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CN-121993785-A - Self-shearing type winding-preventing pneumatic jet feeding system for CFB boiler

CN121993785ACN 121993785 ACN121993785 ACN 121993785ACN-121993785-A

Abstract

The invention discloses a self-shearing type winding-preventing pneumatic jet feeding system for a CFB boiler. The system sequentially comprises an upper hopper, a differential bridge breaking device, a shearing type screw conveyor and a Venturi ejector along the material flow direction. The differential bridge breaking device utilizes the differential rotation hooked tooth roller shaft to tear materials to prevent bridging. The fixed knife lining board and the blade saw tooth edge of the screw conveyer form a fixed movable shearing pair, the clearance is 0.5-1.0 mm, the fiber is actively sheared during conveying, and the material is compressed into a sealing material plug by the tail end variable pitch section. The venturi ejector generates converging high-speed jet flow through the Laval nozzle array, bursts and breaks up the material plug and sprays the material plug into the hearth at high speed, and meanwhile, the pneumatic check valve tempering prevention device is formed. The invention integrally solves four problems of winding, bridging, agglomeration and smoke reverse channeling of flexible fiber materials.

Inventors

  • GONG XUN
  • LI BOWEN

Assignees

  • 华中科技大学

Dates

Publication Date
20260508
Application Date
20260326

Claims (9)

  1. 1. A self-shearing type anti-winding pneumatic jet feeding system for a CFB boiler, which is characterized by sequentially comprising an upper hopper assembly (100), a differential bridge breaking device (200), a shearing type screw conveyor (300) and a venturi jet (400) along the material conveying direction; The upper hopper assembly (100) is of an inverted cone structure; The differential bridge breaking device (200) is arranged at the throat outlet of the upper hopper assembly (100) and comprises two bridge breaking roll shafts (201, 202) which are horizontally arranged in parallel, the two bridge breaking roll shafts (201, 202) are driven by a gear set to realize differential rotation, and the surfaces of the bridge breaking roll shafts are provided with chickpea-shaped hook teeth in a staggered manner; The shearing type spiral conveyor (300) comprises a split type machine shell (310), a spiral shaft (303) and a driving device, wherein the spiral shaft (303) is arranged in the machine shell, at least one pair of strip-shaped fixed cutter lining plates (320) are fixedly arranged on the inner wall of the machine shell (310) along the axial direction, the spiral shaft (303) comprises a shaft core (331) and a spiral blade (332) fixed on the shaft core, the outer edge of the spiral blade (332) is processed into a continuous sawtooth cutting edge (3321), the radial gap delta between the sawtooth cutting edge (3321) and the fixed cutter lining plates (320) is controlled to be 0.5-1.0 mm, a variable pitch section (340) is arranged on the spiral shaft (303) close to the outlet end, and the pitch of the variable pitch section (340) is gradually reduced along the discharging direction; The venturi ejector (400) is connected to the outlet end of the shearing screw conveyor (300), and comprises an outer annular pressure equalizing air chamber (410) and an inner venturi runner, wherein the annular pressure equalizing air chamber (410) is connected with a high-pressure air inlet pipe (411), a circle of Laval nozzle array (420) with an axis forming an included angle of 30-45 degrees with the central runner is arranged around the inner wall of the throat of the venturi runner, and the Laval nozzle array (420) is communicated with the annular pressure equalizing air chamber (410).
  2. 2. A self-shearing anti-windup pneumatic jet feed system for CFB boilers as in claim 1 wherein the upper hopper assembly (100) has an inner wall inclination angle α of greater than 70 °.
  3. 3. A self-shearing anti-windup pneumatic jet feed system for CFB boilers as in claim 1 wherein tungsten carbide overlay (3322) is provided at the serrated edge (3321) of the helical blade (332).
  4. 4. A self-shearing anti-windup pneumatic jet feed system for CFB boilers as in claim 3 wherein the tungsten carbide overlay (3322) has a width of 15 to 25mm and an overlay depth of 10 to 20mm.
  5. 5. A self-shearing anti-windup pneumatic jet feed system for CFB boilers as in claim 1 wherein the working surface of said stationary knife liner (320) is textured with anti-slip lines or splines.
  6. 6. The self-shearing type antiwind pneumatic jet feeding system for CFB boiler according to claim 1, wherein the connection part of the inner wall of the split type casing (310) and the fixed knife lining plate (320) is provided with an arc transition.
  7. 7. A self-shearing anti-windup pneumatic jet feed system for CFB boilers as in claim 1 wherein the inner wall of the diffuser section of said venturi jet (400) is provided with a ceramic wear resistant liner (430).
  8. 8. The self-shearing type anti-winding pneumatic jet feeding system for the CFB boiler according to claim 1, wherein the rotation speed ratio of two bridge breaking roll shafts (201, 202) in the differential bridge breaking device (200) is 1:1.2-1.8.
  9. 9. A self-shearing antiwind pneumatic jet feed system for CFB boilers as in claim 1 wherein the gas source pressure of said high pressure gas inlet duct (411) is higher than the dense phase zone pressure of the CFB boiler furnace.

