Water washing fly ash back furnace low carbon coupling treatment system and method, incinerator and power plant

Abstract

The application discloses a water-washed fly ash recycling low-carbon coupling treatment system and method, an incinerator and a power plant, which comprises a mixing and rod making unit, a power plant resource cooperation unit and a conveying and recycling unit; after being compressed and filtered by a compression and filtration device, water-washed fly ash is obtained as ash cake, enters the mixing and rod making unit together with biomass powder, is quantitatively fed according to a proportion, is mixed, and is made into a rod body with a certain size. The rod body enters the power plant resource cooperation unit, is conveyed to the front of each incinerator by a main conveyor, and the water content of the rod body is further reduced by using the waste heat of clean flue gas of a chimney. The dried rod body enters the conveying and recycling unit, is accurately weighed and fed at the front of the incinerator, and is sent to the surface of a waste layer of a combustion section of a grate by the way of gas force. The application realizes low-carbon emission, low energy consumption, high efficiency and power plant cooperative coupling treatment of fly ash treatment, and effectively treats and utilizes fly ash.

Description

Technical Field

[0001] This application belongs to the field of solid waste treatment technology, specifically relating to a water-washed fly ash return low-carbon coupled treatment system and method, incinerator and power plant. Background Technology

[0002] Fly ash is a residue collected by flue gas purification systems (such as bag filters and scrubbing towers) during the incineration of municipal solid waste. It is classified as hazardous waste, specifically category HW18 in the National Hazardous Waste List. With the acceleration of urbanization and the advancement of "zero-waste city" construction in my country, municipal solid waste incineration has become the mainstream method for urban waste treatment due to its advantages of volume reduction, harmlessness, and high resource utilization. According to the latest statistics from the Ministry of Ecology and Environment, approximately 13 million tons of fly ash are generated annually nationwide, and this fly ash is rich in heavy metals, dioxins, and soluble salts. Such a massive and continuously generated amount of hazardous waste, if not properly disposed of, can easily cause serious harm to the ecological environment and human health, while also placing unprecedented pressure on the sustainable development of cities.

[0003] Faced with the enormous volume and high hazard of fly ash, national policy has undergone a fundamental shift, moving from "primarily relying on safe landfill" to "strictly restricting landfill while encouraging resource utilization." In February 2025, the Ministry of Ecology and Environment issued the "Guiding Opinions on Further Strengthening the Environmental Governance of Hazardous Waste and Strictly Preventing Environmental Risks" (hereinafter referred to as the "Guiding Opinions"), establishing "phased management targets" for the next five years to 2030. It explicitly states a rigid constraint that by 2030, the proportion of hazardous waste disposed of by landfill nationwide must be controlled within 10%. This target marks the formal entry of my country's hazardous waste management into a new stage of "near-zero landfill." As the single hazardous waste with the largest landfill volume, municipal solid waste incineration fly ash has a profound impact on the fly ash treatment industry. Traditional chelation landfill disposal methods can no longer meet the requirements, making the search for safe, efficient, and economical large-scale disposal and resource utilization pathways urgent.

[0004] Among the various technological approaches to fly ash resource utilization, a general consensus has emerged: water washing pretreatment is an indispensable key step in most advanced resource utilization technologies, with its core purpose being the removal of high chloride and soluble heavy metal content from fly ash. After nearly two decades of research and development both domestically and internationally, fly ash water washing technology has been widely validated in industrial applications in terms of process equipment, water resource recycling, and eluent treatment. Numerous engineering cases demonstrate that water washing can effectively reduce the chloride and soluble heavy metal content of fly ash, ensuring that these two indicators of the washed ash meet the relevant requirements of the Technical Specification for Pollution Control of Municipal Solid Waste Incineration Fly Ash (Trial) (HJ 1134—2020).

[0005] Although water washing pretreatment solves the common problem of chloride salts, existing mainstream technical routes still have their own disadvantages and limitations when it comes to the deep resource utilization or final disposal of fly ash after water washing.

