Carbon-free burner capable of adjusting fuel mixing degree and flue gas recirculation

Abstract

The invention relates to the technical field of combustion, aims to solve the problem of combustion efficiency, and discloses a carbon-free combustor capable of adjusting fuel mixing degree and flue gas recirculation, which comprises a flame retainer arranged at the center of the combustor, a hydrogen pipe surrounding the flame retainer and an ammonia pipe surrounding the hydrogen pipe, a primary air pipe is arranged outside the ammonia pipe, and a secondary air pipe is arranged outside the primary air pipe. A Venturi mixing pipe is arranged at the top of the primary air pipe, a flue gas inner circulating pipe is arranged outside the Venturi mixing pipe, the flame retainer, the hydrogen pipe, the ammonia pipe and the primary air pipe are coaxially arranged, an inner swirler is arranged in the ammonia pipe, an outer swirler is arranged in the primary air pipe, an inner inserting pipe is arranged on the wall between the ammonia pipe and the primary air pipe, and an outer inserting pipe is arranged on the wall between the outer swirler and the primary air pipe. An inner inserting pipe adjusting device is arranged at the bottom of the inner inserting pipe. The inner-layer hydrogen flame is wrapped by the outer-layer ammonia flame, and the flue gas is circulated, so that the temperature of the central flame is reduced, and the generation of thermal NOx is reduced; and the mixing process of fuel and air is optimized through flue gas internal circulation and Venturi tube design.

Description

Technical Field

[0001] The invention relates to the field of combustion technology, in particular to a carbon-free burner capable of adjusting fuel mixing degree and flue gas recirculation. Background Art

[0002] As the global energy structure transformation progresses, hydrogen and ammonia, as carbon-free fuels with great potential, have gradually attracted the attention of the industry and scientific research fields. Hydrogen only produces water vapor after combustion, which is environmentally friendly. However, the hydrogen flame propagates quickly and is prone to backfire, and the high combustion temperature easily produces a large amount of thermal NOx. Ammonia has a high hydrogen content and can be stored in a liquid state, which is convenient for transportation. Therefore, it is regarded as an important choice to replace traditional fossil fuels. However, there are some technical challenges in the combustion of carbon-free fuels, especially in the design of the burner, which requires effective control of the combustion process to avoid the generation of pollutants such as NOx.

[0003] At present, the current hydrogen / ammonia combustion technology is mainly focused on the research and development of traditional fuel blending burners. Traditional burners usually have the following problems: uneven mixing of fuel and air, incomplete combustion, high NOx generation; unstable burner flames, hydrogen-blended combustion faces the risk of flashback, and the adjustment range of ammonia-blended combustion is limited; in addition, the flame propagation speed of ammonia and hydrogen is quite different from that of conventional fuels, and it is often necessary to optimize the mixing conditions to ensure their stable combustion.

[0004] In response to these problems, there are several patent solutions for the development of related technologies. For example, hydrogen combustion is achieved through micro-mixing technology (CN116182194B); multi-stage air ducts and swirl structures are used to optimize the mixing of ammonia and air to improve combustion efficiency (CN113623653B); and a more efficient combustion process is achieved by adjusting the injection method and position to reduce the generation of NOx (CN114893767B, CN112984508B).

[0005] Although there have been certain technical progresses, the existing technology still faces some bottlenecks, especially in the stable combustion of hydrogen / ammonia fuels, low NOx emissions and structural optimization of burners. To this end, the present invention proposes a carbon-free burner with adjustable fuel mixing and flue gas recirculation to achieve net zero carbon dioxide emissions, and can effectively improve combustion stability and combustion efficiency, while reducing NOx emissions. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies of the prior art and provide a carbon-free burner capable of adjusting the fuel mixing degree and flue gas recirculation.

[0007] The present invention is achieved through the following technical solutions:

[0008] A carbon-free burner with adjustable fuel mixing degree and flue gas recirculation comprises a flame holder arranged at the center of the burner, a hydrogen pipe surrounding the flame holder and an ammonia pipe surrounding the hydrogen pipe, a primary air duct is arranged outside the ammonia pipe, a venturi mixing pipe is arranged on the top of the primary air duct, a flue gas internal circulation pipe is arranged outside the venturi mixing pipe, the flame holder, hydrogen pipe, ammonia pipe and primary air duct are arranged coaxially, an inner swirler is arranged inside the ammonia pipe, an outer swirler is arranged inside the primary air duct, an inner insert pipe is arranged on the wall between the ammonia pipe and the primary air duct, and an inner insert pipe adjustment device is arranged at the bottom of the inner insert pipe.

