Product Carbon Footprint of Cryogenic Turboexpanders Equipped with Active Magnetic Bearings in Hydrocarbon Gas Processing

This paper examines the lifecycle greenhouse gas (hereafter “GHG” or “product carbon”) footprint of turboexpanders used in an ethylene process, with a focus on comparing those fitted with magnetic bearings versus oil bearings. While the results favor the use of magnetic bearings, the analysis highlights the importance of considering appropriate boundary conditions and working hypotheses, which may introduce biases. For instance, the effectiveness of their sealing systems, as well as the type of gas or simply the simulation models used to evaluate losses, can significantly affect the results. However, this analysis helps quantify the amount of greenhouse gas (GHG) emissions from turboexpanders and indicates reducing emissions would not be the sole factor of bearing technology choice. The choice of magnetic bearings in turboexpanders is mainly driven by other advantages, including reliability, availability, and the elimination of oil contamination, all of which introduce indirect carbon emissions.