Low-nitrogen burner and low-nitrogen burner control system for intelligently adjusting air-fuel ratio

Abstract

The present invention discloses a low-nitrogen burner and a low-nitrogen burner control system for intelligently adjusting the air-fuel ratio. The low-nitrogen burner comprises: a peripheral air pipe, a main gas pipe air inlet seat and the main gas pipeline, a plurality of axial gas branch pipes, a plurality of oblique gas branch pipes and a flame stabilizing disk arranged inside the peripheral air pipe; the roots of the plurality of axial gas branch pipes are connected to the main gas pipeline, and the ends are connected to the flame stabilizing disk, and have axial injection ports arranged on the flame stabilizing disk; the roots of the plurality of oblique gas branch pipes are connected to the main gas pipeline, and the ends surround the outer edge of the flame stabilizing disk and are provided with oblique injection ports; the flame stabilizing disk is provided with a central air hole and a plurality of air swirl holes uniformly distributed in the circumferential direction; the ends of the peripheral air pipe are provided with a flame hood contraction port and a plurality of triangular guide vanes. The technical solution of the present invention helps to efficiently organize combustion and reduce pollutant emissions by strengthening the mixing of air and gas and forming a graded flame through graded combustion.

Description

Technical Field

[0001] The present invention relates to the technical field of low-nitrogen burners, and in particular to a low-nitrogen burner and a low-nitrogen burner control system for intelligently adjusting an air-fuel ratio. Background Art

[0002] Nitrogen oxides NOx and carbon monoxide CO are important atmospheric pollutants and are important factors in causing acid rain and haze. With the increasing requirements for environmental protection, the country's restrictions on NOx and CO emissions are becoming increasingly stringent. Gas burners have the advantages of safety, high efficiency, and easy operation, and are the core equipment used by industrial boilers to provide heat energy. Therefore, whether it is to respond to the strict requirements of national policies on emissions, or the environmental protection needs of energy conservation and emissions caused by the large-scale use of various gases, the development of low NOx emission burners will become a key factor in resolving these contradictions.

[0003] The combustion head of the burner is the key core component of the entire burner. The function of this component is to mix the fuel gas (also called fuel, gas) and combustion air and organize combustion. The structural type of this component determines the reliability and stability of the combustion process, as well as the speed and temperature distribution of the entire combustion area, which are all key factors affecting flue gas emissions.

[0004] Most of the existing burners use diffusion combustion. In order to ensure sufficient combustion, the burner generally adopts a design method that mixes fuel and air better. This type of combustion has a high flame temperature and a large high-temperature area, which easily produces a large amount of NOx. How to design a combustion head structure that reduces the oxygen concentration of tail flue gas, further reduces NOx, and ensures stable and sufficient combustion is an urgent problem that research and development technicians need to solve.

[0005] In addition, the burner can be controlled by adjusting the combustion air damper opening and gas damper opening according to the load output size, forming an automatic control scheme for the burner. However, this control method cannot achieve accurate control of the demand for combustion air during the combustion process. Especially in oil field heating furnaces, due to the unstable fuel source, large fluctuations in fuel pressure, and the impact of the environment on combustion air, etc., the air volume will be unstable during the combustion process, resulting in insufficient combustion or excessive NOx emissions due to excessive local temperature. Summary of the invention

[0006] The main purpose of the present invention is to provide a low-nitrogen burner, which applies the gas staged combustion technology to the forced draft burner, aiming to solve the shortcomings of high nitrogen oxide emissions and unstable combustion of common gas burners, and achieve the purpose of efficient combustion organization, energy saving and reduction of NOx and other pollutant emissions. The purpose of the present invention is also to provide a low-nitrogen burner control system that intelligently adjusts the air-fuel ratio, aiming to solve the shortcomings of common gas burners that cannot accurately control the excess air coefficient, and achieve the purpose of precise combustion control.