[0006] Cement kiln co-processing: This technology involves calcining washed fly ash in a cement kiln at high temperatures to decompose dioxins and produce cement clinker. Currently, the technology is mature, with numerous operational examples and strong government support. However, due to the downturn in the construction industry and insufficient cement kiln operating rates, the co-processing of fly ash in cement kilns is significantly affected by off-peak production and kiln shutdowns. Furthermore, not all regions have the necessary conditions for co-processing. Simultaneously, the cement industry's own carbon reduction pressures limit its capacity for large-scale waste acceptance.

[0007] High-temperature melting: This technology involves completely melting fly ash into a liquid state at around 1500℃, which then cools to form a dense, glassy slag. Disadvantages include: extremely high energy consumption, resulting in very expensive processing costs; high equipment requirements and insufficient operational stability due to the high operating temperature; the potential for secondary fly ash generation at high temperatures, making flue gas treatment difficult; and low added value of the high-temperature slag, making it difficult for revenue to cover the high processing costs.

[0008] High-temperature sintering: This technical route refers to softening and bonding the surface of fly ash particles at around 1200℃ to form a sintered body with a certain strength (such as ceramsite, lightweight aggregate, etc.). Its disadvantages are similar to those of the high-temperature melting route: higher cost, severe secondary pollution, low product added value, and difficulty in covering processing costs.

[0009] Low-temperature pyrolysis: This technical route typically involves thermally decomposing and destroying organic pollutants such as dioxins in fly ash under oxygen-free conditions of 350-500℃, thus achieving detoxification. The disadvantage is that the treated ash cannot be directly used as a valuable product and still needs to be disposed of or utilized as general solid waste.

[0010] Overall, while water washing pretreatment has established a consensus in fly ash disposal, effectively overcoming the constraints imposed by chloride salts, the resource utilization pathway for post-washing fly ash still faces challenges. Existing mainstream technologies are either limited by stringent collaborative conditions, hampered by high energy costs and complex secondary pollution control, or constrained by the unclear fate of treated byproducts. Summary of the Invention

[0011] In order to solve the problems of high cost, complex system process and unclear product destination in existing fly ash disposal technologies, this application provides a water-washed fly ash return to the furnace low-carbon coupling treatment system and method, incinerator and power plant, to achieve low carbon emissions, low energy consumption and high efficiency in synergistic coupling treatment with power plants, which is applicable to the treatment and disposal of fly ash generated by waste-to-energy plants.

[0012] To achieve the above objectives, this application adopts the following technical solution:

[0013] A low-carbon coupled treatment system for water-washed fly ash returning to the furnace includes a mixing and briquetting unit, a power plant resource coordination unit, and a conveying and returning unit.

[0014] The mixing and briquetting unit includes a filter press, a biomass powder supply device, a mixer, and a briquetting machine. The mixer is connected to both the filter press and the biomass powder supply device. The mixer is used to mix water-washed fly ash and biomass powder at a mass ratio of 90:10-95:5. The mixer is connected to the briquetting machine, which forms the mixture into briquettes.

[0015] The power plant resource coordination unit includes a clean flue gas inlet pipe, a main conveyor, an exhaust fan, and a primary air duct. The main conveyor is used to connect to the briquetting machine. The front end of the main conveyor is connected to the clean flue gas inlet pipe, which is used to introduce clean flue gas into the chimney. The rear end of the main conveyor is connected to the exhaust fan, which is connected to the primary air duct, and the primary air duct is connected to the incinerator.

[0016] The conveying and return unit includes a branch conveyor, a blower, and a feeding gun; the branch conveyor is connected to the main conveyor, the blower is connected to the feeding gun, the feeding gun is installed inside the incinerator, and the rods are delivered to the surface of the waste layer in the combustion section via the blower and the feeding gun.

[0017] As a preferred embodiment, the mixing and briquetting unit further includes a fly ash cake storage silo, a quantitative feeder I, and a conveyor I; the filter press device forms fly ash cakes, the fly ash cake storage silo is used to store the fly ash cakes, the quantitative feeder I is used to weigh the fly ash cakes, and the conveyor I sends the weighed fly ash cakes to the mixing machine.

