Hot blast furnace low nitrogen combustion device

Abstract

The present invention provides a low-nitrogen combustion device for a hot blast furnace, which relates to the technical field of combustion equipment. The low-nitrogen combustion device for a hot blast furnace comprises a furnace shell having a combustion chamber, and a furnace lining arranged on the furnace shell. Along the height direction of the furnace lining, an upper air-fuel mixing structure, a middle air-fuel mixing structure, and a lower air-fuel mixing structure are sequentially arranged on the furnace lining. The upper air-fuel mixing structure is inclined at a first angle toward the middle air-fuel mixing structure, and the lower air-fuel mixing structure is inclined at a second angle toward the middle air-fuel mixing structure. The present invention can improve the mixing uniformity between air and gas by coordinating the upper air-fuel mixing structure and the lower air-fuel mixing structure, so that the gas and air can be fully burned, thereby improving combustion efficiency, reducing flame length, and reducing the generation of nitrogen oxides.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion equipment, in particular to a low-nitrogen combustion device for a hot blast furnace. Background Art

[0002] In the prior art, most top-fired hot blast furnaces employ a combustion structure consisting of a top burner and a lower combustion chamber. The top burner typically employs a multi-layer nozzle arrangement consisting of an upper gas nozzle and a lower combustion air nozzle. However, during use, the upper gas nozzle forms a columnar gas flow flowing downward within the burner cavity. This is then followed by multiple layers of combustion air flow injected into the gas flow, causing the gas and combustion air to locally mix and burn. However, this layered gas distribution method results in a smaller contact surface between the gas and combustion air, resulting in poor mixing of the gas and combustion air. This leads to incomplete combustion of the gas and a longer flame, which in turn increases the production of nitrogen oxides. Summary of the Invention

[0003] In order to overcome the above-mentioned defects of the prior art, the technical problem to be solved by the embodiments of the present invention is to provide a low-nitrogen combustion device for a hot blast furnace, which is used to improve the mixing uniformity of air and gas to reduce the generation of nitrogen oxides.

[0004] The above-mentioned objectives of the present invention can be achieved by adopting the following technical solutions. The present invention provides a low-nitrogen combustion device for a hot blast furnace, comprising a furnace shell having a combustion chamber, and a furnace lining arranged on the furnace shell. Along the height direction of the furnace lining, an upper air-fuel mixing structure, a middle air-fuel mixing structure and a lower air-fuel mixing structure are sequentially provided on the furnace lining. The upper air-fuel mixing structure is inclined at a first angle toward the middle air-fuel mixing structure, and the lower air-fuel mixing structure is inclined at a second angle toward the middle air-fuel mixing structure.

[0005] In a preferred embodiment of the present invention, the upper air-fuel mixing structure includes a plurality of upper air nozzles and a plurality of upper gas nozzles arranged on the furnace lining, and the upper air nozzles and the upper gas nozzles are arranged in sequence and staggered at the same height, and the upper air nozzles and the upper gas nozzles are inclined at a first angle toward the middle air-fuel mixing structure.

[0006] In a preferred embodiment of the present invention, along the circumference of the furnace lining, each of the upper air nozzles and each of the upper gas nozzles are tangent to a first rotary cutting circle preset in the combustion chamber along the same rotation direction.

[0007] In a preferred embodiment of the present invention, the first angle is 15°-30°.

[0008] In a preferred embodiment of the present invention, the lower layer air-fuel mixing structure includes a plurality of lower layer air nozzles and a plurality of lower layer gas nozzles arranged on the furnace lining, and each of the lower layer air nozzles and each of the lower layer gas nozzles are arranged in sequence and staggered at the same height, and each of the lower layer air nozzles and each of the lower layer gas nozzles are inclined at a second angle toward the middle layer air-fuel mixing structure.

[0009] In a preferred embodiment of the present invention, along the circumference of the furnace lining, each of the lower-layer air nozzles and each of the lower-layer gas nozzles are tangent to a second rotary circle preset in the combustion chamber along the same rotation direction.

[0010] In a preferred embodiment of the present invention, along the height direction of the furnace lining, the projections of the first rotary cutting circle and the second rotary cutting circle coincide with each other.

[0011] In a preferred embodiment of the present invention, the upper air nozzles and the upper gas nozzles are arranged along the same rotation direction as the lower air nozzles and the lower gas nozzles.

