Modeling and Performance for Seabed Airlift Device Based on Pressure Drop

An accurate model of a seabed airlift device is difficult to propose using the traditional mechanical equilibrium method because the forces among gas, liquid, and solid phases are very complex. In order to improve lifting performance, a new model is proposed for this device, considering the pressure drop in the gas–liquid–solid mixture without taking into account the forces among these three phases. The flow unit of the gas–liquid–solid three-phase mixture in this device is considered, and a pressure model is established by analyzing the friction between this unit and the pipe. Subsequently, the pressure model is utilized to develop an airlift theoretical model by combining inlet and outlet pressure constraints. Finally, an experiment is conducted to validate this new model; the results showed that: 1) The new model aligns well with the experimental data with a maximum error of 17.6%. 2) A high gas flow rate increases the pressure drop but reduces the solid fraction. The liquid friction loss is substantial under high gas flow rates, suggesting that a flow drag reduction strategy could be proposed for enhanced lifting performance. 3) The solid superficial velocity initially increases and then decreases with the gas superficial velocity, and an optimal gas flow rate exists for achieving maximum ore flow rate. The overall research provides a theoretical basis and technical support for the analysis of multiphase flow and the optimal design of seabed airlift devices.