[0018] As a preferred embodiment, the mixing and briquetting unit also includes an online moisture content detector. When the moisture content of the ash cake is detected to exceed 35%, the material is returned for re-pressing and filtration.

[0019] As a preferred embodiment, the biomass powder supply device includes a biomass powder storage bin, a quantitative feeder II, and a conveyor II; the biomass powder storage bin is used to store biomass powder, the quantitative feeder II is used to weigh the biomass powder, and the conveyor II delivers the weighed biomass powder to the mixer.

[0020] As a preferred embodiment, the conveying and returning unit further includes a pre-furnace rod buffer bin, a pre-furnace quantitative feeder, and a pre-furnace conveyor; the branch conveyor is connected to the pre-furnace rod buffer bin, and the rods are discharged from the bottom of the pre-furnace buffer bin and then enter the pre-furnace quantitative feeder. The pre-furnace quantitative feeder is used to calculate the incinerator's processing capacity and co-firing ratio. The pre-furnace quantitative feeder is sequentially connected to the pre-furnace conveyor, the feeding gun, and the incinerator to feed the rods into the incinerator.

[0021] As a preferred embodiment, the biomass powder includes one or more of sawdust, straw, or fruit shells.

[0022] As a preferred embodiment, the mixing time of the mixer is 10-15 minutes; the briquetting pressure of the briquetting machine is 8-15 MPa, the briquetting diameter is 8mm-15mm, and the length is 20mm-50mm.

[0023] In addition, this application also provides a method for low-carbon coupling treatment of water-washed fly ash returned to the furnace, used in the water-washed fly ash low-carbon coupling treatment system described above, comprising:

[0024] After being filtered by a filter press, the washed fly ash is obtained as ash cake, which is then mixed with biomass powder and fed into a mixing and briquetting machine. After quantitative feeding, mixing and briquetting, briquetting is carried out to form briquettes. The mass ratio of ash cake to biomass powder is 90:10-95:5.

[0025] The rods enter the power plant resource coordination unit. When they are transported in the main conveyor, the residual heat of the flue gas from the chimney is used to further reduce the moisture content of the rods. The moisture, dust or odor released from the rods is drawn into the primary air duct by the exhaust fan and used as combustion air for the incinerator.

[0026] After being dried by the main conveyor, the rods enter the conveying and returning unit, and are pneumatically fed to the surface of the waste layer in the combustion section by the blower and the feeding gun.

[0027] In addition, this application also provides an incinerator, including the low-carbon coupling treatment system for water-washed fly ash return as described above.

[0028] In addition, this application also provides a power plant including the incinerator described above.

[0029] Compared with the prior art, this application has the following advantages:

[0030] This application incorporates a certain proportion of biomass powder into the water-washed fly ash, which can increase the internal temperature of the material after it is returned to the furnace, thus facilitating the efficient desorption of dioxins.

[0031] This application involves shaping the mixture into rods of a certain size and strength, which can prevent fly ash from being directly returned to the furnace, thus avoiding a large amount of dust and increasing the risk of coking in the incinerator.

[0032] This application makes full use of the thermal energy, electrical energy, systems and equipment of waste-to-energy plants, which can further reduce equipment investment and operating costs. It also avoids secondary pollution problems by coupling the flue gas treatment system of the power plant. After the fly ash is treated, it becomes general solid waste and is co-utilized with slag, which solves the problem of product disposal and also reduces carbon emissions caused by separate treatment of fly ash.

[0033] The rods in this application are pneumatically conveyed to the combustion section for dioxin desorption through holes made at appropriate locations on the four walls of the incinerator. This avoids the problem of not being able to remove all the rods after they directly enter the waste pool, and also avoids the problem of insufficient temperature caused by the rods entering from the feed hopper. Attached Figure Description

[0034] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of the application and, together with their description, serve to explain the application, but do not constitute an undue limitation of the application. In the drawings:

[0035] Figure 1 This is a schematic diagram of the low-carbon coupling treatment system for water-washed fly ash returned to the furnace in this application;

