Hydrogen-ammonia mixed low-nitrogen burner

Abstract

The invention provides a hydrogen-ammonia mixed low-nitrogen combustor, and belongs to the technical field of combustors. The technical problem of gas combustion with hydrogen and ammonia serving as fuel at present is solved, and the problems that due to the fact that the ammonia combustion reaction activity is poor, the hydrogen combustion speed is high, a nozzle is burnt by tempering, and the NOx emission concentration is high are solved. The device comprises a hydrogen introduction pipe, an ammonia gas introduction pipe, a fuel gas mixer, an annular header, ammonia gas branch pipes and ammonia gas nozzles. The hydrogen introducing pipe comprises a central hydrogen pipe and a combustion-supporting hydrogen pipe, the outlet end of the central hydrogen pipe is located in the annular collecting box, the input end of the combustion-supporting hydrogen pipe is connected with the central hydrogen pipe, the output end of the combustion-supporting hydrogen pipe is connected with the fuel gas mixer, and the output end of the ammonia introducing pipe is connected with the fuel gas mixer; the output end of the gas mixer is connected with an annular header, the annular header is connected with a plurality of ammonia branch pipes, the ammonia branch pipes are annularly arranged, and ammonia nozzles are arranged at the outlet ends of the ammonia branch pipes. The device is mainly used for hydrogen-ammonia mixed combustion.

Description

Technical Field

[0001] The invention belongs to the technical field of burners, and in particular relates to a hydrogen-ammonia mixed low-nitrogen burner. Background Art

[0002] The widespread use of traditional fossil energy and its non-renewable nature have brought about increasingly serious environmental pollution, greenhouse effects and energy crises. Energy depletion and climate deterioration have become two major challenges facing mankind in the 21st century. In order to fundamentally solve the resource constraints and environmental problems facing the whole society, China has proposed carbon peak and carbon neutrality goals and timetables. The realization of the dual carbon goals requires the participation of a wide range of carbon reduction technologies. The use of carbon-free fuels to replace traditional fossil energy in the combustion field is an important technical means.

[0003] Hydrogen is considered to be one of the most ideal clean energy sources. Hydrogen fuel has the characteristics of good combustion, low ignition energy, and fast combustion reaction speed. Water is the only product of complete combustion of hydrogen. However, hydrogen combustion also has many disadvantages, such as low volume energy density and the generation of thermal nitrogen oxides NO due to high combustion temperature. x Pollutants, too fast hydrogen combustion reaction rate may cause pre-ignition, flashback and other problems, which limit the promotion and use of pure hydrogen fuel. Ammonia is a low-cost chemical raw material. When it is completely burned, the products are only nitrogen and water. Ammonia has a high volume energy density, does not produce CO2 when burned, is easy to compress, liquefy and store, and has low storage and transportation costs. There are also some obvious disadvantages to using ammonia as a fuel. The laminar combustion flame propagation speed of pure ammonia fuel is low, it has a relatively high auto-ignition temperature and requires a higher ignition energy, and the flammable limit of ammonia is narrow. The volume fraction of the flammable limit in the air is 15.5%-27%. It is difficult to achieve complete combustion of pure ammonia. Moreover, since ammonia itself contains nitrogen, the potential nitrogen oxides NO in the combustion products of ammonia x The emission content is high.

[0004] Ammonia and hydrogen have certain deficiencies and disadvantages when used alone, but using these two fuels in combination without introducing carbon-containing fuels is a better technical route choice, which combines the advantages and disadvantages of ammonia and hydrogen fuels to achieve efficient and clean combustion while zero carbon emissions. At present, there are few known types of ammonia hydrogen gas burners, and they have not completely solved the problem of efficient combustion of fuels and reduction of nitrogen oxides NO. x The coordination problem between emissions. To address the problem of poor combustion reactivity of ammonia, the commonly used technical method is to add a more reactive combustible gas, such as natural gas, hydrogen, etc., to ammonia. The existing burner design focuses on organizing combustion and fails to combine a variety of combustion technologies. It has not yet effectively controlled nitrogen oxides NO. x Emission value. Summary of the invention

