Ammonia-coal co-fired thermal power boiler

Abstract

This invention relates to a coal-fired power plant boiler with ammonia and coal co-firing, characterized in that it comprises: a furnace (10) including a first combustion zone (10a); a plurality of first burners (20) for supplying fuel and air into the first combustion zone (10a) of the furnace (10) and arranged circumferentially along a center (X) within the first combustion zone (10), each first burner (20) including a fuel and air outlet (1), the fuel and air outlet (1) including a primary air and pulverized coal outlet (11) and an ammonia fuel output component (12) disposed within the primary air and pulverized coal outlet (11), the ammonia fuel output component (12) including an ammonia fuel outlet (121). Introducing ammonia fuel into the primary air of the first burner (20) of the coal-fired power plant boiler facilitates the co-combustion of ammonia fuel and pulverized coal airflow.

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 major high-carbon emission industry. Under the dual carbon (carbon peaking and carbon neutrality) goals, coal-fired power faces significant challenges in carbon emission reduction. Therefore, introducing zero-carbon fuels to replace a certain proportion of coal in coal-fired boilers is proposed as an ideal way to reduce carbon emissions at the source.

[0003] Among them, ammonia (NH3), a zero-carbon 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 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 challenges: (1) High ignition temperature, with an ignition point of 651℃, slow flame propagation speed, narrow flammability limit, 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 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

[0006] The present invention aims to provide a thermal power boiler that uses ammonia and coal co-firing and is conducive to the stable combustion of ammonia fuel.

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

[0008] Thermal power generation boilers include:

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

[0010] Multiple first burners are arranged circumferentially along a center located within the first combustion zone of the furnace for supplying fuel and air. Each first burner includes a fuel and air outlet, which includes a primary air outlet and a pulverized coal outlet. All or part of the primary air and pulverized coal outlets are provided with an ammonia fuel output component, which includes an ammonia fuel outlet.

[0011] In some embodiments, a plurality of ammonia fuel output components are provided inside the primary air and pulverized coal outlets, with adjacent ammonia fuel output components spaced apart.

[0012] In some embodiments, the ammonia fuel output component further includes an air outlet for outputting air.

[0013] In some embodiments, the air outlet is arranged circumferentially along the ammonia fuel outlet, or the air outlet is located outside the ammonia fuel outlet.

[0014] In some embodiments, the air outlet is an annular outlet, which is fitted outside the ammonia fuel outlet.

[0015] In some embodiments, the ammonia fuel output component includes a first tubular component and a second tubular component sleeved outside the first tubular component. The first tubular component and the second tubular component form an annular channel. One end of the annular channel forms an annular outlet. One end of the first tubular component forms an ammonia fuel outlet. The ammonia fuel outlet includes a pure ammonia gas nozzle or an ammonia-air mixture gas nozzle.

[0016] In some embodiments,

[0017] The end of the first tubular component is provided with a baffle, and the baffle has a hole for forming an ammonia fuel outlet; or

[0018] The port of the first tubular component is provided with a first strip component and a second strip component that intersects with the first strip component, so as to divide the port of the first tubular component into multiple ammonia fuel outlets.

[0019] In some embodiments, the orientation of the ammonia fuel outlet is at a certain angle α with the orientation of the primary air and pulverized coal outlets, wherein α ranges from 0ˉ±90°.

[0020] In some embodiments, the primary air and pulverized coal outlets and the ammonia fuel outlet of the ammonia fuel output component are inclined to either radially to the sides of the center or to the same radial side of the center, respectively.

[0021] In some embodiments,

[0022] The radial angle between the primary air and pulverized coal outlets and the center is greater than the radial angle between the ammonia fuel outlet and the center; or

[0023] The radial angle between the primary air and pulverized coal outlets and the center is smaller than the radial angle between the ammonia fuel outlet and the center.

[0024] In some embodiments,

[0025] The flow rate of the ammonia fuel output component is adjustable; and / or

[0026] Multiple ammonia fuel output components are installed in the primary air and pulverized coal outlets, and the opening and closing of the multiple ammonia fuel output components can be controlled independently.

