Self-shearing type anti-winding pneumatic injection feeding system for CFB (Circulating Fluidized Bed) boiler

Abstract

The invention discloses a self-shearing type anti-winding pneumatic jet feeding system for a CFB (circulating fluid bed) boiler. The system sequentially comprises an upper hopper, a differential bridge breaking device, a shear type spiral conveyor and a Venturi ejector in the material flow direction. According to the differential bridge breaking device, materials are torn to prevent bridging through a differential rotating roller shaft with hook teeth. A fixed cutter lining plate and a blade sawtooth cutting edge of the spiral conveyor form a movable and fixed shearing pair, the gap is 0.5-1.0 mm, and fibers are actively sheared off during conveying; and the variable-pitch section at the tail end compresses the material into a sealing material plug. The venturi ejector generates convergent high-speed jet flow through a Laval nozzle array, the material plug is blasted, scattered and sprayed into a hearth at a high speed, and meanwhile a pneumatic one-way valve is formed for preventing backfire. The four problems of winding, bridging, agglomeration and flue gas backflow of flexible fiber materials are integrally solved.

Description

Technical Field

[0001] This invention relates to the field of solid fuel feeding technology, specifically to a self-shearing anti-entanglement pneumatic injection feeding system for co-firing flexible fibrous fuels such as waste textiles in circulating fluidized bed (CFB) boilers. Background Technology

[0002] Circulating fluidized bed (CFB) combustion technology has become one of the mainstream technologies for the co-processing of municipal solid waste, sludge, and various industrial wastes in industrial boilers due to its comprehensive advantages, including wide fuel adaptability, high combustion efficiency, and good pollutant emission control. This is particularly true in textile industry clusters, such as Yong'an City in Fujian Province, where the amount of industrial waste textiles (including but not limited to chemical fiber scraps, cotton rags, and used clothing) generated by the local pillar industry is enormous. These wastes typically have high calorific values ​​(generally 3500-5000 kcal / kg or even higher). Direct landfill disposal not only occupies a large amount of land resources but also results in significant energy waste. Therefore, using them as solid recycled fuel (SRF) in CFB boilers in power plants to achieve energy utilization offers significant economic and environmental benefits, aligning with the national strategy for the resource utilization of solid waste.

[0003] Currently, the power and heat industry has developed mature technologies for conveying and feeding conventional "rigid pellet" fuels such as coal and shaped biomass pellets, forming a standardized equipment system represented by belt feeders, scraper feeders, and various screw feeders. However, waste textiles are typical "flexible fibrous" materials, and their physical properties (such as low bulk density, high tensile toughness, easy entanglement, and easy agglomeration) are significantly different from traditional rigid pellet fuels. Existing conveying and feeding systems designed for rigid materials generally face serious adaptability barriers when handling such flexible materials. With the increasing national policy requirements and enforcement efforts for the resource utilization of solid waste, how to achieve large-scale, continuous, stable, and reliable conveying and combustion of waste textiles in industrial boilers has become a prominent technical bottleneck restricting the promotion and industrial application of this technology.

[0004] Specifically, most existing feeding systems for co-firing waste in CFB boilers are either reused or simply modified from traditional biomass feeding equipment, lacking specific designs tailored to the unique characteristics of flexible fiber materials. This has led to a series of key technical deficiencies in practical applications:

[0005] Screw feeders, a common type of mechanical conveying equipment, rely on rotating screw blades and a central shaft to propel materials axially. When processing long, fibrous waste fabrics, the material easily adheres to and becomes entangled on the rotating central shaft. As the screw continues to rotate, this entanglement accumulates and tightens, eventually forming a dense, knot-like layer on the shaft. This not only severely reduces the effective material flow cross-section but also causes an exponential increase in the screw's frictional resistance. The direct consequence is frequent overload tripping of the drive motor, and in extreme cases, even serious equipment failure such as the reduction gearbox output shaft breaking.

[0006] To address the entanglement problem of shafted screw feeders, the industry has experimented with shaftless screw feeders. These feeders feature only thickened ribbon-shaped helical blades within their U-shaped troughs, eliminating the central shaft structure. Despite this removal, for high-strength synthetic fiber fabrics such as polyester and nylon, there will inevitably be assembly or operational gaps between the edges of the shaftless helical blades and the wear-resistant lining of the inner wall of the machine casing. Flexible fabrics are easily squeezed into or jammed in these tiny gaps. Once jamming occurs, the shaftless screw, lacking central support, is prone to elastic torsional deformation (i.e., the "spring effect") under torque, leading to equipment stagnation or even complete shutdown. Furthermore, due to its inherent non-rigid support characteristics, the shaftless screw structure struggles to operate stably at high speeds, limiting conveying capacity. More importantly, it cannot form a sufficiently dense and continuous material sealing layer at the end of the conveyor, failing to effectively prevent the backflow of high-temperature positive-pressure flue gas from the CFB boiler furnace to the upstream equipment, posing safety risks and operational disruptions.

