A household garbage incineration fly ash resource treatment system

Abstract

The utility model provides a kind of household garbage incineration fly ash resource processing system, it is related to raw ash and chelate solidified fly ash processing technical field, including: pretreatment system, low-temperature pyrolysis system, multi-effect cascade countercurrent water washing system, water washing liquid purification treatment system and evaporative cooling crystallization system, raw ash and chelate solidified fly ash is crushed after pretreatment system, after drying, it is sent into low-temperature pyrolysis system, realizes the decomposition detoxification of dioxin in fly ash and realizes up-to-standard discharge after pyrolysis waste gas treatment;Fly ash treated by low-temperature pyrolysis system is transported to multi-effect cascade countercurrent water washing system and is washed out to obtain water washing liquid;Water washing liquid purification treatment system further removes heavy metal ions, calcium and magnesium ions in water washing liquid, and then filters to obtain filter precipitate and solution;Evaporative cooling crystallization system circulates heat steaming, flash cooling crystallization to the solution after purification, to realize the effective separation and recovery of sodium salt and potassium salt in high-salt water washing liquid.

Description

Technical Field

[0001] This utility model relates to the field of resource utilization technology for fly ash from municipal solid waste incineration, and specifically to a resource utilization system for fly ash from municipal solid waste incineration. Background Technology

[0002] my country has a large volume of municipal solid waste, which is growing rapidly. Incineration power generation has become the most important means of municipal solid waste disposal in my country. Fly ash is the ash collected by the flue gas purification system of municipal solid waste incineration facilities and the bottom ash that settles at the bottom of the flue and chimney. It is a powdery substance with a relatively light density and fine particle size collected in flue gas ducts, flue gas purification devices, cyclone separators and bag filters. Because the incineration of municipal solid waste produces a variety of secondary pollutants, including heavy metals, dioxins and soluble chlorides, these pollutants usually accumulate in fly ash, resulting in high heavy metal leaching and high dioxin toxicity. It is listed in the "National Hazardous Waste List" (waste category: HW18-incineration residue) and needs to undergo chelation solidification treatment (adding 2-5% chelating agent and 25-30% water to fly ash) to fix the heavy metal ions in fly ash before landfilling.

[0003] Given the environmental risks of fly ash, and the fact that the traditional harmless disposal route of chelating and solidifying fly ash before sending it to municipal solid waste landfills consumes a large amount of land resources and is difficult to recycle, promoting the development of safe and efficient fly ash harmless disposal technology is an urgent need for ecological and environmental management. In addition to harmful substances, fly ash also contains approximately 70% calcium, silicon, aluminum, iron, magnesium, and other building material components, and approximately 25% soluble sodium, potassium, and chloride salts. High-value recycling of these resources is also a major requirement for achieving sustainable development. Therefore, this utility model proposes a municipal solid waste incineration fly ash resource utilization system that can treat both raw ash and chelated and solidified fly ash, to achieve "zero landfill" and resource recycling of fly ash, promoting the construction of "zero-waste cities." Utility Model Content

[0004] Therefore, the technical problem to be solved by this utility model is to overcome the above-mentioned defects and thus provide a system for the resource utilization of fly ash from municipal solid waste incineration.

[0005] To address the aforementioned problems, this utility model provides a system for the resource recovery and treatment of fly ash from municipal solid waste incineration, comprising: The system comprises a pretreatment system, a low-temperature pyrolysis system, a multi-effect cascade countercurrent water washing system, a water washing liquid purification system, and an evaporation cooling crystallization system. The output end of the pretreatment system is connected to the low-temperature pyrolysis system. The raw ash and the chelated solidified fly ash are crushed and dried by the pretreatment system and then sent to the low-temperature pyrolysis system to achieve the decomposition and detoxification of dioxins in the fly ash and to achieve the standard emission after the pyrolysis exhaust gas is treated. The output end of the low-temperature pyrolysis system is connected to the multi-effect cascade countercurrent water washing system. The fly ash processed by the low-temperature pyrolysis system is transported to the multi-effect cascade countercurrent water washing system for chloride salt elution. The system is filtered using a combination of cascade countercurrent water washing, horizontal screw centrifugation, and ultra-high pressure plate and frame filter press to obtain the washing liquid. The output end of the multi-effect cascade countercurrent water washing system is connected to the water washing liquid purification system. The water washing liquid is sent into the water washing liquid purification system to further remove heavy metal ions, calcium and magnesium ions, and then filtered to obtain filtered precipitate and solution. The output of the washing liquid purification system is connected to the evaporation cooling crystallization system. The purified washing liquid solution is circulated through the evaporation cooling crystallization system for hot evaporation and flash evaporation cooling crystallization to achieve effective separation and recovery of sodium and potassium salts in the high-salt water washing liquid.

