Ammonia Combustion Reduction Low NOx Emission Continuous Heating Furnace and Control Method

Abstract

This invention discloses a continuous heating furnace for low NOx emissions through ammonia combustion reduction and its control method. The furnace includes a kiln body with a discharge end and a feed end. A conveying channel is provided within the kiln body. From the feed end to the discharge end, the kiln body sequentially comprises a preheating section and a high-temperature firing section. The high-temperature firing section is equipped with multiple burners, including an ammonia burner, a natural gas burner, and an ammonia combustion reduction lance. The high-temperature firing section is further divided into an initial heating section and a high-temperature section. The ammonia combustion reduction lance is located in the initial heating section, while the ammonia burner and natural gas burner are located in the high-temperature section. A flue gas outlet is located at the material inlet end of the preheating section. The flue gas generated during combustion flows in the opposite direction to the ceramic blank along the furnace length, forming a counter-current heat exchange flow. In the initial heating section, unburned ammonia acts as a reducing agent to reduce nitrogen oxides present in the combustion flue gas, reducing nitrogen oxide production. Furthermore, the heat from the flue gas is utilized to heat the material in the preheating section.

Description

Technical Field

[0001] This invention relates to the field of combustion technology, and in particular to a continuous heating furnace and kiln with low NOx emissions from ammonia combustion reduction, and its control method. Background Technology

[0002] Continuous heating furnaces are essential large-scale key equipment for high-temperature heating or firing of raw materials, products, and fuels in the production of ceramics, cement, steel, non-ferrous metals, and other materials.

[0003] Currently, hydrogen energy is considered a crucial direction for the development of the global energy structure to achieve carbon neutrality. Ammonia, as a highly efficient zero-carbon carrier of hydrogen, has a hydrogen content as high as 17.6% and can be liquefied at 8 atm at room temperature. Its production and storage supply chain is mature, and liquid ammonia has an energy density of 18.8 MJ / kg, making it the most promising zero-carbon fuel to replace traditional fossil fuels in industrial thermal equipment such as power boilers, industrial furnaces, internal combustion engines, and gas turbines. Ammonia has the advantage of being carbon-free; the only emissions after complete combustion are water and nitrogen. Furthermore, as a carbon-free fuel, ammonia also has advantages such as high calorific value and ease of storage. From the perspective of reducing carbon emissions, it is suitable as a new generation fuel for continuous heating furnaces in ceramics, cement, and metal products. However, when ammonia is used as a heating furnace fuel, its poor combustion stability and the presence of nitrogen in the fuel lead to a significant increase in nitrogen oxide emissions during combustion. Unless selective non-catalytic reduction (SNCR) or selective catalytic reduction (SCR) flue gas aftertreatment methods are adopted at increased costs, it will cause significant environmental pollution. Summary of the Invention

[0004] The purpose of this invention is to provide a continuous heating furnace and kiln with low NOx emissions from ammonia combustion reduction and control method, so as to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0005] The technical solution adopted to solve the above-mentioned technical problems is as follows:

[0006] A continuous heating furnace for low NOx emissions through ammonia combustion reduction includes a kiln body with a discharge end and a feed end. A conveying channel is provided within the kiln body. From the feed end to the discharge end, the kiln body sequentially includes a preheating section and a high-temperature firing section. The high-temperature firing section is equipped with multiple burners, including an ammonia burner, a natural gas burner, and an ammonia combustion reduction lance. The high-temperature firing section also includes an initial heating section and a high-temperature section. The ammonia combustion reduction lance is located in the initial heating section, while the ammonia burner and the natural gas burner are located in the high-temperature section. A flue gas outlet is provided at the material inlet end of the preheating section.

[0007] The beneficial effects of this invention are:

[0008] The ceramic tile blanks are fed from the inlet and conveyed sequentially through the conveyor channel into the preheating section of the kiln for drying and preheating. They then enter the high-temperature firing section where they are fired by burners. Finally, they are cooled and discharged from the outlet, completing the sintering process. Multiple burners are arranged on both sides of the kiln in the high-temperature firing section to supply fuel and ensure that the ceramic blanks receive sufficient heat to reach the required firing temperature.

