Method of operating a combustor for a gas turbine

Abstract

A method of operating a combustion system (16) for a gas turbine (10), the combustor system (16) comprising a main fuel supply (72, 73), a pilot fuel supply (74), a combustion chamber (38). The method comprises the steps of: supplying a first fuel flow by the main fuel supply (72) and the pilot fuel supply (74); monitoring the composition of the first fuel; monitoring combustion instability; reducing the first fuel flow by the pilot fuel supply (74) to zero when the first fuel composition has a) a hydrogen content > 5% by volume and / or b) a high HC content > 5% by volume and the combustion instability is < a predetermined value.

Description

Technical Field

[0001] The present invention relates to a combustion system for a gas turbine and a method of operating the combustion system, and more particularly to a method of operating a fuel supply device for the combustion system. Background Technology

[0002] Stringent emission regulations and the requirement to burn multiple fuels are forcing gas turbine manufacturers, particularly those producing industrial gas turbines, to better control their combustors to meet emission targets while maintaining acceptable combustion performance. Typically, gas turbine combustors with canister-type annular technology operate in a lean, premixed manner, employing multiple fuel lines for this purpose. To prevent high-pressure fluctuations (or pressure dynamics) within the combustion chamber, the main premixed flame is supplemented by an ignition flame to aid in the stability of the main flame. The ignition flame may be partially premixed under varying loads, often resulting in hot spots where the flame is fuel-rich, producing high levels of thermal NOx. Additionally, under certain operating conditions, the metal temperature of the combustor components also increases due to flame enrichment.

[0003] In a typical industrial gas turbine engine, two fuel valves are used: one to control the total fuel flow and the other to determine how much of the total fuel flow is directed to the ignition fuel flow in each burner canister. An intelligent control fuel management system is employed to find the optimal ratio of main fuel to ignition fuel; however, this ratio is identical for all burner canisters in the gas turbine engine. During normal operation using natural gas, the engine control unit (ECU) requires each burner to operate with a portion of the ignition fuel flow to mitigate problems associated with load acceptance / rejection, cross-burner contamination, and high-pressure fluctuations during initiation or combustion instability. Typically, the ECU shuts down the engine when one burner canister of the gas turbine exhibits a pressure dynamic level exceeding permissible limits. Summary of the Invention

[0004] The present invention has at least the following objectives: to reduce emissions from gas turbine engines, and particularly NOx emissions; to improve combustor dynamics and reduce pressure fluctuations in the combustion chamber; to improve combustion stability or reduce combustion instability; to burn high-carbon hydrogen fuels; to burn hydrogen-rich fuels; and to limit the temperature of combustion components.

[0005] The above objective is achieved by a method of operating a combustion system for a gas turbine. The combustor system includes a main fuel supply, an ignition fuel supply, and a combustion chamber. The method includes the following steps: supplying a first fuel stream via the main fuel supply and the ignition fuel supply; monitoring the composition of the first fuel; monitoring combustion instability; and reducing the first fuel stream supplied via the ignition fuel to zero when the first fuel composition has a hydrogen content ≥5% by volume and / or b) a high HC content ≥5% by volume and the combustion instability is < a predetermined value.

[0006] The method may include the following steps: when the first fuel has a hydrogen content of <5% by volume and a high HC content of <5% by volume or a combustion instability ≥ a predetermined value, increasing the first fuel flow supplied by the ignition fuel from zero.

[0007] The burner system may include an auxiliary fuel supply. The method may include the step of supplying auxiliary fuel via the auxiliary fuel supply, wherein the auxiliary fuel may include ammonia.

[0008] The step of supplying auxiliary fuel via auxiliary fuel supply can be performed when combustion instability is below a threshold. Preferably, this threshold is any one of the following: a) a value between 27.5 mbar RMS and 34.5 mbar RMS (0.4 psi RMS and 0.5 psi RMS) in the combustion chamber, preferably 31 mbar RMS (0.45 psi RMS) in the combustion chamber, or b) a value between 20.5 mbar RMS and 27.5 mbar RMS (0.3 psi RMS and 0.4 psi RMS) outside the combustion chamber, preferably 24 mbar RMS (0.35 psi RMS) outside the combustion chamber.

