A powder electron irradiation treatment device

Abstract

An electron irradiation treatment apparatus for powder, relating to the field of materials processing, is disclosed. It comprises a main chamber with a heating furnace, vertically arranged with a larger diameter at the top and a smaller diameter at the bottom, transitioning into a cylindrical shape via a conical section. The top cover of the main chamber is equipped with an electron irradiation titanium window for electron beam transmission, an exhaust outlet, and a feed inlet. The upper, larger diameter end of the main chamber has an inlet / outlet duct with a built-in cooling device and an auxiliary working gas inlet. The bottom of the main chamber has a double-layered bottom with a stirring paddle, a discharge port, and a working gas inlet. The mounting components are sealed to the main chamber. The working gas blows the powder up and maintains its fluidized state, ensuring the powder remains fluidized and suspended throughout the irradiation process and subsequent heat treatment, preventing heat accumulation during irradiation or sintering and agglomeration during heat treatment. The powder heat is easily dissipated during irradiation, allowing for the use of a larger electron beam current, and the process has wide applicability.

Description

Technical Field

[0001] This invention relates to the field of materials processing, and in particular to a powder electron irradiation treatment apparatus. Background Technology

[0002] Electron beam irradiation, a processing technology that uses an electron accelerator to generate a high-energy electron beam to irradiate the object being treated, has been widely applied in plastic crosslinking and curing, rubber vulcanization, waste oxidative degradation, and food sterilization, and has the potential for use in ceramic powder synthesis. Currently, there are two main challenges in using electron irradiation technology for powder synthesis: reducing the accumulation of irradiation heat and eliminating free radicals. Electron beams, especially high-energy electron beams with high accelerating voltages, have high energy density. When the irradiated object absorbs the electron beam, it generates a large number of free radicals. In this process, the kinetic energy of the electrons is converted into heat that accumulates inside the irradiated object; simultaneously, the annihilation of free radicals also generates heat. During powder irradiation, the poor heat dissipation of loosely packed powder, coupled with the failure to promptly dissipate this heat, can lead to powder sintering, agglomeration, and even melting into lumps.

[0003] To address this issue, existing powder processing methods often employ vacuum packaging, similar to those used for irradiating bulk materials, to compress the powder into clumps. This increases the bulk density and improves heat dissipation. However, even with this method, only small beams can be used to ensure timely heat dissipation. Furthermore, the initial powder compression increases subsequent processing steps (requiring powder redispersement), raising costs. Besides thermal factors, the annihilation of free radicals has a certain half-life. For some irradiated materials, if appropriate processing is not performed to remove free radicals, highly reactive free radicals can react with oxygen and water vapor in the air, resulting in impure products, releasing significant amounts of heat, and even causing spontaneous combustion (especially for powders and fibers with large surface areas). Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in existing powder irradiation processes by providing a powder electron irradiation treatment device. The powder to be irradiated by electron beam is fluidized and suspended in a cold gas for irradiation treatment. The heat generated during irradiation can be carried away by the fluidizing gas and the built-in cooling device. After irradiation, the powder can be heated in a fluidized state to eliminate free radicals and achieve a stable state.

[0005] The powder electron irradiation treatment device has a main structure consisting of a main cavity with a heating furnace. The main cavity is vertically arranged, with a larger diameter at the top and a smaller diameter at the bottom, transitioning into a cylindrical shape with a conical transition in the middle. The top cover of the main cavity is equipped with an electron irradiation titanium window for transmitting electron beams, an exhaust gas outlet, and a feed inlet. The upper large-diameter end of the main cavity has an inlet and outlet air duct with a built-in cooling device and an auxiliary working gas inlet. The bottom of the main cavity has a double-layer bottom with a stirring paddle, a discharge port, and a working gas inlet. All mounting components are sealed to the main cavity.

[0006] In the main cavity, the lower cylindrical section with a smaller diameter is the loading section, where the irradiated powder is loaded and blown up by the working gas into a fluidized state. The upper cylindrical section and conical section serve as the settling section for the fluidized bed powder. The powder to be irradiated that is blown up settles back into the loading section in the settling section.

