Low-nitrogen combustion device for heating furnace

Abstract

The low-nitrogen combustion device comprises a combustion channel, a first-stage combustion tube and a first-stage combustion tube burner are arranged on the inner side of the combustion channel, and a second-stage combustion tube burner is arranged on the outer side of the combustion channel in the circumferential direction; the first-stage combustion tube is provided with an inner ring spray hole and an outer ring spray hole, the second-stage combustion tube is provided with an inner ring spray hole and an outer ring spray hole, the first-stage combustion tube burner and the second-stage combustion tube burner are located on the same horizontal plane, the included angle between the axial direction of the outer ring spray hole and the axial direction of the second-stage combustion tube burner is b1, and the included angle between the axial direction of the inner ring spray hole and the axial direction of the second-stage combustion tube burner is b2, the included angle between the conical outer wall of the combustion channel and the axial direction of the burner of the secondary combustion tube is c, and c is greater than b2 and greater than b1; and the side wall of the combustion channel is horizontally provided with a flue gas circulation hole which is communicated with the second-stage combustion tube burner nozzle injection area and the first-stage burner nozzle hole injection area. According to the scheme, through the multi-point combustion and flue gas internal circulation combustion technology, the problems that in the prior art, small and medium-sized natural air suction heating furnaces are unstable in combustion, and flue gas emission does not reach the standard are solved.

Description

Technical Field

[0001] The present invention relates to a low-nitrogen combustion device for a heating furnace. Background Art

[0002] A tubular heating furnace generally consists of a radiation section, burners, and a ventilation system. According to the air intake method, it can be divided into a natural ventilation method and a forced ventilation method. The temperature of the radiation section is as high as 600°C - 1600°C, and radiative heat transfer accounts for about 70 - 80% of the heat load. The flame temperature of the burner is as high as 1300°C - 1800°C, and thermal NO is generated during the combustion process X , resulting in a relatively high NO in the flue gas X .

[0003] The "GB 31571-2015 Discharge Standard of Pollutants for the Petroleum Chemical Industry" stipulates that the emission limit of nitrogen oxides in the flue gas of the heating furnace is 150 mg / Nm3. Some local environmental protection discharge standards stipulate that the emission limit of nitrogen oxides has dropped to <80 mg / Nm3. Since the second half of 2015, a large-scale low-NOx emission transformation project has been carried out on all oil refining and chemical installations across the country. The most direct one is to replace and transform the burners of the tubular heating furnace. However, during the transformation of some small natural draft heating furnaces, it was found that due to their small size (the structure of this type of heating furnace is relatively short and small) and low heat load (generally, one heating furnace has 1 - 3 burners), the transformation process of its low-nitrogen burner is extremely likely to cause flame tube burning, unstable combustion, and non-compliant flue gas.

[0004] Chinese Patent Document CN201121890Y discloses a low-nitrogen oxide wall-attached energy-saving and environmental protection staged burner, which includes a combustion channel composed of special-shaped fire bricks; a sound-absorbing and heat-insulating inner cylinder composed of a sound-absorbing plate and a lining of high-temperature heat-resistant fibers, as well as a burner body and a pilot light. An air duct is arranged inside the burner body, and an air inlet is arranged on one side of the burner; two rows of gas guns are arranged, the lower parts of the gas guns are located inside the burner body, and the upper parts are located inside the combustion channel. The two rows of gas guns are arranged in a stepped manner, that is, the gas outlets of the two rows are not at the same height. This solution is installed at the bottom of the heating furnace and uses the stepped staged combustion technology. The flame rises along the furnace wall, first heating the furnace wall into a uniform heat wall carrier, and then radiating the heat to the furnace tubes. This makes the heat radiation received by the furnace tubes more uniform, thereby avoiding local overheating and coking of the medium inside the tubes, improving the service life of the furnace tubes and the thermal efficiency of the heating furnace. At the same time, the maximum flame temperature is reduced, and the generation of NOx is reduced, thereby achieving the purpose of reducing thermodynamic nitrogen oxides.

[0005] The burner in this prior art is not suitable for use in the burners of small natural draft heating furnaces with small size and low heat load, and its effect is difficult to guarantee. Summary of the Invention

[0006] The object of the present invention is to provide a low-nitrogen combustion device for a heating furnace to solve the problem that the flue gas emissions of small natural draft heating furnaces in the prior art do not meet the standards.

