A biomass feeding system for direct-fired coupled coal-fired power generation

Abstract

The application discloses a kind of biomass feeding system for direct-fired coupling coal-fired generating unit, including biomass powder bin, its lower discharge section uses shelter structure;Along the bottom of shelter structure and side-by-side arrangement multiple material taking screw, each material taking screw is respectively configured with independent variable frequency driving device;The discharge outlet of material taking screw is provided with weighing conveyor device below, for receiving material and carrying out continuous weighing;The discharge outlet of weighing conveyor device is provided with double-stage air lock below;The discharge outlet of double-stage air lock is provided with pneumatic conveying system below;Double-stage air lock and biomass powder bin are all communicated with dust removal system.The application is by shelter powder bin bottom multiple screw variable frequency forced material taking, cooperate with weighing continuous metering, double-stage air lock air-locked feeding and dust removal system negative pressure dust prevention, solve the technical problems of millimeter level, higher moisture biomass powder particle bridging, blockage, jam and powder, realize the continuous, stable and long-period operation of biomass powder particle feeding.

Description

Technical Field

[0001] This invention relates to the field of direct biomass co-firing technology for coal-fired power units, and in particular to a biomass feeding system for direct-fired coupled coal-fired power generation units. Background Technology

[0002] This invention relates to the field of direct co-firing of biomass in coal-fired power units, specifically to a biomass feeding system for direct-fired coupled coal-fired power generation units, and is particularly suitable for a continuous, stable, long-cycle feeding system and method for millimeter-sized, high-moisture biomass powder particles.

[0003] In recent years, biomass co-firing has become an effective way to reduce carbon emissions from coal-fired power plants. Biomass direct combustion coupled with coal-fired power generation is currently in the early demonstration stage in my country, and many technologies are not yet mature.

[0004] In biomass co-firing systems, the continuous, stable, and long-term operation of the biomass powder feeding system is crucial. Frequent jamming, blockages, or bridging in the feeding system leading to system shutdowns will directly cause significant load fluctuations in coal-fired units. This will not only trigger grid inspections but also affect the stability and safety of unit operation, especially during deep peak shaving phases, where a sudden disconnection of the biomass system can cause unit tripping. Therefore, the feeding system in a biomass co-firing system must be able to operate continuously and stably. While millimeter-sized biomass powder is sufficient for in-furnace combustion, millimeter-sized biomass powder has poorer flowability than micron-sized powder, making it more prone to jamming and bridging during feeding. Given that micron-sized biomass powder consumes more energy and has lower production capacity, millimeter-sized biomass powder is still chosen in the design of biomass co-firing systems; otherwise, the project will be uneconomical or even result in losses. The lower the moisture content of biomass powder, the less likely it is to bridging during the feeding process. However, low-moisture biomass powder needs to be dried, which increases costs and makes the overall economic efficiency of the project poor. Therefore, in actual production, the moisture content of biomass powder is at a relatively high level, such as around 20%. Biomass powder with 20% moisture content is prone to bridging and blockage after being piled up in the powder silo, resulting in poor material discharge.

[0005] Therefore, this patent proposes a biomass feeding system and method for direct-fired coupled coal-fired power generation, which can achieve continuous, stable, and long-cycle feeding of millimeter-sized, high-moisture biomass powder particles. Summary of the Invention

[0006] The present invention aims to at least partially solve one of the technical problems in the related art.

[0007] To achieve the above objectives, the present invention proposes a biomass feeding system for direct-fired coupled coal-fired power generation, including a biomass powder silo, wherein the lower discharge section of the biomass powder silo adopts a container structure.

[0008] Multiple material handling screws are arranged side by side along the bottom of the container structure, and each material handling screw is equipped with an independent frequency conversion drive device; a weighing and conveying device is set below the discharge port of the material handling screws to receive materials and perform continuous weighing. A double-stage airlock is installed below the discharge port of the weighing and conveying device; a pneumatic conveying system is installed below the discharge port of the double-stage airlock; and a dust removal system is connected to both the double-stage airlock and the biomass powder silo.

