A fly ash harmless and resourceful disposal system and disposal method

Abstract

The present application belongs to the technical field of solid waste treatment, and particularly relates to a fly ash harmless and resourceful disposal system and a disposal method. The fly ash harmless and resourceful disposal system comprises a mixing and stirring unit, a fluidized bed drying and preheating unit, a dioxin catalytic cracking unit, a water washing and desalination unit, an evaporation and crystallization salt making unit and a flue gas treatment unit; the mixing and stirring unit is used for stirring and mixing fly ash, a solidifying agent and a catalyst in a set proportion; the gas outlet of the dioxin catalytic cracking unit is connected with the gas inlet of the fluidized bed preheating and drying unit, the gas outlet of the fluidized bed preheating and drying unit is connected with the gas inlet of the evaporation and crystallization salt making unit, and the gas outlet of the evaporation and crystallization salt making unit is connected with the gas inlet of the flue gas treatment unit. The fly ash harmless and resourceful disposal method adopts the fly ash harmless and resourceful disposal system, realizes the harmless and resourceful disposal of fly ash, greatly reduces energy consumption and saves cost.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology, and in particular relates to a system and method for the harmless and resource-based disposal of fly ash. Background Technology

[0002] Fly ash refers to the tiny ash particles emitted during the combustion of dyes, with a particle size generally between 1 and 100 μm. The main source of fly ash is municipal solid waste incineration, where it is a secondary pollutant generated during the incineration process, accounting for approximately 0.5% to 3% of the total waste incinerated. Fly ash contains the toxic substance dioxin, which, under certain conditions, can seep into soil, atmosphere, and other environmental media, entering the bodies of plants and animals, ultimately accumulating in the human body and threatening human health, causing secondary pollution. Furthermore, fly ash from municipal solid waste incineration also accumulates various heavy metals, which can accumulate through the food chain, posing a serious threat to the environment and human health. Therefore, the harmless treatment of fly ash is essential. Additionally, fly ash contains components such as CaO, SiO2, and Fe2O3, similar to the raw materials used in cement production. Therefore, it is often used as a substitute for cement production raw materials or utilized in the preparation of concrete and aggregates. Thus, the resource utilization of fly ash is also crucial.

[0003] The most common method for treating fly ash is solidification landfill, which consolidates heavy metals and dioxins within the fly ash, reducing the risk of landfill leaching. However, this method requires a large amount of cement and extensive human supervision. Landfilling is limited, and fly ash itself has low economic value and added value, resulting in a low resource utilization rate.

[0004] To address the aforementioned issues, Chinese invention patent application CN116851421A discloses a continuous fly ash dioxin hydrothermal degradation and heavy metal solidification system and method. This system includes a slurry preparation device, a feeding device, a hydrothermal reaction device, a heating device, a discharging device, and a slurry cooling device. Fly ash enters the slurry preparation device, where water is added to prepare a fly ash slurry. The fly ash slurry is fed into the hydrothermal reaction device via the feeding device, and the heating device provides heat to the hydrothermal reaction device. The hydrothermal reaction degrades the dioxins in the fly ash slurry. After hydrothermal reaction, the fly ash slurry is discharged into the slurry cooling device. After cooling, it undergoes further resource utilization treatment, including fly ash washing, evaporation crystallization for salt extraction, use as a cement production raw material, and use as a brick and ceramic raw material, or one or more of these treatments.

[0005] As can be seen from the above-disclosed information, there are currently methods to remove dioxins from fly ash using hydrothermal degradation and to convert chlorine in fly ash into chloride salts through evaporation and crystallization. However, both hydrothermal degradation and evaporation and crystallization require heat to be provided, which consumes a lot of energy. Summary of the Invention

[0006] This invention provides a system and method for the harmless and resource-based treatment of fly ash, which differs from existing methods for the harmless and resource-based treatment of fly ash and solves the technical problem of high energy consumption in existing methods.

