Inlet duct system for heat recovery steam generator

Abstract

MEANS FOR SOLVING THE PROBLEM: To provide an inlet duct system for a heat recovery steam generator.SOLUTION: A system (10) includes an exhaust diffuser system (22) for a heat recovery steam generator (HRSG) (16). The system (10) includes an inlet portion (23), a diffuser portion (24) axially extending from the inlet portion (23), and an outlet portion (26) fluidly coupled to an axial distal end of the diffuser portion (24), where an outlet extent (252) of the outlet portion (26) is greater than an inlet extent (254) of the inlet portion (23). The diffuser portion (24) includes multiple wall portions (272), and the multiple wall portions (272) are incrementally angled relative to an axial extent (258) extending from the inlet portion (23) to the outlet portion (26). The system (10) may further include a gas turbine engine (12) coupled to the inlet portion (23), and the HRSG (16) coupled to the outlet portion (26).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The subject matter disclosed herein relates generally to an inlet duct system for a heat recovery steam generator. [Background technology]

[0002] A heat recovery steam generator (HRSG) may receive an exhaust stream through an inlet duct coupled to the HRSG, which in turn is coupled to a gas turbine unit. Unfortunately, the exhaust stream may separate from the inner surface of the inlet duct, forming one or more vortices between the exhaust stream and the inner surface. When the exhaust stream separates from the inner surface of the inlet duct, a pressure loss occurs within the inlet duct, which increases backpressure on the connected turbine (i.e., expansion turbine) and reduces the efficiency of a combined cycle power plant that includes a gas turbine system. Therefore, there is a need to at least mitigate or prevent the exhaust stream from separating from the inner surface of the inlet duct and heading toward the HRSG. Summary of the Invention

[0003] Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention; rather, these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

[0004] In a particular embodiment, a system includes an exhaust diffuser system for a heat recovery steam generator (HRSG), the system including an inlet section, a diffuser section extending axially from the inlet section, and an outlet section fluidly coupled to an axially distal end of the diffuser section, the outlet section having an outlet extent greater than an inlet extent of the inlet section, the diffuser section including a plurality of sidewalls, the plurality of sidewalls being angled incrementally relative to the axial extent extending from the inlet section to the outlet section.

[0005] In certain embodiments, a system includes a gas turbine system, a heat recovery steam generator (HRSG), and an exhaust diffuser system, the exhaust diffuser system including an inlet section coupled to the gas turbine system, a diffuser section extending axially from the inlet section, and a plenum fluidly coupled to an axially distal end of the diffuser section, the plenum coupled to the HRSG, the plenum having a plenum extent greater than an inlet extent of the inlet section, the diffuser section including a plurality of wall sections, the plurality of wall sections being angled incrementally relative to an axial extent extending from the inlet section to the plenum, and the plenum including a curved wall extending transversely relative to the axial extent.

[0006] In certain embodiments, a method includes receiving an exhaust flow from a gas turbine through an inlet of an exhaust diffuser system, the method further includes expanding the exhaust flow in a diffuser section of the exhaust diffuser system, the diffuser section including a plurality of walls that are increasingly angled from an inlet to an outlet of the exhaust diffuser system, and discharging the exhaust flow through a plenum in the outlet to an HRSG, the plenum including curved walls that diverge transversely relative to the diffuser section. [Brief explanation of the drawings]

[0007] These and other features, aspects, and advantages of the present invention can be better understood from the following detailed description when read in conjunction with the drawings, in which like characters represent like parts. [Figure 1] 1 is a block diagram of an embodiment of a combined cycle power plant system (hereinafter "combined cycle system") having a gas turbine system, a steam turbine system, a HRSG, and an exhaust diffuser system between the gas turbine system and the HRSG. [Figure 2]FIG. 2 is a side view of an embodiment of an exhaust diffuser system coupled to the HRSG of FIG. 1, illustrating aspects of the exhaust diffuser system that can direct the exhaust flow into the HRSG. [Figure 3] FIG. 3 is a side view of one embodiment of the exhaust diffuser system of FIG. 2, illustrating aspects of the transitions and junctions of the exhaust diffuser system. [Figure 4] FIG. 3 is a top view of one embodiment of the exhaust diffuser system of FIG. 2, illustrating aspects of the transitions and junctions of the exhaust diffuser system. [Figure 5] FIG. 3 is a front view of one embodiment of the exhaust diffuser system of FIG. 2, illustrating aspects of the exhaust diffuser system's transition section having multiple, increasingly angled flat walls. [Figure 6] FIG. 3 is a front view of one embodiment of the exhaust diffuser system of FIG. 2, illustrating the aspect of a transition section having multiple curved walls with increasing angles in the exhaust diffuser system. [Figure 7] 3 is a flow chart of one embodiment of a process for operation of the inlet section of the exhaust diffuser system of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] Described below are one or more specific embodiments of the present invention. These embodiments are an attempt at brevity, and not all features of an actual implementation may be described herein. It should be understood that the development of any actual implementation, like any engineering or design project, requires the execution of numerous implementation-specific decisions to achieve the developer's particular goals (e.g., compliance with system-related and business-related constraints, which may vary from implementation to implementation). Moreover, it should be understood that such a development effort might be complex and time-consuming, but would be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill in the art having the benefit of this disclosure.

[0009] When introducing elements of various embodiments of the present subject matter, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the element. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0010] As described in more detail below, disclosed embodiments include an exhaust diffuser system (e.g., an inlet duct) for an HRSG configured to mitigate flow separation of an exhaust gas flow from an inner surface of a transition section of the exhaust diffuser system. In certain embodiments, the exhaust diffuser system includes an inlet section coupled to a transition section, the transition section extending axially from the inlet section. The transition section includes a plurality of sidewalls, one or more of the sidewalls having a plurality of wall sections. The wall sections are angled increasingly outward, such that the transition section gradually diverges outward along the axial extent of the transition section. The gradual divergence of the transition section mitigates separation of the exhaust gas flow through the transition section from the inner surface of the transition section, thereby mitigating vortex formation between the inner surface and the exhaust gas flow.

[0011] In certain embodiments, the transition section is coupled to a coupling section. The coupling section includes a curved wall that extends transversely to the axial extent of the transition section. The transition section is coupled to a convex portion of the curved wall of the coupling section. Further, the transition section is coupled to a lower portion of the curved wall of the coupling section. The coupling section includes a junction having first and second lateral extents. The junction is fluidly coupled to a side of the HRSG, thereby fluidly coupling the inlet section and the transition section to the HRSG.

[0012] FIG. 1 is a block diagram of one embodiment of a combined cycle system 10 including a gas turbine system 12, a steam turbine system 14, a heat recovery steam generator (HRSG) 16, a gas processing system 18 having one or more gas recovery systems 20, and an exhaust diffuser system 22 (e.g., inlet duct, inlet duct system, etc.). The gas recovery system 20 is configured to recover undesirable gases (e.g., CO) from gases (e.g., exhaust gases and / or air). The exhaust diffuser system 22 includes an inlet section 23 (e.g., inlet section), a transition section 24 (e.g., transition section, diffuser section) coupled to the inlet section 23, and a coupling section 26 (e.g., outlet section, plenum), where the inlet section 23 is coupled to the gas turbine system 12 and the coupling section 26 is coupled to the HRSG 16. The coupling section 26 is configured to transfer exhaust gases 152 from the transition section 24 to the HRSG 16.

[0013] Before describing the details of the gas processing system 18 and the exhaust diffuser system 22, various aspects of the combined cycle system 10 will be described in further detail. To indicate directions in the drawings, reference may be made to an axial direction or axis 30, a radial direction or vertical direction or axis 32 extending radially away from the axial direction or axis 30, and a lateral direction or axis 34 extending radially away from the axial direction or axis 30 and the radial direction or vertical direction or axis 32. The directions or axes 30, 32, and 34 may be referenced to, for example, an axis of rotation 36 of the gas turbine system 12. Additionally, the directions or axes 30, 32, and 34 may be referenced to a central axis of the exhaust diffuser system 22.

[0014] The gas turbine system 12 may include an intake section 40, a compressor or compressor section 42, a combustor section 44, a gas (expansion) turbine or turbine section 46, and an exhaust section 48. The compressor section 42 may include at least one shaft 50 disposed along the rotational axis 36, a casing 52 (e.g., an annular casing) disposed circumferentially about the at least one shaft 50, a plurality of rotating compressor blades 54 extending radially outward from the at least one shaft 50, and a plurality of stationary compressor vanes 56 extending radially inward from the casing 52 toward the at least one shaft 50. In the illustrated embodiment, the compressor section 42 includes multiple compressor stages 58, each having a plurality of compressor vanes 56 spaced circumferentially about the at least one shaft 50 at an axial location and a plurality of compressor blades 54 spaced circumferentially about the at least one shaft 50 at a different axial location immediately adjacent the axial location of the compressor vanes 56 (i.e., the compressor vanes 56 and compressor blades 58 are axially spaced apart). The compressor section 42 is thus configured to receive an intake gas flow 60 from the intake section 40 and incrementally compress the intake gas 60 through the multiple compressor stages 58. As described in more detail below, the intake gas 60 may include intake air, an exhaust gas recirculation (EGR) flow, recirculated exhaust gas, or a combination thereof.

