CN103438480A - Nozzle and combustor for a gas turbine engine, and corresponding methods - Google Patents

Abstract

The present invention discloses a combustor for a gas turbine engine. The combustor has a head end portion carrying at least one fuel/air nozzle. Each fuel/air nozzle includes a premix pilot nozzle having a premix duct with a concentric shaft directing the fuel/air mixture axially from the premix pilot nozzle . The premix pilot nozzle may include an annular passage disposed radially outwardly from the premix and including air jets directing air radially outwardly from the premix duct.

Description

Nozzle, combustor and corresponding method for gas turbine engine

technical field

The present invention generally relates to a gas turbine engine that combusts a hydrocarbon fuel mixed with air to generate a high temperature gas flow that drives turbine blades to rotate a shaft attached to the blades, and more particularly to Fuel nozzles for engines with pilot nozzles that premix fuel and air while achieving low levels of nitrogen oxides.

Background technique

Gas turbine engines are widely used to generate electricity for many applications. A conventional gas turbine engine includes a compressor, a combustor, and a turbine. In a typical gas turbine engine, a compressor provides compressed air to a combustor. Air entering the combustion chamber is mixed with fuel and burned. The hot gases of the combustion are exhausted from the combustion chamber and flow into the blades of the turbine, which rotates a shaft in the turbine connected to the blades. Some of the mechanical energy generated by the rotating shaft drives the compressor and/or other mechanical systems.

Since government regulations do not permit nitrogen oxides to be vented to the atmosphere, production of nitrogen oxides as a by-product of gas turbine engine operation strives to remain below tolerances. One path to complying with such regulations is to move from flame-diffusion combustors to combustors that use a fully premixed operating mode with a lean fuel and air mixture to reduce, for example, nitrogen oxides (commonly denoted as NOx) and carbon monoxide (CO ) emissions. These combustors are variously known in the art as dry low NOx (DLN), dry low emission (DLE) or lean premixed (LPM) combustion systems.

Fuel-air mixing affects the level of nitrogen oxides formed in the hot gases combusted by a gas turbine engine and the performance of the engine. Gas turbine engines may employ one or more fuel nozzles to intake air and fuel to facilitate fuel/air mixing in the combustor. The fuel nozzles may be located in the head end portion of the combustion chamber and may be configured to draw in a flow of air to be mixed with the fuel input. Typically, each fuel nozzle may be internally supported by a centerbody located inside the fuel nozzle, and a pilot burner may be mounted at a downstream end of the centerbody. For example, as described in U.S. Patent No. 6,438,961, which is hereby incorporated by reference in its entirety for all purposes, a so-called swozzle may be mounted to the outside of the center body, upstream of the pilot burner . The swozzle has curved vanes extending radially from the center body through the annular flow passage, and fuel is directed from the curved vanes into the annular flow passage for entrainment into the air flow swirled by the swozzle.

Various parameters describing the combustion process in gas turbine engines are associated with the formation of nitrogen oxides. For example, higher gas temperatures in the combustion reaction zone are responsible for the higher formation of nitrogen oxides. One way to lower these temperatures is to premix the fuel-air mixture and reduce the ratio of fuel to air that undergoes combustion. As the ratio of fuel to air being combusted decreases, the amount of nitrogen oxides produced decreases. However, there is a balance in the performance of gas turbine engines. Because the fuel nozzle flame is more likely to extinguish as the ratio of fuel to air being combusted decreases, presenting an unstable operation of the gas turbine engine. Flame spreader type burners have been used to better stabilize the flame in the combustion chamber, but NOx also increases.

Contents of the invention

Various aspects and advantages of the invention will be set forth in the following description, or may be obvious from the description, or may be learned by practice of the invention.

In theory, the closer theory involves that at each point in the combustion chamber there is a stoichiometric relationship between the fuel undergoing combustion at a given combustion temperature and the air that will be formed as a by-product of combustion The amount of nitrogen oxides is minimized. Using a fuel nozzle configured as described below, a more uniform equivalence ratio can be achieved at the centerbody tip plane of the outer nozzle, thereby closer to this theoretical condition for achieving the desired stoichiometric relationship in the combustion chamber of a gas turbine engine , the desired stoichiometric relationship is the stoichiometric relationship between fuel and air undergoing combustion at a given combustion temperature. In addition, in order to overcome one of the disadvantages of flame diffusion type pilot burners, premix pilot burners can also be used as pilot burners to stabilize the pilot flame and prevent the amount of NOx from increasing even when the ratio of fuel to air is low.

In one embodiment of the fuel nozzle, the fuel nozzle comprises premixing ducts configured with concentric axes parallel to the burner tube axis to direct the fuel/air mixture axially from the premixing pilot nozzles; each premixing duct adjacent to at least one air jet, wherein each air jet is directed radially outward from the premix duct such that each air jet may entrain some portion of the fuel/air mixture to direct the mixture radially outward from the premix duct, This results in a more uniform fuel/air mixture in the combustion exit plane of the nozzle before entering the combustion chamber of the gas turbine. The air jets are contemplated at the downstream end of the annular passage arranged radially outwardly of the premixing duct.

In another embodiment of the invention, each premixing duct is itself concentrically arranged about a central longitudinal axis disposed at an acute angle with respect to the axis of the burner tube to direct the fuel/air mixture radially outward about the axis of the burner tube , resulting in a more uniform fuel/air mixture in the combustion exit plane of the nozzle before entering the combustion chamber of the gas turbine.

In another embodiment of the invention, each premixing duct is itself arranged concentrically around a bidirectional central longitudinal axis having a first leg arranged parallel to the axis of the burner tube and with respect to the burner tube A second leg set at an acute angle to the axis of the combustion tube to direct the fuel/air mixture radially outward around the axis of the burner tube, resulting in a more uniform fuel/air mixture in the combustion exit plane of the nozzle before entering the gas turbine in the combustion chamber.

