A combustion chamber with a trapped vortex micro-mixing combined nozzle

Abstract

A combustion chamber with a trapped vortex micro-mixing combination nozzle, the combustion chamber includes a nozzle body, a flame tube and a combustion chamber casing; wherein the nozzle body is arranged at the head of the combustion chamber, and is connected with the flame tube and is arranged together in the combustion chamber casing; the internal cylindrical area formed by the flame tube is the combustion zone of the combustion chamber, and the flame tube and the combustion chamber casing form a compressed air flow cavity. Compared with the traditional combustion chamber, the nozzle body of the present invention adopts the staged combustion technology, and takes into account the technical advantages of the micro-mixing burner and the trapped vortex burner. On the basis of ensuring stable combustion under low working conditions, it effectively reduces pollutant emissions under high working conditions, thereby broadening the stable operation range of the gas turbine combustion chamber.

Description

Technical Field

[0001] The invention relates to the technical field of a gas turbine combustion chamber, in particular to a combustion chamber with a trapped vortex micro-mixing combined nozzle. Background Art

[0002] Gas turbines have become an indispensable source of power in industrial production due to their high efficiency and cleanliness. With the iteration and update of technology, gas turbines are constantly developing towards higher efficiency and wider load regulation range. How to achieve stable, low-emission combustion within a wide load range is an important performance target of the gas turbine combustor.

[0003] Most of the existing gas turbines use burners with Dry Low NOx (DLN) combustion technology. Such burners mainly mix excess air and fuel into lean premixed gas to suppress the generation of nitrogen oxides. However, when the gas turbine develops to J level, its temperature level is close to the critical value of the DLN effective working range (1670-1900K). If the temperature rises further, on the one hand, even if the air and fuel are fully premixed, nitrogen oxide emissions will increase significantly. On the other hand, if conventional swirl premixed combustion is used, there are risks such as flashback, auto-ignition, and thermoacoustic oscillation. Therefore, Dry Low NOx (DLN) combustion technology can no longer meet the development of gas turbines.

[0004] Compared with traditional swirl burners, micro-premixed combustion technology mixes air and fuel in a tiny pipe, which improves the uniformity of gas mixing. It also has a small flame structure and a high gas flow rate. Combined with the quenching effect of the pipe diameter, micro-premixed combustion technology can not only reduce NOX emissions but also has good anti-flashback capabilities. However, due to the lack of a swirl structure and a higher gas flow rate than traditional burners, the stability of micro-premixed combustion technology is relatively poor. Summary of the invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the prior art and propose a combustion chamber with a trapped vortex micro-mixing combined nozzle that effectively reduces pollutant emissions under high operating conditions while ensuring stable combustion under low operating conditions.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solution: a combustion chamber with a trapped vortex micro-mixing combined nozzle, which is characterized by comprising a nozzle body, a flame tube and a combustion chamber casing, wherein:

[0007] The nozzle body is arranged at the head of the combustion chamber, and is connected with the flame tube and arranged together in the combustion chamber casing; an air intake channel is arranged at the bottom of the combustion chamber casing, the combustion chamber casing and the flame tube cylinder form an air flow cavity, and the internal cylindrical area formed by the flame tube is the combustion zone of the combustion chamber;

[0008] The nozzle body adopts a staged combustion technology, including a duty stage and a main combustion stage, and the duty stage is arranged outside the main combustion stage;

[0009] The main combustion stage includes a main combustion stage fuel inlet pipe, a main combustion stage fuel cavity, a nozzle micro-premixing tube bundle, and a nozzle end cover;

[0010] The main combustion stage fuel inlet pipe is connected to the main combustion stage fuel cavity, and the main combustion stage fuel cavity is connected to the nozzle micro-premixing tube bundle to provide the main combustion stage fuel therefor;

[0011] The side wall and the front end surface of the nozzle micro-premixing tube bundle are respectively provided with an air inlet hole and a fuel inlet hole;

[0012] The nozzle end cover is arranged at the nozzle micro-premixing tube bundle outlet, and a cooling hole is arranged on the side wall of the nozzle end cover;

[0013] The duty class includes a duty class fuel intake pipe, a duty class fuel ring pipe, a duty class fuel intake branch pipe, a duty class fuel cavity, and a concave cavity;