[0007] To achieve the above object, the basic solution of the present invention provides a low-nitrogen combustion device for a heating furnace, including a burner body. A combustion channel is arranged on the upper part of the burner body. A primary combustion tube and a pilot burner are arranged on the inner side of the combustion channel. A secondary combustion tube and a secondary combustion tube burner are arranged on the outer circumference of the combustion channel. The secondary combustion tube burner is provided with an inner ring spray hole and an outer ring spray hole. A primary burner tube extending towards the inner wall of the combustion channel is arranged on the primary combustion tube. A primary combustion tube burner is arranged at one end of the primary burner tube close to the inner wall of the combustion channel. The primary combustion tube burner and the secondary combustion tube burner are located on the same horizontal plane; the primary combustion tube burner is provided with a primary burner hole facing the inner edge of the end of the combustion channel; the axial angle between the outer ring spray hole and the axis of the secondary combustion tube burner is b1, the axial angle between the inner ring spray hole and the axis of the secondary combustion tube burner is b2, and the angle between the conical outer wall of the combustion channel and the axis of the secondary combustion tube burner is c, and b2 > c > b1; a flue gas circulation hole communicating the injection area of the secondary combustion tube burner and the injection area of the primary burner hole is horizontally arranged on the side wall of the combustion channel.

[0008] The beneficial effect of this basic solution is as follows: With such a setting, multi-point combustion is formed by the primary combustion tube burner and the secondary combustion tube burner, and through the cooperation of the primary burner hole, the inner ring spray hole, the outer ring spray hole and the flue gas circulation hole, flue gas recirculation combustion is realized, effectively controlling the combustion temperature, thereby effectively reducing the generation of thermal nitrogen oxides, and further making the flue gas emissions of the heating furnace meet the standards.

[0009] Preferably, two inner ring spray holes are provided, at least three outer ring spray holes are provided, all the outer ring spray holes and the inner ring spray holes are distributed in a curve, and the outer ring spray holes and the inner ring spray holes enclose a semi-surrounding shape with the opening facing the combustion channel. With such a setting, the fuel ejected from the inner ring spray hole and the outer ring spray hole will form a groove-shaped space outside the combustion channel, so that the flue gas flowing through the flue gas circulation hole is surrounded by the groove-shaped space, which is beneficial to further improving the effect of flue gas circulation combustion, thereby further reducing the generation of nitrogen oxides.

[0010] Preferably, to further stabilize combustion and reduce the generation of nitrogen oxides, a vertical ignition hole and a horizontal ignition hole are arranged at the top of the combustion channel. The vertical ignition hole and the horizontal ignition hole are communicated with each other, and the axis of the primary burner hole intersects with the end of the horizontal ignition hole.

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

[0012] Preferably, in order to further reduce the generation of nitrogen oxides, the primary combustion tube is coaxially arranged with the combustion channel, at least four primary burner tubes are provided, and all the primary burner tubes are evenly distributed along the circumferential direction of the primary combustion tube, and the pilot burner is located on the angular bisector of two adjacent primary burner tubes.

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

[0014] Preferably, for further low-nitrogen combustion, an automatic actuator for controlling the size of the air intake damper is provided at the lower part of the burner body. The automatic actuator realizes the automatic adjustment of the flue air intake damper through the adjustment of receiving 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, which is beneficial to stably control the residual oxygen in the flue gas between 2% and 5%, thereby reducing the generation of nitrogen oxides.

[0015] Preferably, for further realizing rapid maintenance and stable adjustment, the primary combustion tube is connected to the burner body through a limit bolt, and the primary combustion tube is communicated with a primary fuel gas main pipe provided with a primary fuel gas control valve; the secondary combustion tube is connected to the burner body through a flange, and the secondary combustion tube 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, it is beneficial to realize stable combustion of the burner under different loads.

[0016] Preferably, for further realizing rapid maintenance, a flame detector access hole is reserved at the bottom of the burner body, and the flame detector is connected to the bottom of the burner body through a flange.

[0017] The present invention has the following beneficial effects: The present invention makes full use of multi-point combustion to disperse the original concentrated combustion, providing conditions for adjusting the flame temperature. Through staged combustion and a special combustion channel structure, flue gas recirculation combustion is realized, effectively controlling the combustion temperature, thereby effectively reducing the generation of thermal-type nitrogen oxides and making the flue gas emissions of small natural ventilation heating furnaces easily meet the standards. Through special spray hole angles, the combustion space of the flame can be effectively controlled to adapt to small natural ventilation heating furnaces with a small furnace chamber, avoiding the phenomenon of flame burning the tubes. Description of the Drawings

[0018] Figure 1 Schematic diagram of an embodiment of a low-nitrogen combustion device for a heating furnace according to the present invention; Figure 2 is Figure 1 an enlarged view of part A in Figure 3 is Figure 2 a top view of the burner of the secondary combustion tube in Figure 4 is Figure 1 a schematic diagram of the primary combustion tube in Specific embodiments

[0019] The following is a further detailed description through specific embodiments: The reference numerals in the accompanying drawings of the specification include: combustion channel 1, burner of secondary combustion tube 2, secondary combustion tube 3, primary burner tube 4, primary combustion tube 5, pilot burner 6, heat insulation layer 7, access hole for flame detector 8, air damper 9, flue gas residual oxygen detector 10, vertical ignition hole 11, horizontal ignition hole 12, ignition groove 13, flue gas circulation hole 14, primary burner hole 15, outer ring spray hole 16, inner ring spray 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.

