Systems and methods for extended emissions compliant operation of gas turbine engines - Patents.com

Abstract

To provide emissions compliant operation of a combustor of a gas turbine engine below a conventional minimum emissions compliance load when the electric power demand decreases and a power grid operator requests reduced power generation.SOLUTION: A method of operating a rotary machine below a minimum emissions compliance load includes reducing a fuel split to zero. The fuel split apportions a total flow of fuel to a combustor between a first combustion zone and a second combustion zone. The method also includes determining a current operating temperature of the first combustion zone using a digital simulation of the rotary machine. The method further includes determining a target operating temperature of the first combustion zone. The target operating temperature enables the rotary machine to operate below a conventional minimum emissions compliance load while still in compliance with emissions standards. The method also includes channeling a first flow of fuel to the first combustion zone. The first flow of fuel decreases the temperature of the first combustion zone to the target operating temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The field of this disclosure relates generally to control of gas turbine engines, and more particularly, to controlling extended emissions compliant loads of gas turbine engines. [Background technology]

[0002] In at least some known rotary machines, energy extracted from a gas stream in a turbine is used to power a mechanical load. Specifically, the rotary machine includes a compressor section, a combustor section, and a turbine section arranged in a serial flow arrangement. The compressor section compresses air for combustion with a fuel in the combustor section, and the turbine section extracts energy from combustion gases generated in the combustor section. At least some known combustor sections include an axial fuel staging (AFS) technique that includes axial (sequential) staging of combustion in at least two zones. More specifically, the combustor section can include a plurality of first stage fuel nozzles disposed upstream of a plurality of second stage fuel nozzles. A first fuel stream is directed to the combustor by the first stage fuel nozzles, and a second fuel stream is directed to the combustor by the second stage fuel nozzles. The temperature in the combustor of the combustion gases generated by combustion of the first fuel stream is T 3.5 is the temperature. T 3.5 By controlling the temperature and air from the compressor section, an operator can control the exhaust gases produced by the rotary machine. More specifically, carbon monoxide exhaust gases produced by rotary machines are typically generated by the T 3.5 It is controlled by controlling the temperature.

[0003] Further, rotating machines typically have a minimum emission compliance load (MECL), which is the lowest load at which the rotating machine can operate while still complying with emission standards. More specifically, a conventional MECL is the lowest load of a rotating machine at which combustor temperatures facilitate maintaining compliance with emission standards. When a power grid operator requests an operator of a rotating machine to reduce operation of the rotating machine such that the rotating machine is operating below the MECL, the rotating machine operator turns off the rotating machine to maintain compliance with emission standards. Thus, a rotating machine with a high MECL shuts down operation of the rotating machine more frequently than a rotating machine with a low MECL, resulting in lost revenue for the operator of the high MECL rotating machine. Summary of the Invention

[0004] In one aspect, a method is provided for operating a rotary machine below a minimum emission compliant load in a responsive mode. The rotary machine includes a combustor including a first combustion zone and a second combustion zone. The method includes: i) reducing a fuel split to zero. The fuel split apportions a total flow of fuel to the combustor between the first and second combustion zones. The method also includes: ii) determining a current operating temperature of the first combustion zone using a digital simulation of the rotary machine. The method further includes: iii) determining a target operating temperature of the first combustion zone. The target operating temperature allows the rotary machine to operate below a conventional minimum emission compliant load (MECL) while still complying with emission standards. The method also includes: iv) directing a first fuel flow to the first combustion zone. The first fuel flow reduces the temperature of the first combustion zone to the target operating temperature. The method further includes: v) repeating steps i through iv until the rotary machine operates below a conventional MECL and complies with emission standards.

[0005] In another aspect, a method is provided for operating a rotary machine below a minimum emission compliant load in a standby mode. The rotary machine includes a combustor including a first combustion zone and a second combustion zone. The method includes: i) reducing a fuel split to zero. The fuel split apportions a total flow of fuel to the combustor between the first and second combustion zones. The method also includes: ii) determining a current operating temperature of the first combustion zone using a digital simulation of the rotary machine. The method further includes: iii) determining a target operating temperature of the first combustion zone. The target operating temperature allows the rotary machine to operate below a conventional minimum emission compliant load (MECL) while still complying with emission standards. The method further includes: iv) directing a first fuel flow to the first combustion zone. The first fuel flow reduces the temperature of the first combustion zone to the target operating temperature and reduces the temperature of exhaust gases from the rotary machine below a minimum exhaust temperature for operation of the power plant. The method also includes v) repeating steps i through iv until the rotating machine is operating below the conventional MECL and in compliance with the emissions standard.

[0006] In yet another aspect, a rotary machine is provided. The rotary machine includes a compressor configured to compress a flow of intake air, a combustor, and a computing device. The combustor includes a first combustion zone, a second combustion zone, at least one first fuel nozzle, and at least one second fuel nozzle. The at least one first fuel nozzle is configured to direct a first fuel flow to the first combustion zone, and the at least one second fuel nozzle is configured to direct a second fuel flow to the second combustion zone. The combustor is configured to receive the flow of intake air. The fuel split is a percentage of a total flow of fuel that is directed to the second combustion zone. The computing device includes a digital simulation of the rotary machine and is configured to operate the rotary machine in a responsive mode. The computing device is configured to reduce the fuel split to zero and determine a current operating temperature of the first combustion zone using the digital simulation of the rotary machine. The computing device is also configured to determine a target operating temperature of the first combustion zone. The target operating temperature allows the rotary machine to operate below a conventional minimum emission compliant load (MECL) while still complying with emission standards. The computing device is further configured to direct a first fuel flow to the first combustion zone. The first fuel flow reduces a temperature of the first combustion zone to the target operating temperature. The computing device is also configured to repeat until the rotary machine operates below a conventional MECL and complies with emission standards.

[0007] These and other features, aspects, and advantages of the present disclosure will become 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 description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an exemplary rotating machine. [Figure 2A] 2 is a flow diagram of an exemplary method of emissions compliant operation of the rotary machine shown in FIG. 1 below a conventional MECL. [Figure 2B] 2B is a continuation of the flow chart of FIG. 2A. [Figure 2C]2A and 2B. [Figure 2D] 2A, 2B, and 2C. [Diagram 3] 2 is a graph of an example relationship between exhaust temperature and electrical load of the rotary machine shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Unless otherwise indicated, the drawings provided herein are intended to illustrate features of embodiments of the present disclosure. These features are believed to be applicable in a wide variety of systems that include one or more embodiments of the present disclosure. Thus, the drawings are not intended to include all conventional features known to those skilled in the art as being required for the practice of the embodiments disclosed herein.