[0012] In a preferred embodiment of the present invention, the second angle is 15°-30°.

[0013] In a preferred embodiment of the present invention, the middle-layer air-fuel mixing structure includes a plurality of middle-layer air nozzles and a plurality of middle-layer gas nozzles arranged on the furnace lining, and the middle-layer air nozzles and the middle-layer gas nozzles are arranged in sequence and staggered at the same height, and the middle-layer air nozzles and the middle-layer gas nozzles are horizontally arranged toward the center of the middle-layer air-fuel mixing structure.

[0014] In a preferred embodiment of the present invention, a plurality of the middle-layer air-fuel mixing structures are arranged in parallel.

[0015] In a preferred embodiment of the present invention, along the height direction of the furnace lining, the upper air nozzles, the middle air nozzles and the lower air nozzles are correspondingly arranged in the same row, and the upper gas nozzles, the middle gas nozzles and the lower gas nozzles are correspondingly arranged in the same row.

[0016] In a preferred embodiment of the present invention, along the height direction of the furnace lining, the upper layer air nozzles, the middle layer air nozzles and the lower layer air nozzles are evenly spaced, and the upper layer gas nozzles, the middle layer gas nozzles and the lower layer gas nozzles are evenly spaced.

[0017] In a preferred embodiment of the present invention, the low-nitrogen combustion device of the hot blast furnace also includes a plurality of air channels and a plurality of gas channels arranged in the furnace lining, the air channels are provided with an air inlet, the gas channels are provided with a gas inlet, the upper-layer air nozzles, the middle-layer air nozzles and the lower-layer air nozzles located in the same row are connected to one air channel respectively, and the upper-layer gas nozzles, the middle-layer gas nozzles and the lower-layer gas nozzles located in the same row are connected to one gas channel respectively.

[0018] The technical solution of the present invention has the following significant beneficial effects:

[0019] When the hot blast furnace low-nitrogen burner of the present invention is used, gas and air are respectively fed into the upper, middle, and lower air-fuel mixing structures. The gas and air are rapidly mixed and sprayed into the combustion chamber for combustion using the upper, middle, and lower air-fuel mixing structures. The middle air-fuel mixing structure rapidly mixes the air and gas, and the mixed air and gas are then sprayed toward the center of the middle air-fuel mixing structure, thereby improving the uniformity of the mixing of the air and gas. Furthermore, the upper air-fuel mixing structure can quickly mix air and gas, and the mixed air and gas are sprayed toward the middle air-fuel mixing structure, thereby generating a downward swirl in the combustion chamber; and the lower air-fuel mixing structure can quickly mix air and gas, and the mixed air and gas are sprayed toward the middle air-fuel mixing structure, thereby generating an upward swirl in the combustion chamber; the upward swirl and the downward swirl can produce a synergistic effect to cause secondary mixing of the gas and air, thereby further improving the mixing uniformity between the air and the gas, allowing the gas to fully burn, thereby improving combustion efficiency, reducing flame length and reducing the generation of nitrogen oxides. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the various components in the drawings are merely illustrative and are used to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the various components of the present invention. Those skilled in the art can select various possible shapes and proportional dimensions to implement the present invention according to specific circumstances under the guidance of the present invention.

[0022] Figure 1This is a schematic cross-sectional view of a low-nitrogen combustion device for a hot blast furnace;

[0023] Figure 2 Schematic diagram of the expanded structure of the furnace lining;

[0024] Figure 3 for Figure 1 Schematic diagram of the AA cross-section structure;

[0025] Figure 4 for Figure 1 Schematic diagram of the BB cross-section structure.

[0026] Reference numerals in the above drawings:

[0027] 1. Furnace shell; 11. Combustion chamber; 12. Furnace lining; 13. First rotary cutting circle; 14. Second rotary cutting circle;

[0028] 2. Upper air-fuel mixing structure; 21. Upper air nozzle; 22. Upper gas nozzle;

[0029] 3. Middle layer air-fuel mixing structure; 31. Middle layer air nozzle; 32. Middle layer gas nozzle;

[0030] 4. Lower layer air-fuel mixing structure; 41. Lower layer air nozzle; 42. Lower layer gas nozzle;

[0031] 5. Air passage;

[0032] 6. Gas channel. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Please refer to Figure 1 As shown, an embodiment of the present invention provides a low-nitrogen combustion device for a hot blast furnace, comprising a furnace shell 1 having a combustion chamber 11, and a furnace lining 12 arranged on the furnace shell 1. Along the height direction of the furnace lining 12, an upper air-fuel mixing structure 2, a middle air-fuel mixing structure 3 and a lower air-fuel mixing structure 4 are sequentially provided on the furnace lining 12. The upper air-fuel mixing structure 2 is inclined at a first angle a toward the middle air-fuel mixing structure 3, and the lower air-fuel mixing structure 4 is inclined at a second angle b toward the middle air-fuel mixing structure 3.

