Biomass boiler combustion device and combustion method

Abstract

The invention relates to the technical field of boiler equipment, and discloses a biomass boiler combustion device and method.The biomass boiler combustion device comprises a boiler body, a feeding pipe is installed at the top of the boiler body, a grading unit is arranged in the boiler body, and the grading unit comprises a guide isolation cover fixedly installed on the inner wall of the boiler body through multiple sets of connecting pieces; the whole feeding pipe is in an inverted funnel shape, and a discharging guide cone used for preliminarily guiding a particle fuel discharging path is fixed to the center of the upper surface of the guide isolation cover. According to the equipment, particle fuel is guided through all parts of the grading unit and intercepted and retarded through the guide isolation cover, high-temperature flue gas is used for pre-dehydration, fuel of different particle sizes is screened through the multi-stage ring net to form a particle fuel ring, and the fuel is guided by the lower guide cone to sequentially flow through the low-combustion area, the medium-combustion area and the high-combustion area to achieve step-by-step combustion. Particle fuel is subjected to partition adaptation according to states, graded sufficient combustion is achieved, the smoldering phenomenon is avoided from the source, and the combustion uniformity and the fuel utilization rate are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of boiler equipment technology, and in particular to a biomass boiler combustion device and combustion method. Background Technology

[0002] Biomass boilers are biomass co-firing boilers adapted to the development needs of the new energy industry, and belong to the core energy equipment in the fields of biomass energy and other new energy industries. Biomass boilers use biomass pellets made from organic waste such as straw and wood as the main pellet fuel, and can also co-process the waste gas generated during the production process. They adopt a dual pellet fuel supply mode of biomass pellet fuel and production waste gas, and are equipped with a complete feeding system, a screen-type heating surface structure, and environmental protection treatment devices such as SCR denitrification and bag dust collection to ensure efficient combustion of pellet fuel and compliant treatment of pollutants. Its core purpose is to replace traditional fossil energy boilers, reduce dependence on non-renewable energy sources such as coal, and realize the resource utilization of biomass waste, respond to the requirements of low-carbon development policies, and help achieve carbon reduction goals. In practical applications, they are mainly used to undertake clean heating and power supply functions, which not only fits the development direction of the new energy industry, but also meets the resource recycling needs of the biomass energy field.

[0003] Regarding the above-mentioned and existing related technologies, the inventors believe that the following defects often exist: First, existing boiler equipment is insufficient in adaptability to the characteristics of pellet fuel. After pellet fuel is mixed and piled up, uneven air permeability is easy to occur. Some pellet fuel will also clump together due to high humidity, blocking the combustion channel, causing local oxygen supply to be unable to penetrate, the fuel falls into a state of oxygen deficiency, and burns without being deoxygenated, a large amount of heat is consumed, it is difficult to stably reach the ignition point, resulting in discontinuous combustion. Ultimately, the pellet fuel frequently "smolders," resulting in low combustion efficiency and failing to meet the requirements for clean and efficient combustion of biomass. Summary of the Invention

[0004] The technical problem to be solved by this invention is that uneven moisture content of particulate fuel in the prior art can easily cause boiler smoldering and reduced combustion efficiency. To address this, we propose a biomass boiler combustion device and combustion method.

[0005] To achieve the above objectives, this application adopts the following technical solution: a biomass boiler combustion device, including a furnace body, a feed pipe installed on the top of the furnace body, and a grading unit arranged inside the furnace body; The grading unit includes a guide shield fixedly installed on the inner wall of the furnace body via multiple sets of connectors. The feed pipe is shaped like an inverted funnel. A feed guide cone for initially guiding the particle fuel path is fixed at the center of the upper surface of the guide shield. A multi-stage ring network for grading and distributing particle fuel of different sizes is fixed on the inner wall of the furnace body below the guide shield. A bottom perforated plate is fixed on the inner wall of the furnace body below the multi-stage ring network. A lower guide cone is fixed at the center of the upper surface of the bottom perforated plate. The upper surface of the guide shield and the space of the inner wall of the furnace body together form a low-combustion zone. The side wall of the guide shield and the inner wall of the furnace body together form a feed ring cavity. The inner walls of the guide shield and the bottom perforated plate together form a medium-combustion zone with the inner wall of the furnace body. The lower surface of the bottom perforated plate together forms a high-combustion zone with the inner wall of the furnace body.

