Coal-fired power boiler with ammonia injection

Abstract

The present application relates to a thermal power boiler, the thermal power boiler comprising: a furnace comprising a first combustion zone; a plurality of first burners for delivering fuel and air into the first combustion zone of the furnace and arranged in a circumferential direction of a center located in the first combustion zone, each of the first burners comprising a primary air and pulverized coal outlet and an ammonia fuel output component, the outlet of the ammonia fuel output component comprising an ammonia fuel outlet, the ammonia fuel output component and the primary air and pulverized coal outlet being arranged in the circumferential direction of the center, and the primary air and pulverized coal outlet being inclined in a radial direction of the center to a side away from the ammonia fuel output component. The ammonia fuel output component is located on a fire-facing side of the primary air and pulverized coal outlet, the fire-facing side providing ammonia fuel ignition energy by means of an upper adjacent angle high-temperature flame, which can ensure stable ignition of the ammonia fuel, and the lean oxygen environment on the fire-facing side is conducive to reducing the generation of NO x x.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation technology, and more specifically, to a thermal power generation boiler. 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 under the dual carbon targets. 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 ammonia (NH3) fuel is a highly efficient hydrogen storage medium with advantages such as high energy density, easy liquefaction and transportation, high safety and no carbon emissions during 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 challenges: (1) High ignition temperature, with an ignition point of 651℃, slow flame propagation speed, narrow flammability limit range, and poor combustion reactivity, resulting in problems such as difficulty in ignition, poor combustion stability, and difficulty in complete combustion; (2) NH3 molecules contain nitrogen atoms, and improper control during combustion can easily generate a large amount of pollutant NO. x .

[0004] 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.

[0005] 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 once-through 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 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, and also includes exhaust gas and tertiary air, with different nozzle arrangements. Summary of the Invention

[0006] 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.

[0007] According to one aspect of the present invention, a thermal power generation boiler is provided, the thermal power generation boiler comprising:

[0008] The furnace chamber, including the first combustion zone;

[0009] 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 away from the ammonia fuel outlet relative to the center.

[0010] In some embodiments, the outlet of the ammonia fuel output component faces the center of the first combustion zone.

[0011] 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.

[0012] In some embodiments,

[0013] The outlet of the ammonia fuel output component also includes an air outlet arranged circumferentially along the ammonia fuel outlet; or

[0014] The outlet of the ammonia fuel output component also includes an air outlet housed within the ammonia fuel outlet.

[0015] In some embodiments, the air outlet is an annular outlet, which is fitted outside the ammonia fuel outlet.

[0016] 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.

[0017] In some embodiments, a dividing component is provided within the ammonia fuel outlet, which divides the ammonia fuel outlet into multiple outlets.

[0018] 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.

[0019] In some embodiments, the shape of the ammonia fuel outlet is circular, elliptical, or square.

[0020] 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.

[0021] 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.

[0022] Applying the technical solution of this application, ammonia fuel is introduced into the fire-facing side of the primary air and pulverized coal outlet of the first burner of a thermal power boiler, located on the fire-facing side of the tangential circular combustion rotating airflow. Ammonia fuel nozzles are arranged on the fire-facing side at a certain distance from each primary air inlet. The ammonia fuel ignition energy is provided by the high-temperature flame at the upper adjacent corner, and the NO rich reducing atmosphere on the fire-facing side is used to suppress NO. x The process generates and organizes the tangential combustion of ammonia fuel jets, forming a stable rotating upward airflow that increases the combustion path of ammonia fuel, thus creating conditions for complete combustion of ammonia fuel.

[0023] 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

[0024] 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.

[0025] Figure 1 A three-dimensional structural schematic diagram of a thermal power generation boiler according to an embodiment of the present invention is shown;

[0026] Figure 2 A front view structural schematic diagram of a thermal power boiler according to an embodiment of the present invention is shown;

[0027] 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;

[0028] Figure 4 A cross-sectional structural schematic diagram of a thermal power boiler according to an embodiment of the present invention is shown;

[0029] Figure 5 It shows Figure 4 Enlarged view of point B in the middle;

[0030] Figure 6 A cross-sectional structural schematic diagram of a thermal power boiler according to another optional embodiment of the present invention is shown;

[0031] Figure 7 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

[0032] Figure 8 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

[0033] 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.