[0009] The flue gas generated by combustion flows in the opposite direction to the direction of the ceramic blank along the length of the furnace, forming a counter-current heat exchange flow. In the initial heating section, unburned ammonia acts as a reducing agent to reduce the nitrogen oxides present in the combustion flue gas, thereby reducing the generation of nitrogen oxides. Furthermore, the heat of the flue gas is used to heat the material in the preheating section.

[0010] In the high-temperature firing section of the kiln, a combination of ammonia burners and natural gas burners is used for combustion. Nitrogen oxides are reduced through incomplete combustion of ammonia with a low air coefficient and partial decomposition of ammonia into hydrogen and nitrogen molecules. Then, secondary low-NOx complete combustion is achieved through oxygen-rich combustion of natural gas with a high air coefficient. In the initial heating section, an even lower air coefficient incomplete combustion method is used to simultaneously provide heat and selectively non-catalytically reduced nitrogen oxides. This method can significantly reduce nitrogen oxide emissions during ammonia combustion.

[0011] As a further improvement to the above technical solution, multiple burners are arranged alternately on both sides of the conveying channel, and the ammonia burner and the natural gas burner are arranged alternately on the same side of the conveying channel.

[0012] The staggered arrangement on both sides of the conveying channel can evenly heat the combustion chamber of the kiln. The staggered arrangement on the same side helps the excess oxygen in the natural gas burner to further burn off the unburned fuel in the ammonia burner in the high-temperature section.

[0013] As a further improvement to the above technical solution, the air coefficient of the natural gas burner is 1.1~1.3, and the air coefficient of the ammonia burner is 0.85~1.0. Ammonia fuel produces less nitrogen oxides when the air coefficient is in the range of 0.85~1.0, while natural gas combustion, with an air coefficient of 1.1~1.3, allows for complete combustion with minimal nitrogen oxide production, thus reducing nitrogen oxide generation.

[0014] As a further improvement to the above technical solution, the air coefficient of the ammonia combustion reduction nozzle is 0.5~0.95. Utilizing the combustion characteristics of ammonia fuel within the air coefficient range of 0.5~0.95, the reducing atmosphere created by the oxygen-deficient combustion of the ammonia burner in this initial heating section facilitates the reduction reaction of nitrogen oxides in the flue gas, thus significantly reducing the amount of nitrogen oxides generated during ammonia combustion.

[0015] As a further improvement to the above technical solution, a cooling section is also provided near the discharge end. The cooling section is equipped with a cooling structure to cool and lower the temperature of the fired high-temperature ceramic tile.

[0016] As a further improvement to the above technical solution, the wall of the kiln body is an insulated furnace wall, which plays a role in heat insulation.

[0017] As a further improvement to the above technical solution, the temperature of the initial heating section is controlled between 800 and 1000 degrees Celsius, and the temperature of the high-temperature section is controlled above 1000 degrees Celsius. When the initial heating section temperature is between 800 and 1000 degrees Celsius, the reducing atmosphere formed by the oxygen-deficient combustion of the ammonia burner facilitates the reduction reaction of nitrogen oxides in the flue gas inside the furnace, thus greatly reducing the amount of nitrogen oxides generated during ammonia combustion.

[0018] As a further improvement to the above technical solution, the temperature of the initial heating section is controlled at 900 degrees Celsius. At around 900 degrees Celsius, the initial heating section uses the incomplete combustion method of the ammonia combustion reduction torch. The reducing atmosphere formed by the oxygen-deficient combustion of the ammonia burner makes it easier to carry out the reduction reaction of nitrogen oxides in the flue gas in the furnace, thus greatly reducing the amount of nitrogen oxides generated by ammonia combustion.

[0019] This invention provides a control method applicable to any of the above-described ammonia combustion reduction low-NOx emission continuous heating furnaces:

[0020] Control the flow of flue gas from the high-temperature section to the initial heating section;

[0021] Control the air coefficients of the ammonia combustion reduction spray gun, ammonia burner, and natural gas burner, and ensure that the temperature of the high-temperature section reaches above 1000 degrees Celsius, while the initial heating temperature is between 800 and 1000 degrees Celsius.

