The Role of Refractory Bricks in High-Temperature Industry
In industrial production, almost all high-temperature furnaces require refractory brick products, from glass factories and iron and steel plants to refining furnaces and chemical reactors. The bricks protect the furnace shell, retain heat and resist the attack of slag, gases and mechanical loads at high temperature. The specific use depends on the type of brick, because each type has its own temperature limit, chemical resistance and mechanical properties. Selecting the correct brick for each zone of the furnace is the first step in achieving a long, predictable campaign.
Ordinary Refractory Bricks
Ordinary refractory bricks must comply with the specification for physical and chemical indicators, dimensional tolerance and product section quality, including limits on cracks and layer separation. They are used for refractory masonry of furnace linings, furnace walls, furnace bottoms and flues, generally at service temperatures below about 1250 degrees Celsius. In combustion chamber parts, their use is allowed above 1400 degrees Celsius. This type is the economical baseline for moderate-temperature zones where chemical attack is not severe.
High Alumina Bricks
High alumina bricks are specified by the same kind of physical, chemical and dimensional requirements. They are used in general kiln heat-resistant and wear-resistant areas, in masonry under heavier loads, for burner bricks and for special masonry requirements. Typical applications include the high-temperature area of the combustion chamber vault, where the allowed use temperature is in the range of about 1300 degrees Celsius and above depending on the grade. The higher alumina content gives better refractoriness, load-bearing capacity and resistance to attack than ordinary fireclay bricks.
Lightweight Clay Bricks
Lightweight clay brick is also a kind of refractory brick, with its own physical and chemical indicators, dimensional tolerances and product section requirements. It is used as a kiln lining in conditions with high-temperature slag and aggressive gas attack, and depending on the capacity of the kiln it is used in the range of about 1150 to 1400 degrees Celsius. Its low density reduces heat loss and furnace weight, which is why it is often chosen for insulating zones behind denser hot-face materials.
Corundum and Low-Silicon Fused Corundum Bricks
General corundum bricks are suitable for working pressures below about 3 MPa and are used for the fire-face lining of heavy-duty gasifiers, for important parts of salt-laden wastewater incineration units, and for radiant burner bricks operating at high temperature. Their service temperature range is below about 1600 to 1670 degrees Celsius. Low-silicon fused corundum bricks are suitable for strongly reducing atmospheres, melts with high hydrogen content and conditions with high-temperature water vapor, such as the collector pipe lining of the first section and the lining of the second section of conversion furnaces in large ammonia synthesis plants, as well as other high-temperature furnace linings. Their use temperature is also in the range below about 1600 to 1670 degrees Celsius.
Selecting the Right Brick
The correct brick is selected by matching the service temperature, atmosphere, slag composition, mechanical load and installation method to the brick type and grade. The buyer should confirm the alumina or other main component content, bulk density, apparent porosity, cold crushing strength, refractoriness under load and dimensional tolerance against the specification, and should request test certificates for the delivered lot. Working with a supplier that can document these properties helps avoid premature lining failure and unplanned furnace downtime.
FAQ
Q: Where are ordinary refractory bricks used?
A: They are used for furnace linings, walls, bottoms and flues at temperatures generally below about 1250 degrees Celsius, and in combustion chamber parts above 1400 degrees Celsius.
Q: What are high alumina bricks suitable for?
A: They are used in heat-resistant and wear-resistant kiln areas, masonry under heavier loads, burner bricks and combustion chamber vaults, typically around 1300 degrees Celsius and above.
Q: What is the service range of lightweight clay bricks?
A: Depending on kiln capacity, lightweight clay bricks are used in the range of about 1150 to 1400 degrees Celsius, mainly in linings exposed to slag and aggressive gases.
Q: Where are corundum bricks used?
A: They are used for gasifier fire-face linings, salt-laden wastewater incineration units and radiant burner bricks, at temperatures below about 1600 to 1670 degrees Celsius and pressures below about 3 MPa.
Q: What specifications should a buyer check when ordering refractory bricks?
A: Check the main component content, bulk density, porosity, cold crushing strength, refractoriness under load and dimensional tolerance, and request test certificates for the delivered lot.
