An axially staged combustion chamber taking into account the cooling of the flame tube wall
By designing axial hierarchical combustion structure and premixed combustion technology in the combustion chamber of the gas turbine, the combustion chamber is solved, and the combustion chamber is unstable and the NOX emissions are high under low load conditions, and the wall cooling of the flame cylinder and nitrogen oxide emissions are achieved. reduce.
Patent Information
- Application Number
- CN202310340869.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-27
- Publication Date
- 2024-12-06
- Estimated Expiration
- 2043-03-27
AI Technical Summary
The combustion chambers of existing gas turbines are difficult to maintain stable combustion and low pollutant emissions under low load conditions, and the fuel and air are unevenly mixed, resulting in an increase in NOX emissions.
Design an axial hierarchical combustion chamber that takes into account the cooling of the wall of the flame cylinder. By setting up a duty burner, a main burner and a secondary burner on the flame cylinder, the double wall and cooling holes can achieve uniform distribution of air, and The secondary burner adds a flow ring to form a premix burner, reducing combustion temperature and NOX emissions.
The cooling of the flame barrel wall and the equivalent ratio of the main combustion area under low load conditions are achieved, while providing sufficient air to support secondary fuel combustion under high load conditions, significantly reducing the overall nitrogen oxide emissions.
Smart Images
Figure CN116481054B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of gas turbines, and in particular to an axially staged combustion chamber taking into account the cooling of the flame tube wall. Background Art
[0002] As people's environmental awareness increases, the requirements for low-pollution emission performance of gas turbines in various application fields are becoming increasingly higher. Gas turbine emission standards are not only increasingly stringent for full-load conditions, but also restrict pollutant emissions in a wider operating range such as low-load conditions. In low-load conditions of gas turbines, it is necessary to ensure combustion stability and meet emission requirements, which puts higher requirements on combustion chamber design. For this reason, various gas turbine manufacturers have conducted more in-depth research on low-pollution combustion chambers.
[0003] At present, the research on low-pollutant combustion technology in gas turbine combustion chambers mainly focuses on the research on radial staged fuel combustion technology. The radial staged fuel combustion technology is to divide the fuel into several paths at the burner head. Different gas turbine loads supply fuel to different channels to form a local stable flame in the flame tube, while controlling the generation of pollutants. Different gas turbine manufacturers use different combustion chamber structures, and the purpose of achieving stable combustion and controlling pollutant emissions is the same. The existing combustion chamber adopts the combustion technology of multiple burners in the head. Under the low-load condition of the gas turbine, fuel is supplied to some of the head burners to ensure that the air-fuel ratio of some burners is the same as the design point. As the load increases, the number of burners supplied with fuel in the head increases until it reaches full load. In addition, there are also combustion chambers that lead manifolds from the annular cavity to the outside of the gas turbine, and then inject them back into the front of the turbine for mixing. A valve is set on the manifold to control the air flow to achieve the adjustment of the air-fuel ratio in the combustion chamber. In the prior art, there is also a combustion technology that uses axial staged fuel to broaden the low-load stable operation range of the gas turbine and reduce pollutant emissions, but only the fuel is adjustable at the rear of the flame tube, and the air flow is not adjustable. In the prior art, there is also a bypass valve structure design, in which a bypass valve is arranged on the transition section, and air does not need to be led out of the gas turbine. The bypass valve is opened at low load to maintain the air-fuel ratio at the head of the combustion chamber. The bypass valve is arranged on the transition section, close to the turbine inlet, and cannot be supplied with fuel.
[0004] The combustion stability and pollutant emission level of the gas turbine combustor depend on the combustion temperature of the main combustion area. The air and fuel ratio in the main combustion area of the combustor is maintained through the air flow distribution and fuel flow distribution in the combustor, so that the combustor can maintain stable combustion and lower pollutant emission levels in a wider range of operating conditions.