[0036] Figure 2 This is a schematic diagram of the low-carbon coupling treatment method for returning water-washed fly ash to the furnace in this application. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0038] In the description of this application, it should be understood that the relationship between the method steps can be sequential or non-sequential, as long as it does not affect the overall technical effect, and therefore should not be construed as a limitation of this application. The following description of this application is merely a description of individual embodiments of the technical solution of this application; other embodiments are not shown in the following description, but this does not mean that this application excludes these other embodiments, nor is the technical solution of this application limited to the specific implementations described below, and the scope of protection of this application is not limited to the specific implementations described below. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0039] It should be noted that if the terms "first," "second," etc., appear in the specification, claims, and accompanying drawings of this application, such descriptions are only used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] In some embodiments, such as Figure 1 As shown, this application provides a low-carbon coupled treatment system for water-washed fly ash returning to the furnace. The system includes a mixing and briquetting unit, a power plant resource coordination unit, and a conveying and returning unit.

[0041] The mixing and briquetting unit includes a filter press 1, a ash cake storage silo 2, a quantitative feeder I4, and a conveyor I5. After the final water washing process, the chlorine content and heavy metal leaching concentration of the fly ash meet the relevant requirements of the Technical Specification for Pollution Control of Municipal Solid Waste Incineration Fly Ash (Trial) (HJ 1134—2020). The fly ash slurry is then pumped into the filter press 1 to form ash cakes. The ash cakes are first stored in the ash cake storage silo 2, weighed by the quantitative feeder I4, and then conveyed to the mixer 9 by the conveyor I5.

[0042] The mixing and briquetting unit also includes a biomass powder storage silo 6, a quantitative feeder II 7, and a conveyor II 8. Because the waste biomass powder contains a certain calorific value, mixing it with washed fly ash in a specific ratio is more conducive to increasing the briquetting temperature in the furnace, thereby facilitating dioxin desorption. The mass ratio of washed fly ash to biomass powder is 90:10-95:5.

[0043] The mixing and briquetting unit also includes a mixer 9, a conveyor III 10, and a briquetting machine 11. Ash cake, biomass powder, wood chips, and other materials are fed into the mixer 9 in a certain proportion. The mixing time is 10-15 minutes. After being mixed evenly, a viscous material is formed. The material is then conveyed to the briquetting machine 11 via the conveyor III 10. The briquetting rods produced have a diameter of 8mm-15mm and a length of 20mm-50mm. The briquetting pressure is 8-15 MPa to ensure that the briquetting rods have a certain strength and prevent them from breaking during the tumbling process in the furnace.

[0044] The mixing and briquetting unit is equipped with an online moisture content detector 3. The appropriate moisture content of the ash cake after filtration by the filter press 1 is between 30% and 35%. If the moisture content exceeds 35%, the excess ash cake is returned for re-filtration. This is to reduce the risk of bridging during subsequent transportation and also to reduce the energy consumption required for evaporating moisture.

[0045] The inner wall of the ash cake storage silo 2 is coated with a smooth coating and is equipped with a mechanical forced arch-breaking device to reduce the risk of bridging due to the high stickiness of the ash cake.

[0046] The quantitative feeder I4 includes, but is not limited to, a belt weighing scale, etc., which serves two purposes: to ensure accurate feeding and to facilitate smooth material discharge.

[0047] The mixer 9 is a continuous feeding and discharging automated mixer 9. Two materials are fed into it at one end. During the mixing process, the materials are continuously conveyed backward. When the materials reach the end, they are mixed evenly and discharged into the next device.

[0048] The briquetting machine 11 includes, but is not limited to, a roller extrusion briquetting machine 11 or a ring briquetting machine 11, with the aim of producing briquettes of uniform size and regular shape.

