US20060000216A1 - Multi-venturi tube fuel injector for gas turbine combustors - Google Patents
Multi-venturi tube fuel injector for gas turbine combustors Download PDFInfo
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- US20060000216A1 US20060000216A1 US10/879,279 US87927904A US2006000216A1 US 20060000216 A1 US20060000216 A1 US 20060000216A1 US 87927904 A US87927904 A US 87927904A US 2006000216 A1 US2006000216 A1 US 2006000216A1
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- 239000000446 fuel Substances 0.000 title claims abstract description 123
- 230000003197 catalytic effect Effects 0.000 claims abstract description 12
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 9
- 230000007704 transition Effects 0.000 claims abstract description 5
- 239000000203 mixture Substances 0.000 claims description 12
- 238000004891 communication Methods 0.000 claims description 5
- 238000003491 array Methods 0.000 claims description 3
- 239000003054 catalyst Substances 0.000 abstract description 16
- 238000009826 distribution Methods 0.000 abstract description 7
- 238000002347 injection Methods 0.000 description 7
- 239000007924 injection Substances 0.000 description 7
- 238000002485 combustion reaction Methods 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- 238000000926 separation method Methods 0.000 description 3
- 230000003068 static effect Effects 0.000 description 2
- 238000009827 uniform distribution Methods 0.000 description 2
- 238000005219 brazing Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
- F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
- F23R3/40—Continuous combustion chambers using liquid or gaseous fuel characterised by the use of catalytic means
Definitions
- the present invention relates to a fuel injector for gas turbine combustors and particularly relates to a multi-venturi fuel injector for catalytic and dry low-NOx applications.
- the main components of a combustor for a gas turbine include (1) a pre-burner which may typically constitute a diffusion style combustor that burns a small fraction of the fuel to elevate air temperature sufficiently to activate the catalyst downstream; (2) a pre-mixer which includes the main fuel injector and accomplishes fuel and air mixing; (3) a catalyst which partially converts the fuel in a flameless reaction in which no NOx is produced; and (4) a burn-out zone which includes homogeneous combustion in a post-catalyst liner of the lean fuel/air mixture flowing from the catalyst which does not generate NOx due to the relatively reduced temperature of the combustion.
- This type of combustor is capable of generating very low emissions.
- a multi-venturi tube has been used in a catalytic combustor as a main fuel injector. See, for example, U.S. Pat. Nos. 4,845,952 and 4,966,001. These arrangements are intended to provide a uniform fuel/air mixture at the catalyst inlet. It will be appreciated that tight uniformity of the fuel distribution must be maintained over the large cross-sectional area at the catalyst inlet. Fuel/air mixing is accomplished by distributing the fuel among the large number of venturis that fill up the cross-section of the combustor followed by aerodynamic mixing inside the venturi tube as well as in the downstream region between the venturi exit plane and the catalyst inlet. In addition to uniform fuel/air mixture, the catalyst requires a uniform temperature and a uniform velocity across the catalyst inlet plane.
- the catalyst does not function optimally. It will also be appreciated that multiple venturi tubes produce laminar flow which suppresses large scale mixing and preconditions the flow such that only local mixing can be accomplished between the diffuser exit and the catalyst inlet. That is, mixing in that cross-sectional region is limited. For example, if a region of flow has a high temperature or velocity in comparison to the remaining flow, the thermal or velocity mal-distribution will deleteriously appear at the catalyst inlet. Accordingly, there is a need for a fuel injector for a gas turbine combustor affording improved uniform fuel/air, temperature and velocity distributions to the catalyst inlet.
- a flow conditioner in combination in a combustor, a flow conditioner, a venturi configuration having a diffuser with multiple sides and an improved fuel circuit.
- the flow conditioner may be of the type described and illustrated in co-pending U.S. patent application Ser. No. 10/648,203 filed Aug. 27, 2003, the disclosure of which is incorporated herein by reference.
- multiple venturi tubes having a frustum-like cross-sectional configuration are provided to enhance fuel/air mixing, to afford uniform distribution of the fuel/air, velocity and temperature at the catalyst inlet, and to eliminate flame-holding issues.
- the venturi configuration eliminates recirculation regions, i.e., flow gaps between the venturis in the exit planes and downstream thereof, as well as the potential for flame-holding.
