WO2016082525A1 - Device for moving small heat insulating plate at bottom of polycrystalline silicon ingot furnace and polycrystalline silicon ingot furnace - Google Patents

Abstract

Provided are a device for moving a small heat insulating plate at the bottom of a polycrystalline silicon ingot furnace and a polycrystalline silicon ingot furnace. The moving device comprises a small bottom heat insulating plate (2), a support rod (3), a telescopic tube (6), and a lifting device (7); the small bottom heat insulating plate (2) is fixed to the upper part of the support rod (3) using an upper nut (4) and a lower nut (16); the lower part of the support rod (3) extends to the bottom of the telescopic tube (6); the upper end of the telescopic tube (6) is connected to the furnace body, and the lower end of the telescopic tube (6) is connected to the lifting device (7); and the small bottom heat insulating plate (2) can move upward and downward under the control of the lifting device (7). The above-mentioned structure achieves: when the crystal growth begins inside the furnace, the small bottom heat insulating plate (2) moves downward to be separated from a large bottom heat insulating plate (1), which quickens the cooling of a core of a coagulation enhancement block, such that the cooling crystallization rate of a silicon melt inside a crucible can be improved, and in addition, the silicon melt forms a considerable degree of supercooling to improve the quality of the polycrystalline silicon ingot.

Description

Small heat insulation board movable device and polysilicon ingot furnace at the bottom of polycrystalline silicon ingot furnace Technical field:

The invention relates to a polycrystalline silicon ingot furnace, in particular to a small thermal insulation board movable device at the bottom of a polycrystalline silicon ingot furnace, and a polycrystalline silicon ingot furnace comprising the bottom small thermal insulation board movable device.

Background technique:

The growth of silicon crystals is generally divided into three methods: polycrystalline ingot, single crystal pulling and zone melting. With the large-scale application of crystalline silicon photovoltaic products, the solar grade crystalline wafer industry continues to mature and mature, and silicon wafers are used as The price of raw materials has gradually fallen back in rationality, and it has also caused the continuous compression of the profit margin of wafer manufacturers. Increasing the quality of silicon wafers and reducing processing costs have become a problem for all solar wafer manufacturers. The crystalline silicon photovoltaic power generation industry chain includes processes from silicon-silicon-battery-component-systems, in which silicon wafers are produced mainly by crystal growth and crystal cutting, and crystal growth is fundamental to manufacturing high-quality silicon wafers. . In crystalline silicon photovoltaic power generation, polycrystalline directional solidification has become a mainstream technology for wafer production due to its low cost and large output. However, due to its crystal defects, impurities and other factors, the conversion efficiency of polycrystalline cells is always single crystal. There is a certain gap in the battery. Improving the growth method of polycrystalline ingots has become the main direction of the current improvement of polycrystalline silicon wafers. The difference between the polycrystalline ingot and the single crystal pulling method is that the pulling growth has a seed crystal, the subsequent seeding, the equal diameter and the like are all performed based on the seed crystal, so the crystal has a certain crystal orientation, and the polycrystal Nucleation in an ingot is a process of random nucleation according to thermodynamics, and the structure of the polycrystalline ingot is different every time. Different crystal orientations of silicon materials have different ability to recombine carriers and accept impurities. Among them, the <110> and <112> twin structures of silicon are precipitated due to dense atomic arrangement and low interface energy. Less, and the carrier recombination is very weak, so the minority carrier lifetime (ie carrier lifetime) is relatively high, this part is very suitable for the base wafer of the battery.

The polycrystalline ingot is a typical melt solidification growth method: the polycrystalline silicon raw material is heated and melted into a melt at a high temperature, and then cooled by the bottom, and the crystal is grown by upward directional solidification, and the growth process is relatively slow, after the growth is completed. The crystal is annealed and cooled to normal temperature. Studies have shown that in order to form suitable silicon germanium structures of <110> and <112>, it is necessary to form a certain degree of subcooling in the process of crystal nucleation, usually between 10 and 100 K below the melting point.

