Mass transfer in gas-liquid cocurrent downflow in a pipeline contactor

Interfacial areas and mass transfer coefficients were affected by changes in liquid and gas velocities. Interfacial areas decreased with liquid velocity in the transition from falling film to bubbly-slug. In the transition from annular flow to froth flow, interfacial area increased with liquid velocity, while only a slight increase was noted within the falling bubbly-film regime. A large increase in interfacial area was observed with increase in gas velocity in the transition from falling film, bubbly-slug to falling bubbly-film. Interfacial area increased with gas velocity in the transition from falling bubbly-film to froth flow but decreased in the transition from falling bubbly-film to annular flow. Interfacial areas obtained in this study fall into the broad range of values in other works. Interfacial areas for cocurrent upflow are up to five times larger.

The liquid phase chemical mass transfer coefficient increased with liquid velocity. With increase in gas velocity in the transition from falling film, bubbly-slug to falling bubbly-film, it experienced a sizable decrease. The volumetric physical mass transfer coefficient increased with liquid velocity but generally remained unchanged with increase in gas velocity. The physical mass transfer coefficient measured in this study compared closely with mass transfer coefficients reported in the literature. The chemical mass transfer coefficient however exceeded these values by a factor of 10 to 50.

The mass transfer results follow the flow regime boundaries of the flow regime map by Oshinowo and Charles very closely.