- the venturis have a three body construction to improve fuel distribution among the various venturis and also to improve mechanical durability by thermo-shielding of the brazed joints of the construction.
- the venturi fuel circuit provides a secondary plenum between the main fuel plenum surrounding the venturis defined between spaced axial forward and aft walls and fuel supply inlets to the converging inlet of the venturis.
- a combustor for a gas turbine comprising a combustor housing including a flow liner for receiving compressor discharge air; a main fuel injector downstream of the flow liner for receiving the compressor discharge air and mixing air and fuel; a catalytic section downstream of the main fuel injector for receiving a mix of air and fuel from the main fuel injector; the main fuel injector including (i) an array of venturis each including a convergent inlet, a throat and a diffuser for flowing a fuel/air mixture therethrough in a generally axial direction for exit from said diffuser, (ii) a front plate and (iii) an aft plate surrounded by an enclosure defining a fuel supply plenum between the plates; each plate having a plurality of openings for receiving the venturis; and each venturi inlet having at least one fuel supply hole for supplying fuel from the fuel supply plenum into the venturi inlet at a location axially upstream from the
- a combustor for a gas turbine comprising a combustor housing including a flow liner for receiving compressor discharge air; a main fuel injector downstream of the flow liner for receiving the compressor discharge air; a catalytic section downstream of the main fuel injector for receiving a mix of air and fuel from the main fuel injector; the main fuel injector including an array of venturis about a combustor axis, each venturi including a converging inlet, a throat and a diffuser for flowing the fuel/air mixture, each venturi including a fuel supply hole for flowing fuel into the venturi, said diffuser having multiple discrete angularly related side walls therealong, the array of venturis being arranged in circumferential side-by-side relation to one another about the axis and spaced radially from one another.
- FIG. 1 is a fragmentary perspective view with parts broken out and in cross section illustrating a portion of a catalytic combustor for use in a gas turbine incorporating a multi-venturi tube arrangement according to a preferred aspect of the present invention
- FIG. 2 is a perspective view of the multi-venturi tube arrangement
- FIG. 3 is a cross-sectional view thereof
- FIG. 4 is a cross-sectional view thereof taken generally about on line 4 - 4 in FIG. 3 ;
- FIG. 5 is an enlarged fragmentary view with parts in cross-section illustrating a venturi and the fuel plenums
- FIG. 6 is a fragmentary perspective view of a portion of the diverging tube of the venturi.
- FIG. 7 is an enlarged fragmentary end view of the diverging sections of the multi-venturi tubes as viewed in an upstream direction.
- a typical gas turbine has an array of circumferentially spaced combustors about the axis of the turbine for burning a fuel/air mixture and flowing the products of combustion through a transition piece for flow along the hot gas path of the turbine stages whereby the energetic flow is converted to mechanical energy to rotate the turbine rotor.
- the compressor for the turbine supplies part of its compressed air to each of the combustors for mixing with the fuel.
- a portion of one of the combustors for the turbine is illustrated in FIG. 1 and it will be appreciated that the remaining combustors for the turbine are similarly configured. Smaller gas turbines can be configured with only one combustor having the configuration illustrated in FIG. 1 .
- a combustor generally designated 10 , includes a preburner section 12 having an interior flow liner 14 .
- Liner 14 has a plurality of holes 16 for receiving compressor discharge air for flow in the preburner section 12 .
- Preburner section 12 also includes a preburner fuel nozzle 18 for supplying fuel to the preburner section.
- the flow of combustion products, from the preburner section has a center peaked flow distribution, i.e., both flow velocity and temperature, which does not result in the desired uniform flow to the additional fuel injectors, e.g., the venturi fuel type injectors described and illustrated in U.S. Pat. No. 4,845,952.
- the main fuel injector is designated 20 in FIG.
- a perforated plate 24 to assist in conditioning the flow of fuel/air to obtain optimum mixing and uniform distribution of the flows and temperature at the inlet to catalytic section 22 .
- the main fuel injector 20 includes a pair of axially spaced perforated plates, i.e. a front plate 30 and an aft plate 32 ( FIGS. 1, 3 and 5 ). Plates 30 and 32 are perforated and form axially aligned annular arrays of openings, e.g., openings 34 in FIG. 4 of plate 30 .