[0007] To achieve the above-mentioned purpose, the first aspect of the present invention provides a low-nitrogen burner, comprising: a peripheral air pipe, a main gas pipe air inlet seat and arranged inside the peripheral air pipe: a main gas pipeline, a plurality of axial gas branch pipes, a plurality of oblique gas branch pipes and a flame stabilizing disk; the peripheral air pipe is coaxially arranged with the main gas pipeline, and the main gas pipe air inlet seat is connected to the root of the main gas pipeline; the roots of the plurality of axial gas branch pipes are connected to the main gas pipeline, and the ends are connected to the flame stabilizing disk, and have axial injection ports arranged on the flame stabilizing disk; the roots of the plurality of oblique gas branch pipes are connected to the main gas pipeline, and the ends surround the outer edge of the flame stabilizing disk, and are provided with oblique injection ports inclined outward; the flame stabilizing disk is provided with a central air hole and a plurality of air swirl holes evenly distributed circumferentially; the end of the peripheral air pipe is provided with a fire hood contraction port and a plurality of triangular guide plates formed on the fire hood contraction port.

[0008] In a further implementation, the low-nitrogen burner divides the air injected into the boiler furnace through the peripheral air pipe into three parts: the first part of the air is injected into the furnace axially along the central axis of the low-nitrogen burner through the central air hole of the flame stabilizing disk to form primary air; the second part of the air enters the furnace through the air swirl holes of the flame stabilizing disk to form secondary air; the third part of the air is ejected through the annular channel between the outer edge of the flame stabilizing disk and the peripheral air pipe to form tertiary air.

[0009] In a further implementation method, the low-nitrogen burner divides the gas entering the main gas pipeline through the main gas pipe inlet seat into two parts: the first part of the gas is sprayed out through the axial fuel branch pipe and mixed with the secondary air, burned near the central axis of the boiler furnace, and convoluted a part of the primary air to form a primary flame area; the second part of the gas is sprayed outward obliquely through the oblique gas branch pipe, mixed with the tertiary air that has not yet sprayed out of the burner head, and after being fully mixed inside the flame hood, develops downstream to form a secondary flame.

[0010] In a further implementation, the air swirl hole comprises a radial air long hole and a matching swirl blade; the number of the air swirl holes is 4 to 12, and the inclination angle of the swirl blade is 15° to 60°.

[0011] In a further implementation, the number of the axial gas branch pipes is 3 to 10, and the number of the oblique gas branch pipes is 3 to 10, all of which are evenly distributed circumferentially around the central axis of the main gas pipeline.

[0012] According to a second aspect of the present invention, there is provided a low-nitrogen burner control system for intelligently adjusting the air-fuel ratio, the system comprising the low-nitrogen burner as described in claim 1, which acts on a boiler; the system further comprises: a gas filter, an electric gas pressure regulating valve, a gas flow meter, a fuel pressure sensor and a gas valve group installed in sequence along the fuel intake direction on the fuel supply pipeline of the low-nitrogen burner; an electric damper regulating valve installed on the combustion-supporting air supply pipeline of the low-nitrogen burner; and a flue gas analysis module installed on the chimney of the boiler; and an intelligent air-fuel ratio adjustment terminal; the electric gas pressure regulating valve, the gas flow meter, the fuel pressure sensor, the electric damper regulating valve and the flue gas analysis module are respectively connected to the intelligent air-fuel ratio adjustment terminal.

[0013] In a further implementation, the flue gas analysis module is used to collect NOx emission values ​​and flue gas oxygen content. When the NOx emission value and the flue gas oxygen content exceed the set values ​​respectively, the NOx emission value and the flue gas oxygen content are transmitted as input signals to the intelligent air-fuel ratio adjustment terminal; the intelligent air-fuel ratio adjustment terminal is used to calculate the gas and air adjustment parameters according to the input signal from the flue gas analysis module, and adjust the gas flow rate and air flow rate respectively by controlling the electric gas pressure regulating valve and the electric damper regulating valve, so that the NOx emission value decreases and the flue gas oxygen content meets the set range; the fuel pressure sensor is used to collect the fuel pressure value entering the low-nitrogen burner, and when the fuel pressure value deviates from the set value, the fuel pressure value is transmitted as an input signal to the intelligent air-fuel ratio adjustment terminal; wherein the flow value of the gas flow meter changes with the change of the fuel pressure value; the intelligent air-fuel ratio adjustment terminal is also used to calculate the pressure adjustment parameter according to the input signal from the fuel pressure sensor, adjust the gas pressure by controlling the electric gas pressure regulating valve, and confirm whether the gas pressure meets the combustion requirements according to the flow signal fed back by the gas flow meter.

