JP3804042B2 - Electron beam irradiation device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of an electron beam irradiation apparatus for sterilizing powder particles such as grains and spices. An electron beam irradiation apparatus is an apparatus that generates an electron beam in a vacuum, accelerates it, takes it out into the atmosphere through a window foil, and irradiates a workpiece. The acceleration energy of the electron beam ranges from 5 MeV to several tens keV. The appropriate acceleration energy varies depending on the object to be processed and the processing purpose.
[0002]
For example, it is used for promoting the cross-linking reaction of the wire coating. Electron beam irradiation is also used for curing the polymer coating. It is also effective for printed materials and coating film curing. It is also used for sterilization of medical instruments and medical materials. These are those that cause a certain reaction by exposing an electron beam to an object to be processed of a fixed solid.
[0003]
Sterilization of medical instruments and materials by radiation of cobalt 60 has been performed by radiation of cobalt 60, but radioactive materials are not easy to use because careful attention must be paid to supply, transportation and storage. Therefore, electron beam irradiation devices have come to be used to sterilize fixed solids such as medical materials.
[0004]
The electron beam irradiation apparatus includes a portion that generates and accelerates an electron beam and a portion that irradiates the object to be processed. The former consists of a high-voltage power source, a filament power source, a vacuum chamber, a filament, an acceleration electrode, and the like. In the vacuum chamber, an electron beam is generated from a hot filament and accelerated by applying a voltage. The latter includes a shielding housing, a transport device, and the like.
[0005]
The shielding case is a heavy box for shielding X-rays. The transport device transports an object to be processed from the shielding housing entrance to the shielding housing exit so as to receive electron beam irradiation on the way. When the fixed solid is an object to be processed, the transport mechanism often uses an endless conveyor. An electron beam irradiation window is at the boundary between the electron beam generation acceleration portion and the conveyance path of the workpiece. A window foil is stretched on the irradiation window to partition the atmospheric pressure on the workpiece side and the vacuum on the filament side.
[0006]
Not only does the window foil have a pressure difference, it is heated by the passage of an electron beam. The window foil is strongly cooled by cooling water or cooling air so that the window foil is not broken by heating with an electron beam. In the case of cooling water, a cooling pipe is attached to a frame that holds the window foil so that it is cooled from the vacuum side. In the case of cooling air, the window foil is blown obliquely from the atmospheric pressure side.
[0007]
The cooling air may be dry air or nitrogen gas. The reason is as follows. X-rays are emitted because an electron beam is applied to a solid. X-rays are dangerous radiation. In order to shield X-rays, the entire transport system is covered with a shielding housing. When the atmosphere contains oxygen, X-rays oxidize oxygen to produce ozone. When dry air is used as cooling air, ozone is generated. Since ozone is also a harmful gas, it is necessary to forcibly exhaust it from the gas exhaust system. If the workpiece itself is affected by ozone, the ozone generation itself must be suppressed. In that case, nitrogen gas or rare gas is forcibly blown as cooling air. If nitrogen gas or noble gas, there is no fear of generating ozone by X-ray.
[0008]
[Prior art]
Attempts to use the electron beam irradiation apparatus, which has been used for processing solid solids, for sterilization of grains and spices have been promoted by the present applicants. Grains such as wheat, rice, soybeans and barley, and spices such as pepper are usually not sterilized. May be sterilized if it can be eaten raw or if it is imported food. Grain insecticides may be fumigated with methyl bromide or ethylene oxide. However, chemical treatment is not always safe because toxic gases may remain. Compared with that, the treatment with the electron beam is safe and preferable. The electron beam has a bactericidal action and should be used. There are still problems in terms of cost, but they will eventually be overcome.
