A method and system for co-processing fly ash dechlorination and thermal treatment in waste incineration

Abstract

This invention discloses a method and system for co-processing dechlorination and thermal treatment of fly ash during waste incineration, belonging to the field of waste treatment technology. The system provided by this invention includes an incineration system, a leachate system, and a fly ash treatment system. By integrating leachate recycling and waste heat energy utilization, it achieves both the harmless disposal of waste fly ash, realizing the effect of treating waste with waste, and improves the economic efficiency of waste incineration plants, achieving low-cost disposal and resource utilization of waste fly ash. The two-stage dust collector, consisting of a fly ash dust collector and a deacidification dust collector, can separate the waste fly ash into a large amount of usable granulation material and a small amount of unusable material after treatment. This not only reduces the amount of solid waste that the deacidification reaction tower needs to handle and extends its service life, but also allows the deacidification dust collector to collect a small amount of high-chloride-alkali concentration fly ash, preventing the circulation of high-chloride-alkali substances within the incinerator.

Description

Technical Field

[0001] This invention relates to the field of waste treatment technology, specifically to a method and system for co-processing fly ash dechlorination and thermal treatment during waste incineration. Background Technology

[0002] Waste incineration, as an efficient waste treatment method, has successfully achieved multiple goals of waste volume reduction, resource recovery, and harmless disposal, and is widely regarded as the preferred strategy for waste management. However, this process inevitably generates a large number of byproducts, with fly ash accounting for approximately 3% to 5% of the total incineration volume, posing a significant challenge to the treatment process. Furthermore, during the preparation stage before incineration, the natural fermentation of fresh waste in large storage pits generates a large amount of leachate. The amount of leachate generated is influenced by multiple factors, including the diversity of waste composition, climatic conditions, and seasonal changes, and can typically reach 10% to 20% of the incineration volume, further increasing the complexity of the treatment process.

[0003] In the actual operation of waste-to-energy plants, fly ash and leachate are typically treated separately. This approach aims to minimize their impact on the ecological environment through targeted treatment technologies, while exploring the possibilities of resource recycling and reuse to promote the sustainable development of the waste management industry.

[0004] Fly ash from landfills contains high levels of chloride salts, easily leached heavy metal pollutants, and highly toxic dioxins. If not properly disposed of, its potential hazards are extremely serious. These harmful substances not only cause profound damage to the natural ecological environment but may also indirectly threaten human health and food safety through accumulation and transmission within the food chain. Currently, the treatment processes for fly ash can be categorized according to their treatment principles into physicochemical separation, high-temperature treatment, and solidification stabilization treatment. Landfill disposal occupies a large amount of land, and the prevention of toxic substance leaching requires high-quality landfill sites, posing certain risks. Chelation treatment processes lack reliability in terms of environmental indicators. Water washing for cement kiln blending is costly and prone to heavy metal leaching. As for emerging technologies such as fly ash melting, sintering, and medium-temperature thermal decomposition, although they demonstrate promising treatment prospects, they are currently in the demonstration stage and face the dual challenges of high costs and the difficulty of controlling secondary pollutants.

[0005] Leachate, a typical type of complex organic wastewater, is characterized by severe nutrient imbalance and high pollutant loads, particularly significantly high levels of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD5), posing a significant challenge to its treatment. Currently, most waste-to-energy incineration plants employ a comprehensive treatment process chain of "pretreatment + biological treatment + membrane treatment" for leachate. While this process can effectively reduce pollutant concentrations to some extent, the resulting high operating and maintenance costs, as well as the potential for system instability under extremely high pollutant concentrations, are significant factors limiting its widespread application.

[0006] In view of the above, there is an urgent need for a method and system for co-processing fly ash dechlorination and thermal treatment in waste incineration, which can achieve the harmlessness of fly ash, optimize the leachate treatment process, promote the efficient recovery and reuse of resources, and thus reduce the overall treatment cost. Summary of the Invention

[0007] The purpose of this invention is to provide a method and system for co-processing fly ash dechlorination and thermal treatment in waste incineration, in order to solve the aforementioned technical problems. The method or system provided by this invention can achieve the harmless disposal of waste fly ash, realizing the effect of treating waste with waste; and can also achieve low-cost disposal and resource utilization of waste fly ash.

