Snail-shaped element combustor ignition and combustion stabilizing device and ignition method

Abstract

The application discloses a snail-shaped element combustor ignition and stable combustion device and method, which comprises an inlet structure, a combustor shell, a wall surface necking concentration weir, an arc-shaped expansion channel, an outlet structure and an ignition device; the inlet structure is connected to one side of the bottom of the combustor shell, and the outlet structure is connected to the other side of the bottom of the combustor shell; the arc-shaped expansion channel and the wall surface necking concentration weir are arranged on the inner wall of the combustor shell, the arc-shaped expansion channel is located on the side where the outlet structure is arranged, and the arc-shaped expansion channel is a cold pulverized coal gas flow outlet channel, receives a high-speed primary air flow and mixed high-temperature flue gas flow, gradually expands along the circular shell, continuously receives radiation and mixed heating of a flame center in the expansion flow process, and is ignited stably; the wall surface necking concentration weir is located on the side where the inlet structure is arranged, the wall surface necking concentration weir concentrates un-gasified hot coke powder in high-temperature gas, and sends the un-gasified hot coke powder to a primary air nozzle outlet, so that the concentration and heat of the coal coke powder at an ignition position are increased; and the ignition device is arranged at the outlet of a primary air flow deformation channel or the primary air nozzle outlet.

Description

Technical Field

[0001] This invention belongs to the field of combustion technology, specifically relating to a snail-shaped element burner ignition and stabilization device and method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In the field of existing pulverized coal boilers and their burners, pulverized coal burners are mainly classified into two types: direct-flow pulverized coal burners and swirl pulverized coal burners. The combustion organization and ignition / stabilization of existing pulverized coal boilers are inseparable, both igniting at the burner outlet within the furnace and then burning within the furnace (except for industrial pulverized coal combustion devices). Existing swirl burners rely on recirculation heat as the ignition heat source, and recirculation heat is one of the core issues in swirl burner stabilization technology. Existing direct-flow burners with a tangential combustion method rely on the upstream rotating flame merging with primary air as the ignition source. The temperature and mixing rate of the recirculation heat flame are the core issues for stable combustion. The difficulty in controlling the recirculation heat and the upstream flame supply has become a constraint on the ignition and stabilization of existing pulverized coal boilers and their burners! Especially when the boiler is operating at low load, the furnace flame temperature or recirculation flow rate decreases, making stable ignition even more difficult.

[0004] Modern pulverized coal burners are essentially injectors that mix air and pulverized coal. They rely on the flame inside the furnace to supply ignition heat, working together to achieve ignition and combustion. Under low loads, the furnace temperature is low, recirculation and heat recovery are weakened, ignition conditions deteriorate, and may even fail to meet the requirements. Stable ignition and combustion are crucial for boiler operation at low loads and for ensuring complete combustion. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a snail-shaped burner ignition and stabilization device and method. This device truly achieves combustion within the burner, decoupling it from combustion within the pulverized coal boiler and is unaffected by the boiler's combustion conditions or load. The snail-shaped burner ignition and stabilization device and method ignites the pulverized coal before feeding it into the boiler. This advances the physical space and reaction timing of combustion, enabling boilers operating at low loads to maintain stable high-temperature combustion, thus achieving stable operation of coal-fired boilers at ultra-low loads (below 20% of rated load).

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a snail-shaped element burner ignition and stabilization device, comprising a primary air inlet structure, a burner shell, a wall-constricted concentration weir, an arc-shaped expansion channel, an outlet structure, and an ignition device;

[0008] The inlet structure is connected to one side of the bottom of the burner housing, and the outlet structure is connected to the other side of the bottom of the burner housing;

[0009] An arc-shaped expansion channel and a wall-constriction concentration weir are provided on the inner wall of the burner shell. The arc-shaped expansion channel is located on the side where the outlet structure is located. It is the outlet channel for cold pulverized coal gas. It receives high-speed primary air flow and mixed high-temperature flue gas flow. It gradually expands along the circular shell. During the expansion flow process, it continuously receives radiation and mixed heating from the flame center until stable ignition.

