基于压差法的海底气举扬矿装置建模与工作特性分析

Modeling and Performance for Seabed Airlift Device Based on Pressure Drop

气举扬矿装置通过气-液-固三相间动量交换,实现海底矿浆的举升,能长期在泥、水、砂等多相共存的恶劣环境中工作,克服了传统机械泵耐磨性差、密封要求高的缺点,具有极强的市场应用价值和广阔的应用前景。海底气举扬矿装置气-液-固三相力学作用过程极为复杂,传统三相力学平衡方法难以精确建立海底气举扬矿模型,严重影响扬矿装置的设计与过程控制。为了提升扬矿性能,在不考虑气-液-固内部力学作用机理情况下,从气-液-固混合流体整体压降衰减角度建立扬矿装置理论模型。提取扬矿管气-液-固流动单元,分析流动单元与管壁的摩擦损耗特性,建立混合流体的压差模型,并以扬矿管进出口压力为约束条件,形成了扬矿理论模型,突破了常规三相力学建模繁琐难题。在此基础之上,搭建海底气举扬矿实验测试平台,验证了理论模型的可靠性,研究结果表明:1)理论模型与实验值吻合度较高,误差在17.6%范围内;2)增大气体表观速度提高了混合流体压差,却降低了含固率,这可能是因为高进气工况下液流摩擦损耗较大,可采取液流减阻策略提高扬矿性能;3)固体颗粒表观速度随气体表观速度先增加后减小,存在最优气体表观速度使得装置扬矿量最大。研究结论为海底气举扬矿装置多相流动特征分析及装置优化设计提供理论基础与技术支撑。

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.