[0010] In the following specification and claims, reference will be made to a number of terms that shall be defined to have the following meanings.

[0011] The singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0012] Unless otherwise specified, approximation terms such as "generally," "substantially," and "approximately" used herein indicate that the term so modified may only be applied to an approximate degree as recognized by a person skilled in the art, and not to an absolute or complete degree. Thus, values ​​modified with one or more terms such as "approximately," "about," and "substantially" should not be limited to the exact value specified. In at least some instances, approximation terms may correspond to the precision of an instrument for measuring the value. Range limits may be specified here and throughout this specification and claims. Such ranges are combinable and / or interchangeable, and include all subranges contained therein, unless the context or language indicates otherwise. Furthermore, unless otherwise indicated, terms such as "first," "second," and the like are used herein merely as labels and do not impose any order, position, or hierarchical requirements on the items to which they refer. Moreover, reference to, for example, a "second" item does not require or exclude the presence of, for example, a "first" or lower-numbered item, or a "third" or higher-numbered item.

[0013] As used herein, the terms "axial" and "axially" refer to directions and orientations that extend substantially parallel to the longitudinal axis of the rotary machine. Additionally, the terms "radial" and "radially" refer to directions and orientations that extend substantially perpendicular to the longitudinal axis of the rotary machine. Additionally, as used herein, the terms "circumferential" and "circumferentially" refer to directions and orientations that extend in an arc about the longitudinal axis of the rotary machine. Additionally, as used herein, the term "upstream" refers to the forward or inlet end of the rotary machine, and the term "downstream" refers to the aft or exhaust end of the rotary machine. When describing the flow of fluid through a component, the direction from which the fluid flows is described as "upstream" and the direction in which the fluid flows is described as "downstream."

[0014] The methods and systems described herein relate to a method for emissions compliant operation of a combustor of a gas turbine engine below a conventional MECL. More specifically, the gas turbine engine includes a combustor including a first combustion zone, a second combustion zone, at least one first fuel nozzle, and at least one second fuel nozzle. The at least one first fuel nozzle directs a first fuel flow to the first combustion zone and the at least one second fuel nozzle directs a second fuel flow to the second combustion zone. The fuel split is the percentage of the total fuel flow that is directed to the second combustion zone. A digital simulation simultaneously determines a current operating temperature of the first combustion zone and at least one sensor measures a current operating temperature of the combustor exhaust. Additionally, an inlet guide vane controls the flow of air to the combustor. When the demand for the gas turbine engine decreases (i.e., when the power grid operator requests the gas turbine engine operator to reduce power generation), the gas turbine engine operator can place the gas turbine engine in a response mode and / or a standby mode.

[0015] In the responsive mode, the gas turbine engine operator reduces the fuel split to zero (i.e., turns off the second combustion zone) to reduce the combustor's current operating temperature for carbon monoxide emission compliance, and controls the airflow to the combustor using inlet guide vanes to maintain the gas turbine engine's exhaust temperature above a minimum exhaust temperature, typically the minimum exhaust temperature required for operation of a heat exchanger used to operate an associated steam turbine in the power plant. The responsive mode allows the gas turbine engine to continue operating at a reduced, but non-zero, power generation level while maintaining compliance with carbon monoxide emission requirements.

[0016] In standby mode, the gas turbine engine operator reduces the fuel split to zero (i.e., turns off the second combustion zone) to reduce the combustor's current operating temperature for carbon monoxide emission compliance and controls the air flow to the combustor using inlet guide vanes to maintain the combustor exhaust temperature below the minimum exhaust temperature for operation of the power plant's steam generating system. The standby mode allows the gas turbine engine to continue to operate without generating power while maintaining compliance with carbon monoxide emission requirements.

[0017] Both the response mode and the standby mode allow the gas turbine engine to maintain emissions compliant operation during periods of reduced power demand. Thus, when power demand increases and grid operators request more power generation, the gas turbine engine described herein remains operational, i.e., does not require an extended start-up procedure, and is one of the first generators called upon to increase power generation. In some embodiments, the elimination of start-up delays in returning such gas turbine engines to increased power generation increases the revenue of gas turbine engine operators. Thus, the systems and methods described herein provide emissions compliant operation of the combustor of a gas turbine engine below a conventional MECL throughout periods of reduced power demand and grid operators requesting less power generation.

[0018] FIG. 1 is a schematic diagram of an exemplary rotary machine 100, i.e., a turbomachine, and more specifically, a turbine engine. In the exemplary embodiment, rotary machine 100 is a gas turbine engine. Alternatively, rotary machine may be other turbine engines and / or rotary machines, including, but not limited to, a gas turbofan aircraft engine, other aircraft engines. In the exemplary embodiment, gas turbine engine 100 includes an intake section 102, a compressor section 104 coupled downstream from intake section 102, a combustor section 106 coupled downstream from compressor section 104, a turbine section 108 coupled downstream from combustor section 106, and an exhaust section 110 coupled downstream from turbine section 108. Turbine section 108 is coupled to compressor section 104 via a rotor shaft 112.

[0019] It should be noted that, as used herein, the term "couple" is not limited to a direct mechanical, thermal, electrical, and / or flow communication connection between components, but can also include an indirect mechanical, thermal, electrical, and / or flow communication connection between multiple components. In the exemplary embodiment, combustor section 106 includes multiple combustors 114. Combustor section 106 is coupled to compressor section 104 such that each combustor 114 is in flow communication with compressor section 104. Rotor shaft 112 is further coupled to a load 116, such as, but not limited to, a generator and / or a mechanical drive application. In the exemplary embodiment, compressor section 104 and turbine section 108 each include at least one rotor assembly 118 coupled to rotor shaft 112.

[0020] In this embodiment, the intake section 102 includes at least one inlet guide vane 103 controlled by an inlet guide vane controller 105. The inlet guide vane 103 controls the flow of intake air 120 that the intake section 102 directs from the atmosphere to the compressor section 104. Specifically, the inlet guide vane 103 may include a variable or fixed airfoil 107 that directs the intake air 120 to the compressor section 104. Furthermore, the airfoil 107 of the inlet guide vane 103 may be variable, i.e., the angle of the airfoil 107 relative to the compressor section 104 may be changed to change the angle of the flow of the intake air 120 and increase the efficiency of the compressor section 104 during different operating conditions.