[0009]
In addition to cost, there are various problems to be solved in the electron beam processing of grains and spices. One is that it is necessary to apply a thin electron beam only to the surface. Since the particles are small, it is possible to increase the acceleration energy and penetrate the electron beam throughout the particles. However, if an electron beam penetrates inside, proteins and carbohydrates are denatured and the flavor is lowered. It is not preferable. In addition, only the surface of particles such as grains may be contaminated by bacteria. Therefore, it is desirable to apply a thin penetrating electron beam only to the surface.
[0010]
This becomes a problem of the transport system. In the case where a conventional fixed solid is used as an object to be processed, an endless circulating conveyor has been used as a transport system. Since it is sufficient to irradiate only one surface with an electron beam, it should have been transported by a static endless conveyor. However, in the case of an object to be processed in which it is necessary to apply a thin electron beam to the entire surface, an endless conveyor which is a static conveying means is not useful. This is because an electron beam cannot be applied to the back side.
[0011]
Accordingly, the present applicants have come up with the idea of using a vibrating conveyor for the conveying system or using a wind-powered conveying system. A vibrating conveyor is a conveyor device that advances particles by vibrating a trough made of a metal plate in an oblique direction. Because the particles are lifted by the vibration trough, there is always a moment when the surface rotates strongly and the entire surface faces the electron beam. The entire surface can be exposed to a thin electron beam. For example, the applicant has made the following proposal.
[0012]
(1) Japanese Patent Application No. 10-142873 “Electron Beam Irradiating Device” proposes an electron beam irradiating device for conveying grains by a vibrating conveyor.
[0013]
(2) Japanese Patent Application No. 11-61327 “Electron Beam Irradiation Device, Electron Beam Irradiation Method, and Object to be Processed” proposes an electron beam irradiation apparatus having a wind conveyor that lifts and conveys particles to be processed by wind force.
[0014]
(3) Japanese Patent Application No. 2000-134640 “Electron Beam Irradiation Device” proposes an electron beam irradiation device having a conveying system using a vibrating conveyor. Since the amplitude when the vibrating conveyor stops is abnormally large, the height of the vibrating conveyor can be adjusted so that the vibrating conveyor does not collide with the electron beam generating mechanism.
[0015]
The next problem is ozone. I explained that cooling air is necessary because the window foil is heated. Since oxygen is converted into ozone by X-rays, it is stated that an inert gas such as nitrogen gas noble gas is used as cooling air when ozone generation is disliked. When ozone is generated due to oxygen in the atmosphere gas, a strong ozone odor adheres to the object to be treated. If ozone odor adheres to grains, it does not become food. However, since it is in the form of particles, it has a void portion that is intertwined inside, and the effective cavity volume is wide. In addition, the air adhering to the surface cannot be easily removed because the gap is narrow. Even if nitrogen gas is blown onto grains that have been deposited in a static state, it is difficult to completely replace the air contained in the interior simply by scratching the surface. It is difficult to strip off air that is strongly attached to the surface of fine particles such as grains and spices.
[0016]
Therefore, it is necessary not only for the purpose of cooling the window foil but also for blowing an inert gas onto the object to be processed in order to forcefully remove oxygen from the object particles. Oxygen must be stripped off and all surrounding gas must be replaced with an inert gas such as nitrogen gas. Therefore, it is not always sprayed toward the window foil from near the window foil like cooling air. In order to distinguish the gas for cooling from the cooling air, it can be expressed as, for example, oxygen stripping gas. A device for preventing the generation of ozone is indispensable when food is used for electron beam sterilization. The present applicant has also made several proposals for such a device.
[0017]
(4) Japanese Patent Application No. 2000-134691 “Electron Beam Irradiator” blows an inert gas into a hopper on the inlet side to strip oxygen. In this application, a prior application of an imagination by the inventor is described. That is, an inert gas (nitrogen gas or noble gas) is blown toward the particles from the vicinity of the window foil to replace oxygen with the inert gas. The gas exits from the workpiece inlet and the workpiece outlet. The conductance is large because it is discharged from a wide open outlet and inlet. In other words, gas consumption is enormous. However, in (4), the particles are retained by using the workpiece inlet side and the workpiece outlet side as hoppers, and an inert gas is introduced from the side into the inlet hopper. The object to be processed has a large amount of oxygen gas, but the oxygen is stripped off by the inert gas while staying in the inlet hopper and reaches the irradiation part, where it is subjected to electron beam processing. . The gas containing oxygen is discharged from the outlet hopper together with the object to be processed.
