Thermal insulation cylinder for consumption reduction of single crystal furnace

Abstract

The utility model provides a thermal insulation cylinder for consumption reduction of a single crystal furnace, which comprises a thermal insulation cylinder, an annular cavity is arranged in the thermal insulation cylinder, the central axis of the annular cavity is the same as that of the thermal insulation cylinder, and the annular cavity is filled with gas. The annular cavity is formed in the heat preservation cylinder and filled with the gas, the filled gas replaces traditional graphite soft felt to serve as a heat preservation material, the heat preservation effect is better, pulverization is avoided, and the service life is longer; the heat preservation cylinder is provided with the annular cavity which is of a hollow structure, so that the weight of the heat preservation cylinder is reduced, the heat preservation cylinder is more convenient to disassemble and assemble, and the working efficiency is improved; the thermal insulation cylinder is mainly made of carbon / carbon composite materials, so that the thermal shock resistance of the thermal insulation cylinder is better.

Description

Technical Field

[0001] The utility model relates to the field of single crystal furnace equipment, in particular to a heat preservation cylinder used for reducing consumption of a single crystal furnace. Background Art

[0002] The thermal system of the CZ single crystal furnace consists of a heater, a heat preservation tube, a graphite electrode, a graphite support bowl, and a graphite support rod. In the single crystal furnace, the heat preservation tube constitutes the heat preservation system of the thermal field, and its function is to reduce heat loss.

[0003] At present, the insulation cylinder used by single crystal factories on the market is mainly made of cured felt, and the outer layer is wrapped with graphite soft felt, which has a heat preservation effect. For example, the existing patent document CN102808222A discloses a sleeve-type single crystal furnace insulation cylinder with different density layers. The insulation cylinder is composed of at least two concentric cylinders with different diameters. The cylinders are mutually fitted to form the insulation cylinder as a whole. The inner cylinder is made of soft carbon felt bonded and cured by a binder, and flexible graphite paper is pasted on the inner and outer surfaces. The outer cylinder is made of soft carbon felt bonded and cured by a binder, and then carbonized, and coated on the inner and outer surfaces.

[0004] Carbon felt refers to polyacrylonitrile-based carbon felt, which is divided into soft carbon felt and hard carbon felt (also called cured felt, soft carbon felt is cured after adding glue). According to the different temperatures in the production process of carbon felt, it is divided into carbon felt (generally treated at a temperature of more than 900 degrees in China) and graphite felt (generally treated at a temperature of about 1700 degrees in China). During the operation of a single crystal furnace, the maximum temperature in the furnace can reach about 1950°C, and the cured felt will have problems of felt powdering and reduced thermal insulation performance.

[0005] At the same time, during the high-temperature operation of the single crystal furnace, the graphite soft felt also has the following defects: (1) The graphite soft felt will be powdered during operation, and the thermal insulation performance will be reduced, resulting in an increase in the power of the single crystal furnace; (2) After the graphite soft felt is powdered during operation, the thermal insulation performance of each position of the insulation tube changes, resulting in changes in the thermal field gradient of the entire thermal field, affecting production; (3) The graphite soft felt needs to be replaced after running for a period of time, which is relatively costly; (4) The thermal conductivity of the currently used graphite soft felt is large and its thermal insulation performance is poor. Utility Model Content

[0006] In view of the deficiencies in the prior art, the utility model aims to provide an insulation cylinder for reducing energy consumption in a single crystal furnace, which solves the problem that during the high-temperature operation of the single crystal furnace, the traditional insulation cylinder is prone to felt differentiation, resulting in reduced insulation performance, increased energy consumption and reduced output of the single crystal furnace.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] A heat preservation tube for reducing consumption of a single crystal furnace, the heat preservation tube is a sleeve, an annular cavity is arranged inside the heat preservation tube, the central axis of the annular cavity is the same as the central axis of the heat preservation tube, and the annular cavity is filled with gas. Two layers of annular cavities are arranged inside the heat preservation tube, namely a first annular cavity and a second annular cavity, the central axes of the first annular cavity and the second annular cavity are respectively the same as the central axis of the heat preservation tube, the first annular cavity is located on a side close to the central axis, and the second annular cavity is located on a side away from the central axis.

[0009] Furthermore, the gas is argon.

[0010] Further, the thickness of the first annular cavity is greater than the thickness of the second annular cavity.

[0011] Furthermore, the ratio of the thickness of the first annular cavity to the thickness of the second annular cavity is 1:4.

