A multi-stage combustion low-nitrogen oxide radiant tube burner

Abstract

The application discloses a multistage combustion low nitrogen oxide radiation tube type burner. By arranging a burner inner cylinder, a flame stabilizer, combustion air blind channels, a burner inner and outer nozzle with a necking and a gas gun extending out of the nozzle, multistage dense and thin combustion is formed in the burner area and the whole combustion chamber, internal flue gas circulation is formed at the front end of a heat-resistant sleeve pipe downstream of the flue gas, low-temperature and low-oxygen flue gas is backflowed into the internal flue gas passage, and the high-temperature and high-oxygen flue gas / fuel gas is mixed, so that the oxygen content in the fuel combustion process is reduced, the combustion temperature is further reduced, and the NOx emission is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of gas combustion, in particular to a multi-stage combustion low nitrogen oxide radiation tube burner. BACKGROUND

[0002] With the increasing efforts of various industries for energy saving and emission reduction, the management of atmospheric pollutants, the NOx emission requirement of gas boiler has been reduced to 80mg / Nm 3 or more stringent standards.

[0003] The radiation tube burner uses the burner in the radiation tube to generate high-temperature flue gas, which radiates heat to the radiation tube, and the radiation tube radiates heat to the medium in the heating furnace. The high-temperature flue gas gradually exchanges heat and cools down in the radiation tube under the flow guiding effect of the silicon carbide tube, and then flows from the front end to the rear end of the radiation tube, and then returns from the periphery of the rear end to the outlet of the front end and flows out of the radiation tube.

[0004] At present, there are a large number of heating furnaces in the steel industry, and each heating furnace is equipped with dozens to hundreds of radiation tube burners. Other industries such as the food industry, industrial product baking paint, and the automobile industry also use radiation burners to dry objects or paint.

[0005] The heating furnace in the steel industry mainly uses industrial waste gas such as coke oven gas and natural gas as fuel. The industrial waste gas such as coke oven gas contains fuel compounds to some extent, and the NOx emission is higher than that of natural gas, which is about 300mg / Nm 3 , so the emission reduction potential in the steel industry is huge. Some owners need to start trying to reduce the nitrogen content of the radiation tube burner to reduce the low-nitrogen emission of NOx. The food industry, industrial product baking paint and other industries use natural gas as fuel for the radiation tube burner, and the emission is about 200mg / Nm 3 , so the pressure of the transformation is also huge. SUMMARY

[0006] The purpose of the present application is to provide a multi-stage combustion low nitrogen oxide radiation tube burner to reduce the emission of easily polluted nitrogen oxides.

[0007] To solve the above technical problems, the present application provides a multi-stage combustion low nitrogen oxide radiation tube burner, comprising:

[0008] A center tube, a burner throat, a burner outer throat and a radiation tube are arranged in a nested manner from inside to outside; the center tube is provided with a center gas gun; a first-stage combustion-supporting air passage is formed between the center gas gun and the burner throat, and the outer edge of the first-stage combustion-supporting air passage is a combustion-supporting air blind channel; a main gas gun is arranged between the center tube and the combustion-supporting air blind channel; a secondary combustion-supporting air passage is formed between the burner throat and the burner outer throat; a flue gas downstream heat-resistant sleeve gap is arranged downstream of the burner outer throat; and the radiation tube is arranged at the outermost periphery and surrounds the burner outer throat and the flue gas downstream heat-resistant sleeve.

[0009] Through the above arrangement, multi-stage dense and dilute combustion is formed in the burner area and the entire combustion chamber, and flue gas internal circulation is formed at the front end of the flue gas downstream heat-resistant sleeve, and multiple effects reduce the emission of NOx.

[0010] Optionally, the inner wall of the combustion-supporting air blind channel is a burner inner flame tube, the outer wall is a part of the burner throat, and the rear end of the burner inner flame tube is recessed.

