Screw compressor

A screw compressor comprising:

• a casing;
• a rotor that is disposed in the casing, compresses low-pressure water vapor sucked from one end side of the casing into high-pressure water vapor, and emits the high-pressure water vapor to the other end side of the casing;
• a rotation shaft of the rotor supported by a bearing;
• a shaft seal portion of the rotation shaft formed between the rotor and the bearing;
• and
• a plurality of seals arranged at predetermined intervals at the shaft seal portion of the rotation shaft on a discharge side along an axial direction of the rotation shaft, wherein
• the plurality of seals includes:
• a seal that increases flow resistance of a fluid passing between the seal and the rotation shaft and is not in contact with the rotation shaft;
• and
• at least a first seal, a second seal, and a third seal from a rotor side toward a bearing side of the shaft seal portion, and
• a compressed gas supply device that supplies compressed gas between the first seal and the second seal and is different from the rotor, and a heating device that heats the compressed gas supplied between the first seal and the second seal from the compressed gas supply device are provided.