Low-nitrogen turbulent burner for staged combustion of hydrogen and ammonia

Abstract

The invention discloses a low-nitrogen turbulent burner for staged combustion of hydrogen and ammonia, and relates to a low-nitrogen combustion device. The problems that during combustion of ammonia gas, the flame propagation speed is low, the ammonia gas is difficult to be fully mixed with air, and fuel type NOx is likely to be generated are solved. Hydrogen is used as ignition fuel for ammonia gas combustion, the hydrogen has the advantages of being high in activity, low in ignition energy and high in flame propagation speed, the ammonia gas is ignited through the high reaction activity of the hydrogen, stable ignition and efficient combustion of the ammonia gas are achieved, the problem that the ammonia gas is difficult to ignite is effectively solved, meanwhile, NOx emission is effectively controlled, and the combustion efficiency is improved. And a feasible technical scheme is provided for large-scale clean combustion of ammonia gas. Secondly, a staged combustion technology is adopted, and a combustion area is divided into a first-stage combustion area and a second-stage combustion area; the ignition stability is guaranteed in the first-stage combustion area, complete combustion of fuel is achieved in the second-stage combustion area, and ammonia escape is reduced. The invention belongs to the technical field of boiler combustion devices.

Description

Technical Field

[0001] This invention relates to a low-NOx combustion device, specifically a low-NOx swirl burner with hydrogen-ammonia staged combustion, belonging to the technical field of boiler combustion devices. Background Technology

[0002] To achieve dual carbon goals, one of the development objectives in the energy sector is to promote the clean, low-carbon, and efficient development and utilization of fossil energy. Ammonia, as an important carrier for hydrogen utilization, has advantages such as high energy density, low cost, and safe storage and transportation, and has received widespread attention in recent years. However, its direct application as a fuel still faces many technical challenges.

[0003] First, ammonia has a high ignition temperature and a slow flame propagation speed, making it difficult to achieve stable combustion and prone to incomplete combustion. Compared to traditional fuel gas like methane, the maximum laminar flame velocity of ammonia is only 1 / 5 that of methane. This results in a lower combustion reaction rate for ammonia in the boiler, directly affecting its combustion efficiency and heat release.

[0004] Secondly, most ammonia burner designs currently struggle to achieve adequate mixing of ammonia and air, resulting in excessively high or low local fuel concentrations. This leads to unstable combustion, the formation of localized high-temperature zones, increased thermal NOx generation, and potential ammonia escape issues.

[0005] Finally, ammonia contains a high proportion of nitrogen. Under lean combustion conditions, ammonia combustion will significantly increase NOx emissions, while under rich combustion conditions, ammonia combustion will cause unburned ammonia to escape, resulting in secondary pollution.

[0006] In summary, how to propose a novel low-NOx burner to address the aforementioned technical problems has become a pressing issue for those skilled in the art. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention provides a low-NOx swirl burner with staged combustion of hydrogen and ammonia.

[0008] The technical solution of the present invention is: a low-NOx swirl burner for staged combustion of hydrogen and ammonia, comprising a hydrogen pipeline, a primary ammonia pipeline, a primary air pipeline, a secondary air pipeline, a secondary ammonia annular pipe, several secondary ammonia branch pipes, and several L-shaped hydrogen branch pipes.

[0009] The primary air pipeline, the primary ammonia pipeline, and the secondary air pipeline are sequentially nested on the hydrogen pipeline from the inside out.

[0010] Several primary ammonia swirl vanes are installed inside the primary ammonia pipeline, several primary air swirl vanes are installed inside the primary air pipeline, and several secondary air swirl vanes are installed inside the secondary air pipeline.

[0011] The secondary ammonia ring pipe is installed on the primary ammonia pipeline, and several secondary ammonia branch pipes are arranged in a circumferential array inside the secondary air pipeline, and the secondary ammonia branch pipes are connected to the secondary ammonia ring pipe.