[0034] Combination Figures 1 to 5 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 within the first combustion zone 10. 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 away from the center X towards the side away from the ammonia fuel outlet component 4.

[0035] Because the outlet orientation of the primary air and pulverized coal outlet 1 is inclined relative to the center X, the primary air and pulverized coal output from the primary air and pulverized coal outlet 1 tend to rotate circumferentially E along the center X. The ammonia fuel output component 4 is located on the fire-facing side of the primary air and pulverized coal outlet 1.

[0036] In this embodiment, ammonia fuel is introduced into the fire-facing side of the primary air inlet and pulverized coal outlet 1 of the first burner 20 of the thermal power boiler, located on the fire-facing side of the tangential circular combustion rotating airflow. Ammonia fuel nozzles are arranged on the fire-facing side at a certain distance from each primary air inlet. The ammonia fuel ignition energy is provided by the high-temperature flame at the upper adjacent corner, and the NO rich reducing atmosphere on the fire-facing side is used to suppress NO. x This process generates and organizes the tangential combustion of ammonia fuel jets, creating a stable rotating upward airflow that increases the combustion path of the ammonia fuel and creates conditions for complete combustion. This achieves efficient, low-NOx combustion of ammonia fuel in tangential pulverized coal boilers.

[0037] 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.

[0038] In this embodiment, the thermal power boiler is equipped with an ammonia burnout zone, which achieves both stable ignition and burnout of ammonia and coal, and effectively suppresses NO. x The ammonia blending method can meet the conditions for high-proportion ammonia blending by adjusting the opening of the ammonia fuel nozzle or the number of ammonia nozzle operation layers within the ammonia blending ratio range of 0-60%, making it highly applicable. This technical solution is suitable for the ammonia blending retrofitting of coal-fired units or 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.

[0039] like Figure 5 As shown, in some embodiments, the outlet of the ammonia fuel output component 4 is generally oriented towards the center of the first combustion zone 10a. There is a small angle between the outlet orientation of the ammonia fuel output component 4 and the orientation of the primary air and pulverized coal outlet 1.

[0040] In other embodiments, the outlet of the ammonia fuel output component 4' intersects the orientation of the primary air and pulverized coal outlet 1.

[0041] By aligning the ammonia fuel outlet 41 with the primary air and pulverized coal outlet 1, the ammonia fuel jet direction forms a certain angle (0–180°) with the primary air and pulverized coal flow. This allows the ammonia jet to be directed towards the root of the pulverized coal flow, enhancing rapid mixing with active materials. Alternatively, the ammonia jet can be deviated from the pulverized coal flow to create a reverse shear, further strengthening the thorough mixing of ammonia fuel and pulverized coal and allowing for earlier contact with the high-temperature flame at the adjacent corner, thus enhancing stable combustion. Furthermore, the ammonia fuel nozzle can be equipped with a blunt body or utilize a flow divider to create a recirculation zone at the outlet, entraining high-temperature flue gas and providing sufficient heat for fuel combustion. This increases the contact area between the ammonia flow and the high-temperature flue gas, enhancing combustion. Through these various combustion stabilization measures, this technology exhibits high adaptability to ammonia mixing ratios. The ammonia mixing ratio (calorific value ratio) ranges from 0–60%.

[0042] like Figure 6 As shown, in some other embodiments, two centers X are arranged side by side inside the furnace 10, and a plurality of first burners 20 are arranged circumferentially in each center X. The ammonia fuel output component 4 of the first burner 20 and the primary air and pulverized coal outlet 1 are arranged circumferentially in the center X, and the primary air and pulverized coal outlet 1 is inclined radially away from the center X towards the side away from the ammonia fuel output component 4.

[0043] like Figure 7 and 8 As shown, 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, providing an oxygen-rich atmosphere for the combustion of ammonia fuel.

[0044] 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.

[0045] like Figure 7 and 8 As shown, 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 provided 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.

[0046] 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.

[0047] 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.

[0048] The shape of the ammonia fuel outlet 41 is round, elliptical, or square.

[0049] 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.

[0050] 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 fire-facing side of the tangential combustion rotating airflow. Ammonia fuel nozzles are arranged on the fire-facing side at a certain distance from each primary air inlet, thereby forming an overall trend in which the ammonia fuel is surrounded by the pulverized coal airflow in the center of the furnace.