[0006] Preferably, the pretreatment system includes: a crushing mechanism, a drying mechanism, and a particle size / moisture content detection mechanism. The input end of the crushing mechanism receives raw ash and fly ash from chelated solidification. The output end of the crushing mechanism is connected to the input end of the drying mechanism, and the output end of the drying mechanism is connected to the particle size / moisture content detection mechanism.

[0007] Preferably, the particle size / moisture content detection mechanism is connected to the crushing mechanism and the drying mechanism respectively through a conveying mechanism, so as to convey fly ash with substandard particle size and substandard moisture content to the crushing mechanism and the drying mechanism respectively.

[0008] Preferably, the low-temperature pyrolysis system includes a low-temperature pyrolysis furnace, the low-temperature pyrolysis furnace being connected to a waste gas treatment system, the waste gas treatment system being used to treat the flue gas generated during pyrolysis.

[0009] Preferably, the multi-effect cascade countercurrent water washing system includes: a two-stage fly ash water washing system, each stage of the fly ash water washing system including: a feeding water-ash mixing and washing mechanism, an ultrasonic rinsing mechanism, a catalytic oxidation mechanism, an electrolysis mechanism, and a horizontal screw centrifuge with plate and frame filter press mechanism connected in sequence. Each feeding water-ash mixing and washing mechanism is connected to an external water pipeline, and each centrifuge with plate and frame filter press mechanism conveys the fly ash treatment product to the outside through a slurry conveying mechanism.

[0010] Preferably, the water washing liquid purification system includes: a heavy metal removal mechanism, a decalcification and demagnesium removal mechanism, a filtration mechanism, and a greywater tank connected in sequence.

[0011] Preferably, the evaporation cooling crystallization system includes: an evaporation crystallization mechanism and a flash cooling crystallization mechanism. The input end of the evaporation crystallization mechanism is connected to the greywater tank. Sodium chloride is precipitated after evaporation crystallization in the evaporation cooling crystallization system. The condensate generated by the evaporation crystallization mechanism is recycled to the multi-effect countercurrent water washing system. The evaporation mother liquor of the evaporation crystallization mechanism precipitates potassium chloride after passing through the flash cooling crystallization mechanism. The flash cooling mother liquor generated by the flash cooling crystallization mechanism is recycled back to the evaporation crystallization mechanism for circulation.

[0012] The waste incineration fly ash resource utilization system provided by this utility model has the following beneficial effects: This invention comprehensively and efficiently treats raw fly ash and chelated solidified fly ash through a series of coherent and synergistic treatment steps, including pretreatment, low-temperature pyrolysis, multi-effect cascade countercurrent water washing, water washing liquid purification, and evaporative cooling crystallization. Compared to single treatment methods or simple combination treatment systems, it can more thoroughly solve the problem of multiple pollutants in fly ash, achieving harmless and resource-based treatment of fly ash. During the treatment process, water resources are recycled, and fly ash treatment products and salt products are recovered. The products of fly ash after pyrolysis and water washing are recycled as general solid waste and can be used in the construction industry. The condensate generated by the evaporative cooling crystallization system is reused in the multi-effect cascade countercurrent water washing system, reducing the consumption of fresh water resources. At the same time, sodium chloride and potassium chloride crystals are precipitated through evaporative crystallization and flash cooling crystallization, respectively, realizing the recovery and utilization of salts, reducing treatment costs, improving resource utilization, and conforming to the concept of sustainable development. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the fly ash resource utilization system of this utility model; Figure 2 This is a schematic diagram of the evaporation cooling crystallization system of this utility model; Figure 3 This is a schematic diagram of the multi-effect cascade countercurrent water washing system of this utility model.

