A low-nitrogen combustion device for a heating furnace

Abstract

The application discloses a low-nitrogen combustion device for a heating furnace, which comprises a combustion channel, a primary combustion pipe and a primary combustion pipe burner arranged on the inner side of the combustion channel, and a secondary combustion pipe burner arranged on the outer side of the combustion channel in a circumferential direction; the secondary combustion pipe is provided with an inner ring injection hole and an outer ring injection hole; the primary combustion pipe burner and the secondary combustion pipe burner are located on the same horizontal plane; the axial direction of the outer ring injection hole and the axial direction of the secondary combustion pipe burner form an angle b1; the axial direction of the inner ring injection hole and the axial direction of the secondary combustion pipe burner form an angle b2; the angle between the conical outer wall of the combustion channel and the axial direction of the secondary combustion pipe burner is c, and b2 > c > b1; and a flue gas flow-through hole is horizontally arranged on the side wall of the combustion channel and communicates with the injection area of the secondary combustion pipe burner and the injection area of the primary burner hole. The present scheme solves the problems of unstable combustion and substandard flue gas emission of a small natural draft heating furnace in the prior art by using multi-point combustion and flue gas internal circulation combustion technology.

Description

TECHNICAL FIELD

[0001] The present application relates to a low-nitrogen combustion device for a heating furnace. BACKGROUND

[0002] The tubular heating furnace is generally composed of a radiation section, a burner and a ventilation system. According to the air suction mode, it can be divided into a natural ventilation mode and a forced ventilation mode. The radiation section temperature is as high as 600-1600℃, and the radiation heat transfer accounts for about 70-80% of the heat load. The burner flame temperature is as high as 1300-1800℃, and the combustion process produces thermal NOx X , resulting in a high NOx X content in the flue gas.

[0003] The GB 31571-2015 Petroleum Chemical Industry Pollutant Discharge Standard stipulates that the heating furnace flue gas nitrogen oxide emission limit is 150mg / Nm3. Some local environmental protection emission standards stipulate that the nitrogen oxide emission limit has decreased to <80mg / Nm3. Since the second half of 2015, a large-scale low-NOx emission modification project has been carried out in various oil refining and chemical plants across the country, and the most direct method is to replace and modify the burners of the tubular heating furnace. However, during the modification process of some small natural draft heating furnaces, it is found that due to the small size (the structure of this type of heating furnace is relatively short and small), the low heat load (generally 1-3 burners per heating furnace), the low-nitrogen burner modification process is prone to cause flame burning of the pipe, unstable combustion and non-compliance of the flue gas.

[0004] The Chinese patent document CN201121890Y discloses a low-nitrogen oxide wall-attached energy-saving environmental protection staged combustion burner, which comprises a combustion channel composed of special-shaped fire channel bricks; a soundproof and heat preservation inner cylinder composed of a soundproof plate and an inner lining of high-temperature heat-resistant fiber, a burner body and a permanent light, a wind channel is arranged in the burner body, and an air inlet is arranged on one side of the burner; two rows of gas guns are arranged, the lower part of the gas gun is located in the burner body, and the upper part is located in the combustion channel, and the two rows of gas guns are arranged in a stepped manner, that is, the outlets of the two rows of gas guns are not at the same height. The scheme is installed at the bottom of the heating furnace, adopts a stepped staged combustion technology, the flame rises along the furnace wall, first heats the furnace wall to become a uniform heat wall carrier, and then radiates heat to the furnace pipe. The furnace pipe is more uniformly subjected to heat radiation, thereby avoiding local overheating and coking of the medium in the pipe, improving the service life of the furnace pipe and the thermal efficiency of the heating furnace. At the same time, the highest flame temperature is reduced, the generation of NOx is reduced, and the purpose of reducing thermodynamic nitrogen oxide is achieved.

[0005] The burner in the prior art is not suitable for use in the burner of a small natural draft heating furnace with small size and low heat load, and the effect is difficult to guarantee. SUMMARY

[0006] The present application aims to provide a low-nitrogen combustion device for a heating furnace to solve the problem of substandard flue gas emission of small natural draft heating furnaces in the prior art.