[0015] The combustor section 44 may include one or more combustors 62 (e.g., a single annular combustor arranged circumferentially about the axis of rotation 36 or multiple combustors 62 spaced circumferentially about the axis of rotation 36). In the illustrated embodiment, each combustor 62 includes a head-end portion 64 coupled to a combustion section 66. In the exemplary configuration, the combustion section 66 includes a combustion chamber 68, a combustor liner 70 arranged circumferentially about the combustion chamber 68, a flow sleeve 72 arranged circumferentially about the combustor liner 70, and a passage 74 extending between the combustor liner 70 and the flow sleeve 72. The passage 74 is configured to channel a compressed gas flow in an upstream direction 76 toward a head-end chamber 78 located in the head-end portion 64. The head-end chamber 78 and the combustion chamber 68 of the combustor 62 are separated or divided from each other by an intermediate plate 80. In head end chamber 78, a plurality of fuel nozzles 82 are coupled to intermediate plate 80 and to an end plate 84 of head end portion 64. During operation, each combustor 62 receives compressed gas 86 (e.g., air, EGR, etc.) from compressor section 42 and channels the compressed gas 86 along passageway 74, as indicated by arrows 76, toward head end chamber 78, where the compressed gas is channeled through fuel nozzles 82 and into combustion chamber 68.

[0016] In certain embodiments, each combustor 62 may receive one or more fuel streams from a fuel system 88 coupled to the fuel nozzles 82, the fuel system 88 including a fuel supply system 90 coupled to one or more fuel circuits 92. For example, the fuel circuits 92 may include fuel circuits 94, 96, and 98 coupled to different sets of fuel nozzles 82. The fuel circuits 92 (e.g., 94, 96, and 98) may include fuel conduits, fuel manifolds, fuel valves, pressure regulators, and other flow controls. The fuel system 88 is configured to supply one or more fuels (e.g., liquid fuels and / or gaseous fuels) to each fuel nozzle 82 for injection into the combustion chamber 68. The fuels may include natural gas, syngas produced from a gasifier, methane, hydrogen, biofuel, fuel oil, or any combination thereof. The fuel supply system 90 may include multiple components for controlling the flow of various fluids to the combustors 62. For example, the fuel supply system 90 may include one or more components 100. In certain embodiments, components 100 may include one or more fuel tanks, fuel pumps, valves, pressure regulators, flow regulators, filters, water removal units, particulate removal units, manifolds, flow controllers, or any combination thereof.

[0017] The fuel nozzles 82 are configured to inject one or more fuels from a fuel system 88 and to inject compressed gas 86 from the compressor section 42. In certain embodiments, the fuel nozzles 82 are configured to inject compressed air 104 from a compressor system 106 having an air compressor 108 coupled to a drive 110 (e.g., an electric motor, a combustion engine, a shaft coupled to the gas turbine system 12, or other suitable drive). The compressor system 106 may be configured to receive air from the ambient and / or from the intake section 40. Furthermore, the compressor system 106 may be configured to enable multiple operating modes (e.g., EGR mode or non-EGR mode).

[0018] For example, in certain embodiments of the gas turbine system 12 having exhaust gas recirculation (EGR), the compressor section 42 supplies compressed gas 86 (e.g., compressed exhaust gas) to each combustor 62, and the compressor system 106 supplies compressed air 104 to each combustor 62. To further illustrate, in certain embodiments of the gas turbine system 12 without exhaust gas recirculation (EGR), the compressor section 42 supplies compressed gas 86 (e.g., compressed air) to each combustor 62 without requiring an additional air supply. Thus, the compressor system 106 may optionally supply compressed air 104 to each combustor 62. In operation, fuel is combusted with air in the combustion chamber 68 of each combustor 62, thereby generating hot combustion gases 112, which may be supplied from the combustion chamber 68 to the turbine section 46.

[0019] The turbine section 46 includes at least one shaft 114 disposed along the rotational axis 36, a casing 116 (e.g., an annular casing) disposed circumferentially about the at least one shaft 114, a plurality of rotating turbine blades 118 extending radially outward from the at least one shaft 114, and a plurality of stationary turbine vanes 120 extending radially inward from the casing 116 toward the at least one shaft 114. The turbine section 46 may include a plurality of turbine stages 122, each having a plurality of turbine vanes 120 spaced circumferentially about the at least one shaft 114 at an axial location and a plurality of turbine blades 118 spaced circumferentially about the at least one shaft 114 at a different axial location immediately adjacent the axial location of the turbine blades 118 (i.e., the turbine vanes 120 and the turbine blades 118 are axially spaced apart). Additionally, the at least one shaft 114 may be coupled to the at least one shaft 50 of the compressor section 42 via at least one intermediate shaft 124 .

[0020] Further, the at least one shaft 114 may be coupled to a load 126 via a shaft 128. In certain embodiments, the load 126 may include a generator, a machine, a vehicle propulsion system, or any other suitable load. In the illustrated embodiment, the load 126 is a generator, which may make the combined cycle system 10 a combined cycle power plant. In operation, the combustion gases 112 flow from the combustor 62 into the turbine section 46, where the combustion gases 112 gradually expand and drive turbine blades 118 coupled to the at least one shaft 114 in each turbine stage 122 to rotate. The combustion gases 112 therefore drive the turbine section 46, which in turn drives the compressor section 42 and the load 126 via the interconnected shafts 50, 124, 114, 128.

[0021] In certain embodiments, the gas turbine system 12 may be configured such that the shafts 50, 114, 124, and 128 and the associated compressor blades 54 and turbine blades 118 have a common rotational direction. The shafts 50, 114, 124, and 128 may be removably coupled to one another by shaft connections (e.g., flange joints). In some embodiments, some shafts may be combined to reduce the number of shafts. For example, all of the illustrated shafts 50, 114, and 124 may represent a common shaft that rotates in a common rotational direction (e.g., clockwise or counterclockwise).

[0022] The gas turbine system 12 may be configured with or without the compressor system 106 and the exhaust gas recirculation (EGR) system 150. The EGR system 150 is configured to recirculate exhaust gases 152 output by the turbine section 46 to the compressor section 42 (e.g., through the intake section 40) to compress the exhaust gases and supply them to the combustor section 44. However, the gas turbine system 12 may not include the EGR system 150 and may instead only take an airflow into the intake section 40 and compress it through the compressor section 42.

[0023] In certain embodiments of the gas turbine system 12 having the EGR system 150, the recirculated exhaust gas 152 flows through the intake section 40 and each compressor stage 58 of the compressor section 42, whereby the recirculated exhaust gas is compressed as compressed gas 86 and delivered to the combustor section 44. Additionally, the combustor section 44 may receive compressed air 104 from an air compressor 108 of the compressor system 106 through fuel nozzles 82. The combustor section 44 also receives fuel from a fuel system 88, such as through the fuel nozzles 82. The fuel from the fuel system 88 is then combusted with air from the compressor system 106 to generate combustion gases 112, which flow through the turbine section 46 and drive the turbine blades 118 of each turbine stage 122 to rotate. The recirculated exhaust gases are then combusted with the air from the fuel system 88, such as through the fuel nozzles 82, to generate combustion gases 112 associated with the combustion in the combustor section 44, thereby reducing the temperature rise and certain emissions associated with combustion in the combustor section 44, such as nitrogen oxides (NO X )) is useful in suppressing its formation.

[0024] In certain embodiments of the gas turbine system 12 that do not include the EGR system 150, the compressor section 42 receives the airflow from the intake section 40, progressively compresses the airflow through the compressor stages 58, and delivers the compressed airflow to the combustor section 44 as compressed gas 86. The compressed airflow facilitates combustion of fuel from the fuel system 88, thereby generating hot combustion gases 112 that may be supplied to the turbine section 46. In such embodiments, the compressor system 106 may be excluded or included to provide additional compressed air 104 to the combustor section 44. Regardless of the configuration, the combustion gases 112 drive turbine blades 118 of the turbine stages 122 to rotate, which in turn rotates at least one shaft 114 coupled to the at least one shaft 50 of the compressor section 42 and a shaft 128 that drives the load 126.

[0025] The exhaust gases 152 output by the turbine section 46 may then pass through the exhaust diffuser system 22 and into the HRSG 16, which transfers heat from the exhaust gases to water to generate steam for the steam turbine system 14. Various aspects of the exhaust diffuser system 22 are described in detail below. In the illustrated embodiment, the HRSG 16 includes a high-pressure section 160, an intermediate-pressure section 162, and a low-pressure section 164 arranged in series, thereby generating high-pressure steam 166, intermediate-pressure steam 168, and low-pressure steam 170. The HRSG 16 may include multiple components (e.g., economizers, evaporators, superheaters, or any combination thereof) in each section 160, 162, 164. The components of the HRSG 16 may form tube bundles (e.g., heat exchanger tube bundles) for each section 160, 162, 164. The multiple components of the HRSG 16 may be coupled by various conduits and headers. In certain embodiments, the components of the HRSG 16 include a final high pressure superheater, a secondary reheater, a primary reheater, a primary high pressure superheater, an interstage attemperator, a high pressure evaporator, a high pressure economizer, an intermediate pressure evaporator, an intermediate pressure economizer, a low pressure evaporator, and a low pressure economizer.

