FLOW VISUALIZATION OF HIGH-PRESSURE (21 MPA) BUBBLE-COLUMN - BUBBLE CHARACTERISTICS

A flow visualization apparatus is developed to study high pressure flo w phenomena in a gas-liquid bubble column. The apparatus can be operat ed at a pressure as high as 21 MPa. The flow behaviour in the column c an be directly visualized through transparent windows. Particle image velocimetry (PIV) is employed to characterize the bubble flow. The stu dy indicates that pressure affects the hydrodynamics mainly through th e variation in bubble size and its distribution. The bubble size decre ases, the bubble size distribution narrows, and the gas hold-up increa ses as the pressure increases. The pressure effect on the Sauter mean bubble diameter is not significant when the pressure is higher than 1. 5 MPa. Photographic presentation of bubble flow at high pressures is a lso given.