Methane mixed ammonia gas combustion heater structure for power station boiler

Abstract

The utility model relates to the technical field of combustion heaters, and particularly discloses a methane-mixed ammonia gas combustion heater structure for a power station boiler, which comprises a combustion chamber, a combustor body is arranged in the combustion chamber, and a porous medium is arranged at the downstream of the combustor body; a fuel fluid center channel is formed in the center of the burner body, a first-stage axial channel, a second-stage axial channel, a plurality of jet flow holes and a third-stage radial channel are formed in the burner body, and a first-stage axial rotational flow channel is formed in the first-stage axial channel through first-stage blades. A second-stage axial rotational flow channel is formed in the second-stage axial channel through second-stage blades, and a third-stage radial rotational flow channel is formed in the third-stage radial channel through third-stage blades; by means of the combined design of the burner and the porous medium, mixed fuel of methane and ammonia gas can be fully mixed, stable on-duty flames are formed in the porous medium, cold air can be heated, carbon emission of cold start of the boiler is reduced, and the purpose of reducing carbon is achieved.

Description

Technical Field

[0001] This utility model relates to the field of combustion heater technology, and specifically discloses a structure for a methane-ammonia-blended combustion heater for power plant boilers. Background Technology

[0002] Currently, many domestic thermal power generating units are considering using plasma ignition and micro-oil ignition methods to reduce fuel consumption. When using plasma ignition for cold boiler startup, thermal power generating units still require auxiliary heat sources for processes such as hot air pulverization in coal mills, soot blowing in boiler air preheaters, and thermal deaeration of feedwater. Currently, the main method for power plants to achieve this heat source is to install a startup boiler and connect it to the unit's auxiliary steam header, or to connect it to the auxiliary steam header of adjacent boilers or units. For power plants building two or fewer new units, this method not only increases the construction cost of the startup boiler room, but also significantly increases startup costs due to the large amount of fuel consumed by the startup boiler.

[0003] To address the issue of high fuel consumption during cold starts of power plant boilers, some industry practices have employed methane-ammonia blends as fuel gas for combustion heating. However, limitations in burner design prevent the thorough mixing of methane and ammonia, hindering the formation of a stable standby flame for heating cold air. Therefore, this application proposes a methane-ammonia blend combustion heater structure for power plant boilers. This structure enables the thorough mixing of methane and ammonia to form a stable standby flame for heating cold air, thereby meeting the requirements for cold-start coal mills in power plant boilers while simultaneously reducing carbon emissions during cold starts, ultimately achieving the goal of carbon reduction. Utility Model Content

[0004] The purpose of this invention is to provide a structure for a methane-ammonia mixed combustion heater for power plant boilers, which enables the methane and ammonia mixture to burn fully and stably, allowing it to serve as an auxiliary heat source to preheat cold air. This reduces carbon emissions during cold start-up of the power plant boiler while enabling cold start-up of the coal mill.

[0005] This utility model is achieved through the following technical solution:

[0006] A structure for a methane-ammonia-blended combustion heater for a power plant boiler includes a combustion chamber, inside which a burner body is disposed, and a porous medium is concentrically connected downstream of the burner body.

[0007] The burner body has a fuel fluid central channel at its center. A primary axial channel and a secondary axial channel are concentrically arranged on the burner body surrounding the fuel fluid central channel. A tertiary radial channel is formed on the outer circumference of the burner body. A primary axial swirl channel is formed in the primary axial channel by primary blades. A secondary axial swirl channel is formed in the secondary axial channel by secondary blades. A tertiary radial swirl channel is formed in the tertiary radial channel by tertiary blades. Multiple first jet holes are uniformly formed circumferentially on the burner body between the fuel fluid central channel and the primary axial channel. Multiple second jet holes are uniformly formed circumferentially on the burner body between the primary axial channel and the secondary axial channel.

[0008] The cross-sectional area of ​​the primary air outlet corresponding to the first-stage axial swirl channel gradually increases, while the cross-sectional areas of the secondary air outlet and the tertiary cooling air outlet corresponding to the second-stage axial swirl channel and the third-stage radial swirl channel gradually decrease. The secondary air outlet and the tertiary cooling air outlet are respectively inclined toward the center of the burner body and toward the inner wall of the combustion chamber.

[0009] As a further provision of the above scheme, the multiple first-stage blades are circumferentially and uniformly arranged in the first-stage axial channel, the multiple second-stage blades are circumferentially and uniformly arranged in the second-stage axial channel, and the multiple third-stage blades are circumferentially and uniformly arranged in the third-stage radial channel.

