Ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner

Abstract

An ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner is provided according to the present application, including a primary air duct, an inner secondary air duct, and an outer secondary air duct. The gas injector in the primary air duct is used to mix gas uniformly into primary air-coal powder flow. The gas injectors in the inner secondary air duct and the outer secondary air duct are arranged in a staggered configuration, with nozzles in both the gas injectors in the inner secondary air duct and the outer secondary air duct curving toward a center of a burner outlet, directing gas into flame core. By arranging different types of the gas injectors in the primary air duct, the inner secondary air duct, and the outer secondary air duct, and optimizing their positions, promoting a more uniform combustion process and improving overall combustion efficiency and stability.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The application claims priority to Chinese patent application No. 202411921984.7, filed on Dec. 25, 2024, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present application relates to the technical field of burners, and in particular to an ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner.BACKGROUND

[0003] Ammonia-coal co-firing technology involves mixing ammonia and coal in a specific ratio to be used as boiler fuel, achieving both stable combustion and low-carbon emissions. By mixing ammonia into coal, the carbon dioxide emissions from coal-fired power plants can be significantly reduced. This technology not only facilitates the transformation and upgrading of coal-fired units but also contributes to achieving carbon peaking and carbon neutrality goals.

[0004] In the operation of related burners, issues such as the nozzle design for ammonia injection, the arrangement of injection points, and the inability to adjust ammonia flow rates result in uneven mixing of ammonia and coal powder. This results in localized overheating or incomplete combustion, thereby increasing the generation of emissions.SUMMARY

[0005] In view of this, an ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner is provided according to the present application, so as to at least solve the technical problem existing in the conventional technology.

[0006] In order to solve the above problem, an ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner is provided according to the present application, including a primary air duct, an inner secondary air duct, and an outer secondary air duct arranged sequentially from inside to outside. The primary air duct, the inner secondary air duct, and the outer secondary air duct are internally provided with gas injectors, respectively. The gas injector in the primary air duct is used to mix gas uniformly into primary air-coal powder flow. The gas injectors in the inner secondary air duct and the outer secondary air duct are arranged in a staggered configuration, with nozzles in both the gas injectors in the inner secondary air duct and the outer secondary air duct curving toward a center of a burner outlet, directing gas into flame core.

[0007] Optionally, the gas injector includes a first gas injector, which is positioned inside the primary air duct and is coaxially arranged with the primary air duct.

[0008] Optionally, the gas injector further includes a second gas injector and a third gas injector, where the second gas injector is arranged circumferentially within the inner secondary air duct, and the third gas injector is arranged circumferentially within the outer secondary air duct.

[0009] Optionally, there are four second gas injectors arranged at equal intervals circumferentially, and there are four third gas injectors arranged at equal intervals circumferentially.

[0010] Optionally, the burner further includes a heat exchange assembly. The heat exchange assembly includes a heat exchanger, with an inlet end of the heat exchanger connected to a gas main pipe, and an outlet end of the heat exchanger connected to multiple gas branch pipes. Each of the gas branch pipes is respectively connected to the corresponding gas injector, and the heat exchanger is used to heat the gas, ensuring that the heated gas is delivered into the gas injectors.

[0011] Optionally, the heat exchange assembly includes a main pipe flow adjustment assembly and a branch flow adjustment assembly. The main pipe flow adjustment assembly is arranged on the gas main pipe to regulate the gas flow within the gas main pipe, and the branch flow adjustment assembly is arranged on the gas branch pipe to regulate the gas flow within the gas branch pipe.

[0012] Optionally, the inner secondary air duct is provided with inner secondary air swirling blades at an end close to the nozzle, and the outer secondary air duct is provided with outer secondary air swirling blades at an end close to the nozzle.

[0013] Optionally, the nozzle of the primary air duct is provided with a primary air expansion cone.

[0014] Optionally, the nozzle of the inner secondary air duct is provided with an inner secondary air expansion cone.

[0015] Optionally, the nozzle of the outer secondary air duct is provided with an outer secondary air expansion cone.

[0016] By means of the above technical solution, the present application has at least the following benefits.

[0017] The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner provided according to the present application is designed for use in ammonia preheating and flow-controllable low-nitrogen co-firing systems. By improving the nozzle design, optimizing placement, and enabling adjustable ammonia flow, the burner leverages the denitrification properties of ammonia while enhancing coal combustion efficiency. After preheating, ammonia is mixed with coal powder and introduced into the combustion system. Through precise flow adjustment and strategic placement of gas injectors, the system ensures uniform mixing of ammonia and coal powder. This promotes complete combustion of the coal powder, reduces the formation of unburned residues, improves combustion efficiency, and lowers carbon emissions. The burner not only maintains the energy efficiency of coal but also significantly reduces NOx emissions, meeting increasingly stringent environmental regulations. Additionally, it enhances the overall thermal efficiency and stability of the boiler.BRIEF DESCRIPTION OF DRAWINGS

[0018] FIG. 1 is a schematic structural view of an ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to an embodiment of the present application;

[0019] FIG. 2 is a cross-sectional view of the ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to the embodiment of the present application.

