JP2009281383A - Systems for and methods of cooling heated components in turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide systems for and methods of cooling heated components in a turbine. <P>SOLUTION: According to one embodiment, the system for cooling the turbine is provided that may include at least one liquid source 116 which may include a coolant liquid. The system may also include at least one liquid nozzle 118 in fluid communication with the liquid source 116 or sources and operable to deliver the coolant liquid in an atomized form adjacent to at least one heated turbine component positioned in a hot gas path 216 of the turbine. Upon delivering the atomized coolant liquid adjacent to the heated turbine component or components, at least a portion of the coolant liquid substantially changes phase to a gas. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates generally to turbines, and more particularly to systems and methods for cooling heated components in a turbine.

  In a turbine, such as a gas turbine, some components such as nozzles, turbines, buckets or shrouds may be placed in the hot gas flow path and may be at a temperature higher than the melting point of one or more components. Exposure to hot gas. In some modern power generation gas turbines, the temperature of the hot gas can reach up to 1600 ° C. Thus, in many cases, the components placed in the hot gas flow path are cooled during turbine operation. In an exemplary conventional system, the air extracted from the compressor of the gas turbine acts to cool the part. However, this air already consumes a lot of work or energy and bypasses the combustion chamber of the gas turbine. This air then flows into components such as turbine buckets or nozzles to cool them so that they can withstand in the hot gas flow path. Thereafter, this air is released into the hot gas flow path and returns. Since this air bypasses the combustion chamber, this air does not burn any fuel and does not add any additional momentum. Therefore, this air cannot do useful work in other turbine stages. As a result, the efficiency of the gas turbine is reduced.

  In other exemplary conventional systems, the heating component can be cooled by steam rather than air taken from the compressor. Steam can be extracted from the steam turbine and piped into a heated turbine component located in the hot gas flow path. Steam generally has a higher heat transfer coefficient and therefore absorbs more heat from turbine components in the hot gas flow path. Thus, steam cooling can provide an improved cooling method over air cooling methods. Steam can be removed from the gas flow path and reintroduced into the steam turbine. Thus, some of the thermal energy drawn from the hot gas flow path by the steam can be recovered by the steam turbine to perform additional useful work. Thus, in the exemplary case, the efficiency of the steam cooled gas turbine can be higher than that of the air cooled gas turbine.

  However, conventional steam cooling systems can be very complex. For example, steam must be removed from the fixed pipe and sent into a rotating bucket. The steam supply and recovery system must be kept in a good seal because steam is present at very high pressures and would otherwise cause leakage in the steam system. Moreover, since the steam travels back to the steam turbine, the steam system must also be sealed to maintain purity.

U.S. Pat. No. 3,446,481 U.S. Pat. No. 3,446,482 US Pat. No. 4,283,822

  Accordingly, there is a need for a system and method for cooling heated components in a turbine.

  Embodiments of the invention can address some or all of the needs described above. Embodiments of the present invention generally relate to systems and methods for cooling heated turbine components in a turbine engine.

  According to one exemplary embodiment of the present invention, a system for cooling a heated component in a hot gas path of a turbine is provided. The exemplary system can include one or more liquid sources that can include a cooling medium liquid. The system is also in fluid communication with one or more liquid sources and is operative to deliver a coolant liquid in an atomized state near one or more heated turbine components disposed within the hot gas flow path of the turbine. One or more possible liquid nozzles can be included. According to the present exemplary embodiment, when the atomized coolant fluid is delivered near one or more heated turbine components, at least a portion of the coolant fluid substantially phase changes to a gas.

  According to another exemplary embodiment of the present invention, a method for cooling a heated component in a hot gas flow path of a turbine is provided. The exemplary method includes one or more liquids that include a coolant liquid and are in fluid communication with one or more liquid nozzles disposed adjacent to one or more heated turbine components disposed within the hot gas flow path of the turbine. Providing a source can be included. The method may further include atomizing coolant fluid from one or more liquid sources and delivering the atomized coolant fluid near one or more heated turbine components. According to the present exemplary embodiment, when the atomized coolant fluid is delivered near one or more heated turbine components, at least a portion of the coolant fluid substantially phase changes to a gas.