[0009] High HC content can include any or more of the fuels that contain hydrocarbon molecules having at least 3 carbon atoms. Fuels containing hydrocarbon molecules having at least 3 carbon atoms can be derived from the group containing propane, butane, pentane, and hexane.

[0010] At least the primary fuel can have a hydrogen content of ≥5% by volume and a strength of >40 MJ / Nm³. 3 The Wobbe index.

[0011] At least the first fuel can have a high HC content of >5% by volume and a strength of ≥49 MJ / Nm³. 3 The Wobbe index.

[0012] The predetermined value can be any of the following: a) a value between 27.5 mbar RMS and 34.5 mbar RMS (0.4 psi RMS and 0.5 psi RMS) in the combustion chamber, preferably 31 mbar RMS (0.45 psi RMS) in the combustion chamber, or b) a value between 20.5 mbar RMS and 27.5 mbar RMS (0.3 psi RMS and 0.4 psi RMS) outside the combustion chamber, preferably 24 mbar RMS (0.35 psi RMS) outside the combustion chamber.

[0013] The combustion system may include a set of combustion chambers. The step of reducing the ignition fuel supply to zero may include simultaneously reducing the ignition fuel supply to zero in all of the set of combustion chambers.

[0014] The combustion system may include a set of combustion chambers. The step of reducing the ignition fuel supply to zero may include reducing the ignition fuel supply to zero for each combustion chamber in a manner independent of the other combustion chambers in the set of combustion chambers.

[0015] The total fuel supply can be the sum of the main fuel supply and the ignition fuel supply. When the demand output of the combustion system is constant, the total fuel supply to each burner can be constant.

[0016] The main fuel supply may include a main fuel valve for changing the amount of main fuel supplied to the combustion chamber. The ignition fuel supply may include an ignition fuel valve for changing the amount of ignition fuel supplied to the combustion chamber. The step of reducing the ignition fuel supply to zero may include closing the ignition fuel valve and preferably opening the main fuel valve.

[0017] In another aspect of the invention, a combustion system for a gas turbine is provided. The combustor system includes a main fuel supply, an ignition fuel supply, a combustion chamber, a controller, a fuel composition monitor for monitoring the fuel composition of the main fuel supply and / or the ignition fuel supply, and a combustion monitor for monitoring combustion instability. The controller is programmed to reduce the ignition fuel supply to zero when the fuel composition has a hydrogen content ≥5% by volume and / or b) a high HC content ≥5% by volume and combustion instability < a predetermined value.

[0018] The main fuel supply may include a main fuel valve for changing the amount of main fuel supplied to the combustion chamber. The ignition fuel supply may include an ignition fuel valve for changing the amount of ignition fuel supplied to the combustion chamber. The controller may be programmed to reduce the ignition fuel supply to zero by closing the ignition fuel valve and preferably opening the main fuel valve.

[0019] The total fuel supply is the sum of the main fuel supply and the ignition fuel supply. When the demand output of the combustion system is constant, the total fuel supply to each burner can be constant. Attached Figure Description

[0020] The above-described properties and other features and advantages of the present technology, as well as the ways of obtaining these properties and other features and advantages, will become more apparent from the following description of embodiments of the present technology taken in conjunction with the accompanying drawings, and the currently disclosed burner and operating method will be better understood.

[0021] Figure 1 A portion of the turbine engine is shown in cross-section, and a combustion system according to this disclosure is incorporated into the turbine engine.

[0022] Figure 2 This is a schematic cross-section of the burner through the combustion system of the gas turbine according to the invention.

[0023] Figure 3 This is a schematic illustration of a first embodiment of a fuel supply device for supplying fuel to a burner in a combustion system according to the present invention.

[0024] Figure 4 This is a schematic illustration of a second embodiment of a fuel supply device for supplying fuel to a burner in a combustion system according to the present invention.