[0014] In a further implementation, the intelligent air-fuel ratio adjustment terminal is specifically used to adjust the gas flow and air flow by controlling the electric gas pressure regulating valve and the electric damper regulating valve, so that the excess air coefficient of gas combustion in the boiler furnace is 1.05~1.2.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) Strengthen the mixing of air and gas to make the mixing more uniform, improve combustion efficiency, and increase boiler thermal efficiency;

[0017] (2) Forming a staged mixture of air and fuel to create a multi-stage flame, which lowers the flame temperature and thus greatly reduces nitrogen oxide emissions;

[0018] (3) Mutual shearing and flame transfer can be formed between the multi-stage flame areas, making the combustion of the mixed gas more stable;

[0019] (4) The low-nitrogen burner control system of the present invention, which can intelligently adjust the air-fuel ratio, can achieve precise control of the excess air coefficient and nitrogen oxide emissions during the combustion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments and the description of the prior art will be briefly introduced below. 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 paying creative work.

[0021] Figure 1 is a cross-sectional structural diagram of a low nitrogen burner provided by one embodiment of the present invention;

[0022] Figure 2 is a front view of a low nitrogen burner provided by one embodiment of the present invention;

[0023] Figure 3 is a three-dimensional structural diagram of a low-nitrogen burner provided by an embodiment of the present invention;

[0024] Figure 4 It is a structural schematic diagram of a low-nitrogen burner control system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. 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 creative work should fall within the scope of protection of the present invention.

[0026] The terms "first", "second", "third", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0027] The following describes the embodiments in detail.

[0028] Please refer to Figures 1 to 3 One embodiment of the present invention provides a low nitrogen burner.

[0029] The low nitrogen burner comprises: an outer air pipe 1, a main gas pipe air inlet seat 3 and arranged inside the outer air pipe 1: a main gas pipeline 2, a plurality of axial gas branch pipes 6, a plurality of oblique gas branch pipes 7 and a flame stabilizing disk 4.

[0030] Among them, the peripheral air pipe 1 is coaxially arranged with the main gas pipeline 2, and the main gas pipe air inlet seat 3 is connected to the root of the main gas pipeline 2; the roots of multiple axial gas branch pipes 6 are connected to the end face of the main gas pipeline 2, and the ends are connected to the flame stabilizing disk 4, with axial injection ports arranged on the disk surface (or wall surface) of the flame stabilizing disk 4; the roots of multiple oblique gas branch pipes 7 are connected to the end of the main gas pipeline 2, and the ends surround the outer edge of the flame stabilizing disk 4, and are provided with oblique injection ports inclined outward; the flame stabilizing disk 4 is provided with a central air hole 10 and a plurality of air swirl holes 5 uniformly distributed in the circumferential direction; the end of the peripheral air pipe 1 is provided with a fire hood contraction port 8 and a plurality of triangular guide plates 9 formed on the fire hood contraction port 8.

[0031] Among them, the triangular guide plate 9 and the flame hood contraction opening 8 are both inclined toward the central axis of the low-nitrogen burner.

[0032] The structure of the air swirl hole 5 includes a radial air long hole and a matching swirl blade, and the air coming out of the radial air long hole is sprayed out at an angle under the action of the swirl blade. Optionally, the number of the air swirl holes 5 is 4 to 12, and the inclination angle of the swirl blade is 15° to 60°.

[0033] Among them, optionally: the number of axial gas branch pipes 6 is 3 to 10, which are evenly distributed circumferentially around the central axis of the main gas pipeline 2; the number of oblique gas branch pipes 7 is also 3 to 10, which are also evenly distributed circumferentially around the central axis of the main gas pipeline 2.

[0034] The low-nitrogen burner of the present invention has an outer air pipe 1 which is used as a passage for air to flow through, thereby guiding the combustion-supporting air to the boiler furnace; and a main gas pipe air inlet seat 3 which is used as a passage for gas to enter, thereby introducing the gas into the main gas pipeline 2, and then introducing the axial gas branch pipe 6 and the oblique gas branch pipe 7, and finally guiding the gas to the boiler furnace.