[0027] In some embodiments, the furnace further includes a second combustion zone located above the first combustion zone, and the thermal power boiler further includes a second burner for supplying air or air and fuel to the second combustion zone, the second burner being used to create an oxygen-rich atmosphere in the second combustion zone so that the fuel is burned completely therein.

[0028] By applying the technical solution of this application, ammonia fuel is introduced into the primary air chamber of the first burner of a thermal power boiler, which is beneficial to achieving the mixed combustion of ammonia fuel and pulverized coal gas flow.

[0029] 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

[0030] 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.

[0031] Figure 1 A three-dimensional structural schematic diagram of a thermal power generation boiler according to an embodiment of the present invention is shown;

[0032] Figure 2 A front view structural schematic diagram of a thermal power boiler according to an embodiment of the present invention is shown;

[0033] 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;

[0034] Figure 4 A cross-sectional structural schematic diagram of a thermal power boiler according to an embodiment of the present invention is shown;

[0035] Figure 5 It shows Figure 4 Enlarged view of point B in the middle;

[0036] Figure 6 A schematic diagram of the fuel and air outlet of the first burner of a thermal power boiler according to an embodiment of the present invention is shown;

[0037] Figure 7 It shows Figure 6 A three-dimensional structural schematic diagram of the ammonia fuel outlet component at the fuel and air outlets shown;

[0038] Figure 8 A schematic diagram of the fuel and air outlet of the first burner of a thermal power boiler according to another embodiment of the present invention is shown; and

[0039] Figure 9 It shows Figure 8 The diagram shows a three-dimensional structural schematic of the ammonia fuel outlet component at the fuel and air outlets. Detailed Implementation

[0040] 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.

[0041] like Figures 1 to 3 As shown, the thermal power generation boiler of this embodiment 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 fuel and air outlet 1, the fuel and air outlet 1 includes a primary air and pulverized coal outlet 11 and an ammonia fuel output component 12 disposed in the primary air and pulverized coal outlet 11, the ammonia fuel output component 12 including an ammonia fuel outlet 121.

[0042] In this embodiment, introducing ammonia fuel into the primary air chamber of the first burner 20 of the thermal power boiler facilitates the mixed combustion of ammonia fuel and pulverized coal gas flow. In this embodiment, the first burner 20 of the thermal power boiler introduces ammonia fuel into the primary air chamber of the first burner 20 of the tangentially circular pulverized coal boiler, achieving mixed combustion of ammonia fuel and pulverized coal gas flow. This technical solution does not require oxygen enrichment or pure oxygen for combustion, thus eliminating safety hazards. Because the ammonia fuel and pulverized coal gas flow are mixed and combusted in a fuel-rich, oxygen-deficient environment, the large amount of volatile active substances released by the pyrolysis of pulverized coal in the initial stage of combustion enhances the combustion activity of ammonia, and the oxygen-deficient reducing atmosphere inhibits NO combustion.x generate.

[0043] like Figure 1 and 2 As shown, the furnace also includes a second combustion zone 10b located above the first combustion zone 10a. The furnace also includes an upper furnace zone 10c located above the second combustion zone 10b.

[0044] Multiple ammonia fuel output components 12 are installed inside the primary air and pulverized coal outlet 11, with adjacent ammonia fuel output components 12 spaced apart.

[0045] like Figure 3 , 6 As shown in Figure 8, in some embodiments, the cross-section of the primary air and pulverized coal outlet 11 is polygonal, for example, the cross-section of the primary air and pulverized coal outlet 11 is rectangular or square. In other embodiments, the cross-section of the primary air and pulverized coal outlet 11 may also be triangular, pentagonal, or hexagonal. Multiple ammonia fuel output components 17 are distributed within the cross-section of the primary air and pulverized coal outlet 11.

