Patent ID: 8690532

Claim:
A nozzle box of an axial flow turbine, comprising: a lead-in pipe configured to lead a working fluid in a first channel direction; a bent pipe connected to the lead-in pipe and formed so as to change a direction of a channel center line from the first channel direction to a second channel direction, the second channel direction being an axial direction of a turbine rotor of the axial flow turbine and different from the first direction; and an annular pipe connected to the bent pipe, covering the turbine rotor from an outer peripheral side of the turbine rotor, and forming an annular passage leading the working fluid to a first-stage nozzle of the axial flow turbine while spreading the working fluid in a circumferential direction of the turbine rotor, wherein the lead-in pipe, the bent pipe, and the annular pipe form a working fluid channel from an inlet of the lead-in pipe toward an outlet of the annular pipe, the working fluid channel having a gradually increasing channel width in a first direction intersecting with the channel center line and a gradually decreasing channel width in a second direction intersecting with the channel center line and perpendicular to the first direction.