Patent Description:
The present invention relates to a method of injecting hydrogen into a combustion chamber of a combustor of a gas turbine system.

A gas turbine arrangement commonly used for industrial power generation is illustrated in <FIG>. As can be appreciated from International Publication No. <CIT>, this arrangement can conventionally include a cold section characterized by a compressor, followed by a hot section that has a combustor section and a turbine. The cold section often includes an air intake for feeding air to a multi-stage axial flow compressor that delivers high pressure air to the combustor section. A fuel can be mixed with the air flow and combusted in the combustion section to produce a high temperature, high pressure gas stream that is to be fed to the turbine. The turbine is downstream of the combustor section and is configured to receive the hot combustion gas from the combustor section and expand that flow of gas as the gas passes through the turbine, which spins the rotating blades of the turbine. Often, the rotating blades of the turbine are attached to a shaft to rotate the shaft to perform a dual function: (<NUM>) help drive the compressor to draw more pressurized air into the combustor section, and (<NUM>) spin a generator to produce electricity. The operating pressure ratio of the turbine, which is defined as the pressure of the air at the compressor exit to that of the air at the compressor intake, is normally less than about <NUM>:<NUM>.

While combustor designs vary based on manufacturer, size, and application, many, particularly those of the multiple-can type (an example of which is shown in <FIG>), and the can-annular type (an example of which is shown in <FIG>), carry out combustion via an array of cylindrical tubes or "cans" disposed circumferentially around the turbine shaft. In the multiple-can type combustor, each can's air intake is mechanically coupled to a corresponding outlet port of the compressor. In contrast, the can-annular type combustor is typically configured so that each can's air intake is open to a common single annulus connected to the compressor outlet. In either case, products of combustion are discharged from each can through a transition duct where they are then distributed around a <NUM>° arc into the first stage of the turbine.

Each can combustor typically has a combustor chamber fed by one or more air-fuel nozzles disposed about the circumference of an inlet plane of the can combustor in an annular configuration. The air-fuel nozzles introduce a mixture of air and fuel into the combustor chamber. In many cases, an air-fuel pilot burner is additionally disposed along the combustor axis. The air-fuel pilot burner, which is employed to enhance combustion stability, may be of either a pre-mix design or a nozzle-mix (i.e., diffusion or non-pre- mix) design. The combination of premix nozzles and pilot burner is often collectively referred to as a burner, and each can combustor usually includes its own burner or group of burners. Typically, a premix nozzle includes a fuel injector that discharges fuel into a corresponding air stream. Often, the nozzle is arranged as an annular nozzle that includes one or more fuel injectors arranged in an annular configuration surrounded by an air annulus around a central air- fuel pilot burner. The burner helps combust the mixture of air and fuel injected into the combustion chamber of a can of the combustion section to form the hot gas for feeding to the turbine. <CIT> discloses a multifuel gas turbine combustor capable of combusting gases containing hydrogen in a high concentration with a low NOx while maintaining a low emission performance brought about by the pre-mixture combustion in the main burner. The gas turbine combustor includes a main burner (<NUM>) for supplying to and combusting a premixed gas (M), containing a first fuel (F1), within a first combustion region (S1) of a combustion chamber (<NUM>), and a supplemental burner (<NUM>) for supplying to and combusting a second fuel (F2) of a composition different from that of the first fuel (F1) within a second combustion region (S2) defined downstream of the first combustion region (S1) within the combustion chamber (<NUM>).

It is desirable for environmental reasons to run a gas turbine system so that ist combustors or combustor section operate using lean combustion. The use of lean combustion can refer to a condition in which there is excess air, or oxygen, for combustion relative to the fuel fed to the combustion chamber for combustion. Operating in a lean combustion condition can help reduce nitrous oxide (NOx) formation, which results in a more environmentally friendly exhaust to be output from the gas turbine system. However, lean combustion operation can result in instabilities. These instabilities can result in combustor pressure oscillations, which can also be referred to as vibrations, due to the lack of sufficient uniformity in a continuous burn, or combustion of the fuel. The oscillations, or vibrations, which can be caused from these instabilities, can cause mechanical damage to the gas turbine system. We have determined that such a problem can be better addressed by improving lean combustion stability to greatly reduce combustion instability issues. The reduction of combustion instability can greatly reduce combustor oscillations or vibrations to prolong the life of gas system components and improve operational performance of the gas turbine system. In some embodiments, a flow of hydrogen (H<NUM>) gas can be injected into a first wake region of an air-fuel injector (also called air-fuel burner) within a combustion chamber that is formed downstream of where a swirled air-fuel stream was fed into the combustion chamber via a premix burner nozzle. The hydrogen can be injected so that the first wake region interacts with one or more second wakes of a secondary wake region formed between the location at which the hydrogen is injected into the combustion chamber and the first wake region within the combustion chamber. The injection of the hydrogen can form at least one second wake in the combustion chamber via combustion of the injected hydrogen. The one or more second wakes can be formed between the hydrogen injector and the first wake region as well as between the outlet of the hydrogen injector and a position at which a swirling flow of the mixture of fuel and air crosses a discharge plane of the outlet for hydrogen injection. This can result in an interaction between one or more first wakes of the first wake region and one or more second wakes that can facilitate improved combustion stability as a consequence of the combustion of hydrogen interacting with combustion gases of the first wakes. This interaction can include, for example, activated gas in the one or more first wakes from combustion of fuel communicating heat and active chemical species with the one or more second wakes.

