Low-nitrogen-oxide air single-heat-storage burner

Abstract

The invention belongs to the technical field of combustors, and particularly relates to a low-nitrogen-oxide air single-heat-storage burner. The burner comprises an air heat storage box, a gas nozzle, an air nozzle group and a combustion area, the fuel gas nozzles serve as vertexes, the primary air nozzles are located at the waistline position of an isosceles triangle, the secondary air nozzles are distributed along the bottom edge of the triangle, and the three projections form an isosceles triangle space layout. According to the structure, nozzle inclination angle design and flow rate control are combined, and the synergistic effect of staged combustion and flue gas internal circulation is achieved; oxygen-deficient combustion in a primary air area inhibits generation of nitric oxide, and stepped oxygen supplementation is conducted in a secondary air area to complete final combustion; the isosceles triangle layout enhances high-temperature flue gas backflow, dilutes the oxygen concentration of a combustion core area and reduces the peak temperature; the high-flow-speed gas nozzle prolongs the flame length, and local high temperature is avoided. And finally, while the combustion efficiency of the high-calorific-value fuel is guaranteed, the emission of nitrogen oxides is reduced, the generation of high-carbon hydrocarbon cracking carbon black is inhibited, and the temperature uniformity of a heating area is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of burners, and relates to a low-nitrogen air single regenerative burner. BACKGROUND

[0002] Regenerative combustion technology significantly improves the preheating temperature of combustion air by efficiently recovering high-temperature flue gas waste heat, and has important value in the field of energy saving of industrial thermal equipment. For high-calorific-value gas fuels (such as coke oven gas, natural gas, liquefied petroleum gas, etc.), the theoretical air-fuel ratio is large, the volume of flue gas generated by combustion is small, the flue gas emission ratio of the regenerative system is high, and the overall flue gas emission temperature is low, so the fuel utilization rate advantage is significant. However, this technology faces severe challenges in high-calorific-value fuel applications: when the combustion temperature exceeds 1500℃, the generation of thermal-type nitrogen oxides (NOx) increases exponentially, becoming a key bottleneck restricting its environmental performance.

[0003] The design core of the traditional regenerative burner is to optimize the flame structure to maintain combustion stability, but there are inherent defects in controlling the uniformity of the temperature distribution in the combustion zone. For medium and low calorific value fuels, due to the large amount of flue gas generated, the regenerative combustion has a limited increase in overall combustion temperature, and the NOx increment is within a controllable range; while for high-calorific-value fuels, the volume of combustion products is significantly reduced, and the use of air single regenerative technology limits the preheating of air (often above 1000℃), which will cause the overall temperature in the combustion zone to rise sharply. At the same time, the momentum of the gas stream is low, and problems such as short injection distance, concentrated flame, and prominent local high-temperature area are prone to occur, resulting in a sharp increase in nitrogen oxide emissions. In the existing technology, conventional staged combustion or diffusion combustion strategies are difficult to balance flame stability and temperature uniformity under regenerative combustion conditions, especially lacking low-nitrogen optimization structure design for high-calorific-value fuels in single regenerative mode. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a low-NOx air single regenerative burner that can effectively inhibit the formation of high-temperature zones, expand the combustion reaction area, and strengthen the internal circulation of flue gas, in order to meet the urgent needs of clean combustion of high-calorific-value fuels.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A low-nitrogen air single regenerative burner, characterized in that it comprises an air regenerative tank and a combustion zone, the air regenerative tank is connected to the combustion zone through an air injection port and a gas injection port, the air injection port comprises a primary air injection port and a secondary air injection port, and the gas injection port, the primary air injection port, and the secondary air injection port are arranged in sequence.

[0007] Optionally, the primary air injection port comprises two injection ports, and the secondary air injection port comprises three injection ports.

[0008] Optionally, the diameter D1 of the primary air nozzle and the diameter D2 of the secondary air nozzle satisfy 0.9D2≤D1≤1.1D2.

[0009] Optionally, the gas nozzle is a single nozzle; and the side projection of the gas nozzle and the secondary air nozzle shows an isosceles triangle with the gas nozzle as the vertex.

