Seal structure and control method therefor

摘要

The invention discloses a seal structure and a control method therefor that can improve sealing performance between a rotating portion and a fixed portion, smoothly start up a steam turbine (2), and suppress the temperature rise of the rotating portion even if the rotating portion is continuously rotated for a long period of time. A seal structure is configured such that seal fins (62) on a seal base-plate (61) side and corresponding breathable spacers (4b) on a rotor (2a) side are opposed to each other and breathable spacers (4a) on the seal base-plate (61) side and corresponding seal fins (2a1) on the rotor (2a) side are opposed to each other. The seal base-plate (61) is installed shiftably in a direction coming close to or moving away from the rotor (2a). If steam St has low pressure, the seal fins (62) and the corresponding breathable spacers (4b) are not in contact with each other and the seal fins (2a1) and the corresponding breathable spacers (4a) are not in contact with each other. If the steam St has high pressure, the seal fins (62) and the corresponding breathable spacers (4b) are in contact with each other and the seal fins (2a1) and the corresponding breathable spacers (4a) are in contact with each other.