The first scheduled inspection of the magnetic bearings turbogenerator (MTG) operated by Kogas in Gimhae station was jointly performed by Kogas, SKF and Cryostar in autumn 2017.

Designed by Cryostar for recovering energy from natural expansion in low footprint/low flow pressure let down stations, the MTG turbine is equipped with SKF S2M Magnetic Bearings and integrates a high-speed generator, also supplied by S2M.

A press release explained the MTG makes it possible to generate 300 kW of clean electricity from what looks like a 1.8 m long/18 ‘’ diameter piece of pipe. Its compact design allows in-pipe installation saving civil engineering costs.

The pressure to power application

Turbines for Pressure to Power application are designed to recover the energy from expansion of natural gas on a natural gas grid. This is clean energy generation, as no fossil fuel is burned.

Cryostar has an extensive experience with Pressure to Power application. Its’ portfolio for this application includes oil-free MTG, 300 kW expander equipped with SKF S2M Magnetic Bearings, and also TG turbogenerators, power up to 20 MW, fitted with oil bearings. MTG and TG turbines are equipped with variable inlet nozzles, and can therefore keep a high efficiency over a wide operating range. It can be operated 24 hours a day, 7 days a week, generating green power from energy that would otherwise have been wasted.

Inspection results

This inspection showed that all the internal components, including the turbine wheel, generator and Magnetic Bearings were in very good conditions, confirming the excellent performance of the machine during operation. One of the advantages of the Magnetic Bearing technology is the virtually maintenance-free operation due to the contact-free rotation controlled by reliable electronics.

This inspection confirmed that the MTG technology (magnetic bearings and high speed generator) is the right choice for energy recovery in pressure let down stations with low flow and reduced space.