We have determined that the injection of hydrogen into a region of hot excess air can often, if not always, result in the rapid ignition of hydrogen for combusting the hydrogen. We believe this is due to the relatively high chemical reactivity of hydrogen, its wide range of flammability and elevated flame temperature. We have determined that the injection of hydrogen into the combustion chamber and its resultant combustion, can initiate a flame-stabilizing chain reaction that can subdue combustion driven oscillations that can occur within a combustion chamber during the combustion of the fuel therein. We have determined that this is particularly applicable to embodiments in which the injection of the hydrogen gas occurs at a location within the combustion chamber that is adjacent to a swirled air-fuel mixture output from a nozzle, while also being separated from this swirled air-fuel mixture output and being positioned downstream of the output flow of the air-fuel mixture output from the nozzle so that the injected hydrogen can interact with the fuel and air within the combustion chamber in a wake region within the combustion chamber.

A method of injecting hydrogen into a combustion chamber of a combustor of a gas turbine system according to the invention is defined in claim <NUM>.

The method can be utilized so that the at least one central jet of hydrogen is injected into a secondary wake region within the combustion chamber that is downstream of the outlet of the inner hydrogen injection conduit and upstream of a position within the combustion chamber at which the mixture of fuel and air output from the outlet of the outer conduit crosses a discharge region of the outlet of the inner hydrogen injection conduit within the combustion chamber. The crossing of the discharge region can include passing through the discharge region, entering the discharge region, and/or moving along the discharge region. In at least some version of this aspect the at least one central jet of hydrogen can be injected at a velocity of at least <NUM>/s.

The method can also include generating a swirl of air via at least one swirler to generate a swirling flow for the mixture of air and fuel prior to outputting the mixture of air and fuel from the outlet of the outer conduit. In such an aspect, or in conjunction with the fifteenth and/or sixteenth aspects, the secondary wake region can be between the outlet of the inner hydrogen injection conduit and the position within the combustion chamber at which the mixture of fuel and air output from the outlet of the outer conduit crosses the outlet of the inner hydrogen injection conduit while the fuel of the mixture combusts in the combustion chamber.

The method can be employed such that the outlet of the inner hydrogen injection conduit is a single orifice and the inner hydrogen injection conduit has at least one cavity upstream of the single orifice.

The at least one cavity can have a depth, a cavity length, and a cavity trailing edge distance, which is a distance a downstream end of the cavity is from the outlet of the inner hydrogen injection conduit. The cavity depth can be greater than or equal to a radius of the orifice of the outlet of the inner hydrogen injection conduit and also be less than or equal to a diameter of the orifice of the outlet of the inner hydrogen injection conduit, the cavity length can be a value so that a ratio of the length to the depth is between <NUM> and <NUM>, and the cavity trailing edge distance can be a value so that a ratio of the cavity trailing edge distance to the diameter is no more than <NUM>. Of course, the at least one cavity in a nineteenth aspect can be structured to have other parameters for the cavity length, depth, and trailing edge distance parameters that differ from these parameters as well.

The method can be employed in situations where the outlet of the inner hydrogen injection conduit includes a nozzle with at least one central orifice to form the at least one central jet of hydrogen to inject hydrogen into the combustion chamber and multiple outer orifices to form multiple non-central jets of hydrogen to inject hydrogen into the combustion chamber. The method can also include injecting the non-central jets of hydrogen into the combustion chamber via the outer orifices of the nozzle. In some embodiments, the one or more central jets of hydrogen can flow in an axial direction while the non-central jets of hydrogen flow in a non-axial direction. The injection of the non-central jets can be performed so they are injected into a secondary wake region within the combustion chamber that is downstream of the outlet of the inner hydrogen injection conduit and upstream of a region within the combustion chamber at which the mixture of fuel and air output from the outlet of the outer conduit crosses a discharge region of the outlet of the inner hydrogen injection conduit within the combustion chamber. The crossing of the discharge region can include passing through this discharge region, entering the discharge region, and/or moving along the discharge region. The outer orifices can be configured so that each of the non-central jets of hydrogen are output in a flow direction that flows at an angle to a flow direction of the at least one central jet of hydrogen. This angle can be greater than <NUM>° and less than <NUM>°, greater than <NUM>° and less than <NUM>°, or within another range to meet a particular set of design criteria. The at least one central jet of hydrogen can be injected at a velocity of at least <NUM>/s and each of the non-central jets of hydrogen can be injected at a velocity that is at least <NUM>/s. The recirculation gas flow rate (m,recirc) can be a function of the main premix burner swirl number and average axial injection velocity that may either be estimated by empirical correlation (available in the public domain) or via computational fluid dynamics modeling. The outer conduit and/or the inner hydrogen injection conduit are portions of the burner of the combustor.

Another method according to the invention is defined in claim <NUM>.

Exemplary embodiments of gas turbines, injection devices for combustion chambers in a gas turbine system, operation of gas turbines, operation of injectors for combustion used in conjunction with a gas turbine system, plants utilizing one or more gas turbine systems, and methods of making and using the same are shown in the drawings included herewith. It should be understood that like reference characters used in the drawings may identify like components.