[0025] Figure 5 This is a schematic illustration of a third embodiment of a fuel supply device for supplying fuel to a burner in a combustion system according to the present invention. Detailed Implementation

[0026] Figure 1 This is a schematic cross-sectional view of the overall arrangement of a turbine engine 10, which includes an inlet 12, a compressor 14, a combustor system 16, a turbine system 18, an exhaust duct 20, and twin shaft units 22 and 24. The turbine engine 10 is generally arranged about an axis 26, which is the axis of rotation for rotating components. The shafts of the twin shaft units 22 and 24 may have the same or opposite directions of rotation. The combustor system 16 comprises an annular array of combustors or combustor canisters 36, with only one combustor or combustor canister shown. In one example, there are six combustors 36 evenly spaced around the engine 10. The turbine system 18 includes a high-pressure turbine 28 driven to the compressor 14 via a first shaft 22 of the twin shaft unit. The turbine system 18 also includes a low-pressure turbine 30 driven to a load (not shown) via a second shaft 24 of the twin shaft unit.

[0027] The terms “radial,” “circumferential,” and “axial” are relative to the engine’s axis of rotation 26, or, as otherwise stated, for example, relative to the combustor axis 44. The terms “upstream” and “downstream” are relative to the general direction of gas flow through the engine, and as… Figure 1 What we see is usually from left to right.

[0028] Compressor 14 includes an axially arranged series of stator blades and rotor blades mounted in a conventional manner. As is known, the stator or compressor blades can be fixed or have variable geometry to improve airflow to the downstream rotor or compressor blades. Each turbine 28, 30 includes an axially arranged series of stator blades and rotor blades. The stator blades can be mounted to a radial housing or radial inner cylinder. The rotor blades are mounted via rotor disks arranged and operated in a conventional manner. The rotor assembly includes an annular array of rotor blades or blades and rotor disks.

[0029] Each burner 36 consists of two walls—an inner wall 37 and an outer wall 39—defining a generally annular space or chamber 35 between the inner wall 37 and the outer wall 39. At the head of the burner 36 is a radial swirler 40, which includes swirl plates or base plates 45, an annular array of swirler blades 46, and fuel injection points, as described in more detail later. Following the swirler 40 is a pre-combustion chamber 42, and then a main combustion chamber 38. These burner components 36 are generally arranged about a burner axis 44. The annular array of swirler blades 46 defines swirler slots 47 arranged around the base plate 45.

[0030] In operation, air 32 is drawn into the engine 10 through inlet 12 and enters the compressor 14, where the impellers and blades of the continuous stage compress the air 34 before it is delivered to the combustor system 16. The compressed air 34 flows through the air chamber 35 and enters the cyclone separator 40. The cyclone separator 40 generates highly turbulent air into which fuel is injected. The air / fuel mixture is delivered to the pre-combustion chamber 42, where it continues to mix, and then to the main combustion chamber 38. In the combustion chamber 38, the compressed air and fuel mixture is ignited and burned. The resulting hot working gas stream is directed to the high-pressure turbine 28, causing it to expand and drive the high-pressure turbine 28, which in turn drives the compressor 14 via the first shaft 22. After passing through the high-pressure turbine 28, the hot working gas stream is directed to the low-pressure turbine 30, which drives the load via the second shaft 24.

[0031] The low-pressure turbine 30 can also be referred to as a power turbine, and the second shaft 24 can also be referred to as a power shaft. The load is typically an electric motor for generating electricity or a mechanical machine such as a pump or process compressor. Other known loads can be driven via the low-pressure turbine. The fuel can be in gaseous and / or liquid form.

[0032] Reference Figure 1 The turbine engine 10 shown and described is merely one example of many engines or turbomachinery into which the present invention can be incorporated. Such engines can be gas turbines or steam turbines, and include single-shaft, twin-shaft, and triple-shaft engines used in marine, industrial, and aerospace applications.

[0033] Figure 2 It is a cross-section passing through a portion of one of the combustors 36 in a group of combustors of the turbine engine 10 described above according to the invention. The radial vortex 40 comprises an annular array of blades 46 arranged about a combustor axis 44, and the blades 46 are tangentially angled relative to the combustor axis 44 to generate a vortex flow 55 mixing air and fuel, as is known. The vortex flow 55 rotates about the combustor axis 44 and flows in a generally left-to-right direction, as... Figure 2 As seen in the image. Swirl impellers 46 form an array of mixing channels or swirl grooves 47 between each successive swirl impeller 46. The swirl 40 also includes main fuel injectors 60, 62 for injecting main fuel and an ignition fuel injector 50 for injecting ignition fuel. The swirl 40 includes a base plate 45 having a guide surface 52 facing the pre-combustion chamber 42 and defining an upstream axial extent of the pre-combustion chamber. The main fuel injector 60 is located in the base plate 45, and the main fuel injector 62 is conventionally located in the swirl impellers 46. The pre-combustion chamber 42 is also defined by an annular wall 54 symmetrically arranged about the combustor axis 44. The pre-combustion chamber 42 has an inlet 67 and an outlet 68. The outlet 68 is formed at or located at the lip 69 of the pre-combustion chamber 42 and defines the termination position of the pre-combustion chamber 42. The annular wall 54 of the pre-combustion chamber 42 then follows the generally annular wall 37 of the main combustion chamber 38. From the lip 69 downstream, the generally annular wall 37 is divergent and open to define the main combustion chamber 38. The main combustion chamber 38 has a cross-sectional area larger than that of the pre-combustion chamber 42.

