METHOD TO REPAIR, RECONSTRUCT OR EXTEND AXIALLY A STEAM TURBINE DIAPHRAGM RING OR WEB
Publication Date: 2014-Mar-28
The IP.com Prior Art Database
The present invention proposes a technique for repairing, reconstructing or extending steam turbine diaphragm ring or web axially. The technique attaches a ring or multiple rings which are welded to the outer ring or inner web of any of the diaphragm. The rings are added either for an increased setback modification, steam seal face repair, diaphragm redesign or any other reason which requires material to be added to the diaphragm.
The present invention generally relates to a steam turbine and more particularly to a technique for repairing, reconstructing or extending steam turbine diaphragm ring or web axially.
In general, diaphragms are stationary components of steam path which guide steam and provide proper stage-by-stage distribution of available energy. The first stage diaphragms of any section are susceptible to damage like solid particle erosion (SPE). The erosion damage occurs predominantly on the discharge half of the suction (convex) side on reheat stages. The damage occurs due to collision of particles with leading edge of bucket and rebound into the nozzle trailing edge suction surface. Damage is also found on the steam seal face which fits to a casing on any section of the steam turbine and on exit appendages where spill strips or bucket tip packing ring are held. Clearance between the bucket and partition is called setback.
A conventional technique reduces solid particle erosion on first reheat stages or second stages by increasing the setback dimension to reduce the referred particle rebounding effect on the nozzle partitions.
Another conventional technique relates to minimizing or eliminating solid particles erosion damage in double-flow steam turbines by providing additional axial setback of first-stage nozzles from first-stage rotor buckets.
Yet another conventional technique reduces solid particle erosion in turbines by a protection means disposed over a portion of the suction side of nozzle partition.
However, the above mentioned conventional techniques do not repair steam turbines diaphragm.
Therefore there is a need in the art for a technique to repair, reconstruct or extend steam turbine diaphragm.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 depicts a ring or multiple rings welded to the outer ring or inner web of any of the diaphragm.
Figure 2 depicts two half rings with rabbet fits or dovetail manufactured to proper dimensions.
Figure 3 depicts conventional diaphragm ring and/or web surface which is to be extended or reconstructed and required to be rectified.
Figure 4 depicts ring located on the ring or web by the rabbet fit or tangentially welded on the inner and outer sides.
Figure 5 depicts the ring attachment which is made using an interference fit with different materials of different expansion coefficient.
Figure 6 depicts ring or web which is final machined to proper diaphragm dimensions.
The invention proposes a technique to repair, reconstruct or extend steam turbine diaphragm ring or web axially.
Figure 1 depicts, technique attaching a ring or multiple rings which are welded to the outer ring or inner web of any of the diaphragm.
As illustrated in the above figure, ring or multiple rings are attached to add material either for an increased setback modification, steam seal face repair, diaphragm redesign or an...