[0022] This invention uses a combination of ammonia and natural gas for high-temperature combustion in the furnace. By controlling the combustion air coefficient of different burners, the amount of nitrogen oxides generated is controlled. At the same time, the incomplete combustion method of the ammonia burner is used in the initial heating section at about 900°C. This ensures that the kiln body is heated and that nitrogen oxides in the flue gas are reduced. It does not involve any changes to the structure of the furnace body. The method is simple and clear and the effect is obvious.

[0023] As a further improvement to the above technical solution, the air coefficient of the ammonia combustion reduction spray gun is controlled at 0.5~0.95, the air coefficient of the ammonia burner is controlled at 0.85~1.0, and the air coefficient of the natural gas burner is controlled at 1.1~1.3.

[0024] Ammonia fuel produces the least amount of nitrogen oxides when the air coefficient is in the range of 0.85 to 1.0. At the same time, natural gas combustion can achieve complete combustion with oxygen in the range of 1.1 to 1.3, and the amount of nitrogen oxides produced is very small. This allows the unburned components in the ammonia burner and the excess oxygen after the natural gas burner to combine in the furnace for secondary combustion. At the same time, setting up an ammonia combustion reduction lance in the initial heating section with a flue gas temperature of about 900°C and controlling its air coefficient in the range of 0.5 to 0.95 can not only provide heat to this heating section, but also provide unburned residual ammonia to combine with nitrogen oxides in the flue gas generated in the high-temperature firing section for nitrogen oxide reduction reaction. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0026] Figure 1 This is a schematic diagram of an embodiment of a continuous heating furnace for ammonia combustion reduction with low NOx emissions provided by the present invention.

[0027] Figure 2 yes Figure 1 Cross-sectional view at point AA;

[0028] Figure 3 yes Figure 1 Cross-sectional view of section BB in the diagram. Attached image description:

[0030] Kiln body 100, discharge end 110, feed end 120, conveying channel 130, preheating section 140, high temperature firing section 150, initial heating section 151, high temperature section 152, cooling section 160, flue gas outlet 170;

[0031] Ammonia burner 200;

[0032] 300 natural gas burner;

[0033] Ammonia combustion reduction spray gun 400. Detailed Implementation

[0034] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0035] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0036] In the description of this invention, if there are words such as "several", they mean one or more, "multiple" means two or more, "greater than", "less than", "exceeding" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself.

[0037] In the description of this invention, unless otherwise explicitly defined, terms such as "setting," "installing," and "connecting" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0038] To address the problem of large amounts of nitrogen oxides generated in continuous heating furnaces for ceramics, cement, metals, and other materials, referencing Figures 1 to 3 This invention discloses a continuous heating furnace and kiln with low NOx emissions from ammonia combustion reduction, and its control method. These methods can be applied to ceramic tunnel kilns, cement continuous kilns, and metal continuous heating furnaces. Taking ceramic sintering as an example, and using NOx (nitrogen oxides) as an example, the following embodiments are provided:

[0039] In this embodiment, a continuous heating furnace for low NOx emissions from ammonia combustion reduction includes a kiln body 100. The combustion chamber within the kiln body 100 extends horizontally. The left end of the kiln body 100 is the feed end 120, and the right end is the discharge end 110. A conveying channel 130 is provided within the kiln body 100. In this embodiment, the conveying channel 130 is a roller conveyor. In other embodiments, other conveying structures capable of material movement, such as belt conveyors, can be used. These structures must be able to convey ceramic tiles and also be heat-resistant. From the feed end 120 to the discharge end 110, the kiln body 100 is sequentially provided with a preheating section 140, a high-temperature firing section 150, and a cooling section 160. The ceramic tile blanks are fed from the feeding end 120 and conveyed sequentially through the conveying channel 130 into the preheating section 140 of the kiln body 100 for drying and preheating. Then they enter the high-temperature firing section 150 where they are fired by the burner. Finally, they are cooled through the cooling section 160 and discharged from the discharge end 110 into the kiln body 100, completing the sintering process.

[0040] The walls of the kiln body 100 are insulated furnace walls, serving a heat-insulating function. In some embodiments, they may also be made of high-temperature resistant metal materials.

