Magnetic bearing applications & economics

Magnetic bearings offer a myriad of operational advantages and efficiency improvement over traditional oil lubricated bearings. They have been in use for the past thirty years, but for several reasons, including cost, have been limited to niche applications (such as high-speed turbomachines) that required their unique capabilities. Recent advances in the technology are making it more practical to apply these bearings in a broader range of applications. They have become much smaller, simpler and economical. In response, API Standards 617[1] (centrifugal compressors) and 684[2] (rotor dynamics) are being revised and will include sections on magnetic bearings. Other API Standards will surely follow suit. Hence, it is timely to review the actual operating history and performance of magnetic bearings, while taking a fresh look at the economics. In addition to a very basic (and generic) explanation of how these bearings work, this paper will examine the actual operating experience of one user in refining applications, as well as the overall experience within the oil & gas industry (including substantial experience in gas transmission). The paper will also offer a detailed economic analysis of the cost/benefit vs. oil lubricated bearings in a variety of applications that are important to the petroleum and chemical industry.