Tubular furnace gas backflow sleeve

Abstract

The utility model discloses a tube furnace gas backflow sleeve, which belongs to the field of experimental instruments and comprises a furnace tube, a carrying box is movably arranged in the furnace tube, an opening is arranged on one side of the carrying box facing the gas inlet end of the furnace tube, and the carrying box is closed in other directions to form a space for placing experimental raw materials. The inner contours of the furnace tubes are larger than the outer contours of the carrying boxes. According to the tube furnace gas backflow sleeve, the object carrying box is added, so that the easily-sublimated object forms local turbulence after sublimation, the contact time of the easily-sublimated object and an object to be doped is effectively prolonged, a high-doping-amount catalyst is manufactured, the doping efficiency of volatile matters can be improved, the use of excessive easily-sublimated objects is avoided, and a tube furnace flange is prevented from being blocked.

Description

Technical Field

[0001] The utility model relates to a gas reflux sleeve of a tube furnace, belonging to the technical field of experimental instruments. Background Art

[0002] In the preparation method of carbon-based non-noble metal electrocatalysts, it usually includes a heat treatment step for precursor materials under specific atmosphere protection. The main purposes include carbonizing the carrier, reducing the metal, promoting the generation and transformation of sites, etc., to obtain the required catalytic performance. A newly developed heat treatment method is based on the principle of Chemical Vapor Deposition (CVD). An easily sublimable (or volatile) dopant is placed upstream of the tube furnace, and the material to be doped is placed downstream of the adjacent tube furnace. At high temperature, the volatile substances flow with the gas flow and contact the material to be doped to complete doping. Its advantage is that surface doping can be realized, which is beneficial to constructing rich surface sites. Two typical examples include: 1. A volatile metal source is placed upstream, and a carbon carrier with rich defects is placed downstream, and a highly dispersed metal catalyst is formed by volatilization; 2. A volatile non-metal source is placed upstream, and a carbon-based catalyst to be doped is placed downstream, and heteroatom doping of the catalyst is realized by volatilization.

[0003] Specifically, as shown in Figure 1 , an easily sublimable substance 8 and a material to be doped 9 are placed in the furnace tube 11 of the tube furnace. Both the easily sublimable substance 8 and the material to be doped 9 are within the range of the heating temperature zone 12 of the furnace tube 11. The easily sublimable substance 8 is located upstream of the material to be doped 9. Under the blowing of the carrier gas flow A, the easily sublimable substance 8 accelerates sublimation. The gas B formed by sublimation passes through the material to be doped 9 under the entrainment of the carrier gas flow A and dopes the material to be doped 9.

[0004] Although the prior art can prepare carbon-based non-noble metal electrocatalysts with surface doping, there are still the following problems:

[0005] (1) After the dopant volatilizes, it flows unidirectionally with the gas introduced into the tube furnace and has a short contact time with the material to be doped, and it is not easy to obtain a catalyst with a high doping amount.

[0006] (2) When the required doping temperature is high and the dopant is easy to volatilize, before reaching the appropriate doping temperature, a large amount of the dopant has volatilized, making it difficult to ensure effective doping.

[0007] (3) If an excessive amount of dopant is placed upstream to ensure the doping effect, when it volatilizes to the outlet flange, due to temperature reduction and cooling deposition, the outlet will be blocked. Summary of the Utility Model

[0008] In order to overcome the deficiencies of the prior art, the utility model provides a gas reflux sleeve of a tube furnace, which can reduce the waste of easily sublimable substances and achieve a higher doping amount with less easily sublimable substances.

[0009] The technical solution adopted by the present utility model to solve its technical problems is as follows:

[0010] A gas reflux sleeve for a tubular furnace, comprising a furnace tube, wherein a loading box is movably arranged in the furnace tube, an opening is arranged on one side of the loading box facing the air inlet end of the furnace tube, and the rest of the loading box is closed to form a space for placing experimental raw materials. On any radial section of the furnace tube, the inner contour of the furnace tube is larger than the outer contour of the loading box.

[0011] The gas reflux sleeve for a tubular furnace provided by this application forms a reflux of gas in the loading box by arranging a loading box with an opening in the furnace tube, prolongs the contact time between the gas and the experimental raw materials, is beneficial to improving the doping efficiency, and improves the experimental stability.

[0012] Further, the length of the longest side of the loading box is less than the length of the heating temperature zone of the furnace tube.

[0013] Further, a pull ring is arranged on one side of the loading box facing the air outlet end of the furnace tube.

[0014] Further, on one side of the loading box facing the air inlet end of the furnace tube, the upper part is closed and the opening is arranged at the lower part.

