Efficient water vibration cooling method in industrial silicon production

Abstract

The invention relates to the technical field of industrial silicon production, in particular to an efficient water vibration cooling method in industrial silicon production. Comprising the following steps: injecting a high-temperature silicon melt into a mold with a cooling water channel; applying multi-direction mechanical vibration to the mold, wherein the vibration direction comprises composite vibration in the vertical direction and the horizontal direction; circulating cooling water is synchronously injected into a cooling water channel of the mold, and the water flow direction and the vibration direction form a synergistic effect; the vibration frequency is controlled to be 1-500 Hz, the amplitude is controlled to be 0.1-5 mm, and the cooling water flow is controlled to be 10-200 L / min; heat transfer in the silicon melt is accelerated through the synergistic effect of vibration and cooling water, and the cooling time is shortened by more than 30%. The invention provides an efficient cooling method capable of realizing a multi-physical field synergistic effect and dynamically regulating and controlling process parameters so as to break through the cooling efficiency and quality bottlenecks in industrial silicon production.

Description

Technical Field

[0001] The invention relates to the technical field of industrial silicon production, and in particular to a high-efficiency water vibration cooling method in industrial silicon production. Background Art

[0002] Industrial silicon is an important raw material for photovoltaics, semiconductors, and alloy materials. The cooling process in its production directly affects the product's grain structure, mechanical properties, and production efficiency. Traditional industrial silicon melt cooling mostly uses a static mold water cooling process, where heat exchange is achieved through circulating cooling water through the mold's built-in water channels. However, this method has significant technical bottlenecks: First, during the solidification process of the silicon melt, due to the high thermal conductivity difference, local thermal stress concentration is easily formed, resulting in a high crack defect rate inside the silicon block; second, the laminar boundary layer between the cooling water and the mold wall seriously restricts the heat exchange efficiency, and the conventional method has a long cooling time, which seriously restricts the increase in production capacity; third, single-direction cooling can easily cause directional segregation of the silicon melt solidification, resulting in uneven distribution of components.

[0003] In recent years, the industry has attempted to introduce mechanical vibration-assisted cooling technology, such as the use of unidirectional vertical vibration devices. Although these devices can destroy part of the boundary layer through vibration, the single vibration direction causes the turbulence effect to be limited to a local area, and the actual improvement in cooling efficiency is limited. Another technical solution uses high-frequency electromagnetic vibration, but this does not form a synergistic effect with the cooling water flow direction, and the fixed-frequency vibration is prone to causing resonant cavity defects inside the silicon melt. In addition, the thermal conductivity of traditional mold materials is insufficient, and the water channels are mostly arranged in a straight line, resulting in low heat exchange area utilization.

[0004] In terms of cooling medium optimization, existing technologies attempt to enhance heat transfer by adding micron-sized ceramic particles. However, due to particle settling issues, extremely high flow rates must be maintained during actual operation, resulting in a surge in energy consumption. Furthermore, existing vibration control systems generally operate in continuous mode, leading to excessive temperature rises and significantly increased failure rates. Particularly, existing technologies lack a response mechanism to dynamic thermal stress changes during the solidification phase, and the problem of hidden cracks caused by insufficient stress release in the late solidification phase has long remained unresolved. Summary of the Invention

[0005] The present invention provides an efficient cooling method capable of realizing the synergistic effect of multiple physical fields and dynamically regulating process parameters, so as to break through the cooling efficiency and quality bottlenecks in industrial silicon production.

[0006] The technical solution adopted by the present invention is: a high-efficiency water vibration cooling method in industrial silicon production, comprising the following steps:

[0007] Step 1: Inject high-temperature silicon melt into a mold with cooling water channels;

[0008] Step 2: Apply multi-directional mechanical vibration to the mold, the vibration direction includes composite vibration in vertical and horizontal directions;

[0009] Step 3: Synchronously inject circulating cooling water into the cooling water channel of the mold, and the water flow direction and vibration direction form a synergistic effect;

[0010] Step 4: Control the vibration frequency to 1-500Hz, the amplitude to 0.1-5mm, and the cooling water flow rate to 10-200L / min;

[0011] Step 5: Accelerate the heat transfer inside the silicon melt through the synergistic effect of vibration and cooling water, shortening the cooling time by more than 30%.

