Hydrogen-doped low-nitrogen combustor for low-oxygen dilution combustion

Abstract

The application relates to the technical field of burners and discloses a hydrogen-doped low-nitrogen burner for low-oxygen dilution combustion, which comprises a mixed gas ring cavity and a combustion head cover, the combustion head cover is arranged at the end of the mixed gas ring cavity away from the mixed gas ring cavity, and the combustion head cover is provided with an outer flame stabilizing disc and a central flame stabilizing disc; a main fuel gas inlet pipe is connected to the outside of the mixed gas ring cavity; a hydrogen gas ring cavity is coaxially arranged on the outside of the main fuel gas inlet pipe; a plurality of mixed pipes are arranged on the inside of the main fuel gas inlet pipe; a hydrogen gas inlet pipe is arranged on the outside of the hydrogen gas ring cavity; a plurality of mixed gas secondary pipes are arranged on the side of the mixed gas ring cavity close to the combustion head cover; a mixed gas central pipe is further arranged in the mixed gas ring cavity and the combustion head cover; a plurality of central mixed gas primary injection pipes are arranged at one end of the mixed gas central pipe; a plurality of central mixed gas secondary injection pipes are uniformly distributed on the outside of the mixed gas central pipe; and an air accelerating section, an air rectifying section and a porous bluff body are arranged on the outside of the mixed gas central pipe. The application strengthens the low-oxygen effect, avoids local high temperature and reduces the generation of thermal type and rapid type NOx.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of burners, and particularly relates to a hydrogen-doped low-nitrogen burner for low-oxygen dilution combustion. BACKGROUND

[0002] In today's world, traditional fossil fuels such as coal, oil and natural gas bring about environmental pollution, greenhouse effect and many other problems, and hydrogen energy, as a clean renewable energy, has special practical significance.

[0003] Hydrogen combustion has the following characteristics compared with other fuels: high theoretical combustion temperature (about 2050 DEG C), wide explosion limit (4%-75.6%), fast combustion speed (about 10 times the combustion speed of methane), clean and renewable, no carbon emission, and hydrogen-doped fuel is beneficial to improve the ignition condition and reduce carbon emission. The existing burners cannot meet the requirements of hydrogen-doped combustion, and therefore a burner needs to be developed according to the characteristics of the hydrogen-doped combustible mixture to reasonably organize combustion and reduce NOx emission.

[0004] How to design a burner that can control the chemical reaction rate and NOx generation while ensuring sufficient combustion of hydrogen-doped fuel under the premise that the pipeline system meets the combustible gas transportation specification is a problem to be solved by technical personnel. SUMMARY

[0005] The application aims to provide a hydrogen-doped low-nitrogen burner for low-oxygen dilution combustion, which can solve the problems of high combustion temperature, high NOx emission and easy backfire of the existing hydrogen-doped burner.

[0006] To achieve the above technical purpose, the technical scheme adopted by the application is as follows:

[0007] A hydrogen-doped low-nitrogen burner for low-oxygen dilution combustion comprises a mixed gas ring cavity and a combustion head cover, and the mixed gas ring cavity and the combustion head cover are coaxially arranged.

[0008] The combustion head cover is provided with an outer flame stabilizing disc and a central flame stabilizing disc from outside to inside at one end away from the mixed gas ring cavity; a central fireproof cylinder is arranged between the outer flame stabilizing disc and the central flame stabilizing disc; a main fuel gas inlet pipe is connected to the outside of the mixed gas ring cavity; a hydrogen ring cavity is coaxially arranged outside the main fuel gas inlet pipe; a plurality of mixed pipes are arranged inside the main fuel gas inlet pipe and communicate with the hydrogen ring cavity; a hydrogen inlet pipe is arranged outside the hydrogen ring cavity; a plurality of mixed gas secondary pipes are arranged on the side of the mixed gas ring cavity close to the combustion head cover; one end of the mixed gas secondary pipes communicates with the mixed gas ring cavity, and the other end is provided with a plurality of mixed gas holes; a mixed gas central pipe is further arranged inside the mixed gas ring cavity and the combustion head cover, one end of the mixed gas central pipe communicates with the mixed gas ring cavity, and the other end of the mixed gas central pipe is provided with a plurality of central mixed gas primary injection pipes; a plurality of central mixed gas secondary injection pipes are uniformly distributed outside the mixed gas central pipe; one end of the central mixed gas primary injection pipes and the central mixed gas secondary injection pipes communicates with the mixed gas central pipe, and the other end penetrates the central flame stabilizing disc; an air accelerating section, an air rectifying section and a porous bluff body are sequentially arranged outside the mixed gas ring cavity and towards the combustion head cover of the mixed gas central pipe.

