System and method for operating exhaust gas recirculation in gas turbine

Abstract

To provide a system and a method for improving combustion operability and load efficiency through productive use of recirculation exhaust gas.SOLUTION: A system 10 includes: a gas turbine system 52 including an inlet sensor 278 for detecting one or a plurality of characteristics; a power generator driven by a turbine 156 and generating and transferring electric power to an electrical grid; and a control system. The control system includes: one or a plurality of dampers 202, 210, 224, 240, 244, 254, 258 disposed along an exhaust recirculation path 220 and operable between an open position and a closed position; and a controller 214 configured to receive sensor data related to the characteristics at an inlet and control an amount of exhaust gas 66 to be injected to a compressor 152 by adjusting at least one of the dampers 202, 210, 224, 240, 244, 254, 258 on the basis of the received sensor data.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates generally to gas turbine systems and, more particularly, to gas turbine driven power plants. More particularly, the invention claimed herein relates to the subject matter set forth in the claims. [Background technology]

[0002] Gas turbine engines are used in a wide variety of applications, such as power generation, aircraft, and various machinery. Gas turbine engines generally combust fuel with an oxidizer (e.g., air) in a combustor section to generate hot combustion products, which then drive one or more turbine stages in a turbine section. The turbine section then drives one or more compressor stages in a compressor section, thereby compressing the oxidizer and introducing it into the combustor section along with the fuel. Additional fuel and oxidizer are mixed in the combustor section and then combusted to produce hot combustion products. These combustion products may include unburned fuel, residual oxidizer, and various emissions (e.g., nitrogen oxides), depending on the combustion conditions. Furthermore, gas turbine engines typically consume large amounts of air as an oxidizer and emit significant amounts of exhaust gases into the atmosphere. In other words, the exhaust gases are typically discarded as a by-product of gas turbine operation.

[0003] Therefore, improved systems and methods for recirculating exhaust gases are desired in the art. In particular, systems and methods that productively utilize recirculated exhaust gases to improve combustion operability and load efficiency would be advantageous. Summary of the Invention

[0004] The invention claimed herein relates to the subject matter set forth in the appended claims. Aspects and advantages of the invention according to this disclosure will be set forth in part in the description that follows, or will be obvious from the description, or may be learned by practice of the technology.

[0005] According to one embodiment, a system is provided, comprising: a gas turbine system including a compressor configured to compress and supply an oxidant to a combustor; the combustor configured to receive and combust fuel with the oxidant; a turbine driven by combustion products from the combustor; an exhaust gas recirculation (EGR) system configured to recirculate exhaust gases along an exhaust gas recirculation path from the turbine to an inlet of the compressor; and an inlet sensor disposed adjacent to the inlet of the compressor and configured to sense one or more characteristics at the inlet; and a control system including one or more dampers disposed along the exhaust gas recirculation path and operable between open and closed positions, and a controller in communication with the inlet sensor configured to receive sensor data related to the one or more characteristics sensed at the inlet and to operate at least one of the one or more dampers based on the received sensor data to control a temperature of the inlet of the compressor. Additionally, an optional generator driven by the turbine may be provided, which may be further configured to generate electrical power and send a portion of the electrical power to an electrical grid.

[0006] According to another embodiment, a non-transitory computer-readable medium storing instructions that, when executed, cause a method for adjusting an exhaust gas recirculation (EGR) system for injecting exhaust gases into an inlet of a compressor of a gas turbine system to be performed, the method including: receiving, at a controller of the gas turbine system, sensor data from an inlet sensor, the sensor data including one or more of a temperature, humidity, flow rate, or pressure of a fluid at the inlet; processing, by a processor of the controller, the sensor data received from the inlet sensor to determine current operating characteristics at the inlet; determining, by the processor, an EGR injection capacity based on the current operating characteristics at the inlet, the EGR injection capacity defining a maximum injectable amount of exhaust gases from the EGR system into the inlet of the compressor; and controlling, by the processor, one or more dampers associated with the EGR system to adjust the amount of exhaust gases injected into the inlet based on the determined EGR injection capacity.

[0007] According to another embodiment, a method for conditioning exhaust gas from an exhaust gas recirculation (EGR) system to heat an airflow at an inlet of a compressor of a gas turbine system is provided, the method including: determining an EGR injection capacity for an inlet of the compressor of the gas turbine system based on sensed operating characteristics of the airflow at the inlet, the EGR injection capacity defining a maximum injectable amount of exhaust gas from the EGR system of the gas turbine system into the inlet of the compressor while maintaining at least a threshold oxidizer level at the inlet; and adjusting one or more dampers of the EGR system based on the determined EGR injection capacity to maximize the temperature at the inlet of the compressor while maintaining a part load efficiency within a part load operating threshold and a base load efficiency within a base load operating threshold.

[0008] These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the technology and, together with the description, serve to explain the principles of the technology.

[0009] A full and enabling disclosure of the present invention, including the best mode of making and using the same, directed to one of ordinary skill in the art, is set forth in this specification, which makes reference to the accompanying figures. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a system including a gas turbine system according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic diagram of a system including a gas turbine system according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic diagram of a portion of the system of FIG. 2 according to an embodiment of the present disclosure. [Figure 4] 1 is a graph depicting aspects of an exhaust gas recirculation (EGR) system as a result of net GT load according to an embodiment of the present disclosure. [Figure 5] 1 is a graph depicting oxygen (O2) concentration percentage as a result of load percentage according to an embodiment of the present disclosure. [Figure 6] 1 is a graph of system efficiency measured at various loads according to an embodiment of the present disclosure. [Figure 7] 1 is a graph of the tone dynamics of a combustor engine according to an embodiment of the present disclosure. [Figure 8] 1 is a flowchart of a method for conditioning exhaust gas from an exhaust gas recirculation (EGR) system to heat an airflow at a compressor inlet to meet combustor operability requirements of a gas turbine system. DETAILED DESCRIPTION OF THE INVENTION

[0011] Reference will now be made in detail to the embodiments of the present invention, one or more examples of which are illustrated in the drawings. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Moreover, each example is provided by way of explanation of the technology, not as a limitation thereof. Indeed, it will be apparent to those skilled in the art that modifications and variations can be made in the technology without departing from the scope or spirit of the claimed technology. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield yet a further embodiment. Accordingly, the present disclosure is intended to cover such modifications and variations as come within the scope of the appended claims and their equivalents. The detailed description uses numerical and letter designations to refer to features of the drawings. Like or similar designations in the drawings and description are used to refer to like or similar parts of the invention.

[0012] As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to denote the location or importance of the individual components. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Terms such as “coupled,” “fixed,” and “attached” refer to both direct coupling, fixing, or attachment, as well as indirect coupling, fixing, or attachment via one or more intermediate components or features, unless otherwise stated herein. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that includes a list of features is not necessarily limited to only those features and may include other features not expressly listed or that are inherent to such process, method, article, or apparatus. Furthermore, unless expressly stated to the contrary, "or" refers to an inclusive disjunction, not an exclusive disjunction. For example, condition A or B can be satisfied by any one of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), or both A and B are true (or present).

[0013] Approximate terms such as "about," "generally," "approximately," or "substantially" include values ​​within plus or minus 10% of the stated value. When used in the context of angles or directions, such terms include a range of plus or minus 10 degrees of the stated angle or direction. For example, "generally vertical" includes directions within 10 degrees of any direction, e.g., clockwise or counterclockwise, from vertical.

[0014] Benefits, other advantages, and solutions to problems are described below with respect to specific embodiments. However, the benefits, advantages, solutions to problems, and all features that may give rise to or make more noticeable any benefit, advantage, or solution should not be construed as critical, necessary, or essential features of any or all of the claims.

[0015] Generally, the systems and methods described herein are intended to increase the operating (system) efficiency of a gas turbine engine. The systems and methods described herein utilize injection of recycled hot exhaust gases at the inlet of a gas turbine compressor to affect the control of the gas turbine engine. Through feedback control and adjustment of the exhaust gases injected at the inlet of the gas turbine engine, the systems and methods described herein can maximize system performance and keep the gas turbine engine within an acceptable dynamics region while maintaining high system operating flexibility. By using the recycled hot exhaust gases to control the gas turbine engine, the gas turbine engine can be more effectively regulated and maintained within desired operating conditions.

[0016] Referring now to the drawings, FIG. 1 illustrates a schematic diagram of a system 10 according to one embodiment. The system includes a gas turbine system 52 having a gas turbine engine 150 coupled to an exhaust gas recirculation (EGR) system 54. The illustrated gas turbine engine 150 includes a compressor section 152, a combustor section 154, and an expander or turbine section 156. The compressor section 152 includes one or more compressor stages 158, such as 1 to 20 stages of rotating compressor blades arranged in a serial configuration. Similarly, the combustor section 154 includes one or more individual combustors 160, such as 1 to 20 individual combustors 160 distributed circumferentially about a rotational axis 162 of the gas turbine system 52. Additionally, the combustor 160 may include one or more fuel nozzles 164 configured to inject the oxidizer 68 and / or fuel 70 into the combustor 160. For example, the head end 166 of each combustor 160 may house one, two, three, four, five, six, or more fuel nozzles 164 that may inject a stream or mixture of oxidizer 68 and / or fuel 70 into a combustion section 168 (e.g., a combustion chamber) of the combustor 160.

