Patent ID: 9657574
Date: 2017-05-23
CPC Classifications: C22C,F01D,F05D

Claim:
1. A steam turbine that is formed to have rotor members which are formed of different materials from each other and which are joined to each other in an axial direction, the steam turbine comprising: a first rotor member; a second rotor member; a casing which includes a guide portion through which a working fluid is guided and a discharge portion through which the working fluid is discharged; a plurality of sealing portions that seal the casing from outside; and a plurality of bearings, wherein the first rotor member is formed of an Ni-based alloy, wherein the first rotor member includes a hollow inside in the axial direction, wherein the guide portion is open radially inward towards the first rotor member, wherein the first rotor member includes a rotor vane across which the working fluid passes, wherein the second rotor member is formed of a material which is more easily molded than the Ni-based alloy, wherein an inside of the second rotor member is solid, wherein the second rotor member is joined to the first rotor member at one end of the first rotor member in the axial direction, wherein the discharge portion is open radially inward towards the second rotor member, wherein the second rotor member includes a rotor vane, across which the working fluid passes, on a joint side with the first rotor member, wherein one of the sealing portions and one of the bearings are disposed away from the joint side of the second rotor member, wherein the first rotor member and a joint portion on the joint side of the second rotor member with the first rotor member are disposed in a pressure range, wherein a number of vane rows of the first rotor member is greater than a number of vane rows of the second rotor member, and wherein an average linear expansion coefficient of the first rotor member in a temperature range of room temperature to 700° C. which becomes an operation region of the steam turbine is in a range of 12.4×10