WO2020048880A1 - Gas turbine burner with pilot fuel-air mixing - Google Patents

Gas turbine burner with pilot fuel-air mixing Download PDF

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Publication number
WO2020048880A1
WO2020048880A1 PCT/EP2019/073185 EP2019073185W WO2020048880A1 WO 2020048880 A1 WO2020048880 A1 WO 2020048880A1 EP 2019073185 W EP2019073185 W EP 2019073185W WO 2020048880 A1 WO2020048880 A1 WO 2020048880A1
Authority
WO
WIPO (PCT)
Prior art keywords
pilot
burner
mixing
fuel
mixing cavity
Prior art date
Application number
PCT/EP2019/073185
Other languages
French (fr)
Inventor
Anton Berg
Atanu Kumar Kundu
Original Assignee
Siemens Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Priority to EP19769056.3A priority Critical patent/EP3821174B1/en
Publication of WO2020048880A1 publication Critical patent/WO2020048880A1/en

Links

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
    • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
    • F23R3/286—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply having fuel-air premixing devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
    • F23D11/10—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour
    • F23D11/101—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour medium and fuel meeting before the burner outlet
    • F23D11/102—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour medium and fuel meeting before the burner outlet in an internal mixing chamber
    • F23D11/103—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space the spraying being induced by a gaseous medium, e.g. water vapour medium and fuel meeting before the burner outlet in an internal mixing chamber with means creating a swirl inside the mixing chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
    • F23D11/36—Details, e.g. burner cooling means, noise reduction means
    • F23D11/40—Mixing tubes or chambers; Burner heads
    • F23D11/402—Mixing chambers downstream of the nozzle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/02—Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone
    • 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
    • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
    • F23R3/34—Feeding into different combustion zones
    • F23R3/343—Pilot flames, i.e. fuel nozzles or injectors using only a very small proportion of the total fuel to insure continuous combustion
    • 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
    • F23R3/42—Continuous combustion chambers using liquid or gaseous fuel characterised by the arrangement or form of the flame tubes or combustion chambers
    • F23R3/50—Combustion chambers comprising an annular flame tube within an annular casing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/07002—Premix burners with air inlet slots obtained between offset curved wall surfaces, e.g. double cone burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2203/00—Gaseous fuel burners
    • F23D2203/007—Mixing tubes, air supply regulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2900/00—Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
    • F23D2900/14—Special features of gas burners
    • F23D2900/14701—Swirling means inside the mixing tube or chamber to improve premixing
    • 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
    • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
    • F23R2900/03343—Pilot burners operating in premixed mode