[0007] To address the above problems, the present invention provides a fly ash harmless and resource-based disposal system, which adopts the following technical solution: A fly ash harmless and resource-based disposal system includes a mixing and stirring unit with a material inlet and a material outlet, a fluidized bed drying and preheating unit, a dioxin catalytic cracking unit, a water washing and desalination unit, an evaporation crystallization salt production unit, and a flue gas treatment unit; the fluidized bed preheating and drying unit, the dioxin catalytic cracking unit, the evaporation crystallization salt production unit, and the flue gas treatment unit also have an air inlet and an air outlet; The material outlet of the mixing and stirring unit is connected to the material inlet of the fluidized bed drying and preheating unit. The mixing and stirring unit is used to mix fly ash, curing agent and catalyst in a set proportion. The material outlet of the fluidized bed preheating and drying unit is connected to the material inlet of the dioxin catalytic cracking unit. The material outlet of the dioxin catalytic cracking unit is connected to the material inlet of the water washing and desalination unit. The material outlet of the water washing and desalination unit is connected to the material inlet of the evaporation crystallization salt production unit. The outlet of the dioxin catalytic cracking unit is connected to the inlet of the fluidized bed preheating and drying unit, the outlet of the fluidized bed preheating and drying unit is connected to the inlet of the evaporation crystallization salt production unit, and the outlet of the evaporation crystallization salt production unit is connected to the inlet of the flue gas treatment unit.

[0008] Furthermore, the mixing unit includes a fly ash storage bin, a catalyst storage bin, a curing agent storage bin, a metering belt scale, and a mixer. Three metering belt scales are provided, each connected to the outlet of one of the fly ash storage bins, one of the catalyst storage bins, and one of the curing agent storage bins. The ends of all three metering belt scales are connected to the inlet of the mixer. The outlet of the dedicated mixer forms the material outlet of the mixing unit and is connected to the material inlet of the fluidized bed drying and preheating unit. The three metering belt scales simultaneously feed material into the inlet of the mixer.

[0009] Furthermore, the mixing machine includes a material mixing tank and two sets of cutters rotatably assembled inside the material mixing tank. The two sets of cutters rotate in opposite directions and have a speed difference.

[0010] Furthermore, the dioxin catalytic cracking unit includes a cracking furnace and a hot blast furnace. The outlet of the hot blast furnace is connected to the inlet of the cracking furnace to heat the cracking furnace. The fluidized bed preheating and drying unit includes a fluidized bed with an inlet and an outlet and a first dust collector. The outlet of the cracking furnace forms the outlet of the dioxin catalytic cracking unit and is connected to the inlet of the fluidized bed. The outlet of the fluidized bed is connected to the inlet of the first dust collector, and the outlet of the first dust collector is connected to the inlet of the evaporation crystallization salt production unit.

[0011] Furthermore, the evaporation crystallization salt production unit includes an evaporator and a sodium chloride storage tank and a potassium chloride storage tank connected to the material outlet of the evaporator, and the air inlet of the evaporator is connected to the air inlet of the first dust collector.

[0012] Furthermore, the flue gas treatment unit includes a quench tower, a second dust collector, an alkaline scrubbing tower, an activated carbon adsorption device, and a chimney connected in sequence. The air inlet of the quench tower forms the air inlet of the flue gas treatment unit and is connected to the air outlet of the evaporator. The exhaust outlet of the chimney forms the air outlet of the flue gas treatment unit.

[0013] Furthermore, the first dust collector and the second dust collector are either bag filters or cyclone dust collectors.