[0018]
There seems to be no prior art other than (4) that introduces an inert gas for stripping oxygen in order to sterilize foodstuffs such as grains and spices with an electron beam. It was not found by the inventor's investigation. Although the object to be treated is not food and sterilization is not the purpose, there is a prior art of the electron beam irradiation apparatus by the present applicant regarding gas flow. This is a technique for curing a coating material, printing ink, adhesive, and the like with an electron beam.
[0019]
(5) Japanese Patent Application Laid-Open No. 9-262528, “Electron Beam Irradiation Processing Device” uses an electron beam on paper, film, metal to cure the coating, printing, adhesive application on paper, film, metal, etc. We propose improvement of the device that applies When an electron beam is applied to a polymer material such as a coating agent, ink, adhesive, etc., radicals are generated, which promote the curing reaction. In an oxygen atmosphere, the radicals that can be broken react with oxygen to significantly inhibit the curing reaction. Since this is a problem, electron beam irradiation is performed in a nitrogen atmosphere excluding oxygen. Nitrogen gas is blown from the gas blowing port near the irradiation window and the gas is drawn from the gas drawing port near the irradiation window. The extracted nitrogen gas is contaminated with printing ink, organic solvent, and the like. The extracted used nitrogen gas is cooled with cooling water, and the gas is cooled and solidified with a cold trap of liquid nitrogen to remove components such as organic substances (solvent, ink, adhesive). Then, nitrogen gas is again blown from the gas blowing port on the downstream side of the irradiation window of the electron beam irradiation apparatus. Nitrogen gas can be saved because the gas is circulated.
[0020]
However, in the conventional example (5), the granular food is not a workpiece. A fixed solid such as a sheet, a plate member, or paper is an object to be processed. The purpose is to prevent oxygen from interfering with the radical reaction. If oxygen becomes ozone, the flavor is impaired, so oxygen is not excluded.
[0021]
[Problems to be solved by the invention]
In the conventional example, the inert gas is disposable. The amount of expensive inert gas (nitrogen gas or rare gas) used is large, and the running cost is expensive.
This is the biggest difficulty, but there are other causes of gas waste.
[0022]
In the conventional example, there is a large amount of gas leakage from the inlet opening and the outlet opening. In the end, it must be in a state where gas is constantly flowing. This is because there is nothing to prevent gas escape at the inlet and outlet.
[0023]
In the case of granular materials, a normal endless conveyor cannot be used. In the case of carrying out vibration conveyance, the action of sucking in the surrounding air due to trough vibration works remarkably. It is easy to inhale external air, and there is a tendency that the oxygen concentration is higher than that of a normal electron beam irradiation apparatus. So extra oxygen removal must be done.
[0024]
When grains or powders such as cereals and spices are used as treatment objects, the effective cavity volume is large, the amount of air brought along with cereals is large, and an extra replacement gas is required. A large amount of inert gas is required. There is a need for a device that reduces the cost of gas.
[0025]
[Means for Solving the Problems]
The present invention relates to an electron beam irradiation apparatus for sterilizing granular foods, wherein an inlet hopper and an outlet hopper are provided, and an inert gas for preventing ozone generation is supplied from the inlet hopper and the irradiation unit downstream from the electron beam irradiation apparatus. Infuse. Further, the inert gas is drawn out in the path immediately after the inlet hopper, or immediately after the inlet hopper and at the outlet hopper, oxygen is removed, the shortage is replenished, and the inert gas is circulated and used again.
[0026]
This is novel in that the point where the inert gas is drawn out is the vicinity of the inlet hopper, the inert gas is blown into the inlet hopper, and the inert gas is circulated and used.