[0015] Furthermore, on one side of the loading box facing the air inlet end of the furnace tube, the ratio of the closed area to the opening area is 1:1 to 2:3.

[0016] As a possible implementation manner, the loading box is a cuboid.

[0017] Further, on the four surfaces of the loading box facing the inner wall of the furnace tube, rounded corners are arranged at the intersections of the surfaces.

[0018] Further, on the radial section of the furnace tube, the diagonal of the loading box is less than three-quarters of the diameter of the furnace tube.

[0019] Further, support feet are connected to the outer bottom surface of the loading box, and a smooth part is arranged at the lower end of the support feet.

[0020] Furthermore, a counterweight block is arranged at the center of the outer bottom surface of the loading box, and the bottom end of the counterweight block is higher than the bottom end of the smooth part.

[0021] The beneficial effects of the present utility model are as follows: The gas reflux sleeve for a tubular furnace of the present utility model adds a loading box, so that the sublimated substance forms local turbulence after sublimation, effectively increases the contact time with the substance to be doped, manufactures a high-doping catalyst, can improve the doping efficiency of the volatile substance, avoids using excessive sublimated substance, and avoids blocking of the tubular furnace flange.

[0022] Other features and advantages of the present application will be described in the subsequent specification, and partly will become apparent from the specification, or be understood by implementing the present application. The objectives and other advantages of the present application can be achieved and obtained through the structures specifically pointed out in the written specification and the attached drawings. Description of the Drawings

[0023] Figure 1 is a schematic diagram of material doping treatment in a tube furnace based on the CVD principle in the prior art.

[0024] Figure 2 is a schematic diagram of material doping treatment in a tube furnace based on the CVD principle of the present application.

[0025] Figure 3 is one of the schematic structural diagrams of a carrier box provided by an embodiment of the present application.

[0026] Figure 4 is another schematic structural diagram of a carrier box provided by an embodiment of the present application.

[0027] Figure 5 is a schematic structural diagram of a gas reflux sleeve of a tube furnace provided by an embodiment of the present application.

[0028] Figure 6 is a side view of a gas reflux sleeve of a tube furnace provided by an embodiment of the present application.

[0029] Reference Signs: 11, furnace tube; 12, heating temperature zone; 2, carrier box; 21, opening; 22, pull ring; 23, support feet; 231, rounded part; 24, counterweight; 8, easily sublimable substance; 9, doping substance to be doped. Detailed Embodiments

[0030] The following details the embodiments of the present utility model. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary only for explaining the present utility model and should not be construed as limiting the present utility model.

[0031] The following disclosure provides many different embodiments or examples for implementing different structures of the present utility model. To simplify the disclosure of the present utility model, components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present utility model. In addition, the present utility model may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0032] Refer toFigure 2 and Figure 3 In an embodiment of the present application, a gas reflux sleeve for a tube furnace is provided, which includes a furnace tube 11. A carrier box 2 is movably arranged inside the furnace tube 11. An opening 21 is arranged on one side of the carrier box 2 facing the gas inlet end of the furnace tube 11. The remaining directions of the carrier box 2 are all closed to form a space for placing experimental raw materials. On any radial cross-section of the furnace tube 11, the inner contour of the furnace tube 11 is larger than the outer contour of the carrier box 2.

[0033] The carrier box 2 is movably arranged inside the furnace tube 11, indicating that the carrier box 2 is movable inside the furnace tube 11, so as to adjust the position of the carrier box 2 inside the furnace tube 11 according to experimental requirements.

[0034] An opening 21 is arranged on one side of the carrier box 2 facing the gas inlet end of the furnace tube 11, and the remaining directions of the carrier box 2 are all in a closed state, thereby forming a cavity structure for placing experimental raw materials. Experimental gas needs to enter the inside of the carrier box 2 through the opening 21 to make full contact with the experimental raw materials.

[0035] On any radial cross-section of the furnace tube 11, the inner contour of the furnace tube 11 is larger than the outer contour of the carrier box 2, which means that the size of the carrier box 2 is smaller than that of the furnace tube 11, forming a gas channel between the two. Gas can flow around the outside of the carrier box 2.

[0036] The working principle of this gas reflux sleeve for a tube furnace is as follows:

[0037] In a gas doping experiment, first place the dopant 9 deep in the carrier box 2, then place the sublimable substance 8 inside the carrier box 2 near the opening 21. Finally, push the carrier box into the furnace tube 11 with a push rod so that the opening 21 faces the direction of the carrier gas flow A. Both the sublimable substance 8 and the dopant 9 are within the range of the heating temperature zone 12. Pass in the required atmosphere and start programmed temperature rise. After the heat preservation is completed, take out the carrier box 2 to obtain the successfully doped catalyst.

