Process Simulation Of Three-stage Piston Push Centrifuge And Impact Analysis Of High Separation Rate And Low Erosion

According to the improvement requirements of the new three-stage piston push centrifuge,starting from the gradual increase of productivity and diversification of raw materials,it is determined that the structural optimization and operating parameters of the centrifuge have an important impact on the erosion phenomenon and the separation efficiency in the drum during the separation.Based on the theory,this paper uses a combination of experiment and simulation to analyze and summarize the centrifuge separation process,and determine the pretreatment parameters and coupling models that conform to the internal flow field.Finally,combined with the experiment,the size and law of the erosion of particles on each structure in the separation process are obtained.Specific studies are as follows:1)In the theoretical study of the gas-liquid-solid three-phase coupling model of fluid mechanics,many researchers only considered the influence of the internal flow field caused by the turbulent,continuous equal model in the centrifuge.By determining the model suitable model for the fluid-particle theoretical study of the flow field in the centrifuge,carrying out detailed analysis and research of the same type of methods and models,it is determined that the turbulence equation in the flow field in the centrifuge uses the SST k-ω model.And gas-liquid-solid three-phase mixed simulation selects the DDPM model that combines Euler’s method and Lagrange method to complete the process analysis of sodium chloride particle distribution,filter cake,and discharge.2)According to the experiment of sodium chloride particle size,the Py Charm editor is used to fit the distribution of actual value of discrete phase parameters.At the same time,the separation experiment was carried out with an industrial prototype,and the influence of the actual operating parameters on the separation rate was analyzed.Finally,combined with experiments,the error between simulation and experiment is reduced,and the reliability of numerical value is increased.The UG software was used to model the inner cylinder and pusher plate three times,and the ANSYS software was used to extract the flow field and grid the centrifuge.According to the experimental conditions and literature collection,the gas-solid-liquid pretreatment parameters are set,which improves the reliability.3)The calculation method of the flow field in the prototype is reasonably divided and analyzed from the numerical method.By comparing with the separation rate data of the prototype,it is concluded that the model error is within the acceptable range,and the accuracy meets the requirements.The pressure and velocity cloud map of the mixedphase shows that the uneven contact,the surge of the total pressure,and the differential velocity are concentrated in the pistons at all levels.After analyzing the discrete phase parameters,the erosion phenomenon mainly occurs on the screens at the piston pushing blocks at all levels.Moreover,it is concluded that in order to avoid particle accumulation and low erosion phenomenon,the feeding speed in actual production does not exceed 4m/s.When the particle size of sodium chloride is 0.07-0.2mm,the erosion rate of the screen conforms to the increase of the particle diameter.The increase proves the critical influence of material physical parameters on machine loss.Finally,the piston pushing block at all levels is determined as the main optimization component.4)Optimize the selection of the inclination angle of the pusher block structure at all levels,and determine that the pusher block with an inclination angle of 60° is the optimal structure.Compared with the 90° case,the erosion rate on the primary,secondary and third screens are reduced by 10%,45.7%,and 35.4%.The optimization effect is noticeable.Using the BBD response surface method and Design-expert to select the operating parameters,with higher separation rate and lower erosion rate as evaluation indicators,the optimal value is obtained as the pushing frequency40times/min,the drum speed 1431r/min,and the material concentration is 60%.