  According to yet another exemplary embodiment of the present invention, a method for operating a turbine is provided. The exemplary method may include starting the turbine, increasing the turbine speed to operate at a predetermined load, and atomizing the coolant fluid. The method further includes, after the step of increasing the turbine speed and operating at a predetermined load, delivering the atomized coolant fluid to one or more heated turbine components disposed within the hot gas flow path of the turbine. , And delivering the atomized cooling medium liquid may include the step of causing at least a portion of the cooling medium liquid to substantially change to a gas. The method may further include reducing the turbine speed to operate below a predetermined load, and purging excess liquid from the hot gas flow path after reducing the turbine speed below the predetermined load. it can.

  Other embodiments and aspects of the invention will become apparent from the following description taken in conjunction with the following drawings.

  While embodiments of the present invention have been described in general terms as described above, reference will now be made to the accompanying drawings, which are not drawn to scale.

1 is a functional block diagram of an exemplary system for cooling a heated turbine component, according to one embodiment of the invention. 1 is a turbine bucket diagram illustrating an exemplary heated turbine component, according to one embodiment of the invention. FIG. 2 is a flowchart illustrating an exemplary method for cooling a heated turbine component, according to one embodiment of the invention. 2 is a flowchart illustrating an exemplary method of operating a turbine, according to one embodiment of the invention.

  Exemplary embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, which illustrate some, but not all, embodiments. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are contemplated by the present invention. Shown to ensure that applicable legal requirements are met. Throughout, the same reference numbers refer to similar elements.

  By starting the turbine and increasing its speed, combustion occurs in the combustion chamber of the turbine. During combustion, the temperature of the generated hot gas may sufficiently exceed the melting points of various turbine components installed in the hot gas flow path. Accordingly, a coolant fluid can be atomized and delivered to or near the heated turbine component to cool the heated turbine component in the hot gas path of the turbine. During the phase change from liquid to gas, more energy is absorbed by the coolant liquid, for example water, so the atomized coolant liquid is supplied at or near the location of the heated turbine component Cools parts more efficiently than in a steam-only or air-only turbine. Furthermore, mixing the coolant liquid in the air further acts as a cooling mechanism for the air and gas mixture before it is delivered to the heated turbine component.

  FIG. 1 is a functional block diagram of an exemplary system 100 for cooling a heated turbine component, according to one embodiment of the invention. In the exemplary embodiment, the heated turbine component may be a turbine bucket 102, such as a first stage turbine bucket 102. However, it should be understood that other turbine components, such as turbine wheels, turbine nozzles, turbine shrouds, or combinations thereof may also be cooled by the systems and methods described herein. In a gas turbine, hot gas is generated inside the combustion chamber to produce a hot gas temperature that ranges from about 1000 ° C to about 1600 ° C. After exiting the combustion chamber, the hot gas may first flow through the first stage turbine nozzle 104 of the gas turbine, which is in communication with a heated turbine component, such as the turbine bucket 102. For purposes of explanation, it should be understood that only one first stage turbine nozzle 104 is shown in FIG. 1, and that other exemplary turbines may include multiple nozzles, buckets, and the like. Thus, the turbine nozzle 104 and turbine bucket 102, or other turbine components, are exposed to very high temperature hot gases. As a result, these turbine components can experience temperatures that greatly exceed the melting temperature of the component materials.

