Rotordynamic Analysis and Operating Test of an Externally Pressurized Gas Bearing Turbo Expander for Cryogenic Applications

This study designed an externally pressurized bearing and analyzed the rotordynamics of a turbo expander for hydrogen liquefaction plant. The expander, comprising turbine compressor wheel assembled to shaft, lowered temperature helium refrigerant. Its rated speed was 75,000 rpm, gas selected support rotor. Pressurized used as lubricant operation. To design rotor–bearing system, we conducted performance analysis rotordynamic characteristic prediction using developed numerical model. We calculated stiffness flow rate various feed parameters appropriate orifice diameter maximum stiffness. predicted Campbell diagram showed that system had sufficient separation margin with critical speed, correlated well nonlinear orbit simulation. A successful operation achieved manufactured within speed. shaft vibration monitored during test, test results revealed two speeds below by analytical In addition, maintained at <3 μm.