[0010] As a further feature of the above scheme, the first-stage blades and the second-stage blades are arranged in a reverse spiral configuration.

[0011] As a further feature of the above scheme, both the first-stage blade and the second-stage blade are designed with a curved structure.

[0012] As a further feature of the above scheme, the third-stage blades are arranged in the third-stage radial channel with adjustable angles.

[0013] As a further feature of the above scheme, the first jet hole and the second jet hole adopt an irregular hole structure design, with the upstream of the first jet hole and the second jet hole being circular and the downstream outlet being enlarged.

[0014] As a further feature of the above scheme, the porous medium is configured with a double-layer porous structure, with a high pore density at the end near the burner body and a low pore density at the end away from the burner body. Beneficial effects

[0015] The methane-ammonia blended combustion heater structure for power plant boilers disclosed in this utility model can preheat the air during cold start-up of the boiler, thereby serving as an auxiliary heat source. While utilizing ammonia to reduce carbon emissions, it can also reduce fuel oil and coal costs.

[0016] This invention utilizes a combination design of the burner body and porous media to allow the mixed fuel fluid of methane and ammonia to be fully mixed with the air in the central recirculation zone, achieving complete combustion of methane and ammonia. This process heats the cold air, reduces carbon emissions during boiler cold starts, and achieves the goal of carbon reduction.

[0017] In this invention, the burner body, through the structural design of three swirling inlets and outlets, can adjust and control the size of the central recirculation zone, as well as the length of the cooling air and the combustion reaction zone, thereby improving its adaptability to different operating conditions. At the same time, the design of two sets of jet holes can enhance the mixing of methane and air, forming a stable methane standby flame, which can maintain the continuous and stable combustion of methane and ammonia.

[0018] The heater disclosed in this utility model adopts a modular design, which facilitates installation, maintenance and replacement, greatly improving the practicality and promotion value of the equipment. By preheating the cold air, it significantly improves the boiler's start-up efficiency and reduces the dependence on traditional fossil fuels during cold start-up, which is in line with the concept of green development. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a cross-sectional view of the structure of the methane-ammonia-blended combustion heater for the entire power plant boiler in this utility model;

[0021] Figure 2 This is a schematic diagram of the planar structure of the burner body in this utility model;

[0022] Figure 3 This is a three-dimensional structural diagram of the burner body in this utility model;

[0023] Figure 4 This is a cross-sectional side view of the burner body in this utility model;

[0024] Figure 5 This is a three-dimensional structural diagram of the first-stage blade in this utility model;

[0025] Figure 6 This is a three-dimensional structural diagram of the secondary blade in this utility model;

[0026] Figure 7 This is a three-dimensional structural diagram of the three-stage blade in this utility model;

[0027] Figure 8 This is a schematic diagram of the planar structure of the porous medium in this utility model;

[0028] Figure 9 This is a schematic diagram of the central reflux zone formed in the methane-ammonia-mixed warm air heater of this utility model;

[0029] Figure 10 The isosurface distribution of the central recirculation zone of the two-stage axial cyclone and the two-stage axial + radial cyclone of this invention is colored with vorticity cloud diagrams. (a) Two-stage axial cyclone, (b) Two-stage axial + radial cyclone.

[0030] Figure 11 This is a cross-sectional velocity distribution cloud map of the dual-stage axial + radial swirling flow of this patent. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The following will refer to the appendix... Figures 1-11 This application will be described in detail with reference to the embodiments. Example 1

[0033] Example 1 discloses a structure for a methane-ammonia blended combustion heater for a power plant boiler, as shown in the attached figure. Figure 1 The system comprises a combustion chamber 1, a burner body 2, and a porous medium 3. The combustion chamber 1 is pipe-shaped, guiding the flow of cold air. The burner body 2 is located upstream of the combustion chamber 1, and the porous medium 3 is located downstream of the combustion chamber 1 and connected to the fuel fluid outlet at the center of the burner body 2. During operation, the burner body 2 thoroughly mixes the fuel fluid (methane and ammonia) with air, and then ignites it via electric spark ignition (a conventional technique, not shown in the diagram) near the reflux zone and shear layer. This ignites a stable standby flame within the porous medium 3, preheating the flowing cold air. This design can rapidly provide the required thermal energy during the cold start-up of a power plant boiler, significantly improving start-up efficiency and reducing reliance on traditional fuels during startup.