Referring to <FIG>, a hydrogen injection arrangement <NUM> can be included in a gas turbine system, such as the turbine system shown in <FIG> utilizing a multiple can or annular can combustion section arrangement (examples of which are shown in <FIG> and <FIG>). In other embodiments, the hydrogen injection arrangement <NUM> can be included into a turbine system that utilizes a different type of combustor section. The inclusion of the hydrogen injection arrangement <NUM> can be provided as part of a retrofit operation of a pre-existing gas turbine system or can be incorporated into a new design for a new gas turbine system or combustor for such a system that is to be installed at an industrial power plant or other type of plant.

As may best be seen from <FIG>, the hydrogen injection arrangement <NUM> can include an injector assembly that includes an outer conduit <NUM> configured to feed a flow of a mixture of air and fuel 3a (which can also be referred to as an air-fuel mixture) to the combustion chamber 2a of a combustor. The combustion chamber 2a can be defined by a combustion liner <NUM> of a combustor of a gas turbine system. The combustion chamber 2a provides a combustion space in which combustion of fuel can occur to generate a hot gas for outputting to a turbine of the gas turbine system. At least one swirler <NUM> can be positioned in the outer conduit <NUM> to facilitate a swirling flow of the air-fuel mixture 3a to be output into the combustion chamber 2a so that the output mixture of fuel and air includes a swirling output flow <NUM> of the air-fuel mixture that is injected into the combustion chamber 2a to flow along a pre-selected discharge path therein for combustion of the fuel within the combustion chamber 2a.

The one or more swirlers <NUM> can be positioned in the outer conduit <NUM> of the hydrogen injection arrangement <NUM> to swirl air before it is mixed with fuel. As may best be appreciated from <FIG>, the fuel can be fed to the air within the outer conduit <NUM> downstream of the swirler <NUM> and upstream of the outer conduit outlet 5b at which the mixture of fuel and air 3a is fed into the combustion chamber 2a. The mixture of fuel and air 3a within the outer conduit <NUM> that is formed can be considered an "Air-Fuel Premix" flow as the air and fuel are mixed before they are output into the combustion chamber for combustion of the fuel within the combustion chamber (e.g. they undergo pre-mixing within the outer conduit between the swirler <NUM> and the outlet of the outer conduit <NUM> at which the swirling mixture of air and fuel is fed into the combustion chamber 2a).

A flow of hydrogen can be passed through an inner hydrogen injection conduit <NUM> for output into the combustion chamber 2a for injection therein as a hydrogen injection flow. The hydrogen injection flow can be output at the outlet 7b of the inner hydrogen injection conduit <NUM> as at least one jet of hydrogen <NUM> (e.g. a single jet <NUM> or multiple jets <NUM>). In some embodiments, the outlet 7b for the inner hydrogen injection conduit <NUM> can be structured as a nozzle having a single output orifice or a nozzle having multiple output orifices. The outlet 7b of the inner hydrogen injection conduit <NUM> can be positioned inwardly relative to the outlet 5b of the outer conduit <NUM> such that the outlet 5b of the outer conduit <NUM> can be around an outer periphery of the outlet 7b of the inner hydrogen injection conduit <NUM>. For instance, the outlet 5b of the outer conduit <NUM> can surround the entire periphery of the outlet 7b of the inner hydrogen injection conduit <NUM> and the inner hydrogen injection conduit <NUM> can be arranged so its outlet 7b is positioned at a location that is inward relative to the outlet 5b of the outer conduit that is positioned around the periphery of the outlet 7b of the inner hydrogen injection conduit <NUM>. Embodiments can utilize any number of arrangements for the outlets of the inner hydrogen injection conduit <NUM> and outer conduit <NUM>.

In some embodiments, the outlet 7b of the inner hydrogen injection conduit <NUM> can be located in a central region or in a center of an annular opening of an annular shaped outlet 5b of the outer conduit <NUM>. The annular shaped opening of the outlet 5b of the outer conduit <NUM> can be a slot-like shape, a cross shape, an "x" like shape, a "Y" like shape, a "T" like shape, a "W" like shape, a "Z" like shape, an "N" like shape, an "M" like shape, an "F" like shape, an "E" like shape, a "D" like shape, a "C" like shape, a "U" like shape, a "V" like shape, a circular shape, an oval shape, a polygonal shape, or another type of shape. The outlet 7b of the inner hydrogen injection conduit can include a central orifice having a shape that matches the shape of the annular shaped opening of the outlet 5b of the outer conduit <NUM> and is positioned within the annular opening of the outlet 5b of the outer conduit <NUM>.

In some configurations, there can be one or more other conduits arranged between the inner hydrogen injection conduit <NUM> and the outer conduit <NUM>. For example, an annular shaped water injection conduit (not shown) can be positioned between the inner hydrogen injection conduit <NUM> and the outer conduit <NUM>. As another example an annular shaped purge air conduit can be positioned between the inner hydrogen injection conduit <NUM> and the outer conduit <NUM>. As yet another example, an annular shaped water injection conduit (not shown) as well as an annular shaped purge air conduit can be positioned between the inner hydrogen injection conduit <NUM> and the outer conduit <NUM>.

