| 摘要 |
PURPOSE:To facilitate fabrication and disassembly and to reduce production of thermal stress, by a method wherein a main steam inlet tube is formed by a double-circular tube, and steam, which has temperature and a pressure lower than those of main steam and higher than those of exhaust steam, is supplied between the outer and the inner tube of the double-circular tube. CONSTITUTION:A first inlet circular tube 28, extending through an opening part 30 of an internal wheel chamber of a main steam inlet part, is provided and is connected to an inlet joint 26 and an internal wheel chamber 21. A second inlet circular tube 29 is disposed at the outside of and concentrically to the inlet circular tube 28, and is connected to an inlet joint 26 and the opening part 30 of the internal wheel chamber. Steam 55, bled from an intermediate step of stages, is supplied to a passage 56 leading between the inlet circular tubes 28 and 29 to reduce a difference in pressure and temperature between the inside and the outside of the circular tube. As noted above, a steam inlet is of a double structure, and this facilitates fabrication and disassembly, and eliminates a spot where thickness is suddenly changed, resulting in the possibility to decrease concentrztion of thermal stress. |
