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The temperature resistance of refractory castables depends on their material composition and preparation process. Generally speaking, refractory castables can withstand high temperatures, but the specific temperature range will vary depending on the type and formulation of refractory castables. Some common refractory castables, such as high-aluminum refractory castables, corundum refractory castables, and low-cement refractory castables, have high-temperature resistance. These materials typically withstand high-temperature environments ranging from 1500°C to 1800°C. However, for higher-temperature applications, such as steelmaking, glassmaking, or other high-temperature processes, specially formulated and prepared refractory castables may be required. These special refractory castables can withstand higher temperature tests, reaching or even exceeding 2000°C temperature resistance. It should be noted that even if the refractory castable can withstand high temperatures, attention must be paid to the rate of temperature change and the temperature gradient to avoid rupture of the refractory castable or thermal shock due to rapid changes. Therefore, in practical applications, it is necessary to select appropriate refractory castables according to specific conditions and follow relevant usage instructions and operating specifications.
Issues that should be paid attention to when using refractory prefabricated blocks 1. When designing refractory prefabricated blocks, they should not be too large or too narrow (easy to break). They must be of moderate size. In addition to considering expansion joints between two adjacent pieces, special attention should be paid to them during masonry. Arrange the joints staggered, and the expansion joints can be filled with refractory fiber blankets to prevent “penetrating straight joints” from appearing during masonry, which will cause excessive heat loss through the straight joints and even burn out the furnace shell. 2. During masonry, an appropriate amount of refractory mud or high-temperature adhesive should be used to seal the seams between the refractory prefabricated blocks so that they form a whole after high-temperature sintering, which is not only strong but also reduces heat loss. 3. An appropriate amount of insulation layer should be left between the refractory prefabricated blocks and the furnace shell to prevent the furnace shell from overheating and causing large heat dissipation losses. 4. Larger fire-resistant prefabricated blocks must be designed with lifting hooks to facilitate transportation and installation. 5. The service life will be better if the oven is operated according...
In high-temperature working environments such as alumina gas suspension roasters and oil refining catalytic cracking units, the media content is high, high-speed airflow erosion and abrasion are serious, and the use conditions are very harsh. To improve the service life and stability of these parts, wear-resistant and refractory castables need to be used as lining materials. Wear-resistant refractory castables require dense and hard refractory aggregates, refractory powders of suitable fineness, excellent binders, ultrafine powders, and admixtures to achieve densification and high strength of the material. Selection and proportioning of refractory aggregates The refractory aggregate used in wear-resistant refractory castables must have high density and hardness to increase the material’s compression and wear resistance. Multi-stage particle gradation can achieve the maximum packing density and improve the density of the material. Through reasonable proportion design, high-quality refractory aggregate preparation can be achieved. Fineness requirements for refractory powder The refractory powder in wear-resistant refractory castables needs to have suitable fineness, which is generally required to be greater than 0.09mm and greater than 90%. By selecting the appropriate particle size and distribution range, the density and wear resistance of the material can be increased, and the strength of the castable can be improved. Application...
In a biomass burner, the flame nozzle is an important component for putting biomass pellet fuel into the combustion chamber, so the refractory castable used at the flame nozzle is crucial to the normal operation of the biomass burner. Selection factors for fire-throwing nozzle castables: 1. High-temperature resistance: The flame nozzle will be impacted by high temperatures during the biomass combustion process, so the castable needs to have good high-temperature resistance and be able to withstand thermal stress and corrosion in high-temperature environments. 2. Thermal conductivity: The thermal conductivity of the castable will affect the heat dissipation effect of the flame nozzle. Choosing castables with good thermal conductivity can improve the thermal conductivity of the flame nozzle and reduce heat loss. 3. Anti-corrosion performance: Ash and chemicals produced during biomass combustion will cause corrosion to the flame nozzle. Therefore, the castable needs to have good corrosion resistance to extend the service life of the flame nozzle. Based on the analysis of the selection of castables for biomass burner flame nozzles, we formulated refractory castables that meet the requirements for use. That is, the flame nozzle is castable. The flame nozzle castable has the characteristics of high refractory temperature, good compressive...
In winter, the use and maintenance of refractory castables require special attention because low temperatures may cause damage to the refractory materials. The following are some things to note when using refractory castables in winter. 1. Keep refractory materials dry In winter, the humidity is high, and refractory materials easily absorb moisture, causing them to lose part of their mechanical strength. At the same time, when the surface of refractory materials is frosted or covered with snow, the wear and corrosion of the materials will also be accelerated. Therefore, when using and storing refractory castables, they need to be placed in a dry and ventilated environment to avoid being affected by moisture and snowfall. 2. Control construction and hardening temperatures During the construction and hardening process, refractory materials require certain temperature protection measures. Application at temperatures lower than specified for the material will prevent the material from fully reacting, curing, and hardening. On the contrary, if it is applied at a temperature higher than the specified temperature, it will cause cracks and deformation of the material. Therefore, when using refractory castables, it is necessary to strictly follow the construction and hardening temperature requirements in the material instructions. 3. Prevent materials...