[0034] As described later, combustor 36 may include auxiliary fuel injectors 64 and 66. Auxiliary fuel injector 64 may be located in a recess 63 formed in the annular wall 37 of combustion chamber 38. Auxiliary fuel injector 66 may be located in a recess 65 formed in the annular wall 54 of pre-combustion chamber 42. Recesses 63 and 65 are optional. Fuel and air entering recesses 63 and 65 generate a trapping vortex that premixes the fuel and air before entering combustion chamber 38 or pre-combustion chamber 42.

[0035] Two distinct fuel / air mixtures and subsequent combustion flames exist within combustion chamber 38; the ignition flame 56 originates from the ignition fuel / air mixture, and the main flame 58 originates from the main fuel / air mixture. The indicated lines 56 and 58 show the flame fronts, and the corresponding flames continue downstream of the flame fronts. The ignition flame 56 and the main flame 58 differ from each other due to the location of their respective fuel injection points within or near the mixing channel 47 in the airflow 34. The main fuel injectors 48A and 48B inject main fuel into the swirler slots or mixing channel 47, and are located further away from the burner axis 44, i.e., radially outward, compared to the ignition fuel injector 50. Therefore, the corresponding fuel / air mixtures form significantly different flame regions, with the ignition flame 56 typically located radially inward of the main flame 58. In this example, the ignition fuel injector 50 is positioned through the substrate 45 and radially inward of the swirler 40.

[0036] As in the case here, a radial swirler has, or can be defined as having, a swirl number SN. The aforementioned radial swirler 40 has an SN in the range of 0.5 to 0.8. As is known in the art, the swirl number can be calculated, and here it can be said that the swirl number can be defined by the relationship between the angular momentum flux and the linear momentum flux of the fuel / air mixture. That is, the angular momentum is related to the rotational velocity about the combustor axis 44, and the linear momentum is related to the velocity in the axial direction along the combustor axis 44. Therefore, SN is defined herein as the ratio of the tangential momentum to the axial momentum of the fluid or fuel / air mixture.

[0037] The combustion zone (SN) determines the primary aerodynamics of the flow within the combustion chamber and is designed for typical (conventional) fuels, such as natural gas. However, when the fuel composition is changed (e.g., by adding hydrogen or high HC), the combustor's SN cannot be easily altered. This is clearly detrimental and undesirable, and can lead to unstable combustion and even flameout, poor combustor dynamics and high-pressure fluctuations in the combustion chamber, as well as increased emissions of NOx (nitrogen oxides), sulfur oxides, unburned hydrocarbons, and other undesirable combustion byproducts.

[0038] Reference Figures 3 to 5The described embodiments of the invention relate to a method of operating a combustion system 16, and particularly to a method for controlling the fuel supply to the burner 36 and the fuel supply device 70 of the combustion system 16 to prevent these undesirable effects, especially when using high-HC fuels or fuels with high hydrogen content. The invention also relates to a combustion system 16 having a fuel supply device 70 to prevent these undesirable effects, particularly when using high-HC fuels or fuels with high hydrogen content.