[0041] The preheating section 140 is used to preheat the ceramic tiles for drying. Other heating structures can be installed, or the waste heat of the flue gas can be used for preheating to make full use of the heat of the flue gas.

[0042] The high-temperature firing section 150 is equipped with multiple burners, including an ammonia burner 200, a natural gas burner 300, and an ammonia combustion reduction lance 400. The ammonia combustion reduction lance 400 is also a burner, using ammonia fuel, but because the air coefficient is controlled during combustion, its primary function is the reduction reaction; hence, it is referred to as the ammonia combustion reduction lance 400 for better distinction. Multiple burners are arranged on both sides of the kiln body 100 of the high-temperature firing section 150 to supply fuel for combustion, ensuring the ceramic blanks receive sufficient heat to reach the specific firing temperature requirements.

[0043] Furthermore, multiple burners are arranged in a staggered manner on both sides of the conveying channel 130, from... Figure 1 From the side view, multiple burners are arranged at equal intervals in the left-right direction. Figure 2 In the cross-sectional view, two burners are respectively installed on the front and rear side walls of the kiln body 100 on the same section. The two burners are arranged opposite each other to heat the combustion chamber of the kiln body 100. The present invention does not impose specific limitations on the number and position of the burners, and those skilled in the art can make changes according to the actual situation.

[0044] Furthermore, in order to control the nitrogen oxides produced during ammonia combustion, refer to Figure 3 The high-temperature firing section 150 is provided with an initial heating section 151 and a high-temperature section 152. The ammonia combustion reduction spray gun 400 is located in the initial heating section 151. It can be seen that the length of the high-temperature section 152 is greater than the length of the initial heating section 151. The ammonia burner 200 and the natural gas burner 300 are located on the front and rear side walls of the kiln body 100 where the high-temperature section 152 is located.

[0045] Ammonia fuel is burned in the ammonia burner 200 in an incomplete combustion mode with a low air coefficient, which can effectively control the nitrogen oxides generated during the ammonia combustion process; the natural gas burner 300 is burned completely in an over-oxygen combustion mode with a high air coefficient, and the excess oxygen in the high-temperature calcination section 150 combustion chamber helps to further burn the unburned fuel in the ammonia burner 200.

[0046] Furthermore, the ammonia burner 200 and the natural gas burner 300 are staggered on the same side of the conveying channel 130, which helps the excess oxygen in the natural gas burner 300 to further burn the unburned fuel in the ammonia burner 200 in the high-temperature section 152.

[0047] Ammonia combustion reduction lances 400 are installed on both sides of the preheating section 140 of the kiln body 100. The ammonia combustion reduction lances 400 have both combustion and nitrogen oxide reduction functions. The ammonia combustion reduction lances 400 perform incomplete combustion with a lower air coefficient. In addition to providing the heat required by the high-temperature firing section 150, the unreacted hydrogen-containing combustibles can reduce the nitrogen oxides generated during the combustion process of other furnace sections flowing through this section under the appropriate temperature and reactant concentration conditions of the preheating section 140.

[0048] The preheating section 140 has a flue gas outlet 170 at the material inlet end, and the flue gas outlet 170 is connected to a flue gas pipe. The flue gas generated by combustion flows in the opposite direction to the direction of the ceramic billet along the furnace length, forming a counter-current heat exchange flow. In the initial heating section 151, unburned ammonia acts as a reducing agent to reduce the nitrogen oxides present in the combustion flue gas, thereby reducing the generation of nitrogen oxides. Furthermore, the heat of the flue gas is used to heat the material in the preheating section 140.

[0049] A cooling section 160 is also provided near the discharge end 110. The cooling section 160 is equipped with a cooling structure to cool and lower the temperature of the fired high-temperature ceramic tiles. The cooling section 160 is also equipped with a conveying channel 130. The cooling section 160 can be divided into a rapid cooling section and a slow cooling section. The cooling structure is a structure that helps to cool the ceramic tiles, such as a cooling air circulation system, which continuously circulates cold air at the cooling end to achieve a cooling effect.