At present, most polycrystalline silicon ingot furnaces have begun to upgrade the ingot volume expansion, that is, to maintain the existing polycrystalline silicon ingot furnace body structure unchanged, expand the thermal field, upgrade from the original G5 ingot to G6, G7 type ingot. G5, G6, and G7 refer to the weight of the silicon ingot, respectively. G5 means that the silicon ingot is composed of 5x5=25 small silicon blocks of the same weight. By analogy, the yield of G6 and G7 is 44% and 96% higher than that of G5, respectively. Through the transformation, the output of the ingot can be increased and the unit cost of the silicon wafer can be reduced, and the cost per watt of photovoltaic power generation can be reduced. However, due to the constant size of the furnace after the transformation, the weight of the ingot after the transformation was increased by 44% and 96% respectively. The heat dissipation capacity at the bottom of the heat field is also required to be improved accordingly, and the heat dissipation capability of the existing heat insulating cage lifting technology is only slightly increased, so that the solidification speed in the ingot casting process is greatly reduced. For example, the solidification time of the G5 ingot is about 25 hours, but the solidification time of the G6 ingot is about 40 hours, and the solidification time of the G7 ingot is longer. This invisibly increases the cost of wafer production, and at the same time, most of the silicon material is still in a high-temperature melting state during the solidification process, which also increases the risk of silicon leakage. In addition, due to the long contact time between the silicon ingot and the crucible, it also causes a certain diffusion and contamination of oxygen, resulting in a decrease in crystal quality.

At present, the bottom insulation boards of G5, G6, and G7 are all one-piece boards. When the crystals are grown, the heat at the bottom of the crucible is hard to radiate out of the heat at the edge of the crucible, causing the solid-liquid interface at the time of crystal growth to be slightly concave and dissolved. Impurities in the silicon melt will be deposited in the middle, so that the quality of the crystal grown is low, and the efficiency of the cut wafer is also low. At the same time, for the larger G6 type (about 800 kg) and the G7 type (about 1200 kg) polycrystalline ingot, the latent heat of crystallization is huge. According to the current heat dissipation method of the insulating cage, it is difficult to effectively emit the latent heat of crystallization. .

Summary of the invention:

The technical problem to be solved by the present invention is to overcome the above-mentioned defects existing in the prior art, and to provide a small thermal insulation board movable device at the bottom of a polycrystalline silicon ingot furnace, comprising a polycrystalline silicon ingot furnace having the bottom small thermal insulation plate movable device, in the long crystal In addition to the radiant heat dissipation from the edge insulation cage, it also provides a vertical radiant heat dissipation channel directly below the ,, so that not only the initial cooling of the crystal growth, but also the solid-liquid during the growth process. The interface has a beneficial micro-convex shape, and the heat dissipation capability of the coagulation block is strengthened. When the directional solidification is performed, the speed is fast and the quality of the crystal product is high.

The technical solution adopted by the invention to solve the technical problem is: a small thermal insulation board movable device at the bottom of the polycrystalline silicon ingot furnace, comprising a small thermal insulation board at the bottom, a support rod, a telescopic tube, a lifting device; the bottom portion is made with a nut and a lower nut a small insulation board is fixed on the upper part of the support rod; a lower part of the support rod extends to the bottom of the telescopic tube; an upper end of the extension tube is connected to the furnace body, and a lower end of the extension tube is connected with the lifting device; under the control of the lifting device The bottom small insulation board can move up and down along the axial direction of the support rod.

Further, the lifting device is composed of a lifting rod and a servo motor, and the lifting rod can move up and down along the servo motor, thereby driving the bottom of the upper part of the supporting rod to move under the small thermal insulation board.

Further, the lifting device can also be replaced by a C-shaped card, and a C-shaped card of a corresponding height is configured according to different lifting heights of the bottom small thermal insulation board.

Further, the telescopic tube is sealed and welded by a bellows and a quick-change joint; a sealing ring is arranged at an upper end of the telescopic tube and a furnace body, and the clamp can be sealed and fixed; the lower end of the telescopic tube is connected with the blind plate; The sealing ring can be sealed and fixed with a clamp.

Further, in order to increase the stability of the small thermal insulation board at the bottom, between the small thermal insulation board and the lower nut, Pad.

Further, the support rod is one of a molybdenum rod, a tungsten rod, a mast, a graphite rod or a carbon-carbon composite rod.

Further, the bottom small thermal insulation board has a rectangular or inverted T-shaped cross section, and the bottom large thermal insulation board has a rectangular or inverted T-shaped cross section corresponding to the matching hole.

Further, the bottom small thermal insulation board has a circular or rectangular top view, and the bottom large thermal insulation board has a circular or rectangular shape corresponding to the top view of the matching hole.

