A fly ash dioxin removal miniaturized device and method

Abstract

The application discloses a fly ash dioxin removal miniaturized device and method, relates to the technical field of fly ash treatment, and solves the problems of low removal efficiency, complicated process and high cost in the process of removing dioxin in fly ash. The system comprises an air duct for introducing high-temperature flue gas, a gas-powder mixer, a gas-powder separation assembly and a secondary air duct, a first temperature sensor installed in the air duct, a fan, a second temperature sensor and a particulate matter detector installed in the secondary air duct, and a controller. The system can use the high-temperature flue gas of the incinerator in the existing garbage incineration process to desorb dioxin in fly ash, mix the desorbed dioxin with air and return to the incinerator for high-temperature oxidation. The existing garbage incineration process is ingeniously used, the online production conditions are fully utilized, there is no secondary large energy input, and therefore, the cost is effectively reduced.

Description

Technical Field

[0001] This application relates to the field of fly ash treatment technology, and in particular to a miniaturized device and method for removing dioxins from fly ash. Background Technology

[0002] Fly ash is a substance containing various pollutants, typically collected by baghouse dust collectors after a series of treatments following high-temperature incineration. Source industries include waste incineration and hazardous waste incineration. For example, in the waste incineration industry: with the increasing prevalence of municipal solid waste incineration, my country's fly ash production is also continuously increasing. Fly ash has a complex composition, adsorbing high concentrations of organic and inorganic pollutants from flue gas. In particular, fly ash contains highly carcinogenic, teratogenic, and mutagenic dioxins and heavy metals. If not properly treated, these pollutants will be transported from the emission source to various locations through the atmosphere and rainwater, polluting the air and water sources, entering the food chain, and causing harm to humans. Therefore, achieving the harmless disposal and resource utilization of fly ash is one of the urgent environmental problems that needs to be solved.

[0003] Currently, the main technologies for treating dioxins in fly ash include solidification and landfill, biodegradation, chemical removal, low-temperature pyrolysis, and high-temperature treatment. Among these, solidification and landfill may become a potential source of dioxin pollution for landfills; biodegradation and low-temperature pyrolysis have the advantages of being environmentally friendly and low-cost, but their dioxin degradation efficiency is not high; chemical removal has the advantages of low energy consumption and high efficiency, but it poses the problem of secondary pollution. Co-processing fly ash in cement kilns is currently the mainstream high-temperature treatment technology. To strictly control the chlorine content, the amount of fly ash adulterated is very low; therefore, cement kilns can only achieve limited resource utilization of fly ash.

[0004] In addition, water washing is also common, but this process removes less dioxins. Studies have found that the highest toxicity equivalent in ash washing wastewater is 2,3,7,8-TCDD, accounting for 33.93% of the total toxicity equivalent in ash washing wastewater. The migration rate from raw ash to ash washing wastewater is only 0.26%, so this method cannot effectively remove dioxins.

[0005] Existing dioxin removal processes often require high-temperature desorption and re-oxidation using equipment, or the use of inert gases for high-temperature desorption. Both of these require the introduction of third-party equipment and processes, making the processes cumbersome, difficult to operate, and increasing the cost of dioxin removal and treatment.

[0006] For example, the patent with publication number TW200736549A, titled "Treatment Equipment and Method for Degrading Dioxin-like Compounds by Medium-Temperature Desorption Combined with High-Temperature Plasma Oxidation," uses a temperature between 450-850℃ for desorption. The desorbed gas then enters a high-temperature plasma oxidation chamber at at least 1200℃, where a plasma torch oxidizes and destroys the dioxin-like compounds in the gas stream—a process known as plasma torching. The gas is then discharged after passing through a quench tower, a lime reaction tower, an activated carbon injection device, and a filter bag dust collector. Summary of the Invention

[0007] The purpose of this application is to overcome the problems of low removal efficiency, cumbersome process and high cost in the existing technology for removing dioxins from fly ash, and to provide a miniaturized device and method for removing dioxins from fly ash.

[0008] In a first aspect, a miniaturized fly ash dioxin removal device is provided, comprising an exhaust pipe with a temperature regulating component, one end of the exhaust pipe being connected to an incineration system, the other end of the exhaust pipe being connected to a gas-powder mixer, an ash inlet being pre-set at the end of the exhaust pipe near the gas-powder mixer, an exhaust gas-powder separation component being connected to the output end of the gas-powder mixer, and a gas output port of the gas-powder separation component being connected to a secondary air duct of the incinerator through a second air duct, a first temperature sensor being installed on the exhaust pipe, and a fan, a second temperature sensor, and a particulate matter detector being installed on the second air duct, wherein the first temperature sensor, the fan, the second temperature sensor, and the particulate matter detector are all electrically connected to a controller;

