System and method with load control for isothermal expansion in a turbine stage of a gas turbine engine

Abstract

The method includes routing combustion gases through turbine stages along a combustion gas path disposed between a turbine shaft and a turbine casing of a gas turbine, the turbine shaft disposed along an axis of rotation, the turbine casing disposed circumferentially around the turbine shaft, the turbine stage including a plurality of turbine vanes disposed upstream of a plurality of turbine blades, and controlling an axial extent of different combustion axial positions within a turbine stage expansion of the turbine stage in response to changes in load on the gas turbine to reduce temperature variations across the turbine stage expansion via an isothermal expansion system coupled to the turbine stage.

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to gas turbine engines, and more particularly to systems and methods for improving efficiency through isothermal expansion in turbine stages. [Background technology]

[0002] A gas turbine engine includes a compressor, a combustor, and a turbine driven by the combustion gas flow from the combustor. The turbine may include one or more turbine stages, each having a plurality of turbine blades. The combustion gas flow expands through the turbine and drives the rotation of the turbine blades in each of the one or more turbine stages. Unfortunately, unlike the Carnot cycle, the combustion gas flow typically changes temperature during expansion through each of the one or more turbine stages. Therefore, there is a need for isothermal expansion through each of the one or more stages. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2013 / 0167545 Summary of the Invention

[0004] Certain embodiments commensurate in scope with the initially claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the claimed embodiments; rather, these embodiments are intended only to provide a brief summary of possible forms of the present subject matter. Indeed, the embodiments claimed herein may include a variety of forms that may be similar to or different from the embodiments set forth below.

[0005] The method includes routing combustion gases through turbine stages along a combustion gas path disposed between a turbine shaft and a turbine casing of a gas turbine, the turbine shaft disposed along an axis of rotation, the turbine casing disposed circumferentially around the turbine shaft, the turbine stage including a plurality of turbine vanes disposed upstream of a plurality of turbine blades, and controlling an axial extent of different combustion axial positions within a turbine stage expansion of the turbine stage in response to changes in load on the gas turbine to reduce temperature variations across the turbine stage expansion via an isothermal expansion system coupled to the turbine stage.

[0006] The system includes a controller having a processor, a memory, and instructions stored in the memory and executable by the processor, the instructions including instructions for controlling combustion in a combustor to generate a combustion gas flow passing through a turbine stage along a combustion gas path disposed between a turbine shaft and a turbine casing of a gas turbine, the turbine shaft disposed along a rotational axis, the turbine casing disposed circumferentially around the turbine shaft, the turbine stage including a plurality of turbine vanes disposed upstream of the plurality of turbine blades, and the controller configured to control an axial range of different combustion axial positions within a turbine stage expansion of the turbine stage in response to changes in load on the gas turbine to reduce temperature variations across the turbine stage expansion via an isothermal expansion system coupled to the turbine stage.

[0007] The system includes a gas turbine having a turbine shaft disposed along a rotational axis, a turbine casing disposed circumferentially around the turbine shaft, a combustion gas path disposed between the turbine shaft and the turbine casing, and a turbine stage disposed in the combustion gas path, the turbine stage including a plurality of turbine vanes disposed upstream of a plurality of turbine blades. The system includes an isothermal expansion system coupled to the turbine stage, the isothermal expansion system including a plurality of fluid injectors disposed at a plurality of different axial positions between leading edges and trailing edges of the plurality of turbine vanes, at least one fluid injector of the plurality of fluid injectors coupled to each of the plurality of turbine vanes. The system includes a controller having a processor, a memory, and instructions stored in the memory and executable by the processor to control fluid flow to the plurality of fluid injectors in response to changes in load on the gas turbine to vary an axial extent of different combustion axial positions within the turbine stage expansion of the turbine stage and reduce temperature variations across the turbine stage expansion.

[0008] These and other features, aspects, and advantages of the presently disclosed technology will be better understood from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts throughout. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram of an embodiment of a combined cycle system having a gas turbine system, a steam turbine system, and a heat recovery steam generator (HRSG), and an isothermal expansion system for the turbine stages. [Figure 2] 2 is a schematic diagram of an embodiment of a portion of the turbine section of the gas turbine system of FIG. 1 further illustrating details of an isothermal expansion system having a variable injection system with fluid injectors and a variable stabilizer system with a flame stabilizer. [Figure 3]2 is a schematic diagram of an embodiment of a portion of the turbine section of the gas turbine system of FIG. 1, further illustrating details of the isothermal expansion system. [Figure 4] FIG. 4 is a perspective view of an embodiment of a vane of the turbine section of FIGS. 1-3, further showing a fluid injector at a trailing edge portion of the vane at an axial distance from the leading edge of the vane. [Figure 5] FIG. 4 is a perspective view of an embodiment of a vane of the turbine section of FIGS. 1-3, further showing a fluid injector at a mid-portion of the vane, an axial distance from the leading edge of the vane. [Figure 6] FIG. 4 is a perspective view of an embodiment of a vane of the turbine section of FIGS. 1-3, further illustrating a fluid injector at a leading edge portion of the vane at an axial distance from the leading edge of the vane. [Figure 7] FIG. 4 is a perspective view of an embodiment of a vane of the turbine section of FIGS. 1-3, further illustrating a fluid injector at a trailing edge portion of the vane at a variable axial distance from the leading edge of the vane. [Figure 8] FIG. 4 is a perspective view of an embodiment of a vane of the turbine section of FIGS. 1-3, further illustrating a fluid injector at a mid-portion of the vane at a variable axial distance from the leading edge of the vane. [Figure 9] FIG. 4 is a perspective view of an embodiment of a vane of the turbine section of FIGS. 1-3, further illustrating a fluid injector at a leading edge portion of the vane at a variable axial distance from the leading edge of the vane. [Figure 10] FIG. 4 is a perspective view of a vane of the turbine section of FIGS. 1-3, with fluid injectors having different cross-sectional areas. [Figure 11] FIG. 4 is a perspective view of a vane of the turbine section of FIGS. 1-3, with fluid injectors having different cross-sectional areas. [Figure 12] FIG. 4 is a perspective view of a vane of the turbine section of FIGS. 1-3, with fluid injectors having different cross-sectional areas. [Figure 13] FIG. 13 is a schematic diagram of one embodiment of the isothermal expansion system of FIGS. 1-12, further illustrating one embodiment of the fluid injector as a multi-fluid injector. [Figure 14] FIG. 14 is a cross-sectional view of the multi-fluid injector of FIG. 13 taken along line 14-14, further illustrating the geometry of the fluid passages and walls of the multi-fluid injector. [Figure 15] FIG. 13 is a cross-sectional view of an embodiment of one of the fluid injectors of FIGS. 1-12, further illustrating a fluid passage having a converging-diverging passage geometry. [Figure 16] FIG. 13 is a cross-sectional view of an embodiment of one of the fluid injectors of FIGS. 1-12, further illustrating a fluid passage having a convergent passage geometry. [Figure 17] FIG. 15 is a cross-sectional view of the multi-fluid injector of FIGS. 13 and 14, further illustrating the convergent passage geometry of the fluid passages. [Figure 18] FIG. 18 is a cross-sectional view of one embodiment of the fluid injector of FIGS. 1-17, further illustrating that the fluid ejection axis or direction angle is approximately 90 degrees. [Figure 19] FIG. 18 is a cross-sectional view of one embodiment of the fluid injector of FIGS. 1-17, further illustrating the angle of the fluid ejection axis or direction as an acute angle. [Figure 20] 19 is a cross-sectional view of one embodiment of the fluid injector of FIGS. 1-17, further illustrating the angle of the fluid ejection axis or direction as a less acute angle than that of FIG. 19. [Figure 21] FIG. 4 is a perspective view of one embodiment of a blade of the turbine section of FIGS. 1-3, further illustrating a flame stabilizer at a leading edge portion of the blade at an axial distance from the leading edge of the blade. [Figure 22] FIG. 4 is a perspective view of one embodiment of a blade of the turbine section of FIGS. 1-3, further illustrating a flame stabilizer at an intermediate portion of the blade at an axial distance from the leading edge of the blade. [Figure 23] FIG. 4 is a perspective view of an embodiment of a blade of the turbine section of FIGS. 1-3, further illustrating a flame stabilizer at a trailing edge portion of the blade at an axial distance from the leading edge of the blade. [Figure 24]FIG. 4 is a perspective view of an embodiment of a blade of the turbine section of FIGS. 1-3, further illustrating a flame stabilizer at a leading edge portion of the blade at a variable axial distance from the leading edge of the blade. [Figure 25] FIG. 4 is a perspective view of one embodiment of a blade of the turbine section of FIGS. 1-3, further illustrating a flame stabilizer at an intermediate portion of the blade at a variable axial distance from the leading edge of the blade. [Figure 26] FIG. 4 is a perspective view of an embodiment of a blade of the turbine section of FIGS. 1-3, further illustrating a flame stabilizer at a trailing edge portion of the blade at a variable axial distance from the leading edge of the blade. [Figure 27] FIG. 27 is a top view of one embodiment of the flame stabilizer of FIGS. 1-3 and 21-26, further showing details of a protrusion disposed in a recess, the protrusion having a curved or C-shaped geometry. [Figure 28] 28 is a cross-sectional view of an embodiment of the flame stabilizer of FIG. 27, further illustrating details of the protrusions and recesses, including variable height of the protrusions. [Figure 29] FIG. 27 is a top view of one embodiment of the flame stabilizer of FIGS. 1-3 and 21-26, further showing details of a protrusion disposed in a recess, the protrusion having curved or arcuate walls. [Figure 30] FIG. 30 is a cross-sectional view of an embodiment of the flame stabilizer of FIG. 29, further illustrating details of the protrusions and recesses, including variable height of the protrusions. [Figure 31] FIG. 27 is a top view of one embodiment of the flame stabilizer of FIGS. 1-3 and 21-26, further illustrating details of a protrusion disposed in a recess, the protrusion having a rectangular geometry. [Figure 32] FIG. 32 is a cross-sectional view of one embodiment of the flame stabilizer of FIG. 31, further illustrating details of the protrusions and recesses, including variable height of the protrusions. [Figure 33] 33 is a flow chart illustrating one embodiment of a process for operating a gas turbine system with a variable injection system of the isothermal expansion system 18 of FIGS. [Figure 34] 34 is a flow chart illustrating an embodiment of a process for operating a gas turbine system with a variable injection system of the isothermal expansion system 18 of FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0010] One or more specific embodiments of the systems and methods of the present disclosure are described below. While an effort is made to provide a concise description of these embodiments, not all features of an actual implementation may be described herein. It is understood that in developing an actual implementation, such as an engineering or design project, many implementation-specific decisions must be made to achieve the developer's particular objectives, including, for example, adherence to system-related and business-related constraints, and that these constraints may vary from implementation to implementation. Moreover, it is understood that such a development effort may be complex and time-consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those skilled in the art having the benefit of this disclosure.

[0011] When introducing elements of various embodiments of the presently disclosed embodiments, the words "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0012] The disclosed embodiments are configured to provide isothermal expansion (e.g., expansion at a constant temperature) in a turbine stage of a gas turbine system by controlling (e.g., varying and / or distributing) the heat release of combustion across the rotating blades in the turbine stage expansion. While isothermal expansion contemplates expanding the combustion gases at a constant temperature, the disclosed embodiments may also tolerate some temperature fluctuations with substantially isothermal expansion. The heat release of combustion is controlled by at least a variable injection system having fluid injectors on stationary vanes upstream from the rotating blades, a variable stabilizer system having flame stabilizers on the rotating blades, or a combination thereof. The fluid injectors and flame stabilizers are configured to distribute the heat release of combustion along the rotating blades (e.g., via axial positioning of the flame) over an axial range between the leading and trailing edges of the rotating blades in the turbine stage expansion, which axial range can vary between the entire axial distance between the leading and trailing edges and a partial axial distance. The fluid injectors may be fuel injectors or multi-fluid injectors that supply fuel, oxidant, and another fluid as a barrier gas.

[0013] The variable injection system may passively and / or actively control the axial location of the heat release of combustion across the rotating blades in the turbine stage expansion via the fluid injectors on the stationary vanes. For example, the variable injection system may passively control the axial location of the heat release of combustion across the rotating blades in the turbine stage expansion via the fluid injectors on the stationary vanes by employing different mounting locations (e.g., axial and radial locations) of the fluid injectors, different geometries of the fluid ports, different cross-sectional areas of the fluid ports, different angles of fluid injection, or other characteristics that are not controlled during operation.

[0014] As yet another example, a variable injection system may actively control the axial location of the heat release of combustion across the rotating blades in a turbine stage expansion via fluid injectors on stationary vanes by employing control of fluid flow (e.g., fuel flow, oxidant flow, and / or barrier fluid flow) through the fluid injectors. The variable injection system may include multiple fluid circuits (e.g., fuel circuits, oxidant circuits, and / or barrier fluid circuits) independently coupled to multiple different fluid injectors on the same or different stationary vanes. Thus, the variable injection system may vary fluid pressure, flow rate, or other fluid characteristics to vary the downstream axial distance until the fuel mixes and combusts along the rotating blades in a turbine stage expansion. In certain embodiments, the variable injection system may combine active and passive control to vary the downstream axial distance until the fuel mixes and combusts along the rotating blades in a turbine stage expansion.

[0015] The variable injection system may also be actively controlled, for example, using multiple fluid circuits and flow control valves, to adjust the axial positioning of the combustion heat release within the turbine stage expansion in response to operating conditions of the gas turbine system (e.g., full load vs. part load conditions). The variable injection system may selectively move the axial location of the combustion heat release further upstream from the trailing edge of the rotating blade in response to reduced load and / or may move the axial location of the combustion heat release further downstream toward the trailing edge of the rotating blade via control of fluid flow through the fluid injectors. For example, the variable injection system may selectively vary fluid flow through different fluid circuits (e.g., fuel circuits) coupled to different fluid injectors at different axial locations along the stationary vane.

[0016] As load decreases, the variable injection system may selectively decrease or stop fluid flow (e.g., fuel flow) through the fluid circuit to the fluid injector located downstream along the stationary vane while maintaining fluid flow (e.g., fuel flow) through the fluid circuit to the fluid injector located upstream along the stationary vane. As load increases, the variable injection system may selectively increase or start fluid flow (e.g., fuel flow) through the fluid circuit to the fluid injector located downstream along the stationary vane while maintaining fluid flow (e.g., fuel flow) through the fluid circuit to the fluid injector located upstream along the stationary vane. Thus, the ability to vary the axial location of the heat release of combustion along the rotating blades within the turbine stage expansion enables isothermal expansion in the turbine stage at various operating conditions of the gas turbine system, including both full load and part load conditions.

[0017] A variable stabilizer system having flame stabilizers on rotating blades can passively control the axial location of the heat release of combustion across the rotating blades within a turbine stage expansion through flame stabilizer variations such as different mounting locations (e.g., axial and radial locations) between flame stabilizers and / or between rotating blades within a turbine stage, different geometries, different cross-sectional areas, and / or different dimensions. For example, flame stabilizers can be attached to multiple rotating blades at axial locations that vary in multiple incremental axial steps from the leading edge to the trailing edge. The flame stabilizers can be fixed or stationary relative to the rotating blades.

[0018] The following description generally presents various embodiments of a turbine stage isothermal expansion system to help improve the efficiency of a gas turbine system. The isothermal expansion system may include any and all combinations of the disclosed features, including variations of the variable injection system and variable stabilizer system. While reference is made to an isothermal expansion system, the disclosed embodiments are intended to include substantially isothermal expansion through the turbine stages within the turbine stage expansion.

[0019] 1 is a block diagram of an embodiment of a combined cycle system 10 having a gas turbine system 12, a steam turbine system 14, and a heat recovery steam generator (HRSG) 16. As described in further detail below, the combined cycle system 10 includes an isothermal expansion system 18 coupled to the gas turbine system 12 to facilitate isothermal expansion within the turbine stages. Before discussing the details of the isothermal expansion system 18, various aspects of the combined cycle system 10 will be described in further detail. For orientation purposes in the drawings, reference may be made to an axial or axial axis 30, a radial or radial axis 32 (extending radially away from the axial or axial axis 30), and a circumferential or circumferential axis 34 (extending circumferentially around the axial or axial axis 30). The directions or axes 30, 32, and 34 may be referenced, for example, to an axis of rotation 36 of the gas turbine system 12.

[0020] The gas turbine system 12 may include an intake section 40, a compressor or compressor section 42, a combustor section 44, a gas 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 around 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 may include multiple compressor stages 58, each having multiple compressor vanes 56 circumferentially spaced at axial positions about the at least one shaft 50 and multiple compressor blades 54 circumferentially spaced at different axial positions about the at least one shaft 50 (i.e., the compressor vanes 56 and compressor blades 54 are axially spaced apart). Thus, the compressor section 42 is configured to intake a gas stream from the intake section 40 and progressively compress the gas stream through the multiple compressor stages 58. As described in further detail below, the gas stream may include an intake air stream, an exhaust gas recirculation (EGR) stream, or a combination thereof.

[0021] The combustor section 44 may include one or more combustors 62, such as a single annular combustor circumferentially disposed about the rotational axis 36, or multiple combustors 62 spaced circumferentially about the rotational axis 36. In the illustrated embodiment, each combustor 62 includes a head-end portion 64 coupled to a combustion section 66. The combustion section 66 includes a combustion chamber 68, a combustor liner 70 circumferentially disposed about the combustion chamber 68, a flow sleeve 72 circumferentially disposed 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 within the head-end portion 64. The head-end chamber 78 of the combustor 62 and the combustion chamber 68 are separated or divided from each other by an intermediate plate 80. In the head-end chamber 78, a plurality of fuel nozzles 82 are coupled to the intermediate plate 80 and an end plate 84 of the head-end portion 64. In operation, each combustor 62 receives compressed gas 86 (e.g., air, EGR, etc.) from the compressor section 42 and channels the compressed gas 86 along the passages 74 toward the head end chamber 78, as indicated by arrows 76, and channels the compressed gas through the fuel nozzles 82 and into the combustion chamber 68.

