Development of an Axial Magnetic Bearing for Vertical-Type Centrifugal Separators

This paper presents a new axial magnetic bearing for the centrifugal separators, which are used to separate into liquids and solids in chemical, material industries, and so on. In order to separate much original liquid into the liquid and the solid for a short time, the centrifugal separators with large volume and large capability are required. To satisfy the requirements, the large axial magnetic bearing with the maximum axial magnetic force of 7,200 N is proposed. The features are as follows: 1) the magnetic field does not influence on the flow of the original liquid, and 2) the stiffness is relatively high also in the radial direction. The structure of the proposed axial magnetic force is shown and the control system configuration is also introduced. The optimal sizes of the electromagnets and permanent magnets are derived by the analysed results using Finite Element Method (FEM). The radial and axial forces are also computed by FEM for the rotor motion in the parallel and conical modes, respectively. It is confirmed that the enough suspension force is generated to support the rotor suspension part in the proposed axial magnetic bearing, which is quite suitable as the axial magnetic bearing in the vertical-type centrifugal separator.