In the glass industry, float glass furnaces and unit furnaces are core production equipment. The quality of their refractory masonry construction directly impacts the furnace's service life, the quality of the glass products, and production efficiency. This article systematically analyzes the key technical aspects of masonry construction for float glass furnaces and unit furnaces, including refractory material selection, masonry construction processes, key process controls, and quality acceptance standards.

01

Refractory Material Selection and Matching

1. Float Glass Furnace Refractory Materials

Critical areas of a float glass furnace, such as the melting, clarification, and cooling sections, must withstand the erosion of high-temperature molten glass and the erosion of flames. Therefore, the performance requirements for refractory materials are extremely high.

Melting: Fused zirconium-alumina bricks (AZS bricks) are typically used. They offer strong resistance to molten glass and are suitable for high-temperature melting areas. For example, high-quality silica bricks are often used for the melting section's crown (furnace cover). These bricks have a high refractoriness under load and excellent high-temperature impact resistance. They form a protective metamorphic layer below 1600°C, slowing down erosion.

In the clarification section, high-alumina bricks or magnesia-alumina bricks are used to meet the chemical stability requirements of the refractory materials during the clarification of bubbles in the molten glass.

In the cooling section, clay bricks or lightweight insulating bricks are used to reduce heat loss while meeting structural strength requirements.

2. Unit Kiln Refractory Materials

As the core equipment in glass fiber production, the unit kiln's refractory materials must withstand the high temperatures, high-velocity airflow, and special operating conditions of molten glass drawing.

In the melting section, dense chrome bricks or dense zirconium bricks are primarily used, offering superior erosion and high-temperature resistance to ordinary refractory bricks. For example, the tank wall bricks, which must withstand the high temperatures of the molten glass, are typically made of fused zirconium corundum bricks, with cracks less than 1mm to minimize leakage.

Passageway System: Large kaolin bricks or zirconium ramming material are used as a sealing layer to prevent molten glass from penetrating the clay brick layer, which has poor corrosion resistance. Fusion-cast bricks are used in the runners. The casting surface must strictly avoid contact with the molten glass, and the brick joints must be sealed with tape to prevent debris from entering.

02

Masonry Construction Process and Key Techniques

1. Construction Preparation and Benchmark Alignment

Baseline Setting: Using the longitudinal centerline of the melting furnace, the centerline of the No. 1 small furnace, and the design elevation as references, precise measurements are performed using a laser positioning device, with an error control within ±1mm. For example, before laying the large arch of the melting section of a float glass furnace, a thin line is drawn between the two columns to ensure consistent mortar thickness for each row of bricks.

Steel Structure Acceptance: The elevation and levelness of the main beams, secondary beams, and flat steel are checked. The allowable elevation deviation for the top surface of the main beam is -3mm, and the allowable elevation deviation for the top surface of the secondary beam is -2mm. This ensures the verticality of the pool wall bricks after laying.

2. Bottom and Wall Masonry

Bottom masonry: Dry masonry is used, with bricks laid symmetrically from the centerline to the sides. Brick joints are filled with straw paper, then removed and sealed with tape. For example, the allowable deviation in the total thickness of the float glass furnace bottom is -3mm. A layer of zirconium ramming material is laid on the large kaolin bricks at the bottom as a sealing layer.

Wall masonry: The bottom bricks are laid first and leveled, then laid upwards layer by layer. Multi-layer wall bricks should be laid from the inside out to ensure accurate dimensions within the furnace. For example, corners of unit furnace walls must be strictly prohibited. Straight joints should be formed parallel to the length of the wall, with a gap of no more than 5mm.

3. Arch and Parapet Masonry

Arch masonry: The "beating method" is used, using a slurry with high viscosity and strong adhesion. Brick joints should be kept to approximately 2mm. For example, the arch of a float glass furnace is built simultaneously from both sides toward the center, with continuous work time no longer than 24 hours. After completion, grouting is required to ensure full brick joints.

Breast wall construction: Hook bricks are dry-laid, with the upper surface leveled using a spirit level. Expansion gaps of 1-1.5mm are left between each brick, and the gaps are sealed with horse manure paper. For example, when constructing the breast wall of a unit kiln, a line is drawn across the cast iron plate for leveling, and a thin layer of mortar is applied to prevent toppling due to an unstable center of gravity during construction.

4. Expansion Joints and Sealing

Expansion Joint Layout: The expansion joint width is calculated based on the linear expansion coefficient of the refractory material. Typically, a 5mm expansion joint is allowed per meter of masonry. For example, in the flue wall of a float glass furnace, an 8mm expansion joint is left every 2 meters. Expansion joints are staggered, and the outer layer is constructed with clay bricks; insulation bricks are not permitted.

Sealing: After completion, the kiln interior surface must be cleaned and vacuumed to remove debris. For example, the joints between bricks in a unit kiln are inspected with a feeler gauge equal to the specified thickness of the brick joint being inspected. Flatness is checked in all directions using a 2-meter straightedge to ensure there are no gaps or unevenness.

03

Quality Acceptance Standards and Common Problem Control

1. Quality Acceptance Standards

Brick Joint Control: The joints between bricks in special-class masonry must not exceed 0.5mm, those in Class I masonry must not exceed 1mm, those in Class II masonry must not exceed 2mm, and those in Class III masonry must not exceed 3mm. For example, the joints between large arched bricks in the melting section of a float glass furnace must be controlled within 1mm, and mortar fullness must be 100%.

Verticality and Horizontality: The verticality error of the wall must not exceed 2mm per meter of height, and the verticality error across the entire height must not exceed 5mm. For example, after the brickwork of the unit kiln is completed, verticality must be checked with a laser plumb line to ensure compliance with design requirements.

2. Common Problem Control

Brick Joint Leakage: This can be addressed by optimizing the mortar mix and masonry techniques. For example, float glass furnaces use silica refractory slurry, which has fine particles and strong adhesion, effectively reducing leakage between bricks.

Masonry deformation: This is addressed by strictly controlling the masonry sequence and support structure. For example, when constructing the large crown of a unit furnace, sufficient support points must be provided on the crown base to ensure that the crown base does not deform under load.

04

Innovative Technologies and Future Trends

As the glass industry develops towards larger-scale and intelligent construction, refractory masonry technology is also undergoing continuous innovation. For example, 3D scanning technology is used to accurately measure masonry and optimize masonry plans through BIM models; new nano-modified refractory materials are being developed to improve corrosion resistance and high-temperature resistance; and intelligent monitoring systems are being introduced to monitor masonry temperature and stress distribution in real time, enabling preventive maintenance.

In the future, masonry technology for glass melting furnaces will place greater emphasis on environmental protection, energy conservation, and longevity. For example, efforts are underway to promote the use of lightweight insulating bricks with low thermal conductivity to reduce heat loss; develop recyclable refractory materials to reduce resource consumption; and leverage digital technology to precisely control the masonry process, improving construction efficiency and quality.

The masonry construction of glass melting furnaces is a systematic project, requiring comprehensive approaches encompassing refractory material selection, masonry process control, and quality acceptance standards. Through continuous technological innovation, process optimization, and rigorous management, the lifespan and production efficiency of furnaces can be significantly extended, providing strong support for the high-quality development of the glass industry.