Definitions

  • the invention relates to a burner according to the features of the preamble of claim 1.
  • Such burners are preferably used for firing the combustion chamber of a gas turbine.
  • Such burners are known from EP 1 389 713 B1 and comprise a swirl generator and a downstream mixing tube.
  • the burner head is provided with a pilot burner system to support the main flame.
  • the pilot burner system comprises a mixing cavity for mixing pilot fuel and assist air.
  • the mixing cavity of the known burner is of a pure cir cumferential shape. Since such a design bears the risk for the pilot flame to burn inside the mixing cavity
  • EP 2 268 975 B1 proposes a solution with swirler wings being arranged in the vicinity of the pilot fuel/air mix outlet nozzles.
  • the mixing of fuel and air is mainly due to the tangential interaction of fuel and air streams. But still the pilot fuel-air mixing is limited, and fuel rich pockets are di rected towards the combustion chamber. Therefore, the pilot flame is an external air assisted diffusion like flame that has inherent flame stability but can also create high NO x emission due to this diffusion mode combustion.
  • the object of the present invention is to improve a burner of the above type in such a way that NO x emission is reduced.
  • the present invention solves the above problem by providing a burner with a burner head comprising a main mixing tube for premixing combustion air and fuel, wherein the main mixing tube is provided with a pilot burner system in its downstream part, wherein the pilot burner system comprises an annular mixing cavity with an entrance for air in its upstream end, with an entrance for pilot fuel and with an outlet nozzle in its downstream end, wherein a pilot mixing tube extends in side the mixing cavity between the air entrance and the out let nozzle with a pilot mixing tube length exceeding a dis tance between the upstream and the downstream ends of the mixing cavity.
  • the non-premixed behavior of the pilot flame is one of the major sources of NO x .
  • the extended mixing path inside the mixing cavity of the inventive burner improves fuel and air mixing and reduces the formation of NO x . Further premixing of the pilot stage is possible when the pilot flame has an addi tional flame stabilization point.
  • the present invention is intended to increase the pilot fuel mixing and inherently to reduce the NO x without affecting the flame stability.
  • the mix ing cavity comprises a conical front surface facing away from the burner axis and the outlet nozzle is arranged in that conical front surface with an injection angle perpendicular to the front surface.
  • pilot fuel entrance of the mixing cavity is in its downstream part and a pilot fuel entrance of the pilot mixing tube is in its upstream part.
  • a cooling channel is ar- ranged in at least a part of a radially outer wall and the downstream end of the mixing cavity.
  • Yet another preferred embodiment of the present invention is characterized in that the cooling channel opens out at the conical front surface at an inner position compared to the outlet nozzle as seen in a radial direction of the burner.
  • the cooling channel begins at an upstream part of the mixing cavity .
  • pilot mixing tube is a spiral tubing arrangement.
  • the pilot mixing tube comprises secondary tubes that merge before opening out into the outlet nozzle.
  • the pilot mixing tube com prises steps.
  • pilot mixing tube is fully inte grated with the mixing cavity, especially when the pilot burner system is additively manufactured.
  • the present invention additionally relates to an annular com bustion chamber of a gas turbine, which is characterized in that at least two, preferably at least 10 burners as de scribed above are arranged within the combustion chamber.
  • the mixing of fuel and air can be improved by in troducing additively manufactured pilot fueling arrangement with additional mixing length.
  • mixing at the pilot burner stage exit can be controlled more efficient ly.
  • the overall fuel-air mixing is improved.
  • the enhanced mixing can produce lower NO x emission without affecting the combustion stability.
  • a variable mixing length is possible for different fuels. Variable location fuel injection possi bility can widen the fuel flexibility of the pilot stage com bustion .
  • Figure 1 shows a pilot fuel-air mixing arrangement in prior art design
  • Figure 2 shows a burner arrangement with pilot injection
  • Figure 3 shows a pilot flame stabilization process due to dump plane
  • Figure 4 shows a cut through of a double cone burner with mixing tube in prior art design indicating the po sition of the pilot burner system in its downstream part highlighted by the rectangular box;
  • Figure 5 shows a cut through a simplified sketch of the an nular mixing cavity according to the invention
  • Figure 6 shows a cut through an alternative embodiment of the annular mixing cavity with more safety features or film air to protect the metal