[0012] Furthermore, the insulation cylinder includes an inner wall, an outer wall, a middle partition wall, an upper cover plate and a lower cover plate, the upper cover plate and the lower cover plate are both annular cover plates, the space enclosed by the inner wall, the middle partition wall, the upper cover plate and the lower cover plate is a first annular cavity, and the space enclosed by the outer wall, the middle partition wall, the upper cover plate and the lower cover plate is a second annular cavity.

[0013] Furthermore, gaps are retained when the upper cover plate and the lower cover plate are spliced ​​with the inner wall, the outer wall, and the middle partition wall.

[0014] Furthermore, the thickness of the middle partition wall is greater than that of the outer wall and the inner wall.

[0015] Furthermore, the materials of the inner wall, the outer wall, the middle partition wall, the upper cover plate and the lower cover plate are all carbon / carbon composite materials.

[0016] The beneficial effects of the utility model are:

[0017] (1) The utility model provides an annular cavity in the heat preservation tube and provides a filling gas, so that the filling gas replaces the traditional graphite soft felt as the heat preservation material, the heat preservation effect is better, the felt will not be powdered, and the service life is longer.

[0018] (2) The heat preservation tube of the utility model is provided with an annular cavity and is a hollow structure, which reduces the weight of the heat preservation tube, makes disassembly and assembly more convenient, and improves work efficiency.

[0019] (3) The thermal insulation tube of the utility model is mainly made of carbon / carbon composite material, which makes the thermal insulation tube have better thermal shock resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0021] Figure 1 This is a schematic diagram of the structure of a heat preservation tube for reducing consumption in a single crystal furnace according to the utility model;

[0022] Figure 2 This is a cross-sectional view of a heat preservation tube for reducing consumption in a single crystal furnace according to the utility model;

[0023] Figure 3 This is a schematic diagram of the internal structure of a heat preservation cylinder for reducing consumption in a single crystal furnace according to the utility model;

[0024] Figure 4 This is a graph showing the relationship between air thickness and thermal insulation.

[0025] Figure numerals: 1, insulation cylinder; 2, first annular cavity; 3, second annular cavity; 4, inner wall; 5, middle partition wall; 6, outer wall; 7, upper cover plate; 8, lower cover plate. DETAILED DESCRIPTION

[0026] The following is a further detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0027] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] In the description of the present utility model, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0029] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0030] Embodiment 1:

[0031] This embodiment provides a heat preservation tube for reducing consumption of a single crystal furnace, such as Figure 1-Figure 2As shown, the heat preservation tube 1 is a sleeve, and an annular cavity is arranged inside the heat preservation tube 1 , and the annular cavity is filled with gas. The central axis of the annular cavity is the same as the central axis of the heat preservation tube 1 .

[0032] In a single crystal furnace, the heat transfer method consists of heat conduction, heat convection and heat radiation. The main way for the insulation tube to lose heat is heat conduction, which relies on molecular motion to transfer heat. The form of molecular motion is related to the molecular state inside the object. Inside the solid, heat conduction is caused by the collision of adjacent molecules, which transfers vibration energy. In the gas, heat conduction is carried out by transferring kinetic energy through the irregular thermal motion of molecules. Due to the large distance between gases, the heat transfer of gases by heat conduction is very limited. Therefore, the thermal conductivity of gases is worse than that of solids.

[0033] The technical effects of the first embodiment are as follows: (1) The traditional graphite soft felt is replaced by filling gas as the insulation material. Since the heat conductivity of gas is worse than that of graphite soft felt, this embodiment provides an annular cavity in the insulation tube 1 and fills gas. The insulation effect of this embodiment is better, it will not be powdered, and the service life is longer. (2) The traditional insulation tube is heavy, inconvenient to disassemble and assemble, and affects work efficiency. The insulation tube 1 of this embodiment is provided with an annular cavity and is a hollow structure, which reduces the weight of the insulation tube, makes disassembly and assembly more convenient, and improves work efficiency.

[0034] Embodiment 2:

[0035] This embodiment provides a heat preservation tube for reducing consumption of a single crystal furnace. The heat preservation tube 1 is a sleeve. An annular cavity is arranged inside the heat preservation tube. The annular cavity is filled with gas, and the gas is argon.

[0036] Thermal conductivity is one of the physical properties of an object. Its physical meaning is the heat flux (W / m 2 ), so the value indicates the strength of the thermal conductivity of the material and is related to the composition, structure, density, temperature and pressure of the material. The thermal conductivity values ​​of different materials vary greatly. Generally, the thermal conductivity of metals is the largest, followed by non-metallic solids and liquids, and the thermal conductivity of gases is the smallest. The thermal conductivity of different media was tested under the environment of temperature T = 1000 ° C and pressure P = 101.325 kPa, as shown in Table 1:

[0037] Table 1 Thermal conductivity of different media

[0038]

[0039] The thermal conductivity of viscose-based felt with the best thermal insulation performance on the market is 0.15-0.20W / (m·K), while the thermal conductivity of argon gas in a single crystal furnace at 1000°C is only 0.055W / (m·K). In addition, the thermal conductivity of most gases has nothing to do with pressure, and the thermal insulation performance will not change due to changes in furnace pressure. This shows that the air layer is a good thermal insulation material. Among them, argon gas is the best thermal insulation material among the above media.

