Normal temperature air MILD burner and combustion method

Abstract

The present invention belongs to the technical field of industrial burners, and specifically discloses a normal temperature air MILD burner and a combustion method. The normal temperature air MILD burner includes a gas channel, a primary air channel and a secondary air channel. The gas channel includes a gas inlet shell, a gas pipeline and a gas nozzle connected in sequence. A swirl sheet is arranged on the periphery of the gas nozzle. The primary air channel includes a primary air shell and a primary air duct connected in sequence. The secondary air channel includes a secondary air shell and a secondary air duct connected in sequence. The normal temperature air MILD combustion method uses a MILD burner to establish MILD combustion. When performing primary air swirl combustion, only the primary air channel is used to introduce primary air. When the furnace temperature reaches the fuel auto-ignition temperature, the combustion mode is switched from flame swirl combustion to flameless MILD combustion by gradually closing the primary air and gradually opening the secondary air. The present invention has the advantages of easy disassembly and installation, wide application scenarios, simple combustion system and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial burners, and in particular relates to a normal temperature air MILD burner. Background Art

[0002] MILD combustion technology, or mild low-oxygen dilution combustion, is an emerging combustion technology of the 21st century. It utilizes distributed volumetric combustion in a low-oxygen, diluted atmosphere, resulting in uniform furnace temperature distribution, high combustion efficiency, and low nitrogen oxide emissions. Compared to traditional combustion, it significantly increases convective and radiative heat transfer, achieving both energy savings and emission reductions, with significant economic and social benefits.

[0003] Existing MILD burners generally require high-temperature preheating of combustion air. The combustion system has a complex structure, is difficult to disassemble, has high installation costs, and has a short material life in high-temperature environments, which greatly limits the application scenarios of MILD combustion. Summary of the Invention

[0004] In response to the above-mentioned problems, the purpose of the present invention is to provide a normal temperature air MILD burner and combustion method to realize the application scenarios of MILD combustion in multiple fields, improve the combustion efficiency in industrial production and reduce nitrogen oxide emissions.

[0005] The technical solution of the present invention is: a normal temperature air MILD burner, comprising: The gas channel comprises a gas inlet shell, a gas pipeline and a gas nozzle which are connected in sequence, and a swirl plate is provided on the periphery of the gas nozzle; The primary air channel comprises a primary air housing and a primary air duct which are connected in sequence. The primary air duct is sleeved around the gas pipeline and the gas nozzle. The primary air duct is used to guide the primary air to the gas nozzle. The primary air is formed into a swirl at the outlet of the primary air duct by the swirl vane. The gas inlet housing is provided with a gas inlet at one end away from the gas pipeline. The gas inlet is used to connect to an external gas source. The secondary air channel includes a secondary air shell and a secondary air duct connected in sequence. The secondary air duct is arranged on the periphery of the primary air duct. The secondary air duct is used to guide the secondary air to the gas nozzle. The secondary air is used to form a high-speed jet at the gas nozzle.

[0006] Furthermore, a flame observation channel, an igniter channel and a flame monitor channel are also provided inside the gas inlet shell. The flame observation channel is used to observe the flame near the gas nozzle, the igniter channel is used to place the igniter, and the igniter is used to ignite the gas nozzle. The flame monitor channel is used to place the flame monitor, and the flame monitor is used to monitor the flame at the gas nozzle.

[0007] Furthermore, the gas nozzle is provided with a plurality of nozzles arranged in a circumferential pattern, and the nozzles are used to eject the gas and form high-speed jets.

[0008] Furthermore, the periphery of the swirl plate is fixed on the inner wall of the primary air duct.

[0009] Furthermore, the swirl angle of the swirl plate is 65°-75°, and the thickness of the swirl plate is 10mm-15mm.

[0010] Furthermore, the secondary air duct includes a plurality of single tubes arranged circumferentially around the axis of the primary air duct.

[0011] Furthermore, there are 4 to 12 single tubes.

[0012] Furthermore, the air outlet speed of the single tube is 70m / s-90m / s.