[0005] The Chinese patent with publication number CN111829007A relates to an axially graded combustion chamber based on a flame tube concave cavity structure. The designed auxiliary feed piece can bypass part of the air at low load, reduce the air-fuel ratio of the main combustion area, and stabilize combustion; at high load, the fuel is fed into the flame tube from the rear of the main combustion area, so that the equivalence ratio of the main combustion area is constant, reducing NOX emissions. After the air and fuel enter the auxiliary feed piece, they are fully mixed to form a uniform secondary combustion area at the rear of the flame tube, which will not increase NOX emissions. In addition, the concave cavity structure gradually shrinks near the side of the flame tube to prevent the flame from entering the concave cavity. However, this patent focuses on the structural improvement of the flame tube, and the fuel enters directly from the secondary burner, which will increase the diffusion of the amount of fuel entering the cavity between the flame tube and the combustion chamber shell, resulting in uneven mixing of the fuel and the air entering the secondary burner.
[0006] The Chinese patent with the announcement number CN210069920U relates to the technical field of power equipment, and discloses a combustion chamber and a gas turbine, wherein the combustion chamber comprises: a casing; a flame tube arranged in the casing, and a main combustion hole group and a mixing hole group are arranged in sequence from the head to the tail of the flame tube; a swirler and a fuel nozzle arranged at the air inlet of the flame tube; the ratio of the effective opening area of the fuel nozzle, the swirler, the main combustion hole group and the mixing hole group satisfies: the equivalence ratio in the main combustion zone is greater than 1, and the equivalence ratio in the supplementary combustion zone is less than 1. The invention achieves full mixing of fuel and air by setting a supplementary combustion zone on the flame tube, but in the case of insufficient fuel, the supplementary combustion zone cannot provide fuel in time, and there will be problems of generating nitrogen oxides and low working efficiency. Summary of the invention
[0007] In order to solve the above technical problems, the present invention provides an axially staged combustion chamber that takes into account the cooling of the flame tube wall.
[0008] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is as follows:
[0009] An axially staged combustion chamber taking into account the cooling of the flame tube wall, comprising a duty burner, a main burner, a secondary burner, a flame tube and an end cover;
[0010] The main burner is installed on the flame tube, the end of the flame tube is fixedly connected to the end cover, and the duty burner is installed on the end cover;
[0011] The secondary burners are arranged on the outer surface of the flame tube, and a plurality of them are evenly distributed in the circumference of the flame tube; the flame tube includes a double-layer wall and a single-layer wall;
[0012] The arrangement of the duty burner, the primary burner and the secondary burner constitutes an axially graded combustion structure.
[0013] Based on the above technical solution, further, the axially staged combustion chamber is also provided with a casing, the casing is fixedly connected to the end cover, the flame tube is installed inside the casing, and an inlet annular channel is provided between the inner wall of the casing and the outer wall of the flame tube.
[0014] Based on the above technical solution, further, the connection method of the single-layer wall and the double-layer wall is not limited, and they can be formed in one piece or by welding.
[0015] Based on the above technical solution, further, the double-layer wall of the flame tube includes a straight section and an inclined section, the straight section and the inclined section are connected, and a plurality of cooling holes are opened on the straight section, and the air flow of the cooling holes exceeds 30% of the total air flow, wherein the connection method of the straight section and the inclined section can be integrally formed or welded.
[0016] Based on the above technical solution, further, the secondary burner includes guide ribs and a fuel spray rod, the guide ribs are welded on the inner wall surface of the inclined section outlet end of the double-wall flame tube, the fuel spray rod is fixed on the casing, and the end of the fuel spray rod is extended into the flame tube.
[0017] Based on the above technical solution, further, a fuel spray hole is opened on the fuel spray rod, and the fuel enters the flame tube through the fuel spray hole.
[0018] Based on the above technical solution, further, the cross-sectional area of one end of the inclined section connected to the straight section is larger than the cross-sectional area of the other end of the inclined section away from the straight section, and the inclined section presents a tapered structure.
[0019] Based on the above technical solution, further, a guide ring is provided around the outer side of the inclined section, one end of the guide ring is fixed to the outer wall of the double-layer wall, and the other end is suspended.