Different exemplary outlet configurations for the outlet 5b of the outer conduit <NUM> and the outlet 7b of the inner hydrogen conduit <NUM> that are configured to be in fluid communication with the combustion chamber 2a of a combustor of a gas turbine system can be appreciated from <FIG>. These different configurations can include, for example, a slot (<FIG>), cross, (<FIG>), zipper (<FIG>), or annular (<FIG>) type design. Yet other outlet configurations can be appreciated from <FIG> and <FIG> as well as the other examples discussed herein.

For example, as can be appreciated from <FIG>, the outlet 7b for the inner hydrogen injection conduit <NUM> can be a uniform circular or other shape single orifice outlet. The inner hydrogen injection conduit can include at least one intermediate cavity 7a that is positioned upstream of the outlet 7b within the inner hydrogen injection conduit <NUM>. Each cavity 7a can be positioned to adjust a velocity of the hydrogen injection flow as it passes through the inner hydrogen injection conduit <NUM> towards its outlet 7b so that the flow of the hydrogen over the cavity excites a periodic secondary flow within the cavity that acts to increase the level of turbulence of the hydrogen flow. We have found this cavity excitation and increase in hydrogen jet turbulence to be effective in increasing the rate of jet spreading and momentum transfer of the hydrogen jet with its surroundings as it discharges into the combustion chamber 2a.

Each cavity 7a can be positioned to help magnify jet-wake mass and momentum transport of one or more hydrogen jets <NUM> injected into the combustion chamber via the outlet 7b of the inner hydrogen injection conduit (as compared to a circular nozzle without such a cavity 7a or without multiple such cavities 7a). Each cavity 7a that is defined in the inner hydrogen injection conduit <NUM> can include a cavity depth d, a cavity length L, and a cavity trailing edge distance X, which is a distance between the downstream end of the cavity 7a and the outlet 7b. The outlet 7b can be circular in shape and have a diameter D, which is the diameter of the circular orifice through which the hydrogen passes to be directly fed into the combustion chamber 2a.

As may best be appreciated from <FIG>, each cavity 7a can be configured to have a particular depth d and length L and also be positioned to have a particular cavity trailing edge distance X from the outlet 7b of the inner hydrogen injection conduit <NUM>. The cavity depth d is preferably less than the diameter D of a circular orifice of the outlet 7b. In some embodiments, the cavity depth d can be greater than or equal to the radius of the orifice of the outlet 7b and also be less than or equal to the diameter D of the orifice of the outlet 7b (e.g. D/<NUM> ≤ d ≤ D). The cavity length L can be selected so that the length L is a value so that the ratio of length L to depth d is between <NUM> and <NUM> (e.g. <NUM> ≤ L/d ≤ <NUM>). The cavity trailing edge distance X can be selected so that the ratio of the cavity trailing edge distance X to the diameter D of the outlet 7b is no more than <NUM> (e.g. x/D ≤ <NUM>). We have determined that embodiments that utilize the cavity dimensional specifications are often able to provide an improved wake mass and momentum transport that is desirable for the hydrogen injection within the combustion chamber 2a - particularly (but not exclusively) when utilized in conjunction with a uniform sized single orifice outlet 7b for the inner hydrogen injection conduit <NUM>. The hydrogen output from the outlet 7b can be output as a hydrogen jet <NUM> of hydrogen gas that can be output at a pre-selected injection flow rate. The speed of the hydrogen jet <NUM> can be equal to or greater than <NUM>/s, greater than or equal to <NUM>/s, or a flow velocity that is up to the local speed of sound of hydrogen through the injector orifice defining the hydrogen gas outlet 7b.

The outlet 7b for the inner hydrogen injection conduit <NUM> can also be configured to have multiple spaced apart orifices for injection of hydrogen gas jets <NUM> into the combustion chamber 2a. It should be appreciated that each jet <NUM> of the hydrogen gas that is injected can be a flow of hydrogen gas that is output at a relatively high speed velocity. In some of these embodiments, the velocity of each jet can be equal to or greater than <NUM>/s, greater than or equal to <NUM>/s, or a flow velocity that is up to the local speed of sound of hydrogen through the injector orifice of the nozzle defining the outlet 7b.

The outlet 7b having a nozzle configuration to provide multiple jets <NUM> of hydrogen gas for injection into the combustion chamber 2a can be configured to have multiple injection zones. The injection zones can include a first central injection zone having at least one central injection jet of hydrogen 13a that is directed in a direction that is parallel to an axis of the burner <NUM> (e.g. an axial flow direction along which the flow of fuel, air and hydrogen pass through the outer conduit <NUM> and inner hydrogen injection conduit <NUM> for being injected into the combustion chamber 2a). In some embodiments, the first zone may just have a single central orifice <NUM>. However, it is contemplated that other embodiments could include multiple spaced apart central orifices <NUM> for providing a first zone of multiple central injection jets of hydrogen 13a.

