Multi-stage separation treatment system and method for fly ash

Abstract

The invention discloses a fly ash multi-stage sorting treatment system and method. The system comprises a fly ash collecting unit and a sorting unit which are sequentially connected through a pneumatic conveying pipeline. The sorting unit is composed of a preprocessing module, a grading sorting module and an intelligent management and control module. The pretreatment module is connected in series with a permanent magnet drum type magnetic separator and a fluidized bed type carbon separator at an inlet section of a pipeline, respectively and efficiently removes ferromagnetic impurities and unburnt carbon, and realizes resource circulation of carbon powder; the grading and sorting module is used for realizing step-by-step sorting of the coal ash from coarse to fine through a cyclone separation first-stage sorting machine, a cyclone separation second-stage sorting machine and a bag type dust collector which are sequentially connected in series, so as to form a coarse ash, fine ash and superfine ash three-stage product system; the method realizes fine grading and high-value utilization of fly ash, and has the advantages of high grading precision, stable product quality, high resource cyclic utilization rate and the like.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, specifically to a multi-stage sorting and treatment system and method for fly ash. Background Technology

[0002] Traditional methods for treating fly ash from coal-fired power plants primarily employ pneumatic conveying combined with a two-stage screening process. Cyclone separators and other equipment are used to initially separate the fly ash into coarse and fine grades. While this basic sorting method enables the initial utilization of fly ash, it still has several significant drawbacks in practical application: the grading accuracy is limited, failing to effectively separate ultrafine fly ash with a particle size less than 20μm, resulting in a lack of high-value-added ultrafine fly ash products and a limited product structure. Furthermore, due to the lack of a real-time monitoring and feedback mechanism for key fly ash quality indicators, the product exhibits significant fluctuations in key indicators such as loss on ignition and water demand ratio, making it difficult to meet the quality requirements for admixtures in high-end building materials fields such as high-speed rail and nuclear power.

[0003] Furthermore, the fly ash produced by traditional processing systems is mainly sold in bulk, which cannot meet the market demand for standardized packaged products, and faces transportation restrictions in areas with strict environmental protection requirements. This single product form and sales model restricts market expansion capabilities.

[0004] Therefore, there is an urgent need for a fly ash treatment system that can achieve precise grading, stable quality, and adapt to diversified market demands. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a multi-stage sorting and processing system for fly ash; another purpose of this invention is to provide a multi-stage sorting and processing method for fly ash.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A multi-stage fly ash sorting and processing system includes a fly ash collection unit and a sorting unit connected sequentially by a pneumatic conveying pipeline; the sorting unit includes a pretreatment module, a grading and sorting module, an intelligent control module, and a central control system.

[0008] The pretreatment module includes a permanent magnet drum separator and a fluidized bed carbon separator, which are connected in sequence to the inlet section of the pneumatic conveying pipeline; the outlet of the permanent magnet drum separator is connected to a metal particle collection bin; the outlet of the fluidized bed carbon separator is connected to a carbon powder particle collection bin.

[0009] The grading and sorting module includes a primary cyclone separator, a secondary cyclone separator, and a bag filter, which are connected in series along the material airflow direction on the pneumatic conveying main pipeline of the sorting unit to sort fly ash from coarse to fine. The primary cyclone separator is connected to the coarse ash silo; the secondary cyclone separator is connected to the fine ash silo; and the bag filter is connected to the ultrafine ash silo.

[0010] The intelligent control module includes a laser particle size analyzer located at the inlet of the fine ash silo, and a near-infrared spectrometer and an X-ray fluorescence spectrometer located at the inlet of the ultrafine ash silo, as well as a central control system. The laser particle size analyzer, near-infrared spectrometer, and X-ray fluorescence spectrometer are all connected to the central controller for real-time adjustment of sorting process parameters based on the detection data.

[0011] Preferably, the permanent magnet drum magnetic separator is a vertical cylindrical type and has a neodymium iron boron magnetic system inside.

[0012] Preferably, the fluidized bed carbon separator is a cylindrical cavity with a perforated air distribution plate at the bottom for introducing airflow to separate unburned carbon from qualified fly ash based on density difference.

