Tutorial On Cryogenic Turboexpanders.

Abstract

Cryogenic turboexpanders are used in many applications, including ethylene plants, refineries, gas processing plants, and air separation facilities. They frequently produce the coldest level of refrigeration available in the plant, and often operate with turbine outlet conditions such that large quantities of liquid are condensed during the expansion process. Turboexpanders have come a long way in the last 10 years. Their high efficiency and reliability have led to widespread use around the world. The use of magnetic bearings in some critical turboexpander applications such as ethylene plants has become common, and, in the natural gas processing market, they are making inroads as well. Computational fluid dynamics (CFD) programs are providing windows into aerodynamic improvements and new applications that were unheard of in the past. API 617 (2002) now addressed cryogenic turboexpanders in Chapter 4 of the Seventh Edition. Annex 4F of the same document provides guidelines for purchasing equipment using magnetic bearings, and this section is particularly applicable to turboexpanders. This tutorial will attempt to broaden the knowledge of engineers regarding cryogenic turboexpanders from the processes hey are used into their design and application.