[0022] In certain embodiments, each combustor 62 may receive one or more fluid streams from a fluid system 88, which may include a fuel supply system 90, an oxidizer supply system 92, and a fluid supply system 94. The fluid system 88 may include one or more fluid circuits 96 (e.g., fluid conduits, manifolds, valves, etc.) extending to multiple fuel nozzles 82 and / or other locations along the combustor 62. For example, the fuel supply system 90 is configured to supply one or more fuels, such as liquid fuels and / or gaseous fuels, to each of the fuel nozzles 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 oxidizer supply system 92 is configured to supply one or more oxidizers, such as air, oxygen, oxygen-enriched air, or oxygen-lean air, to each of the fuel nozzles 82 for injection into the combustion chamber 68. Fluid supply system 94 is configured to inject one or more fluids, such as exhaust gases, carbon dioxide, an inert gas such as nitrogen, or any combination thereof, into fuel nozzles 82 for injection into combustion chamber 68. In certain embodiments, fluid system 88 may exclude oxidant supply system 92 and / or fluid supply system 94.

[0023] Fluid system 88 may include multiple components for controlling the flow of various fluids to combustor 62. For example, fuel supply system 90 may include one or more components 98, oxidant supply system 92 may include one or more components 100, and fluid supply system 94 may include one or more components 102. In certain embodiments, components 98, 100, and 102 may include one or more valves, pressure regulators, flow regulators, filters, moisture removal units, particle removal units, manifolds, flow controllers, or any combination thereof.

[0024] The fuel nozzles 82 are configured to inject one or more fuels from a fuel supply system 90, an oxidizer from an oxidizer supply system 92, a fluid from a fluid supply system 94, and 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 device 110, such as an electric motor, a combustion engine, a shaft coupled to the gas turbine system 12, or another suitable drive device. For example, in certain embodiments of the gas turbine system 12 with exhaust gas recirculation (EGR), the compressor section 42 supplies the compressed gas 86 (e.g., compressed exhaust gas) to each combustor 62, while the compressor system 106 supplies the compressed air 104 to each combustor 62 and / or the oxidizer supply system 92 supplies the oxidizer to each combustor 62.

[0025] As yet another example, 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 a supply of additional air and / or oxidant. Accordingly, the compressor system 106 may optionally supply compressed air 104 to each combustor 62, and / or the oxidant supply system 92 may optionally supply oxidant to each combustor 62. In operation, fuel may be combusted with air and / or oxidant in the combustion chamber 68 of each combustor 62, thereby generating hot combustion gases 112 for supply from the combustion chamber 68 into the turbine section 46.

[0026] The turbine section 46 includes at least one shaft 114 disposed along the rotational axis 36, a casing 116 (e.g., an annular casing) circumferentially disposed around 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 circumferentially spaced around the at least one shaft 114 at an axial position and a plurality of turbine blades 118 circumferentially spaced around the at least one shaft 114 at different axial positions (i.e., the turbine vanes 120 and the turbine blades 118 are axially spaced apart). The at least one shaft 114 may also be coupled to the at least one shaft 50 of the compressor section 42 via at least one intermediate shaft 124. Additionally, 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 propulsion system for a vehicle, or any other suitable load. In the illustrated embodiment, the load 126 may be a generator, thereby making 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 progressively expand and drive the rotation of turbine blades 118 coupled to the at least one shaft 114 in each of the turbine stages 122. The combustion gases 112 thus drive the turbine section 46, which, in turn, drives the compressor section 42 and the load 126 via the interconnected shafts 50, 124, 114, and 128.

[0027] In certain embodiments, the gas turbine system 12 may be configured with a common rotational direction of the shafts 50, 114, 124, 128 and the connected compressor blades 54 and turbine blades 118. The shafts 50, 114, 124, 128 may be detachably coupled with shaft connections, such as flange joints. In some embodiments, some of the shafts may be combined to reduce the number of shafts. For example, all of the illustrated shafts 50, 114, 124 may represent a common shaft that rotates in a common rotational direction, such as a clockwise or counterclockwise rotational direction.

[0028] Alternatively, in some embodiments, the gas turbine system 12 may be configured for counter-rotation of the compressor blades 54 in the compressor section 42 and / or counter-rotation of the turbine blades 118 in the turbine section 46. In such embodiments, at least one shaft 50 in the compressor section 42 may include a concentric arrangement of an inner shaft 50A surrounded by an outer shaft 50B along at least a portion of the compressor section 42. Similarly, at least one shaft 114 in the turbine section 46 may include a concentric arrangement of an inner shaft 114A surrounded by an outer shaft 114B along at least a portion of the turbine section 46. For example, in the compressor section 42, the inner shaft 50A may be coupled to the compressor blades 54 in a subset 130 of the compressor stages 58, while the outer shaft 50B is coupled to a subset 132 of the compressor stages 58. Similarly, in turbine section 46, inner shaft 114A may be coupled to turbine blades 118, while outer shaft 114B may be coupled to turbine blades 118 in a subset 136 of turbine stages 122. For example, the counter-rotating blades in turbine section 46 may include turbine blade set 140 (or turbine stage portion) followed by turbine blade set 142 (or turbine stage portion), where turbine blade sets 140 and 142 are coupled to outer shaft 114B and inner shaft 114A, respectively.

[0029] The outer shaft 114B of the turbine section 46 is coupled to the outer shaft 50B of the compressor section 42 via the outer shaft 124B of the intermediate shaft 124. Similarly, the inner shaft 114A of the turbine section 46 is coupled to the inner shaft 50A of the compressor section 42 via the inner shaft 124A of the intermediate shaft 124. In operation, the inner shaft 50A and associated compressor blades 54, the inner shaft 124A, and the inner shaft 114A and associated turbine blades 118 (i.e., turbine blade set 142) rotate in a first direction about the axis of rotation 36. The outer shaft 50B and associated compressor blades 54, the outer shaft 124B, and the outer shaft 114B and associated turbine blades 118 (i.e., turbine blade set 140) rotate in a second rotational direction about the axis of rotation 36. The first and second rotational directions are opposite or contralateral to each other. Although the gas turbine system 12 may be configured with counter-rotating compressor blades 54 and turbine blades 118, embodiments of the gas turbine system 12 may include a single rotational direction of the shaft and associated blades. In embodiments with a single rotational direction of the shaft, turbine blade set 140 may be the only blade set used in the first turbine stage, and turbine blade set 142 may be omitted from the first turbine stage. Counter-rotating blade sets 140, 142 are useful in turbines where the pressure drop across the first turbine stage is high enough to cause excessive loads on a single turbine blade set. Thus, the use of two blade sets configured to counter-rotate with respect to one another manages the pressure drop.

[0030] The gas turbine system 12 may be configured with or without a compressor system 106 and an exhaust gas recirculation (EGR) system 150. The EGR system 150 is configured to recirculate exhaust gas 152 output by the turbine section 46 into the compressor section 42 (e.g., via the intake section 40) for compression and delivery to the combustor section 44. However, the gas turbine system 12 may exclude the EGR system 150 and only take in airflow into the intake section 40 for compression by the compressor section 42.

[0031] 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, thereby compressing the recirculated exhaust gas as compressed gas 86 and supplying it to the combustor section 44. The combustor section 44 may also receive compressed air 104 from an air compressor 108 of the compressor system 106, oxidizer from an oxidizer supply system 92, or a combination thereof, via fuel nozzles 82. The combustor section 44 also receives fuel from a fuel supply system 90, such as via the fuel nozzles 82. The fuel from the fuel supply system 90 is then combusted with the air from the compressor system 106 and / or the oxidizer from the oxidizer supply system 92 to generate combustion gases 112, which then flow through the turbine section 46 and drive the rotation of the turbine blades 118 in each of the turbine stages 122. The recirculated exhaust gas is used to reduce certain emissions associated with combustion in the combustor section 44, such as nitrogen oxides (NO X )) helps to reduce the temperature and formation of.

[0032] In certain embodiments of the gas turbine system 12 without 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 as compressed gas 86 into the combustor section 44. The compressed airflow then promotes combustion of fuel from the fuel supply system 90, thereby generating hot combustion gases 112 for delivery to the turbine section 46. In such embodiments, the compressor system 106 may be omitted or may be included to provide additional compressed air 104 to the combustor section 44. Additionally, the oxidizer supply system 92 may be omitted or may be included to provide an additional oxidizer flow to the combustor section 44. Regardless of the configuration, the combustion gases 112 drive the rotation of turbine blades 118 in the turbine stages 122, thereby rotating 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.

[0033] The exhaust gas 152 output by the turbine section 46 may then pass through the HRSG 16 to transfer heat from the exhaust gas to water to generate steam for the steam turbine system 14. For example, the HRSG 16 may include 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 heat recovery steam generator 16 may deliver the high-pressure steam 166 to a high-pressure steam turbine 172 of the steam turbine system 14, the intermediate-pressure steam 168 to an intermediate-pressure steam turbine 174, and the low-pressure steam 170 to a low-pressure steam turbine 176. The steam drives the rotation of blades in each of the steam turbines 172, 174, 176, thereby driving a shaft 178 connected to a load 180, such as an electrical generator. The low-pressure steam turbine 176 may also return condensed water 182 to the low-pressure section 164 of the HRSG 16. The HRSG 16 may then output the exhaust gas 152 as a partially cooled exhaust gas 184 , which may then pass through a gas treatment system 190 .

[0034] Gas processing system 190 may include a carbon capture system 192 and multiple gas processing components, such as components 194, 196, 198, 200, and 202. Gas processing system 190 is configured to remove one or more undesirable substances from exhaust gas 184. In certain embodiments, carbon capture system 192 removes carbon oxides (CO), such as carbon dioxide (CO) and / or carbon monoxide (CO). X ), and are configured to remove and recover carbon dioxide. Components 194, 196, 198, 200, and 202 may be part of carbon recovery system 192 and / or may be separate. Components 194, 196, 198, 200, and 202 may include one or more of a gas removal system, a water removal system (e.g., a water-gas separator), a particle removal system (e.g., a filter and / or a solid-gas separator), one or more heat exchangers, or any combination thereof. The separator may include one or more of a gravity separator, a centrifuge, or a combination thereof. The gas removal system may be part of carbon recovery system 192 and may include a solvent-based gas absorption system, a sorbent-based gas adsorption system, or a combination thereof. The gas removal system may include an acid gas removal (AGR) system, a sulfur recovery unit, or a combination thereof. In the illustrated embodiment, carbon capture system 192 may capture and output carbon dioxide (CO2) 204, which may be further directed to fluid supply system 94 and / or compression system 206. For example, compression system 206 may include one or more compressors configured to compress the carbon dioxide and deliver the carbon dioxide to storage and / or a pipeline 208.

[0035] In certain embodiments, the exhaust gases 184 may flow to the EGR system 150 partially or completely bypassing the gas treatment system 190, and / or the exhaust gases 184 may pass partially or completely through the gas treatment system 190 before flowing to the EGR system 150. The EGR system 150 may include various conduits, valves, and flow controls configured to provide at least a portion of the exhaust gases 152, 184 (e.g., an EGR stream) to the intake section 40 for recirculation through the compressor section 42. The exhaust gases 152, 184 may be extracted at various locations and used as one of the fluids in the fluid supply system 94. The fluid supply system may provide the exhaust gases 152, 184 for use as a barrier gas stream in the isothermal expansion system 18, as described in further detail below.

[0036] In certain embodiments, gas turbine system 12 includes an air separation unit (ASU) 210 configured to receive an intake air stream and separate the air into constituent gases, such as oxygen 212 for supply to oxidant supply system 92 and nitrogen 214 for supply to fluid supply system 94. Oxygen 212 and nitrogen 214 may also be used for other purposes throughout combined cycle system 10. However, in some embodiments, ASU 210 may be excluded from combined cycle system 10.

[0037] In the illustrated embodiment, combined cycle system 10 also includes a controller 220 coupled to gas turbine system 12, steam turbine system 14, HRSG 16, isothermal expansion system 18, gas processing system 190, fluid system 88, EGR system 150, compressor system 106, ASU 210, and various sensors 222 distributed throughout combined cycle system 10. In the illustrated embodiment, controller 220 includes one or more processors 224, a memory 226, instructions 228 stored in memory 226 and executable by processor 224, and communication circuitry 230 configured to communicate with sensors 222 and various equipment throughout combined cycle system 10. For example, controller 220 is configured to control fluid supplies (e.g., fuel, oxidant, and fluid) from fluid system 88 to combustor section 44 and isothermal expansion system 18. In certain embodiments, controller 220 is configured to control fuel, oxidant, and fluid supply systems 90, 92, and 94 to control the flow of fuel, oxidant, and fluid (e.g., barrier fluid) to isothermal expansion system 18 to assist in providing isothermal expansion of combustion gases 112 through turbine blade sets 140 and / or 142.

[0038] The controller 220 may store one or more control modes (e.g., an isothermal control mode, a part load control mode, a full load control mode, or a combination thereof) in the memory 226 for execution by the processor 224. The isothermal control mode is configured to control the isothermal expansion system 18, including the fluid injectors 246, to provide variable combustion axial positioning to assist in reducing temperature fluctuations and promoting isothermal expansion through the turbine blade sets 140 and / or 142. As used herein, the fluid injectors 246 are intended to include fuel injectors and multi-fluid injectors that inject fuel, oxidizer, and barrier gas. Thus, references to fluids associated with the fluid injectors 246 are intended to include fuel or a suitable fluid mixture for promoting combustion. The isothermal control mode may also include and / or be associated with a part load control mode and a full load control mode, thereby adjusting the isothermal expansion system 18 to account for changes in operating parameters (e.g., changes in pressure ratio across the compressor section 42) due to changes in load on the gas turbine system 12. As described in further detail below, the isothermal control mode (e.g., via a part load control mode and a full load control mode) may enable variation of the axial extent of the variable combustion axial position across the turbine blade sets 140 and / or 142 in response to changes in the load on the gas turbine system 12.

[0039] For example, the isothermal control mode (e.g., via the part load control mode and the full load control mode) may enable changes in the axial extent of the variable combustion axial location by at least changing the axial distance between the upstream end and the downstream end of the axial extent, changing the upstream axial position of the upstream end of the axial extent, changing the downstream axial position of the downstream end of the axial range, or a combination thereof. These changes in axial extent may be achieved by modifying the fluid flows (e.g., fuel flow, oxidant flow, and / or barrier gas flow) by either (A) moving the axial location of the combustion further upstream from the trailing edge of the turbine blades 118 in response to a decrease in load on the gas turbine system 12, or (B) moving the axial location of the combustion downstream toward the trailing edge of the turbine blades 118 in response to an increase in load on the gas turbine system 12.

[0040] Sensors 222 (designated "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 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, isothermal expansion system 18, or any combination thereof.

[0041] 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 of each turbine stage, turbine inlet, and turbine exhaust), and exhaust gas emissions. In the illustrated embodiment, sensors 222 may monitor the expansion of combustion gases 112 in turbine section 46, such as turbine blade sets 140 and 142, so that controller 220 can monitor and control additional combustion and temperature distribution in turbine blade sets 140 and 142 to enable isothermal expansion. As yet another example, exhaust gas emissions monitored by sensors 222 may include carbon oxides (CO), such as carbon dioxide (CO) and carbon monoxide (CO). X ), nitrogen oxides such as nitrogen dioxide (NO2) X ), sulfur dioxide (SO2) and other sulfur oxides (SO X ), unburned hydrocarbons, particulate matter, and other undesirable exhaust emissions.

[0042] In the illustrated embodiment, isothermal expansion system 18 is configured to provide isothermal expansion across at least one or more turbine stages 122 of turbine section 46, such as turbine blade set 140 and / or turbine blade set 142. Isothermal expansion system 18 may provide isothermal expansion across turbine blade sets 140 and 142, for example, in a counter-rotating configuration of turbine blades 118. Isothermal expansion system 18 may include a distribution system 240 coupled to fluid system 88 and a fluid manifold 242. Distribution system 240 may include multiple distribution components 244, such as valves, pressure regulators, fluid manifolds, flow controllers, sensors, one or more fluid circuits, or any combination thereof. Isothermal expansion system 18 includes multiple fluid circuits 254, each fluid circuit 254 including one or more valves 256 to enable flow control by controller 220. Fluid circuits 254 may be included with and / or extend between fluid system 88, distribution system 240, and fluid manifold 242.

[0043] The number of fluid circuits 254 may correspond to the number of different axial locations of heat release of combustion, which may include at least 2 to 1000, 5 to 500, 10 to 100, a number equal to the number of turbine vanes 120, or a number equal to the axial length of the turbine vanes 120 divided by the desired axial spacing of the fluid injectors 246 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, or 50 mm). The fluid circuits 254 may include a fuel circuit, an oxidizer circuit, a barrier fluid circuit, a mixed fluid circuit, or any combination thereof. For example, the fluid circuits 254 may include multiple fuel circuits coupled to the fuel supply system 90, multiple oxidizer circuits coupled to the oxidizer supply system 92, and multiple fluid circuits (e.g., barrier fluid circuits) coupled to the fluid supply system 94. In certain embodiments, distribution component 244 may include one or more fluid mixers or mixing chambers configured to mix fluids from fluid system 88 before the fluids are delivered to fluid manifold 242 coupled to turbine section 46. Thus, distribution system 240 may be configured to individually or collectively deliver fuel, oxidant, and / or fluid (e.g., barrier fluid) to fluid manifold 242 along turbine blade set 140 and / or turbine blade set 142.

[0044] Isothermal expansion system 18 includes multiple combustion control mechanisms on turbine vanes 120 and turbine blades 118. Isothermal expansion system 18 may include multiple fluid injectors 246 disposed on turbine vanes 120 of turbine vane set 248 upstream of turbine blade set 140 and / or turbine blade set 142. In certain embodiments, isothermal expansion system 18 may also include one or more flame stabilizers 250 disposed along each of turbine blades 118 within turbine blade set 140 and / or turbine blade set 142. In the illustrated embodiment, fluid injectors 246 within turbine vane set 248 and flame stabilizers 250 within turbine blade sets 140 and, if present, 142 are all part of a common turbine stage 252. For example, common turbine stage 252 may be an inlet or first turbine stage of turbine section 46. In some embodiments, isothermal expansion system 18 may be disposed in one or more turbine stages 122 downstream from the inlet turbine stage. Furthermore, when used with multiple turbine stages 122 , the isothermal expansion system 18 may have the same or different configurations for each of the turbine stages 122 .