[0038] When the carrier gas flow is introduced from the gas inlet end of the furnace tube 11, a part of the gas enters the inside of the carrier box 2 through the opening 21 on one side of the carrier box 2 facing the gas inlet end and makes full contact with the experimental raw materials inside the carrier box 2. Since the remaining directions of the carrier box 2 are closed, the gas entering the inside of the carrier box 2 forms a reflux in the cavity, prolonging the contact time between the gas and the experimental raw materials, improving the doping efficiency and doping amount. At the same time, a part of the gas also flows around the carrier box 2 through the channel between the furnace tube 11 and the carrier box 2 and is discharged from the furnace tube 11, making the system gas flow rate stable. Because of the adoption of the carrier box 2 structure, only a small amount of sublimable substance 8 is needed to achieve doping, reducing the deposition of the sublimable substance at the outlet of the furnace tube 11 and reducing the risk of outlet blockage.

[0039] The present application further proposes that the length of the longest side of the carrier box 2 is less than the length of the heating zone 12 of the furnace tube 11. Thus, it can be ensured that when the carrier box 2 is placed inside the furnace tube 11, the whole of the carrier box 2 is located within the heating zone 12 of the furnace tube 11, which can prevent the gas B formed by the easily sublimable substance 8 from sublimating inside the carrier box due to temperature reduction, ensure the full utilization of the easily sublimable substance, and further improve the doping efficiency.

[0040] The present application further proposes that a pull ring 22 is provided on the side of the carrier box 2 facing the gas outlet end of the furnace tube 11, which facilitates the insertion of a long rod with a hook into the furnace tube 11 after doping is completed, hooking the pull ring 22 to take out the carrier box 2 from the furnace tube. The operation is simple, time-saving and labor-saving.

[0041] The present application further proposes that on the side of the carrier box 2 facing the gas inlet end of the furnace tube 11, the upper part is closed and the lower part is provided with an opening. When the gas flows in from the gas inlet end of the furnace tube 11, the gas mainly enters the internal space of the carrier box 2 through the opening in the lower part of the carrier box 2, accelerates the sublimation of the easily sublimable substance 8, and blows the sublimated gas molecules towards the substance to be doped 9. After impacting the end of the carrier box 2 (the side opposite to the side with the opening), the gas swirling in the internal space of the carrier box 2 flows back towards the side with the opening 21. Blocked by the upper closed structure, it cannot directly flow out upwards, increasing the turbulence, which is beneficial for the carrier gas to fully contact and repeatedly contact the experimental raw materials placed inside the carrier box 2, and increases the contact time between the carrier gas flow and the experimental raw materials. This gas flow mode forms a vortex gas flow similar to that of a whistle inside the carrier box 2, strengthening the gas disturbance and further improving the mixing degree of the gas and the experimental raw materials.

[0042] If the opening 21 is too small, it is not easy to orderly put in and take out the two experimental raw materials. If the opening 21 is too large, the effect of increasing the turbulence is not obvious. The present application further proposes that on the side of the carrier box facing the gas inlet end of the furnace tube, the ratio of the closed area to the opening area is 1:1 to 2:3, which can balance the gas circulation and reflux effects, ensure that the gas enters the carrier box at an appropriate flow rate, and form a certain gas reflux through the closed part. Thereby, the residence time of the gas in the carrier box is prolonged, and finally the doping effect is improved. And at the experimental operation level, such an opening ratio also makes it easy to first put in the substance to be doped and then the easily sublimable substance before the experiment, and it is easy to first scrape off the excess easily sublimable substance and then take out the doped substance after the experiment.

[0043] The present application further proposes that the carrier box 2 is a cuboid. After the carrier box 2 is taken out from the furnace tube 11, the regular shape of the cuboid enables the carrier box to be placed stably on the experimental table, avoiding tipping or rolling caused by an irregular shape and ensuring the safety of the experimental materials.

[0044] Refer to Figure 4 and Figure 6, on the basis that the storage box 2 is a cuboid, the present application further proposes that four faces of the storage box 2 facing the inner wall of the furnace tube 11 (a cuboid has 6 faces, excluding 1 face facing the gas inlet end of the furnace tube and 1 face facing the gas outlet end of the furnace tube, leaving 4 faces), and rounded corners are provided at the intersections of the faces. When the storage box moves in the furnace tube, the rounded corner surfaces replace the sharp edges, which can avoid scratching the inner wall of the furnace tube by the sharp edges.

[0045] The present application further proposes that on the radial cross-section of the furnace tube 11, the diagonal of the storage box 2 is less than three-quarters of the diameter of the furnace tube 11, which avoids the problem that the cuboid storage box 2 is not easy to operate due to its too large size, and also forms a sufficiently wide gap between the storage box and the inner wall of the furnace tube, and this gap is conducive to the smooth flow of the gas inside the furnace tube 11.

