Method for efficient part load compressor operation

A method for compression of gas, comprising:

• (a) providing a gas compressor, the gas compressor comprising
• (1) a pressure case, the pressure case comprising a peripheral wall;
• (2) an inlet for supply of gas, and an outlet for compressed gas;
• (3) a first drive shaft extending along a first central axis;
• (4) a first rotor, the first rotor driven by the first drive shaft for rotary motion in a first direction within the pressure case, the first rotor comprising an outer surface portion, the first rotor further comprising blades, the blades each extending outward from the outer surface portion to a tip end, wherein the blades comprise impulse blades;
• and
• (5) a second rotor, the second rotor driven by the first drive shaft for rotary motion in a second direction within the pressure case, wherein the second direction is opposite in rotation from the first direction, the second rotor comprising (a) a fixed second rotor portion further comprising the plurality of converging-diverging passageways configured for supersonic compression of gas, the converging-diverging passageways having an inlet with an initial shock wave generating surface, a throat portion having a variable cross-sectional area, and an exit, the converging-diverging passageways each having a longitudinal axis, wherein the longitudinal axis is offset toward the first rotor by an angle of attack alpha (a), (b) an adjustable second rotor portion, and (c) a helical adjuster between the fixed second rotor portion and the adjustable second rotor portion, wherein the adjustable second rotor portion further comprises a shockwave-generating body extending outward from the adjustable second rotor portion into each of the converging-diverging passageways, each shockwave-generating body translatable using the helical adjuster to provide simultaneous axial and circumferential motion of the shockwave-generating body relative to the first drive shaft and wherein movement of each body along the longitudinal axis of the converging-diverging passageway in which it is located provides an increase or decrease in the cross-sectional area of the throat portion, thereby enabling both startup and supersonic gas compression operation of each converging-diverging passageway;
• (b) providing a throttle valve, the throttle valve located between the inlet for supply of gas and the first rotor, the throttle valve configured to adjustably regulate mass flow of incoming gas to be compressed;
• (c) providing a prime mover for providing rotary power to the first drive shaft;
• and
• (d) providing a gearbox and an adjustable speed drive, the gearbox configured to receive rotary power from the prime mover and provide rotating power to the first drive shaft at varying rotating speeds.