[0005] In view of this, the present invention aims to propose a hydrogen-ammonia mixed low-nitrogen burner to solve a series of technical problems in the current combustion of gas using hydrogen and ammonia as fuel, such as: poor combustion reaction activity of ammonia, fast combustion reaction rate of hydrogen leading to backfire and burning of the nozzle, and high NOx emission concentration.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A hydrogen-ammonia mixed low-nitrogen burner comprises a hydrogen inlet pipe, an ammonia inlet pipe, a gas mixer, an annular header, an ammonia branch pipe and an ammonia nozzle. The hydrogen inlet pipe comprises a central hydrogen pipe and a combustion-supporting hydrogen pipe, the input end of the combustion-supporting hydrogen pipe is connected to the central hydrogen pipe, and the output end is connected to the gas mixer, the output end of the ammonia inlet pipe is connected to the gas mixer, and the output end of the gas mixer is connected to the annular header, the annular header is connected to multiple ammonia branch pipes, the multiple ammonia branch pipes are arranged in an annular shape, and the outlet end of the ammonia branch pipe is provided with an ammonia nozzle.

[0008] Furthermore, a central hydrogen regulating valve is installed on the central hydrogen pipe, and a combustion-supporting hydrogen regulating valve is installed on the combustion-supporting hydrogen pipe.

[0009] Furthermore, the outlet end of the central hydrogen pipe is connected to a plurality of central hydrogen branch pipes, and the central hydrogen branch pipes are connected to the central hydrogen nozzle.

[0010] Furthermore, a fuel gas panel is provided at the end of the central hydrogen nozzle and the ammonia nozzle.

[0011] Furthermore, a gas flame stabilizer is provided on the outside of the gas panel, and the radial expansion angle of the gas flame stabilizer is 15°-25°.

[0012] Furthermore, an ammonia regulating valve is installed on the ammonia inlet pipe.

[0013] Furthermore, a primary air inlet and a secondary air inlet are sequentially provided outside the burner gas pipeline, the primary air inlet is connected to the primary air annular cavity, the primary air passes through the primary air inlet and is blown into the furnace through the primary air annular cavity, and the secondary air inlet is connected to the secondary air annular cavity, the secondary air passes through the secondary air inlet and is blown into the furnace through the secondary air annular cavity.

[0014] Furthermore, a primary air swirl blade is installed in the primary air ring cavity, and the blade of the primary air swirl blade is deflected 30°-60° from the axial direction.

[0015] Furthermore, a secondary air swirl blade is provided in the secondary air annular cavity, the blade of the secondary air swirl blade is deflected 30°-60° from the axial direction, and the secondary air swirl blade is connected to a swirl blade adjustment mechanism.

[0016] Furthermore, the front end of the secondary air ring cavity is provided with a flange, the corresponding radial expansion angle is 15°-25°, and the side end of the secondary air ring cavity is provided with a flange.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The combustion organization mode of the present invention promotes the combustion of ammonia. Adding an appropriate amount of hydrogen to ammonia can increase the combustion reaction rate of ammonia fuel. The outer layer of the gas jet is a mixed gas of ammonia and hydrogen. The flammability of the mixed fuel is higher than that of pure ammonia fuel. The combustion organization forms a reflow zone outside the burner nozzle. The reflow zone can draw high-temperature flue gas back to the root of the ammonia-hydrogen mixed gas jet to heat the ammonia-hydrogen mixed gas. The high temperature condition can promote the ignition and combustion of the ammonia-hydrogen mixed gas. Finally, the burnout rate of ammonia is high and there is no ammonia escape phenomenon.