[0010] The wall-constriction thickening weir is located on the side of the inlet structure. It concentrates the ungasified hot coke powder in the high-temperature gas and sends it to the primary air nozzle outlet to increase the coal and coke powder concentration and heat at the ignition point.

[0011] The ignition device is located at the outlet of the primary airflow deformation channel and / or the outlet of the primary air nozzle.

[0012] As a further technical solution, when the ignition device is an oil gun ignition device or a natural gas ignition device, it is installed above the arc-shaped expansion channel.

[0013] As a further technical solution, when the ignition device is a plasma ignition device, it is installed below the wall constriction concentration weir and above the primary air nozzle.

[0014] As a further technical solution, the burner shell is circular, elliptical, or volute-shaped. The cold pulverized coal gas flow entering from the inlet structure has sufficient mixing conditions with the high-temperature combustion gas flow to obtain ignition heat and reach the ignition temperature. The circular shell forms a high-temperature combustion flame vortex that pushes the flame to the primary air outlet. The high-temperature flame part mixes with the primary air, and the mixing process generates ignition heat to ignite the primary air and pulverized coal. The high-temperature flame part flows out of the volute-shaped burner through the outlet structure and enters the next device, such as a boiler.

[0015] As a further technical solution, the concentration outlet of the wall-constricted concentration weir is located above the primary air nozzle.

[0016] As a further technical solution, the inlet structure consists of a vertical rectangular nozzle and a circular-to-square section.

[0017] As a further technical solution, the snail-shaped burner stabilizing device is ignited outside the furnace and inside the burner, and then sent into the furnace for further combustion.

[0018] As a further technical solution, the arc-shaped expansion channel is formed by an arc-shaped baffle set on the inner wall of the burner shell, and the distance between the two arc-shaped baffles gradually increases, forming a funnel-shaped distribution.

[0019] As a further technical solution, the wall-constriction enrichment weir is formed by an arc-shaped baffle set on the inner wall of the burner shell, and the distance between the two arc-shaped baffles gradually decreases, forming an inverted trumpet shape.

[0020] Secondly, the present invention also provides an ignition and stabilization method for a snail-shaped burner ignition and stabilization device, as follows:

[0021] Cold pulverized coal enters from the inlet structure, and the oil gun ignition device or natural gas ignition device is set above the primary air expansion channel to ignite the primary air pulverized coal until a stable high-temperature flame is formed in the center of the snail-shaped element burner. Alternatively, cold pulverized coal enters from the inlet structure, and the plasma ignition device is set below the wall narrowing concentration weir outlet and above the primary air nozzle. The plasma heats the pulverized coal particles until the pulverized coal burns and a stable high-temperature flame is formed in the center of the snail-shaped element burner.

[0022] The cold pulverized coal airflow interacts with the high-temperature flame airflow after ignition. The high-speed primary air nozzle creates a suction force to draw in the high-temperature flame and heat the primary air pulverized coal airflow through mixing. The stable high-temperature flame rotating airflow at the center of the snail-shaped burner transfers heat to the cold pulverized coal airflow through radiation heat transfer and mixing heat exchange.

[0023] The high-temperature flame gas flow after combustion fills the central area through rotation, maintaining a continuous high temperature in the center. Due to the low coal powder concentration in the central area, its combustion is relatively more complete, and the temperature is higher than that of the surrounding areas. The high-temperature flame in the center is a stable ignition source after the igniter stops. This gas flow continuously outputs or transports heat to the cold coal powder gas flow, and is constantly replenished from the ignition gas flow.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. This invention utilizes a constricted concentration weir on the wall of a snail-shaped burner ignition and stabilization device to concentrate pulverized coke at a certain temperature from both sides to the center, mixing it with a cold airflow. A high-speed airflow from the primary air nozzle creates a suction force, drawing in the high-temperature airflow. An arc-shaped expansion channel continuously absorbs radiated and mixed heat from the central high-temperature airflow until it reaches the expansion channel outlet. This structure and the resulting flow heat exchange pattern ensure that the pulverized coal airflow easily obtains ignition heat, achieves stable ignition, and is highly adaptable to different coal types. Furthermore, the low wall temperature and high flow velocity prevent slag accumulation on the wall surface.

