Abstract: A method and apparatus for implementing a thermodynamic cycle. A heated gaseous working stream including a low boiling point component and a higher boiling point component is separated, and the low boiling point component is expanded to transform the energy of the stream into useable form and to provide an expanded relatively rich stream. This expanded rich stream is then split into two streams, one of which is expanded further to obtain further energy, resulting in a spent stream, the other of which is extracted. The lean unexpanded stream and the spent rich stream are then combined in a regenerating subsystem with the extracted stream to reproduce the working stream, which is then efficiently heated in a heater to provide the heated gaseous working stream that is separated.

Abstract: Converting heat in a primary fluid (e.g., steam) to useful energy by multistage expansion of the primary fluid, heating of a multicomponent working fluid in a separate closed loop using heat of the primary fluid, and expansion of the multicomponent working fluid. The primary fluid in a vapor state is expanded in a first stage expander to obtain useful energy and to produce a partially expanded primary fluid. The partially expanded primary fluid stream is then separated into liquid and vapor components and split into a vapor stream (which is expanded in a second stage expander) and a further primary stream (which used to heat the multicomponent working fluid).