[0020] Based on the above technical solution, further, the axially graded combustion chamber is also provided with a rectifying hole, and the rectifying hole is arranged at the end of the flame tube.
[0021] Based on the above technical solution, further, the main stage burner includes at least one swirler blade, and the swirler blade constitutes a radial swirler, and the swirler blade is also provided with a main stage fuel introduction hole for spraying fuel into the radial swirler.
[0022] Compared with the prior art, the beneficial effects of the present invention are specifically embodied in:
[0023] The present invention allows a large amount of air to enter the rear area of the main combustion area from the double-layer wall of the flame tube, which can not only ensure the cooling of the flame tube wall surface of the main combustion area, but also ensure the stability of the equivalence ratio of the main combustion area under low-load conditions, while providing the air required for secondary fuel combustion under high-load conditions. In addition, the present invention further reduces the combustion temperature of the secondary combustion area in the combustion chamber by adding a guide ring to the secondary burner to form a secondary premixed combustion burner, thereby achieving the effect of reducing overall nitrogen oxide emissions. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a schematic structural diagram of an axially staged combustion chamber embodiment 1 of the present invention;
[0025] Figure 2 for Figure 1 A magnified view of part A;
[0026] Figure 3 for Figure 1 Partial cross-section of the middle BB;
[0027] Figure 4 This is a schematic diagram of the structure of the double-wall in the axially staged combustion chamber embodiment 2 of the present invention;
[0028] Figure 5 It is a partial structural schematic diagram of the axially staged combustion chamber in Example 3 of the present invention;
[0029] Figure 6 A schematic structural diagram of an axially staged combustion chamber embodiment 3 of the present invention with a guide ring added;
[0030] Figure numerals: 1. Main burner; 2. Secondary burner; 3. Service burner; 4. Flame tube; 5. End cover; 6. Casing; 7. Double wall; 8. Single wall; 9. Straight section; 10. Inclined section; 11. Cooling hole; 12. Fuel spray rod; 13. Guide ribs; 14. Fuel spray hole; 15. Guide ring; 16. Rectification hole; 17. Short tube. DETAILED DESCRIPTION
[0031] In order to make the purpose and technical solution of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with embodiments.
[0032] It should be noted that the directions or positional relationships indicated by the terms "center", "upper" and "lower" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.
[0033] Example 1
[0034] Combined with Figure 1-Figure 3 As shown, an axially staged combustion chamber that takes into account the cooling of the flame tube wall includes a duty burner 3, a main-stage burner 1, a secondary burner 2, a flame tube 4, an end cover 5 and a casing 6; the casing 6 is fixedly connected to the end cover 5, the flame tube 4 is installed inside the casing 6, and an inlet annular channel is provided between the inner wall of the casing 6 and the outer wall of the flame tube 4. The axially staged combustion chamber is also provided with a rectifying hole, which is arranged at the end of the flame tube 4. The main-stage burner 1 includes at least one swirler blade, and the swirler blades constitute a radial swirler, and the swirler blades are also provided with a main-stage fuel introduction hole for spraying fuel into the radial swirler. The main-stage burner 1 is installed on the flame tube 4, the end of the flame tube 4 is fixedly connected to the end cover 5, and the duty burner 3 is installed on the end cover 5.
[0035] The secondary burner 2 is axially arranged on the outer surface of the flame tube 4; the flame tube 4 includes a double wall 7 and a single wall 8; the double wall 7 and the single wall 8 are integrally formed or welded. The double wall 7 of the flame tube 4 includes a straight section 9 and an inclined section 10, and the straight section 9 and the inclined section 10 are connected, which can be connected by integral forming or welding, and a plurality of cooling holes 11 are opened on the straight section 9, and the air flow of the cooling holes exceeds 30% of the total air flow. The secondary burner 2 includes a guide rib 13 and a fuel spray rod 12, the guide rib 13 is welded on the inner wall surface of the outlet end of the inclined section 10 of the double wall 7 of the flame tube 4, the fuel spray rod 12 is fixed on the casing 6, and the end of the fuel spray rod 12 is extended into the flame tube 4. The arrangement of the duty burner 3, the main burner 1 and the secondary burner 2 constitutes an axial graded combustion structure. Specifically, the air required for the secondary fuel sequentially passes through the double-wall 7 of the flame tube 4 to impact the cooling holes 11, and the guide fins 13 of the secondary burner 2 enter the flame tube 4, and are mixed with the secondary fuel for combustion, and the wall annular channel between the double-wall 7 of the flame tube 4 is connected to the air channel of the guide fins 13 of the secondary burner 2, and the guide fins 13 are arranged at the outlet position of the inclined section 10 of the double-wall 7 to ensure that the jet flows to the center of the flame tube 4. That is, the air flows into the guide fins of the secondary burner through the wall annular channel of the double-wall, and the air enters the flame tube through the channel between the guide fins.
