热态气-液-固三相搅拌反应槽的气-液分散特性

Gas-liquid dispersion in a hot-sparged gas-liquid-solid stirred tank

在直径为0.476m椭圆底搅拌槽内,以空气-去离子水-玻璃珠为实验物系,选用HEDT＋WHU组合桨型,在体系温度为80～82℃时,研究热态体系中固相浓度、搅拌转速、通气流量等操作条件对气-液-固三相体系的功率消耗及气含率的影响规律.研究结果表明：在其它条件相同的情况下,热态的相对功率消耗（K）明显高于常温体系,而固相浓度对K影响不大.热态的气-固-液三相体系的气含率明显小于常温体系,但随着固含率的增加,两者气含率的差异逐渐变小.与常温体系中固体颗粒的存在对气含率基本无影响的规律不同,热态的气含率随固相浓度的增加而增加.

Gas-liquid-solid three-phase stirred tanks/reactors are widely used in many processes, however very few studies have been conducted on the effect of solid particle characteristics on the solid-liquid suspension and gas-liquid dispersion. An experimental system involving a hot-sparged three-phase tank with diameter 0. 476 m （T） agitated by a hollow blade dispersing turbine （HEDT） at the top and a wide blade hydrofoil up-pumping impeller （WHo） at the bottom, in which air, deionized water and glass beads are used as gas, liquid and solid phase respectively, has been constructed. The power consumption and gas hold-up of the system were measured with aid of a torque transducer and a calibrated radar probe. The results show that the relative power demand （RPD） in the hot-sparged system is much higher than that in the cold system. The amount of solid has a negligible effect on the power demand in the hot-sparged system and a similar result is obtained for the cold-gassed system. The gas hold-up in the hot-sparged system is up to 50 % less than that in the cold system, and the difference between the two systems decreases with increasing amount of solid. The gas holdup increases with increasing amount of solid in the hot-sparged system, although there is no effect on the gas holdup in the cold system. The results obtained are of value in the design of hot-sparged gas-liquid-solid multi-impeller reactors.