Patent ID: 6422807
Filing Date: 2002-07-23
Classification: F01D

Abstract:
A method of operating a turbine having a rotor including axially spaced buckets carried thereby forming parts of turbine stages, an outer containment shell, an inner shell about the rotor including nozzles carried thereby forming other parts of said turbine stages and shrouds about the respective tips of said buckets of said stages, and a passage formed in said inner shell for flow of a thermal medium to control thermal movement of said inner shell, comprising the steps of:flowing the thermal medium serially (i) through passage portions of the inner shell at a first axial location corresponding in part to an axial location of a second stage of said turbine, (ii) forwardly along said inner shell from said first axial location to passage portions of said inner shell at a second location corresponding in part to an axial location of a first stage of the turbine and (iii) rearwardly along said inner shell from said second axial location to passage portions of said inner shell at said first axial locations to control the thermal radial expansion and contraction of said inner shell and the clearance between the tips of the buckets and shrouds of each said first and second stages.