[0046] The present application further proposes that the outer bottom surface of the storage box is connected with support feet 23, and a smooth part 231 is provided at the lower end of the support feet 23. The smooth part 231 can be set to a spherical shape, or in the shape as shown in Figure 5 and Figure 6 . The support feet 23 are used to lift the storage box body so that the storage box 2 is located as much as possible in the center of the furnace tube 11. The smooth part 231 is used to avoid damaging the inner wall of the furnace tube by the edges or sharp parts of the support feet.

[0047] If the storage box 2 is only a cuboid with rounded corners, the storage box 2 is prone to tilt when it is in the furnace tube 11. Most of the experimental raw materials are granular, and the tilt of the storage box 2 will cause the experimental raw materials to deviate from the original position where the experimenter put them, for example, they are piled up on an edge, reducing the exposed surface area; even the sublimable substances and the substances to be doped are piled up together. If a counterweight is arranged at the bottom of such a storage box 2, it is not easy to place the storage box 2 stably when it is taken out of the furnace tube 11 and placed on the experimental table.

[0048] Based on the embodiment with support feet 23, it is further proposed that a counterweight 24 is arranged at the center of the outer bottom surface of the storage box, and the bottom end of the counterweight 24 is higher than the bottom end of the smooth part 231. When the storage box 2 is taken out of the furnace tube 11 and placed on the experimental table, the smooth part 231 at the bottom end of the support feet 23 can stand on the table to ensure the stable placement of the storage box; when the storage box 2 is put into the furnace tube 11, the existence of the counterweight 24 can lower the overall center of gravity of the storage box 2, improve the stability of the storage box, and make the storage box not easy to tilt during the moving process.

[0049] The gas reflux sleeve structure of the tubular furnace of the present application is simple, low in cost, easy to promote and use, provides a semi-open space for the experimental raw materials, enables the volatile substances to form local turbulence in this space, and enhances the doping effect.

[0050] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "certain embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc., mean that the specific features, structures, materials, or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present utility model. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0051] The above are the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present utility model, several improvements and refinements can still be made, and these improvements and refinements are also regarded as the protection scope of the present utility model.

Claims

1. A gas return sleeve for a tubular furnace, comprising a furnace tube (11), characterized in that: A material carrier box (2) is movably arranged in the furnace tube (11); an opening (21) is arranged on a side of the material carrier box (2) facing the air inlet end of the furnace tube (11); the rest of the directions of the material carrier box (2) are closed to form a space for placing experimental raw materials; and on any radial cross section of the furnace tube (11), the inner contour of the furnace tube (11) is larger than the outer contour of the material carrier box (2).

2. The gas reflux sleeve of a tubular furnace according to claim 1, characterized in that: The length of the longest side of the object carrying box (2) is smaller than the length of the heating temperature zone (12) of the furnace tube (11).

3. The gas reflux sleeve of a tubular furnace according to claim 1, characterized in that: A pull ring (22) is provided on one side of the object carrying box (2) facing the gas outlet end of the furnace tube (11).

4. The gas reflux sleeve of a tubular furnace according to claim 1, characterized in that: On one side of the object carrying box (2) facing the air inlet end of the furnace tube (11), the upper portion is closed and the lower portion is provided with the opening (21).

5. The gas reflux sleeve for a tubular furnace according to claim 4, characterized in that: On a side of the object carrying box (2) facing the air inlet end of the furnace tube (11), the ratio of the closed area to the open area is 1:1 to 2:

3.

6. The gas reflux sleeve of a tubular furnace according to claim 1, characterized in that: The object carrying box (2) is a rectangular parallelepiped.

7. The gas reflux sleeve of a tubular furnace according to claim 6, characterized in that: The four surfaces of the object carrying box (2) facing the inner wall of the furnace tube (11) are provided with rounded corners at the intersections of the four surfaces.

8. The gas reflux sleeve of a tubular furnace according to claim 6, characterized in that: On a radial cross section of the furnace tube (11), a diagonal line of the object carrying box (2) is smaller than three quarters of the diameter of the furnace tube (11).

9. The gas reflux sleeve for a tubular furnace according to claim 8, characterized in that: The outer bottom surface of the object carrying box (2) is connected to a supporting foot (23), and a smooth portion (231) is provided at the lower end of the supporting foot (23).

10. The gas reflux sleeve of a tubular furnace according to claim 9, characterized in that: A counterweight block (24) is arranged at the centre of the outer bottom surface of the object carrying box (2), and the bottom end of the counterweight block (24) is higher than the bottom end of the smooth portion (231).

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