[0020] The embodiment is basically as shown in the attached Figures 1 to 4As shown in the figure: A low-nitrogen combustion device for a heating furnace, including a burner body, a combustion channel 1 is arranged on the upper part of the burner body, and the upper outer wall of the combustion channel 1 is arranged in a conical shape. A vertical ignition hole 11 and a horizontal ignition hole 12 are arranged at the top of the combustion channel 1, and the vertical ignition hole 11 is communicated with the horizontal ignition hole 12. One end of the horizontal ignition hole 12 located outside the combustion channel 1 is higher than the end located inside the combustion channel 1, and the included angle d between the horizontal ignition hole 12 and the cross-section of the combustion channel 1 is between 5° and 60°, such as 5°, 15°, 20°, 30°, 40°, 50°, 60°, etc. A fire guide groove 13 communicated with the horizontal ignition hole 12 is arranged on the inner edge of the combustion channel 1. A primary combustion tube 5 is arranged inside the combustion channel 1, and the primary combustion tube 5 is coaxially arranged with the combustion channel 1. In this embodiment, the primary combustion tube 5 is connected to the burner body through a limit bolt. The primary combustion tube 5 is provided with a plurality of primary burner tubes 4, and the primary burner tubes 4 extend along the radial direction of the combustion channel 1. In this embodiment, four primary burner tubes 4 are arranged, and the four primary burner tubes 4 are evenly distributed along the circumferential direction of the primary combustion tube 5 in a cross shape. One end of the primary burner tube 4 close to the inner wall of the combustion channel 1 is provided with a primary combustion tube burner, and a primary burner hole 15 is arranged on the primary combustion tube burner. The primary burner hole 15 is arranged towards the inner edge of the end of the combustion channel 1, and the axis of the primary burner hole 15 intersects with the end of the horizontal ignition hole 12. The included angle a between the axis of the primary burner hole 15 and the vertical axis of the primary combustion tube 5 is between 15° and 30°, such as 15°, 20°, 25°, 30°, etc.

[0021] A secondary combustion tube 3 is arranged on the outer circumference of the burner body. In this embodiment, the secondary combustion tube 3 is connected to the burner body through a flange. A secondary combustion tube burner 2 is arranged at the end of the secondary combustion tube 3, and the secondary combustion tube burners 2 are distributed along the circumferential direction of the combustion channel 1. The secondary combustion tube burner 2 and the primary combustion tube burner are located on the same horizontal plane. For the convenience of setting, the secondary combustion tube burners 2 and the primary burner tubes 4 are arranged in one-to-one correspondence. The secondary combustion tube burner 2 is provided with an inner ring spray hole 17 and an outer ring spray hole 16. The axial angle between the outer ring spray hole 16 and the axis of the secondary combustion tube burner 2 is b1, and the axial angle between the inner ring spray hole 17 and the axis of the secondary combustion tube burner 2 is b2. The included angle between the conical outer wall of the combustion channel 1 and the axis of the secondary combustion tube burner 2 is c, and b2 > c > b1. In this embodiment, two inner ring spray holes 17 are arranged, and three outer ring spray holes 16 are arranged. All the outer ring spray holes 16 and the inner ring spray holes 17 are distributed in a curve, and the outer ring spray holes 16 and the inner ring spray holes 17 enclose a semi-surrounding shape with an opening facing the combustion channel 1.

[0022] On the side wall of the combustion channel 1, a flue gas circulation hole 14 is horizontally arranged, which connects the injection area of the secondary combustion tube burner 2 and the injection area of the primary burner hole 15. The flue gas circulation hole 14 is arranged close to the primary burner tube 4 and the secondary combustion tube burner 2. An igniter 6 is arranged inside the burner body. The igniter 6 is located on the angular bisector of two adjacent primary burner tubes 4, and the igniter 6 is connected to the bottom of the burner body through a flange. An automatic actuator for controlling the size of the damper 9 is arranged at the lower part of the burner body. The actuator is connected with a flue gas residual oxygen detector 10. The automatic actuator realizes the automatic adjustment of the flue inlet damper through the adjustment of receiving the flue gas residual oxygen detection signal. A flame detector access hole 8 is reserved at the bottom of the burner body. The flame detector is connected to the bottom of the burner body through a flange. An insulating layer 7 is arranged at the lower part of the burner body.

