There are many kinds of boiler refractory materials. According to the chemical mineral composition, they can be divided into silica, aluminum silicate, magnesium, carbon, zirconium, etc. The following are some common boiler refractory materials:
一、Silica refractory materials
Silica bricks: Containing more than 93% SiO₂, it is the main type of acid refractory bricks. It has good resistance to acidic slag erosion, but weak resistance to alkaline slag erosion, high load softening temperature, stable volume at high temperature, and is often used in coke ovens, glass melting furnaces, ceramic kilns, etc., and can also be used in some boiler parts that require acidic environments.
二、Aluminum silicate refractory materials
Clay bricks: Mainly composed of mullite (25%~50%), glass phase (25%~60%), cristobalite and quartz (up to 30%), the refractoriness is generally 1580℃-1770℃, with certain refractory and slag resistance, and relatively low price. It is a commonly used refractory brick for blast furnaces, hot blast furnaces, heating furnaces, power boilers, etc.
High alumina bricks: The mineral composition is corundum, mullite and glass phase. It can be divided into different grades according to the Al2O2 content. The higher the Al2O2 content, the higher the refractoriness and strength, and the better the resistance to slag erosion. It is often used in high-temperature parts of boilers, such as furnaces, furnace walls, furnace roofs, etc., and can withstand high temperatures and slag erosion.
Corundum refractory bricks: The Al2O2 content is not less than 90%, with corundum as the main phase. It can be divided into sintered corundum bricks and fused corundum bricks. It has the advantages of high refractoriness, high bulk density, and good wear resistance, but poor thermal shock stability.
Mullite bricks: Mullite is the main crystal phase, with good refractoriness, thermal shock stability and creep resistance, high high temperature strength, and strong resistance to slag erosion. It can be used in high-temperature superheaters, reheaters and other parts in boilers.
三、Magnesia refractory materials
Magnesia bricks: With magnesium oxide as the main component, they have high refractoriness, good resistance to alkaline slag and iron slag, and can withstand high temperature and erosion of alkaline slag, but poor thermal shock resistance. They are mainly used in alkaline steelmaking furnaces, cement kilns, etc., and can also be used in some boilers that process alkaline materials.
Dolomite bricks: Made of dolomite as the main raw material, they have good resistance to alkaline slag erosion and stable high-temperature performance. They can be used in the alkaline area of the boiler, such as the furnace lining for processing high-alkaline fuels.
四、Carbon refractory materials
Graphite products: They have extremely high refractoriness, good thermal stability and conductivity, small thermal expansion coefficient, excellent thermal shock resistance, but are easily oxidized. They are often used in high-temperature reducing atmosphere environments, such as the lower part of the blast furnace body, hot blast furnace checker bricks, etc. They are also used in some special small boilers or parts that require high thermal conductivity.
Silicon carbide bricks: Made of silicon carbide as raw material, it has the advantages of high temperature strength, good wear resistance, high thermal conductivity, good thermal shock stability, etc. It works well in high temperature oxygen-free atmosphere and can be used in high wear parts such as cyclone separators and return feeders of circulating fluidized bed boilers.
五、Zirconium refractory materials
Zirconium oxide bricks: With zirconium oxide as the main component, it has extremely high melting point, good thermal shock stability and chemical stability, and can maintain good performance under ultra-high temperature and special corrosive environment. It can be used for some key high temperature parts of boilers, such as superheater tubes, reheater tubes, etc., but the price is relatively high.
六、Amorphous refractory materials
Casting material: It is composed of refractory aggregate, powder, binder and admixture, etc. It has good fluidity after adding water and stirring, and can be constructed by pouring, vibration and other methods. It has good integrity and is suitable for various complex shapes of boiler parts, such as furnace, flue, cyclone separator, etc.
七、Refractory castables
Plastic materials: materials include semi-silica, clay, high alumina, zircon, carbon, etc., which are made by adding plasticizing materials and binders. They are plastic and easy to construct. They can be used to repair boiler linings and can also be used as the overall lining of some small boilers.
KERUI Refractory can provide all types of boiler refractory materials, if you have any questions or needs, please contact us.