System for reducing dioxin in household garbage incineration fly ash through organic solvent wet extraction

Abstract

The invention discloses a system for reducing dioxin in household garbage incineration fly ash through wet extraction of an organic solvent, and belongs to the technical field of household garbage incineration fly ash treatment. Comprising a washing device, a filtering device, an extraction device, a suction filtration device and a drying device which are sequentially arranged, the washing device communicates with the filtering device, the washing device comprises a washing barrel, a motor, a rotating shaft impeller, a foot stool and a connecting pipe, the motor is arranged at the top of the washing barrel, and the rotating shaft impeller is rotationally arranged in the washing barrel; the top of the rotating shaft impeller is in transmission connection with a motor; the fly ash sample is soaked in the organic solvent in the extraction device, substances such as dioxin and the like dissolved in the organic solvent in the fly ash sample are separated from the fly ash sample, and the fly ash sample does not need to be heated in the process of separating the dioxin in the fly ash sample, so that the problem of high energy consumption can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of domestic waste incineration fly ash treatment, and in particular to a system for reducing dioxins in domestic waste incineration fly ash by wet extraction using an organic solvent. Background Art

[0002] With the rapid development of my country's social economy, the acceleration of urbanization and the rapid improvement of people's living standards, the domestic waste generated in the process of urban production and life has also increased rapidly. The common method of treating domestic waste is to incinerate it. The heat generated in the process of incinerating domestic waste can be converted into electrical energy. In the process of incinerating domestic waste, some fly ash will also be produced. Although the fly ash contains highly toxic organic carcinogens such as dioxins, etc., the "National List of Hazardous Wastes" lists fly ash as hazardous waste. However, after being treated to eliminate or reduce harmful substances such as chloride salts, dioxins, heavy metals, etc., the fly ash can be sintered to make expanded clay, used as an admixture to make concrete, etc., which has certain economic benefits.

[0003] At present, the technical methods for reducing dioxins in fly ash are mainly divided into physical methods and chemical methods. When using physical methods to reduce dioxins in fly ash, high-temperature sintering, high-temperature melting and other methods are usually used to heat the fly ash to a certain temperature to decompose the dioxins; when using chemical methods to reduce dioxins in fly ash, acid washing and other methods are usually used to use acid solution to remove soluble salts, heavy metals, etc. in the fly ash. After acid washing, the mortar can be made into cement blocks.

[0004] In the prior art, for example, publication number CN113617806B discloses a novel system and method for removing dioxins from waste incineration fly ash, comprising a chemical-mechanical degradation system, a pyrolysis system, and a gas purification system; the chemical-mechanical degradation system is connected to the pyrolysis system; the pyrolysis system is connected to the gas purification system to form a loop; the chemical-mechanical degradation system includes a ball mill; the pyrolysis system includes a pyrolysis furnace; the ball mill is connected to the pyrolysis furnace; the gas outlet of the pyrolysis furnace is connected to the gas purification system; and the ash outlet of the pyrolysis furnace is connected to a first storage bin; a novel method for removing dioxins from waste incineration fly ash comprises fly ash ball milling, fly ash buffering, gas replacement, fly ash pyrolysis, gas purification treatment, and fly ash collection after pyrolysis; the present invention combines a chemical-mechanical method with a pyrolysis method to achieve deep dioxin degradation while reducing energy consumption.

[0005] Publication number CN117415141A discloses a fly ash dioxin pyrolysis system, comprising a fly ash feeding device, a pyrolysis device, and a cooling device. The fly ash feeding device includes a silo and a feed conveyor, the silo's discharge port connected to the feed port of the feed conveyor. The pyrolysis device includes a pyrolysis chamber, a heating device, a pyrolysis stirring device, and an inert gas supply device. The pyrolysis chamber's feed port is connected to the feed port of the feed conveyor. The inert gas supply device is used to supply inert gas to the pyrolysis chamber, and the heating device is used to heat the pyrolysis chamber. The cooling device's feed port is connected to the pyrolysis chamber's discharge port. This system utilizes the heating device to pyrolyze and rapidly cool fly ash in an inert atmosphere, preventing dioxin resynthesis and improving the pyrolysis effect.

