Flooding Characteristics of Hydrofoil Impeller in a Two-and Three-phase Stirred Tank

Abstract

Abstract: The flooding characteristics of hydrofoil impeller were systematically investigated in a two-and three-phase 383 mm i.d. stirred tank operated on air, water and spherical glass beads. The volumetric solid concentration C_s was varied from 0 to 25%. And the superficial gas velocity U_g was at the range of 0-0.096 m·s^-1. A fast and objective method for identifying flooding point N_F is developed based on the statistical analysis of the pressure fluctuation signals. It is found, the effect of solid concentration on the flooding point N_F depends on the gas velocity. At the lower gas velocity (U_g=0.010 m·s^-1), the solid concentration has only a minor effect. However, it displays a very significant effect on the flooding point N_F at the medium and high gas velocity. The flooding point N_F linearly increases with the gas velocity U_g, at lower solid concentration (C_s=0, 10%). When C_s=20%, the behavior of N_F versus U_g becomes more complex. The correlations of the flooding characteristics in the slurry stirred tank are proposed by considering the solid concentration effect.

Key words: flooding point N_F, flooding/loading transition, hydrofoil impeller, power spectra analysis

摘要： The flooding characteristics of hydrofoil impeller were systematically investigated in a two-and three-phase 383 mm i.d. stirred tank operated on air, water and spherical glass beads. The volumetric solid concentration C_s was varied from 0 to 25%. And the superficial gas velocity U_g was at the range of 0-0.096 m·s^-1. A fast and objective method for identifying flooding point N_F is developed based on the statistical analysis of the pressure fluctuation signals. It is found, the effect of solid concentration on the flooding point N_F depends on the gas velocity. At the lower gas velocity (U_g=0.010 m·s^-1), the solid concentration has only a minor effect. However, it displays a very significant effect on the flooding point N_F at the medium and high gas velocity. The flooding point N_F linearly increases with the gas velocity U_g, at lower solid concentration (C_s=0, 10%). When C_s=20%, the behavior of N_F versus U_g becomes more complex. The correlations of the flooding characteristics in the slurry stirred tank are proposed by considering the solid concentration effect.

关键词: flooding point N_F, flooding/loading transition, hydrofoil impeller, power spectra analysis

CAI Qingbai, DAI Gance. Flooding Characteristics of Hydrofoil Impeller in a Two-and Three-phase Stirred Tank[J]. , 2010, 18(3): 355-361.

蔡清白, 戴干策. Flooding Characteristics of Hydrofoil Impeller in a Two-and Three-phase Stirred Tank[J]. , 2010, 18(3): 355-361.

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