This paper presents a three-phase transient hydrodynamic model considering the solid-liquid-air mixture and the theoretical investigation of the flow characteristics in a vertical air lift pipe. The phase transition from solid-liquid two-phase to solid-liquid-air three-phase after air injection at the intake of the air-lift pipe was modeled. In order to describe the simultaneous flow of solid, liquid and gas through pipe, we represent the two-phase flow of particle and liquid from the bottom to the air inlet with the equations of mass and momentum conservation. Also, the three-phase flow in the upper part is expressed by the governing equations composed of mass transfer and momentum transfer between phases and momentum change occurred by frictions between fluid and pipe wall. In the model, the transition phenomena among bubble, slug and churn flow patterns are considered. Finally, the model has been applied to air-lift systems for examining the effects of various flow conditions. As a result, it is confirmed that the developed model can explain adequately the flow characteristics of the transition phenomena between phases.
Recently the world is developing the plan for the use of deep-sea metallic resources because of the reduction of land resources. However, it is essential to have integrated mining technology for developing deep-sea manganese nodules. To lift the manganese nodules from deep seabed, the hydraulic pumping system and the air-lift pumping system are recommended for commercial lifting (Chung, 1985; Yoon et al., 1999). In the past, the small-scale air-lift system was used to lift corrosive and/or toxic liquid, so the main concern was how the submergence ratio of the liquid in a vertical pipe affects the gas-liquid two-phase flow. Researches on the gas-liquid-solid three-phase flow in the vertical pipe have been studied by several workers.