[0045] As described below, the fluid injectors 246 are configured to provide a combustible mixture for generating combustion within the turbine blade sets 140 and 142. Each fluid injector 246 may include one or more fluid injection ports, such as a fuel injection port, an oxidizer injection port, and / or a fluid injection port (e.g., a barrier fluid injection port). The fluid injectors 246 may be configured to inject a fuel-oxidizer mixture (e.g., premixed upstream in a mixing chamber) and / or to separately inject fuel, oxidizer, and fluid streams (e.g., along the turbine blades 118 in the turbine blade sets 140 and / or 142) for subsequent mixing downstream. In certain embodiments, the fluid injectors 246 are coupled to multiple fluid circuits 254 having valves 256 to enable variable control of the fluid injection. The isothermal expansion system 18 may also include one or more flame stabilizers 250 disposed along each of the turbine blades 118 in the turbine blade sets 140 and 142. Flame stabilizer 250 may include structural features configured to help retain and / or stabilize a flame at specific locations (e.g., axial and radial locations) along turbine blade 118. Fluid injectors 246 on turbine vanes 120 and / or flame stabilizers 250 on turbine blades 118 are configured to control the distribution of the flame (and associated heat release) at multiple locations (e.g., axial and radial locations) between the leading and trailing edges of turbine blade 118, thereby providing a substantially uniform temperature during expansion (e.g., isothermal expansion) of combustion gases 112 through turbine blade sets 140 and 142. As is known, isothermal expansion improves the efficiency and performance of gas turbine system 12.

[0046] 2 is a schematic diagram of one embodiment of a portion of turbine section 46 of FIG. 1 , further illustrating details of isothermal expansion system 18 including variable injection system 270 with fluid circuit 254 coupled to fluid injectors 246 and variable stabilizer system 272 with flame stabilizer 250. As described below, variable injection system 270 includes fluid injectors 246 positioned at different axial locations within the turbine stage expansion to help vary the axial location of heat release from combustion along turbine blades 118. Variable stabilizer system 272 also includes flame stabilizers 250 positioned at different axial locations within the turbine stage expansion to help vary the axial location of heat release from combustion along turbine blades 118 within the turbine stage. In certain embodiments, flame stabilizer 250 may be omitted while fluid injectors 246 control the axial location of heat release. The fluid injectors 246 may also incorporate other controls to facilitate varying the axial location of the heat release, such as by controlling the fluid flow rate of fuel, oxidant, and / or fluid (e.g., barrier fluid) per fluid injector 246. Details of the isothermal expansion system 18 are described in more detail below after describing the arrangement of the turbine vanes 120 and turbine blades 118.

[0047] As shown, a portion of turbine section 46 (e.g., turbine stage 252) having isothermal expansion system 18 includes turbine vane set 248 having a circumferential arrangement 274 of vanes 120 at an axial position 276 along rotational axis 36, turbine blade set 140 having a circumferential arrangement 278 of turbine blades 118 at an axial position 280 along rotational axis 36, and turbine blade set 142 having a circumferential arrangement 282 of blades 118 at an axial position 284 along rotational axis 36. Axial position 276 of circumferential arrangement 274 of vanes 120 (i.e., turbine vane set 248) is located upstream from axial positions 280 and 284 of circumferential arrangements 278 and 282 of blades 118 (i.e., turbine blade sets 140 and 142). An axial location 280 of a circumferential location 278 of blades 118 (ie, turbine blade set 140) is located upstream from an axial location 284 of a circumferential location 282 of blades 118 (ie, turbine blade set 142).

[0048] In turbine vane set 248, circumferential arrangement 274 has vanes 120 generally aligned with one another at axial positions 276, such that vanes 120 axially overlap one another along rotational axis 36. Similarly, in turbine blade set 140, circumferential arrangement 278 has blades 118 generally aligned with one another at axial positions 280, such that blades 118 axially overlap one another along rotational axis 36. Finally, in turbine blade set 142, circumferential arrangement 282 has blades 118 generally aligned with one another at axial positions 284, such that blades 118 axially overlap one another along rotational axis 36. In the illustrated embodiment, vanes 120 are positioned in a stationary position, blades 118 in circumferential arrangement 278 of turbine blade set 140 rotate in rotational direction 286 about rotational axis 36, and blades 118 in circumferential arrangement 282 of turbine blade set 142 rotate in rotational direction 288 about rotational axis 36. As illustrated, rotational directions 286 and 288 are opposite or counter-rotating to one another, such that blades 118 in turbine blade sets 140 and 142 counter-rotate to one another (i.e., counter-rotating turbine blades 118).

[0049] For reference, dashed vertical line 290 represents 0 degrees about the axis of rotation 36, dashed vertical line 292 represents 180 degrees about the axis of rotation 36, and dashed vertical line 294 represents 360 degrees about the axis of rotation 36. Accordingly, the depicted vanes 120 and blades 118 are shown at various angular or circumferential positions throughout 360 degrees about the axis of rotation 36. As described in further detail below, isothermal expansion system 18 has a variable injection system 270 and a variable stabilizer system 272 configured to modify the heat release of combustion occurring in the depicted portion of turbine section 46 (i.e., within the turbine stage expansion of turbine stage 252).

[0050] In the illustrated embodiment, the variable injection system 270 has fluid injectors 246 disposed on the vanes 120 at variable injection locations 296 (e.g., spatially distributed injection locations), as indicated by dashed lines 298. The dashed lines 298 vary in axial position from 0 degrees to 180 degrees, as indicated by dashed lines 290 and 292, and from 180 degrees to 360 degrees, as indicated by dashed lines 292 and 294. Each vane 120 has a leading edge 300, a trailing edge 302, a pressure side or surface 304 extending from the leading edge 300 to the trailing edge 302, and a suction side or surface 306 extending from the leading edge 300 to the trailing edge 302. The variable injection locations 296 of the fluid injectors 246 may vary in position (e.g., axial position, radial position) from the leading edge 300 to the trailing edge 302 of each respective vane 120.

[0051] For example, the variable injection locations 296 may include from 2 to 1000 or more axial and radial locations, such as at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 100, 200, or more axial and radial locations. For example, vanes 120 near 0 and 360 degrees may have fluid injectors 246 located on or near the leading edge 300, vanes 120 located near the 180 degree location may have fluid injectors 246 located near the trailing edge 302, and vanes 120 located between 0 and 180 degrees and between 180 and 360 degrees may have fluid injectors 246 located at or intermediate locations between the leading edge 300 and the trailing edge 302. Thus, the variable injection position 296 of the fluid injector 246 may vary in the axial distance from the leading edge 300 to the fluid injector 246 and relative to the overall axial length 310 of the turbine blade 118 from the leading edge 300 to the trailing edge 302 along the axis of rotation 36. The variable injection position 296 of the fluid injector 246 may vary periodically, for example, from 0 degrees to 360 degrees, with dashed line 298 intersecting dashed lines 290, 292, and 294. The dashed line 298 may represent a sinusoidal, cosine, or sawtooth periodic variation having one period of variation about the axis of rotation 36, with the axial position 276 varying from near the leading edge 300 to near the trailing edge 302 throughout the period. Other embodiments may include a periodic variation having multiple periods of variation about the axis of rotation 36. For example, without limitation, embodiments may include a sinusoidal or sawtooth variation having multiple periods. Additionally, the variable injection location 296 may have a variable radial position along the radial direction or axis 32 .

[0052] The fluid injectors 246 may also have an injection axis or injection direction 312 disposed at an angle 314 relative to a tangent 316 of the fluid injector 246. In certain embodiments, the angle 314 may be constant across the vanes 120 in the turbine vane set 248. Alternatively, the angle 314 may be variable for each fluid injector 246 across the vanes 120 in the turbine vane set 248. For example, the angle 314 may be constant or variable for multiple fluid injectors 246 on each individual vane 120 and / or between fluid injectors 246 on different vanes 120. The fluid injectors 246 may also be constant or variable in other aspects, including the cross-sectional area of ​​the fluid injection ports, the geometry of the fluid injection ports (e.g., circular, elliptical, rectangular, etc.), the fluid flow rate, or any combination thereof, between the fluid injectors 246 and / or between the vanes 120. For example, the fluid injectors 246 may have a constant or variable total fluid injection port cross-sectional flow area between the fluid injectors 246 and / or between the vanes 120. Also, in certain embodiments, each fluid injector 246 includes multiple fluid injection ports, such as a fuel injection port, an oxidizer injection port, and a barrier fluid injection port, and the cross-sectional area (or ratio of cross-sectional areas) of the fluid injection ports may be constant or variable between the fluid injectors 246 and / or between the vanes 120. Similarly, in embodiments with multiple fluid injection ports per fluid injector 246, the ratio of fluid flow rates (e.g., fuel, oxidizer, and fluid) may be constant or variable between the fluid injectors 246 and / or between the vanes 120.

[0053] Each of the vanes 120 is fluidly coupled to one or more fluid circuits 254 having valves 256 coupled to the controller 220. The fluid circuits 254 may be part of, extend through, and / or fluidly couple the fluid system 88, the distribution system 240, and the fluid manifold 242, as described above with reference to FIG. 1. Using the fluid circuits 254 and the valves 256, the distribution system 240 is configured to supply one or more fluids (e.g., fuel, oxidizer, and fluid) from the fluid system 88 (e.g., supply systems 90, 92, and 94) to the fluid manifold 242, which then routes the fluid to each of the fluid injectors 246 in the vanes 120. For example, the distribution system 240 may route fuel from the fuel supply system 90 through the fluid manifold 242 to the various fluid injectors 246 in the vanes 120 via one or more fuel circuits of the fluid circuit 254. Distribution system 240 may route oxidizer from oxidizer supply system 92 through fluid manifold 242 to various fluid injectors 246 in vanes 120 via one or more oxidizer circuits of fluid circuit 254. Distribution system 240 may route fluid (e.g., barrier fluid) from fluid supply system 94 through fluid manifold 242 to various fluid injectors 246 in vanes 120 via one or more fluid circuits (e.g., barrier fluid circuits) of fluid circuit 254.

[0054] In certain embodiments, the fuel circuit, oxidizer circuit, and fluid circuit are separate from one another (i.e., separate fluid circuits 254 and fluid manifolds 242), such that fluid injectors 246 separately inject fuel, oxidizer, and fluid flows into turbine section 46. For example, distribution system 240 may use separate fluid circuits 254 to route fuel, oxidizer, and fluid from supply systems 90, 92, and 94 through fluid manifold 242 to multiple fluid ports of each fluid injector 246, as described in further detail below. However, in some embodiments, distribution system 240 mixes one or more fluids (e.g., fuel, oxidizer, and / or fluid) from supply systems 90, 92, and 94, thereby generating a fluid mixture (e.g., a fuel-oxidizer mixture) for distribution to fluid injectors 246 through the circuits of mixed fluid manifold and fluid circuit 254. The controller 220 may also control the fluid flow rates of various fluids to the fluid injectors 246 to help vary the heat release downstream of the turbine blade sets 140 and 142 .

[0055] In the illustrated embodiment, the variable injection system 270 includes a plurality of fluid circuits 254 (e.g., 254A, 254B, 254C, 254D, 254E, 254F, 254G, 254H, 254I, 254J, and 254K) and associated valves 256 (e.g., 256A, 256B, 256C, 256D, 256E, 256F, 256G, 256H, 256I, 256J, and 256K) coupled to fluid injectors 246 on a plurality of turbine vanes 120. Each of the illustrated fluid circuits 254 may represent a single fluid circuit (e.g., a single fuel, oxidant, or barrier gas circuit) or multiple fluid circuits (e.g., multiple fuel, oxidant, and / or barrier gas circuits). For example, each of the turbine vanes 120 may be coupled to a single fluid circuit 254 or multiple fluid circuits 254, each of the fluid circuits 254 may be coupled to a single turbine vane 120 or multiple turbine vanes 120, and each of the fluid circuits 254 may be coupled to a single fluid injector 246 or multiple fluid injectors 246. In the illustrated embodiment, each of the turbine vanes 120 has one or multiple (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) fluid injectors 246 positioned at different locations of the variable injection locations 296, and each of the turbine vanes 120 is coupled to one or more different fluid circuits 254 to supply one fluid stream (e.g., a fuel stream) or multiple fluid streams (e.g., fuel, oxidant, and barrier gas streams) to the fluid injectors 246. For each turbine vane 120, the fluid injectors 246 may be positioned at a common axial location, as described below with reference to Figures 4-6 and 10-12, or at a variable axial location, as described below with reference to Figures 7-9. In certain embodiments, the variable injection locations 296 vary at least partially or completely between turbine vanes 120.

[0056] Variable injection system 270 and variable stabilizer system 272 are configured to enable and control variable heat release or combustion location 320 (e.g., spatially distributed heat release) along turbine blade sets 140 and 142 within turbine stage expansion. Accordingly, isothermal expansion system 18 may enable and control variable heat release or combustion location 320 at circumferential arrangement 278 of blades 118 within turbine blade set 140 and / or at circumferential arrangement 282 of blades 118 within turbine blade set 142. As shown, variable heat release or combustion location 320 is indicated by stars along dashed line 322 within turbine blade set 140 and dashed line 324 within turbine blade set 142, respectively. Dashed lines 322 and 324 generally vary in axial position between 0 degrees and 180 degrees, as indicated by dashed lines 290 and 292, and between 180 degrees and 360 degrees, as indicated by dashed lines 292 and 294. Dashed lines 322 and 324 represent one possible embodiment of a variation (e.g., spatial variation) in variable heat release or combustion location 320. However, dashed lines 322 and 324 may vary in other manners, such as sloping lines, curved lines, wavy or zigzag lines, randomly or irregularly varying lines, or any combination thereof. For example, dashed lines 322 and 324 may vary periodically, e.g., from 0 degrees to 360 degrees, as dashed lines 322 and 324 intersect dashed lines 290, 292, and 294. Dashed line 298 may represent a sinusoidal, cosine, or sawtooth-like periodic variation having one period of variation about axis of rotation 36, with axial positions 280 and 284 varying from near leading edge 326 to trailing edge 328 throughout the period. Other embodiments may include a periodic variation having multiple periods of variation about axis of rotation 36. For example, embodiments may include, but are not limited to, sinusoidal or sawtooth variations having multiple periods.

[0057] 2 , each of the blades 118 in circumferential arrangements 278 and 282 has a leading edge 326, a trailing edge 328, a pressure side or surface 330 extending from the leading edge 326 to the trailing edge 328, and a suction side or surface 332 extending from the leading edge 326 to the trailing edge 328. The variable heat release or combustion location 320 of combustion occurring in the turbine section 46 downstream of the fluid injectors 246 varies axially between the leading edge 326 and the trailing edge 328 of the blades 118 in the circumferential arrangements 278 and / or the circumferential arrangements 282 of the blades 118. For example, the variable heat release or combustion location 320 may be defined with reference to a reference location such as the leading edge 326. Additionally, an axial distance 334 may be defined from a reference location (e.g., leading edge 326) to each variable heat release or combustion location 320, where axial distance 334 is a portion of the overall axial length 336 from leading edge 326 to trailing edge 328 of blade 118.

[0058] In certain embodiments, one or more of the variable heat release or combustion locations 320 may be located directly adjacent to the leading edge 326 as shown by the blade 118 at 0 degrees and 360 degrees (e.g., axial distance 334 is zero), directly adjacent to the trailing edge 328 as shown by a location near 180 degrees (e.g., axial distance 334 equals overall axial length 336), or at an axial distance 334 intermediate between the leading edge 326 and the trailing edge 328 of the blade 118. Thus, the variable heat release or combustion locations 320 may include an axial distance 334 that varies 360 degrees about the axis of rotation 36 for each blade 118 in each of the circumferential locations 278 and 282. The variable heat release or combustion locations 320 may be axially spaced apart from one another at equal intervals, uneven intervals, or a combination thereof. For example, the equal spacing may be defined by the overall axial length 336 divided by N, where N may be any number from 2 to 1000, 2 to 500, 2 to 100, or 2 to 50. For example, N may be at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more.

[0059] In certain embodiments, the variable heat release or combustion location 320 may be achieved at least in part or in whole by a variable injection system 270 having a variable injection location 296. For example, varying the axial distance 308 of the fluid injectors 246 may vary the axial distance 334 of the variable heat release or combustion location 320 along the blades 118 downstream of the vanes 120. The variable injection system 270 may also vary the fluid injectors 246 by cross-sectional area, geometry, fluid flow rate, or other operating parameters configured to adjust the distance to which heat release or combustion occurs in the turbine blade sets 140 and 142, as indicated by the variable heat release or combustion location 320.

[0060] The variable injection system 270 of the isothermal expansion system 18 may be controlled by the controller 220 in one or more of a plurality of control modes 360, such as an isothermal control mode 362, a load control mode 364, a fuel control mode 366, and / or a multi-fluid control mode 368. The isothermal control mode 362 is configured to control the variable injection system 270 to control fluid flow to the plurality of fluid injectors 246 and vary the axial position of the combustion (e.g., variable heat release or combustion location 320) to reduce temperature variations across the turbine blades 118 within the turbine stage expansion, thereby providing an isothermal expansion to the turbine stage 252. In conjunction with and / or as part of the isothermal control mode 362, a load control mode 364 is configured to control the variable injection system 270 to control fluid flow to the plurality of fluid injectors 246 and vary the axial extent of the variable combustion axial location 320 in response to changes in load on the gas turbine system 12 (e.g., an increase or decrease in load). The load may be a generator load, and thus, a change in load may include a change in the generator load. Load control mode 364 is described in further detail below. A fuel control mode 366, which is coupled with and / or part of isothermal control mode 362, is configured to control variable injection system 270 to control fuel flow to multiple fluid injectors 246 (e.g., fuel-only injectors) to vary axial position 320 of combustion within the turbine stage expansion. A multi-fluid control mode 368, which is coupled with and / or part of isothermal control mode 362, is configured to control variable injection system 270 to control multiple fluid flows (e.g., fuel flow, oxidant flow, and barrier gas flow) to multiple fluid injectors 246 (e.g., multi-fluid injectors) to vary axial position 320 of combustion within the turbine stage expansion, as described in further detail below with reference to FIGS. 13 , 14 , and 17 .

[0061] The controller 220 is configured to control the variable injection system 270 using a plurality of control modes 360, alone or in any combination with one another, to vary the axial location of the combustion within a turbine stage expansion (e.g., variable heat release or combustion location 320) and / or vary the axial range of the different combustion axial locations 320. For example, in the load control mode 364, the controller 220 is configured to control the variable injection system 270 to vary the axial range of the different combustion axial locations by varying the axial distance between the upstream end and downstream end of the axial range, varying the upstream axial position of the upstream end of the axial range, varying the downstream axial position of the downstream end of the axial range, or a combination thereof. In the illustrated embodiment, the controller 220 is configured to control the variable injection system 270 to vary the axial range of the different combustion axial locations between the leading edge 326 and the trailing edge 328 of the plurality of turbine blades 118 within the turbine stage 252.

