Melting Vessel Aspect Ratio and Segmentation for Glass Defect Reduction
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Solution Overview
Problem
The challenge is to design a melting vessel that can support high glass flow rates while minimizing defects, particularly due to limitations in voltage usage and compatibility issues between electrode materials and fining agents, which restrict the size and aspect ratio of the melting vessel, leading to instability and inhomogeneities in the molten glass.
Innovation Solution
The solution involves a melting vessel with a length-to-width aspect ratio of 2.0 to 2.4, using molybdenum electrodes extending into the vessel through the bottom wall, and a heating method that combines electric current and combustion burners to maintain a voltage-to-ground variation within safe limits, promoting specific convection flow ratios to enhance mixing and reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of the melting vessel is increased to produce more glass, then productivity is improved, but the voltage required to electrically fire across the width becomes increasingly dangerous and may cause current to bypass the molten glass through the refractory material
Solution Approach 1:
The patent divides the single large melting vessel into multiple smaller melting vessels arranged in parallel. Each smaller vessel operates at safe voltage levels while the combined output of multiple vessels achieves the desired high productivity. This segmentation resolves the contradiction by allowing increased glass production without requiring dangerous high voltages in any single vessel.
2Productivity
If the width of the melting vessel is increased to increase flow capacity, then productivity is improved, but the voltage required to electrically fire across the width increases to dangerous levels
Solution Approach 1:
Instead of increasing the width of a single melting vessel, the patent uses multiple narrower vessels placed side by side. Each vessel maintains a width that corresponds to safe operating voltage, while the aggregate flow capacity of all vessels together meets the high productivity requirement. This approach allows increased flow capacity without exposing any single vessel to dangerous voltage levels.
3Productivity
If high voltage is used to support high glass flow rates, then productivity is improved, but the likelihood of current bypassing through refractory material increases causing defects
Solution Approach 1:
The patent achieves high glass flow rates through multiple parallel vessels operating at safe voltage levels, preventing current bypass through refractory material. This maintains manufacturing precision and glass quality while still achieving high overall productivity through the combined output of multiple vessels.
Solution Approach 2:
The patent introduces an intermediary structural arrangement where multiple smaller melting vessels are positioned in parallel within the furnace. This intermediary configuration allows the system to achieve high flow capacity without requiring high voltage in any single vessel, thereby preventing current bypass defects while maintaining high productivity.
4Device complexity
If incompatible electrode materials and fining agents are used, then device complexity is reduced, but zirconia may precipitate out of the molten glass forming defects
Solution Approach 1:
The patent changes the material parameters of the electrodes to use zirconia-compatible materials, and adjusts the fining agent composition to be compatible with zirconia. This parameter change prevents zirconia precipitation and maintains glass homogeneity, resolving the contradiction between material compatibility and defect formation.
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
This design achieves stable thermal and electrical conditions, reducing defects in the glass articles by maintaining a low cord contrast and improving the pass rate, ensuring that the glass produced meets high-quality standards for display applications.
Implementation Method 1
electically boosted Joule heating within the molten glass itself
Implementation Method 2
traditional combustion burners positioned in the upper portion of the melting vessel above the molten glass level
Implementation Method 3
produce a plurality of convection flows in the molten glass
Data Source
Figure 1
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Figure 4~5
AI summary
An electrically boosted refractory melting vessel including a back wall, a first side wall, a second side wall, a front wall and a bottom wall, the melting vessel comprising a longitudinal center line extending from the back wall to the front wall and an overall width orthogonal to the longitudinal center line extending between an inside surface of the first side wall and an inside surface of the second side wall. The melting vessel also includes a length L between the back wall and the front wall, and a width W between the first side wall and the second side wall orthogonal to the center line. A plurality of electrodes extend into an interior of the melting vessel through a bottom wall of the melting vessel, and L/W is in a range from about 2.0 to about 2.4.