[0046] like Figure 6 As shown, in some embodiments, multiple rows of ammonia fuel output components 12 are provided within the primary air and pulverized coal outlet 11. Optionally, each row of ammonia fuel output components 12 includes multiple ammonia fuel output components 12 arranged laterally or longitudinally along the cross-section of the primary air and pulverized coal outlet 11. Optionally, the number of ammonia fuel output components 12 in adjacent rows is different. The ammonia fuel output components 12 in adjacent rows are staggered. In other embodiments, at least a portion of the ammonia fuel output components 12 in adjacent rows are aligned.

[0047] like Figure 7 As shown, the ammonia fuel output component 12 also includes an air outlet 122 arranged circumferentially along the ammonia fuel outlet 121, although the air outlet may not be provided. In some embodiments, the ammonia fuel outlet 121 includes a plurality of circumferentially arranged ammonia fuel outlets, so that the ammonia fuel output by the ammonia fuel output component 12 can be dispersed to the surrounding area and fully mixed with the air and primary air output by the surrounding air outlet 122 and the primary air and pulverized coal output by the pulverized coal outlet 11. The ammonia fuel outlet 121 also includes a central ammonia fuel outlet located at the center of the plurality of circumferential ammonia fuel outlets.

[0048] Air outlet 122 is an annular outlet, which is located outside ammonia fuel outlet 121.

[0049] The ammonia fuel output component 12 includes a first tubular component 123 and a second tubular component 124 sleeved outside the first tubular component 123. The first tubular component 123 and the second tubular component 124 form an annular channel. One end of the annular channel forms an annular outlet, and one end of the first tubular component 123 forms an ammonia fuel outlet 121.

[0050] like Figure 6 and 7 As shown, a baffle 125 is provided at the end of the first tubular component 123, and the baffle 125 is provided with a hole for forming an ammonia fuel outlet 121.

[0051] like Figure 8 and 9 As shown, a first strip component 126 and a second strip component intersecting the first strip component 126 are provided inside the port of the first tubular component 123 to divide the port of the first tubular component 123 into a plurality of ammonia fuel outlets 121.

[0052] like Figure 3 As shown, in some other embodiments, the cross-section of the primary air and pulverized coal outlet 11 is circular or elliptical, and the primary air and pulverized coal outlet 11 is provided with a plurality of ammonia fuel output components 12, which are arranged along the edge of the cross-section of the primary air and pulverized coal outlet 11.

[0053] The ammonia fuel output component 12 can be made of metal (e.g., stainless steel, nickel-based alloys, and materials with a temperature resistance of over 1000°C) or high-temperature and corrosion-resistant ceramics (e.g., silicon carbide, zirconium oxide).

[0054] like Figure 5 As shown, the orientation of the ammonia fuel outlet 121 is at a certain angle α (0~±90°) with the orientation of the primary air and pulverized coal outlet 11, which is conducive to the thorough mixing of the ammonia fuel output from the ammonia fuel outlet 121 with the primary air and pulverized coal outlet 11.

[0055] In some embodiments, such as Figure 4 As shown, the primary air and pulverized coal outlet 11 and the ammonia fuel outlet 121 of the ammonia fuel output component 12 are inclined to the radial sides of the center X, respectively. The primary air and pulverized coal output from the primary air and pulverized coal outlet 11 flow in direction a, and the ammonia fuel output from the ammonia fuel outlet 121 flows in direction b. Therefore, the primary air and pulverized coal form a vortex rotating in direction F, and the ammonia fuel forms a vortex rotating in direction E. Since the rotation directions F and E are opposite, this can further promote the thorough mixing of ammonia fuel with primary air and pulverized coal.

[0056] In other embodiments, the primary air and pulverized coal outlet 11 and the ammonia fuel outlet 121 of the ammonia fuel output component 12 are inclined to the same side of the radial direction of the center X.

[0057] In some embodiments, the radial angle between the primary air and pulverized coal outlet 11 and the center X is greater than the radial angle between the ammonia fuel outlet 121 and the center X, and the radius of the rotation direction F is greater than the radius of the rotation direction E, forming an overall tendency for the ammonia fuel to be enveloped in the center of the furnace by the mixed airflow of pulverized coal and primary air. This can achieve full mixing of the ammonia fuel with the mixed airflow of pulverized coal and primary air, while effectively avoiding corrosion of the water-cooled wall tubes caused by direct brushing of ammonia fuel against the wall.