[0007] To achieve the above-mentioned purpose, the basic scheme of the present application provides a low-nitrogen combustion device for a heating furnace, comprising a burner body, the upper part of the burner body is provided with a combustion channel, the inner side of the combustion channel is provided with a primary combustion pipe and an eternal lamp, the outer side of the combustion channel is circumferentially provided with a secondary combustion pipe and a secondary combustion pipe burner, the secondary combustion pipe burner is provided with an inner ring nozzle and an outer ring nozzle, the primary burner pipe is provided on the primary combustion pipe and extends towards the inner wall of the combustion channel, the end of the primary burner pipe close to the inner wall of the combustion channel is provided with a primary combustion pipe burner, the primary combustion pipe burner and the secondary combustion pipe burner are located in the same horizontal plane; the primary combustion pipe burner is provided with a primary burner hole facing the inner side of the end of the combustion channel; the axial angle between the outer ring nozzle and the secondary combustion pipe burner is b1, the axial angle between the inner ring nozzle and the secondary combustion pipe burner is b2, the angle between the conical outer wall of the combustion channel and the axial direction of the secondary combustion pipe burner is c, and b2>c>b1; the side wall of the combustion channel is horizontally provided with a flue gas flow hole communicating the injection area of the secondary combustion pipe burner and the injection area of the primary burner hole.

[0008] The beneficial effects of the basic scheme are that: by adopting such a configuration, multi-point combustion is formed by the primary combustion pipe burner and the secondary combustion pipe burner, and by the cooperation of the primary burner hole, the inner ring nozzle, the outer ring nozzle and the flue gas flow hole, flue gas recirculation combustion is achieved, the combustion temperature is effectively controlled, the generation of thermal nitrogen oxides is effectively reduced, and the flue gas emission of the heating furnace is up to standard.

[0009] Preferably, the inner ring nozzle is provided with two, the outer ring nozzle is provided with at least three, all the outer ring nozzles and the inner ring nozzles are arranged in a curve, and the outer ring nozzles and the inner ring nozzles form a half-enclosed shape with the opening facing the combustion channel. By adopting such a configuration, the fuel injected by the inner ring nozzle and the outer ring nozzle will form a groove-shaped space on the outer side of the combustion channel, so that the flue gas flowing through the flue gas flow hole is surrounded by the groove-shaped space, thereby further improving the effect of flue gas recirculation combustion, and further reducing the generation of nitrogen oxides.

[0010] Preferably, in order to further stabilize combustion and reduce the generation of nitrogen oxides, the top of the combustion channel is provided with a vertical fire guide hole and a horizontal fire guide hole, the vertical fire guide hole and the horizontal fire guide hole are in communication with each other, and the axial direction of the primary burner hole intersects with the end of the horizontal fire guide hole.

[0011] Preferably, in order to further stabilize combustion, the angle between the transverse ignition hole and the cross section of the combustion channel is between 5°-60°, and the end of the transverse ignition hole located on the outside of the combustion channel is higher than the end located on the inside of the combustion channel.

[0012] Preferably, in order to further reduce the generation of nitrogen oxides, the primary combustion pipe is coaxially arranged with the combustion channel, at least four primary burner pipes are arranged, and all the primary burner pipes are uniformly distributed along the circumference of the primary combustion pipe, and the long-lasting lamp is located on the angle bisector of two adjacent primary burner pipes.

[0013] Preferably, in order to further reduce the generation of nitrogen oxides, the angle between the axial direction of the primary burner hole and the vertical axial direction of the primary combustion pipe is between 15°-30°.

[0014] Preferably, in order to further low-nitrogen combustion, the lower part of the burner body is provided with an automatic execution mechanism for controlling the size of the air inlet damper, which realizes the automatic adjustment of the flue inlet air damper by accepting the adjustment of the flue gas residual oxygen detection signal. The size of the damper is controlled by the flue gas residual oxygen detector according to the detection result, so that the residual oxygen of the flue gas can be stably controlled between 2% to 5%, thereby reducing the generation of nitrogen oxides.

