Patent ID: 7387486

Claim:
An axial flow steam turbine assembly, comprising: a first turbine having a first rotor with at least one rotor disc, a first turbine casing, a first steam outlet and a plurality of first impulse turbine stages, each first impulse turbine stage having a diaphragm with an annular row of first static blades extending between a first outer static ring mounted to the first turbine casing and a first inner static ring, a first sealing device acting between the first inner static ring and the first rotor, and an annular row of first moving blades having first root portions held in the rotor disc; and a second turbine having a rotor drum, a second turbine casing, a second steam inlet communicating with the first steam outlet, and at least one modified turbine stage having an annular row of second static blades extending between a second outer static ring and a second inner static ring, an annular row of second moving blades having second root portions held in peripherally extending slots of the rotor drum, a second sealing device acting between the second inner static ring and the rotor drum, the second outer static ring being axially located in a recess in the second turbine casing, wherein the second outer static ring has greater thermal inertia and greater stiffness than the second inner static ring and is capable of limited radial movement relative to the second turbine casing, and wherein one of the first and second turbines is a higher pressure turbine, and the other of the first and second turbines is a lower pressure turbine.