[0008] The present invention solves the above-mentioned technical problems through the following technical solution:

[0009] A waste incineration co-processing fly ash dechlorination and heat treatment system includes an incineration system, a leachate system, and a fly ash treatment system. The incineration system includes a waste incinerator and flue gas treatment equipment. The fly ash treatment system includes a fly ash dust collector, a desulfurization reaction tower, a desulfurization dust collector, a washing tank, a granulator, and a drying device. The leachate system includes a bar screen, a leachate equalization tank, an anaerobic system, a denitrification tank, a nitrification tank, a membrane separation system, and a clear liquid tank. The fly ash dust collector is equipped with a fly ash outlet, a high-temperature flue gas outlet, and a waste heat flue gas outlet. The washing tank is equipped with a liquid inlet, a liquid outlet, a solid inlet, and a solid outlet. The desulfurization reaction tower is equipped with a gas inlet, a gas outlet, and a concentrated liquid inlet. The drying device is equipped with a solid inlet, a gas inlet, and a gas outlet. The membrane separation system is equipped with a purified water outlet and a concentrated liquid outlet.

[0010] The waste incinerator is connected in sequence to the gas inlet and outlet of the deacidification reaction tower via the high-temperature flue gas outlet of the fly ash dust collector, and then to the flue gas treatment equipment via the deacidification dust collector. The fly ash dust collector is equipped with an activated carbon injection device. The fly ash outlet of the fly ash dust collector is connected in sequence to the solid inlet and outlet of the washing tank, and then to the solid inlet of the drying device via the granulator. The waste heat flue gas outlet of the fly ash dust collector is connected to the gas inlet of the drying device, and the gas outlet of the drying device is connected to the waste incinerator. The bar screen is connected in sequence along the leachate flow direction to the liquid inlet and outlet of the washing tank, the leachate regulating tank, the anaerobic system, the denitrification tank, the nitrification tank, and then to the membrane separation system. The concentrate outlet of the membrane separation system is connected to the concentrate inlet of the deacidification reaction tower, and the purified water outlet of the membrane separation system is connected to the clear liquid tank. Both the leachate regulating tank and the anaerobic system are equipped with gas outlets, which are connected to the waste incinerator to provide odorous gas and biogas to the waste incinerator.

[0011] Furthermore, it also includes a sludge treatment system, including a sludge tank and a centrifuge. At the same time, the leachate equalization tank, the anaerobic system and the denitrification tank are all equipped with sludge outlets. The sludge outlets are connected to the centrifuges via the sludge tanks for sludge dewatering and making sludge cakes.

[0012] Furthermore, it also includes a DTRO system, and the membrane separation system is also equipped with a second outlet for the concentrate, which is connected to the clear liquid tank via the DTRO system.

[0013] Furthermore, an activated carbon injection device is installed inside the deacidification reaction tower.

[0014] Furthermore, the flue gas treatment equipment is provided with an SGH system, an SCR system, an induced draft fan, and a chimney in sequence along the flue gas flow direction.

[0015] Furthermore, the membrane separation system is provided with an ultrafiltration system, a nanofiltration system, and a reverse osmosis system in sequence along the flow direction of the permeate.

[0016] A method for co-processing fly ash dechlorination and thermal treatment in waste incineration, specifically including:

[0017] The fermented waste is transported to a waste incinerator, where it is burned to produce incineration products and slag.

[0018] The incineration products are collected by a fly ash dust collector, and the activated carbon injection device adsorbs the dioxins in the incineration products. After adsorption, the chlorine-containing fly ash in the incineration products is transported to a washing tank. At the same time, the leachate from the fermented waste is treated by a bar screen and then transported to a washing tank. The chlorine-containing fly ash is washed with leachate in the washing tank to remove chlorine and heavy metals for the first time, resulting in washed fly ash.

