Combustor for mixing ammonia gas in a gas boiler

Abstract

The present application relates to a kind of burner of ammonia mixed burning in gas boiler, including total air inlet, burner outer wall of built-in combustion area and gas injection device, the burner also includes stable combustion disc, gas-ammonia injection device;The total air inlet is located at one end of burner outer wall, the combustion area is started from the self-expanding section in the burner;Stable combustion disc, gas injection device, gas-ammonia injection device are all installed in the import of combustion area;Gas-ammonia injection device is located in the inside of gas injection device, and the gas source of gas injection device and gas-ammonia injection device is communicated;The stable combustion disc is used to organize the flow direction of airflow and the distribution of oxidizing agent in combustion area, so that the outer layer of combustion area forms methane flame, wraps inner flame, forms backflow area in central region, and ignites ammonia in central region.Compared with prior art, the present application has the advantages that ammonia is more easily burned, NOx emission is not increased, etc.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of boiler combustion, in particular to a burner for mixing and burning ammonia gas in a gas boiler. BACKGROUND

[0002] Under the background of double carbon, hydrogen energy has become an important solution to replace fossil energy, but the storage and transportation conditions of hydrogen gas are extremely harsh. Hydrogen gas can be liquefied at 8 atmospheres at room temperature, which can realize large-scale storage and transportation of energy. Ammonia does not contain carbon, and the product of complete combustion is nitrogen and water, without any harm. The process of synthesizing ammonia is gradually mature, and ammonia energy can greatly reduce the emission of carbon dioxide by replacing fossil energy such as coal and natural gas, which is an important way to achieve the double carbon goal. However, ammonia is extremely difficult to burn, and the laminar flame propagation speed is less than one-fourth, so it is almost impossible to burn ammonia alone, so the method of mixing and burning ammonia is usually used.

[0003] Chinese patent CN202121753131.9 discloses a combustion system for mixing and burning ammonia gas in a cyclone burner, which comprises a cyclone burner, a first combustion chamber, a second combustion chamber and a plurality of ammonia nozzles. The first combustion chamber behind the coal or hydrocarbon fuel cyclone burner is used for mixing and burning ammonia gas. Under the condition that the total output of the fuel remains unchanged, the generation of CO2 can be greatly reduced, and the carbon emission can be reduced. By laying refractory material in the first combustion chamber, the heat absorption of the wall surface in this area is reduced, and the first combustion chamber is kept in a high-temperature environment, which is beneficial to ensure stable combustion of the flame after mixing with ammonia. At the same time, the staged air distribution of the cyclone burner and the second combustion chamber makes the local area near the ammonia nozzle of the first combustion chamber present a high-temperature and oxygen-poor reducing atmosphere, which can inhibit the generation of NOx and control the emission of NOx after mixing and burning ammonia.

[0004] However, the existing technology of mixing and burning ammonia gas in natural gas is complex in system design, which is not suitable for engineering application or modification of existing gas boilers. The NOx generated by incomplete combustion of ammonia gas is not monitored and feedback controlled. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art and provide a burner for mixing and burning ammonia gas in a gas boiler.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] According to one aspect of the present application, a burner for burning ammonia in a gas boiler is provided, comprising a total air inlet, a burner outer wall with a built-in combustion area, and a gas injection device, the burner further comprising a flame stabilizing disc, a gas-ammonia injection device; the total air inlet is located at one end of the burner outer wall, and the combustion area starts from the self-expanding section inside the burner; the flame stabilizing disc, the gas injection device, and the gas-ammonia injection device are all installed at the inlet of the combustion area; the gas-ammonia injection device is located inside the gas injection device, and the gas injection device is in communication with the gas source of the gas-ammonia injection device.

[0008] The flame stabilizing disc is used to organize the flow direction of the gas flow and the distribution of the oxidizer in the combustion area, so that the outer layer of the combustion area forms a methane flame, which wraps the inner layer flame, and a backflow area is formed in the central area, igniting the ammonia gas in the central area.