[0020] Reference numerals in the drawings are listed as follows:

[0021] 1 heat exchanger, 2 hot secondary air duct, 3 gas main pipe, 4 main pipe flow adjustment assembly, 5 branch flow adjustment assembly, 6 ceramic sleeve, 7 third gas injector, 8 first gas injector, 9 third nozzle, 10 inner secondary air swirling blade, 11 outer secondary air swirling blade, 12 primary air expansion cone, 13 inner secondary air expansion cone, 14 outer secondary air expansion cone.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In the description of the present application, it should be noted that the terms such as “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise” and the like indicate orientations or positional relationships which are based on the drawings. Such terms are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the indicated device or element must have a specific orientation or be configured and operated in a specific orientation. Hence, the terms should not be construed as limitations to the present application.

[0023] Furthermore, the terms “first” and “second” are merely used for purpose of description, and should not be construed as indicating or implying relative importance or implying the number of the indicated technical features. Therefore, the features defined with “first”, and “second” may explicitly or implicitly comprise one or more of the features. In the description of the present application, “multiple” means two or more, unless specifically defined otherwise.

[0024] In the description of the present application, unless otherwise clearly specified and limited, terms such as “mount”, “be connected to”, “connect” and “fix” should be understood in a broad sense. For example, a connection may be a fixed connection, or a detachable connection, or an integral connection; a connection may be a mechanical connection or an electrical connection; and a connection may be a direct connection, or an indirect connection through an intermediate medium, or an internal connection between two elements. For those skilled in the art, the specific meaning of the above terms in the present application may be understood in the light of specific circumstances.

[0025] Preferred embodiments of the present application are described hereinafter in conjunction with the drawings of the specification. It should be understood that the preferred embodiments described herein are only used for illustrating and explaining the present application and are not intended to limit the present application.

[0026] Referring to FIG. 1 and FIG. 2, an ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner is provided according to an embodiment of the present application, including a primary air duct, an inner secondary air duct, and an outer secondary air duct arranged sequentially from inside to outside. The primary air duct, the inner secondary air duct, and the outer secondary air duct are internally provided with gas injectors, respectively. The gas injector in the primary air duct is used to mix gas uniformly into primary air-coal powder flow. The gas injectors in the inner secondary air duct and the outer secondary air duct are arranged in a staggered configuration, with nozzles in both the gas injectors in the inner secondary air duct and the outer secondary air duct curving toward the center of a burner outlet, directing the gas into flame core.

[0027] It is suitable for ammonia preheating and flow-controllable low-nitrogen co-firing systems. By improving the nozzle design, optimizing placement, and enabling adjustable ammonia flow, the burner leverages the denitrification properties of ammonia while enhancing coal combustion efficiency. After preheating, ammonia is mixed with coal powder and introduced into the combustion system. Through precise flow adjustment and strategic placement of the gas injectors, the system ensures uniform mixing of ammonia and coal powder. This promotes complete combustion of the coal powder, reduces the formation of unburned residues, improves combustion efficiency, and lowers carbon emissions. The burner not only maintains the energy efficiency of coal but also significantly reduces NOx emissions, meeting increasingly stringent environmental regulations. Additionally, it enhances the overall thermal efficiency and stability of the boiler.

[0028] The primary air duct, the inner secondary air duct, and the outer secondary air duct are arranged sequentially from inside to outside. In other words, the primary air duct is positioned at center, with the inner secondary air duct coaxially fitted around the outside of the primary air duct, and the outer secondary air duct coaxially fitted around the outside of the inner secondary air duct.

[0029] The primary air duct, the inner secondary air duct, and the outer secondary air duct are internally provided with the gas injectors, respectively. These gas injectors are used to deliver gas, which, in this embodiment, is ammonia.

[0030] When the boiler operates at low load, the overall furnace temperature is relatively low, while the ignition temperature required for ammonia is higher, resulting in poor combustion conditions. To prevent incomplete combustion, only the gas injectors within the primary air duct are activated at this time. Conversely, when the boiler operates at higher loads, the furnace temperature is higher, and the combustion conditions improve. Therefore, the gas injectors within the inner secondary air duct and the outer secondary air duct can be gradually activated based on the actual load conditions to enhance the combustion efficiency.

[0031] The gas injectors in the inner secondary air duct and the outer secondary air duct are arranged in a staggered configuration, with their nozzles curved toward the center of the burner outlet. In other words, the gas injectors in the inner secondary air duct and the outer secondary air duct are alternately positioned, and their nozzles are directed toward the center of the outlet. This design ensures that the ammonia is effectively injected into the flame core, allowing it to mix thoroughly with the coal powder. This setup promotes a more uniform combustion process, facilitates the complete combustion of the coal powder, reduces the generation of the unburned residues, and improves overall combustion efficiency and stability.

