Russian
High-alumina fire tunnel bricks for heating furnaces are high-alumina shaped refractory bricks specifically designed for high-temperature zones with intense gas flow erosion, such as fire tunnels, flues, combustion chambers, and burner zones in heating furnaces (eg, walking beam, pusher-type, and car-bottom furnaces). Their advantages include high-temperature resistance, thermal shock resistance, resistance to flue gas corrosion, and high strength, making them ideal refractory materials for lining heating furnaces in the steel, metallurgy, and machinery industries.
ⅠMaterial Grades (Classified by Al₂O₃ Content)
For fire tunnel environments, Grade II (LZ-65), Grade I (LZ-75), or thermo-shock-resistant/low-creep high-alumina bricks are typically selected:
Grade | Al₂O₃ (%) | Refractoriness | Load Softening (T₀.₆) | Cold Crushing Strength | Typical Applications in Fire Tunnels |
LZ-55 (Grade III) | ≥55% | ≥1750℃ | ≥1450℃ | ≥45 MPa | Low-temperature sections, non-erosive flue passages |
LZ-65 (Grade II) | 65–75% | ≥1770℃ | ≥1500℃ | ≥50 MPa | Mainstream: Medium/high-temperature fire tunnels, walls, arches |
LZ-75 (Grade I) | ≥75% | ≥1790℃ | ≥1520℃ | ≥60 MPa | High-temperature sections, burner zones, soaking zones, furnace crowns |
Thermo-Shock-Resistant High-Alumina Brick | 60–75% | Same as Grade II | ≥1480℃ | ≥55 MPa | Frequent start-stop cycles, zones with rapid temperature fluctuations |
Low-Creep High-Alumina Brick | ≥65% | ≥1770℃ | ≥1550℃ | ≥60 MPa | Long-term high-temperature service, load-bearing arches, suspended ceilings |
II. Key Performance Requirements for Fire Tunnels
High Refractoriness: 1750–1790°C, with safe long-term service at 1250–1450°C.
High Load Softening Temperature: Resistant to collapse/deformation, ideal for vaults/suspended ceilings.
Excellent Thermal Shock Resistance: Withstands 15–30 cycles of 1100°C water quenching, adapting to frequent startups/shutdowns and rapid temperature fluctuations.
Flue Gas Corrosion Resistance: Resists erosion from iron oxide scale, SO₂, and dust, with a service life 30–100% longer than fireclay bricks.
High Strength: Cold crushing strength of 45–70 MPa, ensuring abrasion resistance and anti-gas scouring.
Minimal Linear Change: Reheating linear change of ±0.4%, ensuring stable masonry and crack-free joints.
III. Application Zones in Heating Furnace Fire Tunnels
1.Combustion Chambers/Burner Ports
Conditions: 1300–1450°C, direct flame impingement, severe thermal shock.
Selection: LZ-75, thermal shock-resistant high-alumina bricks, burner blocks.
2.Heating/Soaking Zone Fire Tunnel Walls & Vaults
Conditions: Continuous high temperatures, strong gas scouring.
Selection: LZ-65/LZ-75, hanging bricks, vault bricks.
3.High-Temperature Flues & Exhaust Outlets
Conditions: 800–1300°C dust-laden hot flue gas.
Selection: LZ-65, dense high-alumina bricks.
4.Furnace Bottoms, Sliding Rails, Walking Beam Insulation Linings
Conditions: Load-bearing + high temperatures + iron oxide scale erosion.
Selection: LZ-65/high-alumina abrasion-resistant bricks.
IV. Standard & Special-Shaped Brick Types
Standard Bricks: 230×114×65/75 mm (for straight walls).
Fire Tunnel Specialized: Wedge bricks (vaults), hanging bricks (roofs), tongue-and-groove bricks, burner blocks, corner bricks.
Customization: Fire tunnel checker bricks and composite bricks processed per furnace drawings.
V. Selection & Installation Guidelines
Selection Criteria
T >1350°C, severe thermal shock: LZ-75/thermal shock-resistant high-alumina bricks.
1250–1350°C, continuous operation: LZ-65/low-creep high-alumina bricks.
T <1250°C, mild erosion: LZ-55.
Masonry Recommendations
Use high-alumina refractory mortar (Al₂O₃ ≥65%) with joint thickness ≤1–2 mm.
Prioritize hanging brick structures for vaults/ceilings, paired with anchoring bricks.
Avoid direct contact with strongly basic bricks (eg, magnesia-carbon bricks) to prevent chemical reactions.
VI. High-Alumina vs. Fireclay Bricks (Why Choose High-Alumina for Fire Tunnels?)
Parameter | High-Alumina Brick | Fireclay Brick |
Refractoriness | 1750–1790°C | 1580–1670°C |
Load Softening | Point 1450–1550°C | 1300–1400°C |
Thermal Shock Stability | Superior (less spalling) | Inferior |
Corrosion Resistance | High (iron scale, flue gas) | Low |
Service Life | 0.5–1× longer | Baseline |
VII. Zhengzhou Kewei Refractories’ Fire Tunnel Solutions
Product Range:
LZ-65/LZ-75 standard/special-shaped fire tunnel bricks.
Specialized Grades:
Thermal shock-resistant high-alumina bricks (with andalusite/sillimanite) for furnaces with frequent startups/shutdowns.
Low-creep high-alumina bricks for long-term high-temperature large-scale furnace vaults.
Support Services:
High-alumina refractory mortar, fire tunnel construction guidance, and optimized brick design.