[0007] Because the titanium window through which the electron beam passes is made of thin titanium foil, its strength is a limitation, and the titanium window cannot be made too wide. Existing accelerators all use narrow, slender titanium windows for their electron exits. Correspondingly, the electron irradiation titanium window should have a slender structure to match the accelerator, and the effective length of the electron irradiation titanium window should correspond to the diameter of the small-diameter section of the main cavity and be slightly smaller than the latter.

[0008] The inlet and outlet ducts of the built-in cooling device are installed on the side of the large cylindrical section. Inside the main cavity, the built-in cooling device enters the large cylindrical section and then vertically connects to the small cylindrical section. The vertical orientation of the built-in cooling device prevents the powder to be irradiated from settling onto it. Two sets of the built-in cooling device are provided, located on either side of the electron irradiation titanium window in the width direction, thus avoiding direct electron beam irradiation.

[0009] The double-layer bottom is installed at the bottom of the small-diameter section of the main cavity. The double-layer bottom is equipped with a stirring paddle, a discharge port, and a working gas inlet. The stirring paddle is installed from the bottom, with the stirring shaft avoiding the electron irradiation titanium window. The stirring paddle has an inclined scraper on the side near the double-layer bottom. By controlling the change of direction, the powder to be irradiated on the bottom plate can be scraped to the surroundings or gathered towards the center. This can enhance the mixing intensity of the powder to be irradiated during electron irradiation or heat treatment, and the stirring paddle can cleanly discharge the powder to be irradiated.

[0010] Furthermore, since the charging section needs to be heated for heat treatment after irradiation, the built-in cooling device uses a gas medium that can withstand the heating temperature for circulating cooling.

[0011] The working gas enters the gas distribution chamber of the double-layered bottom through the working gas port and is evenly distributed to the gas distribution holes of the upper plate, blowing the powder into a fluidized state. The gas distribution holes of the upper plate of the double-layered bottom blow the powder to be irradiated into a fluidized state. The distribution of the gas distribution holes corresponds to the electron irradiation titanium window and is located on the vertical projection of the electron irradiation titanium window. After the powder to be irradiated into a fluidized state by the working gas, it rises along the vertical direction of the vertical projection of the electron irradiation titanium window; and descends to the double-layered bottom at the positions where built-in cooling devices are installed on both sides.

[0012] During irradiation, the working gas passes through a working gas precooler before entering the double bottom. The cooled working gas can blow up the powder to be irradiated and carry away the heat generated by irradiation. After irradiation, when the working gas removes free radicals from the powder to be irradiated, it passes through a working gas preheater and together with the heating furnace of the main chamber, heats the powder to be irradiated to remove its free radicals.

[0013] Powder treated by electron beam irradiation is fluidized and suspended in a cold working gas for irradiation. The heat generated by the irradiated powder can be carried away by the cold fluidized working gas and the built-in cooling device. After irradiation, the powder can be heated in a fluidized state to eliminate free radicals and achieve a stable state.

[0014] The working gas can enter the main cavity through the auxiliary working gas port. The auxiliary working gas port can be used to replenish the working gas in the main cavity after the material is loaded and vacuumed, so as to avoid powder flying under vacuum.

[0015] The present invention has the following advantages:

[0016] (1) The powder can always be kept in a fluidized suspension state during the irradiation process and subsequent heat treatment, so as to avoid the powder from sintering and agglomerating during irradiation or subsequent heat treatment.

[0017] (2) The heat of the fluidized powder is easily dissipated, and it can be treated with high electron beam irradiation to reduce the processing time. The process has wide applicability.

[0018] (3) This powder electron irradiation treatment device can be used to achieve low-cost batch irradiation treatment of fine-grained, high-purity powders. Attached Figure Description

[0019] Figure 1 This is a side cross-sectional view of a powder electron irradiation treatment device.

[0020] Figure 2 This is a top view of a powder electron irradiation treatment device, where the left half shows the outer shell structure of the irradiation window and the right half shows the bottom structure of the device.

[0021] Figure 3 This is a schematic diagram of the working gas connection.

