In a gas-liquid spouted vessel, where power is supplied from a pump to water and gas is introduced at a nozzle attached at the bottom of the vessel, gas bubbles are finely broken at the nozzle and dispersed to the vessel. Gas hold-up in the gas-liquid spouted vessel rapidly increases with increasing liquid flow rate and easily exceeds twice the gas hold-up in the aerated tower of the same gas flow rate with no liquid flow, though co-current liquid flow gives zero or negative effect on gas hold-up in the aerated tower. Effect of liquid flow rate, gas flow rate, nozzle to vessel diameter ratio and nozzle length one'ffective spouting of gas bubbles were studied experimentally. Waysare also considered to scale up the gas-liquid spouted vessel.

Due to the great liquid energy concentrated at the nozzle and strong turbulence in the vessel, the liquid-phase spouted vessel is highly effective in fluidizing or dissolving solid particles5>6) and dispersing gas bubbles7j8). It was reported in a previous paper that large gas hold-up was easily obtained in the gasliquid spouted vessel. In this report, the bubble size distribution in the gas-liquid spouted vessel is reported. ExperimentalDiameter and height of the spouted vessel used in this study were 15 and 142cm, respectively. Cone angle was 60°and nozzles of 10, 13, 16 and 25mmin diameter were tested. The details of gas-liquid spouted vessel were shown in the previous paper7\Tap water was used as liquid and the gas was air in this study. Liquid flow rates were 0 to 50 liter per min. and gas flow rates were 5 to 80 liters per min. Liquid temperature was set at 25°C. Photographs were taken at a point 60cm above the nozzle outlet through a square windowto eliminate errors due to the curvature of the vessel wall.The position where pictures were taken corresponded to the lower part of the calm uniform flow section of the liquid-phase spouted vessel. A 16mm highspeed cine-camera was also used to measure the size of large gas bubbles. Representative bubble diameter was calculated as d,=V dn xdi2 (2) where da and di2 were long and short axis of ellipse, re spectively.

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