Liquid entrainment in high-pressure bubble columns

The liquid entrainment in bubble columns is experimentally studied under high-pressure conditions. Water and Paratherm NF heat-transfer fluid are used as the liquid phase, with nitrogen and air as the gas phase. Operating pressures and superficial gas velocities vary by up to 3.13 MPa and 33 cm/s, respectively. Parameters include the droplet size and droplet velocity, and local and total entrainment rates are examined. The study indicates that the entrainment rate increases with system pressures and superficial gas velocities. The maximum droplet velocity is found to be located between the center and wall regions at low pressures and low superficial gas velocities; the specific location shifts toward the center as the pressure and superficial gas velocity increase. The distributions of the droplet velocity and droplet size are narrower at locations further away from the entrainment surface. The droplet velocity of water at a given location and operating condition is found to be higher than that of paratherm, which has a higher viscosity and larger droplet size compared to water.