(419f) Gas Holdup and Bubble Behavior in an Upflow Packed Bed Column

Gas-liquid two-phase flow in porous media has applications in many engineering operations including chemical and biochemical industries, natural gas release from lake beds, and water reclamation for astronauts during space travel. In this research, gas-liquid up-flow in a rectangular laboratory-scale packed bed is studied experimentally. The bubble emerging mechanism from a packed bed under different operational conditions has been investigated. Two patterns for bubble behavior are detected based on the packed particle sizes and air flow rate. In beds consisting of larger particle sizes and under specified operating conditions, gas bubbles simply go through the interstitial space of the particles and emerge upward. In this case bubble size is closer to the particle size. In the second case, for beds of smaller particles and below a critical particle size, bubbles get stuck in the bed, and coalesce into a larger bubble until the buoyancy force overcomes the surface tension force and releases the bubble. These two bubble behavior patterns in the packed bed column affect the gas holdup in the bed. In the bubble coalescence case, releasing large bubbles from the bed reduces the gas holdup, while in the smaller detached bubbles case, the gas holdup increases and reaches to a maximum.