EP-4737726-A1 - SCREW COMPRESSOR

Abstract

A screw compressor (100) includes a first seal (8a), a second seal (8b), and a third seal (8c) which are non-contact seals from a rotor side (3) to a bearing side (10) of a shaft seal portion (16), a compressed gas supply device (40) which is different from a rotor that supplies compressed gas between the first seal (8a) and the second seal (8b), and a heating device (14) that heats the compressed gas supplied between the first seal (8a) and the second seal (8b) from the compressed gas supply device (40).

Inventors

• KAWAMURA, HIRONOBU
• SEKIYA, SACHIO
• MAITA, HIROSHI
• NUKAGA, HARUKI
• HASHIMOTO, KENTO

Assignees

• Hitachi, Ltd.

Dates

Publication Date

20260506

Application Date

20250710

Claims (4)

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.

Description

BACKGROUND OF THE INVENTION [Field of the Invention] The present invention relates to a screw compressor that compresses water vapor. [Description of Related Art] Conventionally, there has been known a screw compressor that compresses gas, in which a first non-contact seal, a second non-contact seal, and a contact-type lip seal are disposed from a compression chamber side toward a bearing side of a discharge-side shaft seal portion (see, for example, Patent Literature 1). Specifically, when gas is compressed by a rotor, the screw compressor injects water into the compression chamber to lubricate the rotor. In the screw compressor, a part of the gas compressed by the rotor is supplied to a space formed between the first non-contact seal and the second non-contact seal after dehumidification. A space formed between the second non-contact seal and the lip seal communicates with an atmosphere side. According to the screw compressor, since the compressed gas is supplied to the space between the first non-contact seal and the second non-contact seal, it is possible to suppress leakage of water from the compression chamber to the discharge-side shaft seal portion. Further, according to this screw compressor, even if water from the compression chamber leaks into the space between the second non-contact seal and the lip seal, the water is released to the atmosphere side. The screw compressor prevents an occurrence of a situation in which water in the compression chamber reaches a bearing beyond the lip seal. The screw compressor can prevent breakage of the bearing caused by deterioration of lubricating oil of the bearing due to water. [Citation List] [Patent Literature 1]: JP5714945 [Summary of Invention] [Technical Problem] Meanwhile, a screw compressor that compresses water vapor supplies high-pressure water vapor obtained by compressing water vapor with a rotor, from a discharge-side end portion of the rotor to a use side of the high-pressure water vapor through a discharge port of a casing. In such a screw compressor, when high-pressure water vapor is supplied to the use side, it is necessary to more effectively suppress leakage of high-pressure water vapor from the compression chamber to a shaft seal portion formed between the discharge-side end portion of the rotor and a bearing. Further, in the screw compressor, it is also necessary to prevent an occurrence of a situation in which condensed water in the shaft seal portion flows into the bearing side. Therefore, in such a screw compressor, it is also conceivable to adopt a configuration of the conventional screw compressor (see, for example, JP 5714945 B). However, in the conventional screw compressor, gas compressed by the rotor is used for suppressing leakage of water from the compression chamber to the shaft seal portion. Therefore, in the conventional screw compressor, the supply amount of the compressed gas to the use side decreases. In addition, since the conventional screw compressor uses the lip seal in contact with a rotation shaft of the rotor, the power loss due to the seal frictional resistance increases, and the efficiency of the screw compressor decreases. In addition, in the screw compressor that compresses water vapor, although it is desired to suppress the generation of condensed water in the shaft seal portion, it is not possible to sufficiently suppress the generation of condensed water in the shaft seal portion only by supplying the dehumidified compressed gas to the shaft seal portion in the conventional screw compressor. Thus, a screw compressor that compresses water vapor is desired to be capable of sufficiently securing a supply amount of high-pressure water vapor to the use side, being excellent in efficiency of the screw compressor, and being capable of sufficiently suppressing generation of condensed water in the shaft seal portion. An object of the present invention is to provide a screw compressor capable of sufficiently securing a supply amount of high-pressure water vapor to a use side, being more excellent in efficiency of the screw compressor than the related art, and being capable of sufficiently suppressing generation of condensed water in a shaft seal portion. [Solution to Problem] To solve the above problems, according to the present invention, a screw compressor includes 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, in which the plurality of seals includes a seal that increases flow resistance of a fluid passing between the seal