A burner system and method suitable for iron powder

Abstract

The application discloses a burner system and method suitable for iron powder, which comprises a premixing cavity, a precombustion zone, a main combustion zone, a burnout zone and a flue gas distribution system in sequence along the flue gas flow direction. A same direction swirl field is formed by tangential wind of the side wall of the premixing cavity to strengthen the premixing of the iron powder and air. A high-energy igniter and a reverse jet nozzle are arranged in the precombustion zone to introduce high-temperature flue gas to form a backflow zone, thereby assisting the ignition of the iron powder and stabilizing the flame. Weak swirl wind and wall-attached wind are alternately arranged in the main combustion zone, and a micro-bulge structure is matched, so that the iron powder is prevented from being attached to the wall and slagging and full combustion is promoted. The burnout zone adopts a gradually expanding conical structure and is supplemented by burnout wind, so that the iron powder particles are completely burned out. The flue gas distribution system adopts a double-flow direction design of a main path and a circulating path, the distribution ratio is regulated by an electromagnetic flow valve, flue gas in the main path enters a boiler furnace for heat exchange, and flue gas in the circulating path is backflowed to the precombustion zone after being separated by a cyclone, so that energy cascade utilization and stable combustion are realized.

Description

Technical Field

[0001] This invention belongs to the field of combustion equipment technology, specifically relating to a burner system and method suitable for iron powder. Background Technology

[0002] Iron powder, as a potential zero-carbon energy carrier, boasts advantages such as high volumetric energy density, low production and usage costs, and abundant reserves. Its combustion products can be reduced by green energy sources like hydrogen, enabling the cyclical storage and utilization of energy, thus offering broad application prospects. However, the physicochemical properties of iron powder differ significantly from traditional fossil fuels (such as pulverized coal and natural gas): First, iron powder has a much higher density than pulverized coal, making it prone to settling and agglomeration in airflow, leading to difficulties in transportation and uneven gas-solid mixing; second, iron powder has a high ignition temperature, making it difficult to ignite using conventional ignition methods, and exhibiting poor flame stability; third, the high density and hardness of iron powder particles easily cause erosion and wear on the burner wall under high-speed flow, and molten iron oxide easily adheres to the wall and slags, affecting the safe and stable operation of the system. Existing pulverized coal burners or natural gas burners are ill-suited to the aforementioned characteristics of iron powder, and direct application can lead to problems such as ignition difficulties, low combustion efficiency, severe slag formation, and rapid equipment wear. Therefore, there is an urgent need to develop a burner system and method suitable for iron powder fuel, to solve the technical problems of ignition, stable combustion, burnout and safe operation, and to promote the large-scale application of iron powder clean energy. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a burner system and method suitable for iron powder. Through structural design and process optimization, it achieves uniform mixing of iron powder and air, stable ignition and efficient combustion of iron powder, while preventing slagging and erosion wear on the burner wall. It also balances low nitrogen emissions and efficient energy utilization, providing technical support for the industrial application of iron powder as a zero-carbon energy carrier.

[0004] To achieve the above objectives, the present invention is applicable to a burner system for iron powder, comprising a premixing chamber, a pre-combustion zone, a main combustion zone, a burnout zone, and a burner outlet connected sequentially along the flue gas flow direction: The upstream end of the premixing chamber is provided with an iron powder-air inlet for introducing a mixture of iron powder and air, and the side wall is provided with a tangential air inlet for injecting tangential air into the premixing chamber along the tangential direction of the chamber wall. The downstream end is sealed and connected to the upstream end of the pre-combustion zone. The downstream end of the pre-combustion zone is sealed and connected to the upstream end of the main combustion zone; its cavity wall is provided with a local bulge structure and is equipped with a high-energy igniter and a reverse jet nozzle. The downstream end of the main combustion zone is sealed and connected to the upstream end of the burnout zone; its sidewalls are alternately distributed with weak swirling air inlets and wall-mounted air inlets in the horizontal direction, and each weak swirling air inlet and wall-mounted air inlet has a micro-bulge structure in the cavity wall area corresponding to it. The downstream end of the burnout zone is sealed and connected to the upstream end of the burner outlet; and the burnout zone adopts a gradually expanding conical cavity structure with burnout air inlets evenly distributed on the side wall. The reverse jet nozzle is connected to the flue gas diversion circuit at the burner outlet through a pipeline, and is used to reversely inject part of the high-temperature flue gas at the burner outlet into the pre-combustion zone.