[0009] This invention utilizes a modular biomass powder silo structure at the bottom, allowing materials to fall vertically and preventing bridging and arching caused by lateral compression in conical structures. Multiple independently variable frequency feeding screws are arranged side-by-side at the bottom of the silo, flexibly adjusting the speed of each screw according to the material distribution in different areas of the silo. This actively maintains a uniform material surface, preventing material slippage and re-compression caused by excessively fast or slow feeding in certain areas, achieving continuous and uniform forced feeding. The collected material is precisely and continuously weighed and metered by a weighing and conveying device before entering a two-stage airlock. The two-stage airlock effectively locks the air while feeding the material into a high-positive-pressure pneumatic conveying system. Simultaneously, a dust removal system connected to the biomass powder silo and the two-stage airlock maintains a negative pressure environment, preventing dust spillage and ensuring clean production. Therefore, the entire system achieves continuous, stable, and long-cycle feeding of millimeter-level, high-moisture biomass powder particles.

[0010] Optionally, the two-stage airlock includes an air extraction chamber, an upper airlock, and a lower airlock arranged sequentially from top to bottom, with a pneumatic slide gate between the air extraction chamber and the upper airlock.

[0011] Furthermore, the pneumatic conveying system includes a mixer connected to the outlet of the lower-level airlock, and the outlet of the mixer is connected to a biomass powder conveying pipe; the biomass powder conveying pipe conveys the mixed material to the boiler.

[0012] Furthermore, the dust removal system includes a dust collector and a dust removal fan. The dust collector is connected to the biomass powder silo and the exhaust chamber by pipes. The dust removal fan is connected to the dust collector to supply negative pressure airflow to the dust collector.

[0013] Furthermore, multiple vibrating devices are arranged at equal intervals on the side wall of the biomass powder bin.

[0014] Furthermore, at least one arch-breaking device is arranged in the central area of ​​the biomass powder bin.

[0015] Furthermore, the weighing and conveying device is a belt weighing machine, and a blockage switch is provided at the end of the belt weighing machine near the two-stage airlock to provide an early warning of the material level of the two-stage airlock.

[0016] Furthermore, both the upper-stage airlock and the lower-stage airlock are impeller-driven powder feeding structures.

[0017] Furthermore, multiple material-collecting screws cover the entire bottom cross-section of the container structure, allowing the material to fall vertically and be forcibly removed by the material-collecting screws.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

[0019] The beneficial effects of this invention are: 1. This invention utilizes a modular biomass powder silo structure at the bottom, allowing materials to fall vertically and preventing bridging and arching caused by lateral compression in conical structures. Multiple independently variable frequency feeding screws are arranged side-by-side at the bottom of the silo, allowing for flexible adjustment of the screw speed based on material distribution within the silo. This actively maintains a uniform material surface, preventing material slippage and re-compression due to excessively fast or slow feeding in certain areas, achieving continuous and uniform forced feeding. The collected material is precisely and continuously weighed and metered by a weighing and conveying device before entering a two-stage airlock. The two-stage airlock effectively locks the air while feeding the material into a high-positive-pressure pneumatic conveying system. Simultaneously, a dust removal system connects the biomass powder silo and the two-stage airlock, maintaining a negative pressure environment to prevent dust spillage and ensure clean production. Overall, this invention achieves continuous, stable, and long-cycle feeding of millimeter-level, high-moisture biomass powder particles. 2. This invention, through the combined configuration of a belt weighing machine, an extraction chamber, and a two-stage airlock, achieves accurate quantitative feeding of millimeter-sized biomass powder particles, effective airlocking of high-positive-pressure pneumatic conveying, and smooth connection of the system's material flow. The belt weighing machine replaces the traditional rotor scale, fundamentally eliminating the risk of millimeter-sized non-spherical particles being squeezed and jammed in the rotor gap, thus achieving continuous and stable weighing and metering. In the two-stage airlock, the lower stage airlock is dedicated to feeding the high-positive-pressure mixer, while the upper stage airlock is dedicated to airlocking. This functional grading ensures that each airlock is effectively utilized. A conventional impeller clearance can be used, which not only ensures long-term trouble-free impeller rotation for feeding, but also effectively reduces the pressure of backflow air. The air extraction chamber is set between the weighing machine and the two-stage airlock. On the one hand, it acts as a buffer to smooth out fluctuations in the instantaneous feed rate and prevent the material from being squeezed and stuck in the channel. On the other hand, it effectively eliminates residual backflow air through negative pressure suction, ensuring that the equipment operates in a clean environment. It solves the contradictions of poor feeding, inaccurate weighing, and the inability to balance airlock and feeding in traditional solutions, and realizes continuous, stable and long-cycle operation of the system as a whole. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the structure of a biomass feeding system for direct-fired coupled coal-fired power generation unit according to the present invention.

