On 4 March 2020, the European Commission, through the adoption of the European Climate Law, set the objectives for the European Union to become ‘climate-neutral’ by 2050, establishing activities to achieve this goal. It was subsequently amended to include the interim target of reducing at least 55% of greenhouse gas (GHG) emissions by 2030.

The glass industry, highly energy-intensive and historically reliant on the combustion of fossil fuels such as natural gas and fuel oil, is facing strong political pressure to reduce CO2 emissions. The sector is known for its significant economic importance due to the wide range of processes and applications it can provide. However, in order to respond to growing pressures and actively contribute to the stated goals, improving the efficiency of existing production processes has become a top priority. This can be achieved through the exploration of new alternatives to traditional heating systems, aiming for what could be a groundbreaking change.

Glass Service, a long-time partner of the glass industry and attentive to environmental issues and change, is at the forefront of developing and providing technologies that can redefine the normal operations, sustainability and efficiency of distributors (DH) and forehearths (FH).

Electric forehearth

An highly effective and efficient solution for addressing the reduction of CO2 emissions from the glass distribution and conditioning zone before forming is an electric forehearth. It is equipped with a set of radiant elements that replace conventional feeder burners, streamlining the channel layout and reducing the effective height.

The radiant elements are made of silicon carbide (SiC), which proves to be the best option both as a construction material and for durability under operating conditions. What makes it particularly [effective] is its resistance to hot repair; this feature significantly reduces downtime during the replacement of one or more elements, contributing to minimising efficiency losses during maintenance interventions. The required heat is provided by the radiant elements through direct irradiation; these elements work as resistors powered by an electrical circuit that converts supplied electrical energy into thermal energy.

The temperature of the radiant elements is well calibrated to ensure that there are no significant differences in emission capacity compared to traditional gas/air flames, ensuring better thermal distribution along the forehearth and minimising the risk of reboiling bubble formation, a well-known issue in the glass industry that can compromise product quality.

The installation of radiant elements, when combined with Glass Service’s special superstructure design, offers an additional advantage: the ability to differentiate between centrally heated zones and side-heated zones of the forehearth. In each zone, it is possible to create mixtures of heating elements in the centre and on the sides to manage energy emission and homogenise glass temperature effectively. This level of control is essential to ensure the highest quality of the final product.

Despite its apparent simplicity and maturity, this technology faces some significant challenges when applied to forehearths. These challenges include: the low flow rate of oxygen-gas; the need to contain the costs of distribution devices (skids); regular cleaning of coal deposits from the burner nozzles; the design of low-power burners; the need to balance oxygen-gas flows across all burners in the zone, and the creation of burners with optimised maintenance-friendly designs. Despite these challenges, the advantages in terms of emissions reduction and energy cost savings make oxy-gas heating an enticing choice for the glass industry.

The system developed by Glass Service consists of a heat exchanger positioned at the exhaust of each zone’s chimney. Within the exchanger, both the heating of the heat transfer fluid and the preheating of the air/gas mixture occur simultaneously. Incoming ambient air is preheated at the expense of combustion gases and transfers heat to the fuel mixture through a serpentine system specifically designed by Glass Service to ensure optimal efficiency. The preheated mixture is then supplied to the burners’ manifolds. This system is designed to ensure safe and optimal temperature control for both the air and the fuel mixture.

Hydrogen can be used either as a blend with natural gas or as a 100% H2 system. With the NG/H2 blending technology, the transition can be gradual. The burners can operate with both natural gas and hydrogen.

From an environmental perspective, H2/O2 combustion completely eliminates CO2 emissions, a significant factor in achieving the EU 2030 and 2050 objectives.

Glass Service positions itself as a top-level partner for the implementation and success of this technology, having already developed and introduced a low-power 4 kW H2-O2 mixture-fed burner in addition to designing and building the dedicated combustion skid.

It is interesting to highlight that the gas-O2 technology can be easily adapted to a hybrid system, where the fuel consists of a blend of hydrogen and natural gas, without excluding the possibility of a future transition to the exclusive use of H2-O2 with zero CO2 emissions, once the cost of electrolysers becomes more affordable.

This flexibility is possible thanks to the similarity between the skids and burners used in different approaches.