Design of a Hermetically Sealed Chemical Pump with Magnetic Bearings

Increasing demands for environmental protection and severe anti-pollution regulations have led to an extended market for hermetically sealed pumps, e.g. so called canned-motor pumps. The usually installed medium-lubricated hydrodynamic bearings reach their limits of operation if the medium has very poor lubrication characteristics and/or contains gas. Also temperature shocks or bearing overloads may damage such conventional bearing arrangements. Active magnetic bearings seem to be an interesting alternative in such a case. The focus of this study is the possibility to integrate magnetic bearings to one-stage chemical pumps which are available typically in the range of 2 kW to 15 kW. Not only the design of one suspension system is the objective, but the comparison of conventional radial/axial magnetic bearing designs and conical hearing shapes. The influence of the stainless-steel can inside the stator and around the rotor is calculated numerically for static conditions. A test rig is introduced which allows the evaluation of the static calculations and the quantification of power losses caused by Eddy current effects in the can.