An apparatus and method for incineration of gas in the presence of a low concentration of oxygen-containing combustion aid

Abstract

The present application relates to a kind of incineration device and method for gas under low concentration oxygen content combustion-supporting agent, including strong swirl burner, special combustion chamber;Strong swirl burner is annular structure, for providing the wall-attached rotating mixed jet of swirl intensity not less than 1, from inside to outside respectively for first stage gas lance, first stage air pipe, second stage gas lance, second stage air pipe and shell;Special combustion chamber is cylindrical furnace, for forming the high-temperature backflow flue gas filled in the center area of special combustion chamber, and the special combustion chamber entrance is docked with the outlet of strong swirl burner.Wall-attached rotating mixed jet is mixed and heated by high-temperature backflow flue gas, reaches reaction temperature, flows along the inner wall surface of special combustion chamber and reacts and releases heat, when reaches the outlet of special combustion chamber, a part of backflow is formed closed loop as the pilot light source of strong swirl burner, realizes the stable incineration of gas under low concentration oxygen content combustion-supporting agent, reaches the effect of reducing combustion temperature and reducing thermal NOx.

Description

Technical Field

[0001] This invention belongs to the field of low-oxygen-concentration process gas combustion technology, and relates to an apparatus and method for combustion of fuel gas under a low-oxygen-content combustion aid. Background Technology

[0002] In chemical production processes, a large amount of process gases with low oxygen concentrations containing trace amounts of harmful substances need to be incinerated, with oxygen concentrations ranging from approximately 10% to 13%v. Traditional thermal decomposition (incineration) methods are generally divided into four types: direct combustion (TO), regenerative thermal oxidizer (RTO), catalytic combustion (CO), and regenerative catalytic combustion (RCO). These are simply different combinations of combustion and heat exchange methods. None of these methods directly use the process gas as a combustion aid; instead, additional fresh air is required to form the initial heat source, resulting in energy waste.

[0003] The main reason is that the combustion stability of the fuel gas decreases as the oxygen content in the combustion accelerator decreases. Current technology can improve combustion stability by preheating the combustion accelerator; the lower the oxygen concentration, the higher the required preheating temperature. For example, if the oxygen content is 11%v, preheating to above 600℃ is required. This method has certain requirements on the composition of the process gas; it is not suitable if the process gas contains gases with low ignition points or wide explosion limits. Furthermore, this method has high requirements for the upstream processes and cannot achieve the goals of energy saving and investment reduction.

[0004] In their paper "A novel method to improve stability of MILD combustion in a highly heat-extracted furnace", Feifei Wang et al. from Huazhong University of Science and Technology proposed using a furnace body with an internal reflux wall to achieve stable combustion of fuel gas under a low-concentration oxygen-content combustion aid. However, this method is not suitable for large-scale industrial production, as the furnace body with an internal wall is difficult to implement in practice and is too costly. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a combustion device and method for gas under a low-concentration oxygen-content combustion aid, using process gas with an oxygen concentration of 11-13%v as the combustion aid to achieve a large-scale hot flue gas recirculation in the furnace, thereby achieving stable combustion, reducing combustion temperature and reducing thermal NOx.

[0006] The solution of the present invention is: a combustion device for gas under a low-concentration oxygen-containing combustion aid, comprising a strong swirl burner and a special-shaped combustion chamber;

[0007] The high-intensity swirl burner has an annular gap structure and is used to provide a wall-mounted rotating mixing jet with a swirl intensity of not less than a preset threshold. The high-intensity swirl burner consists of a first-stage gas injection gun, a first-stage air duct, a second-stage gas injection gun, a second-stage air duct, and a shell from the inside out.

[0008] The special-type combustion chamber is a cylindrical furnace, used to form high-temperature reflux flue gas filling the central area of ​​the special-type combustion chamber. The inlet of the special-type combustion chamber is connected to the outlet of the strong swirl burner.

[0009] The wall-mounted rotating mixing jet is heated by the high-temperature recirculated flue gas to reach the reaction temperature. It flows along the inner wall of the special combustion chamber and reacts to release heat. When it reaches the outlet of the special combustion chamber, part of the recirculation serves as the ignition heat source for the strong swirl burner, forming a closed loop. This enables stable combustion of the gas under a low-concentration oxygen-containing combustion aid, ultimately forming the outlet flue gas flow.