[0050] In the high-temperature firing section 150 of the kiln body 100, a combination of ammonia burner 200 and natural gas burner 300 is used for combustion. Nitrogen oxides are reduced through incomplete combustion of ammonia with a low air coefficient and partial decomposition of ammonia into hydrogen and nitrogen molecules. Then, secondary low-NOx complete combustion is achieved through oxygen-rich combustion of natural gas with a high air coefficient. In the initial heating section 151, an even lower air coefficient incomplete combustion method is used to simultaneously achieve heating and selective non-catalytic reduction of nitrogen oxides. This method can significantly reduce nitrogen oxide emissions during the ammonia combustion process.

[0051] Furthermore, the air coefficient of the natural gas burner 300 is 1.1~1.3, and the air coefficient of the ammonia burner 200 is 0.85~1.0. Ammonia fuel produces less nitrogen oxides when the air coefficient is around 0.95, while natural gas combustion, with an air coefficient of around 1.3, allows for complete combustion with excess oxygen and produces very little nitrogen oxides, thus reducing nitrogen oxide generation.

[0052] Furthermore, the air coefficient of the ammonia combustion reduction lance 400 is 0.5~0.95. Utilizing the combustion characteristics of ammonia fuel at an air coefficient of around 0.5, the reducing atmosphere created by the oxygen-deficient combustion of the ammonia burner 200 in the initial heating section 151 facilitates the reduction reaction of nitrogen oxides in the flue gas, thus greatly reducing the amount of nitrogen oxides generated during ammonia combustion.

[0053] Furthermore, the temperature of the initial heating section 151 is controlled between 800 and 1000 degrees Celsius, and the temperature of the high-temperature section 152 is controlled above 1000 degrees Celsius. When the initial heating section temperature is between 800 and 1000 degrees Celsius, the reducing atmosphere formed by the oxygen-deficient combustion of the ammonia burner facilitates the reduction reaction of nitrogen oxides in the flue gas inside the furnace, thus greatly reducing the amount of nitrogen oxides generated during ammonia combustion.

[0054] Furthermore, the temperature of the initial heating section 151 is controlled at 900 degrees Celsius. At around 900 degrees Celsius, the initial heating section 151 uses the incomplete combustion method of the ammonia combustion reduction torch 400. The reducing atmosphere formed by the oxygen-deficient combustion of the ammonia burner makes it easier to carry out the reduction reaction of nitrogen oxides in the flue gas in the furnace, thus greatly reducing the amount of nitrogen oxides generated by ammonia combustion.

[0055] This invention relates to a continuous heating furnace for low NOx emissions through ammonia combustion reduction. Along its length, the ceramic tile material undergoes a heating process from low to high temperature from the inlet to the outlet. The combustion flue gas exchanges heat counter-currently with the ceramic tile material as it cools from high to low temperatures. In the high-temperature heating section above 1000°C, a combined combustion method of low-air-coefficient ammonia decomposition combustion and high-air-coefficient ammonia-free fuel combustion is used to control NOx generation. In the medium-temperature heating section at approximately 900°C, a low-air-coefficient ammonia burner with both ammonia combustion and reduction functions is used. On one hand, it provides heat; on the other hand, unburned ammonia acts as a reducing agent to reduce NOx present in the combustion flue gas. Throughout the system, ammonia is used both as fuel and as a reducing agent, eliminating the need for additional selective non-catalytic reduction (SNCR) or selective catalytic reduction (SCR) devices that require ammonia injection or urea for flue gas aftertreatment. Furthermore, it exhibits strong adaptability to combustion temperature processes and very low NOx generation, effectively reducing the operating and equipment costs associated with other technologies used to achieve the same low-NOx emission target with ammonia fuel.

[0056] This invention provides a control method for a continuous heating furnace with low NOx emissions from ammonia combustion reduction, applicable to any of the above-mentioned aspects:

[0057] Control the flow of flue gas from the high-temperature section 152 to the initial heating section 151;

[0058] Control the air coefficients of the ammonia combustion reduction spray gun 400, ammonia burner 200, and natural gas burner 300, and ensure that the temperature of the high-temperature section 152 reaches above 1000 degrees Celsius, with the initial heating temperature between 800 and 1000 degrees Celsius.