  In order to cool the turbine bucket 102, air is delivered from the compressor 106 of the gas turbine. This air can initially flow through the interior space 108 of the turbine nozzle 104. After exiting the turbine nozzle 104, the air flows through the inducer 110, and the inducer 110 further releases air near the root 112 of the turbine bucket 102. The root 112 is the innermost radial portion of the turbine bucket 102. The root 112 typically has an attachment feature (as shown in FIG. 2) that is machined to allow the turbine bucket 102 to be attached to the turbine wheel. In addition, the inducer 110 releases the air so that the air is oriented and flows to enter the turbine bucket 102 through the root 112. FIG. 1 also shows a tube 114 through which the coolant liquid flows through the turbine nozzle 104. In the exemplary embodiment, cooling medium liquid is drawn from liquid source 116. In one exemplary embodiment, the cooling medium liquid can be substantially water, but in other embodiments, the liquid source 116 can deliver a cooling medium liquid other than water. I want to be. After flowing through the tube 114, the coolant liquid flows through the liquid nozzle 118. The liquid nozzle 118 delivers coolant liquid to or near the heated turbine component. For example, as shown in FIG. 1, the liquid nozzle can deliver coolant liquid near the root 112 of the turbine bucket 102. In other exemplary embodiments, the liquid nozzle 118 may deliver coolant liquid to other turbine components, such as a turbine wheel, turbine nozzle, turbine shroud, or combinations thereof.

  In various exemplary embodiments, the liquid nozzle 118 may be installed inside the turbine wheel or outside the turbine shroud. The position of the liquid nozzle 118 determines the position for discharging the coolant liquid to or near the heated turbine component 102. In various exemplary embodiments, the liquid nozzle 118 may be injector, venturi, or the like.

  When the coolant fluid delivered from the fluid nozzle 118 is in direct contact with a heated turbine component, such as the turbine bucket 102, the coolant fluid has a significant temperature increase in the local zone with which the coolant fluid is in contact. May cause decline. This can create a large temperature gradient in the material of the part, and in some cases, a large stress gradient in the material of the heated part, causing cracking where the coolant liquid contacts. There is a fear. To avoid damage to such heated turbine components, in one exemplary embodiment, the cooling medium liquid is discharged into the air in an atomized state and mixed with the air and exposed to high temperatures. At least a portion of the media liquid is phase changed from liquid to gas. Due to the phase change to the gas, it is avoided that the coolant liquid directly contacts the part on the heating component in the liquid state.

In some cases, the coolant liquid that flows out of the liquid source 116 may be at a pressure that is lower than the pressure of the air that flows out of the compressor 106. In such a case, the cooling medium liquid cannot be released into the air in an atomized state and therefore cannot be evenly distributed in the air medium. Thus, the cooling medium liquid can be pressurized before releasing the liquid into the air medium. Accordingly, in one exemplary embodiment, a pressurized pump is utilized to pressurize the coolant liquid, causing the coolant liquid to flow toward the air medium in a substantially atomized state, and the location of the heated turbine component. Can be distributed uniformly in the air medium at or near. For example, the coolant liquid can be pressurized to a pressure of about 2.8 × 10 ⁶ N / m ² (400 psi) or higher.

Mixing the coolant liquid with the air prior to introducing air into the vicinity of a heated turbine component, such as the turbine bucket 102, further causes the latent heat of vaporization of the coolant liquid to form the coolant liquid and the gaseous coolant medium and air in the gaseous state. Therefore, the cooling of the heated turbine component can be further improved. For example, when the cooling medium liquid is water, the latent heat of vaporization, the specific heat of water, and the specific heat of steam are about 2.26 × 10 ² J / kg, 4.184 J / kg- ° C., and ² J, respectively. / Kg- ° C. Thus, a steam-cooled turbine can absorb 2 J of heat with an increase of about 1 ° C. in each kilogram of steam, and a water-cooled turbine can absorb 4.184 J with an increase of about 1 ° C. in each kilogram of water. It can absorb heat. However, in a system such as system 100 where water is converted to steam, 2.26 × 10 ² J of heat can be absorbed by each kilogram of water when converted to steam. Furthermore, this occurs at a constant temperature that is approximately the boiling point of water. Water absorbs 2.26 × 10 ² J / kg- ° C. of heat until almost all of it is converted to steam. This provides a large heat extraction capability for the cooling medium liquid. In addition, mixing the coolant liquid into the air and the resulting conversion to gas is a mechanism for cooling the air before the air and gas mixture is delivered near a heated turbine component, such as the turbine bucket 102. Acts as In this exemplary embodiment of cooling one or more turbine buckets 102, the gas and air mixture may flow through root 112 into interior space 120 of turbine bucket 102 as the coolant liquid phase changes to a gaseous medium. it can.

