An adjustable fuel mixture and flue gas recirculation carbon-free burner

Abstract

The present application relates to the technical field of combustion, and 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 holder arranged at the center of the combustor, a hydrogen pipe surrounding the flame holder, and an ammonia pipe surrounding the hydrogen pipe, wherein the outer part of the ammonia pipe is provided with a primary air pipe, the top of the primary air pipe is provided with a venturi mixing pipe, the outer part of the venturi mixing pipe is provided with a flue gas inner circulation pipe, the flame holder, the hydrogen pipe, the ammonia pipe and the primary air pipe are coaxially arranged, the inner part of the ammonia pipe is provided with an inner cyclone, the inner part of the primary air pipe is provided with an outer cyclone, the wall between the ammonia pipe and the primary air pipe is provided with an inner cannula, and the bottom of the inner cannula is provided with an inner cannula adjusting device.The present application is advantageous in reducing the temperature of the central flame by wrapping the inner layer hydrogen flame with the outer layer ammonia flame and by circulating the flue gas, thereby reducing the generation of thermal NOx; and the mixing process of fuel and air is optimized by the flue gas inner circulation and the venturi pipe design.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of combustion technology, in particular to a carbon-free combustor capable of adjusting fuel mixing degree and flue gas recirculation. BACKGROUND

[0002] With the promotion of global energy structure transformation, hydrogen and ammonia, as a potential carbon-free fuel, have gradually attracted the attention of the industry and scientific research field. Hydrogen combustion only produces water vapor, which is environmentally friendly. However, hydrogen flame propagation speed is fast and easy to backfire, and the combustion temperature is high, which can easily produce a large amount of thermal NOx. Ammonia has a high hydrogen content and can be stored in a liquid state, making transportation convenient, so it is considered 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 combustor, which needs to effectively control the combustion process to avoid the generation of NOx and other pollutants.

[0003] Currently, the research on hydrogen / ammonia combustion technology mainly focuses on the development of traditional fuel mixed combustors. The traditional combustor usually has the following problems: the fuel and air are not uniformly mixed, the combustion is incomplete, and the generation of NOx is high; the combustor flame is unstable, and hydrogen combustion faces the risk of backfire, while the adjustment range of ammonia combustion is limited; in addition, the flame propagation speed of ammonia and hydrogen is quite different from that of conventional fuels, and the mixing conditions often need to be optimized to ensure stable combustion.

[0004] In view of these problems, there are several patent solutions in related technologies. For example, hydrogen combustion is achieved through micro-mixing technology (CN116182194B); the mixing of ammonia and air is optimized through multi-stage air duct and swirling structure to improve combustion efficiency (CN113623653B); a more efficient combustion process is achieved by adjusting the injection mode and position to reduce the generation of NOx (CN114893767B, CN112984508B).

[0005] Although there has been some technical progress, the existing technology still faces some bottlenecks, especially in the stable combustion of hydrogen / ammonia fuel, low NOx emission, and structure optimization of the combustor. Therefore, the present application proposes a carbon-free combustor capable of adjusting fuel mixing degree and flue gas recirculation, achieving net zero carbon dioxide emission, and effectively improving combustion stability and combustion efficiency while reducing NOx emission. SUMMARY

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

[0007] The present application is achieved by the following technical solutions:

[0008] The application discloses a carbon-free combustor capable of adjusting fuel mixing degree and flue gas recirculation, which comprises a flame holder arranged in the center of the combustor, a hydrogen pipe surrounding the flame holder and an ammonia pipe surrounding the hydrogen pipe, wherein an air pipe is arranged outside the ammonia pipe, a venturi mixing pipe is arranged at the top of the air pipe, a flue gas internal recirculation pipe is arranged outside the venturi mixing pipe, the flame holder, the hydrogen pipe, the ammonia pipe and the air pipe are coaxially arranged, an internal swirler is arranged inside the ammonia pipe, an external swirler is arranged inside the air pipe, an internal insertion pipe is arranged on the wall between the ammonia pipe and the air pipe, and an internal insertion pipe adjusting device is arranged at the bottom of the internal insertion pipe.

[0009] Preferably, the top of the internal recirculation pipe is provided with a flue gas recirculation adjusting device.

[0010] Preferably, the side wall of the combustion chamber is provided with an adjustable staged air pipe, and the adjustable staged air pipe is uniformly arranged along the circumference of the combustor.