The hydrogen gas injection zones for the nozzle defining the outlet 7b can also include a second zone. The second zone can be configured so that there are multiple second zone injection orifices <NUM> arranged along an outer circumference surrounding a periphery of at least one first zone central orifice <NUM> through which the at least one central injection jet of hydrogen 13a is output into the combustion chamber 2a. The second zone injection orifices <NUM> can be positioned to output non-central jets of hydrogen 13b so each of these jets are output at an angle Θ of greater than <NUM>° and less than <NUM>° relative to the axis of the burner <NUM> (e.g. non-axial flow directions) and/or a non-zero angle relative to the flow direction of a central injection jet of hydrogen 13a such that the non-central jet of hydrogen 13b is output in a flow direction that flows at an angle to the flow direction of the central jet of hydrogen 13a at an angle Θ that is greater than <NUM>° and less than <NUM>°. The outer second zone orifices <NUM> can be arranged so that the angle Θ at which the non-central jets of hydrogen 13b are output can range from greater than <NUM>° to less than <NUM>°, or more preferably can range from greater than or equal to <NUM>° and less than or equal to <NUM>°. Of course, outer second zone orifices <NUM> can be arranged and configured so that the angle Θ at which the non-central jets of hydrogen 13b are output can be within a different range, such as, for example, a range of greater than or equal to <NUM>° and less than or equal to <NUM>°, a range of greater than or equal to <NUM>° and less than or equal to <NUM>°, or some other range that may better meet a particular set of design criteria and the particular wake flow dynamics that may be present in a particular combustion chamber 2a for a particular operation of a gas turbine system.

In some embodiments, the one or more first zone central orifices <NUM> can emit one or more jets of hydrogen 13a so that they all flow in an axial direction and the outer second zone orifices <NUM> can emit the non-central jets of hydrogen 13b so that they all flow in non-axial directions. In other embodiments, the at least one first zone central orifice <NUM> and outer second zone orifices <NUM> can be arranged and configured so that at least one jet of hydrogen 13a can flow in an axial direction at least some of the non-central jets of hydrogen 13b can be output so that they flow in one or more non-axial directions.

The spaced apart peripheral second zone injection orifices <NUM> can be positioned so that a series of these orifices extend around a periphery of the at least one first zone central orifice <NUM> so that an entirety of the periphery is surrounded by the spaced apart second zone injection orifices <NUM> (an example of which may best be seen from <FIG>) or at least a portion of the periphery of the at least one first zone central orifice <NUM> is surrounded by the second zone injection orifices <NUM>. In yet other embodiments, an outlet 7b for the inner hydrogen injection conduits <NUM>, can be configured to only include outer injection orifices <NUM> such that there is no central injection jet of hydrogen 13a nor any first zone central zone orifice <NUM> defined in the outlet 7b.

The outlet 7b of the inner hydrogen injection conduit <NUM> be configured so that the one or more jets of hydrogen <NUM> interact with the prevailing flow field 12a generated by the swirling output flow <NUM> of the mixture of air and fuel output from the outlet 5b of the outer conduit <NUM> when that output flow <NUM> crosses the discharge region <NUM> of the outlet 7b of the inner hydrogen injection conduit <NUM> within the combustion chamber 2a at a location that is spaced apart from and downstream of the outlet 7b. For example, the prevailing flow field 12a can be generated from the swirling flow of the mixture of fuel and air swirling within the combustion chamber 2a and passing across and in front of the outlet 7b of the inner hydrogen injection conduit 7a at a position within the discharge region <NUM> that is spaced apart and downstream from the outlet 7b that is within the combustion chamber 2a. This position within the discharge region <NUM> can be a location within the combustion chamber 2a or a region within the combustion chamber 2a. A first wake region 12b of fluid can have at least one first wake 12c that is generated by this swirling flow of the mixture of air and fuel as the fuel combusts inside the combustion chamber 2a adjacent to and/or in the discharge region <NUM> of the inner hydrogen injection conduit <NUM> as the output flow <NUM> crosses the discharge region <NUM>.

The hydrogen injected into the combustion chamber 2a via the outlet 7b of the inner hydrogen injection conduit <NUM> can mix with the air and fuel as well as combustion products (e.g. CO<NUM>, CO, water vapor, etc.) from combustion of the fuel that can be directed into the discharge region <NUM> of the inner hydrogen injection conduit <NUM> within the combustion chamber 2a as a result of the first wake(s) 12c of fluid formed via combustion of the fuel occurring in the prevailing flow field 12a within the first wake region 12b adjacent the discharge region <NUM> of the inner hydrogen injection conduit <NUM>. The hydrogen can combust when mixing with the air and generate a secondary wake region <NUM> in the discharge region <NUM> of the inner hydrogen injection conduit <NUM> between the location at which the prevailing flow field 12a of the air-fuel mixture crosses the discharge region <NUM> of the inner hydrogen injection conduit <NUM> within the combustion chamber 2a and the outlet 7b of the inner hydrogen injection conduit <NUM>.

As may best be seen from <FIG> and <FIG>, the combustion of the hydrogen within the one or more jets <NUM> of hydrogen can generate an array of small flame structures 11b that forms via fluid and chemical communication between secondary wakes 11a of adjacent jets of hydrogen within the discharge region <NUM>. The secondary wakes 11a can also be referred to as second wakes.

