In the glass industry, the heat-up process of the glass furnace is a critical step that directly affects the furnace’s service life, glass quality, and production efficiency. However, this process often faces challenges. If problems are not identified and addressed in time, they can cause irreversible damage to the furnace and disrupt the stability of the entire production line.
This article outlines the most common problems encountered during the glass furnace heat-up process and provides practical insights to help industry professionals prevent and solve these risks effectively.
One common issue during the heat-up phase is the sagging of the main arch bricks in the melting section. This problem may result from:
Inconsistent brick sizes
Improper brick placement
Excessive mortar joint gaps
Overuse or uneven tightening of steel pull rods
To fix this, early detection and professional maintenance are essential. For minor sagging, thin steel plates can be used for temporary support. However, if sagging depth exceeds half the brick thickness, reinforcement is required—such as adding a new arch brick above the sunken area to maintain structural integrity.
Arch deformation, including upward bulging or longitudinal cracking, is often caused by:
Excessive heating rates
Uneven or delayed tightening of steel rods
Temperature differences on both sides of the arch
Poor expansion gap design or blocked expansion joints
Immediate adjustment of steel rod tension is needed to restore balance. Temporary measures like placing pressure bricks or steel blocks can help push the arch back into place. However, long-term resolution requires root-cause analysis, particularly checking whether debris or tight joints in expansion gaps are restricting thermal movement.
During the overfire stage, especially between 1100–1200°C, thermal shock can cause mullite or fused cast AZS bricks to crack if the temperature rises too quickly.
To prevent this:
Follow a controlled heating schedule
Avoid rapid temperature rises, especially after overfire
Use calcium silicate boards for temporary insulation in winter to reduce inner-outer wall temperature differences, then remove them once heat balance is achieved
Several steel components in the furnace are vulnerable during heat-up, such as:
Pull rods in the small furnace slope arch
Vertical rods in the regenerator
Main arch rods
Anchor bolts near the breast wall and flat arches
These parts endure both thermal and mechanical stress. Regular inspections and timely repairs are critical to maintaining furnace stability.
As the temperature increases, thermal expansion of the brick structure requires gradual adjustment of pull rods. Operators must consider:
Expected arch sinking after dismantling the formwork
Historical sinking behavior of old arches
During heating, the span of the arch increases, raising its height by 50–100 mm. After heating is complete, ensure all rods are re-tightened. This prevents deformation and preserves furnace shape.
Leakage in the flue system can disrupt temperature control. Before ignition, thoroughly inspect the flue, especially:
Damper valves at heat recovery inlets/outlets
Combustion air dampers
Flue ash pit seals
If leaks are found during operation, seal them immediately using fireclay or temporary insulation to ensure stable flue temperatures and consistent kiln performance.
At the melting end of the furnace, I-beam steel columns may lean toward the throat area due to:
Lack of expansion space under leveling bricks
Unbalanced wall pressure
To address this, install additional I-beams at the throat to act as lateral supports. Reinforcing walls on both sides with vertical steel columns also improves structural stability and compensates for thermal expansion.
During regenerator heating, rapid temperature rise may cause wall deformation if:
Expansion joints are blocked
Insufficient preheating or insulation causes uneven heat transfer
To prevent this:
Ensure all expansion gaps are clean and functional
Apply temporary insulation (e.g., ceramic fiber blankets or boards) before firing
Heat the furnace slowly and evenly
The glass furnace heat-up process is filled with potential risks. If not managed carefully, these issues can impact furnace longevity, product quality, and operator safety.
Through proper planning, technical monitoring, and preventive maintenance, these problems can be effectively controlled—leading to improved operational stability and long-term energy savings. By implementing best practices in furnace commissioning, glass manufacturers can boost efficiency and support sustainable industry development.
📩 For expert support or insulation solutions for your glass furnace, feel free to contact our team at service@firebirdref.com, or reach us via the Contact section in the navigation bar.
