Patent Grant
8047786
This present application relates generally to systems and apparatus for modifying turbine wheel holes. More specifically, but not by way of limitation, the present application relates to systems and apparatus for enhancing turbine performance by reducing or plugging turbine wheel holes.
Turbine wheel holes are common in the turbine industry. Generally, these holes are defined through turbine wheels, which connect the turbine buckets or blades to the rotor. Turbine wheel holes allow the passage of a secondary flow of working fluid through the turbine wheels. This flow path may be provided for several reasons. First, for example, turbine wheel holes allow the leakage of secondary flow through the turbine wheel so to prevent reentry of the working fluid back into the primary flow path, which may cause inefficient flow patterns. In addition, wheel holes may be used to reduce the pressure drop across a turbine stage or to reduce axial pressure on the turbine wheel, which under certain operating conditions may be preferred or necessary. Generally, turbine wheel holes may measure approximately 0.5 to 3.0 inches in diameter and, when present, a turbine wheel may have approximately 3 to 15 wheel holes defined through its axial thickness.
Often, it becomes desirable to cover, plug, block or partially block turbine wheel holes Depending on certain operating conditions, it may be preferable to completely block turbine wheel holes so that no flow is allowed to pass therethrough, or it may be preferable to partially block turbine wheel holes, i.e., reducing the diameter of the wheel hole, so that a decreased amount of flow is allowed to pass therethrough. The reasons for blocking or reducing turbine wheel holes may be several. Many times, plugging the turbine wheel holes is done during the process of refurbishing older turbine engines. The plugging is done to improve the efficiency of the engine. However, processes, systems and/or apparatus currently used for plugging turbine wheel holes are overly complex, time consuming and expensive. Thus, there is a need for improved methods, systems and/or apparatus for plugging turbine wheel holes in an efficient and cost effective manner.
The present application thus describes an apparatus for plugging turbine wheel holes in a turbine wheel. The apparatus may include: 1) a body, the body being sized such that the body fits snugly into a turbine wheel hole; 2) a first flange at a first end of the body; and 3) a second flange at a second end of the body. The first flange and the second flange may lock the body into a preferred position in the turbine wheel hole.
The present application further describes a turbine wheel hole plug. The turbine wheel hole plug may include: 1) an approximate cylindrical body, the cylindrical body sized such that the cylindrical body fits snugly into a turbine wheel hole; 2) a first flange at a first end of the cylindrical body, the first flange being approximately cylindrical in shape and having a diameter that is larger than the diameter of the turbine wheel hole; and 3) a second flange at a second end of the cylindrical body, the second flange comprising a flared flange. The first flange and the second flange may lock the cylindrical body into a preferred position in the turbine wheel hole.
These and other features of the present application will become apparent upon review of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and the appended claims.
Referring now to the figures, where the various numbers represent like parts throughout the several views,
A main or primary flow path, which is indicated by arrows 124, is the flow path of the working fluid that is directed through the stationary diaphragms 104 and through the rotating blades 108. A secondary flow path, which is indicated by arrows 128, also may be defined. The secondary flow path 128 generally is much smaller in volume than the main flow path 124. The secondary flow path 128 is directed in an inward radial direction to a shaft seal 132. The shaft seal 132 creates a seal that limits the amount of working fluid that travels along the route of the secondary flow path 128. As one of ordinary skill in the art will appreciate, working fluid that bypasses the main flow path 124 (and thus bypasses the blades 108) decreases the efficiency of the turbine 100 because no work is extracted from it. The working fluid that does travel through the shaft seal 132 then generally travels in an outward radial direction until reaching one of the turbine wheel holes 120. The secondary flow then passes through the turbine wheel 112 via the turbine wheel holes 120 and continues toward the next shaft seal 132. The secondary flow path 128 then similarly traverses the next stage of the turbine 100, as illustrated.
As described above, leakage through the turbine wheel holes 120 may be advantageous under certain operating conditions. For example, the turbine wheel holes 120 may allow leakage of the secondary flow through the turbine wheel so to prevent reentry of the secondary flow back into the primary flow path, which may cause inefficient flow patterns in the primary flow. In addition, turbine wheel holes 120 may be provided to reduce the pressure drop across the turbine wheel 112, which under certain conditions, may be necessary. However, blocking, plugging or reducing turbine wheel holes 120 may become desirable, such as, for example, when an older turbine is being updated or refurbished and an increase in operating efficiency is desired.