Further, the separation distance between the bottom small thermal insulation board and the bottom large thermal insulation board is 10 to 300 mm.

Further, the telescopic tube is made of a temperature resistant stainless steel, specifically 316L.

Further, the upper nut, the lower nut and the backing plate are made of a graphite material or a carbon-carbon composite material.

The method for using the small thermal insulation board movable device at the bottom of the polycrystalline silicon ingot furnace: when the silicon material is melted, the bottom small thermal insulation board and the bottom large thermal insulation board are in a closed state; when the melting is completed and enters the long crystal stage, the lifting device is started to make the bottom The small thermal insulation board is separated from the large thermal insulation board at the bottom to accelerate the growth rate of the silicon crystal; when the crystal growth enters the annealing stage, the lifting device is started to close the small thermal insulation board at the bottom and the large thermal insulation board at the bottom until the silicon ingot is cooled out.

Compared with the prior art, the invention has the following advantages:

(1) The present invention accelerates the cooling of the core of the coagulation block by providing a small thermal insulation plate movable device at the bottom of the polycrystalline silicon ingot furnace, thereby improving the heat dissipation capability of the coagulation block, thereby improving the cooling crystallization rate of the silicon melt in the crucible. Improve the efficiency of directional solidification, shorten the production cycle and reduce the production cost;

(2) Applying the movable device of the small thermal insulation board at the bottom of the polycrystalline silicon ingot furnace of the present invention can form a large degree of subcooling required for the growth of silicon twin crystal, and the quality of the polycrystalline silicon ingot will be improved.

(3) Applying the movable device of the small thermal insulation board at the bottom of the polycrystalline silicon ingot furnace of the invention, the cooling of the core of the coagulation block is increased, and the central cooling capacity of the polycrystalline silicon ingot is stronger than the edge, and a micro convex solid-liquid interface can be formed, dissolved in The impurities in the silicon melt will be deposited to the periphery, so that the crystals grown are of good quality, and the cut silicon wafers have high conversion efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS:

1 is a schematic structural view of a small thermal insulation plate movable device at the bottom of the polycrystalline silicon ingot furnace of the present invention when the silicon material is melted; FIG. 2 is FIG.

Partially enlarged view of Part A;

3 is a schematic structural view of a telescopic tube in a movable device for a small thermal insulation board at the bottom of a polycrystalline silicon ingot furnace according to the present invention;

4 is a schematic structural view of a small thermal insulation board movable device at the bottom of the polycrystalline silicon ingot furnace of the present invention;

Figure 5 is a schematic view showing the structure of the lifting device of Figure 4 replaced with a C-shaped card;

Figure 6 is a partial enlarged view of a portion B of Figure 5;

Figure 7 is a top view of the small thermal insulation board at the bottom of the rectangle in Figure 1, Figure 4 or Figure 5;

Figure 8 is a top view of the small bottom thermal insulation board of Figure 1, Figure 4 or Figure 5;

Figure 9 is a schematic view showing the inverted T-shaped cross section of the bottom small insulation board when the silicon material is melted;

Figure 10 is a schematic view showing the inverted T-shaped cross section of the bottom small thermal insulation plate when the crystal is grown;

Figure 11 is a top plan view of the rectangular bottom insulation board of Figure 9 or Figure 10;

Figure 12 is a top plan view of the circular bottom small insulation board of Figure 9 or Figure 10;

Among them: 1- bottom large insulation board, 2- bottom small insulation board, 3-support rod, 4-upper nut, 5-pad, 6-telduct, 7-lifting device, 8-lifting rod, 9-servo motor ,10-seal ring,11-clamp,12-blind plate,13-corrugated pipe,14-fast change joint,15-separation distance between small insulation board and bottom large insulation board, 16-lower nut, 17-solid Liquid interface, 18-low furnace body, 19-upper furnace, 20-C-shaped card.

detailed description

The invention will be further described below in conjunction with the examples and the accompanying drawings.