[0059] This invention uses a combination of ammonia and natural gas in the high-temperature section 152 of the furnace for combustion. By controlling the combustion air coefficient of different burners, the amount of nitrogen oxides generated is controlled. At the same time, at around 900°C, the initial heating section uses the incomplete combustion method of ammonia burners, which ensures 100% heating of the kiln body and reduces nitrogen oxides in the flue gas. This does not involve any changes to the structure of the furnace body. The method is simple and clear, and the effect is obvious.

[0060] Furthermore, the air coefficient of the ammonia combustion reduction spray gun 400 is controlled to be 0.5~0.95, the air coefficient of the ammonia burner 200 is controlled to be 0.85~1.0, and the air coefficient of the natural gas burner 300 is controlled to be 1.1~1.3.

[0061] Specifically, ammonia fuel produces the least amount of nitrogen oxides when the air coefficient is around 0.95. At the same time, natural gas combustion, with an air coefficient of around 1.3, allows for complete combustion with excess oxygen and produces very little nitrogen oxides. This allows unburned components in the ammonia burner 200 and excess oxygen from the natural gas burner 300 to combine and undergo secondary combustion in the combustion chamber of the kiln body 100. Meanwhile, at a flue gas temperature of around 900℃ in the kiln body 100, an ammonia combustion reduction spray gun 400 is installed in the initial heating section with its air coefficient controlled at around 0.5. This not only provides heat to the heating section but also allows unburned residual ammonia to combine with nitrogen oxides in the flue gas generated in the high-temperature firing section 150 for nitrogen oxide reduction.

[0062] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A continuous heating furnace for low NOx emissions from ammonia combustion reduction, characterized in that, The system includes a kiln body (100) having a discharge end (110) and a feed end (120). A conveying channel (130) is provided within the kiln body (100). From the feed end (120) to the discharge end (110), the kiln body (100) is sequentially provided with a preheating section (140) and a high-temperature firing section (150). The high-temperature firing section (150) is equipped with multiple burners, including an ammonia burner (200), a natural gas burner (300), and an ammonia combustion reduction spray gun (400). The high-temperature firing section (150) is equipped with... The device has an initial heating section (151) and a high-temperature section (152). The ammonia combustion reduction spray gun (400) is located in the initial heating section (151), and the ammonia burner (200) and the natural gas burner (300) are located in the high-temperature section (152). The preheating section (140) has a flue gas outlet (170) at the material inlet end. The air coefficient of the natural gas burner (300) is 1.1~1.3, the air coefficient of the ammonia burner (200) is 0.85~1.0, and the air coefficient of the ammonia combustion reduction spray gun (400) is 0.5~0.

95.

2. The ammonia combustion reduction low-NOx emission continuous heating furnace according to claim 1, characterized in that: Multiple burners are staggered on both sides of the conveying channel (130), and the ammonia burner (200) and the natural gas burner (300) are staggered on the same side of the conveying channel (130).

3. The ammonia combustion reduction low-NOx emission continuous heating furnace kiln according to claim 1, characterized in that: A cooling section (160) is also provided near the discharge end (110), and the cooling section (160) is provided with a cooling structure.

4. The ammonia combustion reduction low-NOx emission continuous heating furnace according to claim 1, characterized in that: The walls of the kiln body (100) are heat-insulating furnace walls.

5. The ammonia combustion reduction low-NOx emission continuous heating furnace kiln according to claim 1, characterized in that: The temperature of the initial heating section (151) is controlled between 800 and 1000 degrees Celsius, and the temperature of the high-temperature section (152) is controlled above 1000 degrees Celsius.

6. A control method applicable to a continuous heating furnace with low NOx emissions from ammonia combustion reduction as described in any one of claims 1 to 5, characterized in that: Control the flow of flue gas from the high-temperature section (152) to the initial heating section (151); Control the air coefficients of the ammonia combustion reduction torch (400), ammonia burner (200), and natural gas burner (300), and make the temperature of the high-temperature section (152) reach above 1000 degrees Celsius, with the initial heating temperature between 800 degrees Celsius and 1000 degrees Celsius.

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