[0010] Furthermore, the primary gas nozzle is installed inside the primary air duct via a flange. The primary gas nozzle adopts a dual-channel design, including gas channel A and gas channel B. Gas channel A is located inside the cavity of gas channel B.

[0011] The gas passage B has a first-stage gas nozzle B at its end, and a first-stage swirl vane on the end sidewall of the gas passage B; the gas passage A has a first-stage gas nozzle A at its end, and is connected to a conical blunt body.

[0012] Furthermore, the conical blunt body is formed by casting refractory and includes an upper inner conical surface and a lower outer conical surface. The inner conical surface is used to guide air or premixed low-oxygen process gas to flow towards the furnace wall, and the outer conical surface is used to guide the high-temperature reflux flue gas to mix with the low-oxygen process gas.

[0013] The angle between the inner and outer conical surfaces is 90° to 120°. The maximum diameter of the conical blunt body is not greater than the outer diameter of the first-stage swirl blade, and the maximum diameter is flush with the shell outlet.

[0014] Furthermore, the secondary gas spray gun is installed below the primary air duct via a flange, and is located inside the secondary air duct and outside the primary gas spray gun.

[0015] The secondary gas spray gun includes a gas jacket, with secondary swirl vanes on the end sidewall of the gas jacket, and a secondary gas spray hole at the end of the gas jacket, with the secondary gas spray hole facing outward.

[0016] Furthermore, the housing is equipped with a lining and an igniter, and the secondary air duct is installed on the housing via a flange;

[0017] The shell lining forms a central channel and an expansion outlet from top to bottom. The end of the secondary air duct is inserted into the central channel, and the expansion outlet is connected to the inlet of the special combustion chamber. The expansion angle of the expansion outlet is 120° to 150°.

[0018] Furthermore, the gap between the primary gas nozzle, the secondary gas nozzle, and the primary air duct forms a primary vortex air duct. The primary vortex air duct is located at the primary vortex blades. The vortex intensity of the jet is greater than 1, which is called primary vortex.

[0019] Furthermore, the gap between the secondary gas nozzle, the secondary air duct, and the central channel of the casing forms a secondary vortex air duct. The outlet of the air duct is a secondary vortex blade, which generates a jet with the same vortex direction as the primary vortex blade and an intensity no less than that of the primary vortex.

[0020] Furthermore, the interface between the special-type combustion chamber and the strong swirl burner forms a guide fire basin, the depth l of which is 0.4 to 0.6 times the diameter Di of the guide fire basin; the guide fire basin is divided into a straight section and an expansion section, each occupying 1 / 2 of the fire basin depth, and the angle α of the expansion section is not less than 60°.

[0021] The inner diameter D of the special-type combustion chamber is 2.5 to 4 times the diameter Di of the guide fire basin, and the height L of the special-type combustion chamber section is 1 to 1.2 times the inner diameter D.

[0022] The special-type combustion chamber outlet is constricted, with an outlet diameter Do not greater than 0.5 times the inner diameter D, and a contraction angle γ of 90° to 120°.

[0023] Furthermore, the special-type combustion chamber has a lining, and the side of the top of the lining closest to the strong swirl burner is called the combustion chamber front wall, with the angle β of the combustion chamber front wall ranging from 150° to 180°.

[0024] Furthermore, a method for combustion of fuel gas in a low-oxygen-content combustion-supporting agent is proposed, comprising the following steps:

[0025] When the strong swirl burner is in start-up condition, most of the air is introduced into the primary swirl duct, and all the gas is introduced into the gas passage A of the primary gas nozzle. After being throttled and ejected through the primary gas nozzle A, it forms a jet. The gas passage B and the primary gas nozzle B are not working. The air introduced into the primary swirl duct mixes with the gas jet, and after being ignited by the igniter, it burns stably and gradually heats up to reach the operating condition requirements. At this time, a small amount of air is introduced into the secondary swirl duct to keep the gas passage A cool.

[0026] When the strong swirl burner is in start-up condition, the gas passage B and the first-stage gas nozzle B are not working. Most of the air is introduced into the first-stage swirl duct, and all the gas is introduced into the gas passage A of the first-stage gas nozzle. The gas is throttled out through the first-stage gas nozzle A to form a jet, which ignites the igniter to make the air and gas jet burn stably and gradually rise in temperature to meet the operating conditions. At this time, a small amount of air is introduced into the second-stage swirl duct to keep the gas passage A cool.