[0022] The markings in the figure are as follows: working gas 0a, main cavity 1, electron irradiation titanium window 2, exhaust gas outlet 3, gas cooling / dust filter 30, vacuum device 3a, exhaust gas emission device 3b, auxiliary working gas port 4, heating furnace 5, circulating cooling branch pipe 6, cooling air inlet pipe 6a, cooling air exhaust pipe 6b, stirring paddle 7, stirring paddle bottom inclined plate 72, double bottom 8, bottom working gas port 81, gas distribution hole 82, working gas precooler 83, working gas preheater 84, feed port 9, discharge port 10, PCS powder to be irradiated 100. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the following embodiments will be used in conjunction with the accompanying drawings to further illustrate the invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] Fusible polycarbosilane (PCS) is pulverized to form PCS powder. In this embodiment, the pulverized PCS powder is subjected to electron beam irradiation to form high-molecular-weight insoluble and infusible PCS powder. During the irradiation treatment of PCS powder, since PCS can form free radicals, it is necessary to remove the free radicals by heat treatment at 400-600°C after electron beam irradiation to achieve a stable state.

[0025] like Figures 1-3 The main cavity 1 of the powder electron irradiation treatment device is a concentric circular container composed of an upper large cylindrical section, a middle conical section, and a lower small cylindrical section. The lower small cylindrical section of the main cavity 1 is the loading section, which is used to load the PCS powder to be treated. The PCS powder 100 to be irradiated is loaded into the loading section and blown up by the working gas into a fluidized state. The upper large cylindrical section and the middle conical section serve as the settling section for the fluidized bed powder, where the blown powder settles back into the small cylindrical section.

[0026] The top of the main chamber 1 is equipped with an electron irradiation titanium window 2, a tail gas outlet 3, an auxiliary working gas port 4, and a feed port 9. The electron irradiation titanium window 2 is made of thin titanium foil and is used for electron irradiation into the main chamber 1 for irradiation treatment. The tail gas outlet 3 is used for vacuuming and discharging the tail gas generated during the treatment process. A gas cooling / dust filter 30 is installed between the tail gas outlet 3 and the tail gas emission device 3b to cool and filter dust and harmful substances in the tail gas, ensuring that the tail gas is effectively treated before emission and meets relevant emission environmental protection requirements. The electron irradiation titanium window 2 is a narrow rectangular structure, and its effective length is slightly smaller than the diameter of the small cylindrical section at the bottom of the main chamber 1. The PCS powder 100 to be irradiated is loaded into the loading section of the main chamber 1 through the feed port 9.

[0027] A vacuum pumping device 3a is connected to the main chamber 1 and is used to extract the air from the chamber before processing to achieve the required vacuum level. After the vacuum pumping device 3a evacuates the device, working gas 0a is introduced through the auxiliary working gas port 4 to prevent the PCS powder 100 to be irradiated from being stirred up.

[0028] The auxiliary working air port 4 is located on the side of the main cavity 1 and is used to replenish gas and maintain the pressure and gas flow in the cavity.

[0029] The heating furnace 5 surrounds the main cavity 1 and provides the temperature conditions required for subsequent heat treatment. The heating furnace 5 heats the irradiated PCS powder 100 to 400-600°C to remove its free radicals and ensures that the PCS powder 100 is heated uniformly during the process.

[0030] Two sets of circulating cooling branch pipes 6 are located on both sides of the width of the electron irradiation titanium window 2 to avoid direct radiation from the electron beam. The inlet and outlet of each set of circulating cooling branch pipes 6 are installed on the same side of the large cylindrical section of the main cavity 1. Inside the main cavity 1, the circulating cooling branch pipes 6 branch off from the large cylindrical section and then vertically extend to the small cylindrical section to prevent the PCS powder 100 to be irradiated from settling on the outer wall of the pipe. Cooled compressed carbon dioxide gas is introduced into the circulating cooling branch pipes 6 through the air inlet pipe 6a. After the compressed carbon dioxide gas expands, it carries away the heat of the PCS powder 100 to be irradiated. Finally, the expanded carbon dioxide gas is discharged through the exhaust pipe 6b.