At one end of the cylindrical body 142 of the turbine wheel hole plug 140, a first flange or upstream flange 144 may be formed, as illustrated in
The other end of the cylindrical body 142 may be a threaded extension 152, as illustrated in
As already described, depending on the certain conditions, it may be preferable to completely block the turbine wheel hole 120 so that substantially no flow is allowed to pass through it, or it may be preferable to partially block the turbine wheel hole 120, reducing its diameter so that a decreased amount of flow is allowed to pass through it. If it is desired that the turbine wheel hole 120 may be completely blocked, the cylindrical body 142 may be formed so that it is solid or forms a solid surface in the turbine wheel hole 120 that blocks substantially all of the secondary flow from traveling though the turbine wheel hole 120. (Note that insubstantial amounts of the secondary flow may still pass through the wheel hole 120 even when “completely blocked” via the small areas that may remain between the turbine wheel hole plug 140 and the turbine wheel hole 120.)
If, on the other hand, it is desired to reduce the amount of secondary flow moving through the turbine wheel hole 120 and not completely block it, the cylindrical body 142 may have a bore hole 156 (the diameter of which is indicated in
In use, the turbine wheel hole plug 140 may be installed in a turbine wheel hole 120 so that a preferred amount of working fluid is allowed through the turbine wheel hole 120. The turbine wheel hole plug 140 may be conveniently installed by inserting the body 142 through the turbine wheel hole 120 until the first flange 144 abuts the turbine wheel 112. As already described, the turbine wheel hole plug 140 preferably may be oriented such that the first flange 144 is upstream of the second flange 148. As described, this orientation may be reversed if desired. Once the body 142 is installed in the turbine wheel hole 120, the turbine wheel hole plug 140 may be fixed in place by securing the second flange 148, which, as described, may be done by screwing the second flange 148 on the treaded extension 152. The bore hole 156, if present, may be sized to a predetermined diameter such that in use a desired amount of working fluid is allowed to pass through the turbine wheel hole 120.
In some embodiments and as shown in
Like the first embodiment described above, the first flange or upstream flange 144 may be defined at one end of the cylindrical body 162, as illustrated in
At the other end of the cylindrical body 162 a flared flange 166 may be formed. As illustrated in
As already described, depending on the certain operating conditions, it may be preferable to completely block the turbine wheel hole 120 so that no flow is allowed to pass therethrough, or it may be preferable to partially block the turbine wheel hole 120 so that the diameter of the wheel hole 120 is reduced so that a decreased amount of flow is allowed to pass therethrough. If it is desired that the turbine wheel hole 120 be completely blocked, the flow determining portion 163 of the cylindrical body 162 may be solid (i.e., have a solid face) so that it blocks substantially all of the secondary flow from traveling though the turbine wheel hole 120. (Note that insubstantial amounts of the secondary flow may still pass through the wheel hole 120 even when “completely blocked” via the small areas that may remain between the turbine wheel hole plug 140 and the turbine wheel hole 120.)
If, on the other hand, it is desired to reduce the amount of secondary flow moving through the turbine wheel hole 120 and not completely block it, the flow determining portion 163 of the body 162 may have a bore hole 156 (the diameter of which is indicated in
In use, the turbine wheel hole plug 160 may be conveniently installed in a turbine wheel hole 120 so that a preferred amount of working fluid is allowed through the turbine wheel 120.
Once this is complete, a wedge block 176 may be placed into the position shown in
Once the turbine wheel hole plug 160 is secured in place by the wedge block 176, the flared flange 166 may be created by deforming the unflared form 172. This may be accomplished by forcing a cone 178 into the unflared form 172. As the cone 178 is pushed against the unflared form 172 it forces the unflared form 172 to flare outward. Thusly, the flared flange 166 is created. The turbine wheel hole plug 160 becomes axially locked into position by the upstream flange 144 and the flared flange 166. As shown, the cone 178 may be pushed into the unflared form 172 using a hydraulic jack 180. Other methods also may be used. While the hydraulic jack 180 is used to push the cone 178 into the unflared form 172, the hydraulic jack 180 may be secured into position by placing it against a neighboring turbine wheel 112, as illustrated in
Depending on whether it is desired that all of the flow be blocked or just a partial amount of the flow, the bore hole 156 may or may not be present in the turbine wheel hole plug 160. If it is present, the bore hole 156 may be sized to a predetermined diameter such that, in use, a desired amount of working fluid is allowed to pass through the turbine wheel hole 120.
From the above description of preferred embodiments of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims. Further, it should be apparent that the foregoing relates only to the described embodiments of the present application and that numerous changes and modifications may be made herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4393658 | Bohnenkamp et al. | Jul 1983 | A |
| 4425077 | Martin | Jan 1984 | A |
| 6227799 | Kuhn et al. | May 2001 | B1 |
| 6994516 | Takahashi et al. | Feb 2006 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20090178259 A1 | Jul 2009 | US |
