Theoretical Analysis And Experimental Study On The Airlift With Lifting Liquid

Airlift device has been widely used in deep wells water intaking,petroleum exploitation and hazardous chemical liquid transport as a special pump. Comparing with traditional pump and jet pump,few fundamental research on airlift device has been made. There exist many scientific problems in airlift device need to be solved.Few studies have focused on the theoretical model and flow field of lifting system. In order to seek new methods to establish theoretical model of the lifting system and to clarify the structure of flow field, on the basis of research results of the previous investigators, the air-lift apparatus with innovative design on the air injection installment is designed on which the relevant theoretical and experimental analysis are carried out.The influencing factors on the friction loss and pump performance are analyzed. Meanwhile, the models which describe the efficiency and pumping head are proposed based on Bernoulli’s equation, momentum equation and energy equation.A dimensionless equation is obtained based on Bernoulli equation in lifting pipe.In order to vertify the theoretical model, airlift performance(It contains volume of water discharged, efficiency and pumping head) is investigated experimentally for different parameters, which mainly contain submergence ratios and air flow rate. The influence low of flow field affected by such parameters is investigated by using Laser Doppler Velocimeter.The analytical results reveal that the pump performance increases with the increases of submergence ratio and increases with the increases of air flow rate at first and then declined, which shows that there exists an optimal air flow rate to achieve the best pump performance. Maximum water discharged and maximum pumping head come when the air flow is roughly 50 m3 / h, which is slightly slowly than maximum efficiency. The dimensionless experimental data almost located in one function curve under any submergence ratio and is in good agreement with the theoretical model, the experimental value has a little error to the theory value with a deviation of 8%.The investigation on flow field structure shows that flow field velocity distribution in pipe is in the shape of a cone.The velocity gradient near the wall is large, and velocity distribution at the center area is flat. Liquid velocity increases with the increase of air flow rate and then decreases.With the increase of submergence ratio, the difference of liquid velocity between different air flow rate tends to be reduced.The research result is significant for further understanding of airlift mechanism and enriching dynamic theory of multiphase-flow, as well as it is of significance to study airlift system for underground mineral mining, oceanic mineral resources exploitation and sludge clearing in river or harbor.