[0026] 2. Regarding the combustion of pulverized coal, the pulverized coal particles have already undergone partial gasification and pyrolysis coking within the ignition and stabilization device of the snail-shaped burner. After being injected into the boiler, they are easy to burn and burn completely, resulting in high combustion efficiency. The invention also creates a localized strong reducing atmosphere within the boiler, which is conducive to the reduction of NOx to N2, thus achieving the low NOx emission requirements for coal-fired boilers operating at ultra-low loads.

[0027] 3. The snail-shaped element burner ignition and stabilization device of this invention, when used in conjunction with various boiler furnaces, forms a completely new combustion mode and a new combustion organization form, adapting to high-efficiency, low-NOx combustion and other requirements. During low-load boiler operation, it allows secondary combustion in the furnace, ensuring rapid and complete combustion, advancing the reaction time of combustion in the boiler, and making the physical space of combustion more concentrated. This enables stable operation of coal-fired boilers at ultra-low loads (below 20% of rated load).

[0028] 4. In the snail-shaped element burner ignition and stabilization device of the present invention, the entire airflow presents a swirling state. At the center of the swirling flow, the oxygen content is relatively abundant and the temperature is high, making it easy to ignite and resulting in good semi-gasification effect. Corresponding to different air / pulverized coal fuel ratios, the snail-shaped element burner can be used for semi-gasification, gasification, and complete combustion. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a schematic diagram of the axial structure of the snail-shaped burner ignition and stabilization device in Example 1.

[0031] Figure 2 This is a schematic diagram of the ignition and stabilization device for the snail-shaped burner in Example 1.

[0032] Figure 3 This is a schematic diagram of the main structure of the snail-shaped burner ignition and stabilization device in Example 1.

[0033] The components include: 1. Inlet structure; 2. Burner shell; 3. Wall constriction enrichment weir; 4. Arc-shaped expansion channel; 5. Outlet structure; and 6. Ignition device. Detailed Implementation

[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] To distinguish it from existing burners where combustion occurs only at the outlet, the snail-shaped element burner of this invention ignites and burns internally before being discharged, hence the name snail-shaped element burner.

[0037] Example 1

[0038] like Figure 1 As shown, this embodiment discloses a snail-shaped element burner ignition and stabilization device, including an inlet structure 1, a burner shell 2, a wall narrowing concentration weir 3, an arc-shaped expansion channel 4, an outlet structure 5, and an ignition device 6;

[0039] The inlet structure 1 is connected to the burner housing 2. The inlet structure 1 consists of a rectangular nozzle and a circular-to-square section, serving as a primary air nozzle. Figure 1 As shown, the inlet structure 1 is located on the left side of the bottom of the burner shell 2. It serves as the inlet for primary air (i.e., cold pulverized coal airflow). It is generally narrowed, which can form a high-speed jet. By drawing in high-temperature airflow, it enhances the mixing and heat exchange of the high-temperature and low-temperature airflows.

[0040] The burner shell 2 is a circular, near-circular, or snail-shaped shell. The primary air flow at the inlet has sufficient mixing conditions with the high-temperature combustion (gasification) air flow to obtain ignition heat and reach the ignition temperature. The circular shell forms a high-temperature combustion flame vortex that pushes the flame to the primary air outlet (i.e., the outlet structure). The high-temperature flame part mixes with the primary air, and the mixing process generates ignition heat to ignite the primary air pulverized coal. The high-temperature flame part flows out of the snail-shaped burner through the outlet and enters the next device, such as a boiler.

[0041] The wall-narrowing concentration weir 3 is located at the rear of the burner shell 2 and above the primary air nozzle outlet. The purpose of setting the wall-narrowing concentration weir 3 is to concentrate the ungassed hot coke powder in the high-temperature gas and send it to the primary air nozzle outlet to increase the coal and coke powder concentration and heat at the ignition point. Specifically, in this embodiment, the wall-narrowing concentration weir 3 is formed by adding two baffles to the inner wall of the burner shell 2. The two baffles are arc-shaped baffles. One arc-shaped baffle is close to the front side of the burner shell 2, and the other arc-shaped baffle is close to the rear side of the burner shell 2. Along the flow direction of the hot coke powder, the distance between the two arc-shaped baffles decreases from large to small, and they are distributed in an inverted funnel shape, thereby forming the wall-narrowing concentration weir 3.

