Kiln ceiling bricks are a kind of refractory products specially used for the top of the kiln. Among the choices of kiln ceiling bricks, common types include mullite ceiling bricks, high-aluminum ceiling bricks, etc. Mullite ceiling bricks have the characteristics of uniform expansion, good thermal shock stability, high load softening point, small high-temperature creep value, high hardness, and good chemical corrosion resistance. High-aluminum hanging bricks have good high-temperature resistance and are usually used in high-temperature areas of industrial equipment, such as furnaces, flues, etc., as well as some building structures that require fire resistance.
Performance characteristics of mullite ceiling bricks
Mullite ceiling bricks are a material with excellent performance. It has the characteristics of uniform expansion, which makes its volume change more stable when the temperature changes, reducing cracking and damage caused by thermal expansion and contraction. Good thermal shock stability can withstand rapid changes in temperature without breaking, such as during the start-up and stop of the kiln. High load softening point means that it can still maintain its shape and structural integrity under high pressure and high temperature. The high-temperature creep value is small, which ensures the dimensional stability in a long-term high-temperature environment. The high hardness makes it have good wear resistance and impact resistance. Good chemical corrosion resistance, can resist the erosion of various chemical substances in the kiln, and prolong the service life. In addition, the mullite ceiling brick has high refractoriness and can directly contact the flame without erosion and scouring. It is suitable for the thermal insulation layer of the kiln, which provides a strong guarantee for the stable operation of the kiln.
Performance characteristics of high-aluminum ceiling bricks
High-aluminum ceiling bricks have many performance characteristics. The refractoriness of high-aluminum ceiling bricks is usually high, generally above 1750℃. Its high refractoriness comes from the high alumina content, which can withstand high-temperature environments without obvious deformation or damage, such as excellent performance in high-temperature industrial kilns. The load softening temperature of high-aluminum ceiling bricks is high, usually above 1400℃. This means that when subjected to high pressure and high temperature, it is not easy to deform, can maintain good structural stability, and provide a guarantee for the long-term stable operation of the kiln. High-aluminum ceiling bricks have good slag resistance and can effectively resist the erosion of acidic and alkaline slag. This enables it to work stably for a long time in complex industrial environments, such as kilns in the metallurgical and chemical industries, and reduces damage caused by slag corrosion. High-aluminum ceiling bricks have good thermal stability and a small expansion coefficient. When the temperature changes, its volume changes relatively little, reducing the risk of cracking caused by thermal expansion and contraction, and increasing its service life. High-aluminum ceiling bricks are hard and have high compressive strength. Generally above 50MPa, they can withstand greater pressure and impact force, ensuring that they are not easy to break and damage during use.
Selection of ceiling bricks in different kiln structures
Different kiln structures have different requirements for the selection of ceiling bricks. For roller kilns, the kiln roof usually uses lightweight brick ceilings, the quenching section kiln roof uses ceramic fiber folding blocks for flat hanging, and the slow cooling section kiln roof uses fiber cotton felt. The kiln wall uses high-aluminum polylight bricks and fiber blankets from the inside to the outside to reduce the heat dissipation of the kiln wall. In the furnace wall structure that enhances the thermal insulation effect of the kiln, the kiln body includes a refractory insulation layer and a closed cavity from the inside to the outside. The setting of the closed cavity can be evacuated into a vacuum state when the temperature rises, avoiding air convection conduction and reducing heat loss; when the temperature drops, cold air is blown into the closed cavity to accelerate the cooling speed of the furnace. When choosing ceiling tiles, factors such as the use temperature, pressure, and chemical environment of the kiln need to be considered. For example, in a high temperature environment, mullite ceiling tiles may be more preferred because of their high refractoriness; while for kilns with special chemical corrosion environments, ceiling tiles with strong chemical corrosion resistance need to be selected.
The influence of the construction method of ceiling tiles
The construction method of ceiling tiles has an important influence on the performance and service life of the kiln. Before construction, it is necessary to prepare suitable ceiling keels, fixings, tools, etc. During the construction process, it is necessary to ensure that the laying position of the bricks is accurate and firm. For example, if a stick-on ceiling is used, it is necessary to apply adhesive on the brick surface, and the application should be uniform to ensure the close combination of the brick and the base layer; if it is a suspended ceiling, it is necessary to fix the hanger on the brick surface, and the drilling position should be accurate to avoid damage to the brick. The construction sequence is also critical. Generally, the base layer is treated first to ensure that the base layer is flat and firm, and then the ceiling tiles are installed. The correct construction method can ensure the stability and sealing of the ceiling tiles, reduce heat loss, and improve the thermal insulation performance and work efficiency of the kiln.
How to improve the thermal insulation performance of the kiln
To improve the thermal insulation performance of the kiln, you can start from many aspects. First, choose suitable thermal insulation materials, such as lightweight refractory bricks, thermal insulation amorphous refractory materials, thermal insulation fiberboard, etc. These materials have the characteristics of low thermal conductivity and low heat capacity, which can effectively reduce the transfer of heat. Secondly, optimize the structural design of the kiln, such as setting up a closed cavity, vacuuming when heating, and blowing in cold air when cooling to control temperature changes and reduce heat loss. Increasing the thickness and porosity of the insulation layer, reducing the pore size, increasing the complexity of the organizational structure, reducing solid-phase contact, and adding shading materials to prevent radiant heat transfer can also improve thermal insulation performance. In addition, detail processing during the construction process is also very important, such as ensuring that the thermal insulation materials are laid tightly and without gaps, and sealing the joints to prevent heat leakage.
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