- a casing 36 defining a plenum 38 surrounds and is secured to the outer margins of the front and aft plates 30 and 32 respectively.
- a plurality of fuel inlets 40 are equally spaced about the periphery of the casing 36 for supplying fuel to the plenum 38 .
- venturis generally designated 42 and forming part of the MVT 21 .
- each pair of axially aligned openings 34 through the plates 30 and 32 receive a venturi 42 .
- Each venturi includes a converging inlet section 44 , a throat 46 and a diverging section or diffuser 48 .
- Each venturi is a three part construction; a first part including the inlet converging portion 44 , a second part comprising the throat and diffuser 46 and 48 , and a third part comprising an annular venturi member or body 50 .
- Body 50 extends between each of the axially aligned openings in the front and aft plates 30 and 32 and is secured thereto for example by brazing.
- the converging inlet section 44 of the venturi 42 includes an inlet flange 52 which is screw threaded to a projection 54 of the body 50 .
- the integral throat and diffuser 46 and 48 respectively, has an enlarged diameter 56 at its forward end which surrounds the aft end of the inlet 44 and is secured, preferably brazed, thereto.
- each venturi constitutes a main fuel plenum 60 which lies in communication with the fuel inlets 40 .
- the main fuel plenum 60 lies in communication with each inlet section 44 via an aperture 62 through the annular body 50 , a mini fuel plenum 64 formed between the body 50 and the inlet 44 and supply holes 66 formed adjacent the leading edge of the inlet section 44 .
- the fuel supply holes 66 are spaced circumferentially one from the other about the inlet 44 and preferably are four in number. It will be appreciated that the fuel inlet holes 66 to the venturi are located upstream of the throat 46 and in the converging section of the inlet section 44 . Significantly improved mixing of the fuel/air is achieved by locating the fuel injection holes 66 in the converging inlet section of the venturi without flow separation or deleterious flame holding events.
- Fuel from the fuel inlet plenum 38 circulates between the front and aft plates 30 and 32 and about the annular bodies 50 for flow into the venturis 42 via the fuel apertures 62 , the mini plenums 64 between the inlet sections 44 and annular bodies 50 and the fuel inlet holes 66 .
- the fuel inlet holes located adjacent the inlets to the converging sections of the venturis, the fuel is injected in a region where the air side pressure is higher, e.g., compared to static pressure at the throat.
- the magnitude of the fuel/air mixing taking place in each venturi is directly related to the jet penetration which in turn depends on the pressure ratio across the fuel injection holes 66 and the jet momentum ratio, i.e., between the jets and the main flow stream.
- the fuel holes are located upstream of the throat. The fuel is therefore injected in a region where the air-side pressure is higher compared to the static pressure at the throat and therefore, for the same fuel side effective area, the pressure ratio is increased. An optimum pressure ratio-circumferential coverage is achieved. Air velocity is also lower than at the throat and therefore the jets of fuel adjacent the venturi inlet sections 44 develop under better conditions from a momentum ratio standpoint.
- venturis 42 are fixed between the two plates 30 and 32 to form the main fuel plenum 60 between the plates and the outside surfaces of the venturis. Fuel is introduced into plenum 60 from the outside diameter. A general flow of fuel with some axial symmetry occurs from the outside diameter of the plenum toward the center of the MVT as the venturis are fed with fuel.
- each diffuser 48 transitions from a circular shape at the throat 46 to a generally frustum shape at the exit. That is, the diffuser 48 transitions from a circular shape at the throat into multiple discrete angularly related sides 70 ( FIG. 7 ). Sides 70 terminate in circumferentially spaced radially extending side walls 72 as well as radially spaced circumferentially extending arcuate side walls 74 opposite one another. As illustrated, the diffusers 48 are arranged in circular patterns to achieve an axisymmetric geometry by transitioning from circular throat areas to generally frustum areas at their exits. Any gaps between the adjacent venturis both in a radial and circumferential directions are substantially eliminated as can be seen in FIGS.
- each diffuser at each venturi exit lie in contact with and are secured to the corresponding wall 72 of the circumferentially adjacent diffusers.