[0026] The heat recovery steam generator 16 may direct high-pressure steam 166 to a high-pressure steam turbine 172 of the steam turbine system 14, intermediate-pressure steam 168 to an intermediate-pressure steam turbine 174 of the steam turbine system 14, and low-pressure steam 170 to a low-pressure steam turbine 176 of the steam turbine system 14. The steam drives blades in each steam turbine 172, 174, 176 to rotate, thereby driving a shaft 178 coupled to a load 180 (e.g., a generator). The low-pressure steam turbine 176 may also return condensate 182 to the low-pressure section 164 of the HRSG 16. The HRSG 16 then outputs the exhaust gas 152 as partially cooled exhaust gas 184, which passes through the gas treatment system 18.

[0027] As described above, the gas processing system 18 includes one or more gas recovery systems 20. For example, the gas recovery systems 20 may include any one or combination of gas recovery systems 190, 192, and 194 (each system having multiple components (e.g., components 196, 198, 200, and 202)). The gas recovery systems 20 (e.g., 190, 192, and 194) are configured to obtain recovered gas 204 from the intake gas 60 and / or the exhaust gas 152, 184. In the illustrated embodiment, the gas recovery systems 20 (e.g., 190, 192, and 194) may recover carbon dioxide (CO) and output it as recovered gas 204, which may be further provided to a compression system 206. For example, the compression system 206 may include one or more compressors configured to compress the recovered gas 204 (e.g., CO2) and supply the recovered gas to storage and / or a pipeline 208.

[0028] The gas recovery system 190 is disposed at, within, or upstream of the intake section 40 to recover undesirable gases from the intake air. Accordingly, the gas recovery system 190 may be described as a direct air recovery (DAC) system. The gas recovery systems 192 and 194 are disposed downstream of the gas turbine system 12 and / or the HRSG 16 to recover undesirable gases from the exhaust gases 152, 184. The gas recovery systems 20 (e.g., 190, 192, and 194) may include an adsorbent-based gas recovery system, a solvent-based gas recovery system, a cryogenic gas recovery system, or any combination thereof, and may be configured to remove and recover undesirable gases.

[0029] In certain embodiments, the gas recovery system 20 (e.g., 190, 192, and 194) may collect undesirable gases, such as carbon oxides (CO X ) (e.g., carbon dioxide (CO2) and carbon monoxide (CO)), nitrogen oxides (NO X ) (e.g., nitrogen dioxide (NO2), sulfur oxides (SO X ), or a combination thereof. In the following description, gas capture systems 20 (e.g., 190, 192, and 194) may be described as sorbent-based carbon capture systems using, by way of example, a sorbent material, and / or as solvent-based carbon capture systems using, by way of example, a liquid sorbent (e.g., a solvent). However, embodiments disclosed herein may use any type or configuration of gas capture system 20 (e.g., 190, 192, and 194), as described above.

[0030] Each gas recovery system 20 (e.g., 190, 192, and 194) can include components 196, 198, 200, and 202 suitable to support the type and configuration of the gas recovery system 20 (e.g., components supporting an adsorbent-based gas recovery system, a solvent-based gas recovery system, a cryogenic gas recovery system, or any combination thereof). For example, components 196, 198, 200, and 202 can include an absorber having an adsorbent material, a solvent-based absorber and stripper, a heat exchanger, a cryogenic system, or any combination thereof. Additionally, one or more components 210, 212, and 214 can be located upstream of the gas recovery systems 192 and 194, such as, for example, a dryer or water removal system (e.g., a water-gas separator), a particulate removal system (e.g., a filter and / or solid-gas separator), one or more booster fans, one or more coolers (e.g., a direct contact cooler (DCC)), or any combination thereof.

[0031] In certain embodiments, the exhaust gases 184 may partially or completely bypass the gas processing system 18 and flow to the EGR system 150, and / or the exhaust gases 184 may partially or completely pass through the gas processing system 18 before flowing to the EGR system 150. The EGR system 150 may include one or more conduits, valves, flow control devices, coolers, blowers, or any combination thereof configured to provide at least a portion of the exhaust gases 152, 184 (e.g., the EGR flow) to the intake section 40, where at least a portion of the exhaust gases may be recirculated to the compressor section 42. The coolers may be configured to cool the exhaust gases 152, 184 to a lower temperature (e.g., about ambient temperature) before the exhaust gases 152, 184 are recirculated to the compressor section 42. The blowers may be configured to increase the pressure and flow rate of the exhaust gases 152, 184 to address pressure losses in the EGR system 150.

[0032] In the illustrated embodiment, the combined cycle system 10 also includes a controller 220 that is coupled to the gas turbine system 12, the steam turbine system 14, the HRSG 16, the gas processing system 18, the fuel system 88, the EGR system 150, the compression system 106, and various sensors 222 distributed throughout the combined cycle system 10. In the illustrated embodiment, the controller 220 includes one or more processors 224, a memory 226, instructions 228 stored in the memory 226 and executable by the processor 224, and communication circuitry 230 configured to communicate with the sensors 222 and various devices distributed throughout the combined cycle system 10. For example, the controller 220 is configured to control fuel delivery and distribution from the fuel system 88 to the fuel nozzles 82 of the combustor section 44. In certain embodiments, the controller 220 is configured to control the operation of the gas recovery system 20 (e.g., 190, 192, and 194), for example, by controlling the operating mode (e.g., adsorption mode and desorption mode), by controlling the flow of various fluids through the gas recovery system 20, or any combination thereof.

[0033] Sensors 222 (denoted by an "S") are configured to monitor various operating parameters of combined cycle system 10. In certain embodiments, sensors 222 include temperature sensors, pressure sensors, flow sensors, fluid composition sensors (e.g., gas composition sensors), vibration sensors, clearance sensors, speed sensors, humidity sensors, and / or moisture sensors, or any combination thereof. Sensors 222 may monitor parameters (e.g., temperature, pressure, flow, and fluid composition) at one or more locations in compressor section 42, combustor section 44, turbine section 46, gas processing system 18, or any combination thereof. For example, sensors 222 may monitor compressor parameters (e.g., pressure ratio between the inlet and outlet of compressor section 42), combustion gas parameters (e.g., combustion temperature and combustion dynamics), turbine parameters (e.g., temperature and pressure at each turbine stage, turbine inlet, and turbine exhaust), and exhaust gas emissions. In other examples, exhaust gas emissions monitored by sensors 222 may include carbon oxides (CO X ) (such as carbon dioxide (CO2) and carbon monoxide (CO), nitrogen oxides (NO X ) (nitrogen dioxide (NO2), sulfur oxides (SO X ) (such as sulfur dioxide (SO2), unburned hydrocarbons, particulate matter, and other undesirable exhaust gas emissions. As another example, sensor 222 may monitor the temperature of the adsorbent in an adsorbent-based gas capture system, the temperature of the solvent in a solvent-based gas capture system, or a combination thereof. In response to feedback from sensor 222, controller 220 may adjust the operating mode, fluid flow, heating, cooling, or any combination thereof of gas capture system 20.

[0034] As mentioned above, the combined cycle system 10 includes an exhaust diffuser system 22 disposed between the gas turbine system 12 and the HRSG 16. Although the transition section 24 is shown schematically as separate from the gas turbine system 12, the transition section 24 may be attached to the gas turbine system 12 at the turbine section 46. For example, the transition section 24 may be directly or indirectly attached to the aft frame of the gas turbine system 12 coaxial with the axis of rotation of the turbine section 46.

[0035] 2 is a side view of one embodiment of the HRSG 16 of FIG. 1 and illustrates one embodiment of the exhaust diffuser system 22 of the HRSG 16. In the illustrated embodiment, the HRSG 16 includes sections 160, 162, and 164, although it should be appreciated that the HRSG 16 may include any number of sections. For example, the HRSG 16 may include 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 sections. In the illustrated embodiment, the HRSG 16 is shown extending in the axial direction 30. That is, the sections 160, 162, and 164 of the HRSG 16 are oriented axially horizontally.

[0036] As shown, exhaust diffuser system 22 includes an inlet section 23, a transition section 24 (e.g., diffuser section, diffuser duct, transition section) extending axially from inlet section 23 (e.g., inlet section), and a coupling section 26 (e.g., outlet section, plenum) fluidly coupled to an axially distal end 250 of transition section 24. As shown, an outlet extent 252 (e.g., outlet vertical extent, plenum extent) of coupling section 26 is greater than an inlet extent 254 (e.g., inlet vertical extent) of inlet section 23.

[0037] In the illustrated embodiment, the coupling portion 26 includes a curved wall 256 that extends transversely to the axial extent 258 of the exhaust diffuser system 22. For example, the curved wall 256 may have a U-shaped cross-section (e.g., a semicircular cross-section) extending in the radial or vertical direction 32. In certain embodiments, the curved wall 256 may be a semi-cylindrical wall extending in the radial or vertical direction 32 or a frusto-conical wall extending in the radial or vertical direction 32. The curved wall 256 may provide rigidity or structural support to the coupling portion 26 and to the exhaust diffuser system 22 as a whole. The transition portion 24 is coupled to a convex portion 260 of the curved wall 256. In the illustrated embodiment, the transition portion 24 is coupled to a lower portion 261 of the curved wall 256. In certain embodiments, the transition portion 24 may be coupled to an intermediate portion of the curved wall 256 or to an upper portion of the curved wall 256.