[0006] However, in the above scheme, the use of physical pyrolysis to reduce the dioxin content in fly ash consumes a large amount of energy, and the dioxins will transfer from the solid phase to the gas phase during the heating process. The gaseous dioxins will be discharged with the combustion exhaust, causing secondary pollution. When chemical catalysis is used to reduce the dioxin content in fly ash, the catalyst dosage and reaction conditions need to be strictly controlled. If the catalyst dosage and reaction conditions are not properly controlled, new harmful substances will be generated, which will also cause secondary pollution. Summary of the Invention

[0007] The purpose of the present invention is to provide a system for reducing dioxins in fly ash from the incineration of domestic waste by wet extraction using organic solvents, so as to solve the problems of high energy consumption and secondary pollution mentioned in the above background technology.

[0008] To achieve the above-mentioned purpose, the technical solution proposed in the present invention is: a system for reducing dioxins in fly ash from the incineration of domestic waste using wet extraction with an organic solvent, comprising a water washing device, a filtering device, an extraction device, a filtration device and a drying device arranged in sequence, wherein the water washing device is connected to the filtering device.

[0009] Preferably, the water washing device includes a water washing bucket, a motor, a rotating shaft impeller, a tripod and a connecting pipe. The motor is provided on the top of the water washing bucket, and a rotating shaft impeller is provided inside the water washing bucket for rotation. The top of the rotating shaft impeller is connected to the motor transmission. A plurality of tripods are provided at the bottom of the water washing bucket, and a discharge port is provided at the bottom end of the water washing bucket, which is connected to the connecting pipe. The original fly ash sample is provided in the water washing bucket.

[0010] Preferably, the filtering device includes a filter box, an axial flow pump, a filter screen and a drain pipe. An axial flow pump is provided at one end of the filter box, and the axial flow pump is connected to the connecting pipe. A plurality of filter screens are arranged at intervals in the filter box, and a drain pipe is provided at the other end of the filter box. The filter box is provided with a fly ash sample after washing and filtering.

[0011] Preferably, the extraction device includes a condensation barrel, an extraction box and an extraction liquid collection barrel. The condensation barrel is connected to the extraction liquid collection barrel through a steam conduit, and the extraction box is connected to the extraction liquid collection barrel through a siphon. Two condensation water pipes are arranged at upper and lower intervals on the outside of the condensation barrel. A feed port is provided on one side of the extraction box, and a stirring rod is provided in the feed port. A fly ash sample being extracted is provided in the extraction box, and the fly ash sample being extracted is coated inside the filter paper.

[0012] Preferably, the filtration device includes a filtration barrel, a funnel, a safety barrel and a vacuum filter. A funnel is provided on the top of the filtration barrel, the inner wall of the funnel is covered with filter paper, the extracted fly ash sample is covered on the filter paper, the safety barrel is connected to the filtration barrel, and the safety barrel is connected to the vacuum filter.

[0013] Preferably, the drying device includes a vacuum drying box and a nitrogen pipe, the vacuum drying box and the nitrogen pipe are connected, and the vacuum drying box is provided with the fly ash sample and activated carbon treated by the filtration device.

[0014] Beneficial effects: The beneficial effects of the present invention are: 1. The present invention proposes a system for reducing dioxins in fly ash from municipal solid waste incineration using wet extraction with an organic solvent. By soaking a fly ash sample in an organic solvent within an extraction device, dioxins and other organic solvent-soluble substances in the fly ash sample are separated from the fly ash sample. During this dioxin separation process, the fly ash sample does not need to be heated, thereby avoiding the problem of high energy consumption.

[0015] 2. In the system proposed by the present invention for reducing dioxins in fly ash from the incineration of domestic waste using wet extraction with an organic solvent, the original fly ash sample is washed with water by a water washing device, so that water-soluble substances such as chlorine in the fly ash sample are dissolved in water, thereby removing water-soluble substances such as chlorine in the fly ash sample, further improving the subsequent extraction efficiency and extraction quality.

[0016] 3. The present invention proposes a system for reducing dioxins in fly ash from the incineration of domestic waste using wet extraction with an organic solvent. By arranging a condensation drum and a steam conduit in the extraction device, when the organic solvent in the extraction box enters the extraction liquid collection bucket, the organic solvent will evaporate into a gaseous state. The gaseous organic solvent enters the condensation drum through the steam conduit and condenses into a liquid organic solvent in the condensation drum. Finally, the liquid organic solvent returns to the extraction box to soak the fly ash sample. This process can fully utilize the organic solvent, save costs, and avoid waste.

[0017] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 It is a schematic structural diagram of the water washing device and the filtering device of the present invention.

[0019] Figure 2 It is a schematic structural diagram of the extraction device, filtration device and drying device of the present invention.