[0014] Figure label: 1. Crushing mechanism; 2. Drying mechanism; 3. Particle size / moisture content detection mechanism; 4. Low temperature pyrolysis system; 5. Multi-effect cascade countercurrent water washing system; 6. Waste gas treatment system; 7. Heavy metal removal mechanism; 8. Decalcification and demagnesification mechanism; 9. Greywater tank; 10. Filtration mechanism; 11. Evaporation cooling crystallization system. Detailed Implementation

[0015] like Figure 1-3 As shown, this utility model provides a system for the resource utilization of fly ash from municipal solid waste incineration, which includes: The system comprises a pretreatment system, a low-temperature pyrolysis system 4, a multi-effect cascade countercurrent water washing system 5, a water washing liquid purification system, and an evaporation cooling crystallization system 11. The output end of the pretreatment system is connected to the low-temperature pyrolysis system 4. The raw ash and the chelated solidified fly ash are crushed and dried by the pretreatment system and then sent to the low-temperature pyrolysis system 4 to achieve the decomposition and detoxification of dioxins in the fly ash and to achieve the standard emission after the pyrolysis exhaust gas is treated. The output end of the low-temperature pyrolysis system 4 is connected to the multi-effect countercurrent water washing system 5. The fly ash processed by the low-temperature pyrolysis system 4 is transported to the multi-effect countercurrent water washing system 5 for chloride elution. The water washing solution is obtained by using a countercurrent water washing system (including ultrasonic / catalytic oxidation / electrolysis steps) plus horizontal screw centrifugation and ultra-high pressure plate and frame filter press mode. The output end of the multi-effect cascade countercurrent water washing system 5 is connected to the water washing liquid purification system. The water washing liquid is sent into the water washing liquid purification system to further remove heavy metal ions, calcium and magnesium ions, and then filtered to obtain filtered precipitate and solution. The output of the washing liquid purification system is connected to the evaporation cooling crystallization system 11. The purified washing liquid solution undergoes cyclic hot evaporation and flash evaporation cooling crystallization through the evaporation cooling crystallization system 11 to achieve effective separation and recovery of sodium and potassium salts in the high-salt water washing liquid. Figure 1-3 As shown, it includes a pretreatment system, a low-temperature pyrolysis system 4, a multi-effect cascade countercurrent water washing system 5, a water washing liquid purification system, and an evaporation cooling crystallization system 11. The pretreatment system is for the raw ash from municipal solid waste incineration power plants and the fly ash from municipal solid waste landfills after chelation and solidification. Before resource recovery, the ash needs to be pretreated. After crushing and drying, the pretreatment system sends the ash to the low-temperature pyrolysis system 4. The low-temperature pyrolysis system 4 is used to decompose and detoxify dioxins in the fly ash and to treat the pyrolysis exhaust gas to achieve compliant emissions. The multi-effect cascade countercurrent water washing system 5 is used to wash away chlorides in the fly ash, employing a cascade countercurrent... The washing solution is obtained by filtration using a combination of running water washing (including ultrasonic / catalytic oxidation / electrolysis steps), horizontal screw centrifugation, and ultra-high pressure plate and frame filtration. A washing solution purification system further removes heavy metal ions, calcium and magnesium ions before filtration to obtain precipitate and solution. An evaporation-cooling crystallization system 11 separates and recovers sodium and potassium salts from the washing solution. The purified solution undergoes cyclic hot evaporation and flash evaporation-cooling crystallization in the evaporation-cooling crystallization system 11 to effectively separate and recover sodium and potassium salts from the high-salt water washing solution. These systems are sequentially connected and work collaboratively to effectively treat raw ash and chelated solidified fly ash, achieving dioxin decomposition and detoxification, heavy metal removal, and effective separation and recovery of fly ash treatment products and soluble chloride products.