[0009] As a preferred technical solution, the flame stabilizing disc comprises an outer flame stabilizing disc and an inner flame stabilizing disc; the outer flame stabilizing disc is installed outside the inner flame stabilizing disc.

[0010] As a preferred technical solution, the outer flame stabilizing disc is provided with an outer spiral vane, an outer flame stabilizing disc opening, and an outer flame stabilizing disc disturbance device on the side facing the combustion area.

[0011] As a preferred technical solution, the inner flame stabilizing disc is provided with an inner spiral vane on the side facing the combustion area.

[0012] As a preferred technical solution, the gas-ammonia injection device comprises an ammonia inlet, a gas-ammonia annular mixer, a gas-ammonia injection port, and a central bluff body; the ammonia inlet is connected to the gas-ammonia annular mixer, the gas-ammonia annular mixer is connected to the gas-ammonia injection port, and the central bluff body is installed inside the gas-ammonia injection port.

[0013] As a preferred technical solution, the burner further comprises an air staging device, which is arranged in a circular array on the burner outer wall; the air staging device comprises an air staging outlet and an air staging inlet; the air staging outlet is arranged on the burner outer wall and communicates with the combustion area; the air staging inlet is arranged on the total air inlet outer wall and communicates with the total air inlet.

[0014] As a preferred technical solution, the gas-ammonia injection device, the flame stabilizing disc, and the air staging device are independent modules that can be matched with existing burners.

[0015] As a preferred technical solution, the gas injection device comprises a main gas inlet, a main fuel annular mixer, and a main fuel injection port connected in sequence, and part of the gas enters the gas-ammonia injection device from a branch pipe.

[0016] As a preferred technical scheme, the burner further comprises an intelligent flow control device, which controls the flow rates of the gas, the ammonia gas and the air by using an intelligent calculation method to keep the total combustion power stable.

[0017] As a preferred technical scheme, the intelligent flow control device monitors the ammonia escape rate and the NOx emission in real time, and if the ammonia escape rate is too high, the ammonia gas blending ratio or the air staging ratio is reduced, and if the NOx emission is too high, the air staging is increased and the oxygen ratio near the nozzle is reduced.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1) The central region of the present application mixes the ammonia gas and part of the methane to re-enter the combustion chamber to lower the ignition point, the methane flame outside the combustion region wraps the methane-ammonia gas flame inside, and the stable combustion disc with the cyclone device and the central bluff body can form a larger recirculation zone in the center to ignite the combustible gas in the central region, so that the ammonia gas is more easily combusted.

[0020] 2) The present application allows the air to enter near the nozzle to form a fuel-rich condition at the initial stage of combustion, reducing the generation of NOx. The air injection port is arranged downstream to allow the methane and ammonia gas to be completely combusted. The ammonia escape rate and the NOx emission are monitored in real time at the outlet, and the fuel ratio and the air staging flow rate are adjusted. By using the above method, the present application can effectively reduce the NOx emission under the condition that the ammonia gas is completely combusted.

[0021] 3) The present application is designed as an independent module, which can be modified on the existing gas boiler, the mixing method of the ammonia gas into the central region is changed, the main structure of the burner remains unchanged, and the burner is convenient to use and popularize. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a sectional structure schematic view of the present application;

[0023] Figure 2 is a front view structure schematic view of the burner in the present application;

[0024] Figure 3 is a partial structure schematic view of the burner in the present application;

[0025] Figure 4 is a structure schematic view of the outer stable combustion disc in the present application;

[0026] Figure 5 is a disassembly structure schematic view of the present application.