[0011] Optionally, the rear end of the burner throat is recessed, and the rear end of the burner outer throat is recessed, so that the secondary combustion-supporting air passage is bent towards the central axis.

[0012] Optionally, the minimum diameter of the rear end of the burner outer throat is smaller than the diameter of the flue gas downstream heat-resistant sleeve.

[0013] Optionally, the rear end of the burner throat protrudes beyond the center gas gun and the main gas gun.

[0014] Optionally, the rear end of the burner outer throat and the flue gas downstream heat-resistant sleeve form a flue gas internal circulation suction port.

[0015] Optionally, the radiation tube has a radiation tube flue gas outlet between the front end of the burner outer throat and the radiation tube, the radiation tube is closed at one end of the flue gas downstream heat-resistant sleeve and is arranged in the gap of the flue gas downstream heat-resistant sleeve, combustion gas passes through the flue gas internal passage formed by the flue gas downstream heat-resistant sleeve, enters the flue gas external passage between the flue gas downstream heat-resistant sleeve and the radiation tube through the gap between the flue gas downstream heat-resistant sleeve and the radiation tube, and then part of the combustion gas enters the flue gas internal circulation suction port, and the other part of the combustion gas is discharged through the radiation tube flue gas outlet.

[0016] Optionally, a flame stabilizer is arranged between the center tube and the center gas gun.

[0017] Optionally, the main gas gun is provided with at least one layer, and each layer is arranged in a ring shape.

[0018] Optionally, the downstream flue gas heat-resistant sleeve comprises at least one, and each downstream flue gas heat-resistant sleeve is arranged in a radial direction in sequence.

[0019] The application provides a multi-stage combustion low nitrogen oxide radiation tube burner, wherein a burner inner cylinder, a flame stabilizer, a combustion air blind channel, a burner inner and outer throat with a necking and a gas gun extending out of the burner throat are arranged to form multi-stage dense and thin combustion in the burner area and the whole combustion chamber, form flue gas internal circulation at the front end of the downstream flue gas heat-resistant sleeve, make the low-temperature and low-oxygen flue gas backflow into the flue gas internal channel, mix with the high-temperature and high-oxygen flue gas / fuel gas, reduce the oxygen content in the fuel combustion process, and further reduce the combustion temperature and reduce the NOx emission. 3 The application has great significance for NOx emission reduction of the radiation tube burner. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Figure 1 is a schematic diagram of a multi-stage combustion low nitrogen oxide radiation tube burner according to an embodiment of the application. Figure 1 ;

[0021] Figure 2 Figure 2 is a schematic diagram of a multi-stage combustion low nitrogen oxide radiation tube burner according to another embodiment of the application. Figure 2 ;

[0022] Figure 3 Figure 3 is a schematic diagram of part of a multi-stage combustion low nitrogen oxide radiation tube burner according to an embodiment of the application.

[0023] Figure 4 Figure 4 is a schematic diagram of flue gas circulation according to an embodiment of the application.

[0024] In the figure: 1. center gas gun; 2. flame stabilizer; 3. center cylinder; 4. main gas gun; 5. primary combustion air channel; 6. burner inner flame cylinder; 61. necking at the rear end of the inner flame cylinder; 7. combustion air blind channel; 8. burner throat; 81. necking at the rear end of the burner throat; 9. secondary combustion air channel; 10. burner outer throat; 101. necking at the rear end of the burner outer throat; 11. downstream flue gas heat-resistant sleeve; 12. flue gas internal circulation suction port; 13. radiation tube; 14. flue gas internal channel; 15. flue gas external channel; 16. radiation tube flue gas outlet. DETAILED DESCRIPTION

[0025] The application will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

[0026] The application will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

[0027] In the following description, it will be understood that references to "inner" and "outer" with respect to structures can be made with reference to the drawings.