[0034] Reference Appendix Figures 2-7The burner body 2 is ring-shaped and is fixedly connected to the center of the combustion chamber 1 by flanges, bolts, and other connecting parts extending radially outward from the ends. This creates a division point where the upstream section of the burner body 2 is the inlet section 12-1 of the combustion chamber, and the downstream section is the outlet section 12-2. A fuel fluid central channel 4 is located at the center of the burner body 2. This channel allows a mixture of methane and ammonia to pass through, resulting in the mixture being discharged from the fuel outlet of the central channel 4. The mixture then forms a precessing vortex 10 within the porous medium 3, providing a stable standby flame for complete combustion.

[0035] The burner body 2 has concentrically arranged primary and secondary axial channels, and a tertiary radial channel on its outer surface. The primary axial channel forms a primary axial swirl channel 6 through multiple circumferentially evenly distributed primary blades 21. The secondary axial channel forms a secondary axial swirl channel 8 through multiple circumferentially evenly distributed secondary blades 22. The tertiary radial channel forms a tertiary radial swirl channel 9 through multiple circumferentially evenly arranged tertiary blades 23. Simultaneously, multiple first jet holes 5 are circumferentially evenly distributed between the primary axial channel and the fuel fluid center channel 4, and multiple second jet holes 7 are circumferentially evenly distributed between the primary and secondary axial channels. Both the first jet holes 5 and the second jet holes 7 are used to introduce methane gas, thereby generating a stable methane flame (i.e., a standby flame) to facilitate the combustion of the methane and ammonia mixture in the central recirculation zone.

[0036] In its specific design, both the first-stage blade 21 and the second-stage blade 22 adopt a curved structure and are arranged in a counter-spiral pattern. This not only effectively reduces the flow resistance of the fluid in the swirling channel and enhances the mixing between fuel and air, but also optimizes the airflow path due to the curved shape of the first-stage blade 21 and the second-stage blade 22. This makes the fluid flow more smoothly through the swirling channel, reduces turbulence losses, enhances the turbulence characteristics of the fuel fluid, significantly improves the rotational speed and mixing effect of the airflow, and ensures the stability of the combustion process. Furthermore, the coaxial two-stage swirling channel design in the burner effectively controls the flow rate of the primary and secondary air, as well as the local swirling number, thereby adjusting the radial size of the central recirculation zone 25.

[0037] The third-stage blade 23 adopts an adjustable angle design. By dynamically adjusting the tangential angle of the third-stage blade 23, the circumferential velocity of the fluid is changed, thereby changing the local swirl number and affecting the turbulent pulsation characteristics such as the length and radial dimension of the central recirculation zone of the flow field. It can optimize the airflow organization in the combustion chamber under different operating conditions, ensure the stability and efficiency of the combustion process, adapt to changing loads and fuel characteristics, and maintain optimal combustion performance.

[0038] Reference Appendix Figure 4 At the primary air outlet 14 corresponding to the first-stage axial swirl channel 6, the cross-sectional area gradually increases, forming a pressure-boosting and deceleration-reducing region. The secondary air outlet 16 and tertiary cooling air outlet 17 corresponding to the second-stage axial swirl channel 8 and the third-stage radial swirl channel 9 are both designed with blunt bodies to reduce the cross-sectional area and form a pressure-boosting and depressurization-reducing region. Furthermore, the secondary air outlet 16 is tilted towards the center of the burner body 2, while the tertiary cooling air outlet 17 is tilted in the opposite direction towards the inner wall of the combustion chamber 1. Through the structural design of the primary air outlet 14, secondary air outlet 16, and tertiary cooling air outlet 17, a stable and turbulent central recirculation zone can be formed at the outlet of the burner body 2, achieving stable combustion of methane mixed with ammonia. Simultaneously, since the tertiary cooling air flows along the outermost layer, it can remove heat from the inner wall of the combustion chamber 1, effectively controlling the combustion chamber wall temperature.

[0039] In addition, the first jet hole 5 and the second jet hole 7 adopt an irregular hole structure design, which is circular at the upstream end and becomes larger at the downstream outlet. They cooperate with the main inclined surface of the burner body 2 to reduce the velocity and diffusion angle, thereby enhancing the mixing with the primary and secondary air.

