flue gas recirculation burner

Abstract

This invention provides a flue gas internal circulation burner, comprising: an ignition gun; a primary gas pipe, wherein a primary gas nozzle is provided on the primary gas pipe, and the primary gas pipe is radially disposed outside the ignition gun; a secondary gas pipe, wherein a secondary gas nozzle is provided on the secondary gas pipe, and the secondary gas pipe is radially disposed outside the primary gas pipe; an air guide inner cylinder, which is radially disposed between the primary and secondary gas pipes; and an air guide outer cylinder, which is radially disposed outside the air guide inner cylinder. The air guide inner cylinder and the air guide outer cylinder form a Venturi structure, which includes, along the air flow direction therein, a constriction section, a throat section, and a diffuser section in sequence, and the air guide outer cylinder has a flue gas circulation opening at the throat section. The flue gas internal circulation burner of this invention can enhance the flue gas internal circulation effect, promote the mixing of fuel gas, combustion air, and flue gas, and eliminates the need for an additional flue gas external circulation pipe.

Description

Technical Field

[0001] This invention relates generally to the field of burner technology, and more specifically to a flue gas internal circulation burner. Background Technology

[0002] With the vigorous implementation of my country's energy conservation and emission reduction policies, the NOx emission standard for gas burners has been reduced to 30 mg / Nm³. 3 Nationwide low-NOx retrofit projects are progressing steadily, primarily employing surface burners and flue gas recirculation (FGR) low-NOx burners. Surface burners often use a larger excess air coefficient to reduce NOx emissions, which can negatively impact their thermal efficiency to some extent. FGR low-NOx burners, on the other hand, achieve low-NOx combustion by adding an external flue gas recirculation duct, mixing some flue gas with combustion air. This not only makes the overall equipment more complex but also presents challenges in addressing the condensation problem in the flue gas recirculation duct.

[0003] Based on the aforementioned industrial application background of low-NOx burners, and to effectively address the shortcomings of current low-NOx combustion technology, internal flue gas recirculation technology has been proposed. This technology eliminates the need for excess air or external flue gas recirculation pipes, instead implementing a self-circulating flue gas process within the furnace to reduce the oxygen content of the combustion air and thus decrease NOx emissions. For internal flue gas recirculation burners, enhancing the internal recirculation effect and promoting the mixing of fuel gas, combustion air, and flue gas are key to reducing NOx emissions.

[0004] Therefore, there is a need to provide a flue gas recirculation burner to at least partially solve the above problems. Summary of the Invention

[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0006] To at least partially solve the above problems, the present invention provides a flue gas recirculation burner, the flue gas recirculation burner comprising:

[0007] Lighter;

[0008] A primary gas pipe is provided with a primary gas nozzle, and the primary gas pipe is arranged radially on the outside of the ignition gun.

[0009] A secondary gas pipe, wherein the secondary gas pipe is provided with a secondary gas nozzle, and the secondary gas pipe is arranged radially outside the primary gas pipe;

[0010] An air guide inner cylinder is arranged radially between the primary gas pipe and the secondary gas pipe;

[0011] An air guide outer cylinder is arranged radially outside the air guide inner cylinder;

[0012] The inner air guide cylinder and the outer air guide cylinder form a Venturi structure, which includes a constriction section, a throat section and a diffusion section in sequence along the air flow direction. The outer air guide cylinder is provided with a flue gas circulation opening in the throat section.

[0013] Optionally, the primary gas pipe extends axially beyond the secondary gas pipe, such that the primary gas nozzle is located downstream of the throat section of the Venturi structure, and the secondary gas nozzle is located upstream of the throat section of the Venturi structure.

[0014] Optionally, the flue gas internal circulation burner includes a flame tube assembly, the flame tube assembly includes the air guide outer cylinder and a flame tube arranged radially outside the air guide outer cylinder, the flame tube is provided with a flue gas circulation groove, the flue gas circulation groove of the flame tube is arranged at a position corresponding to the position of the flue gas circulation opening of the air guide outer cylinder.

[0015] Optionally, the flue gas recirculation burner includes a flame stabilizer assembly, which includes the air guide inner cylinder and a flame stabilizer disposed radially inside the air guide inner cylinder.