[0016] In some embodiments, the pretreatment system includes: a crushing mechanism 1, a drying mechanism 2, and a particle size / moisture content detection mechanism 3. The input end of the crushing mechanism 1 receives raw ash and fly ash from chelated solidification. The output end of the crushing mechanism 1 is connected to the input end of the drying mechanism 2, and the output end of the drying mechanism 2 is connected to the particle size / moisture content detection mechanism 3. Figure 1 As shown, the crushing mechanism 1 is commercially available. It crushes the raw fly ash and chelated solidified fly ash lumps that have hardened due to moisture absorption to a particle size of <1cm. This effectively avoids dead zones in subsequent processing caused by the hardening of raw fly ash and the clumping after chelation solidification, ensuring sufficient heat penetration into the fly ash during subsequent pyrolysis, thereby guaranteeing the stability and consistency of the overall treatment effect. The drying mechanism 2 is also commercially available. It needs to dry the crushed fly ash, controlling its moisture content to <10%. This is because 25%-30% water needs to be added during the chelation solidification process. Drying by the drying mechanism 2 prevents excessive moisture from consuming a large amount of heat for evaporation, which would slow down the rate at which the target temperature is reached during pyrolysis, affecting the completeness of the pyrolysis reaction. Furthermore, the moisture content... Excessive moisture content can lead to uneven temperature distribution during pyrolysis, affecting the stability of the process. Simultaneously, the combination of moisture and acidic gases generated during pyrolysis forms an acidic solution, corroding the metal components of the equipment and shortening its lifespan. Particle size / moisture content testing equipment is commercially available. The particle size must be verified to meet the standard requirement of <1cm, and the moisture content must be confirmed to be controlled below 10%. If either indicator fails to meet the standard, the batch of fly ash must be returned to the corresponding process (particle size failure to meet the standard returns to the crushing stage, moisture content failure returns to the drying stage) for reprocessing until both indicators meet the feed requirements for subsequent pyrolysis. The pretreatment system can handle both chelated and solidified fly ash and raw fly ash, offering greater adaptability.

[0017] In some embodiments, the particle size / moisture content detection mechanism 3 is connected to the crushing mechanism 1 and the drying mechanism 2 respectively via a conveying mechanism, so as to convey fly ash with substandard particle size and substandard moisture content to the crushing mechanism 1 and the drying mechanism 2 respectively. For example... Figure 1-3 As shown, the particle size / moisture content detection mechanism 3 is connected to the crushing mechanism 1 and the drying mechanism 2 respectively through a conveying mechanism, which can be a screw conveyor, so that particles that do not meet the size standard are returned to the crushing stage and particles that do not meet the moisture content standard are returned to the drying stage.

[0018] In some embodiments, the low-temperature pyrolysis system 4 includes a low-temperature pyrolysis furnace, the low-temperature pyrolysis furnace being pipe-connected to a waste gas treatment system 6, the waste gas treatment system 6 being used to treat the flue gas generated during pyrolysis. For example... Figure 1As shown, commercially available low-temperature pyrolysis furnaces are used. Crushed and dried fly ash is fed into the furnace, which is filled with nitrogen to maintain an inert, oxygen-free atmosphere. Indirect heating with natural gas is used to raise the temperature to 300-400℃ and maintain it for 60-90 minutes. During low-temperature pyrolysis, the phenyl precursor of dioxin molecules in the fly ash undergoes dechlorination / degradation. C-Cl bonds, CC bonds, and other chemical bonds break under thermal action, which is the initial step of degradation, making the molecular structure unstable and creating conditions for subsequent reactions. The broken chemical bonds trigger dechlorination and ring-opening reactions, ultimately decomposing into small molecules such as carbon dioxide (CO2) and hydrogen chloride (HCl). This solves the environmental impact of persistent organic pollutants and ultimately achieves the decomposition and detoxification of dioxins in fly ash. The dioxin concentration in the pyrolysis products is consistently less than 50 ng TEQ / kg, which meets the requirements of the "Technical Specification for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (Trial)" (HJ1134-2020). The flue gas generated during pyrolysis is treated to remove particulate matter and pollutants such as CO, NO, NO2, SO2, and HCl. The removed dust is returned to the low-temperature pyrolysis furnace, and the exhaust gas achieves standard emission (the emission limit for dioxin concentration is less than 0.5 ng TEQ / Nm3, which meets the requirements of the "Standard for Pollution Control of Hazardous Waste Incineration" (GB18484-2020)). The exhaust gas treatment can be as follows: the flue gas first enters a spray tower, where it is sprayed and washed with a spray liquid (such as sodium hydroxide solution) to remove acidic gases and some dust. Then, the flue gas enters an activated carbon adsorption device, where the adsorption of activated carbon further removes organic pollutants and odors. Finally, the flue gas enters a bag filter, where the filter bags remove the remaining dust, and the exhaust gas is discharged into the atmosphere through a chimney after meeting the emission standards.