[0020] Markings in the accompanying drawings: 1. Water washing device; 11. Water washing bucket; 111. Discharge port; 12. Motor; 13. Rotating shaft impeller; 14. Tripod; 15. Connecting pipe; 2. Filtering device; 21. Filter box; 22. Axial flow pump; 23. Filter screen; 24. Drain pipe; 3. Extraction device; 31. Condensation barrel; 32. Extraction box; 33. Extraction liquid collection barrel; 34. Steam duct; 35. Siphon; 36. Condensate pipe; 37. Feed port; 38. Stirring rod; 4. Filtration device; 41. Filtration barrel; 42. Funnel; 43. Safety barrel; 44. Vacuum filter; 5. Drying device; 51. Vacuum drying oven; 52. Nitrogen pipe; 6. Fly ash sample; 7. Filter paper; 8. Activated carbon; 9. Extraction liquid retention barrel. DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. 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, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0023] In the description of this invention, terms such as "greater than," "less than," and "exceed" are understood to exclude the number itself, while terms such as "above," "below," and "within" are understood to include the number itself. The use of terms such as "first" and "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0024] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0025] like Figure 1 、 Figure 2 As shown, a system for reducing dioxins in fly ash from the incineration of domestic waste using wet extraction with an organic solvent is characterized in that it includes a water washing device 1, a filtering device 2, an extraction device 3, a suction filtration device 4 and a drying device 5 arranged in sequence, and the water washing device 1 is connected to the filtering device 2.

[0026] When treating harmful substances such as chloride salts and dioxins in fly ash generated by garbage incineration, the original fly ash sample 6 and water are first placed in a water washing device 1, and the original fly ash sample 6 and water are stirred. This process can wash out water-soluble substances such as chloride salts in the original fly ash sample 6. The original fly ash sample 6 and water in the water washing device 1 are then introduced into a filtering device 2. The filtering device 2 separates the original fly ash sample 6 after water washing from the water, and takes out the fly ash sample 6 in the filtering device 2. The taken out fly ash sample 6 is wrapped in a solvent-resistant filter paper 7. An organic solvent is added to the extraction device 3, and the fly ash sample 6 wrapped in the filter paper 7 is placed in the extraction device 3 for extraction. Harmful substances soluble in organic solvents such as dioxins in the fly ash sample 6 in the extraction device 3 are dissolved in the organic solvent. The extracted fly ash sample 6 is taken out from the extraction device 3 and placed in the filtration device 4. The excess organic solvent in the extracted fly ash sample 6 is separated. Finally, the extracted fly ash sample 6 is placed in a drying device 5 for drying.

[0027] Further optimization scheme, the water washing device 1 includes a water washing bucket 11, a motor 12, a rotating shaft impeller 13, a bracket 14 and a connecting pipe 15. The motor 12 is provided on the top of the water washing bucket 11, and the rotating shaft impeller 13 is rotatably provided inside the water washing bucket 11. The top of the rotating shaft impeller 13 is transmission-connected to the motor 12. A plurality of brackets 14 are provided at the bottom of the water washing bucket 11. A discharge port 111 is provided at the bottom of the water washing bucket 11, and the discharge port 111 is connected to the connecting pipe 15. The original fly ash sample 6 is provided in the water washing bucket 11; After weighing and recording the fly ash sample 6, place it in a water washing bucket 11, add water to the water washing bucket 11, start the motor 12, and the motor 12 drives the rotating shaft impeller 13 to rotate. The rotation of the rotating shaft impeller 13 drives the water and fly ash sample 6 in the water washing bucket 11 to rotate. During this process, the fly ash sample 6 is fully in contact with the water, so that the chlorine and other water-soluble substances in the fly ash sample 6 dissolve in the water, thereby reducing the chlorine content in the fly ash sample 6. Table 1: Content of elements in fly ash samples before and after washing As can be seen from Table 1 above, the chlorine element (Cl) in the fly ash sample 6 is reduced after water washing; among them, the Na2O content in the fly ash sample after water washing is less than 0.01%.

[0028] Further optimized, the filtering device 2 includes a filtering box 21, an axial flow pump 22, a filter screen 23 and a drain pipe 24. The axial flow pump 22 is provided at one end of the filtering box 21, and the axial flow pump 22 is connected to the connecting pipe 15. A plurality of filter screens 23 are arranged at intervals in the filtering box 21. The other end of the filtering box 21 is provided with a drain pipe 24. The filter box 21 is provided with a fly ash sample 6 after washing and filtering. After the fly ash sample 6 is washed with water, the switch of the discharge port 111 is opened, and the axial flow pump 22 is started, so that the water in the water washing barrel 11 and the fly ash sample 6 enter the filter box 21 through the connecting pipe 15. The filter screen 23 in the filter box 21 can separate the fly ash sample 6 and the water. The filtered water flows out through the drain pipe 24, and the filtered fly ash sample 6 is taken out for extraction.

