Technical gases such as nitrogen and oxygen play a key role in modern glass manufacturing. Their use enhances product quality and helps reduce harmful emissions.
Oxygen in Glass Production
Oxygen significantly improves combustion processes by raising furnace temperatures. This leads to reduced emissions of nitrogen oxides (NOx) and particulate matter from glass-melting furnaces, while also boosting overall production efficiency.
Oxygen is used at various stages of glass manufacturing — for instance, in gas burners for trimming off-spec glass items, fire-polishing surfaces to eliminate micro-defects, and smoothing product edges. It is also essential in the production of medical and laboratory glassware, as well as electric light bulbs.
Nitrogen in Glass Production
Nitrogen is primarily used to cool electrodes in arc furnaces. A mixture of nitrogen and hydrogen is also used to prevent oxidation of tin during specific manufacturing stages. A critical factor in maintaining glass purity during these processes is controlling oxygen levels within the gas mixture over molten materials, kept under low overpressure. The permissible oxygen concentration in this environment is as low as 0.0001 %.
Manufacturing Technologies
Glass can be produced using various methods. One traditional method is vertical drawing (the Fourcault process), while the more modern and widely used approach is the float method, which involves forming glass on a bed of molten metal. The float method is now dominant due to its advantages in ensuring uniform thickness, excellent surface quality without further polishing, and high throughput, with minimal optical defects.
Oxygen Boosting in Glass Furnaces
The use of oxygen boosting is an effective way to improve furnace efficiency and lower operating costs. Oxygen serves as an oxidiser in combustion, reducing NOx and particulate emissions during the melting process.
The introduction of oxygen into the fuel mix is facilitated by specialised injector tubes. A portion of the thermal load is shifted to oxygen-fuel burners that complement standard air-fuel burners. This results in improved efficiency and up to 10 % fuel savings.There are two main methods for supplying oxygen:
- Air enrichment with oxygen, where oxygen is added to the airflow feeding the burners.
- Full oxygen-fuel combustion, which is especially beneficial in light of rising energy costs. This method improves furnace efficiency and significantly reduces natural gas consumption.
Advantages of Oxygen Boosting Systems:
- Increased furnace throughput
- Reduced fuel consumption
- Improved glass quality
- Lower flue gas emissions (NOx, fine particles, silica, CO₂)
As energy costs continue to rise, boosting furnace energy efficiency remains a key priority for glass manufacturers. Installing an oxygen-enhanced heating system offers a substantial reduction in monthly natural gas expenditure.
ONHS Gas Generation Systems for the Glass Industry
Large-scale glassworks often rely on nitrogen and oxygen supplied via pipelines from nearby cryogenic plants. However, many of our clients have faced frequent gas price hikes. To address this, we offer custom-built, on-site nitrogen and oxygen generation stations.
Installing an in-house gas supply system eliminates dependence on external suppliers and enables businesses to achieve full autonomy. The cost per cubic metre of self-generated gas is significantly lower, and the startup time for these systems is as short as 15 to 45 minutes.