[0058] In other embodiments, the radial angle between the primary air and pulverized coal outlet 11 and the center X is smaller than the radial angle between the ammonia fuel outlet 121 and the center X, and the radius of the rotation direction F is smaller than the radius of the rotation direction E, forming an overall trend of ammonia fuel enveloping pulverized coal and primary air mixed airflow. This can achieve full mixing of ammonia fuel with pulverized coal and primary air mixed airflow, while also helping to alleviate the problem of pulverized coal particles directly impacting the water-cooled wall and forming slag.

[0059] The flow rate of the ammonia fuel output component 12 is adjustable, and the ammonia fuel output component 12 can be controlled according to the required proportion of ammonia fuel. In some other embodiments, multiple ammonia fuel output components 12 are provided in the primary air and pulverized coal outlet 11, and the opening and closing of the multiple ammonia fuel output components 12 can be controlled independently. The proportion of ammonia fuel added can be adjusted by controlling the number of ammonia fuel output components 12 that are open.

[0060] Multiple second burners 30 are arranged around the second combustion zone 10b. The second burners are used to create an oxygen-rich atmosphere in the second combustion zone. The first combustion zone 10a is the main combustion zone, and the second combustion zone 10b is the burnout zone.

[0061] The ammonia fuel outlet 121 is located within the primary air and pulverized coal outlet 11, allowing the mixed fuels to co-combust. In the initial stage of combustion, a rich and reducing atmosphere is formed. The large amount of volatile active substances such as CH4 / H2 / CO released by the pyrolysis of pulverized coal promotes the ignition of ammonia fuel, increases the combustion speed, and significantly reduces the ignition delay time, ensuring ignition and stable combustion.

[0062] The primary air and pulverized coal outlet 11 is equipped with multiple ammonia fuel outlets 121, with the ammonia fuel output from each outlet 121 forming a certain angle α (0 to ±90°) with the primary air and pulverized coal flow. This enhances the thorough mixing of the ammonia fuel with the primary air and pulverized coal flow, thereby strengthening the rapid mixing with active materials and enhancing the stable combustion of the ammonia fuel. The ammonia fuel nozzle is equipped with a first strip-shaped component 126 and a second strip-shaped component or dividing baffle 125 to increase the contact surface between the ammonia flow and the pulverized coal flow, further enhancing the mixing and combustion.

[0063] Furthermore, because the ammonia fuel outlet 121 is located within the primary air and pulverized coal outlet 11, the ammonia fuel ignites simultaneously with the pulverized coal airflow. Ignition energy can be provided by a pulverized coal ignition source, thus improving the adaptability to high-proportion ammonia blending. The ignition source can be various forms of pulverized coal burner ignition equipment, such as a high-energy igniter, plasma ignition gun, gas gun, or oil gun. For plasma ignition guns, the plasma provides sufficiently high energy while simultaneously pyrolyzing the ammonia to generate active substances, promoting ammonia ignition. Through these stable combustion measures, this technology exhibits high adaptability to ammonia blending. The ammonia blending ratio (calorific value ratio) ranges from 0% to 60%.

[0064] Tangential combustion (creating a rotating vortex) generates a strongly rotating aerodynamic structure in the ammonia fuel gas flow within the furnace. After leaving the burner, it forms a stable, rotating, upward-flowing flame, increasing the combustion path of the ammonia fuel and extending its residence time in the furnace, resulting in a longer burnout stroke and creating conditions for complete combustion. The furnace is divided into a main combustion zone and a burnout zone. An oxygen-rich area is created in the burnout zone to achieve turbulent burnout of unburned fuel, ensuring a high ammonia burnout rate.

