Experimental Investigations Of Airlift Pump With Lifting Large Scale Solid Particles

Air lifting technology as an effective lifting tool was widely used in borehole hydraulic jet mining,deep-sea mining,river dredging and other fields.At present,followed with the exploitation of small particles,the remaining large diameter metal nodules and massive gravel deposits in the water,and it was difficult to be lifted.To with this,we studied the mechanism and law of the pneumatic lifting of large particles by means of experimental methods.This paper takes the large particle air lifting as the research object,in-depth study of the gas liquid solid three-phase flow to improve the performance of the law with the change of parameters.Experiment use medical stone ceramic particles as test object,which have a density of 1967kg/m~3,the diameter of materials are 10 mm to study the effects of various parameters on the performance of the air lift.Experiments using high-speed camera system for three-phase flow tube in motion dynamic shooting,and analyzed by image processing technology in tube flow field structures.Lifting speed model based on three phase flow theory and Newton's second law speed model is established.On that basis,the efficiency model was established by applying the law of conservation of energy.We obtained the influence factors of efficiency and the law of their interaction.An experimental researched on the air-lifting system to improve performance by changing the structure and operation parameters.The lifting performance results show that:The critical volumetric flow rate of air increase with the increase of air intake depth,and decreases with the increase of submergence ratio.The discharged of water,solid and lifting-efficiency increases with the increase of submergence ratio under the same amount of intake air.In addition,compared with the flooding rate,the effect of air volume on the performance of the air lift is more significant,there is an optimal air volume value,which makes the performance of the pneumatic lifting up to the best.Through the high-speed video camera to obtain trajectory characteristics of the particles,and based on the image processing method for the distributionof particles within the tube,The law of the movement of air lifting is expounded.Research results show that: The flow pattern of the air lift pipe is periodic transformation.That is spare bubble flow-intensive bubble flow-bubble churn flow-churn flow-sparse bubble flow.The bubble churn flow is more favorable to the improvement of the system to lift solid particles in the relatively spare bubble flow and intensive bubble flow.Compared with single particle,the strength of the particle swarm is better than that of the single particle,and the particle is affected by the radial force.Through the high-speed video camera shoot the particles in the process of ascension,using digital image processing to analysis the particles flow tube state and motion trajectory in the pipe.The experimental results obtained the law of motion of the pneumatic lifting.Research results show that: The flow pattern of the air lift pipe is periodic transformation.Its law is: sparse bubble flow-dense bubble flow-bubble stirred flow-stirred flow-sparse bubble flow.The bubble agitation flow is more favorable to the improvement of the system to lift solid particles in the relatively sparse bubble flow and dense bubble flow.The particle velocity at the core of the tube is higher,and the velocity of the particles in different radial positions is not symmetrized to the center line of the pipeline.Compared with single particle,the strength of the particle swarm is better than that of the single particle,and the particle is affected by the radial force.At low intake rate,the particle concentration is low and the particles are mostly in the pipe wall.the particle concentration is low.With the increase of air flow rate,the particles move towards the core,and the particles concentration and the rate of increase were higher.At low inlet velocity,the particle concentration is low and the particles are mostly in the pipe wall.With the increase of air flow rate,the particles move towards the core,and the particles concentration and the rate of increase were higher.Continuously increasing the inlet velocity,the flow pattern in the pipe tends stirred flow,particle distribution is relatively sparse in tube.Combined the effect with the intake rate and the radial force of the particles is irregular spiral upward.Furthermore,the mixed fluid in the tube is affected by the bubble polymerization and the splitting effect presents some oscillation characteristics.