Mechanical design of a superconducting demonstrator for magnetic density separation

Abstract

The focus of this paper is on the mechanical design of a NbTi-based demonstrator magnet for magnetic density separation (MDS) that is being constructed at the University of Twente. MDS is a new recycling technology that allows the separation of non-magnetic particles based on their mass density, using a vertical magnetic field gradient and a ferrofluid. The unique mechanical design challenge for this type of magnet is the desired minimization of the distance between a sim1 m2 planar array of cryogenic racetrack coils and the ambient-temperature ferrofluid bath. The optimization of the magnet geometry results in a distance between the coils and ferrofluid of 50 mm. This is made possible by opting for conduction-cooling, for the inclusion of room-temperature rods that pass through the cold mass to support the cryostat, and for the geometry of the cassette that reacts to the Lorentz force.

Literature Review of Suspension Systems for Superconducting Elements

“…A 4-rod + 4-post architecture has been proposed for the magnetic density separator studied at UT (University of Twente) (Figure 4b) [19]. The four posts are arranged vertically at each corner of the coil, while the four rods follow a criss-cross pattern.…”

Mechanical Analysis and Testing of Conduction-Cooled Superconducting Magnet for Levitation Force Measurement Application

“…Modeling each conductor's components leads to modeling difficulty and is time-consuming for computation. However, the different materials of the superconducting coil can be treated as homogeneous orthotropic materials, whose equivalent material properties can be approximately obtained by homogenization techniques based on a finite element method [28][29][30]. The materials constituting the conductor as well as the support structure's materials are given in Table 2 [31,32].…”

Thermal and electrical design of superconducting demonstrator for magnetic density separation

“…This support structure exhibits the conflicting requirements of low thermal conductance and high mechanical strength. The optimization of the chosen fibreglass structure is described in [16].…”

“…The peak magnetic field at the full operating current of 300 A is 5.2 T and the average magnetic field magnitude at the bottom of the fluid bed is 2.0 T. The present manuscript focuses on the thermal design of the magnetic system, and on the electrical circuits used to excite and protect it. The electromagnetic design of the magnet is detailed in [8,14,15], and the mechanical design in [16].…”

“…The columns pass through holes in the cold mass and stay at room temperature. The increase in performance of a conduction-cooled single-walled configuration supported with columns relative that of a bath-cooled double-walled option is estimated at a factor 2 [16]. Other advantages are the absence of cryogens and reduced system mass.…”