[0032] The gas injector includes a first gas injector 8, which is located inside the primary air duct and is coaxially arranged with the primary air duct.

[0033] The first gas injector 8 includes a first nozzle, designed in a swirling pattern to ensure that the ammonia is evenly mixed into the primary air-coal powder flow.

[0034] The first gas injector 8 further includes a first gas pipe, with a first nozzle mounted at an outlet of the first gas pipe.

[0035] Specifically, the first gas pipe is a ceramic sleeve 6.

[0036] The gas injectors further include a second gas injector and a third gas injector 7, where the second gas injector is arranged circumferentially within the inner secondary air duct, and the third gas injector 7 is arranged circumferentially within the outer secondary air duct.

[0037] The second gas injector includes a second nozzle, designed in a linear shape and curved toward the center of the burner outlet to inject the ammonia directly into the flame core.

[0038] Specifically, the second gas injector further includes a second gas pipe, with a second nozzle mounted at the outlet of the second gas pipe.

[0039] The third gas injector includes a third nozzle 9, also designed in a linear shape and curved toward the center of the burner outlet to inject the ammonia directly into the flame core.

[0040] Specifically, the third gas injector further includes a third gas pipe, with a third nozzle 9 mounted at the outlet of the third gas pipe.

[0041] Four second gas injectors are arranged at equal intervals circumferentially, and four third gas injectors 7 are arranged at equal intervals circumferentially.

[0042] Specifically, four second gas injectors are arranged evenly spaced apart and four third gas injectors 7 are arranged evenly spaced apart, meaning that the angle between an axis of the second gas injector and an axis of the third gas injector is 45 degrees. This evenly spaced arrangement offers three key advantages. Firstly, it ensures uniformity in the ammonia injection coverage area, leading to a more balanced gas distribution across the entire region. Secondly, it effectively minimizes dead zones and overlapping areas in the gas injection, thereby enhancing overall injection efficiency and gas utilization. Thirdly, since each of the gas injectors bears an equal load, the reliability of the system is significantly improved, reducing the risk of damage to individual gas injectors due to overloading.

[0043] The burner further includes a heat exchange assembly. The heat exchange assembly includes a heat exchanger 1, an inlet end of which is connected to the gas main pipe 3, and an outlet end of which is connected to multiple gas branch pipes, with each of the gas branch pipes connected to the corresponding gas injector. The heat exchanger 1 is used to heat the gas, allowing the heated gas to be delivered to the respective gas injectors.

[0044] The heat exchanger 1 is arranged within the hot secondary air duct 2, and the ammonia is introduced into the heat exchanger 1 through the gas main pipe 3. The ammonia is heated from room temperature to 150° C. to 200° C. by utilizing heat from the secondary air, thus preheating the ammonia and increasing the temperature of the ammonia entering the furnace. This avoids issues of incomplete combustion or ignition difficulty at low temperatures, ensuring the sufficient combustion of the ammonia and further guaranteeing the stability and efficiency of the combustion process.

[0045] Specifically, the heat exchanger 1 is a finned tube heat exchanger equipped with an acoustic soot blower. In other embodiments, different types of the heat exchangers 1 can be selected based on specific application requirements.

[0046] Each of the gas branch pipes is connected to the corresponding gas injector, enabling individual control of the gas injectors. By switching the gas injectors on or off, it becomes convenient to control the gas injectors at different positions.

[0047] The heat exchange assembly includes a main pipe flow adjustment assembly 4 and a branch flow adjustment assembly 5. The main pipe flow adjustment assembly 4 is mounted on the gas main pipe 3 to regulate the gas flow within the gas main pipe 3. The branch flow adjustment assembly 5 is mounted on the gas branch pipe to regulate the gas flow within the gas branch pipe. Each of the gas injectors is equipped with an independent branch flow adjustment assembly 5, allowing precise adjustment of the ammonia distribution based on changes in boiler load. This enables accurate control of the ammonia flow. Under different load conditions, the ammonia supply can be optimized based on actual requirements, effectively controlling combustion quality and improving thermal efficiency.

[0048] Both the main pipe flow adjustment assembly 4 and the branch flow adjustment assembly 5 are flow control valves.

[0049] Through the arrangement of nine gas injectors, combined with the main pipe flow adjustment assembly 4 and the branch flow adjustment assembly 5, the issue of inflexible and imprecise ammonia flow adjustment is addressed. Conventionally, ammonia flow is controlled by a single nozzle, which cannot be adjusted accurately based on the actual load of the boiler. With the above arrangement, the ammonia flow may be precisely adjusted based on the load of the boiler, ensuring uniform mixing of ammonia with pulverized coal, thereby improving combustion efficiency and reducing pollutant generation.