[0013] A method for MILD combustion of air at room temperature, using the MILD burner to establish MILD combustion, specifically comprising the following steps: The primary air enters from the primary air shell, passes through the primary air duct, and is swirl-formed by the swirl vane at the primary air duct outlet; the gas enters from the gas inlet shell, passes through the gas pipeline, and is ejected from the gas nozzle; after ignition, high-speed swirl combustion is formed; When the temperature reaches the fuel auto-ignition temperature, secondary air is gradually introduced from the secondary air housing through the secondary air duct to the gas nozzle, and the air volume of the primary air is gradually reduced. During this process, the total air volume remains unchanged, and the combustion state transitions from high-speed swirl combustion to MILD combustion until stable MILD combustion is established.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention is assembled from multiple parts and has the advantages of being easy to disassemble and install, having a wide range of applicable scenarios, a simple combustion system and a low cost.

[0015] Moreover, the present invention can realize MILD combustion without preheating combustion air: it generates a swirl flame when using primary air for combustion, which can reduce the generation of nitrogen oxides in the furnace heating stage. When the furnace temperature reaches the fuel auto-ignition temperature, the combustion mode is switched from flame swirl combustion to flameless MILD combustion by gradually closing the primary air and gradually opening the secondary air. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a front view of the present invention; Figure 3 It is a structural schematic diagram of the secondary air duct of the present invention; Figure 4 It is a partial structural schematic diagram of the present invention.

[0017] Among them, 1-gas inlet, 2-gas inlet shell, 3-primary air shell, 4-primary air inlet, 5-secondary air inlet, 6-primary air duct, 7-secondary air shell, 8-mounting flange, 9-secondary air duct, 10-outer pipe sleeve, 11-gas pipeline, 12-swirl plate, 13-gas nozzle, 14-flame observation channel, 15-igniter channel, 16-flame monitor channel. DETAILED DESCRIPTION

[0018] The following is combined with Figure 1 To the attached Figure 4 , a detailed description of the specific embodiments of the present invention is provided. In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limiting the present invention.

[0019] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; and in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0020] It should be noted that the circuit connections involved in the present invention all adopt conventional circuit connection methods and do not involve any innovation.

[0021] Example like Figure 1 、 Figure 2 A normal temperature air MILD burner shown includes a gas channel, a primary air channel and a secondary air channel.

[0022] The gas channel comprises a sequentially connected gas inlet housing 2, gas pipeline 11, and gas nozzle 13. A swirl vane 12 is provided around the periphery of the gas nozzle 13. The primary air channel comprises a sequentially connected primary air housing 3 and primary air duct 6. The primary air duct 6 is sleeved around the periphery of the gas pipeline 11 and gas nozzle 13. The primary air duct 6 is used to direct the primary air to the gas nozzle 13. The primary air is swirl-formed by the swirl vane 12 at the outlet of the primary air duct 6. A gas inlet 1 is provided at the end of the gas inlet housing 2 away from the gas pipeline 11. The gas inlet 1 is connected to an external gas source.

[0023] The secondary air channel includes a secondary air shell 7 and a secondary air duct 9 which are connected in sequence. The secondary air duct 9 is arranged on the periphery of the primary air duct 6. The secondary air duct 9 is used to guide the secondary air to the gas nozzle 13. The secondary air is used to form a high-speed jet at the gas nozzle 13.

[0024] The primary air is guided by the primary air duct 6 to the vicinity of the gas nozzle 13, and forms a swirl near the gas nozzle 13. The secondary air is guided by the secondary air duct 9 to the vicinity of the gas nozzle 13, and forms a high-speed jet near the gas nozzle 13. In actual use, it first produces a swirl flame when using the primary air for combustion. When the furnace temperature reaches the auto-ignition temperature of the fuel, the combustion mode is switched from flame swirl combustion to flameless MILD combustion by gradually closing the primary air and gradually opening the secondary air.

[0025] Preferably, an outer layer pipe sleeve 10 is provided on the outer periphery of the secondary air duct 9 , and the outer layer pipe sleeve 10 is used to protect the secondary air duct 9 .

[0026] The normal temperature air MILD burner proposed in this embodiment is an assembled structure, wherein the gas inlet shell 2 is connected to the gas pipeline 11, the front end of the gas shell 2 is connected to the rear end of the primary air shell 3, the front end of the primary air shell 3 is connected to the rear end of the primary air duct 6 and the rear end of the secondary air shell 7 in sequence, the front end of the secondary air shell 7 is connected to the rear end of the secondary air duct 9 and the rear end of the outer pipe sleeve 10 in sequence, and finally the burner proposed in this embodiment is assembled.