In yet another embodiment of the fuel nozzle wherein each premixing duct is itself concentrically disposed about a central longitudinal axis disposed at an acute angle with respect to the axis of the burner tube to direct the fuel/air mixture around the axis of the burner tube. Outwardly directed; there is at least one air jet next to each premixing duct, such that each air jet entrains some portion of the fuel/air mixture to further direct the mixture radially outward from the premixing duct, allowing combustion at the nozzle A more homogeneous fuel/air mixture is formed in the exit plane before entering the combustion chamber of the gas turbine. In addition, one or more of the air jets are intended to be directed radially outward from the premixing ducts to entrain some portion of the fuel/air mixture to further direct the mixture radially outward from the premixing ducts to A more uniform fuel/air mixture is created in the combustion exit plane of the nozzle before entering the combustion chamber of the gas turbine.

Those of ordinary skill in the art will better understand the features and aspects of such embodiments, among others, by viewing the description.

Description of drawings

The remainder of this specification, with reference to the accompanying drawings, discloses the invention in complete and achievable detail for those skilled in the art, including its best mode, wherein:

1 is a block diagram of a turbine system having a fuel nozzle connected to a combustor in accordance with an embodiment of the present technology;

Figure 2 is a cross-sectional view of portions of a combustor in a gas turbine system of the present invention;

Figure 3 depicts an exemplary embodiment of a component of the present invention in partial perspective and partial cross-sectional view;

Figure 4 depicts another exemplary embodiment of a component of the present invention in cross-sectional view;

Fig. 5 is a cross-sectional view taken along the line of sight marked 5-5 in Fig. 4;

Figure 6 depicts a further exemplary embodiment of a component of the present invention in cross-sectional view;

Figure 7 depicts a further exemplary embodiment of a component of the present invention in cross-sectional view;

FIG. 8 depicts an alternative exemplary embodiment of the portion bounded by the dashed line labeled numeral 8 in FIG. 6 in cross-sectional view;

Figure 9 depicts another exemplary embodiment of a component of the present invention in a cross-sectional view similar to that shown in Figure 4;

Figure 10 schematically represents an embodiment of the method of the present invention for operating a fuel/air nozzle of a gas turbine engine; and

Figure 11 schematically shows an alternative embodiment of the method of the present invention for operating a fuel/air nozzle of a gas turbine engine.

Detailed ways

Reference will now be made in detail to various embodiments of the invention, one or more examples of which are illustrated in the drawings. Numeral and letter designations are used in the detailed description to refer to features in the drawings. The same or similar symbols in the drawings and descriptions are used to refer to the same or similar parts of the embodiments of the present invention.

Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, those skilled in the art will readily appreciate that various modifications and changes can be made in the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and changes as come within the scope of the appended claims and their equivalents.

It should be understood that unless otherwise stated, the ranges and limits mentioned in this patent application document include all subranges within the stated limits, including the limits themselves. For example, a range from 100 to 200 also includes all possible subranges, eg, 100 to 150, 170 to 190, 153 to 162, 145.3 to 149.6, and 187 to 200. Furthermore, a limit of up to 7 also includes up to 5, up to 3, and up to 4.5, and includes all subranges within that limit, such as from about 0 to 5 inclusive, and from 5.2 to 7, These include 5.2 and 7.

Referring to FIG. 1 , a simplified diagram of portions of a gas turbine system 10 is illustrated. Turbine system 10 may operate on liquid or gaseous fuels, such as natural gas and/or hydrogen-rich syngas, to operate turbine system 10 . As shown, a plurality of fuel nozzles 12 of the type described more fully below draw in a fuel supply 14 , mix the fuel with air, and distribute the air-fuel mixture into a combustion chamber 16 . The air-fuel mixture is combusted in a chamber within combustor 16 , producing hot pressurized exhaust gas. Combustion chamber 16 may direct exhaust gas to flow through turbine 18 to exhaust port 20 . As the exhaust gas passes through the turbine 18 , the gases drive one or more turbine blades along the axis of the system 10 to rotate the shaft 22 . As shown, the shaft 22 may be connected to various components of the turbine system 10 , including the compressor 24 . Compressor 24 also includes blades connectable to shaft 22 . As the shaft 22 rotates, blades within the compressor 24 also rotate, thereby compressing air from the air intake 26 through the compressor 24 and into the fuel nozzles 12 and/or the combustor 16 . The shaft 22 may also be connected to a load 28, which may be a vehicle load or a stationary load, such as a generator in a power plant or a propeller on an aircraft. It will be appreciated that load 28 may include any suitable device capable of being powered by the rotational output of turbine system 10 .

FIG. 2 is a simplified diagram of a cross-sectional view of portions of the gas turbine system 10 schematically depicted in FIG. 1 . As shown schematically in FIG. 2 , the turbine system 10 includes one or more fuel/air nozzles 12 located at a head end portion 27 of one or more combustors 16 in a gas turbine engine. Each illustrated fuel nozzle 12 may comprise a plurality of fuel nozzles integrated together and/or an individual fuel nozzle, wherein each illustrated fuel nozzle 12 relies at least substantially or entirely on internal structural support (e.g., to withstand fluid path load). Referring to FIG. 2 , the system 10 includes a compressor portion 24 for pressurizing a gas (eg, air) that flows into the system 10 via an air inlet 26 . In operation, air enters turbine system 10 through air intake 26 and may be pressurized in compressor 24 . It should be understood that although the gas may be referred to in this patent application as air, the gas may be any gas suitable for use in the gas turbine system 10 . The pressurized air discharged from the compressor section 24 flows into the combustor section 16, which is generally characterized by a plurality of combustors 16 (only one combustor is shown in FIGS. 1 and 2 ) arranged in a ring around the axis of the system 10. Array settings. Air entering combustor portion 16 is mixed with fuel and combusted within combustion chamber 32 of combustor 16 . For example, fuel nozzles 12 may inject a fuel/air mixture into combustion chamber 16 at an appropriate fuel-to-air ratio for optimal combustion, emissions, fuel consumption, and electrical power output. Combustion generates hot pressurized exhaust gas, which then flows from each combustor 16 to a turbine section 18 (shown in FIG. 1 ) to drive system 10 and generate electricity. The hot gases drive one or more blades (not shown) within turbine 18 to rotate shaft 22 , thereby rotating compressor 24 and load 28 . Rotation of the shaft 22 rotates the blades 30 within the compressor 24 and draws in and pressurizes the air received by the air intake 26 . It should be readily understood, however, that the combustor 16 need not be in the configuration described above and in this patent application document, and may generally be in any configuration that enables pressurized air to mix with fuel, combust, and enter the turbine portion 18 of the system 10 .