[0014] Furthermore, the water washing and desalination unit includes multiple stages of sequentially connected water washing devices and equalization tanks. The water washing devices are used to wash the fly ash after dioxin removal to obtain a washing solution containing sodium chloride and potassium chloride salts. Each stage of the water washing device has a washing solution inlet, a washing solution outlet, a material inlet, and a material outlet. The material inlet of the first stage water washing device is connected to the material outlet of the dioxin catalytic cracking unit, and the material inlet of the first stage water washing device is also connected to a first reagent addition device for adding alkaline salt solution. In adjacent stages of water washing devices, the material outlet of the previous stage water washing device is connected to the material inlet of the next stage water washing device, and the washing solution outlet of the next stage water washing device is connected to the washing solution inlet of the previous stage water washing device. The washing solution inlet of the last stage water washing device is connected to a water supply source, and the material outlet of the last stage water washing device is connected to a resource utilization device for resource utilization of wet ash. The washing solution outlet of the first stage water washing device is connected to the equalization tank, and the equalization tank is connected to a second reagent addition device for adding pH adjusting agent to the equalization tank to adjust the pH value of the washing solution.

[0015] The beneficial effects of the fly ash harmless and resource-based disposal system of the present invention are: 1. This invention employs a method distinct from existing hydrothermal degradation for treating dioxins in fly ash. Fly ash, catalyst, and solidifying agent are mixed to form a mixture, which is then preheated and dried before being introduced into a pyrolysis furnace. Under the catalytic action of the catalyst, dioxins undergo a pyrolysis reaction. The breaking of chemical bonds requires less energy, allowing the reaction to remove carcinogenic dioxins from fly ash at lower temperatures and with less energy consumption, thus achieving harmless treatment of the fly ash. After the dioxins are eliminated through pyrolysis, subsequent hydrolysis and evaporation crystallization processes are carried out for resource utilization. The heat required for the fluidized bed preheating and drying unit and the evaporation crystallization salt production unit is entirely provided by the high-temperature flue gas generated by the dioxin catalytic pyrolysis unit, eliminating the need for separate external heat sources, significantly reducing energy consumption and saving processing costs.

[0016] 2. In this invention, fly ash, curing agent and catalyst are mixed and preheated to eliminate the water vapor carried before dioxin pyrolysis and removal. The dried and preheated fly ash can reduce the heat of the pyrolysis furnace, so that the pyrolysis furnace does not need a higher temperature, thereby reducing the size of the pyrolysis furnace and making it easier to seal the pyrolysis furnace and reduce heat loss. 3. This invention can solidify heavy metals in fly ash into metal complexes by a solidifying agent, and will not be emitted with flue gas. The toxicity of the solidified heavy metals is greatly reduced, which meets national standards. Silicon, calcium, aluminum, magnesium and other elements can be used as raw materials for building materials production and separated into wet ash through a water washing device. Chlorine is separated into washing liquid through a water washing device and further processed into industrial sodium chloride and potassium chloride through an evaporation crystallization device, which has commercial value.

[0017] The technical solution of the present invention for the harmless and resource-based disposal of fly ash is as follows: The present invention provides a method for the harmless and resource-based disposal of fly ash, employing one of the above-mentioned technical solutions for the harmless and resource-based disposal of fly ash, comprising the following steps: The fly ash, curing agent and catalyst in a set ratio are mixed and stirred in a mixing unit, and the mixture after mixing is preheated and dried by a fluidized bed drying and preheating unit to remove water vapor from the mixture. The fly ash after dioxin removal is washed with water in the water washing and desalination unit to obtain a washing solution containing sodium chloride and potassium chloride salts, and the wet ash obtained after water washing is utilized for resource recovery. The flue gas generated by the dioxin catalytic cracking unit is treated by the flue gas treatment unit and then discharged in compliance with standards. The heat source required for the fluidized bed drying and preheating unit comes from the flue gas of the dioxin catalytic cracking unit, and the heat source required for the evaporation crystallization salt production unit comes from the flue gas preheated by the fluidized bed drying and preheating unit.

[0018] Preferably, the pyrolysis temperature range of the dioxin catalytic cracking unit is 400℃-600℃, the flue gas temperature range of the flue gas inlet of the fluidized bed equipment is 200℃-400℃, and the flue gas temperature range of the inlet of the evaporation crystallization salt production unit is 200℃-300℃.