[0051] (1) Stable Combustion: Stable ignition is achieved by utilizing the high-temperature flame at the upper adjacent corner to provide ignition energy for ammonia fuel. In addition, the ammonia jet is located in the high-coal-powder concentration, fuel-rich zone on the fire-facing side, where a large amount of volatiles are released through pyrolysis of the coal powder. The released active substances such as CH4 / H2 are beneficial to enhancing the ignition of NH3 and increasing the combustion intensity of ammonia fuel, reducing the ignition delay time of the mixed fuel, and ensuring stable combustion. By setting the axial angle of the ammonia fuel nozzle, the direction of the ammonia fuel jet is made at a certain angle (0-180°) with the primary air-coal-powder flow. This allows the ammonia jet to be directed towards the root of the coal-powder flow, thereby strengthening the rapid mixing with active substances. Alternatively, the ammonia jet can be deviated from the coal-powder flow to form a reverse shear, thereby strengthening the full mixing of ammonia fuel and coal-powder fuel and contacting the high-temperature flame at the upper adjacent corner earlier, thus enhancing 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, providing sufficient heat source for fuel combustion, increasing the contact area between the ammonia flow and the high-temperature flue gas, and enhancing combustion. Through various combustion stabilization measures, this technology achieves high adaptability to ammonia blending. The ammonia blending ratio (calorific value ratio) ranges from 0% to 60%.

[0052] (2) Combustion: Organize the ammonia fuel jet to burn in a tangential circle, forming a stable rotating upward flame airflow to increase the combustion path of ammonia fuel, thereby increasing the residence time of ammonia fuel in the furnace and having a longer combustion path, thus creating conditions for the complete combustion of ammonia fuel; the furnace is divided into a main combustion zone and a combustion zone, and an oxygen-rich area is created in the combustion zone to achieve turbulent combustion of unburned fuel and ensure a high ammonia combustion rate.

[0053] (3) NO reduction: The excess air coefficient in the main combustion zone is <1. Achieving air staging in ammonia-coal combustion is beneficial for suppressing NO. x Due to the reducing properties of ammonia, NH3 can act as both a fuel and a catalyst for the combustion of NO. x The reducing agent. By setting a suitable ammonia fuel nozzle jet angle, ammonia fuel is injected into a specific flame temperature range (850℃~1150℃) to reduce the NO generated by pulverized coal. x This allows for the co-firing of ammonia fuel in tangential pulverized coal boilers, reducing CO2 emissions while simultaneously lowering NO2 levels. x Generation amount.

[0054] (4) Corrosion prevention: The overall trend of ammonia fuel being enveloped in the center of the furnace by the coal powder airflow can effectively prevent corrosion of the water-cooled wall tubes caused by ammonia fuel brushing against the walls.

[0055] The above description is merely an exemplary embodiment of the present invention and is 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 generation boiler, characterized in that, include: The furnace (10) includes a first combustion zone (10a); A plurality of first burners (20) are provided for supplying fuel and air into 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 away from the center (X) towards the side away from the ammonia fuel outlet component (4). The ammonia fuel output component (4) and the primary air and pulverized coal outlet (1) are both located at the corners of the furnace (10), with the outlet of the ammonia fuel output component (4) facing the center of the first combustion zone (10a). The ammonia fuel outlet (41) includes multiple outlets arranged in rows or columns, or in a horizontal or vertical direction. A dividing component (42) is provided within the ammonia fuel outlet (41) to divide the ammonia fuel outlet (41) into multiple outlets. The outlet of the ammonia fuel output component (4) also includes an air outlet (43) arranged circumferentially along the ammonia fuel outlet (41). The orientation of the ammonia fuel output component (4) of the same first burner (20) and the orientation of the primary air and pulverized coal outlet (1) are deviated from the same side of the center (X). The orientation of the primary air and pulverized coal outlet (1) of the same first burner (20) is further away from the center (X) than the orientation of the ammonia fuel output component (4).

2. The thermal power boiler according to claim 1, characterized in that, The air outlet (43) is an annular outlet, which is fitted outside the ammonia fuel outlet (41).

3. 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).

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

5. 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).

6. 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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