[0007] Pneumatic conveying systems utilize airflow generated by a blower to transport pre-treated materials through closed pipelines. To meet the particle size requirements of pipeline pneumatic conveying, a high-precision fine crusher must be installed at the front end of the system to crush flexible fabrics to a very small size (e.g., <50mm). This crushing process is extremely energy-intensive, and the high-speed rotating blades wear out very quickly due to cutting tough fibers, resulting in high maintenance costs. Furthermore, the rotary feeder (commonly known as an "airlock"), a key air-locking device in pneumatic conveying systems, also faces a serious risk of entanglement and jamming when fibrous materials pass through. Simultaneously, at bends and other deflections in the conveying pipeline, fibrous materials easily become entangled and bridged, leading to pipeline blockage and poor system reliability.

[0008] Conventional hoppers and mechanical arch-breaking devices are used in this approach. Typically, a standard steel conical hopper is employed, supplemented by silo vibrators or air cannons to break up the bridging. Waste fabric fibers exhibit strong interlocking and entanglement tendencies. At the contraction outlet below the hopper, the material easily hooks together and forms stable "loose material arches," leading to feed interruptions. Traditional arch-breaking methods (such as silo vibration) are largely ineffective for such flexible, loose materials, and may even be counterproductive. The energy generated by vibration is not only insufficient to effectively break the flexible interlocking structure between fibers, but may also gradually compact and tamper the loose material during vibration, exacerbating the bridging stability—a phenomenon known as "the more it vibrates, the more compacted it becomes," ultimately causing a complete halt in feeding.

[0009] In summary, existing technical solutions each have inherent and insurmountable defects, lacking a dedicated feeding equipment that can systematically and integratedly solve the four key challenges unique to flexible fiber materials: "conveyance entanglement," "hopper bridging," "furnace agglomeration," and "high-temperature flue gas backflow." Developing such equipment is an urgent technological need to promote the large-scale, efficient, and clean energy utilization of low-value waste resources such as waste textiles in CFB boilers. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a self-shearing anti-entanglement pneumatic injection feeding system for CFB boilers that has a reasonable structure, reliable operation, can completely solve the problem of entanglement and blockage of flexible fibrous materials, and achieves efficient and safe injection feeding.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A self-shearing anti-winding pneumatic injection feeding system for CFB boilers includes, in sequence along the material conveying direction, an upper hopper assembly, a differential bridge breaking device, a shearing screw conveyor, and a Venturi injector.

[0013] The upper hopper assembly has an inverted conical structure;

[0014] The differential bridge breaking device is located at the throat outlet of the upper hopper assembly, and includes two horizontally parallel bridge breaking rollers. The two bridge breaking rollers are driven by a gear set to achieve differential rotation, and their surfaces are staggered with eagle beak-shaped hook teeth.

[0015] The shearing screw conveyor includes a split housing, a screw shaft disposed within the housing, and a drive device; at least one pair of elongated fixed blade liners are axially fixed on the inner wall of the housing; the screw shaft includes a shaft core and screw blades fixed to the shaft core, the outer edge of the screw blades being machined into continuous serrated cutting edges; the radial clearance δ between the serrated cutting edges and the fixed blade liners is controlled at 0.5~1.0mm; a variable pitch section is provided on the screw shaft near the outlet end, the pitch of the variable pitch section gradually decreasing along the discharge direction;

[0016] The Venturi ejector is connected to the outlet end of the shear screw conveyor and includes an outer annular equalizing air chamber and an inner Venturi channel. The annular equalizing air chamber is connected to a high-pressure air inlet pipe. At the throat of the Venturi channel, a Laval nozzle array is arranged around its inner wall with its axis forming an angle of 30° to 45° with the central channel. The Laval nozzle array is connected to the annular equalizing air chamber.

[0017] Furthermore, the inclination angle α of the inner wall of the upper hopper assembly is greater than 70°.

[0018] Furthermore, the serrated cutting edge of the spiral blade is provided with a tungsten carbide weld overlay layer.