[0035] The low-nitrogen burner of the present invention divides the air injected into the boiler furnace through the peripheral air pipe 1 into three parts, which are respectively as follows: the first part is injected axially to the furnace along the central axis of the low-nitrogen burner through the central air hole 10 of the flame stabilizing disk 4 to form primary air; the second part of the air enters the furnace through the air swirl hole 5 of the flame stabilizing disk 4 to form secondary air; the third part of the air is ejected through the annular channel between the outer edge of the flame stabilizing disk 4 and the peripheral air pipe 1 to form tertiary air.

[0036] The low nitrogen burner of the present invention divides the gas entering the main gas pipeline 2 through the main gas pipe inlet seat 2 into two parts, which are respectively as follows:

[0037] The first part of the fuel gas flows out through the axial fuel branch pipe 6 and mixes with the secondary air, and burns near the central axis of the boiler furnace to form a primary flame area; at the same time, this part of the mixed gas entrains a part of the primary air, so there is excess air, which is oxygen-rich and extremely lean combustion. Since the secondary air formed by flowing through the swirl blades 5 is swirl air, the combustion is more stable and sufficient; the primary air is located at the root of the primary flame area, which can reduce the residence time of the mixed gas in the primary flame area and reduce the temperature of the primary flame area, thereby reducing the high-temperature area where NOx is generated.

[0038] The second part of the gas is sprayed outward obliquely through the oblique gas branch pipe 7 and mixed with the tertiary air that has not yet been sprayed out of the burner head. This part of the mixed gas is fully mixed inside the flame hood and develops downstream to form a secondary flame. This part of the mixed gas has excess air and is oxygen-rich combustion; and, part of the mixed gas in the primary flame area is sucked into the secondary flame area due to the swirl effect for further combustion, which makes the combustion more complete and strengthens the exchange of matter and heat energy between the flame areas.

[0039] In addition, the tertiary air controls the shape and range of the flame downstream of the low-nitrogen burner. The tertiary air forms a countercurrent vortex after passing through the contraction port 8 of the fire hood, which will suck the downstream flue gas back to the secondary flame area, forming a larger recirculation area, so that part of the burning flue gas flows back into the flame. The mixed air flow in the secondary flame area passes through the triangular guide vane 9, and the flame is divided into smaller areas, which reduces the temperature of the flame and further inhibits the formation of nitrogen oxides.

[0040] The low nitrogen burner and its working principle disclosed in the embodiment of the present invention are described above.

[0041] Please refer to Figure 4 The embodiment of the present invention also provides a low-nitrogen burner control system for intelligently adjusting the air-fuel ratio. The system includes a matching low-nitrogen burner 23 and a boiler 19. The low-nitrogen burner 23 is the low-nitrogen burner described in the above embodiment.

[0042] The system structure is as follows: a gas filter 12, an electric gas pressure regulating valve 13, a gas flow meter 14, a fuel pressure sensor 15 and a gas valve group 16 are installed in sequence on the fuel supply pipeline 11 of the burner 23 along the fuel intake direction; an electric damper regulating valve 18 is installed on the combustion air supply pipeline 17 of the burner 23 along the combustion air intake direction; a flue gas analysis module 21 is installed on the chimney 20 of the boiler 19; and an intelligent air-fuel ratio adjustment terminal 22 is also included.

[0043] Among them, the electric gas pressure regulating valve 13, the gas flow meter 14, and the fuel pressure sensor 15 are connected to the intelligent air-fuel ratio regulating terminal 22, the electric damper regulating valve 18 is connected to the intelligent air-fuel ratio regulating terminal 22, and the flue gas analysis module 21 is connected to the intelligent air-fuel ratio regulating terminal 22.

[0044] The flue gas analysis module 21 is used to collect NOx emission values ​​and flue gas oxygen content. When the NOx emission value and the flue gas oxygen content exceed the set value, the NOx emission value and the flue gas oxygen content are transmitted as input signals to the intelligent air-fuel ratio adjustment terminal 22; the intelligent air-fuel ratio adjustment terminal 22 processes and calculates the gas and air adjustment parameters, and controls and adjusts the electric gas pressure regulating valve 13 and the electric air damper regulating valve 18 to adjust the gas flow rate and the air flow rate respectively, so that the NOx emission value is reduced and the flue gas oxygen content meets the set range.

[0045] The fuel pressure sensor 15 is used to collect the fuel pressure value entering the burner. When the fuel pressure deviates from the set value, the fuel pressure value is transmitted as an input signal to the intelligent air-fuel ratio adjustment terminal 22. It should be noted that the flow value of the gas flow meter 14 will change with the change of the fuel pressure value, and the gas flow meter 14 will feed back the real-time flow value to the intelligent air-fuel ratio adjustment terminal 22.