[0005] Downstream of the burner outlet, a flue gas diversion structure is provided to divide the high-temperature flue gas discharged from the burner outlet into main path flue gas and circulating path flue gas. The main path flue gas enters the boiler furnace along the main flue and participates in the heat exchange process. The circulating path flue gas is introduced into a cyclone separator along the diversion pipeline. The gas outlet of the cyclone separator is connected to a check valve and a flow control device in sequence through a return pipeline. The end of the return pipeline is connected to the reverse jet nozzle of the pre-combustion zone.

[0006] The flow control device includes a variable frequency booster fan that provides power for the flue gas recirculation along the flue gas flow direction of the recirculation pipeline, and an electromagnetic flow valve for precisely controlling the flow rate and pressure parameters of the flue gas recirculated to the pre-combustion zone.

[0007] The bottom of the cyclone separator is connected to a solid product collection device that collects the solid particles separated by the cyclone separator via a solid product outlet.

[0008] An iron powder supply system is provided upstream of the premixing chamber. The iron powder supply system includes an iron powder storage bin, a rotary feeder, and a blower. The outlet of the iron powder storage bin is connected to the inlet of the rotary feeder, and the outlet of the rotary feeder is connected to the outlet pipe of the blower through a pipeline.

[0009] The high-energy igniters are respectively embedded on the two side cavity walls of the pre-combustion zone entrance area, and the ignition ends of the two high-energy igniters extend into the pre-combustion zone to reliably ignite the iron powder-air mixture entering the pre-combustion zone.

[0010] The inner surface of the cavity wall of the main combustion zone is coated with a high-temperature and wear-resistant composite coating to resist the erosion and wear of iron powder particles under high temperature conditions.

[0011] A combustion method for iron powder based on the above system includes the following steps: S1: Iron powder is discharged from the iron powder storage silo and enters the rotary feeder, which quantitatively conveys it to the outlet pipeline of the blower; the blower sends air into the pipeline, which mixes with the quantitative iron powder to form an iron powder-air mixture; the iron powder-air mixture enters the premixing chamber through the iron powder-air inlet, while tangential air is sent in along the tangential direction of the premixing chamber wall through the tangential air inlet, forming an enhanced co-current swirling field in the premixing chamber, realizing uniform gas-solid premixing of iron powder and air; S2: The premixed iron powder-air mixture enters the pre-combustion zone. The high-energy igniter starts and releases ignition energy into the mixture, igniting some of the iron powder particles. At the same time, the high-temperature flue gas from the burner outlet enters the reverse jet nozzle through the circulation path and injects high-temperature airflow into the pre-combustion zone. The high-temperature flue gas forms a stable reflux zone in the local bulging structure area of ​​the pre-combustion zone, continuously providing preheating and ignition conditions for the unburned iron powder particles. The local bulging structure also prolongs the residence time of the iron powder in the pre-combustion zone, ensuring ignition stability. S3: After stable ignition, the iron powder particles enter the main combustion zone. The weak swirling air is injected into the main combustion zone through the weak swirling air inlet, providing rotational power for the combustion process and enhancing the turbulent mixing of iron powder and oxygen. The wall-adhering air is sent in tangentially along the inner wall of the main combustion zone through the wall-adhering air inlet, forming a uniform anti-wall-adhering gas film to isolate the high-temperature iron powder particles from direct contact with the vessel wall. The micro-bulge structure in the main combustion zone regulates the local flue gas velocity, preventing iron powder particles from settling and achieving efficient and stable combustion of iron powder particles in a high-temperature environment. S4: Unburned iron powder particles enter the burnout zone with the flue gas. Burnout air is sent into the burnout zone through the burnout air inlet to supplement the oxygen required for combustion. The gradually expanding conical structure of the burnout zone reduces the flue gas velocity and prolongs the residence time of iron powder particles in the burnout zone, ensuring that the unburned iron powder particles are fully burned. S5: The high-temperature flue gas after combustion is discharged through the burner outlet, and most of the flue gas directly enters the boiler furnace to participate in heat exchange; a small part of the flue gas enters the cyclone separator through the diversion pipeline, and gas-solid separation is achieved through the cyclone separator, separating out the solid products and collecting them; the separated high-temperature gas flows back to the reverse jet nozzle in the pre-combustion zone after the parameters are adjusted by the check valve, the variable frequency booster fan and the electromagnetic flow valve, so as to continue to provide a stable combustion heat source for the pre-combustion zone.