[0017] The fuel nozzles 164 may comprise any combination of premix fuel nozzles 164 (e.g., configured to premix the oxidizer 68 and the fuel 70 to generate an oxidizer / fuel premixed flame) and / or diffusion fuel nozzles 164 (e.g., configured to inject separate flows of the oxidizer 68 and the fuel 70 to generate an oxidizer / fuel diffusion flame). Embodiments of the premix fuel nozzles 164 may include swirl vanes, mixing chambers, or other features to internally mix the oxidizer 68 and the fuel 70 within the nozzles 164 prior to injection and combustion in the combustion chamber 168. The premix fuel nozzles 164 may also receive at least some partially mixed oxidizer 68 and fuel 70. In certain embodiments, each diffusion fuel nozzle 164 may separate the flows of the oxidizer 68 and the fuel 70 to the point of injection while also separating the flows of one or more diluents (e.g., exhaust gas 66, steam, nitrogen, or another inert gas) to the point of injection. In other embodiments, each diffusion fuel nozzle 164 may separate the oxidizer 68 and fuel 70 flows up to the injection point while partially mixing the oxidizer 68 and / or fuel 70 with one or more diluents (e.g., exhaust gas 66, steam, nitrogen, or another inert gas) prior to the injection point. Additionally, one or more diluents (e.g., exhaust gas 66, steam, nitrogen, or another inert gas) may be injected into the combustor (e.g., hot combustion products) either in the combustion zone or downstream, thereby helping to lower the temperature of the hot combustion products and reduce NOX (e.g., NO and NO2) emissions. Regardless of the type of fuel nozzle 164, the gas turbine system 52 may be controlled to provide substantially stoichiometric combustion of the oxidizer 68 and fuel 70.

[0018] In diffusion combustion embodiments using the diffusion fuel nozzle 164, the fuel 70 and oxidizer 68 generally do not mix upstream of the diffusion flame; rather, the fuel 70 and oxidizer 68 mix and react directly at the flame surface, and / or the flame surface is present at a mixing location between the fuel 70 and the oxidizer 68. In particular, the fuel 70 and oxidizer 68 approach the flame surface (or diffusion boundary / interface) separately and then diffuse (e.g., via molecular and viscous diffusion) along the flame surface (or diffusion boundary / interface) to produce the diffusion flame. Notably, the fuel 70 and oxidizer 68 may be substantially stoichiometric along the flame surface (or diffusion boundary / interface), resulting in higher flame temperatures (e.g., peak flame temperatures) along the flame surface. A stoichiometric fuel / oxidizer ratio generally results in higher flame temperatures (e.g., peak flame temperatures) compared to fuel-lean or fuel-rich fuel / oxidizer ratios. As a result, a diffusion flame may be substantially more stable than a premixed flame because the diffusion of the fuel 70 and oxidizer 68 helps maintain the stoichiometric ratio (and higher temperatures) along the flame surface. Although higher flame temperatures may also result in greater exhaust emissions, such as NOx emissions, embodiments of the present disclosure may use one or more diluents to help control temperature and emissions while still avoiding any premixing of the fuel 70 and oxidizer 68. For example, one or more diluents may be introduced separately from the fuel 70 and oxidizer 68 (e.g., after the combustion point and / or downstream of the diffusion flame), thereby helping to lower the temperature and reduce emissions (e.g., NOx emissions) produced by a diffusion flame.

[0019] During operation, as shown, the compressor section 152 receives and compresses a mixed stream of ambient air and exhaust gases 66 from the EGR system 54 and outputs a compressed stream 170 to each of the combustors 160 in the combustor section 154. Upon combustion of the fuel 70, oxidizer 68, and exhaust gases 66 in each combustor 160, additional exhaust gases or combustion products 172 (i.e., combustion gases) are channeled to the turbine section 156. Similar to the compressor section 152, the turbine section 156 includes one or more turbine or turbine stages 174, which may include a series of rotating turbine blades. These turbine blades are then driven by the combustion products 172 generated in the combustor section 154, thereby driving the rotation of a shaft 176 coupled to the machine 106. Again, the machine 106 may include various equipment coupled to either end of the gas turbine system 52, such as a machine 178 coupled to the turbine section 156 and / or a machine 180 coupled to the compressor section 152. In certain embodiments, the machines 178, 180 may include one or more generators, an oxidizer compressor for the oxidizer 68, a fuel pump for the fuel 70, a gearbox, or additional drives (e.g., steam turbine, electric motor, etc.) coupled to the gas turbine system 52. As shown, the turbine section 156 outputs exhaust gases 66 for recirculation into the compressor section 152 along an exhaust recirculation path 110 from an exhaust outlet 182 to an exhaust inlet 184 of the turbine section 156. Along the exhaust recirculation path 110, the exhaust gases 66 may pass through an exhaust gas (EG) treatment system 54 (e.g., a heat recovery steam generator (HRSG) 56 and / or an exhaust gas recirculation (EGR) system 58, which are described in more detail below).

[0020] Again, each combustor 160 in the combustor section 154 receives, mixes, and stoichiometrically combusts a compressed stream 170, an oxidizer 68, and a fuel 70 to generate additional exhaust gases or combustion products 172 to drive the turbine section 156. In a particular embodiment, the oxidizer 68 is compressed by an oxidizer compression system 186, such as a main oxidizer compression (MOC) system (e.g., a main air compression (MAC) system) having one or more oxidizer compressors (MOCs). The oxidizer compression system 186 includes an oxidizer compressor 188 coupled to a drive 190. For example, the drive 190 may include an electric motor, a combustion engine, or any combination thereof. In a particular embodiment, the drive 190 may be a turbine engine, such as the gas turbine engine 150. Thus, the oxidizer compression system 186 may be an integral part of the machine 180. In other words, the compressor 188 may be driven directly or indirectly by mechanical power provided by the shaft 176 of the gas turbine engine 150. In such an embodiment, because the compressor 188 relies on electrical power output from the turbine engine 150, the drive 190 may be omitted. However, in certain embodiments where more than one oxidizer compressor is utilized, a first oxidizer compressor (e.g., a low-pressure (LP) oxidizer compressor) may be driven by the drive 190 while the shaft 176 drives a second oxidizer compressor (e.g., a high-pressure (HP) oxidizer compressor), or vice versa. For example, in another embodiment, the HP MOC is driven by the drive 190, and the LP oxidizer compressor is driven by the shaft 176. In the illustrated embodiment, the oxidizer compression system 186 is separate from the machine 180. In each of these embodiments, the compression system 186 compresses and delivers the oxidizer 68 to the fuel nozzles 164 and the combustor 160. Accordingly, some or all of the machines 178, 180 may be configured to enhance the operating efficiency of the compression system 186 (e.g., the compressor 188 and / or the additional compressors).

[0021] The various components of machine 106, represented by element numbers 106A, 106B, 106C, 106D, 106E, and 106F, may be arranged along the line of shaft 176 and / or parallel to the line of shaft 176 in one or more series arrangements, parallel arrangements, or any combination of series and parallel arrangements. For example, machines 106, 178, 180 (e.g., 106A-106F) may include one or more gearboxes (e.g., parallel shaft, planetary gearbox), one or more compressors (e.g., oxidant compressor, booster compressor such as exhaust gas booster compressor), one or more power generation units (e.g., generators), one or more drives (e.g., steam turbine engines, electric motors), heat exchange units (e.g., direct or indirect heat exchangers), clutches, or any combination thereof, in any order and in any series and / or parallel arrangement. The compressor may comprise an axial compressor, a radial compressor, a centrifugal compressor, or any combination thereof, each having one or more compression stages. With respect to heat exchangers, a direct heat exchanger may comprise a spray cooler (e.g., a spray intercooler) that injects a liquid spray into a gas stream (e.g., an oxidant stream) to directly cool the gas stream. An indirect heat exchanger may comprise at least one wall (e.g., a shell-and-tube heat exchanger) that separates first and second streams, such as a fluid stream (e.g., an oxidant stream) separated from a coolant stream (e.g., water, air, refrigerant, or any other liquid or gaseous coolant), where the coolant stream transfers heat from the fluid stream without any direct contact. Examples of indirect heat exchangers include intercooler heat exchangers and heat recovery units, such as heat recovery steam generators. The heat exchanger may also comprise a heater.

[0022] Generally, machines 106, 178, 180 may be configured to increase the efficiency of compression system 186, for example, by adjusting the operating speed of one or more oxidant compressors in compression system 186, facilitating the compression of oxidant 68 through cooling, and / or extracting excess power. Embodiments of the present disclosure contemplate any and all permutations of the aforementioned components in machines 106, 178, 180 in series and parallel arrangements, with one, more than one, all, or none of the components deriving power from shaft 176.