[0015] Preferably, in order to further realize rapid maintenance and stable adjustment, the primary combustion pipe is connected with the burner body through a limiting bolt, and the primary combustion pipe is communicated with a primary fuel gas main pipe provided with a primary fuel gas control valve; the secondary combustion pipe is connected with the burner body through a flange, and the secondary combustion pipe is communicated with a secondary fuel gas main pipe provided with a secondary fuel gas control valve. By adjusting the primary fuel gas control valve and the secondary fuel gas control valve, stable combustion of the burner under different loads can be realized.

[0016] Preferably, in order to further realize rapid maintenance, the bottom of the burner body is reserved to be provided with a flame detector access hole, and the flame detector is connected with the bottom of the burner body through a flange.

[0017] The present application has the following beneficial effects:

[0018] The present application makes full use of multi-point combustion to disperse the original concentrated combustion, which provides conditions for adjusting the flame temperature. Through staged combustion and special combustion channel structure, flue gas recirculation combustion is realized, the combustion temperature is effectively controlled, the generation of thermal type nitrogen oxides is effectively reduced, the flue gas emission of the small natural draft heating furnace can easily meet the standard. Through the special angle of the spray hole, the flame combustion space can be effectively controlled to adapt to the small natural draft heating furnace with small furnace, and the phenomenon of flame burning pipe is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Figure 1 is a schematic view of an embodiment of a low-nitrogen combustion device for a heating furnace according to the present application;

[0020] Figure 2 Figure 2 is a schematic view of a primary combustion tube according to the present application; Figure 1 Figure 3 is an enlarged view of the area A in Figure 2;

[0021] Figure 3 Figure 4 is a top view of a secondary combustion tube burner according to the present application; Figure 2 Figure 5 is a schematic view of a primary combustion tube according to the present application.

[0022] Figure 4 Figure 6 is a schematic view of a primary combustion tube according to the present application. Figure 1 DETAILED DESCRIPTION

[0023] The application will be further described in detail below with specific embodiments:

[0024] The reference signs in the attached drawings of the specification include: combustion channel 1, secondary combustion tube burner 2, secondary combustion tube 3, primary burner tube 4, primary combustion tube 5, permanent light 6, heat insulation layer 7, flame detector access hole 8, damper 9, flue gas residual oxygen detector 10, vertical pilot hole 11, horizontal pilot hole 12, pilot groove 13, flue gas flow hole 14, primary burner hole 15, outer ring injection hole 16, inner ring injection hole 17, primary fuel gas control valve 18, primary fuel gas main pipe 19, secondary fuel gas main pipe 20, secondary fuel gas control valve 21.

[0025] The embodiment is substantially as described in the attached drawings of the specification Figures 1 to 4 ​The application discloses a low-nitrogen combustion device for a heating furnace, which comprises a burner body, the upper portion of the burner body is provided with a combustion channel 1, and the outer wall of the upper portion of the combustion channel 1 is conical. The top of the combustion channel 1 is provided with a vertical ignition hole 11 and a transverse ignition hole 12, the vertical ignition hole 11 and the transverse ignition hole 12 are communicated with each other. One end of the transverse ignition hole 12 located on the outer side of the combustion channel 1 is higher than the other end located on the inner side of the combustion channel 1, and the included angle d between the transverse ignition hole 12 and the cross section of the combustion channel 1 is between 5° and 60°, for example, 5°, 15°, 20°, 30°, 40°, 50°, 60° and the like. The inner edge of the combustion channel 1 is provided with an ignition groove 13 communicated with the transverse ignition hole 12. The inner side of the combustion channel 1 is provided with a primary combustion pipe 5, the primary combustion pipe 5 is coaxially arranged with the combustion channel 1, and in the embodiment, the primary combustion pipe 5 is connected with the burner body through a limiting bolt. The primary combustion pipe 5 is provided with a plurality of primary burner pipe 4, the primary burner pipe 4 is arranged in the radial direction of the combustion channel 1, and in the embodiment, the primary burner pipe 4 is provided with four primary burner pipes 4, the four primary burner pipes 4 are uniformly distributed in the circumferential direction of the primary combustion pipe 5 in a cross shape. One end of the primary burner pipe 4 close to the inner wall of the combustion channel 1 is provided with a primary combustion pipe burner, the primary combustion pipe burner is provided with a primary burner hole 15, the primary burner hole 15 is arranged on the end portion inner edge of the combustion channel 1, and the axial direction of the primary burner hole 15 intersects with the end portion of the transverse ignition hole 12. The included angle a between the axial direction of the primary burner hole 15 and the vertical axial direction of the primary combustion pipe 5 is between 15° and 30°, for example, 15°, 20°, 25°, 30° and the like.