[0029] Further optimized, the extraction device 3 includes a condensation barrel 31, an extraction box 32 and an extract collection barrel 33. The condensation barrel 31 is connected to the extract collection barrel 33 through a steam conduit 34, and the extraction box 32 is connected to the extract collection barrel 33 through a siphon 35. Two condensation water pipes 36 are provided on the upper and lower sides of the condensation barrel 31. A feed port 37 is provided on one side of the extraction box 32. A stirring rod 38 is provided in the feed port 37. The extraction box 32 is provided with a fly ash sample 6 being extracted, and the fly ash sample 6 being extracted is coated on the inside of the filter paper 7. The washed and filtered fly ash sample 6 enters the extraction device 3 for extraction. Before extraction, the washed fly ash sample 6 is weighed and placed in a filter paper 7 resistant to organic solutions. The extract collection bucket 33 is connected to the extraction box 32, and the bottom of the condensation bucket 31 is connected to the extraction box 32. The condensation water pipe 36 on the condensation bucket 31 is connected to the condensation water. During extraction, the fly ash sample 6 wrapped with filter paper 7 is placed in the extraction box 32, and an organic solvent is poured above the condensation barrel 31. The organic solvent flows along the condensation barrel 31 into the extraction box 32, and the organic solvent fully submerges the fly ash sample 6. The dioxins in the fly ash sample 6 are dissolved in the organic solvent, and the highest point of the liquid level of the organic solvent is lower than the highest point of the siphon tube 35. During this process, the stirring rod 38 stirs the organic solvent and the fly ash sample 6 in the extraction box 32. After soaking and extracting for a period of time, the organic solvent is continued to be added until the highest point of the liquid level of the organic solvent exceeds the highest point of the siphon tube 35. At this time, the siphon tube 35 starts to work, and the organic solvent containing dioxins in the extraction box 32 enters the extraction liquid collection barrel 33 through the siphon tube 35. The organic solvent in the extraction liquid collection barrel 33 will evaporate, and the evaporated organic solvent can enter the condensation barrel 31 through the steam conduit 34 and condense into liquid organic solvent in the condensation barrel 31. The condensed organic solvent can continue to flow into the extraction box 32 to continue soaking the fly ash sample 6. After extraction, the extraction device 3 is closed and the fly ash sample 6 after extraction is taken out from the extraction box 32 .

[0030] Further optimization scheme, the filtration device 4 includes a filtration bucket 41, a funnel 42, a safety bucket 43 and a vacuum filter 44. The funnel 42 is provided on the top of the filtration bucket 41, the inner wall of the funnel 42 is paved with filter paper 7, and the extracted fly ash sample 6 is laid on the filter paper 7. The safety bucket 43 is connected to the filtration bucket 41, and the safety bucket 43 is connected to the vacuum filter 44. The extracted fly ash sample 6 is placed on the filter paper 7 above the funnel 42 for filtration to separate the residual organic solvent in the fly ash sample 6. The vacuum filter 44 is turned on to draw the extract from the fly ash sample 6 above the funnel 42 into the filtration barrel 41. During this process, the organic solvent in the extract collection barrel 33 is used to rinse the fly ash sample 6 on the funnel 42 to reduce the residual dioxins in the fly ash sample 6. Finally, the organic solvent is poured into the extract retention barrel 9 for storage.

[0031] Further optimizing the solution, the drying device 5 includes a vacuum drying box 51 and a nitrogen pipe 52, the vacuum drying box 51 and the nitrogen pipe 52 are connected, and the fly ash sample 6 and the activated carbon 8 after being treated by the filtration device 4 are arranged in the vacuum drying box 51; After filtration, the fly ash sample 6 is placed on a drying tray in a ventilated place to allow most of the residual organic solvent to evaporate naturally, completing preliminary drying. After preliminary drying is completed, the fly ash sample 6 is placed in a vacuum drying oven 51, and activated carbon 8 is placed in the vacuum drying oven 51. The vacuum drying oven 51 is turned on to form a vacuum space in the vacuum drying oven 51. During this process, the temperature in the vacuum drying oven 51 is lower than 200° C. to prevent the decomposition of residual dioxins under high temperature conditions.

