Coal-fired power boiler with ammonia injection

Abstract

This invention relates to a coal-fired power plant boiler with ammonia and coal co-firing. The power plant boiler includes: a furnace (10) including a first combustion zone; and a plurality of first burners (20) for supplying fuel and air to the first combustion zone of the furnace (10) and arranged circumferentially along a center (X) within the first combustion zone (10a). Each first burner includes a primary air and pulverized coal outlet (1) and an ammonia fuel outlet component (4). The outlet of the ammonia fuel outlet component includes an ammonia fuel outlet (41). The ammonia fuel outlet components (4) are arranged side by side circumferentially along the center, and the primary air and pulverized coal outlet (1) is inclined radially toward the ammonia fuel outlet component (4) relative to the center. Because the backfire side of the primary air and pulverized coal outlet (1) presents an oxidizing environment and has inherent properties of low speed, high temperature and backflow, the backfire side of the primary air and pulverized coal outlet (1) is a more favorable ignition source area during combustion, which can ensure stable ignition of ammonia fuel.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation technology, and more specifically, to a thermal power generation boiler that uses ammonia and coal co-firing. Background Technology

[0002] In my country, coal-fired power plays a vital role in ensuring power supply and peak shaving. However, due to its heavy reliance on fossil fuels, it is a key high-carbon emission industry, facing significant challenges in carbon reduction. Therefore, the proposal to introduce zero-carbon fuels to replace a certain proportion of coal in coal-fired boilers is an ideal way to reduce carbon emissions at the source.

[0003] Among them, zero-carbon fuel - ammonia (NH3) is a highly efficient hydrogen storage medium with advantages such as high energy density, easy liquefaction and storage, high safety and no carbon emissions from combustion. In addition, it can be synthesized from renewable energy sources, making it a truly green and clean energy storage medium, suitable as a zero-carbon alternative fuel for coal-fired boilers. However, the ammonia combustion process has the following technical problems: (1) High ignition temperature, with an ignition point of 651℃, and slow flame propagation speed, narrow combustible limit range, and poor combustion reactivity, which makes ammonia combustion difficult to ignite, has poor combustion stability and is difficult to burn completely;

[0004] (2) NH3 molecules contain nitrogen atoms, and improper combustion can easily generate a large amount of pollutant NO. x .

[0005] Therefore, how to achieve stable combustion and complete burnout of ammonia fuel while avoiding the generation of large amounts of pollutants (unburned ammonia escape, NO) is crucial. x The combustion of ammonia in coal-fired boilers is a critical technical issue that urgently needs to be addressed.

[0006] One of the most widely used combustion methods in coal-fired boilers is tangential combustion. In tangential pulverized coal boilers, the pulverized coal airflow is introduced into the furnace by direct-flow first burners located at the four, six, or eight corners of the furnace or at certain positions on the furnace wall to organize tangential combustion, forming various tangential shapes, such as four-corner tangential, four-wall tangential, hexagonal tangential, single-furnace octagonal tangential, and octagonal double tangential. In addition, based on the arrangement of the first burners at the corners or vertically in the furnace wall, it is further divided into alternating primary and secondary air arrangements, secondary air arrangements on the back side of each primary air source, or concentrated primary air arrangements. It also includes exhaust gas and tertiary air, and the arrangement of each nozzle varies. Summary of the Invention

[0007] The present invention aims to provide a thermal power boiler that uses ammonia and coal co-firing and is conducive to ensuring stable ignition and combustion of ammonia fuel.

[0008] According to one aspect of the present invention, a thermal power generation boiler is provided, the thermal power generation boiler comprising:

[0009] The furnace chamber, including the first combustion zone;

[0010] Multiple first burners are provided for supplying fuel and air to a first combustion zone in the furnace and are arranged circumferentially along a center located within the first combustion zone. Each first burner includes a primary air and pulverized coal outlet and an ammonia fuel outlet. The outlet of the ammonia fuel outlet includes an ammonia fuel outlet. The ammonia fuel outlet and the primary air and pulverized coal outlet are arranged circumferentially along the center, and the primary air and pulverized coal outlet are inclined radially toward the ammonia fuel outlet with respect to the center.

[0011] In some embodiments, the outlet of the ammonia fuel output component faces the center of the first combustion zone.

[0012] In some embodiments, the outlet of the ammonia fuel output component is oriented in an orientation that intersects with the primary air and pulverized coal outlets.

[0013] In some embodiments,

[0014] The outlet of the ammonia fuel output component also includes an air outlet arranged circumferentially along the ammonia fuel outlet; or

[0015] The outlet of the ammonia fuel output component also includes an air outlet housed within the ammonia fuel outlet.

[0016] In some embodiments, the air outlet is an annular outlet, which is fitted outside the ammonia fuel outlet.

