86th Glass Problems Conference (GPC)
The Glass Problems Conference (GPC) returns with its 86th edition in the “Glass City” of Toledo, from October 6 to 9, 2025.
This event is organized by the Glass Manufacturing Industry Council (GMIC) and Alfred University, and proudly endorsed by The American Ceramic Society.
Join SEFPRO at GPC 2025
Abstract 1: Increasing Melter Throughput, Efficiency, and Life through Design of Mullite Crown Performance
Crowns are a critical component of glass furnaces, functioning as the roof to contain the glass and vapors and keeping the heat inside the furnace for energy efficiency. The operating temperatures for crowns are among the highest in the furnace and there is high potential for creep deformation over time. Thus, the most critical properties for crown refractories include thermomechanical stability (refractoriness under load and creep rate), heat conduction, and resistance to vapor corrosion. But an often-overlooked attribute of crowns is the ability absorb and re-emit radiation back to the batch for melting efficiency.
Traditional silica crowns are limited to a maximum operating temperature of 1600°C, above which the creep is very high, and the emissivity is very low, causing both structural problems and inefficient heat transfer to the melt. SEFPRO offers a line of mullite refractories designed for the reinforcement fiberglass and specialty glass markets. These products have excellent creep resistance and improved emissivity compared to these traditional silica crowns, thus increasing furnace lifetime and improving heating efficiency.
As glassmakers desire to push the operating temperature of the furnace even higher for increased throughput, the creep resistance and refractoriness under load of the crown become even more critical. SEFPRO BP Mullite REC is a specially tailored refractory with a creep rate ~50% lower than BP Mullite between 1600-1700°C, allowing furnace operation to increase by 50 degrees, well over what a silica crown could handle. Alternatively, the furnace operating temperature could remain the same, but more insulation added to reduce the heat loss through the crown.
Emissivity is also a critical parameter to improve energy efficiency of the crown. SEFPRO BP Mullite has an improvement in emissivity compared to silica, allowing the furnace to transfer heat to the melt more efficiently.
The SEFPRO BP Mullite refractory family offers solutions for crowns that provide improved emissivity and excellent creep resistance compared to traditional silica crowns. These refractories can provide the ability to comfortably increase the operation temperature, resulting in higher throughput with reduction in energy losses through the crown.
Abstract 2: From Siemens to Simulation: Understanding and optimizing regenerators
Reducing energy losses and recovering energy from flue gases are two key principles that need to be followed in the design process of an efficient glass furnace. In 1860, the first regenerative-fired furnace was built by Friedrich Siemens which utilized two chambers filled with checkerwork to store thermal energy from the flue gases. By reversing the combustion process every 20 minutes, one chamber preheats the combustion air while the other recovers the energy from the flue gases. Although the core operating principle has remained unchanged for over 165 years, advancements in refractory materials have significantly improved the regenerator and furnace performance. Modern refractories allow for higher preheating and melting temperatures, leading to shorter melting times, enhanced energy efficiency, lower fuel consumption and CO2 emissions, as well as, extended furnace lifetimes.
In addition to material composition improvements, optimizing refractory shapes and their arrangement in the checkerwork has emerged as a critical area of innovation. SEFPRO, a leading refractory supplier, has conducted extensive research to enhance heat transfer efficiency and prolong regenerator lifetimes by refining the design of refractory components. However, real-world comparisons between standard chimney blocks and SEFPRO Cruciforms® within the same furnace are challenging as regenerator chambers are built together with the melter, thus switching between different checker work setups is impossible. To address this limitation, SEFPRO partnered with Glass Service in 2022 to systematically investigate the heat transfer and flow characteristics of different checker types using detailed computational fluid dynamics (CFD) simulations.
Over the past 2.5 years, Glass Service has developed a robust methodology for simulating various checker designs in detail. By deriving Darcy porous wall parameters, we have successfully integrated these findings into Glass Service’s proprietary CFD simulation software, Glass Furnace Model. This approach enables more accurate regenerator simulations by accounting for local flow velocities and temperatures. The study's results provide valuable insights for selecting optimal checker types based on specific operating conditions, bringing regenerator design closer to real-world performance.
This research represents a significant step forward in improving glass furnace efficiency through advanced simulation techniques and innovative refractory designs. By leveraging CFD tools to optimize heat transfer and flow dynamics, manufacturers can achieve greater energy savings and operational reliability.
