In view of the shortcomings of the existing solid particles used in fluidized bed heat exchang-ers,such as high density,low strength and low wear resistance,low-density spherical ZrO2/SiO2/Al2O3 composite ceramic particles were prepared by sol-gel and hot oil column curing methods,and the effects of ZrOCl2 solution and silica sol addition sequence and Zr/Si/Al molar ratio on the microstructure and physicochemical properties of the prepared composite ceramic particles were studied,and the feasibility of the application of the prepared particles in fluidized bed heat transfer was evaluated.The results show that the as-prepared particles with a Zr/Si/Al molar ratio of 1∶1∶60 have a dry granule density of 1 740 kg·m-3 and wet granule density of 2 170 kg·m-3,much lower than that of the normal ceramic(2 400～2 900 kg·m-3).The lower density is beneficial to their uniform fluidization and distribution in the heat exchange tube bundle,and hence ensures the effectiveness of preventing/removing scale and en-hancing heat transfer.Besides,the particles with a mean diameter of 1.55 mm present good wear and corrosion resistances,and dry and wet single particle compressive strengths of 116.0 N and 115.7 N,re-spectively,which are high enough for the fluidized bed.Comprehensive consideration of size,density,mechanical strength,and wear and corrosion resistances,the as-prepared spherical composite ceramic particles are suitable for fluidized bed,especially in a tube heat exchanger for preventing/removing scale and enhancing heat transfer.
sol-gelpreparationalumina-based compositesspherical particlefluidized bed heat transfer
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