[0019] In some embodiments, the multi-effect cascade countercurrent water washing system 5 includes: a two-stage countercurrent fly ash water washing system, each stage of the fly ash water washing system including: a feed water-ash mixing and washing mechanism, an ultrasonic rinsing mechanism / catalytic oxidation mechanism / electrolysis mechanism, and a horizontal screw centrifuge with plate and frame filter press mechanism connected in sequence. Each feed water-ash mixing and washing mechanism is connected to an external water pipeline, and each centrifuge with plate and frame filter press mechanism conveys the fly ash treatment product to the outside through a slurry conveying mechanism. Figure 1-3As shown, the multi-effect cascade countercurrent water washing system adopts a two-stage countercurrent fly ash water washing system; the water-ash ratio is controlled at 1.5-2:1 at room temperature. Each stage of the fly ash water washing system includes a feed water-ash mixing and washing mechanism, an ultrasonic rinsing mechanism / catalytic oxidation mechanism / electrolysis mechanism, and a horizontal screw centrifuge with plate and frame filter press mechanism connected in sequence. The feed water-ash mixing and washing mechanism uses a mixing tank to fully mix fly ash and water to form slurry. The feed water-ash mixing and washing mechanism of the first-stage fly ash water washing system is also connected to an external water pipeline. The ultrasonic rinsing mechanism is equipped with an ultrasonic rinsing tank, an ultrasonic generator, and a transducer, which can generate high-frequency ultrasonic waves to enhance the water washing and dechlorination effect. The centrifuge with plate and frame filter press mechanism... The plate and frame filter press unit consists of a horizontal screw centrifuge and an ultra-high pressure plate and frame filter press, used for solid-liquid separation of the washed slurry; the catalytic oxidation unit and the electrolysis unit are auxiliary units of the washing system to remove organic matter from the washing liquid and improve the washing and desalination efficiency; each feed water-ash mixing and washing unit is connected to an external water pipeline for supplementing the washing water; each centrifugal plate and frame filter press unit conveys the fly ash treatment product to the outside through a slurry conveying mechanism (such as a screw pump); the fly ash treated by the low-temperature pyrolysis system 4 is conveyed to the feed water-ash mixing and washing unit of the first-stage fly ash washing system by a screw conveyor; in the mixing tank, fly ash and water are mixed in proportion to form slurry; ash The slurry is pumped to an ultrasonic rinsing tank. Inside the tank, the ultrasonic waves facilitate the separation of soluble chlorides from the fly ash, improving the washing effect. The washed slurry flows out of the ultrasonic rinsing tank and enters a centrifugal and plate-and-frame filter press. First, a horizontal screw centrifuge performs preliminary solid-liquid separation; the separated liquid enters subsequent processing, while the solids undergo further dewatering in an ultra-high pressure plate-and-frame filter press. The resulting washed fly ash is then conveyed via a slurry conveying mechanism to the feed water-ash mixing and washing mechanism of the second-stage fly ash washing system. The liquid from the first-stage washing is further treated by a catalytic oxidation and electrolysis mechanism before being transported via pipeline to the washing liquid purification system. The first stage is a chemical treatment system; the second stage water washing system operates in the same manner as the first stage, using the ash from the first stage water washing system and fresh water for washing. The treated fly ash is temporarily stored after washing, and the washing liquid is returned to the feed water-ash mixing and washing mechanism of the first stage water washing system for recycling. After two stages of washing, the resulting washing liquid is transported to the washing liquid purification system through pipelines. This application ensures both the dispersion of ash during the washing process and efficient solid-liquid separation, thereby improving the salt elution rate and reducing the water-ash ratio. The washing process can remove more than 95% of chloride ions and more than 70% of potassium and sodium ions. After the washing process, the water content in the fly ash is ≤30%, and the chloride content is ≤1%.

[0020] In some embodiments, the water washing liquid purification system includes: a heavy metal removal mechanism 7, a decalcification and demagnesification mechanism 8, a filtration mechanism 10, and a greywater tank 9 connected in sequence. For example... Figure 1-3As shown, the washing liquid purification system includes a heavy metal removal unit 7, a decalcification and demagnesification unit 8, a filtration unit 10, and a greywater tank 9 connected in sequence. The heavy metal removal unit 7 uses chemical precipitation, adding precipitants such as sodium sulfide to cause heavy metal ions in the washing liquid to precipitate and be removed. The decalcification and demagnesification unit 8 uses an inorganic polymeric gelling-precipitant one-step method to remove calcium and magnesium ions, reducing hardness and purifying the chloride solution. The filtration unit 10 uses a multi-media filter to further remove suspended solids and precipitates from the washing liquid. The greywater tank 9 stores the purified solution, providing raw materials for subsequent treatment. The washing liquid from the multi-effect countercurrent washing system first enters the heavy metal removal unit 7. An appropriate amount of sodium sulfide solution is added to the washing liquid, and after stirring and reacting for a period of time, heavy metal ions combine with sulfur ions to form sulfide precipitates. The precipitates are separated by a sedimentation tank, and the supernatant enters the decalcification and demagnesification unit 8. In the decalcification and demagnesification unit 8, calcium and magnesium ions are removed from the washing liquid through a one-step inorganic polymer gelling-precipitant process, reducing hardness and lowering the calcium content in the solution to below 10 mg / L and the total hardness to below 20 mg / L. After decalcification and demagnesification, the washing liquid enters the filtration unit 10, where a multi-media filter removes residual suspended solids and precipitates, yielding a pure solution. Finally, the solution enters the greywater tank 9 for storage, awaiting further processing in the evaporation cooling crystallization system 11.