[0027]
In the above, the inert gas is blown from the downstream of the irradiation unit, but in addition, the inert gas may be blown into the inlet hopper. It can be expressed as:
[0028]
In an electron beam irradiation device for sterilizing granular food, an inert gas is blown into the electron beam irradiation device downstream from the irradiation unit and from the inlet hopper to prevent generation of ozone, and a path and outlet connecting the inlet hopper and the electron beam irradiation device In the side hopper, the inert gas is drawn out, oxygen is removed, the deficiency is replenished, and blown again into the electron beam irradiation apparatus, and the inert gas is circulated and used.
[0029]
This is because the point where the inert gas is drawn out is the vicinity of the inlet hopper and the outlet hopper, the point where the inert gas is blown is the inlet hopper in addition to the irradiation unit downstream point, and the inert gas is circulated and used. This is new.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
In order to make the gas circulation type electron beam irradiation apparatus of the present invention, the following improvements must be made.
(1) A hopper is provided on the inlet side to collect the granular material to be processed and supply it to the electron beam irradiation apparatus (referred to as an inlet-side hopper). When the powder particles are supplied to the transport system all at once, the particles are overlapped and stacked to prevent the electron beam from hitting. This should not be. It is necessary to supply the particles to be processed to the conveying system at such a speed that the thickness of the trough of the vibration conveyor is about one layer. It is not new as a supply system for powder and granular materials. However, they are for putting the processed material particles that are likely to be scattered on the transport system without being scattered. In the present invention, the inlet hopper also has a role of preventing the escape of gas to the inlet side, and its role is novel.
[0031]
(2) A treated pulverized material is collected on the outlet side, and a hopper for discharging the granular material to the outside at an appropriate speed is provided (referred to as an outlet-side hopper). The outlet hopper also has an object of preventing gas leakage to the gas outlet side by the action of the granular material itself. There is no other than the above (4) Japanese Patent Application No. 2000-134691 to provide a hopper on the outlet side in the powder processing. This also delayed the discharge of the granular material and prevented gas leakage from the outlet side.
[0032]
(3) A gas inlet is provided immediately downstream of the irradiation window. This downstream side blowing port is also provided in a normal electron beam irradiation apparatus. Nitrogen gas is blown into the transport system from the downstream side of the irradiation window. Most of this gas flows upstream, excludes oxygen in the vicinity of the irradiation window, removes oxygen upstream of the transport system, and stubbornly passes through the gaps in the pre-treatment powder particles that fall through a narrow path from the inlet hopper. Remove the sticking oxygen. This gas flow is most important for oxygen replacement.
[0033]
(4) A gas discharge port is provided in a narrow path immediately before the transfer system immediately after the inlet hopper to discharge the oxygen-containing gas to the outside of the transfer system. In the conventional electron beam irradiation apparatus, a gas discharge port is provided immediately upstream of the irradiation window. In that case, oxygen will be taken away just under the irradiation window, which is incomplete. Since the gas discharge port is far upstream from the irradiation unit, the discharged gas strips oxygen from the granular material in a wide range such as from the irradiation window downstream to the irradiation window upstream, the conveyance system upstream, and the narrow path. . In other words, since the contact time and the contact length with the granule are long, oxygen replacement can be performed more completely.
[0034]
(5) A gas blowing port for an inert gas is provided inside the inlet hopper. Since the inert gas is blown into the inside of the granular material staying inside the inlet hopper, it can enter the voids of the granular material to remove attached oxygen and effectively replace oxygen. Since the gas is blown into the inside of the granular material which is almost stationary, the attached oxygen can be removed even if the amount of the inert gas is small. Since the oxygen concentration in the inlet hopper is the highest, it is extremely effective to blow an inert gas into the inlet hopper and replace the oxygen. The inert gas containing oxygen is not brought into the irradiation window because the gas outlet of the narrow path (4) is eliminated. It is a very good idea to remove oxygen in the early stages of the inlet hopper.
