Hydrogen fuel orthogonal vortex pair efficient mixing anti-backfire low-pollution combustor

Abstract

The invention provides a hydrogen fuel orthogonal vortex pair efficient mixing anti-backfire low-pollution burner. The hydrogen fuel orthogonal vortex pair efficient mixing anti-backfire low-pollution burner comprises a petal-shaped fuel nozzle, a partition plate and an air guide plate. Hydrogen fuel is sprayed out through fuel holes formed in a lobe structure of the lobe-shaped fuel nozzle and is intensively mixed with incoming flow air; the premixed gas forms vortex pairs which are the same in size and opposite in direction on the downstream of the tail edge of the lobe, secondary reinforced mixing of fuel and air is achieved along with increasing of the axial distance and the reinforcing and crushing process of the orthogonal vortex pairs, meanwhile, the axial speed of the premixed gas is kept uniform, a low-speed area does not exist, and center tempering can be prevented; and the other part of the air flows through a circular seam between the partition plate and the air guide plate, and the spatial distribution of the combustible mixture and the air is changed at an outlet of the combustor, so that the tempering phenomenon of a boundary layer is prevented. According to the invention, high-efficiency reinforced mixing is realized, emission of nitrogen oxides generated in the combustion process is reduced, thermoacoustic oscillation can be inhibited through parameter differentiation and grading of lobes, and meanwhile, a tempering phenomenon is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen fuel gas turbine combustion chambers, and in particular to a hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner. Background Art

[0002] Gas turbines use natural gas mixed with hydrogen or even pure hydrogen as fuel, which can gradually reduce carbon emissions from the power generation sector until they achieve zero carbon emissions. Compared with traditional natural gas fuel, the use of high-hydrogen fuel in gas turbine combustion chambers faces many challenges. Due to the huge technical difficulties faced in burning high-hydrogen or even pure hydrogen fuel, the volume adaptability of most gas turbines on the market is about 30%. The high flame propagation speed and low ignition delay time of hydrogen will bring the risk of flashback; the higher adiabatic flame temperature and rapid heat release at the same equivalence ratio will lead to increased nitrogen oxide emissions; at the same time, the above fuel characteristics of hydrogen make it have significantly different combustion characteristics, with a unique and compact reaction zone morphology, resulting in significant changes in the flame thermoacoustic response. Therefore, it is necessary to consider the ability to achieve rapid mixing of fuel and air in a limited time and space when designing the premixed combustion chamber, improve the mixing quality, and then improve the combustion stability and reduce nitrogen oxide emissions. At the same time, it is necessary to consider the safety of hydrogen fuel combustion to avoid the occurrence of thermoacoustic oscillation and flashback. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a hydrogen fuel orthogonal vortex pair high-efficiency mixing anti-flashback low-pollution burner, which can effectively prevent flashback, reduce nitrogen oxide emissions, and inhibit thermoacoustic oscillations under hydrogen fuel combustion conditions, especially high hydrogen content or even pure hydrogen combustion conditions, thereby achieving safe, stable and low-emission combustion of hydrogen fuel gas turbines.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A hydrogen fuel orthogonal vortex pair high-efficiency mixing anti-flashback low-pollution burner, comprising: a petal-shaped fuel nozzle, a partition plate and an air guide plate; the petal-shaped fuel nozzle comprises an upstream straight structure and a downstream lobe structure, and the interior is a fuel cavity; the partition plate comprises an inner partition plate and an outer partition plate, which are adjacent to the petal-shaped fuel nozzle and arranged coaxially with it; the air guide plate comprises an inner air guide plate and an outer air guide plate, which are adjacent to the partition plate and arranged coaxially with the petal-shaped fuel nozzle, and the air guide plate is connected to the petal-shaped fuel nozzle through the bottom surface of the burner, wherein the inner air guide plate of the first stage of the burner is connected to the central duty class;

[0006] The hydrogen-containing fuel flows through the fuel duct arranged on the bottom surface of the burner, enters the fuel cavity in the petal-shaped fuel nozzle, and is then ejected through the inner fuel hole and the outer fuel hole asymmetrically arranged in the downstream lobe structure. It is first intensively mixed with the air flowing in from the annular gap between the petal-shaped fuel nozzle and the partition plate. The premixed gas formed forms a vortex pair downstream of the trailing edge of the lobe. The enhancement and fragmentation process of the vortex pair realizes secondary intensive mixing of the fuel and air. At the same time, the axial velocity of the premixed gas remains uniform, and there is no low-speed zone to prevent center flashback. The air flowing through the narrow space between the partition plate and the air guide plate changes the spatial distribution of the combustible mixture and air at the burner outlet, which is used to prevent the occurrence of boundary layer flashback. At the same time, the lifting height of the reaction zone is controlled, and the differences in different lobe structures and the grading scheme are combined to suppress thermoacoustic oscillations.