[0019] 2. The present invention effectively reduces the fuel-type NO in ammonia combustion x Pollutant generation: Ammonia burns in a low-oxygen environment, and the high-temperature flame environment can promote the thermal decomposition reaction rate of ammonia. Ammonia is consumed quickly. In a low-oxygen environment, fuel-type nitrogen oxides NO are generated by the combustion of ammonia. x Ammonia can also be used as a reducing agent for NOx, converting the generated nitrogen oxides NO x Reducing to nitrogen solves the problem of high concentration of fuel-type NO in the combustion process of ammonia. x Technical difficulties in emission potential.

[0020] 3. The structural design of the present invention is simple, the combustion process is adjustable and controllable, the ammonia-hydrogen mixing ratio of the outer fuel gas can be adjusted by using a valve group, and the swirl blade adjustment mechanism of the secondary air can adjust the swirl intensity of the secondary air, thereby changing the flow field morphology.

[0021] 4. The present invention controls the combustion process of hydrogen and will not cause burnout of the burner. Since the excessively fast combustion reaction rate of hydrogen may lead to problems such as premature combustion and flashback, the present invention adopts a diffusion combustion method, sets hydrogen in the inner layer of the gas jet, delays the air distribution of hydrogen, and controls the hydrogen combustion area to maintain an appropriate distance from the burner.

[0022] 5. The present invention uses ammonia and hydrogen as fuels in combination and does not introduce carbon-containing fuels, making comprehensive use of the advantages and disadvantages of ammonia and hydrogen fuels to achieve efficient and clean combustion with zero carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 is a schematic structural diagram of a hydrogen-ammonia hybrid low-nitrogen burner according to the present invention;

[0025] Figure 2 is a diagram of the burner flow field and combustion organization scheme.

[0026] 1 - Hydrogen inlet pipe, 2 - Central hydrogen pipe, 3 - Central hydrogen regulating valve, 4 - Combustion-supporting hydrogen pipe, 5 - Combustion-supporting hydrogen regulating valve, 6 - Central hydrogen branch pipe, 7 - Central hydrogen nozzle, 8 - Gas panel, 9 - Gas flame stabilizer, 10 - Ammonia inlet pipe, 11 - Ammonia regulating valve, 12 - Gas mixer, 13 - Annular header, 14 - Ammonia branch pipe, 15 - Ammonia nozzle, 16 - Primary air inlet, 17 - Primary air annular cavity, 18 - Primary air swirl vane, 19 - Flanged edge, 20 - Secondary air inlet, 21 - Secondary air annular cavity, 22 - Secondary air swirl vane, 23 - Swirl vane adjusting mechanism, 24 - Arch opening. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0028] Refer to Figure 1-2 To illustrate this embodiment, a hydrogen-ammonia hybrid low-nitrogen burner is characterized in that it includes a hydrogen inlet pipe 1, an ammonia inlet pipe 10, a gas mixer 12, an annular header 13, ammonia branch pipes 14 and ammonia nozzles 15. The hydrogen inlet pipe 1 includes a central hydrogen pipe 2 and a combustion-supporting hydrogen pipe 4. The outlet end of the central hydrogen pipe 2 is located at the center of the burner. The input end of the combustion-supporting hydrogen pipe 4 is connected to the central hydrogen pipe 2, and the output end is connected to the gas mixer 12. The output end of the ammonia inlet pipe 10 is connected to the gas mixer 12. The output end of the gas mixer 12 is connected to the annular header 13. The annular header 13 is connected with multiple ammonia branch pipes 14. The multiple ammonia branch pipes 14 are arranged in a ring. The outlet end of the ammonia branch pipe 14 is provided with an ammonia nozzle 15. A central hydrogen regulating valve 3 is installed on the central hydrogen pipe 2. A combustion-supporting hydrogen regulating valve 5 is installed on the combustion-supporting hydrogen pipe 4. An ammonia regulating valve 11 is installed on the ammonia inlet pipe 10.