[0028] The application provides a multi-stage combustion low nitrogen oxide radiation tube burner, the embodiments described below by reference to the drawings are exemplary, only for the purpose of explaining the application, and can not be understood as limiting the application.

[0029] As shown in Figure 1 and Figure 2 , the multi-stage combustion low nitrogen oxide radiation tube burner comprises:

[0030] The center tube 3, the burner throat 8, the burner outer throat 10 and the radiation tube 13 are arranged in a nested manner from inside to outside; the center gas gun 1 is arranged in the center tube 3; the first-stage combustion-supporting air passage 5 is formed between the center gas gun 1 and the burner throat 8, and the outer edge of the first-stage combustion-supporting air passage 5 is the combustion-supporting air blind channel 7; the main gas gun 4 is arranged between the center tube 3 and the combustion-supporting air blind channel 7; the secondary combustion-supporting air passage 9 is formed between the burner throat 8 and the burner outer throat 10; the flue gas downstream heat-resistant sleeve 11 is arranged downstream of the burner outer throat 10; the radiation tube 13 is arranged at the outermost periphery and surrounds the burner outer throat 10 and the flue gas downstream heat-resistant sleeve 11. Through the above arrangement, multi-stage dense and dilute combustion is formed in the burner area and the entire combustion chamber, and internal circulation of flue gas is formed at the front end of the flue gas downstream heat-resistant sleeve 11, and multiple effects reduce the emission of NOx.

[0031] The main gas gun 4 is provided with at least one layer, and each layer is arranged in a ring shape. Each layer is arranged in a ring shape with the same radius and with the axis of the device as the center. Figure 1 The configuration of the main gas gun 4 as shown in

[0032] Further, the center tube 3 and the center gas gun 1 are provided with a flame stabilizer 2.

[0033] The center gas gun 1 is placed in the center of the burner, and a plurality of gas holes are arranged on the head of the center gas gun 1 as needed, and the center gas gun 1 extends out of the flame stabilizer 2.

[0034] The flame stabilizer 2 can be a shield flame stabilizer or a cyclone flame stabilizer, arranged between the center gas gun 1 and the center cylinder 3, and plays a role in stabilizing the flame of the burner.

[0035] The center cylinder 3 is placed at the outer end of the flame stabilizer 2 and is connected to the flame stabilizer 2.

[0036] The inner wall of the combustion air blind channel 7 is the burner inner flame cylinder 6, and the outer wall is part of the burner throat 8, and the rear end of the burner inner flame cylinder 6 is tapered inward. There is no air inlet in the area where the combustion air blind channel 7 is located, so that the state of hypoxic combustion (rich combustion) is maintained in the early stage of combustion.

[0037] Among them, the structure of the burner inner flame cylinder 6 can refer to Figure 3 .

[0038] The rear end of the burner throat 8 is tapered inward, and the rear end of the burner outer throat 10 is tapered inward, so that the secondary combustion air channel 9 is bent towards the central axis. The secondary air enters downstream from the flue gas / fuel gas stream, creating a general rich and lean combustion atmosphere in the combustion chamber.

[0039] Among them, the structure of the burner throat 8 and the burner outer throat 10 can refer to Figure 3 . It should be noted that the structures of the burner inner flame cylinder 6, the burner throat 8 and the burner outer throat 10 are similar, so they all adopt Figure 3 One view is shown, but it is not considered that the three components are the same structure, and there are differences in size among the three.

[0040] Further, the minimum diameter of the rear end taper 101 of the burner outer throat is smaller than the diameter of the flue gas downstream heat-resistant sleeve 11.

[0041] The rear end taper 81 of the burner throat 8 exceeds the center gas gun 1 and the main gas gun 4.

[0042] The rear end taper 101 of the burner outer throat 10 and the flue gas downstream heat-resistant sleeve 11 form a flue gas internal circulation suction port 12.

