CN114857619B - Micro-mixed combustion chamber of gas turbine - Google Patents

Abstract

A micro-mixed combustion chamber of a gas turbine belongs to the technical field of combustion chambers of gas turbines. The combustion device is arranged in the outer shell, and an air inlet cavity is formed between the outer wall of the combustion device and the inner wall of the outer shell; the combustion device comprises a burner and a flame tube, a nozzle area is arranged on the burner, the flame tube is arranged at the periphery of the nozzle area, and a flue gas outlet communicated with the flame tube is arranged on the outer shell; the nozzle area comprises a class micro-premixing nozzle area and a main combustion stage micro-premixing nozzle area; the burner is provided with a fuel supply area in the direction opposite to the nozzle area, the periphery of the burner is provided with a shell covering the fuel supply area, and the fuel supply area comprises an on-duty mixing cavity and a main combustion mixing cavity; the periphery of the on-duty stage mixing cavity is provided with a rotary air inlet channel communicated with the air inlet cavity, the shell is provided with an air inlet communicated with the air inlet channel, and the shell is provided with an air inlet communicated with the air inlet cavity and used for supplying air to the main combustion stage mixing cavity. Thereby reducing the emission of nitrogen oxides and improving the cooling efficiency of the flame tube.

Description

A gas turbine slightly mixed combustion chamber

Technical field

The invention relates to the technical field of gas turbine micro-mixed combustion chambers, in particular to a gas turbine micro-mixed combustion chamber.

Background technique

Gas turbines have become an indispensable source of power in industrial production due to their efficient and clean characteristics. With the iterative updates of technology, gas turbines continue to develop towards higher efficiency and a wider load adjustment range. The main method to improve cycle efficiency is to increase The combustion temperature and pressure are achieved. Paradoxically, as the combustion temperature and pressure increase, on the one hand, the generation of nitrogen oxides increases rapidly, and on the other hand, due to the dual factors of the decline in cooling gas quality and the increase in combustion temperature The influence makes it more difficult to cool the flame tube wall. Therefore, how to achieve safe, stable and low-emission combustion in a wide load range is an important performance goal of the gas turbine micro-mixed combustor.

Most existing gas turbines use dry low NOx (DLN) combustion technology burners. This type of burner mainly mixes excess air and fuel into lean premixed gas to suppress the generation of nitrogen oxides. However, as the gas turbine develops to J level, its temperature level is already 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 completely premixed, the nitrogen oxide emissions will On the other hand, if conventional swirling premixed combustion is used, there are risks such as backfire, self-ignition, thermoacoustic oscillation, etc. Therefore, dry low NOx (DLN) combustion technology can no longer meet the needs of gas turbines. develop.

Therefore, there is an urgent need to propose a micro-mixed combustion chamber for gas turbines that can reduce nitrogen oxide emissions and improve flame tube cooling efficiency, thereby achieving safe, stable, and low-emission combustion under a wide load range.

Contents of the invention

The technical problem to be solved by the present invention is to provide a gas turbine micro-mixed combustion chamber that can reduce nitrogen oxide emissions and improve flame tube cooling efficiency to achieve safe, stable, low-emission combustion under a wide load range in view of the shortcomings of the existing technology.

The technical problems to be solved by the present invention are achieved through the following technical solutions. The present invention is a gas turbine micro-mixed combustion chamber, which is characterized in that it includes an outer casing, an inner cavity is provided in the outer casing, and a combustion device is installed in the inner cavity. An air inlet cavity is formed between the outer wall of the combustion device and the inner wall of the outer shell, and the outer shell is provided with an air inlet communicating with the air inlet cavity;

The combustion device includes a burner and a flame tube. The burner is provided with a nozzle area. The flame tube is arranged on the outer periphery of the nozzle area. The outer shell is provided with a smoke outlet communicating with the flame tube; the nozzle area includes a flame tube. There is a duty class micro premix nozzle area in the middle and a main combustion stage micro premix nozzle area arranged around the periphery of the duty class micro premix nozzle area;