[0062] For example, the controller 220 is configured to control the variable injection system 270 to change the axial range of the axial positions of the different combustions by changing at least the downstream axial position of the downstream end of the axial range (e.g., relative to the trailing edge 328), including (A) moving the downstream axial position of the downstream end of the axial range upstream in response to a change in load, including a decrease in load on the gas turbine system 12, or (B) moving the downstream axial position of the downstream end of the axial range downstream in response to a change in load, including an increase in load on the gas turbine system 12.

[0063] As yet another example, the controller 220 is configured to control the variable injection system 270 to change the axial range of the axial positions of the different combustions by changing at least the upstream axial position of the upstream end of the axial range (e.g., relative to the leading edge 326), including (A) moving the upstream axial position of the upstream end of the axial range upstream in response to a change in load, including a decrease in load on the gas turbine system 12, or (B) moving the upstream axial position of the upstream end of the axial range downstream in response to a change in load, including an increase in load on the gas turbine system 12.

[0064] As yet another example, the controller 220 is configured to control the variable injection system 270 to vary the axial range of the axial locations of the different combustions by at least one of (A) decreasing the axial range of the axial locations of the different combustions in response to a change in load, including a decrease in the load on the gas turbine system 12, or (B) increasing the axial range of the axial locations of the different combustions in response to a change in load, including an increase in the load on the gas turbine system 12. Varying control of the axial range of the axial locations of the different combustions may be achieved by the controller 220 controlling (e.g., increasing, decreasing, starting, or stopping) fluid flow through the multiple fluid circuits 254 to the multiple fluid injectors 246 on the multiple turbine vanes 120.

[0065] 2 , during operation, the controller 220 is configured to control the variable injection system 270 to control fluid flow to the plurality of fluid injectors 246 via the plurality of fluid circuits 254 and associated valves 256, thereby selectively varying (e.g., starting, increasing, decreasing, or stopping) fluid flow at the variable injection locations 296 to achieve a corresponding change in the variable heat release or combustion location 320. The variable heat release or combustion location 320 along the turbine blade 118 can be a function of the variable injection locations 296, such that the upstream variable injection locations 296 correspond to the upstream combustion location 320, the downstream variable injection locations 296 correspond to the downstream combustion location 320, and the intermediate variable injection locations 296 correspond to the intermediate combustion location 320. Thus, the variable heat release or combustion location 320, and the axial extent of such locations 320, is controlled by selectively varying the fluid flow to the fluid injectors 246 at the variable injection locations 296.

[0066] In certain embodiments, the load control mode 364 of the controller 220 may respond to a decrease in load on the gas turbine system 12 by controlling the valves 256 along the fluid circuit 254 to gradually reduce and / or stop fluid flow to the fluid injectors 246 in a sequence based on the variable injection positions 296 (e.g., in an upstream direction starting from the downstream fluid injector 246 and moving toward the upstream fluid injector 246). For example, the controller 220 may gradually close the valves 256 along the fluid circuit 254 in the following order: (1) valve 256F along the fluid circuit 254F, (2) valve 256G along the fluid circuit 254G, (3) valve 256E along the fluid circuit 254E, (4) valve 256H along the fluid circuit 254H, (5) valve 256D along the fluid circuit 254D, (6) valve 256I along the fluid circuit 254I, (7) valve 256C along the fluid circuit 254C, (8) valve 256J along the fluid circuit 254J, (9) valve 256B along the fluid circuit 254B, (10) valve 256K along the fluid circuit 254K, and (11) valve 256A along the fluid circuit 254A. The above sequence gradually moves the variable heat release or combustion location 320 along the turbine blade 118 upstream from the trailing edge 328 towards the leading edge 326 of the turbine blade 118, thereby also reducing the axial extent of the combustion location 320.

[0067] In certain embodiments, the load control mode 364 of the controller 220 may respond to an increase in load on the gas turbine system 12 by controlling the valves 256 along the fluid circuit 254 to gradually initiate or increase fluid flow to the fluid injectors 246 in a sequence based on the variable injection positions 296 (e.g., in a downstream direction starting from the upstream fluid injector 246 and moving toward the downstream fluid injector 246). For example, the controller 220 may gradually open the valves 256 along the fluid circuit 254 in the following order: (1) valve 256A along the fluid circuit 254A, (2) valve 256K along the fluid circuit 254K, (3) valve 256B along the fluid circuit 254B, (4) valve 256J along the fluid circuit 254J, (5) valve 256C along the fluid circuit 254C, (6) valve 256I along the fluid circuit 254I, (7) valve 256D along the fluid circuit 254D, (8) valve 256H along the fluid circuit 254H, (9) valve 256E along the fluid circuit 254E, (10) valve 256G along the fluid circuit 254G, and (11) valve 256F along the fluid circuit 254F. The above sequence gradually moves the variable heat release or combustion location 320 along the turbine blade 118 downstream from the leading edge 326 to the trailing edge 328 of the turbine blade 118, thereby also increasing the axial extent of the combustion location 320.

[0068] 2 or the constant injection location 350 of FIG. 3 , the load control mode 364 of the controller 220 may control the valves 256 along the fluid circuit 254 to vary the range of flow to the different fluid injectors 246 in response to varying loads on the gas turbine system 12, thereby varying the axial extent of the combustion location 320 along the turbine blade 118 within the turbine stage expansion. For example, for each of the fluid injectors 246, the controller 220 may gradually close the valves 256 along the fluid circuit 254 to reduce the flow to the fluid injector 246, thereby gradually moving the corresponding combustion location 320 upstream from the trailing edge 328 toward the leading edge 326 of the turbine blade 118. As yet another example, for each fluid injector 246, controller 220 may gradually open valves 256 along fluid circuit 254 to increase the flow rate to the fluid injector 246, thereby gradually moving the corresponding combustion location 320 downstream from the leading edge 326 toward the trailing edge 328 of the turbine blade 118. Using the increase or decrease in flow rate to the fluid injector 246 described above, controller 220 is configured to control variable injection system 270 to vary the number of different combustion locations 320, the axial distance 334 to the different combustion locations 320, the axial extent of the different combustion locations 320, the downstream end of the axial extent, the upstream end of the axial extent, or any combination thereof.

[0069] In certain embodiments, variable heat release or combustion location 320 may be controlled at least in part or in whole by flame stabilizer 250 of variable stabilizer system 272. For example, flame stabilizer 250 may be positioned on each of blades 118 in circumferential arrangement 278 and / or circumferential arrangement 282 at various locations (e.g., axial and radial locations) along blade 118. For example, the various locations of flame stabilizer 250 may include from 2 to 1000 or more axial and radial locations, such as at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 100, 200, or more axial and radial locations. As yet another example, flame stabilizer 250 may be positioned at variable heat release or combustion location 320 at axial distance 334, as indicated by dashed lines 322 and 324, to help distribute the heat release of combustion occurring in turbine blade sets 140 and 142.

[0070] In certain embodiments, flame stabilizer 250 may be stationary or fixed in position relative to each turbine blade 118. As described in further detail below, flame stabilizer 250 includes structural features on the surface of blade 118 that promote turbulence or low-velocity zones along blade 118, facilitating flame retention or stabilization along blade 118 at different axial locations or distances 334, as indicated by variable heat release or combustion location 320. Flame stabilizers 250 may be of the same structure located at different axial distances 334, of different geometries or shapes at different or common axial distances 334, or any combination thereof. For example, as described in further detail below, flame stabilizer 250 may include one or more recesses, one or more protrusions, or any combination thereof. Thus, different flame stabilizers 250 may be used for each blade 118 in circumferential arrangement 278 and / or circumferential arrangement 282 to provide variable heat release or combustion location 320.

[0071] Variable heat release or combustion location 320 achieved by variable injection system 270 with variable injection location 296 and / or variable stabilizer system 272 with flame stabilizer 250 is configured to distribute heat release across turbine blades 118 to provide a more uniform temperature and isothermal expansion of the hot gas flow through turbine blade sets 140 and 142. Again, variable heat release or combustion location 320 may be achieved at least partially or wholly via variable injection system 270, which may vary axial distance 308 to fluid injector 246, flow path cross-sectional area, geometry, angle 314, or any combination thereof. Additionally or alternatively, variable heat release or combustion location 320 may be achieved at least partially or wholly by variable stabilizer system 272, which may vary axial distance 334 to flame stabilizer 250, geometry of flame stabilizer 250, or any combination thereof. Thus, variable injection system 270 and / or variable stabilizer system 272 are configured to evenly distribute or average the combustion temperature across turbine blade sets 140 and 142 to help provide isothermal expansion in turbine section 46.

[0072] FIG. 3 is a schematic diagram of an embodiment of a portion of the turbine section 46 of FIG. 1 , further illustrating details of the isothermal expansion system 18 having a variable injection system 270 and a variable stabilizer system 272. The illustrated embodiment has a variable stabilizer system 272 with substantially the same features as those described in detail above with reference to FIG. 2. However, the variable injection system 270 of FIG. 3 differs from the embodiment of FIG. 2 because the variable injection system 270 has fluid injectors 246 positioned at constant injection positions 350 between the vanes 120, as indicated by dashed lines 352. In particular, each vane 120 in a circumferential arrangement 274 of vanes 120 of a turbine vane set 248 may have a fluid injector 246 positioned the same axial distance 308 from the leading edge 300 of the vane 120.

[0073] However, the variable injection system 270 may vary other aspects of the fluid injectors 246 from one vane 120 to another in a circumferential arrangement 274 of the vanes 120 of the turbine vane set 248. For example, as described above with reference to FIG. 2 , the fluid injectors 246 may vary from one vane 120 to another in cross-sectional flow area, fluid flow rate, angle 314 of injection axis or direction 312, or any combination thereof. For example, if each fluid injector 246 includes a fuel injection port, the cross-sectional flow area of ​​the fuel injection port may vary from one vane 120 to another. Similarly, if each fluid injector 246 includes multiple fluid injection ports, such as a fuel injection port, a barrier fluid injection port, and an oxidizer injection port, the relative cross-sectional areas of the different ports in each fluid injector 246 may vary from one vane 120 to another in a circumferential arrangement 274. Thus, even though the variable injection system 270 of FIG. 3 has a constant injection location 350 at axial distance 308, the variable injection system 270 has other modifications to the fluid injectors 246 to provide a variable heat release or combustion location 320 on the blades 118 in the turbine blade sets 140 and 142, as described above with reference to FIG. 2.

[0074] Variable stabilizer system 272 may also include flame stabilizers 250 positioned at various axial distances 334, as described above with reference to Figure 2. In the illustrated embodiment, variable injection system 270 and variable stabilizer system 272, used alone or in combination with each other, are configured to distribute heat in a more uniform manner throughout turbine blade sets 140 and 142, thereby providing substantially isothermal expansion through turbine blade sets 140 and 142.

[0075] In the illustrated embodiment, the load control mode 364 of the controller 220 may control the valves 256 along the fluid circuit 254 to vary the range of flow to the different fluid injectors 246 in response to varying loads on the gas turbine system 12, thereby varying the axial extent of the combustion location 320 along the turbine blade 118. For example, for each of the fluid injectors 246, the controller 220 may gradually close the valves 256 along the fluid circuit 254 to reduce the flow to the fluid injector 246, thereby gradually moving the corresponding combustion location 320 upstream from the trailing edge 328 toward the leading edge 326 of the turbine blade 118. As yet another example, for each of the fluid injectors 246, the controller 220 may gradually open the valves 256 along the fluid circuit 254 to increase the flow to the fluid injector 246, thereby gradually moving the corresponding combustion location 320 downstream from the leading edge 326 toward the trailing edge 328 of the turbine blade 118. By using the increased or decreased flow rate to the fluid injectors 246 described above, the controller 220 is configured to control the variable injection system 270 to vary the number of different combustion locations 320, the axial distance 334 to the different combustion locations 320, the axial extent of the different combustion locations 320, the downstream end of the axial extent, the upstream end of the axial extent, or any combination thereof.

[0076] 4-12 are perspective views of embodiments of the vane 120 of the isothermal expansion system 18 of FIGS. 1-3, further illustrating embodiments of fluid injectors 246 that may be used alone or in combination with one another in the variable injection location 296 of FIG. 2 and / or the constant injection location 350 of FIG. 3. In each illustrated embodiment, the vane 120 has a vane body 370 that extends radially 32 from a vane base 372 to a vane tip 374. The vane 120 may have an overall radial length 376 from the base 372 to the tip 374, and the fluid injectors 246 may be positioned at multiple radial distances 378 measured radially 32 from the base 372 toward the tip 374.

[0077] In certain embodiments, the vane 120 may include a single fluid injector 246 positioned at a particular radial distance 378. However, in the illustrated embodiment, the vane 120 includes multiple fluid injectors 246 positioned at different radial distances 378 between the base 372 and the tip 374. For example, the radial distance 378 may vary from above the base 372 to above the tip 374, and anywhere in between. For example, the radial distance 378 may range from 0-100%, 10-90%, 20-80%, 30-70%, or 40-60% of the radial length 376 (sometimes referred to as the "span"). The fluid injectors 246 may be uniformly spaced radially, or the fluid injectors 246 may be non-uniformly spaced (e.g., with a greater number of fluid injectors 246 at a particular radial span).

[0078] The vane body 370 may have an airfoil geometry defined by a leading edge 300, a trailing edge 302, a pressure side 304, and a suction side 306. In certain embodiments, the vane body 370 may have a cross-sectional area or shape 380 (e.g., a cross-section of an airfoil geometry) that varies or is constant in the radial direction 32 from the base 372 to the tip 374. The number of fluid injectors 246 may include at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more fluid injectors 246 disposed on the suction side 306 of the vane body 370. As described in further detail below, for each embodiment of vane 120, for each fluid injector 246 on each vane 120, the axial distance 308 from the leading edge 300 to the fluid injector 246 may vary or remain constant, the cross-sectional area 382 of the fluid injector 246 may vary or remain constant, the angle 314 of the injection axis or direction 312 may change or remain constant, the geometric shape or geometry may vary or remain constant, and the fluid flow rate may vary or remain constant, or any combination thereof.

[0079] FIG. 4 is a perspective view of one embodiment of the vane 120 of FIGS. 1-3 , with multiple fluid injectors 246 positioned a constant axial distance 308 from the leading edge 300, as indicated by dashed line 384. In particular, dashed line 384 may be positioned directly along, adjacent to, and / or parallel to the trailing edge 302, such that dashed line 384 extends in the radial direction 32 at the constant axial distance 308 relative to the leading edge 300. In the illustrated embodiment, the axial distance 308 may be at least 70%, 80%, 90%, or 100% of the axial length 310. The vane 120 of FIG. 4 may be used for one or more of the multiple vanes 120 of FIG. 2 , with other vanes 120 positioned at multiple different axial distances 308. Also, in certain embodiments, the vane 120 of FIG. 4 may be used for each of the vanes 120 at the constant injection location 350 of FIG. 3 . 4 may vary from one another along dashed line 384 or may remain the same. For example, fluid injectors 246 may be the same or different from one another with respect to cross-sectional area 382, ​​angle 314 of ejection axis or direction 312, geometric shape or geometry, fluid flow rate, type of fluid ejected, or any combination thereof.

[0080] FIG. 5 is a perspective view of one embodiment of the vane 120 of FIGS. 1-3, in which multiple fluid injectors 246 are positioned a constant axial distance 308 from the leading edge 300, as indicated by dashed line 390. The vane 120 of FIG. 5 is similar to the embodiment of FIG. 4, except that the constant axial distance 308 in FIG. 5 is smaller than the constant axial distance 308 in FIG. 4. In particular, the constant axial distance 308 (e.g., dashed line 390) to the multiple fluid injectors 246 in FIG. 5 is approximately midway between the leading edge 300 and the trailing edge 302 of the vane 120. For example, the constant axial distance 308 may be approximately 30-70%, 40-60%, or 50% of the axial length 310 from the leading edge 300 to the trailing edge 302. The vanes 120 with fluid injectors 246 located along dashed line 390 in Figure 5 may be used with one or more of the vanes 120 with variable injection locations 296 as shown in Figure 2, or with each of the vanes 120 with constant injection locations 350 in Figure 3. In certain embodiments, the fluid injectors 246 in Figure 5 may vary from one another along dashed line 390 or remain the same. For example, the fluid injectors 246 may be the same or different from one another with respect to cross-sectional area 382, ​​angle 314 of injection axis or direction 312, geometric shape or geometry, fluid flow rate, type of fluid injected, or any combination thereof.

[0081] FIG. 6 is a perspective view of one embodiment of the vane 120 of FIGS. 1-3 in which multiple fluid injectors 246 are positioned a constant axial distance 308 from the leading edge 300, as indicated by dashed line 400. The vane 120 of FIG. 6 is similar to the embodiment of FIGS. 4 and 5. However, the constant axial distance 308 in FIG. 6 is smaller than the constant axial distance 308 in FIGS. 4 and 5. Notably, the constant axial distance 308 (e.g., dashed line 400) to the multiple fluid injectors 246 in FIG. 6 is directly along, adjacent to, and / or parallel to the leading edge 300 of the vane 120. For example, in the illustrated embodiment, the constant axial distance 308 can be 0-50%, 0-40%, 0-30%, 0-20%, or 0-10% of the axial length 310 from the leading edge 300 to the trailing edge 302. A vane 120 with a fluid injector 246 located along dashed line 400 in Figure 6 may be used with one or more of the vanes 120 with variable injection locations 296 in Figure 2 or with each of the vanes 120 with constant injection locations 350 in Figure 3. In certain embodiments, the fluid injectors 246 in Figure 6 may vary from one another along dashed line 400 or remain the same. For example, the fluid injectors 246 may be the same or different from one another with respect to cross-sectional area 382, ​​angle 314 of injection axis or direction 312, geometric shape or geometry, fluid flow rate, type of fluid injected, or any combination thereof.

[0082] 7 is a perspective view of one embodiment of the vane 120 of FIGS. 1-3 , in which multiple fluid injectors 246 are positioned at a variable axial distance 308 from the leading edge 300 along a variable dashed line 410. For example, the variable dashed line 410 may include one or more of a curved line, a zigzag or wavy line, a slanted line, or any combination thereof, where the variable dashed line 410 indicates (or follows) the change in the axial distance 308 relative to the leading edge 300. For example, the variable dashed line 410 may alternately rotate (e.g., curve) in opposite axial directions in a uniform (e.g., sinusoidal) or non-uniform (e.g., irregular) manner to define the variable axial distance 308 to the fuel injectors 246.