[0019] Slag and washed fly ash are transported to a granulator, and coal gangue is added to granulate the granules and obtain embryos. The embryos are then dried by a drying device and placed on a waste incinerator for burning and collection.

[0020] The first part of the flue gas from the incineration products is passed through the deacidification reaction tower and the deacidification dust collector for a second removal of chlorine and heavy metals, and then transported to the flue gas treatment equipment; the second part of the flue gas is transported to the drying device to exchange heat with the embryo, and after heat exchange, it is transported to the furnace of the waste incinerator as recirculated flue gas.

[0021] The leachate after washing in the washing tank is sequentially transported to the membrane separation system for treatment through the leachate conditioning tank, anaerobic system, denitrification tank, and nitrification tank. After treatment, concentrated liquid and purified water are obtained. The purified water is transported to the clear liquid tank for storage, and the concentrated liquid is transported to the deacidification reaction tower to remove chlorine and heavy metals. At the same time, the odor gas and biogas generated in the leachate conditioning tank and anaerobic system are transported to the waste incinerator for combustion as fuel.

[0022] Furthermore, it also includes:

[0023] The sludge produced from the leachate equalization tank, anaerobic system and denitrification tank is made into sludge cakes after centrifugation and dewatering.

[0024] Furthermore, the concentrate is fed to a deacidification reaction tower to remove chlorine and heavy metals. This can be replaced by feeding the concentrate to a DTRO system to remove chlorine and heavy metals.

[0025] It can also be used to deliver the concentrate to the DTRO system and the deacidification reaction tower for replacement.

[0026] Furthermore, the incineration temperature is 1050–1150℃; the mass ratio of the slag, washed fly ash, and coal gangue generated after incineration is (35–40):(30–35):30; and the diameter of the embryo is 5–10 mm.

[0027] Compared with the prior art, the positive and progressive effects of the present invention are as follows:

[0028] The system for co-processing fly ash dechlorination and heat treatment in waste incineration provided by this invention includes an incineration system, a leachate system, and a fly ash treatment system. By recycling the leachate and utilizing the waste heat energy, it forms an integrated whole, which can not only achieve the harmless disposal of waste fly ash and achieve the effect of treating waste with waste, but also improve the economic benefits of waste incineration plants and realize the low-cost disposal and resource utilization of waste fly ash.

[0029] A fly ash dust collector is installed before the deacidification reaction tower to collect the large amount of chlorine-containing fly ash generated by the waste incineration system. The fly ash dust collector is equipped with an activated carbon injection device, which adsorbs dioxins in the flue gas and acts as a foaming agent for granulation. An acid-removing dust collector is installed after the deacidification reaction tower to treat the CaCl2, CaSO4, dust from the concentrated liquid treatment, and adsorbed activated carbon. This two-stage dust collector system (fly ash dust collector and acid-removing dust collector) separates the waste fly ash into a large amount of usable granulation material and a small amount of unusable material. This not only reduces the amount of solid waste that the deacidification reaction tower needs to handle and extends its service life, but also allows the acid-removing dust collector to collect the small amount of high-chlorine-alkali concentrated fly ash, preventing the circulation of high-chlorine-alkali substances within the incinerator. The gas outlets of the leachate conditioning tank and anaerobic system are connected to the waste incinerator. The generated odor and biogas are sent to the waste incinerator for treatment, which can effectively reduce odor emissions and improve air quality. At the same time, biogas is used as an energy source to achieve resource reuse. It can also improve the efficiency and stability of the overall waste treatment system and reduce the equipment and energy costs for separately treating odor and biogas.

[0030] Furthermore, the deacidification reaction tower is equipped with an activated carbon injection device to ensure the final dioxin emission is limited.

[0031] Furthermore, it also includes a sludge treatment system that sends the dewatered sludge cake to a waste incinerator for processing. This not only reduces the need for landfill space but also enables the energy utilization of sludge through incineration, thereby improving the resource recovery rate.

[0032] Furthermore, it also includes a DTRO system, which can reduce the discharge and treatment volume of concentrate, thereby reducing the burden on the deacidification reaction tower process.