[0023] In this embodiment, the primary combustion tube 5 is communicated with the primary fuel gas main pipe 19 provided with a primary fuel gas control valve 18, and the secondary combustion tube 3 is communicated with the secondary fuel gas main pipe 20 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, it is beneficial to realize the stable combustion of the burner under different loads. In this embodiment, the secondary fuel gas main pipe 20 is in a ring shape, so as to facilitate the connection of all the secondary combustion tubes 3 with the secondary fuel gas main pipe 20.

[0024] The present invention conducts multi-point combustion through a plurality of primary burner holes 15 and a plurality of secondary combustion tube burner holes 2. And with the cooperation of the vertical ignition holes 11, the horizontal ignition holes 12 and the flue gas circulation hole 14, the flue gas internal circulation of the combustion channel 1 is realized, which can effectively control the oxygen concentration in the combustion process, reduce the combustion temperature, thereby realizing the reduction of the concentration of nitrogen oxides in the flue gas, and further realizing the stable low-nitrogen combustion of the heating furnace.

[0025] The above are only the embodiments of the present invention. Common general knowledge such as the specific structures and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent.

Claims

1. A low-nitrogen combustion device for a heating furnace, comprising a burner body. A combustion channel is arranged at the upper part of the burner body. An inner combustion tube and a pilot burner are arranged on the inner side of the combustion channel. A secondary combustion tube and a secondary combustion tube burner are arranged on the outer circumference of the combustion channel. The secondary combustion tube burner is provided with an inner ring spray hole and an outer ring spray hole. Characterized in that: An inner burner tube extending towards the inner wall of the combustion channel is arranged on the inner combustion tube. An inner combustion tube burner is arranged at one end of the inner burner tube close to the inner wall of the combustion channel. The inner combustion tube burner and the secondary combustion tube burner are located on the same horizontal plane; the inner combustion tube burner is provided with an inner burner hole facing the inner edge of the end of the combustion channel; the axial angle between the outer ring spray hole and the axis of the secondary combustion tube burner is b1, the axial angle between the inner ring spray hole and the axis of the secondary combustion tube burner is b2, and the angle between the conical outer wall of the combustion channel and the axis of the secondary combustion tube burner is c, and b2 > c > b1; a flue gas circulation hole communicating the spraying area of the secondary combustion tube burner and the spraying area of the inner burner hole is horizontally arranged on the side wall of the combustion channel.

2. The low-nitrogen combustion device for a heating furnace according to claim 1, Characterized in that: There are two inner ring spray holes, and there are at least three outer ring spray holes. All the outer ring spray holes and inner ring spray holes are distributed in a curve, and the outer ring spray holes and the inner ring spray holes enclose a semi-surrounding shape with an opening facing the combustion channel.

3. The low-nitrogen combustion device for a heating furnace according to claim 2, Characterized in that: A vertical ignition hole and a horizontal ignition hole are arranged at the top of the combustion channel. The vertical ignition hole and the horizontal ignition hole are communicated with each other. The axis of the inner burner hole intersects with the end of the horizontal ignition hole.

4. The low-nitrogen combustion device for a heating furnace according to claim 3, Characterized in that: The angle between the horizontal ignition hole and the cross-section of the combustion channel is between 5° and 60°, and the end of the horizontal ignition hole located outside the combustion channel is higher than the end located inside the combustion channel.

5. The low-nitrogen combustion device for a heating furnace according to claim 4, Characterized in that: The inner combustion tube is coaxially arranged with the combustion channel. There are at least four inner burner tubes, and all the multiple inner burner tubes are evenly distributed along the circumference of the inner combustion tube. The pilot burner is located on the angular bisector of two adjacent inner burner tubes.

6. The low-nitrogen combustion device for a heating furnace according to claim 5, Characterized in that: The angle between the axis of the inner burner hole and the vertical axis of the inner combustion tube is between 15° and 30°.

7. The low-nitrogen combustion device for a heating furnace according to claim 6, Characterized in that: An automatic actuator for controlling the size of the air inlet damper is arranged at the lower part of the burner body. The automatic actuator realizes the automatic adjustment of the flue gas inlet damper through the adjustment of receiving the flue gas residual oxygen detection signal.

8. The low-nitrogen combustion device for a heating furnace according to claim 7, Characterized in that: The primary combustion tube is connected to the burner body through limit bolts, and the primary combustion tube is communicated with a primary fuel gas main pipe provided with a primary fuel gas control valve; the secondary combustion tube is connected to the burner body through a flange, and the secondary combustion tube is communicated with a secondary fuel gas main pipe provided with a secondary fuel gas control valve.

9. A low-nitrogen combustion device for a heating furnace according to claim 8, characterized in that: A flame detector access hole is reserved at the bottom of the burner body, and the flame detector is connected to the bottom of the burner body through a flange.

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