Description

Self-shearing type winding-preventing pneumatic jet feeding system for CFB boiler Technical Field The invention relates to the technical field of solid fuel feeding, in particular to a self-shearing type winding-preventing pneumatic jet feeding system for flexible fibrous fuels such as waste textiles and the like mixed-burned by a Circulating Fluidized Bed (CFB) boiler. Background The Circulating Fluidized Bed (CFB) combustion technology has become one of the mainstream technologies for cooperatively disposing municipal solid waste, sludge and various industrial wastes of industrial boilers because of the comprehensive advantages of wide fuel adaptability, high combustion efficiency, good pollutant emission control and the like. Particularly in the collection areas of textile industry, such as Yongan City, fujian province, the number of industrial waste fabrics (including but not limited to chemical fiber leftover materials, cotton woven cloth, waste clothes and the like) derived as local post industry is huge. Such waste generally has a relatively high heat value (typically 3500-5000 kcal/kg or even higher), and if the waste is disposed in a direct landfill, not only a large amount of land resources are occupied, but also significant energy waste is caused. Therefore, the solid waste is used as a Solid Recovery Fuel (SRF) to be mixed and burnt into a CFB boiler of a power plant, so that the energy utilization is realized, the economic benefit and the environmental benefit are obvious, and the national pushing strategy of solid waste resource utilization is met. At present, the power and heating industries are very mature aiming at the conventional conveying and feeding technology of rigid particle-shaped fuels such as coal, formed biomass particles and the like, and a standardized equipment system represented by a belt feeder, a scraper feeder and various screw feeders is formed. However, waste textiles are typically "flexible fibrous" materials whose physical properties (e.g., low bulk density, high tensile toughness, ease of entanglement, ease of fluffy agglomeration) are quite different from conventional rigid particulate fuels. Existing rigid material based design conveyor feed systems are generally subject to serious compliance barriers when handling such flexible materials. Along with the continuous improvement of the national policy requirements and execution force for the recycling of the solid wastes, how to realize the large-scale, continuous, stable and reliable transportation and feeding of the waste fabrics into an industrial boiler for combustion has become an outstanding technical bottleneck for restricting the technical popularization and the industrialized application in the field. Specifically, the existing feeding systems for CFB boilers to blend waste are mostly the on-edge or simple modification of traditional biomass feeding equipment, and lack of special designs for the specificity of flexible fiber materials results in exposure of a series of key technical defects in practical application: The technology is the most common mechanical conveying equipment at present, and the material is pushed to move along the axial direction by means of rotating spiral blades and a central shaft. When processing waste fabrics in long strips and fibers, the materials are very easy to attach and wind on the rotating central shaft. As the spiral continues to rotate, the winding continues to accumulate and tighten, eventually forming a dense wrap on the shaft resembling a "dead knot". The device has the advantages that the effective material conveying and circulating section is severely reduced, the spiral running friction resistance is led to be increased sharply in an exponential level, the driving motor is frequently tripped and protected due to overload, and even serious equipment faults that the output shaft of the speed reducer is twisted off are caused under extreme conditions. In order to solve the winding problem of the shaftless screw feeder, attempts are made in the industry to adopt the shaftless screw feeder, and only thickened strip-shaped screw blades are arranged in the U-shaped groove of the shaftless screw feeder, so that a central shaft structure is eliminated. Although the central shaft is removed, for high-strength chemical fiber fabrics such as terylene, chinlon and the like, an assembly or running gap is necessarily reserved between the edge of the shaftless spiral blade and the wear-resistant lining plate of the inner wall of the shell. The flexible fabric is very easily squeezed or jammed in the minute gap. Upon jamming, shaftless screws lacking a central support tend to elastically distort under torque (i.e., a "spring effect") resulting in equipment operational jamming and even complete stalling. In addition, the shaftless spiral structure is difficult to stably run at high rotation speed due to the inherent non-rigid supporting characteristic, and the conveying capacity is re