[0006] Preferably, the sidewall of the feeding guide cone has a hollow structure, the axes of the furnace body, the feed pipe, the guide shield and the feeding guide cone are coincident, the upper surface of the guide shield is slightly arched, and the top of the feeding guide cone extends into the inside of the feed pipe.

[0007] Preferably, the middle position of the guide shield is a variable diameter section, and the top diameter of the guide shield is larger than the bottom diameter of the guide shield.

[0008] Preferably, the surface of the multi-level ring network is equipped with multiple layers of filter arc plates from top to bottom, the multi-level ring network is funnel-shaped as a whole, and the center of the multi-level ring network has an opening, and the mesh count of the filter arc plates increases layer by layer from top to bottom.

[0009] Preferably, one end of the multi-level ring network moves away from the lower guide cone layer by layer from top to bottom, the top of the lower guide cone is pointed, and the top of the lower guide cone extends into the interior of the intermediate combustion zone.

[0010] Preferably, the low-combustion zone, medium-combustion zone, and high-combustion zone are interconnected, and the curved outer wall of the guide shield and part of the inner wall of the furnace body are provided with frosted texture.

[0011] Preferably, multiple sets of burners are interspersed on the outer wall of the furnace body, and the output ends of multiple sets of burners extend into the interior of the low-combustion zone and the high-combustion zone.

[0012] Preferably, multiple sets of gas supply pipes are installed interlaced on the outer wall of the furnace body, and the output ends of multiple sets of gas supply pipes extend into the interior of the low-combustion zone and the high-combustion zone, with each set of burners and gas supply pipes being symmetrical to each other.

[0013] Preferably, an exhaust pipe is fixedly connected to the upper surface of the furnace body, and a bottom furnace cavity is fixed to the bottom end of the furnace body.

[0014] The combustion method of a biomass boiler combustion device includes the following steps: S1. First, the pellet fuel is guided and pre-dehydrated. The pellet fuel enters the furnace body through the feed pipe at the top of the furnace body. The feed guide cone guides the pellet fuel in a circumferential direction to form an umbrella-shaped feed surface. The pellet fuel enters the low combustion zone along the feed ring cavity. The slightly arched upper surface of the guide cover intercepts part of the pellet fuel. The high-temperature flue gas flowing in from the inner wall is used to pre-dehydrate the pellet fuel. S2. Next, the pellet fuel is graded, screened, and initially combusted in the intermediate combustion zone. The pellet fuel enters the intermediate combustion zone from the low combustion zone and falls along the inclined surface of the multi-stage ring network. After being graded and screened by the multi-layer filter arc plate, it is guided by the variable diameter structure at the bottom to fall onto the upper surface of the bottom perforated plate to form a multi-stage pellet fuel ring. The annular combustion ring heats the multi-stage ring network, further dehydrating the passing pellet fuel and achieving initial combustion. S3. Next, the pellet fuel is fully burned in the high-combustion zone and the ash is separated. After the initial combustion, the pellet fuel falls into the high-combustion zone. The lower guide cone reduces the connection between the opening and the high-combustion zone, extending the residence time of the pellet fuel. The burner and the gas supply pipe provide the maximum gas supply and high-intensity flame according to the needs of the high-combustion zone, so that the pellet fuel is fully burned. The bottom sieve screens the ash after combustion into the bottom furnace cavity. S4. Finally, there is the re-combustion and emission of flue gas. The flue gas generated by combustion rises from the high-combustion zone to the medium-combustion zone through the exhaust channel, and then flows into the low-combustion zone through the hollow part of the feed guide cone. It comes into contact with the downstream particulate fuel to increase the rising time of the flue gas, providing sufficient time for the flue gas to be re-combusted and for heat recovery. Finally, the flue gas is discharged through the exhaust pipe on the upper surface of the furnace body.

[0015] The technical effects and advantages of this invention are as follows: In this invention, the equipment guides the particulate fuel through various components of the grading unit, slows down the flow by intercepting the fuel with a guide hood, pre-dehydrates the high-temperature flue gas, and forms particulate fuel rings by screening different particle sizes through a multi-stage ring network. The lower guide cone guides the fuel to flow sequentially through the low-combustion zone, medium-combustion zone, and high-combustion zone to achieve staged combustion. This enables the particulate fuel to be zoned and adapted according to its state and to achieve full combustion in stages, thereby avoiding smoldering from the source and significantly improving combustion uniformity and fuel utilization.