Example 1

The embodiment comprises a bottom small thermal insulation board 2, a support rod 3, a telescopic tube 6, and a lifting device 7; the bottom small thermal insulation board 2 is fixed on the upper part of the support rod 3 by the upper nut 4 and the lower nut 16; the lower part of the support rod 3 is worn The upper end of the telescopic tube 6 is connected to the furnace body, and the lower end of the telescopic tube 6 is connected to the lifting device 7; under the control of the lifting device 7, the bottom small thermal insulation board 2 can move up and down along the axial direction of the support rod 3. (As shown in Figure 1);

The lifting device 7 is composed of a lifting rod 8 and a servo motor 9. The lifting rod 8 can move up and down along the servo motor 9, thereby driving the bottom small thermal insulation board 2 on the upper part of the supporting rod 3 to move up and down.

The bellows 6 is sealed and welded by the bellows 13 and the quick-change joint 14; the upper end of the bellows 6 is connected with the furnace body with a sealing ring 10, which can be sealed and fixed by the clamp 11; the lower end of the telescopic tube 6 is connected with the blind plate 12 A sealing ring 10 is provided, which can be sealed and fixed by the clamp 11. (as shown in Figure 2 and Figure 3);

In order to increase the stability of the bottom small thermal insulation board 2, a backing plate 5 is further disposed between the bottom small thermal insulation board 2 and the lower nut 16. (as shown in Figure 1, Figure 4, Figure 5, Figure 9 and Figure 10);

The support rod 3 is a molybdenum rod.

The bottom small thermal insulation board 2 has a rectangular cross section and is also rectangular in plan view (as shown in FIG. 7), and the bottom large thermal insulation board 1 has a rectangular cross section corresponding to the matching hole.

The telescopic tube 6 is made of a temperature-resistant stainless steel, specifically 316L.

The upper nut, lower nut and backing plate are made of graphite material.

When the silicon material is melting, the bottom small thermal insulation board 2 and the bottom large thermal insulation board 1 are in a closed state (as shown in FIG. 1); when the melting is completed and enters the long crystal stage, the lifting device 7 is activated to make the bottom small thermal insulation board 2 and the bottom. Large insulation board 1 is separated and separated The distance 15 is 10mm, which accelerates the crystal growth rate of the silicon crystal; and the solid-liquid interface 17 is slightly convex (as shown in FIG. 4); when the crystal growth enters the annealing stage, the lifting device 7 is activated to make the bottom small thermal insulation board 2 The bottom large thermal insulation board 1 is in a closed state until the silicon ingot is cooled out of the furnace.

The use of the polycrystalline silicon ingot furnace bottom small thermal insulation plate movable device to produce the silicon ingot can increase the solidification rate of the silicon melt inside the crucible, thereby accelerating the growth of the ingot, increasing the ingot production, and reducing the electricity cost of the ingot. .

Taking the G5 of the GT polysilicon ingot furnace into G6 as an example, the weight of the ingot is increased from 500 kg to 800 kg. If the long crystal scheme of the insulated cage is simply adopted, the crystal growth time takes about 40 hours, and the total The process time is 75 hours; and with the small thermal insulation plate moving device of the polycrystalline silicon ingot furnace of the invention, the crystal growth time is shortened to 30 hours, and the total process time is shortened to 65 hours. Since the power is kept constant at 60-66 kW during the growth period, each ingot can save about 600-660 degrees of power consumption, and the production efficiency is increased by about 13%-15%. At the same time, the ingot yield is increased by about 1%, and 300 wafers/ingot of silicon wafers can be produced. The current polycrystalline silicon wafer is 6.5 yuan/piece, which increases the income by 1950 yuan. In addition, the average conversion efficiency of the silicon wafer is increased by 0.1%. Absolute value (conversion efficiency increased from 17.8% to 17.9%).

Example 2

The difference between the embodiment and the embodiment 1 is that the support rod 3 is a tungsten rod; the bottom small insulation board 2 has a rectangular cross section and a circular shape in plan view (as shown in FIG. 8 ), and the bottom large insulation board 1 corresponds to the matching hole. The cross section is circular; when the melting is completed into the crystal growth stage, the lifting device 7 is activated to separate the bottom small thermal insulation board 2 from the bottom large thermal insulation board 1, and the separation distance 15 is 60 mm. The same as Example 1.