[0029] The hydrogen inlet pipe 1 introduces hydrogen into the burner, and the ammonia inlet pipe 10 introduces ammonia into the burner. The hydrogen inlet pipe 1 is divided into a central hydrogen pipe 2 and a combustion-supporting hydrogen pipe 4. The flow rate in the central hydrogen pipe 2 is regulated by a central hydrogen regulating valve 3, and the flow rate in the combustion-supporting hydrogen pipe 4 is regulated by a combustion-supporting hydrogen regulating valve 5. The ammonia regulating valve 11 is used to regulate the ammonia flow rate in the ammonia inlet pipe 10. The hydrogen in the combustion-supporting hydrogen pipe 4 with regulated flow rate and the ammonia in the ammonia inlet pipe 10 enter the gas mixer 12 together to fully mix the hydrogen and ammonia. The mixed ammonia-hydrogen mixed gas enters the annular header 13. The annular header 13 is connected to multiple ammonia branch pipes 14. The ammonia branch pipes 14 form an annular arrangement. The front end of the ammonia branch pipe 14 is provided with an ammonia nozzle 15 to spray the ammonia-hydrogen mixed gas into the furnace to organize combustion.

[0030] Using hydrogen and ammonia as fuel to burn in a burner can control the chemical reaction rate of the gas and inhibit the formation of nitrogen oxides (NO) produced by the combustion product. x The burner structure is simple and stable, and does not burn the nozzle, while ensuring high-efficiency combustion of the gas. Adding hydrogen to ammonia is an effective technical method to increase the combustion reaction rate of ammonia fuel. The outer layer of the jet is a mixed gas of ammonia and hydrogen. The flammability of the mixed fuel is higher than that of pure ammonia fuel. The combustion organization forms a recirculation zone outside the burner. The recirculation zone can draw high-temperature flue gas back to the root of the ammonia-hydrogen mixture jet to heat the ammonia-hydrogen mixture. The high temperature condition can promote the ignition and combustion of the ammonia-hydrogen mixture. Finally, the burnout rate of ammonia is high, there is no ammonia escape phenomenon, and the fuel-type NO of ammonia combustion is effectively reduced. x Pollutant generation: Ammonia burns in a low-oxygen environment, and the high-temperature flame environment can promote the thermal decomposition reaction rate of ammonia. Ammonia is consumed quickly. In a low-oxygen environment, fuel-type nitrogen oxides NO are generated by the combustion of ammonia. x The production is suppressed, and ammonia can also be used as NO x The reducing agent converts the generated nitrogen oxides NO x Reducing to nitrogen solves the technical problem of high concentration fuel-type NOx emission potential during ammonia combustion. The combustion process of hydrogen is controlled, and the problem of burner burnout will not occur. The excessively fast hydrogen combustion reaction rate may cause problems such as premature combustion and flashback. The diffusion combustion method is adopted to set the hydrogen in the inner layer of the gas jet, delay the hydrogen air distribution, and control the hydrogen combustion area to maintain an appropriate distance from the burner.

[0031] Furthermore, the outlet end of the central hydrogen pipe 2 is connected to multiple central hydrogen branch pipes 6, which are connected to central hydrogen nozzles 7. The central hydrogen pipe 2 is connected to multiple central hydrogen branch pipes 6 at its front end, and central hydrogen nozzles 7 are provided at the front end of the central hydrogen branch pipe 6 to spray pure hydrogen into the furnace to organize combustion. The gas jet forms a gas distribution pattern of pure hydrogen in the center and ammonia-hydrogen mixed gas in the outer circle.

[0032] Furthermore, a gas panel 8 is provided at the end of the central hydrogen nozzle 7 and the ammonia nozzle 15. The gas panel 8 is connected to the ends of the ammonia nozzle 15 and the central hydrogen nozzle 7. The gas panel 8 is used to position and fix the central hydrogen nozzle 7 and the ammonia nozzle 15. At the same time, it can protect the ammonia branch pipe 14 and the central hydrogen branch pipe 6 from high temperature radiation of the flame in the furnace.