[0039] Figure 3 This is a schematic illustration of a first embodiment of a fuel supply device 70 for supplying fuel to the burners of a combustion system. The fuel supply device 70 includes a main fuel supply 72, an ignition fuel supply 74, a total fuel supply 76, a fuel composition monitor 78, a main fuel valve 80, an ignition fuel valve 82, a combustion monitor 84, and a controller 86. The main fuel supply 72 supplies a first fuel flow to the main fuel injectors 60 and 62. The ignition fuel supply 74 supplies a first fuel flow to the ignition fuel injector 50. Therefore, in this embodiment, the same fuel is supplied to the main fuel injector and the ignition fuel injector via the respective main fuel supply and ignition fuel supply. Fuel passes through the main fuel valve 80 and the ignition fuel valve 82 in the respective main fuel supply 72 and ignition fuel supply 74.

[0040] The controller 86 is part of the engine's electronic control unit (ECU), but it can be a separate component. The controller 86 includes software programming as part of the overall engine control software. The controller 86 is connected to a fuel composition monitor 78, the main fuel valve 80 of each burner 36, the ignition fuel valve 82, and a combustion monitor 84. The combustion monitor 84 measures combustion instability via dynamic pressure fluctuations. As mentioned, the combustion system 16 has multiple burners 36; in this case, there are six burners 36 evenly spaced around the engine's axis 26. Each burner 36 has its own main fuel supply 70 controlled by the main fuel valve 80 and an ignition fuel supply 72 controlled by the ignition fuel valve 82, and each main fuel valve 80 and ignition fuel valve 82 is connected to and can be controlled by the controller 86. Each burner 36 may have at least one combustion monitor 84, and these combustion monitors 84 are each connected to the controller 36.

[0041] During the operation of the combustion system 16, the composition of the fuel flowing in the total fuel supply 76 is monitored by the fuel composition monitor 78, and the composition is transmitted to the controller 86. Meanwhile, the combustion monitor 84 monitors pressure fluctuations in the combustion chamber 38 and transmits the pressure fluctuation readings to the controller 86. The fuel composition monitor 78 and the combustion monitor 84 continuously transmit data to the controller 86.

[0042] During engine startup, fuel is supplied to the ignition injector 50 in one or more of the burners 36, and the fuel is ignited. The ignition fuel valve 82 is opened. The main fuel valve 80 is closed. When an ignition flame 56 is established in any of the burners 36 and there is a demand for increased engine power, fuel is subsequently supplied to the main injectors 60, 62, and the main fuel valve 80 opens by an amount representing the required power output. When a main flame 58 is established in each burner 36, the controller 86 determines the state of combustion instability in each burner 36 and the fuel composition in the main fuel supply 72 and / or the ignition fuel supply 74, or alternatively, the total fuel supply 76. For each burner 36, if the fuel composition has a hydrogen content of ≥5% by volume and / or a high HC content of ≥5% by volume and the combustion instability is < a predetermined value, the ignition fuel valve 82 for that burner 36 begins to close and the ignition fuel supply is reduced. In a preferred embodiment, the ignition fuel valve 82 is completely closed, and the ignition fuel flow rate is zero. The total fuel supply 76 remains constant or has negligible variation; therefore, the amount that would otherwise be the ignition fuel supply is diverted into the main fuel supply and injected through the main fuel injectors 60, 62. Thus, with the demand output of the combustion system 16 or the gas turbine engine 10 constant, when the ignition fuel supply 72 is reduced to zero, the total fuel supplied and burned in the combustion chamber 38 also remains constant or very close to constant.

[0043] During operation, if the fuel composition is detected to have a hydrogen content of <5% by volume and a high HC content of <5% by volume, or a combustion instability ≥ a predetermined value, the ignition fuel valve 82 for any one or more burners in burner 36 is commanded to open, thereby increasing the ignition fuel supply to a level sufficient to sustain the ignition flame 56. Here, the total fuel flow remains constant or has negligible variation; therefore, some of the main fuel supply flow is now diverted into the ignition fuel supply flow and injected through the ignition fuel injector 50.

[0044] Each combustion monitor 84 monitors pressure fluctuations in each combustion chamber 38 and transmits the readings to the controller 86. Alternatively, the combustion monitor 84 monitors pressure fluctuations (burner instability) in the gas chamber 35 immediately outside the combustion chamber 38. The controller 86 is programmed to regulate the ignition fuel supply 74 in part based on the pressure fluctuations of each burner 36 by opening or closing the ignition fuel valve 82. Here, any one or more burners of the burners 36 can close or open their ignition fuel valve 82 based on their combustion instability (and based on the fuel composition). Thus, any one or more burners of the burners 36 can operate solely by means of their main fuel supply and main flame 58, and other burners 36 can operate with the ignition fuel supply 72 and main fuel supply in the presence of a corresponding ignition flame 56 and main flame 58. However, a group of burners 36 or all burners of the burners 36 can close or open the ignition fuel supply 72 based on the combustion instability of any one or more burners. For example, when the ignition fuel valves on all burners in a group of burners 36 are closed and the combustion instability threshold or combustion instability value is reached, all ignition fuel valves 82 in that group are opened.