  In one exemplary embodiment, a pipe system 122 is optionally provided that couples the liquid source 116 to the liquid nozzle 118 and ensures proper delivery of cooling medium liquid from the liquid source 116 and liquid nozzle 118. Can do. Furthermore, the pipe system 122 may be located in an environment where the temperature of the coolant system liquid is significantly higher as the phase of the coolant liquid changes to a gaseous state. This causes the coolant liquid to lose some of the heat extraction capability that it has well for the heated turbine component 102. In order to avoid a phase change of the cooling medium liquid to gas, the pipe system 122 can be insulated from its surroundings. In addition, the pipe system 122 can corrode due to the corrosive action of the coolant fluid. Thus, in one exemplary embodiment, the pipe system 122 can be provided with a corrosion resistant coating.

  In some situations during operation of the system 100, the speed of the gas turbine is reduced and the gas turbine no longer operates at a predetermined load. The gas turbine may need to purge excess coolant liquid that is not converted to the gas phase from the hot gas flow path. Accordingly, in one exemplary embodiment, a purging unit 124 is optionally provided in the gas turbine. However, exemplary gas turbines may generally include a drain system for discharging unburned fuel from within the gas turbine. Thus, in one exemplary embodiment, the fuel drain system can be expanded as a purging unit 124 that purges excess coolant liquid remaining in the flow path.

  FIG. 2 is a diagram of an exemplary turbine bucket 202 illustrating an example of one or more heated turbine components in the hot gas path 216 of the turbine, according to one embodiment of the present invention. The turbine bucket 202 has a first side 218 </ b> A and a second side 218 </ b> B that are opposing walls of the turbine bucket 202 and that define an internal space 208 in the turbine bucket 202. The turbine bucket 202 may include a plurality of orifices 204 and a bucket platform 206. Orifice 204 extends through first side 218A and second side 218B of turbine bucket 202. The coolant liquid and air mixture 210 can be delivered to or near the root 212 of the turbine bucket 202 where the mixture 210 can flow into the turbine bucket 202 through the bucket platform 206. . Mixture 210 further flows through interior space 208. Since the air is already at a high temperature of about 750 ° C. and the cooling medium liquid is evenly distributed in the atomized state throughout the air, the cooling medium liquid absorbs heat from the air and is substantially in the gaseous phase. To change. As the cooling medium liquid of the mixture 210 is converted to a gas, a gaseous mixture 214 is formed. This gaseous mixture 214 can then flow at least partially from the orifice 204 into the hot gas flow path 216.

  It is understood that the turbine bucket 202 is shown for illustrative purposes only, and that other heated turbine components in the hot gas flow path 216 can be cooled in a manner similar to that described herein. I want to be. In various different exemplary embodiments, the heated turbine component can be, but is not limited to, a turbine nozzle, turbine bucket, turbine wheel, or combinations thereof.

  FIG. 3 illustrates an exemplary method by which one embodiment of the present invention can be operated. The presented flowchart 300 illustrates an exemplary method for cooling a heated turbine component in a hot gas path of a turbine, according to one embodiment of the present invention.