[0012] As a further improvement of the present invention, in the multi-directional mechanical vibration, the frequency ratio of vertical vibration to horizontal vibration is 1:1 to 1:3, and the amplitude of the vertical vibration is greater than 20%-50% of the amplitude of the horizontal vibration.

[0013] As a further improvement of the present invention, the vibration is ultrasonic vibration with a frequency range of 10-50 kHz, which enhances the wettability of the cooling water on the mold surface and the heat exchange efficiency through the ultrasonic cavitation effect.

[0014] As a further improvement of the present invention, the mold is made of copper or aluminum alloy, and is provided with spiral cooling water channels inside. The water channel spacing is 5-20 mm, the water channel diameter is 3-10 mm, and the water channel surface is coated with a nano-silicon carbide coating to improve thermal conductivity.

[0015] As a further improvement of the present invention, the cooling water has a flow rate of 1-5 m / s, a pressure of 0.2-1.5 MPa, a water temperature of 5-25° C., and nano-aluminum oxide particles are added to the water at a mass fraction of 0.1%-1% to enhance the turbulence effect.

[0016] As a further improvement of the present invention, the addition amount of the nano-alumina particles is dynamically adjusted according to the vibration frequency: when the vibration frequency is ≤100 Hz, the mass fraction of the nano-particles is 0.3%-0.8%; when the vibration frequency is >100 Hz, the mass fraction of the nano-particles is 0.1%-0.5%; and the particle size of the nano-particles is 20-100 nm, and the turbulent boundary layer destruction effect is optimized by matching the particle dispersion with the vibration intensity.

[0017] As a further improvement of the present invention, the vibration is achieved by an electromagnetic vibrator and an eccentric wheel mechanical vibrator, the vibrator is installed on the bottom and side wall of the mold, and the vibration direction is programmable.

[0018] As a further improvement of the present invention, the vibration adopts an intermittent working mode: it works for 2-10 minutes and stops for 1-5 minutes, and keeps the cooling water flowing continuously during the stop period to reduce energy consumption and avoid overheating of the equipment.

[0019] As a further improvement of the present invention, the vibration direction is dynamically adjusted according to the solidification stage of the silicon melt: vertical vibration is mainly used in the early stage of solidification, and it is switched to horizontal vibration in the later stage of solidification, and the vibration direction is alternated every 30 seconds to eliminate stress concentration.

[0020] As a further improvement of the present invention, when the vibration direction is switched between the early and late stages of solidification, the cooling water flow rate is adjusted synchronously: in the early vertical vibration stage of solidification, the cooling water flow rate is 3-5 m / s; in the late horizontal vibration stage of solidification, the cooling water flow rate is reduced to 1-3 m / s; the flow rate change gradient is ≤1 m / s·min-1, so as to avoid cracks caused by sudden temperature changes inside the silicon block.

[0021] The beneficial effects of the present invention are as follows: (1) The present invention forms a three-dimensional turbulence effect on the mold surface through the coordinated design of vertical and horizontal composite vibration directions and cooling water flow directions, effectively destroying the laminar boundary layer and improving the heat transfer coefficient by 40%-60%. At the same time, the vibration energy is transmitted through the interior of the silicon melt, accelerating the uniform distribution of crystal nuclei and reducing directional segregation. The uniformity deviation of the silicon block composition is reduced from ±8% of the traditional process to within ±2%.

[0022] (2) Based on the changing characteristics of thermal stress during the solidification stage, the present invention dynamically switches the vibration direction and synchronously adjusts the cooling water flow rate. Combined with the vibration frequency response mechanism of the amount of nanoparticles added, it achieves a precise match between turbulence intensity and solidification rate. It not only shortens the cooling time to less than 2.8 hours, but also reduces the internal crack defect rate from 12%-18% to 3%-5%. In addition, the energy consumption of the equipment is reduced by 25%-30% compared with the traditional continuous vibration mode.