[0021] In the exemplary embodiment, the combustors 114 include an axial fuel staging (AFS) technique that includes axial (sequential) staging of combustion in at least two zones. Specifically, one or more of the combustors 114 are axially staged combustors that include a first combustion zone 115, a second combustion zone 117, at least one first fuel nozzle 119, and at least one second fuel nozzle 121. The at least one first fuel nozzle 119 is disposed upstream of the at least one second fuel nozzle 121 and directs a first fuel flow into the first combustion zone 115 correspondingly upstream of the second combustion zone 117. The at least one second fuel nozzle 121 is disposed downstream of the at least one first fuel nozzle 119 and the first combustion zone 115 and directs a second fuel flow into the second combustion zone 117. The first and second combustion zones 115, 117 stage the combustion of the total flow of fuel to the combustors to control combustion dynamics within the combustors 114. In the exemplary embodiment, a single first fuel nozzle 119 and a single second fuel nozzle 121 are shown in FIG. 1 . However, one or more of the combustors 114 may include multiple first fuel nozzles 119 and / or multiple second fuel nozzles 121.

[0022] In an alternative embodiment, combustor 114 is a single stage combustor including multiple combustion zones and multiple nozzle arrays directing fuel to each combustion zone in the single stage combustor. The nozzle array thus stages the fuel flow to the single stage combustor. In another alternative embodiment, rotary machine 100 includes two turbines, a high pressure turbine (not shown) and a low pressure turbine (not shown). The high pressure turbine is disposed between a first combustor (not shown) and a second combustor (not shown), and the low pressure turbine is disposed downstream of the second combustor. The high pressure turbine recovers energy from the combustion gases discharged from the first combustor, which are discharged to the second combustor. The second combustor mixes the combustion gases with fuel and ignites the combustion gases with the fuel. The combustion gases are then discharged from the second combustor to the low pressure turbine, which recovers energy from the combustion gases discharged from the second combustor. In yet another alternative embodiment, combustor 114 includes three or more combustors and / or combustion zones and three or more nozzle arrays.

[0023] The rotary machine 100 also includes a fuel supply system 130 including at least one valve 132 that controls a fuel split of the total flow of fuel. The fuel split corresponds to an allocation of the total fuel flow to the combustor 114 between the first and second fuel flows. In an exemplary embodiment, the fuel split is expressed as a percentage of the total fuel flow that is directed to the at least one second fuel nozzle 121 (i.e., the second fuel flow divided by the sum of the first and second fuel flows). Alternatively, the fuel split may be expressed in any suitable manner. Specifically, the fuel supply system 130 directs the total fuel flow to the combustor 114. More specifically, the fuel supply system 130 directs the total fuel flow to the first fuel nozzle 119 and the second fuel nozzle 121, which in turn direct the total fuel flow to the first combustion zone 115 and the second combustion zone 117, respectively. Valve 132 is controllable to divide the total flow of fuel into a first fuel stream and a second fuel stream according to a selected fuel split.

[0024] Rotary machine 100 further includes a computing device 134 that controls at least one operating parameter of rotary machine 100. More specifically, in the exemplary embodiment, computing device 134 controls the fuel split of the total flow of fuel to combustor 114 by controlling valve 132. Additionally, computing device 134 may also send control signals to inlet guide vane controller 105 and / or directly control inlet guide vanes 103 to control the flow of intake air 120 that is directed to combustor 114. Thus, computing device 134 controls the stoichiometry of the combustion reaction in combustor 114 by controlling both the fuel split and the flow of intake air 120 to combustor 114.

[0025] The computing device 134 is also programmed to perform a digital simulation of the rotating machine 100 to accurately determine at least one temperature within the combustor 114, such as a temperature that is not and / or cannot be directly measured with reliable accuracy. More specifically, the digital simulation may determine a temperature within the combustor 114, such as a temperature that is not directly measured and / or cannot be measured with reliable accuracy, in the absence of direct temperature sensor measurements within the first combustion zone 115 and the second combustion zone 117. 3.5 and T 3.9 Accurately determine temperature. T 3.5 The temperature is the temperature in the combustor 114 axially upstream of the second fuel nozzle 121 and the second combustion zone 117, in the first combustion zone 115. 3.9 The temperature is the temperature within the combustor 114 axially downstream of the secondary fuel nozzle 121, within the secondary combustion zone 117. As will be described in more detail below, the computational device 134 uses digital simulations to determine T 3.5 To control the temperature, the fuel split and the flow of intake air 120 to the combustor 114 are controlled.

[0026] During operation, the intake section 102 channels intake air 120 towards the compressor section 104. The computational device 134 and / or the inlet guide vane controller 105 controls the inlet guide vanes 103 to control the flow of the intake air 120. The compressor section 104 compresses the intake air 120 to a higher pressure and then discharges the compressed air 122 towards the combustor section 106 where it is mixed with fuel (not shown) and combusted to generate hot combustion gases 124. The computational device 134 uses digital simulations to calculate the T 3.5 The fuel split to the first and second fuel nozzles 119, 121 is controlled to control the temperature. The combustion gases 124 are directed downstream towards the turbine section 108 where they impinge on the turbine blades (not shown) and convert thermal energy into mechanical rotational energy that is used to drive the rotor assembly 118 about a longitudinal axis 126. Often the combustor section 106 and the turbine section 108 are referred to as the hot gas section of the turbine engine 100. The exhaust gases 128 are then discharged through the exhaust section 110 to the surrounding atmosphere or to a steam turbine (not shown) if the rotary machine 100 is a gas turbine that is part of a combined cycle power plant.

[0027] 2A, 2B, 2C, and 2D are flow diagrams of an example method 200 of emissions compliant operation of rotating machine 100 below a conventional MECL. FIG. 3 is a graph 300 illustrating the relationship between exhaust temperature of rotating machine 100 and electrical load of rotating machine 100. Method 200 includes step 202 of operating rotating machine 100 in a normal operating mode, i.e., at a load above a minimum emissions compliant load (MECL) 302, to supply power to the power grid. Rotating machine 100 has MECL 302, which is the lowest load of rotating machine 100 at which rotating machine 100 can operate normally as before while still complying with emission standards. More specifically, MECL 302 is a load that is equal to or greater than T 3.5This is the lowest load of the rotary machine 100 at which the temperature is maintained at a temperature that complies with emission standards, both the first combustion zone 115 and the second combustion zone 117 are operating, and the exhaust gas 128 is maintained above the minimum exhaust temperature for operation of the combined cycle power plant.