[0033] Furthermore, by combining multi-stage membrane separation technologies, the treatment efficiency and water quality of leachate can be improved, achieving comprehensive and in-depth purification of leachate. Attached Figure Description

[0034] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] Figure 1 This is a system schematic diagram of the present invention;

[0036] The components include: 1. Waste pit; 2. Waste incinerator; 3. Fly ash dust collector; 4. Deacidification reaction tower; 5. Deacidification dust collector; 6. SGH+SCR system; 7. Exhaust fan; 8. Chimney; 9. Chlorine-containing fly ash; 10. Washing tank; 11. Slag; 12. Granulator; 13. Drying device; 14. Bar screen; 15. Leachate equalization tank; 16. Anaerobic system; 17. Denitrification tank; 18. Nitrification tank; 19. Ultrafiltration system; 20. Nanofiltration system; 21. Reverse osmosis system; 22. Clear liquid tank; 23. DTRO system; 24. Activated carbon injection device. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0039] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0041] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0043] The present invention will be further described in detail below with reference to the accompanying drawings. These descriptions are for illustrative purposes only and are not intended to limit the scope of the invention.

[0044] See Figure 1 This invention provides a waste incineration co-processing fly ash dechlorination and heat treatment system, mainly comprising: an incineration system, a leachate system, and a fly ash treatment system. The incineration system mainly includes a waste incinerator 2 and its flue gas treatment equipment; the leachate treatment system includes a bar screen 14, a leachate equalization tank 15, an anaerobic system 16, denitrification tanks 18 and 17, a nitrification tank 18, an ultrafiltration system 19, a nanofiltration system 20, a reverse osmosis system 21, a clear liquid tank 22, and a DTRO system 23; the fly ash treatment system includes a fly ash dust collector 3, a deacidification reaction tower 4, a deacidification dust collector 5, a washing tank 10, a granulator 12, and a drying device 13; the fly ash treatment system, leachate treatment system, and incineration system are integrated through leachate recycling and waste heat energy utilization.

[0045] The fly ash dust collector 3 is equipped with a fly ash outlet, a high-temperature flue gas outlet, and a waste heat flue gas outlet; the water washing tank 10 is equipped with a liquid inlet, a liquid outlet, a solid inlet, and a solid outlet; the deacidification reaction tower 4 is equipped with a gas inlet, a gas outlet, and a concentrated liquid inlet; the drying device 13 is equipped with a solid inlet, a gas inlet, and a gas outlet; and the membrane separation system is equipped with a clean water outlet and a concentrated liquid outlet.

[0046] The waste incinerator 2 is connected sequentially to the gas inlet and outlet of the deacidification reaction tower 4, and then to the deacidification dust collector 5 via the high-temperature flue gas outlet of the fly ash dust collector 3, leading to the flue gas treatment equipment. The fly ash dust collector 3 is equipped with an activated carbon injection device 24. The deacidification dust collector 5 is installed after the deacidification reaction tower 4 to treat the deacidified CaCl2, CaSO4, dust from the concentrated liquid treatment, and adsorbed activated carbon. This two-stage dust collector system separates the waste fly ash into a large amount of usable granulation material and a small amount of unusable material. This significantly reduces the amount of solid waste that the deacidification reaction tower 4 needs to handle, extending the tower's service life. Furthermore, the deacidification dust collector 5 collects the small amount of high-chloride-alkali concentration fly ash, achieving precise removal and preventing the circulation of high-chloride-alkali substances within the incinerator. The activated carbon injected into the fly ash dust collector 3 accounts for 5%-10% of the fly ash volume, adsorbing dioxins in the flue gas and acting as a foaming agent for granulation.