[0012] In step S5, the distribution ratio of main path flue gas and circulating path flue gas is controlled by adjusting the opening of the electromagnetic flow valve; while ensuring the heat exchange requirements of the boiler furnace, the high temperature characteristics of the circulating path flue gas are used to achieve stable combustion in the pre-combustion zone, thereby improving the overall energy utilization rate of the burner system.

[0013] This invention effectively solves the technical problems of high-density agglomeration, high ignition temperature, easy slagging and wear, and difficult burnout associated with iron powder as fuel by constructing a staged combustion process of "premixing chamber swirl premixing, high-temperature ignition in pre-combustion zone, mixed combustion in main combustion zone, and supplementary air burnout in burnout zone," coupled with a high-temperature flue gas internal circulation system. The system diverts the high-temperature flue gas from the burner outlet. The main path flue gas enters the boiler for heat exchange to achieve energy output, while the circulating path flue gas, after being separated by a cyclone separator, flows back to the pre-combustion zone as a high-temperature gas source to assist ignition. This achieves the cascade and recycling of energy within the system, significantly improving overall energy utilization efficiency.

[0014] This invention achieves precise control of the flow field, temperature field, and reaction process during iron powder combustion by independently adjusting the airflow parameters of tangential wind, weak swirling wind, wall-adhering wind, and burnout wind in each functional area, ensuring stable, efficient, and safe operation of the combustion process. Furthermore, through precise temperature control of the main combustion zone, the generation of thermal nitrogen oxides is effectively suppressed, achieving ultra-low emissions of pollutants and demonstrating significant environmental advantages.

[0015] The present invention has at least the following beneficial technical effects: (1) The iron powder combustion process does not produce greenhouse gases such as carbon dioxide, thus solving the carbon emission problem caused by traditional fossil fuels.

[0016] (2) The solid products generated by combustion are mainly iron oxide, which can be efficiently collected by a cyclone separator. The collected iron oxide can be used as a raw material in the metallurgical and chemical fields, or it can be reduced and regenerated into iron powder by green energy such as hydrogen, thus constructing a closed-loop resource utilization system.

[0017] (3) The tangential swirl design of the premixing chamber works synergistically with the iron powder supply system to effectively break up iron powder agglomerates, address the technical pain point of high-density iron powder settling, significantly improve the uniformity of gas-solid mixing, and lay the foundation for subsequent stable combustion.

[0018] (4) A high-energy igniter and a reverse jet nozzle are set in the pre-combustion zone to reduce the ignition energy consumption of iron powder by utilizing the residual heat of high-temperature flue gas, and to adapt to the combustion characteristics of iron powder with high ignition temperature, so as to ensure ignition success rate and stability.

[0019] (5) The integrated design of “weak swirling air + wall-adhering air + micro-bulging” in the main combustion zone enhances the gas-solid mixing effect through weak swirling air and forms a uniform protective gas film through wall-adhering air, effectively preventing iron powder particles from directly contacting the burner wall and molten oxide from adhering to the wall and forming slag, significantly reducing the risk of equipment erosion and wear, and extending the service life of the burner.