[0045] In addition to monitoring fuel composition and combustion instability and subsequently reducing or increasing the ignition fuel supply while keeping the total fuel supply constant, the output or power of the gas turbine engine can also be used as another threshold to consider before reducing or increasing the ignition fuel supply. When the engine power is less than 30% of maximum power, the ignition fuel supply remains constant, and therefore over-control is applied based on changes in fuel composition and combustion instability. This over-control is because when the engine power is less than 30% of maximum power, it is known that reducing the ignition fuel supply could lead to potential flame extinction, and an ignition flame is required to stabilize the main flame.

[0046] Now refer to Figure 4 , Figure 4 This is a schematic illustration of a second embodiment of a fuel supply device 70 for supplying fuel to the burner 36 of the combustion system 16. Similar components in this second embodiment have the same reference numerals as those described in the first embodiment, and generally operate in the same manner as described in the first embodiment, unless otherwise interpreted.

[0047] In a second embodiment of the fuel supply device 70, a single main fuel valve 80 is provided on the main fuel supply 72 that supplies main fuel to a group of burners 36 of the combustion system 16. A single ignition fuel valve 82 is provided on the ignition fuel supply 74 that supplies ignition fuel to the same group of burners 36 of the combustion system 16. Preferably, the group of burners 36 comprises all burners of the combustion system 16, but the group of burners can be any two or more of the total number of burners 36 in the combustion system 16. Each burner 36 has a combustion monitor 84, and each of these combustion monitors 84 transmits data to a controller 86. Regarding combustion instability, if the combustion instability is below a predetermined value, the ignition fuel supply 74 can be reduced to zero for all burners 36 in the group of burners, although this also depends on the fuel composition; or detecting combustion instability equal to or above a predetermined threshold will cause the controller 86 to maintain the ignition fuel supply 74 to all burners in the group of burners based on the current state of the ignition fuel supply 74, or to increase the fuel supply to all burners in the group of burners from zero. In this embodiment, all burners 36 in the group of burners operate in the same manner. This can be advantageous because all burners 36 in the group of burners will have very similar usage histories and produce very similar heat outputs to provide a constant thermal pattern around the outer perimeter of the engine covered by the group of burners.

[0048] In the present invention Figure 4 In another aspect shown, the main fuel supply 72 and the ignition fuel supply 74 each have separate fuel composition monitors 78A and 78B. The fuel sources for the main fuel supply and the ignition fuel supply can be the same, but they can also be different. If the fuel sources are different, the fuels for each of the main fuel supply 72 and the ignition fuel supply 74 can have different compositions. In this example, the decision to reduce the ignition fuel supply 74 to zero and use the fuel composition of the main fuel supply 72 is considered, as the instability of the main flame is important and depends on the fuel composition.

[0049] Now refer to Figure 5 The third embodiment of the invention is described, although, for example, according to Figure 3 and Figure 4 Other burners can be used in this implementation, but Figure 5 Only one burner 36 or combustion system 16 is shown. Unless otherwise stated, the same features herein are carried with... Figure 3 and Figure 4The same reference numerals appear in the accompanying drawings, and they are functionally similar. Here, the first main fuel supply 72 supplies first fuel to the main fuel injectors 60, 62, and the ignition fuel supply 74 supplies first fuel to the ignition fuel injector 50. The main fuel valve 80 and the ignition fuel valve 82 are connected to and controlled by the controller 86 as described herein, and the fuel composition monitor 78 measures the fuel composition of the first fuel and forwards this information to the controller 86. The arrangement of the main fuel supply 72, the ignition fuel supply 74, the main fuel valve 80, and the ignition fuel valve 82 together with the fuel composition monitor 78 can be referenced. Figure 3 or Figure 4 The arrangement shown and described. In this embodiment, an auxiliary fuel supply 73 is provided, which has an auxiliary fuel valve 81 connected to and controlled by a controller 86. As previously described, the burner 36 may include one or two auxiliary fuel injectors 64 and 66. The auxiliary fuel may include ammonia, or may be ammonia-based fuels, such as a mixture of ammonia and hydrogen, or a mixture of ammonia and natural gas.