[0016] In this invention, the equipment, through a burner, a gas supply pipe, a flue gas channel, and a bottom perforated plate, optimizes combustion conditions, ensures combustion stability, further improves boiler combustion efficiency, reduces the difficulty of later cleaning and maintenance, and ensures that flue gas pollutants are discharged in compliance with standards. Attached Figure Description

[0017] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts: Figure 1 This is a schematic diagram of the main external structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the present invention; Figure 3 This is a cross-sectional schematic diagram of the internal structure of the guide shield of the present invention; Figure 4 This is a cross-sectional schematic diagram of the internal structure of the multi-level ring network of the present invention; Figure 5 This is a schematic diagram of the internal structure of the present invention. Figure 6 This is a cross-sectional view of the internal structure of the present invention.

[0018] Legend: 1. Furnace body; 11. Feed pipe; 12. Exhaust pipe; 13. Bottom furnace cavity; 14. Burner; 15. Gas supply pipe; 2. Grading unit; 21. Guide baffle; 211. Feed guide cone; 22. Multi-stage ring network; 23. Bottom perforated plate; 231. Lower guide cone; 24. Low combustion zone; 25. Medium combustion zone; 26. High combustion zone. Detailed Implementation

[0019] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0020] Reference Figure 1-6 As shown, the present invention provides a technical solution: a biomass boiler combustion device, including a furnace body 1, a feed pipe 11 installed on the top of the furnace body 1, and a grading unit 2 arranged inside the furnace body 1; The grading unit 2 includes a guide shield 21 fixedly installed on the inner wall of the furnace body 1 via multiple sets of connectors. The feed pipe 11 is shaped like an inverted funnel, and the inner wall of the guide shield 21 can be fitted with a heat exchange device to remove the heat generated during combustion from the boiler equipment. A feed guide cone 211 for initially guiding the path of the pellet fuel is fixed at the center of the upper surface of the guide shield 21. The feed guide cone 211 guides the continuously falling pellet fuel in a circumferential direction to the interior of the low-combustion zone 24. The pellet fuel continuously impacts the feed guide cone 211 to form a continuous "umbrella-shaped feed surface". Then the pellet fuel continues to flow and enters the intermediate combustion zone 25 along the feed ring cavity. A multi-stage ring mesh 22 for grading and distributing pellet fuel of different particle sizes is fixed on the inner wall of the furnace body 1 below the guide shield 21. The pellet fuel falls along the inclined surface of the multi-stage ring mesh 22. During the falling process, the pellet fuel of different particle sizes is screened and graded by the multi-stage ring mesh 22 and falls to the bottom hole. On the upper surface of plate 23, pellet fuel is guided by the "variable diameter structure" at the bottom of the multi-stage ring network 22 to fall onto the upper surface of the bottom perforated plate 23 and form a multi-stage "particle fuel ring". This increases the combustion intensity by increasing the combustible area of ​​the pellet fuel. The bottom perforated plate 23 is fixed on the inner wall of the furnace body 1 and below the multi-stage ring network 22. The bottom perforated plate 23 is used to screen the ash after combustion into the interior of the bottom furnace cavity 13. During subsequent manual cleaning, the cleaning port set at the bottom of the furnace wall can be opened to clean the ash. Ash is cleaned up. A lower guide cone 231 is fixed at the center of the upper surface of the bottom perforated plate 23. The lower guide cone 231 is used to reduce the connection between the opening and the high combustion zone 26. The upper surface of the guide cover 21 and the inner wall space of the furnace body 1 together form the low combustion zone 24. The side wall of the guide cover 21 and the inner wall of the furnace body 1 together form the feeding ring cavity. The inner walls of the guide cover 21 and the bottom perforated plate 23 together with the inner wall of the furnace body 1 together form the medium combustion zone 25. The lower surface of the bottom perforated plate 23 and the inner wall of the furnace body 1 together form the high combustion zone 26. The "variable diameter structure" specifically refers to the fact that the distance between one end of the filter arc plate of each stage and the outer wall of the lower guide cone 231 increases from top to bottom, so the cross-sectional shape of the cavity area at the bottom of the multi-stage ring network 22 is triangular. The term "particle fuel ring" specifically refers to the multiple ring-shaped material piles that form after the particle fuel falls onto the upper surface of the bottom perforated plate 23. Since the particle fuel is in a state of gradual accumulation, the particle fuel will form a ring-shaped pile with a narrow upper end and a wide lower end as it accumulates.