[0035] In general, when the hot blast furnace low-nitrogen combustion device is used, the gas and air are respectively sent into the upper air-fuel mixing structure 2, the middle air-fuel mixing structure 3 and the lower air-fuel mixing structure 4. The upper air-fuel mixing structure 2, the middle air-fuel mixing structure 3 and the lower air-fuel mixing structure 4 can be used to quickly mix the gas and air and spray them into the combustion chamber 11 for combustion. The upper air-fuel mixing structure 2 can quickly mix the air and gas, and the mixed air and gas are sprayed toward the middle air-fuel mixing structure 3, thereby generating a downward vortex in the combustion chamber 11; while the lower air-fuel mixing structure 4 can quickly mix the air and gas, and spray the mixed air and gas toward the middle air-fuel mixing structure 3, thereby generating an upward vortex in the combustion chamber 11; the upward vortex and the downward vortex can produce a synergistic effect to cause the gas and air to be mixed twice, thereby further improving the mixing uniformity between the air and gas, allowing the gas to burn fully, thereby improving combustion efficiency, reducing flame length and reducing the generation of nitrogen oxides.

[0036] In an embodiment of the present invention, Figure 2 and Figure 3 In the embodiment shown, the upper air-fuel mixing structure 2 includes a plurality of upper air nozzles 21 and a plurality of upper gas nozzles 22 arranged on the furnace lining 12, and the upper air nozzles 21 and the upper gas nozzles 22 are arranged in a staggered manner at the same height, and the upper air nozzles 21 and the upper gas nozzles 22 are inclined at a first angle a toward the middle air-fuel mixing structure 3.

[0037] By arranging the multiple upper air nozzles 21 and the multiple upper gas nozzles 22 at the same height, stratification of air and gas in the upper air-fuel mixing structure 2 can be prevented, thereby avoiding the formation of a flame front during the mixed combustion of gas and air. By eliminating the flame front, the thermodynamic reaction between oxygen and nitrogen at the flame front is reduced, thereby reducing the amount of nitrogen oxides generated.

[0038] In this embodiment of the present invention, along the circumference of the furnace lining 12, each upper layer of air nozzles 21 and each upper layer of gas nozzles 22 are tangential to a first rotary circle 13 preset within the combustion chamber 11 along the same rotational direction. Specifically, the first rotary circle 13 is the circle with the maximum radius within the area enclosed by the upper layer of air nozzles 21 and the upper layer of gas nozzles 22 at the same height.

[0039] By controlling the injection direction of the upper air nozzles 21 and upper gas nozzles 22, each upper air nozzle 21 and upper gas nozzle 22 can be tangent to the first rotary cutting circle 13 in a clockwise or counterclockwise direction. By adjusting the size of the first rotary cutting circle 13, the injection direction of each upper air nozzle 21 and upper gas nozzle 22 can be controlled accordingly, thereby controlling the rotational direction and rotational speed of the air and gas entering the combustion chamber 11. By causing the air and gas to mix rotationally within the combustion chamber 11, the mixing speed of the air and gas can be significantly accelerated.

[0040] In an embodiment of the present invention, the first angle a ranges from 15° to 30°. Specifically, in one feasible embodiment of the present invention, the first angle a is set to 30°. Setting the first angle a to 30° allows the upper air nozzles 21 and the upper gas nozzles 22 to spray toward the middle air-fuel mixing structure 3, thereby generating a downward swirl flow within the combustion chamber 11, which facilitates the mixing of air and gas. Designers can adjust the first angle a according to specific needs, and this is not a specific limitation.