[0009] Further, the air accelerating section is a constricted cylinder; the hole diameter of the air accelerating section close to the mixed gas ring cavity is larger than the hole diameter of the air accelerating section away from the mixed gas ring cavity; the air rectifying section is a cylinder with consistent hole diameters at both ends; the porous bluff body is an enlarged cylinder, the hole diameter of the porous bluff body close to the mixed gas ring cavity is smaller than the hole diameter of the porous bluff body away from the mixed gas ring cavity, and a plurality of through holes are uniformly arranged on the surface of the porous bluff body.

[0010] Further, the mixed pipes are arranged in parallel, and the two ends of the mixed pipes respectively communicate with the inner wall of the mixed gas ring cavity; a plurality of hydrogen holes are uniformly arranged on the surface of the mixed pipes.

[0011] Further, one end of the mixed gas secondary pipes close to the outer flame stabilizing disc is sealed, and the mixed gas holes are uniformly distributed at the position outside the mixed gas secondary pipes close to the outer flame stabilizing disc.

[0012] Further, the diameter of the outer flame stabilizing disc is larger than the hole diameter of the combustion head cover.

[0013] Further, the central flame stabilizing disc is a composite structure of a plurality of holes and slots.

[0014] Further, a plurality of rectifying plates are arranged outside the central fireproof cylinder; the rectifying plates are steel rectifying plates.

[0015] Further, the number of the central mixed gas primary injection pipes is 8-12, and the number of the central mixed gas secondary injection pipes is 8-12.

[0016] Further, the air flow speed in the air rectifying section is 50-80 m / s.

[0017] Further, the notch angle of the center and outer flame stabilizing discs is 0-45°.

[0018] The application with the technical scheme has the following advantages:

[0019] (1) The low-oxygen effect is enhanced, the internal flue gas circulation rate Kv (internal flue gas mass flow / combustion air mass flow) can reach 0.3-0.45, the air oxygen content can be reduced to 15.6%, and the chemical reaction process, internal temperature field distribution of the furnace and the generation of thermal NOx can be effectively controlled;

[0020] (2) The internal flow field of the burner is adjusted by the porous bluff body, the center flame air excess coefficient is 1.3, and the total air excess coefficient is 1.1;

[0021] (3) The center flame is further divided by the center mixed gas primary nozzle, the center mixed gas secondary nozzle and the center flame stabilizing disc to form a small flame, the chemical reaction is rapidly completed under the designed equivalence ratio, and the flame temperature is reduced.

[0022] (4) The mixed gas secondary nozzle and the outer flame stabilizing disc form a small premixed flame combustion, the reaction equivalence ratio deviates from the designed value is inhibited, local high temperature is avoided, and the generation of thermal and rapid NOx is reduced.

[0023] (5) The flame structure is pulled up in the radial direction by the structure between the outer flame stabilizing disc and the burner head cover, the end heat exchange efficiency of the burner is improved, and the energy efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] The application can be further illustrated by the non-limiting embodiments shown in the drawings;

[0025] Figure 1 It is a front view of a low-oxygen dilution combustion hydrogen-doped low-nitrogen burner according to the application;

[0026] Figure 2 It is a perspective structural view of a low-oxygen dilution combustion hydrogen-doped low-nitrogen burner according to the application;

[0027] Figure 3 It is a partial structural view of a center flame protection cylinder in a low-oxygen dilution combustion hydrogen-doped low-nitrogen burner according to the application;

[0028] Figure 4 It is a partial structural view of a main fuel gas inlet pipe in a low-oxygen dilution combustion hydrogen-doped low-nitrogen burner according to the application;

[0029] Figure 5It is a partial structure diagram of air accelerating section, air rectifying section and porous bluff body in a hydrogen-doped low-nitrogen combustor of low-oxygen dilution combustion of the present application.

