Patent Application
20180340687
Disclosed embodiments are generally related to components in gas turbine engines.
Gas turbines comprise a casing or cylinder for housing a compressor section, a combustion section, and a turbine section. A supply of air is compressed in the compressor section and directed into the combustion section. The compressed air enters the combustion inlet and is mixed with fuel. The air/fuel mixture is then combusted to produce high temperature and high pressure (working) gas. This working gas then travels through the transition and into the turbine section of the turbine.
The turbine section may comprise rows of vanes which direct the working gas to the airfoil portions of the turbine blades. The working gas travels through the turbine section, causing the turbine blades to rotate, thereby turning a rotor associated therewith.
Higher efficiency of a combustion turbine can be achieved by increasing the temperature of the working gas flowing through the combustion section to as high a temperature as is practical. The aggressive hot gas, however, can degrade various metal turbine components, such as the combustor, transition ducts, vanes, ring segments, and turbine blades as it flows through the turbine.
For this reason, strategies have been developed to protect turbine components from extreme temperatures, such as the development and selection of high temperature materials adapted to withstand these extreme temperatures and cooling strategies to keep the components adequately cooled during operation. Superalloys with additional protective coatings are commonly used for hot gas path components of gas turbines. In view of the substantial and longstanding development in the area of superalloys, further increases in the temperature capability of superalloys has become more difficult.
Ceramic matrix composite (CMC) materials have been developed and increasingly utilized in gas turbine engines. Typically, CMC materials include a ceramic or a ceramic matrix material, either of which hosts a plurality of reinforcing fibers. The fibers may have a predetermined orientation to provide the CMC materials with additional mechanical strength. Generally, (fiber reinforced) ceramic matrix composites are manufactured by the infiltration of a matrix slurry (e.g., alumina, mullite, silicon-containing polymers, molten silicon, or the like) into a fiber preform. While these materials may offer a higher temperature resistance than superalloys, fiber grains of the CMC may coarsen and result in reduced strength over time. In addition, matrix grain coarsening can result in CMC embrittlement leading to a propensity for cracking and crack propagation as firing temperatures increase.
While both of the above strategies are frequently employed, their usage can necessitate additional cooling strategies and can be undesirably expensive for certain applications.
Briefly described, aspects of the present disclosure relate to a component for a gas turbine engine.
An aspect of present disclosure may be a gas turbine engine comprising a combustor basket. A cone may be connected to the combustor basket. The cone comprises a liner; and a shell surrounding the liner, wherein the liner is formed from a refractory oxide ceramic material and the shell is formed from metal.
Another aspect of the present disclosure may be a component for a gas turbine engine. The gas turbine engine may comprise a liner; and a shell surrounding the inner layer, wherein the inner layer is formed from a refractory oxide ceramic material and the shell is formed from metal.
To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments. Embodiments of the present disclosure, however, are not limited to use in the described systems or methods.
A ceramic liner is proposed for use in the gas turbine engines that is able to provide the protection desired for the gas turbine engine. This is a ceramic liner that avoids the costs associated with CMC.
Forming the liner 12 with a plurality of bricks 15 makes it easier to service and/or replace the liner 12. For example, in the event that a portion of the liner 12, such as one of the bricks 15, has undergone some type of damage or has simply outlived its natural life span that particular brick 15 may be serviced. The liner 12 may provide further savings in life cycle cost with only the liner 12 needing to be replaced at combustion/transition intervals, instead of the entire cone 10.
Another advantage of using a plurality of bricks 15 to form the liner 12 relates to costs of using the bricks 15. The costs of the bricks 15 made from refractory oxide ceramic material are relatively inexpensive compared with other ceramic materials, or forming the liner 12 out of CMC.
Additional savings can be achieved by using bricks 15 formed from refractory oxide ceramic material. The refractory oxide ceramic material is able to handle higher temperatures without cooling. When used in the gas turbine engine 100 savings can be achieved by not having to provide additional cooling features that would be needed to cool metal components and part.
The refractory ceramic bricks 15 form a liner 12 that is heavier than typically used liners. Each of the bricks 15 has an inner surface 17 and an outer surface 19. The distance d1 (i.e. the thickness) between a point on the inner surface 17 and a point on the outer surface 19 may be greater than 20 mm, and preferably greater than 25 mm. A range for the distance d1 may be between 20-30 mm. The thicker or greater the distance d1, the more heat protection liner 12 will provide. The thickness or distance d1 also compensates for the lower durability that the bricks 15 made of oxide ceramic may have. The overall thickness of the refractory ceramic bricks 15 also distinguishes the liner 12 from other types of liners.
As indicated above, the use of bricks 15 reduces the need for cooling air since the bricks 15 can withstand higher operating temperatures, such as those greater than 1400° C. This greater than the temperatures that other types of materials can typically withstand. By using materials that permit the gas turbine engine 100 to operate at higher temperatures NOx emissions can be reduced. The liner 12 made of refractory oxide ceramic material can replace current metal designs, which are cooled by impingement and film cooling and need high temperature turbine alloys. The cooling of the ceramic liner 12 may be via radiation to the metallic shell 13.
As discussed above, the bricks 15 are made of a refractory oxide material. Some examples of the oxide ceramic materials that can be used to construct the bricks 15 are zirconium oxide, titanium oxide, aluminum oxide, mullite, combinations thereof, and the like. For example brick 15 may be composition of SiO2 and Al2O3. Preferably the brick 15 is a conglomerate of multiple phases, such as mullite and aluminium oxide. This type of oxide ceramic material is capable of being easily cast in order to form the bricks 15 necessary for the formation of the gas turbine engine component.
The ceramic fiber mat 11 may be made of ceramic materials such as alumina, mullite, aluminosilicate, yttria alumina garnet, silicon carbide, silicon nitride, silicon carbon nitride, molydisicilicide, zirconium oxide, titanium oxide, combinations thereof, and the like. The fiber material used in the ceramic fiber mat 11 may comprise a non-oxide material. The fiber material may comprise ceramic fibers sold under the trademark Nextel, such as Nextel 610, and 720 fibers. In addition, fiber material may be in any suitable form, such as a straight filament, a bundle or a roving of multiple fibers, a braid, or a rope. The fiber material may comprise non-ceramic materials, including but not limited to carbon, glass, polymeric, metal, or any other suitable fiber materials.
Each of the bricks 15 has a first mating side 16 and a second mating side 18. The first mating side 16 and the second mating side 18 are contoured so that they complement each other. First mating side 16 is contoured outwards (i.e. convex) so that it is shaped to engage second mating side 18, which is contoured inwards (i.e. concave). The pressures exerted by adjacent bricks 15 when assembled cause the bricks 15 to mate with each other and remain in place. While the bricks 15 may mate with each other in this manner, other means for engaging each of the bricks 15 may be used, such as pins, grooves and other interlocking assemblies.
Other attachment means can be used to connect the pins 21, such as bolts, etc. Preferably the pins 21 are removable so as to permit easy repair and replacement of the bricks 15. The pins 21 should be able to accommodate thermal growth of the cone 10 while limiting movement of the cone 10 in the axial and circumferential directions. Additionally the pins 21 should be able to accommodate the weight that the cone 10 may have due to the use of the bricks 15, which may be heavier than other materials typically used.
While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.