[0083] Thus, the fluid injectors 246 are not positioned at a common axial distance 308 from the leading edge 300, but rather the axial distance 308 of the fluid injectors 246 may vary over an axial range 412 relative to the axial length 310 from the leading edge 300 to the trailing edge 302 of the vane 120. The axial range 412 may be 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% or more of the axial length 310 between the leading edge 300 and the trailing edge 302. In the illustrated embodiment, the axial range 412 of the fluid injectors 246 is positioned at a trailing edge portion 414 of the vane 120. The trailing edge portion may include the area between the trailing edge 302 of the vane 120 and approximately 10, 20, or 30% of the axial length 310 of the vane 120. During operation, varying the axial distance 308 of the fluid injector 246 over the axial range 412 may provide axial variation to facilitate variable heat release or combustion location 320, as described above with reference to Figures 2 and 3.

[0084] The vanes 120 with fluid injectors 246 located along the variable dashed line 410 in FIG. 7 may be used on one or more of the vanes 120 with variable injection locations 296 as shown in FIG. 2. In some embodiments, the vanes 120 with fluid injectors 246 located along the variable dashed line 410 in FIG. 7 may be used on all of the vanes 120 in FIG. 3. As a result, although each vane 120 has variations, the vanes 120 are the same throughout the circumferential arrangement 274. In certain embodiments, the fluid injectors 246 in FIG. 7 may vary from one another along the variable dashed line 410 or remain the same. For example, the fluid injectors 246 may be the same or different from one another with respect to cross-sectional area 382, ​​angle 314 of injection axis or direction 312, geometric shape or geometry, fluid flow rate, type of fluid injected, or any combination thereof.

[0085] Figure 8 is a perspective view of one embodiment of the vane 120 of Figures 1-3, in which multiple fluid injectors 246 are positioned along a variable dashed line 420 at a variable axial distance 308 from the leading edge 300. The variable dashed line 420 in Figure 8 may vary in the same or similar manner as the variable dashed line 410 in Figure 7, however, the variable dashed line 420 is positioned upstream of the variable dashed line 410 in Figure 7. For example, the variable dashed line 420 may be rotated (e.g., curved) in alternating opposite axial directions in a uniform (e.g., sinusoidal) or non-uniform (e.g., irregular) manner to define the variable axial distance 308 to the fuel injectors 246. In the illustrated embodiment, variable dashed line 420 extends over an axial range 422 between leading edge 300 and trailing edge 302, which may be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% or more of axial length 310 between leading edge 300 and trailing edge 302. For example, axial range 422 may be the same as axial range 412 in FIG. 7 and variable dashed line 420 may be the same shape as variable dashed line 410 in FIG. 7. However, axial range 422 and variable dashed line 420 may differ from the embodiment of FIG. 7.

[0086] As discussed above with reference to Figure 7, the vanes 120 of Figure 8 may be used for one or more of the vanes 120 having variable injection locations 296 of Figure 2, or the vanes 120 of Figure 8 may be used for all of the vanes 120 in the circumferential arrangement 274 of Figure 3. In certain embodiments, the fluid injectors 246 of Figure 8 may vary from one another along the variable dashed line 420 or remain the same. For example, the fluid injectors 246 may be the same or different from one another with respect to cross-sectional area 382, ​​angle 314 of injection axis or direction 312, geometric shape or geometry, fluid flow rate, type of fluid injected, or any combination thereof.

[0087] Figure 9 is a perspective view of one embodiment of the vane 120 of Figures 1-3, in which multiple fluid injectors 246 are positioned along a variable dashed line 430 at a variable axial distance 308 from the leading edge 300. The variable dashed line 430 in Figure 9 may vary in the same or similar manner as the variable dashed line 410 in Figure 7 and / or the variable dashed line 420 in Figure 8, however, the variable dashed line 430 is positioned upstream from the variable dashed lines 410 and 420 in Figures 7 and 8. For example, the variable dashed line 430 may be rotated (e.g., curved) in alternating opposite axial directions in a uniform (e.g., sinusoidal) or non-uniform (e.g., irregular) manner to define the variable axial distance 308 to the fuel injectors 246. The plurality of fluid injectors 246 are disposed along a variable dashed line 430 over an axial extent 432 that may be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% or more of the axial length 310 between the leading edge 300 and the trailing edge 302. In the illustrated embodiment, the axial extent 432 of the plurality of fluid injectors 246 is disposed at a leading edge portion 434 of the vane 120. The leading edge portion 434 may extend between the leading edge 300 and approximately 10%, 20%, or 30% of the axial length 310.

[0088] 2, the vanes 120 of FIG. 9 may be used for one or more of the vanes 120 in the variable injection locations 296, or the vanes 120 of FIG. 9 may be used for all of the vanes 120 in the circumferential arrangement 274. In certain embodiments, the fluid injectors 246 of FIG. 9 may vary from one another along the variable dashed line 430 or may remain the same. For example, the fluid injectors 246 may be the same or different from one another with respect to the cross-sectional area 382, ​​the angle 314 of the injection axis or direction 312, the geometric shape or geometry, the fluid flow rate, the type of fluid injected, or any combination thereof.

[0089] 10, 11, and 12 are perspective views of the vane 120 of FIGS. 1-3, with multiple fluid injectors 246 having different cross-sectional areas 382. For example, the cross-sectional area 382 of the fluid injector 246 of FIG. 10 is larger than the cross-sectional area 382 of the fluid injector 246 of FIGS. 11 and 12, which in turn is larger than the cross-sectional area 382 of the fluid injector 246 of FIG. 11. As shown in FIG. 10, the fluid injector 246 is positioned an axial distance 308 from the leading edge 300, as indicated by dashed line 440, which can be constant or variable, as discussed in detail above with reference to FIGS. 4-9. Similarly, fluid injector 246 in Figure 11 is positioned at an axial distance 308 from leading edge 300, as indicated by dashed line 450, which may be fixed or variable, as described in detail above with reference to Figures 4-9. Finally, fluid injector 246 in Figure 12 is positioned at an axial distance 308 from leading edge 300, as indicated by dashed line 460, which may be fixed or variable, as described above with reference to Figures 4-9.

[0090] In each of the vanes 120 of Figures 10, 11, and 12, the fluid injectors 246 may have common or different geometries, such as circular, elliptical, square, polygonal, triangular, or any combination thereof. Also, the fluid injectors 246 of Figures 10, 11, and 12 may have common or different angles 314 of fluid injection axis or direction 312, constant or variable flow rates, constant or variable types of fluid injected, or any combination thereof. The vanes 120 of Figures 10, 11, and 12 may be used alone or in combination with each other in the variable injection system 270 of Figures 2 and 3.

[0091] 4-12 may be used independently or in combination with one another for the vanes 120 in the turbine vane set 248. Additionally, the fuel injector 246 may include any number and types of variations in the axial 30, radial 32, and circumferential 34 directions to vary the heat release, or combustion, at the turbine blades 118 of the turbine blade sets 140 and 142 within the turbine stage expansion to help provide an isothermal expansion within the turbine stage 122 (e.g., common turbine stage 252). For example, the number of variations may be 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 75, 100, or more. For example, the types of variations may include the axial distance 308, the cross-sectional area 382, ​​the angle 314 of the injection axis or direction 312, the geometric shape or geometry, the fluid flow rate, the type of fluid injected, or any combination thereof. Further details of the fluid injectors 246 may also be used in combination with the vanes 120 described in detail above with reference to Figures 1-12. For example, as described in detail below, each of the fluid injectors 246 may include one or more fluid injection ports in various arrangements, one or more angles 314 of the fluid injection axis or direction 312, one or more internal geometries that accelerate or direct the flow from the fluid injector 246, or any combination thereof.

[0092] FIG. 13 is a schematic diagram of one embodiment of the isothermal expansion system 18 of FIGS. 1-12 , further illustrating one embodiment of the fluid injector 246 as a multi-fluid injector 470. In the illustrated embodiment, the multi-fluid injector 470 may have a body 472. The body 472 may be part of the vane body 370 of the vane 120 as described above, or may be located in a receptacle within the vane 120. The body 472 includes a fluid passage 474 disposed longitudinally along a central axis 476, a wall 478 disposed circumferentially about the fluid passage 474 and the central axis 476 to define the fluid passage 474, a fluid passage 480 disposed circumferentially about the wall 478, a wall 482 disposed circumferentially about the fluid passage 480 to define the fluid passage 480, a fluid passage 484 disposed circumferentially about the wall 482, and a wall 486 disposed circumferentially about the fluid passage 484 to define the fluid passage 484. Walls 478, 482, 486 may be concentric annular walls disposed about central axis 476, such that fluid passage 474 is a cylindrical passage centered along central axis 476, fluid passage 480 is an annular passage concentric with fluid passage 474, and fluid passage 484 is an annular passage concentric with fluid passages 480 and 474. In certain embodiments, fluid passage 480 may include multiple passages circumferentially spaced about central axis 476, fluid passage 484 may include multiple passages circumferentially spaced about central axis 476, or combinations thereof. Generally, fluid passage 480 is disposed between fluid passages 474 and 484, thus separating the fluid flows.

[0093] The multi-fluid injectors 470 are configured to inject oxidizer from the oxidizer supply system 92, barrier fluid from the fluid supply system 94, and fuel from the fuel supply system 90. In certain embodiments, the isothermal expansion system 18 routes the oxidizer, barrier fluid, and fuel to the respective fluid passages 474, 480, and 484 of the multi-fluid injectors 470 via distribution through the distribution system 240 and the fluid manifold(s) 242 as described above. For example, the controller 220 may be configured to control the oxidizer supply system 92, the fluid supply system 94, the fuel supply system 90, the distribution system 240, the fluid manifold(s) 242, and various flow control components to adjust the fluid flow rate, pressure, fluid flow direction, fluid composition, or any combination thereof to and through the multi-fluid injectors 470 at one or more positions within each vane 120.

[0094] In certain embodiments, isothermal expansion system 18 may be configured to selectively reroute the oxidant flow, the barrier fluid flow, and the fuel flow to different passages 474, 480, and 484 of multi-fluid injector 470. For example, in some embodiments, controller 220 may control distribution system 240, fluid manifold 242, and various flow control components (e.g., valves) to direct the fuel flow to fluid passage 474, the barrier fluid flow to fluid passage 480, and the oxidant flow to fluid passage 484, such that the barrier fluid flow is disposed between the fuel and oxidant flows. Similarly, controller 220 may control distribution system 240, fluid manifold 242, and various flow control components to direct the oxidant flow to fluid passage 474, the barrier fluid flow to fluid passage 480, and the fuel flow to fluid passage 484, such that the barrier fluid flow is disposed between the oxidant and fuel flows.

[0095] In either case, a barrier fluid flow is output by the multi-fluid injectors 470 between the fuel and oxidant flows, thereby delaying mixing of the oxidant and fuel flows an axial distance downstream of the multi-fluid injectors 470. In certain embodiments, the isothermal expansion system 18 is configured to control the fluid flow rates of the oxidant, barrier fluid, and fuel, whereby the barrier fluid delays mixing of the oxidant and fuel flows a variable axial distance downstream of the multi-fluid injectors 470, helping to facilitate variable heat release or combustion locations 320, as described in detail above with reference to FIGS. 2 and 3. Thus, the isothermal expansion system 18 may differentially control the fluid flow (e.g., oxidant, barrier fluid, and fuel) through different multi-fluid injectors 470 on the same or different vanes 120, thereby varying the axial distance to heat release or combustion along the turbine blades 118 within the turbine stage expansion to help provide an isothermal expansion through the turbine stage 122 (e.g., common turbine stage 252).

[0096] Figure 14 is a cross-sectional view of multi-fluid injector 470 of Figure 13 taken along line 14-14 and further illustrates the geometry of fluid passages 474, 480, 484 and walls 478, 482, and 486. As shown in Figure 14, walls 478, 482, and 486 are annular walls disposed in a concentric arrangement about central axis 476. Similarly, fluid passages 474, 480, and 484 are disposed in a concentric arrangement about central axis 476, where fluid passage 474 is a cylindrical passage, fluid passage 480 is an annular passage disposed between annular walls 478 and 482, and fluid passage 484 is an annular passage disposed between annular walls 482 and 486.

[0097] In the illustrated embodiment, fluid passage 474 may be configured to inject fuel from fuel supply system 90, fluid passage 480 may be configured to inject barrier fluid from fluid supply system 94, and fluid passage 484 may be configured to inject oxidizer from oxidizer supply system 92. However, in other embodiments, fluid may be rerouted through fluid passages 474, 480, and 484. For example, fluid passage 474 may be configured to inject oxidizer from oxidizer supply system 92, fluid passage 480 may be configured to inject barrier fluid from fluid supply system 94, and fluid passage 484 may be configured to inject fuel from fuel supply system 90. The oxidizer may include oxygen, air, hypoxic air, oxygen-enriched air, or any combination thereof. The barrier fluid may include an inert gas such as nitrogen, exhaust gas (e.g., exhaust gas from stoichiometric combustion), low-oxygen air (e.g., exhaust gas from non-stoichiometric combustion), carbon dioxide or other capture gas from carbon capture system 192, or other suitable fluid to prevent mixing of the fuel and oxidizer and retard combustion.

[0098] 13 and 14, walls 478, 482, 486 terminate at a common axial location or plane 488 along central axis 476. However, in certain embodiments, walls 478, 482, and 486 may be axially staggered relative to one another along central axis 476 to control the injection location and delay mixing of the oxidizer and fuel flows from multi-fluid injector 470. Again, multi-fluid injector 470 may be used in each of fluid injectors 246 in vane 120 to help control the variable heat release, or combustion location 320, in turbine blade sets 140 and 142 of circumferential locations 278 and 282 of blades 118.

[0099] FIG. 15 is a cross-sectional view of one embodiment of the fluid injector 246 of FIGS. 1-12 , further illustrating a fluid passage 500 having a converging-diverging passage geometry 502. The fluid passage 530 may be a fuel passage, an oxidant passage, or a barrier fluid passage. As shown, the fluid passage 500 is disposed within a body 504, which may be part of the vane body 370 of the vane 120 as described above. However, the body 504 may be fixedly or removably attached to a receptacle within the vane 120. The fluid passage 500 extends through the body 504 in a flow direction 510 along an axis 512 from an inlet 506 to an outlet 508. In the illustrated embodiment, the converging-diverging passage geometry 502 of the fluid passage 500 includes a convergent passage 514 disposed at the inlet 506, a diverging passage 516 disposed at the outlet 508, and a throat 518 between the convergent passage 514 and the diverging passage 516. Converging-diverging passage geometry 502 may be symmetrical about axis 512. For example, convergent passage 514 may include an annular converging passage that converges toward axis 512 along a straight or curved profile 520, while diverging passage 516 may be an annular diverging passage that diverges away from axis 512 along a straight or curved profile 520 (e.g., an inner annular surface profile). For example, profile 520 may be defined by a conical surface and / or a curved annular surface. Throat 518 may be a circular or cylindrical throat that defines a minimum cross-sectional area along convergent-divergent passage geometry 502.

[0100] In certain embodiments, the convergent passages 514 are configured to accelerate the fluid flow along the flow direction 510 toward the outlets 508 of the fluid injectors 246. The particular geometries of the convergent passages 514, divergent passages 516, and throats 518 may be used to control the acceleration of the fluid flow in the downstream direction to facilitate variable heat release or combustion location 320, as described above with reference to Figures 2 and 3. For example, the cross-sectional areas of the fluid passages 500 (e.g., the inlets 506, outlets 508, and throats 518), ratios of the cross-sectional areas, and other characteristics of the fluid passages 500 may be varied from fluid injector 246 to help vary the heat release or combustion location 320 within the turbine stage expansion, thereby helping to provide isothermal expansion across the blades 118 of the turbine stage 122 (e.g., the common turbine stage 252).

[0101] FIG. 16 is a cross-sectional view of one embodiment of the fluid injector 246 of FIGS. 1-12 , further illustrating a fluid passage 530 having a convergent passage geometry 532. The fluid passage 530 may be a fuel passage, an oxidant passage, a barrier fluid passage, or a fluid mixture passage (e.g., a fuel-air mixture passage). As shown, the fluid passage 530 has a convergent passage geometry 532 that penetrates along an axis 540 in a flow direction 538 from an inlet 534 to an outlet 536. The convergent passage geometry 532 may include an annular convergent passage geometry, where the convergent passage geometry 532 gradually converges toward the axis 540 in a linear or curved manner, as indicated by a profile 542 (e.g., an inner annular surface profile). In certain embodiments, the linear profile 542 may include one or more angles relative to the axis 540, thereby gradually converging the fluid flow in the flow direction 510 toward the outlet 536. 15 , the convergent passage geometry 532 may be configured to accelerate the fluid flow in a flow direction 538 toward the turbine blades 118 to provide a variable heat release or combustion location 320, as described in detail above with reference to FIGS. 2 and 3 . For example, the cross-sectional areas of the fluid passages 530 (e.g., at the inlet 534, outlet 536, and intermediate locations), ratios of the cross-sectional areas, and other characteristics of the fluid passages 530 may be varied from fluid injector 246 to help vary the heat release or combustion location 320 within the turbine stage expansion, thereby helping to provide an isothermal expansion across the blades 118 of a turbine stage 122 (e.g., common turbine stage 252).

[0102] 17 is a cross-sectional view of the multi-fluid injector 470 of FIGS. 13 and 14 , further illustrating the convergent passage geometries 550, 552, and 554 in the fluid passages 474, 480, 484, respectively. In particular, the fluid passage 474 has a convergent passage geometry 550 configured to converge toward the central axis 476 in the flow direction 556, the passage 480 has a convergent passage geometry 552 configured to converge the passage in the flow direction 556, and the passage 484 has a convergent passage geometry 554 configured to converge the passage in the flow direction 556. Thus, the passage 474 may be a conical flow path that converges from the inlet 558 to the outlet 560, the passage 480 may be a convergent annular flow path extending from the inlet 562 to the outlet 564, and the passage 484 may be a convergent annular flow path extending from the inlet 566 to the outlet 568. 13 and 14 , the outlets 560, 564, and 568 may be positioned along a common axial location or plane 488, or the outlets 560, 564, 568 may be axially staggered relative to one another via the axial staggering of the walls 478, 482, and 486. The illustrated multi-fluid injector 470 may be used for one or more of the fluid injectors 246 on the vane 120, alone or in combination with the multi-fluid injectors 470 of FIGS. 13 and 14 , the convergent-divergent passage geometry 502 of FIG. 15 , the convergent passage geometry 532 of FIG. 16 , or additional passage geometries described in more detail below, to help provide variable heat release, i.e., combustion location 320, and isothermal expansion across the blades 118 in the turbine stage 122 (e.g., common turbine stage 252).

