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Mass Transfer in Multiphase Systems and its Applications Part 4

Tham khảo tài liệu 'mass transfer in multiphase systems and its applications part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Mass Transfer in Multiphase Mechanically Agitated Systems 109 The effect of upper agitator type on the volumetric mass transfer coefficient value in the gas-solid-liquid system is presented in Fig. 14. Fig. 14. Comparison of values of kLa coefficient for two impeller configurations working in gas-solid-liquid systems X A const n 15 1 s various values of superficial gas velocity wog X10-3 m s In the three-phase system that which agitator ensure better conditions to conduct the process of gas ingredient transfer between gas and liquid phase depends significantly on the quantity of gas introduced into the vessel. Comparison of values of kLa coefficient for two impeller configurations working in gas-solid-liquid systems with two different solid concentrations is presented in Fig. 14. At lower value of superficial gas velocity wog 1.71 X10-3 m s both in the system with lower solid particles concentration X 0.5 mass and with greater one X 2.5 mass higher of about 20 values of volumetric mass transfer coefficient were obtained in the system agitated by means of the configuration with HE 3 impeller. With the increase of gas velocity wog the differences in the values of kLa coefficient achieved for two tested impellers configuration significantly decreased. Moreover in the system with lower solid concentration at the velocity wog 3.41x10-3 m s in the whole range of impeller speeds kLa values for both sets of impellers were equal. Completely different results were obtained when much higher quantity of gas phase were introduced in the vessel. For high value of wog for both system including 0.5 and 2.5 mass of solid particles more favourable was configuration Rushton turbine - A 315. Using this set of agitators about 20 higher values of the volumetric mass transfer coefficient were obtained comparing with the data characterized the vessel with HE 3 impeller as an upper one Fig. 12 . The data obtained for three-phase systems were also described mathematically. On the strength .