[0013] Preferably, the cyclone separator is a double-volute cyclone separator.

[0014] Preferably, the bag filter is a PTFE filter bag pulse bag filter.

[0015] Preferably, the system further includes a post-processing unit; the post-processing unit is connected to the sorting unit and includes a packaging line and a paste ash preparation line; the packaging line is located at the outlet of the fine ash silo and the ultrafine ash silo; the paste ash preparation line is located at the outlet of the coarse ash silo.

[0016] Preferably, the packaging line is an automatic quantitative packaging line; the paste preparation line is equipped with a biaxial humidifying mixer.

[0017] A method for multi-stage separation and treatment of fly ash includes the following steps:

[0018] (1) At the inlet section of the pneumatic conveying pipeline, fly ash is passed sequentially through a permanent magnet drum separator and a fluidized bed carbon separator; the permanent magnet drum separator removes ferromagnetic impurities from the fly ash and collects them into a metal particle collection bin; the fluidized bed carbon separator separates unburned carbon and collects it into a carbon powder particle collection bin.

[0019] (2) The pretreated fly ash is sequentially separated from coarse to fine by passing through a series of cyclone separators, a secondary cyclone separator, and a bag filter along the direction of material flow. Coarse ash is separated from the primary cyclone separator and transported to the coarse ash silo, fine ash is separated from the secondary cyclone separator and transported to the fine ash silo, and ultrafine ash is captured from the bag filter and transported to the ultrafine ash silo.

[0020] (3) The particle size distribution of fly ash at the inlet of the fine ash silo is monitored in real time by laser particle size analyzer, and the loss on ignition and chemical composition of fly ash at the inlet of the ultrafine ash silo are monitored in real time by near-infrared spectrometer and X-ray fluorescence spectrometer; and the sorting process parameters are adjusted in real time by central controller based on the monitoring data.

[0021] (4) The ash in the fine ash silo and the ultrafine ash silo are quantitatively packaged, and the ash in the coarse ash silo is humidified and stirred to prepare paste ash.

[0022] Preferably, in step (1), the separated unburnt carbon is returned to the boiler coal yard for reuse via a screw conveyor and a coal conveyor belt.

[0023] Preferably, in step (2), the coarse ash particle size is greater than 45 μm; the fine ash particle size is 20 μm to 45 μm; and the ultrafine ash particle size is less than 20 μm.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant effects:

[0025] I. By constructing a three-tiered product system of "coarse ash - fine ash - ultrafine ash" through a grading and sorting module, ultrafine ash suitable for high-end concrete was successfully separated. Combined with a quantitative packaging line and a paste ash preparation line, product diversification was achieved, significantly enhancing product value.

[0026] Second, by employing an online detection system that integrates laser particle size analyzer, near-infrared spectrometer, and X-ray fluorescence spectrometer, and connecting it to a central controller, key indicators such as particle size distribution, loss on ignition, and chemical composition of fly ash can be monitored and automatically adjusted in real time. This significantly increases the product qualification rate from the original 65% to over 98%, consistently meeting the Class I ultrafine fly ash standard and providing quality assurance for entering high-end application markets such as high-speed rail and nuclear power.

[0027] Third, the combined application of a drum magnetic separator and a fluidized bed carbon separator not only effectively removes iron impurities and unburned carbon, but also enables the recovery of carbon powder for reuse in the boiler, forming a resource cycle. The preparation of paste ash solves the dust problem during transportation.

[0028] Fourth, the system of this invention adopts a modular design and is integrated into the existing pneumatic conveying pipeline, preserving the original system architecture to the greatest extent. This allows the renovation period to be shortened to 72 hours, and eliminates the need for additional modifications to the main power equipment, greatly reducing renovation costs and the impact on power plant production. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system flow of the present invention;

[0030] List of identifiers in attached diagrams:

[0031] 1. Economizer ash silo; 2. Denitrification ash silo; 3. Electrostatic precipitator ash silo; 4. Ash pump; 5. Ash silo; 6. Roots blower; 7. Gasification blower heater; 8. Permanent magnet drum separator; 9. Metal particle collection silo; 10. Fluidized bed carbon separator; 11. Carbon powder particle collection silo; 12. High-pressure centrifugal induced draft fan; 13. Cyclone separator primary separator; 14. Coarse ash silo; 15. Booster fan; 16. Cyclone separator secondary separator; 17. Fine ash silo; 18. Laser particle size analyzer; 19. Near-infrared spectrometer; 20. X-ray fluorescence spectrometer; 21. Bag filter; 22. Ultrafine ash silo; 23. Packaging line; 24. Paste ash preparation line. Detailed Implementation

[0032] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0033] Please see Figure 1 A multi-stage fly ash sorting and processing system includes a fly ash collection unit and a sorting unit connected in sequence via pneumatic conveying pipelines;

[0034] The fly ash collection unit includes an economizer ash bin 1, a denitrification ash bin 2, an electrostatic precipitator ash bin 3, an ash pump 4, and an ash bin 5. Raw fly ash from the boiler system is first collected in the economizer ash bin 1, the denitrification ash bin 2, and the electrostatic precipitator ash bin 3, respectively. Then, it is transported by the ash pump 4 and concentrated in the ash bin 5 for temporary storage and homogenization, providing a stable and continuous ash source for subsequent sorting and processing.

[0035] The sorting unit includes a pretreatment module, a grading and sorting module, an intelligent control module, and a central control system. The pretreatment module is connected in series at the inlet section of the pneumatic conveying pipeline starting from the outlet of ash silo 5. The permanent magnet drum separator 8 has a cylindrical vertical structure and is internally equipped with a high-performance neodymium iron boron magnetic system with a magnetic field strength ≥1500 Gauss. When fly ash is pneumatically conveyed to the permanent magnet drum separator 8, ferromagnetic impurities, such as boiler slag fragments and metal abrasion particles, are adsorbed onto the surface of the drum by the strong magnetic field. As the drum rotates, they are carried to the non-magnetic field area and then fall off under gravity, entering the metal particle collection bin 9 below. This process achieves an iron impurity separation efficiency of ≥95%, effectively protecting subsequent grading equipment. The collected iron impurities can be sold externally.

[0036] The fluidized bed carbon separator 10 is a cylindrical cavity with a perforated air distribution plate at the bottom. A Roots blower 6 is installed at the outlet of the ash silo 5. The airflow provided by the Roots blower 6, preheated by the gasification blower heater 7, is uniformly introduced from the bottom of the fluidized bed carbon separator 10, keeping the passing fly ash in a fluidized state. Unburned carbon has a density of 1.2-1.4 g / cm³, while qualified fly ash has a density of 2.1-2.4 g / cm³. Based on this density difference, the lighter unburned carbon floats with the airflow and enters the carbon powder collection silo 11 from the top outlet; while the qualified fly ash settles along the cavity sidewall and enters the lower-level pipeline from the bottom outlet. This process can reduce the fly ash loss on ignition from over 8% to below 3%. The collected carbon powder is returned to the boiler for combustion through the coal conveying system, achieving resource recycling.

[0037] The pre-treated and purified fly ash enters the grading and sorting module under the traction of a high-pressure centrifugal induced draft fan 12. The cyclone separator 13 in the grading and sorting module, as the first stage of sorting, uses centrifugal force to separate particles >45μm from the airflow, which are then transported as coarse ash to the coarse ash silo 14 for storage. The cyclone separator 16 is a double-volute cyclone separator, a current technology whose dual-inlet structure better matches the power characteristics of the existing system's fans. It further separates particles with a diameter of 20-45μm as fine ash, which are then transported to the fine ash silo 17. A booster fan 15 is installed between the cyclone separator 13 and the cyclone separator 16 to compensate for the system pressure loss after the first stage of sorting, providing stable airflow power for the second stage of sorting and ensuring sorting efficiency. Baghouse dust collector 21 is a PTFE filter bag pulse bag dust collector, which efficiently filters and captures ultrafine dust with a particle size <20μm that was not captured in the first two stages, with a capture rate of over 99.5%. The collected ultrafine dust is sent to the ultrafine dust silo 22. The purified dry air can be reused or discharged. At this point, the system forms a three-stage product system of coarse dust with a diameter >45μm, fine dust with a diameter of 20-45μm, and ultrafine dust with a diameter <20μm.

