Day Tank
Day Tank from IWG Glasofenbau
The day tank was developed as a standalone furnace type to provide a periodically operating melting unit – but without the typical disadvantages of a pot furnace, such as complex pot changes or temperature-related limitations.
The melting process, similar to a pot furnace, follows a 24-hour cycle. In contrast, however, the day tank allows for significantly higher melting temperatures without damaging the melting basin. This makes it suitable for glass types that are difficult to melt.
Day tanks are preferably used for studio and small-batch glass production. For applications with particularly high quality requirements, the pot furnace still offers advantages, especially due to the separate melting process in individual pots.
A day tank can be heated either electrically or with fossil fuels (gas or oxy-fuel) and can be flexibly adapted to the respective process requirements.
Day Tank
// IWG Glasofenbau
Gas-fired day tank
Gas-fired day tanks are among the most commonly used designs in discontinuous glass furnace construction. Heating is typically done using natural gas or liquid gas burners, which are specifically aimed at the glass bath and the combustion chamber. Through direct combustion, the required melting temperature can be reached relatively quickly and controlled precisely.
A key advantage of gas-fired day tanks is their high thermal performance combined with simple plant technology. Temperature profiles can be flexibly adapted to different glass recipes, which is particularly relevant for frequent glass changes or varying batch sizes. The design also allows for a compact furnace construction with manageable investment costs.
Gas-fired day tanks are primarily used where process reliability, robust technology, and economic implementation are priorities. Depending on the requirements, they can be equipped with different burner systems, refractory materials, and control concepts.
Tableware and kitchen glass
Crystal glass, Soda-lime glass,
Lead crystal,
Glass containers
Soda-lime glass
Art glass
Crystal glass, Lead crystal
Colored glass
Conditioning
Forehearth for various glass types
Conditioning
Platinum Feeder System
Electrically heated day tank
Electrically heated day tanks are used when high temperature homogeneity, precise process control, and low emissions are priorities. Heating is achieved using electrically operated heating elements, which are located directly in the furnace chamber or in the immediate vicinity of the glass bath. This allows heat to be introduced into the glass very evenly.
A key advantage of electrically heated day tanks is the precise controllability of the temperature. Fluctuations in the melting process can be minimized, which is particularly important in the production of high-quality technical or optical glass. Furthermore, electric heating does not produce combustion-related exhaust gases in the furnace chamber, which can positively affect glass quality.
Electric day tanks are particularly suitable for small to medium melting capacities and for applications with high requirements for purity and reproducibility. Depending on the operational conditions – especially energy costs – they represent a technically sophisticated alternative to gas-fired systems. IWG Glasofenbau designs electrically heated day tanks individually tailored to the glass type, batch size, and production processes.
Tableware and kitchen glass
Crystal glass, Soda-lime glass,
Lead crystal,
Glass containers
Soda-lime glass
Art glass
Crystal glass, Lead crystal
Colored glass
Conditioning
Forehearth for various glass types
Conditioning
Platinum Feeder System
Oxy-fuel-fired day tank
Oxy-fuel heated day tanks operate with the combustion of fuel gas and nearly pure oxygen instead of ambient air. By eliminating the nitrogen component, a significantly higher flame temperature is achieved with a simultaneously reduced exhaust gas volume. The introduced energy thus has a more direct effect on the glass bath.
A key advantage of oxy-fuel heating is its high energy efficiency and very uniform heat distribution. The melting process can be designed more compactly, which is particularly advantageous with limited installation space or special glass recipes. At the same time, CO₂ and NOₓ emissions can be significantly reduced compared to conventional air-heated systems.
Oxy-fuel heated day tanks are primarily used for demanding glass types, higher quality requirements, or in modernization projects. The technical effort and operating costs for the oxygen supply are higher, but these are offset in many applications by process stability, energy savings, and improved glass quality.
Tableware and kitchen glass
Crystal glass, Soda-lime glass,
Lead crystal,
Glass containers
Soda-lime glass
Art glass
Crystal glass, Lead crystal
Colored glass
Conditioning
Forehearth for various glass types
Conditioning
Platinum Feeder System
Applications of day tanks
Day tanks are used wherever glass is produced not continuously, but in batches and with high flexibility. They are particularly suitable for production processes that require frequent glass changes, small to medium melt quantities, or special glass compositions.