[0065] The excess air coefficient in the main combustion zone is <1. Achieving staged air combustion in ammonia-coal is beneficial for suppressing NO₂. 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 α, the ammonia fuel can reduce the NO generated by pulverized coal. x This achieves the effect of reducing CO2 emissions while lowering NOx emissions in pulverized coal boilers that co-fire ammonia fuel. x NO generation. Because the initial combustion stage occurs in a fuel-rich, strongly reducing atmosphere, NO production can be effectively suppressed. x NO generated simultaneously from pulverized coal x It can be reduced by ammonia, thus reducing NOx emissions.

[0066] In this embodiment, by selecting the flow rate of ammonia fuel outlet or the quantity put into operation, a high proportion of ammonia fuel blending conditions can be achieved, which has strong applicability in the range of ammonia blending ratio from 0 to 60%.

[0067] 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 generation boiler, characterized in that, include: The furnace (10) includes a first combustion zone (10a); Multiple first burners (20) are arranged circumferentially along a center within the first combustion zone (10a) of the furnace (10) to supply fuel and air. Each first burner (20) includes a fuel and air outlet (1), which includes a primary air and pulverized coal outlet (11) and an ammonia fuel output component (12) disposed within the primary air and pulverized coal outlet (11). The ammonia fuel output component (12) includes an ammonia fuel outlet (121) to introduce ammonia fuel into the primary air of the first burner (20) of the thermal power boiler. The ammonia fuel and pulverized coal airflow are co-fired in a fuel-rich and oxygen-deficient environment. The primary air and pulverized coal outlet (11) and the ammonia fuel outlet (121) of the ammonia fuel output component (12) are respectively inclined radially to both sides of the center, so that the primary air and pulverized coal form a vortex rotating in direction F, and the ammonia fuel forms a vortex rotating in direction E, wherein the rotation directions F and E are opposite. The radial angle between the primary air and pulverized coal outlet (11) and the center is smaller than the radial angle between the ammonia fuel outlet (121) and the center, and the radius of the rotation direction F is smaller than the radius of the rotation direction E.

2. The thermal power boiler according to claim 1, characterized in that, Multiple ammonia fuel output components (12) are installed inside the primary air and pulverized coal outlet (11), with adjacent ammonia fuel output components (12) spaced apart.

3. The thermal power boiler according to claim 1, characterized in that, The ammonia fuel output component (12) also includes an air outlet (122) for outputting air.

4. The thermal power boiler according to claim 3, characterized in that, The air outlet (122) is arranged circumferentially along the ammonia fuel outlet (121), or the air outlet (122) is located outside the ammonia fuel outlet (121).

5. The thermal power boiler according to claim 3, characterized in that, The air outlet (122) is an annular outlet, which is fitted outside the ammonia fuel outlet (121).

6. The thermal power boiler according to claim 5, characterized in that, The ammonia fuel output component (12) includes a first tubular component (123) and a second tubular component (124) sleeved outside the first tubular component (123). The first tubular component (123) and the second tubular component (124) form an annular channel. One end of the annular channel forms the annular outlet. One end of the first tubular component (123) forms the ammonia fuel outlet (121). The ammonia fuel outlet (121) includes a pure ammonia gas nozzle or an ammonia-air mixture gas nozzle.

7. The thermal power boiler according to claim 6, characterized in that, The first tubular component (123) has a baffle (125) at its end, and the baffle (125) has a hole for forming the ammonia fuel outlet (121); or A first strip member (126) and a second strip member intersecting the first strip member (126) are provided in the port of the first tubular member (123) to divide the port of the first tubular member (123) into a plurality of ammonia fuel outlets (121).

8. The thermal power boiler according to claim 1, characterized in that, The flow rate of the ammonia fuel output component (12) is adjustable; and / or The primary air and pulverized coal outlet (11) is provided with a plurality of ammonia fuel output components (12), and the opening and closing of the plurality of ammonia fuel output components (12) can be controlled independently.

9. 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), and the thermal power boiler also includes a second burner (30) for supplying air or air and fuel to the second combustion zone (10b), the second burner (30) for creating an oxygen-rich atmosphere in the second combustion zone (10b) so that the fuel is burned out there.

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