[0027] 1. Outer combustion stabilizer disc, 2. Main fuel nozzle, 3. Inner combustion stabilizer disc, 4. Gas-ammonia nozzle, 5. Central blunt body, 6. Staged air outlet, 7. Main air inlet, 8. Burner outer wall, 9. Staged air inlet, 10. Main fuel inlet, 11. T-junction and valve, 12. Combustion zone, 13. Main fuel annular mixer, 14. Ammonia inlet, 15. Gas-ammonia annular mixer, 16. Inner swirl vane, 17. Outer swirl vane, 18. Outer combustion stabilizer disc opening, 19. Outer combustion stabilizer disc turbulence device. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0029] like Figure 1 As shown, a burner for ammonia co-firing in a gas-fired boiler includes a total air inlet 7, an outer wall 8 of the burner with an internal combustion zone 12, and a gas injection device. The burner also includes a combustion stabilizer, a gas-ammonia injection device, and an air grading device. The total air inlet 7 is located at one end of the outer wall 8 of the burner, and the combustion zone 12 is located inside the burner starting from the expansion section. The inner and outer combustion stabilizers, the gas injection device, and the gas-ammonia injection device are all installed at the inlet of the combustion zone. The gas-ammonia injection device is located inside the gas injection device, and the gas source of the gas injection device is connected to that of the gas-ammonia injection device.

[0030] The combustion stabilizing disc is used to organize the flow direction of the airflow and the distribution of the oxidant in the combustion zone 12, so that the outer layer of the combustion zone 12 forms a methane flame, which wraps the inner layer of methane-ammonia flame, and a recirculation zone is formed in the central region to ignite the ammonia in the central region.

[0031] The combustion stabilizing disc includes an outer combustion stabilizing disc 1 and an inner combustion stabilizing disc 3; the outer combustion stabilizing disc 1 is installed outside the inner combustion stabilizing disc 3, the diameter of the outer combustion stabilizing disc is 3 times the diameter of the inner combustion stabilizing disc, and the outer diameter of the inner combustion stabilizing disc is similar to the inner diameter of the outer combustion stabilizing disc.

[0032] The outer stabilizing disk 1 is provided with an outer swirl vane 17, an outer stabilizing disk opening 18, and an outer stabilizing disk turbulence device 19 on the side facing the combustion zone 12. The swirl vane, opening, and turbulence device are arranged in a circumferential array on the stabilizing disk. The inner swirl vane and the stabilizing disk turbulence device are arranged alternately, with 24 of them. The angle between the swirl vane and the disk surface is set to 50°.

[0033] The inner side stable combustion disc 3 is provided with inner side swirl vanes 16 on the side facing the combustion area 12, the gas-ammonia injection device passes through the stable combustion disc, the swirl vanes are circumferentially arranged on the stable combustion disc, and eight swirl vanes are arranged, and the angle between the swirl vanes and the disc surface is 50°.

[0034] The gas-ammonia injection device comprises an ammonia inlet 14, a gas-ammonia annular mixer 15, a gas-ammonia nozzle 4 and a central bluff body 5; the ammonia inlet 14 is connected with the gas-ammonia annular mixer 15, the gas-ammonia annular mixer 15 is connected with the gas-ammonia nozzle 4, and the central bluff body 5 is installed inside the gas-ammonia nozzle 4.

[0035] The burner further comprises air staging devices which are circumferentially arranged outside the burner, and three air staging devices are arranged; the air staging devices comprise staging air outlets 6 and staging air inlets 9; the staging air outlets 6 are arranged on the outer wall of the burner and communicate with the combustion area 12, and the staging air inlets 9 are arranged on the outer wall of the total air inlet 7 and communicate with the total air inlet 7.

[0036] After the gas and ammonia are mixed, the mixing ratio of ammonia is about 50%-80%, and the total ammonia ratio (heat value ratio) of the burner is about 10%-30%.

[0037] The gas injection device comprises a main gas inlet 10, a main fuel annular mixer 13 and a main fuel nozzle 2 which are connected in sequence.