[0007] Preferably, the grading scheme includes: setting the burner to N levels, satisfying N = 2, 3, 4, 5; the petal-shaped fuel nozzle, two circles of partition plates and two circles of air guide plates constitute one level of the burner.

[0008] Preferably, the number of lobes included in the lobe structure downstream of a circle of lobe-shaped fuel nozzles is n, satisfying 16≤n≤80.

[0009] Preferably, the inner angle α and the outer angle β of the lobe structure satisfy: 10°≤α≤30°, 10°≤β≤30°.

[0010] Preferably, the number of fuel holes in a single row in a single lobe is p, the number of fuel holes in a single row outside a single lobe is q, satisfying 4 ≤ p ≤20, 4 ≤ q ≤ 20, and the aperture size d satisfies 0.1 mm ≤ d ≤ 2.0 mm.

[0011] Preferably, the distance L2 between the center positions of the inner fuel holes and the outer fuel holes in the first row downstream and the end face of the burner satisfies 0 ≤ L2 ≤ 5L1, where L1 is the distance between the inner partition plate and the outer partition plate.

[0012] Preferably, the distance L3 between the center positions of the inner fuel holes and the outer fuel holes in the first row downstream and the end of the lobe trailing edge satisfies 0 ≤ L3 ≤ L1, where L1 is the distance between the inner partition plate and the outer partition plate.

[0013] Preferably, the inner fuel holes and the outer fuel holes each have two rows and are arranged in a staggered manner. The spacing L4 between the two rows of fuel holes should satisfy 1 / 4 L1 ≤ L4 ≤ L1, where L1 is the distance between the inner partition plate and the outer partition plate.

[0014] Preferably, the wave height L5 of a single lobe satisfies 1 / 5 L1 ≤ L5 ≤ 4 / 5L1, wherein L1 is the distance between the inner partition plate and the outer partition plate.

[0015] Preferably, the distance L6 between adjacent partition plates and air guide plates satisfies 0.5 mm ≤ L6 ≤ 3 mm; and the distance L7 between the partition plate and the end face of the burner satisfies 0 ≤ L7 ≤ 10 mm.

[0016] The present invention can achieve enhanced mixing by arranging a plurality of tiny fuel holes on the petal-shaped fuel nozzle to cross-mix with the incoming air, while the axial velocity of the premixed gas is kept uniform, and there is no low-speed zone, which can prevent center flashback. At the same time, the arrangement of the lobe structure can not only increase the contact area of ​​the inner and outer airflows under the condition of the same airflow outlet area, but also induce the formation of a large-scale vortex structure at the trailing edge of the lobe, thereby achieving secondary enhanced mixing of fuel and air and reducing nitrogen oxide emissions. The geometric dimensions of the lobe structure control the scale of the vortex. Therefore, the change in the geometric shape of the lobe structure between radial stages staggers the vortex shedding frequency, which can effectively reduce the problem of thermoacoustic oscillations generated in the combustion chamber. By arranging a partition plate between the air guide plate and the petal-shaped fuel nozzle, the spatial distribution of fuel and air at the burner outlet is changed, so that there is no combustible material in the boundary layer near the burner outlet, which can suppress boundary layer flashback.

[0017] It can be seen from the above technical solution that the present invention has the following beneficial effects:

[0018] (1) Compared with the traditional premixed burner, the burner fuel nozzle of the present invention has a lobe structure, which can make the mixed gas form a vortex pair of the same size and opposite direction downstream of the lobe trailing edge. The enhancement and fragmentation process of the vortex pair realizes the secondary enhanced mixing of fuel and air, thereby reducing NO x emission;

[0019] (2) Compared with the traditional premixed burner, the burner of the present invention staggers the vortex shedding frequency by changing the geometric dimensions of the radial lobe structure between stages. At the same time, the different axial arrangements of the fuel holes change the hysteresis time, which can suppress the phenomenon of thermoacoustic oscillation in the combustion chamber.

