Bubble size distributions in a bubble column reactor under industrial conditions

Abstract The design of gas liquid processes requires a detailed knowledge of bubble size distributions, since they determine the mass transfer. In this contribution the influence of operating conditions and physical properties of gas and liquid phase on initial and final (“stable”) bubble sizes is discussed. The measurements were performed in a lab scale bubble column for different liquids sparged with nitrogen for pressures up to 50 bars and temperatures up to 175 °C. Bubble size distributions were determined by image processing. Bubbles tend to become smaller with decreasing surface tension, increasing gas density and decreasing liquid viscosity, resulting in reduced stable bubble sizes at increased pressure and also at increased temperature as long as evaporation can be neglected. Impurities in aqueous and organic liquids can severely influence bubble sizes by restraining coalescence. For such systems bubble size distributions in a column mainly depend on the size of the primary bubbles, which are determined by the sparger design.