[0014] The duty class fuel air intake pipe is connected to the duty class fuel annular pipe, and the duty class fuel annular pipe is connected to the duty class fuel cavity through the duty class fuel air intake branch pipe;

[0015] The concave cavity comprises a concave cavity front wall, a concave cavity rear wall and a concave cavity upper wall;

[0016] The duty class fuel cavity is arranged on the upper wall of the concave cavity, and the upper wall of the concave cavity is also provided with a duty class fuel air inlet hole, and the duty class fuel air inlet hole runs through the duty class fuel cavity and the concave cavity;

[0017] The front wall of the concave cavity and the rear wall of the concave cavity are respectively provided with a front air intake hole and a rear air intake hole. The front air intake hole is close to the upper wall of the concave cavity, and the rear air intake hole is far away from the upper wall of the concave cavity.

[0018] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the inner diameter d of the nozzle micro-premixing tube bundle is 5 to 12 mm.

[0019] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the length of the nozzle micro-premixing tube bundle is 15 to 120 mm.

[0020] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the air inlet holes are circular holes or strip holes, which are evenly arranged in the circumferential direction.

[0021] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the number of rows of air inlet holes along the axis of the tube bundle is 1 to 2 rows.

[0022] The technical problem to be solved by the present invention can be further achieved by the following technical solution: the number of the duty class fuel intake branch pipes is ≥4, and they are evenly arranged along the duty class fuel ring pipe.

[0023] The technical problem to be solved by the present invention can also be further achieved through the following technical solution: the value-class fuel air inlet holes are evenly arranged on the upper wall of the concave cavity, and the number of rings is ≥2.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) Compared with traditional burners, each micro-premixing tube of the main nozzle of this burner is relatively independent and can be expanded in a modular array according to load requirements, so it has better scalability.

[0026] (ii) The micro-mixing tube nozzles are all set at the millimeter level. By mixing the fuel and air at the millimeter scale, a more uniform fuel and air premix can be obtained compared to the traditional swirl premixing burner. Therefore, the peak flame temperature during the combustion process can be reduced, thereby achieving a better nitrogen oxide emission reduction effect.

[0027] (III) The nozzles of the micro-mixing tubes are all set at the millimeter level. The flow velocity in the micro-mixing tubes is relatively high, which can effectively avoid the flashback problem, shorten the residence time of high-temperature flue gas, and reduce nitrogen oxide emissions.

[0028] (iv) Since the flame formed by the micro-mixing tube is relatively short and the temperature distribution is uniform, the length of the flame tube in the combustion chamber can be greatly shortened.

[0029] (V) Since multiple micro-premixing tubes are distributed in an array, the ejected flames are relatively dispersed in the radial direction and the heat release is relatively uniform. At the same time, each main nozzle micro-mixing tube can adopt different structural schemes to achieve natural frequency differences, reduce the probability of thermal-acoustic coupling, and effectively avoid combustion instability problems.

[0030] (6) The nozzle body adopts staged combustion technology: in the small state, only the value class works, and in the large state, the value class and the main combustion stage work at the same time, thus broadening the operating range of the combustion chamber.

[0031] (VII) The duty class is set outside the main combustion stage and does not occupy the cross-sectional space of the nozzle body. The nozzle body can be arranged with more nozzle micro-mixing tube bundles according to load requirements, thus widening the upper limit of the combustion chamber load;

[0032] (8) The combination of trapped vortex and micro-mixed combustion technology takes into account the advantages of trapped vortex stability and micro-mixed low emission technology. On the basis of achieving low emission performance, it improves combustion stability and broadens the operating boundary of the combustion chamber;

[0033] (IX) Cooling holes are provided on the side wall of the nozzle end cover. On the one hand, the cooling gas can directly impact the nozzle tube bundle to achieve cooling. On the other hand, it can form a cooling gas film on the high-temperature side of the nozzle end face to isolate the nozzle end face from the flame and protect the nozzle end face from being eroded by high-temperature flue gas / flame. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a three-dimensional schematic diagram of a combustion chamber of the present invention;

[0035] Figure 2 It is a schematic diagram of the combustion chamber structure principle;

[0036] Figure 3 is a schematic diagram of the nozzle body;

