Experimental Investigations Of Airlift Pump With Lifting Non-uniform Solid Particles

The airlift pump has been widely applied in the fields of pulp lifting, tailrace dredging, oil and chemical liquid transportation as a new technology. The general characteristics of it have been researched deeply, but the theory of lifting non-uniform particles is less studied. Hench, this paper proposes an idea of lifting non-uniform particles using airlift pump. The lifting mechanism will be revealed from the point of experiment and theoretical modeling.In order to investigate the lifting law of particles, a critical model of solid particles can be lifted based on Newton’s second law and the fundamental theory of hydrodynamics is established, and then the variation of critical velocity under different particles diameter is obtained. Based on this, to analysis the variation of axial pressure, hold-up and real velocity of each phase in pipe and obtain the triangular relationships of the volumetric fluxes of air supplied, the volumetric fluxes of water discharged and the volumetric fluxes of particles discharged, a velocity model of gas-liquid-solid three phase flow is built. Furthermore, the effect of particles diameter, concentration of particles and submergence ratio on lifting performance is analyzed. In addition, a model of lifting efficiency is established based on the energy conservation law to analysis the influence of every factor on efficiency.In order to verify the reliability of the theoretical model, we choose the ceramic particles of 2mm and 5mm as medium and investigate the variation of the volumetric flow rate of water and particles and lifting efficiency with the volumetric flow rate of air, the submergence ratio, the diameter of particles, the concentration of particles and mixing ratio.The theoretical analysis and experimental results show that the critical velocity increases with increasing the size of particles, but decreases with increasing the submergence ratio. In the experiment, it is found that the critical volumetric flow rate of air decreases with increasing submergence ratio and increases with increasing the size of particles.The volumetric flow rate of particles and lifting efficiency both increase with increasing submergence ratio and decrease with increasing the size of particles. Besides, the volumetric flow rate of particles and lifting efficiency both reach a peak value at a specific volumetric flow rate of air. Whereas, the volumetric flow rate of particles increases with increasing concentration of particles, the variation of lifting efficiency is opposite.The volumetric flow rate of particles and efficiency both increase with increasing the ratio of fine particles. The effect of submergence ratio of on coarse particles is bigger the fine particles. The theoretical analysis is agreed with the experimental results.