[0038] The above-mentioned gas is generally selected from methane. The core points of the present application are as follows:

[0039] 1. The stable combustion disc with swirl devices can organize the flow direction of the gas flow and the distribution of the oxidant in the combustion chamber, the outer layer of the combustion area forms a methane flame which wraps the inner layer of the methane-ammonia flame, a larger recirculation zone is formed in the center, and the combustible gas in the central area is ignited;

[0040] 2. Since ammonia is difficult to ignite, the ammonia mixed with part of the methane is further introduced into the combustion chamber before entering the combustion area, so as to further improve the combustion reaction speed and make the ammonia completely combustible;

[0041] 3. The air entering a part near the nozzle forms a fuel-rich condition in the initial stage of combustion, so as to reduce the emission of NOx, and the air injection inlet is arranged in the downstream, so that the gas and ammonia are completely combusted;

[0042] 4. The ammonia escape rate and the emission of NOx are monitored in real time at the outlet, if the ammonia escape rate is too high, the ammonia blending ratio is reduced or the internal ammonia blending ratio is reduced, if the emission of NOx is too high, the air staging is increased, and the oxygen ratio near the nozzle is reduced;

[0043] 5. Intelligent flow control device, due to the different heat values of methane and ammonia, the total combustion power is kept stable by using intelligent calculation method, and the air flow is adjusted according to different combustion conditions and ambient temperatures;

[0044] 6. The existing gas boiler is modified, mainly the ammonia mixing entering mode at the center position is changed, and the main structure of the burner is unchanged.

[0045] The specific principle of the present application is as follows:

[0046] The burner provided by the present application mainly comprises four parts, as shown in the figure, from left to right, they are a burner shell, a gas injection device, a methane-ammonia mixed fuel injection device and a stable combustion disc. Figure 1 Air enters from the leftmost side, most of the air directly enters the combustion area, and about 20% of the air enters the rear part of the combustion chamber through the three air staging guide tubes on the outside to form air staging for combustion. The gas enters the annular distribution pipe from the main fuel pipe, is distributed to the six uniformly arranged jet pipes (main fuel injection ports), is mixed with air, and forms a stable flame in the outer layer. The methane-ammonia fuel is mixed through different pipelines and then enters the annular distribution pipe (methane-ammonia annular mixer), and then enters the central combustion area to burn in the flame backflow, and the center is a blunt body to form a stable backflow area. The stable combustion disc can distribute the oxygen distribution of each area and form a swirling flame to stabilize combustion.

[0047] The internal structure comprises a total air inlet 7, an air staging inlet 9 and a staging air outlet 6, a combustion area 12, the combustion area starts from the expansion section of the shell to form a stable flame and a flame backflow area, part of the air entering from the air inlet enters the rear part of the combustion area through the air staging channel, the gas injection device comprises a main fuel inlet 10 and a main fuel injection port 2, most of the gas is sprayed out from the main fuel injection port, the ammonia injection device comprises an ammonia inlet 14 and a methane-ammonia injection port, and a small part of the gas is mixed with ammonia in the pipeline and then sprayed into the methane-ammonia injection port.

[0048] The part of the air entering the front part of the combustion area forms a fuel-rich condition in the initial stage of combustion to reduce NOx emission, and the air staging injection inlet is arranged downstream to make the gas fully burn;

[0049] The ammonia escape rate and NOx emission are monitored in real time at the outlet of the burner, if the ammonia escape rate is too high, the ammonia blending ratio is reduced or the air staging ratio is reduced, if the NOx emission is too high, the air staging ratio is increased and the oxygen ratio near the injection port is reduced;

[0050] The intelligent flow control device, due to the different heat values of methane and ammonia, the flow rates of methane and ammonia are synchronously adjusted to keep the total combustion power stable, and the air flow is adjusted according to different combustion conditions and ambient temperatures.

[0051] Air is distributed by the stable combustion disc to form the outer methane combustion area and the inner ammonia-doped combustion area, the outer stable combustion area wraps the inner ammonia-doped area to ensure complete combustion of ammonia gas; ammonia gas is mixed with part of methane before entering the combustion area to reduce the ignition temperature and ensure that ammonia gas can be ignited and completely combusted;

[0052] A stable central recirculation zone is formed by the central bluff body and the stable combustion disc, and the high-temperature flue gas in the recirculation zone volatilizes the methane-ammonia mixed gas to ensure complete combustion of ammonia gas.

[0053] In addition, the methane-ammonia injection device, the stable combustion disc and the air staging device are relatively independent modules, and the main structure of the burner can remain unchanged during modification of the existing burner.

