| 摘要 |
PROBLEM TO BE SOLVED: To obtain a steam control valve which is inexpensive even in a plant under the temperature condition of main steam or reheating steam exceeding approximately 600°C. SOLUTION: A valve casing is constituted by a double wall, namely, an outer wall 20, and an inner wall 21. The outside steam chamber 25 formed between the inner and outer walls is divided into the upstream and the downstream at a valve sheet. Thus, at least two independent steam chambers, namely, an upper steam chamber 25a and a lower steam chamber 25b are constituted. Then steam or a fluid is circulated from the independent systems of the outside steam chamber through the medium of an interlock valve. At the time of rapid closing of a steam valve, the upper steam chamber 25a is controlled so that it has almost the same pressure as the system which is on the side more upstream than a main valve 7, and the lower steam chamber 25b is controlled so that it has almost the same pressure as the system which is on the side more downstream than the main valve 7. Thus, the deformation can be prevented in the inner wall caused by pressure. COPYRIGHT: (C)2007,JPO&INPIT
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