[0041] In an embodiment of the present invention, Figure 2 and Figure 4 In the embodiment shown, the lower layer air-fuel mixing structure 4 includes a plurality of lower layer air nozzles 41 and a plurality of lower layer gas nozzles 42 arranged on the furnace lining 12, and the lower layer air nozzles 41 and the lower layer gas nozzles 42 are arranged in a staggered manner at the same height, and the lower layer air nozzles 41 and the lower layer gas nozzles 42 are inclined at a second angle b toward the middle layer air-fuel mixing structure 3.

[0042] By arranging the multiple lower-layer air nozzles 41 and the multiple lower-layer gas nozzles 42 at the same height, stratification of air and gas in the lower-layer air-fuel mixing structure 4 can be prevented, thereby avoiding the formation of a flame front during the mixed combustion of gas and air. By eliminating the flame front, the thermodynamic reaction between oxygen and nitrogen at the flame front is reduced, thereby reducing the amount of nitrogen oxides generated.

[0043] In this embodiment of the present invention, along the circumference of the furnace lining 12, each lower-layer air jet 41 and each lower-layer gas jet 42 are tangential to a second rotary circle 14 preset within the combustion chamber 11 along the same rotational direction. Specifically, the second rotary circle 14 is the circle with the maximum radius within the area enclosed by the lower-layer air jets 41 and the lower-layer gas jets 42 at the same height.

[0044] By controlling the injection direction of the lower air nozzles 41 and the lower gas nozzles 42, each lower air nozzle 41 and each lower gas nozzle 42 can be tangent to the second rotary cutting circle 14 in a clockwise or counterclockwise direction. By adjusting the size of the second rotary cutting circle 14, the injection direction of each lower air nozzle 41 and lower gas nozzle 42 can be controlled accordingly, thereby controlling the rotational direction and rotational speed of the air and gas entering the combustion chamber 11. By causing the air and gas to mix rotationally within the combustion chamber 11, the mixing speed of the air and gas can be significantly accelerated.

[0045] In this embodiment of the present invention, the projections of the first rotary circle 13 and the second rotary circle 14 overlap along the height direction of the furnace lining 12. By aligning the projections of the first rotary circle 13 and the second rotary circle 14, the downward swirl generated by the upper air-fuel mixing structure 2 and the upward swirl generated by the lower air-fuel mixing structure 4 are substantially equal in size. As a result, the middle air-fuel mixing structure 3 is sandwiched between the downward and upward swirls in a relatively stable swirl mixing field. Consequently, the combined effects of the downward and upward swirls accelerate the mixing speed of the air and gas.

[0046] In this embodiment of the present invention, the upper air nozzles 21 and upper gas nozzles 22 are arranged in the same rotational direction as the lower air nozzles 41 and lower gas nozzles 42. By arranging them in the same rotational direction, the swirl speed of the upper air-fuel mixing structure 2 and the swirl speed of the lower air-fuel mixing structure 4 can be superimposed, thereby increasing the overall swirl speed within the combustion chamber 11. By increasing the swirl speed within the combustion chamber 11, the mixing efficiency of air and gas can be improved.

[0047] In this embodiment of the present invention, the second angle b ranges from 15° to 30°. Specifically, in one feasible embodiment of the present invention, the second angle b is set to 30°. Setting the second angle b to 30° allows the lower air nozzles 41 and the lower gas nozzles 42 to spray toward the middle air-fuel mixing structure 3, thereby generating a downward swirl flow within the combustion chamber 11, which helps to improve the mixing efficiency of air and gas. Designers can adjust the first angle a according to actual needs, and this is not a specific limitation here.

[0048] In an embodiment of the present invention, the middle-layer air-fuel mixing structure 3 includes a plurality of middle-layer air nozzles 31 and a plurality of middle-layer gas nozzles 32 arranged on the furnace lining 12. The middle-layer air nozzles 31 and the middle-layer gas nozzles 32 are arranged in sequence and staggered at the same height. The middle-layer air nozzles 31 and the middle-layer gas nozzles 32 are all arranged horizontally toward the center of the middle-layer air-fuel mixing structure 3.

[0049] By staggering the middle-layer air nozzles 31 and the middle-layer gas nozzles 32 at the same height, the air and gas are mixed immediately upon ejection, improving the mixing efficiency of the two. Placing multiple middle-layer air nozzles 31 and gas nozzles 32 at the same height prevents stratification of the air and gas in the middle-layer air-fuel mixing structure 3, thereby avoiding the formation of a flame front during the mixed combustion of gas and air. Eliminating the flame front reduces the thermodynamic reaction between oxygen and nitrogen at the flame front, thereby reducing the formation of nitrogen oxides.