[0023] In one embodiment, the EGR system 54 may include multiple exhaust gas (EG) treatment components 192, such as those indicated by element numbers 194, 196, and 198. These exhaust gas treatment components 192 (e.g., 194-198) may be arranged along the exhaust gas recirculation path 110 in one or more series arrangements, parallel arrangements, or any combination of series and parallel arrangements. For example, the exhaust gas treatment components 192 (e.g., 194-198) may include one or more heat exchangers (e.g., heat recovery units such as heat recovery steam generators, condensers, coolers, or heaters), catalyst systems (e.g., oxidation catalyst systems), particulate and / or water removal systems (e.g., inertial separators, coalescing filters, water-impermeable filters, and other filters), chemical injection systems, solvent-based treatment systems (e.g., absorbers, flash tanks, etc.), gas separation systems, gas purification systems, or any combination thereof, in any order and in any series and / or parallel arrangements. In certain embodiments, the catalyst system may include an oxidation catalyst, a carbon monoxide reduction catalyst, a nitrogen oxide reduction catalyst, aluminum oxide, zirconium oxide, silicone oxide, titanium oxide, platinum oxide, palladium oxide, cobalt oxide, or mixed metal oxides, or combinations thereof. Embodiments of the present disclosure contemplate any and all permutations of the aforementioned components 192 in series and parallel configurations. These exhaust gas treatment components 192 may remove moisture and particulates from the exhaust gas 66 while enabling feedback control of temperature, pressure, flow rate, and gas composition. Furthermore, the treated exhaust gas 66 may be extracted at one or more extraction points 76 and / or recycled to the inlet 184 of the compressor section 152, as described in more detail below. In one embodiment, the one or more extraction points 76 may be fluidly coupled to an exhaust gas supply system 78, e.g., having an exhaust gas extraction system and an exhaust gas treatment system, that receives the exhaust gas 42 from the extraction points 76, treats the exhaust gas 42, and then supplies or distributes the exhaust gas 42 to various target systems. The target system may comprise an enhanced oil recovery system, a pipeline, a storage tank, or a carbon sequestration system.

[0024] As the treated, recirculated exhaust gas 66 passes through the compressor section 152, the gas turbine system 52 may gradually bleed off a portion of the compressed stream along one or more lines 213 (e.g., bleed conduits or bypass conduits). Each line 213 may route the compressed stream to one or more heat exchangers 215 (e.g., cooling units), thereby cooling the compressed stream for recirculation to the gas turbine system 52. For example, after passing through the heat exchangers 215, a portion of the cooled compressed stream may be routed along line 213 to the turbine section 156 for cooling and / or sealing the turbine casing, turbine shroud, bearings, and other components. In such an embodiment, the gas turbine system 52 does not route the oxidizer 68 (or other potential contaminants) to the turbine section 156 for cooling and / or sealing purposes, thereby preventing leakage of the cooled compressed stream from contaminating the hot combustion products (e.g., working exhaust gases) that flow through and drive the turbine stages of the turbine section 156. In a further example, after passing through heat exchanger 215, a portion of the cooled compressed stream may be sent along line 217 (e.g., a return conduit) to an upstream compressor stage of compressor section 152, thereby improving the efficiency of compression by compressor section 152. In such an embodiment, heat exchanger 215 may be configured as an inter-stage cooling unit for compressor section 152. In this manner, the cooled compressed stream helps to increase the operating efficiency of gas turbine system 52 while maintaining the purity of the exhaust gas (e.g., substantially free of oxidant and fuel).

[0025] Figure 2 illustrates a schematic diagram of a portion of the system 10 described with respect to Figure 1. In particular, aspects of the EGR system 54 are depicted in Figure 2 in simplified form to provide a clear understanding of one example of an airflow path through the system 10 that can be used to condition the airflow in the combustor 160, and more specifically, to condition the exhaust gas airflow injected from the EGR system 54 into the inlet 184 of the compressor section 152 of the gas turbine system 52. It should be understood that the architecture depicted in Figure 2 is provided by way of example, and that other systems, components, features, and characteristics of the depicted system 10 can be otherwise included, modified, or adjusted to accommodate various system designs and requirements.

[0026] The gas turbine system 52 includes a combustor 160, a compressor section 152, and a turbine section 156. Fuel 70 is injected into the combustor 160 by fuel nozzles 164. The fuel 70 mixes with an oxidizer 68 to generate exhaust gases 66, which exit the combustor 160, at least a portion of which is supplied to the EGR system 54 through an inlet 200 of the EGR system 54. The inlet 200 of the EGR system 54 can be adjusted to control the amount (e.g., volumetric flow rate) of the exhaust gases 66 entering the EGR system 54. A damper 202 disposed in fluid communication with the inlet 200, such as within a conduit of the inlet 200, can be selectively actuated (moved) between an open position and a closed position by a motor 208, such as a servo motor. The motor 208 is in communication with a controller 214 (e.g., via wired or wireless communication) and receives signals from the controller 214 that affect the state of the damper 202 between the open and closed positions (adjusting the damper). The motor 208 may adjust the damper 202 toward an open or closed position, maintain the position of the damper 202, or otherwise adjust the position of the damper in response to commands (signals) received from the controller 214. In the closed position, the damper 202 may prevent the flow of exhaust gases 66 into the EGR system 54. By adjusting the damper 202, the flow of exhaust gases 66 may be controlled to achieve a desired exhaust gas profile (e.g., a desired volumetric flow rate, a desired pressure, etc.) controlled by the controller 214. In the fully open position, the damper 202 may maximize the flow of exhaust gases 66 into the EGR system 54. In some cases, the maximum flow of exhaust gases 66 into the EGR system 54 may refer to all of the exhaust gases 66 produced by the combustor 160. That is, the damper 202 may allow all of the exhaust gases 66 discharged from the combustor 160 to enter the EGR system 54 when the damper 202 is in the open position. In other cases, the maximum flow of exhaust gases 66 may refer to less than the total volumetric flow of exhaust gases 66 produced by combustor 160 .For example, the EGR system 54 may be configured to receive only a portion of the exhaust gases 66 generated by the combustor 160, such as 90% or less of the exhaust gases 66, 75% or less of the exhaust gases 66, or 50% or less of the exhaust gases, even when the damper 202 is in a fully open position. The remaining exhaust gases 66 may be routed away from the EGR system 54 by a conduit, often referred to as a flue 204. The flue 204 may lead to the ambient environment, another capture system or component, or the like. The flue 204 may include sensors, such as a continuous emissions monitoring system (CEMS) 206, that monitor one or more characteristics of the exhaust gases 66 passing through the flue 204. As depicted in FIG. 3 , the CEMS 206 may be in communication with a controller 214 to provide the controller 214 with sensor data related to the monitored conditions. The sensor data may be used by the controller 214 as described below. A flue damper 210 may be disposed in series with the flue 204 to control the flow of the exhaust gas 66, more specifically, to regulate leakage of the exhaust gas 66 into the surrounding environment. The flue damper 210 may be disposed in series upstream of the CEMS 206, in series downstream of the CEMS 206, or in parallel with the CEMS. The flue damper 210 may be actuated by a motor 212, such as a servo motor, in communication with a controller 214. The motor 212 is in communication with the controller 214 and receives signals from the controller 214 that affect the state of the flue damper 210 between an open position and a closed position. In response to signals received from the controller 214, the motor 212 may adjust the flue damper 210 toward an open or closed position, maintain the position of the flue damper 210, or otherwise adjust the position of the damper 210. In the closed position, the damper 210 may prevent the exhaust gas 66 from exiting the flue 204. This can create back pressure within the system 10 and / or allow the exhaust gases to further flow to another portion of the system 10, such as a carbon capture and storage (CCS) system 216, described below. The flue damper 210 can be adjusted between a closed position and an open position.Exhaust gas purification can be performed at or near the flue 204 with a filter or associated scrubbing device to further capture components of the exhaust gas 66 exiting the EGR system 54 through the flue 204. Still other treatment and disposal processes are contemplated herein.

[0027] The exhaust gas 66 entering the inlet 200 of the EGR system 54 can pass through a carbon capture and storage (CCS) system 216, which can extract carbon from the exhaust gas 66 and sequester the extracted carbon. By way of example, the CCS system 216 can utilize wet chemistry, whereby carbon dioxide (CO) is captured by adsorption to a chemical or physical solvent in aqueous solution. In other embodiments, dry chemistry, such as a carbonate looping process, can be utilized. A direct contact cooler (DCC) can be utilized by the CCS system 216 using a cooling fluid, such as cooling water, to contact and cool the exhaust gas 66. The cooling water is routed through the DCC to reduce the temperature of the exhaust gas 66, clean and purify the exhaust gas 66, capture residual contaminants in the exhaust gas 66, and reduce the moisture content of the exhaust gas 66. The CCS system 216 can generally utilize any carbon capture process, including cooling the exhaust gas and removing CO from the cooled gas using an ammoniated solution or slurry. It should be noted that the exhaust gas is cooled not only in the DCC but also in the absorber and water wash section. Apart from cooling, a significant portion of the heat of CO2 absorption may also be removed by using a mechanical refrigeration system depending on the ambient conditions and the specific application. The removed (cleaned) components of the exhaust gas 66 may be removed in the blowdown line 218.

[0028] The exhaust gases 66 enter an exhaust gas recirculation path 220 (which may be part of the exhaust gas recirculation path 110 described above with respect to FIG. 1 ). A flue gas outlet 222 in communication with the exhaust gas recirculation path 220 vents the exhaust gases 66 from the exhaust gas recirculation path 220 to the ambient environment or another location, such as a storage system. A damper 224 may be located downstream to further selectively restrict passage of the exhaust gases 66 along the exhaust gas recirculation path 220. The damper 224 may be actuable between an open position and a closed position by a motor 226, such as a servo motor. In certain instances, the damper 224 may be referred to as an EGR inlet damper. The damper 224 may be adjusted between an open position and a closed position to selectively route the exhaust gases 66 to the exhaust gas recirculation path 220. The motor 226 may be in communication with the controller 214 to affect the state of the damper 224 between the open position, the closed position, and the adjusted position. When the damper 224 is closed, the exhaust gases 66 are directed to the flue gas outlet 222. When the damper 224 is open or adjusted between an open and a closed position, the exhaust gases 66 (or a portion thereof) may pass through the exhaust gas recirculation path 220 to further components that inject the exhaust gases 66, as described below.