3 to 9 schematically illustrate various embodiments of the fuel/air nozzle 12 according to an exemplary embodiment of the present invention. For example, in each of Fig. 4, Fig. 8 and Fig. 9, each upstream end of at least each premixing duct 41 is provided with a central shaft 41d configured and arranged so that each premixing The fluid flow of the inlet hole 66 a of the conduit 41 is directed parallel to the central axis 36 of the central body 52 . For example, in each of Figures 6 and 7, at least each upstream end of each premixing conduit 41 is provided with a central axis 41d configured and arranged such that the The fluid flow of the inlet aperture 66a is directed at an acute angle to the central axis 36 of the central body 52, the acute angle being in the range of 0.1 degrees to 20 degrees. For example, as shown schematically in FIG. 3 , one embodiment of the fuel/air nozzle 12 includes a premix duct 41 configured with a concentric axis parallel to the burner tube axis 36 to direct the fuel/air mixture from the premix to the nozzle 40. Axially guided. In the various embodiments shown schematically in Figures 4, 5 and 9, there is at least one air jet 42 next to each premixing duct 41, wherein each air jet 42 can entrain some of the fuel/air mixture. part to direct the mixture radially outward from the premixing duct 41 to create a more uniform fuel/air mixture in the combustion exit plane 44 of the nozzle 12 before entering the combustion chamber 16 (shown in FIGS. 1 and 2 ). chamber 32. In the embodiment depicted in FIGS. 4 and 5 , each air jet 42 is intended to be directed radially outward from the premix duct 41 so that each air jet 42 can more easily entrain more fuel/air mixture to Directing more mixture radially outward from the premixing duct 41 creates a more uniform fuel/air mixture in the combustion exit plane 44 of the nozzle 12 before entering the combustion chamber 16 (shown in FIGS. 1 and 2 ) chamber 32.

For example, as shown schematically in FIG. 3 , a fuel/air nozzle 12 for a gas turbine engine is contemplated to include an axially extending peripheral wall 50 that defines the outer shell of the nozzle 12 . The peripheral wall 50 of the fuel/air nozzle 12 has an outer surface 50a and an inner surface 50b facing away from the outer surface 50a and defining an axially extending lumen 50c.

For example, as shown schematically in FIG. 3 , a fuel/air nozzle 12 for a gas turbine engine is contemplated to include a hollow, axially extending center body 52 disposed within a lumen 50c of the fuel/air nozzle 12 and having a A central axis 36 which is identical to the central axis of the combustion tube. The center body 52 is bounded by a center body wall 52a that defines an upstream end 52b and a downstream end 52c axially opposite the upstream end 52b. The central body wall 52a is bounded by an outer surface 52d and an inner surface 52e facing away from the outer surface 52d. The inner surface 52d of the centerbody wall 52a defines an axially extending internal passageway 53 that is concentrically disposed about the central axis 36 of the centerbody 52 . The primary air flow passage 51 is defined in an annular space between the inner surface 50b of the peripheral wall 50 and the outer surface 52d of the center body wall 52a.

For example, as shown schematically in FIG. 3 , a fuel/air nozzle 12 for a gas turbine engine is contemplated to include an axially extending hollow fuel supply tube 54 extending axially through an internal passage 53 of a centerbody 52 . Fuel supply tube 54 has an upstream end 54a disposed at upstream end 52b of center body 52 and configured for connection to a fuel source (not shown). The fuel supply tube 54 has a downstream end 54b disposed at the downstream end 52c of the central body 52 . The secondary air flow passage is bounded by the annular space between the inner surface 52e of the center body 52 and the outer surface of the fuel supply tube 54 and defines an axially extending inner passage 53 shown schematically in FIG. 3 .

As shown schematically in FIG. 3 , primary fuel may be supplied to the combustion chamber 32 of the combustor 16 (shown in FIG. 2 ) through a plurality of air swirler vanes 56 which are fixed and extend The flow path through the primary air flow channel 51 . These air swirler vanes 56 constitute so-called swozzles extending radially from the outer surface of the central body wall 52a. As shown schematically in FIG. 3, each air swirler vane 56 of the swozzle is expected to have an inner fuel conduit 57 terminating in a fuel injection port or hole 58 from which primary fuel (designated by numeral 57a) flows. ) can be injected from the fuel injection ports or holes 58 into primary air (shown by arrows labeled 51 a ) that flows through the fuel injection ports in the air swirler vanes 56 58. As the primary airflow 51a is directed against the air swirler vanes 56, a swirl pattern may be imparted to the primary airflow 51a to promote mixing of the primary airflow 51a with the primary fuel passing from the air swirler vanes. The holes 58 of 56 inject into the passing primary air flow 51a. The primary air flow 51a mixed with the primary fuel may then flow into a premixing ring 51 defined between the peripheral wall 50 and the inner center body 52, wherein the primary air flow 51a and primary fuel continue to mix together, It then enters the combustion chamber 32 .

For example, as shown schematically in FIG. 3 , a fuel/air nozzle 12 for a gas turbine engine is contemplated to include a premixing pilot nozzle 40 having an upstream end 40 a connected to a downstream end 52 c of a center body 52 . In the embodiment depicted in FIG. 3 , the downstream end 52 c of the central body 52 and the upstream end 40 a of the premixing pilot nozzle 40 are partially formed from different parts of the metal cylinder forming the central body 52 and the outermost portion of the premixing pilot nozzle 40 is defined. layer walls to define. The premix pilot nozzle 40 has a downstream end 40b axially opposite the upstream end 40a of the premix pilot nozzle 40 .

For example, as shown schematically in Figures 3, 4 and 9, the premixing pilot nozzle 40 is provided with a pilot fuel nozzle 60 having an upstream end 60a and a downstream end 60b. For example, as shown schematically in FIGS. 4 and 9 , the upstream end 60a of the pilot burner fuel nozzle 60 is in fluid communication with the downstream end 54b of the fuel supply tube 54 . The downstream end 60b of the pilot fuel nozzle 60 is provided with at least one fuel jet 61 configured to be in fluid communication with the upstream end 60a of the pilot fuel nozzle 60 . For example, fuel 62 entering the pilot fuel nozzle 60 through the downstream end 54b of the fuel supply tube 54 passes through a plurality of fuel nozzles 61 (shown in phantom in FIG. 5 ) as shown schematically by the arrow labeled 62 in FIGS. Exit pilot fuel nozzle 60 .