[0021] Explanation of reference numerals in the attached figures: 1. Biomass powder silo; 2. Vibrator; 3. Arch breaking device; 4. Feeding screw; 5. Belt weigher; 6. Blocking switch; 7. Air extraction chamber; 8. Pneumatic slide gate; 9. Upper airlock; 10. Lower airlock; 11. Mixer; 12. Biomass powder pipe; 13. Dust collector; 14. Dust removal fan. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] This invention proposes a biomass feeding system for direct-fired coupled coal-fired power generation units, as described below. Figure 1 Please provide a detailed explanation.

[0024] A biomass feeding system for direct-fired coupled coal-fired power generation includes a biomass powder silo 1, the lower discharge section of which adopts a container structure. Multiple material handling screws 4 are arranged side by side along the bottom of the container structure. Each material handling screw 4 is equipped with an independent frequency conversion drive device. A weighing and conveying device is installed below the discharge port of the material handling screw 4 to receive materials and perform continuous weighing. A double-stage airlock is installed below the discharge port of the weighing and conveying device; a pneumatic conveying system is installed below the discharge port of the double-stage airlock; and a dust removal system is connected to both the double-stage airlock and the biomass powder silo 1.

[0025] This invention utilizes a modular biomass powder silo 1 with a container-like structure at the bottom, allowing materials to fall vertically and preventing bridging and arching caused by lateral compression in conical structures. Multiple independently variable frequency feeding screws 4 are arranged side-by-side at the bottom of the container, allowing for flexible adjustment of the rotation speed of each screw 4 according to the material distribution in different areas of the silo. This actively maintains a uniform material surface, preventing material slippage and re-compression caused by excessively fast or slow feeding in certain areas, achieving continuous and uniform forced feeding. The collected material is precisely and continuously weighed and metered by a weighing and conveying device before entering a two-stage airlock. The two-stage airlock effectively locks the air while feeding the material into a high-positive-pressure pneumatic conveying system. Simultaneously, a dust removal system connected to the biomass powder silo 1 and the two-stage airlock maintains a negative pressure environment, preventing dust spillage and ensuring clean production. Therefore, the entire system achieves continuous, stable, and long-cycle feeding of millimeter-level, high-moisture biomass powder particles.

[0026] In some embodiments, the two-stage airlock includes an extraction chamber 7, an upper airlock 9, and a lower airlock 10 arranged sequentially from top to bottom, with a pneumatic gate 8 between the extraction chamber 7 and the upper airlock 9. By setting the extraction chamber 7, a buffer space is formed between the weighing and conveying device and the upper and lower airlocks 10, which can temporarily store the instantaneous fluctuations in the amount of material, effectively suppress the mismatch in the feeding amount between the feeding screw 4 and the lower airlock 10, and prevent the material from being squeezed and agglomerated due to excessive accumulation in the connecting channel. The upper airlock 9 is dedicated to the airlock function, attenuating the high-pressure airflow that backflows from the pneumatic conveying system, while the lower airlock 10 is mainly responsible for feeding the mixer 11 at a uniform speed. After the functions of the two are decoupled, both can use conventional impeller gaps, which not only ensures the smooth and trouble-free rotation of the impeller for a long time, but also achieves a good airlock effect and greatly reduces the amount of backflow. The pneumatic gate 8 facilitates the quick isolation of the upper and lower airlocks 10 during maintenance.