[0019] The beneficial effects of the fly ash harmless and resource-based disposal method of the present invention are: the present invention can realize the harmless and resource-based treatment of fly ash, and the heat energy required by the fluidized bed drying preheating unit and the evaporation crystallization salt production unit are all from the flue gas of the dioxin catalytic cracking unit, without the need for an additional heat source, which greatly reduces energy consumption. Attached Figure Description

[0020] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein: Figure 1 This is a schematic diagram showing the connection process between various units in the fly ash harmless and resource-based disposal system of the present invention. Figure 2 This is a detailed process flow diagram of the fly ash harmless and resource-based disposal system of the present invention; Figure 3 for Figure 2 A schematic diagram of the structural connections between the various devices.

[0021] Explanation of reference numerals in the attached figures: 10. Mixing and stirring unit; 11. Fly ash temporary storage bin; 12. Catalyst temporary storage bin; 13. Curing agent temporary storage bin; 14. First metering belt scale; 15. Mixing machine; 16. Second metering belt scale; 17. Third metering belt scale; 20. Fluidized bed drying and preheating unit; 21. Fluidized bed; 22. First dust collector; 23. Hot air furnace; 30. Dioxin catalytic cracking unit; 31. Cracking furnace; 40. Flue gas treatment unit; 41. Quenching tower; 42. Second dust collector; 43. Spray tower; 44. Activated carbon adsorption device; 45. Chimney; 50. Multi-stage countercurrent water washing and desalination unit; 51. First-stage water washing device; 52. Second-stage water washing device; 53. Third-stage water washing device; 54. Adjustment tank; 60. Evaporation crystallization salt production unit; 61. Evaporator; 62. Sodium chloride storage tank; 63. Potassium chloride storage tank. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art should understand that the embodiments described below are only some, not all, of the embodiments disclosed. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] The principles and spirit of the present invention will be explained in detail below with reference to several representative embodiments.

[0024] Embodiments of the fly ash harmless and resource-based disposal system provided by the present invention: like Figure 1 As shown, a fly ash harmless and resource-based treatment system includes a mixing and stirring unit 10, a fluidized bed drying and preheating unit 20, a dioxin catalytic cracking unit 30, a flue gas treatment unit 40, a multi-stage countercurrent water washing and desalting unit 50, and an evaporation crystallization salt production unit 60.

[0025] The relationships between the various units are as follows: Figure 1 As shown, the material outlet of the mixing and stirring unit 10 is connected to the material inlet of the fluidized bed drying and preheating unit 20; the material outlet of the fluidized bed preheating and drying unit is connected to the material inlet of the dioxin catalytic cracking unit 30; the material outlet of the dioxin catalytic cracking unit 30 is connected to the material inlet of the multi-stage countercurrent water washing and desalting unit 50; and the material outlet of the multi-stage countercurrent water washing and desalting unit 50 is connected to the material inlet of the evaporation crystallization salt production unit 60. The fluidized bed preheating and drying unit, the dioxin catalytic cracking unit 30, the evaporation crystallization salt production unit 60, and the flue gas treatment unit 40 are also equipped with air inlets and outlets. The air outlet of the dioxin catalytic cracking unit 30 is connected to the air inlet of the fluidized bed preheating and drying unit, the air outlet of the fluidized bed preheating and drying unit is connected to the air inlet of the evaporation crystallization salt production unit 60, and the air outlet of the evaporation crystallization salt production unit 60 is connected to the air inlet of the flue gas treatment unit.

