The glass melting furnace is the "heart" of glass production, accounting for 60%-70% of the entire production process's energy consumption and facing risks such as high temperatures, high emissions, and high costs. Traditional air-assisted combustion methods have pain points such as low thermal efficiency, high NOx emissions, and large fluctuations in melting quality. The introduction of oxy-fuel and all-oxygen combustion technology is profoundly reshaping the combustion and melting processes of glass melting furnaces, becoming a core engine driving the transformation of the glass industry towards high efficiency, high quality, and low carbon emissions.

4.3.1、Technical Core: Deep Adaptation of Oxy-fuel/All-Oxygen Combustion and Glass Melting

1. Oxy-fuel Combustion: Increases the oxygen concentration in the combustion air to 23%-95%, significantly reducing the nitrogen content.
2. All-Oxygen Combustion: Uses oxygen with a purity >90% to replace air as the combustion agent (current mainstream).
3. Specialized Burner Design:
   • Precise Flame Characteristic Control: Optimizes the mixing of fuel (natural gas, heavy oil, coke oven gas, etc.) and oxygen to achieve short, wide, flat, and soft flame shapes to ensure large coverage area, uniform temperature, and avoid local overheating.
   • Low Momentum Design: Reduces the impact of the flame on the glass liquid surface, reducing dust flying and refractory material erosion.
   • Material Upgrade: Withstands higher temperatures (flame temperature can reach 2800℃+) and strongly oxidizing/corrosive environments (especially those containing alkaline vapor).
   • Low NOx Integration: All-oxygen combustion itself has no thermal NOx, and combined with staged oxygen supply and other technologies, it further inhibits fuel NOx.
4. Intelligent Control System: Precisely interlinks oxygen flow, fuel flow, kiln pressure, and temperature distribution to achieve optimal melting process.

4.3.2、Core Application Scenarios and Disruptive Advantages

1. Melting and Refining of Various Glass Furnaces

1. Applications: Float glass, pressed glass, daily-use glass (bottles, containers, tableware), special glass (electronic, optical, pharmaceutical), glass fiber pool kilns, etc.
2. Advantages:
   • Revolutionary Energy Saving (20%-40%):
     1. Eliminates 78% of nitrogen heat absorption and exhaust heat loss (all-oxygen).
     2. Higher flame temperature, greater blackness, Radiation heat transfer efficiency increased by 30% or more 。
     3. More complete combustion, reducing chemical incomplete combustion losses.
     4. Flue gas volume sharply reduced (all-oxygen combustion is only 15%-25% of air combustion), Waste heat recovery system efficiency significantly improved 。
   • Significantly Improves Melting Quality and Output:
     1. More uniform temperature distribution: Eliminates "hot spots", reduces temperature difference, improves glass liquid convection, Increases melting rate (10%-30%) and refining quality , reduces defects such as bubbles, streaks, and stones.
     2. Improved Glass Homogeneity: A stable high-temperature environment is conducive to chemical and thermal homogenization.
     3. Adaptable to High-Grade/Refractory Materials: Enhanced melting capacity, expanding the range of raw material choices.
   • Ultra-Low Emissions, Environmental Compliance:
     1. NOx Reduction (70%-90%): All-oxygen combustion basically eliminates thermal NOx; combined with optimized design, fuel NOx can be controlled. Emission concentration easily reduced to <500mg/Nm³, or even <200mg/Nm³ (far below stringent standards).
     2. Dust Emission Reduction: Flue gas volume is significantly reduced, and low-momentum flames reduce material flying, Absolute dust emissions reduced by 50%+ 。
     3. SOx/CO₂ Emission Reduction: Reduced total flue gas volume leads to a decrease in absolute emissions; high CO₂ concentration (>80%) is beneficial for subsequent capture (CCUS) 。
   • Extended Kiln Life:
     1. Reduces high-temperature corrosion and powder erosion of the kiln crown "hot spots".
     2. Reduces the damage caused by flame impact and local high temperatures to the breast wall, small furnace, and regenerator checkerwork.
     3. All-oxygen combustion can eliminate regenerators/heat exchangers (or simplify the structure), eliminating temperature fluctuations and structural stress caused by switching.
   • Improved Production Flexibility and Stability:
     1. Eliminating switching, kiln temperature, kiln pressure, and atmosphere extremely stable , reducing operational fluctuations.
     2. Fast adjustment response, easier to adapt to changes in formula, color, and drawing amount.
   • Investment and Space Savings:
     1. All-oxygen combustion can Eliminates the large and complex regenerator system Shorten the kiln length to reduce the footprint and civil works investment.
     2. Simplify the combustion system (no small furnace, reversing valve) to reduce maintenance costs.