[0103] FIG. 18 is a cross-sectional view of one embodiment of the fluid injector 246 of FIGS. 1-17 , further illustrating that the angle 314 of the fluid injection axis or direction 312 is approximately 90 degrees relative to a surface 580 at an outlet 582 of a fluid passageway 584 through a body 586. The body 586 may be part of the vane body 370 of the vane 120, as detailed above. However, in certain embodiments, the body 586 may be fixedly or removably coupled to the vane 120 via a receptacle in the vane body 370. The fluid passageway 584 extends through the body 586 from an inlet 588 to an outlet 582. The fluid passageway 584 is generally aligned or coaxial with an axis 590 through the body 586, with the axis 590 and the fluid injection axis or direction 312 disposed at an angle 314 relative to the surface 580, which may correspond to a surface along the vane 120. As detailed above, the angle 314 may be the same or vary between different fluid injectors 246 on each vane 120, or between different vanes 120 within the circumferential arrangement 274 of vanes 120 in a turbine vane set 248. Thus, while the angle 314 in FIG. 18 is approximately 90 degrees, the angle 314 may vary for other fluid injectors 246. The variable angle 314 between the fluid injectors 246 and / or vanes 120 may be configured to help vary the heat release or combustion location 320 within the turbine stage expansion, thereby helping to provide an isothermal expansion across the blades 118 of a turbine stage 122 (e.g., common turbine stage 252).

[0104] 1-17 , further illustrating the angle 314 of the fluid injection axis or direction 312 as an acute angle relative to the surface 598 of the body 600. In the illustrated embodiment, the fluid injector 246 has a fluid passageway 602 extending through the body 600 from an inlet 604 to an outlet 606 at the surface 580, which may be part of the vane body 370 or may be attached to a receptacle in the vane body 370, as described above. The fluid passageway 602 may include a passageway 608 followed by a passageway 610, which extends from the inlet 604 to the passageway 610, which extends to the outlet 606. The passageway 608 may be approximately perpendicular to the surface 580, while the passageway 610 may be oriented at an angle 314 such that the fluid injection axis or direction 312 extends at an angle relative to the surface 580 (e.g., relative to a tangent to the surface 580 at the outlet 606). For example, the angle 314 may be between 0 and 90 degrees, between 10 and 80 degrees, between 20 and 70 degrees, between 30 and 60 degrees, or between 40 and 60 degrees. In the illustrated embodiment, the angle 314 is an acute angle. A fluid injector 246 having an angle 314 of the passageway 610 leading to the outlet 606 may be used for one or more of the fluid injectors 246 on one or more vanes 120, as described in detail above.

[0105] 20 is a cross-sectional view of one embodiment of the fluid injector 246 of FIGS. 1-17 , further illustrating the angle 314 of the fluid injection axis or direction 312 as an acute angle relative to the surface 620 of the body 622. The fluid injector 246 includes a fluid passageway 624 extending through the body 622 from an inlet 626 to an outlet 628 along the surface 620, the fluid passageway 624 including a passageway 630 followed by passageways 632 and 634. The passageway 630 extends from the inlet 626 to the passageway 632, the passageway 632 extends from the passageway 630 to the passageway 634, and the passageway 634 extends from the passageway 632 to the outlet 628. Each of the passageways 630, 632, and 634 may have a constant or variable cross-sectional area along the axis 590. For example, one or more of passages 630, 632, or 634 may include a converging passage or a diverging passage, as described above with reference to Figures 15-17. In the illustrated embodiment, passage 634 includes a converging passage (e.g., a conical passage) that converges in the flow direction toward outlet 628.

[0106] Passages 630, 632, and 634 may gradually change angle until they reach surface 620, thereby defining angle 314 of fluid injection axis or direction 312. In the illustrated embodiment, angle 314 may be 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, or 30 degrees or less relative to surface 620 (e.g., relative to a tangent to surface 620 at outlet 628). Furthermore, angle 314 of fluid injector 246 in FIG. 20 is less than angle 314 of fluid injector 246 in FIGS. 18 and 19, which in turn is less than angle 314 of fluid injector 246 in FIG. 18. Thus, various angles 314 may be used for fluid injectors 246 on each vane 120 and / or for each vane 120 within circumferential arrangement 274 of vanes 120 in turbine vane set 248. 18-20 (including any number of different angles 314) may be used in combination with various fluid injector 246 features described herein. As described above, the variable angle 314 of the fluid injector 246 may be configured to help control or vary the heat release or combustion location 320 along the blades 118 at the turbine blade sets 140 and 142 within the turbine stage expansion, thereby helping to provide isothermal expansion across the blades 118 of the turbine stage 122 (e.g., common turbine stage 252).

[0107] 21-26 are perspective views of one embodiment of the blade 118 of FIGS. 1-3 , further illustrating details of the flame stabilizer 250 of the variable stabilizer system 272. The flame stabilizer 250 includes structural features configured to help retain and / or stabilize the flame (and thus the heat release from combustion) at specific locations (e.g., axial and radial locations) along the turbine blade 118. Before addressing each embodiment of FIGS. 21-26 , various aspects of the blade 118 are described below. As illustrated, the blade 118 includes a blade body 650 that extends from a base 652 in the radial direction 32 to a tip 654. The blade body 650 has a cross-sectional area 656 that can be constant or variable in the radial direction 32 from the base 652 to the tip 654. For example, in certain embodiments, the cross-sectional area 656 gradually decreases in the radial direction 32 from the base 652 to the tip 654. Blade body 650 is further defined by leading edge 326, trailing edge 328, pressure side 330, and suction side 332. A cross-sectional area 656 is bounded by pressure side 330 and suction side 332 and may define an airfoil geometry. As described above, blade 118 has an axial length 336 that extends from leading edge 326 to trailing edge 328. Axial length 336 may vary from base 652 to tip 654 depending on whether cross-sectional area 656 is constant or variable from base 652 to tip 654.

[0108] Variable stabilizer system 272 includes flame stabilizers 250 arranged at one or more locations along blade 118, such as arranged radially 32 and axially 30 along pressure face 330 between leading edge 326 and trailing edge 328. Each flame stabilizer 250 may include one or more protrusions 660 and / or recesses 662 arranged in separate or overlapping positions relative to one another. For example, in the illustrated embodiment, each flame stabilizer 250 may include a protrusion 660 arranged within a recess 662 along a surface 664, such as pressure face 330, of blade body 650. The protrusions 660 and recesses 662 may have various shapes and dimensions in the axial, radial, and circumferential directions 30, 32, and 34. In the illustrated embodiment, recesses 662 have an elongated elliptical geometry 666, and protrusions 660 have a curved or C-shaped geometry 668. However, as will be described in further detail below, the geometry of the protrusions 660 and recesses 662 may vary between the flame stabilizers 250 on each blade 118 and between different blades 118. Also, to facilitate the variable heat release, i.e., combustion location 320, and isothermal expansion described above with reference to Figures 2-3, the variable stabilizer system 272 has flame stabilizers 250 at various locations along the blade 118, as shown in Figures 21-26. The differences between the embodiments of Figures 21-26 are described in further detail below.

[0109] 21 is a perspective view of one embodiment of the blade 118 of FIGS. 1-3 , further illustrating details of the variable stabilizer system 272 in which the flame stabilizers 250 are positioned at a constant axial distance 334 from the leading edge 326, as indicated by dashed line 670. Dashed line 670 generally extends in the radial direction 32 parallel to the leading edge 326 such that each flame stabilizer 250 is positioned the same axial distance 334 from the leading edge 326. In various embodiments, the flame stabilizers 250 can have the same or different geometries for the protrusions 660 and recesses 662. In the illustrated embodiment, the variable stabilizer system 272 includes multiple flame stabilizers 250 at different radial distances 672 from the base 652 in the radial direction 32. For example, the radial distance 672 may be in the range of 0-100%, 10-90%, 20-80%, 30-70%, and 40-60% of the overall radial length 674 from the base 652 to the tip 654 of the blade 118, or any other suitable range or percentage.

[0110] Flame stabilizers 250 may be evenly or unevenly spaced from one another in radial direction 32. In the embodiment of FIG. 21 , axial distance 334 may be measured between leading edge 326 and the center of flame stabilizer 250, as shown by dashed line 670. Thus, axial distance 334 may be between 0-50%, 0-40%, 0-30%, 0-20%, and 0-10% of axial length 336 between leading edge 326 and trailing edge 328. For example, flame stabilizer 250 along dashed line 670 may be positioned at leading edge portion 676 of blade 118, which may correspond to a portion of blade 118 between leading edge 326 and approximately 10%, 20%, or 30% of axial length 336.

[0111] FIG. 22 is a perspective view of one embodiment of the blade 118 of FIGS. 1-3 , further illustrating details of the variable stabilizer system 272 with the flame stabilizers 250 positioned at a common axial distance 334 from the leading edge 326, as indicated by dashed line 690. In the illustrated embodiment, the flame stabilizers 250 may have substantially the same characteristics as described above with reference to FIG. 21 , but the axial distance 334 along dashed line 690 is further downstream from the leading edge 326 compared to FIG. 21 . For example, in the illustrated embodiment, the axial distance 334 along dashed line 690 may be 20-80%, 30-70%, 40-60%, or approximately 50% of the axial length 336 between the leading edge 326 and the trailing edge 328. Again, the flame stabilizers 250 may have the same or different geometries for the protrusions 660 and recesses 662. Flame stabilizers 250 may be positioned at similar radial distances 672 in radial direction 32 as described above with reference to Figure 21. However, in certain embodiments, the radial distances 672 of flame stabilizers 250 may differ from the radial distances of flame stabilizers 250 of Figure 21.

[0112] 23 is a perspective view of one embodiment of the blade 118 of FIGS. 1-3 , further illustrating details of the variable stabilizer system 272 in which the flame stabilizer 250 is positioned a constant axial distance 334 from the leading edge 326, as indicated by dashed line 700. In the illustrated embodiment, the flame stabilizer 250 may have substantially the same characteristics as described above with reference to FIG. 21 , but the axial distance 334 along dashed line 700 is further downstream from the leading edge 326 compared to FIGS. 21 and 22 . For example, in the embodiment of FIG. 23 , the flame stabilizer 250 along dashed line 700 may be positioned at a trailing edge portion 702 of the blade 118, which may be positioned between the trailing edge 328 and approximately 10%, 20%, or 30% of the axial length 336 from the trailing edge 328. In certain embodiments, axial distance 334 can be approximately 50-100%, 60-100%, 70-100%, 80-100%, or 90-100% of axial length 336 of blade 118. As with the embodiment of FIGS. 21 and 22 , dashed line 700 extends in radial direction 32, and flame stabilizers 250 can be positioned at different radial distances 672 along radial length 674 of blade 118. Radial distance 672 can be the same or different from radial distance 672 of flame stabilizer 250 shown in FIGS. 21 and 22 .

[0113] Flame stabilizers 250 having constant axial distances 334 along dashed lines 670, 690, and 700 in Figures 21, 22, and 23 may be used individually or in combination with each other on blades 118 in circumferential arrangements 278 and 282 in Figures 2 and 3. Flame stabilizers 250 may be arranged in other arrangements in combination with the arrangements shown in Figures 21, 22, and 23. Also, flame stabilizers 250 may be coupled to blades 118 at any number of axial and radial positions, such as at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 100, 200, or more axial and radial positions. The different positions of the flame stabilizer 250 help vary the heat release or combustion location 320 along the blades 118 at the turbine blade sets 140 and 142 within the turbine stage expansion, thereby helping to provide isothermal expansion across the blades 118 within the turbine stage 122 (e.g., common turbine stage 252).

[0114] 24, 25, and 26 are perspective views illustrating embodiments of blade 118 having a variable axial distance 334 from leading edge 326 to flame stabilizer 250, with each subsequent embodiment shown with flame stabilizer 250 offset further from leading edge 326. For example, FIG. 24 is a perspective view of blade 118 of FIGS. 1-3 illustrating variable stabilizer system 272 with flame stabilizer 250 positioned at a variable axial distance 334, as indicated by variable dashed line 710. Variable dashed line 710 generally extends radially 32 while varying axially 30. Thus, axial distance 334 from leading edge 326 to flame stabilizer 250 varies for each flame stabilizer 250 along variable dashed line 710. In the illustrated embodiment, the flame stabilizer 250 having the variable axial distance 334 is generally positioned at the leading edge portion 676 of the blade 118. For example, the flame stabilizer 250 may be positioned along the variable dashed line 710 (e.g., centered along the variable dashed line) over an axial range 712 of approximately 5-100%, 10-90%, 20-80%, 30-70%, or 40-60% of the axial length 336 between the leading edge 326 and the trailing edge 328.

[0115] Variable dashed line 710 may include one or more of a curved line, a zigzag or wavy line, a slanted line, or any combination thereof, where variable dashed line 710 indicates (or follows) the change in axial distance 334 relative to leading edge 326. For example, variable dashed line 710 may alternately rotate (e.g., curve) in opposite axial directions in a uniform (e.g., sinusoidal) or non-uniform (e.g., irregular) manner to define variable axial distance 334 to flame stabilizer 250. Thus, variable axial distance 334 of flame stabilizer 250 may be located anywhere between leading edge 326 and trailing edge 328. However, in the illustrated embodiment, flame stabilizer 250 along variable dashed line 710 is generally located at leading edge portion 676.

[0116] Figure 25 is a perspective view of one embodiment of blade 118 of Figures 1-3, further illustrating details of variable stabilizer system 272 in which flame stabilizer 250 is positioned at a variable axial distance 334, as indicated by variable dashed line 720. Variable dashed line 720 in Figure 25 may vary in the same or similar manner as variable dashed line 710 in Figure 24, except that variable dashed line 720 is positioned downstream from variable dashed line 710 in Figure 24. For example, variable dashed line 720 may alternately rotate (e.g., curve) in opposite axial directions in a uniform (e.g., sinusoidal) or non-uniform (e.g., irregular) manner to define variable axial distance 334 to flame stabilizer 250. Additionally, flame stabilizer 250 may be positioned (e.g., centered) along variable dashed line 720 over an axial range 722 that may be at least approximately 5-100%, 10-90%, 20-80%, 30-70%, or 40-60% of axial length 336 between leading edge 326 and trailing edge 328. In the illustrated embodiment, flame stabilizer 250 is positioned along variable dashed line 720 in an intermediate region approximately halfway between leading edge 326 and trailing edge 328.

[0117] Figure 26 is a perspective view of one embodiment of blade 118 of Figures 1-3, further illustrating details of variable stabilizer system 272 in which flame stabilizer 250 is positioned at a variable axial distance 334, as indicated by variable dashed line 730. Variable dashed line 730 in Figure 26 may vary in the same or similar manner as variable dashed lines 710 and 720 in Figures 24 and 25, but variable dashed line 730 is positioned downstream from variable dashed lines 710 and 720 in Figures 24 and 25. For example, variable dashed line 730 may be rotated (e.g., curved) in alternating opposite axial directions in a uniform (e.g., sinusoidal) or non-uniform (e.g., irregular) manner to define variable axial distance 334 to flame stabilizer 250. Flame stabilizer 250 may be positioned (e.g., centered) along variable dashed line 730 over an axial range 732 that may be at least approximately 5-100%, 10-90%, 20-80%, 30-70%, or 40-60% of axial length 336 between leading edge 326 and trailing edge 328. In the illustrated embodiment, flame stabilizer 250 along dashed line 730 is generally positioned at trailing edge portion 702 of blade 118 such that flame stabilizer 250 may be between trailing edge 328 and approximately 10%, 20%, or 30% of axial length 336.

[0118] As shown in Figures 24, 25, and 26, flame stabilizers 250 may have the same geometry and configuration at each blade 118 and at each location. However, in certain embodiments, flame stabilizers 250 may be constant or variable in geometry, angle, spacing, or any combination thereof between flame stabilizers 250 and blades 118. Variable stabilizer system 272 may have flame stabilizers 250 in any of the arrangements shown in Figures 21-26 used alone or in combination with each other on blades 118 in circumferential arrangements 278 and 282 of Figures 2 and 3. The variability in the arrangement and configuration of flame stabilizers 250 is configured to help provide variable heat release, i.e., combustion location 320, which in turn helps to provide isothermal expansion across blades 118 of turbine stage 122 (e.g., common turbine stage 252). In embodiments having two turbine blade sets 140, 142, the flame stabilizer in the first blade set 140 may be the same as or different from the flame stabilizer in the second blade set 142.

[0119] As mentioned above, flame stabilizer 250 may be used alone or in combination with various aspects of variable injection system 270, which may include variable injection location 296 of FIG. 2 , constant injection location 350 of FIG. 3 , geometry type, flow rate, angle 314, multi-fluid injector 470, or any combination thereof. Each of the features of variable injection system 270 and variable stabilizer system 272 are configured to help provide isothermal expansion across blades 118 within turbine stage 122 (e.g., common turbine stage 252). FIGS. 27-32 illustrate embodiments of flame stabilizer 250 that may be used in any combination with variable injection system 270 and variable stabilizer system 272 detailed above.

[0120] FIG. 27 is a top view of one embodiment of the flame stabilizer 250 of FIGS. 1-3 and 21-26, further illustrating details of the protrusion 660 disposed within a recess 662 in a surface 664 of the blade 118. As shown, the recess 662 has an elongated or elliptical geometry 666, while the protrusion 660 has a curved or C-shaped geometry 668. The protrusion 660 may be positioned anywhere within the recess 662, thereby helping to maintain a low profile of the protrusion along the surface 664 of the blade 118. The blade 118 has the flame stabilizer 250 oriented along the flow direction 750, such that the fluid flow in the flow direction 750 extends partially across the recess 662 before reaching the protrusion 660. During operation, the fluid flow in flow direction 750 enters recess 662 and impinges on protrusion 660, which creates a low velocity zone that helps stabilize or maintain the flame at a location along blade 118 and controls the location (e.g., axial and radial location) of heat release from combustion along blade 118.

[0121] The recess 662 has an elongated or elliptical geometry 666 that may include an upstream edge 752, a downstream edge 754, and opposing sides 756 and 758 that extend from the upstream edge 752 to the downstream edge 754. The recess 662 may also have a constant or variable depth between the upstream edge 752 and the downstream edge 754 and between the opposing sides 756 and 758. The protrusion 660 may be positioned a variable or constant distance 760 from the upstream edge 752. For example, the distance 760 may be any percentage of the axial length 762 of the recess 662 between the upstream edge 752 and the downstream edge 754. For example, distance 760 may be in the range of 0-100%, 0-80%, 0-60%, 0-40%, 0-20%, 20-80%, 30-70%, or 40-60% of axial length 762, or any other suitable percentage of axial length 762. Distance 760 may be varied to control the flame stabilization provided by flame stabilizer 250.

