The single-stage impulse turbine is also called the de Laval turbine after its inventor. The turbine is made up of a single rotor with impulse blades attached to it. The steam is fed through one or more convergent-divergent nozzles that do not extend entirely around the circumference of the rotor, allowing the steam to impinge on only a portion of the blades at any given time. The nozzles can be put ON or Off to improve partial flow performance.
Steam passes through the nozzle to increase the Velocity, then enters the moving blade and exhausts our of the single stage impulse turbine. This stationary nozzle achieves complete expansion of steam against decrease in enthalpy thus an increase in kinetic energy of the steam.
The rotor rotates when steam passes through the nozzle and strikes the turbine blades that are fixed on the rotor. The rotor can be coupled to a drive unit such as a Pump, Blower, Fan or to electric generator to generate power.
Single stage impose turbines are very reliable equipment and are often used as promotes of critical machines such as Pump, Fan or a Blower in Oil and Gas Industry.