[0028] The graph 300 includes a number of lines 304, 306, 308, and 310 that indicate potential paths of the rotating machine 100 during operation. Specifically, the graph 300 includes a conventional path 304, an exemplary first response mode path 306, an exemplary second response mode path 308, and an exemplary standby mode path 310. The graph 300 also illustrates a target T 3.5 1. The exhaust temperature line 312 and the target exhaust temperature line 314. The conventional path 304 is the path that is conventionally followed during startup, operation, and shutdown of the rotating machine 100. The first response mode path 306 and the second response mode path 308 are paths that are used to ensure that the rotating machine 100 continues to operate at a reduced power generation level while maintaining compliance with carbon monoxide emission requirements, i.e., at a target T 3.5 3 is an example of a response mode that allows an operator of the rotary machine 100 to reach an operating point that is on the temperature line 312. Specifically, in the response mode, the operator of the rotary machine 100 reduces the fuel split to zero (i.e., turns off the second combustion zone 117) and controls the air flow to the combustor 114 using the inlet guide vanes 103 to reduce the T of the first combustion zone 115 and the combustor 114 along one of the first response mode path 306 and the second response mode path 308, for example, for carbon monoxide emissions compliance. 3.5 The temperature is reduced to maintain the exhaust gas 128 at or above the target exhaust temperature line 314, i.e., the minimum exhaust temperature for operating the power plant at a reduced but non-zero load. The standby mode path 310 allows the rotary machine 100 to continue to operate without generating power while still complying with carbon monoxide emissions requirements. Specifically, in standby mode, the operator of the rotary machine 100 reduces the fuel split to zero (i.e., turns off the second combustion zone) and controls the air flow to the combustor using the inlet guide vanes 103 to reduce the T of the first combustion zone 115 and the combustor 114 for carbon monoxide emissions compliance. 3.5 Lower the temperature, i.e., the target T 3.5An operating point that is on temperature line 312 is reached to maintain exhaust gas 128 below target exhaust temperature line 314, which is the minimum exhaust temperature for operation of the power plant. Both the response and standby modes allow rotary machine 100 to maintain emissions compliant operation during periods of reduced power demand. Thus, when the demand for electricity increases and the grid operator requests more power generation, rotary machine 100 described herein remains operational and will be one of the first generators called upon to increase power generation, increasing revenue for the operator of rotary machine 100. Thus, the systems and methods described herein provide for emissions compliant operation of the combustor of rotary machine 100 below MECL 302 when power demand decreases and the grid operator requests less power generation.

[0029] Method 200 also includes receiving 204 a request to reduce power generation below MECL 302. In an exemplary embodiment, a controller of the power grid determines that excess electricity is being generated and requests that one or more generators reduce the production of power. In an alternative embodiment, rather than receiving a request to reduce power generation, rotating machine 100 may be requested to reduce power generation for other reasons, such as, but not limited to, emergency situations and / or maintenance requirements related to rotating machine 100, the combined cycle power plant, and / or the power grid.

[0030] The method 200 further includes a step 206 of reducing the fuel split to zero. An operator of the rotary machine 100 reduces the fuel split to zero to stop combustion in the second combustion zone 117. The first fuel nozzle 119 continues to direct the first fuel flow into the first combustion zone 115 while the second fuel nozzle 121 stops directing the second fuel flow into the second combustion zone 117. More specifically, the computing device 134 controls the valve 132 to reduce the second fuel flow to zero while maintaining the first fuel flow. Thus, the first combustion zone 115 is the only combustion zone in operation and the total flow of fuel is not staged to control the combustion dynamics in the combustor 114. In an alternative embodiment, the T 3.5The first fuel flow to the first combustion zone 115 is also reduced to control the temperature.

[0031] The method 200 also includes operating 208 the rotary machine 100 in a response mode, such as a first response mode 306 and / or a second response mode 308. In the response mode, an operator of the rotary machine 100 reduces the fuel split to zero (i.e., turns off the second combustion zone) and controls the air flow to the combustor 114 using the inlet guide vanes 103 to adjust the T of the first combustion zone 115 and the combustor 114 for carbon monoxide emissions compliance. 3.5 The temperature is reduced to maintain the exhaust gases 128 at or above the minimum exhaust temperature for the power plant operation. The rotary machine 100 then begins to operate along a first response mode path 306, for example, as shown in graph 300. As shown in graph 300, the first response mode path 306 deviates from the conventional path 304 because the second combustion zone 117 is turned off and the combustor temperature is controlled by manipulation of the combustor inlet airflow. More specifically, the second combustion zone 117 is turned off and the inlet guide vanes are used to control the T 3.5 Temperature is controlled so that the exhaust temperature and T 3.5 Temperature drops. Therefore, load, exhaust temperature, and T 3.5 The temperature is simultaneously reduced along a first response mode path 306 that is different from the conventional path 304 .

[0032] A step 208 of operating the rotating machine 100 in a responsive mode includes determining the current operating T of the first combustion zone 115 using a digital simulation of the rotating machine 100. 3.5The digital simulation includes a step 210 of determining the temperature in the combustor 114. The digital simulation is a model of the rotating machine 100. Specifically, the digital simulation is any suitable model that accurately determines the operating conditions of multiple operating parameters within the rotating machine 100 in real time during operation of the rotating machine 100 based on control inputs to the computing device 134 and / or feedback from suitable sensors (not shown) located throughout the rotating machine 100. More specifically, the digital simulation is a thermodynamic and fluid dynamic model that accurately determines the operating conditions of multiple operating parameters within the rotating machine 100 in real time during operation of the rotating machine 100. The multiple operating parameters that the digital simulation determines include, among many other parameters, the T in the combustor 114, which typically cannot be directly measured by sensors in the combustion zone. 3.5 and T 3.9 Thus, the digital simulation can be performed to measure the T 3.5 and T 3.9 The determining step 210 may be performed continuously while other steps of the method 200 are performed simultaneously. In an alternative embodiment, the current operating temperature T of the first combustion zone 115 is determined. 3.5 The step of determining 210 the temperature may be performed by determining the current operating temperature T of the first combustion zone 115 using a non-physically based model of the rotating machine 100, such as a state variable model or a neural network. 3.5 A step 210 of determining a temperature may be included.

[0033] The step 208 of operating the rotating machine 100 in the response mode is performed by setting a target operation T 3.5 In an exemplary embodiment, the step of determining 212 the temperature is 3.5 The step of determining temperature 212 uses a digital simulation to determine the target operating temperature T 3.5 The digital simulation includes a step 212 of determining the actual temperature of the first combustion zone 115 using a digital simulation of the rotating machine 100 to iteratively determine the target operating temperature T 3.5The temperature can be determined. More specifically, the target operation T 3.5 The temperature is determined based on emission standards to ensure that the rotating machine 100 operates in compliance with the emission standards. For example, a target operating temperature T 3.5 The conditions requiring a temperature update may change (i.e., the grid operator may request that rotating machine 100 increase power generation to a level below MECL 302, the ambient temperature, pressure, and / or humidity may change, and / or the fuel temperature may change). For example, the requirements of load 116 may increase or decrease, and thus the operating conditions of rotating machine 100 may change to accommodate the changing requirements of load 116. Specifically, target T 3.5 The operating temperature may vary. However, in an alternative embodiment, the target operating temperature T 3.5 The temperature may be determined by an operator or some other method other than by digital simulation and / or may not be updated iteratively every control cycle. The determining step 212 may be performed continuously while other steps of method 200 are performed simultaneously.