[0020] (6) The burnout zone adopts a gradually expanding structure design, which can extend the residence time of iron powder particles in the combustion system. Combined with the precise air supply design, it provides sufficient oxygen for iron powder particles, ensuring that iron powder particles undergo a full oxidation reaction and greatly improving combustion efficiency.

[0021] (7) Through the flue gas diversion structure at the burner outlet, part of the high-temperature flue gas is returned to the pre-combustion zone as an auxiliary ignition and stable combustion heat source. No additional auxiliary fuel is required, realizing the cascade utilization and recycling of energy within the system, significantly improving the overall energy utilization efficiency and reducing equipment operating costs.

[0022] (8) The system adopts a staged combustion mode to precisely control the reaction temperature of the main combustion zone, effectively suppressing the generation path of thermal nitrogen oxides, achieving low nitrogen emissions during the combustion process, meeting environmental emission requirements, and demonstrating outstanding environmental advantages.

[0023] (9) This invention provides key combustion technology equipment adapted to the large-scale industrial application of iron powder, breaks through the technical bottleneck of iron powder as a zero-carbon energy carrier in industrial scenarios, enriches the utilization path of clean energy, and provides strong technical support for the transformation of energy structure in the industrial field. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the burner system of the present invention applicable to iron powder; Explanation of reference numerals in the attached diagram: 1 is iron powder storage silo, 2 is rotary feeder, 3 is blower, 4 is iron powder-air inlet, 5 is premixing chamber, 6 is tangential air inlet, 7 is high-energy igniter, 8 is reverse jet nozzle, 9 is pre-combustion zone, 10 is main combustion zone, 11 is weak swirl air inlet, 12 is wall-mounted air inlet, 13 is burnout zone, 14 is burnout air inlet, 15 is burner outlet, 16 is cyclone separator, 17 is solid product collection device, 18 is check valve, 19 is variable frequency booster fan, and 20 is electromagnetic flow valve. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0026] like Figure 1 As shown, the present invention provides a burner system suitable for iron powder, which consists of an iron powder supply unit, a combustion core unit, and a flue gas circulation unit. The specific structure, connection relationship, and function of each unit are as follows: (1) Iron powder supply unit: including iron powder storage silo 1, rotary feeder 2 and blower 3; wherein, the outlet of iron powder storage silo 1 is connected to the feed end of rotary feeder 2 through a pipe, and the outlet of rotary feeder 2 and the outlet of blower 3 are connected together to the iron powder-air inlet 4 of premixing chamber 5 to realize the quantitative mixing and conveying of iron powder and combustion air.

[0027] (2) Combustion core unit: along the flue gas flow direction, the premixing chamber 5, the pre-combustion zone 9, the main combustion zone 10 and the burnout zone 13 are connected in series; Premixing chamber 5: Tangential air inlets 6 are symmetrically opened on both sides of the premixing chamber along the circumferential direction to receive tangential air; after the tangential air is introduced through the inlets, a uniform unidirectional swirling flow field is formed in the premixing chamber 5, and the gas-solid mixing uniformity of the iron powder-air mixture is enhanced by the swirling flow disturbance. Pre-combustion zone 9: Its upstream end is sealed to the downstream end of the premixing chamber 5. High-energy igniters 7 are symmetrically embedded on both sides of the inlet end. The ignition end of the high-energy igniter 7 extends into the interior of the pre-combustion zone 9 to provide initial ignition energy. At the same time, two interfaces are symmetrically opened along the axis of the pre-combustion zone 9. Each interface is correspondingly sealed to a reverse jet nozzle 8, so that the return high-temperature flue gas can be evenly injected into the interior of the pre-combustion zone 9, and work together with the high-energy igniter 7 to form a stable high-temperature ignition environment. Main combustion zone 10: Its upstream end is sealed to the downstream end of pre-combustion zone 9. The two side walls are alternately and symmetrically opened with weak swirling air inlets 11 and wall-mounted air inlets 12 along the flue gas flow direction. Each cavity wall area corresponding to the weak swirling air inlet 11 and the wall-mounted air inlet 12 is fixedly provided with a micro-bulge structure. The weak swirling air strengthens the mixing, the wall-mounted air forms a wall gas film, and the micro-bulge structure regulates the flow field, so as to achieve efficient combustion of iron powder and wall protection. Combustion zone 13: Its upstream end is sealed to the downstream end of the main combustion zone 10, and its two side walls are symmetrically opened with combustion air inlets 14 in the circumferential direction to supplement the oxygen required in the later stage of combustion; its downstream outlet end is sealed to the burner outlet 15 to exhaust the high-temperature flue gas after combustion.

