·         The motive power in a steam turbine is obtained by the rate of change of momentum of a high velocity jet of steam impinging on a curved blade, which is free to rotate.

·         The steam from the boiler is expanded in a nozzle, resulting in the generation of a high velocity jet. This jet of steam impinges on the moving vanes or blades mounted on a disc / drum.

Steam Turbine Stage

·         A turbine stage consists of stationary stator row (guide vanes or nozzle ring) and rotating rotor row.

·         In the guide vanes, the high pressure, high temperature steam is expanded, resulting in hi g h flow velocity.

·         The guide vanes also direct the flow to the rotor blades at an appropriate angle.

·         In the rotor, the flow direction is changed, and kinetic energy of the working fluid is absorbed by the rotor shaft producing mechanical energy

Steam Turbine Principle

·         Process of complete expansion of steam takes place in stationary nozzle and the velocity energy is converted into mechanical work on the turbine blades.

·         Pressure drop with expansion and generation of mechanical energy takes place in the moving blades.

·        Pressure drop may be partly effected in nozzles and partly in moving blades which are so designed that expansion of steam takes place in them. High velocity jet from nozzle produces an impulse on the moving blade and the jet coming out at still higher velocity from moving blades produces a reaction.

Steam Turbine Compounding

Steam Turbine Blades and Stages

Steam Turbine Specification