The burner is provided with a fuel supply area in the direction facing the nozzle area, and a shell covering the fuel supply area is installed on the outer periphery of the burner. The fuel supply area includes a duty class that provides gas to the micro premixed nozzle area of the duty class. The mixing chamber and the main combustion stage mixing chamber provide gas to the main combustion stage micro premixing nozzle area; the outer periphery of the duty class mixing chamber is provided with a swirling air inlet channel connected with the air inlet chamber, and the housing is provided with There is an air inlet connected to the air inlet channel, and a duty class fuel pipe that provides fuel is installed in the duty class mixing chamber; the housing is provided with several air intake chambers that are connected to the air intake chamber and supply air to the main combustion stage mixing chamber. The air inlet, the main combustion stage mixing chamber is equipped with a main combustion stage fuel pipe that provides fuel;

The air inlet cavity between the inner wall of the outer casing and the outer wall of the flame tube is provided with a swirling fin. The swirling fin is connected to the outer wall of the flame barrel. The channels have the same direction of rotation.

The technical problem to be solved by the present invention can also be further realized through the following technical solution: one fuel pipe is provided in the duty class, and at least two fuel pipes are provided in the main combustion stage.

The technical problems to be solved by the present invention can also be further realized through the following technical solutions: the duty class fuel pipes in the duty class mixing chamber have duty class fuel branch pipes evenly distributed in the circumferential direction at the outlet end, and the duty class fuel branch pipes are provided with fuel Exit hole.

The technical problem to be solved by the present invention can also be further realized through the following technical solution: main combustion stage fuel branch pipes are evenly distributed around the outlet end of the main combustion stage fuel pipe in the main combustion stage mixing chamber.

The technical problem to be solved by the present invention can also be further realized through the following technical solution: the air inlet holes are of equal size and are arranged densely in front and sparsely in back on the housing.

The technical problem to be solved by the present invention can also be further realized through the following technical solution: the cross-sectional area of the air inlet channel gradually decreases along the air inlet to the duty class mixing chamber.

The technical problem to be solved by the present invention can also be further realized through the following technical solution: the air inlet is provided on the outer shell close to the smoke outlet end.

Compared with the prior art, the beneficial effects of the present invention are:

(1) Compared with traditional burners, each micro-premixing tube of the main nozzle of this burner is relatively independent, and the modular array is expanded according to load requirements, so it has better scalability; the micro-mixing tube nozzles are all set at the millimeter level, and the micro-premixing tubes are The high flow rate in the mixing tube can effectively avoid backfire problems, shorten the residence time of high-temperature flue gas, and reduce nitrogen oxide emissions.

(2) Using a mixing chamber combined with a micro-mixing tube two-stage mixing mode, by mixing fuel and air at the millimeter scale, a more uniform fuel and air premix can be obtained compared to traditional swirl premix burners. Therefore, it can reduce The peak flame temperature during the combustion process can achieve better nitrogen oxide emission reduction effect; because the flame formed by the micro-mixing tube is relatively short and the temperature distribution is uniform, the length of the flame barrel of the combustion chamber can be greatly shortened.

(3) Multiple micro-premixed tubes are distributed in an array, so the ejected flame is relatively dispersed in the radial direction and the heat release is relatively uniform. At the same time, each main nozzle micro-mixed tube can adopt different structural solutions to achieve natural frequency differences and reduce It reduces the probability of thermo-acoustic coupling and can effectively avoid combustion instability problems.

(4) The swirling air intake structure of the duty class matches the flame tube fins, which is beneficial to improving the uniformity of fuel-air mixing, reducing emissions, and improving the combustion performance of the burner; it not only increases the turbulence intensity of the gas mixture but also increases the distance along the air path. , which is beneficial to flame stability, thereby broadening the stable operation boundary of the burner, increasing the heat exchange time between the flame tube wall and cooling air, and improving the cooling efficiency of the flame tube wall.

