1) Grate cooler low wall and top prefabricated parts
The position of the grate cooler is special, the flue gas composition is complex, the temperature is high, the wind speed is high, and the dust in the flue gas is mostly small particles of cement clinker, which are not only large in volume but also high in hardness, and cause serious erosion and erosion of refractory materials. Therefore, the phenomenon of over-temperature or burn-through in the grate cooler is very common, so the reasonable selection of refractory materials in this part and the construction quality are very important. The prefabricated parts in this part usually use high alumina bauxite, silicon carbide, etc. as aggregates, use calcium aluminate cement as binder, add ultrafine powder, admixtures, and add a certain amount of heat-resistant steel fibers, pouring according to low cement According to the construction specification, the prefabricated parts are made into suitable shapes.
The shape, size and structural form of prefabricated parts are related to their use parts. For the prefabricated parts for the grate cooler low wall, in order to improve the stability of the low wall structure, the upper and lower surfaces of each prefabricated part are respectively provided with grooves or tongues. Through the combination between the tongue and the groove, the sliding between the blocks is restricted, and the integrity and stability of the masonry structure are improved. For the top of the grate cooler, especially in a high temperature area, the prefabricated parts can be welded or bolted to the top through anchors, or they can be directly connected by hanging on the steel plate.
2) The prefabricated part of the tertiary air duct bend
The lining of the tertiary air duct bend of the cement kiln not only needs to withstand the scouring of the high-speed tertiary air flow full of a large amount of fine-grained clinker, but also suffers from severe alkali corrosion under the working temperature of 800~1200 °C, resulting in frequent peeling of the lining. The wear-resistant materials used for the inner lining of the tertiary air duct have experienced a series of development processes such as high-alumina castables, mullite corundum castables, and frame structures composed of high wear-resistant bricks and mullite corundum castables. At present, most of the ultra-high-strength wear-resistant castables with corundum and silicon carbide as the main materials are used, and the use effect is better at the bend of the tertiary air duct.
In the process of preparing the tertiary air duct curved prefab, the shape and size of the prefab need to consider the diameter of the air duct, and the shape of the prefab is designed to be an arc-shaped wedge-shaped structure, which is conducive to enhancing the tightness between the blocks. According to the working temperature conditions of the prefabricated parts, the composite combination of ultra-low cement and ultrafine powder is adopted, which mainly focuses on improving the performance of the prefabricated parts under working conditions. The appearance and typical performance indicators of the tertiary air duct bend prefabricated by some domestic manufacturers are as follows:
3) Prefabricated parts of the tertiary air duct gate
In the new dry process cement kiln, the opening and closing degree of the tertiary air duct gate is adjusted to adjust the air volume in the rotary kiln and ensure the oxygen content required for full combustion of pulverized coal in the precalciner. The gate is always subjected to the frontal impact of high-temperature and high-speed airflow during use. The flue gas flow rate is high, the dust concentration is large, and the hardness of the particles contained is high. Usually, the gate is prone to serious wear. The prefabricated part of the tertiary air duct gate adopts high-quality heat-resistant steel as the skeleton in terms of structure, and is welded with anchors to ensure that the gate does not deform under high temperature conditions. The construction process is shown in the figure below. After the surface of the heat-resistant steel and the anchor is painted with asphalt paint, the corundum mullite castable with steel fibers is used for casting and molding, which can not only make the castable and the anchor tightly form a whole, but also reduce the stress between the two. Buffering provides some space. In order to reduce the influence of high temperature baking on the performance of steel structures, the overall baking temperature of the tertiary air duct gate prefabricated parts is lower than that of the prefabricated parts used in other parts of the cement kiln, to meet the requirements of fully eliminating bound water and improving strength, the tertiary air duct Typical performance indicators of gate prefabricated parts are shown in the table below:
4) Kiln hood prefabricated parts
The kiln head cover is located at the discharge end of the rotary kiln, and the coal injection pipe extends into the kiln mouth through the kiln head cover. Due to frequent mutation and thermal shock, the use conditions are very harsh. The lining of this part is usually made of mullite and silicon carbide as the main materials, and it is designed as a prefabricated part. Compared with the unshaped products, it can give sufficient curing and baking time, realize quick installation, and avoid the influence of the construction environment of the cement plant. In addition, the use of prefabricated parts is more conducive to the formation of a heavy-weight and light-weight density gradient composite structure. The heavy-weight part is used as a working layer, which mainly plays the role of structural strength support, and the light-weight part is used as a thermal insulation layer, mainly to reduce heat loss. It avoids a series of problems caused by the use of the shaping pressing method and the amorphous casting method.
