Dr Hartmut Hegeler* outlines Sorg’s sustainable glass melting technology, and how it can help glassmakers to reduce their energy and emission consumption.
In this second piece in a three-article series by the Sorg Group, we will discover how glassmakers can utilise already existing and approved technologies to reduce emissions and start their journey to carbon neutral glass melting.
It’s the word on everyone’s lips and a complex issue that’s at the forefront of our minds. The call for sustainability is a sign of the times we live in, with environmental legislation and modern society demanding immediate answers.
Plant manufacturers and operators are positioning themselves accordingly, selling or requesting sustainable products and technologies that will benefit their customers, the glass industry and of course, the future of our planet.
But what does sustainability mean for the glass industry? First and foremost, it is the reduction of energy consumption, and in turn, emissions. It’s the raison d’être for energy-intensive thermal processing industries like ours.
Driven by energy reduction, glass quality improvement and lower emissions, the Sorg Group is on a mission to help glassmakers reach net zero by creating furnaces without compromise.
The family-owned business has a well-charted history of sustainable melting and using renewable energies in glass manufacturing, especially when it comes to furnace development.
Low NOx melter
In the mid-1980s, legislative measures were introduced to drastically reduce NOx emissions. Sorg used physical modelling as an important tool to develop the LoNOx Melter, which was still common at the time.
The result was a melter with external cullet preheating, internal batch preheating and internal post-combustion.
To reduce the NOx components in the exhaust gas, partition walls in the furnace superstructure divided it into several zones.
Sorg’s engineering team planned and constructed these complex assemblies to ensure full functionality, forming the basis for many later design features and applications, including in the Clean Melter.
The LoNOx Melter technology allows for furnace operation at NOx emissions below 400 mg/Nm³ solely through primary measures.
This is achieved by combining separation walls, along with both internal and external preheating, and recuperators, which together contribute to reduced energy consumption.
Pic 2. Vertical Super Melter (VSM) – interior.
Pic 3. Vertical Super Melter (VSM) – exterior.
Batch3 integrated concept
Sorg’s Batch Preheater solved the problem of clumping during preheating, when water released from the soda ash reacts with other raw materials and creates concrete phases.
In combination with the IRD (Increased Radiation Doghouse) and the EME-NEND (No Emission No Dust) batch charger, the Integrated Batch3 Concept was born.
The combination of batch and melting know-how offers reduced NOx, CO2, energy consumption, dusting and pull increase, less induced air, and an optimal batch distribution in the furnace – all resulting in better glass quality and considerable cost savings.
The IRD design has a much wider and higher superstructure than a conventional doghouse.
Heat loss is lower because the doghouse is closed, while the larger furnace opening allows in more radiation to ensure that the surface material is glazed before entering the melter, with considerably less dust and carry-over.
Compared to other furnaces with batch preheating but without the IRD Doghouse and EME-NEND Batch Charger, the Batch3 Integrated Concept reduces carry over in the port neck, regenerative chamber, and checker back to the regular levels expected in furnaces without batch preheating.
The combination of the EME-NEND batch charger and the IRD doghouse achieves a completely sealed doghouse.
Despite this sealing, it still allows for influence and control over the batch pattern.
Advanced Regenerator Design
The Advanced Regenerator Design (ARD) facilitates a more cost-effective transition from traditional melter furnaces to highly efficient regenerative furnace types, including those used in civil works such as steelworks, groundworks, and regenerator pits.
This design (Pic 1 above) also makes it easier and more economical for glass producers to switch from energy-intensive melter types to highly efficient endport furnaces.
Its design is also suitable for high groundwater levels or rock formations where the foundation depth limits the regenerator height.
There are no design constraints that limit the furnace’s efficiency.
Other benefits include a shorter construction time and a more homogenised flow of the waste gases through the regenerator packing.
Electric melters
Early on, Sorg saw the huge potential of all-electric furnaces.
Although few were available at this time, they had two major disadvantages.
Initially, a design with an open superstructure led to significant energy losses and elevated dust levels in the surrounding environment.
And secondly, batch charging from the side over the complete melting area meant a large space requirement for the charger.
To answer this, Sorg created the Vertical Super Melter (VSM): a vertical, fully electric melter with batch charging from the top through a closed superstructure (Pic 2 above).
Charging the batch from the top closes the batch cover (Pic 3 above), making this furnace type particularly suitable for melting glass types with highly evaporative components, such as fluorine or boron.
In 1971, the first all-electric VSM was installed and commissioned, and by 1977 the rotating crown for batch charging was introduced.
In 1988, the top-electrodes with swing-bar for easy maintenance was developed on the VSM, and in 2003 the largest all-electric VSM was commissioned at 180 t/d for container glass applications.
The VSM has zero emissions (NOx, CO2 out of combustion) when green electricity is used.
Clean Melter
With the invention of mathematical modelling in the early 2000’s, Sorg was among the early adopters, utilising it to enhance and innovate existing and new technologies, furnaces, and processes. This approach supported the development of its latest innovation, the hybrid Clean Melter (Pic 4).
Pic 4. Sorg’s Clean Melter. Pic Source Ardagh Glass Packaging
The pioneering VSM delivered many sustainable advantages, but its limitations were a maximum pull of 200 t/d, no reduced glasses and sensitivity to raw material deviations and modifications.
Based on Sorg’s experience with highly boosted fossil-heated furnaces and all-electric furnaces, the Clean Melter looks like a melter-type furnace.
With its segmented superstructure, it is the first of its kind that incorporates proven Sorg design technologies like bottom boosting, oxygen heating and a refining shelf.
However, the Clean Melter can produce up to 400 tpd, as well as soda-lime glasses, without the restrictions of other technologies such as the VSM.
A flexible range of energy input is also possible, from 80% fossil / 20% electric to 20% fossil / 80% electric.
In addition, with much greater output comes much lower NOx and CO2 emissions; where green hydrogen, biofuels and synthetic fuels are used, the furnace can operate with zero CO2 emissions.
Zero emissions, zero compromises
The European Energy Crisis and the Paris Climate Accord mandate a 60% reduction in carbon emissions by 2030 and aim for carbon neutrality by 2050.
The examples mentioned illustrate Sorg’s longstanding commitment to providing glassmakers with technologies designed to lower emissions, energy consumption, and costs.
From designing its first all-electric furnace over 50 years ago to launching the first hybrid furnace for large tonnages, Sorg’s technologies have helped to shape sustainable glass production.
Whether it’s increasing recycled content or optimising equipment to run on higher amounts of cullet, the Sorg Group is more committed than ever to developing new ways to improve the energy efficiency of glass plants and reduce carbon across the whole melting process.
*Marketing Manager, Sorg,
Lohr am Main, Germany
