Patent Application
20090320288
The present disclosure is directed to a method of repair and, more particularly, to a method for repairing a turbine.
Turbines such as, for example, turbines used in turbochargers, may be driven by exhaust gases from an engine. The exhaust gases may expand while flowing through the turbine with the expansion energy causing the turbine blades to rotate. Because exhaust gases may be at very high temperatures and include combustion particles, significant wear may occur on the blades of the turbine. For example, exhaust gases may cause cracks or bends to develop in the turbine blades. For smaller turbines, entire turbine components are often discarded and replaced at considerable cost instead of being repaired. Smaller turbines may also be repaired using laser deposition techniques such as plasma transferred arc laser spraying, but these techniques are typically costly and labor-intensive.
One attempt at repairing turbines is described in U.S. Pat. No. 7,278,829 B2 (the '829 patent) issued to Roedl et al. The '829 patent discloses a method for replacing an entire squealer tip disposed at an end of a turbine blade. The entire existing squealer tip is removed by grinding away the existing squealer tip material. A new squealer tip, made from a different alloy than the original squealer tip, is then welded to the blade.
Although the repair method of the '829 patent may provide a method for replacing a squealer tip of a turbine blade, it may fail to provide a method for determining a repair based on variables such as turbine type and application. The '829 patent replaces the entire squealer portion of the turbine blade, instead of determining a required repair area based on turbine type or application. Therefore, the repair method of the '829 patent may replace more of the blade than is appropriate for a given turbine, resulting in a substantial waste of materials when numerous turbines are repaired.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.
In accordance with one aspect, the present disclosure is directed toward a method for facilitating turbine repair. The method includes determining wear characteristics of a turbine blade based on at least one of turbine type or turbine application. The method also includes determining a delineated repair area on the turbine blade based on the determined wear characteristics of the turbine blade. The method additionally includes providing a replacement turbine blade part generally matching the size, shape, and material of the turbine blade.
According to another aspect, the present disclosure is directed toward a method for repairing a turbine. The method includes locating a predetermined repair area on a turbine blade. The method also includes removing a portion of the turbine blade corresponding to the predetermined repair area. The method additionally includes attaching a replacement turbine blade part to the turbine blade at the repair area, the replacement turbine blade part having material and dimensions generally matching the removed portion of the blade.
As illustrated in
As the exhaust gases expand against blade 16 at high temperature and velocity, solid particles contained within the exhaust may strike blade 16, causing deterioration. The wear characteristics of blade 16 (i.e., a manner in which the exhaust gases affect blade 16) may vary based on any engineering variable associated with turbine operation such as, for example, turbine application and type. Turbine type factors affecting the wear characteristics of blade 16 may include, for example, a size of turbine 10, whether turbine 10 is shrouded or shroudless, and whether turbine 10 is contra-rotating. Turbine application factors affecting the wear characteristics of blade 16 may include, for example, whether turbine 10 is a turbocharger, supercharger, turbopump, or turboexpander. The amount and locations of deterioration occurring on blades 16 may vary as the type and application of turbine 10 varies. Determining the wear characteristics of blade 16 may include accounting for locations of blade 16 that may be prone to developing more significant amounts of wear than other locations of blade 16. The wear characteristics of blade 16 may be determined empirically through experience and observation, theoretically through calculation, by dynamic modeling, or by any other suitable engineering methodology known in the art.
A delineated repair area 20 may be determined based on the determined wear characteristics of blade 16. Delineated repair area 20 may be predetermined (i.e., determined before turbine 10 is put into service). Delineated repair area 20 may be a spatial representation of the wear characteristics of blade 16 that may cause turbine 10 to operate improperly. For example, for a given type and application of turbine 10, blade 16 may be determined to have wear characteristics of becoming deteriorated near outer diameter 15 to an extent that turbine 10 operates improperly. Delineated repair area 20 may be determined so that it envelopes (i.e., completely includes) the locations on a blade 16 that may become deteriorated from exhaust gases and affect turbine 10 to operate improperly. Delineated repair area 20 includes a portion of blade 16 that is less than the entire blade 16. Because delineated repair area 20 may include only a portion of blade 16, significant savings in material may be achieved by avoiding an unnecessary removal of an entire blade 16. The size and shape of the delineated repair area 20 may be labeled on blade 16 by any suitable method known in the art such as, for example, marking blade 16 itself, or marking a physical model or a computer-aided design (CAD) model of blade 16. A repair schedule may be developed that provides a plurality of delineated repair areas 20 for various types, applications, and other engineering variables affecting turbine 10. The repair schedule may indicate when to attach the insert 26 to blade 16. It is contemplated that the blade repair method may be applicable to a plurality of blades 16 of turbine wheel 14.
Referring to
Turbine 10 may be monitored for indications of deterioration and periodically inspected during its service life. When actual deterioration is observed on blade 16 that approaches an extent of delineated repair area 20, thereby potentially affecting turbine 10 to operate improperly, blade 16 may be repaired. Delineated repair area 20 includes only a part of blade 16, and a portion 25 of blade 16 that generally matches delineated repair area 20 may be removed, as illustrated in
After portion 25 has been removed, insert 26 may be attached to a remaining portion 28 of blade 16 as illustrated in
Laser 30 may weld insert 26 to remaining portion 28 by any suitable welding method known in the art such as, for example, butt-welding. Butt-welding may be an autogenous welding method that requires no filler or additional welding material. As illustrated in
The disclosed method may provide a repair for turbine 10 accounting for wear characteristics of blade 16 that may vary as a function of turbine type and application. Because delineated repair area 20 may be determined based on variables such as turbine type and application, only part of a blade 16 may be replaced, saving significant cost and materials when numerous repairs are made. Additionally, because insert 26 may be pre-fabricated based on dimensions of delineated repair area 20 and maintained on hand, turbine 10 may be quickly repaired. A quick repair of turbine 10 may reduce the amount of time turbine 10 is taken out of service, which may increase productivity.
Turbine 10 may be repaired by method steps 42, 44, 46, 48, 50, and 52, illustrated in
In step 48, turbine 10 may be put into service. Maintenance personnel may monitor turbine 10 by periodically inspecting blade 16 for deterioration. Maintenance personnel may refer to the repair schedule to compare delineated repair area 20 to any indication of deterioration on blade 16. When actual deterioration on blade 16 approaches an extent of delineated repair area 20, maintenance personnel may obtain an appropriate insert 26, according to the repair schedule, and stop the operation of turbine 10. To improve maintenance efficiency, maintenance personnel may coordinate the simultaneous repair of several blades 16 and/or numerous turbines 10.
In step 50, maintenance personnel may use delineated repair area 20 as a reference to remove portion 25 from blade 16. In step 52, maintenance personnel may attach insert 26 to remaining portion 28 of blade 16, and turbine 10 may be put back into service.
As noted above, the method of
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed repair method. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and apparatus. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