[0021] Reference Figure 2-6 As shown in this embodiment: the side wall of the feeding guide cone 211 is a hollow structure, the axes of the furnace body 1, the feeding pipe 11, the guide cover 21 and the feeding guide cone 211 coincide, the upper surface of the guide cover 21 is slightly arched, and the top of the feeding guide cone 211 extends into the inside of the feeding pipe 11. Among them, the annular outer wall of the lower guide cone 231, the through-hole space, the intermediate combustion zone 25, the inner wall and hollowed-out part of the feeding guide cone 211, and the low combustion zone 24 together constitute the smoke exhaust channel. The upper surface of the baffle 21 is slightly arched, which can trap some particulate fuel. The high-temperature flue gas continuously flowing into the inner wall of the baffle 21 is used to dry the particulate fuel located in the low combustion zone 24 for a short time, and to perform a certain degree of pre-dehydration treatment on the particulate fuel.

[0022] Reference Figure 3-6 As shown in this embodiment: the middle position of the guide shield 21 is a variable diameter section, and the top diameter of the guide shield 21 is larger than the bottom diameter of the guide shield 21. As a large amount of material continuously flows into the combustion zone 25 along the feeding ring cavity, the multi-section diameter change of the guide cover 21 can slow down the falling speed of the particulate fuel to a certain extent and increase the drying time of the particulate fuel. The guide cover 21 is made of wear-resistant alloy and has good thermal conductivity. After being continuously heated by high-temperature flue gas, the guide cover 21 is in a high-temperature state and can continuously heat the particulate fuel that passes through it in contact.

[0023] Reference Figure 3-6 As shown in this embodiment: the surface of the multi-level ring network 22 is equipped with multiple layers of filter arc plates from top to bottom, the multi-level ring network 22 is funnel-shaped, and the center of the multi-level ring network 22 has an opening, and the mesh count of the filter arc plates increases layer by layer from top to bottom; After being filtered through multiple layers by the filter arc plate, the pellet fuel is divided into inner and outer rings using a "variable diameter structure". This distinguishes the combustion intensity of the inner and outer rings of pellet fuel with different particle sizes. The outermost ring of pellet fuel has the highest combustion intensity. The annular combustion ring formed by the combustion of multiple pellet fuel rings heats the multi-level ring network 22, continuously heating and drying the pellet fuel passing through the inclined surface of the multi-level ring network 22, further reducing the moisture content.

[0024] Reference Figure 3-6 As shown in this embodiment: one end of the multi-level ring network 22 moves away from the lower guide cone 231 layer by layer from top to bottom, the top of the lower guide cone 231 is cone-shaped, and the top of the lower guide cone 231 extends into the interior of the intermediate combustion zone 25; The low-combustion zone 24, medium-combustion zone 25, and high-combustion zone 26 are connected, and the curved outer wall of the guide cover 21 and part of the inner wall of the furnace body 1 are provided with frosted texture. The frosted texture can further increase the friction with the particulate fuel and slow down its falling speed.

[0025] Reference Figure 3-6 As shown in this embodiment, multiple sets of burners 14 are interspersed on the outer wall of the furnace body 1, and the output ends of the multiple sets of burners 14 extend into the interior of the low-combustion zone 24 and the high-combustion zone 26.

[0026] Multiple sets of gas supply pipes 15 are installed on the outer wall of the furnace body 1, and the output ends of multiple sets of gas supply pipes 15 extend into the interior of the low combustion zone 24 and the high combustion zone 26. Each set of burners 14 and gas supply pipes 15 are symmetrical to each other. By controlling the output intensity of the burner 14 and the gas supply pipe 15 located in the low-combustion zone 24 and the high-combustion zone 26 in stages, the necessary medium is provided for the stepwise heating and combustion of the pellet fuel. Specifically, the gas supply in the low-combustion zone 24 is the smallest, while that in the high-combustion zone 26 is the largest. Similarly, the combustion intensity of the burner 14 can also be differentiated. In the low-combustion zone 24, the pellet fuel is burned by a low-intensity flame, while in the high-combustion zone 26, the pellet fuel is burned by a high-intensity flame.