[0050] Furthermore, the mid-level air-fuel mixing structure 3 further increases the air-fuel distribution within the combustion chamber 11, thereby achieving a better combustion effect. The horizontally arranged mid-level air nozzles 31 and mid-level gas nozzles 32 improve the stability of the air-fuel mixing process within the combustion chamber 11, allowing the gas to fully contact the air for combustion, resulting in a shorter flame and better combustion.

[0051] In this embodiment of the present invention, multiple mid-level air-fuel mixing structures 3 are arranged in parallel. Specifically, two mid-level air-fuel mixing structures 3 are arranged in parallel. Increasing the number of mid-level air-fuel mixing structures 3 can further improve the stability of the air-fuel mixing process within the combustion chamber 11 and increase the air-fuel distribution within the combustion chamber 11, thereby achieving the desired heating capacity. Designers can determine the number of mid-level air-fuel mixing structures 3 based on actual use, and this is not a specific limitation.

[0052] In an embodiment of the present invention, along the height direction of the furnace lining 12, the upper air nozzles 21, the middle air nozzles 31 and the lower air nozzles 41 are correspondingly arranged in the same row, and the upper gas nozzles 22, the middle gas nozzles 32 and the lower gas nozzles 42 are correspondingly arranged in the same row.

[0053] By arranging the upper air nozzles 21, the middle air nozzles 31, and the lower air nozzles 41 in the same row, and arranging the upper gas nozzles 22, the middle gas nozzles 32, and the lower gas nozzles 42 in the same row, the air nozzles and the gas nozzles can be arranged in sequence and spaced apart along the circumference of the combustion chamber 11, thereby improving the uniformity of the distribution of air and gas along the circumference of the combustion chamber 11, completing the premixing operation before the air and gas are ejected, and significantly improving the mixing efficiency of the air and gas.

[0054] In an embodiment of the present invention, along the height direction of the furnace lining 12, the upper air nozzles 21, the middle air nozzles 31 and the lower air nozzles 41 are evenly spaced, and the upper gas nozzles 22, the middle gas nozzles 32 and the lower gas nozzles 42 are evenly spaced.

[0055] By evenly spacing the air and gas nozzles, the uneven distribution of air and gas along the height of the furnace lining 12 is eliminated, improving the uniformity of the premixing effect achieved by the air and gas nozzles and, in turn, the uniformity of the air and gas mixing. When the air and gas are thoroughly and evenly mixed, the combustion efficiency of the gas is improved, resulting in a shorter flame length, known as short-flame combustion. By achieving short-flame combustion of the gas and air, the gas is fully burned, thereby reducing the generation of nitrogen oxides.

[0056] In an embodiment of the present invention, the low-nitrogen combustion device of the hot blast furnace also includes a plurality of air channels 5 and a plurality of gas channels 6 arranged in the furnace lining 12. The air channel 5 is provided with an air inlet, and the gas channel 6 is provided with a gas inlet. The upper air nozzles 21, the middle air nozzles 31 and the lower air nozzles 41 located in the same row are connected to one air channel 5 respectively, and the upper gas nozzles 22, the middle gas nozzles 32 and the lower gas nozzles 42 located in the same row are connected to one gas channel 6 respectively.

[0057] Specifically, each air channel 5 and each gas channel 6 is embedded in the furnace lining 12, and each air channel 5 and each gas channel 6 is arranged in a staggered manner. The air channel 5 can be connected to an external air supply pipeline for air supply; the gas channel 6 can be connected to an external gas supply pipeline for gas supply.

[0058] Air channels 5 uniformly supply air to the upper air nozzles 21, middle air nozzles 31, and lower air nozzles 41 in the same row, improving the uniformity of air distribution along the height of the furnace lining 12. Controlling the amount of air within each air channel 5 also improves the uniformity of air distribution along the circumference of the furnace lining 12. Gas channels 6 uniformly supply gas to the upper gas nozzles 22, middle gas nozzles 32, and lower gas nozzles 42 in the same row, improving the uniformity of gas distribution along the height of the furnace lining 12. Controlling the amount of gas within each gas channel 6 also improves the uniformity of gas distribution along the circumference of the furnace lining 12. Improving the uniformity of air and gas distribution improves combustion stability. Controlling the air-fuel ratio also enables under-oxygen combustion of air and gas, further reducing the production of nitrogen oxides.