[0043] The downstream flue gas resistant sleeve 11 is placed downstream of the burner outer throat 10, and functions to guide the flame and flue gas flow, and to bear the high temperature radiation of the flame outward. The downstream flue gas resistant sleeve 11 is coaxial with the central axis of the device, and is arranged as needed. A plurality of downstream flue gas resistant sleeves 11 are arranged in the same diameter and sequentially arranged in the rear, forming a flue gas inner passage 14.

[0044] In one embodiment, the downstream flue gas resistant sleeve 11 can be a silicon carbide sleeve.

[0045] Please refer to Figure 4 The radiation tube 13 and the front end of the burner outer throat 101 have a radiation tube flue gas outlet 16. The radiation tube 13 is closed at one end of the downstream flue gas resistant sleeve 11 and is arranged with a gap between the downstream flue gas resistant sleeve 11. After the combustion gas passes through the flue gas inner passage 14 formed by the downstream flue gas resistant sleeve 11, it enters the flue gas outer passage 15 between the downstream flue gas resistant sleeve 11 and the radiation tube 13. Then, a part enters the flue gas inner circulation inlet 12, and the other part is discharged from the radiation tube flue gas outlet 16.

[0046] The downstream flue gas resistant sleeve 11 is placed downstream of the burner outer throat 10, and the radiation tube 13 is arranged at the outermost periphery.

[0047] When the device is working, a part of combustion air enters the first combustion air channel 5, the rest of combustion air enters the second combustion air channel 9, a small part of fuel enters the burner from the center gas gun 1, and the rest of fuel enters the burner from the main gas gun 4. The combustion air entering the first combustion air channel 5, under the guide of the center cylinder 3, a small amount of combustion air enters the flame holder 2, and the center gas gun 4 sprays the center gas, which has a rich combustion with an excess air ratio less than 0.5, to generate a small flame, reduce the emission of NOx, and the flame holder 2 plays a role in combustion and flame stabilization for the center gas, which enhances the flame stabilization performance of the burner. The rest of combustion air entering the first combustion air channel 5 is sprayed obliquely to the center of the burner at high speed from the channel between the center cylinder 3 and the rear end of the flame cylinder 6 before the neck 61, and meets the main gas sprayed from the main gas gun 4, which is ignited by the small flame to generate a main flame. The combustion air sprayed obliquely to the center of the burner at high speed avoids the combustion air being directly sprayed to the root of the flame generated by the main gas combustion, strengthens the effect of rich and lean combustion, and reduces the emission of NOx; no combustion air enters the combustion air blind channel 7, the unburned fuel and combustion air are gradually sucked and mixed, continue to have a lack of oxygen rich combustion and reduction reaction, reduce the emission of NOx, and make the fuel further burn to generate high-temperature flue gas / fuel air mixture; the mixture flows to the downstream of the combustion chamber, meets the rest of combustion air needed for combustion sprayed from the second combustion air channel 9, and the subsequent combustion has a lean combustion to burn the unburned fuel and upstream intermediates, which ensures the complete combustion of fuel. Although there is a large amount of combustion air in the lean combustion stage, the temperature of the flue gas is reduced by the external radiation of the radiation pipe and the heat absorption of the external cold source medium, so there is no large amount of NOx generated in the lean combustion stage, which reduces the emission of NOx. Therefore, the radiation pipe type burner makes the fuel complete multi-stage rich and lean combustion in the combustion chamber, and finally makes the amount of NOx generated by combustion low.