[0027] The primary air housing 3 is provided with a primary air inlet 4 , the primary air housing 3 is coaxially arranged with the gas pipeline 11 , and the primary air housing 3 is connected with the primary air duct 6 to form a primary air channel.

[0028] The secondary air housing 7 defines a secondary air inlet 5 , the secondary air housing 7 is coaxially arranged with the primary air duct 6 and surrounds the primary air duct 6 , and the secondary air housing 7 is connected to the secondary air duct 9 to form a secondary air channel.

[0029] It also includes a mounting flange 8, which is arranged on the outer side wall of the secondary air housing 7. The mounting flange 8 is used to install the normal temperature air MILD on the furnace.

[0030] Preferably, Figure 4 As shown, a flame observation channel 14, an igniter channel 15 and a flame monitor channel 16 are also provided inside the gas inlet shell 2. The flame observation channel 14 is used to observe the flame near the gas nozzle 13. The igniter channel 15 is used to place the igniter, and the igniter is used to ignite the gas nozzle 13. The flame monitor channel 16 is used to place the flame monitor, and the flame monitor is used to monitor the flame at the gas nozzle 13.

[0031] Preferably, the gas nozzle 13 is provided with a plurality of nozzles arranged in a circumferential pattern, and the nozzles are used to eject gas and form high-speed jets. Since the aperture of the nozzles is small, when a certain flow of gas passes through the gas pipeline 11 and exits the gas nozzle 13, a high-speed jet is formed.

[0032] Preferably, the periphery of the swirl blade 12 is fixed on the inner wall of the primary air duct 6, so that when the primary air passes through the swirl blade 12 from the primary air duct 6, the swirl blade 12 is ensured to act on the entire primary air to form a swirl.

[0033] Preferably, the swirl angle of the swirl plate 12 is 65°-75°, and the thickness of the swirl plate 12 is 10 mm-15 mm.

[0034] Preferably, the secondary air duct 9 includes a plurality of single tubes arranged circumferentially around the axis of the primary air duct 6 .

[0035] Preferably, there are 4 to 12 tubes in a single tube. Figure 3 As shown, there are 12 single tubes in this embodiment.

[0036] Preferably, the air outlet speed of a single tube is 70m / s-90m / s, which can effectively draw in high-temperature flue gas, thereby reducing the oxygen content in the reaction zone and the maximum temperature in the combustion zone, and ultimately significantly reducing the production of nitrogen oxides.

[0037] A prerequisite for establishing MILD combustion is a high-temperature, low-oxygen combustion environment. This embodiment heats the furnace through primary swirl combustion. Once the furnace temperature rises above the fuel's auto-ignition temperature, high-speed secondary air jets entrain surrounding high-temperature flue gas, delaying the combustion reaction. The entrained high-temperature flue gas then fully dilutes the reactants, consisting of the fuel and combustion-supporting air. The reactant temperature rises until it reaches the fuel's auto-ignition temperature, leading to spontaneous combustion and the establishment of MILD combustion. Because the reactants are fully diluted by the flue gas during MILD combustion, their oxygen content is extremely low, lowering the maximum reaction temperature and effectively reducing the formation of nitrogen oxides.

[0038] A method for MILD combustion of air at room temperature, using a MILD burner to establish MILD combustion, specifically comprising the following steps: When performing primary air swirl combustion, only the primary air inlet 4 is opened, and the primary air enters from the primary air housing 3, passes through the primary air duct 6, and is formed into a swirl from the outlet of the primary air duct 6 by the swirl blades 12.

[0039] The gas enters the gas inlet shell 2 from the gas inlet 1, passes through the gas pipeline 11, and is ejected from the gas nozzle 13 to form a high-speed jet. The igniter automatically ignites and forms high-speed swirl combustion. During the primary air combustion process, the furnace temperature gradually increases. When the furnace temperature reaches the fuel auto-ignition temperature, the secondary air inlet 5 is gradually opened and the primary air inlet 4 is gradually closed. During this process, the total air volume remains unchanged, and the combustion state transitions from high-speed swirl combustion to MILD combustion until stable MILD combustion is established. When the temperature reaches the fuel auto-ignition temperature, the secondary air inlet 5 is opened, and the secondary air gradually enters the secondary air shell 7 from the secondary air inlet 5, passes through the secondary air duct 9, and forms a high-speed jet near the gas nozzle 13.