[0019] Furthermore, the width of the tungsten carbide weld overlay is 15~25mm, and the weld overlay depth is 10~20mm.

[0020] Furthermore, the working surface of the fixed blade liner is machined with anti-slip textures or grooves.

[0021] Furthermore, the connection between the inner wall of the split housing and the fixed blade liner is provided with an arc transition.

[0022] Furthermore, the inner wall of the diffuser section of the Venturi injector is provided with a ceramic wear-resistant liner.

[0023] Furthermore, the speed ratio of the two bridge-breaking rollers in the differential bridge-breaking device is 1:1.2~1.8.

[0024] Furthermore, the gas source pressure of the high-pressure air inlet pipe is higher than the pressure in the dense phase zone of the CFB boiler furnace.

[0025] The advantages of this invention over the prior art are:

[0026] 1. Completely solves the fiber entanglement problem and ensures high operational reliability: This invention innovatively sets up a spiral blade (moving blade) with continuously serrated cutting edges and a fixed blade liner (fixed blade) on the inner wall of the casing in the screw conveyor, and strictly controls the radial gap between the two to 0.5~1.0mm, forming a precise "moving-fixed shearing pair". The conveying process is an active crushing process. Any flexible fiber attempting to entangle can be cut off instantly in the shearing gap, fundamentally transforming the "passive anti-entanglement" of traditional equipment into "active shearing", thereby completely eliminating the inherent problems of entanglement, jamming, and spring effect of shafted or shaftless screw conveyors, and significantly improving the long-term stability and reliability of the equipment.

[0027] 2. Effectively prevents bridging in the hopper and ensures continuous and stable feeding: Addressing the tendency of waste fabrics to form flexible "fluffy material arches," this invention innovatively employs a differential speed bridging device at the hopper throat. This device utilizes two bridging rollers with beak-shaped hooks rotating at different speeds (e.g., a speed ratio of 1:1.5) to forcibly tear and disperse the falling material clumps. This differential tearing action effectively disrupts the interlocking structure and flexible framework between fibers, fundamentally preventing bridging formation and ensuring a continuous and stable supply of material to the screw conveyor. This overcomes the drawback of traditional vibration bridging methods, which tend to "make the material more compacted with vibration."

[0028] 3. Significantly Improved Combustion Efficiency and Fuel Adaptability: This invention innovatively combines a shear-type screw conveyor with a Venturi injector. The variable-pitch section at the end of the screw compresses the material into a dense "bolt," which then enters the throat of the Venturi injector. A high-speed jet converging towards the center is generated by an annular equalizing air chamber and an inwardly inclined (30°~45°) Laval nozzle array, instantly "exploding" and breaking the dense bolt into a loose, flocculent fibrous cloud, which is then injected into the furnace at high speed. This process greatly increases the specific surface area of ​​the fuel, allowing it to fully and rapidly contact the high-temperature furnace flue gas, achieving instantaneous ignition and efficient suspension combustion, avoiding the risks of incomplete combustion, uneven furnace temperature, and coking caused by fuel clumping and settling.

[0029] 4. Provides dual safety protection to effectively prevent backflow of high-temperature flue gas: This invention constructs a dual-sealed backfire prevention barrier combining physical and pneumatic methods. The first barrier is provided by the dense "material plug" formed by the variable pitch section at the end of the screw conveyor, serving as a reliable physical seal to block flue gas; the second barrier is constituted by the "pneumatic one-way valve" formed by the high-speed unidirectional jet of the Venturi injector. These two barriers work together to effectively prevent backflow of high-temperature positive pressure flue gas in the furnace, even when boiler operating conditions fluctuate, protecting upstream equipment and operational safety, and solving the safety hazards caused by poor sealing of equipment such as shaftless screw conveyors. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a longitudinal cross-sectional view of the overall structure of the feeding system of the present invention.

[0032] Figure 2 This is an exploded view of the core components of the shear screw conveyor in this invention.

[0033] Figure 3 This is a three-dimensional partial cross-sectional schematic diagram of the Chinese-made mound injector of the present invention.

[0034] Figure 4 for Figure 1 A schematic diagram of the cross-section of a shear screw conveyor with section AA in the middle.

[0035] Figure 5 for Figure 4 A magnified view of the serrated cutting edge of the medium-sized helical blade.