[0029] In one embodiment, the exhaust gas recirculation path 220 is in fluid communication with one or more conditioning components 228. The conditioning components 228 may include, for example, one or more EGR blowers 230 (also referred to as booster blowers, recycle blowers, or exhaust gas compressors) and one or more EGR coolers 232. The EGR blowers 230 may affect the flow rate of the exhaust gases 66 in the exhaust gas recirculation path 220. The EGR coolers 232 may reduce the temperature of the exhaust gases 66 before returning to the combustor 160. To reduce the temperature gradient across the one or more EGR coolers, the EGR may be “pre-cooled” through a first EGR cooler to reduce the temperature of the EGR entering the second EGR cooler. The temperature of the cooling fluid used to pre-cool the EGR in the first EGR cooler may be higher than the temperature of the cooling fluid used to cool the EGR in the second EGR cooler. In this manner, the overall temperature drop of the EGR may be split across the two EGR coolers, reducing the temperature gradient to which each cooler is exposed. The recycle blower 230 and EGR cooler 232 may be arranged in series or parallel along the exhaust gas recirculation path 220 to affect desired characteristics (i.e., conditions) of the exhaust gas 66 prior to injection into the combustor 160.

[0030] In one embodiment, conditioning component 228 may be disposed in parallel with EGR recirculation loop 234. EGR recirculation loop 234 may include an inlet 236 disposed upstream of conditioning component 228 and an outlet 238 disposed downstream of conditioning component 228. A damper 240 may be disposed along EGR recirculation loop 234 between inlet 236 and outlet 238. Damper 240 may be controlled by a motor 242, such as a servo motor, to selectively adjust the airflow of exhaust gases through EGR recirculation loop 234. Motor 242 may be in communication with controller 214 to open, close, and / or adjust the position of damper 240 to regulate the airflow through EGR recirculation loop 234. For example, if the controller 214 determines that a greater volumetric flow rate of recirculated exhaust gas 66 is desired in the combustor 160, the controller 214 may send a signal to the motor 242 to open the damper 240, allowing the greater volumetric flow rate through the exhaust recirculation path 220. Bypassing the conditioning component 228 may allow the airflow through the exhaust recirculation path 220 to be adjusted more quickly than would be necessary if adjustments were made in series with the conditioning component 228. In other cases, the conditioning component 228 may remain operating in a fixed (or range-bound) state, with additional exhaust gas 66 being routed to the combustor 160 through the EGR recirculation loop 234. In still other cases, the EGR recirculation loop 234 may reverse the flow of exhaust gas 66 from a downstream location to an upstream location. For example, if airflow is throttled downstream of conditioning component 228, EGR recirculation loop 234 may prevent backpressure from building downstream of conditioning component 228 by temporarily allowing exhaust gases to be injected back into exhaust recirculation path 220 upstream of conditioning component 228. Damper 224 may be adjusted (i.e., moved toward an open or closed position) in response to exhaust gases 66 traveling through EGR recirculation loop 234 toward an upstream location to further control backpressure in exhaust recirculation path 220.

[0031] A damper 244, located downstream of the inlet 236 to the EGR recirculation loop 234, is controlled by a motor 246, such as a servo motor, to regulate the flow of exhaust gases 66. The damper 244 may be selectively actuated (moved) between an open position and a closed position by the motor 246. The motor 246 is in communication with the controller 214 and receives signals from the controller 214 that affect the state of the damper 244 between the open and closed positions. In response to the signals received from the controller 214, the motor 246 may adjust the damper 244 toward the open or closed position, maintain the position of the damper 244, or otherwise adjust the position of the damper 244. In the closed position, the damper 244 may prevent the flow of exhaust gases 66 into the combustor 160. The damper 244 may be adjusted between a closed position and an open position to control the exhaust flow. Excess exhaust gases may exit the exhaust recirculation path 220 through a drain 248 located upstream of the damper 244.

[0032] A sensor 250 positioned along the exhaust gas recirculation path 220 may measure one or more characteristics of the exhaust gas 66 at or near the damper 244. The one or more characteristics may include, for example, pressure, temperature, flow rate, humidity, etc. The sensor 250 may further sample the exhaust gas 66 to detect other aspects of the exhaust gas, such as particle count or the presence of one or more combustion components. The sensor 250 may communicate the sensed one or more characteristics to the controller 214.

[0033] An EGR vent 252 is disposed downstream of the damper 244. The EGR vent 252 may be connected to the ambient environment, another capture system or component, or the like. A damper 254 may be disposed at or within the EGR vent 252 to control the flow of exhaust gases through the EGR vent 252. The damper 254 may be selectively actuated (moved) between an open position and a closed position by a motor 256, such as a servo motor. The motor 256 is in communication with the controller 214 and receives signals from the controller 214 that affect the state of the damper 254 between the open and closed positions. In response to signals received from the controller 214, the motor 256 may adjust the damper 254 toward the open or closed position, maintain the position of the damper 254, or otherwise adjust the position of the damper 254. In the closed position, the damper 254 may prevent the flow of exhaust gases 66 from the exhaust gas recirculation path 220. The damper 254 can be adjusted between a closed and an open position to control the exhaust flow.

[0034] An EGR outlet damper 258 is disposed downstream of the EGR vent 252. The EGR outlet damper 258 may be selectively actuated (moved) between an open position and a closed position by a motor 260, such as a servo motor. The motor 260 is in communication with the controller 214 and receives signals from the controller 214 that affect the state of the EGR outlet damper 258 between the open and closed positions. In response to the signals received from the controller 214, the motor 260 may adjust the EGR outlet damper 258 toward the open or closed position, maintain the position of the EGR outlet damper 258, or otherwise adjust the position of the EGR outlet damper 258. In the closed position, the EGR outlet damper 258 may prevent the flow of exhaust gases 66 from the exhaust gas recirculation path 220 to the combustor 160. The EGR outlet damper 258 may be adjusted between a closed position and an open position to control exhaust flow. When closed, the EGR outlet damper 258 may allow the passage of exhaust gases 66 from the exhaust gas recirculation path 220 to the inlet 184 of the combustor 160. In some cases, the EGR outlet damper 258 and the damper 244 may operate in series to form a dual outlet damper 258.

[0035] The outlet 262 of the exhaust gas recirculation path 220 may be in fluid communication with the inlet 184 of the combustor 160, such as an inlet 264 located upstream of the inlet 184, so that the exhaust gas 66 returning to the combustor 160 through the EGR system 54 is injected into the upstream flow path along with the oxidizer 68 for combustion. As depicted in FIG. 2 , the upstream side of the combustor 160 may include various components configured to prepare the airflow including the oxidizer 68 for combustion. These various components may include an oxidizer sensor 266 configured to sense one or more characteristics of the airflow entering a pre-combustor section 268. The oxidizer sensor 266 may be in communication with the controller 214 and transmit data to the controller 214 regarding the one or more sensed characteristics of the oxidizer in the pre-combustor section 268. The pre-combustor section 268 may further include an inlet filter 270, one or more evaporative waste control systems (EVAPs) 272, and a drift eliminator 274. An EGR mixer 276 may be included, for example, between the EVAP 272 and the drift eliminator 274 to mix the exhaust gas 66 injected into the pre-combustor section 268 with the oxidizer 68 .

[0036] For example, a sensor 278 may be positioned upstream of the combustor 160 to detect one or more properties of the airflow including the injected exhaust gas 66 and oxidant 68. The sensor 278 is in communication with the controller 214 and transmits sensor data regarding the sensed one or more properties of the oxidant and exhaust gas 66 entering the combustor 160. As described below, the controller 214 may process and / or compare the data received from the sensors 266 and 278 to determine the effectiveness of the EGR system 54, and more specifically, the status of the EGR system 54, which may be used for further processing and closed-loop control.

[0037] During some turbine operations, the turbine pressure ratio may reach the operating pressure ratio limit of the compressor. This can result in compressor surge. The compressor pressure ratio may also be greater than the turbine pressure ratio due to pressure losses across the combustor. Protecting the compressor pressure ratio typically involves bleeding discharge air and recirculating it to the compressor inlet. This operation, known as inlet bleed heat (IBH) control, also increases the compressor inlet temperature by mixing cooler ambient air with the bleed portion of the hot compressor discharge air. This is depicted by path 280 in FIG. 2. In one embodiment, path 280 may be divided into two segments, including a first segment 282 and a second segment 284. The first segment 282 and the second segment 284 may be coupled to the pre-combustor section 268 at staggered intervals along the air flow path to continuously introduce IBH into the pre-combustor section 268, thereby reducing the introduction of steep temperature gradients. Additionally, a drain 286 may be located in the pre-burner section 268 to dissipate excess airflow and heat.

[0038] FIG. 3 shows a schematic diagram of various components of the system 10, such as sensors 206, 250, 266, and 278, motors 208, 212, 226, 246, 256, 260, and controller 214, which communicate with each other.