[0027] In some embodiments, the pneumatic conveying system includes a mixer 11 connected to the outlet of the lower-stage airlock 10, and a biomass powder conveying pipe connected to the outlet of the mixer 11; the biomass powder conveying pipe conveys the mixed material to the boiler. After the material is quantitatively fed into the mixer 11 by the lower-stage airlock 10, it is fully mixed and fluidized with the conveying air source, and is stably pneumatically conveyed to the boiler furnace through the biomass powder conveying pipe, ensuring the continuity and stability of the co-firing process.

[0028] In some embodiments, the dust removal system includes a dust collector 13 and a dust collector fan 14. The dust collector 13 is connected to the biomass powder silo 1 and the extraction chamber 7 by pipes. The dust collector fan is connected to the dust collector 13 to supply negative pressure airflow to the dust collector 13. Through continuous suction by the dust collector fan 14, both the biomass powder silo 1 and the extraction chamber 7 are kept under negative pressure. This not only removes the dust rising during the feeding and conveying process of the powder silo, suppressing dust emission from the powder silo, but more importantly, it can promptly remove the air and dust that have flowed back into the extraction chamber 7 through the double-stage airlock, fundamentally eliminating the phenomenon of dust leakage from equipment gaps and ensuring the cleanliness of the workshop environment and operational safety.

[0029] In some embodiments, multiple vibrating devices are arranged at equal intervals on the side wall of the biomass powder silo 1. The regular vibration of the vibrating devices can disturb the silo wall, destroy the adhesion between the material and the wall surface and the bridging structure between the materials, and help the material slide smoothly, further improving the smoothness of the powder silo discharge.

[0030] In some embodiments, at least one arch-breaking device 3 is arranged in the central region of the biomass powder silo 1. The arch-breaking device 3 includes a drive shaft disposed within the biomass powder silo 1, parallel to the vertical axis of the biomass powder silo 1, and arch-breaking blades fixedly disposed outside the drive shaft. One end of the drive shaft facing the top wall of the biomass powder silo 1 is connected to a drive motor that provides power for the rotation of the drive shaft. The drive shaft is sealed and rotatably connected to the top wall of the biomass powder silo 1. The arch-breaking device 3 acts directly on the interior of the material accumulation area, actively breaking down existing or soon-to-be-formed material arches from within. Working in conjunction with the rapping equipment, it effectively eliminates the risk of arching and blockage, ensuring continuous material flow.

[0031] In some embodiments, the weighing and conveying device is a belt weigher 5, where the material is in a loose state on the conveyor belt and weighed during the conveying process. A blockage switch 6 is installed near the end of the belt weigher 5 close to the double-stage airlock to provide early warning of the material level in the double-stage airlock. By using the belt weigher 5, its wide conveyor belt allows millimeter-sized biomass powder particles to be conveyed in a loose state, fundamentally avoiding weighing failures caused by particle compression and jamming in traditional rotor scales, thus achieving continuous and stable online weighing and metering. The blockage switch 6 at the discharge end can monitor the material flow status in real time, issuing an early warning if the downstream material level is abnormal or a blockage trend occurs, facilitating timely intervention by operators to prevent the blockage from worsening.

[0032] In some embodiments, both the upper-stage airlock 9 and the lower-stage airlock 10 are impeller-driven powder feeding structures. Employing a mature impeller-driven powder feeding structure, the rotating impeller and the housing work together to achieve quantitative material delivery and intermittent airlocking. The structure is reliable, easy to maintain, and can adapt to the feeding requirements of millimeter-sized biomass powder particles, ensuring stable long-term operation.