[0027] Reference Figure 1-6 As shown in this embodiment: the upper surface of the furnace body 1 is connected and fixed with a flue pipe 12, and the bottom furnace cavity 13 is fixed at the bottom end of the furnace body 1.

[0028] The combustion method of a biomass boiler combustion device includes the following steps: S1. First, the pellet fuel is guided and pre-dehydrated. The pellet fuel enters the furnace body 1 through the feed pipe 11 at the top of the furnace body 1. The feed guide cone 211 guides the pellet fuel in a circumferential direction to form an umbrella-shaped feed surface. The pellet fuel enters the low combustion zone 24 along the feed ring cavity. The guide baffle 21 retains part of the pellet fuel on its slightly arched upper surface. The high-temperature flue gas flowing in from the inner wall is used to pre-dehydrate the pellet fuel. S2. Next, the pellet fuel is graded, screened, and initially combusted in the intermediate combustion zone 25. The pellet fuel enters the intermediate combustion zone 25 from the low combustion zone 24 and falls along the inclined surface of the multi-stage ring network 22. After being graded and screened by the multi-layer filter arc plate, it is guided by the variable diameter structure at the bottom to fall onto the upper surface of the bottom perforated plate 23 to form a multi-stage pellet fuel ring. The annular combustion ring heats the multi-stage ring network 22, further dehydrating the passed pellet fuel and achieving initial combustion. S3. Next, the pellet fuel is fully burned in the high-combustion zone 26 and the ash is separated. After the initial combustion, the pellet fuel falls into the high-combustion zone 26. The lower guide cone 231 reduces the connection between the opening and the high-combustion zone 26, extending the residence time of the pellet fuel. The burner 14 and the gas supply pipe 15 provide the maximum gas supply and high-intensity flame according to the needs of the high-combustion zone 26, so that the pellet fuel is fully burned. The bottom sieve plate 23 screens the incinerated ash into the bottom furnace chamber 13. S4. Finally, the flue gas is re-burned and discharged. The flue gas generated by combustion rises from the high combustion zone 26 to the medium combustion zone 25 through the exhaust channel, and then flows into the low combustion zone 24 through the hollow part of the feed guide cone 211. It comes into contact with the downstream particulate fuel to increase the rising time of the flue gas, providing sufficient time for the flue gas to be re-burned and for heat recovery. Finally, the flue gas is discharged through the exhaust pipe 12 on the upper surface of the furnace body 1.