[0048] The minimum diameter of the rear end neck 101 of the burner outer throat is smaller than the diameter of the flue gas downstream heat-resistant sleeve 11; the flame and high-temperature flue gas generated by combustion flow forward in the flue gas inner channel 14 along the axial direction, and the temperature of the high-temperature flue gas gradually decreases. When the flue gas reaches the end of the radiation pipe 13, it flows back from the flue gas outer channel 15, and the temperature of the flue gas gradually decreases due to the external radiation of the radiation pipe 13 to heat the external cold source medium. The low-temperature flue gas finally flows out from the radiation pipe flue gas outlet 16 and is finally discharged to the atmosphere. When the backflowing flue gas passes through the flue gas inner circulation suction port 12 at the end of the burner outer throat 10, part of the low-temperature and low-oxygen flue gas is sucked back by the negative pressure formed by the high-speed flame and flue gas inside the burner sleeve, achieving the effect of flue gas inner circulation. The extracted low-temperature and low-oxygen flue gas participates in the combustion process, reduces the oxygen concentration of combustion, further inhibits the generation of nitrogen oxides, and achieves the effect of low-nitrogen combustion.

[0049] The radiant tube burner has made a great breakthrough in the low-nitrogen transformation of heating furnaces and industrial product heating in the steel industry, helps the environmental protection, and has a very large market prospect in the subsequent low-nitrogen transformation of the steel industry.

[0050] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A multi-stage combustion low-NOx radiant tube burner, characterized in that, include: The central tube, burner throat (8), burner outer throat and radiant tube are nested from the inside out; A central gas gun is provided in the central cylinder; a primary combustion air passage (5) is formed between the central gas gun and the burner throat, and the outer edge of the primary combustion air passage is a combustion air blind passage; a main gas gun is provided between the central cylinder (3) and the combustion air blind passage; a secondary combustion air passage is formed between the burner throat and the burner outer throat. The downstream heat-resistant sleeve gap is located downstream of the burner's outer throat; the radiant tube is arranged on the outermost periphery, surrounding the burner's outer throat and the downstream heat-resistant sleeve. The inner wall of the combustion air blind channel is the inner flame tube of the burner, and the outer wall is part of the throat of the burner. The rear end of the inner flame tube of the burner is narrowed inward. The rear end of the burner throat is narrowed and inward, and the rear end of the burner outer throat is narrowed and inward, causing the secondary combustion air passage to bend toward the central axis. The rear end of the burner throat extends beyond the central gas gun and the main gas gun; During operation, the residual combustion air entering from the primary combustion air channel is ejected at high speed at an angle from the channel before the rear end contraction of the central cylinder and the flame tube inside the burner. When it encounters the main combustion gas ejected from the main combustion gun, the main combustion gas is ignited by a small flame to generate the main flame.

2. The multi-stage combustion low-NOx radiant tube burner as described in claim 1, characterized in that, The minimum diameter of the rear end of the burner's external throat is smaller than the diameter of the downstream heat-resistant sleeve of the flue gas.

3. A multi-stage combustion low-NOx radiant tube burner as described in claim 1, characterized in that, The rear end of the burner's external throat and the downstream heat-resistant sleeve of the flue gas form a flue gas internal circulation intake port.

4. A multi-stage combustion low-NOx radiant tube burner as described in claim 3, characterized in that, The radiant tube has a radiant tube flue gas outlet between its front end and the burner's external throat. One end of the radiant tube is closed and gapped between it and the downstream heat-resistant sleeve. After the combustion gas passes through the internal flue gas channel formed by the downstream heat-resistant sleeve, it enters the external flue gas channel between the downstream heat-resistant sleeve and the radiant tube through the gap between them. Then, a portion of the gas enters the internal flue gas recirculation inlet, and the other portion is discharged from the radiant tube flue gas outlet.

5. A multi-stage combustion low-NOx radiant tube burner as described in claim 1, characterized in that, A flame stabilizer is provided between the central cylinder and the central gas gun.

6. A multi-stage combustion low-NOx radiant tube burner as described in claim 1, characterized in that, The main gas gun is provided in at least one layer, with each layer arranged in a ring.

7. A multi-stage combustion low-NOx radiant tube burner as described in claim 1, characterized in that, The downstream heat-resistant sleeve for flue gas includes at least one, and each of the downstream heat-resistant sleeves for flue gas is arranged radially in sequence.

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