[0016] Optionally, the flue gas internal circulation burner further includes a gas passage outer sleeve and a gas passage inner sleeve, the ignition gun is arranged radially inside the gas passage inner sleeve, the primary gas pipe is arranged radially between the gas passage outer sleeve and the gas passage inner sleeve, and the secondary gas pipe is arranged radially outside the gas passage outer sleeve.

[0017] Optionally, the flue gas circulation opening of the air guide outer cylinder is inclined according to the air flow direction in the Venturi structure.

[0018] Optionally, the flue gas circulation groove of the flame tube extends axially from the starting end of the venturi structure beyond the axial position of the flue gas circulation opening of the air guide outer tube.

[0019] Optionally, the angle between the axis of the flue gas circulation opening of the air guide outer cylinder and the central axis of the burner is 30° to 60°.

[0020] Optionally, the ratio of the diameter of the throat section of the venturi structure to the radius of the flame tube is 0.09-0.18.

[0021] Optionally, the ratio of the length of the throat section of the venturi structure to the radius of the flame tube is 0.013-0.25.

[0022] Optionally, the ratio of the width of the flue gas circulation opening of the air guide outer cylinder to the radius of the flame tube is 0.02-0.05.

[0023] Optionally, the ratio of the flue gas circulation groove of the flame tube to the radius of the flame tube is 0.3-0.45.

[0024] Optionally, the portion of the air guide inner cylinder forming the diffuser section is inclined toward the central axis of the burner at an angle of 10° to 20°.

[0025] Optionally, the air guide inner cylinder includes a straight extension section adjacent to the portion of the air guide inner cylinder that forms the contraction section.

[0026] Optionally, the ratio of the length of the straight extension section to the radius of the flame tube is 0.06-0.13.

[0027] Optionally, the ratio of the airflow width inside the straight extension section of the air guide inner cylinder to the radius of the flame tube is 0.18-0.25.

[0028] The flue gas internal circulation burner according to the present invention, by setting an air guide outer cylinder and an air guide inner cylinder and making them cooperate to form a Venturi structure, can enhance the flue gas internal circulation effect and promote the mixing of fuel gas, combustion air and flue gas; it eliminates the need for additional flue gas external circulation pipes and avoids condensate problems; it can simplify low-NOx burner equipment; it can reduce burner operating costs and lower risks; it ensures boiler combustion efficiency; and it effectively ensures that NOx emissions are reduced to 30 mg / Nm³ under the above-mentioned beneficial effects. 3 . Attached Figure Description

[0029] The following drawings, which illustrate embodiments of the present invention, are included as part of this invention for understanding its principles. The drawings depict embodiments of the invention and their descriptions, serving to explain the principles of the invention. In the drawings,

[0030] Figure 1 This is a cross-sectional side view of a flue gas recirculation burner according to an embodiment of the present invention;

[0031] Figure 2 This is a front view of a flue gas recirculation burner according to an embodiment of the present invention;

[0032] Figure 3 A partial cross-sectional side view of a flue gas internal recirculation burner according to an embodiment of the present invention. Detailed Implementation

[0033] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with embodiments of the invention.

[0034] To fully understand the embodiments of the present invention, detailed structures will be presented in the following description. Obviously, the implementation of the embodiments of the present invention is not limited to the specific details familiar to those skilled in the art.

[0035] This invention provides a flue gas internal recirculation burner. For example... Figure 1 and Figure 2 As shown, the flue gas internal circulation burner includes: ignition gun 1, gas passage assembly 2, burner mounting flange 3, flame tube assembly 4, and flame stabilizer assembly 5. The ignition gun 1 has an ignition function; the gas passage assembly 2 includes a gas passage outer sleeve 21, a gas passage inner sleeve 22, a gas pipe positioning component 23, a primary / inner ring gas pipe equipped with a primary / inner ring gas nozzle 25, and a secondary / outer ring gas pipe located radially outside the primary / inner ring gas pipe and equipped with a secondary / outer ring gas nozzle 24. The primary / inner ring gas nozzle 25 and the secondary / outer ring gas nozzle 24 can realize staged combustion of fuel; the burner mounting flange 3 is used for equipment installation; the flame tube assembly 4 includes a flame tube mounting flange 41, a flame tube 42, and an air guide outer cylinder 43, mainly used to guide the combustion air and provide a path for flue gas internal circulation; the flame stabilizer assembly 5 includes an air guide inner cylinder 51, a flame stabilizer fixing component 52, and a flame stabilizer 53, mainly used to stabilize the flame, achieve a reasonable ratio of combustion air, and promote flue gas internal circulation.

