Oil-Free Compressor Systems for Gas Pipelines: Is now the Time?

The "World's First Oil-Free Compressor" was commissioned in the NOVA (now TransCanada Pipelines) gas transmission system in 1985. This move to oil-free technology was driven initially by a desire to reduce unscheduled downtime by removing the problematic oil seal and lubrication systems. Over the years more compressors were equipped with dry gas seals and magnetic bearings. By 1992, 34 compressors totaling about 60 percent of the installed power of the NOVA system were running on magnetic bearings. At that time problems with the reliability of the magnetic bearings were noticed and the oil-free compressor program was reviewed. The main reasons for these problems in the early days were connectors, amplifiers, auxiliary bearings, and some design and training issues (see “Magnetic Bearing Improvement Program: History and Details”, Alves et al, NOVA GTL at MAG ’95). These problems were corrected over the next three years and since then the systems have worked satisfactorily.