The secondary wakes 11a can be formed within the combustion chamber 2a between the first wake region 12b and the outlet 7b of the inner hydrogen conduit and also between the position at which the mixture of fuel and air within the swirling output flow <NUM> of the mixture of air and fuel crosses the discharge region <NUM> of the outlet 7b of the inner hydrogen injection conduit <NUM> within the combustion chamber 2a and the outlet 7b of the inner hydrogen injection conduit <NUM>.

The small flame structures 11b can be provided by the relatively high nozzle velocity hydrogen jets <NUM>, which can create a multiplicity of secondary jet wake flows 11a that can each entrain lean premix air-natural gas reactants and hot products of combustion into the hydrogen jet <NUM> for combustion of the hydrogen in the combustion chamber 2a to form the small flame structures 11b in the flows of the secondary jet wakes 11a. These small flame structures 11b can help provide improved mixing of air and fuel due to the combustion of the hydrogen while also helping to transport heat from the combustion away from the burner <NUM> due to the transport of momentum provided by the velocity of the hydrogen jets in combination with the combustion of the hydrogen to form the flame structures. The combustion of hydrogen within the secondary wake region <NUM> can help avoid zones of decreased mixing of air and fuel to mitigate or avoid combustion instability from the fuel combusting in the combustion chamber.

For example, the interaction of the hydrogen combusting in a secondary wake region <NUM> located in the combustion chamber 2a can help improve flame stability of the burner <NUM> and combustion stability within the combustion chamber 2a. For instance, the one or more central injection jets of hydrogen 13a can be output in a flow direction that is opposed to the streamline of the reverse flow field generated by the swirling output flow <NUM> of the mixture of air and fuel output from the outlet 5b of the outer conduit <NUM> of the burner <NUM> generated via the one or more swirlers <NUM> of the burner <NUM> can interact with this first wake region inside the combustion chamber 2a. A detailed nature of this flow interaction between the injected hydrogen and the swirling flow of the air-fuel mixture can be dependent on the relative momenta of the hydrogen jet(s) <NUM> and the recirculated flow along the jet burner axis. However, We have determined that the presence of high shear rates, high turbulence intensity, and opposing flows can provide an efficient method by which mixing and subsequent combustion can occur that provide viable energy and chemical radical species as a result of the combustion which is then communicated fluidically through the first wake recirculation flow to the peripheral hydrogen jets, if present, as well as the swirling flow of air and fuel from the main burner as the mixture of air and fuel enters into the combustion space via the outlet 5b of the outer conduit.

Hydrogen introduced into the combustion chamber 2a via the outer injector orifices <NUM> can further enhance such an effect to help provide a further improvement in lean combustion stability. The divergent non-central jets of hydrogen 13b that can be output in flow directions that are nominally parallel to the shear layer between the toroidal recirculation vortex and the swirling flow <NUM> of the air-fuel mixture discharging from the outlet 5b of the outer conduit <NUM> can create a multiplicity of diffusion flames whose reaction rates are augmented due to the presence of the hydrogen as well as the heat and radicals convected from the reaction zone of the central hydrogen jet(s) 13a. The combustion of the hydrogen and its interaction with the swirling flow <NUM> of the mixture of air and fuel can help improve combustion stability within the combustion space of the combustion chamber 2a when the air-fuel mixture is a lean mixture having an excess of oxygen relative to the fuel within the mixture (e.g. there is more oxygen within the mixture than needed to fully combust the fuel within the flow).

<FIG> further illustrates the interaction between the injected hydrogen and the output mixture of fuel and air from the burner <NUM> in an exemplary interaction process that can result from the operation of the exemplary burner <NUM> having the outer conduit <NUM> and the inner hydrogen injection conduit <NUM>. The secondary wake region <NUM> can include at least one secondary wake 11a adjacent each hydrogen output orifice, which can create one or more small recirculation zones within the secondary wake region <NUM> in a first step S1 of the exemplary process. Flames, or flame structures 11b, formed in secondary wake region <NUM> can communicate heat and active chemical species (e.g. radicals) to local hydrogen jet <NUM> and adjacent secondary wakes 11a in a second step S2 of the exemplary process. The ignited jets <NUM> can communicate heat and active chemical species to the larger at least one first wake 12c formed from the fuel combusting in the combustion chamber 2a as it is output from the outlet 5b of the outer conduit <NUM> and passes across the discharge region <NUM> of the outlet 7b of the inner hydrogen injection conduit <NUM> in a third step S3 of the exemplary process. The hot, activated gases in the first wake(s) 12c from combustion of the fuel can communicate heat and active chemical species to the output flow exiting burner <NUM> in a fourth step S4 of the exemplary process. The interaction between the first wake(s) 12c and second wakes 11a of the secondary wake region <NUM> can facilitate improved combustion stability as a consequence of the combustion of hydrogen interacting with combustion gases of the first wake(s) 12c in a fifth step S5 of the exemplary process. This interaction can include, for example, activated gas in the one or more first wakes 12c from combustion of fuel communicating heat and active chemical species with the one or more second wakes 11a.