Description of the drawings

Figure 1 is a schematic diagram of the front cross-sectional structure of the combustion chamber;

Figure 2 is a schematic diagram of the main structure of the combustion chamber;

Figure 3 is a schematic diagram of the flame tube structure;

Figure 4 is a schematic cross-sectional view of the burner;

Figure 5 is a schematic structural diagram of a top view of the burner;

Figure 6 is a schematic diagram of the fuel pipe structure on duty;

Figure 7 is a schematic structural diagram of the main combustion stage fuel pipe.

In the picture: 1. Combustion device; 2. Outer shell; 21. Air inlet; 22. Air flow direction; 3. Flame tube; 31. Swirling fins; 32. Main combustion stage combustion area; 33. Duty class combustion area ; 34. Air intake chamber; 4. Burner; 41. Main combustion stage fuel pipe; 41A. Main combustion stage fuel inlet; 41B main combustion stage fuel branch pipe; 42. Duty class fuel pipe; 42A. Duty class fuel inlet; 42B. Duty class fuel branch pipe; 42C. Duty class fuel outlet; 43. Main combustion stage mixing chamber; 43A. Air inlet hole; 44. Duty class mixing chamber; 45. Main combustion stage micro premixing nozzle area; 46. Duty class Micro-premixed nozzle area; 47. Intake channel; 48. Fuel flow direction; 49. Mixed air flow direction.

Detailed ways

Specific technical solutions of the present invention are further described below to facilitate those skilled in the art to further understand the present invention, but do not constitute a limitation on their rights.

Referring to Figures 1 to 7, a gas turbine micro-mixed combustion chamber is characterized by including an outer casing, an inner cavity is provided in the outer casing, a combustion device is installed in the inner cavity, and air is formed between the outer wall of the combustion device and the inner wall of the outer casing. An air inlet chamber is provided with an air inlet connected to the air inlet chamber on the outer shell;

The combustion device includes a burner and a flame tube. The burner is provided with a nozzle area. The flame tube is arranged on the outer periphery of the nozzle area. The outer shell is provided with a smoke outlet communicating with the flame tube; the nozzle area includes a flame tube. There is a duty class micro premix nozzle area in the middle and a main combustion stage micro premix nozzle area arranged around the periphery of the duty class micro premix nozzle area;

The burner is provided with a fuel supply area in the direction facing the nozzle area, and a shell covering the fuel supply area is installed on the outer periphery of the burner. The fuel supply area includes a duty class that provides gas to the micro premixed nozzle area of the duty class. The mixing chamber and the main combustion stage mixing chamber provide gas to the main combustion stage micro premixing nozzle area; the outer periphery of the duty class mixing chamber is provided with a swirling air inlet channel connected with the air inlet chamber, and the housing is provided with There is an air inlet connected to the air inlet channel, and a duty class fuel pipe that provides fuel is installed in the duty class mixing chamber; the housing is provided with several air intake chambers that are connected to the air intake chamber and supply air to the main combustion stage mixing chamber. The air inlet, the main combustion stage mixing chamber is equipped with a main combustion stage fuel pipe that provides fuel;

The air inlet cavity between the inner wall of the outer casing and the outer wall of the flame tube is provided with a swirling fin. The swirling fin is connected to the outer wall of the flame barrel. The channels have the same direction of rotation.

There is one fuel pipe for the duty class and at least two fuel pipes for the main combustion stage.

The duty class fuel pipes in the duty class mixing chamber have duty class fuel branch pipes evenly distributed in the circumferential direction at the outlet end, and the duty class fuel branch pipes are respectively provided with fuel outlets.

Main combustion stage fuel branch pipes are evenly distributed around the outlet end of the main combustion stage fuel pipe in the main combustion stage mixing chamber.

The air inlet holes are of equal size and are arranged densely in front and sparsely in back on the housing.

The cross-sectional area of the air inlet channel gradually decreases along the air inlet to the duty class mixing chamber.

The air inlet is provided on the outer shell close to the smoke outlet end.

Referring to Figures 1-5, this embodiment discloses a gas turbine micro-mixed combustion chamber including: a combustion device 1, an outer shell 2, a flame tube 3, a swirling fin 31, a burner 4, a main combustion stage fuel pipe 41, a duty class The fuel pipe 42 , the main combustion stage mixing chamber 43 , the duty class mixing chamber 44 , the main combustion stage micro premixing nozzle area 45 , the duty class micro premixing nozzle area 46 , and the air intake passage 47 .