[0021] In some embodiments, the evaporative cooling crystallization system 11 includes an evaporative crystallization mechanism and a flash cooling crystallization mechanism. The input end of the evaporative crystallization mechanism is connected to the greywater tank 9. After evaporative crystallization, sodium chloride is precipitated in the evaporative cooling crystallization system 11. The condensate generated by the evaporative crystallization mechanism is recycled to the multi-effect countercurrent water washing system. The evaporation mother liquor from the evaporative crystallization mechanism precipitates potassium chloride after passing through the flash cooling crystallization mechanism. The flash cooling mother liquor generated by the flash cooling crystallization mechanism is recycled back to the evaporative crystallization mechanism for circulation. Figure 1-3As shown, after the washing liquid is purified, sodium and potassium salts are separated by high-temperature sodium precipitation, low-temperature potassium precipitation, and mother liquor recycling. Based on the different solubilities of potassium chloride and sodium chloride in the solution at different temperatures, evaporation is first carried out in a sodium chloride evaporator crystallizer at 100℃, concentrating the solution to a certain concentration (controlled not to exceed the concentration point for potassium chloride precipitation), crystallizing out sodium chloride, which is then separated by centrifugation to obtain sodium chloride as a byproduct. The evaporated condensate is reused in a multi-effect countercurrent washing system. Then, the mother liquor is discharged from the evaporator crystallizer and sent to a two-stage flash crystallizer for flash cooling, cooling and crystallizing out potassium chloride, which is then separated by centrifugation to obtain potassium chloride as a byproduct. Part of the potassium chloride mother liquor is returned to the sodium chloride evaporator crystallizer for circulating hot evaporation-flash cooling crystallization to improve the recovery rate of potassium and sodium salts. Part of the mother liquor is sent to a mother liquor drying device for treatment to obtain mixed salts. This application uses a hot evaporation-flash cooling crystallization process, which can effectively separate and recover salt products from high-salt water washing liquid containing potassium chloride and sodium chloride. The vacuum-controlled process offers more stable technical control, lower energy consumption, and improved salt purity compared to conventional freeze-drying crystallization processes. The produced sodium chloride (NaCl content > 97.5%) meets the requirements for premium grade industrial wet salt in the "Industrial Salt" (GB / T5462-2015) standard; the potassium chloride (K2O content > 58%) meets the requirements for Class II Grade I potassium chloride in the "Potassium Chloride" (GB6549-2011) standard.

[0022] This application employs a series of coherent and synergistic treatment steps, including pretreatment, low-temperature pyrolysis, multi-effect countercurrent water washing, washing liquid purification, and evaporative cooling crystallization, to comprehensively and efficiently treat raw fly ash and chelated solidified fly ash. Compared to single treatment methods or simple combination treatment systems, it can more thoroughly solve the problem of multiple pollutants in fly ash, achieving harmless and resource-based treatment of fly ash. During the treatment process, water resources are recycled, and fly ash treatment products and salt products are recovered. The fly ash, after being treated by the low-temperature pyrolysis system 4 and the multi-effect cascade countercurrent water washing system 5, can be recycled as general solid waste and used as raw material for the production of non-high-temperature building materials such as geopolymer cementitious materials, roadbed water-stabilized materials, concrete admixtures, non-fired bricks, and aerated bricks in the construction industry. The condensate generated by the evaporation cooling crystallization system 11 is reused in the multi-effect cascade countercurrent water washing system, reducing the consumption of fresh water resources. At the same time, through evaporation crystallization and flash cooling crystallization, sodium chloride and potassium chloride crystals are precipitated respectively, realizing the recovery and utilization of salt, reducing treatment costs, improving resource utilization, and conforming to the concept of sustainable development.