[0037] Figure 4 This is an enlarged view of the fuel ring pipe department of the duty shift;

[0038] Figure 5 It is a two-dimensional schematic diagram of a single micro-premixing tube in the main combustion stage of the nozzle body;

[0039] Figure 6 for Figure 5 Premixing tube cross section;

[0040] The meanings of the reference numerals are as follows: 1. Combustion chamber of gas turbine; 2. Combustion chamber casing; 3. Flame tube; 4. Nozzle body; 21. Compressed air inlet; 22. Compressed air flow direction; 23. Compressed air flow cavity; 31. Duty class combustion zone; 32. Main combustion stage combustion zone; 41. Main combustion stage fuel inlet pipe; 42. Duty class fuel inlet pipe; 43. Nozzle micro-mixing tube bundle; 44. Nozzle end face; 411. Main combustion stage fuel cavity; 412. Fuel gas flow direction; 413. Mixed gas flow direction; 421. Duty class fuel annular pipe; 422. Duty class fuel inlet branch pipe; 423. Duty class fuel cavity; 424. Duty class fuel inlet hole; 425. Concave cavity front wall; 426. Concave cavity rear wall; 427. Concave cavity upper wall; 428. Air front inlet hole; 429. Air rear inlet hole; 42A. Cooling hole; 431. Air inlet hole; 432. Fuel inlet hole. DETAILED DESCRIPTION

[0041] The specific technical solutions of the present invention are further described below. To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer and to facilitate those skilled in the art to further understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them, and do not constitute a limitation on the rights thereof. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0042] like Figure 1-3 As shown, the present embodiment discloses a trapped vortex micro-mixing combined nozzle and a combustion chamber including the same, including: 2, a combustion chamber casing; 3, a flame tube; 4, a nozzle body; 41, a main combustion stage fuel inlet pipe; 42, a duty class fuel inlet pipe; 43, a nozzle micro-mixing tube bundle; 44, a nozzle end face; 411, a main combustion stage fuel cavity; 421, a duty class fuel annular pipe; 422, a duty class fuel inlet branch pipe; 423, a duty class fuel cavity; 424, a duty class fuel inlet hole; a concave cavity; 425, a concave cavity front wall; 426, a concave cavity rear wall; 427, a concave cavity upper wall;

[0043] like Figure 1-2 As shown, the combustion chamber of this embodiment includes a nozzle body 4, which is arranged at the head of the combustion chamber 1 and connected with the flame tube 3 and arranged together in the combustion chamber casing 2. The combustion chamber casing 2 and the flame tube 4 cylinder form an air flow cavity 23, and an air inlet 21 is also opened at the bottom of the combustion chamber casing 2. Compressed air flows into the combustion chamber casing 2 along the air flow direction 22 through the air inlet 21, and flows toward the nozzle body 4 along the air flow cavity 23. One stream of air enters the concave cavity through the front air intake hole 428 and the rear air intake hole 429 on the front and rear walls of the concave cavity to participate in combustion, and another stream of air enters the nozzle micro-premixing tube bundle through the air inlet 431 on the nozzle micro-premixing tube bundle, and forms a premixed gas after mixing with the main combustion stage fuel, and flows out of the nozzle micro-premixing tube bundle 43 and enters the main combustion zone 32 for combustion.

[0044] The gas turbine combustion chamber 1 of this embodiment adopts a main combustion stage and a duty stage stage stage combustion mode. The internal cylindrical area formed by the flame tube 3 is the main combustion stage combustion zone 32 of the combustion chamber, and the main combustion stage combustion zone 32 occupies the entire cross-sectional area of ​​the flame tube; the annular area formed by the concave cavity is the duty stage combustion zone 31, and the duty stage combustion zone 31 is arranged in the air flow cavity 23, and wraps the main combustion stage combustion zone 32.

[0045] like Figure 3 As shown, the main combustion stage includes a main combustion stage fuel intake pipe 41, a main combustion stage fuel cavity 411, a nozzle micro-premixing tube bundle 43, and a nozzle end face 44. The main combustion stage fuel intake pipe 41 is connected to the main combustion stage fuel cavity 411, and the main combustion stage fuel cavity 411 is connected to the nozzle micro-premixing tube bundle 43 to provide the main combustion stage fuel. The main combustion stage nozzle micro-premixing tube bundle 43 can be modularly arrayed according to actual load requirements, and the number of layers is preferably 3 to 8 layers, and in this embodiment, 4 layers are arranged in a staggered manner to reduce the influence of the outer tube bundle intake on the inner tube bundle intake.