[0027] The low-oxygen process gas rotating jet, after being guided by the conical surface of the conical blunt body, then expands through the expansion section of the guide basin, where the shape abruptly changes, losing wall constraint and expanding to form a wall-attached rotating mixing jet moving downstream. A negative pressure area is formed in the center of the special-shaped combustion chamber, causing the downstream high-temperature flue gas to flow back. After being guided by the outer conical surface, it mixes with the wall-attached rotating mixing jet. After being heated by the high-temperature backflow flue gas, the wall-attached rotating mixing jet reaches the reaction temperature, flows along the inner wall of the special-shaped combustion chamber and reacts and releases heat. When it reaches the outlet of the special-shaped combustion chamber, part of it flows out of the special-shaped combustion chamber, and part of it flows back as the ignition heat source for the strong swirl burner, realizing the design closed loop.

[0028] The advantages of this invention compared to the prior art are:

[0029] (1) The present invention adopts strong swirling premixing, blunt body guiding and special proportional size of furnace body structure to realize large-scale hot flue gas recirculation in the furnace body, and uses the recirculated flue gas to ignite the low oxygen concentration process gas of premixed gas, so as to achieve stable combustion, reduce combustion temperature and reduce thermal NOx.

[0030] (2) The strong swirl burner of the present invention has an annular gap structure, which provides a premixed jet with sufficient swirl intensity. The special combustion chamber can form a large-scale high-temperature recirculation. The two work together to achieve stable combustion of the gas under low-concentration oxygen content combustion aid. At the same time, due to the low oxygen content, no obvious high-temperature zone will be generated, and thus the thermal NOx will be greatly reduced. Attached Figure Description

[0031] Figure 1 This is an assembly and schematic diagram of the incineration device described in an embodiment of the present invention;

[0032] Figure 2 This is a structural diagram of the high-swirl burner according to an embodiment of the present invention;

[0033] Figure 3 This is a structural diagram of the first-stage gas spray gun according to an embodiment of the present invention;

[0034] Figure 4 This is a structural diagram of the two-stage gas spray gun according to an embodiment of the present invention;

[0035] Figure 5 This is a structural diagram of the shell and lining of a high-swirl burner according to an embodiment of the present invention;

[0036] Figure 6 This is a structural diagram of the dimensions of a special combustion chamber according to an embodiment of the present invention.

[0037] Among them: 1. Strong swirl burner, 2. Special type combustion chamber, 3. Wall-mounted rotating mixing jet, 4. High-temperature flue gas recirculation, 5. Outlet flue gas flow;

[0038] 11 Primary gas spray gun, 12 Primary air duct, 13 Secondary gas spray gun, 14 Secondary air duct, 15 Housing, 16 Lining, 17 Igniter, 18 Secondary swirl duct, 19 Primary swirl duct;

[0039] 111 Gas passage A, 112 Gas passage B, 113 First-stage swirl vane, 114 First-stage gas nozzle B, 115 First-stage gas nozzle A, 116 Conical blunt body, 117 Blunt outer conical surface, 118 Blunt inner conical surface;

[0040] 131 Gas jacket, 132 Secondary swirl vane, 133 Secondary gas nozzle;

[0041] 151 Central passage, 152 Expanded exit;

[0042] 21. Guide fire basin, 211. Straight section, 212. Expansion section, 22. Combustion chamber front wall, 23. Special type combustion chamber outlet. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] Example 1

[0045] like Figure 1 As shown, the present invention proposes a combustion device for gas under a low-concentration oxygen-content combustion aid, which includes a strong swirl burner 1 and a special-shaped combustion chamber 2.

[0046] The high-intensity swirl burner 1 is an annular gap structure, used to provide a wall-mounted rotating mixing jet 3 with a swirl intensity of not less than 1, such as... Figure 2 As shown, the strong swirl burner 1 consists of a primary gas spray gun 11, a primary air duct 12, a secondary gas spray gun 13, a secondary air duct 14, and a housing 15 from the inside out; the housing 15 is equipped with a lining 16, an igniter 17, a flame detector, and a sight glass, etc.

