Steam turbine system and method for starting steam turbine

A steam turbine system comprising:

• a steam turbine having a casing into which steam is fed from an outside of the casing, and a rotating shaft that is provided within the casing so as to be rotatable around a central axis;
• a deaerator that is connected to the steam turbine and configured to deaerate leaked steam that has leaked from a gap between the casing and the rotating shaft to the outside of the casing;
• a vacuum pump that is connected to the deaerator and configured to lower a pressure within the deaerator;
• and
• a shaft sealing device that is connected to the deaerator and is configured to seal the gap between the casing and the rotating shaft,
• wherein the shaft sealing device has:
• a seal member having a seal body that is configured to seal a portion between the seal body and an outer peripheral surface of the rotating shaft, and a pressure-receiving part that is connected to the seal body and is configured to move the seal body in a radial direction of the rotating shaft;
• a housing that holds the pressure-receiving part in an accommodating recess formed therein so as to be movable in the radial direction;
• a biasing member that is configured to bias the pressure-receiving part toward an inside of the radial direction;
• and
• a negative-pressure introduction part that is configured to make a pressure inside the accommodating recess lower than a pressure outside the housing.