[0026] Specifically, the mixing unit 10 is used to weigh and mix the fly ash, facilitating the subsequent solidification of heavy metals in the fly ash and the decomposition of dioxins. In this embodiment, as... Figure 2 and Figure 3As shown, the mixing unit 10 includes a fly ash storage bin 11, a catalyst storage bin 12, a curing agent storage bin 13, a first metering belt scale 14, a second metering belt scale 16, a third metering belt scale 17, and a mixer 15. The catalyst stored in the catalyst storage bin 12 is an alkaline metal oxide such as calcium oxide, copper oxide, or alumina. The first metering belt scale 14 is connected to the outlet of the catalyst storage bin 12 and is used to weigh and transport the catalyst. The curing agent stored in the curing agent storage bin 13 is cement; however, in other embodiments, cement can be replaced with fly ash or other commercial curing agents. The second metering belt scale 16 is connected to the outlet of the curing agent storage bin 13 and is used to weigh and transport the curing agent. The third metering belt scale 17 is connected to the outlet of the fly ash storage bin 11 and is used to weigh and transport the fly ash. The first metering belt scale 14, the second metering belt scale 16, and the third metering belt scale 17 have the same structure, and their ends are all connected to the feed inlet of the mixer 15 to synchronously feed materials into the mixer 15. The catalyst entering the mixer 15 accounts for 3%-5% of the mass of the fly ash entering the mixer 15; the curing agent entering the mixer 15 accounts for 3%-5% of the mass of the fly ash entering the mixer 15.

[0027] The mixing machine 15 is a special equipment that can fully and evenly mix fly ash, curing agent and catalyst. It includes a rotatable material mixing drum and two sets of cutters. The two sets of cutters are rotatably assembled in the material mixing drum. The material mixing drum rotates clockwise, while the two sets of cutters rotate in opposite directions and have different rotation speeds. The discharge port of the material mixing drum forms the material outlet of the entire mixing unit 10.

[0028] The fluidized bed drying and preheating unit 20 is used to preheat and dry the fly ash, facilitating subsequent pyrolysis and dioxin removal. For example... Figure 2 and Figure 3 As shown, the fluidized bed drying and preheating unit 20 includes a fluidized bed 21 and a first dust collector 22. The material inlet of the fluidized bed 21 is connected to the material outlet of the mixer 15. Both the fluidized bed 21 and the first dust collector 22 have an air inlet and an air outlet, with the air outlet of the fluidized bed 21 connected to the air inlet of the first dust collector 22. In this embodiment, the first dust collector 22 is a cyclone dust collector commonly used in the prior art.

[0029] The dioxin catalytic cracking unit 30 is used to efficiently remove the harmful substance dioxin from fly ash. In this embodiment, for example... Figure 2 and Figure 3As shown, the dioxin catalytic cracking unit 30 includes a cracking furnace 31 and a hot air furnace 23. The outlet of the hot air furnace 23 is connected to the inlet of the cracking furnace 31. The hot air generated by the hot air furnace 23 enters the cracking furnace 31 and heats it, raising its temperature to the temperature required for cracking. The pyrolysis temperature of the cracking furnace 31 is 400℃-600℃. The outlet of the cracking furnace 31 forms the outlet of the entire dioxin catalytic cracking unit 30. The outlet of the cracking furnace 31 is connected to the inlet of the fluidized bed 21, and the flue gas temperature at the inlet of the fluidized bed 21 is 200℃-400℃.

[0030] The multi-stage countercurrent water washing and desalination unit 50 is used to wash the fly ash after dioxin removal with water to obtain a washing solution containing sodium chloride and potassium chloride salts. In this embodiment, as shown... Figure 2 and Figure 3 As shown, the multi-stage countercurrent water washing and desalination unit 50 includes a first-stage water washing device 51, a second-stage water washing device 52, a third-stage water washing device 53, and an equalization tank 54. Each stage of the water washing device has a water washing liquid inlet, a water washing liquid outlet, a material inlet, and a material outlet. Furthermore, each stage of the water washing device also has the functions of mixing water and fly ash and separating water and wet ash. This part is prior art and will not be described in detail here.

