Single crystal furnace with telescopic heat preservation structure

Abstract

The utility model relates to monocrystal silicon production equipment field discloses a single crystal furnace with telescopic heat preservation structure, including single crystal furnace body, the crucible of setting in the furnace body, set up in the heat preservation structure of furnace bottom area and the connecting piece of connecting crucible and heat preservation structure, when the position of crucible rises, heat preservation structure is synchronous to the upper pull -up and stretches from the contraction state to the unfolded state through connecting piece, and the bottom distance of heat preservation structure keeps a predetermined distance from furnace bottom. Heat preservation structure is multilayer graphite solid felt, and is connected through connecting rope and the upper along support part of support bar. The utility model solves the problem that the existing single crystal furnace bottom heat preservation layer is not fixed and leads to the problem that energy loss area expands, through the synchronous lifting of telescopic heat preservation structure, keeps energy loss area constant, effectively improves heat field stability, reduces single crystal furnace power consumption, avoids the security risk that leads to because bottom temperature is too low, simultaneously does not influence the existing crystal pulling technological process.

Description

Technical Field

[0001] This utility model relates to the technical field of monocrystalline silicon production equipment, and in particular to a monocrystalline furnace with a retractable heat preservation structure. Background Technology

[0002] With the rapid development of the photovoltaic market, reducing non-silicon costs has become a crucial issue to be addressed. In the production of monocrystalline silicon rods for solar photovoltaic applications, the monocrystalline furnace is a key piece of equipment. It uses heaters such as graphite heaters to heat and melt solid polycrystalline silicon raw materials, which are then recrystallized to form monocrystalline silicon rods. Because the monocrystalline growth process requires continuous heating of the molten silicon, it consumes a significant amount of electrical energy.

[0003] The existing bottom insulation structure of single crystal furnaces is a fixed design and cannot be moved. During the growth of single crystal silicon rods, the crucible position rises as the rods grow. As the crucible position rises, the space at the bottom of the furnace gradually increases, leading to a larger energy loss area. This results in increased heat loss and changes in the overall temperature field, negatively impacting the stability of crystal pulling.

[0004] As the crucible rises during crystal pulling, the bottom insulation performance gradually deteriorates. To ensure the overall temperature field remains unchanged and maintain the stability of the crystal growth interface, the single crystal furnace needs to compensate for temperature based on the length of the single crystal silicon rod. During the temperature compensation process, the stability of temperature compensation is poor, and the amount of compensation cannot be precisely controlled. Too much or too little compensation will cause the single crystal silicon rod to break, seriously affecting production capacity.

[0005] To address the issue of deteriorating bottom insulation during operation, existing single-crystal furnaces typically increase the temperature gradually during the constant-diameter process. As the power increases, so does the electricity cost. According to average field data, the minimum power for constant-diameter operation is 55kW, but the furnace power has increased to 57kW before completion, representing an average increase of 2kW. This cost increase leads to a decrease in the overall profitability of the single-crystal furnace.

[0006] In addition, poor bottom insulation performance can lead to excessively low bottom temperature in the single crystal furnace, which may cause silicon liquid to crystallize inside the quartz crucible, resulting in safety accidents such as silicon leakage or rod drop, seriously affecting production safety and stable equipment operation. Utility Model Content

[0007] The purpose of this invention is to provide a single crystal furnace with a retractable heat preservation structure to solve the problems of increased energy loss area, unstable thermal field and increased power consumption caused by the fixed bottom heat preservation of the single crystal furnace in the prior art.

[0008] To solve the above-mentioned technical problems, this utility model provides a single crystal furnace with a retractable heat-insulating structure, comprising:

[0009] The single crystal furnace body has a furnace bottom;

[0010] A crucible is disposed inside the furnace body;

[0011] A heat insulation structure is provided in the furnace bottom area;

[0012] Connector, connecting the crucible to the insulation structure;

[0013] When the crucible rises, the insulation structure is simultaneously pulled upwards through the connector and extends from a contracted state to an unfolded state, with the bottom of the insulation structure maintaining a predetermined distance from the furnace bottom.

[0014] Optionally, a support mechanism may also be included, through which the crucible is connected to the connector.