[0046] The intelligent air-fuel ratio adjustment terminal 22 processes and calculates the pressure adjustment parameters, adjusts the pressure by controlling the electric gas pressure adjustment valve 13, and confirms whether the combustion requirements are met based on the flow signal fed back by the gas flow meter 14.

[0047] The system of the present invention can control the excess air coefficient of gas combustion in the boiler furnace by adjusting the gas flow rate and the air flow rate. Preferably, the excess air coefficient is controlled to be 1.05-1.2.

[0048] The air-fuel ratio regulation principle of the present invention is: in the process of organizing the mixing and combustion of fuel and combustion air, the fuel and combustion air meet a fixed ratio. In order to ensure sufficient mixing and combustion, a certain excess amount of combustion air is required. The excess coefficient of combustion air reflects the energy-saving status of the burner. Generally speaking, the excess air coefficient of the gas fuel of the boiler is preferably 1.05-1.2. When the amount of fuel is reduced, the combustion air is also required to be reduced accordingly to meet the excess air coefficient within the range value, otherwise it will cause the flue gas volume to increase and the flue gas heat loss to increase; when the amount of fuel is increased, the combustion air is also required to be increased accordingly to meet the excess air coefficient within the range value, otherwise the fuel and air will be insufficiently mixed and insufficiently burned, and CO and NOx in the flue gas emissions will also increase. The excess air coefficient can be calculated by the flue gas oxygen content, and the fuel amount and air amount are calculated therefrom. There is a certain rule between the flue gas oxygen content and the NOx emission value. Generally speaking, NOx decreases with the increase of oxygen content, but according to the NOx conversion method, excessive oxygen content will also cause the NOx conversion value to be high.

[0049] In summary, the present invention discloses a low-nitrogen burner, which solves the shortcomings of high nitrogen oxide emissions and unstable combustion of common gas burners by applying gas staged combustion technology to forced draft burners, and achieves the purpose of efficiently organizing combustion, saving energy and reducing emissions of pollutants such as NOx. The present invention also discloses a low-nitrogen burner control system that intelligently adjusts the air-fuel ratio, which solves the shortcoming that common gas burners cannot accurately control the excess air coefficient, and achieves the purpose of accurately controlling combustion.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) Strengthen the mixing of air and gas to make the mixing more uniform, improve combustion efficiency, and increase boiler thermal efficiency;

[0052] (2) Forming a staged mixture of air and fuel to create a multi-stage flame, which lowers the flame temperature and thus greatly reduces nitrogen oxide emissions;

[0053] (3) Mutual shearing and flame transfer can be formed between the multi-stage flame areas, making the combustion of the mixed gas more stable;

[0054] (4) The low-nitrogen burner control system of the present invention, which can intelligently adjust the air-fuel ratio, can achieve precise control of the excess air coefficient and nitrogen oxide emissions during the combustion process.

[0055] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. A person skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low nitrogen burner, characterized in that: include: An outer air pipe (1), a main gas pipe air inlet seat (3), and arranged inside the outer air pipe (1): a main gas pipeline (2), a plurality of axial gas branch pipes (6), a plurality of oblique gas branch pipes (7) and a flame stabilizing plate (4); The peripheral air pipe (1) is coaxially arranged with the main gas pipeline (2), and the main gas pipeline air inlet seat (3) is connected to the root of the main gas pipeline (2); The roots of the plurality of axial gas branch pipes (6) are connected to the main gas pipeline (2), the ends are connected to the flame stabilizing disk (4), and the plurality of axial gas branch pipes (6) have axial injection ports arranged on the flame stabilizing disk (4); The roots of the plurality of oblique gas branch pipes (7) are connected to the main gas pipeline (2), and the ends surround the outer edge of the flame stabilizing disk (4) and are provided with oblique injection ports inclined outwards; The flame stabilizing disk (4) is provided with a central air hole (10) and a plurality of air swirl holes (5) evenly distributed in the circumferential direction; The end of the peripheral air pipe (1) is provided with a fire hood contraction opening (8) and a plurality of triangular guide vanes (9) formed on the fire hood contraction opening (8); the triangular guide vanes (9) and the fire hood contraction opening (8) are both inclined toward the central axis of the low-nitrogen burner; The low nitrogen burner divides the air injected into the boiler furnace through the peripheral air pipe (1) into three parts: The first part of the air is injected axially along the central axis of the low-nitrogen burner into the furnace through the central air hole (10) of the flame stabilizing disk (4) to form primary air; The second part of air enters the furnace through the air swirl holes (5) of the flame stabilizing plate (4) to form secondary air; The third part of the air is ejected through the annular channel between the outer edge of the flame stabilizing disk (4) and the peripheral air pipe (1) to form tertiary air; The low-nitrogen burner divides the gas entering the main gas pipeline (2) through the main gas pipe inlet seat (3) into two parts: The first part of the gas is sprayed out through the axial gas branch pipe (6) and mixed with the secondary air, and burns near the central axis of the boiler furnace, and convolutes a part of the primary air to form a primary flame area; The second part of the gas is sprayed outward obliquely through the oblique gas branch pipe (7), mixed with the tertiary air that has not yet sprayed out of the burner head, and after being fully mixed inside the flame hood, develops downstream to form a secondary flame.