Taking the G5 of the GT polysilicon ingot furnace into G6 as an example, the weight of the ingot is increased from 500 kg to 800 kg. If the long crystal scheme of the insulated cage is simply adopted, the crystal growth time takes about 40 hours, and the total The process time is 75 hours; and with the small thermal insulation board moving device of the polycrystalline silicon ingot furnace of the present invention, the crystal growth time is shortened to 29 hours, and the total process time is shortened to 64 hours. Since the power is kept constant at 60-66 kW during the growth period, each ingot can save about 660-726 degrees of power consumption, and the production efficiency is increased by about 14%-15%. At the same time, the ingot yield is increased by about 1.2%, and the wafer can be produced in a total of 360 pieces/ingot. The current polycrystalline silicon sheet is 6.5 yuan/piece, which increases the income by 2340 yuan. In addition, the average conversion efficiency of the silicon wafer is increased by 0.1%. Absolute value (conversion efficiency increased from 17.8% to 17.9%).

Example 3

The difference between this embodiment and the embodiment 1 is that the support rod 3 is a mast; the upper nut 4, the lower nut 16 and the back plate 5 are made of carbon-carbon composite material; the lifting device 7 is replaced by a C-shaped card 20, when When the melting is completed and the crystal growth stage is entered, the bottom small thermal insulation board 2 is separated from the bottom large thermal insulation board 1 by the C-shaped card 20, and the separation distance 15 is 100 mm (as shown in Figs. 5 and 6). The same as Example 1.

Taking the G5 of JYT polysilicon ingot furnace into G7 as an example, the weight of the ingot is increased from 500 kg to 1200 kg. Simply adopt the long crystal scheme of the insulated cage, the crystal growth time takes about 52 hours, and the total process time is 90 hours; and the crystal growth time of the polysilicon ingot furnace bottom small thermal insulation board movable device is adopted. Shortened to 42 hours and the total process time was reduced to 81 hours. Since the power is kept constant at about 70-75 kW during the growth period, each ingot can save about 700-750 degrees of power consumption, and the production efficiency is increased by about 10%-13%. At the same time, the ingot yield is increased by about 1%, and 450 wafers/ingot of silicon wafer can be produced. The current polycrystalline silicon wafer is 6.5 yuan/piece, which increases the income by 2,925 yuan. In addition, the average conversion efficiency of the silicon wafer is increased by 0.1%. Absolute value (conversion efficiency increased from 17.75% to 17.85%).

Example 4

The difference between this embodiment and the first embodiment is that the support rod 3 is a graphite rod; the bottom small thermal insulation board 2 has an inverted T-shaped cross section and a rectangular shape in plan view (as shown in FIG. 11), and the bottom large thermal insulation board 1 is matched. The cross section of the hole is inverted T-shaped; when the melting is completed into the crystal growth stage, the lifting device 7 is activated to separate the bottom small thermal insulation board 2 from the bottom large thermal insulation board 1, and the separation distance 15 is 180 mm. The same as Example 1.

Taking the G6 of JYT polycrystalline silicon ingot furnace into G7 as an example, the weight of the ingot is increased from 800 kg to 1200 kg. If the long crystal scheme of the insulated cage is simply adopted, the crystal growth time takes about 52 hours, and the total The process time is 92 hours; and with the small thermal insulation board moving device of the polycrystalline silicon ingot furnace of the present invention, the crystal growth time is shortened to 41 hours, and the total process time is shortened to 82 hours. Since the power is kept constant at about 70-75 kW during the growth period, each ingot can save about 770-825 degrees of power consumption, and the production efficiency is increased by about 11%-15%. At the same time, the ingot yield is increased by about 1.1%, and the wafer can be produced in a total of 500 pieces/ingot. The current polycrystalline silicon sheet is 6.5 yuan/piece, which increases the income by 3,250 yuan. In addition, the average conversion efficiency of the silicon wafer is increased by 0.1%. Absolute value (conversion efficiency increased from 17.75% to 17.85%).

Example 5

The difference between this embodiment and the embodiment 1 is that the support rod 3 is a carbon-carbon composite rod; the bottom small insulation board 2 has an inverted T-shaped cross section and a circular shape in a plan view (as shown in FIG. 12), and the bottom portion is large. The cross section of the heat insulating plate 1 corresponding to the matching hole is inverted T-shaped; when the melting is completed into the crystal growth stage, the lifting device 7 is activated to separate the bottom small thermal insulation board 2 from the bottom large thermal insulation board 1, and the separation distance 15 is 300 mm. The same as Example 1.