[0038] In the illustrated embodiment, the exhaust diffuser system 22 is coupled to a side 262 of the HRSG 16 via a coupling 26. As illustrated, a joint 264 formed at a longitudinally distal end 266 of the coupling 26 is configured to engage (e.g., connect) with the side 262 of the HRSG 16. That is, the periphery of the joint 264 is configured to couple to the periphery of the side 262 of the HRSG 16. In the illustrated embodiment, the concave surface 270 of the curved wall 256 is configured to be fluidly coupled to the HRSG 16 by engagement between the joint 264 and the side 262 of the coupling 26. In other embodiments, the HRSG 16 can extend in the vertical direction 32 such that the sections 160, 162, 164 of the HRSG 16 are stacked vertically (e.g., a vertical configuration). In certain embodiments, the exhaust diffuser system 22 can be coupled to the top or bottom of an HRSG 16 having a vertical configuration.

[0039] As described in further detail herein, transition section 24 includes a plurality of walls 272 (e.g., plates) that have an incrementally increasing angle relative to axial extent 258 extending from inlet section 23 to junction section 26. In certain embodiments, walls 272 may include flat plates, panels, or sheets (e.g., metal sheets) such that each wall 272 has a constant angle along the width of the respective wall 272, and the angle of each wall 272 increases incrementally at a constant angle. In certain embodiments, walls 272 may include curved plates, panels, or sheets (e.g., metal sheets) such that each wall 272 has a curvature in directions 30, 32, and / or 34, and the angle of each wall 272 varies. For example, each wall portion 272 may be slightly curved at the location of the respective wall portion 272 with a radius equal to or greater than the height and / or width of the transition portion 24 (e.g., a radius of 1, 1.1, 1.2, 1.3, 1.5, 2, or 3 times).

[0040] In the illustrated embodiment, the continuous walls 272 are joined at interface 274. In certain embodiments, the continuous walls 272 may be separate plates (e.g., sheets) joined by welding (e.g., weld joints) or multiple mechanical fasteners (e.g., rivets, screws). That is, interface 274 may include weld lines and / or overlapping portions of the continuous walls 272. In other embodiments, the multiple walls 272 may be formed into a single plate by bending the plate at interface 274. That is, in certain embodiments, interface 274 between the continuous walls 272 may include bent portions of material (e.g., folds and angle changes). It should be appreciated that interface 274 provides a self-reinforcing (e.g., self-stiffening) feature to the multiple walls 272. This self-reinforcing feature of interface 274 may be used in conjunction with, or in certain embodiments, in place of, an external support structure that would otherwise be required to support the exhaust diffuser system 22.

[0041] In certain embodiments, transition portion 24 is formed by rolling (e.g., roll bending) a single wall portion 272 to form a continuously curved shape without discontinuous (e.g., stepped) changes in angle. In certain embodiments, transition portion 24 may include a plurality of walls 272, at least one of which is rolled into a gradually curved shape. The process of rolling at least one of the plurality of walls 272 may include feeding at least one wall portion 272, which may be composed of metal, into a three-roller roll bender.

[0042] FIG. 3 is a side view of one embodiment of the exhaust diffuser system 22 of FIG. 2 , illustrating one embodiment of the transition section 24 of the exhaust diffuser system 22 and one embodiment of the junction section 26 of the exhaust diffuser system 22. In the illustrated embodiment, the transition section 24 includes a sidewall 280. In the illustrated embodiment (as can be clearly seen in FIGS. 5 and 6 ), the sidewall 280 includes a first sidewall 281 (e.g., first side), a second sidewall 282 (e.g., top), a third sidewall 284 (e.g., second side), and a fourth sidewall 286 (e.g., bottom). In certain embodiments, the transition section 24 may include fewer or more sides. For example, the transition section 24 may include three, five, six, seven, eight, or more sides.

[0043] In the illustrated embodiment, each of first side wall 281, second side wall 282, and fourth side wall 286 includes a wall portion 272. In certain embodiments, third side wall 284 also includes a wall portion 272. As shown, wall portion 272 includes a plurality of first wall portions 290 (e.g., first wall portions 292, 294, 296, 298, 300, and 302) that form first side wall 281 of transition portion 24. First wall portions 290 include a first outer surface 304 (e.g., first outer surfaces 306, 308, 310, 312, 314, and 316). While the illustrated embodiment shows the first sidewall 281 as having six first wall portions 290, the first sidewall 281 may include fewer than six first wall portions 290 or more than six first wall portions 290. For example, the first sidewall 281 may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, or more first wall portions 290 and corresponding first outer surfaces 304. In certain embodiments, the first sidewall 281 may include four or more first wall portions 290. Furthermore, for any combination of these first wall portions 290, the longitudinal extents of the first wall portions relative to the axial direction 30 may be the same (e.g., equal dimensions). However, in some embodiments, the first wall portions 290 may have different dimensions in the axial direction 30.

[0044] In the illustrated embodiment, the wall portion 272 further includes second wall portions 318 (e.g., second wall portions 320, 322, 324, 326, 328, and 330) that form second side walls 282 of the transition portion 24. The second wall portions 318 include second outer surfaces 332 (e.g., second outer surfaces 334, 336, 338, 340, 342, and 344). In the illustrated embodiment, the second side wall 282 is shown as having six second wall portions 318, although the second side wall 282 may include fewer or more than six second wall portions 318. For example, the second side wall 282 may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, or more second wall portions 318 and corresponding second outer surfaces 332. In certain embodiments, the second side wall 282 may include four or more second wall portions 318. Furthermore, in any combination of these second wall portions 318, the longitudinal extents of the second walls relative to the axial direction 30 may be the same (e.g., equal dimensions). However, in some embodiments, the second wall portions 318 may have different dimensions in the axial direction 30.

[0045] In the illustrated embodiment, the wall portion 272 further includes fourth wall portions 346 (e.g., fourth wall portions 348, 350, 352, 354, 356, and 358) that form a fourth side wall 286 of the transition portion 24. The fourth wall portions 346 include fourth outer surfaces 360 (e.g., fourth outer surfaces 362, 364, 366, 368, 370, and 372). In the illustrated embodiment, the fourth side wall 286 is shown as having six fourth wall portions 346, but the fourth side wall 286 may include fewer or more than six fourth wall portions 346. For example, the fourth side wall 286 may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, or more fourth wall portions 346 and corresponding fourth outer surfaces 360. In certain embodiments, the fourth sidewall 286 may include four or more fourth wall portions 346. Furthermore, for any combination of these fourth wall portions 346, the longitudinal extents of the fourth wall portions relative to the axial direction 30 may be the same (e.g., equal dimensions). However, in some embodiments, the multiple fourth wall portions 346 may have different dimensions in the axial direction 30. The wall portion 272 may further include a third wall portion that forms the third sidewall 284 and a corresponding third outer surface, which will be described in more detail herein.

[0046] In the illustrated embodiment, the second wall portions 318 of the second sidewall 282 are angled incrementally relative to successive second wall portions 318, with successive second wall portions 318 angled by second angles 374 (e.g., second angles 375, 376, 378, 380, and 382), each second angle 374 being an angle across adjacent second outer surfaces 332 of successive second wall portions 318. In certain embodiments, each second angle 374 is between 150 and 179 degrees, between 165 and 178 degrees, or between 168 and 175 degrees. In certain embodiments, these second angles 374 can be the same as one another. In certain embodiments, in the direction of exhaust gas flow through the exhaust diffuser system 22, each successive second wall portion 318 may vary by 2, 3, 4, 5, 6, 7, 8, 9, or 10 degrees or less (e.g., 2 to 10 degrees, or 3 to 7 degrees) relative to the previous second wall portion 318, thereby reducing the risk of exhaust gas flow separation along the second sidewall 282. In certain embodiments, in the direction of exhaust gas flow through the exhaust diffuser system 22, the second wall portions 318 are angled progressively upward as the transition portion 24 extends from the inlet portion 23 to the junction portion 26. The upwardly angled second wall portions 318 of the fourth sidewall 286 may collectively define an increasing, concave slope in the second sidewall 282.

[0047] In the illustrated embodiment, the fourth wall portions 346 of the fourth side wall 286 are angled increasing relative to successive fourth wall portions 346, with successive fourth wall portions 346 angled by fourth angles 384 (e.g., fourth angles 385, 386, 388, 390, and 392), each fourth angle 384 being an angle across adjacent fourth exterior surfaces 360 of successive fourth wall portions 346. In certain embodiments, each fourth angle 384 is between 150 and 179 degrees, between 165 and 178 degrees, or between 168 and 175 degrees. In certain embodiments, these fourth angles 384 can be the same as one another. Additionally or alternatively, any combination of fourth angles 384 can be equivalent to any combination of second angles 374 described herein. In certain embodiments, in the direction of exhaust gas flow through exhaust diffuser system 22, each successive fourth wall portion 346 varies in angle from the previous fourth wall portion 346 by 2, 3, 4, 5, 6, 7, 8, 9, or 10 degrees or less (e.g., 2 to 10 degrees, or 3 to 7 degrees), thereby reducing the risk of exhaust gas flow separation along fourth side wall 286. In certain embodiments, in the direction of exhaust gas flow through exhaust diffuser system 22, fourth wall portions 346 are angled progressively upward (e.g., defining an upwardly angled portion of fourth side wall 286) and then angled progressively downward (e.g., defining a downwardly angled portion of fourth side wall 286) as transition portion 24 extends from inlet portion 23 to junction portion 26. The upwardly angled and downwardly angled portions of the fourth sidewall 286 may collectively define an upwardly convex shape for the fourth sidewall 286. The upwardly angled portion of the fourth sidewall 286 may be configured to encourage the exhaust flow to be directed upward relative to the second sidewall 282, which may avoid or reduce the risk of flow separation along the second sidewall 282.