[0033] Furthermore, a gas flame stabilizer 9 is provided outside the gas panel 8, and the radial expansion angle of the gas flame stabilizer 9 is 15°-25°. The gas flame stabilizer 9 is arranged outside the gas panel 8, and is made of heat-resistant cast steel, which will not burn under high-temperature use environment. The radial expansion angle of the gas flame stabilizer 9 is 15°-25°, which can guide the primary air, and the organization flow field is helpful to form a reflow zone of the combustion flame.

[0034] Furthermore, a primary air inlet 16 and a secondary air inlet 20 are sequentially provided outside the burner gas pipeline. The primary air inlet 16 is connected to the primary air annular cavity 17, and the primary air is blown into the furnace through the primary air inlet 16 and the primary air annular cavity 17. The secondary air inlet 20 is connected to the secondary air annular cavity 21, and the secondary air is blown into the furnace through the secondary air inlet 20 and the secondary air annular cavity 21. The primary air and the secondary air provide oxygen for combustion of the fuel gas.

[0035] Furthermore, a primary air swirl blade 18 is installed in the primary air annular cavity 17. The blades of the primary air swirl blade 18 are deflected 30°-60° from the axial direction. The primary air forms a swirl after passing through and organizes the flow field morphology after entering the furnace.

[0036] Further, the secondary air annular cavity 21 is provided with a secondary air swirl blade 22, the blade of the secondary air swirl blade 22 is axially deflected by 30°-60°, the secondary air swirl blade 22 is connected to the swirl blade adjustment mechanism 23, the front end of the secondary air annular cavity 21 is provided with a flange 19, the corresponding radial expansion angle is 15°-25°, and the side end of the secondary air annular cavity 21 is provided with a swirl opening 24. The secondary air is introduced into the secondary air annular cavity 21 through the secondary air inlet 20, and the secondary air annular cavity 20 is provided with a secondary air swirl blade 22, the blade is axially deflected by 30°-60°, the secondary air swirl blade 22 is movable, and the swirl intensity of the secondary air can be adjusted using the swirl blade adjustment mechanism 23. The front end of the secondary air annular cavity 20 is provided with a flange 19, the corresponding radial expansion angle is 15°-25°, which can guide the secondary air, and the organization of the flow field is helpful to form a reflow zone of the combustion flame.

[0037] Specific as Figure 2As shown, the fuel gas ejected from the central hydrogen nozzle 7 and the ammonia nozzle 15 forms a jet in the external furnace of the combustion burner. The outer layer of the jet gas is ammonia-hydrogen mixed gas, and the central gas of the jet is pure hydrogen. The primary air and the secondary air are supplied to the furnace from the front end of the burner in the form of a rotating jet, and after the guiding effect of the gas flame stabilizer 9 and the flange 19, a reflow zone is formed in the flow field outside the burner. The reflow zone can draw high-temperature flue gas back to the root of the ammonia-hydrogen mixed gas jet, heat the ammonia-hydrogen mixed gas, and the high temperature condition can promote the ignition and combustion of the ammonia-hydrogen mixed gas. Adding hydrogen to ammonia is an effective technical method to increase the combustion reaction rate of ammonia fuel. The outer layer of the jet is ammonia-hydrogen mixed gas, and the combustibility of the mixed fuel is higher than that of pure ammonia fuel. The design of the reflow zone and the mixing of hydrogen into ammonia for combustion, the combination of the two technical means can effectively create suitable conditions for ammonia combustion. The oxygen concentration in the recirculation zone is low, and the primary air and secondary air are mixed and distributed for gas combustion step by step to supply oxygen for gas combustion. Ammonia burns in a low-oxygen environment, and the high-temperature flame environment can promote the thermal decomposition reaction rate of ammonia. Ammonia is consumed quickly, and the fuel-type nitrogen oxides NO generated by the combustion of ammonia in a low-oxygen environment are x The production is suppressed. Ammonia can also be used as NO x The reducing agent converts the generated nitrogen oxides NO x The combustion organization of this design effectively reduces the fuel-type NO in ammonia combustion. x The amount of pollutants generated, as the outer layer of ammonia-hydrogen mixed gas is consumed, the secondary air gradually comes into contact with the pure hydrogen in the center of the gas jet. The combustion reaction rate of hydrogen is fast, forming a hydrogen combustion zone.