[0039] The controller 214 may generally comprise a control circuit having one or more processors 300 coupled to a memory 302. The processor 300 may comprise any suitable processing device (e.g., a control circuit, a processor core, a microprocessor, an application-specific integrated circuit, a field-programmable gate array, a controller, a microcontroller, etc.) and may be one or more operably connected processors. The memory 302 may comprise one or more non-transitory computer-readable storage media, such as RAM, ROM, EEPROM, EPROM, one or more memory devices, flash memory devices, and combinations thereof. The memory 302 may store information accessible by the processor 300. For example, the memory 302 (e.g., one or more non-transitory computer-readable storage media, memory devices) may include computer-readable instructions 304 executable by the processor 300. The instructions 304 may be software, firmware, or both written in any suitable programming language, or may be implemented in hardware or firmware. Additionally or alternatively, the instructions 304 may execute in logically and / or virtually separate threads on the processor 300. For example, memory 302 may store instructions 304 that, when executed by processor 300, cause processor 300 to perform operations, such as any of the operations and functions described herein.

[0040] Controller 214 may communicate with various components of system 10 via wired or wireless interfaces 306. In one embodiment, sensors 206, 250, 266, and 278 and motors 208, 212, 226, 246, 256, and 260 may be coupled to controller 214 via one or more wired connections 308. Controller 214 receives data 310 including information related to one or more sensed characteristics 312 from sensors 206, 250, 266, and 278 and controls (e.g., regulates) motors 208, 212, 226, 246, 256, and 260 by sending signals via wired connections 308. In another embodiment, sensors 206, 250, 266, and 278 and motors 208, 212, 226, 246, 256, and 260 may communicate wirelessly with controller 214 via a wireless communication mode such as, for example, an ultra-wideband communication network (UWB), a wireless universal serial bus (USB) communication network, a communication network implementing ZigBee Alliance Corporation's ZigBee®, a general packet radio service (GPRS) network, or the like.

[0041] The controller 214 generates command instructions that generally control the operation of the EGR system 54 ( FIG. 2 ) to inject the exhaust gas 66 into the inlet 184 of the combustor 160, thereby enhancing the performance and efficiency of the system 10. In addition to relying on the data 310, the controller 214 may generate the command instructions based in part on algorithms stored in a memory, such as the memory 302. These algorithms may, for example, enable the controller 214 to maintain NOx and CO2 emissions in the exhaust gas within certain predetermined emission limits, or in another case, to maintain the light-off temperature of the combustor within predetermined limits. It will be appreciated that the algorithms may include inputs of parameter variables such as compressor pressure ratio, ambient humidity, inlet pressure loss, turbine exhaust backpressure, as well as any other suitable parameters. The schedules and algorithms executed by the controller 214 respond to variations in ambient conditions that affect emissions, combustor dynamics, light-off temperature limits at full load and part load operating conditions, maintaining part load efficiency within part load operating thresholds, maintaining base load operating threshold requirements, etc. The controller 214 may apply algorithms for scheduling the gas turbine, such as setting a desired turbine exhaust temperature and combustor fuel split, in order to adhere to the operability boundaries of the gas turbine system while meeting performance targets. For example, the controller 214 may determine the combustor temperature rise and NOx during part load operation to increase the operating margin to the combustion dynamics boundaries, thereby improving the operability, reliability, and availability of the power generation unit.

[0042] 4 shows a graphical representation of EGR control parameters for an exemplary system, where the X-axis represents load in megawatts (mw) and the Y-axis represents EGR percentage and compressor inlet temperature (CTIM) in degrees Fahrenheit. Line 400 represents the percentage of maximum EGR (%EGR). Line 402 represents the EGR T DEMAND Line 404 shows CTIM with EGR. Line 406 shows inlet guide vane (IGV) temperature. Line 408 shows IGV temperature (cold) and line 410 shows IGV temperature (hot).

[0043] FIG. 5 shows a graphical representation of the oxygen (O2) concentration detected in the system 10 as a result of loading the system. The X-axis represents the percentage of maximum load (% load), and the Y-axis represents the relative amount of O2. Line 500 indicates the minimum O2 concentration required to sustain a flame in the combustor 160 (FIG. 2). Line 500 is typically set at 15-17% O2, below which point the flame becomes difficult to sustain and performance rapidly declines. Line 502 indicates the minimum O2 concentration required to effectively operate the duct burner 288 (FIG. 2) downstream of the combustor 160. Line 502 is typically set at 10-12% O2, below which point the duct burner 288 (FIG. 2) becomes difficult to sustain a flame. Line 504 indicates the O2 concentration at the inlet 184 of the combustor 160 as a result of load percentage. Line 506 shows the O2 concentration at the outlet of combustor 160 as a result of load percentage. In one embodiment, the O2 concentration measured at the inlet 184 of combustor 160 may be measured by sensor 278, and the O2 concentration measured at the outlet of combustor 160 may be measured by sensor 290.

[0044] Referring again to FIG. 4 , a vertical line 412 is shown at a minimum emissions compliance load (MECL), approximately 165 megawatts in this illustration. Prior to achieving the MECL, the EGR system 54 ( FIG. 2 ) may be in an off state, as indicated by line 400. That is, exhaust gases 66 are not actively injected into the inlet 184 of the combustor 160 prior to achieving the MECL. To turn the EGR system 54 off, the controller 214 may cause one or more of the motors 208, 212, 226, 242, 246, 256, and / or 260 to close the associated dampers 202, 210, 224, 240, 244, 256, and / or 258, thereby preventing the flow of exhaust gases from reaching the outlet 262 and entering the flow path of the oxidizer 68. In many cases, dampers 202, 210, 224, 240, 244, 256, and / or 258 start in a closed state prior to operation of system 10. Beginning at line 412 (after achieving MECL), EGR system 54 is enabled by controller 214 to inject exhaust gas 66 into the flow path of oxidizer 68. First, EGR system 54 may ramp up (increase) the injection rate at a first rate shown at section 414 of line 400. To affect the ramp-up indicated by section 414 of line 400, controller 214 may cause one or more (e.g., all) of motors 208, 212, 226, 242, 246, 256, and / or 260 to move associated dampers 202, 210, 224, 240, 244, 256, and / or 258 toward an open position, thereby allowing the flow of exhaust gas to reach outlet 262 and mix with oxidizer 68 at an increased velocity. After a period of time, EGR system 54 may continue ramping up at a second rate, indicated by section 416 of line 400, that is slower than the first rate. EGR system 54 continues to increase the injection of exhaust gas 66 into inlet 184 of combustor 160, for example, at the second rate.

[0045] 5, the O2 concentration at the inlet 184, i.e., the concentration measured by sensor 278 and represented by line 504, is maintained at ambient conditions (approximately 21%) until the system 10 reaches a load percentage of approximately 20-40% load, represented by line 508, at which point the system 10 exceeds the MECL. After reaching the MECL, the O2 concentration at the inlet 184 decreases as a result of the introduction of exhaust gas 66. As the EGR system 54 increases the volumetric flow rate of exhaust gas injected into the inlet 184 of the combustor 160, the O2 concentration continues to decrease. However, the O2 concentration remains above the minimum O2 concentration, represented by line 500, required to sustain a flame in the combustor 160 until 100% (maximum) load is achieved. As shown by line 506, the O2 concentration at the exit of the combustor 160 continues to exceed the O2 concentration represented by line 502 required to effectively operate the duct burner 288 until 100% (maximum) load is achieved. Thus, the EGR system 54 does not adversely affect combustion by causing flame problems in the combustor or duct burner.

[0046] 6-8 show graphical illustrations of system efficiency at various relative loads across an exemplary gas turbine system 52. Specifically, FIG. 6 shows system efficiency measured at 40% relative load across a range of EGR return temperatures, FIG. 7 shows system efficiency measured at 60% relative load across a range of EGR return temperatures, and FIG. 8 shows system efficiency measured at 80% relative load across a range of EGR return temperatures. In all of FIGs. 6-8, the X-axis represents EGR return temperature, i.e., the temperature, measured in degrees Celsius, of the exhaust gases 66 injected into the inlet 184 of the combustor 160, and the Y-axis represents net system efficiency as a result of the EGR return temperature.

[0047] Referring to FIG. 6 , a graph of net efficiency is shown for a 40% relative load 600A, a 60% relative load 600B, and an 80% relative load 600C. The relative loads 600A, 600B, and 600C are shown for ease of understanding. In reality, the relative loads 600A, 600B, and 600C do not overlap on the Y axis. Instead, the relative loads 600A, 600B, and 600C are displaced from one another along the Y axis. For ease of illustration, the left endpoints of the relative loads 600A, 600B, and 600C are located at a relatively common starting point. In reality, the left endpoints of the relative loads 600A, 600B, and 600C vary. For example, the left endpoint of relative load 600A may be at approximately 42.5%, while the left endpoint of relative load 600B may be at approximately 48.5%, while the left endpoint of relative load 600C may be at approximately 52.2%. Each of relative loads 600A, 600B, and 600C includes lines 602A, 602B, and 602C, respectively, at system efficiencies measured without EGR. That is, lines 602A, 602B, and 602C represent system efficiencies when the system efficiency is estimated without EGR exhaust gas injected at inlet 184 of combustor 160. Test data was collected for EGR exhaust gas injected into inlet 184 at six different temperatures, including approximately 17°C (left endpoint), approximately 23°C, approximately 28°C, approximately 34°C, approximately 39°C, and approximately 45°C (right endpoint). Tests were conducted at 17°C, 23°C, and 28°C by cooling the EGR exhaust gas above the ambient conditions where lines 602A, 602B, and 602C were measured. Tests at 34°C, 39°C, and 45°C were conducted above the ambient EGR temperature where line 602 was measured. As depicted, increasing the EGR stream temperature facilitates increasing the inlet stream temperature to the compressor section and optimizing / minimizing the extraction of compressor discharge air via the inlet bleed heating system, thereby improving part-load system efficiency.