[0049] The power plant resource coordination unit includes a clean flue gas inlet pipe 12, a main conveyor 13, an exhaust fan 14, a primary air duct 15, a waste incinerator 16, and a flue gas treatment system. The briquettes made from washed fly ash and biomass powder in a certain proportion have a reduced moisture content, but it is still around 30%. If the moisture content can be further reduced before returning them to the furnace, the energy consumption caused by moisture evaporation can be reduced. The temperature of the clean flue gas emitted by the waste-to-energy plant is between 150-200℃, and the heat energy within it is not utilized. Therefore, during the long-distance transport from the briquetting machine 11 to each incinerator 16, clean flue gas is introduced into the chimney to further reduce the moisture content of the briquettes. The evaporated moisture, dust, and odors are then drawn through the exhaust fan 14 to the primary air duct 15 for use as combustion air.

[0050] The flue gas treatment system refers to the system in which pollutants generated after the rods are put into the furnace are treated in conjunction with the original flue gas treatment system of the waste-to-energy plant, which can further reduce equipment investment costs and flue gas treatment operating costs.

[0051] The main conveyor 13 includes, but is not limited to, scraper conveyors, belt conveyors, etc., and needs to be sealed to prevent the rods from being damaged during the conveying process. When the air is ventilated, a slight negative pressure can be formed inside the conveyor to prevent gas and dust from escaping.

[0052] The conveying and return unit includes a branch conveyor 17, a pre-furnace rod buffer bin 18, a pre-furnace quantitative feeder 19, a pre-furnace conveyor 20, a feeding gun 21, and an incinerator 16. Rods exiting the rod-making machine 11 enter the main conveyor 13. Since a waste-to-energy plant often has multiple incinerators 16, a pre-furnace branch conveyor 17 needs to be installed in each incinerator 16, connecting to the main conveyor 13 above and the pre-furnace rod buffer bin 18 below. Rods exiting from the bottom of the buffer bin enter the pre-furnace quantitative feeder 19. This is used to calculate the processing capacity and co-firing ratio of each incinerator 16. The pre-furnace quantitative feeder 19 is sequentially connected to the pre-furnace conveyor 20, the feeding gun 21, and the incinerator 16, sending the rods into the furnace for dioxin treatment.

[0053] The furnace front branch conveyor 17 and furnace front feeder include, but are not limited to, scraper conveyors and belt conveyors, and are intended to prevent the bars from breaking during the conveying process.

[0054] A valve is installed between the main conveyor 13 and each furnace front branch conveyor 17. If a furnace front branch conveyor 17 or its downstream equipment malfunctions, the valve of that branch is closed and the rod is sent to other branches for processing. Several branches serve as backups for each other to ensure sufficient maintenance time.

[0055] The conveying and returning unit is also equipped with an emergency bar storage compartment 22, which is separately connected to the main conveyor 13. If the incinerator 16 is shut down for maintenance, or if several branch lines fail at the same time, there is an emergency storage place for the bars.

[0056] The conveying and returning unit is also equipped with a blower 23, which includes, but is not limited to, a blower or an air compressor. The air duct is connected between the furnace front conveyor 20 and the feeding gun 21. The rods are blown into the incinerator 16 for co-processing by means of pneumatic force.

[0057] The feeding gun 21 is positioned at appropriate locations on the four walls of the waste incinerator 16. The feed rods are not directly fed into the waste pit and mixed with the waste before entering the furnace. This avoids the problem of hazardous waste entering the waste pit if the rods cannot be completely removed. The rods are also not directly fed into the feeding hopper to mix with the waste before entering the furnace. This is because with this feeding method, the rods and waste must pass through a feeding chute and grate to reach the furnace. Since the rods are too small compared to the waste, they easily fall through the waste gaps during the mixing process, ending up in the interlayer between the bottom of the waste layer and the top of the grate. The temperature at this location is too low, typically only around 300°C, making it inefficient to desorb dioxins from the rods. By positioning the feeding gun 21 at appropriate locations on the four walls of the incinerator 16, the rods are pneumatically fed to the surface of the waste layer in the combustion section. This location has a higher temperature, meeting the conditions for dioxin desorption. Furthermore, after passing through the drying section, the waste layer is more compact, making it less likely for the rods to fall through the waste gaps to the lower part. After the rods are incinerated together with the waste, they meet the relevant requirements of the Technical Specification for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (Trial) (HJ 1134—2020), and are transformed from hazardous waste into general solid waste.