[0048] In certain embodiments, the first sidewall 281, the third sidewall 284, and / or the fourth sidewall 286 of the transition region 24 may include a single wall portion rather than multiple wall portions. That is, in certain embodiments, the first sidewall 281, the third sidewall 284, and / or the fourth sidewall 286 may not be gradually diverging and / or may not be gradually varied by multiple wall portions. As described herein, the gradually angled wall portions 272 provide a diverging transition region 24. This diverging angle of the angled wall portions 272 reduces the risk of flow separation from the inner surface of the transition region 24. In certain embodiments, the diverging sidewall 280 provided by gradually angling the wall portions 272 is applied to at least the second (upper) sidewall 282.

[0049] In the illustrated embodiment, first wall portion 290 is coupled to second wall portion 318, forming a plurality of first edges 394 (e.g., first edges 396, 398, 400, 402, 404, and 406) that couple first side wall 281 of transition portion 24 to second side wall 282 of transition portion 24. That is, first walls 292, 294, 296, 298, 300, and 302 are coupled to second walls 320, 322, 324, 326, 328, and 330 through first edges 396, 398, 400, 402, 404, and 406, respectively. Additionally, first wall portion 290 is coupled to fourth wall portion 346, forming a plurality of fourth edges 408 (e.g., fourth edges 410, 412, 414, 416, 418, and 420) that couple first side wall 281 of transition portion 24 to fourth side wall 286 of transition portion 24. That is, first wall portions 292, 294, 296, 298, 300, and 302 are coupled to fourth wall portions 348, 350, 352, 354, 356, and 358 through fourth edges 410, 412, 414, 416, 418, and 420, respectively.

[0050] In the illustrated embodiment, the transition section 24 includes an inlet side 422 that couples to the inlet section 23 of the exhaust diffuser system 22. Additionally, the transition section 24 includes an outlet side 424 that couples to the coupling section 26 of the exhaust diffuser system 22. In the illustrated embodiment, a first extent 426 (e.g., vertical extent) of the outlet side 424 is greater than a second extent 428 (e.g., vertical extent) of the inlet side 422. Additionally, a first central axis 430 that is perpendicular to the first extent 426 is offset in direction 32 from a second central axis 432 that is perpendicular to the second extent 428. In the illustrated embodiment, the first central axis 430 is vertically higher than the second central axis 432. That is, the first side wall 281 and the third side wall 284 are not symmetrical with respect to a plane (e.g., a horizontal plane) that passes through the axes 30 and 34. Similarly, second (upper) sidewall 282 and fourth (lower) sidewall 286 are not symmetrical about a plane (e.g., a horizontal plane) passing through axes 30 and 34. In certain embodiments, first central axis 430 may be vertically lower than second central axis 432, and in certain embodiments, first central axis 430 may be vertically at the same height as second central axis 432.

[0051] In the illustrated embodiment, the first extent 426 of the exit side 424 of the transition portion 24 is smaller than the exit extent 252 of the coupling portion 26. In certain embodiments, the first extent 426 can be equal to or less than the exit extent 252. For example, the first extent 426 can be less than 10, 25, 50, 75, or 100 percent of the exit extent 252. As described herein, the first central axis 430 of the first extent 426 is offset from the coupling central axis 434 of the coupling portion 26. In the illustrated embodiment, the first central axis 430 is lower than the coupling central axis 434. That is, the exit side 424 of the transition portion 24 is coupled to the lower portion 436 of the coupling portion 26. In certain embodiments, the first central axis 430 can be aligned with the coupling central axis 434, or in certain embodiments, the first central axis 430 can be higher than the coupling central axis 434.

[0052] In the illustrated embodiment, the coupling portion 26 includes a curved wall 256 that extends transversely relative to an axial extent 258 of the exhaust diffuser system 22. As shown, the transition portion 24 is coupled to a convex portion 260 of the curved wall 256. The exit extent 252 of the coupling portion 26 extends transversely relative to the coupling central axis 434. In the illustrated embodiment, the coupling portion 26 includes a first lateral wall 448 (e.g., a top wall) that is coupled to the curved wall 256, disposed in a direction 452 away from the coupling central axis 434, and extending laterally from the curved wall 256. The coupling portion 26 also includes a second lateral wall 450 (e.g., a bottom wall) that is coupled to the curved wall 256, disposed in a direction 452 away from the coupling central axis 434, and extending laterally from the curved wall 256. As shown, the first lateral wall 448 and the second lateral wall 450 are convexly curved relative to the central coupling axis 434 .

[0053] In the illustrated embodiment, transition region 24 includes an angled portion 453 that includes a first sloped surface 454 disposed adjacent inlet region 23 and along the plurality of first edges 394. In the illustrated embodiment, first sloped surface 454 longitudinally intersects first walls 292 and 294 and second walls 320 and 322. In certain embodiments, first sloped surface 454 may intersect a greater or lesser number of first walls 290 and / or a greater or lesser number of second walls 318. Transition region 24 further includes a fourth sloped surface 456 that is disposed adjacent inlet region 23 and along the plurality of fourth edges 408. In the illustrated embodiment, fourth sloped surface 456 longitudinally intersects first walls 292 and 294 and fourth walls 348 and 350. In certain embodiments, the fourth beveled surface 456 may intersect with a greater or lesser number of first walls 290 and / or a greater or lesser number of fourth walls 346 .

[0054] 4 is a top view of one embodiment of the exhaust diffuser system 22 of FIG. 2 , illustrating an embodiment of the transition section 24 of the exhaust diffuser system 22 and an embodiment of the junction section 26 of the exhaust diffuser system 22. In the illustrated embodiment, the wall portion 272 includes a plurality of second wall portions 318 (e.g., second wall portions 320, 322, 324, 326, 328, and 330) that form the second side portion 282 of the transition section 24. The second wall portions 318 include second outer surfaces 332 (e.g., second outer surfaces 334, 336, 338, 340, 342, and 344). In the illustrated embodiment, the second side wall 282 is shown as having six second wall portions 318, although the second side wall 282 may include fewer than six or more than six second wall portions 318. For example, the second side wall 282 may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, or more second wall portions 318 and corresponding second exterior surfaces 332. In certain embodiments, the second side wall 282 may include four or more second wall portions 318.

[0055] In the illustrated embodiment, the wall portion 272 includes a plurality of first wall portions 290 (e.g., first wall portions 292, 294, 296, 298, 300, and 302) that form a first sidewall 281 of the transition portion 24. The first wall portions 290 include first outer surfaces 304 (e.g., first outer surfaces 306, 308, 310, 312, 314, and 316). In the illustrated embodiment, the first sidewall 281 is shown as having six first wall portions 290, although the first sidewall 281 may include fewer than six or more than six first wall portions 290. For example, the first sidewall 281 may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, or more first wall portions 290 and corresponding first outer surfaces 304. In certain embodiments, the first side wall 281 may include four or more first wall portions 290. Furthermore, in any combination of these first wall portions 290, the longitudinal extent of the first wall portions relative to the axial direction 30 may be the same (e.g., equal in size). However, in some embodiments, these first wall portions 290 may have different sizes in the axial direction 30.

[0056] In certain embodiments, in the direction of exhaust gas flow through exhaust diffuser system 22, each successive first wall portion 290 of first sidewall 281 varies in angle relative to the previous first wall portion 290 by 2 degrees, 3 degrees, 4 degrees, 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, or 10 degrees or less (e.g., 2 degrees to 10 degrees or 3 degrees to 7 degrees), thereby reducing the risk of exhaust gas flow separation along first sidewall 281. In certain embodiments, in the direction of exhaust gas flow through exhaust diffuser system 22, first wall portions 290 are angled progressively outward relative to central axis (e.g., central axis 434) as transition portion 24 extends from inlet portion 23 to junction portion 26. The outwardly angled first wall portions 290 of the first side wall 281 can collectively define an upwardly concave, increasing slope (i.e., in a direction away from the central axis 434) in the first side wall 281.

[0057] In the illustrated embodiment, the wall portion 272 includes a plurality of third wall portions 480 (e.g., third wall portions 482, 484, 486, 488, 490, and 492) that form the third side wall 284 of the transition portion 24. The third wall portions 480 include third outer surfaces 494 (e.g., third outer surfaces 496, 498, 500, 502, 504, and 506). In the illustrated embodiment, the third side wall 284 is shown as having six third wall portions 480, although the third side wall 284 may include fewer or more than six third wall portions 480. For example, the third side wall 284 may include 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, or more third wall portions 480 and corresponding third outer surfaces 494. In certain embodiments, the third side wall 284 may include four or more third wall portions 480. Furthermore, in any combination of these third wall portions 480, the longitudinal extents of the third wall portions relative to the axial direction 30 may be the same (e.g., equal dimensions). However, in some embodiments, the multiple third wall portions 480 may have different dimensions in the axial direction 30.

