Numerical Simulation And Drum Angle Research On Flow Field Of Centrifuges

Centrifuges are one of the most widely used solid-liquid separation equipments at present. However, there are many serious accidents, such as high-speed plug and stuck, due to design flaws and the variations of separation environment. The main reason for the above problems is the unreasonable match of separation speed and feed rate.The fundamental reason is lack of theoretical study of centrifuge that the intrinsic link between separation medium movement and the structure size of centrifuge was not be grasped. Grasp of the fluid movement station and law in separate field play a role in centrifuge design and structure optimization, and meanwhile lay a foundation for centrifuge research.The mathematical model of the fluid motion is established on the basis of full study of separation liquid. And then the separation liquid motion model is derived without the spiral influence. On this basis, the finite element model of centrifuge is established and variation laws of liquid flow velocity and pressure under controlled parameters are achieved.Firstly, the material properties of separation liquid is defined that the physical and chemical properties are clarified, according to the features of architecture mud. Meanwhile, the in-depth study of centrifuge separation features lay the foundation for the study of motion law of solid particles.Secondly, the material motion model in centrifugal force field is inferred by the cylindrical coordinates method. And based on this, the velocity an pressure law used by the simulation model is achieved.Finally, the three-dimensional model of centrifuge is built by GAMBIT, which owed to FLUENT. And the meshing and boundary conditions are done. Motion simulation of centrifuge model by FLUENT analysed relationship between the axial, circumferential, and radial velocity and structure parameters, simulated the small solid particles' motion, and studied the pressure law of centrifugal field, which gained the variations of dynamic pressure and static pressure along the axis.The results are followed.1) Axial velocity is complex, which is greatly influenced by the geometry. It decreases during the liquid flows from tube to internal of drum, and the lowest axial velocity appears at the sub-feeder section. Results show that the rotate speed boost of drum is not conducive to the flow of the axial flow, and decreasing rate of axial velocity coefficient is basically the same with different liquid layer depth.2) Radial velocity is the key to the separation. Compare of simulation and calculation results shows that Viscous force of the drum wall decreases with the increase of depth of liquid, and the lagged values increases with the increase of rotate speed.3) Dynamic pressure and static pressure of centrifuges meet the basic law of rotational eddy current pressure. They all gradually increase along the direction of the liquid ring radius, and reach the maximum at the drum wall.4) The sediment thickness of centrifuge is closely linked to the cone angle. As the angle changes, sediment thickness decreases. The same cone angle is difficult to meet the separation of large particles and small particles at the same time. As to the deficiency, the double tapered drum is designed, and it is verified that it can improve the disadvantages of single cone angle to some extent.