[0047] The special-type combustion chamber 2 is a cylindrical furnace used to form high-temperature reflux flue gas 4 that fills the central area of ​​the special-type combustion chamber 2. The inlet of the special-type combustion chamber 2 is connected to the outlet of the strong swirl burner 1.

[0048] The wall-mounted rotating mixing jet 3 is mixed and heated by the high-temperature reflux flue gas 4 to reach the reaction temperature. It flows along the inner wall of the special combustion chamber 2 and reacts and releases heat. When it reaches the outlet 23 of the special combustion chamber, a portion of the reflux serves as the ignition heat source for the strong swirl burner 1 to form a closed loop, achieving stable combustion of the gas under a low-concentration oxygen-containing combustion aid, and finally forming the outlet flue gas flow 5.

[0049] like Figure 3As shown, the primary gas spray gun 11 adopts a dual-channel design, including gas channel A111 and gas channel B112. Gas channel A111 is located inside the cavity of gas channel B112. The primary gas spray gun 11 is installed in the primary air duct 12 through a flange.

[0050] The gas passage B112 has a primary gas nozzle B114 at its end, and a primary swirl vane 113 on its end sidewall. The gas passage A111 has a primary gas nozzle A115 at its end, and is connected to a conical blunt body 116. In this embodiment, from top to bottom, the components are a primary swirl vane 113, a primary gas nozzle B114, a primary gas nozzle A115, and a conical blunt body 116.

[0051] like Figure 3 As shown, the conical blunt body 116 is formed by casting refractory, including an upper inner conical surface 118 and a lower outer conical surface 118. The inner conical surface 118 is used to guide air or premixed low-oxygen process gas to flow towards the furnace wall, and the outer conical surface 117 is used to guide the high-temperature reflux flue gas 4 to mix with the low-oxygen process gas.

[0052] In this embodiment, the inner conical surface 118 and the outer conical surface 118 have an angle of approximately 90°. The maximum diameter of the conical blunt body 116 is slightly smaller than the outer diameter of the first-stage swirl blade 113, and the maximum diameter is flush with the outlet of the shell 15.

[0053] like Figure 4 As shown, the secondary gas spray gun 13 adopts a jacket design and is installed below the primary air duct 12 through a flange, while located inside the secondary air duct 14 and outside the primary gas spray gun 11.

[0054] The secondary gas spray gun 13 includes a gas jacket 131, a secondary swirl vane 132 is provided on the end sidewall of the gas jacket 131, and a secondary gas spray hole 133 is provided at the end of the gas jacket 131, with the secondary gas spray hole 133 facing outward. In this embodiment, from top to bottom, the secondary swirl vane 132 and the secondary gas spray hole 133 are arranged in sequence.

[0055] The secondary air duct 14 is installed on the housing 15 via a flange.

[0056] like Figure 5 As shown, the inner lining 16 of the shell 15 forms a central channel 151 and an expansion outlet 152 from top to bottom. The diameter of the central channel 151 is similar to the diameter of the secondary air duct 14. The end of the secondary air duct 14 is inserted into the central channel 151. The expansion outlet 152 is connected to the inlet of the special combustion chamber 2. The expansion angle of the expansion outlet 152 is 120° to 150°.

[0057] like Figure 2As shown, the gap between the primary gas spray gun 11, the secondary gas spray gun 13, and the primary air duct 12 forms a primary swirl duct 19. The primary swirl duct 19 is located at the position of the primary swirl blade 113. The swirl intensity of the jet is greater than 1, which is called primary swirl.

[0058] The gap between the secondary gas spray gun 13, the secondary air duct 14, and the central channel 151 of the housing 15 forms a secondary swirl air duct 18. The outlet of the air duct is the secondary swirl blade 132, which generates a jet with the same swirl direction as the primary swirl blade 113 and an intensity not less than that of the primary swirl.

[0059] The special-type combustion chamber 2 consists of a second shell, a second lining, and other accessories (such as thermocouples, pressure gauges, sight glasses, etc.), and its structural dimensions have specific requirements for forming a large-scale recirculation.

[0060] like Figure 6 As shown, the interface between the special-shaped combustion chamber 2 and the strong swirl burner 1 forms a guide fire basin 21. In this embodiment, the depth l of the guide fire basin 21 is about 0.5 times the diameter Di of the guide fire basin 21. The guide fire basin 21 is divided into a straight section 211 and an expansion section 212, which occupy 1 / 2 of the depth of the fire basin 21 respectively. The angle α of the expansion section 212 is not less than 60°.