[0015] Optionally, the support mechanism includes a support rod and a crucible support, the support rod supporting the crucible support and the crucible support supporting the crucible.

[0016] Optionally, the support rod is provided with a support upper edge portion, and the connector is connected to the support upper edge portion.

[0017] Optionally, the diameter of the support portion along the upper edge of the support rod is 0-10 mm larger than the outer diameter of the crucible.

[0018] Optionally, the insulation structure is provided with guide holes, and the support mechanism passes through the guide holes.

[0019] Optionally, the insulation structure is a multi-layer graphite felt.

[0020] Optionally, the graphite felt has 4-6 layers, and the thickness of each layer of graphite felt is 35-50mm.

[0021] Optionally, the connector is a connecting rope, the length of which is 150-200mm; the number of connecting ropes on each layer of the insulation structure is 4-8.

[0022] Compared with the prior art, the present invention has at least the following technical effects:

[0023] By setting up a retractable insulation structure, when the crucible position rises, the insulation structure can be pulled up synchronously and extended from the contracted state to the unfolded state, maintaining a predetermined distance between the bottom of the insulation structure and the furnace bottom. This effectively controls the size of the energy loss area, solves the problem of the expansion of the energy loss area caused by the fixed bottom insulation of existing single crystal furnaces, significantly improves the thermal stability, reduces the power consumption of single crystal furnaces, and avoids safety hazards such as silicon liquid crystallization, silicon leakage, or rod drop caused by excessively low bottom temperature.

[0024] Furthermore, by employing multi-layer graphite felt as the insulation structure and connecting it to the support mechanism via connecting ropes, not only is the reliability of the insulation effect guaranteed, but the entire device structure is also simple and easy to maintain. The optimized design of the support rod along the diameter of the support section ensures the stability of the connection, while the guide holes improve the alignment and thermal stability of the entire system. This technical solution does not interfere with existing crystal pulling processes, requires no separate operation during operation, and has good process compatibility and practicality. Attached Figure Description

[0025] Figure 1a This is a schematic diagram of the crucible position rising process in the hot zone crystal pulling process of the prior art;

[0026] Figure 1b This is a schematic diagram of the crucible position rising process in the hot zone crystal pulling process of the prior art;

[0027] Figure 1c This diagram illustrates the crucible position rising process during the hot zone crystal pulling process in existing technologies. Figure 3 ;

[0028] Figure 2a A schematic diagram of the energy loss region generated during the hot zone crystal pulling process in the prior art;

[0029] Figure 2b Schematic diagram 2 shows the energy loss area generated during the hot zone crystal pulling process in the prior art;

[0030] Figure 3 This is a schematic diagram of the structure of a single crystal furnace with a retractable heat preservation structure according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the thermal insulation structure in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the support rod in an embodiment of the present utility model.

[0033] In the diagram: 100, energy loss area; 101, insulation structure; 102, connector; 1021, connection point; 103, guide hole; 104, support rod; 105, crucible liner; 106, crucible support; 107, upper support of the support rod. Detailed Implementation

[0034] The following description, with reference to schematic diagrams, illustrates a single-crystal furnace with a retractable heat-insulating structure according to the present invention. Preferred embodiments of the present invention are shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the present invention.

[0035] Based on the teachings of this specification, those skilled in the art can form new technical solutions through cross-combination of different implementation methods without creating technical contradictions. Such variations should all be considered to fall within the protection scope of this utility model.

[0036] The present invention will be described in more detail below by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0037] Please refer to Figures 1a-1c and Figures 2a-2b The existing bottom insulation structure of single crystal furnaces is a fixed design. As the crucible rises during the crystal pulling process, the bottom space gradually increases, meaning the energy loss area 100 gradually increases, leading to increased heat loss. This requires increasing the heating power to compensate, resulting in increased energy consumption. This invention uses a retractable insulation structure 101 to effectively control the size of the energy loss area 100, reducing heat loss and thus lowering power consumption.

[0038] This utility model embodiment provides a single crystal furnace with a retractable heat-insulating structure. Please refer to [reference needed]. Figure 3 - Figure 5 It includes a single crystal furnace body (not shown in the figure), a crucible, a heat insulation structure 101, and a connector 102.