The outer casing 2 is provided with an air inlet 21. The compressed air flows into the outer casing 2 along the air flow direction 22 through the air inlet 21, and rotates upstream along the cavity in the swirling fin and flows into the air inlet chamber 34. Finally, the air flows into the main combustion stage mixing chamber 43 and the duty class mixing chamber 44 respectively through the air inlet hole 43A and the air inlet channel 47. The flame tube forms the main combustion stage combustion zone 32 in the area connected to the main combustion stage micro-premix nozzle area, and is connected with the duty class mixing chamber 43. The area where the stage micro-premixed nozzle areas are connected forms the value class combustion zone 33, and the value class combustion zone is arranged inside the main combustion stage combustion zone;

Referring to Figure 4-5, the burner 4 adopts the main combustion stage and the duty class staged combustion mode. The front end of the burner 4 is provided with two main combustion stage fuel pipes 41 and a duty class fuel pipe 42. The main combustion stage fuel pipe 41 is symmetrical. Distributed, the duty class fuel pipe 42 is located on the center line of the burner body 4 and communicates with the main combustion stage mixing chamber 43 and the duty class mixing chamber 44 respectively. Several main nozzle micro-premixing tubes are provided in the main combustion stage micro-premixing nozzle area 45, which are arranged in a staggered manner to reduce the impact of the air intake of the outer tube bundle on the air intake of the inner layer tube bundle. Several on-duty nozzle micro-premixing tubes are arranged in the area 46, and the number of layers is preferably 1 to 2; in this embodiment, it is 1 layer. The main combustion stage micro-premixing nozzle area 45 surrounds the on-duty stage micro-premixing nozzle area 46. , surrounding it 360°, which is conducive to flame transmission and flame stabilization. In addition, the outer wall surface of the main combustion stage mixing chamber is provided with air inlet holes 43A along the axial direction, and the spacing between the air inlet holes 43A gradually becomes larger along the axial direction; the duty class mixing chamber 44 is also evenly provided with three duty class mixing chambers in the circumferential direction. The air inlet channel 47 has a long inlet and outlet, and the inlet area of the air inlet channel 47 is smaller than the outlet area. The air inlet channel 47 is tilted, and the rotation direction is consistent with the air rotation direction, and is consistent with the flame tube. The duty class mixing chamber air inlet structure with the swirling fins 31 matching each other reduces the air flow loss on the one hand, and on the other hand, after the air enters the duty class mixing chamber 44 through the air inlet passage 47, it mixes with the fuel in the duty class mixing chamber 44. Rotary mixing not only improves the uniformity of fuel and air mixing, reduces emissions, but also increases the turbulence intensity of the mixture, improves the stability of the flame, and broadens the stable operation boundary of the burner;

Referring to Figures 6-7, fuel flows into the main combustion stage mixing chamber 43 and the duty class mixing chamber 44 respectively along the fuel flow direction 48 through the main combustion stage fuel inlet 41A and the duty class fuel inlet 42A. The fuel is evenly spread in the mixing chamber. And mixed with air, then flows into the main combustion stage micro premix nozzle area 45 and the duty stage micro premix nozzle area 46. After further mixing, it flows out of the burner body. Finally, the mixed premixed gas flows into the combustion area of the flame tube in the combustion chamber. , participating in combustion in the main combustion stage combustion zone 33 and the duty class combustion zone 34 respectively.

The main outlet pipe of the duty class fuel pipe 42 is provided with a duty class fuel branch pipe 42B. Preferably, there are at least two duty class fuel branch pipes 42B, and they are evenly arranged along the circumferential direction. In this embodiment, the number of duty class fuel branch pipes 42B is 3. The duty class fuel branch pipes 42B are also respectively provided with air outlets 42C. The number of air outlets 42C on each duty class fuel branch pipe 42B is equal and at least 2 are provided. In this embodiment, the number of air outlets is 2, and The sizes are equal, and the air outlet faces in the opposite direction to the rotation direction of the air inlet channel in the micro-premixing zone, thereby improving the uniformity of fuel and air mixing, thereby reducing the emission of nitrogen oxides.