[0038] To ensure stable product quality, an intelligent control module is implemented. This includes a laser particle size analyzer 18 located at the inlet of the fine ash silo 17, and near-infrared spectrometer 19 and X-ray fluorescence spectrometer 20 located at the inlet of the ultrafine ash silo 22, along with a central control system. The laser particle size analyzer 18 monitors the particle size distribution indicators such as D10, D50, and D90 of the incoming fine ash in real time. If the D50 deviation exceeds ±5%, the central controller automatically adjusts the frequency converter of the grading fan to change the airflow speed and correct the grading accuracy.

[0039] Near-infrared spectrometer 19 and X-ray fluorescence spectrometer 20 are used. The sampling probe of near-infrared spectrometer 19 is inserted into the inlet pipe of ultrafine ash silo 22 to quickly detect the loss on ignition (LOI) and water demand ratio of fly ash. If the LIO > 5%, the system will link with the boiler DCS to increase the secondary air distribution ratio from 28% to 32% to reduce the carbon content. If the water demand ratio > 105%, the electric heating wire installed on the outer wall of the conveying pipe will be automatically activated. By adjusting the current of the electric heating wire, the heating amount will be changed, thereby regulating the temperature to improve the surface activity of the particles. X-ray fluorescence spectrometer 20 automatically samples from fine ash silo 17 every hour to detect the total content of SiO2, Al2O3, and Fe2O3. If it is lower than 70%, an early warning will be triggered, prompting an adjustment of the coal blending ratio.

[0040] Based on market demand, the sorted products undergo morphological optimization. The system also includes a post-processing unit connected to the sorting unit. This includes a packaging line 23 and a paste / ash preparation line 24.

[0041] Packaging line 23 is located at the bottom of the fine ash silo 17 and the ultrafine ash silo 22, and is an automatic quantitative packaging line. It includes two forms: 25kg small bag heat-sealed packaging and 1-ton large bag ton packaging, to meet the small-batch purchasing needs of different customers.

[0042] The paste ash preparation line 24 is located at the outlet of the coarse ash silo 14 and is equipped with a twin-shaft humidifying mixer. The paste ash preparation line mixes the coarse ash into a paste with a moisture content of 30%-35% at a water-ash ratio of 1:0.3, and then transports it by sealed tank truck. It is suitable for areas with strict environmental protection requirements and effectively avoids dust.

[0043] It should be noted that the system described in this invention is a modular upgrade based on retaining the main architecture of the existing fly ash pneumatic conveying system in the power plant, including but not limited to the main conveying pipelines, fan power foundations, and ash silo facilities. The permanent magnet drum separator, fluidized bed carbon separator, double volute cyclone separator, and PTFE filter bag pulse jet bag filter are all existing technologies. The central control system can be implemented using conventional programmable logic controllers (PLCs), distributed control systems (DCS), or industrial computers. Its core function is to execute the specific control logic and linkage program designed in this invention, while the hardware itself is existing technology. This invention achieves refined grading and stable quality control of fly ash on existing infrastructure through the innovative integration and synergy of specific functional modules such as pre-processing, grading and sorting, intelligent control, and post-processing.