[0032] In another embodiment, after the vacuum drying box 51 extracts air, when there is no oxygen in the vacuum drying box 51, the vacuum drying box 51 stops extracting the air inside it, and the nitrogen pipe 52 is connected to the nitrogen source, so that the nitrogen fills the vacuum drying box 51. When the pressure in the vacuum drying box 51 returns to normal pressure or a slightly positive pressure state, the nitrogen source is turned off. During this process, nitrogen purges the fly ash sample 6 to accelerate the separation of the organic solvent and the fly ash gas. After the nitrogen is added, it can be maintained for a period of time, and then vacuum is re-extracted. This reciprocating operation is repeated until the fly ash sample 6 is dry.

[0033] Table 2: Dioxin content of fly ash sample 6 before and after extraction As can be seen from Table 2 above, the dioxin content in the fly ash sample 6 after extraction is significantly lower than the dioxin content in the fly ash sample before extraction.

[0034] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A system for reducing dioxins in fly ash from municipal solid waste incineration using wet extraction with organic solvents, characterized in that: The invention comprises a water washing device (1), a filtering device (2), an extraction device (3), a suction filtering device (4) and a drying device (5) which are arranged in sequence, wherein the water washing device (1) is connected to the filtering device (2).

2. The system for reducing dioxins in fly ash from municipal solid waste incineration by wet extraction using organic solvents according to claim 1, characterized in that: The water washing device (1) comprises a water washing bucket (11), a motor (12), a rotating shaft impeller (13), a footrest (14) and a connecting pipe (15). The motor (12) is arranged on the top of the water washing bucket (11), and the rotating shaft impeller (13) is rotatably arranged inside the water washing bucket (11). The top of the rotating shaft impeller (13) is transmission-connected to the motor (12). A plurality of footrests (14) are arranged on the bottom of the water washing bucket (11). A discharge port (111) is arranged at the bottom end of the water washing bucket (11), and the discharge port (111) is communicated with the connecting pipe (15). An original fly ash sample (6) is arranged in the water washing bucket (11).

3. The system for reducing dioxins in fly ash from municipal solid waste incineration by wet extraction using organic solvents according to claim 2, characterized in that: The filtering device (2) comprises a filtering box (21), an axial flow pump (22), a filter screen (23) and a drain pipe (24); an axial flow pump (22) is provided at one end of the filtering box (21); the axial flow pump (22) is communicated with a connecting pipe (15); a plurality of filter screens (23) are arranged at intervals in the filtering box (21); a drain pipe (24) is provided at the other end of the filtering box (21); and a fly ash sample (6) after washing and filtering is provided in the filtering box (21).

4. The system for reducing dioxins in fly ash from municipal solid waste incineration by wet extraction using organic solvents according to claim 3, characterized in that: The extraction device (3) includes a condensation barrel (31), an extraction box (32) and an extraction liquid collection barrel (33), wherein the condensation barrel (31) is connected to the extraction liquid collection barrel (33) through a steam conduit (34), and the extraction box (32) is connected to the extraction liquid collection barrel (33) through a siphon (35). Two condensation water pipes (36) are arranged on the outer side of the condensation barrel (31) at intervals above and below. A feed port (37) is arranged on one side of the extraction box (32), and a stirring rod (38) is arranged in the feed port (37). A fly ash sample (6) being extracted is arranged in the extraction box (32), and the fly ash sample (6) being extracted is coated inside the filter paper (7).

5. The system for reducing dioxins in fly ash from municipal solid waste incineration by wet extraction using organic solvents according to claim 4, characterized in that: The filtration device (4) comprises a filtration bucket (41), a funnel (42), a safety bucket (43) and a vacuum filter (44); the funnel (42) is provided on the top of the filtration bucket (41); the inner wall surface of the funnel (42) is paved with filter paper (7); the extracted fly ash sample (6) is paved on the filter paper (7); the safety bucket (43) is connected to the filtration bucket (41), and the safety bucket (43) is connected to the vacuum filter (44).

6. The system for reducing dioxins in fly ash from municipal solid waste incineration by wet extraction using organic solvents according to claim 5, characterized in that: The drying device (5) comprises a vacuum drying box (51) and a nitrogen pipe (52), wherein the vacuum drying box (51) and the nitrogen pipe (52) are connected, and the fly ash sample (6) and activated carbon (8) treated by the filtration device (4) are arranged in the vacuum drying box (51).

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