[0036] The working principle of the axially staged combustion chamber of the present invention is:
[0037] The combustion chamber has three fuel inlets, namely, duty fuel, main fuel and secondary fuel. The duty fuel is introduced into the duty burner 3, using the diffusion combustion mode; the main fuel is introduced into the main burner 1, using the premixed combustion mode; the secondary fuel is introduced into the secondary burner 2, using the diffusion combustion mode. The side and top of the end of the fuel spray rod 12 of the secondary burner 2 are provided with a number of fuel spray holes 14, and the fuel enters the flame tube 4 through the fuel spray holes 14.
[0038] The air enters the combustion chamber through the inlet annular channel formed by the flame tube 4 and the casing 6. In the inlet annular channel, the air enters the flame tube 4 in three ways. The first way enters the head burner through the rectifying hole, and then is divided into two ways to enter the duty burner 3 and the main burner 1 respectively. The air entering the duty burner 3 is mixed with the duty fuel after passing through the axial swirler, and then enters the flame tube 4 to undergo a combustion reaction to form a diffusion flame; the air entering the main burner 1 is mixed with the main fuel, and then enters the flame tube 4 through the radial swirler and the premixing channel to undergo a combustion reaction to form a main combustion zone. The second way enters the wall annular channel between the double-layer wall 7 of the flame tube 4 through the cooling hole 11 of the flame tube 4. The wall annular channel is connected to the air channel of the guide fin 13 of the secondary burner 2. The guide fin 13 is set at the outlet position of the inclined section 10 of the double wall 7 to ensure that the jet flows to the center of the flame tube 4. The air enters the flame tube 4 through the guide fin 13 of the secondary burner 2, and is mixed with the secondary fuel to undergo a combustion reaction to form a secondary combustion zone. A small amount of third-path air enters the flame tube 4 through the gap between the secondary burner 2 and the short tube 17 on the flame tube 4, playing the role of cooling the spray rod.
[0039] During the operation of the gas turbine, under low load conditions, the amount of fuel is low. At this time, all the fuel is introduced into the head burner. Since a large amount of air enters the flame tube 4 from the cooling hole 11, the amount of air entering the head burner from the fairing is reduced, which can ensure the stability of the premixed combustion in the main combustion zone. At the same time, the cooling effect of the wall of the flame tube 4 in the main combustion zone is significant. As the load increases, fuel can be introduced into the secondary burner 2. This method ensures stable combustion in the main combustion zone and low nitrogen oxide emissions. At the same time, since a large amount of air is diverted to participate in the combustion of the secondary fuel, the equivalence ratio of the secondary burner 2 is reduced, and the generation of nitrogen oxides in the secondary combustion zone is reduced. In summary, this combustion method can not only ensure the cooling of the wall of the flame tube 4 in the main combustion area, but also ensure the stability of the equivalence ratio of the main combustion area under low load conditions, and at the same time provide the air required for the combustion of the secondary fuel under high load conditions.
[0040] Example 2
[0041] Different from Example 1, in order to further reduce nitrogen oxide emissions, the secondary burner 2 can be designed as a premixing mode, such as Figure 4 As shown, a guide ring 15 is arranged around the outer side of the inclined section 10, one end of the guide ring 15 is fixed to the outer wall of the double wall 7, and the other end is suspended.