[0046] The nozzle end cover 44 is close to the outlet of the nozzle micro-premixing tube bundle 43, isolating the air cavity and the flame tube combustion zone. The side wall of the nozzle end cover is provided with cooling holes 42A. The compressed air flows out through the cooling holes. On the one hand, it directly impacts the nozzle micro-premixing tube bundle 43 to achieve impact cooling and cooling. On the other hand, the outflowing cooling air forms a cooling air film on the high-temperature side of the nozzle end cover 44. The cooling air film isolates the nozzle end cover 44 from the high-temperature flue gas / flame, thereby protecting the nozzle end cover 44 from high-temperature flue gas / flame erosion.

[0047] The duty class includes a duty class fuel intake pipe 42, a duty class fuel ring pipe 421, a duty class fuel intake branch pipe 422, a duty class fuel cavity 423, and a concave cavity. The duty class fuel intake pipe 42 is connected to the duty class fuel ring pipe 421, and the duty class fuel ring pipe 421 is connected to the duty class fuel cavity 423 through the duty class fuel intake branch pipe 422; the number of the duty class fuel intake branch pipes 422 is ≥ 4, and in this embodiment, there are 6, which are evenly arranged along the duty class fuel ring pipe 421 to ensure uniform circumferential intake of the duty class fuel; the concave cavity includes a concave cavity front wall 425, a concave cavity rear wall 426, and a concave cavity upper wall 427. The duty class fuel cavity 423 is arranged on the concave cavity upper wall 427, and the concave cavity upper wall 47 is also provided with a duty class fuel. The fuel intake hole 424 of the value class runs through the fuel cavity 423 of the value class and the concave cavity. The number of the fuel intake holes 424 of the value class is ≥ 2 rings. In this embodiment, there are 2 rings. The fuel intake holes 424 of the value class are evenly arranged on the upper wall 427 of the concave cavity to ensure that the fuel of the value class is evenly counted into the concave cavity in the circumferential direction. The front wall 425 of the concave cavity and the rear wall 426 of the concave cavity are respectively provided with a front air intake hole 428 and a rear air intake hole 429, wherein the front air intake hole 428 is close to the upper wall 427 of the concave cavity, and the rear air intake hole 429 is arranged away from the upper wall 427 of the concave cavity.

[0048] Working principle of the duty class: the duty class fuel enters the duty class fuel ring pipe 421 from the duty class fuel inlet pipe 42, and then evenly enters the duty class fuel cavity 423 through the duty class fuel inlet branch pipe 422, and finally enters the concave cavity through the duty class fuel inlet hole 424, and the air entering through the air front inlet hole 428 flows and mixes in the concave cavity. A part of the high-temperature flue gas generated by the combustion in the concave cavity changes its flow direction due to the air blocking entering through the air rear inlet hole 429, and flows back into the concave cavity to preheat the fresh premixed gas in the concave cavity, which can be used as a continuous ignition source for the concave cavity. Another part of the high-temperature flue gas flows into the main combustion zone 32 along the gap between the air rear inlet holes 429, ignites the main combustion stage premixed gas flowing out of the nozzle micro-premixing tube bundle 43, thereby realizing stable combustion of the main combustion stage.

[0049] Figure 4It is the nozzle micro-premixing tube bundle 43 in this embodiment. The fuel inlet 432 is located at the end of the nozzle micro-premixing tube bundle 43 and is connected to the main combustion stage fuel chamber 411; the air inlet hole 432 is arranged on the side wall of the nozzle micro-premixing tube bundle 43, and can adopt a circular hole or a strip hole structure. In this embodiment, a strip hole is selected, and the number of rows of air holes along the axis is preferably 1 to 2 rows, and the number of rows in this embodiment is 1 row.