[0058] In certain embodiments, in the direction of exhaust gas flow through exhaust diffuser system 22, each successive third wall portion 480 of third sidewall 284 varies in angle from the previous third wall portion 480 by 2 degrees, 3 degrees, 4 degrees, 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, or 10 degrees or less (e.g., 2 degrees to 10 degrees or 3 degrees to 7 degrees), thereby reducing the risk of exhaust gas flow separation along third sidewall 284. In certain embodiments, in the direction of exhaust gas flow through exhaust diffuser system 22, third wall portions 480 are angled progressively outward relative to central axis (e.g., central axis 434) as transition portion 24 extends from inlet portion 23 to junction portion 26. The outwardly angled third wall portions 480 of the third side wall 284 can collectively define an upwardly concave, increasing slope (i.e., in a direction away from the central axis 434) in the third side wall 284.

[0059] Each of the first side wall 281, second side wall 282, third side wall 284, and fourth side wall 286 includes the same number of wall portions 272 (i.e., first wall portion 290, second wall portion 318, third wall portion 480, and fourth wall portion 346). As shown in the exemplary embodiment, each of the side walls 281, 282, 284, 286 includes six wall portions 272, although each side wall may include 3, 4, 5, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, or more wall portions 272.

[0060] As described herein, first wall portion 290 is coupled to second wall portion 318, forming a plurality of first edges 394 (e.g., first edges 396, 398, 400, 402, 404, and 406) that couple first side wall 281 of transition portion 24 to second side wall 282 of transition portion 24. That is, first walls 292, 294, 296, 298, 300, and 302 are coupled to second walls 320, 322, 324, 326, 328, and 330 through first edges 396, 398, 400, 402, 404, and 406, respectively. In the illustrated embodiment, second wall 318 is coupled to third wall 480 to form a plurality of second edges 508 (e.g., second edges 510, 512, 514, 516, 518, and 520) that couple second side wall 282 of transition portion 24 to third side wall 284 of transition portion 24. That is, second walls 320, 322, 324, 326, 328, and 330 are coupled to third walls 482, 484, 486, 488, 490, and 492 through second edges 510, 512, 514, 516, 518, and 520, respectively.

[0061] In the illustrated embodiment, the transition section 24 includes an angled portion 453 that includes a first sloped surface 454 adjacent to the inlet section 23 and disposed along the plurality of first edges 394. As described herein, the first sloped surface 454 longitudinally intersects the first walls 292 and 294 and the second walls 320 and 322. In certain embodiments, the first sloped surface 454 intersects a greater or lesser number of the first walls 290 and / or a greater or lesser number of the second walls 318. In the illustrated embodiment, the transition section 24 includes a second sloped surface 522 that is adjacent to the inlet section 23 and disposed along the plurality of second edges 508. In the illustrated embodiment, the second sloped surface 522 longitudinally intersects the second walls 320 and 322 and the third walls 496 and 498. In certain embodiments, the second beveled surface 522 may intersect with a greater or lesser number of the second walls 318 and / or a greater or lesser number of the third walls 480 .

[0062] As described herein, the coupling portion 26 includes a curved wall 256 that extends transversely relative to the axial extent 258 ( FIG. 3 ). As shown, the transition portion 24 is coupled to a convex portion 260 of the curved wall 256. The second lateral extent 524 of the coupling portion 26 extends transversely relative to the coupling central axis 434, similar to the first lateral extent of the coupling portion 26. In certain embodiments, the exit extent 252 (e.g., shown in FIG. 3 ) and the second lateral extent 524 of the coupling portion 26 may be the same as or different from one another. Referring to FIGS. 3 and 4 , the exit extent 252 may be larger than the second lateral extent 524, although an appropriate ratio (e.g., aspect ratio) of the exit extent 252 and the second lateral extent 524 of the coupling portion 26 can be used to engage HRSGs of various shapes and sizes. For example, the exit extent 252 may be smaller than the second lateral extent 524. In the illustrated embodiment, the coupling portion 26 includes a first lateral wall 448 that is coupled to the curved wall 256, disposed in a direction 32 away from the coupling central axis 434, and extends laterally from the curved wall 256.

[0063] In the illustrated embodiment, the curved wall 256 includes curved ends 526 (e.g., curved ends 528, 530) located at lateral ends 532 (e.g., lateral ends 534, 536) of the second lateral extent 524. The curved ends 526 are more sharply curved (e.g., have a smaller radius) than an intermediate portion 538 (e.g., have a larger radius) of the curved wall 256, providing a transition from the intermediate portion 538 to the junction 264 (e.g., a lip, junction, etc.) located at the distal longitudinal end 542 of the coupling portion 26. That is, the curvature associated with the curved wall 256 increases at the curved ends 526 relative to a location 544 along the second lateral extent 524 of the coupling portion 26. In certain embodiments, location 544 is located inward from a distal lateral end 546 (e.g., distal lateral ends 548, 550) of second lateral extent 524 of coupling portion 26 by 1, 2, 3, 4, 5, 8, 10, 15, or 20 percent of the total length of second lateral extent 524. In certain embodiments, the radius of intermediate portion 538 of curved wall 256 can be at least equal to or greater than second lateral extent 524, or can be in the range of about 0.7 to 2 times the radius of second lateral extent 524. In certain embodiments, the radius of intermediate portion 538 can be a constant radius in vertical direction 32 or a radius that varies in vertical direction 32. As discussed above, the curvature of curved wall 256 is configured to add rigidity and structural support to exhaust diffuser system 22 while simultaneously promoting expansion of exhaust gases flowing from transition section 24 through junction 26 to HRSG 16.

[0064] 5 is a front view of one embodiment of the exhaust diffuser system 22 of FIG. 2 , illustrating one embodiment of the transition section 24 of the exhaust diffuser system 22 having a plurality of incrementally angled wall portions 272. In the illustrated embodiment, the transition section 24 includes a first sidewall 281, a second sidewall 282, a third sidewall 284, and a fourth sidewall 286, as described herein. The transition section 24 also includes a plurality of first edges 394, a plurality of second edges 508, and a plurality of fourth edges 408, as described herein. Additionally, the transition section 24 includes a plurality of third edges 570 that join the third wall portion 480 of the third sidewall 284 to the fourth wall portion 346 of the fourth sidewall 286. In the illustrated embodiment, transition portion 24 also includes angled portion 453, as described herein, which includes first beveled surface 454, second beveled surface 522, and fourth beveled surface 456. Additionally, angled portion 453 includes third beveled surface 572 that intersects with a plurality of third edges 570.

[0065] In the illustrated embodiment, the transition portion 24 includes an annular surface 573 that interfaces with the inlet portion 23. An octagonal outer boundary 574 of the annular surface 573 is formed by the flat portion 576 of the angled portion 453 along with the first sidewall 281, the second sidewall 282, the third sidewall 284, and the fourth sidewall 286. In the illustrated embodiment, the inlet portion 23 extends in the longitudinal direction 30. As shown, the inlet cross section 578 of the inlet portion 23 is circular. An opening 580 in the inlet portion 23 is centrally disposed in the inlet portion 23 and passes through an inner boundary 579 (e.g., an inner circular boundary) of the annular surface 573.

[0066] In the illustrated embodiment, each of the plurality of first wall portions 290, second wall portion 318, and third wall portion 480 has a flat outer surface. That is, first outer surface 304, second outer surface 332, and third outer surface 494 are flat (e.g., not curved). In the illustrated embodiment, fourth outer surface 360 ​​of fourth wall portion 346 is slightly curved inward such that fourth outer surface 360 ​​is concave. In the illustrated embodiment, transition portion 24 includes a plurality of transition sections 582. As shown, the plurality of transition sections 582 are generally rectangular, and the generally rectangular shape includes four side walls 280 arranged in a rectangular shape, although these side walls 280 may include some variation (e.g., variation in flatness, angle, etc.). For example, the term "generally rectangular" may allow for a deviation of up to 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 percent (or less than each of these percentages) from a straight line along each of the four side walls 280, which deviation may be calculated by dividing the maximum height (H) from a straight line by the total length (L) of the straight line along each of the side walls 280 (e.g., deviation = H / L). In other examples, the term "generally rectangular" may allow for a deviation of up to 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 degrees (or less than each of these angles) between the sides of each pair of adjacent sides of the four side walls 280. In certain embodiments, the fourth outer surface 360 ​​is a flat outer surface, and each transition section of the plurality of transition sections 582 of the transition portion 24 is rectangular. In certain embodiments, at least one of the plurality of first walls 290, second walls 318, third walls 480, and fourth walls 346 has a flat outer surface.

[0067] 6 is a front view of one embodiment of the exhaust diffuser system 22 of FIG. 2 illustrating one embodiment of the transition section 24 of the exhaust diffuser system 22 having a plurality of incrementally angled walls 272. In the illustrated embodiment, the transition section 24 includes a first sidewall 281, a second sidewall 282, a third sidewall 284, and a fourth sidewall 286, as described herein. The transition section 24 includes a plurality of first edges 394, a plurality of second edges 508, a plurality of third edges 570, and a plurality of fourth edges 408, as described herein.