[0050] In the method of operating combustion system 16, the predetermined value for combustion instability is 31 mbar RMS (0.45 psi RMS) when measured inside combustion chamber 38 or 24 mbar RMS (0.35 psi RMS) when measured outside combustion chamber 38. The outside of combustion chamber 38 is preferably adjacent to the outside of combustion chamber 38 and preferably within gas chamber 35. For other combustion systems 16, the predetermined value for combustion instability may be between 27.5 mbar RMS and 34.5 mbar RMS (0.4 psi RMS and 0.5 psi RMS) when measured inside combustion chamber 38, or between 20.5 mbar RMS and 27.5 mbar RMS (0.3 psi RMS and 0.4 psi RMS) when measured outside combustion chamber 38.

[0051] As previously stated, during operation, if a fuel composition is detected to have a hydrogen content of ≥5% by volume and / or a high HC content of ≥5% by volume, the ignition fuel supply is reduced to zero, taking into account combustion instability. High HC fuels include any one or more of the group consisting of hydrocarbon molecules having at least three carbon atoms. Preferably, high HC fuels include any one of the group consisting of propane, butane, pentane, and hexane. Preferably, high HC fuels have a hydrogen content of ≥49 MJ / Nm³. 3 The Wobbe index. Regarding the hydrogen content of the fuel, the fuel composition must have a hydrogen content of ≥5% by volume and preferably >40 MJ / Nm³. 3 The Wobbe index.

[0052] The ignition fuel valve 82 actuates very quickly and can open and / or close within 0.1 seconds, allowing for very rapid correction in response to combustion instabilities. Furthermore, the main fuel valve 80 actuates very quickly to accommodate the redirection of ignition fuel quantity, thereby maintaining a constant total fuel flow to each burner 36.

[0053] All features disclosed in this specification (including any appended claims, abstract, and drawings) and / or all steps of any method or process disclosed thereby may be combined in any combination except for combinations in which at least some of these features and / or steps are mutually exclusive.

[0054] Unless otherwise expressly stated, each feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by an alternative feature for the same, equivalent, or similar purpose. Therefore, unless otherwise expressly stated, each disclosed feature is merely one example of an equivalent or similar feature in a general series.

[0055] This invention is not limited to the details of the foregoing embodiments. The invention extends to any novel feature or combination of novel features disclosed in this specification (including any appended claims, abstract, and drawings), or to any novel step or combination of novel steps in any method or process disclosed thereby.

Claims

1. A method of operating a combustion system (16) for a gas turbine (10), the combustion system (16) comprising: Main fuel supply (72). Ignition fuel supply (74). Combustion chamber (38) The method includes the following steps: The first fuel flow is supplied through the main fuel supply (72) and the ignition fuel supply (74). Monitor the composition of the first fuel stream. Monitoring combustion instability, The first fuel flow through the ignition fuel supply (74) is reduced to zero under the following conditions: The composition of the first fuel stream has: a) Hydrogen content ≥5% by volume, and / or b) High hydrocarbon content ≥5% by volume; and The combustion instability is less than a predetermined value.

2. The method for operating the combustion system (16) according to claim 1, the method comprising the following steps: The first fuel flow supplied via the ignition fuel is increased from zero under the following conditions: The first fuel stream includes: a) Hydrogen content <5% by volume, and b) High hydrocarbon content <5% by volume, or The combustion instability is greater than or equal to a predetermined value.

3. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The combustion system (16) includes: Auxiliary fuel supply (73). The method includes the following steps: Auxiliary fuel is supplied via the auxiliary fuel supply (73), wherein the auxiliary fuel includes ammonia.

4. The method of operating the combustion system (16) according to claim 3, wherein, The step of supplying auxiliary fuel via the auxiliary fuel supply (73) is performed when the combustion instability is below a threshold, and the threshold is any one of the following: a) Values ​​between 27.5 mbar RMS and 34.5 mbar RMS within the combustion chamber (38), and b) Values ​​outside the combustion chamber (38) between 20.5 mbarRMS and 27.5 mbarRMS.

5. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The high hydrocarbon content includes any or more of the fuel group that contains hydrocarbon molecules having at least 3 carbon atoms.

6. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The first fuel stream, comprising at least 5% hydrogen by volume, has a hydrogen content of >40 MJ / Nm³. 3 The Wobbe index.

7. The method of operating the combustion system (16) according to claim 1 or 2, wherein, At least the first fuel stream includes a high hydrocarbon content of >5% by volume and has a concentration of ≥49 MJ / Nm³. 3 The Wobbe index.

8. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The predetermined value is any one of the following: a) Values ​​between 27.5 mbar RMS and 34.5 mbar RMS within the combustion chamber (38), and b) Values ​​outside the combustion chamber (38) between 20.5 psiRMS and 27.5 psiRMS.

9. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The combustion system (16) includes a set of combustion chambers (38), wherein, The steps to reduce the ignition fuel supply to zero include: At the same time, the ignition fuel supply (74) of all combustion chambers (38) in the group of combustion chambers is reduced to zero.

10. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The combustion system (16) includes a set of combustion chambers (38), wherein, The steps to reduce the ignition fuel supply to zero include: The ignition fuel supply (74) of each combustion chamber (38) is reduced to zero in a manner independent of the other combustion chambers (38) in the group of combustion chambers.

11. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The total fuel supply is the sum of the main fuel supply (72) and the ignition fuel supply (74), and The combustion system (16) includes a plurality of burners (36), and the total amount of fuel supplied to each burner (36) is constant when the demand output of the combustion system (16) is constant.

12. The method of operating the combustion system (16) according to claim 1 or 2, wherein, The main fuel supply (72) includes a main fuel valve for changing the amount of main fuel supplied to the combustion chamber (38). The ignition fuel supply (74) includes an ignition fuel valve for changing the amount of ignition fuel supplied to the combustion chamber (38). The step of reducing the ignition fuel supply (74) to zero includes: Close the ignition fuel valve (82), and Open the main fuel valve (80).

13. The method of operating the combustion system (16) according to claim 4, wherein, The value inside the combustion chamber (38) is 0.45 psiRMS, or the value outside the combustion chamber (38) is 24 mbarRMS.

14. The method of operating the combustion system (16) according to claim 5, wherein, The hydrocarbon molecules having at least 3 carbon atoms include propane, butane, pentane, and hexane.

15. The method of operating the combustion system (16) according to claim 8, wherein, The value inside the combustion chamber (38) is 0.45 psiRMS, or the value outside the combustion chamber (38) is 24 mbarRMS.

16. A combustion system (16) for a gas turbine (10), the combustion system (16) comprising: Main fuel supply (72). Ignition fuel supply (74). Combustion chamber (38) Controller (86). A fuel composition monitor (78) is used to monitor the fuel composition of the main fuel supply (72) and / or the ignition fuel supply (74). Combustion monitor (84), said combustion monitor (84) is used to monitor combustion instability, Controller (86), which is programmed to reduce the ignition fuel supply (74) to zero when: The fuel composition has: a) Hydrogen content ≥5% by volume, and / or b) High hydrocarbon content ≥5% by volume; and The combustion instability is less than a predetermined value.

17. The combustion system (16) according to claim 16, wherein, The main fuel supply (72) includes a main fuel valve (80) for changing the amount of main fuel supplied to the combustion chamber (38). The ignition fuel supply (74) includes an ignition fuel valve (82) for changing the amount of ignition fuel supplied to the combustion chamber (38). The controller (86) is programmed to reduce the ignition fuel supply to zero by closing the ignition fuel valve (82).

18. The combustion system (16) according to claim 16 or 17, wherein, The total fuel supply is the sum of the main fuel supply (72) and the ignition fuel supply (74), and The combustion system (16) includes a plurality of burners (36), and the total amount of fuel supplied to each burner (36) is constant when the demand output of the combustion system (16) is constant.

19. The combustion system (16) according to claim 17, wherein, The controller (86) is programmed to open the main fuel valve (80) when the ignition fuel valve (82) is closed.

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