[0035]
(6) A gas discharge port is also provided in the outlet hopper or the narrow path following the outlet hopper. Part of the gas is also discharged from here. As described above, one of the purposes of providing the outlet hopper is to prevent leakage of the inert gas from the outlet. If the gas is removed from the outlet side, a large amount of gas is wasted. However, even if the particles are retained in the outlet hopper, part of the gas enters the gap between the particles in the outlet hopper. Therefore, it may be necessary to eliminate the gas inside the outlet hopper. For this purpose, a gas discharge port is also provided on the outlet side (exit-side hopper or narrow path near the outlet-side hopper).
[0036]
(7) Water, impurities, and oxygen are removed from the inert gas discharged from the vicinity of the inlet hopper and the inert gas discharged from the vicinity of the outlet hopper through a cold trap. A dry inert gas is obtained.
[0037]
(8) A deficient inert gas is added, and the dry inert gas is again blown from the gas blowing port on the downstream side of the irradiation unit and the gas blowing port of the inlet hopper. Such circulation use is a remarkable feature of the present invention. Since the inert gas is an expensive gas, if the gas is directly scattered in the air as in the conventional example, the gas cost is high. Therefore, the present invention recycles the inert gas once used through a cold trap and uses it in a circulating manner. As a result, the running cost related to gas can be greatly reduced.
[0038]
【Example】
An electron beam irradiation apparatus according to an embodiment of the present invention will be described with reference to FIG. This illustrates an area type (non-scanning type) electron beam irradiation apparatus.
[0039]
A concentric shield electrode 2 is provided inside the cylindrical vacuum chamber 1. There is a parallel filament 3 in the shield electrode 2. In vacuum, a negative voltage is applied to the filament 3 and a filament current flows. Heat electrons are emitted from the filament 3 by being heated by the electric current. This is accelerated by a negative voltage to become an electron beam e. The opening at the bottom of the vacuum chamber 1 serves as the irradiation window 4. This is a window for drawing an electron beam into the atmosphere. A window foil 5 is stretched on the irradiation window 4 to separate the vacuum from the atmospheric pressure. The window foil 5 is provided with an appropriate cooling mechanism as described above. Immediately below the irradiation window 4 is a transport mechanism 6 for transporting the workpiece. Since the transport mechanism 6 needs to rotate the particulate workpiece as described above, a vibrating conveyor or the like is suitable. Here, illustration of a vibration source and a spring for supporting the trough is omitted.
[0040]
The granular material S, which is a horizontally long transport mechanism and is a workpiece, is transported from left to right in the drawing. The workpiece introduced from the inlet hopper 7 is transported to the outlet hopper 8 by the transport mechanism 6 and undergoes electron beam processing in the middle. A second inert gas blowing port 9 is provided on the downstream side in the vicinity of the irradiation window 4. The gas blown from here is urged upstream by the wind direction plate 10. The inert gas travels upstream from the second inert gas inlet 9 on the downstream side of the irradiation window.
[0041]
The inlet hopper 7 is connected to the front of the transport mechanism 6 through the narrow path 11. The inlet side narrow path 11 is provided with an inert gas outlet 12. The inert gas that has traveled upstream from the inert gas inlet 9 takes away oxygen adhering to the powder and exits from the inert gas outlet 12 to the outside. An inert gas discharge port 14 is also provided in the narrow path 13 of the outlet hopper 8 at the rear of the transport mechanism 6. This draws an inert gas from the treated granule. Here, rather than extracting oxygen, the downward movement of the powder can be adjusted by extracting gas from here. The granular material S falls onto the carry-out conveyor 16 through the rotary valve 15 at the lower end of the narrow path 13. The carry-out conveyor 16 conveys the processed object to be processed to an appropriate part.