[0010] Optionally, the adjacent center distance L1 of the primary air nozzle satisfies 2D1≤L1≤5D1; and the top angle D of the isosceles triangle satisfies 50°<D<90°, preferably 60°.

[0011] Optionally, the two secondary air nozzles are symmetrically arranged on two sides of the height of the isosceles triangle, the center distance L2 is greater than or equal to 2D3, and the center point does not exceed the waist line of the triangle.

[0012] Optionally, the axis of the secondary air nozzle is horizontally arranged, the axis of the primary air nozzle is inclined to the direction of the gas nozzle at an inclination angle of 0°-15°, and the axis of the gas nozzle is inclined to the direction of the air nozzle at an inclination angle of 0°-20°.

[0013] Optionally, the position of the primary air nozzle in the height direction of the isosceles triangle is at the midpoint or the midpoint on the side of the primary air nozzle, and the center distance of any two adjacent air nozzles is not less than 2D1.

[0014] Optionally, the included angle between the axis of the primary air nozzle and the axis of the gas nozzle is less than or equal to 30°.

[0015] Optionally, the working flow rate of the gas nozzle and the working flow rate of the air nozzle are both greater than or equal to 60 m / s, and the difference between the two is less than or equal to 20%.

[0016] The beneficial effects of the present application are as follows:

[0017] The low-nitrogen oxide air single-regenerative burner of the present application significantly inhibits the generation of nitrogen oxides while maintaining the efficient combustion of high-calorific-value fuels through innovative structural design, and its core advantages are reflected in the following three aspects:

[0018] Synergistic nitrogen reduction mechanism of staged combustion and flue gas internal circulation

[0019] Based on an isosceles triangular nozzle spatial structure (gas nozzle at the vertex, primary air dual nozzles at the waistline, and secondary air triple nozzles distributed at the base), an expanded recirculation region is formed at the flame root. This structure significantly enhances the entrainment intensity of high-temperature combustion products towards the nozzle direction, achieving active internal circulation of flue gas in the combustion initiation zone. The internally circulated flue gas dilutes the local oxygen concentration, reduces the mixing rate of gas and air, suppresses the intensity of the combustion reaction from the source, avoids the formation of local high-temperature zones, and thus significantly weakens the basis for the formation of thermal nitrogen oxides.

[0020] The expanded layout of the primary and secondary air nozzles (apex angle 50°–90°) further widens the transition zone between the primary and secondary air. This zone becomes the priority channel for flue gas recirculation, continuously reducing the oxygen partial pressure and allowing the combustion gas to undergo oxygen-deficient combustion in the primary air zone, forming a reducing atmosphere to essentially block the formation path of nitrogen oxides. After unburned combustion gas and primary combustion products penetrate into the secondary air zone, they complete final combustion in a low-oxygen concentration environment, achieving a smoothing of the overall temperature gradient of the reaction.

[0021] Optimization of dynamic stability of flame morphology and temperature field

[0022] The single gas nozzle design, combined with high-velocity control, significantly enhances the momentum of the gas stream and extends its injection distance. This design prevents the gas from being prematurely torn apart by the air stream, thus avoiding concentration buildup, eliminating the risk of localized high temperatures, and maintaining flame length stability.

[0023] The tilt angle of the air nozzle towards the gas nozzle and the reverse tilt angle of the gas nozzle towards the air nozzle create a directional convergence of the gas and air jets. This cross-mixing mode expands the combustion coverage area while constraining the spread direction of the flame pattern, preventing temperature field runaway caused by flame dispersion.

[0024] Precise control of nozzle spacing ensures that each stream develops independently without premature mixing, avoids combustion oscillations caused by stream interference, and guarantees uniform overall temperature distribution.

[0025] Enhanced adaptability of high-calorific-value fuels and synergistic control of pollutants

[0026] By reducing the temperature of the combustion core zone and expanding the reaction area, the tendency of high-carbon hydrocarbons in high-calorific-value gaseous fuels (such as coke oven gas and natural gas) to crack at high temperatures is effectively suppressed, reducing the formation of carbon black and avoiding an increase in particulate matter emissions and a loss of combustion efficiency.

[0027] Flow rate difference threshold control ensures momentum matching of the flow streams, prevents high-speed flow streams from shearing and damaging low-speed flow streams, maintains the stability of the staged combustion structure, and guarantees the sustainability of low-NOx performance from an operational perspective.