[0030] The main element symbols are explained as follows:

[0031] Air inlet pipe 1; hydrogen inlet pipe 2; hydrogen ring cavity 3; mixing pipe 4; mixed gas ring cavity 5; air passage 6; mixed gas center pipe 7; air accelerating section 8; air rectifying section 9; porous bluff body 10; mixed gas secondary pipe 11; combustor head cover 12; outer flame stabilizer 13; center flame shield 14; center mixed gas primary nozzle 15; center flame stabilizer 16; center mixed gas secondary nozzle 17; rectifying plate 18. DETAILED DESCRIPTION

[0032] The present application will be described in detail below in conjunction with the drawings and specific examples. It should be noted that similar or identical parts are denoted by the same reference numerals in the drawings or description, and the implementation not shown or described in the drawings is in a form known to those skilled in the art. In addition, the directional terms mentioned in the examples, such as "up", "down", "top", "bottom", "left", "right", "front", "back", etc., are only with reference to the direction of the drawings, and are not intended to limit the scope of protection of the present application.

[0033] As shown in Figures 1-5 A hydrogen-doped low-nitrogen combustor of low-oxygen dilution combustion includes a mixed gas ring cavity 5 and a combustor head cover 12, which are installed separately and coaxially. The maximum aperture of the mixed gas ring cavity 5 is consistent with the aperture of the combustor head cover 12. At the same time, there is a gap between the mixed gas ring cavity 5 and the combustor head cover 12, and a relatively large negative pressure is generated near the gap. The flue gas inside the furnace is sucked into the combustor under the action of the negative pressure from the gap between the mixed gas ring cavity 5 and the combustor head cover 12, and is mixed with the combustion air. The air passage 6 is formed between the inner walls of the mixed gas ring cavity 5 for air flow.

[0034] The end of the combustor head cover 12 away from the mixed gas ring cavity 5 is provided with an outer flame stabilizer 13 and a center flame stabilizer 16 from outside to inside in sequence. The outer flame stabilizer 13 and the center flame stabilizer 16 are on the same horizontal plane and adjacent to each other. The outer flame stabilizer 13 and the center flame stabilizer 16 further divide the center flame to form a small flame, and the chemical reaction is rapidly completed under the condition of partial equivalence ratio, which reduces the flame temperature and plays a role in stabilizing the flame through the flow around the backflow. The center flame shield 14 is arranged between the outer flame stabilizer 13 and the center flame stabilizer 16. The center flame shield 14 is a hollow cylinder that surrounds the center flame stabilizer 16 in the cylinder. The center flame shield 14 is a center flame stabilizer that stabilizes the flame through flue gas vortex and keeps the center flame stable combustion.

[0035] The outer side of the mixed gas annular chamber 5 is connected with a main fuel gas inlet pipe 1; one end of the main fuel gas inlet pipe 1 is communicated with the mixed gas annular chamber 5; the outer side of the main fuel gas inlet pipe 1 is coaxially provided with a hydrogen annular chamber 3, and the inner side of the hydrogen annular chamber 3 is attached to the outer side of the mixed gas annular chamber 5; the inner side of the main fuel gas inlet pipe 1 is provided with a plurality of mixed pipes 4 communicated with the hydrogen annular chamber 3, and the outer side of the hydrogen annular chamber 3 is provided with a hydrogen inlet pipe 2; the hydrogen is sprayed out from the mixed pipes 4, and the main fuel gas is mixed with the hydrogen at the position of the mixed pipes 4 and then enters the mixed gas annular chamber 5;

