Abstract: Processes using multiple expansion turbines for efficient recovery of power from a plurality of very high pressure streams of superheated vapor are disclosed. Beneficially, processes of the invention use at least two classes of expansion turbines. Processes according to this invention are particularly useful for recovery of power from very high pressure streams of superheated steam in an olefins manufacturing process. Such streams are typically produced by thermal cracking of suitable petroleum derived feed stocks, and the olefins being produced and purified are typically ethylene and/or propylene.