[0122] The protrusion 660 has a curved or C-shaped geometry 668 that may include a rear wall 764 connected to opposing side walls 766 and 768. The rear wall 764 and side walls 766 and 768 are arranged about a space 770, while the protrusion 660 has an opening 772 into the space 770 between the opposing side walls 766 and 768. The opening 772 and the space 770 face in an upstream direction opposite to the flow direction 750, thereby directing the fluid flow into the opening 772 and the space 770. The rear wall 764 may be a flat or curved wall, while the side walls 766 and 768 may be sloped, straight, or curved about the space 770. The protrusion 660 may also provide or define a low velocity zone 774 aft or downstream of the rear wall 764 in the flow direction 750 , thereby facilitating flame stabilization of a flame formed adjacent the flame stabilizer 250 .

[0123] The geometry, dimensions, and positioning of recesses 662 and protrusions 660 may facilitate or adjust the position of the flame stabilization provided by flame stabilizer 250. In certain embodiments, recesses 662 and protrusions 660 of flame stabilizer 250 of FIG. 27 may have the same geometry and dimensions, but in different positioning, across multiple flame stabilizers 250 on a particular blade 118 or for different blades 118 in circumferential arrangements 278 and 282 within turbine blade sets 140 and 142. However, the geometry and / or dimensions may also vary between different flame stabilizers 250 on the same or different blades 118, with or without changes in positioning. In certain embodiments, the geometry, dimensions, and positioning of recesses 662 and protrusions 660 may vary between different flame stabilizers 250 on a particular blade 118 or between different blades 118.

[0124] Figure 28 is a cross-sectional view of one embodiment of flame stabilizer 250 of Figure 27, further illustrating details of protrusion 660 and recess 662. As shown in Figure 28, recess 662 has a base or bottom surface 790 with a variable depth 792 between upstream edge 752 and downstream edge 754. In particular, base or bottom surface 790 may curve to the variable depth 792 between upstream edge 752 and downstream edge 754. Protrusion 660 is disposed within recess 662 along base or bottom surface 790, where protrusion 660 extends outward to a height 794 relative to base or bottom surface 790. Height 794 may be equal to depth 792 of recess 662 at location of protrusion 660, or height 794 may be located at a lower height 796 or a higher height 798 relative to the height of a line or contour 800 where surface 664 surrounds recess 662. Thus, in certain embodiments, flame stabilizers 250 may have variable depths 792, variable heights 794, variable distances 760, other variable dimensions and geometries, or any combination thereof, per flame stabilizer 250 to vary the positioning of flame stabilization by flame stabilizer 250 to help distribute the heat release of combustion and provide isothermal expansion across blade 118.

[0125] FIG. 29 is a top view of one embodiment of the flame stabilizer 250 of FIGS. 1-3 and 21-26 , further illustrating details of the protrusion 660 disposed within a recess 662 in a surface 664 of the blade 118. The flame stabilizer 250 is substantially similar to that described above with reference to FIGS. 27 and 28 , with one or more features of the flame stabilizer 250 being variable to help provide isothermal expansion throughout the blade 118. However, the curved or C-shaped geometry 668 of FIG. 29 differs from the embodiment of FIGS. 27 and 28 . The curved or C-shaped geometry 668 of the protrusion 660 in the embodiment of FIG. 29 has a curved or arcuate wall 810 that extends at least partially around the space 812. For example, the C-shaped geometry 668 may exclude flat or straight walls altogether, such that the protrusion 660 is at least substantially or completely defined by the curved or arcuate wall 810. Curved or arcuate wall 810 has an opening 814 to space 812, with opening 814 and space 812 facing in an upstream direction opposite flow direction 750. Downstream of curved or arcuate wall 810, flame stabilizer 250 has a low velocity zone 774 configured to facilitate flame stabilization and heat release at a desired location for isothermal expansion in turbine blade sets 140 and 142. Other aspects of flame stabilizer 250 are as described in detail above.

[0126] Figure 30 is a cross-sectional view of one embodiment of the flame stabilizer 250 of Figure 29, further illustrating the curved or arcuate wall 810 of the protrusion 660 disposed within the recess 662. The recess 662 is substantially similar to that described above with reference to Figures 27 and 28, including a variable depth 792 of the base or bottom surface 790 and a variable height 794 of the protrusion 660. For example, the curved or arcuate wall 810 of the protrusion 660 may be disposed flush or at the same height 794 as the line or contour 800 of the surface 664, or the curved or arcuate wall 810 may be disposed at a lower height 796 or a higher height 798 relative to the line or contour 800. Thus, in certain embodiments, the flame stabilizers 250 may have a variable depth 792, a variable height 794, a variable distance 760, a variable radius of curvature of the curved or arcuate walls 810, other variable dimensions and geometries, or any combination thereof, per flame stabilizer 250, which alters the positioning of the flame stabilization by the flame stabilizers 250 to help distribute the heat release of combustion and provide isothermal expansion across the blade 118.

[0127] FIG. 31 is a top view of one embodiment of the flame stabilizer 250 of FIGS. 1-3 and 21-26 , further illustrating details of the protrusion 660 disposed within a recess 662 in a surface 664 of the blade 118. The flame stabilizer 250 is substantially similar to that described above with reference to FIGS. 27-30 , with one or more features of the flame stabilizer 250 being variable to help provide isothermal expansion across the blade 118. However, whereas the protrusion 660 of the embodiment of FIG. 31 includes a rectangular geometry 820, the protrusion 660 of the embodiment of FIGS. 27-30 includes a different curved or C-shaped geometry 668. As shown, the rectangular geometry 820 of the protrusion 660 includes an upstream flat wall 822, a downstream flat wall 824, and opposing flat sidewalls 826 and 828. Upstream flat wall 822 faces in an upstream direction, opposite flow direction 750, while downstream flat wall 824 faces in a downstream direction, towards low-velocity zone 774. The ratio of the dimensions of flat walls 822 and 824 to side walls 826 and 828 can vary depending on the dimensions of recess 662 and the desired width of low-velocity zone 774. Again, as with the above-described embodiment, distance 760 from upstream edge 752 to rectangular geometry 820 of protrusion 660 can vary for each flame stabilizer 250 on a particular blade 118 or for different blades 118.

[0128] FIG. 32 is a cross-sectional view of one embodiment of the flame stabilizer 250 of FIG. 31 , further illustrating details of the rectangular geometry 820 of the protrusion 660 disposed within the recess 662. The recess 662 is substantially similar to that detailed above with reference to FIGS. 27 and 28 , including a variable depth 792 of the base or bottom surface 790 and a variable height 794 of the protrusion 660. For example, the recess 662 may include a variable depth 792 to the base or bottom surface 790. Furthermore, the protrusion 660 having the rectangular geometry 820 may have a variable height 794 between the base or bottom surface 790 and the line or contour 800, such that the height 794 is the same as or equal to the line or contour 800, or such that the protrusion 660 may have a lower height 796 or a higher height 798 relative to the line or contour 800. The distance 760 between the upstream edge 752 and the protrusion 660 may also vary, as described above. Thus, in certain embodiments, the flame stabilizers 250 may have a variable depth 792, a variable height 794, a variable distance 760, a variable width or length / width ratio of the rectangular geometry 820, other variable dimensions and geometries, or any combination thereof, per flame stabilizer 250, to vary the positioning of the flame stabilization by the flame stabilizers 250, distribute the heat release of combustion, and help provide isothermal expansion across the blade 118.

[0129] 27-32 are examples of different flame stabilizers 250 that may be used alone or in combination with each other on each and / or per blade 118 within variable stabilizer system 272. Thus, flame stabilizers 250 may be coupled to various blades 118 having different geometries, different dimensions, different positioning (e.g., axial and radial positions), or any combination thereof, thereby varying the heat release along turbine blades 118, i.e., the axial distance to combustion, within a turbine stage expansion and helping to provide an isothermal expansion through turbine stage 122 (e.g., common turbine stage 252). Flame stabilizers 250 of variable stabilizer system 272 may be used in any combination with the features of variable injection system 270 detailed above.

[0130] FIG. 33 is a flowchart illustrating one embodiment of a process 840 for operating the gas turbine system 12 with the variable injection system 270 of the isothermal expansion system 18 of FIGS. 1-32 , the process 840 including control via the controller 220. In the illustrated embodiment, the process 840 includes combusting fuel in the combustor 62 of the gas turbine system 12 to generate combustion gases 112 (block 842). The process 840 also includes routing the combustion gases 112 through a turbine stage 252 of the turbine section 46 of the gas turbine system 12 (block 844). The process 840 also includes controlling fluid flow through fluid injectors 246 coupled to turbine vanes 120 of the isothermal expansion system 18 to provide combustion across the turbine blades in the turbine stage 252 (block 846). The process 840 also includes varying the axial position of combustion within the turbine stage expansion to reduce temperature variations across the turbine blades 118 in the turbine stage 252 (block 848). Process 840 also includes controlling the axial range of the axial position of the combustion (block 850) in response to changes in load on gas turbine system 12. The change in axial position (block 848) and the controlled axial range (block 850) may be achieved by controlling variable injection system 270 using controller 220, as detailed above with reference to Figures 2 and 3, and fluid injector 246 may be positioned at variable injection location 296 in Figure 2 or constant injection location 350 in Figure 3.

[0131] As shown below, Table 1 illustrates a control strategy for the isothermal expansion system 18 using the fluid injectors 246 of the variable injection system 270. [Table 1] As described above, the control scheme may include multiple fluid injectors 246, or groups of multiple fluid injectors 246, as indicated by fluid injectors I1-I10. The fluid injectors 246 may be axially coupled to the turbine vanes 120, as indicated by axial positions P0-P10. The fluid flow rate through the fluid injectors 246 may be controlled by the controller 220, such as via valves 256 in the fluid circuit 254, as indicated by fluid flow rates R0-R10. If the fluid injectors 246 inject only fuel, the fluid flow rate may correspond to the fuel flow rate. In the case of a multi-fluid injector 470, multiple fluid flow rates may be part of the control scheme to account for different fluid flow rates of fuel, oxidant, and barrier gas, as detailed above.

[0132] The control strategy in Table 1 is configured to use axial position (e.g., P0-P10) and / or fluid flow rate (e.g., R0-R10) to effect a change in axial combustion position (e.g., variable heat release or combustion position 320) along the turbine blade 118, as indicated by axial combustion positions CP0-CP10. In certain embodiments, the change in axial combustion position (block 848) of process 840 is achieved at least in part or in whole by positioning fluid injectors I0-I10 at a plurality of different axial positions corresponding to axial positions P0-P10. For example, axial positions P0-P10 may be represented by the ratio of axial distance 308 divided by total axial length 310, as shown in FIGS. 2 and 3, where the ratio may gradually increase (e.g., 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0) from axial position P0 to axial position P10.

[0133] In certain embodiments, varying the axial position of combustion (block 848) in process 840 is achieved at least in part or in whole by controlling the fluid flow rate through fluid injectors I0-I10 at a plurality of different fluid flow rates (e.g., R0-R10). For example, fluid flow rates R0-R10 may gradually increase from P0 to P10, gradually decrease from P0 to P10, or any combination of increases and decreases from P0 to P10. For example, fluid flow rates R0-R10 may gradually change by at least 5%, 10%, 15%, or 20%. In the embodiment of FIG. 2, the control scheme may use different axial positions P0-P10 with or without different fluid flow rates (e.g., R0-R10). In the embodiment of FIG. 3, the control scheme may use the same axial positions P0-P10 with different fluid flow rates (e.g., R0-R10).

[0134] Additionally, the control strategy of Table 1 is configured to use axial position (e.g., P0-P10) and / or fluid flow rate (e.g., R0-R10) to control the axial extent of different axial combustion locations (e.g., variable heat release or combustion locations 320) along turbine blade 118, as shown by axial combustion locations CP0-CP10. For example, in an embodiment with different axial positions (e.g., P0-P10), process 840 may control the fluid flow rate to block upstream and / or downstream fluid injectors 246 to decrease the axial extent, such as by progressively blocking fluid flow in the following order: I10, I9, I8, I7, I6, I5, I4, I3, I2, I1, and I0. The process 840 may control the fluid flow rate to initiate fluid flow through the upstream and / or downstream fluid injectors 246 to increase the axial extent, such as by gradually initiating fluid flow in the following order: I0, I1, I2, I3, I4, I5, I6, I7, I8, I9, and I10.

[0135] As yet another example, in embodiments having the same or different axial positions (e.g., P0-P10), process 840 may control the fluid flow rates to gradually increase the range of flow rates R0-R10, such as by gradually increasing the rate of change of flow rates R0-R10, to create a larger axial range of combustion locations. Process 840 may also control the fluid flow rates to gradually decrease the range of flow rates R0-R10, such as by gradually decreasing the rate of change of flow rates R0-R10, to create a smaller axial range of combustion locations. Aspects of the control schemes described above may be used alone or in combination with each other in process 840 of FIG. 33.

[0136] FIG. 34 is a flowchart illustrating one embodiment of a process 860 for operating the gas turbine system 12 with the variable injection system 270 of the isothermal expansion system 18 of FIGS. 1-33 , where the process 860 includes control via the controller 220. In a particular embodiment, the process 860 provides detailed steps of blocks 848 and 850 in the process 840 of FIG. 33 . As shown, the process 860 includes monitoring a load on the gas turbine system 12 having the isothermal expansion system 18 coupled to the turbine stage 252 (block 862). The load may correspond to a driven machine, such as a motor-generator. The process 860 also monitors a change in the load, such as a load increase or load decrease (block 864). The load change can affect many operating parameters of the gas turbine system 12, and the operating parameters may be monitored to enable load monitoring. The operating parameters may include a compressor pressure ratio in the compressor section 42 of the gas turbine system 12, where a decrease in the compressor pressure ratio indicates a load decrease and an increase in the compressor pressure ratio indicates a load increase. The operating parameters may also include compressor outlet pressure at the outlet of compressor section 42, exhaust temperature at the outlet of turbine section 46, or any other suitable indicator of load.

[0137] If the process 860 does not observe a change in load (block 864), the process 860 continues to monitor the load (block 862). If the process 860 observes a change in load (block 864), the process 860 proceeds to initiate (block 866) a load control mode (e.g., load control mode 364) of a fluid injector 246 of the isothermal expansion system 18, the fluid injector 246 being coupled to the turbine vane 120 upstream of the turbine blade 118. Using the load control mode, the process 860 proceeds to reduce fuel flow to a downstream one of the fluid injectors 246 coupled to the turbine vane 120 in response to a load reduction (block 868). For example, the reduced fuel flow may correspond to a fluid injector 246 near the trailing edge 328 of the turbine blade 118. The process 860 may gradually decrease and / or stop fuel flow to a sequence of fluid injectors 246 at different axial locations along the turbine vane 120, with the sequence of decreasing fuel flow gradually moving from one fluid injector 246 to another in an upstream direction away from the trailing edge 328. Similarly, using a load control mode, the process 860 may proceed to increase fuel flow to downstream fluid injectors of the plurality of fluid injectors 246 coupled to the turbine vane 120 in response to an increase in load (block 870). The process 860 may gradually start and / or increase fuel flow to a sequence of fluid injectors 246 at different axial locations along the turbine vane 120, with the sequence of increasing fuel flow gradually moving from one fluid injector 246 to another in a downstream direction toward the trailing edge 328.

[0138] Technical effects of the present invention include systems and methods for isothermal expansion in turbine stages of a turbine section of a gas turbine system. The isothermal expansion can be achieved by active and / or passive control features that vary and distribute the axial location of heat release from combustion occurring in the turbine stages. The isothermal expansion system can include multiple variations in fluid injectors of a variable injection system coupled to stationary vanes of the turbine stages. The fluid injectors can vary in location (e.g., axial and radial location), cross-sectional area, geometry, fluid injection angle, fluid flow rate, relative fluid flow rate through multiple passages of the multi-fluid injectors, or any combination thereof. The isothermal expansion system can also include multiple variations in flame stabilizers of a variable stabilizer system coupled to rotating blades of the turbine stages. The flame stabilizers can vary in location (e.g., axial and radial location), cross-sectional area, geometry, size, or any combination thereof.

[0139] The isothermal expansion system may also provide active control, such as by controlling fluid flow through different fluid circuits of the variable injection system, to accommodate different operating conditions in the gas turbine system (e.g., full load and part load conditions). For example, as described above, when transitioning from a full load condition to a part load condition of the gas turbine system, the isothermal expansion system may adjust the axial location of the heat release of combustion to move further away from the trailing edges of the rotating blades. The axial location of the heat release of combustion may be controlled by reducing and / or eliminating fluid injection from fluid injectors downstream along the stationary vanes, reducing fluid flow through the fluid injectors to move the heat release further away from the trailing edges of the rotating blades, or a combination thereof.

[0140] The subject matter detailed above may be governed by one or more of the provisions set forth below.

[0141] The method includes routing combustion gases through turbine stages along a combustion gas path disposed between a turbine shaft and a turbine casing of a gas turbine, the turbine shaft disposed along an axis of rotation, the turbine casing disposed circumferentially around the turbine shaft, the turbine stage including a plurality of turbine vanes disposed upstream of a plurality of turbine blades, and controlling an axial extent of different combustion axial positions within a turbine stage expansion of the turbine stage in response to changes in load on the gas turbine to reduce temperature variations across the turbine stage expansion via an isothermal expansion system coupled to the turbine stage.

[0142] 10. The method of claim 9, wherein the change in load on the gas turbine comprises an increase in load or a decrease in load on a generator driven by the gas turbine.

[0143] 10. The method of any preceding claim, wherein controlling the axial range of different combustion axial positions comprises changing the axial distance between an upstream end and a downstream end of the axial range, changing the upstream axial position of the upstream end of the axial range, changing the downstream axial position of the downstream end of the axial range, or a combination thereof.

[0144] The method of any preceding clause, wherein controlling the axial range of axial locations of the different combustions comprises varying the downstream axial location of a downstream end of the axial range.

[0145] 10. The method of any preceding clause, wherein varying the downstream axial position of the downstream end of the axial range includes moving the downstream axial position of the downstream end of the axial range upstream in response to a change in load, including a decrease in load on the gas turbine.

[0146] 10. The method of any preceding clause, wherein varying the downstream axial position of the downstream end of the axial range includes moving the downstream axial position of the downstream end of the axial range downstream in response to a change in load, including an increase in load on the gas turbine.

