Numerical Simulation And Application Research Of Air-lift Pump Based On CFD

Air-lift pump is a device on account of the theory of air-lift, which lifts and conveys the materials to be located on the the bottom of device with compressed gas. It has been widely applied because there are advantages of the device, such as simple mechanical structure, no moving parts and simple technology. In view of that, the main field of its application includes mining of deep sea manganese nodules, conveying of chemical material, pumping water of deep well, pumping oil of deep well, dredging of the river and so on. Especially air-lift in the deep sea mining and dredging is considered as one of the most promising techniques. Aimed at the more serious problems of reservoir sedimentation, the paper takes into account the traditional mechanical structure used in the domestic river dredging equipment often results in low efficiency, large depletion and small depth of dredging. Centred on improving efficiency of the air-lift pump applied in reservoir dredging and route-orientated on solving the problems of the device, the paper expounds and makes conclusions from the following five aspects based on the exposed disadvantages of river dredging equipment in the practical use.(1) Summarizes the research of air-lift pump, related research at home and abroad and the engineering background pf the research subject. Discusses the existing advantages and disadvantages of the air-lift pump under the current conditions. Thus concludes:the widely applied air-lift pump in dredging field will have very good development perspective, which is a kind of advanced productivity. Puts forward the existing problems of the device and constructs the research technique route and research contents on the basis of that.(2) Studies the theory of air-lift and analyses the performance of the air-lift pump from multiphase flow in the pipe, the friction loss of the pipe and the efficiency of the device, which is under the work condition. Brings forward the design of process parameters of the air-lift pump.Thus concludes:The factors which affect the performance of the air-lift pump consist of the diameter of the riser, the submergence ratio, the flow rate of gas and the gas injection method.(3) Discusses the fundamental theory of the computational fluid dynamics(CFD) applied to air-lift pump. Based on the governing equations’general form of the common fluid, raises the numerical calculation strategy of multiphase flow in air-lift pump.Thus concludes: employs governing equations of the mixture model to study the multiphase flow, and discretizes the gonerning equation with finite volume method(FVM). Chooses the standard k-e model of eddy model as turbulent flow in the pipe. Additional treatment with standard wall functions in the near wall region of the pipe.Considers PISO algorithm of the segregated method as the solution method to accelerate the convergence speed.(4) Verifies and validates the feasibility of CFD numerical model applied to the air-lift pump. By building numerical model of known experiment carries on numerical calculation whose predictions have to be compared with the real experimental data for proving the consistency. Thus concludes:After comparing, the error of water flow between the present model and the experimental model is controlled in less than20%, which proves the numerical model is feasible and stable.(5) Puts forward the conceptual model of the air-lift pump applied in reservoir dredging. Combined with the actual condition, analyses the key factors affecting the performance of the pump. In the foundation of approximate processing the conceptual model, carries out optimization design of key parameters of the mixing tube,which utilizes CFD numerical simulation and orthogonal test. Thus concludes:Achieves optimum scheme of key parameters by numerical orthogonal test, and makes the efficiency of the device being up to84.58%, which realizes the target of high efficiency.