[0040] The insulation tube designed by this patent uses argon layer instead of graphite soft felt as insulation material, and no longer uses traditional graphite soft felt as insulation material. Since the thermal conductivity of argon is one tenth of that of graphite soft felt, according to the heat transfer formula Q=KAΔtm, the insulation performance of the insulation tube using argon layer as insulation material is about ten times that of graphite soft felt.

[0041] The technical effects of the second embodiment are as follows:

[0042] In this embodiment, based on the first embodiment, argon gas is filled in the annular cavity to achieve a better heat preservation effect of the heat preservation tube.

[0043] Embodiment three:

[0044] This embodiment provides an insulation cylinder for reducing consumption of a single crystal furnace, the insulation cylinder 1 is a sleeve, and two layers of annular cavities are arranged in the insulation cylinder 1, and both layers of annular cavities are filled with argon. The two layers of annular cavities are respectively a first annular cavity 2 and a second annular cavity 3, the central axes of the first annular cavity 2 and the second annular cavity 3 are respectively the same as the central axis of the insulation cylinder 1, the first annular cavity 2 is located on the side close to the inner wall 4 of the insulation cylinder, and the second annular cavity 3 is located on the side close to the outer wall 6 of the insulation cylinder, and a middle partition wall 6 is arranged between the first annular cavity 2 and the second annular cavity 3 as a spacer between the two layers of annular cavities.

[0045] The advantages of separating two layers of annular cavities in this embodiment are:

[0046] like Figure 4 As shown, when the thickness of the air layer reaches a critical value, its thermal insulation will reach a peak value. When the thickness of the air layer is greater than or less than the critical value of the air layer thickness, the thermal insulation will decrease.

[0047] After separating the two layers of annular cavities, the volume and thickness of the single-layer annular cavity are reduced, so that both layers of annular cavities are close to the critical value. Compared with the single-layer annular cavity, the thermal insulation effect is doubled, the reflected radiation heat transfer effect is better, and the thermal insulation effect of the insulation tube is better.

[0048] In this embodiment, the thickness of the first annular cavity is greater than the thickness of the second annular cavity, which has the following advantages:

[0049] Since the volume of the insulation tube is fixed, its thickness is much greater than the critical value. At the same time, in order to control costs, it is impossible to set up more annular cavities to improve the insulation effect. Therefore, it is first ensured that the thickness of the first annular cavity 2 is near the critical value. Therefore, the volume of the first annular cavity 2 is smaller than the volume of the second annular cavity 3. According to empirical values, when the ratio of the thickness of the first annular cavity 2 to the thickness of the second annular cavity 3 is 1:4, the insulation effect of the insulation tube is best. In order to reduce heat loss, the thickness of the first annular cavity 2 is set to be smaller than the thickness of the second annular cavity 3 in this embodiment. The first annular cavity 2 is located on the inner side of the insulation tube, and more heat needs to be reflected. When the thickness of the annular cavity is greater than the critical value, the smaller the thickness of the annular cavity, the more heat is reflected, and the smaller the heat loss.

[0050] In this embodiment, the thickness of the middle partition wall is greater than that of the outer wall or the inner wall, which has the following advantages:

[0051] The thickness of the outer wall 6 and the inner wall 4 of the insulation tube are the same, and the thickness of the middle partition wall 6 is greater than that of the outer wall 6 and the inner wall 4. The middle partition wall 6 needs to be reinforced by increasing the thickness to support the thermal field component, and the thickness of the middle partition wall 6 is twice that of the outer wall 6 and the inner wall 4.

[0052] The insulation tube material is carbon / carbon composite material.

[0053] The advantages of using carbon / carbon composite materials as the insulation tube material in this embodiment are:

[0054] Carbon / carbon composite materials (cc composite or carbon-carbon composite material) are carbon-based composite materials reinforced by carbon fibers and their fabrics. They have the advantages of low density (<2.0g / cm3), high strength, high specific modulus, high thermal conductivity, low expansion coefficient, good friction performance, good thermal shock resistance, and high dimensional stability. They are one of the few alternative materials used above 1650℃, and the highest theoretical temperature is as high as 2600℃. Therefore, they are considered to be one of the most promising high-temperature materials. During the operation of a single crystal furnace, the highest temperature in the furnace can reach about 1950℃. Therefore, after the insulation tube material is made of carbon / carbon composite materials, the thermal shock resistance of the insulation tube is better.