[0147] The method of any preceding clause, wherein controlling the axial range of the different combustion axial positions comprises varying the axial distance between an upstream end and a downstream end of the axial range.

[0148] The method of any preceding clause, wherein controlling the axial range of different combustion axial locations comprises varying the upstream axial location of an upstream end of the axial range.

[0149] 10. The method of any preceding clause, wherein controlling the axial range of axial positions of the different combustions includes varying the axial range of axial positions of the different combustions between leading edges and trailing edges of a plurality of turbine blades in a turbine stage.

[0150] The method of any preceding clause, wherein varying the axial range of the axial location of the different combustions comprises decreasing the axial range of the axial location of the different combustions in response to a change in load, including a decrease in load on the gas turbine.

[0151] The method of any preceding clause, wherein varying the axial range of the axial location of the different combustions comprises increasing the axial range of the axial location of the different combustions in response to a change in load, including an increase in load on the gas turbine.

[0152] 10. The method of any preceding clause, wherein controlling the axial range of the different combustion axial positions includes varying fluid flow to a plurality of fluid injectors of the isothermal expansion system, at least one of the plurality of fluid injectors being coupled to each of a plurality of turbine vanes.

[0153] 10. The method of any preceding clause, wherein varying the fluid flow to the plurality of fluid ejectors includes varying the fluid flow among a plurality of fluid circuits, each of the plurality of fluid circuits being coupled to one or more of the plurality of fluid ejectors.

[0154] The method of any preceding clause, wherein the fluid flow includes a fuel flow, each of the plurality of fluid circuits includes a fuel circuit, and each of the plurality of fluid injectors includes a fuel port.

[0155] 10. The method of any preceding clause, wherein the plurality of fluid injectors are positioned at a plurality of different axial positions between the leading and trailing edges of the plurality of turbine vanes.

[0156] The method of any preceding clause, wherein varying the fluid flow to the plurality of fluid injectors comprises reducing or stopping fuel flow to one or more downstream fluid injectors of the plurality of fluid injectors disposed at a downstream portion of one or more turbine vanes of the plurality of turbine vanes in response to a change in load, including a decrease in load on the gas turbine, and wherein varying the fluid flow to the plurality of fluid injectors comprises increasing or starting fuel flow to one or more downstream fluid injectors of the plurality of fluid injectors disposed at a downstream portion of one or more turbine vanes of the plurality of turbine vanes in response to a change in load, including an increase in load on the gas turbine.

[0157] The system includes a controller having a processor, a memory, and instructions stored in the memory and executable by the processor, the instructions including instructions for controlling combustion in a combustor to generate a combustion gas flow passing through a turbine stage along a combustion gas path disposed between a turbine shaft and a turbine casing of a gas turbine, the turbine shaft disposed along a rotational axis, the turbine casing disposed circumferentially around the turbine shaft, the turbine stage including a plurality of turbine vanes disposed upstream of the plurality of turbine blades, and the controller configured to control an axial range of different combustion axial positions within a turbine stage expansion of the turbine stage in response to changes in load on the gas turbine to reduce temperature variations across the turbine stage expansion via an isothermal expansion system coupled to the turbine stage.

[0158] 10. The system of any preceding claim, wherein controlling the axial range of different combustion axial positions comprises changing the axial distance between an upstream end and a downstream end of the axial range, changing the upstream axial position of the upstream end of the axial range, changing the downstream axial position of the downstream end of the axial range, or a combination thereof.

[0159] 10. The system of any preceding clause, wherein the controller is configured to control an axial range of different combustion axial positions by varying at least a fluid flow to a plurality of fluid injectors of the isothermal expansion system, at least one of the plurality of fluid injectors being coupled to each of a plurality of turbine vanes, and the controller is configured to vary the fluid flow to the plurality of fluid injectors in response to at least a change in load including a decrease in load on the gas turbine by reducing or stopping fuel flow to one or more downstream fluid injectors of the plurality of fluid injectors disposed at a downstream portion of one or more turbine vanes of the plurality of turbine vanes, and the controller is configured to vary the fluid flow to the plurality of fluid injectors in response to at least a change in load including an increase in load on the gas turbine by increasing or starting fuel flow to one or more downstream fluid injectors of the plurality of fluid injectors disposed at a downstream portion of one or more turbine vanes of the plurality of turbine vanes.

[0160] The system includes a gas turbine having a turbine shaft disposed along a rotational axis, a turbine casing disposed circumferentially around the turbine shaft, a combustion gas path disposed between the turbine shaft and the turbine casing, and a turbine stage disposed in the combustion gas path, the turbine stage including a plurality of turbine vanes disposed upstream of a plurality of turbine blades. The system includes an isothermal expansion system coupled to the turbine stage, the isothermal expansion system including a plurality of fluid injectors disposed at a plurality of different axial positions between leading edges and trailing edges of the plurality of turbine vanes, at least one fluid injector of the plurality of fluid injectors coupled to each of the plurality of turbine vanes. The system includes a controller having a processor, a memory, and instructions stored in the memory and executable by the processor to control fluid flow to the plurality of fluid injectors in response to changes in load on the gas turbine to vary an axial extent of different combustion axial positions within the turbine stage expansion of the turbine stage and reduce temperature variations across the turbine stage expansion.

[0161] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any related 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 have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims. [Explanation of symbols]

[0162] 10 Combined Cycle Systems 12 Gas Turbine System 14 Steam Turbine System 16 Heat recovery steam generator 18 Isothermal Expansion System 30 axial direction, axial 32 Radial, axial 34 Circumferential direction, axis 36 Rotation axis 40 Intake section 42 Compressor Section 44 Combustor Section 46 Turbine Section 48 Exhaust Section 50 shaft 50A inner shaft 50B outer shaft 52 Casing 54 Compressor blade 56 Compressor vane 58 Compressor Stage 62 Combustor 64 Head end section 66 Combustion part 68 Combustion chamber 70 Combustor liner 72 Flowleave 74 Passage 76 Upstream direction 78 Headend Room 80 Intermediate Plate 82 Fuel nozzle 84 End Plate 86 Compressed Gas 88 Fluid Systems 90 Fuel supply system 92 Oxidant Supply System 94 Fluid Supply System 96 Fluid circuit 98 Components 100 components 102 Components 104 Compressed Air 106 Compressor System 108 Air Compressor 110 Drive unit 112 Combustion gases, hot combustion gases 114 Shaft 114A Inner Shaft 114B Outer Shaft 116 Casing 118 Blades, Turbine Blades 120 vanes, turbine vanes 122 Turbine Stage 124 shaft, intermediate shaft 124A Inner Shaft 124B outer shaft 126 Load 128 Shaft Subset of 130 compressor stages 132 Subset of Compressor Stages 134 Subset of Turbine Stages 136 Subset of Turbine Stages 140 Blade Set, Turbine Blade Set 142 Blade Set, Turbine Blade Set 150 EGR system 152 Exhaust Gas 152 Recirculated exhaust gas 160 High-Pressure Section 162 Medium Pressure Section 164 Low Pressure Section 166 High-Pressure Steam 168 Medium Pressure Steam 170 Low-pressure steam 172 Steam turbines, high-pressure steam turbines 174 Steam turbines, intermediate pressure steam turbines 176 Steam turbines, low-pressure steam turbines 178 Shaft 180 load 182 Condensed water 184 Exhaust Gas 190 Gas Treatment System 192 Carbon Capture Systems 194 Components 196 components 198 Components 200 Components 206 Compression System 208 Reservoir / Pipeline 212 Oxygen 214 Nitrogen 220 Controller 222 Sensor 224 processors 226 memory 228 Command 230 Communication Circuit 240 Distribution System 242 Fluid Manifold 244 Distribution Components 246 Fuel injector, fluid injector 248 Turbine Vane Set 250 Flame Stabilizer 252 Turbine Stage, Common Turbine Stage 254 Fluid circuit 256 valves 270 variable injection system 272 Variable Stabilizer System 274 Circumferential arrangement 276 Axial position 278 Circumferential arrangement 280 Axial position 282 Circumferential arrangement 284 Axial position 286 Rotation Direction 288 Rotation Direction 290 vertical dashed line, dashed line 292 vertical dashed line, dashed line 292 vertical dashed line, dashed line 294 vertical dashed line 296 Variable injection position 298 dashed line 300 leading edge 302 Trailing edge 304 Pressure Surface, Surface 306 Suction surface, surface 308 Axial distance 310 Total axial length 312 Jet axis or jet direction, fluid jet axis or direction 314 angle 316 Tangent line 320 Combustion position (axial position of combustion), variable heat release or combustion position 322 dashed line 324 dashed line 326 leading edge 328 Trailing edge 330 Pressure Surface 332 Suction surface, surface 334 Axial distance 336 Overall axial length, axial length 350 Constant injection position 352 dashed line 360 Control Mode 362 Isothermal Control Mode 364 Load Control Mode 366 Fuel Control Mode 368 Multi-fluid control mode 370 Vane body 372 Vane base 374 Vane tip 376 Radial length, total radial length 378 Radial Distance 380 Cross-sectional area or cross-sectional shape 382 Cross-sectional area 384 dashed line 390 dashed line 400 dashed line 410 Variable dashed line 412 axial range 414 Trailing edge part 420 Variable dashed line 422 axial range 430 Variable dashed line 432 axial range 434 Leading edge 440 dashed line 450 dashed line 460 dashed line 470 Multifluid Injector 472 Main Unit 474 Fluid passage 476 Central axis 478 Wall 479 Multifluid Injector 480 Fluid passage 482 Wall 484 Fluid passage, passageway 486 Wall 488 plane 500 fluid passage 502 Converging-Diverging Passage Geometry 504 Main Unit 506 Entrance 508 Exit 510 Flow direction 512 axes 514 Converging Passage 516 Diverging Passage 518 throat, profile 520 Profile 530 Fluid passage 532 Converging Passage Geometry 534 Entrance 536 Exit 538 Flow Direction 540 axes 542 Profiles 542 Linear Profile 550 Converging Passage Geometry 552 Converging Passage Geometry 554 Converging Passage Geometry 556 Flow direction 558 Entrance 560 Exit 562 Entrance 564 Exit 566 Entrance 568 Exit 580 surface 582 Exit 584 Fluid passage 586 Main Unit 588 Entrance 590 shaft 598 Surface 600 body 602 Fluid passage 604 Entrance 606 Exit 608 Passage 610 Passage 620 surface 622 Main Unit 624 Fluid passage 626 Entrance 628 Exit 630 Passage 632 Passage 634 Passage 650 Blade Body 652 Base 654 Tip 656 Cross-sectional area 660 Protrusion 662 recess 664 Surface 666 Elliptical Geometry 668 C-shaped geometry 670 dashed line 672 Radial Distance 674 Radial length, total radial length 676 Leading edge 690 dashed line 700 dashed line 702 Trailing edge part 710 Variable dashed line 712 axial range 720 Variable dashed line 722 axial range 730 dashed line, variable dashed line 732 axial range 750 Flow direction 752 Upstream edge 754 Downstream edge 756 Opposite side 758 Opposite side 760 Variable Distance, Distance 764 Back wall 766 Opposite side walls, side walls 770 Space 772 Opening 774 Low speed range 790 bottom 792 variable depth, depth 794 height, variable height 796 height 798 height 800 Contours, Lines 810 Wall 812 Space 814 Opening 820 Rectangular Geometry 822 Upstream flat wall, flat wall 824 Downstream flat wall 826 Side wall 840 Process

Claims

1. 1. A method comprising: channeling (844) combustion gases along a combustion gas path disposed between a turbine shaft (114) and a turbine casing (116) of a gas turbine (46) through a turbine stage (122), wherein the turbine shaft (114) is disposed along a rotational axis, the turbine casing (116) is circumferentially disposed around the turbine shaft (114), and the turbine stage (122) comprises a plurality of turbine vanes (120) disposed upstream of a plurality of turbine blades (118); The method further includes controlling (850) an axial extent of different combustion axial locations within a turbine stage expansion of the turbine stage (122) to reduce temperature variations across the turbine stage expansion via an isothermal expansion system (18) coupled to the turbine stage (122) in response to changes in load of the gas turbine (46).

2. The method of claim 1 , wherein the change in the load on the gas turbine (46) comprises an increase in load or a decrease in load on a generator driven by the gas turbine (46).

3. 2. The method of claim 1, wherein controlling (850) the axial range of the different combustion axial locations comprises changing the axial distance between an upstream end and a downstream end of the axial range, changing the upstream axial position of the upstream end of the axial range, changing the downstream axial position of the downstream end of the axial range, or a combination thereof.

4. The method of claim 1 , wherein controlling (850) the axial range of the different combustion axial locations comprises varying a downstream axial location of a downstream end of the axial range.

5. 5. The method of claim 4, wherein varying the downstream axial position of the downstream end of the axial range comprises moving the downstream axial position of the downstream end of the axial range upstream in response to the change in the load, including a decrease in the load on the gas turbine.

6. 5. The method of claim 4, wherein varying the downstream axial position of the downstream end of the axial range comprises moving the downstream axial position of the downstream end of the axial range downstream in response to the change in the load, including an increase in the load on the gas turbine.

7. The method of claim 1 , wherein controlling (850) the axial range of the different combustion axial locations comprises varying an axial distance between an upstream end and a downstream end of the axial range.

8. The method of claim 1 , wherein controlling the axial range of the different combustion axial locations comprises varying an upstream axial location of the upstream end of the axial range.

9. 2. The method of claim 1, wherein controlling the axial range of axial positions of the different combustions comprises varying the axial positions of the different combustions between leading edges and trailing edges of the plurality of turbine blades in the turbine stage.

10. 10. The method of claim 9, wherein varying the axial range of axial locations of the different combustions comprises decreasing the axial range of axial locations of the different combustions in response to a change in the load, the change comprising a decrease in the load on the gas turbine.

11. 10. The method of claim 9, wherein varying the axial range of axial locations of the different combustions comprises increasing the axial range of axial locations of the different combustions in response to a change in the load, including an increase in the load on the gas turbine.

12. 2. The method of claim 1, wherein controlling the axial range of the different combustion axial positions comprises varying fluid flow to a plurality of fluid injectors of the isothermal expansion system, at least one of the plurality of fluid injectors being coupled to each of the plurality of turbine vanes.

13. 13. The method of claim 12, wherein varying the fluid flow to the plurality of fluid injectors includes varying the fluid flow among a plurality of fluid circuits, each of the plurality of fluid circuits being coupled to one or more of the plurality of fluid injectors.

14. The method of claim 13, wherein the fluid flow comprises a fuel flow, each of the plurality of fluid circuits (96) comprises a fuel circuit, and each of the plurality of fluid injectors (246) comprises a fuel port.

15. The method of claim 14, wherein the plurality of fluid injectors (246) are positioned at a plurality of different axial positions between a leading edge (300) and a trailing edge (302) of the plurality of turbine vanes (120).

16. 13. The method of claim 12, wherein varying the fluid flow to the plurality of fluid injectors comprises reducing or ceasing fuel flow to one or more downstream fluid injectors of the plurality of fluid injectors disposed at a downstream portion of one or more turbine vanes of the plurality of turbine vanes in response to the change in load comprising a decrease in the load on the gas turbine, and varying the fluid flow to the plurality of fluid injectors comprises increasing or initiating fuel flow to the one or more downstream fluid injectors of the plurality of fluid injectors disposed at a downstream portion of the one or more turbine vanes of the plurality of turbine vanes in response to the change in load comprising an increase in the load on the gas turbine.

17. A system (10), comprising: a controller (220) having a processor (224), a memory (226), and instructions stored in the memory and executable by the processor (224); the instructions include instructions for controlling combustion in the combustor (62) to generate a combustion gas flow passing through a turbine stage (122) along a combustion gas path disposed between a turbine shaft (114) and a turbine casing (116) of a gas turbine (46), the turbine shaft (114) being disposed along an axis of rotation (36), the turbine casing (116) being circumferentially disposed about the turbine shaft (114), and the turbine stage (122) comprising a plurality of turbine vanes (120) disposed upstream of a plurality of turbine blades (118); The system (10) also includes instructions for controlling an axial range of different combustion axial locations within a turbine stage expansion of the turbine stage (122) in response to changes in load on the gas turbine (46) to reduce temperature variations across the turbine stage expansion via an isothermal expansion system (18) coupled to the turbine stage (122).

18. 18. The system (10) of claim 17, wherein controlling the axial range of the different combustion axial positions comprises changing the axial distance between an upstream end and a downstream end of the axial range, changing the upstream axial position of the upstream end of the axial range, changing the downstream axial position of the downstream end of the axial range, or a combination thereof.

19. The controller is configured to control the axial range of the different combustion axial positions by varying fluid flow to at least a plurality of fluid injectors of an isothermal expansion system, at least one of the plurality of fluid injectors being coupled to each of the plurality of turbine vanes, and the controller is configured to at least vary fluid flow to one or more downstream fluid injectors of the plurality of fluid injectors located at a downstream portion of one or more turbine vanes of the plurality of turbine vanes in response to the change in load, including a decrease in the load on the gas turbine.

18. The system of claim 17, wherein the controller is configured to modify the fluid flow to the plurality of fluid injectors by reducing or ceasing fuel flow to one or more downstream fluid injectors of the plurality of fluid injectors disposed at the downstream portion of the one or more turbine vanes of the plurality of turbine vanes in response to at least the change in load including an increase in the load on the gas turbine by increasing or initiating fuel flow to the one or more downstream fluid injectors of the plurality of fluid injectors disposed at the downstream portion of the one or more turbine vanes of the plurality of turbine vanes.

20. A system (10), comprising: a turbine shaft (114) disposed along the axis of rotation (36); a turbine casing (116) circumferentially disposed about the turbine shaft (114); a combustion gas path disposed between the turbine shaft (114) and the turbine casing (116); a turbine stage (122) disposed in the combustion gas path, the turbine stage (122) comprising a plurality of turbine vanes (120) disposed upstream of a plurality of turbine blades (118); a gas turbine (46) comprising: an isothermal expansion system coupled to the turbine stage, the isothermal expansion system including a plurality of fluid injectors positioned at a plurality of different axial positions between a leading edge and a trailing edge of the plurality of turbine vanes, at least one of the plurality of fluid injectors being coupled to each of the plurality of turbine vanes; a controller having a processor; a memory; and instructions stored in the memory and executable by the processor, a controller (220), the instructions including instructions for controlling fluid flow to the plurality of fluid injectors (246) in response to changes in load on the gas turbine (46) to vary an axial extent of different combustion axial locations within a turbine stage expansion of the turbine stage (122) to reduce temperature variations across the turbine stage expansion; A system (10) comprising:

Images