| 摘要 |
PROBLEM TO BE SOLVED: To provide the shaft seal device for a liquefied gas, capable of exercising shaft-seal function under a proper and stable condition, in a rotary machine which handles the liquefied gas. SOLUTION: A shaft seal means 5 is mounted in a seal case 4, and first to third seal chambers 6a, 6b and 6c are defined. The shaft seal means 5 supplies a purge gas 11 at a pressure lower than the pressure (pressure of liquefied gas 16) in a pump casing 2, to a purging chamber 10 formed between non- contact-type mechanical seals 8 and 9. The first seal chamber 6a and the second seal chamber 6b are communicated and connected by means of a communication passage 17 which passes to the outside of the seal case 4. The liquefied gas 16 which infiltrate into the second seal chamber 6b from the pump casing 2 via the third seal chamber 6c is evaporated by a heat exchanger 19 mounted on the communication passage 17, and the evaporated gas 16a is supplied to the first seal chamber 6a.
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