Multistage turboexpander

Figure 1-10. Multistage turboexpander in natural gas letdown servioe. (Source GHH-Borsig.)...

Turboexpanders can be classified as either axial or radial. Axial flow expanders nave either impulse or reaction type blades and are suitable for multistage expanders because they permit a much easier flow path from one stage to the next. However, radial turboexpanders nave lower stresses at a given tip speed, which permits them to run at higher speeds. This results in higher efficiencies with correspondingly lower energy requirements. As a consequence, most turboexpanders built today are of the radial type. 

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