[0039] The single-crystal furnace has a furnace bottom, providing a sealed, high-temperature environment for the growth of single-crystal silicon rods. The crucible is placed inside the furnace to hold polycrystalline silicon raw materials and form molten silicon during the heating process.

[0040] The crucible is usually made of quartz, which can withstand high temperatures and has good chemical stability. This is a common practice among those skilled in the art and will not be elaborated further.

[0041] The heat insulation structure 101 is installed in the furnace bottom area to provide heat insulation and prevent heat loss.

[0042] The connector 102 connects the crucible to the insulation structure 101.

[0043] When the crucible rises, the insulation structure 101 is simultaneously pulled upwards via the connector 102, extending from a contracted state to an unfolded state, while the bottom of the insulation structure 101 maintains a predetermined distance from the furnace bottom. This synchronous lifting mechanism solves the problem of increased energy loss area 100 caused by the fixed bottom insulation in existing technologies. By maintaining the fixed connection between both ends of the insulation structure 101 and the crucible and furnace bottom, the stability of the thermal field is effectively maintained.

[0044] In this embodiment, the predetermined distance is controlled within the range of 50-100mm, which ensures both good heat preservation and safe operation and easy maintenance of the equipment. In practical applications, this distance can be adjusted appropriately according to the specific model and power of the single crystal furnace.

[0045] Furthermore, in this embodiment, the thermal insulation structure 101 is a multi-layer graphite felt. Graphite felt has excellent thermal insulation performance and high-temperature resistance, improving thermal energy utilization efficiency.

[0046] Specifically, the connector 102 is a flexible connector.

[0047] In one specific example, the connector 102 is a connecting rope, one end of which is connected to the support structure of the crucible, and the other end is connected to the graphite felt.

[0048] Figure 4 The connection point 1021 between the connector 102 and the insulation structure 101 is schematically marked in the diagram.

[0049] In one specific example, one end of the connecting rope is connected to the upper support part 107 of the support rod by binding or punching, and the other end is connected to the graphite felt by a reserved hole or binding point.

[0050] Furthermore, it also includes a support mechanism, through which the crucible is connected to the connector 102.

[0051] Specifically, the support mechanism includes a support rod 104 and a crucible support 106. The support rod 104 is a vertically arranged support rod, with its lower end connected to the lower shaft of the furnace platform and its upper end supporting the crucible support 106. The support rod 104 bears the weight of the crucible and the molten silicon inside. The crucible support 106 is located at the upper end of the support rod 104 and is used to support the crucible and maintain its shape stability. In a specific example, the crucible support 106 and the upper end of the support rod 104 are fixedly connected by welding to form an integrated support structure. The fit between the crucible support 106 and the crucible is a common practice among those skilled in the art and will not be described in detail.

[0052] Please continue to refer to this. Figure 5 The support rod 104 is provided with a support rod upper edge support part 107, and the connector 102 is connected to the support rod upper edge support part 107.

[0053] The upper support portion 107 of the support rod is an enlarged portion of the upper end of the support rod 104, providing a fixing point for the connector 102, so that the connector 102 can reliably transmit the lifting and lowering movement of the support rod 104.

[0054] In one specific example, the diameter of the support portion 107 along the upper edge of the bracket is 0-10 mm larger than the outer diameter of the flange 105. This provides an appropriate installation allowance for easy assembly and maintenance. This dimensional design ensures both the reliability of the connection and avoids structural instability caused by excessive diameter differences.

[0055] The insulation structure 101 is provided with a guide hole 103, through which the support mechanism passes. The guide hole 103 enables the positioning and guiding function of the graphite felt, ensuring that the graphite felt maintains the correct position during lifting and lowering, while improving the centering of the thermal field and maintaining its stability. The diameter of the guide hole 103 is slightly larger than the diameter of the support rod 104, which achieves the guiding function without excessively restricting the movement of the graphite felt.

[0056] The graphite felt consists of 4-6 layers, with each layer having a thickness of 35-50 mm. In a specific example, 5 layers of graphite felt are used, each with a thickness of 40 mm, for a total thickness of 200 mm. This ensures good insulation while avoiding material waste and structural complexity caused by excessive thickness.