[0029] Working principle: First, the pellet fuel enters the furnace body 1 through the feed pipe 11 at the top of the furnace body 1. At this time, the pointed tip of the feed guide cone 211 can accurately guide the continuously falling pellet fuel in the circumferential direction, so that the pellet fuel forms a continuous "umbrella-shaped feed surface", and then smoothly and slowly enters the low combustion zone 24 along the gradually narrowing space of the feed ring cavity. Meanwhile, the side wall of the feeding guide cone 211 is a hollow structure, which can be used in conjunction with the guide baffle 21 to form an important part of the flue gas channel. The guide baffle 21 is fixed to the inner wall of the furnace body 1 through the connector. Its slightly arched upper surface can intercept part of the particulate fuel. The high temperature flue gas continuously flowing into the inner wall of the guide baffle 21 can be used to pre-dehydrate the particulate fuel in the low combustion zone 24 for a short time, which can initially dehydrate the particulate fuel. Secondly, the multi-stage ring network 22 can classify and screen the pellet fuel, accurately separating pellet fuel of different sizes. Then, the "variable diameter structure" at the bottom of the multi-stage ring network 22 guides the pellet fuel to fall onto the upper surface of the bottom perforated plate 23, ultimately forming a multi-stage "pellet fuel ring". This structure increases the combustible area of ​​the pellet fuel to a certain extent, allowing the pellet fuel to be evenly heated and initially combusted in the intermediate combustion zone 25. In addition, the annular distribution of the pellet fuel ring can also heat the multi-stage ring network 22, further dehydrating the pellet fuel that subsequently passes through the inclined surface of the multi-stage ring network 22 and enhancing the anti-smoldering effect. Secondly, the particulate fuel processed in the intermediate combustion zone 25 falls into the high combustion zone 26. The annular outer wall and the gap space between the opening form part of the exhaust channel, which can reduce the connection between the opening and the high combustion zone 26 and prolong the residence time of the particulate fuel in the high combustion zone 26. Meanwhile, the multiple sets of burners 14 and gas supply pipes 15 installed on the outer wall of the furnace body 1 adopt a graded control method. The low-combustion zone 24 has the smallest gas supply and the lowest combustion intensity, while the high-combustion zone 26 has the largest gas supply and the highest combustion intensity. This design can provide sufficient combustion medium and high-intensity flame for the high-combustion zone 26 according to the state of the pellet fuel after pre-dehydration in the low-combustion zone 24 and screening in the medium-combustion zone 25. This avoids the pellet fuel from smoldering due to insufficient combustion conditions and allows the pellet fuel to achieve complete combustion in the high-combustion zone 26. In addition, the bottom perforated plate 23 can screen the incinerated ash into the bottom furnace cavity 13 and clean it through the cleaning port later to prevent ash from accumulating in the combustion area and further prevent smoldering problems caused by ash obstruction. Meanwhile, throughout the combustion process, the exhaust channel, specifically composed of the annular outer wall of the lower guide cone 231 and the through-hole space, the intermediate combustion zone 25, the inner wall and hollowed-out area of ​​the feeding guide cone 211, and the low combustion zone 24, serves as an auxiliary anti-smoldering component. It guides the flue gas generated by combustion from the high combustion zone 26 to the intermediate combustion zone 25, and then through the hollowed-out opening at the top of the inner wall of the guide baffle 21 into the low combustion zone 24. During this process, the flue gas comes into contact with the continuously flowing particulate fuel as it rises. The downward flow velocity of the particulate fuel increases the flue gas rising time, providing sufficient time for the re-combustion of the flue gas in the intermediate combustion zone 25. This not only reduces the impurity content in the flue gas, making it meet emission standards, but also allows the heat carried by the flue gas to act on the particulate fuel again, assisting in the dehydration and heating of the particulate fuel, further improving the combustion performance of the particulate fuel, and avoiding the risk of smoldering from multiple dimensions. In summary, the coordinated action of all components forms a complete anti-smoldering combustion structure. The feeding guide cone 211 guides and pre-dehydrates the fuel, the guide baffle 21 intercepts and slows the fuel flow, the multi-stage ring network 22 screens and expands the fuel surface, the burner 14 provides graded gas supply, and the flue gas in the exhaust channel is reused. Ultimately, the pellet fuel completes pre-dehydration in the low-temperature combustion zone 24, graded screening and preliminary combustion in the medium-temperature combustion zone 25, and completes full combustion in the high-temperature combustion zone 26. Throughout the process, there is no "smoldering" phenomenon caused by excessively high humidity of the pellet fuel, uneven particle size, accumulation and blockage, or insufficient combustion medium. Moreover, the combustion intensity is high, the pellet fuel utilization rate is high, and the ash can be separated in time and the impurity content of the flue gas is low. This not only improves the combustion efficiency of the biomass boiler, but also reduces the difficulty of later cleaning and maintenance.

[0030] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A biomass boiler combustion device, characterized in that, The furnace includes a furnace body, a feed pipe is installed on the top of the furnace body, and a grading unit is provided inside the furnace body; The grading unit includes a guide shield fixedly installed on the inner wall of the furnace body via multiple sets of connectors. The feed pipe is shaped like an inverted funnel. A feed guide cone for initially guiding the feed path of the pellet fuel is fixed at the center of the upper surface of the guide shield. A multi-stage ring network for grading and distributing pellet fuel of different particle sizes is fixed on the inner wall of the furnace body below the guide shield. A bottom perforated plate is fixed on the inner wall of the furnace body below the multi-stage ring network. A lower guide cone is fixed at the center of the upper surface of the bottom perforated plate. The upper surface of the guide shield and the space of the inner wall of the furnace body together form a low-combustion zone. The side wall of the guide shield and the inner wall of the furnace body together form a feed ring cavity. The inner walls of the guide shield and the bottom perforated plate together form a medium-combustion zone with the inner wall of the furnace body. The lower surface of the bottom perforated plate together forms a high-combustion zone with the inner wall of the furnace body.