[0020] (3) Compared with the traditional premixed burner, the burner of the present invention can avoid the occurrence of central flashback by arranging multiple tiny fuel holes on the petal-shaped fuel nozzle to cross-mix the incoming air. At the same time, a partition plate is arranged between the fuel nozzle and the air guide plate, which can change the spatial distribution of fuel and air at the burner outlet, thereby avoiding boundary layer flashback and raising the reaction zone to improve the safety of the fuel nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A cross-sectional view of a hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to an embodiment of the present invention;

[0022] Figure 2 for Figure 1 AA plane cross-sectional view of the lobe structure of the burner shown;

[0023] Figure 3 It is a schematic diagram of a petal-shaped vortex pair mixing and anti-flashback burner according to an embodiment of the present invention.

[0024] Wherein, the accompanying drawings are marked as follows:

[0025] 1-flap fuel nozzle; 2a-internal partition plate;

[0026] 2b-external partition plate; 3a-internal air guide plate;

[0027] 3b-external air guide plate; 4-burner bottom surface;

[0028] 5-lobe structure; 6-straight structure;

[0029] 7-lobe trailing edge; 8a-inner fuel hole;

[0030] 8b-external fuel hole; 9-fuel cavity;

[0031] 10-hydrogen-containing fuel; 11-fuel conduit;

[0032] 12-Center duty class.

[0033] α-the inner angle of the lobe structure; β-the outer angle of the lobe structure; L1-the distance between the inner partition plate and the outer partition plate; L2-the distance between the center position of the first row of inner fuel holes and outer fuel holes in the downstream and the end face of the burner; L3-the distance between the center position of the first row of inner fuel holes and outer fuel holes in the downstream and the end of the lobe trailing edge; L4-the distance between the two rows of inner fuel holes and outer fuel holes; L5-the wave height of a single lobe; L6-the distance between adjacent partition plates and air guide plates; L7-the distance between the partition plate and the end face of the burner. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] like Figure 1-Figure 2As shown, an embodiment of the present invention provides a hydrogen fuel orthogonal vortex pair efficient mixing anti-flashback low-pollution burner, comprising: a flap-shaped fuel nozzle 1, a partition plate and an air guide plate; the flap-shaped fuel nozzle 1 comprises an upstream straight structure 6 and a downstream lobe structure 5, and the interior is a fuel chamber 9; the partition plate comprises an inner partition plate 2a and an outer partition plate 2b, both of which are annular, adjacent to the flap-shaped fuel nozzle 1 and arranged coaxially therewith; the air guide plate comprises an inner air guide plate 3a and an outer air guide plate 3b, both of which are annular, adjacent to the partition plate, and arranged coaxially with the flap-shaped fuel nozzle 1, and the air guide plate is connected to the flap-shaped fuel nozzle 1 through the bottom surface 4 of the burner, as shown in FIG. Figure 3 As shown, the inner air guide plate 3a of the first stage of the burner is connected to the central duty class 12, as shown in FIG. Figure 1 shown.

[0036] Among them, the hydrogen-containing fuel 10 flows through the fuel duct 11 arranged on the bottom surface 4 of the burner, enters the fuel chamber 9 in the petal-shaped fuel nozzle 1, and is then ejected through the inner fuel hole 8a and the outer fuel hole 8b in the asymmetrically arranged downstream lobe structure 5. It is firstly intensively mixed with the air flowing in from the annular gap between the petal-shaped fuel nozzle 1 and the partition plate. The formed premixed gas will form a vortex pair downstream of the lobe trailing edge 7. The enhancement and fragmentation process of the vortex pair realizes the secondary intensive mixing of the fuel and air.

[0037] Among them, the air flowing through the narrow space between the partition plate and the air guide plate changes the spatial distribution of the combustible mixture and air at the burner outlet, which is used to prevent the occurrence of boundary layer flashback, while controlling the lifting height of the reaction zone and suppressing thermoacoustic oscillations.

[0038] The petal-shaped fuel nozzle 1, two circles of partition plates and two circles of air guide plates constitute one stage of the burner, and the burner includes N stages in total, satisfying N = 2, 3, 4, 5. N is the number of burner stages.