Taking the G6 of JYT polycrystalline silicon ingot furnace into G7 as an example, the weight of the ingot is increased from 800 kg to 1200 kg. If the long crystal scheme of the insulated cage is simply adopted, the crystal growth time takes about 52 hours, and the total The process time is 92 hours; and with the small thermal insulation board moving device of the polycrystalline silicon ingot furnace of the present invention, the crystal growth time is shortened to 40 hours, and the total process time is shortened to 82 hours. Since the power is kept constant at about 70-75 kW during the growth period, each ingot can save about 840-900 degrees of power consumption, and the production efficiency is increased by about 12%-15%. At the same time, the ingot yield is increased by about 1.1%, and the wafer can be produced in a total of 500 pieces/ingot. The current polycrystalline silicon sheet is 6.5 yuan/piece, which increases the income by 3,250 yuan. In addition, the average conversion efficiency of the silicon wafer is increased by 0.1%. Absolute value (conversion efficiency increased from 17.75% to 17.85%).

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Any modification, modification, and equivalent structural transformation of the above embodiments in accordance with the technical spirit of the present invention are still the technical solutions of the present invention. The scope of protection.

Claims (10)

A small thermal insulation board movable device at the bottom of a polycrystalline silicon ingot furnace, comprising a small thermal insulation board at the bottom (2), a support rod (3), a telescopic tube (6), a lifting device (7); an upper nut (4) and a lower nut ( 16) fixing the bottom small thermal insulation board (2) to the upper part of the support rod (3); the lower part of the support rod (3) is extended to the bottom of the telescopic tube (6); the upper end of the extension tube (6) is The furnace body is connected, and the lower end of the telescopic tube (6) is connected with the lifting device (7); characterized in that: under the control of the lifting device (7), the bottom small thermal insulation board (2) can be along the axis of the support rod (3) Move up and down. The movable device for small insulation board at the bottom of a polycrystalline silicon ingot furnace according to claim 1, characterized in that: the lifting device (7) is composed of a lifting rod (8) and a servo motor (9), and the lifting rod (8) is along the servo The motor (9) can move up and down to drive the small insulation board (2) at the bottom of the upper part of the support rod (3) to move up and down. A small thermal insulation board movable device for a polycrystalline silicon ingot furnace according to claim 1, wherein said lifting device (7) is replaced by a C-shaped card (20) under the control of said C-shaped card (20) The bottom small insulation board (2) can move up and down along the axial direction of the support rod (3). The movable device for a small thermal insulation board at the bottom of a polycrystalline silicon ingot furnace according to claim 1, wherein the telescopic tube (6) is sealed and welded by a bellows (13) and a quick-change joint (14); A sealing ring (10) is arranged at the upper end of the pipe (6) and the furnace body, and is fixed by a clamp (11); a sealing ring (10) is provided at a lower end of the telescopic pipe (6) and the blind plate (12), and the card is used. The hoop (11) is fixed. The movable device for the small thermal insulation board at the bottom of the polycrystalline silicon ingot furnace according to claim 1, characterized in that: a spacer (5) is further disposed between the bottom small thermal insulation board (2) and the lower nut (16). The movable device for the bottom of the polycrystalline silicon ingot furnace according to any one of claims 1 to 5, characterized in that the support rod (3) can be a rod or a pipe member, and the material can be molybdenum, tungsten or stainless steel. One of graphite, or carbon-carbon composites. The movable device for the small thermal insulation board at the bottom of the polycrystalline silicon ingot furnace according to any one of claims 1 to 5, characterized in that: the bottom small thermal insulation board (2) has a rectangular or inverted T-shaped cross section, and a large thermal insulation board at the bottom. (1) The cross section of the corresponding mating hole is rectangular or inverted T-shaped. The movable device for the bottom small insulation board of the polycrystalline silicon ingot furnace according to any one of claims 1 to 5, characterized in that: the bottom small thermal insulation board (2) has a circular or rectangular top view and a large thermal insulation board at the bottom (1) The top view of the corresponding matching hole is circular or rectangular. The movable device for the small thermal insulation board at the bottom of the polycrystalline silicon ingot furnace according to any one of claims 1 to 5, characterized in that: the vertical separation distance between the bottom small thermal insulation board (2) and the bottom large thermal insulation board (1) (15) is 10 to 300 mm. A polycrystalline silicon ingot furnace comprising a lower furnace body (18) and an upper furnace body (19), characterized in that the polycrystalline silicon ingot furnace bottom small thermal insulation board movable device according to any one of claims 1 to 9.

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