Burner is an important equipment component of cement kiln firing system. In addition to factors such as clinker quality, refractory life in the kiln, clinker coal consumption, environmental emissions and so on, the durability of castable lining of burner will greatly affect the selection and collocation of burner. After the equipment is put into operation, the damage phenomenon of refractory castable such as peeling, crack and spalling often appears.
The first layer is pale yellow with obvious corrosion phenomenon, indicating that liquid phase is generated on the surface of castable. The second layer is white and has the most loose structure. The castable has completely deteriorated and is basically the crystallization accumulation of alkali and salt. The third layer is light black with dense structure, and aggregate particles in castable components can be seen. The 4 layers are gray with dense structure and no crystalline material is found. The matrix part and aggregate particles of castable can be clearly seen.
The mineral composition of the first layer is mainly anorthite (CAS₂), wollastonite (C₂S) and potassium feldspar (KAS6) phases. The analysis shows that the wollastonite (C₂S) in this position is caused by the adhesion of cement clinker on the castable surface of burner liner. Calcium feldspar (CAS₂) generation may be due to cement clinker in the calcium material penetration into the lining castable, and castable matrix part of the reaction generated. The production process of potassium feldspar (KAS6) may be that the vapor phase substance containing K is volatilized from the basic substance in the original combustion material during the high-temperature calcination process, which condenses and deposits on the surface of the burner castable after encountering with the substrate of the castable, and is generated by reaction with the matrix of the castable at high temperature. Both minerals are low melts, and liquid phase is produced by melting at high temperature, resulting in corrosion of the lining surface, which reduces the surface strength of castable and accelerates its wear.
New compounds such as KAS₂(white garnet) and KAS₄(potassium Nenet) from salt K that has infiltrated into the castable react with the matrix to form volume expansion, changing the composition and structure of the matrix and causing damage to the castable. On the other hand, after K salt penetrates into castable matrix, it gradually cools and deposits in the process of temperature reduction. Due to its low volume density, volume expansion will occur after deposition, resulting in damage of castable matrix. And because its mechanical properties are completely different from the original matrix, it may fracture or damage the castable matrix due to volume change under the action of thermal stress or temperature fluctuation. Fe₂O₃, Na₂O, MgO and other oxides as shown in Table 1.
EBICO will attend Thailand's Premier Power Generation & Electric Exhibition...
How a bowl of Baixiang good noodles is born? About 1.8 million years ago, humans learned to cook food with purposeful control of fire. The use of fire has made unprecedented progress in human health and life, and Darwin also called cooking the most important invention of mankind after language....