[0012] Several L-shaped hydrogen branch pipes are arranged in a circular array inside the primary ammonia pipeline. After passing through the primary ammonia pipeline, the L-shaped hydrogen branch pipes are connected to the hydrogen pipeline.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. This invention utilizes hydrogen as the ignition fuel for ammonia combustion. Hydrogen has the characteristics of high reactivity, low ignition energy, and fast flame propagation speed. By utilizing the high reactivity of hydrogen to ignite ammonia, stable ignition and efficient combustion of ammonia are achieved, effectively solving the problem of difficult ammonia ignition. At the same time, NOx emissions are effectively controlled, providing a feasible technical solution for the large-scale clean combustion of ammonia.

[0015] 2. This invention employs staged combustion technology, dividing the combustion zone into a primary combustion zone and a secondary combustion zone. In the primary combustion zone, hydrogen, primary ammonia, and primary air are mixed and burned to form a stable combustion zone, ensuring ignition stability. In the secondary combustion zone, secondary air and secondary ammonia are introduced to achieve complete fuel combustion and reduce ammonia escape.

[0016] 3. The swirl blade design in this invention can enhance the mixing efficiency of fuel and air, ensure uniform combustion at each stage, improve the temperature field distribution, and reduce the formation of local high temperatures during combustion. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the flame inside the furnace when the present invention is in use.

[0019] In the diagram: 1. Hydrogen pipeline; 2. Primary ammonia pipeline; 3. Secondary ammonia pipeline; 4. Primary air pipeline; 5. Secondary air pipeline; 6. Secondary ammonia ring pipe; 7. Secondary ammonia branch pipe; 8. L-shaped hydrogen branch pipe; 10. Secondary air swirl blade; 11. Primary ammonia swirl blade; 12. Primary air swirl blade. Detailed Implementation

[0020] To make the objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings.

[0021] Specific implementation method one: Combining Figure 1This embodiment describes a low-NOx swirl burner with staged hydrogen-ammonia combustion, comprising a hydrogen pipeline 1, a primary ammonia pipeline 2, a primary air pipeline 4, a secondary air pipeline 5, a secondary ammonia annular pipe 6, several secondary ammonia branch pipes 7, and several L-shaped hydrogen branch pipes 8.

[0022] The primary air pipeline 4, the primary ammonia pipeline 2, and the secondary air pipeline 5 are sequentially installed on the hydrogen pipeline 1 from the inside out.

[0023] Several primary ammonia swirl vanes 11 are installed inside the primary ammonia pipeline 2, several primary air swirl vanes 12 are installed inside the primary air pipeline 4, and several secondary air swirl vanes 10 are installed inside the secondary air pipeline 5.

[0024] The secondary ammonia ring pipe 6 is installed on the primary ammonia pipeline 2, and several secondary ammonia branch pipes 7 are arranged in a circular array inside the secondary air pipeline 5, and the secondary ammonia branch pipes 7 are connected to the secondary ammonia ring pipe 6.

[0025] Several L-shaped hydrogen branch pipes 8 are arranged in a circular array inside the primary ammonia pipeline 2. After passing through the primary ammonia pipeline 2, the L-shaped hydrogen branch pipes 8 are connected to the hydrogen pipeline 1.

[0026] Specific Implementation Method Two: Combining Figure 1 This embodiment describes a method where a flared end is integrally provided at the outlet of the secondary air duct 5.

[0027] Furthermore, a secondary ammonia gas pipeline 3 is installed on the secondary ammonia gas ring pipe 6.

[0028] Other components and connection methods are the same as in Specific Implementation Method 1.

[0029] Specific implementation method three: Combining Figure 1 This embodiment describes a system where there are four secondary ammonia branch pipes 7 and four L-shaped hydrogen branch pipes 8. Other components and connection methods are the same as in specific embodiments one or two.

[0030] Specific implementation method four: Combination Figure 1 This embodiment describes a secondary ammonia gas pipeline 3 installed on the secondary ammonia gas annular pipe 6.

[0031] Other components and connection methods are the same as those in specific implementation methods one, two or three.

[0032] Working principle

[0033] Combination Figure 1 and Figure 2 Explanation of the working principle of this invention:

[0034] Hydrogen pipeline 1 is used to transport hydrogen. After the hydrogen is ejected at high speed, it is fully mixed with the air ejected from the primary air pipeline 4.