[0058] In this application, washed fly ash and biomass powder are mixed in a certain proportion to form rods. In the power plant resource coordination unit, the moisture is further evaporated by the waste heat of the flue gas in the power plant chimney. Then, the rods are pneumatically conveyed to the surface of the waste layer in the grate combustion section through the conveying and return unit, so that the dioxins are desorbed.

[0059] See Figure 1 Specifically, in the mixing and briquetting unit, the outlet of the filter press 1 is connected to the inlet of the ash cake storage silo 2, the outlet of the ash cake storage silo 2 is connected to the inlet of the quantitative feeder I 4, the outlet of the quantitative feeder is connected to the inlet of the conveyor I 5, the outlet of the conveyor I 5 is connected to the inlet of the mixer 9, the outlet of the biomass powder storage silo 6 is connected to the inlet of the quantitative feeder II 7, the outlet of the quantitative feeder II 7 is connected to the inlet of the conveyor II 8, and the outlet of the conveyor II 8 is connected to the inlet of the mixer 9. After the ash cake and biomass powder enter the mixer 9, they are mixed evenly under the action of stirring. The outlet of the mixer 9 is connected to the inlet of the conveyor III 10, and the outlet of the conveyor III 10 is connected to the inlet of the briquetting machine 11. The mixed materials are formed into briquettes with a certain strength and uniform size in the briquetting machine 11.

[0060] In the power plant resource coordination unit, the flue gas diversion pipe introduces clean flue gas from the power plant chimney. The outlet of the flue gas diversion pipe is connected to the inlet of the main conveyor 13. The outlet of the main conveyor 13 is connected to the inlet of the exhaust fan 14. The outlet of the exhaust fan 14 is connected to the primary air duct 15. Moisture, odor, dust, etc. evaporated from the rod are discharged into the primary air duct 15 through the exhaust fan 14 and finally enter the incinerator 16 for treatment.

[0061] In the conveying and returning unit, the inlet of the main conveyor 13 is connected to the outlet of the briquetting machine 11, the outlet of the main conveyor 13 is connected to the inlet of the branch conveyor 17, the outlet of the branch conveyor 17 is connected to the inlet of the briquetting buffer bin 18, the outlet of the briquetting buffer bin 18 is connected to the inlet of the pre-furnace quantitative feeder 19, the outlet of the pre-furnace quantitative feeder 19 is connected to the inlet of the pre-furnace conveyor 20, the outlet of the pre-furnace conveyor 20 is connected to the inlet of the feeding gun 21, the outlet of the blower 23 is connected to the inlet of the feeding gun 21, and the outlet of the feeding gun 21 is connected to the incinerator 16. The briquetting rods are conveyed to the front of each incinerator 16 by the main conveyor 13, and then conveyed to the surface of the waste layer in the grate combustion section of the incinerator 16 for dioxin desorption by quantitative weighing and pneumatic feeding. The main conveyor 13 is also provided with an outlet connected to the inlet of the bar emergency compartment 22, so that there are emergency handling measures in case of furnace shutdown or failure of the conveying return unit.

[0062] In some embodiments, such as Figure 2 As shown, this application provides a method for low-carbon coupling treatment of water-washed fly ash returned to the furnace, comprising:

[0063] (1) After the water-washed fly ash is filtered by the filter press 1, the ash cake is obtained and then mixed with biomass powder into the mixing and briquetting unit. After quantitative feeding, mixing and briquetting according to the proportion, briquetting is made into briquetting rods of a certain size.

[0064] (2) The rod enters the power plant resource coordination unit and is transported to each incinerator 16 via the main conveyor 13. The residual heat of the flue gas in the chimney is used to further reduce the moisture content of the rod.

[0065] (3) The dried rods are sent to the conveying and returning unit. After precise weighing and feeding in front of the furnace, they are sent to the surface of the garbage layer in the combustion section of the grate by pneumatic means for efficient desorption of dioxins.