[0036] The mixed gas annular chamber 5 is provided with a plurality of mixed gas secondary pipes 11 on the side close to the combustion head cover 12; the mixed gas secondary pipes 11 are evenly distributed; most of the mixed gas secondary pipes 11 are surrounded by the combustion head cover 12; one end of the mixed gas secondary pipes 11 is communicated with the mixed gas annular chamber 5, and the other end is provided with a plurality of mixed gas holes; the inner side of the mixed gas annular chamber 5 and the combustion head cover 12 is further provided with a mixed gas central pipe 7, one end of the mixed gas central pipe 7 is communicated with the mixed gas annular chamber 5, and the other end is provided with a plurality of central mixed gas primary injection pipes 15; the outer side of the mixed gas central pipe 7 is evenly distributed with a plurality of central mixed gas secondary injection pipes 17; one end of the central mixed gas primary injection pipes 15 and the central mixed gas secondary injection pipes 17 is communicated with the mixed gas central pipe 7, and the other end penetrates the central flame stabilizing disc 16; the central mixed gas primary injection pipes 15 are evenly distributed on the surface of the central flame stabilizing disc 16; the central mixed gas secondary injection pipes 17 are evenly distributed with the mixed gas central pipe 7 as the axis; the mixed gas is evenly distributed in the annular chamber and then flows out of the annular chamber in two ways, one way into the mixed gas central pipe 7 and the other way into the mixed gas secondary pipes 11, and the mixed gas is sprayed out from the mixed gas holes to form micro-premix with the low-oxygen air;

[0037] The outer side of the mixed gas central pipe 7 is sequentially provided with an air accelerating section 8, an air rectifying section 9 and a porous bluff body 10 from the mixed gas annular chamber 5 to the combustion head cover 12; the air enters from the air channel 6, is distributed as central air and secondary air through the air accelerating section 8, the air rectifying section 9 and the porous bluff body 10; the central air and the secondary air adopt different equivalence ratios, the central air excess coefficient is 1.3, the total air excess coefficient is 1.1, and the air gap between the mixed gas annular chamber 5 and the combustion head cover 12 is affected by the induced negative pressure, the flue gas in the furnace enters the burner to mix with the air, thereby reducing the oxygen content of the air, the flue gas circulation rate Kv (internal flue gas mass flow rate / combustion air mass flow rate) in the furnace can reach 0.3-0.45. The oxygen content of the air can be reduced to 15.6%, which can effectively control the chemical reaction process, the internal temperature field distribution of the furnace and the generation of thermal type Nox.

[0038] Compared with the prior art, the hydrogen-doped low-nitrogen combustor for low-oxygen dilution combustion adjusts the flow field inside the combustor through the porous bluff body 10, meets the air excess coefficient of 1.3 of the central flame and the total air excess coefficient of 1.1, further divides the central flame through the central mixed gas primary nozzle 15, the central mixed gas secondary nozzle 17 and the central flame stabilizing disc 16, forms a small flame, rapidly completes the chemical reaction under the design equivalence ratio, and reduces the flame temperature; forms a small premixed flame combustion through the mixed gas secondary pipe 11 and the outer flame stabilizing disc 13, suppresses the equivalence ratio deviation from the design value, avoids local high temperature, and reduces the generation of thermal and rapid NOx; and strengthens the low-oxygen effect, so that the internal flue gas circulation rate Kv (internal flue gas mass flow rate / combustion air mass flow rate) can reach 0.3-0.45. The oxygen content of air can be reduced to 15.6%, and the chemical reaction process, the internal temperature field distribution of the furnace and the generation of thermal NOx can be effectively controlled.

[0039] In some embodiments, the air accelerating section 8 is a converging cylinder, the air accelerating section 8 has a larger hole diameter near one end of the mixed gas annular cavity 5 than a hole diameter far from the one end of the mixed gas annular cavity 5, air flows into the air accelerating section 8 from the air channel 6, the air straightening section 9 is a cylinder with consistent hole diameters at two ends, the porous bluff body 10 is an expanding cylinder, the porous bluff body 10 has a smaller hole diameter near one end of the mixed gas annular cavity 5 than a hole diameter far from the one end of the mixed gas annular cavity 5, and the surface of the porous bluff body 10 is uniformly provided with a plurality of through holes; the porous bluff body 10 quickly forms a complete injection flow after the air is straightened, which helps to suck in the internal flue gas of the furnace, and at the same time, the porous bluff body 10 can adjust the flow field inside the combustor to meet the technical requirements of the air excess coefficient of 1.3 of the central flame and the total air excess coefficient of 1.1; and the oxygen content of air is further reduced, and the chemical reaction process, the internal temperature field distribution of the furnace and the generation of thermal NOx can be effectively controlled.