[0042] Furthermore, the arc-shaped expansion channel 4 is a cold pulverized coal gas outlet channel, which receives the high-speed primary airflow and mixed high-temperature flue gas flow from the inlet structure 1. It gradually expands along the circular shell. During the expansion flow process, it continuously receives radiation and mixed heating from the flame center until stable ignition.

[0043] Specifically, in this embodiment, the arc-shaped expansion channel 4 can be arranged in an irregular shape (such as a dovetail shape or a toothed shape) to enhance the mixing of the cold and hot airflows and coordinate the flow of the two airflows; the arc-shaped expansion channel 4 can be a semi-open partition or a louver-like partition. In this embodiment, for example... Figure 1 , Figure 2 , Figure 3 As shown, an arc-shaped expansion channel 4 is formed by adding two baffles to the inner wall of the burner housing 2. The two baffles are arc-shaped, with one arc-shaped baffle close to the front side of the burner housing 2 and the other arc-shaped baffle close to the rear side of the burner housing 2. The distance between the two arc-shaped baffles gradually increases, forming a funnel-shaped distribution, thus forming the arc-shaped expansion channel 4.

[0044] The outlet structure 5 is connected to the burner housing 2, and flows out of the snail-shaped element burner from one or both sides of the primary air channel (i.e., the front section of the arc-shaped expansion channel). The outlet flame gas composition of the snail-shaped element burner stabilizing device is generally, but not limited to, incomplete combustion, such as the semi-gasification combustion state of primary air pulverized coal, or the complete combustion state. Specifically, such as... Figure 1 As shown, the outlet structure 5 is installed on the bottom right side of the burner housing 2, opposite to the inlet structure 1 in front.

[0045] Furthermore, the outlet structure 5 comprises two sections: one section is a rectangular nozzle, and the other section is a circular tube with a gradually decreasing diameter; and the cross-sectional area of ​​the outlet structure 5 is larger than the cross-sectional area of ​​the inlet structure 1.

[0046] Furthermore, the ignition device 6 in this embodiment can be configured in two ways: an oil (natural gas) gun ignition device and a plasma ignition device; the specific installation location is as follows: Figure 1 As shown, the oil (natural gas) gun ignition device is installed at the outlet of the primary air flow deformation channel (i.e., the arc-shaped expansion channel 4); the plasma ignition device is installed at the outlet of the primary air nozzle (i.e., the inlet structure 1). It should be noted that in actual use, only one of the two ignition devices needs to be selected, and it is not necessary to set both ignition devices at the same time.

[0047] The aforementioned snail-shaped element burner stabilization device is ignited outside the furnace and inside the burner, and then sent into the furnace for further combustion after ignition; the aforementioned snail-shaped element burner stabilization device has, but is not limited to, a high-speed jet suction effect to obtain ignition heat and achieve ignition.

[0048] The ignition mechanism of the snail-shaped burner ignition and stabilization device is as follows: the cold pulverized coal gas flow and the high-temperature flame gas flow after ignition are interactive. The high-temperature flame heats the cold pulverized coal gas flow to the ignition point through radiation heat transfer and mixing. After ignition, the flame spreads radially from the center outward until the entire gas flow is burned.

[0049] The high-temperature flame stream after combustion is partially mixed with the cold pulverized coal stream, and part of it is sent to the boiler through the outlet to continue combustion.

[0050] The snail-shaped burner ignition and stabilization device has a stable high-temperature flame rotating at low speed in the center. This airflow continuously outputs or transports heat to the cold pulverized coal airflow, and is constantly replenished from the ignition airflow.