[0023] (3) The present invention adopts a high thermal conductivity copper / aluminum alloy mold and a spiral water channel design, combined with a nano-silicon carbide coating, so that the overall thermal conductivity of the mold reaches 400-600W / (m·K), and the heat exchange area utilization rate is increased to more than 75%; and the dynamic suspension effect of nano-alumina particles in the vibration field solves the traditional problem of micron particle sedimentation. At a flow rate of 1-3m / s, it can achieve an enhanced heat transfer effect equivalent to a flow rate of 8m / s, significantly reducing the power consumption of the water pump. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described herein are only used to explain this application and are not intended to limit this application.

[0025] The present invention provides a high-efficiency water vibration cooling method for industrial silicon production, comprising the following steps:

[0026] Step 1: Inject high-temperature silicon melt into a mold with cooling water channels;

[0027] Step 2: Apply multi-directional mechanical vibration to the mold, the vibration direction includes composite vibration in vertical and horizontal directions;

[0028] Step 3: Synchronously inject circulating cooling water into the cooling water channel of the mold, and the water flow direction and vibration direction form a synergistic effect;

[0029] Step 4: Control the vibration frequency to 1-500Hz, the amplitude to 0.1-5mm, and the cooling water flow rate to 10-200L / min;

[0030] Step 5: Accelerate the heat transfer inside the silicon melt through the synergistic effect of vibration and cooling water, shortening the cooling time by more than 30%.

[0031] In the multi-directional mechanical vibration of the present invention, the frequency ratio of vertical vibration to horizontal vibration is 1:1 to 1:3, and the amplitude of vertical vibration is greater than 20%-50% of the amplitude of horizontal vibration.

[0032] The vibration described in the present invention is ultrasonic vibration with a frequency range of 10-50kHz, which enhances the wettability of the cooling water on the mold surface and the heat exchange efficiency through the ultrasonic cavitation effect.

[0033] The mold of the present invention is made of copper or aluminum alloy, and is provided with spiral cooling water channels inside. The water channel spacing is 5-20 mm, the water channel diameter is 3-10 mm, and the water channel surface is coated with a nano-silicon carbide coating to improve thermal conductivity.

[0034] The cooling water of the present invention has a flow rate of 1-5 m / s, a pressure of 0.2-1.5 MPa, a water temperature of 5-25° C., and 0.1%-1% by mass of nano-aluminum oxide particles are added to the water to enhance the turbulence effect.

[0035] The addition amount of the nano-alumina particles described in the present invention is dynamically adjusted according to the vibration frequency: when the vibration frequency is ≤100Hz, the mass fraction of the nano-particles is 0.3%-0.8%; when the vibration frequency is >100Hz, the mass fraction of the nano-particles is 0.1%-0.5%; and the particle size of the nano-particles is 20-100nm. The turbulent boundary layer destruction effect is optimized by matching the particle dispersion with the vibration intensity.

[0036] The vibration of the present invention is achieved by an electromagnetic vibrator and an eccentric wheel mechanical vibrator. The vibrator is installed on the bottom and side wall of the mold, and the vibration direction can be programmably adjusted.

[0037] The vibration machine of the present invention adopts an intermittent working mode: it works for 2-10 minutes and stops for 1-5 minutes. During the stop period, the cooling water is kept flowing to reduce energy consumption and avoid overheating of the equipment.

[0038] The vibration direction of the present invention is dynamically adjusted according to the solidification stage of the silicon melt: vertical vibration is mainly used in the early stage of solidification, and is switched to horizontal vibration in the later stage of solidification, and the vibration direction is alternated every 30 seconds to eliminate stress concentration.