For example, as shown schematically in FIGS. 3 , 4 and 9 , the premixing pilot nozzle 40 is further provided with an annular fuel chamber wall 63 disposed radially outward from the pilot fuel nozzle 60 and is expected to Concentric with respect to fuel tube axis 36 shown in FIG. 3 . For example, as shown schematically in FIGS. 3 , 4 and 9 , a fuel chamber wall 63 defines a fuel chamber 64 leading between the fuel nozzle 60 and the fuel chamber wall 63 . For example, as shown schematically in FIGS. 4 and 9 , the fuel chamber wall 63 further defines a plurality of fuel holes 63 a through which fuel is expelled from the fuel chamber 64 . For example, as shown schematically in FIGS. 4 and 9 , at least one fuel hole 63 a is in fluid communication with at least one fuel nozzle 61 through a fuel chamber 64 . Ideally, each fuel hole 63 a is in fluid communication with each fuel nozzle 61 through the fuel chamber 64 .

For example, as shown schematically in FIGS. 3 , 4 and 9 , the premixing pilot nozzle 40 is further provided with a plurality of axially extending hollow premixing ducts 41 , and the premixing ducts 41 extend radially from the fuel chamber wall 63 to external settings. For example, as shown schematically in the embodiment depicted in FIGS. 4 and 9 , each premixing duct 41 is contemplated to be partially bounded by a partition wall 63 . For example, as shown schematically in FIG. 3 , each premixing conduit 41 has an upstream end 41 a disposed near the downstream end 52 c of the central body 52 . For example, as shown schematically in FIGS. 4 and 9 , each premixing conduit 41 is provided at its upstream end 41 a with an inlet aperture 66 a in fluid communication with the internal passage 53 of the center body 52 . The arrows labeled 53a in FIGS. 4 and 9 schematically indicate the air flow 53a that enters the inlet aperture 66a of each premixing duct 41 from the internal passage 53 of the central body 52 .

For example, as shown schematically in FIGS. 4 and 9 , each premixing conduit 41 is in fluid communication with at least one fuel aperture 63 a defined in the fuel chamber wall 63 of the fuel chamber 64 . Arrows labeled 62a in FIGS. 4 and 9 schematically indicate fuel flow 62a that exits fuel chamber 64 through fuel holes 63a defined in fuel chamber wall 63 and then enters each premixing conduit 41 . The arrow labeled 62b in FIGS. 4 and 9 schematically indicates a fuel-air mixture flow 62b that flows downstream in the premixing duct 41 of the premixing pilot nozzle 40 .

For example, as shown schematically in Figures 4 and 9, each premixing duct 41 has a downstream end 41b, which is axially opposite to the upstream end 41a of the premixing duct 41, and is arranged at the premixing pilot nozzle Near the downstream end 40b of 40. For example, as shown schematically in FIGS. 4 and 9 , each downstream end 41 b of each premixing duct 41 is provided with an outlet hole 66 b that allows fluid, i.e., fuel-air mixture 62 b, to flow from the hollow The premix line 41 exits. For example, as shown schematically in Fig. 4 and Fig. 9, each downstream end 41b of each premixing pipe 41 is provided with a central axis 41c, and the walls delimiting each premixing pipe 41 are concentrically formed around this central axis 41c. set up. In addition, for example, the embodiment of the premixing pilot nozzle 40 shown schematically in FIGS. Instead, the fluid flow is the mixture of fuel and air discharged from the outlet hole 66b of each premixing duct 41 .

Although the fuel-air mixture 62b tends to diffuse radially from each central axis 41c as the fuel-air mixture 62b exits the outlet aperture 66b of each premixing conduit 41, applicants have shown that radial diffusion is not significant. In fact, the applicant's research has shown that, in terms of the equivalence ratio of each part in the combustion outlet plane 44 (shown in FIGS. 4 and 9 ), the part immediately downstream of the outlet hole 66b of each premixing duct 41 can be approximately twice the portion of the central body 52 immediately downstream of the central axis 36 . The high equivalence ratio at a location immediately downstream of the outlet orifice 66b of each premixing duct 41 allows for continuous and efficient ignition of the fuel/air mixture through the axially extending lumen 50c (shown in FIG. 3 ) and even when the flame is at a lean blowout (LBO ) conditions can also maintain a stable flame. This is an important role of the premix pilot burner, and the premix pilot burner 60 accomplishes this role without increasing NOx.

Embodiments of the present invention include features to counteract the higher equivalence ratio that exists immediately adjacent the exit of each premixing duct 41 in the combustion exit plane 44 (shown in FIGS. 4 and 9 ). The portion downstream of the hole 66b. For example, as shown schematically in the embodiment of the premixing pilot nozzle 40 described in FIGS. 70. For example, as in the embodiments described in FIGS. 3 , 4 , 5 and 9 , the inner wall 43 of the annular channel 70 also serves to define the outer wall 43 of the premixing duct 41 . For example, as in the embodiment illustrated in FIGS. 3 , 4 , 5 and 9 , the central body wall 52 a also serves to define the outer wall 52 a of the annular channel 70 .

For example, as shown schematically in the embodiment of the premixing pilot nozzle 40 described in FIGS. 3, 4 and 9, the upstream end of the annular passage 70 is configured to The internal passage 53 accommodates the air flow. At the downstream end of the annular passage 70, a plurality of air jets 42 are formed. At least one air jet 42 is arranged near at least one outlet opening 66b of at least one premixing duct 41 . Ideally, for example, as shown in FIGS. 4 , 5 and 9 , at least one air jet 42 is provided near each outlet hole 66 b of each premixing duct 41 .