[0036] The inner air guide cylinder 51 and the outer air guide cylinder 43 form a Venturi structure, which extends along the direction of air flow (e.g., ...). Figure 1As shown from right to left, the structure includes a contraction section, a throat section, and a diffusion section. The air guide outer cylinder has multiple flue gas recirculation openings in the throat section. When the combustion air flows through this venturi structure, the airflow velocity increases due to the gradually decreasing cross-sectional area in the contraction section, accelerating to its maximum velocity in the throat section. Therefore, the internal pressure of the venturi structure is lowest in the throat section, which helps the externally recirculating flue gas to flow into the venturi structure through the flue gas recirculation openings in the throat section (the flue gas volume can reach 10%-12% of the air volume), thereby enhancing the internal flue gas recirculation effect and promoting the mixing of fuel gas, combustion air, and flue gas.

[0037] According to the flue gas recirculation burner of the present invention, the primary gas pipe extends axially beyond the secondary gas pipe, such that the primary gas nozzle 25 is located axially downstream of the throat section of the Venturi structure (e.g., Figure 1 As shown, the first-stage gas nozzle 25 extends axially beyond the terminating end of the diffuser section of the Venturi structure, and the second-stage gas nozzle 24 is located axially upstream of the throat section of the Venturi structure (e.g., Figure 1 As shown, the secondary gas nozzle 24 is located at the contraction section of the Venturi structure along the axial direction. Multiple primary / inner ring gas pipes and multiple secondary / outer ring gas pipes are arranged circumferentially to achieve flame segmentation. The arrangement of multiple inner ring gas pipes and multiple outer ring gas pipes, with the outer ring gas pipes being concave relative to the inner ring gas pipes along the axial direction, enhances the staged combustion effect and strengthens the mixing and combustion of recirculated flue gas and combustion air.

[0038] According to the flue gas internal circulation burner of the present invention, the flame tube 42 is arranged radially outside the air guide outer tube 43, and the flame tube 42 and the air guide outer tube 43 can be integrally formed. The flame tube 42 is provided with multiple flue gas circulation slots, such as... Figure 3 As shown, the flue gas circulation groove of the flame tube is positioned corresponding to the flue gas circulation opening of the air guide outer cylinder. This arrangement facilitates that a portion of the flue gas generated during combustion sequentially enters the Venturi structure formed by the air guide outer cylinder 43 and the air guide inner cylinder 51 through the flue gas circulation groove of the flame tube and the flue gas circulation opening of the air guide outer cylinder, thereby mixing with the combustion air. Furthermore, a portion of the recirculated flue gas can mix with the combustion gas ejected by the secondary gas nozzle 24 in the area between the flame tube 42 and the air guide outer cylinder 43 (e.g., Figure 1 (As shown). This enhances the mixing effect of fuel gas, combustion air, and flue gas. Multiple flue gas circulation slots on the flame tube 4.2 can guide backflowing flue gas, providing a path for flue gas circulation; multiple flue gas circulation openings on the air guide outer tube 43 can enhance the internal flue gas circulation effect under the Venturi effect.

[0039] The flame stabilizing disc 53 is radially disposed inside the air guide inner cylinder 51 and axially positioned approximately flush with the terminating end of the diffuser section of the Venturi structure. The flame stabilizing disc 53 and the air guide inner cylinder 51 can be integrally formed. The flame stabilizing disc 53 is equipped with a blade structure, which enables air swirl and provides a flame stabilizing effect.

[0040] According to the flue gas internal recirculation burner of the present invention, such as Figure 1 As shown, the ignition gun 1 is radially disposed inside the inner sleeve 22 of the gas passage, the primary gas pipe is radially disposed between the outer sleeve 21 of the gas passage and the inner sleeve 22 of the gas passage, and the secondary gas pipe is radially disposed outside the outer sleeve 21 of the gas passage. The gas passage assembly 2 of the present invention can optimize the internal and external gas distribution ratio by changing the number and cross-sectional area of ​​the inner and outer gas pipes.

[0041] like Figure 1 As shown, the primary gas nozzle 25 penetrates the flame stabilizer 53 along the axial direction, so that the gas injected by the primary gas nozzle 25 can mix with the combustion air flowing out through the air swirl of the flame stabilizer 53.