Typical applications include the production of technical glass, special glass, colored glass, and optical glass. Day tanks are also used in development and pilot plants, as they allow for precise control of the melting process and good reproducibility of results. Due to the discontinuous operation, recipes can be specifically adapted without long transition phases or high material losses.
Depending on the glass type, quality requirements, and energy concept, day tanks can be designed as gas-heated, electric, or oxy-fuel systems. IWG Glasofenbau develops day tanks individually for the respective application area – from test facilities to industrial special glass production.
Technical features of day tanks
The technical equipment of day tanks is individually adapted to the glass type, melting capacity, and mode of operation. Central components are the combustion chamber, the melting tank, and the refractory materials used, which are matched to the respective thermal and chemical loads. Depending on the glass recipe, different tank materials and lining concepts are used.
An essential equipment feature is the respective heating concept. Day tanks can be designed as gas-heated, electric, or oxy-fuel systems. The choice of heating method influences the energy input, the temperature distribution in the glass bath, the emission behavior, and the controllability of the melting process. In addition, control and regulation systems can be integrated to specifically manage temperature profiles, heating rates, and holding times.
Other equipment features concern the furnace charging, the removal of the molten glass, and safety and monitoring devices. These include manual or automatic charging systems, defined tapping points, and measurement and control technology for process monitoring. IWG Glasofenbau designs day tanks in a modular way, so that the technical equipment can be precisely adapted to the respective production requirements.
Advantages and limitations of day tanks
The advantages and limitations of day tanks result directly from their discontinuous mode of operation as well as from the typical requirements of flexible glass production processes.
Advantages of day tanks
- High flexibility in glass formulas and batch sizes
- Suitable for frequent glass changes and special glasses
- Good process control due to discontinuous operation
- Compact design with a small footprint
- Comparatively manageable investment costs
- Precise temperature control possible depending on the heating concept
- Well-suited for development, pilot, and special applications
Limitations of day tanks
- Limited melting capacity compared to continuous glass melting furnaces
- Not suitable for large-volume mass production
- Higher specific energy costs per ton of glass
- Repeated heating and cooling phases required
- Sometimes higher personnel monitoring and operating effort
- Economic viability highly dependent on the application profile and energy costs
Whether a day tank is the appropriate solution therefore depends significantly on the desired production volume, the type of glass, and the operational framework conditions.
Service life, campaign operation, as well as modernization and retrofitting
Day tanks are typically operated in campaigns. The duration of a campaign is primarily determined by the type of glass, the operating temperature, the chemical load, and the refractory materials used. Compared to continuously operated glass melting furnaces, the service life of day tanks is generally shorter, but shutdowns, overhauls, and modifications are technically easier to plan.
An advantage of this operating principle is the good accessibility of the system. Refractory linings, heating components, and control technology can be specifically renewed or adapted during campaign changes. This allows day tanks to be modernized with relative flexibility, without requiring extensive structural interventions in the overall system.
Retrofits, for example in the areas of heating, measurement and control technology, or emission reduction, are also easily implemented with day tanks. This enables a gradual adaptation to changing production requirements, new glass formulas, or stricter energy and environmental regulations.
IWG Glasofenbau already considers campaign operation in the design phase to ensure ease of maintenance and long-term operational reliability.
Day tanks from IWG Glasofenbau
In-depth process understanding and practical experience are crucial for the design of glass furnaces. IWG Glasofenbau has many years of expertise in the planning, design, and implementation of day tanks for various types of glass and production requirements. The heating method, furnace structure, refractory materials, and control and regulation concepts are specifically tailored to the respective melting process.
Whether it's the new construction of a glass furnace, adaptation of existing systems, or technical retrofitting – IWG supports projects from conceptual planning to implementation during ongoing operations. The goal is a glass furnace that operates reliably, is economically designed, and meets the requirements for quality, flexibility, and service life.
Glass furnace construction – then IWG.