- the arcuate walls 74 of each diffuser exit lie in contact with adjacent walls 74 of the next radially adjacent diffuser exit.
- the venturis are arranged in a pattern of circular arrays at different radii about the axis. Thus, gaps between the radially and circumferentially adjacent diffuser exit walls are minimized or eliminated at the exit plane.
- the exit plane of the venturi diffusers had large gaps between the circular exits.
- venturi exits are stepped towards the outside diameter and in an upstream direction. That is, the venturi exits are spaced axially increasing distances from a plane normal to the flow through the combustor in a radial outward upstream direction. This enables any gap between adjacent venturis to be further reduced. Also, by making the radial outer venturis shorter, the angle of the exit diffuser is reduced, e.g. to about 7.8° thereby reducing the potential for flow separation in the exit diffuser.
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Abstract
Description
- The present invention relates to a fuel injector for gas turbine combustors and particularly relates to a multi-venturi fuel injector for catalytic and dry low-NOx applications.
- The main components of a combustor for a gas turbine, for example, a catalytic combustor, include (1) a pre-burner which may typically constitute a diffusion style combustor that burns a small fraction of the fuel to elevate air temperature sufficiently to activate the catalyst downstream; (2) a pre-mixer which includes the main fuel injector and accomplishes fuel and air mixing; (3) a catalyst which partially converts the fuel in a flameless reaction in which no NOx is produced; and (4) a burn-out zone which includes homogeneous combustion in a post-catalyst liner of the lean fuel/air mixture flowing from the catalyst which does not generate NOx due to the relatively reduced temperature of the combustion. This type of combustor is capable of generating very low emissions.
- A multi-venturi tube has been used in a catalytic combustor as a main fuel injector. See, for example, U.S. Pat. Nos. 4,845,952 and 4,966,001. These arrangements are intended to provide a uniform fuel/air mixture at the catalyst inlet. It will be appreciated that tight uniformity of the fuel distribution must be maintained over the large cross-sectional area at the catalyst inlet. Fuel/air mixing is accomplished by distributing the fuel among the large number of venturis that fill up the cross-section of the combustor followed by aerodynamic mixing inside the venturi tube as well as in the downstream region between the venturi exit plane and the catalyst inlet. In addition to uniform fuel/air mixture, the catalyst requires a uniform temperature and a uniform velocity across the catalyst inlet plane. Absent either one of these factors, the catalyst does not function optimally. It will also be appreciated that multiple venturi tubes produce laminar flow which suppresses large scale mixing and preconditions the flow such that only local mixing can be accomplished between the diffuser exit and the catalyst inlet. That is, mixing in that cross-sectional region is limited. For example, if a region of flow has a high temperature or velocity in comparison to the remaining flow, the thermal or velocity mal-distribution will deleteriously appear at the catalyst inlet. Accordingly, there is a need for a fuel injector for a gas turbine combustor affording improved uniform fuel/air, temperature and velocity distributions to the catalyst inlet.
- In accordance with the preferred aspect of the present invention, there is provided in combination in a combustor, a flow conditioner, a venturi configuration having a diffuser with multiple sides and an improved fuel circuit. The flow conditioner may be of the type described and illustrated in co-pending U.S. patent application Ser. No. 10/648,203 filed Aug. 27, 2003, the disclosure of which is incorporated herein by reference. In addition to the flow conditioner, multiple venturi tubes having a frustum-like cross-sectional configuration are provided to enhance fuel/air mixing, to afford uniform distribution of the fuel/air, velocity and temperature at the catalyst inlet, and to eliminate flame-holding issues. The venturi configuration eliminates recirculation regions, i.e., flow gaps between the venturis in the exit planes and downstream thereof, as well as the potential for flame-holding. The venturis have a three body construction to improve fuel distribution among the various venturis and also to improve mechanical durability by thermo-shielding of the brazed joints of the construction. The venturi fuel circuit provides a secondary plenum between the main fuel plenum surrounding the venturis defined between spaced axial forward and aft walls and fuel supply inlets to the converging inlet of the venturis. By providing a secondary plenum in each venturi, the plane of fuel intake into the plenum is separated from the plane of fuel injection into the venturi by a maximum available distance. Also cold fuel flow is directed along the cold side of the fuel plenum thereby minimizing thermal stress at the front and aft plate brazed joints.