[0038] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A hydrogen-ammonia mixed low-nitrogen burner, characterized in that: A hydrogen inlet pipe (1), an ammonia inlet pipe (10), a gas mixer (12), an annular header (13), an ammonia branch pipe (14) and an ammonia nozzle (15). The hydrogen inlet pipe (1) comprises a central hydrogen pipe (2) and a combustion-supporting hydrogen pipe (4). The outlet end of the central hydrogen pipe (2) is located in the annular header (13). The input end of the combustion-supporting hydrogen pipe (4) is connected to the central hydrogen pipe (2), and the output end is connected to the gas mixer (12). The output end of the ammonia inlet pipe (10) is connected to the gas mixer (12), and the output end of the gas mixer (12) is connected to the annular header (13). The annular header (13) is connected to multiple ammonia branch pipes (14). The multiple ammonia branch pipes (14) are arranged in an annular shape. The outlet end of the ammonia branch pipe (14) is provided with an ammonia nozzle (15).

2. A hydrogen-ammonia mixed low-nitrogen burner according to claim 1, characterized in that: The central hydrogen pipe (2) is provided with a central hydrogen regulating valve (3), and the combustion-supporting hydrogen pipe (4) is provided with a combustion-supporting hydrogen regulating valve (5).

3. A hydrogen-ammonia mixed low-nitrogen burner according to claim 2, characterized in that: The outlet end of the central hydrogen pipe (2) is connected to a plurality of central hydrogen branch pipes (6), and the central hydrogen branch pipes (6) are connected to a central hydrogen nozzle (7).

4. A hydrogen-ammonia mixed low-nitrogen burner according to claim 3, characterized in that: A fuel gas panel (8) is provided at the ends of the central hydrogen nozzle (7) and the ammonia nozzle (15).

5. A hydrogen-ammonia mixed low-nitrogen burner according to claim 4, characterized in that: A gas flame stabilizer (9) is provided outside the gas panel (8), and the radial expansion angle of the gas flame stabilizer (9) is 15°-25°.

6. The hydrogen-ammonia mixed low-nitrogen burner according to claim 1, characterized in that: An ammonia regulating valve (11) is installed on the ammonia introduction pipe (10).

7. The hydrogen-ammonia mixed low-nitrogen burner according to claim 1, characterized in that: A primary air inlet (16) and a secondary air inlet (20) are sequentially arranged outside the burner gas pipeline. The primary air inlet (16) is connected to the primary air annular cavity (17), and primary air is blown into the furnace through the primary air inlet (16) and the primary air annular cavity (17). The secondary air inlet (20) is connected to the secondary air annular cavity (21), and secondary air is blown into the furnace through the secondary air inlet (20) and the secondary air annular cavity (21).

8. The hydrogen-ammonia mixed low-nitrogen burner according to claim 7, characterized in that: A primary air swirl blade (18) is installed in the primary air annular cavity (17), and the blade of the primary air swirl blade (18) is deflected 30°-60° from the axial direction.

9. The hydrogen-ammonia mixed low-nitrogen burner according to claim 7, characterized in that: A secondary air swirl blade (22) is arranged in the secondary air annular cavity (21), the blade of the secondary air swirl blade (22) is axially deflected by 30°-60°, and the secondary air swirl blade (22) is connected to a swirl blade adjustment mechanism (23).

10. The hydrogen-ammonia mixed low-nitrogen burner according to claim 7, characterized in that: The front end of the secondary air ring cavity (21) is provided with a flange (19), the corresponding radial expansion angle is 15°-25°, and the side end of the secondary air ring cavity (21) is provided with a flange opening (24).

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