For example, as shown schematically in FIG. 9 , each passage provided with an air jet 42 is formed concentrically around a central axis 42 a disposed parallel to the center of the downstream end 41 b of the adjacent premixing duct 41 . Shaft 41c. In this way, the higher velocity air exiting each air jet 42 entrains some of the fuel/air mixture exiting the premixing duct 41 and serves to condition some portion of the fuel/air mixture present in the combustion outlet plane 44 (shown in FIG. 9 ). Guided, this part is immediately downstream of the outlet hole 66b of each premixing duct 41. The overall result is a more uniform equivalence ratio at the combustion exit plane 44 (shown in FIG. 9 ) of the fuel air nozzle 12, and this can also be used as an igniter by the ignition source.

For example, as shown schematically in FIG. 4 , each passage provided with an air jet 42 is formed concentrically around a central axis 42 a disposed about the central axis of the downstream end 41 b of the adjacent premixing duct 41 41c is at an acute angle. The magnitude of this acute angle is expected to range from 0.1 degrees to 20 degrees. Furthermore, the air jets 42 in the FIG. 4 embodiment are contemplated to be configured and arranged such that each air jet 42 directs the air flow exiting the air jet 42 in a direction away from a nearby one of the outlet holes 66b in the premix duct 41 . Thus, for example, in the embodiment shown schematically in FIG. 4 , each air jet 42 is directed such that air exiting that air jet 42 moves in a direction downstream of the central axis 36 of the central body 52 and radially away from Central axis 36 of central body 52 , and central axis 41 c radially remote from downstream end 41 b of each adjacent premixing duct 41 . In this way, the air exiting each air jet 42 entrains some of the fuel/air mixture exiting the premix duct 41 and serves to direct some portion of the fuel/air mixture present in the combustion outlet plane 44 (shown in FIG. 4 ), This portion is immediately downstream of the outlet aperture 66b of each premixing duct 41 radially outwards towards the peripheral wall 50 (shown in FIG. 3 ). The overall result is a more uniform equivalence ratio at the combustion exit plane 44 (shown in FIG. 4 ) of the fuel air nozzle 12, and this can also be used as an igniter by the ignition source.

For example, in another embodiment of the present invention schematically depicted in FIG. 6, except for the embodiment of the premixing pilot nozzle 40 schematically depicted in FIG. 6, the embodiment of FIG. The embodiment of Fig. 9 is similar. As schematically shown in FIG. 6 , each premixing duct 41 is itself arranged concentrically around a central longitudinal axis 41 c arranged at an acute angle with respect to the central axis 36 of the central body 52 . The magnitude of this acute angle is expected to range from 0.1 degrees to 20 degrees. Thus, in the premixing pilot nozzle 40 schematically depicted in FIG. 6 , each premixing duct 41 is configured and arranged to direct the fuel/air mixture exiting the outlet aperture 66b of each premixing duct 41 away from the center. The central axis 36 of the body 52 is directed radially outward to create a more uniform fuel/air mixture in the combustion exit plane 44 of the fuel air nozzle 12 before entering the combustion chamber of the gas turbine 10 for continuous and efficient ignition through Axially extending lumen 50c (shown in FIG. 3 ) of fuel air nozzle 12 supplies the fuel/air mixture. For example, although not specifically shown in FIG. 6 , the axial length of one or more of the premixing conduits 41 may extend concentrically around the central axis 41c of the downstream end 41b of the premixing conduit 41, Beyond the downstream end 40b of the premixing pilot nozzle 40 .

For example, in another embodiment of the present invention schematically described in FIG. 8, except for the embodiment of the premixing duct 41 in the premixing pilot nozzle 40 schematically described in FIG. 6, the embodiment of FIG. The embodiments of Fig. 4, Fig. 5, Fig. 6 and Fig. 9 are similar. In the embodiment schematically depicted in Figure 8, each premixing duct 41 is itself arranged concentrically around a bi-directional central longitudinal axis having a first leg 41d and a second leg 41c. As shown schematically in FIG. 8 , the first leg 41 d of the bi-directional central longitudinal axis is arranged parallel to the central axis 36 of the central body 52 and extends between the upstream end 41 a and the downstream end 41 b of each premixing conduit 41 . A second leg 41 c of a bi-directional central longitudinal axis is disposed at an acute angle with respect to the central axis 36 of the central body 52 and extends through the downstream end 41 b of each premixing duct 41 . The magnitude of this acute angle is expected to range from 0.1 degrees to 20 degrees. Accordingly, the premixing duct 41 schematically depicted in FIG. A more uniform fuel/air mixture is formed in the combustion outlet plane 44 of the gas turbine 12, and then enters the combustion chamber of the gas turbine 12, thereby continuously and effectively igniting the axially extending inner cavity 50c (shown in FIG. 3 ) through the fuel air nozzle 12. supplied fuel/air mixture.

For example, in another embodiment of the present invention schematically depicted in FIG. 7 , in addition to the premixing duct 41 and annular channel 70 in the premixing pilot nozzle 40 schematically depicted in FIGS. 3 , 4 , 5 and 9 The embodiment of FIG. 7 is similar to the embodiment of FIG. 3 , FIG. 4 , FIG. 5 and FIG. 9 . As schematically shown in FIG. 7 , each premixing duct 41 is itself arranged concentrically around a central longitudinal axis 41 c arranged at an acute angle with respect to the central axis 36 of the central body 52 . The magnitude of this acute angle is expected to range from 0.1 degrees to 20 degrees. Thus, in the premix pilot nozzle 40 schematically depicted in FIG. 7 , each premix duct 41 is configured and arranged to direct the fuel/air mixture exiting the outlet aperture 66b of each premix duct 41 away from the center body. The central axis 36 of the nozzle 52 is directed radially outward to create a more uniform fuel/air mixture in the combustion exit plane 44 of the fuel air nozzle 12 before entering the combustion chamber of the gas turbine 10 to continuously and efficiently ignite the passing fuel An axially extending lumen 50c (shown in FIG. 3 ) of the air nozzle 12 supplies the fuel/air mixture.

For example, as shown schematically in the embodiment of the premixing pilot nozzle 40 described in FIG. tapers in the downstream direction. As described above with respect to the embodiments of FIGS. 3 , 4 and 5 , each air jet 42 is directed radially outward from the premixing duct 41 such that each air jet 42 can entrain some portion of the fuel/air mixture to The mixture is further directed radially outward from the premixing duct 41 to form a more uniform fuel/air mixture in the combustion exit plane 44 of the fuel air nozzle 12 before entering the combustion chamber 16 (shown in FIGS. 1 and 2 ). The fuel/air mixture supplied through the axially extending inner cavity 50c (shown in FIG. 3 ) of the fuel air nozzle 12 is continuously and effectively ignited.