- In accordance with a preferred aspect of the present invention, there is provided a combustor for a gas turbine comprising a combustor housing including a flow liner for receiving compressor discharge air; a main fuel injector downstream of the flow liner for receiving the compressor discharge air and mixing air and fuel; a catalytic section downstream of the main fuel injector for receiving a mix of air and fuel from the main fuel injector; the main fuel injector including (i) an array of venturis each including a convergent inlet, a throat and a diffuser for flowing a fuel/air mixture therethrough in a generally axial direction for exit from said diffuser, (ii) a front plate and (iii) an aft plate surrounded by an enclosure defining a fuel supply plenum between the plates; each plate having a plurality of openings for receiving the venturis; and each venturi inlet having at least one fuel supply hole for supplying fuel from the fuel supply plenum into the venturi inlet at a location axially upstream from the throat.
- In accordance with another aspect of the present invention, there is provided a combustor for a gas turbine comprising a combustor housing including a flow liner for receiving compressor discharge air; a main fuel injector downstream of the flow liner for receiving the compressor discharge air; a catalytic section downstream of the main fuel injector for receiving a mix of air and fuel from the main fuel injector; the main fuel injector including an array of venturis about a combustor axis, each venturi including a converging inlet, a throat and a diffuser for flowing the fuel/air mixture, each venturi including a fuel supply hole for flowing fuel into the venturi, said diffuser having multiple discrete angularly related side walls therealong, the array of venturis being arranged in circumferential side-by-side relation to one another about the axis and spaced radially from one another.
-
FIG. 1 is a fragmentary perspective view with parts broken out and in cross section illustrating a portion of a catalytic combustor for use in a gas turbine incorporating a multi-venturi tube arrangement according to a preferred aspect of the present invention; -
FIG. 2 is a perspective view of the multi-venturi tube arrangement; -
FIG. 3 is a cross-sectional view thereof; -
FIG. 4 is a cross-sectional view thereof taken generally about on line 4-4 inFIG. 3 ; -
FIG. 5 is an enlarged fragmentary view with parts in cross-section illustrating a venturi and the fuel plenums; -
FIG. 6 is a fragmentary perspective view of a portion of the diverging tube of the venturi; and -
FIG. 7 is an enlarged fragmentary end view of the diverging sections of the multi-venturi tubes as viewed in an upstream direction. - As will be appreciated a typical gas turbine has an array of circumferentially spaced combustors about the axis of the turbine for burning a fuel/air mixture and flowing the products of combustion through a transition piece for flow along the hot gas path of the turbine stages whereby the energetic flow is converted to mechanical energy to rotate the turbine rotor. The compressor for the turbine supplies part of its compressed air to each of the combustors for mixing with the fuel. A portion of one of the combustors for the turbine is illustrated in
FIG. 1 and it will be appreciated that the remaining combustors for the turbine are similarly configured. Smaller gas turbines can be configured with only one combustor having the configuration illustrated inFIG. 1 . - Referring to
FIG. 1 a combustor, generally designated 10, includes apreburner section 12 having aninterior flow liner 14.Liner 14 has a plurality ofholes 16 for receiving compressor discharge air for flow in thepreburner section 12. Preburnersection 12 also includes apreburner fuel nozzle 18 for supplying fuel to the preburner section. The flow of combustion products, from the preburner section has a center peaked flow distribution, i.e., both flow velocity and temperature, which does not result in the desired uniform flow to the additional fuel injectors, e.g., the venturi fuel type injectors described and illustrated in U.S. Pat. No. 4,845,952. The main fuel injector is designated 20 inFIG. 1 and forms part of a multi-venturi tube arrangement of which certain aspects are in accordance with a preferred embodiment of the present invention. The air and products of combustion from thepreburner section 12 and the fuel from thefuel injector 20 flow to a catalyst orcatalytic section 22. As a consequence there is a lack of uniformity of the flow at the inlet to thecatalytic section 22. One effort to provide such uniformity, has resulted in the design of a flow controller generally designated 24 between thepreburner section 12 and thefuel injector 20. Details of theflow conditioner 24 may be found in U.S. patent application Ser. No. 10/648,203 filed Aug. 27, 2003 for Flow Controller For Gas Turbine Combustors, the subject matter of which is incorporated herein by reference. - At the inlet to the multi-venturi tube arrangement 21 (hereinafter MVT) forming part of the
