Industrial High Speed Turbogenerator System For Energy Recovery

The developed turbogenerator system is designed for process gas expansion producing a maximum of mechanical turbine power of about 70 kW that is fed as electrical power into the grid. In this arrangement the radial inflow expander turbine is mounted on the shaft of a permanent magnet excited high speed synchronous generator, supported by 5 axis active magnetic bearings. This arrangement eliminates the gearbox and is absolutely oil free. A novel static frequency inverter using flexible closed loop vector control improves machine application and allows a very wide range of speed with a nominal value of 45,000 rpm. On the grid output, pure sine currents with a power factor of 1 is fed to the grid. Active magnetic bearings prevent every type of process fluid contamination and seals are only to prevent excessive loss of process fluid. In the first test phase the proposed package was tuned and tested in steady state and transient conditions on a specially developed test stand using an identical second machine as a motor linked to the generator package under test via a flexible high speed coupling. In a second phase, the turboexpandergenerator package was tested in nominal conditions in an open loop with pressurized air, connected to a 460 VAC 60Hz grid.