[0028] (3) Flue gas circulation unit: The high-temperature flue gas discharged from the burner outlet 15 is divided into two paths: one path is the main path flue gas, which enters the boiler furnace directly through the guide channel to participate in the heat exchange in the furnace and realize energy output; the other path is the circulation path flue gas, which is connected to the inlet of the cyclone separator 16, the check valve 18, the variable frequency booster fan 19, and the electromagnetic flow valve 20 in sequence through the diversion pipeline, and finally connected to the reverse jet nozzle 8 of the pre-combustion zone 9 through the pipeline to form a complete flue gas circulation loop.

[0029] This invention provides a combustion method suitable for iron powder, comprising the following steps: S1: Iron powder is discharged from iron powder storage silo 1 and enters rotary feeder 2, which quantitatively conveys it to the outlet pipeline of blower 3; blower 3 sends air into the pipeline, which mixes with the quantitative iron powder to form an iron powder-air mixture; the iron powder-air mixture enters the premixing chamber 5 through iron powder-air inlet 4, and at the same time, tangential air is sent into the premixing chamber 5 through tangential air inlet 6 along the tangential direction of the premixing chamber 5 wall, forming an enhanced co-current swirling field in the premixing chamber 5, so as to achieve uniform gas-solid premixing of iron powder and air; S2: The premixed iron powder-air mixture enters the pre-combustion zone 9. The high-energy igniter 7 is activated and releases ignition energy into the mixture, igniting some of the iron powder particles. At the same time, the high-temperature flue gas from the burner outlet 15 enters the reverse jet nozzle 8 through the circulation path and injects high-temperature airflow into the pre-combustion zone 9. The high-temperature flue gas forms a stable reflux zone in the local bulging structure area of ​​the pre-combustion zone 9, continuously providing preheating and ignition conditions for the unburned iron powder particles. The local bulging structure also prolongs the residence time of the iron powder in the pre-combustion zone 9, ensuring ignition stability. S3: After stable ignition, the iron powder particles enter the main combustion zone 10. The weak swirling air is injected into the main combustion zone 10 through the weak swirling air inlet 11 to provide rotational power for the combustion process and enhance the turbulent mixing of iron powder and oxygen. The wall-adhering air is sent into the main combustion zone 10 along the tangential direction of the inner wall through the wall-adhering air inlet 12 to form a uniform anti-wall-adhering gas film, which isolates the high-temperature iron powder particles from direct contact with the vessel wall. The micro-bulge structure in the main combustion zone 10 regulates the local flue gas velocity to prevent iron powder particles from settling, thereby achieving efficient and stable combustion of iron powder particles in a high-temperature environment. S4: Incompletely burned iron powder particles enter the burnout zone 13 with the flue gas. Burnout air is sent into the burnout zone 13 through the burnout air inlet 14 to supplement the oxygen required for combustion. The gradually expanding conical structure of the burnout zone 13 reduces the flue gas velocity and prolongs the residence time of iron powder particles in the burnout zone 13, ensuring that the unburned iron powder particles are fully burned. S5: The high-temperature flue gas after combustion is discharged through the burner outlet 15. Most of the flue gas directly enters the boiler furnace to participate in heat exchange. A small part of the flue gas enters the cyclone separator 16 through the diversion pipeline. The cyclone separator 16 achieves gas-solid separation, and the solid products (mainly iron oxide) are separated and collected by the solid product collection device 17. After the separated high-temperature gas is adjusted by the check valve 18, the variable frequency booster fan 19 and the electromagnetic flow valve 20, it flows back to the reverse jet nozzle 8 of the pre-combustion zone 9 to continue to provide a stable combustion heat source for the pre-combustion zone 9.