[0042]
The most important inert gas blowing port is the second inert gas blowing port 9 provided immediately downstream of the irradiation unit 17 (just below the irradiation window 4). However, in order to make oxygen removal even more complete, it is preferable to blow inert gas from the side of the inlet hopper 7.
[0043]
In this figure, a first inert gas inlet 18 is provided above the inlet hopper 7. About the inlet side hopper, you may make it provide the 1st inert gas blowing inlet 19 in the site | part shown with the lower broken line. This is an alternative and only needs to be in either one.
[0044]
The granular material S is conveyed to the upper part of the electron beam irradiation device by the input conveyor 20. The granular material S drops from the input conveyor 20 to the input port 21, and then drops into the inlet hopper 7 through the rotary valve 22. The powder S stays in the inlet hopper 7 for a while. The rotary valve 22 adjusts the input amount.
[0045]
Screen meshes 23 and 24 are provided at the inert gas outlet 12 of the narrow path 11 and the inert gas outlet 14 of the narrow path 13. The screen meshes 23 and 24 pass gas and do not pass the granular material S.
[0046]
An inert gas is blown into the inlet hopper 7 from an inert gas blowing port 18. This sews through the gaps between the staying powder and scrapes off oxygen. The inert gas containing oxygen and moisture is drawn out from the inert gas outlet 12 of the narrow path 11. Oxygen, moisture, light impurities, and the like are removed by the flow of the inert gas in the inlet hopper 7.
[0047]
The inert gas drawn out from the inert gas discharge port 12 on the inlet side passes through the path a, passes through the discharge port flow rate adjustment valve 25, and reaches the blower 26 from the path b. The inert gas drawn out from the inert gas discharge port 14 on the outlet side passes through the path c and passes through the discharge port flow rate adjustment valve 27 to the blower 26 from the path d. The blower 26 collects the inert gas discharged from both of the inert gas discharge ports and applies pressure to circulate through the path.
[0048]
The inert gas passes from the blower 26 through the path g and enters the cold trap 28 where it is cooled by liquid nitrogen. Moisture, impurities, etc. are trapped on the trap surface. Not only that, oxygen is also trapped here. In the conventional example (5), the cold trap captures and removes the printing ink, adhesive, etc., but the cold trap of the present invention can remove moisture, impurities, and oxygen. The cold trap cools the vessel wall surface with liquid nitrogen or liquid helium to lower the vapor pressure and remove volatile components and impurities in the gas. Naturally, moisture and light impurities (powder) can be removed.
[0049]
How can we eliminate oxygen? Since it cools with liquid nitrogen, the inner surface temperature of the container is lowered to a liquid nitrogen temperature of 77K. The boiling point of oxygen is 90K. Therefore, oxygen is also liquefied and adheres as droplets to the wall surface of the cold trap 28. So oxygen can also be collected. The gas that has passed through the cold trap 28 has returned to a pure inert gas (nitrogen gas, rare gas). The gas purified and purified by the cold trap 28 passes through the path h to the mixer 29. The new inert gas is guided to the mixer 29 via the path p, the flow rate adjusting valve 32, and the path i. The gas regenerated in the cold trap 28 is replenished with a new inert gas in the mixer 29.
[0050]
The inert gas passes through the path j, and is blown again into the downstream transport mechanism 6 from the second inert gas blowing port 9 via the blowing port flow rate adjustment valve 30. At the same time, the air is blown from the first inert gas blowing port 18 into the inlet hopper 7 through the blowing port flow rate adjusting valve 31. Thus, the feature of the present invention is that the inert gas is purified and circulated.
[0051]
Although it is used cyclically, the path is not single. There are two gas outlets, B and D. There are two gas inlets, A and C. Therefore, the path f-26-g-28-h-29-j including the blower 26, the cold trap 28, and the mixer 29 is common, but branches before and after that. If you consider the blower 26 as a heart,
B → 26 (B-a-25-b-f-26)
D → 26 (Dc-27-df-26)
There are two venous flows. The flow rate of the venous flow can be freely adjusted by the flow rate adjusting valves 25 and 27.