[0031] The bottom of the small-diameter cylinder of the main chamber 1 is equipped with a stirring paddle 7, a double-layer bottom 8, a bottom working air port 81, and a discharge port 10. The stirring paddle 7 is installed from the bottom to avoid electron beam irradiation. The stirring paddle 7 is equipped with a bottom inclined plate 72 to facilitate the flow and mixing of PCS powder 100, ensuring that the PCS powder 100 is uniformly dispersed during the processing. When the direction of rotation is changed to counterclockwise 700, the PCS powder 100 to be irradiated on the bottom plate can be scraped to the surrounding area. When the direction of rotation is changed to clockwise 701, it is scraped towards the center. This can enhance the mixing intensity of the PCS powder 100 to be irradiated during electron irradiation and heat treatment, and the stirring paddle can be used to cleanly discharge the PCS powder 100 to be irradiated.

[0032] The double-layer bottom 8 is located at the bottom of the main cavity 1 and includes a bottom working gas port 81 and a gas distribution hole 82. The double-layer bottom 8 is used to support the PCS powder 100 to be irradiated and uniformly distributes the working gas 0a through the gas distribution hole 82, so that the PCS powder 100 to be irradiated is uniformly suspended for electron beam irradiation. The double-layer bottom 8 has a gas distribution chamber. After the working gas 0a enters the double-layer bottom 8 from the bottom working gas port 81, it is uniformly blown up by the gas distribution hole 82. The gas distribution hole 82 is distributed at the projection of the electron irradiation titanium window 2 onto the double-layer bottom 8. Under the action of the airflow, the PCS powder 100 to be irradiated rises along the vertical direction of the vertical projection of the electron irradiation titanium window to receive electron beam irradiation; the PCS powder 100 to be irradiated at the top flows back to the bottom along both sides equipped with circulating cooling branch pipes 6.

[0033] The working gas precooler 83 is used to precool the working gas 0a. The cooled working gas 0a can better blow up the PCS powder 100 to be irradiated and can effectively remove the heat generated during the irradiation process, which helps to maintain the temperature stability of the system and prevent the powder from overheating. The working gas preheater 84 is used to preheat the working gas 0a. The preheated working gas 0a helps to provide the necessary heat when removing free radicals in the irradiated PCS powder in the later stage. It works together with the heating furnace 5 to ensure that the PCS powder reaches the required temperature conditions during the process of removing free radicals.

[0034] The feed inlet 9 and discharge outlet 10 are respectively located at the top and bottom of the main cavity 1. The feed inlet 9 is used to add the PCS powder 100 to be irradiated, and the discharge outlet 10 is used to discharge the treated powder. After loading, the device is evacuated by the vacuum device 3a and then the working gas 0a is introduced through the auxiliary working gas port 4 to prevent the PCS powder 100 to be irradiated from being thrown up.

[0035] The powder electron irradiation treatment device of this invention features a main cavity design that is wider at the top and narrower at the bottom, facilitating powder fluidization and sedimentation, and ensuring uniformity and efficiency of irradiation treatment. A slender titanium electron irradiation window is used, with its effective length corresponding to the diameter of the small-diameter section of the main cavity, ensuring electron beam transmission while considering the strength limitations of the titanium window. An internal cooling device extends vertically to the small cylindrical section to prevent powder sedimentation, and utilizes a circulating gas medium for cooling, improving the cooling effect and adapting to the heat treatment temperature of the heating furnace. The double-layered bottom design of the stirring paddle and gas distribution holes enhances the mixing intensity of the powder, ensuring uniformity of irradiation treatment and facilitating powder discharge. The combined use of a working gas precooler and preheater effectively removes heat during irradiation, preventing powder overheating, and provides necessary heat for free radical removal, improving processing efficiency. All mounting components are sealed to the main cavity, ensuring the airtightness of the device and preventing external contamination and energy loss. The stirring paddle is equipped with an inclined scraper, which can change direction to scrape or gather the powder, enhancing the mixing effect and facilitating powder discharge. Experiments show that this invention can efficiently and uniformly perform electron irradiation treatment of powders, while also possessing good cooling and heating functions, making it suitable for the processing needs of various powder materials.