Each embodiment of the premix pilot nozzle 40 has a small, well-fixed premix flame near the base of the fuel-air nozzle 12 to hold the swirling fuel-air mixture exiting the fuel-air nozzle 12 . Improved flame stability reduces fuel/air handling, extending LBO and emissions operability windows.

An advantageous method for operating a fuel/air nozzle 12 of a gas turbine engine 10 may be implemented using a fuel/air nozzle 12 such as the embodiments described above. One embodiment of the method for operating a fuel/air nozzle 12 of a gas turbine engine 10 is contemplated to include the following steps schematically shown in FIG. ) is delivered through the swozzle to swirl the primary air flow; step 82 is to deliver the primary fuel flow 57a (eg, shown in FIG. primary air flow 51a mixing; step 83, the delivery of pilot fuel flow 62 (eg, shown in FIG. 4 ) through the hollow fuel supply tube 54 to the premixing pilot nozzle 40; , shown in FIG. 4 ) is delivered downstream through the central body 52 (shown in FIG. 3 ) to the premixing pilot nozzle 40; (shown) mixes pilot fuel 62 with secondary air flow 53a, and the premix conduit 41 directs fuel/air mixture 62b (shown, for example, in FIGS. and step 86 of discharging the fuel/air mixture 62b from the premixing conduit 41 of the premixing pilot nozzle 40 that is remote from the central axis 36 of the center body 52 (eg, FIGS. 3 , 4 , and 6 to Figure 9).

Another embodiment of the method for operating a fuel/air nozzle 12 of a gas turbine engine 10 is contemplated to include the following steps schematically shown in FIG. Delivered downstream through the swozzle to swirl the primary air flow; step 82, delivering the primary fuel flow 57a (eg, shown in FIG. The primary air flow 51a mixing; step 83, the pilot fuel flow 62 (for example, shown in Figure 4) delivered through the hollow fuel supply tube 54 to the premixing pilot nozzle 40; step 84, the secondary air flow 53a ( For example, shown in FIG. 4 ) is delivered downstream through the central body 52 (shown in FIG. 3 ) to the premixing pilot nozzle 40; 4) mixes the pilot fuel 62 with the secondary air stream 53a, the mixing duct 41 directs the fuel/air mixture 62b (shown, for example, in FIGS. Evacuation; step 87, that is, some of the secondary air flow 53a (eg, shown in FIGS. 4 , 7 and 9 ) is transferred to the annular channel 70 arranged radially outward from the premixing duct 41 of the premixing pilot nozzle 40; and Step 88, ie air is expelled from the annular channel 70 away from the pre-mixing pilot nozzle 40 (eg, shown in FIGS. 4, 7 and 9). Ideally, the pressure of the air exiting the annular passage 70 exceeds the pressure of the air entering the annular passage 70 . Ideally, for example, as shown schematically in FIG. 7 , the annular channel 70 includes an upstream end configured to taper in a downstream direction. Ideally, for example, as shown schematically in FIG. 7 , a further embodiment of the method includes the step of discharging the fuel/air mixture from a premixing duct 41 of a premixing pilot nozzle 40 , said premixing duct 41 Distant from central axis 36 of central body 52 . Ideally, for example, as shown schematically in FIG. Discharge in the direction of the central axis 36. Ideally, for example, as shown schematically in FIGS. discharge in the direction.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are also within the scope of the claims if they have structural elements that do not differ from the literal meaning of the claims, or if such examples include equivalent structural elements with insubstantial differences from the literal meaning of the claims. .

Claims (36)