Claims

1. A burner system suitable for iron powder, characterized in that, Along the flue gas flow direction, it includes a premixing chamber (5), a pre-combustion zone (9), a main combustion zone (10), a burnout zone (13), and a burner outlet (15) connected in sequence: The upstream end of the premixing chamber (5) is provided with an iron powder-air inlet (4) for introducing a mixture of iron powder and air, and the side wall is provided with a tangential air inlet (6) for injecting tangential air into the premixing chamber (5) along the tangential direction of the chamber wall. The downstream end is sealed and connected to the upstream end of the pre-combustion zone (9). The downstream end of the pre-combustion zone (9) is sealed and connected to the upstream end of the main combustion zone (10); its cavity wall is provided with a local bulge structure and is equipped with a high-energy igniter (7) and a reverse jet nozzle (8). The downstream end of the main combustion zone (10) is sealed and connected to the upstream end of the burnout zone (13); Its sidewalls are alternately distributed with weak swirling air inlets (11) and wall-mounted air inlets (12) in the horizontal direction, and each cavity wall area corresponding to a weak swirling air inlet (11) and a wall-mounted air inlet (12) is provided with a micro-bulge structure; The downstream end of the burnout zone (13) is sealed and connected to the upstream end of the burner outlet (15); and the burnout zone (13) adopts a gradually expanding conical cavity structure with burnout air inlets (14) evenly distributed on the side wall. The reverse jet nozzle (8) is connected to the flue gas diversion circuit of the burner outlet (15) through a pipeline, and is used to reversely inject part of the high-temperature flue gas from the burner outlet (15) into the pre-combustion zone (9). Downstream of the burner outlet (15), there is a flue gas diversion structure that divides the high-temperature flue gas discharged from the burner outlet (15) into main path flue gas and circulating path flue gas; the main path flue gas enters the boiler furnace along the main flue and participates in the heat exchange process; the circulating path flue gas is introduced into the cyclone separator (16) along the diversion pipeline, and the gas outlet of the cyclone separator (16) is connected to the check valve (18) and the flow control device in sequence through the return pipeline, and the end of the return pipeline is connected to the reverse jet nozzle (8) of the pre-combustion zone (9).

2. The burner system for iron powder according to claim 1, characterized in that, The flow control device includes a variable frequency booster fan (19) that provides power for the flue gas recirculation along the flue gas flow direction of the recirculation pipeline, and an electromagnetic flow valve (20) for precisely controlling the flue gas flow and pressure parameters recirculated to the pre-combustion zone (9).

3. The burner system for iron powder according to claim 2, characterized in that, The bottom of the cyclone separator (16) is connected to a solid product collection device (17) that collects the solid particles separated by the cyclone separator (16) via a solid product outlet.

4. The burner system for iron powder according to claim 3, characterized in that, An iron powder supply system is provided upstream of the premixing chamber (5). The iron powder supply system includes an iron powder storage silo (1), a rotary feeder (2), and a blower (3). The outlet of the iron powder storage silo (1) is connected to the inlet of the rotary feeder (2), and the outlet of the rotary feeder (2) is connected to the outlet pipe of the blower (3) through a pipeline.