[0047] The fly ash outlet of the fly ash dust collector 3 is sequentially connected to the solid inlet and solid outlet of the washing tank 10, and then to the solid inlet of the granulator 12 and drying device 13. The waste heat flue gas outlet of the fly ash dust collector 3 is connected to the gas inlet of the drying device 13, and the gas outlet of the drying device 13 is connected to the waste incinerator 2. Specifically, the outlet of the granulator 12 is connected to the solid inlet of the drying device 13, the waste heat flue gas is connected to the gas inlet of the drying device 13, and the waste incinerator 2 is connected to the gas outlet of the drying device 13 but not to the solid outlet. The granulator 12 is used to form pellets from the treated waste fly ash, and the drying device 13 is used to dry the pellets. The heat used in this process is provided by the waste heat from the tail flue gas of the waste incinerator 2, improving energy utilization. The flue gas then re-enters the incinerator as recirculated flue gas, further improving the combustion efficiency of the waste incinerator 2.

[0048] The bar screen 14 is sequentially connected along the leachate flow direction to the liquid inlet and liquid outlet of the washing tank 10, the leachate equalization tank 15, the anaerobic system 16, the denitrification tanks 18 and 17, the nitrification tank 18, and finally to the membrane separation system. The concentrate outlet of the membrane separation system is connected to the concentrate inlet of the deacidification reaction tower 4, and the purified water outlet of the membrane separation system is connected to the clear liquid tank 22. Specifically, the liquid inlet of the washing tank 10 is connected to the outlet of the bar screen 14 for receiving landfill leachate; the solids inlet of the washing tank 10 is connected to the fly ash outlet of the fly ash dust collector 3 for receiving landfill fly ash; the liquid outlet of the washing tank 10 is connected to the inlet of the leachate equalization tank 15 for returning the washing liquid to the leachate treatment system; and the solids outlet of the washing tank 10 is connected to the inlet of the granulator 12 for discharging the dechlorinated fly ash. In the washing tank 10, landfill leachate and fly ash are mixed. By utilizing the property of landfill leachate to absorb chloride ions, chloride and heavy metals are removed from the fly ash, saving water resources and reducing pretreatment costs. In addition, by utilizing the well-developed porous structure of the fly ash, suspended solids and small particulate matter in the leachate are adsorbed, reducing pollutants such as color and COD, and reducing subsequent leachate treatment costs.

[0049] Both the leachate equalization tank 15 and the anaerobic system 16 are equipped with gas outlets, which are connected to the waste incinerator 2 to supply odor gas and biogas to the waste incinerator 2. The gas outlets of the leachate equalization tank 15 and the anaerobic system 16 are connected to the waste incinerator 2, and the generated odor gas and biogas are sent to the waste incinerator 2 for treatment. This effectively reduces odor emissions and improves air quality; simultaneously, it utilizes biogas as an energy source, achieving resource reuse; and it also improves the efficiency and stability of the overall waste treatment system, reducing the equipment and energy costs associated with separately treating odor gas and biogas.

[0050] In some specific embodiments of the present invention, a sludge treatment system is also included, comprising a sludge tank and a centrifuge. The leachate equalization tank 15, the anaerobic system 16, and the denitrification tank 1817 are all equipped with sludge outlets. These sludge outlets are connected to the centrifuge via the sludge tank. The generated sludge is dewatered by the centrifuge and formed into sludge cakes, which are then sent to the waste incinerator 2 for further processing. This not only reduces the volume of sludge, facilitating subsequent transportation and storage, but also transforms the sludge into a relatively stable form, making it easier for further processing or utilization. Sending the dewatered sludge cakes to the waste incinerator 2 for processing not only reduces the need for landfill space but also achieves energy utilization of the sludge through incineration, improving resource recovery rates.

[0051] In some specific embodiments of the present invention, a DTRO system 23 is also included. The membrane separation system is also provided with a second outlet for the concentrate, which is connected to the clear liquid tank 22 via the DTRO system 23. This can reduce the discharge and processing volume of the concentrate, thereby reducing the burden on the deacidification reaction tower 4 processing process.

[0052] In certain embodiments of the present invention, the membrane separation system comprises an ultrafiltration system 19, a nanofiltration system 20, and a reverse osmosis system 21 arranged sequentially along the flow direction of the leachate. Each of the ultrafiltration system 19, nanofiltration system 20, and reverse osmosis system 21 is provided with a second outlet for the concentrate. By combining multiple membrane separation technologies, the treatment efficiency and water quality of the leachate are improved, achieving comprehensive and deep purification of the leachate.