Portland cement refractory concrete is prepared with ordinary Portland cement, slag Portland cement, and Portland heat-resistant cement as binding agents, and refractory aggregates and powders. The maximum operating temperature is 1200℃ or 1200℃ The following medium and low temperature refractory concrete. It has the advantages of easily available materials and low cost and can be used to cast integral load-bearing and heat-resistant structures and kiln linings, especially in projects such as foundations and floors of thermal equipment, flues, chimney linings, and thermal storage tanks. More. Ordinary concrete prepared with Portland cement is not fire-resistant and is prone to damage or serious loss of strength when exposed to heat for a long time. Based on overcoming this defect, Portland cement refractory concrete was gradually formed. The preparation of Portland cement refractory concrete is generally divided into two aspects: 1. Add specific powder to Portland cement In Portland cement refractory concrete, specific powder is added, its main functions are: reducing the shrinkage of cement stone; binding free calcium oxide; and stabilizing dicalcium silicate. 2. Use appropriate aggregates From the analysis of the causes of thermal damage to ordinary concrete, it can be seen that the aggregate used to prepare refractory concrete should...
1. If construction conditions permit, the water-cement ratio should be reduced as much as possible to reduce water consumption. This is because water in refractory concrete is easily lost at high temperatures, resulting in increased concrete pores and reduced strength. 2. To meet the workability and normal temperature strength, the amount of cementing materials and cement should be reduced as much as possible. This is because the fire resistance of aggregates is generally higher than cementing materials and high-temperature cementing materials soften and deform before aggregates. 3. Adding appropriate admixture materials can improve the fire resistance of concrete, improve workability, and reduce the amount of cement. Commonly used blending materials include clay clinker, clay refractory bricks, alumina clinker, magnesia, chromite, fly ash, finely ground powder of high alumina bricks, and silica powder and corundum powder with high refractory properties. 4. Appropriate gradation of aggregates should be selected to maximize density, and attention should be paid to matching with cementitious materials. The sand rate is controlled at 40% to 60%. The mix ratio design is generally based on the empirical mix ratio and is determined after adjustment through experiments. Refractory concrete is generally not equipped with steel bars because the thermal...
Porous clinker refractory castable is a lightweight refractory castable with excellent properties and is widely used in large coke ovens, blast furnaces, steel rolling heating furnaces, ammonia synthesis plants, and other fields. This article analyzes the raw materials, mix ratio, and molding process of porous clinker refractory castables, summarizes the key technical measures to improve its performance, and compares the performance of ordinary porous clinker refractory castables and high-strength porous clinker refractory castables. 1. Raw materials and characteristics of porous clinker refractory castables Porous clinker is a synthetic material with the characteristics of small bulk density, high cylinder pressure or particle strength, high refractoriness, and low thermal conductivity. There are many varieties, usually porous pyrophyllite or siliceous clinker, porous clay or high alumina clinker, porous mullite or corundum clinker, porous zirconium-containing and alumina clinker, etc. In China, porous clinker refractory castables have been formulated from porous clay, high alumina, and mullite clinker, with a volume density of 1.0~1.8g/cm³ and a service temperature of 1300~1600°C. 2. Preparation process and performance optimization of porous clinker refractory castables The mix ratio and molding process of porous clinker refractory castables have a significant impact on their performance. First, the amount of cement should be...
In recent years, self-flowing refractory castables have been widely used in thermal equipment. The refractory castables of this new construction method are innovatively developed based on low-cement series refractory castables and are based on the solid closest packing principle and rheology theory. Self-flowing refractory castables not only have significant economic benefits but have also achieved initial success in thermal equipment such as spoons, tundishes, blast furnace tap trenches, slag trenches, boiler tube protective layers, incinerator grates, heating furnaces, and cement kilns. Results. Self-flowing refractory castable (S.F.C) is a highly thixotropic mixture that can flow and degas by its gravity. Compared with vibration-type low-cement series refractory castables, self-flowing refractory castables have better performance and do not require vibration equipment, steel drills, or beating of external molds, thereby reducing construction costs, noise pollution, and labor intensity. However, raw material costs increase slightly due to the high quality and large quantities of matrix materials. To improve the performance of self-flowing refractory castables, research and development work mainly focuses on the optimization of critical particle size and particle gradation (including ultrafine powder), binders, and admixtures of refractory aggregates. The application of ultrafine powder technology has created a new era for low-cement series refractory castables....
The construction process of refractory plastics needs to be carried out in strict accordance with the design requirements. The following are the specific construction steps: 1. Construction preparation Before starting construction, it is necessary to conduct a comprehensive inspection of the furnace steel structure, baselines, holes, and other parts. Construction can only be carried out after passing the inspection. The construction department should clean up debris in and around the furnace and transport air compressors, construction tools, scaffolding, etc. to the site. The air compressor must be connected to the power supply and tested to run normally. Fire-resistant plastic blanks should be stored in a cool warehouse. Their plasticity should be checked before construction, and construction can only proceed if they meet the requirements. If the ambient temperature is lower than 10℃, cold protection measures need to be taken. Close cooperation between various types of work is required during the construction process. Once construction begins, it must be carried out continuously without interruption. Cover the knotted surface with plastic sheeting to prevent dehydration if interruption is necessary. 2. Ramming construction When pounding the refractory plastic furnace wall, the blanks must be laid out tightly and flat, and only one layer...
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