Development of gas foil thrust bearings for high-speed cryogenic turboexpander

Abstract

Cryogenic turboexpander is considered; as the heart of modern gas liquefier for its high thermodynamic efficiency and high reliability. The operating speed of small-sized turboexpander is usually greater than 50,000 rpm. Such high rotational speed brings constrain in the selection of the bearings. Oil-free gas bearings is a novel approach to keep the process gas contamination free. In the current research, a pair of gas foil thrust bearings (GFTB) are designed and developed for a vertical turboexpander used in nitrogen liquefier. The rotational speed of the rotor is 80,000 rpm with an axial load of 83 N in the direction of turbine wheel. The author believes the detailed design and development methodology will be helpful to the bearings designer around the globe.