[0009] Preferably, a flue gas circulation regulating device is provided on the top of the inner circulation pipe.

[0010] Preferably, the combustion chamber side wall is provided with adjustable graded air pipes, and the adjustable graded air pipes are evenly arranged along the circumference of the burner.

[0011] Preferably, the inner tube adjustment device is provided with a rotating push rod, the disc has an irregular height distribution, and the adjustment roller interacts with the disc to finely adjust the height of the inner tube.

[0012] Preferably, the flue gas circulation regulating device is provided with a sensor, and the opening controller is linked to the sensor.

[0013] Preferably, the adjustable graded air pipe is provided with a nozzle angle controller.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. Achieve low NOx emissions: Maintaining a rich combustion state in the main combustion zone through air staging can reduce the generation of fuel-type NOx from ammonia; NOx emissions during burner operation can be optimized by adjusting the degree of mixing of ammonia and air; the outer ammonia flame wrapping the inner hydrogen flame and flue gas circulation can help reduce the temperature of the center flame, thereby reducing thermal NOx generation.

[0016] 2. Improve flame stability and combustion efficiency: The central hydrogen flame improves flame stability; the mixing process of fuel and air is optimized through internal flue gas circulation and Venturi tube design. At the same time, the preheating effect of circulating flue gas is conducive to improving flame stability and combustion efficiency, avoiding flameout problems at low load or variable load.

[0017] 3. Preventing thermoacoustic instabilities: Flue gas internal circulation and adjustable internal inserts can make the flame heat release more dispersed, thereby reducing the risk of thermoacoustic instabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention.

[0019] Figure 2 It is a schematic diagram of the structure of the cooperation between the inner tube adjustment roller and the disc of the present invention.

[0020] Figure 3 It is a side view of the cooperation between the inner tube adjustment roller and the disc of the present invention.

[0021] Figure 4 It is an internal schematic diagram of the flue gas circulation regulating device of the present invention.

[0022] Figure 5 It is a schematic diagram of the coordination between the nozzle angle controller and the control line of the present invention.

[0023] Explanation of reference numbers: 1. flame holder, 2. hydrogen pipe, 3. ammonia pipe, 4. internal cyclone, 5. internal insert pipe, 6. internal insert pipe regulating device, 7. primary air duct, 8. external cyclone, 9. venturi mixing tube, 10. flue gas internal circulation pipe, 11. flue gas circulation regulating device, 12. adjustable graded air pipe, 13. combustion chamber, 14. push rod, 15. disc, 16. internal insert pipe regulating roller, 17. connecting device, 18. spring, 19. fixing plate, 20. sensor, 21. opening controller, 22. nozzle angle controller, 23. control line. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1-5 , the present invention provides a technical solution:

[0026] One of the purposes of the present invention is to provide a carbon-free burner capable of adjusting the fuel mixing degree and flue gas recirculation, which comprises: a flame holder 1 arranged at the central axis of the burner, a hydrogen pipe 2 surrounding the flame holder 1, an ammonia pipe 3 surrounding the hydrogen pipe 2, a primary air pipe 7 arranged outside the ammonia pipe 3, a venturi mixing pipe 9 arranged on the top of the primary air pipe 7, and a flue gas internal circulation pipe 10 arranged outside the venturi mixing pipe 9. The flame holder 1 is used to stabilize the flame, the hydrogen pipe 2 is used to transport hydrogen to the furnace, the ammonia pipe 3 is used to transport ammonia to the furnace, and the primary air pipe 7 is used to provide the primary air required for combustion.