[0017] In some embodiments, the ammonia fuel outlets include a plurality of outlets arranged in rows or columns or arranged in a horizontal or vertical direction.

[0018] In some embodiments, a dividing component is provided within the ammonia fuel outlet, which divides the ammonia fuel outlet into multiple outlets.

[0019] In some embodiments, the first burner includes a plurality of primary air and pulverized coal outlets arranged in a vertical direction, and at least some of the primary air and pulverized coal outlets are provided with ammonia fuel output components.

[0020] In some embodiments, the shape of the ammonia fuel outlet is circular, elliptical, or square.

[0021] In some embodiments, the furnace further includes a second combustion zone located above the first combustion zone. A plurality of second burners are arranged around the second combustion zone. The second burners are used to supply air or air and fuel to the second combustion zone and to create an oxygen-rich atmosphere within the second combustion zone.

[0022] In some embodiments, the output flow rate of the ammonia fuel output component is adjustable, or the opening and closing of multiple ammonia fuel output components can be controlled independently.

[0023] By applying the technical solution of this application, the backfire side of the primary air and pulverized coal outlet presents an oxidizing environment and has the inherent properties of low speed, high temperature and backflow. The backfire side of the primary air and pulverized coal outlet is a more favorable ignition source area during the combustion process, which can ensure the stable ignition of ammonia fuel.

[0024] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A three-dimensional structural schematic diagram of a thermal power generation boiler according to an embodiment of the present invention is shown;

[0027] Figure 2 A front view structural schematic diagram of a thermal power boiler according to an embodiment of the present invention is shown;

[0028] Figure 3 It shows Figure 2 A schematic diagram of the structure of the first burner at point A of a medium-sized thermal power plant boiler;

[0029] Figure 4 A cross-sectional structural schematic diagram of a thermal power boiler according to an embodiment of the present invention is shown;

[0030] Figure 5 A schematic diagram of the ammonia fuel output section of a thermal power boiler according to an embodiment of the present invention is shown; and

[0031] Figure 6 A schematic diagram of the ammonia fuel output section of a thermal power boiler according to another embodiment of the present invention is shown. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Combination Figures 1 to 4 As shown, the thermal power boiler includes a furnace 10 and a plurality of first burners 20. The furnace 10 includes a first combustion zone 10a. The plurality of first burners 20 are used to supply fuel and air into the first combustion zone 10a of the furnace 10 and are arranged circumferentially along a center X located in the first combustion zone 10a. Each first burner 20 includes a primary air and pulverized coal outlet 1 and an ammonia fuel output component 4. The outlet of the ammonia fuel output component 4 includes an ammonia fuel outlet 41. The ammonia fuel output component 4 and the primary air and pulverized coal outlet 1 are arranged circumferentially along the center X, and the primary air and pulverized coal outlet 1 is inclined to the side of the ammonia fuel output component 4 with respect to the radial direction of the center X. Therefore, the ammonia fuel output component 4 is located on the backfire side of the primary air and pulverized coal outlet 1.

[0034] Since the outlet of the primary air and pulverized coal outlet 1 is tilted relative to the center X, the primary air and pulverized coal output from the primary air and pulverized coal outlet 1 tend to rotate in the circumferential direction E along the center X.

[0035] In this embodiment, ammonia is introduced to the backfire side outside the primary air and pulverized coal outlet 1 of the first burner 20 of the thermal power boiler. Ammonia fuel nozzles are arranged on the furnace wall or corner area of ​​the backfire side at a certain distance from each primary air and pulverized coal outlet 1. This technical solution does not require oxygen enrichment or pure oxygen for combustion, thus eliminating safety hazards. Furthermore, due to the inherent properties of the backfire side of the primary air and pulverized coal outlet 1—an oxidizing environment with low speed, high temperature, and backflow—it is a relatively favorable ignition source area during combustion, ensuring stable ignition of the ammonia fuel.

[0036] The furnace 10 also includes a second combustion zone 10b located above the first combustion zone 10a. Multiple second burners 30 are arranged around the second combustion zone 10b. The second burners 30 are used to supply air or air and fuel to the second combustion zone 10b and to create an oxygen-rich atmosphere within the second combustion zone 10b. The furnace also includes an upper furnace zone 10c located above the second combustion zone 10b. The first combustion zone 10a is the main combustion zone, and the second combustion zone 10b is the burnout zone.

[0037] In some embodiments, the outlet of the ammonia fuel output component 4' is generally oriented towards the center of the first combustion zone 10a. The outlet orientation of the ammonia fuel output component 4' forms a small angle with the orientation of the primary air and pulverized coal outlet 1.

[0038] In other embodiments, the outlet of the ammonia fuel output component 4 intersects with the orientation of the primary air and pulverized coal outlet 1.