[0033] The system employs a combination of belt weigher 5, extraction chamber 7, and two-stage airlock, achieving accurate quantitative feeding of millimeter-sized biomass powder, effective airlocking in high-positive-pressure pneumatic conveying, and smooth connection of the system's material flow. The belt weigher 5 replaces the traditional rotor scale, fundamentally eliminating the risk of millimeter-sized non-spherical particles being squeezed and jammed in the rotor gap, thus achieving continuous and stable weighing and metering. In the two-stage airlock system, the lower-stage airlock 10 is dedicated to feeding the high-positive-pressure mixer 11, while the upper-stage airlock 9 is dedicated to airlocking. This functional grading ensures that each airlock... All air chambers can use conventional impeller clearances, which not only ensures long-term trouble-free impeller rotation for feeding, but also effectively reduces backflow pressure. The air extraction chamber 7 is located between the weighing machine and the two-stage air lock. On the one hand, it acts as a buffer to smooth out fluctuations in the instantaneous feed rate and prevent materials from being squeezed and stuck in the channel. On the other hand, it effectively eliminates residual backflow through negative pressure suction, ensuring that the equipment operates in a clean environment. This solves the contradictions of poor feeding, inaccurate weighing, and the inability to balance air lock and feeding in traditional solutions, and realizes continuous, stable, and long-cycle operation of the entire system.

[0034] In some embodiments, multiple material-collecting screws 4 cover the entire bottom cross-section of the container structure, allowing materials to fall vertically and be forcibly removed by the screws 4. By covering the entire bottom of the container with material-collecting screws 4, dead zones are eliminated. After the material falls vertically onto the screws under gravity, it is forcibly conveyed to the discharge port. With independent frequency conversion adjustment of each screw, uniform and synchronous removal of materials from all areas within the container can be achieved, avoiding material compression and arching caused by local stagnation, thus ensuring continuous and smooth material collection.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0038] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0039] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A biomass feeding system for direct-fired coupled coal-fired power generation units, characterized in that, Includes a biomass powder silo, wherein the lower discharge section of the biomass powder silo adopts a container structure; Multiple material handling screws are arranged side by side along the bottom of the container structure, and each material handling screw is equipped with an independent frequency conversion drive device; a weighing and conveying device is set below the discharge port of the material handling screws to receive materials and perform continuous weighing. A double-stage airlock is installed below the discharge port of the weighing and conveying device; a pneumatic conveying system is installed below the discharge port of the double-stage airlock; and a dust removal system is connected to both the double-stage airlock and the biomass powder silo.

2. The biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 1, characterized in that, The dual-stage airlock includes an air extraction chamber, an upper airlock, and a lower airlock arranged sequentially from top to bottom, with a pneumatic slide door between the air extraction chamber and the upper airlock.

3. A biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 2, characterized in that, The pneumatic conveying system includes a mixer connected to the outlet of the lower-level airlock, and the outlet of the mixer is connected to a biomass powder conveying pipe; the biomass powder conveying pipe conveys the mixed material to the boiler.

4. A biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 2, characterized in that, The dust removal system includes a dust collector and a dust removal fan. The dust collector is connected to the biomass powder silo and the exhaust chamber by pipes. The dust removal fan is connected to the dust collector to supply negative pressure airflow to the dust collector.

5. A biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 1, characterized in that, Multiple vibrating devices are arranged at equal intervals on the side wall of the biomass powder silo.

6. A biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 1, characterized in that, At least one arch-breaking device is arranged in the central area of ​​the biomass powder bin.

7. A biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 1, characterized in that, The weighing and conveying device is a belt weighing machine. A blockage switch is provided at one end of the belt weighing machine near the double-stage airlock to provide an early warning of the material level of the double-stage airlock.

8. A biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 2, characterized in that, Both the upper-stage airlock and the lower-stage airlock have impeller-feeding structures.

9. A biomass feeding system for direct-fired coupled coal-fired power generation as described in claim 1, characterized in that, Multiple material-collecting screws cover the entire bottom section of the container structure, allowing materials to fall vertically and be forcibly removed by the screws.

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