| 摘要 |
PROBLEM TO BE SOLVED: To improve a sealing performance of a steam turbine without affecting an operation of the steam turbine. SOLUTION: This seal device for steam turbine comprises a labyrinth seal. In this labyrinth seal, fins 24 are provided to a peripheral surface of a turbine shaft 25, fins 23 are provided to a peripheral surface of a packing ring 22 having the peripheral surface opposite to the peripheral surface of the turbine shaft, and a pitch of each of the fins 23 of the packing ring 22 is arranged to be equal to a pitch of each of the fins 24 of the turbine shaft 25. In this seal device, a fin moving means is provided for moving and arranging the fins 23 at a side of the packing ring 22 with respect to the fins 24 of the turbine shaft 25 such that, at a steady operation at a high load of the steam turbine, respective tips of the fins 23 of the packing ring 22 and respective tips of the fins 24 of the turbine shaft 25 are alternately arranged with negative gaps 27a being provided in a radial direction, in order to provide a gap 27b between the respective tips of the fins 23 of the packing ring 22 and the respective tips of the fins 24 of the turbine shaft 25. |