[0040] Reference Appendix Figure 8 In this embodiment, the porous medium 3 adopts a double-layer porous structure design. The upper porous medium 12-1 has a higher pore density (i.e., the end closest to the burner body 2 is the upper porous medium), which helps promote the diffusion of combustion gases, while the lower porous medium 11-2 has a lower pore density and is mainly used to stabilize the flame. This double-layer porous structure design can not only form a stable methane combustion standby flame when the boiler starts up, but also effectively heat the cold air, significantly reduce carbon emissions, and help achieve carbon reduction goals.

[0041] Reference Appendix Figure 9 In the operation of a methane-ammonia blended combustion heater for power plant boilers, the volume ratio of ammonia fuel can be set between 0-50%. Flame stability is affected by the Reynolds number (incoming flow velocity), swirl number, and fuel volume fraction, and the ammonia volume ratio can be adjusted accordingly. After the fuel gas is introduced, a central recirculation zone 25 can be formed in the inlet section 12-1 of the combustion chamber. (See attached reference.) Figure 10 Compared to traditional two-stage axial cyclones, the central recirculation zone 25 formed in this embodiment 1 is shorter in length, corresponding to stronger turbulence intensity within it, thereby producing stronger mixing characteristics and combustion performance. (See attached diagram) Figure 11A angular recirculation zone is formed between the tertiary cooling air outlet 17 and the inner wall of the combustion chamber 1, and a lip recirculation zone is formed between the secondary air outlet 16 and the tertiary cooling air outlet 17. This results in a stronger velocity gradient distribution within the shear layer. The presence of the central recirculation zone and the porous medium promotes fuel-air mixing and enhances flame stability, thereby improving combustion efficiency. Furthermore, by adjusting the size of the central recirculation zone, the intensity and duration of the combustion reaction can be effectively controlled, improving the overall thermal efficiency and environmental friendliness of the system.

[0042] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A structure for a methane-ammonia blended combustion heater for a power plant boiler, comprising a combustion chamber, characterized in that, The combustion chamber is equipped with a burner body, and a porous medium is concentrically connected downstream of the burner body. The burner body has a fuel fluid central channel at its center. A primary axial channel and a secondary axial channel are concentrically arranged on the burner body surrounding the fuel fluid central channel. A tertiary radial channel is formed on the outer circumference of the burner body. A primary axial swirl channel is formed in the primary axial channel by primary blades. A secondary axial swirl channel is formed in the secondary axial channel by secondary blades. A tertiary radial swirl channel is formed in the tertiary radial channel by tertiary blades. Multiple first jet holes are uniformly formed circumferentially on the burner body between the fuel fluid central channel and the primary axial channel. Multiple second jet holes are uniformly formed circumferentially on the burner body between the primary axial channel and the secondary axial channel. The cross-sectional area of ​​the primary air outlet corresponding to the first-stage axial swirl channel gradually increases, while the cross-sectional areas of the secondary air outlet and the tertiary cooling air outlet corresponding to the second-stage axial swirl channel and the third-stage radial swirl channel gradually decrease. The secondary air outlet and the tertiary cooling air outlet are respectively inclined toward the center of the burner body and toward the inner wall of the combustion chamber.

2. The structure of the methane-ammonia blended combustion heater for power plant boilers according to claim 1, characterized in that, Multiple first-stage blades are circumferentially and uniformly arranged in a first-stage axial channel, multiple second-stage blades are circumferentially and uniformly arranged in a second-stage axial channel, and multiple third-stage blades are circumferentially and uniformly arranged in a third-stage radial channel.

3. The structure of the methane-ammonia blended combustion heater for power plant boilers according to claim 2, characterized in that, The primary and secondary blades are arranged in a reverse spiral configuration.

4. The structure of the methane-ammonia blended combustion heater for power plant boilers according to claim 2, characterized in that, Both the primary and secondary blades are designed with a curved structure.

5. The structure of the methane-ammonia blended combustion heater for power plant boilers according to claim 3, characterized in that, The three-stage blades are set in the three-stage radial channel with adjustable angles.

6. The structure of the methane-ammonia blended combustion heater for power plant boilers according to claim 1, characterized in that, The first and second jet holes adopt an irregular hole structure design, with the upstream of the first and second jet holes being circular and the downstream outlet being enlarged.

7. The structure of the methane-ammonia blended combustion heater for power plant boilers according to claim 1, characterized in that, The porous medium has a double-layer porous structure with a high pore density at the end closer to the burner body and a low pore density at the end farther from the burner body.

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