1. Characteristics and requirements of refractory prefabricated parts
The pre-construction part is divided into small pieces in advance, and the appropriate shape is designed, and then the mold is made according to the shape, and then the factory is poured into shape, maintenance, baking and shipped to the site for construction and installation. The application of refractory prefabricated parts has changed the traditional casting construction method, so that the construction is simple and easy, can save the on-site mixing, pouring or ramming and the required corresponding equipment, greatly saving the construction time, and the site construction conditions are not affected by the construction environment and seasons, and is more conducive to ensuring the construction quality. In order to facilitate the production, transportation and installation, the shape of the prefabricated parts can not be designed too large and too complex, and as far as possible uniform size, in addition to the need to take into account the combination between the block and the block, so as to enhance the integration effect after construction. The construction parts need to be cleaned, otherwise it will affect the installation accuracy and effect of the refractory prefabricated parts.
Most of the parts used in refractory prefabricated parts are special parts in harsh environments such as high temperature, cement clinker erosion, wear, acute cooling and acute heat, which are easy to produce mechanical deformation, and need to have good erosion resistance, good wear resistance and high temperature gas erosion resistance and excellent thermal shock stability. To achieve the performance requirements, the ratio of raw materials is the basis, which is similar to the requirements of castable, but the castable needs to pay attention to the performance of the entire temperature range from construction to use conditions, and the refractory prefabricated parts, as the shaped products prepared by castable, pay attention to the performance after baking. Many manufacturers have listed the performance indicators of prefabricated parts under different temperature conditions, which is actually of little reference significance for cement manufacturers. In view of this situation, the raw materials and ratios used in refractory prefabricated parts can be adjusted on the basis of castable, and more attention needs to be paid to the performance after baking.
Refractory materials in key parts of cement kiln need higher construction quality in the construction process, and during the maintenance of cement kiln, the general construction period is short, the quality of on-site pouring construction is difficult to guarantee, and the quality of construction quality has a great impact on the service life of refractory materials. The increase of water added will increase the porosity of castable, decrease the strength, and seriously affect the wear resistance of castable. After the construction of castable, there must be a certain maintenance time, and it must be baked after the maintenance is completed, otherwise it is easy to burst.
Because the production process is carried out in the production enterprise, it can overcome the adverse effects of factors such as urgent site construction time, environmental seasonal temperature changes, site construction management, etc. After adequate maintenance and strict baking, the construction quality can be guaranteed, and the quality problems caused by non-standard construction can be greatly reduced, so that the performance of refractory materials can be fully played. Direct ignition after installation can shorten the maintenance time and create good economic benefits.
2. Performance requirements of precast parts in different parts of cement kiln
1) Grate cooling machine low wall and top prefabricated parts
The grate cooler is located in a special position, the flue gas composition is complex, the temperature is high, the wind speed is high, the dust contained in the flue gas is mostly small particles of cement clinker, which is not only large but also hard, and the erosion and erosion wear of refractory materials are serious. Therefore, the phenomenon of overtemperature or burning through is very common in the grate cooler, so the reasonable selection of refractory materials in this part and the construction quality are crucial. The prefabricated parts in this part are usually made of high bauxite and silicon carbide as aggregate, calcium aluminate cement as binder, adding ultrafine powder and admixture, and adding a certain amount of heat-resistant steel fiber, in accordance with the construction specification of low cement castable to make a suitable shape of the prefabricated parts.
The shape, size and structure of the prefabricated parts are related to the parts used. For the prefabricated parts for the low wall of the grate cooling machine, 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 lugs. Through the combination of tongue and groove, the sliding between each block is limited, and the integrity and stability of the masonry structure is improved. For the top of the grate cooler, especially a section of high temperature area, the prefabricated parts can be welded or bolted to the top by anchoring parts, or can be connected directly by hanging on the steel plate.