[0068] In the illustrated embodiment, each of the plurality of first walls 290, second walls 318, and third walls 480 has an outwardly curved outer surface. That is, each of the first outer surface 304, second outer surface 332, and third outer surface 494 is curved (e.g., bent or bowed) outward relative to the axial direction 30. In certain embodiments, the fourth outer surface 360 ​​is also curved outward relative to the axial direction 30. In certain embodiments, at least one of the plurality of first walls 290, second walls 318, third walls 480, and fourth walls 346 has a curved outer surface. "Curved" should be understood to mean any shape that is curved outward (e.g., convex outward). For example, at least one of the plurality of walls 272 may be conical (e.g., tapered), parabolic, or elliptical. In certain embodiments, the radius of curvature (e.g., outward curve) of the first wall portion 290, the second wall portion 318, and the third wall portion 480 can be at least equal to or greater than (e.g., 1x, 1.1x, 1.2x, 1.3x, 1.4x, 1.5x, 2x, 3x, 4x, or 5x) the vertical 32 height and / or lateral 34 width at the axial position of the radius of curvature in the axial direction 30.

[0069] FIG. 7 is a flowchart of one embodiment of an exemplary process 600 for the operation of an inlet duct of an HRSG (i.e., the exhaust diffuser system of FIG. 2 ). In block 602 of process 600, the inlet duct receives an exhaust stream (e.g., flue gas) from a gas turbine through an inlet section of the inlet duct. In block 604 of process 600, the inlet duct expands the exhaust stream in a diffuser section. The outlet section of the inlet duct has an outlet extent greater than the inlet extent of the inlet section. The outlet extent and the inlet extent extend transversely to the axial extent between the inlet and outlet sections. The diffuser section includes a plurality of walls. The plurality of walls are angled incrementally relative to the axial extent. The angled walls are configured to mitigate flow separation of the exhaust stream from the inner surface of the diffuser section.

[0070] At block 606, the inlet duct discharges the exhaust stream (e.g., exhaust gas) to the HRSG through a plenum defined by a coupling 26 fluidly coupled to the diffuser section. In certain embodiments, the process 600 includes the plenum laterally expanding the exhaust stream. The plenum includes a curved wall extending transversely across the axial extent of the inlet duct between the inlet and outlet sections. The curved wall further mitigates flow separation of the exhaust stream from the interior surface of the inlet duct before the exhaust stream enters the HRSG.

[0071] Technical effects of the disclosed embodiments include mitigating flow separation of an exhaust flow in an inlet duct (i.e., an exhaust diffuser system) that directs the exhaust flow to an HRSG. The inlet duct in the disclosed embodiments includes a diffuser section having a plurality of walls with incremental angles. The incremental angling (e.g., gradual angling) of the walls is configured to mitigate flow separation of the exhaust flow (e.g., flue gas) from the inner surface of the inlet duct. The reduced flow separation allows a larger portion of the exhaust flow to remain near the inner surface, thereby reducing pressure loss within the inlet duct. Furthermore, the reduced flow separation reduces the level of turbulence / recirculation, thereby increasing the cross-sectional area available for the exhaust flow from the inlet through the HRSG. The increased cross-sectional area reduces the mean cross-sectional velocity, further mitigating flow separation and reducing pressure loss. The reduced pressure loss allows for higher static pressure recovery, which improves gas turbine power output while maintaining uniform heat exchanger flow. Furthermore, the curved shape of the coupling duct that connects the inlet duct to the HRSG smoothly directs the exhaust flow into the heat exchanger, thereby reducing turbulence of the exhaust flow. Furthermore, the incrementally angled walls further increase the mechanical strength of the inlet duct; that is, the bent sections (e.g., interfaces, welds, etc.) where the increasingly angled walls join can provide an improved stiffening effect. The improved stiffening effect reduces the cost of constructing external structures used to prevent vibration of the inlet duct panel due to overpressure.

[0072] The subject matter detailed above can be defined by one or more embodiments, as set forth below. [Embodiment 1] The system (10) includes an exhaust diffuser system (22) for a heat recovery steam generator (HRSG) (16). The system (10) includes an inlet section (23), a diffuser section (24) extending axially from the inlet section (23), and an outlet section (26) fluidly coupled to an axially distal end of the diffuser section (24), wherein the outlet section (26) has an outlet extent (252) greater than an inlet extent (254) of the inlet section (23). The diffuser section (24) includes a plurality of wall sections (272), the plurality of wall sections (272) being angled incrementally relative to an axial extent (258) extending from the inlet section (23) to the outlet section (26). [Embodiment 2] A system (10) as described in embodiment 1, wherein the diffuser section (24) includes a first side (281) including a first plurality of walls (290) of the plurality of walls (272), a second side (282) including a second plurality of walls (318) of the plurality of walls (272), a third side (284) including a third plurality of walls (480) of the plurality of walls (272), a fourth side (286) including a fourth plurality of walls (346) of the plurality of walls (272), or a combination thereof. [Embodiment 3] A system (10) as described in embodiment 1 or 2, wherein the first plurality of walls (290) includes four or more walls, the second plurality of walls (318) includes four or more walls, the third plurality of walls (480) includes four or more walls, the fourth plurality of walls (346) includes four or more walls, or any combination thereof. [Embodiment 4] A system (10) according to any one of embodiments 1 to 3, wherein at least one of the first plurality of walls (290), the second plurality of walls (318), the third plurality of walls (480), and the fourth plurality of walls (346) has a flat wall. [Embodiment 5] A system (10) according to any one of embodiments 1 to 4, wherein at least one of the first plurality of wall portions (290), the second plurality of wall portions (318), the third plurality of wall portions (480), and the fourth plurality of wall portions (346) has a wall portion that curves outward relative to the axial range (258). [Embodiment 6] A system (10) according to any one of embodiments 1 to 5, wherein the diffuser section (24) has a plurality of approximately rectangular cross sections formed by the first plurality of wall sections (290), the second plurality of wall sections (318), the third plurality of wall sections (480), and the fourth plurality of wall sections (346). [Embodiment 7] A system (10) according to any one of embodiments 1 to 6, wherein the diffuser section (24) includes an annular surface (573) configured to join with the inlet section (23), and an outer boundary portion (574) of the annular surface (573) is octagonal in shape. [Embodiment 8] A system (10) according to any one of embodiments 1 to 7, wherein the angles (374, 384) between adjacent outer surfaces (232, 360) of consecutive wall portions (318, 346) of the plurality of wall portions (272) that define opposing side walls (282, 286) of the diffuser section (24) are between 165 degrees and 178 degrees. [Embodiment 9] The system (10) according to any one of the first to eighth embodiments, wherein the plurality of walls (272) includes at least one wall having a cone shape. [Embodiment 10] A system (10) according to any one of embodiments 1 to 9, wherein the outlet portion (26) has a curved wall (256) extending in a direction transverse to the axial extent (258). [Embodiment 11] The system (10) according to any one of the first to tenth embodiments, wherein the diffuser section (24) is coupled to a convex portion (260) of the curved wall (256) of the plenum (26). [Embodiment 12] A system (10) described in any of embodiments 1 to 11, wherein the curvature associated with the curved wall (256) begins to increase at a position (544) along the lateral extent (524) of the plenum (26), the position (544) being located more than 10 percent of the total length of the lateral extent (524) from the lateral distal end (546) of the plenum (26). [Embodiment 13] A system (10) according to any one of embodiments 1 to 12, wherein the lateral walls (448, 450) of the plenum are connected to the curved wall (256) and extend laterally from the curved wall (256), and the lateral walls (448, 450) are convexly curved relative to the central axis (434) of the plenum. [Embodiment 14] A system (10) according to any one of embodiments 1 to 13, wherein a joint periphery of the joint (264) of the plenum (26) is configured to be aligned with and coupled to a side periphery of a side (262) of the HRSG (16), and a concave surface (270) of the curved wall (256) is configured to fluidly couple with the HRSG (16). [Embodiment 15] The system (10) of any one of embodiments 1 to 14, including an HRSG (16) coupled to the plenum (26) and a gas turbine system (12) coupled to the inlet (23). [Embodiment 16] The system (10) includes a gas turbine system (12), a heat recovery steam generator (HRSG) (16), and an exhaust diffuser system (22). The exhaust diffuser system (22) includes an inlet section (23) coupled to the gas turbine system (12), a diffuser section (24) extending axially from the inlet section (23), and a plenum (26) fluidly coupled to an axially distal end of the diffuser section (24), the plenum (26) being coupled to the HRSG (16), and a plenum extent (252) of the plenum (26) being greater than an inlet extent (254) of the inlet section (23). The diffuser section (24) includes a plurality of wall sections (272, 290, 318, 480, 346) that are angled incrementally relative to an axial extent (258) extending from the inlet section (23) to the plenum (26), and the plenum (26) includes a curved wall (256) that extends transversely relative to the axial extent (258). [Embodiment 17] 19. The system (10) of any one of embodiments 1 to 18, wherein the diffuser section (24) is coupled to a convex portion (260) of the curved wall (256) of the plenum (26). [Embodiment 18] A system (10) according to any one of embodiments 1 to 17, wherein the angle (374, 384) between the continuous outer surfaces (232, 360) of the continuous wall portions (318, 346) of the plurality of wall portions (272) that define the opposing side walls (282, 286) of the diffuser section (24) is between 165 degrees and 178 degrees. [Embodiment 19] The method (600) includes receiving (602) an exhaust flow (i.e., flue gas) from the gas turbine system (12) through an inlet section (23) of an exhaust diffuser system (22). The method (600) further includes expanding (604) the exhaust flow in a diffuser section (24) of the exhaust diffuser system (22), the diffuser section (24) including a plurality of walls (272) that are increasingly angled from the inlet section (23) toward an outlet section (26) of the exhaust diffuser system (220). The method (600) further includes discharging (606) the exhaust flow through a plenum at the outlet section (26) to the HRSG (16), the plenum including a curved wall (256) that extends transversely relative to the diffuser section (24). [Embodiment 20] The method (600) according to any one of embodiments 1 to 17, wherein the angle subtended by the continuous outer surfaces (232, 360) of the continuous wall portions (318, 346) of the plurality of wall portions (272) that define the opposing side walls (282, 286) of the diffuser section (24) is between 165 degrees and 178 degrees.