[0034] Operating 208 the rotary machine 100 in a responsive mode includes determining 214 a current temperature of the exhaust gas 128 using at least one sensor (not shown) configured to measure a current operating temperature of the exhaust gas 128. The sensor determines the current temperature of the exhaust gas 128 in real time during operation of the rotary machine 100. Additionally, transmitting the temperature of the exhaust gas 128 to a digital simulation to determine a current operating temperature of the first combustion zone 115. 3.5 Step 210 of determining the temperature and / or the target operation T 3.5 The temperature may be used as an input to determining step 212. Determining step 214 may be performed continuously while other steps of method 200 are performed simultaneously.

[0035] Operating 208 the rotating machine 100 in the responsive mode includes determining 216 a target temperature of the exhaust gases 128. In an exemplary embodiment, determining 216 a target temperature of the exhaust gases 128 includes determining a target operating temperature T 3.5 The method includes determining 216 a target temperature of the exhaust gas 128. The digital simulation and / or computing device 134 may iteratively determine a target temperature of the exhaust gas 128 using the digital simulation and / or computing device 134 of the rotating machine 100, simultaneously with determining 214 a current temperature of the exhaust gas 128. More specifically, the target temperature of the exhaust gas 128 is determined based on a minimum exhaust temperature for operation of the power plant. For example, conditions may change that require the rotating machine 100 to update the target temperature of the exhaust gas 128 to meet load requirements (i.e., a power grid operator requests that the rotating machine 100 increase power generation to a level below the MECL 302). For example, the requirements of the load 116 may increase or decrease, and thus, the operating conditions of the rotating machine 100 may change to accommodate the changing requirements of the load 116. Specifically, the temperature of the exhaust gas 128 may change to accommodate the changing requirements for the load 116. However, in alternative embodiments, the target temperature of the exhaust gas 128 may be determined by an operator or in some other manner (such as a plant controller separate from the rotating machinery controller) rather than by digital simulation and / or computing device 134, and / or may not be updated iteratively every control cycle. The determining step 216 may be performed continuously while other steps of method 200 are performed simultaneously.

[0036] Step 208 of operating the rotating machine 100 in a responsive mode is 3.5 Temperature and target operation T 3.5 The present operation T 3.5 Temperature and target operation T 3.5 If the temperatures are different, the computing device 134 calculates the current operating temperature T 3.5Target temperature T 3.5 Control the first fuel flow and the flow of intake air 120 to vary the temperature. The comparing step 218 may be performed continuously while other steps of the method 200 are performed simultaneously.

[0037] Operating 208 the rotating machine 100 in the responsive mode further includes comparing 220 the current temperature of the exhaust gas 128 to the target temperature of the exhaust gas 128. If the current temperature of the exhaust gas 128 and the target temperature of the exhaust gas 128 differ, the computing device 134 controls the first fuel flow and the flow of the intake air 120 to change the current temperature of the exhaust gas 128 to the target temperature of the exhaust gas 128, as described below. The comparing 220 may be performed continuously while other steps of the method 200 are performed simultaneously.

[0038] A step 208 of operating the rotating machine 100 in a responsive mode includes using the digital simulation and / or computing device 134 to calculate the current operating T 3.5 Target temperature T 3.5 The present invention further includes a step 222 of calculating a target first fuel flow rate that changes the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. In an exemplary embodiment, the digital simulation and / or computing device 134 calculates 222 a target first fuel flow rate that changes the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128 by performing an additional digital simulation of the rotating machine 100. 3.5 Target temperature T 3.5 A target first fuel flow rate may be calculated that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128 .

[0039] A step 208 of operating the rotating machine 100 in a responsive mode includes using the digital simulation and / or computing device 134 to calculate the current operating T 3.5 Target temperature T 3.5In an exemplary embodiment, the digital simulation further includes calculating 224 a target flow rate of the intake 120 that changes the current temperature of the exhaust gases 128 to the target temperature of the exhaust gases 128 by performing an additional digital simulation of the rotating machine 100. 3.5 Target temperature T 3.5 The calculation device may calculate a target intake air 120 flow rate that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. Alternatively, the calculation device may calculate a target intake air 120 flow rate that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. 3.5 Target temperature T 3.5 A target intake air 120 flow rate can be calculated that changes the current temperature of the exhaust gases 128 to a target temperature of the exhaust gases 128 .

[0040] Step 208 of operating the rotating machine 100 in a responsive mode is 3.5 Target temperature T 3.5 The method further includes controlling 226 the first fuel flow and the flow of intake air 120 to change the current temperature of the exhaust gas 128 to the target temperature of the exhaust gas 128. Specifically, the computation device 134 controls the valve 132 to control the first fuel flow and the inlet guide vane 103 to control the flow of the intake air 120. The computation device 134 controls the valve 132 to adjust the first fuel flow to the target first fuel flow rate and the control inlet guide vane 103 to adjust the flow of the intake air 120 to the target flow rate of the intake air 120. The computation device 134 and the digital simulation control the flow of the intake air 120 and the first fuel flow to the first combustion zone 115 to control the stoichiometry of the first combustion zone 115. 3.5 Temperature is the target operating temperature T 3.5 After the target temperature of the exhaust gas 128 is changed to the target exhaust gas 128 temperature and the operating conditions of the rotating machine 100 change, the digital simulation and / or calculation device 134 repeats the method 200 as necessary to maintain compliance with emissions requirements and to maintain the temperature of the exhaust gas 128 at or above the minimum exhaust temperature for operation of the power plant.

[0041] As shown in graph 300, an exemplary second response mode path 308 extends from the first response mode path 306 and may be used, for example, when the temperature of the intake air 120 flow is relatively high. More specifically, for example, when the temperature of the intake air 120 flow is greater than 80° F., the second response mode path 308 may be followed by a target burner tube speed of the first fuel nozzle 119. For example, the target burner tube speed is a burner tube speed above which a flame from the first fuel nozzle 119 is pushed into the first combustion zone 115 to avoid flashback or auto-ignition.