We believe the improved combustion stability and gas turbine system performance that can be provided by embodiments of my hydrogen injection arrangement <NUM> is due to a number of factors. For instance, We believe that the kinetic energy of each relatively high velocity hydrogen jet <NUM> can act as a pump that can entrain local mass in proportion to its velocity while generating local turbulence within the combustion chamber 2a that enhances mixing. The enhanced mixing can help reduce temperature stratifications; which can lower peak flame temperatures and thereby reduce NOx emissions. As another example, We believe that the high velocity hydrogen injection jet(s) <NUM> can help to convectively transport the heat released during the combustion of the hydrogen so that this heat is transported away from the nozzle, which can prevent nozzle overheating.

Embodiments of the hydrogen injection arrangement <NUM> that utilize multiple hydrogen jets <NUM> can provide relatively high nozzle velocity hydrogen jets to create a multiplicity of secondary jet wake flows 11a that can each entrain lean premix air-natural gas reactants and hot products of combustion into the hydrogen jet. Due to the low ignition energy of hydrogen, the excess oxygen available in the entrained mass and the elevated temperature of combustion products, the hydrogen - entrained gas mixture is readily ignited within the relatively low velocity secondary wake region <NUM> within the combustion chamber 2a - which can be a region near the outlet of the burner <NUM> that is located upstream of where the swirling flow <NUM> of the air-fuel mixture output from the outlet 5b of the outer conduit <NUM> may pass within the combustion chamber as it is injected therein such that this secondary wake region <NUM> is between the outlet 7b of the inner hydrogen injection conduit <NUM> and the region within the combustion chamber that is axially spaced apart from the outlet within the combustion chamber at which the swirling flow <NUM> output from the outer conduit's outlet 5b will pass.

The multiplicity of secondary wake ignition sources that can be provided by the multiple jets <NUM> of injected hydrogen (e.g. hydrogen injected via first zone and second zone orifices <NUM> and <NUM>, etc.) can generate an array of small flame structures within the combustion chamber 2a in the secondary wake region <NUM> that each act as a miniature "pilot" flame to adjacent hydrogen jets <NUM>. We have determined that this can provide a synergistic effect among adjacent hydrogen jets <NUM> that can unexpectedly provide a much higher level of flame stability as compared to use of a single hydrogen jet <NUM> of the same mass flow rate as the cumulative sum of flow rates from the multiple hydrogen jets <NUM>.

'In some embodiments, the central (axial) injection of hydrogen that can be provided by the at least one central injection jet 13a of hydrogen can be output so this central jet can mix with recirculated gases in the wake of the burner <NUM> at or below an equivalence ratio of unity, which can be an operational mode in which the mixture thus created in the burner wake within the combustion chamber 2a remains stoichiometric or lean. Hydrogen injected above the stoichiometric amount can constitute an excess reactant that can become diluted in its effect as it mixes with other gases outside the burner wake. Expressed mathematically, assuming that the ratio of hydrogen to a fuel flow rate is much less than unity, it can be shown that this ratio is equal to: <MAT> Where m,H2,central,max is the maximum allowable central hydrogen injection mass flow rate; m,Fuel is the burner fuel flow rate, m,recirc is the mass flow recirculation (i.e. reverse flow) rate in the burner first wake region; m,total is the total burner flow rate and Φ is the equivalence ratio accounting for only air and fuel injected through the burner. It should be understood that the recirculation gas flow rate (m,recirc) can be a function of the main premix burner swirl number and average axial injection velocity that may either be estimated by empirical correlation (available in the public domain) or via computational fluid dynamics modeling.

For embodiments in which the fuel is methane (CH<NUM>), the m,Fuel variable would be the mass flow rate of methane injected into the combustion chamber 2a via the outlet 5b of the outer conduit <NUM>. Of course, this fuel flow rate value may be different depending on the type of fuel utilized in the combustion chamber 2a as the fuel could alternatively be propane, liquefied petroleum gas, fuel oil, No. <NUM> fuel oil, kerosene, or a synthetic gas made from another type of fuel (e.g. carbon, etc.) or another type of suitable fuel.

Embodiments of the hydrogen injection arrangement <NUM> can be configured for utilization in gas turbine systems to provide a co-firing of hydrogen with a primary fuel (e.g. natural gas, propane, liquefied petroleum gas, No. <NUM> fuel oil, kerosene, synthetic gases made from other fuels, etc.). The hydrogen injection arrangement <NUM> can be utilized to facilitate different types of operation of the gas turbine system. For instance, the arrangement can be utilized to help lower the overall combustor stoichiometric ratio utilized during operation of the gas turbine system. As another example, the hydrogen injection arrangement <NUM> can be utilized to help facilitate an increased combustor axial fuel staging.

For instance, the hydrogen injection arrangement <NUM> can be employed to use the hydrogen for lowering the overall equivalence ratio of the combustor relative to the low equivalence ratio limit attainable without hydrogen injection (based on hydrogen, primary fuel and air flow rates, where the primary fuel can be the fuel included in the mixture of fuel and air output into the combustion chamber via the outer conduit <NUM>). This can occur by the injected hydrogen offsetting the ratio of fuel to available oxygen to provide for an increased proportion of oxygen so that a lower equivalence ratio for the combustion occurring within the combustion space of the combustor chamber 2a. An objective of such an operational strategy for a gas turbine system can be to either facilitate extended turbine load reduction and/or to lower combustor NOx emissions without increasing carbon monoxide (CO) emissions. It can be shown that the relationship among the reactant flow rates for this operational case is equal to: <MAT> where:.