2. The biomass boiler combustion device according to claim 1, characterized in that: The sidewall of the feeding guide cone has a hollow structure. The axes of the furnace body, the feed pipe, the guide shield and the feeding guide cone are coincident. The upper surface of the guide shield is slightly arched. The top of the feeding guide cone extends into the inside of the feed pipe.

3. The biomass boiler combustion device according to claim 1, characterized in that: The middle section of the guide shield is a variable diameter section, and the top diameter of the guide shield is larger than the bottom diameter of the guide shield.

4. The biomass boiler combustion device according to claim 1, characterized in that: The surface of the multi-level ring network is equipped with multiple layers of filter arc plates from top to bottom. The multi-level ring network is funnel-shaped as a whole, and an opening is opened in the center of the multi-level ring network. The mesh count of the filter arc plates increases layer by layer from top to bottom.

5. The biomass boiler combustion device according to claim 1, characterized in that: Furthermore, one end of the multi-level ring network moves away from the lower guide cone layer by layer from top to bottom, and the top of the lower guide cone is cone-shaped, extending into the interior of the intermediate combustion zone.

6. The biomass boiler combustion device according to claim 1, characterized in that: The low-combustion zone, medium-combustion zone, and high-combustion zone are interconnected, and the curved outer wall of the guide cover and part of the inner wall of the furnace body are provided with frosted texture.

7. The biomass boiler combustion device according to claim 1, characterized in that: Multiple sets of burners are interspersed on the outer wall of the furnace body, and the output ends of multiple sets of burners extend into the interior of the low-combustion zone and the high-combustion zone.

8. The biomass boiler combustion device according to claim 7, characterized in that: Multiple sets of gas supply pipes are interspersed on the outer wall of the furnace body, and the output ends of multiple sets of gas supply pipes extend into the interior of the low combustion zone and the high combustion zone. Each set of burners and gas supply pipes are symmetrical to each other.

9. The biomass boiler combustion device according to claim 1, characterized in that: The upper surface of the furnace body is connected and fixed with a flue pipe, and the bottom end of the furnace body is fixed with a bottom furnace cavity.

10. The combustion method of the biomass boiler combustion device according to any one of claims 1-9, characterized in that: Includes the following steps: S1. First, the pellet fuel is guided and pre-dehydrated. The pellet fuel enters the furnace body through the feed pipe at the top of the furnace body. The feed guide cone guides the pellet fuel in a circumferential direction to form an umbrella-shaped feed surface. The pellet fuel enters the low combustion zone along the feed ring cavity. The slightly arched upper surface of the guide cover intercepts part of the pellet fuel. The high-temperature flue gas flowing in from the inner wall is used to pre-dehydrate the pellet fuel. S2. Next, the pellet fuel is graded, screened, and initially combusted in the intermediate combustion zone. The pellet fuel enters the intermediate combustion zone from the low combustion zone and falls along the inclined surface of the multi-stage ring network. After being graded and screened by the multi-layer filter arc plate, it is guided by the variable diameter structure at the bottom to fall onto the upper surface of the bottom perforated plate to form a multi-stage pellet fuel ring. The annular combustion ring heats the multi-stage ring network, further dehydrating the passing pellet fuel and achieving initial combustion. S3. Next, the pellet fuel is fully burned in the high-combustion zone and the ash is separated. After the initial combustion, the pellet fuel falls into the high-combustion zone. The lower guide cone reduces the connection between the opening and the high-combustion zone, extending the residence time of the pellet fuel. The burner and the gas supply pipe provide the maximum gas supply and high-intensity flame according to the needs of the high-combustion zone, so that the pellet fuel is fully burned. The bottom sieve screens the ash after combustion into the bottom furnace cavity. S4. Finally, there is the re-combustion and emission of flue gas. The flue gas generated by combustion rises from the high-combustion zone to the medium-combustion zone through the exhaust channel, and then flows into the low-combustion zone through the hollow part of the feed guide cone. It comes into contact with the downstream particulate fuel to increase the rising time of the flue gas, providing sufficient time for the flue gas to be re-combusted and for heat recovery. Finally, the flue gas is discharged through the exhaust pipe on the upper surface of the furnace body.

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