[0039] Furthermore, by aligning the ammonia fuel outlet 41 with the primary air and pulverized coal outlet 1, the ammonia fuel is injected into the flame of the pulverized coal gas flow, achieving mixed combustion of the ammonia fuel and pulverized coal gas flow. This creates a stable, rotating, upward gas flow, increasing the combustion path of the ammonia fuel and creating conditions for stable ignition and complete combustion. The furnace is divided into a main combustion zone and a burnout zone, and NO is reduced through air staging. x Therefore, it can achieve stable ignition and complete combustion of ammonia coal, while effectively suppressing NO emissions. x The ammonia blending method allows for the adjustment of the ammonia fuel nozzle opening or the number of ammonia nozzle operation layers within the ammonia blending ratio range of 0-60%, thus meeting the conditions for high-proportion ammonia blending and exhibiting strong applicability. This technical solution is applicable to both ammonia blending retrofits of coal-fired units and the construction of new ammonia-blended coal-fired units, as the ammonia combustion system involved is simple, resulting in low retrofitting and construction costs, low operating costs, and low operational complexity.

[0040] The outlet of the ammonia fuel output component 4 also includes an air outlet 43 arranged circumferentially along the ammonia fuel outlet 41. The air outlet 43 is used to output air for ammonia fuel combustion.

[0041] In some embodiments, the air outlet 43 is an annular outlet, which is fitted outside the ammonia fuel outlet 41. In other embodiments, the air outlet is fitted inside the ammonia fuel outlet 41.

[0042] The ammonia fuel output component 4 may consist of only an ammonia fuel outlet 41 or may also include an air outlet 43 extending around the ammonia fuel outlet 41 or an ammonia and air premixed nozzle. Figure 4 and Figure 5 The ammonia fuel output component 4 includes an air outlet 43, which may or may not be provided. A dividing component 42 is installed within the ammonia fuel outlet 41 to divide the flow of pure ammonia gas or a premixed flow of ammonia and air within the nozzle. When an air channel is provided, a state of air-coated ammonia fuel is formed, preventing the oxygen content in the near-wall region from weakening the oxidizing atmosphere due to ammonia combustion, thereby avoiding high-temperature corrosion.

[0043] The ammonia fuel outlet 41 includes multiple outlets arranged in rows or columns, or horizontally or vertically. A dividing component 42 is installed within the ammonia fuel outlet 41, dividing it into multiple outlets. To enhance combustion and improve the adaptability and adjustment capability of the mixed ammonia boiler to different coal types, a dividing component or 0 to n longitudinal and transverse baffles can be installed inside the ammonia fuel outlet 41 to separate the ammonia fuel jet into dispersed jets. This allows the ammonia fuel gas flow to create a recirculation zone at the outlet, entraining high-temperature flue gas and increasing the contact surface between the ammonia gas flow and the high-temperature flue gas. The baffles can be set at a certain guiding angle to form a scattering flow or a swirling jet of ammonia gas flow, promoting turbulence and intense mixing of ammonia and high-temperature flue gas. Alternatively, the ammonia fuel nozzle may not have a blunt body or baffles.

[0044] The first burner 20 includes a plurality of primary air and pulverized coal outlets 1 arranged in a vertical direction, and at least some of the primary air and pulverized coal outlets 1 are provided with ammonia fuel output components 4.

[0045] The shape of the ammonia fuel outlet 41 is round, elliptical, or square.

[0046] The flow rate of the ammonia fuel output component 4 is adjustable, and the proportion of ammonia fuel to be added can be controlled according to the required ratio. In other embodiments, the primary air and pulverized coal outlets 11 correspond to multiple ammonia fuel output components 4, and the opening and closing of the multiple ammonia fuel output components 4 can be controlled independently. The proportion of ammonia fuel to be added can be adjusted by controlling the number of ammonia fuel output components 4 that are open. Therefore, the jet rigidity of ammonia fuel can be ensured while meeting the ammonia fuel addition requirements.

[0047] In this embodiment, ammonia fuel, which is difficult to ignite and has poor combustion stability, is introduced outside the primary air inlet of the tangential pulverized coal boiler burner and located on the backfire side of the tangential combustion rotating airflow. Ammonia fuel nozzles are arranged on the backfire side at a certain distance from each pulverized coal burner / primary air inlet.

[0048] Stable combustion: The backfire side of the pulverized coal burner presents an oxidizing environment with inherent properties of low speed, high temperature, and backflow, making it a relatively favorable ignition source area during combustion. This ensures stable ignition of ammonia fuel. Furthermore, by setting the angle α between the ammonia fuel nozzle axis and the primary air / pulverized coal flow, [further advantages can be achieved].