[0026] The outer side of the burner body is circumferentially provided with a secondary combustion pipe 3, and in the embodiment, the secondary combustion pipe 3 is connected with the burner body through a flange. The end portion of the secondary combustion pipe 3 is provided with a secondary combustion pipe burner 2, and the secondary combustion pipe burner 2 is distributed in the circumferential direction of the combustion channel 1. The secondary combustion pipe burner 2 is located in the same horizontal plane as the primary combustion pipe burner. In order to facilitate the arrangement, the secondary combustion pipe burner 2 is correspondingly arranged with the primary burner pipe 4. The secondary combustion pipe burner 2 is provided with an inner ring nozzle 17 and an outer ring nozzle 16, the axial direction of the outer ring nozzle 16 and the axial direction of the secondary combustion pipe burner 2 form an included angle b1, the axial direction of the inner ring nozzle 17 and the axial direction of the secondary combustion pipe burner 2 form an included angle b2, the conical outer wall of the combustion channel 1 and the axial direction of the secondary combustion pipe burner 2 form an included angle c, and b2>c>b1. In the embodiment, the inner ring nozzle 17 is provided with two inner ring nozzles 17, the outer ring nozzle 16 is provided with three outer ring nozzles 16, all the outer ring nozzles 16 and the inner ring nozzles 17 are distributed in a curve, and the outer ring nozzles 16 and the inner ring nozzles 17 form a half-enclosed shape with the opening facing the combustion channel 1.

[0027] The side wall of the combustion path 1 is horizontally provided with a flue gas flow hole 14 which communicates the injection area of the secondary combustion pipe burner 2 and the injection area of the primary burner hole 15. The flue gas flow hole 14 is arranged close to the primary burner pipe 4 and the secondary combustion pipe burner 2. The inner side of the burner body is provided with a long-lasting lamp 6 which is located on the angle bisector of the adjacent two primary burner pipes 4, and the long-lasting lamp 6 is connected with the bottom of the burner body through a flange. The lower part of the burner body is provided with an automatic actuating mechanism which controls the size of the damper 9, and the actuating mechanism is connected with a flue gas residual oxygen detector 10. The automatic actuating mechanism realizes the automatic adjustment of the flue inlet damper by accepting the adjustment signal of the flue gas residual oxygen detection. The bottom of the burner body is provided with a flame detector access hole 8, and the flame detector is connected with the bottom of the burner body through a flange. The lower part of the burner body is provided with a heat insulation layer 7.

[0028] In the embodiment, the primary combustion pipe 5 is communicated with a primary fuel gas main pipe 19 which is provided with a primary fuel gas control valve 18, and the secondary combustion pipe 3 is communicated with a secondary fuel gas main pipe 20 which is provided with a secondary fuel gas control valve 21. By adjusting the primary fuel gas control valve 18 and the secondary fuel gas control valve 21, the stable combustion of the burner under different loads can be realized. In the embodiment, the secondary fuel gas main pipe 20 is annular, so that all the secondary combustion pipes 3 are communicated with the secondary fuel gas main pipe 20.

[0029] The present application realizes the multi-point combustion through the plurality of primary burner holes 15 and the plurality of secondary combustion pipe burners 2, and realizes the internal circulation of the flue gas of the combustion path 1 under the cooperation of the vertical pilot hole 11, the horizontal pilot hole 12 and the flue gas flow hole 14, so that the oxygen concentration in the combustion process can be effectively controlled, the combustion temperature can be reduced, the concentration of nitrogen oxides in the flue gas can be reduced, and the stable low-nitrogen combustion of the heating furnace is realized.

