文摘
Many industries use gas-liquid stirred-tank reactors with a third phase of buoyant particles. Few studieshave looked at the effects of buoyant particle characteristics on solid-liquid suspension and gas-liquiddispersion, and even less have considered operation at elevated temperatures. This paper reports powerconsumption and gas holdup measurements made in a hot-sparged three-phase system. The vessel was adished-base reactor of diameter 0.476 m (T) holding 0.145 m3 of liquid, agitated by a multi-impeller agitator(a hollow half-elliptical blade dispersing turbine below two up-pumping wide-blade hydrofoils, identified asHEDT+2WHU). This configuration has been recommended in previous work. Air, deionized water, andpolypropylene (PP) particles were used in this work. The temperature of the water was in the range 80.5-82.5 C. The results show that, as in a cold system, the effect of the solid concentration on aerated agitatorpower demand is negligible. There is little difference between the agitator power demand in cold- and hot-sparged systems, except that the relative (gassed-to-ungassed ratio) power demand, RPD, is a little higher inhot-sparged conditions. The influence of power consumption and gas rate on gas holdup is slightly less whenhot than when cold. Gas holdup in the hot-sparged system, which, with similar total gas rates and powerinput, is only about one-half or two-thirds of that at room temperature, is slightly increased at higher solidsconcentrations. The reasons for the differences in gas dispersion between cold- and hot-sparged systems areanalyzed and discussed in this paper, with further experimental and CFD studies planned for future work.