This machine built by RMG integrates generator and turbo expander without the need for a gearbox between expander wheel and generator. Electricity is generated by expanding natural gas coming at high pressure from the transportation network prior to distribution to consumers. Typically, two units are connected in series or parallel depending on inlet pressure and gas flow-rate. The design challenge consisted in building a sealed and gearless machine running at high speed in order to achieve high power density. The Active Magnetic Bearings operate in pure natural gas atmosphere, thus, fulfilling ATEX requirements and greatly simplifying machine design. The shaft was designed to be sub-critical at 32000 rpm, allowing for a very compact machine.

Technical Data
Photo courtesy RMG Regel und Messtechnik GmbH, Kassel

Speed:	32'000 rpm
Rotor weight:	110 kg
Radial bearing:	ø110mm / 2200N
Motor power:	550 kW