[0036] In the diagram: 100 - Upper hopper assembly, 200 - Differential speed bridge breaking device, 201, 202 - Bridge breaking rollers, 300 - Shearing screw conveyor, 301 - Drive motor, 302 - Reducer, 303 - Screw shaft, 310 - Split housing, 320 - Fixed blade liner, 331 - Shaft core, 332 - Spiral blade, 3321 - Serrated cutting edge, 3322 - Tungsten carbide weld overlay, 340 - Variable pitch section, 400 - Venturi injector, 410 - Annular equalizing air chamber, 411 - Air inlet pipe, 420 - Laval nozzle array, 430 - Ceramic wear-resistant liner, 500 - Boiler furnace interface. Detailed Implementation

[0037] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limiting purposes, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details.

[0038] This invention addresses the engineering bottlenecks in the co-firing of flexible fibrous fuels such as waste fabrics in circulating fluidized bed (CFB) boilers, providing an integrated solution. This solution systematically solves four major problems commonly encountered in existing technologies when handling such materials: entanglement and jamming, hopper bridging, furnace agglomeration, and flue gas backflow. It ensures large-scale, continuous, stable, safe, and efficient fuel delivery and combustion.

[0039] It was applied to a 130t / h circulating fluidized bed boiler in a thermal power plant to co-fire industrial waste fabrics such as chemical fiber scraps and cotton rags produced by local textile enterprises.

[0040] like Figure 1 As shown, the feeding system of the present invention includes, in sequence along the material flow direction, an upper hopper assembly 100, a differential speed bridge-breaking device 200, a shear-type screw conveyor 300, and a Venturi ejector 400. Waste fabric is fed into the hopper by the loading equipment, and after being successively subjected to bridge breaking, shearing, compression, and jet dispersion, it finally enters the boiler furnace in a high-speed, fluffy state.

[0041] like Figure 1 As shown, the upper hopper assembly 100 adopts an inverted conical steel structure design, whose main function is to temporarily store and guide materials. A key parameter is its inner wall inclination angle α, which is set to 75°. This angle is significantly larger than the design angle of conventional hoppers (typically 45°-60°), and clearly greater than 70°. This large inclination angle is a targeted measure taken to address the high coefficient of friction and poor flowability of flexible fabric surfaces. Its purpose is to maximize the use of the material's own gravity, assisting it in sliding downwards, significantly reducing friction and adhesion between the material and the wall surface, and minimizing the risk of "hanging" or "retention" in the upper section of the hopper from the source.

[0042] A differential speed bridging device 200 is installed at the throat outlet of the hopper. This device, directly installed at the throat outlet of the upper hopper assembly 100, is key to solving the problem of "loose material arching." The differential speed bridging device 200 comprises two horizontally parallel bridging rollers 201 and 202. Multiple beak-shaped hooks are staggered along the axial and circumferential directions on the roller surfaces, designed to easily hook and tear fabric. The two rollers are driven by a sealed gearbox (illustrated in the figure, internal structure not shown) to achieve differential rotation. In this embodiment, the speed ratio of the two rollers is set to 1:1.5. For example, the front roller 201 rotates at 20 r / min, and the rear roller 202 rotates at 30 r / min. When the falling waste fabric clump passes between the two rollers, the differentially rotating beak-shaped hooks act like two "tearers" at different speeds, generating strong tearing and shearing effects on the material. This action effectively disrupts the flexible structure formed by the interlocking of flexible fibers, breaking up large clumps of material and fundamentally preventing the formation of stable "bridging" phenomena at the hopper's contraction throat that could interrupt material flow. This contrasts sharply with the negative effect of traditional silo vibrators, which tend to "make the material more compacted with each vibration," achieving forced and efficient arch breaking.

[0043] The shear screw conveyor 300 is the core of this system. For example... Figure 1 , Figure 2 , Figure 4As shown, its function is not limited to conveying; it also integrates active anti-winding and primary sealing. It includes a split housing 310, a screw shaft 303, a drive motor 301, and a reducer 302. The split housing 310 adopts a split design with upper and lower parts connected by flanges, greatly facilitating the installation, maintenance, and replacement of the internal screw shaft and fixed blade liners. On both sides of the inner wall of the split housing 310 (and possibly more sides depending on the conveying capacity and material characteristics), long strip-shaped fixed blade liners 320 are axially fixed and bolted in place. The surface of the liners is machined with raised anti-slip textures to increase friction with the material and prevent it from slipping with the blades. Notably, the connection between the inner wall of the housing and the fixed blade liners 320 uses a rounded R transition; this detail avoids material accumulation and fiber snagging caused by sharp edges.

