Optimized performance strategy for a multi-stage volumetric expander

A multi-stage volumetric fluid expansion device comprising:

• a. a first fluid expansion stage having a first pair of non-contacting rotors disposed between a first inlet and a first outlet, the first fluid expansion stage being configured to generate useful work at the first pair of rotors by expanding a working fluid from a first pressure to a second pressure that is lower than the first pressure;
• b. a second fluid expansion stage having a second pair of non-contacting rotors disposed between a second inlet and a second outlet, the second fluid expansion stage being configured to generate useful work at the second pair of rotors by receiving the working fluid from the first fluid expansion stage outlet and expanding the working fluid to a third pressure that is lower than the second pressure;
• c. a third fluid expansion stage having a third pair of non-contacting rotors disposed between a third inlet and a third outlet, the third fluid expansion stage being configured to generate useful work at third pair of rotors by receiving the working fluid from the second fluid expansion stage outlet and expanding the working fluid to a fourth pressure that is lower than the third pressure;
• d. a first working fluid bypass line extending between the first inlet and first outlet of the first fluid expansion stage, the first working fluid bypass line including a first control valve;
• e. a second working fluid bypass line extending between the first inlet and first outlet of the second fluid expansion stage, the second working fluid bypass line including a second control valve;
• f. a power output device rotated by the first, second, and second third of rotors.