[0061] The side of the second lining of the special-type combustion chamber 2 that is close to the strong swirl burner 1 is called the combustion chamber front wall 22. The angle β of the combustion chamber front wall 22 can be rotated from 150° to 180°, and a larger value should be taken as much as possible.

[0062] The inner diameter D of the special-type combustion chamber 2 is about 3 times the diameter Di of the guide fire basin 21, and the height L of the cylindrical section of the special-type combustion chamber 2 is about 1 to 1.2 times the inner diameter D.

[0063] The special combustion chamber outlet 23 is constricted, with an outlet diameter Do approximately 0.5 times the inner diameter D and a contraction angle γ approximately 90°.

[0064] The device described in this invention enables stable combustion of fuel gas under a low-concentration oxygen-containing combustion aid. The specific operating method is as follows:

[0065] The high-intensity swirl burner 1 has two operating states: start-up and operation. In start-up, air-assisted combustion is used, while in operation, low-oxygen process gas is used. Start-up is a prerequisite for operation. The high-intensity swirl burner 1 and the special-type combustion chamber 2 need to react with the combustion air and fuel gas. Only after the special-type hot combustion chamber 2 reaches a certain temperature and forms a stable, large-scale reflux can it switch to operation—changing the combustion air to low-oxygen process gas as the combustion aid. This temperature depends on the fuel's combustion characteristics and is generally around 1100℃ (referencing relevant requirements in standard GB 18484). A higher furnace temperature helps prevent flame fluctuations during the switching process.

[0066] During startup, the primary gas nozzle 11 and the primary swirl duct 19 operate. The dual-channel design of the primary gas nozzle 11 is designed to handle startup and operation conditions respectively. The load distribution of the two channels is matched with the design flow rates of the primary swirl duct 19 and the secondary swirl duct 18 so that the jet intensity of the primary gas nozzles A115 and B114 meets the mixing requirements with the primary swirl air.

[0067] In this embodiment, under the design conditions of identical heat load and identical fuel composition and flow rate for both start-up and operation conditions, the oxygen content of the combustion-supporting agent differs significantly between the two conditions (the oxygen content of the fresh air used in the start-up condition is 21%v, while the oxygen content of the low-oxygen process gas used in the operation condition is 11%v, and the combustion-supporting agent flow rate ratio is approximately the reciprocal of the oxygen content). To ensure the designed flow rate of the channel, the specific conditions for the two conditions are as follows:

[0068] During startup, most of the air is introduced into the primary swirl duct 19, and all the gas is introduced into the gas passage A111 of the primary gas nozzle 11. The gas is throttled and ejected through the primary gas nozzle A115 to form a jet. The gas passage B112 and the primary gas nozzle B114 are not working. The air introduced into the primary swirl duct 19 mixes with the gas jet and is ignited by the igniter 17. The gas then burns stably and gradually heats up to meet the operating conditions. At this time, a small amount of air is introduced into the secondary swirl duct 18 to keep the gas passage A111 cool.

[0069] Under operating conditions, the air is switched to low-oxygen process gas, the flow rate of the combustion-supporting agent increases, and the primary swirl duct 19 and the secondary swirl duct 18 work simultaneously, introducing low-oxygen process gas; part of the gas passes through the gas passage B112 of the primary gas spray gun 11 and is throttled and ejected through the primary gas spray hole B114 to form a jet, which cooperates with the rotating jet of the primary swirl duct 19; the remaining gas passes through the secondary gas spray gun 13 and is throttled and ejected through the secondary gas spray hole 133 to form a jet, which cooperates with the rotating jet of the secondary swirl duct 18; the rotating jets generated by the primary swirl duct 19 and the secondary swirl duct 18 have the same swirl direction, and the designed flow velocities are comparable with a difference of 1 to 2 m / s.