  • Figure 7 shows a spiral tubing arrangement possible inside the mixing cavity
  • Figure shows a multiple pilot tube arrangement
  • Figure 9 shows a pilot fuel arrangement where secondary
  • Figure 1 shows a pilot fuel-air mixing arrangement in prior art design according to EP 2 268 975 B1.
  • Pilot fuel 19 is provided through a gas channel 16.
  • the gas channel 16 emerges into a mixing cavity 17.
  • Assist air 20 for burning the pilot fuel 19 is led into the mixing cavity 17 through air channels (not shown) and is deflected by swirler vanes 18.
  • fuel and air mixing is mainly due to a tangential inter action of fuel and air streams. Due to a relatively short mixing length, the mixing is limited, and a center rich pilot jet is directed toward the combustion chamber.
  • Figure 2 shows a burner arrangement in an annular combustion chamber 15 with pilot injection holes 21 arranged in a coni cal front surface 9 of a downstream part of the respective burner 1.
  • Figure 3 shows a pilot flame stabilization process due to dump plane in a double cone burner 1.
  • Fuel and air enter the main mixing tube 2 through tangential slots 22 of a swirler prior entering the combustion chamber 15. Due to the broaden ing a main recirculation zone 23 of the main flame 26 forms with a forward stagnation point 24 at the entry level of the combustion chamber 15.
  • Pilot fuel 19 and air are added to the combustion chamber 15 radially outwardly with respect to the main air and fuel, the pilot fuel 19 and air forming external recirculation zones 25 with opposite direction of rotation compared to the main recirculation zone 23.
  • Figure 4 shows a cut through of a prior art double cone burn er 1 with a burner head comprising a main mixing tube 2 for premixing combustion air and fuel, wherein the main mixing tube 2 is provided with a pilot burner system 3 in its down stream part.
  • the pilot burner system 3 is highlighted by a rectangular box and shows the prior art design that has al ready been presented in Figure 1.
  • the relatively small partially premixed pilot arrangement of the prior art can be replaced with a cavity filled with fuel and tube arrangements according to the invention.
  • pilot burner system 3 comprising an annular mixing cavity 4 with an entrance 5 for air in its upstream end, with an entrance 6 for pilot fuel and with an outlet nozzle 7 in its downstream end.
  • a pilot mixing tube 8 extends inside the mixing cavity 4 between the air entrance 5 and the outlet nozzle 7.
  • the pilot mixing tube 8 length exceeds a distance between the upstream and the downstream ends of the mixing cavity 4 which is achieved by a meandering pilot mix ing tube 8.
  • the pilot mixing tube 8 is fully inte grated with the mixing cavity 4 and given the geometry is suitable for being additively manufactured.
  • the mixing cavity 4 comprises a conical front surface 9 fac ing away from the burner axis 10 (see figure 3) .
  • the outlet nozzle 7 is arranged in that conical front surface 9 with an injection angle perpendicular to the front surface 9.
  • pilot fuel 19 is provided through a channel 27 arranged in the wall of the main mixing tube 2 which is also the radially inner wall of the mixing cavity 4 and enters the mixing cavity 4 at its downstream part where it travels in the opposite direction and enters the pilot mixing tube 8 in its upstream part so that the pilot mixing tube 8 carries the air and the fuel.
  • the fuel supply is indi cated by lines and arrows in figure 5.
  • the fuel injection holes at the pilot fuel entrance 11 of the pilot mixing tube 8 can be of different cross section like oval/triangular or circular to get the penetration. Additionally, swirl can also be introduced in the fuel holes if required.
  • Figure 6 shows a cut through an alternative embodiment of the annular mixing cavity 4 for supplying fuel and air in the pi lot burner system 3 with more safety features or film air to protect the metal.
  • Figure 6 shows a cooling channel 12 ar ranged in at least a part of a radially outer wall 13 and the downstream end of the mixing cavity 4 for a small stream of air.
  • the cooling channel 12 opens out at the conical front surface 9 at an inner position compared to the outlet nozzle 7 as seen in a radial direction of the burner 1.
  • the cooling channel 12 begins at an upstream part of the mixing cavity 4. Further, the front surface 9 is cooled by the fuel which is then introduced inside the mixing cavity 4 for mixing.
  • Figure 7 shows the pilot mixing tube 8 realized as a spiral tubing ar rangement inside the mixing cavity 4.
  • Figure 8 shows a multiple pilot tube arrangement where the pilot mixing tubes 8 comprise steps.
  • the step type tubing can be in X-Y or X-Z plane.
  • the X-Z plane which is parallel to the burner outer surface, opens many possibilities to place the pilot mixing tube bundles.
  • Figure 9 shows a pilot fuel arrangement where secondary tubes 14 combine inside the mixing cavity 4 before opening out into the outlet nozzle 7.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Gas Burners (AREA)