[0053] In some specific embodiments of the present invention, an activated carbon injection device 24 is provided inside the deacidification reaction tower 4 to ensure the final dioxin emission is limited.

[0054] In some specific embodiments of the present invention, the flue gas treatment equipment specifically includes an SGH system, an SCR system (SGH+SCR system) 6, an induced draft fan 7, and a chimney 8 arranged sequentially along the flue gas flow direction.

[0055] This invention also provides a method for co-processing fly ash dechlorination and thermal treatment in waste incineration, specifically including:

[0056] Waste is fed into waste pit 1 of the waste-to-energy plant, where it undergoes fermentation and storage for 5-7 days, producing waste with high combustion stability and calorific value, as well as leachate. The waste is then fed into waste incinerator 2, where it is incinerated to produce incineration products and ash 11. The incineration products are collected by fly ash dust collector 3, and activated carbon injection device 24 adsorbs dioxins from the incineration products. After adsorption, chlorine-containing fly ash 9 from the incineration products is transported to washing tank 10. The amount of activated carbon injected accounts for 5%-10% of the mass of chlorine-containing fly ash 9 in the incineration products.

[0057] Meanwhile, the leachate from the fermented waste is processed by the bar screen 14 and then transported to the washing tank 10. The chlorine-containing fly ash 9 is washed in the washing tank 10 with leachate to remove chlorine and heavy metals for the first time, resulting in washed fly ash. The slag 11 and the washed fly ash are transported to the granulator 12, and coal gangue is added for granulation to obtain a pellet. The pellet is then dried by the drying device 13 and placed on the waste incinerator 2 for burning and collection.

[0058] The first part of the flue gas from the incineration products is sequentially passed through the deacidification reaction tower 4 and the deacidification dust collector 5 for a second removal of chlorine and heavy metals, and then transported to the flue gas treatment equipment; the second part of the flue gas is transported to the drying device 13 to exchange heat with the embryo, and after heat exchange, it is transported as recirculated flue gas to the furnace of the waste incinerator 2; the deacidification dust collector 5 is used to treat materials such as CaCl2, CaSO4, and dust after the concentrated liquid treatment after the deacidification reaction tower 4.

[0059] The leachate washed in the washing tank 10 is sequentially transported to the membrane separation system for treatment via the leachate conditioning tank 15, the anaerobic system 16, the denitrification tank 1817, and the nitrification tank 18. After treatment, concentrated liquid and purified water are obtained. The purified water is transported to the clear liquid tank 22 for storage, and the concentrated liquid is transported to the deacidification reaction tower 4 to remove chlorine and heavy metals. At the same time, the odor and biogas generated by the leachate conditioning tank 15 and the anaerobic system 16 are transported to the waste incinerator 2 for combustion as fuel.

[0060] Of course, in some specific embodiments of the present invention, the sludge produced by the leachate equalization tank 15, the anaerobic system 16 and the denitrification tank 1817 is further processed into sludge cakes by centrifugation and dewatering.

[0061] In some specific embodiments of the present invention, the concentrate is fed to the deacidification reaction tower 4 to remove chlorine and heavy metals, which can be replaced by the following method: feeding the concentrate to the DTRO system 23 to remove chlorine and heavy metals.

[0062] In some specific embodiments of the present invention, the concentrate is transported to the deacidification reaction tower 4 to remove chlorine and heavy metals, and can also be transported to the DTRO system 23 and the deacidification reaction tower 4 for replacement.

[0063] In some specific embodiments of the present invention, the incineration temperature is 1050-1150℃; the mass ratio of the slag 11, the washed fly ash and the coal gangue generated after incineration is (35-40):(30-35):30; and the diameter of the embryo is 5-10 mm.