[0042] The method 200 also includes a step 228 of operating the rotary machine 100 in a standby mode. In the standby mode, the rotary machine 100 operator reduces the fuel split to zero (i.e., turns off the second combustion zone) and controls the air flow to the combustor 114 using the inlet guide vanes 103 to reduce the T of the first combustion zone 115 and the combustor 114 for carbon monoxide emissions compliance. 3.5 The temperature is reduced to maintain the exhaust gas 128 below a minimum exhaust temperature for the operation of the power plant, e.g., for the operation of a heat exchanger used to generate steam for a steam turbine from the residual heat in the exhaust gas 128. The operator operates the rotary machine 100 in a standby mode rather than a response mode because the grid operator has requested the operator to generate less power than in the response mode. In some embodiments, the rotary machine 100 operates in the response mode first, and then further reduces power generation by operating in the standby mode in response to a subsequent request from the grid operator to reduce power generation. The rotary machine 100 then begins to operate, for example, along a standby mode path 310 shown in graph 300. As shown in graph 300, the standby mode path 310 deviates from the conventional path 304 because the second combustion zone 117 is turned off and the combustor temperature is controlled by the manipulation of the combustor inlet airflow. More specifically, the second combustion zone 117 is turned off and the inlet guide vanes 103 are used to reduce the T 3.5 Temperature is controlled so that the exhaust temperature and T 3.5 Temperature drops. Therefore, load, exhaust temperature, and T 3.5The temperature simultaneously drops along a standby mode path 310 that is different from the conventional path 304 .

[0043] The step 228 of operating the rotating machine 100 in a standby mode includes determining the current operating T of the first combustion zone 115 using a digital simulation of the rotating machine 100, as described above in the step 210 of determining. 3.5 The method includes determining the temperature 230. The determining step 230 may be performed continuously while other steps of the method 200 are performed simultaneously.

[0044] The step 228 of operating the rotating machine 100 in the standby mode is performed in accordance with the target operating condition T 3.5 In an exemplary embodiment, the step of determining 232 the temperature is 3.5 The step of determining temperature 232 uses a digital simulation to determine the target operating temperature T 3.5 The digital simulation includes a step 232 of determining the temperature of the first combustion zone 115. The digital simulation includes a step 232 of determining the temperature of the first combustion zone 115 using a digital simulation of the rotating machine 100 to iteratively calculate the target operating temperature T 3.5 The temperature can be determined. More specifically, the target operation T 3.5 The temperature is determined based on emission standards to ensure that the rotating machine 100 operates in compliance with the emission standards. For example, a target operating temperature T 3.5 The conditions requiring a temperature update may change (i.e., the grid operator requires that rotating machine 100 increase power generation to a level below MECL 302). For example, the requirements of load 116 may increase or decrease, and thus the operating conditions of rotating machine 100 may change to accommodate the changing requirements of load 116. Specifically, target T 3.5 The operating temperature may vary. However, in an alternative embodiment, the target operating temperature T 3.5The temperature may be determined by an operator or some other method other than by digital simulation and / or may not be updated iteratively every control cycle. The determining step 232 may be performed continuously while other steps of method 200 are performed simultaneously.

[0045] Operating 228 the rotary machine 100 in a standby mode includes determining 234 a current temperature of the exhaust gas 128 using at least one sensor (not shown) configured to measure a current operating temperature of the exhaust gas 128. The sensor determines the current temperature of the exhaust gas 128 in real time during operation of the rotary machine 100. Additionally, transmitting the temperature of the exhaust gas 128 to a digital simulation to determine the current operating temperature of the first combustion zone 115. 3.5 Step 230 of determining the temperature and / or the target operation T 3.5 The temperature may be used as an input to determining step 232. The determining step 234 may be performed continuously while other steps of method 200 are performed simultaneously.

[0046] Operating 228 the rotating machine 100 in the standby mode includes determining 236 a target temperature of the exhaust gases 128. In the exemplary embodiment, determining 236 a target temperature of the exhaust gases 128 includes determining a target operating temperature T 3.5 The method includes determining 236 a target temperature of the exhaust gas 128. The digital simulation and / or computing device 134 may iteratively determine a target temperature of the exhaust gas 128 using the digital simulation and / or computing device 134 of the rotating machine 100, simultaneously with determining 234 a current temperature of the exhaust gas 128. More specifically, the target temperature of the exhaust gas 128 is determined based on the physical operating limits and best heat value of the rotating machine 100. The determining 236 may be performed continuously while other steps of the method 200 are performed simultaneously.

[0047] Step 228 of operating rotating machine 100 in standby mode is performed based on the current operating T 3.5 Temperature and target operation T 3.5 The present operation T 3.5 Temperature and target operation T 3.5 If the temperatures are different, the computing device 134 calculates the current operating temperature T 3.5 Target temperature T 3.5 Control the first fuel flow and the flow of intake air 120 to vary the temperature. The comparing step 238 may be performed continuously while other steps of the method 200 are performed simultaneously.

[0048] Operating 228 the rotating machine 100 in a standby mode further includes comparing 240 the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. If the current temperature of the exhaust gas 128 and the target temperature of the exhaust gas 128 differ, the computing device 134 controls the first fuel flow and the flow of the intake air 120 to change the current temperature of the exhaust gas 128 to the target temperature of the exhaust gas 128, as described below. The comparing 240 may be performed continuously while other steps of the method 200 are performed simultaneously.

[0049] The step 228 of operating the rotating machine 100 in the standby mode may include using the digital simulation and / or computing device 134 to calculate the current operating T 3.5 Target temperature T 3.5 In an exemplary embodiment, the digital simulation further includes calculating 242 a target first fuel flow rate that changes the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128 by performing an additional digital simulation of the rotating machine 100. 3.5 Target temperature T 3.5 The calculation device may calculate a target first fuel flow rate that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. Alternatively, the calculation device may calculate a target first fuel flow rate that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. 3.5 Target temperature T 3.5A target first fuel flow rate may be calculated that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128 .

[0050] The step 228 of operating the rotating machine 100 in the standby mode may include using the digital simulation and / or computing device 134 to calculate the current operating T 3.5 Target temperature T 3.5 In an exemplary embodiment, the digital simulation further includes calculating 244 a target flow rate of the intake air 120 that changes the current temperature of the exhaust gases 128 to the target temperature of the exhaust gases 128 by performing an additional digital simulation of the rotating machine 100. 3.5 Target temperature T 3.5 The calculation device may calculate a target intake air 120 flow rate that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. Alternatively, the calculation device may calculate a target intake air 120 flow rate that will change the current temperature of the exhaust gas 128 to a target temperature of the exhaust gas 128. 3.5 Target temperature T 3.5 A target intake air 120 flow rate can be calculated that changes the current temperature of the exhaust gases 128 to a target temperature of the exhaust gases 128 .