[0027] The positional relationship and connection relationship of these parts are as follows:

[0028] The flame holder 1, hydrogen pipe 2, ammonia pipe 3 and primary air pipe 7 are coaxially arranged. An inner swirler 4 is arranged inside the ammonia pipe 3 to deflect the airflow inside the ammonia pipe 3 and form a rotating airflow, which is conducive to promoting the mixing of fuel and air in the combustion chamber; an outer swirler is arranged inside the primary air pipe 7 to deflect the primary air into a rotating airflow. An adjustable height inner insert pipe 5 is arranged at the upper part of the wall between the ammonia pipe 3 and the primary air pipe 7, and an inner insert pipe adjustment device 6 is arranged at the bottom of the adjustable height inner insert pipe 5 to achieve the adjustment of the adjustable height inner insert pipe 5 up and down along the axial direction of the burner.

[0029] How these parts work together to solve real problems:

[0030] When the adjustable height inner tube 5 is located at the highest point, ammonia enters the combustion chamber 13 independently without being pre-mixed with the primary air in the primary air duct 7; when the adjustable height inner tube 5 is located at the lowest point, ammonia is mixed with the primary air in the primary air duct 7 and the flue gas in the flue gas internal circulation pipe 10 before entering the combustion chamber 13. At this time, the mixing distance is the longest and the mixing degree is the greatest; when the adjustable height inner tube 5 is located in the middle position, the mixing length can change with the height of the adjustable height inner tube 5, and finally the mixing degree of ammonia, primary air and recycled flue gas can be adjusted.

[0031] The cross-sectional area of ​​the Venturi mixing tube 9 changes along the height by first contracting and then expanding. The contraction section at the bottom of the Venturi mixing tube 9 accelerates the fluid in the channel, promotes the full mixing of the primary air with the recirculated flue gas and ammonia (when the height-adjustable inner insert tube 5 is not at the top position), and can also prevent flashback. When the primary air flows through the Venturi mixing tube 9, it can draw the flue gas in the flue gas internal circulation tube 10, thereby increasing the flue gas recirculation amount.

[0032] A flue gas circulation regulating device 11 is provided at the top of the flue gas internal circulation pipe to achieve adjustable annular inlet area entering the flue gas internal circulation pipe. When the opening area of ​​the flue gas circulation regulating device 11 increases, the amount of flue gas entering the flue gas internal circulation pipe 10 and mixing with the air increases; when the opening area of ​​the flue gas circulation device 11 decreases, the flue gas flow entering the flue gas internal circulation pipe 10 decreases, thereby achieving the regulation of flue gas recirculation. By adjusting the flue gas recirculation, the degree of mixing of the flue gas and the primary air in the primary air duct 7 can be controlled, and at the same time, the primary air and ammonia can be preheated, thereby increasing the flame stability. The temperature level of the main combustion zone can be reduced by flue gas circulation, thereby reducing the generation of thermal NOx.

[0033] The flue gas circulation regulating device 11 and the height-adjustable inner tube 5 can regulate the distribution of heat release during the operation of the burner, thereby reducing the risk of combustion instability.

[0034] The combustion chamber side wall is provided with an adjustable air classification tube 12 for conveying the secondary air required for combustion. The adjustable air classification tubes 12 are evenly arranged along the circumference of the burner, and the number of arrangement can be selected as 6 or 8; the adjustable air classification tube 12 can adjust the nozzle angle, thereby adjusting the angle of the secondary air entering the burner. During the operation of the burner, primary air is supplied to the furnace through the primary air duct 7, and the primary air supply is lower than the theoretical air amount required for complete combustion, so that the flame is in a rich combustion state in the main combustion zone, thereby inhibiting the conversion of ammonia into NOx; the secondary air required for combustion is supplied through the adjustable classification air tube, and the angle of the secondary air entering the combustion chamber can be adjusted according to the fuel ratio and thermal power of the actual operation of the burner.