Abstract

The invention relates to burner (1) with a burner head comprising a main mixing tube (2) for premixing combustion air and fuel, wherein the main mixing tube (2) is provided with a pilot burner system (3) in its downstream part, wherein the pilot burner system (3) comprises an annular mixing cavity (4) with an entrance (5) for air in its upstream end, with an entrance (6) for pilot fuel and with an outlet nozzle (7) in its downstream end, wherein a pilot mixing tube (8) extends inside the mixing cavity (4) between the air entrance (5) and the outlet nozzle (7) with a pilot mixing tube (8) length exceeding a distance between the upstream and the downstream ends of the mixing cavity (4).

Description

Description
GAS TURBINE BURNER WITH PILOT FUEL-AIR MIXING
FIELD OF THE INVENTION
The invention relates to a burner according to the features of the preamble of claim 1.
BACKGROUND OF THE INVENTION
Such burners are preferably used for firing the combustion chamber of a gas turbine. Such burners are known from EP 1 389 713 B1 and comprise a swirl generator and a downstream mixing tube. The burner head is provided with a pilot burner system to support the main flame. The pilot burner system comprises a mixing cavity for mixing pilot fuel and assist air. The mixing cavity of the known burner is of a pure cir cumferential shape. Since such a design bears the risk for the pilot flame to burn inside the mixing cavity EP 2 268 975 B1 proposes a solution with swirler wings being arranged in the vicinity of the pilot fuel/air mix outlet nozzles.
The mixing of fuel and air is mainly due to the tangential interaction of fuel and air streams. But still the pilot fuel-air mixing is limited, and fuel rich pockets are di rected towards the combustion chamber. Therefore, the pilot flame is an external air assisted diffusion like flame that has inherent flame stability but can also create high NOx emission due to this diffusion mode combustion.
Further, the combustor dump locations contribute to flame stabilization as will be shown in Figure 3.
The object of the present invention is to improve a burner of the above type in such a way that NOx emission is reduced. SUMMARY OF THE INVENTION
The present invention solves the above problem by providing a burner with a burner head comprising a main mixing tube for premixing combustion air and fuel, wherein the main mixing tube is provided with a pilot burner system in its downstream part, wherein the pilot burner system comprises an annular mixing cavity with an entrance for air in its upstream end, with an entrance for pilot fuel and with an outlet nozzle in its downstream end, wherein a pilot mixing tube extends in side the mixing cavity between the air entrance and the out let nozzle with a pilot mixing tube length exceeding a dis tance between the upstream and the downstream ends of the mixing cavity.
The non-premixed behavior of the pilot flame is one of the major sources of NOx. The extended mixing path inside the mixing cavity of the inventive burner improves fuel and air mixing and reduces the formation of NOx. Further premixing of the pilot stage is possible when the pilot flame has an addi tional flame stabilization point. The present invention is intended to increase the pilot fuel mixing and inherently to reduce the NOx without affecting the flame stability.
According to a preferred embodiment of the invention the mix ing cavity comprises a conical front surface facing away from the burner axis and the outlet nozzle is arranged in that conical front surface with an injection angle perpendicular to the front surface.
It is particularly advantageous when a pilot fuel entrance of the mixing cavity is in its downstream part and a pilot fuel entrance of the pilot mixing tube is in its upstream part.
According to a preferred embodiment, a cooling channel is ar- ranged in at least a part of a radially outer wall and the downstream end of the mixing cavity. Yet another preferred embodiment of the present invention is characterized in that the cooling channel opens out at the conical front surface at an inner position compared to the outlet nozzle as seen in a radial direction of the burner.
According to another preferred embodiment of the invention, the cooling channel begins at an upstream part of the mixing cavity .
According to a further embodiment of the invention the pilot mixing tube is a spiral tubing arrangement.
Alternatively, the pilot mixing tube comprises secondary tubes that merge before opening out into the outlet nozzle.
In another alternative embodiment, the pilot mixing tube com prises steps.
It is advantageous, when the pilot mixing tube is fully inte grated with the mixing cavity, especially when the pilot burner system is additively manufactured.
The present invention additionally relates to an annular com bustion chamber of a gas turbine, which is characterized in that at least two, preferably at least 10 burners as de scribed above are arranged within the combustion chamber.
To sum up, the mixing of fuel and air can be improved by in troducing additively manufactured pilot fueling arrangement with additional mixing length. With the invention mixing at the pilot burner stage exit can be controlled more efficient ly. The overall fuel-air mixing is improved. The enhanced mixing can produce lower NOx emission without affecting the combustion stability. A variable mixing length is possible for different fuels. Variable location fuel injection possi bility can widen the fuel flexibility of the pilot stage com bustion . BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention are now described, by way of ex ample only, with reference to the accompanying drawings, of which :
Figure 1 shows a pilot fuel-air mixing arrangement in prior art design;
Figure 2 shows a burner arrangement with pilot injection
holes ;
Figure 3 shows a pilot flame stabilization process due to dump plane;
Figure 4 shows a cut through of a double cone burner with mixing tube in prior art design indicating the po sition of the pilot burner system in its downstream part highlighted by the rectangular box;
Figure 5 shows a cut through a simplified sketch of the an nular mixing cavity according to the invention;
