Patent ID: 8979480
Filing Date: 2015-03-17
Classification: F01D,F05D

Abstract:
1. A steam turbine comprising: a rotor; a rotor disc integrated with the rotor; a plurality of blades studded in the rotor disc in an arrangement along a circumferential direction of the rotor; a casing that covers the rotor; a plurality of vanes attached to the casing along the circumferential direction of the rotor in positions adjacent to the blades and on an upstream side in an axial direction of the rotor; and an internal diaphragm disposed on rotor-side surfaces of the vanes in the axial direction of the rotor in such a way that the internal diaphragm faces the rotor disc, in which the vanes and the blades adjacent to each other in the axial direction of the rotor form a turbine stage, wherein in at least one of the turbine stages, a rotor-side cooling path is formed through the rotor disc in the axial direction of the rotor and a diaphragm-side cooling path is formed through the internal diaphragm in the axial direction of the rotor, and a cooling medium flowing through the rotor-side cooling path diverts into the diaphragm-side cooling path and a labyrinth flow path provided between the internal diaphragm and the rotor, and wherein a plurality of turbine stages, each of which has the diaphragm-side cooling path which passes through the internal diaphragm in the axial direction of the rotor and through which the cooling medium flows, are formed, and among the plurality of turbine stages, each of which has the diaphragm-side cooling paths formed therein, the diaphragm-side cooling path is formed in parallel to the axis of the rotor in an upstream-side turbine stage, an outlet of the diaphragm-side cooling path which is linearly formed is positioned radially closer to the rotor than an inlet of the diaphragm-side cooling path in a downstream-side turbine stage, and an inclination angle of the diaphragm-side cooling path in a next downstream-side turbine stage to the axis of the rotor is greater than the inclination angle of the diaphragm-side cooling path in the downstream-side turbine stage to the axis of the rotor.