[0040] In some embodiments, the mixing pipes 4 are arranged in parallel, and the two ends of the mixing pipes 4 are respectively in communication with the inner wall of the mixed gas annular cavity 5; the surface of the mixing pipes 4 is uniformly provided with a plurality of hydrogen holes; the hydrogen in the hydrogen annular cavity 3 uniformly flows out through the hydrogen holes and is fully mixed with the gas flowing into the main gas inlet pipe 1, so as to complete hydrogen doping and mixing. As a more optimal technical solution, the mixing pipes 4 are arranged in a multi-pipe array, the side wall of the mixing pipes 4 is provided with a plurality of hydrogen holes, hydrogen is sprayed out from the hydrogen holes, and the main gas is mixed with hydrogen at the position of the mixing pipes 4 and then enters the mixed gas annular cavity 5.

[0041] In some embodiments, one end of the mixed gas secondary pipe 11 is sealed near the outer flame stabilizing disc 13, the mixed gas holes are uniformly distributed at the position of the outer wall of the mixed gas secondary pipe 11 near the outer flame stabilizing disc 13, and the mixed gas is sprayed out from the mixed gas holes to form a micro-premix with low-oxygen air.

[0042] In some embodiments, the diameter of the outer flame stabilizing disc 13 is greater than the hole diameter of the combustion head cover 12. By so arranging, the flame structure is pulled up in the radial direction, improving the end heat exchange efficiency of the burner and improving energy efficiency.

[0043] In some embodiments, the central flame stabilizing disc 16 is a composite structure of holes and slots, specifically, a plurality of slots are uniformly arranged in the radial direction on the central flame stabilizing disc 16, and holes are uniformly arranged in other places; such an arrangement further divides the central flame to form a small flame, which plays a role in stabilizing the flame.

[0044] In some embodiments, the outer side of the central flame guard 14 is provided with a plurality of flow straightening plates 18; the flow straightening plates 18 are uniformly arranged around the central flame guard 14, the flow straightening plates 18 are steel flow straightening plates 18; in some embodiments, the number of flow straightening plates 18 is 12, the flow straightening plates 18 can be rectangular flow straightening plates, and an angle is formed between the plane where the flow straightening plates 18 are connected and the central flame guard 14, the angle can be any angle in the range of 0-90°; after the air and flue gas in the combustion head cover 12 are mixed, the vortex that may be formed when the air and flue gas are mixed is arranged into a designed flow field state by the flow straightening plates 18.

[0045] In some embodiments, the number of central mixed gas primary nozzles 15 is 8-12; the number of central mixed gas secondary nozzles 17 is 8-12. Such a segmented flame arrangement further strengthens the mixing of air and gas, making the mixing more uniform and rapid, and the chemical reaction is rapidly completed under the designed equivalence ratio, avoiding local temperature, thereby reducing the generation of nitrogen oxides.

[0046] In some embodiments, the air flow speed in the air flow straightening section 9 is 50-80 m / s; at this time, the internal flue gas circulation rate Kv (internal flue gas mass flow rate / comburent air mass flow rate) of the furnace can reach 0.3-0.45. The oxygen content of the air can be reduced to 15.6%, which can effectively control the chemical reaction process, the internal temperature field distribution of the furnace, and the generation of thermal NOx; the low oxygen effect is strengthened.

[0047] In some embodiments, the slot angle of the central flame stabilizing disc 16 and the outer flame stabilizing disc 13 is 0-45°; such an arrangement further divides the mixed gas and low-oxygen air sprayed by the mixed gas secondary nozzle 11, forms a small premixed flame combustion, suppresses the deviation of the reaction equivalence ratio from the design value, avoids local high temperature, reduces the generation of thermal and rapid NOx, and through the cyclone backflow, plays a role in stabilizing the flame, further improving the stability of the combustion.