[0035] The air in the primary air duct 4 forms a swirling airflow after passing through the primary air swirl blade 12. This swirling airflow can quickly mix and react with the hydrogen gas ejected from the hydrogen duct 1, forming a stable flame in the primary combustion zone at the outlet of the primary air duct 4. This provides ignition conditions and a stable combustion environment for the subsequent ammonia combustion.

[0036] The primary ammonia pipeline 2 is used to transport ammonia. After passing through the primary ammonia swirl vane 11, the primary ammonia gains swirl intensity and mixes thoroughly with the high-speed hydrogen flow injected from the L-shaped hydrogen branch pipe 8, which significantly improves the uniformity of the hydrogen-ammonia mixture and ensures the stability of combustion.

[0037] Because the high temperature generated by hydrogen combustion allows primary ammonia to ignite and burn rapidly after mixing, it solves the problems of difficult ignition and slow flame propagation in traditional burners.

[0038] The ammonia gas supplied by the secondary ammonia pipeline 3 is first evenly distributed through the secondary ammonia ring pipe 6, and then through four secondary ammonia branch pipes 7, forming a secondary combustion zone at the outlet of the secondary air pipeline 5. This avoids the concentrated distribution of the combustion flame, making the flame present a diffuse distribution, thereby reducing the generation of local high-temperature zones, improving the uniformity of the temperature field, and further reducing the generation of thermal NOx.

[0039] The air delivered by the secondary air duct 5 forms a strong swirling airflow after passing through the secondary air swirl blades 10. This airflow mixes with the secondary ammonia in the secondary combustion zone, providing sufficient oxygen for ammonia combustion, ensuring complete combustion, and preventing ammonia escape.

[0040] The present invention has been disclosed above with reference to preferred embodiments, but it is not intended to limit the present invention. Any simple modifications, equivalent changes and alterations made by those skilled in the art to the above embodiments without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A low-nitrogen hydrogen-ammonia staged combustion swirl burner, characterized in that: it comprises a hydrogen pipe (1), a primary ammonia pipe (2), a primary air pipe (4), a secondary air pipe (5), a secondary ammonia annular pipe (6), a plurality of secondary ammonia branch pipes (7) and a plurality of L-shaped hydrogen branch pipes (8); the primary air pipe (4), the primary ammonia pipe (2) and the secondary air pipe (5) are sequentially sleeved on the hydrogen pipe (1) from inside to outside; a plurality of primary ammonia swirl vanes (11) are installed in the primary ammonia pipe (2), a plurality of primary air swirl vanes (12) are installed in the primary air pipe (4), and a plurality of secondary air swirl vanes (10) are installed in the secondary air pipe (5); the secondary ammonia annular pipe (6) is sleeved on the primary ammonia pipe (2), a plurality of secondary ammonia branch pipes (7) are arranged in the secondary air pipe (5) in a circumferential array, and the secondary ammonia branch pipes (7) are in communication with the secondary ammonia annular pipe (6); a plurality of L-shaped hydrogen branch pipes (8) are arranged in the primary ammonia pipe (2) in a circumferential array, and the L-shaped hydrogen branch pipes (8) are in communication with the hydrogen pipe (1) after penetrating through the primary ammonia pipe (2).

2. A low NOx, staged combustion, hydrogen-ammonia, swirl burner according to claim 1, wherein: The secondary ammonia annular pipe (6) is provided with a secondary ammonia pipe (3).

3. A low NOx, staged combustion, hydrogen-ammonia premixed swirl burner according to claim 2, wherein: The number of the secondary ammonia branch pipes (7) is 4.

4. A low NOx, staged combustion, hydrogen-ammonia premixed swirl burner according to claim 3, wherein: The number of the L-shaped hydrogen branch pipes (8) is 4.

5. A low NOx, staged combustion, hydrogen-ammonia premixed swirl burner according to claim 4, wherein: The secondary air pipe (5) is integrally provided with an expanded portion at the outlet thereof.

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