Screw compressor
A screw compressor includes a first seal, a second seal, and a third seal which are non-contact seals from a rotor side to a bearing side of a shaft seal portion, a compressed gas supply device which is different from a rotor that supplies compressed gas between the first seal and the second seal, and a heating device that heats the compressed gas supplied between the first seal and the second seal from the compressed gas supply device.
1 . 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.
2 . The screw compressor according to claim 1 , wherein
the casing includes a discharge port that discharges the high-pressure water vapor compressed by the rotor, and a compressed gas supply port that supplies the compressed gas between the first seal and the second seal, and
the screw compressor further comprises:
a first pressure sensor that detects a first pressure of the high-pressure water vapor that has been compressed by the rotor and flows through a first pipe connected to the discharge port;
a second pressure sensor that detects a second pressure of compressed gas flowing through a second pipe connected to the compressed gas supply port; and
a control device that controls a supply amount of the compressed gas supplied between the first seal and the second seal from the compressed gas supply device such that the second pressure is equal to or lower than the first pressure and higher than atmospheric pressure.
3 . The screw compressor according to claim 1 , wherein
the casing includes a discharge port that discharges the high-pressure water vapor compressed by the rotor, and a compressed gas emission port that emits the compressed gas from a space between the second seal and the third seal, and
the screw compressor further comprises:
a temperature sensor that detects a temperature of compressed gas flowing through a third pipe connected to the compressed gas emission port; and
a control device that controls a heating amount by the heating device such that the temperature detected by the temperature sensor is higher than a saturation temperature of water calculated based on a first pressure of high-pressure water vapor that flows through a first pipe connected to the discharge port and is compressed by the rotor.
4 . The screw compressor according to claim 1 , wherein
the casing includes a compressed gas emission port that emits compressed gas from a space between the second seal and the third seal, and
the screw compressor further comprises a heat exchanger that recovers heat from the compressed gas flowing through a third pipe connected to the compressed gas emission port in the middle of extension of the third pipe.