Cooled Polycrystalline Feed Tube Shielding Near Molten Silicon
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The generation of silicon dust and crushed particles during the feeding of polycrystalline silicon into a crucible for crystal growth is a significant issue, which can negatively impact the crystal growth process and lead to damage of the feed tube due to the proximity of the tube's outlet to the high-temperature melt.
Innovation Solution
A polycrystalline feed system with a heat exchanger and shield assembly is employed to cool the feed tube, allowing it to be positioned closer to the melt surface while protecting it from thermal damage, thereby reducing dust and particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the feed tube is positioned closer to the melt surface to reduce silicon dust generation, then dust and particle generation is reduced, but the feed tube suffers thermal damage and melting
Solution Approach 1:
A water-cooled shield assembly is introduced as an intermediary component between the feed tube and the molten silicon. The shield absorbs and dissipates thermal radiation from the melt through active cooling, protecting the feed tube from thermal damage while enabling closer positioning to reduce dust generation.
Solution Approach 2:
The temperature of the shield assembly is actively controlled by circulating cooling water, changing the thermal parameters of the system. This allows the shield to maintain a lower temperature than the molten silicon while the feed tube operates in the high-temperature zone, resolving the thermal protection requirement.
2Reliability
If the feed tube is positioned farther from the melt surface to protect from thermal damage, then feed tube integrity is maintained, but silicon dust and crushed particles are generated
Solution Approach 1:
The water-cooled shield serves as a thermal barrier that decouples the feed tube from the high-temperature environment. This intermediary structure allows the feed tube to operate in a cooler zone while still maintaining close proximity to the melt surface, thereby reducing dust generation without compromising tube integrity.
Solution Approach 2:
The system is segmented into distinct thermal zones: the shield assembly handles the high-temperature exposure near the melt, while the feed tube operates in a cooler region. This segmentation allows each component to function in its optimal thermal environment, resolving the contradiction between proximity and protection.
3Reliability
If a cooling system is added to protect the feed tube, then thermal damage is reduced, but device complexity increases
Solution Approach 1:
The shield assembly with integrated cooling channels provides thermal protection while maintaining a relatively simple structure. The cooling system is confined to the shield component rather than the entire feed tube assembly, minimizing the increase in overall system complexity while achieving effective thermal protection.
Solution Approach 2:
A hydraulic cooling system using circulating water is employed to remove heat from the shield assembly. This approach provides efficient heat removal with simple infrastructure requirements, avoiding the need for complex mechanical or electrical cooling systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively reduces thermal damage to the feed tube and minimizes silicon dust and particle generation, enhancing the crystal growth process by enabling closer positioning to the melt surface without causing damage.
Implementation Method 1
a heat exchanger extending around, and spaced from, the outer sidewall of the feed tube for cooling the feed tube
Implementation Method 2
a heat shield extending radially between the outer sidewall of the feed tube and the heat exchanger to shield at least a portion of the feed tube from the heat of the melt
Data Source
AI summary
A polycrystalline feed system for supplying chunk polycrystalline to a crucible containing a melt includes a feed tube having an outer sidewall and an outlet end and a heat exchanger extending around, and spaced from, the outer sidewall of the feed tube for cooling the feed tube. The feed system further includes a shield assembly connected to the feed tube. The shield assembly includes a heat shield extending radially between the outer sidewall of the feed tube and the heat exchanger to shield at least a portion of the feed tube from the heat of the melt.