[0030] The above-mentioned is only the embodiment of the present application, and the well-known specific structure and characteristics and other common knowledge in the scheme are not described in detail. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should be regarded as the protection scope of the present application, and these will not affect the effect and practicality of the patent.

Claims

1. A low-nitrogen combustion device for a heating furnace, comprising a burner body, an upper part of the burner body is provided with a combustion channel, an inner side of the combustion channel is provided with a primary combustion pipe and a permanent light, an outer side of the combustion channel is circumferentially provided with a secondary combustion pipe and a secondary combustion pipe burner, the secondary combustion pipe burner is provided with an inner ring injection hole and an outer ring injection hole, characterized in that: The primary combustion pipe is provided with a primary burner pipe extending towards the inner wall of the combustion channel, and the primary burner pipe is provided with a primary combustion pipe burner at one end close to the inner wall of the combustion channel, which is located in the same horizontal plane as the secondary combustion pipe burner; the primary combustion pipe burner is provided with a primary burner hole facing the inner side of the end of the combustion channel; the angle between the axial direction of the outer ring injection hole and the axial direction of the secondary combustion pipe burner is b1, the angle between the axial direction of the inner ring injection hole and the axial direction of the secondary combustion pipe burner is b2, and the angle between the conical outer wall of the combustion channel and the axial direction of the secondary combustion pipe burner is c, and b2>c>b1; the side wall of the combustion channel is horizontally provided with a flue gas flow hole communicating the injection area of the secondary combustion pipe burner and the injection area of the primary burner hole; The inner ring injection hole is provided with two, and the outer ring injection hole is provided with at least three, all of which are curvedly distributed, and the outer ring injection hole and the inner ring injection hole form a semi-enclosed shape with the opening facing the combustion channel.

2. A low NOx combustion apparatus for a heating furnace according to claim 1, characterized by: The top of the combustion channel is provided with a vertical pilot hole and a horizontal pilot hole, and the vertical pilot hole and the horizontal pilot hole are in communication with each other, and the axial direction of the primary burner hole intersects with the end of the horizontal pilot hole.

3. A low NOx combustion apparatus for a heating furnace according to claim 2, characterized by: The angle between the horizontal pilot hole and the cross section of the combustion channel is between 5° and 60°, and the end of the horizontal pilot hole located on the outside of the combustion channel is higher than the end located on the inside of the combustion channel.

4. A low NOx combustion apparatus for a heating furnace according to claim 3, characterized in that: The primary combustion pipe is coaxially arranged with the combustion channel, the primary burner pipe is provided with at least four, and all the multiple primary burner pipes are uniformly distributed along the circumference of the primary combustion pipe, and the long-lasting lamp is located on the angle bisector of the adjacent two primary burner pipes.

5. A low NOx combustion apparatus for a heating furnace according to claim 4, characterized in that: The angle between the axial direction of the primary burner hole and the vertical axial direction of the primary combustion pipe is between 15° and 30°.

6. A low NOx combustion apparatus for a heating furnace according to claim 5, characterized by: The lower part of the burner body is provided with an automatic execution mechanism for controlling the size of the air inlet damper, which realizes the automatic adjustment of the flue inlet damper by adjusting the detection signal of the residual oxygen in the flue gas.

7. A low NOx combustion apparatus for a heating furnace according to claim 6, characterized by: The primary combustion pipe is connected with the burner body through a limiting bolt, and the primary combustion pipe is in communication with a primary fuel gas main provided with a primary fuel gas control valve; the secondary combustion pipe is connected with the burner body through a flange, and the secondary combustion pipe is in communication with a secondary fuel gas main provided with a secondary fuel gas control valve.

8. A low NOx combustion apparatus for a heating furnace according to claim 7, characterized by: The bottom of the burner body is provided with a flame detector access hole, and the flame detector is connected with the bottom of the burner body through a flange.

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