[0070] The low-oxygen process gas rotating jet, after being guided by the inner conical surface 118 of the conical blunt body 116 of the strong swirl burner 1, then rapidly expands after the abrupt change in the expansion section 212 of the guide basin 21, losing wall constraint, forming a wall-attached rotating mixing jet 3 that moves downstream. The central part of the special-shaped combustion chamber 2, lacking sufficient airflow to fill, forms a negative pressure zone, causing the downstream high-temperature flue gas to recirculate. This recirculated gas then mixes with the wall-attached rotating mixing jet 3 after being guided by the outer conical surface 117. Heated by the high-temperature recirculated flue gas 4, the wall-attached rotating mixing jet 3 reaches its reaction temperature, flows along the inner wall of the special-shaped combustion chamber 2, and reacts exothermically. Upon reaching the outlet 23 of the special-shaped combustion chamber, part flows out of the chamber, and part recirculates as the ignition heat source for the strong swirl burner 1, achieving a closed-loop design. Simultaneously, due to the low oxygen content during combustion, no significant high-temperature zone is generated, thus significantly reducing thermal NOx.

[0071] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A combustion apparatus for fuel gas in a low-concentration oxygen-enriched combustion-supporting agent, wherein the oxygen concentration of the combustion-supporting agent is lower than the oxygen concentration of air, characterized in that, Includes a strong swirl burner (1) and a special-type combustion chamber (2); The strong swirl burner (1) has an annular gap structure and is used to provide a wall-mounted rotating mixed jet (3) with a swirl intensity not less than a preset threshold. The strong swirl burner (1) consists of a first-stage gas spray gun (11), a first-stage air duct (12), a second-stage gas spray gun (13), a second-stage air duct (14), and a shell (15) from the inside to the outside. The special-type combustion chamber (2) is a cylindrical furnace used to form high-temperature reflux flue gas (4) filling the central area of ​​the special-type combustion chamber (2). The inlet of the special-type combustion chamber (2) is connected to the outlet of the strong swirl burner (1). The wall-mounted rotating mixing jet (3) is mixed and heated by the high-temperature reflux flue gas (4) to reach the reaction temperature. It flows along the inner wall of the special combustion chamber (2) and reacts and releases heat. When it reaches the outlet (23) of the special combustion chamber, a portion of the reflux serves as the ignition heat source for the strong swirl burner (1) to form a closed loop, thereby achieving stable combustion of the gas under a low-concentration oxygen content combustion aid, and finally forming the outlet flue gas flow (5). The first-stage gas nozzle (11) is installed in the first-stage air duct (12) through a flange. The first-stage gas nozzle (11) adopts a dual-channel design, including gas channel A (111) and gas channel B (112). Gas channel A (111) is set inside the cavity of gas channel B (112). The gas passage B (112) is provided with a first-stage gas nozzle B (114) at the end, and a first-stage swirl vane (113) is provided on the end side wall of the gas passage B (112); the gas passage A (111) is provided with a first-stage gas nozzle A (115) at the end, and is connected to a conical blunt body (116). The conical blunt body (116) is formed by casting and includes an upper inner conical surface (118) and a lower outer conical surface (117). The inner conical surface (118) is used to guide air or premixed low-oxygen process gas to flow to the furnace wall, and the outer conical surface (117) is used to guide the high-temperature return flue gas (4) to mix with the low-oxygen process gas. The inner conical surface (118) and the outer conical surface (117) have an angle of 90° to 120°. The maximum diameter of the conical blunt body (116) is not greater than the outer diameter of the first-stage swirl blade (113), and the maximum diameter is flush with the outlet of the shell (15).

2. The combustion device for fuel gas under a low-concentration oxygen-containing combustion-supporting agent according to claim 1, characterized in that, The secondary gas spray gun (13) is installed below the primary air duct (12) via a flange, and is located inside the secondary air duct (14) and outside the primary gas spray gun (11); The secondary gas spray gun (13) includes a gas jacket (131), a secondary swirl vane (132) is provided on the end side wall of the gas jacket (131), and a secondary gas spray hole (133) is provided at the end of the gas jacket (131), with the secondary gas spray hole (133) facing outward.

3. The combustion device for fuel gas under a low-concentration oxygen-containing combustion-supporting agent according to claim 2, characterized in that, The housing (15) is provided with a lining (16) and an igniter (17), and the secondary air duct (14) is installed on the housing (15) through a flange; The inner lining (16) of the shell (15) forms a central channel (151) and an expansion outlet (152) from top to bottom. The end of the secondary air duct (14) is inserted into the central channel (151). The expansion outlet (152) is connected to the inlet of the special combustion chamber (2). The expansion angle of the expansion outlet (152) is 120° to 150°.