[0039] The present invention synchronously adjusts the cooling water flow rate when switching the vibration direction in the early and late stages of solidification: in the vertical vibration stage in the early stage of solidification, the cooling water flow rate is 3-5 m / s; in the horizontal vibration stage in the late stage of solidification, the cooling water flow rate is reduced to 1-3 m / s; the flow rate change gradient is ≤1 m / s·min-1, so as to avoid cracks caused by sudden temperature changes inside the silicon block.

[0040] Example 1:

[0041] A high-temperature silicon melt at 1550°C was injected into a copper mold (water channel diameter 6 mm, spiral pitch 12 mm, surface coated with 50 μm nano-silicon carbide coating). The composite vibration device was activated; (1) vertical vibration: frequency 80 Hz, amplitude 2.8 mm; (2) horizontal vibration: frequency 120 Hz, amplitude 1.5 mm; (3) vibration mode: intermittent cycle of 5 minutes on / 3 minutes off.

[0042] Cooling water parameters: (1) inlet water temperature 15°C, pressure 0.8 MPa; (2) addition of 0.6% alumina particles with a particle size of 40 nm; (3) flow rate 4.2 m / s in the early stage of solidification (vertical vibration stage); (4) flow rate 2.5 m / s in the late stage of solidification (horizontal vibration stage).

[0043] Real-time monitoring showed that: (1) the solidification time was shortened to 2 hours and 45 minutes; (2) the internal crack rate of the silicon ingot was reduced to 3.8%; and (3) the thermal imager showed that the temperature difference on the mold surface was reduced from 120°C in the traditional process to 35°C.

[0044] Example 2:

[0045] An aluminum alloy mold (water channel diameter 8 mm, spiral pitch 8 mm) was used to implement ultrasonic vibration; (1) vertical vibration: 28 kHz, amplitude 0.3 mm; (2) horizontal vibration: 35 kHz, amplitude 0.2 mm; (3) the vibration direction automatically switched every 30 seconds.

[0046] Cooling water system configuration: (1) Dynamic adjustment of nano-alumina concentration (0.4% at 100 Hz vibration); (2) Flow rate gradient control: 0.8 m / s·min-1; (3) Segmented pressure control: initial 1.2 MPa → later 0.5 MPa.

[0047] Performance data: (1) Heat transfer coefficient reaches 5800W / (m 2·K); (2) the standard deviation of grain size distribution is reduced from 45μm in traditional process to 12μm; (3) the unit energy consumption is only 72% of traditional vibration cooling.

[0048] The index data of the above-mentioned embodiment 1, embodiment 2, and comparative example 1 (traditional static), comparative example 2 (unidirectional vibration), and comparative example 3 (electromagnetic vibration) are shown in the following table.

[0049]

[0050]

[0051] As can be seen from the above table, the composite vibration of the present method causes the cooling water to produce a swirling flow, and the boundary layer thickness is reduced by 62% compared with the unidirectional vibration of Comparative Example 2 (measured data: the boundary layer of Example 1 is 0.15 mm vs. 0.4 mm of Comparative Example 2); the flow rate gradient control during the solidification stage stabilizes the temperature drop at 18°C / min, avoiding the stress mutation caused by the traditional process of fast at the beginning and slow at the end (35°C / min→8°C / min); the Stokes number of the nanoparticles in the vibration field is controlled in the range of 0.01-0.1, achieving a suspension stability of more than 90%, and the sedimentation rate is reduced by 83% compared with the micron particle system; the intermittent vibration mode controls the temperature rise of the vibrator within 45°C, which effectively extends the equipment life by 3 times compared with the continuous vibration mode (temperature rise of 110°C).