1. A fuel/air nozzle for a gas turbine engine, said fuel/air nozzle comprising: an axially extending peripheral wall defining the housing of the fuel/air nozzle, the peripheral wall having an outer surface and an inner surface facing away from the outer surface and defining an axially extending inner Cavity; a hollow, axially extending centerbody disposed within the lumen of the fuel/air nozzle and having a central axis, the centerbody being bounded by a centerbody wall defining an upstream end and a downstream end axially opposite the upstream end, the central body wall is defined by an outer surface and an inner surface facing away from the outer surface, the inner surface of the central body wall defines an axially extending an internal passage concentrically disposed about the central axis of the central body; an elongated hollow fuel supply tube extending axially through the interior passageway of the center body, the fuel supply tube having an upstream end disposed at the center body said upstream end and configured for connection to a fuel source, said fuel supply tube having a downstream end disposed at said downstream end of said central body; a primary air flow channel bounded by an annular space between the outer surface of the center body and the inner surface of the peripheral wall; a premixing pilot nozzle having an upstream end connected to the downstream end of the center body, the premixing pilot nozzle having a the downstream end; and The premix pilot nozzle is further provided with a plurality of axially extending hollow premix conduits each having an upstream end disposed adjacent the downstream end of the central body and bounded by the an inlet hole in fluid communication with the internal passage of the central body, each premixing tube has at least one fuel hole in fluid communication with the downstream end of the fuel supply tube, each premixing tube has having downstream ends provided with outlet orifices for fluid exiting the hollow premixing ducts, each downstream end of each premixing duct being provided with a central shaft which is connected to the central body The central axes are not parallel. 2. The fuel/air nozzle of claim 1, wherein each central axis of at least one premixing duct is disposed at an acute angle to the central axis of the central body. 3. The fuel/air nozzle of claim 1 , wherein said premix pilot nozzle further defines an annular passage disposed radially outwardly from said premix duct, said annular passage configured to align with said center body The internal passage is in fluid communication, and the annular passage is provided with a plurality of air jets, at least one of which is disposed near one of the outlet holes of at least one of the premixing ducts and has a central axis. 4. The fuel/air nozzle of claim 3, wherein said central axis of said upstream end of at least one premixing duct is configured and arranged to extend in a direction parallel to said central axis of said central body . 5. The fuel/air nozzle of claim 3, wherein said central axis of at least one of said air jets forms an acute angle with said central axis of said central body. 6. The fuel/air nozzle of claim 3, wherein the annular passage tapers in a downstream direction proceeding towards the air jet. 7. The fuel/air nozzle of claim 1, further comprising a swozzle comprising a plurality of swirl vanes extending radially across said primary air flow passage, at least one of said swozzles The vane is provided with a fuel conduit in fluid communication with the primary airflow passage, the fuel conduit having an inlet at one end thereof and an outlet at an opposite end thereof. 8. The fuel/air nozzle of claim 1 wherein said premixing pilot nozzle is provided with a pilot fuel nozzle having an upstream end and a downstream end, said upstream end of said pilot fuel nozzle in fluid communication with the downstream end of the fuel supply tube, the downstream end of the pilot fuel nozzle being provided with at least one fuel jet configured in fluid communication with the upstream end of the pilot fuel nozzle; and The premixing pilot nozzle is further provided with a fuel chamber wall disposed radially outward from the pilot fuel nozzle and bounding a fuel chamber between the pilot fuel nozzle and the fuel chamber wall, the The fuel chamber wall is further provided with a plurality of fuel holes, at least one of said fuel holes is in fluid communication with at least one of said fuel nozzles through said fuel chamber, each premixing conduit is disposed radially outwardly from said fuel chamber wall and connected to At least one of the fuel holes is in fluid communication. 9. A combustor for a gas turbine engine, the combustor comprising: head part; at least one fuel/air nozzle carried by the head portion, each fuel/air nozzle further comprising: an axially extending peripheral wall defining the housing of the fuel/air nozzle, the peripheral wall having an outer surface and an inner surface facing away from the outer surface and defining an axially extending inner Cavity; a hollow, axially extending centerbody disposed within the lumen of the fuel/air nozzle and provided with a central axis, the centerbody being bounded by a centerbody wall defining an upstream end and a downstream end axially opposite to the upstream end, the central body wall is defined by an outer surface and an inner surface facing away from the outer surface, the inner surface of the central body wall defines an axially extending an internal passage concentrically disposed about the central axis of the central body; an elongated hollow fuel supply tube extending axially through the interior passageway of the center body, the fuel supply tube having an upstream end disposed in the center body at an upstream end and configured for connection to a fuel source, the fuel supply tube has a downstream end disposed at the downstream end of the central body; a primary air flow channel bounded by an annular space between the outer surface of the center body and the inner surface of the peripheral wall; a premixing pilot nozzle having an upstream end connected to the downstream end of the center body, the premixing pilot nozzle having a the downstream end; and The premix pilot nozzle is further provided with a plurality of axially extending hollow premix conduits each having an upstream end disposed adjacent the downstream end of the central body and bounded by the an inlet hole in fluid communication with the internal passage of the central body, each premixing tube has at least one fuel hole in fluid communication with the downstream end of the fuel supply tube, each premixing tube has having downstream ends provided with outlet orifices for fluid exiting the hollow premixing ducts, each downstream end of each premixing duct being provided with a central shaft which is connected to the central body The central axes are not parallel. 10. The combustor of claim 9, wherein said premixing pilot nozzle further defines an annular passage disposed radially outwardly from said premixing duct, said annular passage being configured with said centerbody The inner passage is in fluid communication, and the annular passage is provided with a plurality of air jets. 11. The combustor of claim 9, wherein at least one said air jet is disposed adjacent one said outlet opening of at least one said premixing duct and has a central axis disposed in relation to at least one said The central axis of the premixing duct adjacent to one of the outlet holes forms an acute angle. 12. The combustor of claim 9, wherein the annular passage tapers in a downstream direction proceeding toward the air jet. 13. A method for operating a fuel/air nozzle in a gas turbine engine to improve flame stability and NOx emissions, said fuel/air nozzle being defined by: a peripheral wall; disposed within said peripheral wall and having a hollow central body of a central axis; a swirl nozzle extending radially from the exterior of said upstream end of said central body towards said peripheral wall; and a premixing pilot nozzle at said downstream end of said central body , the premixing pilot nozzle includes a plurality of premixing pipes with outlet holes, the method comprising the steps of: delivering a primary air stream downstream through the swozzle to swirl the primary air stream; delivering a flow of primary fuel through said swozzle to mix with a flow of primary air swirled downstream of said swozzle; delivering a flow of pilot fuel through a hollow fuel supply tube to said premixing pilot nozzle; delivering a flow of secondary air downstream through the center body to the premixing pilot nozzle; The pilot fuel is mixed with the secondary air stream in a plurality of axially extending hollow premixing ducts, wherein each premixing duct is provided with a central shaft at its downstream end which is connected to the said central axis of a centerbody is non-parallel and discharges said fuel/air mixture from said downstream end of said premixing pilot nozzle; and The fuel/air mixture is discharged from the outlet hole of the premix conduit of the premix pilot nozzle. 14. The method of claim 13, further comprising the step of diverting said fuel/air mixture from said premix conduit of said premix pilot nozzle radially away from said center axis of said center body discharge in the direction. 15. The method of claim 13, further comprising the step of diverting some of said secondary air flow to an annular passage radially outward from said premix duct of said premix pilot nozzle set up. 16. The method of claim 15, wherein the pressure of the air exiting the annular passage exceeds the pressure of the air entering the annular passage. 