5. The burner system for iron powder according to claim 4, characterized in that, The high-energy igniters (7) are respectively embedded on the two side walls of the inlet area of ​​the pre-combustion zone (9), and the ignition ends of the two high-energy igniters (7) extend into the interior of the pre-combustion zone (9) to reliably ignite the iron powder-air mixture entering the pre-combustion zone (9).

6. The burner system for iron powder according to claim 5, characterized in that, The inner surface of the cavity wall of the main combustion zone (10) is coated with a high-temperature wear-resistant composite coating to resist the erosion and wear of iron powder particles under high temperature conditions.

7. A combustion method for iron powder based on the system of claim 6, characterized in that, Includes the following steps: S1: Iron powder is discharged from the iron powder storage silo (1) and enters the rotary feeder (2), which quantitatively conveys it to the outlet pipeline of the blower (3); the blower (3) sends air into the pipeline and mixes it with the quantitative iron powder to form an iron powder-air mixture; the iron powder-air mixture enters the premixing chamber (5) through the iron powder-air inlet (4), and at the same time, tangential air is sent into the premixing chamber (5) along the tangential direction of the premixing chamber (5) wall through the tangential air inlet (6), forming a strengthened unidirectional swirling flow field in the premixing chamber (5) to achieve uniform gas-solid premixing of iron powder and air; S2: The premixed iron powder-air mixture enters the pre-combustion zone (9), the high-energy igniter (7) starts and releases ignition energy to the mixture, igniting some iron powder particles; at the same time, the high-temperature flue gas from the burner outlet (15) enters the reverse jet nozzle (8) through the circulation path and sprays high-temperature airflow into the pre-combustion zone (9); the high-temperature flue gas forms a stable reflux zone in the local bulging structure area of ​​the pre-combustion zone (9), continuously providing preheating and ignition conditions for unburned iron powder particles, and the local bulging structure prolongs the residence time of iron powder in the pre-combustion zone (9), ensuring ignition stability; S3: After stable ignition, the iron powder particles enter the main combustion zone (10). The weak swirling air is injected into the main combustion zone (10) through the weak swirling air inlet (11) to provide rotational power for the combustion process and enhance the turbulent mixing of iron powder and oxygen. The wall-adhering air is sent into the main combustion zone (10) along the tangential direction of the inner wall of the main combustion zone (10) through the wall-adhering air inlet (12) to form a uniform anti-wall-adhering gas film, which isolates the high-temperature iron powder particles from direct contact with the vessel wall. The micro-bulge structure in the main combustion zone (10) regulates the local flue gas velocity, avoids the settling of iron powder particles, and realizes efficient and stable combustion of iron powder particles in a high-temperature environment. S4: Incompletely burned iron powder particles enter the burnout zone (13) with the flue gas. Burnout air is sent into the burnout zone (13) through the burnout air inlet (14) to supplement the oxygen required for combustion. The gradually expanding conical structure of the burnout zone (13) reduces the flue gas flow rate and prolongs the residence time of iron powder particles in the burnout zone (13), ensuring that the unburned iron powder particles are fully burned. S5: The high-temperature flue gas after combustion is discharged through the burner outlet (15), and most of the flue gas directly enters the boiler furnace to participate in heat exchange; a small part of the flue gas enters the cyclone separator (16) through the diversion pipeline, and gas-solid separation is achieved through the cyclone separator (16), separating out the solid products and collecting them; the separated high-temperature gas is returned to the reverse jet nozzle (8) of the pre-combustion zone (9) after the parameters are adjusted by the check valve (18), the variable frequency booster fan (19) and the electromagnetic flow valve (20), and continues to provide a stable combustion heat source for the pre-combustion zone (9).

8. The combustion method for iron powder according to claim 7, characterized in that, In step S5, the distribution ratio of main path flue gas and circulating path flue gas is controlled by adjusting the opening of electromagnetic flow valve (20); while ensuring the heat exchange requirements of boiler furnace, the high temperature characteristics of circulating path flue gas are used to achieve stable combustion in pre-combustion zone (9) and improve the overall energy utilization rate of burner system.

Images