[0048] As depicted graphically in FIG. 6 , increasing EGR injection into the combustor 160 improves system efficiency, allowing the gas turbine system 52 to operate at higher efficiency while reducing fuel consumption. In addition to improving system efficiency, the EGR system 54 can assist in regulating the control of tone dynamics. While higher combustion gas temperatures (such as those introduced by utilizing large amounts of EGR injection) generally improve the thermodynamic efficiency of the combustor, higher combustion gas temperatures also promote flame-holding conditions, in which the combustion flame moves toward the fuel delivered by the fuel nozzles, potentially accelerating fuel nozzle wear over a relatively short period of time. Furthermore, higher combustion gas temperatures generally increase the dissociation rate of diatomic nitrogen, increasing the production of nitrogen oxides (NOX). Conversely, lower combustion gas temperatures, associated with reduced fuel flow and / or part-load operation (turndown), generally decrease the chemical reaction rate of the combustion gases, increasing the production of carbon monoxide and unburned hydrocarbons.

[0049] Although effective in providing flame-holding protection and controlling undesirable emissions while enabling higher operating temperatures, some combustors, under certain operating conditions, may exhibit combustion instability resulting from the interaction or coupling of the combustion process or flame dynamics with one or more acoustic resonant frequencies of the combustor. For example, one mechanism of combustion instability can occur when acoustic pressure pulsations cause mass flow fluctuations at the fuel ports, resulting in fuel-air ratio fluctuations in the flame zone. If the resulting fuel-air ratio fluctuations and acoustic pressure pulsations have a specific phase behavior (e.g., approximately in phase), a self-exciting feedback loop results. This mechanism, and the magnitude of the resulting combustion dynamics, depends on the delay time between fuel injection and the time the fuel reaches the flame zone, known in the art as the convection time (Tau). Increasing the convection time decreases the frequency of combustion instability, while decreasing the convection time increases the frequency of combustion instability. This results in combustion dynamics that may shorten the useful life of one or more combustor and / or downstream components. For example, combustion dynamics may generate pressure pulses within the fuel nozzle and / or combustion chamber that can adversely affect the high-cycle fatigue life of these components, combustion flame stability, flameholding design margins, and / or undesirable emissions. Alternatively, or additionally, in-phase and coherent combustion dynamics at certain frequencies and sufficient amplitudes may generate undesirable resonant vibrations in the turbine and / or other downstream components. Shifting the frequency of combustion instabilities in one or more combustors from other combustors reduces the coherence of the overall combustion system and reduces coupling between combustors. This reduces the ability of combustor tones to generate oscillatory responses in downstream components, further promoting destructive interference between combustors and reducing the amplitude of combustion dynamics.

[0050] Referring to FIG. 7, a graphical representation 700 of combustor operability is depicted. Specifically, FIG. 7 illustrates a combustor engine tonal dynamics boundary 702 measured taking into account compressor discharge temperature. The x-axis represents compressor discharge temperature, and the y-axis represents combustor operating temperature. To the left of the combustor engine tonal dynamics boundary 702, an avoidance region 704 is depicted. In the avoidance region 704, high combustion system dynamics may result in damage to the gas turbine system hardware and downstream systems. To the right of the combustor engine tonal dynamics boundary 702 is an acceptable dynamics region 706. The tonal dynamics of the acceptable dynamics region 706 are ideal for dry-load operation of the gas turbine system.

[0051] When the EGR exhaust gas is injected into the combustor at a higher temperature and / or a higher flow rate, the compressor discharge temperature increases, i.e., moves to the right. As a result, the gas turbine system's tone dynamics improve from the avoidance region 704 to the acceptable dynamics region 706. This allows the gas turbine system to exhibit improved cold turndown capability while remaining MECL compliant. While inlet bleed heat (IBH) can be used to control tone dynamics, IBH volumetric flow capacity is limited from the perspective of combustor operability. Increasing EGR exhaust gas injection reduces the inlet bleed heat (IBH) requirement, which in turn allows for a more open inlet guide vane (IGV) angle, further improving component loading efficiency and improving life cycle. EGR injection rate and temperature can be monitored and adjusted to act as control effectors for managing combustor operability and maintaining gas turbine system operation within the acceptable dynamics region 906. Thus, EGR may provide additional authority and capacity to maintain higher operating temperatures in the combustor more efficiently than IBH. The controller 214 may utilize information regarding IBH control, etc., to further modify the control of the EGR system 54.

[0052] EGR injection into the compressor is not unlimited. As EGR injection flow rate increases, O2 concentration decreases. Above a critical threshold (shown by line 500 in FIG. 5), the O2 concentration becomes too low to sustain a flame, resulting in a blowout. As a result, EGR injection is limited by the oxygen requirement to maintain flammability. This requires the controller 214 (FIG. 2) to monitor flammability and inject a threshold limit flow rate into the combustor 160 to maintain the flame and improve system efficiency (FIG. 6), while maintaining tone dynamics within the acceptable dynamics region 706 (FIG. 7).

[0053] Referring again to FIG. 3 , the controller 214 (more specifically, the processor 300 operating in conjunction with the memory 302 and / or external / other memory) may affect the control of the EGR system 54 by performing control operations using data received from, for example, any one or more of the sensors 206, 250, 266, 278, and 290. The controller 214 may rely, at least in part, on a model-based control strategy. In one embodiment, sensor data from one or more of the sensors 206, 250, 266, 278, and 290 is transmitted to the controller 214, which is used to initialize the control of the EGR system 54. The controller 214 may rely on a plant or engine model 314 that analyzes the transmitted data. The model 314 may be used by the controller 214 to generate one or more state parameters, which may include estimates of performance parameters. In certain embodiments, the model 314 may be an adaptive real-time engine simulation (ARES) implemented with a Kalman filter. The ARES may be a model suitable for use with a model-based controller for a relatively large industrial gas turbine. In other embodiments, the model 314 may include a recursive filter, a recursive estimator, an adaptive digital filter, an extended Kalman filter, or any other filter, algorithm, device, or method similar to those described herein.

[0054] The state parameters from model 314 may be transmitted to a model-based predictive control module or control module 316. The control module 316 may use the state parameters to perform optimization to determine commands for one or more actuators of the plant or engine. For example, the control module 316 may perform optimization to determine the operating conditions of combustor 160 ( FIG. 2 ) and the amount of EGR capacity in combustor 160 based on the determined operating conditions and, optionally, further taking into account measured EGR characteristics. In this regard, the control module 316 may include an optimizer 318 and a model 320. The model 320 associated with control module 316 may be identical to model 314. In certain embodiments, either or both of model 314 or 320 may be an adaptive real-time engine simulation (ARES) implemented with a Kalman filter. The use of either or both of model 314 or 320 enables optimization of EGR exhaust gas injection.

[0055] In use, embodiments of the present invention may be used to initialize model 314 or 320 at start-up. Additionally, embodiments of the present invention may be used to re-initialize the dynamics state of model 314 or 320 after some event, such as a load dump or sensor failure. Other embodiments of the present invention may be used to initialize the dynamics state of other types of machines or devices in other situations.

[0056] FIG. 8 is a flowchart of a method for conditioning exhaust gas from an exhaust gas recirculation (EGR) system to heat an airflow at the inlet of a combustor of a gas turbine system, according to one embodiment. Method 800 includes determining 802 an EGR injection capacity for a combustor of the gas turbine system based on sensed operating characteristics. The sensed operating characteristics may include one or more characteristics measured by a sensor. For example, as depicted in FIG. 3 , one or more characteristics 312 are measured by sensors 206, 250, 266, 278, and 290. One or more data transmission streams including data 310 are sent to wired or wireless interface 306 of controller 214. Controller 214 processes the received data 310, for example, using model 314 or 320, and generates / determines control instructions to affect the operation of the EGR system. Method 800 further includes step 804 of adjusting one or more components of the EGR system, such as one or more dampers, based on the determined EGR injection capacity to maintain part-load efficiency within a part-load operating threshold and maintain base-load efficiency within a base-load operating threshold while maximizing the temperature at the inlet of the combustor. Adjustment 804 may be performed by transmitting the determined control commands to various components in the system, such as one or more of motors 208, 212, 226, 246, 256, and / or 260, to adjust associated dampers 202, 210, 224, 240, 244, 256, and / or 258. The resulting adjustments cause the EGR system to inject EGR gases into the inlet of the combustor at a desired flow rate. Controller 214 continues to monitor one or more characteristics 312 and generate control commands to further affect operation of the EGR system to maximize system performance and system efficiency while maintaining the gas turbine engine within an acceptable dynamics region.

[0057] Hereinafter and in the claims, "EGR" may also be used as an abbreviation for exhaust gas recirculation.

[0058] Hereinafter and in the claims, "IBH" may also be used as an abbreviation for inlet bleed heat.

[0059] Hereinafter and in the claims, "ARES" may also be used as an abbreviation for Adaptive Real-Time Engine Simulation.

[0060] Hereinafter and in the claims, "MECL" may also be used as an abbreviation for Minimum Emissions Compliance Load.

[0061] Further aspects of the invention are provided by one or more of the following embodiments.