[0035] The inner tube adjustment device is provided with a rotating push rod 14 for driving the height adjustment of the inner tube; a disc 15 having an irregular height distribution for adjusting the position of a roller 16; an adjusting roller 16 interacting with the disc 15 to achieve fine adjustment of the height of the inner tube; a connecting device 17 linked with the adjusting roller 16, and when the roller 16 is lifted up, the connecting device rises accordingly; a spring 18 cooperates with a fixing plate 19 to provide elastic force to enhance the connection between the adjusting roller and the inner tube. By rotating the push rod 14, the disc 15 positions the adjusting roller 16 according to its irregular height distribution. The adjusting roller 16 is lifted up under the action of the disc 15, and at this time, the connecting device linked with the adjusting roller 16 also rises accordingly. Through the cooperation of the spring 18 and the fixing plate 19, the connection between the adjusting roller and the inner tube is enhanced by the elastic force, thereby achieving flexible adjustment of the height of the inner tube. The stability and accuracy of the inner tube during the adjustment process are ensured, so that the mixing ratio of NH3, air and flue gas can be accurately controlled, the combustion effect can be optimized and environmental pollution can be reduced.

[0036] The flue gas circulation regulating device is provided with a sensor 20 for detecting specific parameters in the system and providing corresponding numerical signals; an opening controller 21 is linked with the sensor 20 to adjust the opening according to the numerical signal provided by the sensor 21. When the value detected by the sensor 20 enters the preset control range, the sensor 20 transmits the signal to the opening controller 21; after receiving the signal from the sensor 20, the opening controller 21 acts according to the preset program to adjust the opening of the system so that the detection value of the sensor 20 exits the control range; once the detection value of the sensor 20 reaches and remains in the non-control range, the opening controller 21 immediately stops the action and returns to the fully open state to ensure that the system operates in the optimal state.

[0037] The adjustable graded air pipe is provided with a nozzle angle controller 22 for receiving a set value and adjusting the angle of the nozzle accordingly; a control line 23 for transmitting the action command of the nozzle angle controller 22 to the nozzle. When the air needs to be graded, the operator controls the nozzle angle controller 22 by setting a specific value; after receiving the set value, the nozzle angle controller 22 transmits the action command through the control line 23 to achieve precise control of the nozzle angle; by adjusting the nozzle angle, the graded air device can effectively change the direction and speed of air flow, thereby achieving optimization of air classification.

[0038] This specific embodiment is only an explanation of the present invention, not a limitation of the present invention. After reading this specification, those skilled in the art can make non-creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A carbon-free burner capable of adjusting fuel mixing and flue gas recirculation, comprising a flame holder (1) arranged at the center of a combustion chamber (13), a hydrogen pipe (2) surrounding the flame holder (1), and an ammonia pipe (3) surrounding the hydrogen pipe (2), characterized in that: A primary air duct (7) is arranged outside the ammonia pipe (3), a venturi mixing pipe (9) is arranged at the top of the primary air duct (7), a flue gas internal circulation pipe (10) is arranged outside the venturi mixing pipe (9), a flame holder (1), a hydrogen pipe (2), an ammonia pipe (3) and the primary air duct (7) are coaxially arranged, an internal cyclone (4) is arranged inside the ammonia pipe (3), an external cyclone (8) is arranged inside the primary air duct (7), an inner insert pipe (5) is arranged on the wall between the ammonia pipe (3) and the primary air duct (7), and an inner insert pipe adjustment device (6) is arranged at the bottom of the inner insert pipe (5).

2. A carbon-free burner with adjustable fuel mixing and flue gas recirculation according to claim 1, characterized in that: A flue gas circulation regulating device (11) is provided on the top of the flue gas internal circulation pipe (10).

3. A carbon-free burner with adjustable fuel mixing and flue gas recirculation according to claim 1, characterized in that: The side wall of the combustion chamber (13) is provided with an adjustable graded air pipe (12), and the adjustable graded air pipe (12) is evenly arranged along the circumference of the combustion chamber (13).

4. A carbon-free burner with adjustable fuel mixing and flue gas recirculation according to claim 1, characterized in that: The inner tube adjustment device (6) is provided with a push rod (14), the disc (15) has an irregular height distribution, and the inner tube adjustment roller (16) interacts with the disc (15) to finely adjust the height of the inner tube (5).

5. A carbon-free burner with adjustable fuel mixing and flue gas recirculation according to claim 2, characterized in that: The flue gas circulation regulating device (11) is provided with a sensor (20), and the opening controller (21) is linked to the sensor (20).

6. A carbon-free burner with adjustable fuel mixing and flue gas recirculation according to claim 3, characterized in that: The adjustable graded air pipe (12) is provided with a nozzle angle controller (22).

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