hermetically sealed compressor

MAN Diesel & Turbo wins order to deliver a complete compressor system to extend a gas storage cavern in Staßfurt (Saxony-Anhalt, Germany) from RWE, one of Germany’s largest electricity and gas suppliers.

The hermetically sealed type HOFIM unit will increase the capacity of the storage cavern from around 380 million standard cubic metres of natural gas at present to as much as 500 million standard cubic metres. Weighing around 80 tonnes, the unit comprises two multi-stage radial compressors arranged in tandem around a centrally positioned 14-MW motor driver. The driver was specially developed and manufactured by MAN Diesel & Turbo for use in compressor units with magnetic bearings.

Their tandem arrangement enables the compressors to feed gas into and out of the storage cavern, operating either in parallel or in series. The system achieves its highest output of 350,000 standard cubic metres an hour in parallel, and peak pressure of over 160 bar in series operation. 

Because it is hermetically sealed, the complete compressor unit does not require dry gas seals on the drive shafts. At the same time, the sealing virtually eliminates the possibility of any gas escaping into the atmosphere. Moreover, the rotating shafts are located in magnetic bearings and float freely in the bearing points, without touching the bearing and therefore without friction, eliminating the need for any lubrication throughout the system.