[0042] like Figure 3 As shown, the flue gas recirculation opening of the air guide outer cylinder 43 is inclined according to the air flow direction in the Venturi structure, that is, the port of the flue gas recirculation opening on the outer wall of the air guide outer cylinder is closer to the contraction section than the port on the inner wall. This arrangement helps to guide the return flue gas into the Venturi structure formed by the air guide outer cylinder and the air guide inner cylinder under the action of airflow in the Venturi structure. Preferably, the angle θ between the axis of the flue gas recirculation opening of the air guide outer cylinder and the central axis of the burner is 30° to 60°.

[0043] like Figure 3 As shown, the flue gas circulation groove of the flame tube 42 extends axially from the starting end (starting end of the contraction section) of the venturi structure beyond the axial position of the flue gas circulation opening of the air guide outer cylinder 43. This arrangement ensures that sufficient recirculated flue gas enters the area between the flame tube 42 and the air guide outer cylinder 43.

[0044] like Figure 1 and Figure 3 As shown, the portion of the diffuser section of the inner air guide cylinder 51 is inclined inward toward the central axis of the burner, while the portion of the diffuser section of the outer air guide cylinder 43 extends parallel to the central axis of the burner. This arrangement helps to guide the mixture of combustion air flowing out through the venturi structure and return flue gas inward / towards the position pointed to by the primary gas injector 25, thereby achieving mixed combustion with the gas injected by the primary gas injector 25.

[0045] like Figure 1 and Figure 3 As shown, the air guide inner cylinder 51 has a straight extension section at the starting end of its venturi structure. This straight extension section is adjacent to the portion of the air guide inner cylinder that forms the contraction section, thereby dividing the combustion air into a portion that is guided into the venturi structure and another portion that flows along the primary / inner ring gas pipe to the flame stabilizer, thus achieving a reasonable ratio of combustion air between the inner and outer rings.

[0046] According to embodiments of the present invention, such as Figure 3 As shown, for a flue gas recirculation burner with a flame tube radius of R, the airflow width D1 inside the air guide inner cylinder is (0.18-0.25)R, the width D2 of the Venturi structure throat section is (0.09-0.18)R, and the opening width D3 of the flue gas recirculation slot in the air guide outer cylinder is (0.02-0.05)R. The straight extension length L1 of the air guide inner cylinder is (0.06-0.13)R, the throat section length L2 of the Venturi structure is (0.013-0.25)R, and the inward tilt angle of the Venturi structure diffuser section (air guide inner cylinder) is... The angle is 10° to 20°, and the width L3 of the flue gas circulation groove of the flame tube is (0.3-0.45)R.

[0047] According to a preferred embodiment of the present invention, taking a 1.5MW flue gas internal recirculation burner as an example, the flame tube radius is 160mm, the airflow width D1 inside the air guide inner cylinder is 36.5mm, the width D2 of the Venturi structure throat section is 20mm, the opening width D3 of the flue gas recirculation groove in the air guide outer cylinder is 4mm, and the angle θ is 45°. The length L1 of the straight extension section at the rear end of the air guide inner cylinder is 10mm, the length L2 of the Venturi structure throat section is 20mm, and the inward tilt angle of the Venturi structure diffuser section (air guide inner cylinder) is... The angle is 10°, and the width L3 of the flue gas circulation groove of the flame tube is 60mm.

[0048] The flue gas recirculation burner of this invention injects flue gas through internal recirculation, thereby reducing the oxygen concentration in the combustion air. Furthermore, it optimizes the mixing effect by adjusting the ratio of combustion gas and combustion air in the inner and outer rings, thus jointly reducing thermal NOx formation. This flue gas recirculation burner eliminates the need for external flue gas recirculation ducts and controls NOx emissions to 30 mg / Nm³. 3 the following.

[0049] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for descriptive purposes only and is not intended to limit the invention. Terms such as “set” appearing herein can refer to either a component being directly attached to another component or a component being attached to another component via an intermediary. A feature described in one embodiment herein may be applied, alone or in combination with other features, to another embodiment, unless that feature is not applicable in that other embodiment or is otherwise stated.

[0050] The present invention has been described through the above embodiments; however, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the present invention to the described embodiments. Those skilled in the art will understand that many variations and modifications can be made based on the teachings of the present invention, and all such variations and modifications fall within the scope of protection claimed by the present invention.

