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CN-122015135-A - Axial staged combustion secondary combustor with micro-mixing pipe

CN122015135ACN 122015135 ACN122015135 ACN 122015135ACN-122015135-A

Abstract

The invention provides an axial staged combustion secondary combustor with a micro-mixing pipe, and relates to the technical field of combustion of gas turbines. The burner comprises a straight vane type burner body which is gradually expanded and extends, wherein a fuel cavity is formed by surrounding the outer side wall and the inner side wall of the burner body, a diffusion cavity is formed by surrounding the inner side wall of the burner body, a fuel inlet is arranged at the upstream end of the fuel cavity, a fuel hole which is communicated with the two cavities is formed in the inner side wall of the fuel cavity, a plurality of micro-mixing pipes which are perpendicular to the section of each vane and are communicated are arranged in the diffusion cavity, two ends of each micro-mixing pipe correspond to an air inlet side and an air outlet side, spray holes are formed in the pipe wall of each micro-mixing pipe, and the inner side wall converges in the direction of the diffusion cavity at the downstream of the micro-mixing pipe to form a converging channel. According to the invention, the fuel is uniformly distributed through the two-stage pressure release of the fuel cavity and the diffusion cavity, the air rectification and the primary mixing are realized through the micro-mixing pipe, the secondary intensified mixing and the pneumatic tempering inhibition are realized through the convergence channel, the combustion stability is obviously improved, the NOx emission is reduced, and the support is provided for the safe and clean operation of the high-power gas turbine under the wide working condition.

Inventors

  • LI SHANSHAN
  • YUAN HAOYANG
  • Pei Fanqi
  • SHEN WENKAI
  • LV XUAN

Assignees

  • 中国联合重型燃气轮机技术有限公司

Dates

Publication Date
20260512
Application Date
20260320

Claims (15)

  1. 1. An axial staged combustion secondary burner with micro-mixing tubes, comprising: the burner body is of a straight blade type structure which gradually expands along the axial direction of the combustion chamber and comprises a blade type outer side wall (10) and a blade type inner side wall (20); The fuel cavity is formed by enclosing the blade-shaped outer side wall (10) and the blade-shaped inner side wall (20), and is a closed cavity positioned at the periphery of the burner body, and one end of the blade-shaped outer side wall (10) positioned at the upstream side is provided with a fuel inlet (11); the diffusion cavity is formed by enclosing the blade-type inner side wall (20), is positioned in the middle of the burner body and is a closed cavity adjacent to the fuel cavity, and a plurality of fuel holes (21) are formed in the blade-type inner side wall (20) and are used for communicating the fuel cavity and the diffusion cavity; the micro-mixing pipes (30) are arranged in the diffusion cavity, penetrate through the combustor body perpendicular to the sections of the blades, and correspond to the air inlet side and the air outlet side respectively at two ends of the combustor body, and spray holes (31) are formed in the pipe walls of the micro-mixing pipes (30).
  2. 2. The axially staged combustion secondary burner with micro-mixing tube as set forth in claim 1, wherein the fuel chamber has a flow cross section that increases gradually in the axial direction of the combustion chamber to form a primary pressure relief chamber for the fuel.
  3. 3. The axially staged combustion secondary burner with micro-mixing tube as set forth in claim 1, wherein the flow cross section of the diffusion chamber increases gradually along the combustion chamber axis and the volume of the diffusion chamber is greater than the volume of the fuel chamber to form a secondary pressure relief chamber for fuel.
  4. 4. The micro-mixing tube axial staged combustion secondary combustor as claimed in claim 3, wherein the plurality of diffusion chambers are arranged in sections along the length direction of the combustor body, and each section of fuel diffusion chamber has different chamber diameters.
  5. 5. The axially staged combustion secondary burner with micro-mixing tube as claimed in any of claims 1-4, wherein the fuel holes (21) are arranged on both sides and downstream ends of the vane type inner side wall (20), and the number of the fuel holes (21) on the downstream end is smaller than the number of the both sides.
  6. 6. The axially staged combustion secondary burner with micro-mixing tube as claimed in claim 1, wherein the injection holes (31) are arranged at one end of the micro-mixing tube (30) close to the air inlet side.
  7. 7. The axially staged combustion secondary burner with micro-mixing tube as claimed in claim 6, wherein the distribution of the spray holes (31) on the wall of the micro-mixing tube (30) is single hole, symmetrical double hole or circumferential multi-hole.
  8. 8. The axially staged combustion secondary burner with micro-mixing tube as claimed in claim 6, characterized in that the ratio of the diameter of the injection holes (31) to the inner diameter of the micro-mixing tube (30) is 0.2-0.5.
  9. 9. The axially staged combustion secondary burner with micro-mixing tube as claimed in claim 6, wherein the micro-mixing tube (30) has an inner diameter of 5-10mm and the ratio of the length of the micro-mixing tube (30) to the inner diameter is 15-50.
  10. 10. The axially staged combustion secondary burner with micro-mixing tubes as claimed in claim 9, wherein a plurality of the micro-mixing tubes (30) are arranged in an array, and a ratio of a space between adjacent micro-mixing tubes (30) to an inner diameter of the micro-mixing tubes (20) is 0.5-2.0.
  11. 11. The axially staged combustion secondary burner with micro-mixing tube as claimed in claim 1, wherein the vane type inner side wall (20) converges in a downstream section of the outlet end of the micro-mixing tube (30) toward the diffuser chamber to form a converging passage, the cross-sectional area of which gradually decreases in the direction of the gas flow.
  12. 12. The micro-mixed tube axial staged combustion secondary burner as claimed in claim 11, wherein the converging channel has a converging angle greater than 10 °.
  13. 13. The micro-mixed tube axial staged combustion secondary burner as claimed in claim 12, wherein the converging channel has a converging angle of 15 ° -30 °.
  14. 14. A combustion chamber of a gas turbine comprises a primary combustor and a secondary combustor which are sequentially arranged along the axial direction, and is characterized in that the secondary combustor is an axial staged combustion secondary combustor with a micro-mixing tube according to any one of claims 1 to 13.
  15. 15. The gas turbine combustor as set forth in claim 14, wherein the plurality of secondary combustors are uniformly arranged in the circumferential direction of the combustor, the smallest flow area between adjacent secondary combustors is a throat cross-sectional area A2, the passage cross-sectional area downstream of the secondary combustors is a downstream cross-sectional area A1, and the downstream cross-sectional area A1 is equal to or smaller than the throat cross-sectional area A2.