[0040] The flame state is monitored in real time through the flame observation channel 14 and the flame monitor. Once a fire is extinguished, the gas input is immediately shut off and the above operation is repeated to re-establish MILD combustion.

[0041] The specific models of the above electronic components are not particularly specified, and common products available on the market can be selected as long as they can meet the use requirements of the present invention.

[0042] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A normal temperature air MILD burner, characterized in that: include: A gas channel, comprising a gas inlet shell (2), a gas pipeline (11) and a gas nozzle (13) which are connected in sequence, wherein a swirl plate (12) is provided on the periphery of the gas nozzle (13); a gas inlet (1) is provided on one end of the gas inlet shell (2) away from the gas pipeline (11), and the gas inlet (1) is used to be connected to an external gas source; A primary air channel, comprising a primary air housing (3) and a primary air duct (6) which are connected in sequence, the primary air duct (6) being sleeved on the periphery of a gas pipeline (11) and a gas nozzle (13), the primary air duct (6) being used to guide the primary air to the gas nozzle (13), the primary air being formed into a swirl at the outlet of the primary air duct (6) by the action of a swirl blade (12); The secondary air channel comprises a secondary air housing (7) and a secondary air duct (9) which are connected in sequence. The secondary air duct (9) is sleeved on the periphery of the primary air duct (6). The secondary air duct (9) is used to guide the secondary air to the gas nozzle (13). The secondary air is used to form a high-speed jet at the gas nozzle (13).

2. A normal temperature air MILD burner as claimed in claim 1, characterized in that: The gas inlet housing (2) is also provided with a flame observation channel (14), an igniter channel (15) and a flame monitor channel (16); the flame observation channel (14) is used to observe the flame near the gas nozzle (13); the igniter channel (15) is used to place an igniter, which is used to ignite the gas nozzle (13); the flame monitor channel (16) is used to place a flame monitor, which is used to monitor the flame at the gas nozzle (13).

3. A normal temperature air MILD burner as claimed in claim 1, characterized in that: The gas nozzle (13) is provided with a plurality of nozzles arranged in a circumferential pattern, and the nozzles are used to spray out the gas and form high-speed jets.

4. A normal temperature air MILD burner as claimed in claim 1, characterized in that: The periphery of the swirl blade (12) is fixed on the inner wall of the primary air duct (6).

5. A normal temperature air MILD burner as claimed in claim 4, characterized in that: The swirl angle of the swirl sheet (12) is 65°-75°, and the thickness of the swirl sheet (12) is 10 mm-15 mm.

6. A normal temperature air MILD burner as claimed in claim 1, characterized in that: The secondary air duct (9) comprises a plurality of single tubes arranged in a circle around the axis of the primary air duct (6).

7. A normal temperature air MILD burner as claimed in claim 6, characterized in that: The number of the single tubes is 4 to 12.

8. A normal temperature air MILD burner as claimed in claim 6, characterized in that: The air outlet speed of the single tube is 70m / s-90m / s.

9. A normal temperature air MILD combustion method, characterized in that: Establishing MILD combustion using the MILD burner according to any one of claims 1 to 8 specifically comprises the following steps: The primary air enters from the primary air housing (3), passes through the primary air duct (6), and is subjected to the action of the swirl blade (12) at the outlet of the primary air duct (6) to form a swirl flow; the gas enters from the gas inlet housing (2), passes through the gas pipeline (11), and is ejected from the gas nozzle (13), and after ignition, forms a high-speed swirl combustion; When the temperature reaches the fuel auto-ignition temperature, secondary air is gradually introduced from the secondary air housing (7) through the secondary air duct (9) to the gas nozzle (13), and the air volume of the primary air is gradually reduced. During this process, the total air volume is kept unchanged, and the combustion state transitions from high-speed swirl combustion to MILD combustion until stable MILD combustion is established.

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