  The exemplary method begins at block 302. At block 302, one or more liquid sources are provided that supply cooling medium liquid to, near, or near one or more heated turbine components. In various different exemplary embodiments, the heated turbine component can be, but is not limited to, a turbine nozzle, turbine bucket, turbine wheel, turbine shroud, or combinations thereof. In one exemplary embodiment, the cooling medium liquid can be water, but other cooling media can also be provided. The liquid source is in fluid communication with one or more liquid nozzles located adjacent to or near one or more heated turbine components. Accordingly, the one or more liquid nozzles are operable to supply cooling medium liquid from a liquid source to or near one or more heated turbine components. The one or more liquid nozzles or nozzles can be injector, venturi, or the like.

  In one example, a pipe system from a liquid source to a liquid nozzle can provide fluid communication therebetween. In an exemplary embodiment, the pipe system can be subjected to significantly higher temperatures, such as during turbine operation, which can cause the coolant liquid to undergo a phase change at least in part within the pipe system. is there. Thus, in one exemplary embodiment, the method may further include the step of thermally isolating the pipe system to avoid heat transfer from its surroundings to the coolant fluid inside the pipe system.

  Block 304 continues to block 302 where the cooling medium liquid from the liquid source is substantially atomized. The liquid nozzle may be operable to substantially atomize the cooling medium liquid. Furthermore, in other exemplary embodiments, the turbine may include a pressurizing pump that pressurizes the coolant liquid received from the liquid source and further serves to atomize the coolant liquid.

  Block 306 follows block 304, where a liquid nozzle delivers atomized coolant fluid to the air near or near one or more heated turbine components. By substantially uniformly delivering the atomized cooling medium liquid to the air supplied from the compressor, the cooling medium liquid mixed with the air is substantially exposed when exposed to a higher temperature in the hot gas flow path. Phase change to gas.

  In one exemplary embodiment, the method may include providing a purging unit that excludes the coolant fluid from the hot gas flow path when the turbine speed drops below a predetermined load. In one embodiment, purging the cooling medium from the hot gas flow path can occur before the next start of the turbine. In another example, the coolant fluid can be purged when the turbine is shut down.

  FIG. 4 illustrates another exemplary method by which one embodiment of the present invention can be operated. The presented flowchart 400 illustrates an exemplary method of operating a turbine, according to one embodiment of the present invention.

  The exemplary method begins at block 402. In block 402, the turbine is started. Block 404 follows block 402, where the speed of the turbine is increased to operate the turbine at a predetermined load. By starting the gas turbine and increasing the speed of the gas turbine, a combustion process occurs in the combustion chamber of the gas turbine. In an exemplary embodiment, the temperature of the generated hot gas may be well above the melting point of the various turbine components installed in the hot gas flow path.

  Block 406 follows block 404 where the coolant liquid received from the liquid source is atomized and can be used to cool one or more heated turbine components in the hot gas flow path of the turbine. . In one exemplary method, a liquid nozzle in fluid communication with a liquid source substantially atomizes the coolant liquid. In an exemplary embodiment, the cooling medium liquid can be water, but other cooling media can also be provided.

  Block 408 follows block 406, where the atomized coolant fluid is delivered near or near one or more heated turbine components. In this exemplary method, at least a portion of the cooling medium liquid is phased because the cooling medium liquid is delivered in an atomized state to air in a hot gas flow path having a temperature above the boiling point of the cooling medium liquid. Changes are made and converted to the gas phase. In an exemplary embodiment, the one or more heated turbine components can include a turbine bucket, turbine nozzle, turbine wheel, turbine shroud, or the like.

  Block 410 continues to block 408, where the turbine speed is reduced so that the turbine operates below a predetermined load, such as when decelerating or shutting down. It may be possible to prevent a portion of the coolant liquid from undergoing a phase change during load reduction or momentary shutdown of turbine operation. Leaving liquid in the turbine can cause corrosion of the turbine component and can ultimately cause cracking in the turbine component due to high stress factors. Accordingly, block 412 follows block 410, where an excess of such coolant fluid is purged from the hot gas flow path. In one embodiment, the coolant liquid purge from the hot gas flow path can occur before the next start of the turbine. In another example, the coolant fluid can be purged when the turbine is shut down.