Description

Axial staged combustion secondary combustor with micro-mixing pipe Technical Field The invention relates to the technical field of combustion of gas turbines, in particular to an axial staged combustion secondary combustor with a micro-mixing pipe. Background With increasingly stringent environmental regulations, reducing NOx emissions is a central goal in gas turbine combustor design. The modern heavy gas turbine generally adopts a lean premixed combustion technology to inhibit thermal NOx generation, wherein the axial staged combustion is an advanced scheme, a primary combustion zone is responsible for maintaining flame stability under most working conditions, a secondary combustion zone is started under high-temperature and high-load working conditions, and the full burnout of fuel and the control of combustion temperature are realized through afterburning. The performance of the secondary burner directly determines the stability and emission level of the axially staged combustion, which requires a rapid and uniform mixing of fuel and air in the high-speed main stream and ensures flame-stable anchoring. The existing secondary nozzle generally adopts a circular or oval cross-section structure, and the design is easy to form a cylindrical turbulent flow effect at the downstream, so that on one hand, the air inlet of the primary burner is possibly uneven, and on the other hand, a large-area backflow area is easily induced at the upstream of the primary burner, the tempering risk of the primary burner is obviously increased, and the combustion stability and the operation safety are influenced. Aiming at the problems of low mixing efficiency and high tempering risk, the prior art proposes an improvement scheme of arranging a micro-mixing pipe inside a secondary combustor, and improves the mixing effect of fuel and air through micro-scale mixing. However, the existing secondary combustor adopting the micro-mixing tube still has the defects that (1) the structural design of the micro-mixing tube is imperfect, the number, arrangement and spray hole positions are lack of optimization, so that the mixing is uneven, the outlet concentration field is uneven, the local high-temperature area is obvious, NOx is limited to be further reduced, (2) the fuel injection uniformity is insufficient, the fuel flow of each micro-mixing tube is unevenly distributed due to the unreasonable diffusion cavity or fuel distribution structure, the combustion uniformity is influenced and the local tempering risk is increased, and (3) the tempering protection structure is lacked, the outlet section of the micro-mixing tube is lack of convergence channel design, a pneumatic barrier cannot be formed, the flame root is close to the inside of the tube, the tempering easily occurs when the load fluctuates, and the structural safety is threatened. The prior patent CN118463179A discloses a micro-mixing burner and an axial air staged combustion system, and the radial support stability of a mixing tube is improved through a positioning column and a stabilizing mechanism, so that the radial bending problem caused by air flow blowing is avoided. However, the patent does not provide tempering protection for the outlet structure of the micro-mixing tube, and cannot solve the technical problems of uneven fuel mixing and high tempering risk. The prior patent CN121557483A discloses a multi-angle microtube staged combustion cyclone gas burner, which realizes uniform fuel injection through a multi-angle fuel distribution device and introduces reflux smoke through a flaring of a mixing tube and a rolling mouth of an arc-shaped air sleeve. However, the scheme does not optimize the interference problem of the secondary burner to the primary burner flow field in the axial staged combustion, and does not solve the technical defect that the outlet of the micro-mixing tube lacks a tempering protection structure. In view of the foregoing, there is a need for a device that can overcome the problems of uneven fuel mixing, insufficient flashback protection, and large interference to the primary combustor flow field in the prior art, and achieve the goals of efficient and uniform fuel and air mixing, stable anchoring of flame, and safety and low emission of the overall operation of the combustion chamber. Disclosure of Invention Based on the current state of the art, the invention provides an axial staged combustion secondary combustor with a micro-mixing pipe, which aims to solve the problems of uneven combustion, higher NOx emission, high backfire risk, large flow field interference and the like of the existing secondary combustor. Compared with the prior art, the invention realizes double improvement of combustion stability and combustion efficiency and cooperative reduction of NOx and CO emission, and provides key technical support for clean and safe operation of the high-parameter and high-power gas turbine in a wide working condition range. In order to achieve t