[0048] The low-oxygen dilution combustion hydrogen-doped low-nitrogen combustor provided by the application is described in detail. The description of the specific embodiments is only used to help understand the method of the application and the core idea thereof. It should be indicated that, for those skilled in the art, some improvements and modifications can be made to the application without departing from the principle of the application, and the improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion, comprising a mixing ring chamber (5) and a burner head cover (12), wherein the mixing ring chamber (5) and the burner head cover (12) are coaxially arranged, characterized in that: At the end of the burner head cover (12) away from the mixed gas ring cavity (5), an outer flame stabilizer (13) and a central flame stabilizer (16) are arranged sequentially from the outside to the inside; a central flame shield (14) is arranged between the outer flame stabilizer (13) and the central flame stabilizer (16); a main gas inlet pipe (1) is connected to the outside of the mixed gas ring cavity (5); a hydrogen ring cavity (3) is coaxially arranged outside the main gas inlet pipe (1), and multiple mixing pipes (4) communicating with the hydrogen ring cavity (3) are arranged inside the main gas inlet pipe (1), and a hydrogen inlet pipe (2) is arranged outside the hydrogen ring cavity (3); multiple secondary mixed gas pipes (11) are arranged on the side of the mixed gas ring cavity (5) near the burner head cover (12); one end of the multiple secondary mixed gas pipes (11) is connected to the mixed gas ring cavity (5), and the other end is connected to the mixed gas ring cavity (5). Multiple mixing holes are provided; a central mixing pipe (7) is also provided inside the mixing ring cavity (5) and the burner head cover (12). One end of the central mixing pipe (7) is connected to the mixing ring cavity (5), and the other end of the central mixing pipe (7) is provided with multiple central mixing primary nozzles (15); multiple central mixing secondary nozzles (17) are evenly distributed on the outside of the central mixing pipe (7); one end of the central mixing primary nozzle (15) and the central mixing secondary nozzle (17) are connected to the central mixing pipe (7), and the other end passes through the central flame stabilizer (16); from the mixing ring cavity (5) to the burner head cover (12), an air acceleration section (8), an air rectification section (9) and a porous blunt body (10) are sequentially provided on the outside of the central mixing pipe (7).

2. The hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 1, characterized in that: The air acceleration section (8) is a constricted cylinder; the diameter of the air acceleration section (8) at the end near the mixing ring cavity (5) is larger than the diameter at the end away from the mixing ring cavity (5); the air rectification section (9) is a cylinder with the same diameter at both ends; the porous blunt body (10) is an enlarged cylinder, the diameter of the porous blunt body (10) at the end near the mixing ring cavity (5) is smaller than the diameter at the end away from the mixing ring cavity (5), and multiple through holes are uniformly arranged on the surface of the porous blunt body (10).

3. The hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 2, characterized in that: The mixing tubes (4) are arranged in parallel, and the two ends of the mixing tubes (4) are respectively connected to the inner wall of the mixing gas ring cavity (5); the surface of the mixing tubes (4) is uniformly provided with a plurality of hydrogen pores.

4. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 3, characterized in that: The end of the secondary gas mixing pipe (11) near the outer flame stabilizer (13) is sealed, and the gas mixing holes are evenly distributed on the outside of the secondary gas mixing pipe (11) near the outer flame stabilizer (13).

5. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 4, characterized in that: The diameter of the outer flame stabilizer (13) is larger than the aperture of the burner head cover (12).

6. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 5, characterized in that: The central flame stabilizer (16) has a composite structure of porous and slotted holes.

7. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 6, characterized in that: Multiple rectifier plates (18) are provided on the outer side of the central fire shield (14); the rectifier plates (18) are steel rectifier plates (18).

8. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 7, characterized in that: The number of the central mixed gas primary nozzles (15) is 8-12; the number of the central mixed gas secondary nozzles (17) is 8-12.

9. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 8, characterized in that: The airflow velocity in the air rectification section (9) is 50-80 m / s.

10. A hydrogen-doped low-NOx burner for low-oxygen dilution combustion according to claim 9, characterized in that: The slot angle of the central flame stabilizer (16) and the outer flame stabilizer (13) is 0-45°.

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