[0073] This specification uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention (e.g., to make and use devices or systems, and to perform incorporated methods). The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they contain structural elements that do not differ from the claim language, or if they contain equivalent structural elements that do not differ substantially from the claim language. [Explanation of symbols]

[0074] 10 Combined Cycle Systems 12 Gas Turbine System 14 Steam Turbine System 16 Heat recovery steam generator 18 Gas Treatment System 20 Gas Recovery System 22 Exhaust diffuser system 23 Entrance 24 Transition 26 Joint 36 Rotation axis 40 Intake section 42 Compressor Section 44 Combustor Section 46 Turbine Section 48 Exhaust Section 50 shaft 52 Casing 62 Combustor 64 Head end 66 Combustion section 68 Combustion Chamber 70 Combustor liner 72 Flow Sleeve 74 Passage 78 Head End Chamber 80 Intermediate Plate 82 Fuel nozzle 84 End Plate 86 Compressed Gas 88 Fuel System 90 Fuel supply system 92 Fuel circuit 94 Fuel circuit 100 components 104 Compressed Air 108 Air Compressor 110 Drive unit 112 Hot combustion gases 112 Combustion Gas 114 Shaft 116 Casing 118 Rotating Turbine Blades 118 Turbine Blade 120 Stationary Turbine Vane 120 Turbine vane 122 Turbine Stage 124 Intermediate shaft 126 Load 128 Shaft 150 EGR) system 150 EGR system 152 Exhaust gas 152 Exhaust Gas 160 High-Pressure Section 160 Section 162 Medium Pressure Section 164 Low Pressure Section 166 High-Pressure Steam 168 Medium Pressure Steam 170 Low-pressure steam 172 High-pressure steam turbine 172 Steam turbine 174 Medium-pressure steam turbine 176 Low-pressure steam turbine 178 Shaft 180 load 182 Condensate 184 Exhaust Gas 184 Exhaust Gas 190 Gas Recovery System 192 Gas Recovery System 196 Components 204 Gas 208 Pipeline 210 Components 220 Controller 222 Sensor 224 processors 226 memory 228 Command 230 Communication Circuit 250 axial distal end 252 Exit Range 254 Entrance Range 256 Curved Wall 258 axial range 260 Convex 261 Lower 262 Side 264 Joint 266 Longitudinal Distal End 270 Concave 272 Wall 274 Boundary part 280 side wall 290 First Wall 292 First Wall 304 First Outer Surface 306 First Outer Surface 318 Second Wall 320 Second Wall 332 Second Exterior 334 Second Exterior 346 Fourth Wall 348 Fourth Wall 360 Fourth Exterior 362 Fourth Exterior 374 Second Angle 375 Second Angle 384 The Fourth Angle 385 The Fourth Angle 394 First Edge 396 First Edge 408 The Fourth Edge 410 The Fourth Edge 422 Entrance side 424 Exit side 426 First Range 428 Second Range 430 First Central Axis 432 Second Central Axis 436 Lower part 448 First Transverse Wall 450 Second lateral wall 452 directions 453 Diagonal part 454 First Slope 456 Fourth Slope 480 Third Wall 482 Third Wall 494 Third Exterior 508 Second Edge 522 Second Slope 524 Second Horizontal Range 526 curved end 528 curved end 532 Lateral end 534 Lateral end 538 Middle part 542 longitudinal distal end 544 position 546 Lateral Distal End 548 Lateral Distal End 570 Third Edge 572 Third Slope 573 Annular Surface 574 Outer boundary part 576 Flat area 578 Inlet cross section 579 Inner boundary part 580 aperture 582 Transition Section 600 processes Block 602 604 Block

Claims

1. A system (10), comprising: An exhaust diffuser system (22) for a heat recovery steam generator (HRSG) (16), the exhaust diffuser system (22) comprising: Inlet section (23), a diffuser section (24) extending axially from the inlet section (23), the diffuser section (24) having a plurality of side sections (280) arranged around a central axis of the diffuser section (24); and an outlet section (26) fluidly coupled to the axially distal end of said diffuser section (24); Including, an outlet extent (252) of the outlet section (26) is greater than an inlet extent (254) of the inlet section (23), at least one of the plurality of side sections (280) of the diffuser section (24) has a plurality of wall sections (272) that are angled incrementally with respect to an axial extent (258) extending from the inlet section (23) to the outlet section (26); The system (10) wherein each wall of the plurality of walls (272) is angled relative to the immediately preceding wall of the plurality of walls (272) by an angle within a common angular range of angles between 150 degrees and 179 degrees, the angle between successive walls of the plurality of walls (272) varies by an angle of less than 10 degrees, or a combination thereof is achieved.

2. The diffuser section (24) has a plurality of sides (280): a first sidewall (281) having a first plurality of wall portions (290) of said plurality of wall portions (272); a second sidewall (282) having a second plurality of wall portions (318) of said plurality of wall portions (272); a third sidewall (284) having a third plurality of wall portions (480) of said plurality of wall portions (272); a fourth sidewall (286) having a fourth plurality of walls (346) of the plurality of walls (272); or The combination of these sidewalls The system (10) of claim 1, comprising:

3. 3. The system of claim 2, wherein the first plurality of walls includes four or more walls, the second plurality of walls includes four or more walls, the third plurality of walls includes four or more walls, the fourth plurality of walls includes four or more walls, or a combination thereof.

4. 4. The system (10) of claim 2 or 3, wherein at least one of the first plurality of walls (290), the second plurality of walls (318), the third plurality of walls (480), and the fourth plurality of walls (346) comprises a flat wall.

5. 5. The system (10) of claim 2, 3, or 4, wherein at least one of the first plurality of walls (290), the second plurality of walls (318), the third plurality of walls (480), and the fourth plurality of walls (346) has a wall that curves outwardly relative to the axial extent (258).

6. 6. The system of claim 2, 3, 4, or 5, wherein the diffuser section has a plurality of generally rectangular cross sections formed by the first plurality of walls, the second plurality of walls, the third plurality of walls, and the fourth plurality of walls.

7. The system (10) of claim 1, wherein the plurality of walls (272) includes at least one wall having a cone shape.

8. The system (10) of claim 1, wherein the outlet section (26) has a curved wall (256) that extends transversely relative to the axial extent (258).

9. The system (10) of claim 8, wherein the diffuser section (24) is coupled to a convex portion (260) of a curved wall (256) of the outlet section (26).

10. 10. The system of claim 8 or 9, wherein the curvature associated with the curved wall begins to increase at a location along the lateral extent of the outlet, the location being more than 10 percent of the total length of the lateral extent from a distal lateral end of the outlet.

11. 11. The system of claim 8, 9, or 10, wherein lateral walls of the outlet section are coupled to and extend laterally of the curved wall, and the lateral walls are convexly curved relative to a central axis of the outlet section.

12. 11. The system of claim 8, wherein a junction periphery of the junction portion of the outlet section is configured to align with and couple to a side periphery of a side surface of the HRSG, and wherein the concave surface of the curved wall is configured to fluidly couple with the HRSG.

13. A system (10), comprising: a gas turbine system (12); a heat recovery steam generator (HRSG) (16), and An exhaust diffuser system (22) according to any one of claims 1 to 12. and The gas turbine system (12) is coupled to an inlet (23) of the exhaust diffuser system (22), and the HRSG (16) is coupled to an outlet (26) of the exhaust diffuser system (22).

14. 1. A method (600) comprising: receiving (602) an exhaust flow from a gas turbine system (12) through an inlet (23) of an exhaust diffuser system (22); Expanding the exhaust flow in a diffuser section of the exhaust diffuser system, the diffuser section having a plurality of sides arranged about a central axis of the diffuser section, at least one of the sides of the diffuser section including a plurality of walls that are angled incrementally from an inlet section toward an outlet section of the exhaust diffuser system; and Discharging (606) the exhaust stream through a plenum in the outlet section (26) to a heat recovery steam generator (16), the plenum including a curved wall (256) that extends transversely to the diffuser section (24). The method (600) includes:

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