[0055] Embodiment 4:

[0056] This embodiment provides a heat preservation tube for reducing consumption of a single crystal furnace. The heat preservation tube 1 is a sleeve, and two layers of annular cavities are arranged inside the heat preservation tube, and both layers of annular cavities are filled with argon. The two layers of annular cavities are respectively a first annular cavity 2 and a second annular cavity 3. The central axes of the first annular cavity and the second annular cavity are respectively the same as the central axis of the heat preservation tube. The first annular cavity 2 is located on the side close to the inside of the heat preservation tube, and the second annular cavity 3 is located on the side close to the outer wall of the heat preservation tube. A middle partition wall 6 is arranged between the first annular cavity 2 and the second annular cavity 3 as a spacer between the two layers of annular cavities.

[0057] like Figure 3 As shown, the heat preservation cylinder includes an inner wall 4, an outer wall 6, a middle partition wall 6, an upper cover plate 7 and a lower cover plate 8. The upper cover plate 7 and the lower cover plate 8 are both annular cover plates. The space enclosed by the inner wall 4, the middle partition wall 6, the upper cover plate 7 and the lower cover plate 8 is a first annular cavity 2, and the space enclosed by the outer wall 6, the middle partition wall 6, the upper cover plate 7 and the lower cover plate 8 is a second annular cavity 3. When the upper cover plate 7 and the lower cover plate 8 are spliced ​​with the inner wall 4, the outer wall 6 and the middle partition wall 6, gaps are retained.

[0058] The gas in the single crystal furnace is argon. When it starts running, it needs to be evacuated. When evacuating, the air in the cavity will be evacuated to form a negative pressure. When the pressure increases, the argon will enter the cavity through the gap. When the evacuation process is completed, there is no strong convection in the single crystal furnace, and the argon is stable in the cavity, ensuring the heat preservation of the insulation tube.

[0059] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the utility model.

Claims

1. A heat preservation cylinder for reducing consumption of a single crystal furnace, characterized in that: The thermal insulation tube (1) is a sleeve, and an annular cavity is arranged inside the thermal insulation tube (1), the central axis of the annular cavity is the same as the central axis of the thermal insulation tube (1), and the annular cavity is filled with gas; the thermal insulation tube (1) is provided with two layers of annular cavities, namely a first annular cavity (2) and a second annular cavity (3), the central axes of the first annular cavity (2) and the second annular cavity (3) are respectively the same as the central axis of the thermal insulation tube (1), the first annular cavity (2) is located on a side close to the central axis, and the second annular cavity (3) is located on a side away from the central axis.

2. The heat preservation cylinder for reducing consumption of a single crystal furnace according to claim 1, characterized in that: The gas is argon.

3. The heat preservation cylinder for reducing consumption of a single crystal furnace according to claim 1, characterized in that: The thickness of the first annular cavity (2) is greater than the thickness of the second annular cavity (3).

4. The heat preservation cylinder for reducing consumption of a single crystal furnace according to claim 3, characterized in that: The ratio of the thickness of the first annular cavity (2) to the thickness of the second annular cavity (3) is 1:

4.

5. The heat preservation cylinder for reducing consumption of a single crystal furnace according to claim 1, characterized in that: The heat-insulating cylinder (1) comprises an inner wall (4), an outer wall (6), a middle partition wall (5), an upper cover plate (7) and a lower cover plate (8); the upper cover plate (7) and the lower cover plate (8) are both annular cover plates; the space enclosed by the inner wall (4), the middle partition wall (5), the upper cover plate (7) and the lower cover plate (8) is the first annular cavity (2); and the space enclosed by the outer wall (6), the middle partition wall (5), the upper cover plate (7) and the lower cover plate (8) is the second annular cavity (3).

6. The heat preservation cylinder for reducing consumption of a single crystal furnace according to claim 5, characterized in that: Gaps are retained when the upper cover plate (7) and the lower cover plate (8) are spliced ​​with the inner wall (4), the outer wall (6), and the middle partition wall (5).

7. The heat preservation cylinder for reducing consumption of a single crystal furnace according to claim 5, characterized in that: The thickness of the middle partition wall (5) is greater than that of the outer wall (6) and the inner wall (4).

8. The heat preservation cylinder for reducing consumption of a single crystal furnace according to claim 5, characterized in that: The materials of the inner wall (4), the outer wall (6), the middle partition wall (5), the upper cover plate (7) and the lower cover plate (8) are all carbon / carbon composite materials.

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