[0023] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model. The above description is only a preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this utility model, and these improvements and modifications should also be considered within the protection scope of this utility model.

Claims

1. A system for the resource utilization of fly ash from municipal solid waste incineration, characterized in that, include: The system comprises a pretreatment system, a low-temperature pyrolysis system, a multi-effect cascade countercurrent water washing system, a water washing liquid purification system, and an evaporation cooling crystallization system. The output end of the pretreatment system is connected to the low-temperature pyrolysis system. The raw ash and the chelated solidified fly ash are crushed and dried by the pretreatment system and then sent to the low-temperature pyrolysis system to achieve the decomposition and detoxification of dioxins in the fly ash and to achieve the standard emission after the pyrolysis exhaust gas is treated. The output end of the low-temperature pyrolysis system is connected to the multi-effect cascade countercurrent water washing system. The fly ash processed by the low-temperature pyrolysis system is transported to the multi-effect cascade countercurrent water washing system for chloride salt elution. The system is filtered using a combination of cascade countercurrent water washing, horizontal screw centrifugation, and ultra-high pressure plate and frame filter press to obtain the washing liquid. The output end of the multi-effect cascade countercurrent water washing system is connected to the water washing liquid purification system. The water washing liquid is sent into the water washing liquid purification system to further remove heavy metal ions, calcium and magnesium ions, and then filtered to obtain filtered precipitate and solution. The output of the washing liquid purification system is connected to the evaporation cooling crystallization system. The purified washing liquid solution is circulated through the evaporation cooling crystallization system for hot evaporation and flash evaporation cooling crystallization to achieve effective separation and recovery of sodium and potassium salts in the high-salt water washing liquid.

2. The municipal solid waste incineration fly ash resource utilization system according to claim 1, characterized in that: The pretreatment system includes a crushing mechanism, a drying mechanism, and a particle size / moisture content detection mechanism. The input end of the crushing mechanism receives raw ash and fly ash from chelated solidification. The output end of the crushing mechanism is connected to the input end of the drying mechanism, and the output end of the drying mechanism is connected to the particle size / moisture content detection mechanism.

3. The municipal solid waste incineration fly ash resource utilization system according to claim 2, characterized in that: The particle size / moisture content detection mechanism is connected to the crushing mechanism and the drying mechanism respectively through a conveying mechanism, so as to convey fly ash with substandard particle size and substandard moisture content to the crushing mechanism and the drying mechanism respectively.

4. The municipal solid waste incineration fly ash resource utilization system according to claim 1, characterized in that: The low-temperature pyrolysis system includes a low-temperature pyrolysis furnace, the low-temperature pyrolysis furnace being connected to a waste gas treatment system, the waste gas treatment system being used to treat the flue gas generated during pyrolysis.

5. The municipal solid waste incineration fly ash resource utilization system according to claim 1, characterized in that: The multi-effect cascade countercurrent water washing system includes: a two-stage countercurrent fly ash water washing system. Each stage of the countercurrent fly ash water washing system includes: a feeding water-ash mixing and washing mechanism, an ultrasonic rinsing mechanism, a catalytic oxidation mechanism, an electrolysis mechanism, and a horizontal screw centrifuge with plate and frame filter press mechanism connected in sequence. Each feeding water-ash mixing and washing mechanism is connected to an external water pipeline, and each centrifuge with plate and frame filter press mechanism conveys the fly ash treatment product to the outside through a slurry conveying mechanism.

6. The municipal solid waste incineration fly ash resource utilization system according to claim 1, characterized in that: The water washing liquid purification system includes, in sequence, a heavy metal removal mechanism, a decalcification and demagnesification mechanism, a filtration mechanism, and a greywater tank.

7. The municipal solid waste incineration fly ash resource utilization system according to claim 6, characterized in that: The evaporation cooling crystallization system includes an evaporation crystallization mechanism and a flash cooling crystallization mechanism. The input end of the evaporation crystallization mechanism is connected to the greywater tank. Sodium chloride is precipitated after evaporation crystallization in the evaporation cooling crystallization system. The condensate generated by the evaporation crystallization mechanism is recycled to the multi-effect countercurrent water washing system. The evaporation mother liquor of the evaporation crystallization mechanism precipitates potassium chloride after passing through the flash cooling crystallization mechanism. The flash cooling mother liquor generated by the flash cooling crystallization mechanism is recycled back to the evaporation crystallization mechanism for circulation.

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