2. The low nitrogen burner according to claim 1, characterized in that: The air swirl hole (5) comprises a radial air long hole and a matching swirl blade; The number of the air swirl holes (5) is 4 to 12, and the inclination angle of the swirl blades is 15° to 60°.

3. The low nitrogen burner according to any one of claim 1, characterized in that: The number of the axial gas branch pipes (6) is 3 to 10, and the number of the oblique gas branch pipes (7) is 3 to 10, all of which are evenly distributed circumferentially around the central axis of the main gas pipeline (2).

4. A low-nitrogen burner control system with intelligent air-fuel ratio adjustment, characterized in that: comprising the low nitrogen burner as claimed in claim 1, the low nitrogen burner acting on a boiler (19); The system further comprises: A gas filter (12), an electric gas pressure regulating valve (13), a gas flow meter (14), a fuel pressure sensor (15) and a gas valve group (16) are sequentially installed on a fuel supply pipeline (11) of the low-nitrogen burner along a fuel intake direction; an electric damper regulating valve (18) is installed on a combustion air supply pipeline (17) of the low-nitrogen burner; and a flue gas analysis module (21) is installed on a chimney (20) of the boiler (19); and an intelligent air-fuel ratio adjustment terminal (22); The electric gas pressure regulating valve (13), the gas flow meter (14), the fuel pressure sensor (15), the electric damper regulating valve (18) and the flue gas analysis module (21) are respectively connected to the intelligent air-fuel ratio regulating terminal (22); The flue gas analysis module (21) is used to collect NOx emission values ​​and flue gas oxygen content, and when the NOx emission value and the flue gas oxygen content exceed set values ​​respectively, transmit the NOx emission value and the flue gas oxygen content as input signals to the intelligent air-fuel ratio adjustment terminal (22); The intelligent air-fuel ratio regulating terminal (22) is used to calculate the gas and air regulating parameters according to the input signal from the flue gas analysis module (21), and to adjust the gas flow rate and the air flow rate respectively by controlling the electric gas pressure regulating valve (13) and the electric air damper regulating valve (18), so that the NOx emission value is reduced and the flue gas oxygen content meets the set range; The fuel pressure sensor (15) is used to collect the fuel pressure value entering the low-nitrogen burner, and when the fuel pressure value deviates from the set value, the fuel pressure value is transmitted as an input signal to the intelligent air-fuel ratio adjustment terminal (22); wherein the flow value of the gas flow meter (14) changes with the change of the fuel pressure value; The intelligent air-fuel ratio adjustment terminal (22) is further used to calculate the pressure adjustment parameter according to the input signal from the fuel pressure sensor (15), adjust the gas pressure by controlling the electric gas pressure adjustment valve (13), and confirm whether the gas pressure meets the combustion requirement according to the flow signal fed back by the gas flow meter (14); The intelligent air-fuel ratio regulating terminal (22) is specifically used to regulate the gas flow rate and the air flow rate by controlling the electric gas pressure regulating valve (13) and the electric air damper regulating valve (18), so that the excess air coefficient of the gas combustion in the boiler furnace is 1.05-1.2.

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