[0052]
As well
26-> C (26-g-28-h-29-j-kn-30-r-C)
26 → A (26-g-28-h-29-j-k-31-m-A)
There will be two arterial flows. The magnitude of the arterial flow can be freely controlled by the flow rate adjusting valves 30 and 31.
[0053]
In both cases, moisture and oxygen are removed from the cold trap and recycled. These are views of the gas flow outside the electron beam irradiation apparatus. A different complicated gas flow is formed inside the electron beam irradiation apparatus. The flow rate of the gas flowing inside can also be indirectly controlled by the flow rate adjusting valves 25, 27, 30, 31. Each of these gas streams has a different role.
[0054]
(1) Gas flow C → B
A flow in which the inert gas blown from the downstream of the irradiation unit 17 passes through the irradiation unit 17 and strips oxygen while coming into contact with the powder S, and is removed from the inert gas discharge port 12 below the inlet-side hopper 7. It is. This is the most basic gas flow. Since the irradiation window 4 flows from the downstream side to the upstream side, oxygen is prevented from passing through the irradiation window. The granular material that has fallen into the transport system is a thin layer of about one layer, and the contact with the inert gas is vigorous, and the action of removing adhering oxygen is great. Since it goes back through the narrow path 11, it is easy to remove the oxygen and moisture by separating the particles against the falling of the particles.
[0055]
(2) Gas flow A → B
The inert gas blown into the inlet-side hopper 7 from the first inert gas blow-in port 18 sinks into the accumulated static granular material, passes through the narrow path, takes in the attached oxygen and air, and takes the narrow path 11. From the top to the bottom and is removed from the inert gas outlet 12 (B). Since the granular material S containing plenty of air exists in the inlet-side hopper 7, it is effective to remove the air here and replace it with an inert gas. It is intended to remove air, oxygen and moisture long before the irradiation window. Although preliminary, most of the oxygen can be replaced here by an inert gas. Moreover, since the workpiece S inside the inlet hopper 7 is almost stationary, the oxygen replacement effect is great even if the gas consumption is small. Gas containing oxygen and moisture impurities exits from the first inert gas outlet 12 and does not reach the irradiation window 4 and the irradiation unit 17.
[0056]
(3) Gas flow C → D
Most of the gas that enters from the second inert gas inlet 9 goes back to the upstream side. The wind direction plate 10 biases it. It flows upstream and prevents oxygen from entering the irradiation window 4. This is the C → B flow described above. However, some gas is drawn out from the inert gas outlet 14 on the outlet side. This flow is useful as one means of controlling the flow of the granular material at the outlet hopper rather than removing oxygen and moisture. It is possible to prevent clogging of the granular material in the narrow passage 13 of the outlet hopper 8 and to adjust the descending speed of the granular material. For the original purpose of replacing oxygen, the second inert gas outlet 14 (D) can be omitted.
[0057]
(4) Gas flow A → D
From the first inert gas blowing port 18 (A), the inlet side hopper 7 passes through the transport path, reaches the outlet side hopper, and is discharged from the second inert gas discharge port 14 (D). However, there is almost no such gas and it is not important. The presence of this gas flow is not desirable because there is a possibility that the oxygen-containing granular material may pass directly under the irradiation window 4. So it can be said that there is almost no flow.
[0058]
Since there are two gas inlets and two gas outlets, there are four gas paths. Of these, the two most important are (1) C → B and (2) A → B. Naturally, the second inert gas outlet 14 is an outlet that is not useful in terms of oxygen exclusion, and is for gas flow control. The outlet 14 can be omitted.
[0059]
When the transport mechanism 6 is a vibrating conveyor, gas may be sucked into the path of the transport path 6 from the inlet-side hopper 7 and the outlet-side hopper 8 by a pump action caused by vibration. At this time, in order not to increase the oxygen concentration in the transport path,
V ₁ , V ₂ > V ₃ (1)
It is preferable that
[0060]
Where V ₁ Is the volume of the inlet hopper 7, V ₂ Is the volume of the outlet hopper 8, V ₃ Is the volume of the transport path 6. Inlet hopper volume, outlet hopper volume (V ₁ , V ₂ ) Is transport path V ₃ Serves as a buffer layer.