Claims

1. A multi-stage fly ash sorting and processing system, characterized in that: This includes a fly ash collection unit and a sorting unit connected in sequence via pneumatic conveying pipelines; The sorting unit includes a preprocessing module, a grading and sorting module, an intelligent control module, and a central control system; The pretreatment module includes a permanent magnet drum separator (8) and a fluidized bed carbon separator (10), which are connected in sequence to the inlet section of the pneumatic conveying pipeline; the outlet of the permanent magnet drum separator (8) is connected to a metal particle collection bin (9); the outlet of the fluidized bed carbon separator (10) is connected to a carbon powder particle collection bin (11). The grading and sorting module includes a cyclone separator (13), a cyclone separator (16), and a bag filter (21), which are connected in series along the direction of material airflow on the pneumatic conveying main pipeline of the sorting unit; the cyclone separator (13) is connected to the coarse ash silo (14); the cyclone separator (16) is connected to the fine ash silo (17); and the bag filter (21) is connected to the ultrafine ash silo (22). The intelligent control module includes a laser particle size analyzer (18) located at the inlet of the fine ash silo (17), a near-infrared spectrometer (19) and an X-ray fluorescence spectrometer (20) located at the inlet of the ultrafine ash silo (22), and a central control system; the laser particle size analyzer (18), the near-infrared spectrometer (19) and the X-ray fluorescence spectrometer (20) are all connected to the central controller for adjusting the sorting process parameters in real time according to the detection data.

2. The multi-stage fly ash sorting and processing system according to claim 1, characterized in that, The permanent magnet drum magnetic separator (8) is a cylindrical vertical type and is equipped with a neodymium iron boron magnetic system inside.

3. The multi-stage fly ash sorting and processing system according to claim 1, characterized in that, The fluidized bed carbon separator (10) is a cylindrical cavity with a perforated air distribution plate at the bottom.

4. The multi-stage fly ash sorting and processing system according to claim 1, characterized in that, The cyclone separator (16) is a double volute cyclone separator.

5. The multi-stage fly ash sorting and processing system according to claim 1, characterized in that, The bag filter (21) is a PTFE filter bag pulse bag filter.

6. The multi-stage fly ash sorting and processing system according to claim 1, characterized in that, The system also includes a post-processing unit connected to the sorting unit, which includes a packaging line (23) and a paste ash preparation line (24); the packaging line (23) is located at the outlet of the fine ash silo (17) and the ultrafine ash silo (22); the paste ash preparation line (24) is located at the outlet of the coarse ash silo (14).

7. The multi-stage fly ash sorting and processing system according to claim 6, characterized in that, The packaging line (23) is an automatic quantitative packaging line; the paste ash preparation line (24) is equipped with a biaxial humidifying mixer.

8. A multi-stage sorting and treatment method for fly ash as described in claim 1, characterized in that, Includes the following steps: (1) At the inlet section of the pneumatic conveying pipeline, fly ash is passed sequentially through a permanent magnet drum separator (8) and a fluidized bed carbon separator (10); the permanent magnet drum separator (8) removes ferromagnetic impurities from the fly ash and collects them into a metal particle collection bin (9); the fluidized bed carbon separator (10) separates unburned carbon and collects it into a carbon powder particle collection bin (11). (2) The pretreated fly ash is sequentially separated from coarse to fine by passing through a series of cyclone separators (13), cyclone separators (16), and bag filter (21) along the direction of material flow. Coarse ash is separated from the cyclone separator (13) and transported to the coarse ash silo (14). Fine ash is separated from the cyclone separator (16) and transported to the fine ash silo (17). Ultrafine ash is captured from the bag filter (21) and transported to the ultrafine ash silo (22). (3) The particle size distribution of fly ash at the inlet of the fine ash silo (17) is monitored in real time by a laser particle size analyzer (18), and the loss on ignition and chemical composition of fly ash at the inlet of the ultrafine ash silo (22) are monitored in real time by a near-infrared spectrometer (19) and an X-ray fluorescence spectrometer (20); and the sorting process parameters are adjusted in real time by a central controller based on the monitoring data. (4) The ash in the fine ash silo (17) and the ultrafine ash silo (22) are quantitatively packaged, and the ash in the coarse ash silo (14) is humidified and stirred to prepare paste ash.

9. The multi-stage sorting and treatment method for fly ash according to claim 8, characterized in that, In step (1), the separated unburnt carbon is returned to the boiler coal yard for reuse via a screw conveyor and a coal conveyor belt.

10. The multi-stage sorting and treatment method for fly ash according to claim 8, characterized in that, In step (2), the coarse ash particles have a diameter greater than 45 μm; the fine ash particles have a diameter of 20 μm to 45 μm; and the ultrafine ash particles have a diameter less than 20 μm.

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