[0044] The helical shaft 303 consists of a shaft core 331 and helical blades 332 welded to the shaft core. The helical blades 332 are made of high-chromium cast iron. The outer edge of the helical blades 332 is not smooth, but is machined into continuous, sharp serrated cutting edges 3321 (see...). Figure 5 The key point is, such as Figure 4 As shown, the radial clearance δ between the highest point of the serrated cutting edge 3321 of the spiral blade 332 and the working surface of the fixed blade liner 320 is precisely machined and adjusted to 0.8 mm (within the range of 0.5~1.0 mm). This tiny clearance constitutes the shearing pair between the "moving blade" (blade serrations) and the "fixed blade" (liner). When the pre-torn fabric material enters the screw conveyor and is propelled forward, any long fiber that attempts to wrap around the shaft core 331, or is thrown towards the inner wall of the casing by the blade, will inevitably enter the tiny clearance between the blade serrations and the fixed blade liner. The rotating serrated cutting edge 3321, like scissors, engages with the fixed edge of the fixed blade liner to actively shear the fiber. The conveying process is a continuous crushing process, transforming the existing "passive anti-tangling" (such as shaftless spirals) into "active shearing," fundamentally eliminating the possibility of tangling, wrapping around the shaft core, or jamming the equipment.

[0045] To ensure the long-term effectiveness of the shearing edge, such as Figure 5 As shown, to cope with the wear and tear of high-strength synthetic fibers (such as polyester), such as... Figure 5As shown, a tungsten carbide overlay layer 3322, approximately 20 mm wide and 15 mm deep, is welded onto the serrated cutting edge 3321 of the spiral blade 332. This layer has extremely high hardness, ensuring that the cutting edge does not dull during long-term shearing. Furthermore, a variable pitch section 340 is designed within approximately 1 meter of the spiral shaft 303 near the outlet end. Its pitch gradually decreases linearly from 300 mm at the standard inlet end to 150 mm at the outlet end. As the pitch decreases, the axial compressive force on the material gradually increases. Loose, fluffy fabric is forcibly compressed during this process, ultimately forming a dense, continuous "material plug" at the spiral outlet. This dense material plug not only facilitates subsequent pneumatic conveying but, more importantly, acts as a reliable physical sealing wall, effectively preventing the high-temperature positive-pressure flue gas (approximately 8-10 kPa pressure in the dense phase zone of the furnace in this embodiment) from flowing back into the conveyor. This is the first line of defense.

[0046] like Figure 1 and Figure 3 As shown, the Venturi injector 400 is connected via a flange between the outlet of the screw conveyor 300 and the boiler furnace wall interface 500, serving the dual functions of final fuel dispersion into the furnace and secondary sealing. The boiler furnace wall interface 500 is located on the boiler furnace wall, and the inner side of the boiler furnace wall is coated with a refractory castable coating. Externally, there is an annular equalizing air chamber 410, which receives high-pressure air (usually primary air or air supplied by a Roots blower, with a pressure higher than the pressure in the dense phase zone of the furnace) through an inlet pipe 411. Inside the injector, at the throat of the Venturi flow channel, a ring of 8-12 Laval nozzles 420 is evenly arranged, with the angle β between their axes and the central flow channel axis ranging from 30° to 45°, preferably 35°.

[0047] After the high-pressure air stabilizes within the annular equalizing chamber 410, it is simultaneously ejected at supersonic speed from all Laval nozzles. Due to the inward tilt of the nozzles, these high-speed jets converge and collide with each other along the centerline of the ejector, forming a highly turbulent, high-energy "cutting and bursting zone." When the dense "bulks" pushed out by the shear screw conveyor 300 enter this zone, they are instantly and violently impacted, torn, and burst apart by the high-speed converging airflow, reverting to a fluffy, flocculent fibrous cloud. This process greatly increases the specific surface area of ​​the fuel particles, allowing them to fully and rapidly contact the high-temperature flue gas after entering the furnace, achieving instantaneous ignition and efficient suspension combustion. This avoids problems such as incomplete combustion, uneven temperature distribution within the furnace, or grate coking caused by clumping and falling.

[0048] Simultaneously, the high-speed, unidirectional (towards the furnace) jet generated by the Laval nozzle array 420 forms a continuous high-speed air curtain at the injector throat. This air curtain constitutes an effective "pneumatic check valve," serving as a second barrier to prevent backflow of flue gas from the furnace. Even if a very small amount of flue gas attempts to flow backward, it will be blocked by this powerful forward airflow and dispersed back into the furnace.