[0051] Step 228 of operating rotating machine 100 in standby mode is performed based on the current operating T 3.5 Target temperature T 3.5 The method further includes controlling 246 the first fuel flow and the flow of intake air 120 to change the current temperature of the exhaust gas 128 to the target temperature of the exhaust gas 128. Specifically, the computation device 134 controls the valve 132 to control the first fuel flow and the inlet guide vane 103 to control the flow of the intake air 120. The computation device 134 controls the valve 132 to adjust the first fuel flow to the target first fuel flow rate and the control inlet guide vane 103 to adjust the flow of the intake air 120 to the target flow rate of the intake air 120. The computation device 134 and the digital simulation control the flow of the intake air 120 and the first fuel flow to the first combustion zone 115 to control the stoichiometry of the first combustion zone 115. The current operating T 3.5 Temperature is the target operating temperature T 3.5After the target temperature of the exhaust gas 128 is changed to the target exhaust gas 128 temperature and the operating conditions of the rotating machine 100 change, the digital simulation and / or calculation device 134 repeats the method 200 as necessary to maintain compliance with emissions requirements and to maintain the temperature of the exhaust gas 128 below the minimum exhaust temperature for operation of the power plant.

[0052] Method 200 also includes receiving 248 a request to increase power generation above MECL 302 while operating in the response or standby mode. In an exemplary embodiment, a controller of the power grid determines that power generation is too low and requests that one or more generators increase power generation. In an alternative embodiment, rather than receiving a request to increase power generation, rotating machine 100 may be requested to increase power generation for other reasons, such as, but not limited to, emergency situations and / or maintenance requirements associated with rotating machine 100, the combined cycle power plant, and / or the power grid.

[0053] The method 200 further includes step 250 of increasing the fuel split from zero to a level consistent with normal operation. The operator of the rotary machine 100 increases the fuel split and resumes combustion in the second combustion zone 117. The first fuel nozzle 119 and the second fuel nozzle 121 direct the first and second fuel flows to the first combustion zone 115 and the second combustion zone 117, respectively. More specifically, the computing device 134 controls the valve 132 to increase the second fuel flow while maintaining the first fuel flow. Thus, the first combustion zone 115 and the second combustion zone 117 are both operating and the total flow of fuel is staged to control the combustion dynamics in the combustor 114. In an alternative embodiment, the first fuel flow to the first combustion zone 115 is also staged. 3.5 is increased to control the temperature.

[0054] Method 200 also includes operating 252 rotating machine 100 in a normal operating mode, such as in response to a request to increase power generation. In the normal operating mode, an operator of rotating machine 100 may increase T in accordance with emissions requirements.3.5 To maintain temperature, the fuel split is increased and the air flow to the combustor 114 is controlled using the inlet guide vanes 103 to maintain the exhaust gases 128 above the minimum exhaust temperature for power plant operation. The rotary machine 100 then begins to operate along the conventional path 304 shown in graph 300.

[0055] The method 200 may be practiced with a rotary machine 100 having alternative combustor 114 configurations. For example, the method 200 may be practiced with a combustor 114 including a single stage combustor including a multiple nozzle array as described above. Additionally, the method 200 may be practiced with a rotary machine 100 including a high pressure turbine disposed between a first combustor and a second combustor and a low pressure turbine disposed downstream of the second combustor as described above. Additionally, the method 200 may be practiced with any combustor 114 configuration that enables the rotary machine 100 to operate as described herein.

[0056] The above-mentioned system and method relate to a method for emissions-compliant operation of a combustor of a gas turbine engine below a conventional MECL. More specifically, the gas turbine engine includes a combustor including a first combustion zone, a second combustion zone, at least one first fuel nozzle, and at least one second fuel nozzle. The at least one first fuel nozzle directs a first fuel flow to the first combustion zone, and the at least one second fuel nozzle directs a second fuel flow to the second combustion zone. The fuel split is a percentage of the total flow of fuel that is directed to the second combustion zone. The digital simulation simultaneously determines a current operating temperature of the first combustion zone, and at least one sensor measures a current operating temperature of the exhaust of the gas turbine. Additionally, an inlet guide vane controls the flow of air to the combustor. When the demand for the gas turbine engine decreases (i.e., when the power grid operator requests the gas turbine engine operator to reduce power generation), the gas turbine engine operator can place the gas turbine engine in a response mode and / or a standby mode.

[0057] In the response mode, the gas turbine engine operator reduces the fuel split to zero (i.e., turns off the second combustion zone) and controls the air flow to the combustor using the inlet guide vanes to reduce the combustor's current operating temperature for carbon monoxide emission compliance and maintain the combustor exhaust temperature above the minimum exhaust temperature for operation of the power plant's steam generating system. The response mode allows the gas turbine engine to continue operating at a reduced level of power generation by the combined cycle power plant while maintaining compliance with carbon monoxide emission requirements.

[0058] In standby mode, the gas turbine engine operator reduces the fuel split to zero (i.e., turns off the second combustion zone) and controls the air flow to a combustor having inlet guide vanes to reduce the combustor's current operating temperature for carbon monoxide emission compliance and maintain the combustor's exhaust temperature below the minimum exhaust temperature for operation of the power plant's steam generating system. The standby mode allows the gas turbine engine to continue operating without the combined cycle power plant producing electricity while maintaining compliance with carbon monoxide emission requirements.

[0059] Both the response mode and the standby mode allow the gas turbine engine to maintain emissions compliant operation during periods of reduced power demand. Thus, when the demand for electricity increases and the grid operator requests more power generation, the gas turbine engine described herein remains operational and will be one of the first generators called upon to increase power generation, increasing revenue for the gas turbine engine operator. Thus, the systems and methods described herein provide for emissions compliant operation of the gas turbine engine combustor below a conventional MECL when power demand decreases and the grid operator requests less power generation.

[0060] Additionally, example technical effects of the systems and methods described herein include at least one of: (a) controlling the temperature of a first combustion zone of a combustor; (b) controlling the electrical load generated by the gas turbine engine; and (c) controlling the flow of air to the compressor and combustor.

[0061] Exemplary embodiments of systems and methods for emissions compliant operation of a combustor of a gas turbine engine below the conventional MECL are described above in detail. The methods and systems are not limited to the specific embodiments described herein, but rather, the system components and / or method steps may be utilized independent and separate from other components and / or steps described herein. For example, the methods may be used in combination with other rotary machines and are not limited to practice only with the gas turbine engine described herein. Rather, the exemplary embodiments may be implemented and utilized in connection with many other rotary machine applications.