[0051] The snail-shaped burner oil gun ignition device is located at the outlet of the primary air flow expansion channel. It uses the primary air flow as the combustion-supporting flow and is not suitable for other air flows, such as secondary air.

[0052] The snail-shaped burner plasma ignition device is located above the primary air nozzle, where the coal / coke powder concentration is high and the plasma ignition efficiency is high.

[0053] The snail-shaped element burner is ignited outside the furnace and inside the burner, and then sent into the furnace for further combustion.

[0054] This invention utilizes a constricted concentration weir on the wall of a snail-shaped burner ignition and stabilization device to concentrate pulverized coke at a certain temperature from both sides to the center, mixing it with a cold airflow. The high-speed airflow from the primary air nozzle creates a suction force, drawing in the high-temperature airflow. The arc-shaped expansion channel continuously absorbs the radiation and mixing heat from the central high-temperature airflow until it reaches the outlet of the expansion channel. The above structure and the resulting flow heat exchange pattern make it easy for the pulverized coal airflow to obtain ignition heat, ensuring stable ignition and strong adaptability to different coal types. The wall temperature is low, the flow velocity is high, and slag accumulation on the wall is not easy.

[0055] In this invention, the coal powder is partially gasified within the ignition and stabilization device of the snail-shaped burner, and the coal powder particles have already undergone pyrolysis and coking. After being injected into the boiler, it is easy to burn and burn completely, resulting in high combustion efficiency. The invention also creates a localized strong reducing atmosphere within the boiler, which is conducive to the reduction of NOx to N2, thus achieving the low NOx emission requirements for coal-fired boilers operating at ultra-low loads.

[0056] The snail-shaped element burner ignition and stabilization device of this invention, when used in conjunction with various boiler furnaces, forms a completely new combustion mode and a novel combustion organization form, adapting to high-efficiency, low-NOx combustion and other requirements. During low-load boiler operation, it enables secondary combustion in the furnace, ensuring rapid and complete combustion, advancing the combustion reaction time in the boiler, and concentrating the physical space of combustion. This allows for stable operation of coal-fired boilers at ultra-low loads (below 20% of rated load).

[0057] In the snail-shaped element burner ignition and stabilization device of the present invention, the entire airflow presents a swirling state. At the center of the swirling flow, the oxygen content is relatively abundant and the temperature is high, making it easy to ignite and resulting in good semi-gasification. Corresponding to different air / pulverized coal fuel ratios, the snail-shaped element burner can be used for semi-gasification, gasification, and complete combustion.

[0058] Example 2

[0059] Based on the snail-shaped burner in Example 1, this example discloses an ignition and stable combustion method.

[0060] The ignition mechanism of the snail-shaped element burner ignition and stabilization device involves the following steps: The oil gun (natural gas) ignition device 6-1 is positioned above the arc-shaped expansion channel, igniting the primary air and pulverized coal until a stable high-temperature flame forms at the center of the snail-shaped element burner. The plasma ignition device 6-2 is positioned below the enrichment weir outlet and above the primary air nozzle. The plasma heats the pulverized coal particles until they burn, forming a stable high-temperature flame at the center of the snail-shaped element burner. No other combustion-supporting gases are used during the entire ignition process; only the primary air flow is required.

[0061] The ignition mechanism of the snail-shaped burner ignition and stabilization device is as follows: The cold pulverized coal airflow and the high-temperature flame airflow after ignition are interactive. The high-speed nozzle of the primary air forms a suction force, which absorbs the high-temperature flame and heats the primary air pulverized coal airflow through mixing. The stable high-temperature flame rotating airflow at the center of the snail-shaped burner transfers ignition heat to the cold pulverized coal airflow through radiation heat transfer and mixing heat exchange.

[0062] The ignition mechanism of the snail-shaped burner ignition and stabilization device is stable combustion: the high-temperature flame gas flow after combustion fills the central area through rotation, maintaining a continuous high temperature in the center; due to the low coal powder concentration in the central area, its combustion is relatively more complete, and the temperature is higher than that of the surrounding area; the high-temperature flame in the center is a stable ignition source after the igniter stops, and this gas flow continuously outputs or transports heat to the cold coal powder gas flow, and is constantly replenished from the ignition gas flow.