[0061]
【The invention's effect】
In the present invention, the inert gas outlet 12 is provided immediately below the inlet hopper (point B). This is an important point. Further, an inert gas blowing port is provided in the inlet hopper. As a result, oxygen can be stripped and removed from the workpiece in the inlet hopper before entering the transport system.
[0062]
This alone can eliminate oxygen adhering to the object to be processed, but an inert gas inlet 9 is also provided on the downstream side (C) from the irradiation window. As a result, a gas flow of C → B is created, and the structure is such that oxygen is doubled from the workpiece S.
[0063]
Furthermore, the inert gas once used is regenerated and recycled. This can reduce the gas cost. Since a cold trap of liquid nitrogen is used, oxygen having a boiling point higher than that of nitrogen can be collected.
[0064]
An inlet hopper is provided on the inlet side to retain the object to be processed so as to prevent escape of the inert gas from the inlet side. An outlet hopper is provided on the outlet side to retain the object to be processed so as to prevent escape of the inert gas from the outlet side. The waste of inert gas is prevented and the gas cost is greatly reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an electron beam irradiation apparatus according to an embodiment of the present invention.
[Explanation of symbols]
1 Vacuum chamber
2 Shield electrode
3 Filament
4 Irradiation window
5 Window foil
6 Transport mechanism
7 Inlet hopper
8 Exit hopper
9 Second inert gas inlet
10 Wind direction board
11 Narrow path
12 First inert gas outlet
13 Narrow path
14 Second inert gas outlet
15 Rotary valve
16 Unloading conveyor
17 Irradiation part
18 First inert gas inlet
19 Inert gas inlet
20 Input conveyor
21 slot
22 Rotary valve
23 screen mesh
24 screen mesh
25 Discharge port flow adjustment valve
26 Blower
27 Discharge port flow adjustment valve
28 Cold Trap
29 Mixer
30 Blowing flow rate adjustment valve
31 Blowing flow rate adjustment valve
32 Flow control valve
e Electron beam
S powder

Claims (2)

An inlet hopper for temporarily storing powder particles, an outlet hopper for temporarily storing processed powder particles, and a transport mechanism for rotating and conveying the powder particles from the inlet hopper to the outlet hopper An electron beam irradiation unit that irradiates the granular material with an electron beam, a first inert gas inlet provided in the inlet hopper, and a path immediately after the inlet hopper. An inert gas discharge port, a second inert gas blowing port provided downstream of the irradiation window of the transport mechanism, a mechanism for removing oxygen from the inert gas discharged from the inert gas discharge port, and an inert gas An electron beam irradiation apparatus comprising: a circulation mechanism that collects an inert gas from a gas discharge port, energizes the inert gas, and returns the inert gas to the inert gas blowing port, and circulates and uses the inert gas. An inlet-side hopper for charging and temporarily retaining the powder, an outlet-side hopper for temporarily retaining the processed powder, and a transport mechanism for transporting the powder while rotating from the inlet-side hopper to the outlet-side hopper An electron beam irradiation unit that irradiates the granular material with an electron beam, a first inert gas inlet provided in the inlet hopper, and a path immediately after the inlet hopper. A first inert gas outlet, a second inert gas inlet provided downstream of the irradiation window of the transport mechanism, and a second inert gas outlet provided in the outlet-side hopper or a path immediately after the outlet. A mechanism for removing oxygen from the inert gas discharged from the outlet and the inert gas outlet, and a circulation mechanism for recovering the inert gas from the inert gas outlet, energizing it, and returning it to the inert gas inlet An electron beam illumination characterized by circulating an inert gas Apparatus.

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