[0062] Although specific features of various embodiments of the present disclosure may be shown in some drawings and not in others, this is for convenience only, and in accordance with the principles of the embodiments of the present disclosure, any feature of a drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0063] This specification uses examples to disclose embodiments of the present disclosure, including the best mode. It also uses examples to enable any person skilled in the art to practice the embodiments of the present disclosure, including making and using any device or system, and performing any incorporated methods. The patentable scope of the embodiments described herein 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]

[0064] 100 Rotating machines, gas turbine engines 102 Intake section 103 Control inlet guide vane 104 Compressor section 105 Inlet Guide Vane Controller 106 Combustor section 107 Airfoil 108 Turbine section 110 Exhaust section 112 rotor shaft 114 Combustor 115 First Combustion Zone 116 Load 117 Second Combustion Zone 118 Rotor Assembly 119 No. 1 fuel nozzle 120 Intake 121 No. 2 fuel nozzle 122 Compressed Air 124 Hot Combustion Gases 126 Longitudinal Axis 128 Exhaust Gas 130 Fuel Supply System 132 Valve 134 Computing equipment 200 ways 300 Graphs 302 Minimum Emissions Compliant Load (MECL) 304 History Route 306 First Response Mode Route 308 Second Response Mode Route 310 Standby mode route 312 Goal T 3.5 temperature line 314 Target exhaust temperature line

Claims

1. 1. A method (200) for operating a rotary machine (100) including a combustor (106) including a first combustion zone (115) and a second combustion zone (117) below a minimum emissions compatible load (302) in a response mode (306), the method (200) comprising: i) reducing a fuel split to zero (206), the fuel split apportioning a total flow of fuel to the combustor (106) between the first combustion zone (115) and the second combustion zone (117); ii) determining (210) a current operating temperature of the first combustion zone (115) using a digital simulation of the rotating machine (100); and iii) determining (212) a target operating temperature for the first combustion zone (115), the target operating temperature enabling the rotating machine (100) to operate below a conventional minimum emissions compliant load (MECL) (302) while still complying with emission standards; iv) directing a first fuel stream into the first combustion zone, the first fuel stream reducing a temperature of the first combustion zone to the target operating temperature; v) repeating steps i through iv until said rotating machine (100) is operating below said conventional MECL (302) and in compliance with emissions standards. The method (200).

2. The method (200) of any preceding claim, further comprising determining (214) a current temperature of exhaust gases (128) from the rotary machine (100).

3. The method (200) of claim 2, further comprising determining (216) a target temperature of the exhaust gas (128) at or above a minimum exhaust temperature for operation of a power plant.

4. The method (200) of claim 3, further comprising comparing (218) the current temperature of the exhaust gas (128) to the target temperature of the exhaust gas (128).

5. 5. The method (200) of claim 4, further comprising: calculating (222) a target intake air flow rate that will reduce the temperature of the first combustion zone (115) to the target operating temperature and reduce the current temperature of the exhaust gases (128) to the target temperature of the exhaust gases (128).

6. 6. The method (200) of claim 5, further comprising: directing a flow of air into the first combustion zone (115), the flow of air reducing the temperature of the exhaust gases (128) from the current temperature to the target temperature.

7. 1. A method (200) for operating a rotary machine (100) including a combustor (106) including a first combustion zone (115) and a second combustion zone (117) in a standby mode below a minimum emissions compliant load (302), the method (200) comprising: i) reducing a fuel split to zero (206), the fuel split apportioning a total flow of fuel to the combustor (106) between the first combustion zone (115) and the second combustion zone (117); ii) determining (230) a current operating temperature of the first combustion zone (115) using a digital simulation of the rotating machine (100); and iii) determining (232) a target operating temperature for the first combustion zone (115), the target operating temperature enabling the rotating machine (100) to operate below a conventional minimum emissions compliant load (MECL) (302) while still complying with emission standards; iv) directing a first fuel stream into the first combustion zone (115), the first fuel stream reducing a temperature of the first combustion zone (115) to the target operating temperature and reducing a temperature of exhaust gases (128) from the rotary machine (100) below a minimum exhaust temperature for operation of a power plant; v) repeating steps i through iv until said rotating machine (100) is operating below said conventional MECL (302) and in compliance with emissions standards. The method (200).

8. The method (200) of claim 7, further comprising determining (214) a current temperature of the exhaust gas (128) from the rotary machine (100).

9. The method (200) of claim 8, further comprising determining (216) a target temperature of the exhaust gas (128) that is less than the minimum exhaust temperature for operation of a power plant.

10. 10. The method (200) of claim 9, further comprising comparing (218) the current temperature of the exhaust gas (128) to the target temperature of the exhaust gas (128).

11. 11. The method (200) of claim 10, further comprising calculating (222) a target intake air flow rate that will reduce the temperature of the first combustion zone (115) to the target operating temperature and reduce the current temperature of the exhaust gases (128) to the target temperature of the exhaust gases (128).

12. 12. The method (200) of claim 11, further comprising directing a flow of air into the first combustion zone (115), the flow of air reducing the temperature of the exhaust gases (128) from the current temperature to the target temperature.

13. A rotary machine (100), comprising: a compressor (104) configured to compress a flow of intake air; a combustor (106) including a first combustion zone (115), a second combustion zone (117), at least one first fuel nozzle (119), and at least one second fuel nozzle (121), the at least one first fuel nozzle (119) configured to direct a first fuel flow into the first combustion zone (115), the at least one second fuel nozzle (121) configured to direct a second fuel flow into the second combustion zone (117), the combustor (106) configured to receive a flow of the intake air, and a fuel split is a percentage of a total fuel flow that is directed to the second combustion zone (117); A computing device (134) including a digital simulation of the rotating machine (100), the computing device (134) configured to operate the rotating machine (100) in a responsive mode (306), the computing device (134) comprising: Reducing the fuel split to zero (206); and determining (210) a current operating temperature of the first combustion zone (115) using the digital simulation of the rotating machine (100); determining (212) a target operating temperature for the first combustion zone (115), the target operating temperature enabling the rotating machine (100) to operate below a conventional minimum emissions compliant load (302) (MECL) while still complying with emissions standards; directing a first fuel stream into the first combustion zone, the first fuel stream reducing a temperature of the first combustion zone to the target operating temperature; repeating until the rotating machine (100) is operating below the conventional MECL (302) and in compliance with emissions standards; A rotary machine (100) configured to perform the steps of:

14. The rotary machine (100) of claim 13, further comprising a fuel supply system (130) configured to direct a total flow of the fuel to the first combustion zone (115) and the second combustion zone (117).

15. The rotary machine (100) of claim 14, wherein the fuel supply system (130) comprises at least one valve (132) configured to divide a total flow of the fuel between the first fuel stream and the second fuel stream.

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