[0062] Embodiment 1. A gas turbine system comprising: a combustor configured to receive and combust a fuel with an oxidizer, a turbine driven by combustion products from the combustor, a compressor configured to compress the oxidizer and supply it to the combustor, an exhaust gas recirculation (EGR) system configured to recirculate exhaust gases along an exhaust gas recirculation path from the turbine to an inlet of the compressor, and an inlet sensor disposed adjacent to the inlet of the compressor and configured to sense one or more characteristics at the inlet; and a control system comprising: one or more dampers disposed along the exhaust gas recirculation path and operable between open and closed positions; and a controller in communication with the inlet sensor configured to receive sensor data related to the one or more characteristics sensed at the inlet and to operate at least one of the one or more dampers based on the received sensor data to control a temperature at the inlet of the compressor. In a more specific embodiment, the exhaust gas recirculation system may be configured to recirculate exhaust gases from an exhaust outlet of the turbine section.

[0063] Embodiment 2. The system of embodiment 1, wherein the exhaust gas recirculation path comprises an outlet in fluid communication with the inlet of the compressor, and wherein the one or more dampers comprise an EGR outlet damper disposed between the outlet of the exhaust gas recirculation path and the inlet of the compressor.

[0064] Embodiment 3. The system of embodiment 2, wherein the EGR system includes an EGR sensor disposed along the exhaust gas recirculation path, the EGR sensor configured to detect a characteristic of the exhaust gas, the EGR sensor disposed between the exhaust gas compressor and the outlet damper, and the EGR sensor configured to transmit sensor data to the controller.

[0065] Embodiment 4. The system of embodiment 3, further comprising an EGR vent disposed between the EGR sensor and the EGR outlet damper, and a vent damper in fluid communication with the EGR vent to selectively vent exhaust gases from the exhaust gas recirculation path.

[0066] Embodiment 5. A system described in any one or more of embodiments 1 to 4, wherein the one or more characteristics sensed at the inlet include one or more of the temperature, moisture content, flow rate, or pressure of the air flow at the inlet, and the controller is configured to adjust at least one of the one or more dampers in response to the sensed one or more characteristics.

[0067] Embodiment 6. The system of any one or more of embodiments 1-5, wherein the controller comprises a processor in electrical communication with a memory storing instructions, the instructions being executable by the processor to operate one or more dampers to maximize compressor inlet temperature while maintaining part load efficiency within a part load operating threshold and maintaining base load efficiency above a minimum emissions compliant load (MECL).

[0068] Embodiment 7. The system of any one or more of embodiments 1-6, wherein the controller is further configured to maintain at least a threshold oxidant level at the inlet of the compressor taking into account exhaust gases introduced to the inlet by the EGR system, the threshold oxidant level being based on combustor specification requirements.

[0069] Embodiment 8. The system of any one or more of embodiments 1 to 7, wherein the controller is further configured to maintain at least a threshold oxidizer level at the inlet while determining a maximum injectable amount of exhaust gas from the EGR system to the inlet, and wherein actuating at least one of the one or more dampers is performed taking into account the determined maximum injectable amount of exhaust gas.

[0070] Embodiment 9. A system described in any one or more of embodiments 1 to 8, wherein the controller is configured to process the received sensor data and generate control instructions taking into account the processed sensor data, and wherein the controller is configured to process the received sensor data using an adaptive real-time engine simulation (ARES).

[0071] In combination with any of the above-described embodiments, the controller may be further configured to determine an EGR injection capacity based at least in part on the sensor data, the EGR injection capacity defining a maximum injectable amount of exhaust gas from the EGR system to the inlet of the compressor while maintaining at least a threshold oxidant level at the inlet, and the adjustment of the position of at least one of the one or more dampers is performed taking into account the determined EGR injection capacity. The EGR injection capacity may be determined taking into account inlet bleed heat control.

[0072] Further in combination with any of the above-described embodiments and / or the system described in the preceding paragraph, the controller may be further configured to determine an exhaust gas recirculation, i.e., EGR, injection capacity based at least in part on the sensor data, the exhaust gas recirculation, i.e., EGR, injection capacity defining a maximum injectable amount of exhaust gas from the exhaust gas recirculation, i.e., EGR, system, to the compressor inlet while maintaining at least a threshold oxidant level at the inlet, and wherein adjustment of the position of at least one of the one or more dampers is made taking into account the determined exhaust gas recirculation, i.e., EGR, injection capacity.

[0073] Embodiment 10. A non-transitory computer-readable medium storing instructions that, when executed, cause a method of adjusting an exhaust gas recirculation, or EGR, system to inject exhaust gas into an inlet of a compressor of a gas turbine system, the method including: receiving, in a controller of the gas turbine system, sensor data from an inlet sensor, the sensor data including one or more of a temperature, humidity, flow rate, or pressure of a fluid at the inlet; processing, by a processor of the controller, the sensor data received from the inlet sensor to determine current operating characteristics at the inlet; determining, by the processor, an EGR injection capacity based on the current operating characteristics at the inlet, the EGR injection capacity defining a maximum injectable amount of exhaust gas from the EGR system into the inlet of the compressor; and controlling, by the processor, one or more dampers associated with the EGR system to adjust the amount of exhaust gas injected into the inlet based on the determined EGR injection capacity.

[0074] Embodiment 11. The non-transitory computer-readable medium of embodiment 10, wherein processing the sensor data includes using Adaptive Real-Time Engine Simulation (ARES).

[0075] Embodiment 12. A non-transitory computer-readable medium as described in any one or more of embodiments 10 or 11, wherein the method further includes receiving, at the controller, sensor data from an EGR sensor disposed along an exhaust gas recirculation path of the EGR system, the EGR sensor being configured to detect characteristics of exhaust gases in the exhaust gas recirculation path; processing, by a processor, the sensor data received from the EGR sensor to determine current characteristics in the exhaust gases; and further determining, by the processor, an EGR injection capacity based on the current characteristics of the exhaust gases.

[0076] Embodiment 13. The non-transitory computer-readable medium of embodiment 12, wherein the sensor data received at the controller from the EGR sensor includes one or more of temperature, humidity, pressure, or flow rate.

[0077] Embodiment 14. A non-transitory computer-readable medium according to any one or more of embodiments 12 or 13, wherein the exhaust gas recirculation path comprises an outlet in fluid communication with an inlet of the compressor, and wherein the one or more dampers comprise an outlet damper disposed between the outlet of the exhaust gas recirculation path and the inlet of the compressor, and wherein controlling the one or more dampers comprises adjusting the outlet damper to control a volumetric flow of exhaust gas injected into the inlet to achieve the EGR injection capacity determined by the processor.

[0078] Embodiment 15. The non-transitory computer-readable medium of embodiment 14, wherein the exhaust gas recirculation path further comprises an EGR vent disposed between the EGR sensor and the outlet damper, and wherein controlling the one or more dampers comprises controlling the vent damper to adjust the leakage of exhaust gas from the EGR system through the EGR vent, and wherein adjusting the leakage of exhaust gas is based on the volumetric flow of exhaust gas injected into the inlet.

[0079] Embodiment 16. A non-transitory computer-readable medium described in any one or more of embodiments 12 to 15, wherein controlling one or more dampers includes actuating corresponding motors coupled to the one or more dampers to reposition the orientation of the one or more dampers, thereby adjusting the flow rate of exhaust gas to the inlet.

[0080] Additionally, any method performed upon execution of instructions stored on any non-transitory computer-readable medium as set forth in the above embodiments of the non-transitory computer-readable medium is disclosed. The gas turbine system may, in certain embodiments, be a gas turbine system of the system described in the above embodiments.

[0081] Embodiment 17. A non-transitory computer-readable medium as described in any one or more of embodiments 12 to 16, wherein determining the EGR injection capacity is performed with further consideration of maintaining part load efficiency within part load operating thresholds while maximizing the temperature at the inlet and maintaining a minimum emissions compliant load.

[0082] Embodiment 18. A method for adjusting exhaust gas from an exhaust gas recirculation (EGR) system to heat an airflow at an inlet of a compressor of a gas turbine system, the method comprising: determining an EGR injection capacity for an inlet of the compressor of the gas turbine system based on sensed operating characteristics of the airflow at the inlet, the EGR injection capacity defining a maximum injectable amount of exhaust gas from the EGR system of the gas turbine system into the inlet of the compressor while maintaining at least a threshold oxidant level at the inlet; and adjusting one or more dampers of the EGR system based on the determined EGR injection capacity to maximize the temperature at the inlet of the compressor while maintaining part load efficiency within a part load operating threshold and maintaining base load efficiency within a base load operating threshold.

[0083] Embodiment 19. The method of embodiment 18, wherein the sensed operating characteristic includes one or more of temperature, humidity, flow rate, or pressure, and wherein adjusting the one or more dampers is further based on sensor data from an EGR sensor positioned along an exhaust gas recirculation path of the EGR system, the EGR sensor configured to detect characteristics of exhaust gases in the exhaust gas recirculation path.

[0084] Embodiment 20. The method of any one or more of embodiments 18 or 19, wherein determining the EGR injection volume includes inputting sensed operating characteristics into an adaptive real-time engine simulation.

[0085] Embodiment 21. The method of any one or more of embodiments 18-20, wherein determining the EGR injection capacity is performed with further consideration of maintaining part load efficiency within part load operating thresholds and maintaining MECL while maximizing the temperature at the inlet.