[0059] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for all purposes. The term "essentially consisting of..." describing a combination should include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel features of the combination. The use of the terms "comprising" or "including" to describe the combination of elements, ingredients, parts or steps herein also contemplates an embodiment that is essentially composed of these elements, ingredients, parts or steps. By using the term "may", it is intended to illustrate that any attribute described that "may" include is optional. Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0060] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low nitrogen combustion device for a hot blast stove, characterized in that: The invention comprises a furnace shell having a combustion chamber, and a furnace lining provided on the furnace shell, wherein an upper air-fuel mixing structure, a middle air-fuel mixing structure and a lower air-fuel mixing structure are sequentially provided on the furnace lining along a height direction of the furnace lining, the upper air-fuel mixing structure is inclined at a first angle toward the middle air-fuel mixing structure, and the lower air-fuel mixing structure is inclined at a second angle toward the middle air-fuel mixing structure; The upper air-fuel mixing structure includes a plurality of upper air nozzles and a plurality of upper gas nozzles arranged on the furnace lining, wherein the upper air nozzles and the upper gas nozzles are staggered and arranged at the same height, and each of the upper air nozzles and the upper gas nozzles are inclined at a first angle toward the middle air-fuel mixing structure; Along the circumference of the furnace lining, each of the upper air nozzles and each of the upper gas nozzles are tangent to a first rotary circle preset in the combustion chamber along the same rotary direction; The lower layer air-fuel mixing structure includes a plurality of lower layer air nozzles and a plurality of lower layer gas nozzles arranged on the furnace lining, each of the lower layer air nozzles and each of the lower layer gas nozzles are staggered and arranged at the same height, and each of the lower layer air nozzles and each of the lower layer gas nozzles are inclined at a second angle toward the middle layer air-fuel mixing structure; Along the circumference of the furnace lining, each of the lower air nozzles and each of the lower gas nozzles are tangent to a second rotary circle preset in the combustion chamber along the same rotary direction; Along the height direction of the furnace lining, the projections of the first rotary cutting circle and the second rotary cutting circle coincide with each other; The upper air nozzles and the upper gas nozzles are arranged along the same rotation direction as the lower air nozzles and the lower gas nozzles; The middle-layer air-fuel mixing structure includes a plurality of middle-layer air nozzles and a plurality of middle-layer gas nozzles arranged on the furnace lining. The middle-layer air nozzles and the middle-layer gas nozzles are arranged in a staggered manner at the same height, and the middle-layer air nozzles and the middle-layer gas nozzles are horizontally arranged toward the center of the middle-layer air-fuel mixing structure.

2. The hot blast stove low nitrogen combustion device according to claim 1, characterized in that: The first angle is between 15° and 30°.

3. The hot blast stove low nitrogen combustion device according to claim 1, characterized in that: The second angle is between 15° and 30°.

4. The hot blast stove low nitrogen combustion device according to claim 1, characterized in that: A plurality of the middle-layer air-fuel mixing structures are arranged in parallel.

5. The hot blast stove low nitrogen combustion device according to claim 1, characterized in that: Along the height direction of the furnace lining, the upper air nozzles, the middle air nozzles and the lower air nozzles are correspondingly arranged in the same row, and the upper gas nozzles, the middle gas nozzles and the lower gas nozzles are correspondingly arranged in the same row.

6. The hot blast stove low nitrogen combustion device according to claim 1, characterized in that: Along the height direction of the furnace lining, the upper air nozzles, the middle air nozzles and the lower air nozzles are evenly spaced, and the upper gas nozzles, the middle gas nozzles and the lower gas nozzles are evenly spaced.

7. The hot blast stove low nitrogen combustion device according to claim 1, characterized in that: The low-nitrogen combustion device of the hot blast furnace also includes a plurality of air channels and a plurality of gas channels arranged in the furnace lining, the air channels are provided with an air inlet, the gas channels are provided with a gas inlet, the upper-layer air nozzles, the middle-layer air nozzles and the lower-layer air nozzles located in the same row are connected to one air channel respectively, and the upper-layer gas nozzles, the middle-layer gas nozzles and the lower-layer gas nozzles located in the same row are connected to one gas channel respectively.

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