Shroud vortex remover
AssigneeGeneral Electric Company
InventorsSudhakar Neeli, Prakash Bavanjibhai Dalsania
Life of this patent
Estimating the term…
Abstract
Tip shrouds on last stage buckets for condensing steam turbines may create significant blockage and form a vortex at the wall of the steam guide of the diffuser, causing the steam flow to separate from the wall of the steam guide. Vortex formation reduces the effective flow area for the remaining fluid to diffuse, causing poor recovery. An inward radial depression is provided of a predetermined depth and distance along an outer steam guide, which redirects the tip leakage flows slightly downward, reducing a shroud blockage effect. This deflection assists the main flow in rejoining the steam guide, thereby making the diffuser more effective.
Claims20
A low-pressure steam turbine comprising:
- an inner casing including a last stage bucket annulus;
- tip shrouds on a plurality of buckets of the last stage bucket annulus;
- an exhaust hood surrounding the inner casing;
- and
- an axial radial diffuser comprising an inner steam guide and an outer steam guide within the exhaust hood at the outlet of the last stage bucket annulus wherein an inner wall of the outer steam guide includes an inward radial depression adapted to reducing a vortex of steam on the inside wall of the outer steam guide downstream from the outlet of the last stage bucket.
An axial radial diffuser disposed downstream from a last stage annulus of buckets for a condensing steam turbine within an exhaust hood, the diffuser comprising:
- an inner steam guide including an inner wall;
- an outer steam guide including an outer wall;
- an inward radial depression disposed downstream from the outlet of the last stage bucket on an inside wall of the outer steam guide wherein the axial positioning and a depth of the depression are selected to reducing a steam vortex on the outer radial wall downstream from the outlet of the last stage bucket.
A method for reducing vortex formation on an outer steam guide of a diffuser for a steam turbine downstream of last stage buckets with tip shrouds, the method comprising:
- disposing an outer steam guide and an inner steam guide at an outlet annulus of last stage buckets;
- providing a inward radial depression on an inside wall of the outer steam guide wherein the inward radial depression is disposed at a predetermined axial distance downstream from the centerline of the last stage buckets and at a predetermined depth, wherein the axial distance and depth are adapted for reducing the vortex formation along the outer wall of the outer steam guide.
Dependencies are inferred from the claim text.