[0052] In summary, the present invention's high-efficiency water vibration cooling method for industrial silicon production achieves significant improvements in cooling efficiency and product quality through the synergistic effect of multiple physical fields and dynamic control technology. Compared to traditional static cooling, unidirectional vibration, and electromagnetic vibration methods, the present invention not only significantly shortens the cooling time and reduces the internal crack defect rate, but also significantly improves the composition uniformity and grain uniformity of the silicon block, while reducing energy consumption and extending the service life of the equipment. In addition, the method is simple to operate, easy to implement industrial applications, and has broad market prospects and economic benefits.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-efficiency water vibration cooling method for industrial silicon production, characterized in that: The following steps are involved: Step 1: Inject high-temperature silicon melt into a mold with cooling water channels; Step 2: Apply multi-directional mechanical vibration to the mold, the vibration direction includes composite vibration in vertical and horizontal directions; Step 3: Synchronously inject circulating cooling water into the cooling water channel of the mold, and the water flow direction and vibration direction form a synergistic effect; Step 4: Control the vibration frequency to 1-500Hz, the amplitude to 0.1-5mm, and the cooling water flow rate to 10-200L / min; Step 5: Accelerate the heat transfer inside the silicon melt through the synergistic effect of vibration and cooling water, shortening the cooling time by more than 30%.

2. The high-efficiency water vibration cooling method in industrial silicon production according to claim 1, characterized in that: In the multi-directional mechanical vibration, the frequency ratio of vertical vibration to horizontal vibration is 1:1 to 1:3, and the amplitude of the vertical vibration is greater than 20%-50% of the amplitude of the horizontal vibration.

3. The high-efficiency water vibration cooling method in industrial silicon production according to claim 2, characterized in that: The vibration is ultrasonic vibration with a frequency range of 10-50kHz, which enhances the wettability of the cooling water on the mold surface and the heat exchange efficiency through the ultrasonic cavitation effect.

4. The high-efficiency water vibration cooling method in industrial silicon production according to claim 1, characterized in that: The mold is made of copper or aluminum alloy, and is provided with spiral cooling water channels inside. The water channel spacing is 5-20 mm, the water channel diameter is 3-10 mm, and the water channel surface is coated with nano-silicon carbide coating to improve thermal conductivity.

5. The high-efficiency water vibration cooling method in industrial silicon production according to claim 1, characterized in that: The cooling water has a flow rate of 1-5 m / s, a pressure of 0.2-1.5 MPa, a water temperature of 5-25° C., and 0.1%-1% by mass of nano-aluminum oxide particles are added to the water to enhance the turbulence effect.

6. The high-efficiency water vibration cooling method in industrial silicon production according to claim 5, characterized in that: The addition amount of the nano-alumina particles is dynamically adjusted according to the vibration frequency: when the vibration frequency is ≤100 Hz, the mass fraction of the nano-particles is 0.3%-0.8%; when the vibration frequency is >100 Hz, the mass fraction of the nano-particles is 0.1%-0.5%; and the particle size of the nano-particles is 20-100 nm. The turbulent boundary layer destruction effect is optimized by matching the particle dispersion with the vibration intensity.

7. The high-efficiency water vibration cooling method in industrial silicon production according to claim 1, characterized in that: The vibration is achieved by an electromagnetic vibrator and an eccentric wheel mechanical vibrator. The vibrators are installed on the bottom and side walls of the mold, and the vibration direction is programmable.

8. The high-efficiency water vibration cooling method in industrial silicon production according to claim 1, characterized in that: The vibration adopts an intermittent working mode: it works for 2-10 minutes and stops for 1-5 minutes. During the stop period, the cooling water is kept flowing to reduce energy consumption and avoid overheating of the equipment.

9. The high-efficiency water vibration cooling method in industrial silicon production according to claim 1, characterized in that: The vibration direction is dynamically adjusted according to the solidification stage of the silicon melt: vertical vibration is mainly used in the early stage of solidification, and is switched to horizontal vibration in the later stage of solidification, and the vibration direction is alternated every 30 seconds to eliminate stress concentration.

10. The high-efficiency water vibration cooling method in industrial silicon production according to claim 9, characterized in that: When switching the vibration direction at the early and late stages of solidification, the cooling water flow rate is adjusted synchronously: in the early vertical vibration stage of solidification, the cooling water flow rate is 3-5m / s; in the later horizontal vibration stage of solidification, the cooling water flow rate is reduced to 1-3m / s; the flow rate change gradient is ≤1m / s·min-1 to avoid cracks caused by sudden temperature changes inside the silicon block.

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