[0039] In order to ensure the contact area during secondary enhanced mixing, increase the mixing efficiency, and take into account the fact that too many lobes will lead to weakened vortex strength, the number of lobes contained in the lobe structure 5 downstream of a circle of lobe-shaped fuel nozzles 1 is n, satisfying 16≤n≤80. In order to ensure the mixing efficiency and avoid excessive opening angles causing flow separation and thus causing additional pressure loss, the inner opening angle α and the outer opening angle β of the lobe structure 5 satisfy 10°≤α≤30°, 10°≤β≤30°.

[0040] In order to ensure that the fuel and air can fully contact and improve the mixing efficiency, the number of fuel holes 8a in a single lobe is p, and the number of fuel holes 8b in a single lobe is q, which satisfy 4 ≤ p ≤ 20, 4 ≤ q ≤ 20, and the aperture size d satisfies 0.1 mm ≤ d ≤ 2.0 mm. The distance L2 between the center position of the first downstream row of the inner fuel holes 8a and the outer fuel holes 8b and the end face of the burner satisfies 0 ≤ L2 ≤ 5L1, where L1 is the distance between the inner partition plate 2a and the outer partition plate 2b.

[0041] To ensure the mixing efficiency at the combustion chamber outlet, the distance L3 between the downstream first row center position of the inner fuel holes 8a and the outer fuel holes 8b and the end of the lobe trailing edge 7 satisfies 0 ≤ L3 ≤ L1, where L1 is the distance between the inner partition plate 2a and the outer partition plate 2b.

[0042] In order to suppress thermoacoustic oscillation, the inner fuel holes 8a and the outer fuel holes 8b are arranged in two rows in a staggered manner. The spacing L4 between the two rows of fuel holes should satisfy 1 / 4 L1 ≤ L4 ≤ L1, where L1 is the distance between the inner partition plate 2a and the outer partition plate 2b; the wave height L5 of the single lobe satisfies 1 / 5 L1 ≤ L5 ≤ 4 / 5L1.

[0043] In order to avoid flow separation and reduce pressure loss, the distance L6 between the adjacent partition plates and the air guide plates satisfies 0.5 mm ≤ L6 ≤ 3 mm; in order to lift the reaction zone and improve the safety and durability of the nozzle, the distance L7 between the partition plate and the burner end face satisfies 0 ≤ L7 ≤ 10 mm.

[0044] It should be noted that the experimental methods not shown or described in the drawings or the text of the specification are all known to those skilled in the art and are not described in detail. In addition, the above definitions of the various elements are not limited to the various specific structures and shapes mentioned in the embodiments, and those skilled in the art can simply change or replace them, for example:

[0045] (1) The bottom surface of the burner does not need to be manufactured in an integrated manner, but can be split into a semicircular or fan-shaped base, and the air guide plate and flap-shaped fuel nozzle of the burner are then installed on it through connecting parts, as long as they can achieve the same function;

[0046] (2) Considering that the volume of the combustion chamber is limited under specific design parameters, the trailing edge modification design can be considered, such as changing the lobe structure by means of trailing edge beveling, fan-shaped lobes, and sawtooth lobes, so as to improve the mixing performance within a limited distance, as long as the fuel-air mixing degree at the nozzle outlet can meet the requirements;

[0047] (3) In the embodiment of the present invention, the central duty nozzle is in the form of a multi-nozzle array. In addition, a swirl nozzle can also be used as a substitute as long as it can achieve similar functions;

[0048] (4) The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner referred to in the present invention can be installed in a combustion chamber as a single unit or as a burner in the combustion chamber;

[0049] (5) The first stage of the burner mentioned in the present invention may be composed of one circle of petal-shaped fuel nozzles or multiple circles of petal-shaped fuel nozzles, a partition plate and an air guide plate, as long as the expected mixing and thermoacoustic oscillation suppression effects can be achieved;

[0050] (6) The present invention may provide demonstrations of parameters including specific values, but these parameters do not need to be exactly equal to the corresponding values, but can be approximated within acceptable error tolerances or design constraints;

[0051] (7) The directional words mentioned in the implementation, such as "front" and "back", etc., are only for reference to the directions of the drawings and are not intended to limit the scope of protection of the present invention.