[0064] In summary, the embodiments of the present invention provide a system and method for synergistic dechlorination and thermal treatment of fly ash in a waste incineration plant. The fly ash treatment system, leachate treatment system, and incineration system are integrated through water recycling and waste heat energy utilization. The entire system completes the pretreatment of waste fly ash, removes high-chloride and alkaline solid waste through a deacidification and dust removal device, avoids the enrichment of high-chloride and alkaline fly ash in the incinerator system, achieves clean treatment of waste fly ash and obtains high-value granulated products, and has great promotional value.

[0065] A two-stage dust collector and deacidification reaction tower system can separate waste fly ash into a large amount of usable portion and a high-chlorine-alkali-concentration useless portion. A small amount of useless portion is directly discharged through the deacidification dust collector, forming a virtuous cycle for waste fly ash treatment. Because the pre-flying fly ash dust collector collects a large amount of chlorine-containing fly ash, the amount of fly ash and pollutants that the deacidification reaction tower needs to handle is greatly reduced, extending the tower's service life. Furthermore, the deacidification reaction tower can also serve as a treatment unit for leachate concentrate, further reducing leachate treatment costs. Finally, the activated carbon that has adsorbed dioxins is cleanly burned at high temperature in the furnace along with the granulated preforms, significantly reducing dioxin disposal costs. Regarding water washing and heat treatment, washing the waste fly ash with leachate saves water resources and reduces pretreatment costs. Due to its rich porous structure, fly ash can adsorb difficult-to-treat organic pollutants such as COD in the leachate, reducing subsequent leachate treatment costs. By utilizing the waste heat of flue gas for embryo drying, the energy utilization rate is further improved. Furthermore, the flue gas after heat exchange is used as recirculated flue gas and fed into the waste incinerator, thereby improving the combustion efficiency of the waste incinerator.

[0066] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A waste incineration co-processing fly ash dechlorination and thermal treatment system, characterized in that, The system includes an incineration system, a leachate system, and a fly ash treatment system. The incineration system includes a waste incinerator (2) and flue gas treatment equipment. The fly ash treatment system includes a fly ash dust collector (3), a deacidification reaction tower (4), a deacidification dust collector (5), a water washing tank (10), a granulator (12), and a drying device (13). The leachate system includes a bar screen (14), a leachate regulating tank (15), an anaerobic system (16), a denitrification tank (17), a nitrification tank (18), a membrane separation system, and a clear liquid tank (22). The fly ash dust collector (3) is equipped with a fly ash outlet, a high-temperature flue gas outlet, and a waste heat flue gas outlet. The water washing tank (10) is equipped with a liquid inlet, a liquid outlet, a solid inlet, and a solid outlet. The deacidification reaction tower (4) is equipped with a gas inlet, a gas outlet, and a concentrated liquid inlet. The drying device (13) is equipped with a solid inlet, a gas inlet, and a gas outlet. The membrane separation system is equipped with a clean water outlet and a concentrated liquid outlet. Among them, the waste incinerator (2) is connected in sequence to the gas inlet and gas outlet of the deacidification reaction tower (4), the deacidification dust collector (5), and the flue gas treatment equipment via the high-temperature flue gas outlet of the fly ash dust collector (3). The fly ash dust collector (3) is equipped with an activated carbon injection device (24). The fly ash outlet of the fly ash dust collector (3) is connected in sequence to the solid inlet and solid outlet of the washing tank (10), the granulator (12), and the solid inlet of the drying device (13). The waste heat flue gas outlet of the fly ash dust collector (3) is connected to the gas inlet of the drying device (13), and the gas outlet of the drying device (13) is connected to the waste incinerator (2). The bar screen (14) is connected in sequence to the liquid inlet and liquid outlet of the washing tank (10), the leachate regulating tank (15), the anaerobic system (16), and the denitrification tank (17) along the leachate flow direction. The nitrification tank (18) is connected to the membrane separation system. The concentrated liquid outlet of the membrane separation system is connected to the concentrated liquid inlet of the deacidification reaction tower (4). The purified water outlet of the membrane separation system is connected to the clear liquid tank (22). The leachate conditioning tank (15) and the anaerobic system (16) are both equipped with gas outlets. The gas outlets are connected to the waste incinerator (2) to provide odor and biogas to the waste incinerator (2). The system also includes a sludge treatment system, including a sludge tank and a centrifuge. The leachate conditioning tank (15), the anaerobic system (16) and the denitrification tank (17) are all equipped with sludge outlets. The sludge outlets are connected to the centrifuge via the sludge tank for sludge dewatering and making sludge cakes. The system also includes a DTRO system (23). The membrane separation system is also equipped with a second concentrated liquid outlet, which is connected to the clear liquid tank (22) via the DTRO system (23).