Figure 6 shows a cut through an alternative embodiment of the annular mixing cavity with more safety features or film air to protect the metal;
Figure 7 shows a spiral tubing arrangement possible inside the mixing cavity;
Figure shows a multiple pilot tube arrangement and
Figure 9 shows a pilot fuel arrangement where secondary
tubes combine inside the mixing cavity. The illustration in the drawings is in schematic form. It is noted that in different figures, similar or identical ele ments may be provided with the same reference signs.
DESCRIPTION OF THE DRAWINGS
Figure 1 shows a pilot fuel-air mixing arrangement in prior art design according to EP 2 268 975 B1. Pilot fuel 19 is provided through a gas channel 16. The gas channel 16 emerges into a mixing cavity 17. Assist air 20 for burning the pilot fuel 19 is led into the mixing cavity 17 through air channels (not shown) and is deflected by swirler vanes 18. As can be seen fuel and air mixing is mainly due to a tangential inter action of fuel and air streams. Due to a relatively short mixing length, the mixing is limited, and a center rich pilot jet is directed toward the combustion chamber.
Figure 2 shows a burner arrangement in an annular combustion chamber 15 with pilot injection holes 21 arranged in a coni cal front surface 9 of a downstream part of the respective burner 1.
Figure 3 shows a pilot flame stabilization process due to dump plane in a double cone burner 1. Fuel and air enter the main mixing tube 2 through tangential slots 22 of a swirler prior entering the combustion chamber 15. Due to the broaden ing a main recirculation zone 23 of the main flame 26 forms with a forward stagnation point 24 at the entry level of the combustion chamber 15. Pilot fuel 19 and air are added to the combustion chamber 15 radially outwardly with respect to the main air and fuel, the pilot fuel 19 and air forming external recirculation zones 25 with opposite direction of rotation compared to the main recirculation zone 23.
Figure 4 shows a cut through of a prior art double cone burn er 1 with a burner head comprising a main mixing tube 2 for premixing combustion air and fuel, wherein the main mixing tube 2 is provided with a pilot burner system 3 in its down stream part. The pilot burner system 3 is highlighted by a rectangular box and shows the prior art design that has al ready been presented in Figure 1.
The relatively small partially premixed pilot arrangement of the prior art can be replaced with a cavity filled with fuel and tube arrangements according to the invention.
The invention is explained in Figure 5 showing a cut through a simplified sketch of the mixing cavity 4 of the pilot burn er system 3, the pilot burner system 3 comprising an annular mixing cavity 4 with an entrance 5 for air in its upstream end, with an entrance 6 for pilot fuel and with an outlet nozzle 7 in its downstream end. A pilot mixing tube 8 extends inside the mixing cavity 4 between the air entrance 5 and the outlet nozzle 7. The pilot mixing tube 8 length exceeds a distance between the upstream and the downstream ends of the mixing cavity 4 which is achieved by a meandering pilot mix ing tube 8. Further, the pilot mixing tube 8 is fully inte grated with the mixing cavity 4 and given the geometry is suitable for being additively manufactured.
The mixing cavity 4 comprises a conical front surface 9 fac ing away from the burner axis 10 (see figure 3) . The outlet nozzle 7 is arranged in that conical front surface 9 with an injection angle perpendicular to the front surface 9.
Under operating conditions pilot fuel 19 is provided through a channel 27 arranged in the wall of the main mixing tube 2 which is also the radially inner wall of the mixing cavity 4 and enters the mixing cavity 4 at its downstream part where it travels in the opposite direction and enters the pilot mixing tube 8 in its upstream part so that the pilot mixing tube 8 carries the air and the fuel. The fuel supply is indi cated by lines and arrows in figure 5. The fuel injection holes at the pilot fuel entrance 11 of the pilot mixing tube 8 can be of different cross section like oval/triangular or circular to get the penetration. Additionally, swirl can also be introduced in the fuel holes if required.
Figure 6 shows a cut through an alternative embodiment of the annular mixing cavity 4 for supplying fuel and air in the pi lot burner system 3 with more safety features or film air to protect the metal. Figure 6 shows a cooling channel 12 ar ranged in at least a part of a radially outer wall 13 and the downstream end of the mixing cavity 4 for a small stream of air. The cooling channel 12 opens out at the conical front surface 9 at an inner position compared to the outlet nozzle 7 as seen in a radial direction of the burner 1. The cooling channel 12 begins at an upstream part of the mixing cavity 4. Further, the front surface 9 is cooled by the fuel which is then introduced inside the mixing cavity 4 for mixing.
Different tubing arrangements for increasing the fuel-air mixing are possible inside the mixing cavity 4. Figure 7 shows the pilot mixing tube 8 realized as a spiral tubing ar rangement inside the mixing cavity 4.
Figure 8 shows a multiple pilot tube arrangement where the pilot mixing tubes 8 comprise steps. The step type tubing can be in X-Y or X-Z plane. The X-Z plane, which is parallel to the burner outer surface, opens many possibilities to place the pilot mixing tube bundles.
Figure 9 shows a pilot fuel arrangement where secondary tubes 14 combine inside the mixing cavity 4 before opening out into the outlet nozzle 7.
From the examples shown in Figures 7 to 9 it becomes clear that single or multiple pilot mixing tube 8 arrangements can be incorporated based on design requirements. The location of the entrance for pilot fuel of the mixing cavity 4 can be varied to achieve a specific degree of mixing of fuel and air . Although the present invention has been described in detail with reference to the preferred embodiment, it is to be un derstood that the present invention is not limited by the disclosed examples, and that numerous additional modifica- tions and variations could be made thereto by a person skilled in the art without departing from the scope of the invention .