[0052] In summary, the lobe-shaped vortex pair mixing and anti-flashback burner provided by the present invention makes full use of the lobe structure in the fuel nozzle and the setting of the partition plate, thereby improving the safety and durability of the burner during hydrogen fuel combustion. The setting of the tiny fuel holes in the lobe-shaped fuel nozzle and the cross-mixing method with the air help to enhance the mixing efficiency while avoiding flashback. At the same time, the setting of the lobe structure in the fuel nozzle enables the mixture of air and fuel to form a vortex pair of the same size and opposite direction at the trailing edge of the lobe, thereby achieving secondary enhanced mixing of fuel and air and reducing NO X Emissions. By changing the geometric dimensions of the radial lobe structure between stages, the vortex shedding frequency is staggered, thereby suppressing the occurrence of thermoacoustic oscillation in the combustion chamber. By setting a partition between the fuel nozzle and the air guide plate, the spatial distribution of fuel and air at the burner outlet is changed, so that there is no combustible reactant in the boundary layer near the burner outlet, which can avoid boundary flashback and lift the reaction zone, thereby improving the safety and durability of the nozzle.

[0053] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. The above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the ideas and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A hydrogen fuel orthogonal vortex pair high-efficiency mixing anti-flashback low-pollution burner, characterized in that: include: A flap-shaped fuel nozzle, a partition plate and an air guide plate; the flap-shaped fuel nozzle includes an upstream straight structure and a downstream lobe structure, and the interior is a fuel cavity; the partition plate includes an inner partition plate and an outer partition plate, which are adjacent to the flap-shaped fuel nozzle and arranged coaxially with it; the air guide plate includes an inner air guide plate and an outer air guide plate, which are adjacent to the partition plate and arranged coaxially with the flap-shaped fuel nozzle, and the air guide plate is connected to the flap-shaped fuel nozzle through the bottom surface of the burner, wherein the inner air guide plate of the first stage of the burner is connected to the central duty class; The hydrogen-containing fuel flows through the fuel duct arranged on the bottom surface of the burner, enters the fuel cavity in the petal-shaped fuel nozzle, and is then ejected through the inner fuel hole and the outer fuel hole asymmetrically arranged in the downstream lobe structure. It is first intensively mixed with the air flowing in from the annular gap between the petal-shaped fuel nozzle and the partition plate. The formed premixed gas forms a vortex pair downstream of the trailing edge of the lobe. The enhancement and fragmentation process of the vortex pair realizes secondary intensive mixing of the fuel and air. The air flowing through the space between the partition plate and the air guide plate changes the spatial distribution of the combustible mixture and air at the burner outlet.

2. A hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1, characterized in that: The burner is set to N levels, satisfying N = 2, 3, 4, 5; the petal-shaped fuel nozzle, two circles of partition plates and two circles of air guide plates constitute one level of the burner.

3. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The number of lobes included in the lobe structure downstream of a circle of lobe-shaped fuel nozzles is n, which satisfies 16≤n≤80.

4. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The inner angle α and the outer angle β of the lobe structure satisfy the following conditions: 10°≤α≤30°, 10°≤β≤30°.

5. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The number of fuel holes in a single row in a single lobe is p, and the number of fuel holes in a single row outside a single lobe is q, satisfying 4≤p≤20, 4≤q≤20, and the aperture size d satisfies 0.1 mm≤d≤2.0 mm.

6. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The distance L2 between the center positions of the first row of inner fuel holes and outer fuel holes in the downstream and the end face of the burner satisfies 0 ≤ L2 ≤ 5L1, where L1 is the distance between the inner partition plate and the outer partition plate.

7. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The distance L3 between the center positions of the first row of inner fuel holes and outer fuel holes in the downstream and the end of the lobe trailing edge satisfies 0 ≤ L3 ≤ L1, where L1 is the distance between the inner partition plate and the outer partition plate.

8. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The inner fuel holes and the outer fuel holes are arranged in two rows in a staggered manner. The spacing L4 between the two rows of fuel holes should satisfy 1 / 4 L1 ≤ L4 ≤ L1, where L1 is the distance between the inner partition plate and the outer partition plate.

9. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The wave height L5 of a single lobe satisfies 1 / 5 L1 ≤ L5 ≤ 4 / 5L1, where L1 is the distance between the inner partition plate and the outer partition plate.

10. The hydrogen fuel orthogonal vortex pair high-efficiency mixing, anti-flashback and low-pollution burner according to claim 1 is characterized in that: The distance L6 between adjacent partition plates and air guide plates satisfies 0.5 mm ≤ L6 ≤ 3 mm; the distance L7 between the partition plate and the end face of the burner satisfies 0 ≤ L7 ≤ 10 mm.

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