  In various turbines, turbine efficiency can be affected by the introduction of air into the hot gas flow path as a result of air performing significant work between compressor stages. Introducing a coolant liquid as described above into the air helps to increase cooling efficiency and thus reduce the amount of air used to cool the heated turbine components.

  As having the benefit of the teachings presented in the foregoing description and the associated drawings, many variations of the illustrative description and other embodiments described herein to which the description pertains will occur. Accordingly, it will be appreciated that the present invention can be embodied in many forms and should not be limited to the exemplary embodiments described above. Therefore, the present invention should not be limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the claims. I want you to understand that Although specific terms are used herein, these terms are used for general and descriptive purposes only and not for purposes of limitation.

102 Turbine bucket 104 Turbine nozzle 106 Compressor 108 Internal space (within the turbine nozzle)
110 Inducer 112 Root 114 Pipe 116 Liquid source 118 Liquid nozzle 120 Internal space (in turbine bucket)
122 Pipe system 124 Purging unit 202 Turbine bucket 204 Orifice 206 Bucket platform 208 Interior space 210 Mixture 212 Root 214 Gaseous mixture 216 Hot gas flow path 218A First side 218B Second side 300 Method 302 Block 304 Block 306 Block 400 Method 402 block 404 block 406 block 408 block 410 block 412 block

Claims (10)

A system (100) for cooling a heated component in a hot gas flow path (216) of a turbine (102), the system comprising:
One or more liquid sources (116) comprising a cooling medium liquid;
Delivering the coolant liquid in an atomized state near one or more heated turbine components disposed in fluid communication with the one or more liquid sources (116) and disposed in the hot gas flow path (216) of the turbine. One or more liquid nozzles (118) operable to deliver at least a portion of the cooling medium liquid substantially when the atomized cooling medium liquid is delivered near the one or more heated turbine components. A system that changes phase to gas.   The system of claim 1, further comprising one or more pumps that pump the coolant liquid from the one or more liquid sources.   The system of any preceding claim, further comprising a pipe system (122) coupling the one or more liquid sources (116) and the one or more liquid nozzles (118).   The system of claim 3, wherein the pipe system (122) comprises thermal insulation.   The system of claim 1, wherein the cooling medium liquid comprises water.   The system of claim 1, wherein the one or more heated turbine components comprise at least one of a turbine bucket (102), a turbine wheel, a turbine nozzle (104), or a turbine shroud. The one or more heating turbine components comprise a first side (218A) and a second side (218B) defining an interior space (120) therein and the first side (218A) or second A turbine bucket (102) with a plurality of orifices (204) extending through at least one of the side surfaces (218B);
When the atomized coolant fluid is delivered near the turbine bucket (102), at least a portion of the gas flows through the interior space (120) and through at least a portion of the plurality of orifices (204). Out of the internal space (120) to the hot gas flow path (216),
The system of claim 1.   The system of any preceding claim, further comprising a purging unit (124) that purges an excess of the coolant fluid from the hot gas flow path (216). A method of cooling a heated component in a hot gas flow path (216) of a turbine, comprising:
One or more liquids comprising a coolant fluid and in fluid communication with one or more liquid nozzles (118) disposed adjacent to one or more heated turbine components disposed in the hot gas flow path (216) of the turbine. Providing a source (116) (302);
Nebulizing (304) the cooling medium liquid from the one or more liquid sources (116);
Delivering (306) the atomized cooling medium liquid to the vicinity of the one or more heated turbine components;
Delivering the atomized cooling medium liquid to the vicinity of the one or more heated turbine components, at least a portion of the cooling medium liquid substantially phase changes to a gas;
Method.   The method of claim 9, further comprising pumping the cooling medium liquid from the one or more liquid sources (116) by one or more pumps.

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