main fuel injector 20, there is provided aperforated plate 24 to assist in conditioning the flow of fuel/air to obtain optimum mixing and uniform distribution of the flows and temperature at the inlet tocatalytic section 22. - The
main fuel injector 20 includes a pair of axially spaced perforated plates, i.e. afront plate 30 and an aft plate 32 (FIGS. 1, 3 and 5).Plates openings 34 inFIG. 4 ofplate 30. Acasing 36 defining aplenum 38 surrounds and is secured to the outer margins of the front andaft plates FIGS. 2 and 4 , a plurality offuel inlets 40, four being shown, are equally spaced about the periphery of thecasing 36 for supplying fuel to theplenum 38. - The openings through the
plates openings 34 through theplates venturi 42. Each venturi includes a converginginlet section 44, athroat 46 and a diverging section ordiffuser 48. Each venturi is a three part construction; a first part including theinlet converging portion 44, a second part comprising the throat anddiffuser body 50.Body 50 extends between each of the axially aligned openings in the front andaft plates inlet section 44 of theventuri 42 includes aninlet flange 52 which is screw threaded to aprojection 54 of thebody 50. The integral throat anddiffuser diameter 56 at its forward end which surrounds the aft end of theinlet 44 and is secured, preferably brazed, thereto. - It will be appreciated that the space between the front and
aft plates annular bodies 50 of each venturi constitutes amain fuel plenum 60 which lies in communication with thefuel inlets 40. Themain fuel plenum 60 lies in communication with eachinlet section 44 via anaperture 62 through theannular body 50, amini fuel plenum 64 formed between thebody 50 and theinlet 44 andsupply holes 66 formed adjacent the leading edge of theinlet section 44. The fuel supply holes 66 are spaced circumferentially one from the other about theinlet 44 and preferably are four in number. It will be appreciated that the fuel inlet holes 66 to the venturi are located upstream of thethroat 46 and in the converging section of theinlet section 44. Significantly improved mixing of the fuel/air is achieved by locating the fuel injection holes 66 in the converging inlet section of the venturi without flow separation or deleterious flame holding events. - Fuel from the
fuel inlet plenum 38 circulates between the front andaft plates annular bodies 50 for flow into theventuris 42 via thefuel apertures 62, themini plenums 64 between theinlet sections 44 andannular bodies 50 and the fuel inlet holes 66. With the fuel inlet holes located adjacent the inlets to the converging sections of the venturis, the fuel is injected in a region where the air side pressure is higher, e.g., compared to static pressure at the throat. It will be appreciated that the magnitude of the fuel/air mixing taking place in each venturi is directly related to the jet penetration which in turn depends on the pressure ratio across the fuel injection holes 66 and the jet momentum ratio, i.e., between the jets and the main flow stream. To increase the pressure ratio and decouple the fuel injection from airflow distribution, the fuel holes are located upstream of the throat. The fuel is therefore injected in a region where the air-side pressure is higher compared to the static pressure at the throat and therefore, for the same fuel side effective area, the pressure ratio is increased. An optimum pressure ratio-circumferential coverage is achieved. Air velocity is also lower than at the throat and therefore the jets of fuel adjacent theventuri inlet sections 44 develop under better conditions from a momentum ratio standpoint. Further, improved air fuel mixing due to this fuel inlet location is achieved also by the increased mixing length, i.e., the actual travel distance inside the venturi for the same overall length of tube. Additionally, theventuris 42 are fixed between the twoplates main fuel plenum 60 between the plates and the outside surfaces of the venturis. Fuel is introduced intoplenum 60 from the outside diameter. A general flow of fuel with some axial symmetry occurs from the outside diameter of the plenum toward the center of the MVT as the venturis are fed with fuel. Thus, a potential imbalance in fuel flow around the tubes and among the tubes with a penalty in mixing performance which occurs with fuel injection at the venturi throats is avoided since the fuel injection holes into the venturis are spatially displaced from a plane in which the general plenum flow occurs. Finally, because the fuel inlet injection holes 66 are located adjacent theventuri inlet section 44, the potential for fuel jet induced flow separation inside the venturis is greatly reduced. - Referring now to
