What is the Oxyfuel combustion process?

Oxyfuel melting tanks offer a very precise and compact way of introducing energy into the melt.

By using oxygen burners, the flame can be precisely designed for the type of glass, raw material mixture, and required temperature profiles – from smaller units for household glass to powerful tanks for container glass or special glasses. Burner performance, flame shape, and installation position are combined to optimally match melting performance, temperature homogeneity, and glass quality.

Since significantly less nitrogen is present in the system during oxyfuel operation, the exhaust gas volume decreases considerably. This allows for smaller exhaust gas ducts, more compact filter systems, and reduces dust accumulation in the exhaust gas system. At the same time, NOx emissions can be well controlled through process management. Oxyfuel tanks can be designed as pure oxyfuel systems, as hybrid solutions with electric boosting, or as part of modernizations of existing tanks, where existing furnace concepts are adapted to new energy prices, emission regulations, or product changes.

The oxyfuel melting tank is a compact, energy-efficient, and versatile furnace solution that can be easily adapted to future requirements of energy policy, emission regulations, and product portfolio.

Our oxyfuel-heated glass melting tanks can be equipped with electric boosting systems depending on the task. These include melting boosting to increase melting capacity, thermal walls to stabilize the heat balance, and throat heating systems that precisely maintain the desired viscosity in the throat, thereby ensuring reproducible temperature profiles. This allows energy to be delivered very precisely to where it provides the greatest benefit from a process perspective.

Additionally, we use bubbling systems – operated with compressed air or oxygen – that support convection and refining, thereby increasing the homogeneity and purity of the glass. We adapt melting and refining zones using wall and throat constructions with optional air or water cooling. This allows us to precisely tailor the glass tank to raw materials, glass type, and required pull rate. In this way, a customized oxyfuel tank is created for your products, offering high energy efficiency, stable operating conditions, and reliably high glass quality.

There are various oxy-fuel combustion processes, which differ in how oxygen (O₂) and fuel are combined to generate energy. The most significant processes are listed below:

In this process, pure oxygen is used instead of air for fuel combustion. This leads to higher flame temperatures and significantly lower nitrogen oxide (NOₓ) formation. The main advantage lies in the ability to reduce the exhaust gas volume, which facilitates CO₂ capture.

Application: Particularly in the glass and steel industries, where high temperatures are required. This process is ideally suited for glass melting. The high flame temperatures and reduced exhaust gas volumes enable efficient melting with lower energy consumption and fewer emissions.

In Partial Oxy-Fuel Combustion, a mixture of pure oxygen and air is used. The oxygen content is higher than in normal air combustion, but lower than in direct oxy-fuel combustion. This allows for a balance between efficiency and operating costs.

Application: Also suitable, as it offers a balanced combination of efficiency and cost. Although not quite as efficient as direct oxy-fuel combustion, it can still be successfully used for glass melting in the glass industry.

In this process, exhaust gas is partially recirculated back into the combustion chamber. This has the advantage of lowering the flame temperature and improving heat transfer, which allows for better control of process conditions.

Application: Particularly useful in plants designed for CO₂ capture and storage (CCS). This process can also be used for glass melting, as it controls flame temperatures and improves heat transfer. It is particularly employed when additional process control is required.

Here, the fuel is combusted in several stages, with each stage having different oxygen concentrations. This can help control NOₓ formation and increase combustion efficiency.

Application: Often in industrial processes where precise control of combustion is required. This process is less suitable for the glass industry, as it primarily aims at controlling NOₓ formation, and the higher complexities are generally not necessary.

Here, the fuel is combusted in several stages, with each stage having different oxygen concentrations. This can help control NOₓ formation and increase combustion efficiency.

Application: Often in industrial processes where precise control of combustion is required. This process is less suitable for the glass industry, as it primarily aims at controlling NOₓ formation, and the higher complexities are generally not necessary.