[0050] At the end of the inner secondary air duct close to the nozzle, inner secondary air swirling blades 10 are mounted, while at the end of the outer secondary air duct close to the nozzle, outer secondary air swirling blades 11 are arranged. The rotating jets generated by the inner secondary air swirling blades and the outer secondary air swirling blades help form a stable recirculation zone. The inner and outer recirculation zones promote the mixing of fuel and air, enhancing combustion stability.

[0051] A primary air expansion cone 12 is mounted at the nozzle of the primary air duct, an inner secondary air expansion cone 13 is mounted at the nozzle of the inner secondary air duct, and an outer secondary air expansion cone 14 is mounted at the nozzle of the outer secondary air duct.

[0052] The primary air expansion cone 12 is a variable-diameter structure consisting of a first end and a second end. Its diameter gradually increases from the first end to the second end, and the primary air duct is connected to the primary air expansion cone 12 at the first end.

[0053] Similarly, the inner secondary air expansion cone 13 is a variable-diameter structure consisting of a first end and a second end. Its diameter gradually increases from the first end to the second end, and the inner secondary air duct is connected to the inner secondary air expansion cone 13 at the first end.

[0054] The outer secondary air expansion cone 14 is also a variable-diameter structure consisting of a first end and a second end. Its diameter gradually increases from the first end to the second end, and the outer secondary air duct is connected to the outer secondary air expansion cone 14 at the first end.

[0055] The arrangement of the primary air expansion cone 12, the inner secondary air expansion cone 13, and the outer secondary air expansion cone 14 effectively reduces the occurrence of vortices and turbulence in the fluid, allowing the fluid to enter the furnace more smoothly and minimizing energy losses.

[0056] It is easy for those skilled in the art to understand that the above-mentioned advantageous ways can be freely combined and superimposed without conflict.

[0057] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modifications, equivalent substitutions, and improvements made within the spirit and the principle of the present application should be included in the protection scope of the present application. The above descriptions are merely preferred embodiments of the present application. It should be noted that various improvements and modifications can be made by those skilled in the art without departing from the principles of the present application. These improvements and modifications should fall within the protection scope of the present application.

Claims

1. An ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner, comprising a primary air duct, an inner secondary air duct, and an outer secondary air duct arranged sequentially from inside to outside, wherein the primary air duct, the inner secondary air duct, and the outer secondary air duct are internally provided with gas injectors, respectively, the gas injector in the primary air duct is used to mix gas uniformly into primary air-coal powder flow, the gas injectors in the inner secondary air duct and the outer secondary air duct are arranged in a staggered configuration, with nozzles in both the gas injectors in the inner secondary air duct and the outer secondary air duct curving toward a center of a burner outlet, directing gas into flame core.

2. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 1, wherein the gas injector comprises a first gas injector (8), which is positioned inside the primary air duct and is coaxially arranged with the primary air duct.

3. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 2, wherein the gas injector further comprises a second gas injector and a third gas injector (7), wherein the second gas injector is arranged circumferentially within the inner secondary air duct, and the third gas injector (7) is arranged circumferentially within the outer secondary air duct.

4. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 3, wherein there are four second gas injectors arranged at equal intervals circumferentially, and there are four third gas injectors (7) arranged at equal intervals circumferentially.

5. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 1, further comprising a heat exchange assembly, wherein the heat exchange assembly comprises a heat exchanger (1), with an inlet end of the heat exchanger (1) connected to a gas main pipe (3), and an outlet end of the heat exchanger (1) connected to multiple gas branch pipes, each of which is respectively connected to the corresponding gas injector, and the heat exchanger (1) is used to heat the gas, ensuring that the heated gas is delivered into the gas injectors.

6. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 5, wherein the heat exchange assembly comprises a main pipe flow adjustment assembly (4) and a branch flow adjustment assembly (5), wherein the main pipe flow adjustment assembly (4) is arranged on the gas main pipe (3) to regulate the gas flow within the main pipe, and the branch flow adjustment assembly (5) is arranged on the gas branch pipe to regulate the gas flow within the branch pipe.

7. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 1, wherein the inner secondary air duct is provided with inner secondary air swirling blades (10) at an end close to the nozzle, and the outer secondary air duct is provided with outer secondary air swirling blades (11) at an end close to the nozzle.

8. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 1, wherein the nozzle of the primary air duct is provided with a primary air expansion cone (12).

9. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 1, wherein the nozzle of the inner secondary air duct is provided with an inner secondary air expansion cone (13).

10. The ammonia preheating flow-controllable low-nitrogen ammonia-coal co-firing burner according to claim 9, wherein the nozzle of the outer secondary air duct is provided with an outer secondary air expansion cone (14).

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