[0011] Preferably, the internal insertion pipe adjusting device is provided with a rotary push rod, the disc has an irregular height distribution, and the adjusting roller interacts with the disc to finely adjust the height of the internal insertion pipe.

[0012] Preferably, the flue gas recirculation adjusting device is provided with a sensor, and the opening controller is linked with the sensor.

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

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

[0015] 1. Low NOx emission: the main combustion zone is kept in a fuel-rich state through air staging, which can reduce the fuel-type NOx generation of ammonia; the mixing degree of ammonia and air can be adjusted to optimize the NOx emission during the operation of the combustor; the outer ammonia flame wraps the inner hydrogen flame, and the flue gas recirculation is conducive to reducing the temperature of the central flame, thereby reducing the thermal-type NOx generation.

[0016] 2. Improved flame stability and combustion efficiency: the central hydrogen flame improves the flame stability; the flue gas internal recirculation and the venturi pipe design optimize the mixing process of fuel and air, and the preheating effect of the circulating flue gas is conducive to improving the flame stability and the combustion efficiency and avoiding the problem of flameout at low load or variable load.

[0017] 3. Prevention of thermal-acoustic instability: the flue gas internal recirculation and the adjustable internal insertion pipe can make the flame heat release more dispersed, thereby reducing the risk of thermal-acoustic instability. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a structural schematic diagram of the application.

[0019] Figure 2 Structure diagram of the cooperation between the inner pipe adjusting roller and the disc in the present application.

[0020] Figure 3 Structure diagram of the cooperation between the inner pipe adjusting roller and the disc in the present application.

[0021] Figure 4 Internal structure diagram of the flue gas circulation adjusting device in the present application.

[0022] Figure 5 Structure diagram of the cooperation between the nozzle angle controller and the control line in the present application.

[0023] Label explanation: 1, flame holder, 2, hydrogen pipe, 3, ammonia pipe, 4, inner swirler, 5, inner pipe, 6, inner pipe adjusting device, 7, primary air pipe, 8, outer swirler, 9, venturi mixing pipe, 10, flue gas inner circulation pipe, 11, flue gas circulation adjusting device, 12, adjustable staged air pipe, 13, combustion chamber, 14, push rod, 15, disc, 16, inner pipe adjusting roller, 17, connecting device, 18, spring, 19, fixed plate, 20, sensor, 21, opening controller, 22, nozzle angle controller, 23, control line. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0025] Please refer to Figures 1-5 The present application provides a technical solution:

[0026] One of the purposes of the present application is to provide a carbon-free burner capable of adjusting 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 at the top of the primary air pipe 7, and a flue gas inner 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 deliver hydrogen to the furnace, the ammonia pipe 3 is used to deliver ammonia to the furnace, and the primary air pipe 7 is used to provide 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. The ammonia pipe 3 is internally provided with an inner swirler 4 for deflecting the airflow in the ammonia pipe 3 and forming a rotating airflow, which is conducive to promoting the mixing of fuel and air in the combustion chamber; the primary air pipe 7 is internally provided with an outer swirler for deflecting the primary air into a rotating airflow. The upper part of the wall between the ammonia pipe 3 and the primary air pipe 7 is provided with an adjustable height inner pipe 5, and the bottom of the adjustable height inner pipe 5 is provided with an inner pipe adjusting device 6, which realizes the up-down adjustment of the adjustable height inner pipe 5 along the burner axis.

[0029] These parts work together to solve practical problems:

[0030] When the adjustable height inner pipe 5 is at the highest position, the ammonia gas enters the combustion chamber 13 independently without being premixed with the primary air in the primary air pipe 7; when the adjustable height inner pipe 5 is at the lowest position, the ammonia gas is mixed with the primary air in the primary air pipe 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 largest; when the adjustable height inner pipe 5 is at the intermediate position, the mixing length can change with the height of the adjustable height inner pipe 5, and finally the mixing degree of ammonia gas with primary air and recirculated flue gas can be adjusted.

[0031] The cross-sectional area of the Venturi mixing pipe 9 changes along the height, first narrowing and then expanding, and the narrowing section at the bottom of the Venturi mixing pipe 9 realizes the acceleration of the fluid in the channel, promoting the sufficient mixing of the primary air with the recirculated flue gas and the ammonia gas (when the adjustable height inner pipe 5 is not at the top position), while also preventing backfire. The primary air flowing through the Venturi mixing pipe 9 can induce the flue gas in the flue gas internal circulation pipe 10, increasing the amount of flue gas recirculation.