[0049] Because the diffuser section of the ejector is subjected to continuous scouring by high-speed gas-solid two-phase flow, its inner wall is lined with a ceramic wear-resistant lining 430 to significantly extend the service life of the equipment.

[0050] The system works as follows:

[0051] Waste textile scraps are first fed into the upper hopper assembly 100, where they smoothly slide down to the throat using the steeply inclined inner wall. At the throat, the hooks of the differential speed bridge-breaking device 200 forcibly tear the scrap, breaking the material arch and ensuring continuous feeding. The material then enters the shear screw conveyor 300, where any attempt at fiber entanglement is actively cut off by the shearing pair formed by the blade saw teeth and the fixed blade liner. At the end of the conveyor, the material is compressed into a dense plug by the variable pitch section 340. Once pushed out, this plug immediately enters the throat of the Venturi injector 400, where it is abruptly broken and dispersed into a fluffy fiber cloud by the high-speed converging airflow from the Laval nozzle array. Accelerated by the airflow, it is then injected at high speed into the CFB boiler furnace, achieving efficient and clean combustion. The entire system, through the organic integration of four technologies—differential speed bridge breaking, dynamic and fixed shearing, plug sealing, and pneumatic blasting—forms a complete, reliable, and efficient feeding solution specifically designed for flexible fibrous fuels.

[0052] This invention organically integrates differential forced arch breaking, spiral dynamic and fixed shearing, material plug sealing and pneumatic blasting dispersion technology to form a complete feeding solution specifically designed for processing flexible fibrous fuels, which has extremely high engineering application value.

[0053] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0054] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A self-shearing anti-winding pneumatic injection feeding system for a CFB boiler, characterized in that, Along the material conveying direction, it includes, in sequence, an upper hopper assembly (100), a differential bridge breaking device (200), a shear screw conveyor (300), and a Venturi ejector (400). The upper hopper assembly (100) has an inverted conical structure; The differential bridge breaking device (200) is located at the throat outlet of the upper hopper assembly (100), and includes two horizontally parallel bridge breaking rollers (201, 202). The two bridge breaking rollers (201, 202) are driven by a gear set to achieve differential rotation, and their surfaces are staggered with eagle beak-shaped hook teeth. The shear screw conveyor (300) includes a split housing (310), a screw shaft (303) disposed within the housing, and a drive device; at least one pair of elongated fixed blade liners (320) are fixedly disposed axially on the inner wall of the housing (310); the screw shaft (303) includes a shaft core (331) and screw blades (332) fixed to the shaft core, the outer edge of the screw blades (332) being machined into continuous serrated cutting edges (3321); the radial clearance δ between the serrated cutting edges (3321) and the fixed blade liners (320) is controlled at 0.5~1.0mm; a variable pitch section (340) is provided on the screw shaft (303) near the outlet end, the pitch of the variable pitch section (340) gradually decreasing along the discharge direction; The Venturi ejector (400) is connected to the outlet end of the shear screw conveyor (300), and includes an outer annular equalizing air chamber (410) and an inner Venturi channel; the annular equalizing air chamber (410) is connected to a high-pressure air inlet pipe (411); at the throat of the Venturi channel, a ring of Laval nozzle array (420) with its axis at an angle of 30° to 45° to the central channel is provided around its inner wall, and the Laval nozzle array (420) is connected to the annular equalizing air chamber (410).

2. The self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 1, characterized in that, The inclination angle α of the inner wall of the upper hopper assembly (100) is greater than 70°.

3. The self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 1, characterized in that, The spiral blade (332) has a tungsten carbide overlay layer (3322) at the serrated cutting edge (3321).

4. A self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 3, characterized in that, The width of the tungsten carbide overlay (3322) is 15~25mm, and the overlay depth is 10~20mm.

5. A self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 1, characterized in that, The working surface of the fixed blade liner (320) is machined with anti-slip textures or grooves.

6. A self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 1, characterized in that, The connection between the inner wall of the split housing (310) and the fixed blade liner (320) is provided with an arc transition.

7. A self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 1, characterized in that, The diffuser section of the Venturi injector (400) is lined with a ceramic wear-resistant liner (430).

8. A self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 1, characterized in that, The speed ratio of the two bridge-breaking rollers (201, 202) in the differential bridge-breaking device (200) is 1:1.2~1.

8.

9. A self-shearing anti-winding pneumatic injection feeding system for a CFB boiler according to claim 1, characterized in that, The gas source pressure of the high-pressure air inlet pipe (411) is higher than the pressure in the dense phase zone of the CFB boiler furnace.

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