[0036] The above embodiments are merely preferred embodiments of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A powder electron irradiation treatment device, characterized in that... The main chamber is equipped with a heating furnace and is vertically arranged. The upper part of the main chamber has a larger diameter, while the lower part has a smaller diameter, with a conical transition in the middle to form a cylindrical cavity. The top cover of the main chamber is equipped with an electron irradiation titanium window for electron beam transmission, an exhaust outlet, and a feed inlet. The upper large-diameter end of the main chamber is equipped with an air inlet and outlet pipe with a built-in cooling device and an auxiliary working air inlet. The bottom of the main chamber is equipped with a double-layer bottom with a stirring paddle, a discharge outlet, and a working air inlet. All mounting components are sealed to the main chamber. The built-in cooling device is provided in two sets, respectively located on both sides of the width direction of the electron irradiation titanium window, and the built-in cooling device avoids direct irradiation by the electron beam. The double-layer bottom is installed at the bottom of the main cavity, and the stirring paddle is installed from the bottom. The stirring shaft avoids the electron irradiation titanium window. The stirring paddle has an inclined scraper on the side near the double-layer bottom. The direction of the inclined scraper is controlled to scrape the powder on the bottom plate to the surrounding area or to the center. During electron irradiation or heat treatment, the powder mixing intensity is enhanced, and the powder is cleanly discharged when it is discharged. The powder treated by electron beam irradiation is fluidized and suspended in a cold working gas for irradiation. The heat generated by the irradiated powder is carried away by the fluidized working gas and the built-in cooling device. After irradiation, the powder is heated in a fluidized state to eliminate free radicals and achieve a stable state.

2. The powder electron irradiation treatment device as described in claim 1, characterized in that... The lower cylindrical section of the main cavity with a small diameter is the loading section. The powder to be irradiated is loaded in the loading section and blown up by the working gas into a fluidized state. The upper cylindrical section with a large diameter and the middle conical section of the main cavity serve as the settling section for the fluidized bed powder. The powder to be irradiated that is blown up settles back into the small cylindrical section here.

3. The powder electron irradiation treatment device as described in claim 1, characterized in that... The electron irradiation titanium window is made of thin titanium foil and has a narrow and slender shape. The electron irradiation titanium window and its matching accelerator have a corresponding slender structure. The effective length of the electron irradiation titanium window corresponds to and is smaller than the diameter of the small diameter section of the main cavity.

4. The powder electron irradiation treatment device as described in claim 1, characterized in that... The air inlet and outlet ducts of the built-in cooling device are installed on the side of the large cylindrical section. Inside the main cavity, the built-in cooling device enters the large cylindrical section and then vertically leads to the small cylindrical section. The vertical installation prevents the powder to be irradiated from settling on the built-in cooling device. There are two sets of built-in cooling devices, which are respectively located on both sides of the width direction of the electron irradiation titanium window. The built-in cooling device avoids direct irradiation by the electron beam.

5. The powder electron irradiation treatment device as described in claim 1, characterized in that... The built-in cooling device uses a high-temperature resistant circulating medium for cooling.

6. The powder electron irradiation treatment apparatus as described in claim 1, characterized in that... The working gas enters the gas distribution chamber of the double-layer bottom through the working gas port and is evenly distributed to the gas distribution holes of the upper plate, blowing the powder into a fluidized state. The gas distribution holes of the upper plate of the double-layer bottom blow the powder to be irradiated into a fluidized state. The distribution of the gas distribution holes corresponds to the electron irradiation titanium window and is located on the vertical projection of the electron irradiation titanium window. After the powder to be irradiated into a fluidized state by the working gas, it rises along the vertical direction of the vertical projection of the electron irradiation titanium window and descends to the double-layer bottom at the positions where built-in cooling devices are installed on both sides.

7. The powder electron irradiation treatment device as described in claim 1, characterized in that... During irradiation, the working gas passes through a working gas precooler before entering the double bottom. The cooled working gas blows up the powder to be irradiated and carries away the heat generated by the irradiation. After irradiation, when the working gas removes free radicals from the powder to be irradiated, it passes through a working gas preheater and together with the heating furnace in the main chamber, heats the powder to be irradiated to remove its free radicals.

8. The powder electron irradiation treatment apparatus as described in claim 1, characterized in that... The working gas enters the main cavity through the auxiliary working gas port. The auxiliary working gas port is used to replenish the working gas in the main cavity after the material is loaded and vacuumed, so as to avoid the powder flying under vacuum.

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