular material. In that case, a non-scanning type device is sufficient. In the case of a non-scanning type (area type), an irradiation window is provided directly on the housing, and an electron beam generation and acceleration unit is mounted thereon. The electron beam is accelerated between the filament and the irradiation window.

Even for the purpose of sterilization, the beam current and the accelerating voltage differ depending on the type of the object and the throughput. For example, the acceleration voltage is about 50 keV to 500 keV. The beam current is about several mA to 500 mA. The processing amount is several t to 10 t per hour.

An object to be processed, which is a granular material, is charged from a charging hopper at the beginning of the transport path. The object to be processed is
Start end (z direction), downward (+ y direction), upward (-y direction)
It is transported while being mixed and stirred by the introduced gas. An electron beam is irradiated under the irradiation window on the way.

The gas used for the floating conveyance is, for example, air. At the discharge port, the air and the material to be processed are mixed and discharged, so that they are separated into solid and gas by a cyclone or the like. In the case of air, it may or may not be circulated.
When using air as a floating carrier gas, it is necessary to remove dust with a filter and adjust the humidity appropriately. In the case of air,
Ozone is emitted due to X-rays generated by the electron beam. In some cases, the ozone odor impairs the quality and flavor of the object. In that case, it is better not to use air.

When the use of air has an undesirable effect on the object to be treated, use an inert gas such as nitrogen or argon. If it is nitrogen or argon, no ozone is generated. Ozone odor does not adhere to foods and foodstuffs. When a gas such as nitrogen or argon is used, the gas is preferably circulated.

The main roles of the gas introduced from three directions are as follows. 1. Front-end inflow gas (+ z direction) ... for transport 2. Downward inflow gas (+ y direction): floating mixing and stirring Upper inflow gas (-y direction) ... scattering prevention. Each is provided with an independent blower (blower) or an independent flow control valve. Here, the case where the control is performed by the flow control valve will be described.

By adjusting three independent flow control valves, it is possible to change the transport speed, lift (floating force), scattering prevention force, and the like. It can be applied to a wide variety of transfer states of the object to be processed. For example, the transport speed (residence time in the irradiation area) and the state of mixing and stirring can be easily controlled.

When it is necessary to further improve the controllability, it is preferable to increase the number of paths to each gas inlet. That is, a plurality of lower inflow gas introduction sections are provided or a plurality of upper inflow gas introduction sections are provided.

In order to increase the transport amount, the transport path may be provided with the casing slightly inclined downward toward the outlet.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electron beam irradiation apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a longitudinal sectional view of the entire structure. FIG. 2 is a cross-sectional view of the transport path, and FIG. 3 is a cross-sectional view of the transport path at the irradiation window. This shows a non-scanning type (area type), but can also be applied to a scanning type electron beam irradiation apparatus. The inside of the cylindrical vacuum chamber 1 can be evacuated. A cylindrical shield electrode 2 is provided in the vacuum chamber 1, and a meandering filament 3 (cathode) is provided in the center of the shield electrode 2. The filament 3 is energized and heated. The filament 3 is negatively biased and the electrode 2 is positively biased, and thermions are emitted from the filament 3. The end of the vacuum chamber 1 is open, and serves as an irradiation window 4. The irradiation window 4 is covered with a thin window foil 5. The window foil 5 is a foil of titanium or aluminum. An electron beam can be transmitted through a thin material of about several tens of μm. The four sides of the window foil 5 are held down by a window foil flange 6 and a window foil holder 7.

The electron beam is applied to the filament 3 and the shield electrode 2
Between being accelerated to the appropriate energy. The accelerated electrons e enter the housing 8 through the window foil 5 of the irradiation window 4. A housing 8 made of a metal plate surrounds the entire transport mechanism 9. The housing 8 has an opening in the center, where the irradiation window 4 of the electron beam acceleration mechanism is located. It is common in an electron beam irradiation apparatus to surround a mechanism for transporting an object to be processed by a thick metal casing. Since X-rays are generated by electron beam irradiation, the X-rays are surrounded by the housing 8 so as not to leak to the outside.

In the case of processing a normal fixed solid, the transport mechanism is an endless orbiting conveyor, but the present invention does not use an endless orbiting conveyor. The present invention floats and transports a granular material by gas. The first feature of the present invention resides in the transport mechanism 9. The transport path 10 is a rectangular space that is long horizontally. Conveyance path 10
Is connected to the lower end of the charging hopper 11 at the front end. A discharge hopper 12 continues to the rear end (end) of the transport path 10. The object to be processed is supplied from the input hopper 11, and
Pass through 0 from the front (upstream) to the back (downstream),
It is taken out from the discharge hopper 12 to the outside.

