Fully floating inlet flow guide for double-flow low pressure steam

Abstract

A fully-floating inlet flow guide for a double-flow steam turbine includes a pair of partially overlapping, generally cylindrical sealing rings circumscribing a turbine rotor adjacent a steam inlet with each of the bands being coupled to a respective one of a pair of first stage nozzle rings positioned on opposite sides of the inlet for directing steam into an axial flow path. The rings are provided with an annular seal at their overlapping portions such that axial expansion and contraction is accommodated without steam leakage through the seal. Radial expansion and contraction of the sealing rings is accommodated by attachment of each ring to a respective nozzle using a circumferential groove in a radially inner surface of each nozzle ring diaphragm and a tongue on each of the rings which fits into a respective groove. Each tongue has a plurality of circumferentially spaced slots and a block slidingly positioned in each of the slots. A pin extends through the blade diaphragm at each slot and extends through the corresponding block so that the blocks are fixed with respect to the diaphragm. The blocks prevent rotation of the bands about the turbine rotor while permitting radial displacement of the bands since the blocks are only slidingly held in the slots.