2. Special glass and high-end glass production

1. Applications: Extra-white glass, low-iron photovoltaic glass, high borosilicate glass, aluminosilicate cover glass, optical glass, etc.
2. Advantage Enhancement:
   • Ultimate Purity: Nitrogen-free environment Significantly reduces the content of bubbles (especially microbubbles) and dissolved gases , which is crucial for glass with high optical performance and strength requirements.
   • Precise Oxidation-Reduction Control: A full-oxygen atmosphere makes it easier to precisely control the oxygen partial pressure in the kiln, achieving the ideal oxidation-reduction state (RedoxNumber) , ensuring color stability (such as low Fe²⁺ content in extra-white glass) and physicochemical properties.
   • Reduce Metal Contamination: Avoid corrosion products (such as MgO, ZnO) from the regenerator checkerwork being carried into the glass melt by the flue gas.

3. High Proportion of Cullet Melting

1. Advantages:
   • More Significant Energy Saving Effects: Cullet melting has low energy consumption, combined with the high efficiency of oxy-fuel/full-oxygen combustion, overall energy saving can reach 40%+ 。
   • Reduce Volatilization and Secondary Bubbles: Gentle and uniform heating reduces the loss of volatile components (such as boron, lead, and fluorine) in the cullet and the generation of secondary bubbles.
   • Environmental Benefits Doubled: Promotes resource recycling, combined with its own emission reduction advantages.

4.3.3、Application Benefit Overview

4.3.4、Key Risk Points and Countermeasures for Application

1. Oxygen Cost and Supply:
   • Risk Points: Oxygen is the main incremental operating cost.
   • Countermeasures: Optimize high-efficiency, low-energy oxygen production technology (mainly VPSA/VSA); accurately calculate energy-saving benefits to cover oxygen costs; utilize peak and off-peak electricity prices; policy subsidies (carbon emission reduction benefits).
2. Refractory Material Erosion:
   • Risk Points: High temperature, high alkali vapor, and high H₂O partial pressure accelerate the erosion of AZS electrofused bricks, etc. (especially the crown and breast wall).
   • Countermeasures: Select more corrosion-resistant materials (such as α/β-Al₂O₃, chromium corundum, dense zirconia bricks); optimize burner arrangement and flame coverage; strictly control crown temperature; enhance cooling.
3. Burner Design and Maintenance:
   • Risk Points: High-temperature oxidation/corrosion environment requires high demands on the service life of burner nozzles; the flame shape needs to be precisely matched to the kiln type and process.
   • Countermeasures: Use high-quality heat-resistant alloys/ceramic materials; modular design for easy replacement; advanced CFD simulation optimization design; regular maintenance.
4. Control Complexity:
   • Risk Points: Precise coordination of multiple parameters such as oxygen-fuel ratio, kiln pressure, and temperature distribution is required.
   • Countermeasures: Equip with advanced DCS/APC systems; apply artificial intelligence algorithms to optimize combustion models.
5. Safety Risks:
   • Risk Points: Leakage and flashback risks of high-concentration oxygen systems.
   • Countermeasures: Strictly follow safety standards such as NFPA86; multiple safety interlocks (pressure, flow, flame monitoring); explosion-proof design; professional training.

4.3.5、Development Trends and Future

1. Deep Coupling with Electric Melting/Hybrid Melting: Full-oxygen combustion provides the basic heat source, and electric boosting precisely compensates for hot spots, achieving the optimal energy structure under the "dual carbon" goal.
2. Deep Application of Artificial Intelligence: AI real-time optimization of combustion parameters, prediction of refractory material life, and intelligent diagnosis of operational failures.
3. Zero-Carbon Fuel Adaptability: Burner upgrades to adapt to green fuels such as hydrogen and biogas.
4. Modular and standardized design: Reduce costs and shorten delivery cycles.
5. CCUS industry chain integration: Enriched CO₂ flue gas is directly used for the production of food-grade CO₂ or geological sequestration.
6. Promotion of micro-oxygen combustion technology: As a transition or supplement to full oxygen, it is more economical in retrofit projects.

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