The transport path 10 is a space partitioned by metal. The transport path is a rectangular parallelepiped transport path including a transport path bottom plate 13, a transport path upper plate 14, a transport path front plate 15, a transport path rear plate 16, and transport path side plates 17 and 18. Moreover, a part thereof is a double wall with the perforated plate. Immediately above the transport path bottom plate 13, a lower perforated plate 20 parallel to this is fixed. The lower perforated plate 20 can be composed of a punched metal, a mesh, or the like. It is plate-shaped but has many small holes. An upper perforated plate 21 is attached immediately below the transport path upper plate 14 in parallel thereto. This is also perforated metal or mesh. There is also a front perforated plate 22 immediately before the front plate 15 of the transport path. Transport path bottom plate 1
A lower gas chamber 23 through which a gas can flow between the lower perforated plate 20 and the lower perforated plate 20.
It has become. A gas for transportation is sent from outside to this, and is blown out from a large number of holes of the perforated plate 20 toward the inside of the transportation path. This creates an upward flow. The upward flow has the effect of suspending the granular material that is the object to be processed. Upper plate of transport path 1
The upper gas chamber 24 through which gas can flow between the upper perforated plate 4 and
It has become. The gas introduced here is blown into the transport path as a downward flow. The downward flow has an effect of preventing scattering of the granular material.

A front perforated plate 22 is provided immediately before the transport path front plate 15. A front gas chamber 25 is provided between the front plate 15 of the transfer path and the front perforated plate 22, and a transfer gas is introduced from outside. The gas that has passed through the hole of the front perforated plate 22 becomes a forward flow (z direction), and has an action of transporting the granular material. In this way, a mechanism for ejecting gas to the three surfaces is provided.

The transport side plates 17 and 18 have no gas chamber as shown in FIGS. Therefore, no positive gas flow is formed in the direction (x direction, -x direction) orthogonal to the transport path. Therefore, the powder has a distribution that is thin in the vertical direction (y direction) and spread in the horizontal direction (x direction). The granular material H is carried as a thin layer and reaches directly below the irradiation window 4. Here, it is subjected to a treatment such as sterilization by being exposed to the electron beam e. The direction of the electron beam is one fixed direction (−y direction). Since the fine particles and particles of the powder are freely floating in the space, they rotate randomly. Therefore, all the surfaces of the particles may face the electron beam irradiation direction. At that time, the surface is exposed to an electron beam. Therefore, the electron beam impinges almost equally on the entire surface of the particle. Because the gas flow from above and the gas flow from below become balanced, the powder flow becomes flat and spreads, so that all the particles are almost equally and efficiently exposed to the electron beam. That is, the electron dose on the surface of each particle is averaged, and the electron beam irradiation amount is also averaged for all particles. In two ways, the irradiation dose becomes nearly uniform. Ideal electron beam processing can be realized. In order to hold the powder in a band shape, it is important to balance the three gas flows of the downward flow, the upward flow, and the propulsion flow. For this purpose, the three types of gas flows can be independently controlled.

The blower 30 is provided with a carrier gas (air, nitrogen,
(Argon) to supply gas to the transport mechanism 9. Flow rate control valves 31, 32, and 33 are provided to independently control the flow rate of the gas from the blower 30.
The blower 30 and the first flow control valve 31 are connected by a pipe 34. The blower 30 and the second flow control valve 32 are connected by a pipe 36. The blower 30 and the third flow control valve 33 are connected by a pipe 38.

A pipe 35 connected to the first flow control valve 31 is connected to the lower gas chamber 23. A pipe 37 connected to the second flow control valve 32 communicates with the upper gas chamber 24. A pipe 39 connected to the third flow control valve 33 continues to the front gas chamber 25. Part of the gas activated by the blower 30 enters the lower gas chamber 23 via the pipe 34, the first flow control valve 31, and the pipe 35, and enters the transport path 10 as an upward flow. The upward flow has the effect of lifting (lifting) the workpiece. Another part of the gas activated by the blower 30 passes through the pipe 36, the second flow control valve 32, and the pipe 37 to the upper gas chamber 2
4 and enter the transport path 10 as a downward flow. The downward flow has the effect of preventing the powder from scattering.

The remainder of the gas activated by the blower 30 enters the front gas chamber 25 via the pipe 38, the third flow control valve 33, and the pipe 39, and enters the transport path 10 as a forward flow. The forward flow controls the speed of transport of the granules.

In this figure, an upflow gas pipe 35, a downflow gas pipe 37, and a propulsion flow gas pipe 39 are provided in the gas chamber 2 respectively.
The connection to 3, 24, and 25 is written as one place, but is not limited to this. When the pressure inside the gas chamber becomes uneven, a plurality of inlet pipes entering the gas chambers 23 and 24 may be provided. Since the upper gas chamber 24 and the lower gas chamber 23 are long in the flow direction, it is effective to provide two or three inlets. If the pressure in the gas chambers 23 and 24 becomes uniform, the flow rate blown out from the holes becomes almost constant along the flow direction,
The powder can flow while maintaining the balance between the upper and lower gas flows.

The irradiation window 4 has Ti and Al foils, and further below the upper perforated plate 21. Only the electron beam passing through this hole is effective. An electron beam hitting the plate surface causes heat loss. Not only the window foil but also the perforated plate 21 is heated. Perforated plate 2
1, 20, a mechanism for cooling the transport path bottom plate 13 is provided. Here, the cooling mechanism is not shown.