Similarly, main combustion stage fuel branch pipes 41B are provided on the outlet pipe of the main combustion stage fuel pipe 41. In this embodiment, three main combustion stage fuel branch pipes 41B are evenly arranged in the circumferential direction on each main combustion stage fuel pipe 41. The fuel outlet direction is perpendicular to the axis of the main combustion stage fuel pipe, and finally enters the combustion zone of the flame tube along the direction of the mixture flow direction 49. The fuel flow direction is opposite to the air intake direction of the outer ring cavity, causing the fuel and air to conflict with each other, improving Main combustion stage fuel air mixing uniformity.

Although specific embodiments of the present invention have been described above, those skilled in the art will understand that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art can 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 (7)

1. A gas turbine micro-mixed combustion chamber, characterized in that: the combustion device is arranged in the outer shell, an air inlet cavity is formed between the outer wall of the combustion device and the inner wall of the outer shell, and an air inlet communicated with the air inlet cavity is formed in the outer shell;

the combustion device comprises a burner and a flame tube, a nozzle area is arranged on the burner, the flame tube is arranged at the periphery of the nozzle area, and a flue gas outlet communicated with the flame tube is arranged on the outer shell; the nozzle area comprises a duty micro-premixing nozzle area arranged in the middle and a main combustion micro-premixing nozzle area arranged at the periphery of the duty micro-premixing nozzle area;

the burner is provided with a fuel supply area in the direction opposite to the nozzle area, the periphery of the burner is provided with a shell covering the fuel supply area, and the fuel supply area comprises an on-duty mixing cavity for providing fuel gas for the on-duty micro-premixing nozzle area and a main combustion mixing cavity for providing fuel gas for the main combustion micro-premixing nozzle area; the periphery of the duty-level mixing cavity is provided with a rotary air inlet channel communicated with the air inlet cavity, the shell is provided with an air inlet communicated with the air inlet channel, and a duty-level fuel pipe for providing fuel is arranged in the duty-level mixing cavity; the shell is provided with a plurality of air inlets which are communicated with the air inlet cavity and supply air to the main combustion stage mixing cavity, and the main combustion stage mixing cavity is internally provided with a main combustion stage fuel pipe for providing fuel;

a convolution fin is arranged in an air inlet cavity between the inner wall of the outer shell and the outer wall of the flame tube, the convolution fin is connected with the outer wall of the flame tube, and the convolution fin has the same rotation direction as an air inlet channel at the periphery of the duty-level mixing cavity;

a plurality of main nozzle micro-premixing pipes are arranged in the main combustion stage micro-premixing nozzle area in a staggered manner; and a plurality of on-duty nozzle micro-premixing pipes are arranged in the on-duty stage micro-premixing nozzle area.

2. The gas turbine micro-mixed combustor as set forth in claim 1, wherein: the on-duty grade fuel pipe is provided with 1, and the main combustion grade fuel pipe is provided with 2 at least.

3. The gas turbine micro-mixed combustor as set forth in claim 1, wherein: the on-duty fuel pipes in the on-duty mixing cavity are circumferentially and uniformly distributed with on-duty fuel branch pipes at the outlet end, and the on-duty fuel branch pipes are provided with fuel outlet holes.

4. The gas turbine micro-mixed combustor as set forth in claim 1, wherein: main fuel branch pipes are circumferentially and uniformly distributed at the outlet end of the main fuel pipe in the main fuel mixing cavity.

5. The gas turbine micro-mixed combustor as set forth in claim 1, wherein: the size of the air inlet holes is equal and the air inlet holes are densely arranged on the shell.

6. The gas turbine micro-mixed combustor as set forth in claim 1, wherein: the cross-sectional area of the air inlet channel gradually decreases along the air inlet to the duty-class mixing cavity.

7. The gas turbine micro-mixed combustor as set forth in claim 1, wherein: the air inlet is arranged on the outer shell body and is close to the flue gas outlet end.