Methods and systems for variable geometry inlets nozzles for use in turboexpanders

A system for power generation including a turboexpander with at least two expansion stages, each of the expansion stages of the turboexpander being drivingly connected to a power generation unit, the system comprising:

• a controller configured to control (i) an angle of a first inlet guide vane provided at an inlet of a first expansion stage of the turboexpander for maintaining an inlet pressure of the first expansion stage in a predetermined range, and (ii) an angle of a second inlet guide vane provided at an inlet of a second expansion stage of the turboexpander for maintaining the inlet pressure at the first expansion stage in the predetermined range;
• the controller being configured to vary the angle of the second inlet guide vane while maintaining fixed the angle of the first inlet guide vane and to determine a power generated by the power generation unit for corresponding varied angles;
• and
• the controller being configured to determine a highest power from the determined power of the power generation unit and a corresponding angle of the second inlet guide vane and to adjust the angle of the second inlet guide vane independent of the angle of the first inlet guide vane to achieve the highest power.