[0031] The material inlet of the first-stage washing device 51 is connected to the material outlet of the dioxin catalytic cracking unit 30. The material inlet of the first-stage washing device 51 is also connected to a first reagent addition device for adding an alkaline salt solution, such as sodium carbonate, sodium phosphate, or sodium sulfate solution. The material outlet of the first-stage washing device 51 is connected to the material inlet of the second-stage washing device 52. The material outlet of the second-stage washing device 52 is connected to the material inlet of the third-stage washing device 53. The material outlet of the third-stage washing device 53 is connected to a resource utilization device for the resource utilization of wet ash. The washing liquid outlet of the first-stage washing device 51 is connected to the equalization tank 54. The washing liquid inlet of the first-stage washing device 51 is connected to the washing liquid outlet of the second-stage washing device 52. The washing liquid inlet of the second-stage washing device 52 is connected to the washing liquid outlet of the third-stage washing device 53. The washing liquid inlet of the third-stage washing device 53 is connected to a water supply source to supply water to the third-stage washing device 53. During the washing process, the water-to-ash ratio of each level of the washing device can be adjusted from 3:1 to 5:1.

[0032] The equalization tank 54 is used to adjust the pH value of the washing liquid. It is connected to a second agent addition device for adding pH adjusting agent to the equalization tank 54 to adjust the pH value of the washing liquid. The pH adjusting agent uses acidic substances such as hydrochloric acid, and finally adjusts the pH value of the washing liquid to 7~9.

[0033] The evaporation crystallization salt production unit 60 utilizes the different solubilities of sodium chloride and potassium chloride to precipitate them in stages, yielding industrial-grade sodium chloride and potassium chloride. For example... Figure 2 and Figure 3 As shown, in this embodiment, the evaporation crystallization salt production unit 60 includes an evaporator 61, a sodium chloride storage tank 62, and a potassium chloride storage tank 63. The evaporator 61 is an existing MVR evaporator 61. The material inlet of the evaporator 61 is connected to the regulating tank 54, and the material outlet is connected to the sodium chloride storage tank 62 and the potassium chloride storage tank 63, respectively. The evaporator 61 utilizes the difference in solubility of sodium chloride and potassium chloride with temperature changes to evaporate and crystallize the washing liquid separated by the filtration device to obtain sodium chloride crystal salt. The sodium chloride crystal salt is then separated, and the mother liquor is cooled to obtain potassium chloride crystal salt. The air inlet of the evaporator 61 is connected to the air outlet of the first dust collector 22. The first dust collector 22 is used to remove particulate impurities from the flue gas, preventing them from entering the evaporator 61 and causing blockage or damage. In addition, the condensate generated during the evaporation process of the evaporator 61 can also be reused in the multi-stage countercurrent water washing and desalination unit 50 as clean water for the washing process.

[0034] The flue gas treatment unit 40 is used to treat the flue gas generated by the dioxin catalytic cracking unit 30 to ensure it meets emission standards. For example... Figure 2 and Figure 3 As shown, in this embodiment, the flue gas treatment unit includes a quench tower 41, a second dust collector 42, an alkaline scrubbing tower 43, an activated carbon adsorption device 44, and a chimney 45 connected in sequence. The inlet of the quench tower 41 forms the inlet of the flue gas treatment unit and is connected to the outlet of the evaporator 61. The second dust collector 42 is a bag filter or a cyclone dust collector, which can further purify particles and other impurities in the flue gas discharged from the evaporator 61. The exhaust port of the chimney 45 forms the outlet of the flue gas treatment unit, and the outlet flue gas temperature of the chimney 45 is 120℃-150℃.

[0035] This invention makes full use of the surplus heat energy of the flue gas after the pyrolysis stage, and uses the surplus heat of the flue gas to further provide heat energy for the fluidized bed drying preheating unit 20 and the evaporation crystallization salt production unit 60. On the one hand, the fly ash after drying and preheating reduces the heat of the dioxin pyrolysis unit. On the other hand, it saves a lot of energy by not using an additional heat source as the heating source of the evaporator 61.

