The high heat dissipation on the surface of the kiln barrel is a common problem in various cement kilns. Currently, double-layer insulation kiln lining is used in the preheater, decomposition furnace, cooling machine, kiln door cover, and air duct of the new dry process kiln, accounting for about 8% of the total weight of the kiln lining; The energy-saving technology of wet kiln also requires a large amount of insulation bricks. This type of insulation brick should have sufficient strength. Develop a lightweight and high-strength insulation brick using floating beads in fly ash.
Drifting beads are gray white granular spheres of varying sizes, appearing circular or approximately circular. The floating beads used in the experiment have a particle size of 20-25um, a wall thickness of about 10% of the bead size, and a loose bulk density of only 0.34-0.38g/Cm3, which can withstand high pressure. According to lithological and X-ray diffraction analysis, the basic component of floating beads is about 85% vitreous body, with very little crystal content. The chemical composition of floating beads is mainly SiO2 (content 55-59%) and Al2O3 (content 32-36%). Floating beads have a hollow thin-walled spherical structure, and their amorphous thermal conductivity is lower than that of crystals at all temperatures. The use of floating beads to manufacture insulation bricks can result in lower thermal conductivity, smaller bulk density, and higher mechanical strength. Experiments have shown that controlling the bulk density of high-strength insulation bricks can make them have different compressive strengths. Another characteristic of high-strength insulation bricks is that the structure of the pores is relatively reasonable. It contains 12-13% closed pores, while other insulation bricks only have 0.01-1.78%. The more closed pores there are, the more beneficial it is to reduce convective and radiative heat transfer, which can lower the thermal conductivity.
The mechanical strength of the insulation bricks used in each system of the cement kiln is different. According to different usage conditions, locations, and kiln deformation, there are two types of high-strength insulation bricks, with strength indicators of 50kg/cm2 and 100kg/cm2, respectively.
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