[0028] Industrial application value

[0029] This burner structure is compatible with existing heat storage systems, requiring no modification to the furnace body or the addition of external recirculation devices. It significantly reduces nitrogen oxide emissions in high-temperature equipment such as metallurgical heating furnaces and chemical cracking furnaces, while simultaneously improving temperature uniformity in the heating zone. Its compact design is particularly suitable for space-constrained industrial environments, providing key technological support for the clean and efficient utilization of high-calorific-value gaseous fuels.

[0030] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0032] Figure 1 This is a schematic diagram of the solution;

[0033] Figure 2 for Figure 1 The E-direction view.

[0034] Attached reference numerals: 1 Air heat storage box, 2-1 Primary air nozzle, 2-2 Secondary air nozzle, 3 Gas nozzle, 4 Combustion zone. Detailed Implementation

[0035] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0036] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0037] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present 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, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0038] Please see Figures 1-2 The low-nitrogen oxide air regenerative burner of the present invention will be described in detail below with reference to the accompanying drawings. This embodiment takes the application scenario of a metallurgical heating furnace using coke oven gas as fuel as an example, but this solution is also applicable to industrial thermal equipment using other high-calorific-value gaseous fuels such as natural gas and liquefied petroleum gas.

[0039] Overall structural layout

[0040] like Figure 1 As shown, the burner includes an air heat storage box 1, a primary air nozzle 2-1, a secondary air nozzle 2-2, a gas nozzle 3, and a downstream combustion zone 4. The air heat storage box 1 is connected to a high-temperature flue gas waste heat recovery system via a pipeline, which can preheat the combustion air. The preheated air is divided into two paths: one path leads to the two primary air nozzles 2-1 through the primary air channel, and the other path leads to the three secondary air nozzles 2-2 through the secondary air channel. The gas nozzle 3 is independently connected to the gas supply pipeline.

[0041] Nozzle spatial relationship and geometric parameters

[0042] Reference Figure 2 Side view projection:

[0043] The gas nozzle 3 is positioned centrally at the apex;

[0044] The two primary air nozzles 2-1 are located on the two sides of an isosceles triangle, and the line connecting their centers is parallel to the base of the triangle.

[0045] Three secondary air nozzles 2-2 are distributed along the base of the triangle, with two nozzles symmetrically arranged on both sides of the height of the triangle and the third nozzle located at the midpoint of the base.

[0046] The critical dimensional constraints are as follows:

[0047] The diameter of the primary air nozzle 2-1 is denoted as D1, the diameter of the secondary air nozzle 2-2 is denoted as D2, and the diameter of the gas nozzle 3 is denoted as D3, satisfying: 0.9D2≤D1≤1.1D2;

[0048] In the preferred embodiment, D1 = D2 is taken.

[0049] The center distance L1 between adjacent primary air nozzles 2-1 satisfies: 2D1 ≤ L1 ≤ 5D1;

[0050] The range of the apex angle D of the isosceles triangle is: 50° < D < 90°; preferably D = 60°.

[0051] The center distance L2 of the symmetrically distributed secondary air nozzles 2-2 satisfies: L2 ≥ 2D3; and the projection of its center point does not exceed the waist line of the triangle.

[0052] Nozzle inclination angle and flow field control

[0053] The axis of the secondary air nozzle 2-2 is kept horizontally arranged;

[0054] The axis of the primary air nozzle 2-1 is inclined towards the gas nozzle 3, and the inclination angle α ranges from 0° to 15°;

[0055] The axis of the gas nozzle 3 is inclined towards the primary air nozzle 2-1, and the inclination angle β ranges from 0° to 20°.

[0056] This inclination angle design makes the gas flow and the air flow form cross mixing, expanding the combustion coverage range.

[0057] Flow velocity and operating parameters

[0058] The operating flow velocity of the gas nozzle 3 ≥ 60 m / s;

[0059] The operating flow velocities of both the primary air nozzle 2-1 and the secondary air nozzle 2-2 ≥ 60 m / s;

[0060] The flow velocity difference between the gas and the air ≤ 20%.

[0061] High flow velocity ensures the penetration of the flow, preventing premature diffusion of the gas and resulting in too high local concentration.