[0036] Examples of the fly ash harmless and resource-based disposal method of the present invention: The fly ash harmless and resource-based disposal method adopts the fly ash harmless and resource-based disposal system described in the above embodiments, therefore the structure of the fly ash harmless and resource-based disposal system will not be described in detail.

[0037] The methods for harmless and resource-based disposal of fly ash mainly include the following steps: The fly ash, curing agent and catalyst in a set ratio are mixed and stirred in the mixing and stirring unit 10, and the mixture after mixing is preheated and dried by the fluidized bed drying and preheating unit 20 to remove water vapor from the mixture. Dioxins are removed from fly ash via dioxin catalytic cracking unit 30; The fly ash after dioxin removal is washed with water in the water washing and desalination unit to obtain a washing solution containing sodium chloride and potassium chloride salts, and the wet ash obtained after water washing is utilized for resource recovery. The washing liquid containing sodium chloride and potassium chloride is evaporated and crystallized in stages through the evaporation crystallization salt production unit 60 to obtain sodium chloride and potassium chloride. The flue gas generated by the dioxin catalytic cracking unit 30 is treated by the flue gas treatment unit 40 and then discharged in compliance with standards. The surplus heat energy of the flue gas after the dioxin catalytic cracking unit 30 is used to provide heat energy for the fluidized bed drying preheating unit 20 and the evaporation crystallization salt production unit 60.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for the harmless and resource-based treatment of fly ash, characterized in that, It includes a mixing and stirring unit with a material inlet and a material outlet, a fluidized bed drying and preheating unit, a dioxin catalytic cracking unit, a water washing and desalting unit, an evaporation crystallization salt production unit, and a flue gas treatment unit; the fluidized bed preheating and drying unit, the dioxin catalytic cracking unit, the evaporation crystallization salt production unit, and the flue gas treatment unit also have an air inlet and an air outlet; The material outlet of the mixing and stirring unit is connected to the material inlet of the fluidized bed drying and preheating unit. The mixing and stirring unit is used to mix fly ash, curing agent and catalyst in a set proportion. The material outlet of the fluidized bed preheating and drying unit is connected to the material inlet of the dioxin catalytic cracking unit. The material outlet of the dioxin catalytic cracking unit is connected to the material inlet of the water washing and desalination unit. The material outlet of the water washing and desalination unit is connected to the material inlet of the evaporation crystallization salt production unit. The outlet of the dioxin catalytic cracking unit is connected to the inlet of the fluidized bed preheating and drying unit, the outlet of the fluidized bed preheating and drying unit is connected to the inlet of the evaporation crystallization salt production unit, and the outlet of the evaporation crystallization salt production unit is connected to the inlet of the flue gas treatment unit.

2. The fly ash harmless and resource-based disposal system according to claim 1, characterized in that, The mixing unit includes a fly ash storage bin, a catalyst storage bin, a curing agent storage bin, a metering belt scale, and a mixer. Three metering belt scales are provided, each connected to the outlet of one of the fly ash storage bins, one to the outlet of the catalyst storage bin, and one to the outlet of the curing agent storage bin. The ends of all three metering belt scales are connected to the inlet of the mixer. The outlet of the dedicated mixer forms the material outlet of the mixing unit and is connected to the material inlet of the fluidized bed drying and preheating unit. Three metering belt scales simultaneously feed material into the feed inlet of the mixing machine.

3. The fly ash harmless and resource-based disposal system according to claim 2, characterized in that, The mixing machine includes a material mixing tank and two sets of reamers that are rotatably assembled inside the material mixing tank. The two sets of reamers rotate in opposite directions and have a speed difference.

4. A fly ash harmless and resource-based disposal system according to any one of claims 1-3, characterized in that, The dioxin catalytic cracking unit includes a cracking furnace and a hot blast furnace. The outlet of the hot blast furnace is connected to the inlet of the cracking furnace to heat the cracking furnace. The fluidized bed preheating and drying unit includes a fluidized bed with an inlet and an outlet and a first dust collector. The outlet of the cracking furnace forms the outlet of the dioxin catalytic cracking unit and is connected to the inlet of the fluidized bed. The outlet of the fluidized bed is connected to the inlet of the first dust collector, and the outlet of the first dust collector is connected to the inlet of the evaporation crystallization salt production unit.