FIGS. 2, 6 and 7, eachdiffuser 48 transitions from a circular shape at thethroat 46 to a generally frustum shape at the exit. That is, thediffuser 48 transitions from a circular shape at the throat into multiple discrete angularly related sides 70 (FIG. 7 ).Sides 70 terminate in circumferentially spaced radially extendingside walls 72 as well as radially spaced circumferentially extendingarcuate side walls 74 opposite one another. As illustrated, thediffusers 48 are arranged in circular patterns to achieve an axisymmetric geometry by transitioning from circular throat areas to generally frustum areas at their exits. Any gaps between the adjacent venturis both in a radial and circumferential directions are substantially eliminated as can be seen inFIGS. 2 and 7 . Thus, as illustrated inFIG. 7 , theradial extending walls 72 of each diffuser at each venturi exit lie in contact with and are secured to thecorresponding wall 72 of the circumferentially adjacent diffusers. Similarly, thearcuate walls 74 of each diffuser exit lie in contact withadjacent walls 74 of the next radially adjacent diffuser exit. Also, the venturis are arranged in a pattern of circular arrays at different radii about the axis. Thus, gaps between the radially and circumferentially adjacent diffuser exit walls are minimized or eliminated at the exit plane. Previously, for example, as illustrated in U.S. Pat. No. 4,845,952, the exit plane of the venturi diffusers had large gaps between the circular exits. Those interventuri gaps produced large recirculation regions downstream of the exit plane which are filled in by the exit flow from the circular venturis. By transitioning from the circular cross-section at the throat of the venturis to generally frustums at the exit plane of the venturis with minimized or eliminated gaps between circumferentially and radially adjacent venturi exits, these prior large recirculation regions formed downstream of the venturi exits and the risk for flame holding are greatly reduced or eliminated. It will also be appreciated that by providing each venturi in a multi part construction, i.e., aninlet 44 and a combined throat anddiffuser section inlet 44 can be removed for tuning, refurbishing or testing flexibility purposes. - Further, from a review of
FIG. 3 , the venturi exits are stepped towards the outside diameter and in an upstream direction. That is, the venturi exits are spaced axially increasing distances from a plane normal to the flow through the combustor in a radial outward upstream direction. This enables any gap between adjacent venturis to be further reduced. Also, by making the radial outer venturis shorter, the angle of the exit diffuser is reduced, e.g. to about 7.8° thereby reducing the potential for flow separation in the exit diffuser. - While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (22)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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US10/879,279 US6983600B1 (en) | 2004-06-30 | 2004-06-30 | Multi-venturi tube fuel injector for gas turbine combustors |
JP2005189089A JP4744953B2 (en) | 2004-06-30 | 2005-06-29 | Multi-venturi tube fuel injector for gas turbine combustor |
CNB2005100809905A CN100529548C (en) | 2004-06-30 | 2005-06-30 | Multi-venturi tube fuel injector for gas turbine combustors |
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US10/879,279 US6983600B1 (en) | 2004-06-30 | 2004-06-30 | Multi-venturi tube fuel injector for gas turbine combustors |
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US20060000216A1 true US20060000216A1 (en) | 2006-01-05 |
US6983600B1 US6983600B1 (en) | 2006-01-10 |
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US10/879,279 Expired - Fee Related US6983600B1 (en) | 2004-06-30 | 2004-06-30 | Multi-venturi tube fuel injector for gas turbine combustors |
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Cited By (13)
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US20090317760A1 (en) * | 2008-06-20 | 2009-12-24 | Anthony Michael Gadbois | Multi-lumen aspirator device |
WO2011031278A1 (en) * | 2009-09-13 | 2011-03-17 | Lean Flame, Inc. | Inlet premixer for combustion apparatus |
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Also Published As
Publication number | Publication date |
---|---|
CN1715758A (en) | 2006-01-04 |
JP2006029773A (en) | 2006-02-02 |
CN100529548C (en) | 2009-08-19 |
JP4744953B2 (en) | 2011-08-10 |
US6983600B1 (en) | 2006-01-10 |
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