[0062] Combustion mechanism and pollutant control

[0063] Primary combustion stage:

[0064] The gas is ejected from the nozzle 3 at high speed and mixed with the obliquely injected primary air at the front end of the combustion zone 4. Since the oxygen is diluted by the recirculating flue gas, this area is in an oxygen-deficient state, and the gas burns partially in a reducing atmosphere, and basically no NOx is generated.

[0065] Secondary combustion stage:

[0066] The unburned gas penetrates the primary air flow and entrains the combustion products to impact the area of the secondary air nozzle 2-2. The stepped supply of the secondary air enables the remaining gas to complete combustion at a low oxygen concentration. The overall temperature distribution in the combustion zone 4 is flat, and the maximum temperature is significantly reduced.

[0067] Enhanced flue gas recirculation:

[0068] An isosceles triangular arrangement forms an expanded recirculation zone 5 behind the gas nozzle 3. High-temperature flue gas flows back towards the nozzle, creating a local reducing atmosphere and further suppressing the formation of thermal NOx. At the same time, the expanded space between the primary air nozzle 2-1 and the secondary air nozzle 2-2 (determined by the apex angle D) enhances the flue gas entrainment intensity.

[0069] High calorific value fuel adaptability

[0070] For high-carbon hydrocarbon fuels such as coke oven gas, hydrocarbon cracking is effectively suppressed and soot formation is avoided by reducing the core combustion temperature and expanding the reaction zone. Nozzle spacing constraints prevent flame pulsation caused by stream interference and maintain a stable temperature field.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A low-nitrogen oxide air-only regenerative burner, characterized in that: It includes an air heat storage box and a combustion zone. The air heat storage box is connected to the combustion zone through an air nozzle and a gas nozzle. The air nozzle includes a primary air nozzle and a secondary air nozzle, and the gas nozzle, the primary air nozzle, and the secondary air nozzle are arranged in sequence.

2. The low-nitrogen-oxide-air single-cell regenerative burner according to claim 1, characterized in that: The primary air nozzle comprises two nozzles, and the secondary air nozzle comprises three nozzles.

3. The low-nitrogen-oxide-air single regenerative burner according to claim 1, characterized in that: The diameter of the primary air nozzle is D1, and the diameter of the secondary air nozzle is D2; wherein: 0.9D2≤D1≤1.1D2.

4. The low-nitrogen-oxide-air single regenerative burner according to claim 1, characterized in that: The gas nozzle is a single nozzle; the side view projection of the gas nozzle and the secondary air nozzle is an isosceles triangle with the gas nozzle as the vertex.

5. The low-nitrogen oxide air-only regenerative burner according to claim 4, characterized in that: The center-to-center distance L1 between adjacent air nozzles satisfies: 2D1≤L1≤5D1; the vertex angle D of the isosceles triangle is 50°. <D<90°。 6. The low-nitrogen-oxide-air single regenerative burner according to claim 4, characterized in that: Two secondary air nozzles are symmetrically positioned on both sides of the height of an isosceles triangle, with a center distance L2 ≥ 2D3, and the center point does not extend beyond the waist line of the triangle.

7. The low-nitrogen-oxide-air single regenerative burner according to claim 1, characterized in that: The secondary air nozzle axis is horizontally arranged, the primary air nozzle axis is inclined towards the gas nozzle direction at an angle of 0° to 15°, and the gas nozzle axis is inclined towards the air nozzle direction at an angle of 0° to 20°.

8. The low-nitrogen oxide air-only regenerative burner according to claim 1, characterized in that: The position of the primary air nozzle in the height direction of the isosceles triangle is located at the midpoint or the side of the midpoint near the primary air nozzle, and the center distance between any two adjacent air nozzles is not less than 2D1.

9. The low-nitrogen oxide air regenerative burner according to claim 1, characterized in that: The angle between the axis of the primary air nozzle and the axis of the gas nozzle is less than or equal to 30°.

10. The low-nitrogen-oxide-air single-regenerative burner according to claims 1 to 9, characterized in that: The operating velocity of the gas nozzle and the operating velocity of the air nozzle are both greater than or equal to 60 m / s, and the difference between them is less than or equal to 20%.

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