[0049] (0~180°) This allows ammonia fuel to be injected into the flame of the pulverized coal gas stream, enhancing its mixing and combustion with the burning pulverized coal gas stream and strengthening the stable combustion of ammonia fuel. In addition, the ammonia fuel nozzle can be equipped with a blunt body or a flow divider baffle to create a recirculation zone at the outlet to entrain high-temperature flue gas, increasing the contact area between the ammonia gas stream and the high-temperature flue gas and enhancing combustion.

[0050] Burnout: After mixing and burning with the pulverized coal gas flow, it participates in tangential combustion, forming a stable rotating upward flame gas flow, increasing the combustion path of ammonia fuel, increasing the residence time of ammonia fuel in the furnace, and having a longer burnout journey, thus creating conditions for the complete combustion of ammonia fuel; the furnace is divided into a main combustion zone and a burnout zone, and an oxygen-rich area is created in the burnout zone to achieve turbulent burnout of unburned fuel and ensure a high ammonia burnout rate.

[0051] NOx Reduction: The excess air coefficient in the main combustion zone is <1, and a burnout zone is set up to achieve staged air combustion in ammonia-coal, which helps to suppress NOx. x Ammonia is generated. Due to its reducing properties, NH3 can act as both a fuel and a reducing agent in the combustion of NOx. The ammonia fuel nozzles are arranged separately from the primary air nozzles, allowing the pulverized coal flame to mix with the ammonia fuel while burning, exhibiting staged combustion characteristics, which helps reduce NOx formation. xGeneration; On the backfire side, the addition of ammonia enhances the local reducing atmosphere, which is beneficial for reducing NO produced by pulverized coal. x By setting an appropriate ammonia fuel nozzle jet angle, ammonia fuel is injected into a specific flame temperature range (850℃~1150℃) to fully utilize the NO generated from the reduction of pulverized coal. x This achieves the effect of reducing CO2 emissions while lowering NOx emissions in pulverized coal boilers that use ammonia-blended fuel. x Generation amount.

[0052] The above are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermal power boiler that uses ammonia and coal co-firing, characterized in that, include: The furnace (10) includes a first combustion zone (10a); Multiple first burners (20) are provided for supplying fuel and air to a first combustion zone (10a) of the furnace (10) and are arranged circumferentially along a center (X) within the first combustion zone (10a). Each first burner (20) includes a primary air and pulverized coal outlet (1) and an ammonia fuel outlet component (4). The outlet of the ammonia fuel outlet component (4) includes an ammonia fuel outlet (41). The ammonia fuel outlet component (4) and the primary air and pulverized coal outlet (1) are arranged circumferentially along the center (X), and the primary air and pulverized coal outlet (1) is inclined radially toward the ammonia fuel outlet component (4) relative to the center (X). The ammonia fuel outlet component (4) is located on the backfire side of the primary air and pulverized coal outlet (1). The ammonia fuel outlet component (4) and the primary air and pulverized coal outlet (1) are located at the corners of the first combustion zone (10a). The outlet of the ammonia fuel output component (4) faces the center of the first combustion zone (10a).

2. The thermal power boiler according to claim 1, characterized in that, The outlet of the ammonia fuel output component (4) also includes an air outlet (43) arranged circumferentially along the ammonia fuel outlet (41); or The outlet of the ammonia fuel output component (4) also includes an air outlet housed within the ammonia fuel outlet (41).

3. The thermal power boiler according to claim 2, characterized in that, The air outlet (43) is an annular outlet, which is fitted outside the ammonia fuel outlet (41).

4. The thermal power boiler according to claim 1, characterized in that, The ammonia fuel outlet (41) includes multiple outlets arranged in rows or in a horizontal or vertical direction.

5. The thermal power boiler according to claim 4, characterized in that, The ammonia fuel outlet (41) is provided with a dividing component (42) that divides the ammonia fuel outlet (41) into multiple outlets.

6. The thermal power boiler according to claim 1, characterized in that, The first burner (20) includes a plurality of primary air and pulverized coal outlets (1) arranged in a vertical direction, and at least some of the primary air and pulverized coal outlets (1) are correspondingly provided with the ammonia fuel output component (4).

7. The thermal power boiler according to claim 1, characterized in that, The shape of the ammonia fuel outlet (41) is circular, elliptical or square.

8. The thermal power boiler according to claim 1, characterized in that, The furnace (10) also includes a second combustion zone (10b) located above the first combustion zone (10a). A plurality of second burners (30) are arranged around the second combustion zone (10b). The second burners (30) are used to supply air or air and fuel to the second combustion zone (10b) and to form an oxygen-rich atmosphere in the second combustion zone (10b).

9. The thermal power boiler according to claim 1, characterized in that, The output flow of the ammonia fuel output component (4) is adjustable, or the opening and closing of multiple ammonia fuel output components (4) can be controlled independently.

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