[0086] This written description discloses the invention, including the best mode, and uses examples to enable any person skilled in the art to practice the invention, including making and using any device or system, and performing any incorporated methods. The scope of the invention as claimed herein is defined by the claims, and may include other examples other than those outlined above. [Explanation of symbols]

[0087] 10 Systems 42 Exhaust gas 52 Gas Turbine System 54 Exhaust Gas Recirculation (EGR) System, Exhaust Gas (EG) Treatment System 56 Heat Recovery Steam Generator (HRSG) 58 Exhaust Gas Recirculation (EGR) System 66 Exhaust Gas 68 Oxidizing Agents 70 fuel 76 Extraction point 78 Exhaust Gas Supply System 106 Machinery 110 Exhaust gas recirculation path 150 Gas Turbine Engine 152 Compressor section, compressor 154 Combustor section, combustor 156 Expander section, turbine section, turbine 158 Compressor Stage 160 Combustor 162 Rotation axis 164 Premixed fuel nozzle, diffusion fuel nozzle 166 Head end 168 Combustion section, combustion chamber 170 Compressed Streams 172 Combustion Products 174 Turbine Stage 176 Shaft 178 Machinery 180 Machinery 182 exhaust outlet 184 Exhaust inlet 186 Oxidizer Compression System 188 Oxidizer Compressor 190 Drive Unit 192 Exhaust Gas (EG) Treatment Components 194 Exhaust Gas (EG) Treatment Components 196 Exhaust Gas (EG) Treatment Components 198 Exhaust Gas (EG) Treatment Components 200 (EGR system) inlet 202 Damper 204 Flue 206 Continuous Emissions Monitoring System (CEMS), Sensors 208 Motor 210 Flue damper 212 Motor 213 Line 214 Controller 215 Heat exchanger 216 Carbon Capture and Storage (CCS) Systems 217 Line 218 Blowdown Line 220 Exhaust gas recirculation path 222 Flue gas outlet 224 Damper 226 Motor 228 Conditioning Components 230 EGR blower, recycle blower, exhaust gas compressor 232 EGR cooler 234 EGR recirculation loop 236 Entrance 238 Exit 240 Damper 242 Motor 244 Damper 246 Motor 248 Drain 250 Exhaust Gas Recirculation Sensor 252 Exhaust Gas Recirculation (EGR) Vent 254 Ventilation damper 256 Motor, Damper 258 Exhaust Gas Recirculation (EGR) Outlet Damper 260 motor 262 (Exhaust gas recirculation path) outlet 264 Entrance 266 Oxidant Sensor 268 Preburner Section 270 Inlet Filter 272 Evaporative Aerosol Control System (EVAP) 274 Drift Eliminator 276 EGR mixer 278 Inlet Sensor 280 routes 282 First Segment 284 Second Segment 286 Drain 288 Duct Burner 290 Sensors 300 processors 302 memory 304 Computer Readable Instructions 306 Wired or Wireless Interface 308 Wired Connection 310 Data 312 Characteristics 314 model 316 Control Module 318 Optimizer 320 model 400 lines 402 line 404 line 406 line 408 line 410 line 412 Vertical Line 414 Section Section 416 500 lines 502 line 504 line 506 line 508 line 600A relative load 600B relative load 600C relative load 602 line 602A line 602B line 602C line 700 Graphical Representation 702 Tone Dynamics Boundary of Combustor Engine 704 Avoidance area 706 Acceptable Dynamics Region 800 ways 906 Dynamics Area

Claims

1. A gas turbine system (52), comprising: a compressor (152) configured to compress the oxidant (68); a combustor (154) configured to receive fuel (70) and combust it with said oxidant (68); a turbine (156) driven by combustion products (172) from said combustor (154); an exhaust gas recirculation system (54) configured to recirculate at least a portion of the exhaust gases (66) from the turbine (156) along an exhaust gas recirculation path (110) from the turbine (156) to an inlet (184) of the compressor (152); and a gas turbine system including an inlet sensor disposed adjacent to the inlet of the compressor and configured to detect one or more characteristics at the inlet of the compressor; 1. A control system comprising: one or more dampers (202, 210, 224, 240, 244, 254, 258) disposed along the exhaust gas recirculation path (110) and operable between an open position and a closed position; and in communication with said inlet sensor (278); receiving sensor data from the inlet sensor (278) relating to a characteristic detected at the inlet (184) of the compressor (152); and a control system including a controller (214) configured to adjust a position of at least one of the one or more dampers (202, 210, 224, 240, 244, 254, 258) based on the received sensor data to control the amount of exhaust gas (66) injected into the compressor (152); A system (10) comprising:

2. 2. The system of claim 1, wherein the exhaust gas recirculation path comprises an outlet in fluid communication with the inlet of the compressor, and the one or more dampers comprise an exhaust gas recirculation outlet damper disposed at the outlet of the exhaust gas recirculation path to control injection of exhaust gas into the inlet of the compressor.

3. 3. The system of claim 2, wherein the exhaust gas recirculation system comprises an exhaust gas recirculation sensor disposed along the exhaust gas recirculation path, the exhaust gas recirculation sensor configured to detect a characteristic of the exhaust gas, the exhaust gas recirculation sensor disposed between an exhaust gas compressor and the exhaust gas recirculation outlet damper, and the exhaust gas recirculation sensor configured to transmit sensor data to the controller.

4. an exhaust gas recirculation vent (252) located upstream of the exhaust gas recirculation outlet damper (258); a vent damper (254) in fluid communication with the exhaust gas recirculation vent (252) for selectively venting exhaust gas (66) from the exhaust gas recirculation path (110) in accordance with instructions received from the controller (214); The system (10) of claim 2 further comprising:

5. 2. The system (10) of claim 1, wherein the sensed characteristic at the inlet (184) comprises one or more of a temperature, a moisture content, a flow rate, or a pressure of the airflow at the inlet (184), and the controller (214) is configured to adjust at least one of the one or more dampers (202, 210, 224, 240, 244, 254, 258) in response to the sensed one or more characteristics.

6. 6. The system of claim 1, wherein the controller comprises a processor in electrical communication with a memory that stores instructions, the instructions being executable by the processor to adjust the position of the one or more dampers to maximize a temperature at the inlet of the compressor while maintaining a part load efficiency within a part load operating threshold and a base load efficiency above a minimum emissions compliant load.

7. receiving sensor data from an inlet sensor at a controller of a gas turbine system, the sensor data including one or more of a temperature, humidity, flow rate, or pressure of a fluid at the inlet; receiving, the gas turbine system including an exhaust gas recirculation system configured to recirculate at least a portion of exhaust gas from a turbine of the gas turbine system along an exhaust gas recirculation path from the turbine to an inlet of a compressor; processing, by a processor (300) of the controller (214), the sensor data received from the inlet sensor (278) to determine current operating characteristics at the inlet (184) of the compressor (152) of the gas turbine system (52); determining, by the processor (300), an exhaust gas recirculation injection volume based on the current operating characteristics and an inlet bleed heat or IBH control at the inlet (184) of the compressor (152), the exhaust gas recirculation injection volume defining a maximum injectable amount of the exhaust gas (66) from the exhaust gas recirculation system (54) to the inlet (184) of the compressor (152); and controlling, by the processor (300), one or more dampers (202, 210, 224, 240, 244, 254, 258) associated with the exhaust gas recirculation system (54) to adjust the amount of the exhaust gas (66) injected into the inlet (184) of the compressor (152) based on the determined exhaust gas recirculation injection volume. A method comprising:

8. The method of claim 7 , wherein processing the sensor data includes using an adaptive real-time engine simulation.

9. receiving, at the controller (214), sensor data from an exhaust gas recirculation sensor (250) disposed along an exhaust gas recirculation path (110) of the exhaust gas recirculation system (54), the exhaust gas recirculation sensor (250) configured to detect a characteristic of the exhaust gas (66) in the exhaust gas recirculation path (110); processing, by the processor (300), the sensor data received from the exhaust gas recirculation sensor (250) to determine current characteristics of the exhaust gas (66); and and further determining, by the processor (300), the exhaust gas recirculation injection volume based on the current characteristics of the exhaust gas (66). The method of claim 7 further comprising:

10. The method of claim 9, wherein the sensor data received at the controller from the exhaust gas recirculation sensor includes one or more of temperature, humidity, pressure, or flow rate.

11. 10. The method of claim 9, wherein the exhaust gas recirculation path comprises an outlet in fluid communication with the inlet of the compressor, the one or more dampers comprise an outlet damper disposed between the outlet of the exhaust gas recirculation path and the inlet of the compressor, and controlling the one or more dampers comprises adjusting the outlet damper to control a volumetric flow of exhaust gas injected into the inlet to achieve the exhaust gas recirculation injection capacity determined by the processor.

12. 12. The method of claim 11, wherein the exhaust gas recirculation path further comprises an exhaust gas recirculation vent disposed between the exhaust gas recirculation sensor and the outlet damper, and controlling the one or more dampers comprises controlling a vent damper to adjust leakage of exhaust gas from the exhaust gas recirculation system through the exhaust gas recirculation vent, and adjusting the leakage of exhaust gas based on a volumetric flow of exhaust gas injected into the inlet.

13. 8. The method of claim 7, wherein controlling the one or more dampers comprises actuating a corresponding motor coupled to each of the one or more dampers to reorient the one or more dampers to adjust a flow of exhaust gas to the inlet.

14. 10. The method of claim 9, wherein determining the exhaust gas recirculation injection volume is performed with further consideration of maintaining part load efficiency within a part load operating threshold to maintain a minimum emissions compliant load while maximizing temperature at the inlet.

15. A non-transitory computer readable medium storing instructions that, when executed, cause the method of any one of claims 7 to 14 to be performed.

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