[0050] The fuel flows into the main combustion stage fuel chamber 411 through the main combustion stage fuel pipe along the fuel flow direction 412. The fuel is evenly dispersed in the main combustion stage fuel chamber 411. Then, the fuel flows into the nozzle micro-premixing tube bundle 45 from the fuel inlet 432 at the end of the nozzle micro-premixing tube bundle 43, and mixes with the cross air flow entering from the air inlet hole 432 while flowing downstream. Finally, the mixed premixed gas flows into the main combustion zone 32 of the combustion chamber along the flow direction 413 to participate in combustion.

[0051] Combined with previous research findings, the internal flow field structure of the annular value-class combustion zone 31 formed by the concave cavity is basically not affected by the distortion of the incoming flow conditions, and has good ignition performance and a wide stable boundary. The micro-premixed combustion technology has good low-emission combustion potential. This embodiment combines the two combustion methods and takes into account the technical advantages of both. Therefore, it can ensure stable combustion under low operating conditions and effectively reduce pollutant emissions under high operating conditions, thereby broadening the stable operation range of the gas turbine combustion chamber.

[0052] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A combustion chamber with a trapped vortex micro-mixing combined nozzle, characterized in that: It includes a nozzle body, a flame tube and a combustion chamber casing, wherein: The nozzle body is arranged at the head of the combustion chamber, and is connected with the flame tube and arranged together in the combustion chamber casing; an air intake channel is arranged at the bottom of the combustion chamber casing, the combustion chamber casing and the flame tube cylinder form an air flow cavity, and the internal cylindrical area formed by the flame tube is the combustion zone of the combustion chamber; The nozzle body adopts a staged combustion technology, including a duty stage and a main combustion stage, and the duty stage is arranged outside the main combustion stage; The main combustion stage includes a main combustion stage fuel inlet pipe, a main combustion stage fuel cavity, a nozzle micro-premixing tube bundle, and a nozzle end cover; The main combustion stage fuel inlet pipe is connected to the main combustion stage fuel cavity, and the main combustion stage fuel cavity is connected to the nozzle micro-premixing tube bundle to provide the main combustion stage fuel therefor; The side wall and the front end surface of the nozzle micro-premixing tube bundle are respectively provided with an air inlet hole and a fuel inlet hole; The duty class includes a duty class fuel intake pipe, a duty class fuel ring pipe, a duty class fuel intake branch pipe, a duty class fuel cavity, and a concave cavity; The duty class fuel air intake pipe is connected to the duty class fuel annular pipe, and the duty class fuel annular pipe is connected to the duty class fuel cavity through the duty class fuel air intake branch pipe; The concave cavity comprises a concave cavity front wall, a concave cavity rear wall and a concave cavity upper wall; The duty class fuel cavity is arranged on the upper wall of the concave cavity, and the upper wall of the concave cavity is also provided with a duty class fuel air inlet hole, and the duty class fuel air inlet hole runs through the duty class fuel cavity and the concave cavity; A cooling hole is provided on the side wall of the nozzle end cover; The front wall of the concave cavity and the rear wall of the concave cavity are respectively provided with a front air intake hole and a rear air intake hole. The front air intake hole is close to the upper wall of the concave cavity, and the rear air intake hole is far away from the upper wall of the concave cavity.

2. The combustion chamber with a trapped vortex micro-mixing combined nozzle according to claim 1, characterized in that: The inner diameter d of the nozzle micro-premixing tube bundle is 5 to 12 mm.

3. The combustion chamber with a trapped vortex micro-mixing combined nozzle according to claim 1, characterized in that: The nozzle micro-premixing tube bundle has a length of 15 to 120 mm.

4. The combustion chamber with a trapped vortex micro-mixing combined nozzle according to claim 1, characterized in that: The air inlet holes are circular holes or strip holes, and are evenly arranged in the circumferential direction.

5. The combustion chamber with a trapped vortex micro-mixing combined nozzle according to claim 4 is characterized in that: The number of rows of air inlet holes along the axis of the tube bundle is 1 to 2.

6. The combustion chamber with a trapped vortex micro-mixing combined nozzle according to claim 1, characterized in that: The number of the duty class fuel intake branch pipes is ≥ 4, and they are evenly arranged along the duty class fuel ring pipe.

7. The combustion chamber with a trapped vortex micro-mixing combined nozzle according to claim 1, characterized in that: The fuel intake holes for the duty class are evenly arranged on the upper wall of the concave cavity, with the number of rings being ≥2.

Images