4. The combustion device for fuel gas under a low-concentration oxygen-containing combustion-supporting agent according to claim 3, characterized in that, The gap between the primary gas nozzle (11), the secondary gas nozzle (13), and the primary air duct (12) forms a primary swirl duct (19). The primary swirl duct (19) is located at the position of the primary swirl blade (113). The swirl intensity of the jet is greater than 1, which is called primary swirl.

5. The combustion device for fuel gas under a low-concentration oxygen-containing combustion-supporting agent according to claim 4, characterized in that, The gap between the secondary gas nozzle (13), the secondary air duct (14), and the central channel (151) of the housing (15) forms a secondary swirl air duct (18). The outlet of the air duct is a secondary swirl blade (132). The direction of the jet is the same as that of the primary swirl blade (113), and the intensity is not less than that of the primary swirl.

6. The combustion device for fuel gas in a low-concentration oxygen-containing combustion-supporting agent according to claim 5, characterized in that, The interface between the special combustion chamber (2) and the strong swirl burner (1) forms a guide fire basin (21), the depth l of the guide fire basin (21) is 0.4 to 0.6 times the diameter Di of the guide fire basin (21); the guide fire basin (21) is divided into a straight section (211) and an expansion section (212), which occupy 1 / 2 of the depth of the fire basin (21), and the angle α of the expansion section (212) is not less than 60°; The inner diameter D of the special combustion chamber (2) is 2.5 to 4 times the diameter Di of the guide fire basin (21), and the height L of the cylindrical section of the special combustion chamber (2) is 1 to 1.2 times the inner diameter D. The outlet (23) of the special combustion chamber is constricted, and the outlet diameter Do is not greater than 0.5 times the inner diameter D. The constriction angle γ is 90° to 120°.

7. The combustion device for fuel gas in a low-concentration oxygen-containing combustion-supporting agent according to claim 6, characterized in that, The special combustion chamber (2) has a lining, and the side of the top of the lining that is close to the strong swirl burner (1) is called the combustion chamber front wall (22). The angle β of the combustion chamber front wall (22) is 150° to 180°.

8. A method for combustion of fuel gas in a low-concentration oxygen-containing combustion-supporting agent based on the apparatus of claim 7, characterized in that, The process includes the following steps: When the strong swirl burner (1) is in start-up condition, the gas passage B (112) and the first-stage gas nozzle B (114) are not working. Most of the air is introduced into the first-stage swirl duct (19), and all the gas is introduced into the gas passage A (111) of the first-stage gas nozzle (11). The gas is throttled and ejected through the first-stage gas nozzle A (115) to form a jet. The igniter (17) is ignited to make the air and gas jet burn stably and gradually rise in temperature to meet the operating conditions. At this time, a small amount of air is introduced into the second-stage swirl duct (18) to keep the gas passage A (111) cool. When the strong swirl burner (1) is in operation, the primary swirl duct (19) and the secondary swirl duct (18) work simultaneously, and low-oxygen process gas is introduced; part of the gas passes through the gas passage B (112) of the primary gas nozzle (11) and is throttled and ejected through the primary gas nozzle B (114) to form a jet, which cooperates with the rotating jet of the primary swirl duct (19); the remaining gas passes through the secondary gas nozzle (13) and is throttled and ejected through the secondary gas nozzle (133) to form a jet, which cooperates with the rotating jet of the secondary swirl duct (18). The low-oxygen process gas rotating jet, after passing through the expansion section (212) of the guide fire basin (21), loses the wall constraint and expands, forming a wall-attached rotating mixing jet (3) that moves downstream. A negative pressure area is formed in the center of the special combustion chamber (2), causing the downstream high-temperature flue gas to flow back and mix with the wall-attached rotating mixing jet (3). After being heated by the high-temperature reflux flue gas (4), the wall-mounted rotating mixing jet (3) reaches the reaction temperature, flows along the inner wall of the special combustion chamber (2) and reacts to release heat. When it reaches the outlet (23) of the special combustion chamber, part of it flows out of the special combustion chamber (2) and part of it flows back as the ignition heat source of the strong swirl burner (1), thus realizing the design closed loop.

Images