[0057] The number of layers can be adjusted according to the specific furnace type and process requirements: a 4-layer design is suitable for smaller single-crystal furnaces; a 6-layer design is suitable for large single-crystal furnaces, providing better insulation. The thickness of each graphite felt layer can be selected within the range of 35-50mm. A thickness of 35mm is suitable for applications with relatively low insulation requirements, while a thickness of 50mm is suitable for high-power single-crystal furnaces with high insulation requirements.

[0058] The connector 102 is a connecting rope, and the length of the connecting rope is 150-200mm. The length of the connecting rope directly affects the lifting range and insulation effect of the graphite felt. When the connecting rope length is 150mm, it is suitable for applications with a small lifting range; when the connecting rope length is 200mm, it can adapt to a larger lifting range and provide better adaptability.

[0059] The number of connecting ropes on each layer of the insulation structure 101 is 4-8. The distribution of the number of connecting ropes affects the stability and stress uniformity of the graphite felt. When using 4 connecting ropes, the connecting ropes are evenly distributed along the circumference at an angle of 90°; when using 8 connecting ropes, the angle between the connecting ropes is 45°, which can provide a more uniform stress distribution and better stability.

[0060] In a specific example, the connecting rope is made of high-temperature resistant carbon fiber or graphite fiber material, which has good tensile strength and high-temperature resistance, and can work stably for a long time in the high-temperature environment of the single crystal furnace.

[0061] When the crucible is at its lower limit position, the connecting rope is in a relatively contracted state, and the layers of graphite felt are superimposed on each other.

[0062] When the crucible is at its upper limit position, the connecting rope is fully extended, and a certain gap is formed between the layers of graphite felt, with the overall insulation structure 101 in an extended state. This design ensures that the energy loss area 100 is effectively controlled to remain constant throughout the crystal pulling process, avoiding increased heat loss and thermal instability caused by the expansion of the energy loss area 100.

[0063] In the crystal pulling process provided in this embodiment, as the single crystal silicon rod grows, the crucible position gradually rises, and the support part 107 along the upper edge of the support rod drives the connecting rope and graphite felt to rise synchronously.

[0064] The specific working principle is as follows: When the crucible rises, the support rod 104 pulls the connecting rope through the support part 107 along the upper edge of the support rod. The connecting rope further drives the graphite felt to move upward. In the initial state, multiple layers of graphite felt are stacked in the furnace bottom area. As the crucible rises, the connecting rope drives the multiple layers of graphite felt to rise synchronously and gradually unfold, keeping the energy loss area 100 constant, thereby stabilizing the thermal field.

[0065] In a specific example, the single crystal furnace of this invention can maintain a low furnace power level during the crystal pulling process, which can save 2-3kW of power consumption compared with the prior art. According to industrial electricity costs, it can save hundreds of yuan per furnace, which has significant economic benefits.

[0066] In summary, this embodiment solves the problem of heat loss caused by changes in the bottom space of the single crystal furnace through the design of the expandable insulation structure 101, improves the stability of the thermal field, reduces the power consumption of the single crystal furnace, achieves continuous stability of the thermal field, effectively reduces the power consumption of the single crystal furnace, improves the stability of the crystal pulling process, and avoids safety hazards such as silicon liquid crystallization, silicon leakage, or rod drop caused by excessively low bottom temperature. It significantly improves the safety and economy of single crystal silicon rod production. Furthermore, through the optimized design of the number and thickness of graphite felt layers and the specifications of connecting ropes, it not only ensures good insulation effect but also facilitates manufacturing and maintenance, thereby reducing production costs.

[0067] Example 2

[0068] This embodiment relates to a method for growing single-crystal silicon rods based on the single-crystal furnace provided in Embodiment 1. The method includes the following steps:

[0069] S1: The polycrystalline silicon raw material is loaded into the crucible, and the crucible is supported at the lower limit position inside the single crystal furnace by the crucible support 106 and the support rod 104.

[0070] At this time, the thermal insulation structure 101 is in a contracted state, and the layers of graphite felt overlap each other.

[0071] S2: The heating system is activated to heat and melt the polycrystalline silicon raw material, forming molten silicon. During the heating process, the retractable insulation structure 101 provides good bottom insulation, reducing heat loss.