The operation of the above configuration will be described. The granular material H is introduced from the introduction hopper 11. The granular material H that has gradually descended due to gravity enters the transport path 10. This is urged forward (z direction) by the gas from the front gas chamber 25. Receiving the lifting force of the upward flow from below and the suppressing force of the downward flow from above, it travels while floating on the transport path 10. Irradiation window 4
When it comes under, it is exposed to the electron beam e. It rotates freely and receives the electron beam uniformly over the entire surface. After the electron beam treatment, the powdered particles are further advanced and taken out of the discharge hopper 12 to the outside.

[0050]

The use of ethylene oxide and methyl bromide gas in foods is being restricted, and there is a strong possibility that it will be banned in the future. INDUSTRIAL APPLICABILITY The present invention can sterilize powdery foods such as tea leaves, wheat, rice, and beans without using toxic gas.
It is a promising sterilization method with no residual gas and excellent hygiene.
In addition, since the particles are transported while floating, and the electron beam is applied while allowing free movement, the entire surface of the object can be irradiated with the electron beam. Since the electron beam only needs to be applied to the surface layer, the present invention is an optimal processing method that can uniformly irradiate the entire surface with a shallow electron beam.

If the object to be processed does not rotate, it is necessary to use a high energy electron beam that penetrates the whole object. A large-sized device is required to supply energy such that an electron beam penetrates the whole of grains, beans and the like. However, in the present invention, since the object to be processed rotates freely, penetrating energy is unnecessary and a low energy electron beam that penetrates only into the surface layer may be used. Since the energy is low, the whole device can be made compact. This can reduce the processing cost.

Since the particles freely float and rotate at random and receive an electron beam, the irradiation amount of the electron beam is constant even between the particles. Irradiation unevenness between particles cannot be achieved. It's a really good way.

The gas transport requires a delicate balance.
Simply using the upward flow does not result in a uniform flow, only the powder soars. Since the present invention supplies a gas flow that can be independently controlled from at least three directions, optimal conditions can be given to the target. Because of its high controllability, it can be applied to various powders. Wide application range. An electron beam can be irradiated from all surfaces, and high energy of a penetration level is not required. Equipment downsizing and cost reduction are possible.

Due to the delicate balance of the three-way flow, pieces of the object to be processed and scum are completely conveyed, so that no contamination occurs. In addition to sterilizing food ingredients, curing resin pellets,
It can also be used for coating film curing.

[Brief description of the drawings]

FIG. 1 is a front view of a central longitudinal section of an electron beam irradiation apparatus according to an embodiment of the present invention.

FIG. 2 is a vertical sectional side view of a portion of a conveyance path of the apparatus of FIG.

FIG. 3 is a vertical cross-sectional side view of a transport path portion including an irradiation window of the apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Shield electrode 3 Filament 4 Irradiation window 5 Window foil 6 Window foil flange 7 Window foil holder 8 Housing 9 Transport mechanism 10 Transport path 11 Input hopper 12 Discharge hopper 13 Transport path bottom plate 14 Upper plate of transport path 15 Front plate of transport path DESCRIPTION OF SYMBOLS 16 Back plate of conveyance path 17, 18 Side plate of conveyance path 20 Lower perforated plate 21 Upper perforated plate 22 Front perforated plate 23 Lower gas chamber 24 Upper gas chamber 25 Front gas chamber 30 Blower 31 First flow control valve 32 Second flow control valve 33 Third flow control valve 34 Piping 35 Piping 36 Piping 37 Piping 38 Piping 39 Piping H Particles e Electron beam

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Mutsui Mizutani F-term (reference) 4C058 AA21 BB06 EE22 EE23 KK03 4G075 AA22 AA30 AA61 BB10 CA03 CA39 EB31 in Nisshin High Voltage Co., Ltd. EC02 ED11 FB02

Claims (3)

[Claims] 1. A porous plate provided at an input port of a granular material, a transfer path, a discharge port of an object to be processed, a start end, an upper part, and a lower part of a transfer path. By a mechanism that can independently control the flow rate, a transport mechanism that lifts and transports the powder and granules by blowing gas in at least three directions, a housing that surrounds the transport mechanism, and an electron beam fixed outside the housing An electron beam irradiating apparatus, comprising: an electron beam generating mechanism for generating and accelerating, wherein the electron beam is radiated while mixing and agitating the powder and granules in a transport mechanism. 2. The method according to claim 1, wherein the particles are suspended and transported by a gas flow from at least three directions in a transport path surrounded by a housing, and irradiated with an electron beam during the transport, whereby the particles are removed. An electron beam irradiation method comprising performing electron beam treatment. 3. An object to be processed, which is floated and conveyed by a gas flow from at least three directions in a conveyance path surrounded by a housing, and is irradiated with an electron beam during the conveyance.