[0066] The biomass powder mentioned in step (1) is sawdust, straw, fruit shells, etc. The fine powder after grinding is mixed with ash cake. The mass ratio of ash cake to biomass powder is 90:10-95:5. Mixing in a certain amount of high-calorific-value biomass can increase the internal temperature of the rod, which is beneficial to the desorption of dioxins inside.

[0067] Step (1) also involves online detection of the moisture content of the ash cake. The appropriate moisture content range is 30%-35%. If it exceeds 35%, it is returned to the filter press system to further reduce the moisture content. Otherwise, it continues to the next step.

[0068] The mixing process in step (1) is carried out using a fully automatic feed and discharge mixer 9, and the mixing time is 10-15 minutes, which is the entire dwell time from the inlet of the mixer 9 to the discharge of the material.

[0069] In step (1), the mixed material is fed into the briquetting machine 11, and the briquetting rods are 8mm-15mm in diameter and 20mm-50mm in length. The briquetting pressure is 8-15 MPa. These dimensions and pressure settings are to ensure that the briquetting rods have a certain strength and to avoid a large number of breakages during the tumbling process in the furnace.

[0070] In step (2), the rods are dried by the residual heat of flue gas at 150-200°C in the main conveyor 13, and the moisture content is reduced to 10%-25%. The reduced moisture content can reduce the energy loss caused by evaporation of moisture when the rods are returned to the furnace.

[0071] The moisture, dust, odor, etc. released from the rod in step (2) are drawn to the primary air duct 15 by the exhaust fan 14 and treated as combustion air for the incinerator 16.

[0072] The feeding mentioned in step (3) refers to opening holes at appropriate positions on the four walls of the incinerator 16 and sending the rod into the furnace.

[0073] The pneumatic method described in step (3) is to use a blower or compressed air connected between the furnace front conveyor 20 and the feeding gun 21 to blow the rod through the holes to the combustion section of the 16th row of the incinerator for high-temperature desorption of dioxins.

[0074] Combination Figure 2 The specific water-washed fly ash return-to-furnace low-carbon coupling treatment method of this application also includes:

[0075] (1) After the water-washed fly ash is filtered by the filter press 1, a ash cake with a moisture content of 30% is obtained. Then, the ash cake and biomass powder are mixed in the mixer 9 at a mass ratio of 95:5 for 15 minutes to obtain a uniform material. Then, it is put into the briquetting machine 11 with a pressure of 12 MPa, a briquetting length of 30 mm and a diameter of 10 mm to make briquetting rods of uniform size and certain strength.

[0076] (2) During the conveying process of the rod body in the main conveyor 13, clean flue gas with a temperature of 170°C from the chimney is introduced, and the residual heat is used to further reduce the moisture content of the rod body to 15%. Then, the generated moisture, dust, odor and other substances are drawn to the primary air duct 15 by the exhaust fan 14 and put into the furnace for incineration.

[0077] (3) After drying, the rods are conveyed to the surface of the garbage layer in the 16th row of the incinerator by pneumatic conveying under the action of the quantitative feeder, the blower 23 and the feed gun 21 in front of the furnace. The temperature at this position is about 500℃, which can efficiently desorb the dioxins in the rods. The desorbed dioxins and harmful substances are decomposed in the furnace at a temperature above 850℃ under the action of the power plant induced draft fan, and are discharged in compliance with the emission standards under the action of the power plant flue gas treatment system.

[0078] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims. The selected and described embodiments are intended to best elucidate the principles of this application and its practical application, thereby enabling other those skilled in the art to best utilize this application with various modifications suitable for the contemplated specific purpose, as well as the various described embodiments.