[0032] The top of the flue gas internal circulation pipe is provided with a flue gas circulation adjusting device 11 to realize the adjustable annular inlet area of the flue gas internal circulation pipe. When the opening area of the flue gas circulation adjusting device 11 increases, the amount of flue gas mixed with air entering the flue gas internal circulation pipe 10 increases; when the opening area of the flue gas circulation device 11 decreases, the flue gas flow into the flue gas internal circulation pipe 10 decreases, thereby realizing the adjustment of flue gas recirculation. By adjusting the flue gas recirculation, the mixing degree of flue gas with primary air in the primary air pipe 7 can be controlled, and the primary air and ammonia gas can be preheated, thereby increasing the flame stability. By flue gas circulation, the temperature level of the main combustion zone can be reduced, thereby reducing the generation of thermal NOx.

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

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

[0035] The inner tube adjusting device is provided with a rotary push rod 14 for driving the height adjustment of the inner tube; a disc 15 with irregular height distribution for adjusting the position of the adjusting roller 16; the adjusting roller 16 interacts with the disc 15 to realize fine adjustment of the height of the inner tube; the connecting device 17 is linked with the adjusting roller 16, and when the roller 16 is lifted, the connecting device rises accordingly; the spring 18 cooperates with the fixed 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 under the action of the disc 15, and at this time, the connecting device linked with the adjusting roller 16 also rises. Through the cooperation of the spring 18 and the fixed plate 19, the elastic force is used to enhance the connection between the adjusting roller and the inner tube, so as to realize flexible adjustment of the height of the inner tube. The stability and accuracy of the inner tube during the adjustment process are ensured, and then the mixing ratio of NH3, air and flue gas can be accurately controlled, the combustion effect is optimized, and environmental pollution is reduced.

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

[0037] The adjustable staged air pipe is provided with a nozzle angle controller 22 for receiving a set value and adjusting the angle of the nozzle according to the set value; a control line 23 for transmitting the action instruction of the nozzle angle controller 22 to the nozzle. When the staged adjustment of the air is needed, the operator controls the nozzle angle controller 22 by setting a specific value; after the nozzle angle controller 22 receives the set value, the action instruction is transmitted through the control line 23 to realize the accurate control of the angle of the nozzle; by adjusting the angle of the nozzle, the staged air device can effectively change the direction and speed of the air flow, so as to realize the optimization of the air staging.

[0038] The specific embodiment is only an explanation of the present application, and is not a limitation of the present application. Those skilled in the art can make modifications to the embodiment without creative contribution according to the needs after reading the specification, and as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A carbon-free combustor with adjustable fuel mixture and flue gas recirculation, comprising a flame holder (1) disposed in the center of a combustion chamber (13), a hydrogen tube (2) surrounding the flame holder (1), and an ammonia tube (3) surrounding the hydrogen tube (2), characterized in that: The ammonia pipe (3) is externally provided with a primary air pipe (7), the primary air pipe (7) is provided with a Venturi mixing pipe (9) near one end of the combustion chamber (13), the Venturi mixing pipe (9) is externally provided with a flue gas internal circulation pipe (10), the flue gas internal circulation pipe (10) is provided with a flue gas circulation adjusting device (11) near one end of the combustion chamber (13), the flame holder (1), the hydrogen pipe (2), the ammonia pipe (3) and the primary air pipe (7) are coaxially arranged, the ammonia pipe (3) is internally provided with an internal swirler (4), the primary air pipe (7) is internally provided with an external swirler (8), the wall between the ammonia pipe (3) and the primary air pipe (7) is provided with an internal pipe (5) towards one end of the combustion chamber (13), the bottom of the internal pipe (5) is provided with an internal pipe adjusting device (6), the internal pipe adjusting device (6) is provided with a push rod (14), the disc (15) has irregular height distribution, the internal pipe adjusting roller (16) interacts with the disc (15) to finely adjust the height of the internal pipe (5).

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

3. A carbon-free combustor with adjustable fuel mixture and flue gas recirculation according to claim 1, characterized in that: The flue gas circulation adjusting device (11) is provided with a sensor (20), and an opening controller (21) is linked with the sensor (20).

4. The adjustable fuel mixture and flue gas recirculation carbon-free combustor of claim 2, wherein: The adjustable staged air pipe (12) is provided with a nozzle angle controller (22).

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