2. The waste incineration co-processing fly ash dechlorination and thermal treatment system according to claim 1, characterized in that, An activated carbon injection device (24) is installed inside the deacidification reaction tower (4).

3. The waste incineration co-processing fly ash dechlorination and thermal treatment system according to claim 1, characterized in that, The flue gas treatment equipment is provided with an SGH system, an SCR system, an induced draft fan (7), and a chimney (8) in sequence along the flue gas flow direction.

4. The waste incineration co-processing fly ash dechlorination and thermal treatment system according to claim 1, characterized in that, The membrane separation system is provided with an ultrafiltration system (19), a nanofiltration system (20) and a reverse osmosis system (21) in sequence along the direction of permeate flow.

5. A method for a waste incineration co-processing fly ash dechlorination and thermal treatment system as described in any one of claims 1 to 4, characterized in that, Specifically, it includes: The fermented waste is transported to the waste incinerator (2), and after incineration, incineration products and slag (11) are generated. The incineration products are collected by the fly ash dust collector (3), and the activated carbon injection device (24) adsorbs the dioxins in the incineration products. After adsorption, the chlorine-containing fly ash (9) in the incineration products is transported to the washing tank (10). At the same time, the leachate of the fermented waste is treated by the bar screen (14) and then transported to the washing tank (10). The chlorine-containing fly ash (9) is washed with leachate in the washing tank (10) to remove chlorine and heavy metals for the first time, and the washed fly ash is obtained. The slag (11) and the washed fly ash are transported to the granulator (12), and coal gangue is added to granulate and obtain a pellet. The pellet is dried by the drying device (13), and the dried pellet is placed on the waste incinerator (2) for burning and collection. The first part of the flue gas in the incineration products is passed through the deacidification reaction tower (4) and the deacidification dust collector (5) for a second removal of chlorine and heavy metals, and then transported to the flue gas treatment equipment; the second part of the flue gas is transported to the drying device (13) to exchange heat with the embryo, and after heat exchange, it is transported to the furnace of the waste incinerator (2) as recirculated flue gas. The leachate washed in the water washing tank (10) is sequentially transported to the membrane separation system for treatment via the leachate conditioning tank (15), anaerobic system (16), denitrification tank (17), and nitrification tank (18). After treatment, concentrated liquid and purified water are obtained. The purified water is transported to the clear liquid tank (22) for storage, and the concentrated liquid is transported to the deacidification reaction tower (4) to remove chlorine and heavy metals. At the same time, the odor and biogas generated by the leachate conditioning tank (15) and anaerobic system (16) are transported to the waste incinerator (2) for combustion as fuel.

6. The method for a waste incineration co-processing fly ash dechlorination and thermal treatment system according to claim 5, characterized in that, Also includes: The sludge produced by the leachate equalization tank (15), anaerobic system (16) and denitrification tank (17) is made into sludge cakes after centrifugation and dewatering.

7. The method for a waste incineration co-processing fly ash dechlorination and thermal treatment system according to claim 5, characterized in that, The concentrate is transported to the deacidification reaction tower (4) to remove chlorine and heavy metals. Alternatively, the concentrate can be transported to the DTRO system (23) to remove chlorine and heavy metals. It can also deliver the concentrate to the DTRO system (23) and the deacidification reaction tower (4) respectively.

8. A method for a waste incineration co-processing fly ash dechlorination and thermal treatment system according to claim 5, characterized in that, The incineration temperature is 1050-1150℃; the mass ratio of the slag (11) generated after incineration, the fly ash after water washing, and the coal gangue is (35-40):(30-35):30; the diameter of the embryo is 5-10 mm.

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