17. The method of claim 15, wherein the annular channel tapers in the direction of its downstream progression. 18. The method of claim 15, further comprising the step of expelling air from the annular passage of the premix pilot nozzle in a direction away from the outlet aperture of the premix duct. 19. The method of claim 18, wherein the air expelled from the annular passage is directed away from the central axis of the central body. 20. A fuel/air nozzle for a gas turbine engine, said fuel/air nozzle comprising: an axially extending peripheral wall defining the housing of the fuel/air nozzle, the peripheral wall having an outer surface and an inner surface facing away from the outer surface and defining an axially extending inner Cavity; a hollow, axially extending centerbody disposed within the lumen of the fuel/air nozzle and provided with a central axis, the centerbody being bounded by a centerbody wall defining an upstream end and a downstream end axially opposite to the upstream end, the central body wall is defined by an outer surface and an inner surface facing away from the outer surface, the inner surface of the central body wall defines an axially extending an internal passage concentrically disposed about the central axis of the central body; an elongated hollow fuel supply tube extending axially through the interior passageway of the center body, the fuel supply tube having an upstream end disposed at the center body said upstream end and configured for connection to a fuel source, said fuel supply tube having a downstream end disposed at said downstream end of said central body; a primary air flow channel bounded by an annular space between the outer surface of the center body and the inner surface of the peripheral wall; a premixing pilot nozzle having an upstream end connected to the downstream end of the center body, the premixing pilot nozzle having a downstream end; The premix pilot nozzle is further provided with a plurality of axially extending hollow premix conduits each having an upstream end disposed adjacent the downstream end of the central body and bounded by the an inlet hole in fluid communication with the internal passage of the central body, each premixing conduit is provided with at least one fuel hole in fluid communication with the downstream end of the fuel supply pipe; each premixing conduit each having a downstream end provided with an outlet orifice for fluid exiting the hollow premixing duct, at least each upstream end of each premixing duct being provided with a central shaft configured and arranged to causing fluid flow entering the inlet aperture of each premixing conduit to be directed in a direction parallel to the central axis of the central body; and An annular passage disposed radially outward from the premixing conduit, the annular passage configured to be in fluid communication with the internal passage of the centerbody. 21. The fuel/air nozzle of claim 20, wherein said upstream end of at least one premixing duct is provided with a central axis that is aligned with said center of said downstream end of said at least one premixing duct. The axes are not parallel. 22. A fuel/air nozzle according to claim 20, wherein said annular passage is provided with a plurality of air jets at its downstream end. 23. The fuel/air nozzle of claim 22, wherein at least one of said air jets is disposed adjacent one of said outlet holes of at least one of said premixing ducts and has a The central axis of the acute angle. 24. The fuel/air nozzle of claim 23, wherein said central axis of at least one of said air jets directs air flow exiting said air jet in a direction away from said central axis of said center body . 25. The fuel/air nozzle of claim 20, wherein the annular passage is configured to taper in a downstream direction proceeding towards the air jet. 26. A combustor for a gas turbine engine, the combustor comprising: head part; at least one fuel/air nozzle carried by the head portion, each fuel/air nozzle further comprising: an axially extending peripheral wall defining the housing of the fuel/air nozzle, the peripheral wall having an outer surface and an inner surface facing away from the outer surface and defining an axially extending inner Cavity; a hollow, axially extending centerbody disposed within the lumen of the fuel/air nozzle and provided with a central axis, the centerbody being bounded by a centerbody wall defining an upstream end and a downstream end axially opposite to the upstream end, the central body wall is defined by an outer surface and an inner surface facing away from the outer surface, the inner surface of the central body wall defines an axially extending an internal passage concentrically disposed about the central axis of the central body; an elongated hollow fuel supply tube extending axially through the interior passageway of the center body, the fuel supply tube having an upstream end disposed in the center body at an upstream end and configured for connection to a fuel source, the fuel supply tube has a downstream end disposed at the downstream end of the central body; a primary air flow channel bounded by an annular space between the outer surface of the center body and the inner surface of the peripheral wall; a premixing pilot nozzle having an upstream end connected to the downstream end of the center body, the premixing pilot nozzle having a the downstream end; and The premix pilot nozzle further defines a plurality of axially extending hollow premix conduits, each premix conduit having an upstream end disposed adjacent the downstream end of the center body and bounded by the said inner passage of the central body is in fluid communication with an inlet hole, each premixing conduit is in fluid communication with said downstream end of said fuel supply pipe, each premixing conduit has a downstream end, said downstream end is provided with a fluid Outlet holes exiting from said hollow premixing ducts, each downstream end of each premixing duct being provided with a central axis configured and arranged so that the fluid flow exiting the outlet holes is directed along a direction parallel to direction guidance of said central axis of each premixing duct; and An annular passage is disposed radially outward from the premixing conduit, the annular passage being configured to be in fluid communication with the internal passage of the center body. 27. The combustion chamber of claim 26, wherein the annular passage is provided at its downstream end with a plurality of air jets. 28. The combustor of claim 27, wherein at least one of said air jets is disposed adjacent one of said outlet holes of at least one of said premixing ducts and has an acute angle with said central axis of said central body. The central axis. 29. The combustion chamber of claim 28, wherein said central axis of at least one of said air jets directs airflow exiting said air jet in a direction away from said central axis of said centerbody. 30. The combustor of claim 26, wherein the annular passage is configured to taper as it proceeds in a downstream direction toward the air jet. 31. A method for operating a fuel/air nozzle of a gas turbine engine, said fuel/air nozzle being bounded by: a peripheral wall; a hollow central body disposed within said peripheral wall and defining a central axis; swirling flow a nozzle extending outwardly from the upstream end of the central body and radially toward the peripheral wall; and a premixing pilot nozzle at the downstream end of the central body, the premixing pilot nozzle comprising A plurality of premixing pipes having outlet holes, the method comprising the steps of: delivering a primary air stream downstream through the swozzle to swirl the primary air stream; delivering a flow of primary fuel through said swozzle to mix with a flow of primary air swirled downstream of said swozzle; delivering a flow of pilot fuel through a hollow fuel supply tube to said premixing pilot nozzle; delivering a flow of secondary air downstream through the center body to the premixing pilot nozzle; mixing said pilot fuel with said secondary air stream in a plurality of axially extending hollow premixing ducts directing said fuel/air mixture from said premixing channel to said downstream of a nozzle end discharge; diverting a portion of said secondary air flow to an annular passage disposed radially outward from said premix duct of said premix pilot nozzle; and The fuel/air mixture is discharged from the outlet hole of the premix conduit of the premix pilot nozzle. 32. The method of claim 31 , further comprising the step of directing the fuel/air mixture from the premix conduit of the premix pilot nozzle in a direction parallel to the central axis of the center body discharge. 33. The method of claim 31 , further comprising the step of directing the fuel/air mixture from the premix conduit of the premix pilot nozzle radially away from the center axis of the center body. discharge in the direction. 34. The method of claim 31, wherein the pressure of the air exiting the annular passage exceeds the pressure of the air entering the annular passage. 35. The method of claim 31, wherein the annular channel tapers as it progresses in a downstream direction. 36. The method of claim 31 , further comprising the step of expelling air from said annular passage of said premix pilot nozzle in a direction away from said outlet orifice of said premix duct.

Images