[0063] Finally, it should be noted that relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A snail-shaped element burner ignition and stabilization device, characterized in that: This includes the inlet structure, burner shell, wall constriction enrichment weir, arc-shaped expansion channel, outlet structure, and ignition device; The inlet structure is connected to one side of the bottom of the burner housing, and the outlet structure is connected to the other side of the bottom of the burner housing; An arc-shaped expansion channel and a wall-constriction concentration weir are provided on the inner wall of the burner shell. The arc-shaped expansion channel is located on the side where the outlet structure is located. It is the outlet channel for cold pulverized coal gas. It receives high-speed primary air flow and mixed high-temperature flue gas flow. It gradually expands along the burner shell. During the expansion flow process, it continuously receives radiation and mixing heating from the flame center until stable ignition. The wall-constriction thickening weir is located on the side of the inlet structure. It concentrates the ungasified hot coke powder in the high-temperature gas and sends it to the primary air nozzle outlet to increase the coal and coke powder concentration and heat at the ignition point. The ignition device is located above the outlet of the arc-shaped expansion channel or above the outlet of the inlet structure; The snail-shaped burner stabilizing device is ignited outside the furnace and inside the burner, and then sent into the furnace for further combustion after ignition; The arc-shaped expansion channel is formed by arc-shaped baffles set on the inner wall of the burner shell. The distance between the two arc-shaped baffles gradually increases, forming a funnel shape. The wall-constriction enrichment weir is formed by arc-shaped baffles set on the inner wall of the burner shell. The distance between the two arc-shaped baffles gradually decreases, forming an inverted trumpet shape.

2. The snail-shaped burner ignition and stabilization device as described in claim 1, characterized in that: When the ignition device is an oil gun ignition device or a natural gas ignition device, it is installed at the outlet position of the arc-shaped expansion channel.

3. The ignition and combustion stabilization device for the snail-shaped burner as described in claim 1, characterized in that: When the ignition device is a plasma ignition device, it is installed below the wall constriction concentration weir and above the outlet of the inlet structure.

4. The ignition and combustion stabilization device for the snail-shaped burner as described in claim 1, characterized in that: The burner casing is circular, elliptical, or volute-shaped.

5. The ignition and combustion stabilization device for the snail-shaped burner as described in claim 1, characterized in that: The concentration outlet of the wall-constricted concentration weir is located above the outlet of the inlet structure.

6. The ignition and combustion stabilization device for the snail-shaped burner as described in claim 1, characterized in that: The inlet structure consists of a vertical rectangular nozzle and a circular-to-square section.

7. The ignition and stabilization method of the snail-shaped burner ignition and stabilization device as described in any one of claims 1-6, characterized in that: Cold pulverized coal enters from the inlet structure, and the oil gun ignition device or natural gas ignition device is set above the arc-shaped expansion channel to ignite the primary air pulverized coal until a stable high-temperature flame is formed in the center of the snail-shaped element burner. Alternatively, cold pulverized coal enters from the inlet structure, and the plasma ignition device is set below the outlet of the wall narrowing concentration weir and above the inlet structure. The plasma heats the pulverized coal particles until the pulverized coal burns and a stable high-temperature flame is formed in the center of the snail-shaped element burner. The cold pulverized coal airflow interacts with the high-temperature flame airflow after ignition. The high-speed primary air nozzle creates a suction force to draw in the high-temperature flame and heat the primary air pulverized coal airflow through mixing. The stable high-temperature flame rotating airflow at the center of the snail-shaped burner transfers heat to the cold pulverized coal airflow through radiation heat transfer and mixing heat exchange. The high-temperature flame gas flow after combustion fills the central area through rotation, maintaining a continuous high temperature in the center. Due to the low coal powder concentration in the central area, its combustion is relatively more complete, and the temperature is higher than that of the surrounding areas. The high-temperature flame in the center is a stable ignition source after the igniter stops. This gas flow continuously outputs or transports heat to the cold coal powder gas flow, and is constantly replenished from the ignition gas flow.

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