Float Glass Surface Defect Control via Hydrogen Atmosphere
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Solution Overview
Problem
The use of natural gas instead of heavy oil and oxygen gas instead of air in float glass manufacturing leads to defects on the bottom surface of float glass due to increased water elution from molten glass to molten tin, affecting the quality and manufacturing cost.
Innovation Solution
Adjusting the hydrogen gas concentration in the bath atmosphere to limit water elution from molten glass to molten tin to 0.5% or lower, with an initial water concentration of 470 mass ppm or more in the molten glass, and controlling temperatures to suppress gas component precipitation, thereby reducing defects on the bottom surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If natural gas is used instead of heavy oil and oxygen gas instead of air in the melting furnace, then thermal efficiency is improved and CO2/NOx discharge is reduced, but water elution from molten glass to molten tin increases causing defects on the bottom surface of float glass
Solution Approach 1:
The patent changes the chemical composition parameters of the molten glass by adding specific amounts of S (0.03-0.20 mass%), Se (0.003-0.05 mass%), and Te (0.003-0.05 mass%). These parameter changes modify the glass structure to reduce water elution to the molten tin bath, thereby preventing surface defects while maintaining the use of natural gas and oxygen gas for improved thermal efficiency
Solution Approach 2:
The patent introduces sulfur, selenium, and tellurium as intermediary substances that modify the interaction between molten glass and molten tin. These additives act as mediators that suppress water elution from the glass to the tin bath, preventing defect formation on the glass bottom surface while allowing the continued use of efficient natural gas and oxygen gas combustion
2Quantity of substance
If the concentration of water in molten glass is increased to 470 mass ppm or more, then the amount of water eluted to molten tin can be controlled, but defects may be generated on the bottom surface of float glass
Solution Approach 1:
The patent precisely controls the water concentration parameter in molten glass within the range of 470-1500 mass ppm, and combines this with specific additions of S, Se, and Te. This coordinated parameter control allows sufficient water content to maintain glass properties while preventing excessive water elution that would cause surface defects
Solution Approach 2:
The patent creates a composite chemical system in the molten glass by combining water (H2O) with sulfur, selenium, and tellurium additives. This composite composition works synergistically to control water elution behavior, allowing high water content without generating defects on the float glass bottom surface
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 method results in high-quality float glass with reduced defects and lower manufacturing costs by minimizing water elution and gas component oversaturation, ensuring excellent surface quality and efficient production.
Implementation Method 1
a concentration of hydrogen gas in an atmosphere inside the bath may be adjusted so that the amount of water eluted from the molten glass to the molten tin in the bath becomes 0.5% or lower
Implementation Method 2
the amount of water eluted from the molten glass to the molten tin
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present invention relates to a float glass manufactured by causing a molten glass continuously supplied onto a molten tin in a bath to flow on the molten tin toward an outlet of the bath, in which the float glass satisfies the following formula (1). According to the present invention, a high-quality float glass and a method for manufacturing the same are provided. [Math. 1] ∫0DaCa-CxⅆxCa×D×100≦0.5