5. The fly ash harmless and resource-based disposal system according to claim 4, characterized in that, The evaporation crystallization salt production unit includes an evaporator and a sodium chloride storage tank and a potassium chloride storage tank connected to the material outlet of the evaporator. The air inlet of the evaporator is connected to the air inlet of the first dust collector.

6. The fly ash harmless and resource-based disposal system according to claim 5, characterized in that, The flue gas treatment unit includes a quench tower, a second dust collector, an alkaline scrubbing tower, an activated carbon adsorption device, and a chimney connected in sequence. The air inlet of the quench tower forms the air inlet of the flue gas treatment unit and is connected to the air outlet of the evaporator. The exhaust outlet of the chimney forms the air outlet of the flue gas treatment unit.

7. The fly ash harmless and resource-based disposal system according to claim 6, characterized in that, The first dust collector and the second dust collector are either bag filters or cyclone dust collectors.

8. A fly ash harmless and resource-based disposal system according to any one of claims 1-3, characterized in that, The water washing and desalination unit includes multiple stages of water washing devices and equalization tanks connected in sequence. The water washing devices are used to wash the fly ash after dioxin removal to obtain a washing solution containing sodium chloride and potassium chloride salts. Each stage of the water washing device has a washing solution inlet, a washing solution outlet, a material inlet, and a material outlet. The material inlet of the first stage water washing device is connected to the material outlet of the dioxin catalytic cracking unit. The material inlet of the first stage water washing device is also connected to a first reagent addition device for adding alkaline salt solution. In adjacent stages of water washing devices, the material outlet of the previous stage water washing device is connected to the material inlet of the next stage water washing device, and the washing solution outlet of the next stage water washing device is connected to the washing solution inlet of the previous stage water washing device. The washing solution inlet of the last stage water washing device is used to connect to a water supply source, and the material outlet of the last stage water washing device is used to connect to a resource utilization device for resource utilization of wet ash. The outlet of the first-stage washing device is connected to the equalization tank, which is connected to a second agent addition device for adding pH adjusting agents to the equalization tank to adjust the pH value of the washing solution.

9. A method for the harmless and resource-based disposal of fly ash, characterized in that, The fly ash harmless and resource-based disposal system according to any one of claims 1-8 includes the following steps: The fly ash, curing agent and catalyst in a set ratio are mixed and stirred in a mixing unit, and the mixture after mixing is preheated and dried by a fluidized bed drying and preheating unit to remove water vapor from the mixture. Dioxins are removed from fly ash via a dioxin catalytic cracking unit. The fly ash after dioxin removal is washed with water in the water washing and desalination unit to obtain a washing solution containing sodium chloride and potassium chloride salts, and the wet ash obtained after water washing is utilized for resource recovery. The washing liquid containing sodium chloride and potassium chloride is evaporated and crystallized in stages through the evaporation crystallization salt production unit to obtain sodium chloride and potassium chloride. The flue gas generated by the dioxin catalytic cracking unit is treated by the flue gas treatment unit and then discharged in compliance with standards. The heat source required for the fluidized bed drying and preheating unit comes from the flue gas of the dioxin catalytic cracking unit, and the heat source required for the evaporation crystallization salt production unit comes from the flue gas preheated by the fluidized bed drying and preheating unit.

10. A method for the harmless and resource-based disposal of fly ash according to claim 9, characterized in that, The pyrolysis temperature range of the dioxin catalytic cracking unit is 400℃-600℃, the flue gas temperature range of the flue gas inlet of the fluidized bed equipment is 200℃-400℃, and the flue gas temperature range of the inlet of the evaporation crystallization salt production unit is 200℃-300℃.

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