Claims

Patent Claims
1. A burner (1) with a burner head comprising a main mixing tube (2) for premixing combustion air and fuel, wherein the main mixing tube (2) is provided with a pilot burner system (3) in its downstream part, wherein the pilot burner system (3) comprises an annular mixing cavity (4) with an entrance (5) for air in its upstream end, with an entrance (6) for pilot fuel and with an outlet nozzle (7) in its downstream end, characterized in that a pilot mix ing tube (8) extends inside the mixing cavity (4) between the air entrance (5) and the outlet nozzle (7) with a pi lot mixing tube (8) length exceeding a distance between the upstream and the downstream ends of the mixing cavity (4) .
2. The burner (1) according to claim 1, wherein the mixing cavity (4) comprises a conical front surface (9) facing away from a burner axis (10) and wherein the outlet noz zle (7) is arranged in that conical front surface (9) with an injection angle perpendicular to the front sur face ( 9) .
3. The burner (1) according to claim 1 or claim 2, wherein a pilot fuel entrance (6) of the mixing cavity (4) is in its downstream part and a pilot fuel entrance (11) of the pilot mixing tube (8) is in its upstream part.
4. The burner (1) according to claims 1 to 3, wherein a
cooling channel (12) is arranged in at least a part of a radially outer wall (13) and the downstream end of the mixing cavity (4) .
5. The burner (1) according to claim 4, wherein the cooling channel (12) opens out at the conical front surface (9) at an inner position compared to the outlet nozzle (7) as seen in a radial direction of the burner (1) .
6. The burner (1) according to claims 4 or 5, wherein the cooling channel (12) begins at an upstream part of the mixing cavity (4) .
7. The burner (1) according to one of the preceding claims, wherein the pilot mixing tube (8) is a spiral tubing ar rangement .
8. The burner (1) according to one of claims 1 to 6, wherein the pilot mixing tube (8) comprises secondary tubes (14) that merge before opening out into the outlet nozzle (7) .
9. The burner (1) according to one of claims 1 to 6, wherein the pilot mixing tube (8) comprises steps.
10. The burner (1) according to one of the preceding claims, wherein the pilot mixing tube (8) is fully integrated with the mixing cavity (4) .
11. The burner (1) according to one of the preceding claims, wherein the pilot burner system (3) is additively manu factured .
12. Annular combustion chamber (15) of a gas turbine, charac terized in that at least two, preferably at least 10 burners (1) according to the preceding claims are ar ranged within the combustion chamber (15) .
PCT/EP2019/073185 2018-09-07 2019-08-30 Gas turbine burner with pilot fuel-air mixing WO2020048880A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19769056.3A EP3821174B1 (en) 2018-09-07 2019-08-30 Gas turbine burner with pilot fuel-air mixing

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP18193084.3 2018-09-07
EP18193084.3A EP3620718A1 (en) 2018-09-07 2018-09-07 Gas turbine burner with pilot fuel-air mixing

Publications (1)

Publication Number Publication Date
WO2020048880A1 true WO2020048880A1 (en) 2020-03-12

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ID=63528543

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2019/073185 WO2020048880A1 (en) 2018-09-07 2019-08-30 Gas turbine burner with pilot fuel-air mixing

Country Status (2)

Country Link
EP (2) EP3620718A1 (en)
WO (1) WO2020048880A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
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CN113440978A (en) * 2021-07-08 2021-09-28 山东红石环保科技有限公司 Industrial waste gas treatment device and method

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Publication number Priority date Publication date Assignee Title
EP1389713A1 (en) 2002-08-12 2004-02-18 ALSTOM (Switzerland) Ltd Premixed exit ring pilot burner
EP2268975A1 (en) 2008-04-15 2011-01-05 Siemens Aktiengesellschaft Burner
EP3290804A1 (en) * 2016-08-31 2018-03-07 Siemens Aktiengesellschaft A burner with fuel and air supply incorporated in a wall of the burner

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