The injection of hydrogen can be controlled so that the operation of one or more of the combustors of the gas turbine system (or all of the combustors of the gas turbine system) is constrained by the above relationship to control operations of the gas turbine system and/or the combustor(s):
Hydrogen injection can also (or alternatively) be employed via an exemplary embodiment of the hydrogen injection arrangement <NUM> to facilitate a larger magnitude staging of fuel or air for NOx reduction purposes in a gas turbine combustor of a gas turbine system. For example, with fuel-staged combustion, fuel can be diverted away from the outlet of the burner <NUM> and introduced at a downstream location of the combustor. <FIG>, may best illustrate such a configuration as at least one control valve <NUM> of a fuel feed system for the combustor can be configured to permit a portion of the fuel feed to flow to the outer conduit <NUM> for pre-mixing with air for being output from the outlet 5b of the outer conduit while another portion of the fuel can be routed for being fed into the combustor chamber 2a downstream of the burner <NUM>. In such situations, the main burner <NUM> of the combustor can run with a lower equivalence ratio than would be employed without fuel staging. The degree of fuel staging is in many cases limited by lean combustion stability limits of the main burner <NUM>. By utilization of hydrogen injection via an embodiment of my hydrogen injection arrangement <NUM>, the burner's lean combustion safe operating limit can be extended, which can drive a greater NOx reduction by increasing the proportion of axially-staged fuel.

It should be appreciated that modifications to the embodiments explicitly shown and discussed herein can be made to meet a particular set of design objectives or a particular set of design criteria. For example, embodiments of the hydrogen injection arrangement <NUM> can utilize a single output orifice or multiple output orifices for injecting one or more jets of hydrogen gas into the combustion chamber at a pre-selected flow rate or a flow rate within a pre-selected hydrogen injection flow rate range. In some embodiments, such a range may be less than <NUM>/s or less than <NUM>/s. In yet other embodiments such a range can be higher than <NUM>/s or higher than <NUM>/s.

As another example, the size and shape of the inner hydrogen injection conduit <NUM> and outer conduit <NUM> can be any type of suitable size and shape to meet a particular set of design criteria for the operational performance of a particular gas turbine system. For instance, some embodiments may be quite large while others can be smaller to account for the size of the combustor in which it is to be utilized and the operational requirements for that combustor.

As yet another example, embodiments of the hydrogen injection arrangement <NUM> can be configured to inject one or more jets <NUM> of hydrogen that is <NUM>% hydrogen gas or that has another composition (e.g. more than <NUM>% hydrogen gas by volume and less than <NUM>% other gases by volume, etc.). Other gas elements that can be included in the hydrogen gas jets <NUM> can include nitrogen or carbon dioxide, for example. It should be appreciated that the injected hydrogen jet(s) <NUM> can include a composition of hydrogen that is at least <NUM>% by volume hydrogen, at least <NUM>% by volume hydrogen, at least <NUM>% by volume hydrogen, at least <NUM>% by volume hydrogen, or at least <NUM>% by volume hydrogen. The particular composition of the hydrogen jet flow rate utilized in a particular embodiment of the hydrogen injection arrangement may depend on the source of the hydrogen being injected and other operational or design criteria for the gas turbine system.

The gas turbine system as well as the hydrogen injection arrangement <NUM> that can be incorporated into the system can be configured to include process control elements positioned and configured to monitor and control operations (e.g. temperature and pressure sensors, flow sensors, an automated process control system having at least one work station that includes a processor, non-transitory memory and at least one transceiver for communications with the sensor elements, valves, and controllers for providing a user interface for an automated process control system that may be run at the work station and/or another computer device of the system, etc.).

Claim 1:
A method of injecting hydrogen into a combustion chamber (2a) of a combustor of a gas turbine system, the method comprising:
outputting a mixture of fuel and air (3a) into the combustion chamber (2a) via an outlet (5b) of an outer conduit (<NUM>) in fluid communication with the combustion chamber (2a);
injecting at least one jet of hydrogen (<NUM>) into the combustion chamber (2a) via an outlet (7b) of an inner hydrogen injection conduit (<NUM>) that is in fluid communication with the combustion chamber (2a), and
the outer conduit (<NUM>) being positioned such that the outlet (5b) of the outer conduit (<NUM>) is around an outer periphery of the outlet (7b) of the inner hydrogen injection conduit (<NUM>), wherein a burner (<NUM>) of the combustor includes the outer conduit (<NUM>),
characterized in that the injecting of the at least one jet of hydrogen (<NUM>) into the combustion chamber (2a) via the outlet (7b) of the inner hydrogen injection conduit (<NUM>) is performed to control operation of the gas turbine so that a ratio of hydrogen to fuel flow rate is provided so that an equivalence ratio for the combustor is equal to: <MAT> where:
m,H2,central,max is a maximum allowable central hydrogen injection mass flow rate;
m,Fuel is a fuel flow rate of the fuel for the burner,
m,recirc is a mass flow recirculation rate in a first wake region of the burner;
m, total is a total burner flow rate; and
Φ is the equivalence ratio accounting for only the air and the fuel injected through the outlet of the outer conduit.