[0072] S3: Immerse the seed crystal in the molten silicon to begin the growth process of the single crystal silicon rod.

[0073] During this stage, the crucible position remains relatively stable, and the insulation structure 101 remains in a contracted state.

[0074] S4: As the single-crystal silicon rod gradually grows, the support rod 104 is driven upward by the lower shaft of the furnace platform, and the position of the crucible rises accordingly. During the rise of the crucible, the upper support part 107 of the support rod drives the graphite felt to rise synchronously through the connecting rope.

[0075] S5: During the entire crystal pulling process, the insulation structure 101 gradually extends from a contracted state to an unfolded state, the thickness of the insulation layer gradually increases, and the space from the lower edge of the insulation structure 101 to the bottom of the furnace remains constant.

[0076] S6: After completing the growth of the single crystal silicon rod, gradually reduce the temperature to complete the crystal pulling process.

[0077] In this embodiment, the synchronous lifting and lowering of the heat insulation structure 101 eliminates the influence of the change in the energy loss area 100 during the crystal pulling process on the thermal stability, avoiding the problem of needing to increase the heating power to compensate for the heat loss at the bottom in the traditional process.

[0078] In a specific example, using this method to grow a single crystal silicon rod with a diameter of 200 mm and a length of 2000 mm, the power fluctuation range of the furnace during the entire crystal pulling process is controlled within ±1 kW, which is a significant improvement compared to the power fluctuation range of ±3 kW of the traditional method, and the crystal pulling success rate is increased by 15% to 20%.

[0079] The single-crystal silicon rod growth method provided in this embodiment leverages the structural advantages of a single-crystal furnace with a stretchable heat-insulating structure. Through the application of the stretchable heat-insulating structure, the thermal field is kept stable during the crystal pulling process, effectively reducing power consumption, increasing the success rate of crystal pulling, reducing the occurrence of defects such as broken edges, and significantly improving the production efficiency and product quality of single-crystal silicon rods.

[0080] In summary, this invention solves the technical problem of increased energy loss area caused by fixed insulation at the bottom of the single crystal furnace by adding a retractable insulation structure to the furnace bottom area. It achieves a significant improvement in thermal stability and an effective reduction in power consumption, providing important technical support for the efficient and stable production of single crystal silicon rods.

[0081] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this utility model and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A single-crystal furnace with a retractable heat-insulating structure, characterized in that: include The single crystal furnace body has a furnace bottom; A crucible is disposed inside the furnace body; A heat insulation structure is provided in the furnace bottom area; Connector, connecting the crucible to the insulation structure; When the position of the crucible rises, the heat-insulating structure is simultaneously pulled upward through the connector and extends from a contracted state to an unfolded state, with the bottom of the heat-insulating structure maintaining a predetermined distance from the furnace bottom.

2. The single crystal furnace with a retractable heat-insulating structure according to claim 1, characterized in that: It also includes a support mechanism, through which the crucible is connected to the connector.

3. The single crystal furnace with a retractable heat-insulating structure according to claim 2, characterized in that: The support mechanism includes a support rod and a crucible support, the support rod supporting the crucible support, and the crucible support supporting the crucible.

4. The single crystal furnace with a retractable heat-insulating structure according to claim 3, characterized in that: The support rod is provided with an upper support portion, and the connector is connected to the upper support portion.

5. The single crystal furnace with a retractable heat-insulating structure according to claim 4, characterized in that: The diameter of the support portion along the upper edge of the support rod is 0-10 mm larger than the outer diameter of the crucible.

6. The single crystal furnace with a retractable heat-insulating structure according to any one of claims 2-5, characterized in that: The insulation structure is provided with guide holes, and the support mechanism passes through the guide holes.

7. The single crystal furnace with a retractable heat-insulating structure according to claim 1, characterized in that: The insulation structure is a multi-layer graphite felt.

8. The single crystal furnace with a retractable heat-insulating structure according to claim 7, characterized in that: The graphite felt has 4-6 layers, and the thickness of each layer is 35-50mm.

9. The single crystal furnace with a retractable heat-insulating structure according to claim 1, characterized in that: The connector is a connecting rope, and the length of the connecting rope is 150-200mm; the number of connecting ropes on each layer of the insulation structure is 4-8.

Images