[0042] The working principle of the staged combustion chamber of this embodiment 2 is:
[0043] A guide ring 15 is added on the outside of the inclined section of the double wall 7, and the fuel spray rod 12 of the secondary burner 2 penetrates into the guide annular channel between the guide ring 15 and the flame tube 4. The fuel spray rod 12 has a plurality of fuel spray holes 14 on the leeward side. The fuel enters the guide annular channel through the fuel spray holes 14, and after being mixed with the air entering the inclined section 10 of the double wall 7 of the flame tube 4, it enters the flame tube 4 through the impact cooling holes 11 and the guide ribs 13 of the double wall 7, and a combustion reaction occurs in the flame tube 4, forming a premixed combustion mode.
[0044] Example 3
[0045] Different from Example 1, Figure 5 and Figure 6 As shown, the cross-sectional area of one end of the inclined section 10 connected to the straight section 9 is larger than that of the other end of the inclined section 10 away from the straight section 9, and the inclined section 10 is a tapered structure with a tapering angle of α.
[0046] The working principle of the staged combustion chamber of the present embodiment 3 is as follows: the tapered structure can increase the flow rate of the air flowing out of the guide fins, and can reduce the risk of flashback when the secondary burner uses the premixing mode.
[0047] The above is only an embodiment of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.
Claims
1. An axially staged combustion chamber that takes into account the cooling of the flame tube wall. It is characterized in that Includes duty burner, main burner, secondary burner, flame tube and end cover; The main burner is installed on the flame tube, the end of the flame tube is fixedly connected to the end cover, and the duty burner is installed on the end cover; The secondary burners are arranged around the outer surface of the flame tube, and a plurality of them are evenly distributed around the flame tube; the flame tube includes a double wall and a single wall; The double-layer wall of the flame tube includes a straight section and an inclined section, the straight section and the inclined section are connected, and a plurality of cooling holes are opened on the straight section, and the air flow of the cooling holes exceeds 30% of the total air flow; a guide ring is arranged around the outer side of the inclined section, one end of the guide ring is fixed to the outer wall of the double-layer wall, and the other end is suspended; The arrangement of the duty burner, the primary burner and the secondary burner constitutes an axially graded combustion structure.
2. An axially staged combustion chamber taking into account the cooling of the flame tube wall according to claim 1, It is characterized in that The axially staged combustion chamber is also provided with a casing, which is fixedly connected to the end cover, the flame tube is installed inside the casing, and an inlet annular channel is provided between the inner wall of the casing and the outer wall of the flame tube.
3. An axially staged combustion chamber taking into account the cooling of the flame tube wall according to claim 2, It is characterized in that The secondary burner comprises a guide rib and a fuel spray rod. The guide rib is welded on the inner wall surface of the outlet end of the inclined section of the double-layer wall of the flame tube. The fuel spray rod is fixed on the casing. The end of the fuel spray rod extends into the flame tube.
4. An axially staged combustion chamber with consideration of flame tube wall cooling according to claim 3, It is characterized in that The fuel spray rod is provided with a fuel spray hole, and the fuel enters the flame tube through the fuel spray hole.
5. An axially staged combustion chamber taking into account the cooling of the flame tube wall according to claim 4, It is characterized in that The cross-sectional area of one end of the inclined section connected to the straight section is larger than the cross-sectional area of the other end of the inclined section away from the straight section, and the inclined section is in a tapered structure.
6. An axially staged combustion chamber taking into account the cooling of the flame tube wall according to claim 1, It is characterized in that The axially staged combustion chamber is also provided with a rectifying hole, which is arranged at the end of the flame tube.
7. An axially staged combustion chamber with consideration of flame tube wall cooling according to claim 1, It is characterized in that The main stage burner comprises at least one swirler blade, and the swirler blade forms a radial swirler. The swirler blade is also provided with a main stage fuel introduction hole for spraying fuel into the radial swirler.
8. An axially staged combustion chamber with consideration of flame tube wall cooling according to claim 1, It is characterized in that The double-layer wall and the single-layer wall are integrally formed or welded.