Electrical capacitance volume tomography for imaging of pulsating flows in a trickle bed

• A pulsating trickle bed is measured by electrical capacitance volume tomography.
• The pulse structures in fully developed and transient conditions are illustrated.
• The pulse frequency, velocity and liquid holdup in various conditions are measured.
• Liquid holdups in gas and liquid zones are solely dependent on the gas flow rate.

Experimental results of the air–water pulsating flows in a trickle bed column were obtained using the electrical capacitance volume tomography (ECVT) system. Detailed 3-D pulse structures in both the fully developed and the transient conditions were illustrated. Pulse frequency, pulse traveling velocity, average liquid holdup and liquid holdup inside the gas-rich and liquid-rich regions, respectively, were measured. Based on a simplified model, the linear liquid velocities inside the gas-rich and liquid-rich regions were estimated. The results revealed that the gas flow rate was the most important parameter in controlling the pulsating flow properties. Discussion on the physical nature of the pulsating flow was also given.