Claims

1. A low-carbon coupled treatment system for water-washed fly ash returned to the furnace, characterized in that, This includes a mixing and briquetting unit, a power plant resource coordination unit, and a conveying and returning unit. The mixing and briquetting unit includes a filter press, a biomass powder supply device, a mixer, and a briquetting machine. The mixer is connected to both the filter press and the biomass powder supply device. The mixer is used to mix water-washed fly ash and biomass powder at a mass ratio of 90:10-95:

5. The mixer is connected to the briquetting machine, which forms the mixture into briquettes. The power plant resource coordination unit includes a clean flue gas inlet pipe, a main conveyor, an exhaust fan, and a primary air duct. The main conveyor is used to connect to the briquetting machine. The front end of the main conveyor is connected to the clean flue gas inlet pipe, which is used to introduce clean flue gas into the chimney. The rear end of the main conveyor is connected to the exhaust fan, which is connected to the primary air duct, and the primary air duct is connected to the incinerator. The conveying and return unit includes a branch conveyor, a blower, and a feeding gun; the branch conveyor is connected to the main conveyor, the blower is connected to the feeding gun, the feeding gun is installed inside the incinerator, and the rods are delivered to the surface of the waste layer in the combustion section via the blower and the feeding gun.

2. The low-carbon coupling treatment system for water-washed fly ash returned to the furnace according to claim 1, characterized in that: The mixing and briquetting unit also includes a fly ash cake storage silo, a quantitative feeder I, and a conveyor I; the filter press device makes fly ash into fly ash cakes, the fly ash cake storage silo is used to store fly ash cakes, the quantitative feeder I is used to weigh the fly ash cakes, and the conveyor I sends the weighed fly ash cakes to the mixing machine.

3. The low-carbon coupling treatment system for water-washed fly ash returned to the furnace according to claim 2, characterized in that: The mixing and briquetting unit also includes an online moisture content detector. When the moisture content of the ash cake is detected to exceed 35%, the material is returned for re-pressing and filtration.

4. The low-carbon coupling treatment system for water-washed fly ash returned to the furnace according to claim 1, characterized in that: The biomass powder supply device includes a biomass powder storage bin, a quantitative feeder II, and a conveyor II; the biomass powder storage bin is used to store biomass powder, the quantitative feeder II is used to weigh the biomass powder, and the conveyor II delivers the weighed biomass powder to the mixer.

5. The low-carbon coupling treatment system for water-washed fly ash returned to the furnace according to claim 1, characterized in that: The conveying and returning unit also includes a front-end rod buffer bin, a front-end quantitative feeder, and a front-end conveyor. The branch conveyor is connected to the front-end rod buffer bin. The rods are discharged from the bottom of the front-end buffer bin and then enter the front-end quantitative feeder. The front-end quantitative feeder is used to calculate the incinerator's processing capacity and co-firing ratio. The front-end quantitative feeder is connected in sequence to the front-end conveyor, the feeding gun, and the incinerator to feed the rods into the incinerator.

6. The low-carbon coupling treatment system for water-washed fly ash returned to the furnace according to claim 1, characterized in that: The biomass powder includes one or more of sawdust, straw, or fruit shells.

7. The low-carbon coupling treatment system for water-washed fly ash returned to the furnace according to claim 1, characterized in that: The mixing time of the mixer is 10-15 minutes; the briquetting pressure of the briquetting machine is 8-15 MPa, the briquetting diameter is 8mm-15mm, and the length is 20mm-50mm.

8. A method for low-carbon coupling treatment of water-washed fly ash returned to the furnace, used in the low-carbon coupling treatment system for water-washed fly ash returned to the furnace as described in any one of claims 1-7, characterized in that, include: After being filtered by a filter press, the washed fly ash is obtained as ash cake, which is then mixed with biomass powder and fed into a mixing and briquetting machine. After quantitative feeding, mixing and briquetting, briquetting is carried out to form briquettes. The mass ratio of ash cake to biomass powder is 90:10-95:

5. The rods enter the power plant resource coordination unit. When they are transported in the main conveyor, the residual heat of the flue gas from the chimney is used to further reduce the moisture content of the rods. The moisture, dust or odor released from the rods is drawn into the primary air duct by the exhaust fan and used as combustion air for the incinerator. After being dried by the main conveyor, the rods enter the conveying and returning unit, and are pneumatically fed to the surface of the waste layer in the combustion section by the blower and the feeding gun.

9. An incinerator, characterized in that... Includes the low-carbon coupling treatment system for returning water-washed fly ash to the furnace as described in any one of claims 1-7.

10. A power plant, characterized in that... Including the incinerator as described in claim 9.

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