Claims

1. A flue gas internal circulation burner, characterized in that, The flue gas internal recirculation burner includes: Lighter; A primary gas pipe is provided with a primary gas nozzle, and the primary gas pipe is arranged radially on the outside of the ignition gun. A secondary gas pipe, wherein the secondary gas pipe is provided with a secondary gas nozzle, and the secondary gas pipe is arranged radially outside the primary gas pipe; An air guide inner cylinder is arranged radially between the primary gas pipe and the secondary gas pipe; An air guide outer cylinder is arranged radially outside the air guide inner cylinder; The inner air guide cylinder and the outer air guide cylinder form a Venturi structure. The Venturi structure includes a constriction section, a throat section, and a diffusion section in sequence along the air flow direction. The outer air guide cylinder is provided with a flue gas circulation opening in the throat section. The flue gas circulation opening is located on the outer side wall of the outer air guide cylinder, which is closer to the constriction section than the inner side wall, so as to guide the return flue gas into the Venturi structure. The internal flue gas recirculation burner includes a flame tube assembly, which includes an air guide outer cylinder and a flame tube radially disposed outside the air guide outer cylinder. The flame tube is provided with a flue gas recirculation groove, which is located at a position corresponding to the position of the flue gas recirculation opening of the air guide outer cylinder. The flue gas recirculation groove of the flame tube extends axially from the starting end of the venturi structure beyond the axial position of the flue gas recirculation opening of the air guide outer cylinder, so that the recirculated flue gas enters the area between the flame tube and the air guide outer cylinder.

2. The flue gas internal circulation burner according to claim 1, characterized in that, The primary gas pipe extends axially beyond the secondary gas pipe, such that the primary gas nozzle is located downstream of the throat section of the Venturi structure, and the secondary gas nozzle is located upstream of the throat section of the Venturi structure.

3. The flue gas internal circulation burner according to claim 1, characterized in that, The flue gas internal circulation burner includes a flame stabilizer assembly, which includes the air guide inner cylinder and a flame stabilizer disposed radially inside the air guide inner cylinder.

4. The flue gas internal circulation burner according to claim 1, characterized in that, It also includes a gas passage outer sleeve and a gas passage inner sleeve. The ignition gun is arranged radially inside the gas passage inner sleeve. The primary gas pipe is arranged radially between the gas passage outer sleeve and the gas passage inner sleeve. The secondary gas pipe is arranged radially outside the gas passage outer sleeve.

5. The flue gas internal circulation burner according to claim 1, characterized in that, The flue gas circulation opening of the air guide outer cylinder is inclined according to the air flow direction in the Venturi structure.

6. The flue gas internal circulation burner according to claim 1, characterized in that, The angle between the axis of the flue gas circulation opening of the air guide outer cylinder and the central axis of the burner is 30° to 60°.

7. The flue gas internal circulation burner according to claim 1, characterized in that, The ratio of the diameter of the throat section of the Venturi structure to the radius of the flame tube is 0.09-0.

18.

8. The flue gas internal circulation burner according to claim 1, characterized in that, The ratio of the length of the throat section of the Venturi structure to the radius of the flame tube is 0.013-0.

25.

9. The flue gas internal circulation burner according to claim 1, characterized in that, The ratio of the width of the flue gas circulation opening of the air guide outer cylinder to the radius of the flame tube is 0.02-0.

05.

10. The flue gas internal circulation burner according to claim 1, characterized in that, The ratio of the flue gas circulation groove of the flame tube to the radius of the flame tube is 0.3-0.

45.

11. The flue gas internal circulation burner according to claim 1, characterized in that, The portion of the air guide inner cylinder that forms the diffuser section is inclined toward the central axis of the burner at an angle of 10° to 20°.

12. The flue gas internal circulation burner according to claim 1, characterized in that, The air guide inner cylinder includes a straight extension section, which is adjacent to the portion of the air guide inner cylinder that forms the contraction section.

13. The flue gas internal recirculation burner according to claim 12, characterized in that, The ratio of the length of the straight extension section to the radius of the flame tube is 0.06-0.

13.

14. The flue gas internal recirculation burner according to claim 12, characterized in that, The ratio of the airflow width inside the straight extension section of the air guide inner cylinder to the radius of the flame tube is 0.18-0.25.

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