[0054] The outer side swirl vanes on the stable combustion disc are arranged alternately with the stable combustion disc turbulence device, and the inner side swirl vanes are arranged alternately with the stable combustion disc turbulence device.

[0055] The above describes the preferred embodiments of the present application in detail. It should be understood that those skilled in the art can make many modifications and changes without creative labor based on the concept of the present application. Therefore, any technical solution obtained by logical analysis, reasoning or limited experiment based on the existing technology according to the concept of the present application shall be within the protection scope defined by the claims.

Claims

1. A burner for co-firing ammonia in a gas-fired boiler, comprising a total air inlet (7), an outer wall (8) of a burner with an internal combustion zone (12), and a gas injection device, characterized in that, The burner also includes a stabilizing plate and a gas-ammonia injection device; the total air inlet (7) is located at one end of the outer wall (8) of the burner, and the combustion zone (12) is located inside the burner starting from the expansion section; the stabilizing plate, the gas injection device, and the gas-ammonia injection device are all installed at the inlet of the combustion zone (12); the gas-ammonia injection device is located inside the gas injection device, and the gas source of the gas injection device is connected to that of the gas-ammonia injection device; The combustion stabilizing disc is used to organize the flow direction of the airflow and the distribution of the oxidant in the combustion zone (12), so that the outer layer of the combustion zone (12) forms a methane flame, which wraps the inner flame and forms a recirculation zone in the central region, igniting the ammonia in the central region; The gas-ammonia injection device includes an ammonia inlet (14), a gas-ammonia annular mixer (15), a gas-ammonia nozzle (4), and a central blunt body (5); the ammonia inlet (14) is connected to the gas-ammonia annular mixer (15), the gas-ammonia annular mixer (15) is connected to the gas-ammonia nozzle (4), and the central blunt body (5) is installed inside the gas-ammonia nozzle (4); The burner also includes an air grading device, which is arranged in a circumferential array on the outer wall of the burner. The air grading device includes an air grading outlet (6) and an air grading inlet (9). The air grading outlet (6) is located on the outer wall of the burner and communicates with the combustion zone (12). The air grading inlet (9) is located on the outer wall of the main air inlet (7) and communicates with the main air inlet (7). The burner also includes an intelligent flow control device, which uses intelligent calculation methods to control the flow rates of fuel gas, ammonia, and air, maintaining a stable total combustion power while synchronously adjusting the flow rates of methane and ammonia. Simultaneously, it adjusts the air flow rate according to different combustion conditions and ambient temperature. The intelligent flow control device monitors the outlet ammonia slip rate and NOx emissions in real time. If the ammonia slip rate is too high, it reduces the ammonia co-firing ratio or the air staging ratio. If NOx emissions are high, it increases the air staging ratio and reduces the oxygen ratio near the nozzle.

2. The burner for co-firing ammonia in a gas-fired boiler according to claim 1, characterized in that, The combustion stabilizing plate includes an outer combustion stabilizing plate (1) and an inner combustion stabilizing plate (3); the outer combustion stabilizing plate (1) is installed on the outside of the inner combustion stabilizing plate (3).

3. A burner for co-firing ammonia in a gas-fired boiler according to claim 2, characterized in that, The outer stabilizing plate (1) is provided with an outer swirl vane (17), an outer stabilizing plate opening (18), and an outer stabilizing plate turbulence device (19) on the side facing the combustion area (12).

4. A burner for co-firing ammonia in a gas-fired boiler according to claim 2, characterized in that, The inner stabilizing plate (3) has an inner swirl vane (16) on the side facing the combustion zone (12).

5. A burner for co-firing ammonia in a gas-fired boiler according to claim 1, characterized in that, The gas-ammonia injection device, the combustion stabilizer, and the air grading device are independent modules that can be used with existing burners.

6. A burner for co-firing ammonia in a gas-fired boiler according to claim 1, characterized in that, The gas injection device includes a main gas inlet (10), a main fuel annular mixer (13), and a main fuel nozzle (2) connected in sequence. Part of the gas enters the gas-ammonia injection device from a branch pipe.

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