[0009] The gas-powder separation assembly includes a first gas-powder separator and a second gas-powder separator connected in series. Both the first and second gas-powder separators include a housing and a static separation chamber and a dynamic separation chamber disposed within the housing. The upper end of the static separation chamber has a cylindrical structure, and the lower end has a hollow conical structure. A gas-powder inlet is provided on one side of the static separation chamber, and a first powder outlet is provided at the lower end. A connecting pipe is embedded in the upper end of the static separation chamber. One end of the connecting pipe extends into a first conical guide plate inside the static separation chamber, and the other end of the connecting pipe connects to the dynamic separation chamber. A first conical guide plate and a second conical guide plate are fixed inside the static separation chamber. The outer edge of the upper end of the first conical guide plate is fixed... The system includes an annular baffle, a first conical guide plate with a first cylinder fixedly connected to its lower end, the lower end of the first cylinder extending into a second conical guide plate, a second cylinder fixedly connected to its lower end, and a third conical guide plate connected to its lower end. An annular guide plate is fixed to the inner wall of the static separation chamber, located between the first and second conical guide plates. The upper end of the dynamic separation chamber has a cylindrical structure, and the lower end has a hollow conical structure. A gas guide tube is embedded in the upper end of the dynamic separation chamber, with a cylindrical upper end and a hollow conical lower end. A gas outlet is located at the upper end of the gas guide tube, and a second powder outlet is located at the lower end of the dynamic separation chamber.

[0010] In some possible implementations, the incineration system includes an incinerator, a primary waste heat recovery device, and a secondary waste heat recovery device. The induced draft duct includes a first duct, one end of which is connected to a gas-powder mixer, and the other end of which is connected to a first branch duct and a second branch duct. The first branch duct is used to connect the pipeline between the incinerator and the primary waste heat recovery device, and the second branch duct is used to connect the pipeline between the primary waste heat recovery device and the secondary waste heat recovery device. The temperature control component includes a first air valve and a second air valve, the first air valve being installed in the first branch duct and the second air valve being installed in the second branch duct.

[0011] In some possible implementations, both the first and second air valves are electrically controlled valves, and both are electrically connected to the controller.

[0012] In some possible implementations, the ash inlet is connected to the output of a rotary feeder, the input of which is used to connect to an ash source, and the rotary feeder is electrically connected to a controller.

[0013] In some possible implementations, the gas-powder inlet is located between the second and third conical guide plates, the third conical guide plate being located within the hollow conical structure at the lower end of the static separation chamber, and the annular guide plate having at least two guiding surfaces.

[0014] In some possible implementations, the end of the second duct away from the gas-powder separation assembly is connected to one of the inputs of the mixing chamber, the other input of which is connected to the slag silo, and the output of which is connected to the incinerator.

[0015] In a second aspect, a method for removing dioxins from fly ash is provided, applied to the system described in the first aspect, the method comprising:

[0016] Start the fan and adjust the opening of the first and second air valves according to the detection data of the first temperature sensor to adjust the temperature of the mixture sent into the gas-powder mixer to 650℃-750℃.

[0017] Start the rotary feeder and adjust the parameters of the gas-powder separation unit according to the detection data of the particulate matter detector so that the gas output by the gas-powder separation unit carries a preset amount of fly ash.

[0018] Adjust the opening of the first and second valves according to the detection data of the second temperature sensor to adjust the temperature of the mixture in the second air duct to no less than 550℃.

[0019] In some possible implementations, the amount of fly ash carried in the gas output by the gas-powder separation component is 5%-10% of the original fly ash amount.

[0020] In some possible implementations, the air volume in the first duct is 1000m³. 3 / h-2000m 3 The ash feeding capacity of the star feeder is 200kg / h-300kg / h.

[0021] In some possible implementations, the mixture of hot air and fly ash in the first duct has a residence time of 10s-30s in the air-powder mixer.

[0022] This application has the following beneficial effects:

[0023] 1. The system of this application can be organically combined with the existing waste incineration system. It utilizes the high-temperature flue gas of the incinerator in the existing waste incineration process to desorb dioxins from fly ash, and then mixes the desorbed dioxins with air and returns them to the furnace for high-temperature oxidation. It cleverly utilizes the existing waste incineration process, makes full use of online production conditions, and has no secondary large energy input, thereby effectively reducing costs.

[0024] 2. The method of this application can automatically control the corresponding valve opening and the ash feeding amount of the rotary feeder based on the detection data of the first temperature sensor, the second temperature sensor and the particulate matter detector, realizing the automated control of the miniaturized fly ash dioxin removal device, greatly simplifying the control process. At the same time, controlling the fly ash desorption temperature within the range of 650℃-750℃ effectively ensures the desorption rate of dioxins in fly ash, thereby improving the removal efficiency of dioxins in fly ash. Furthermore, it can transport most of the incompletely desorbed dioxins back to the incinerator through the second air duct with an internal temperature of not less than 550℃, effectively avoiding the regeneration of dioxins and eliminating secondary pollution. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a structural block diagram of the miniaturized fly ash dioxin removal device of Embodiment 1 of this application;

[0028] Figure 2 This is a structural block diagram of an existing waste incineration system;

[0029] Figure 3 This is a circuit block diagram of the miniaturized fly ash dioxin removal device of Embodiment 1 of this application;

[0030] Figure 4 This is a model diagram of the type I adsorption isotherm of dioxins in fly ash;

[0031] Figure 5 This is a type I adsorption isobaric model diagram of dioxins in fly ash;

[0032] Figure 6 This is a schematic diagram of the structure of the first gas-powder separator in the miniaturized fly ash dioxin removal device of Embodiment 1 of this application;

[0033] Figure 7 This is a front view of the first gas-powder separator in the miniaturized fly ash dioxin removal device of Embodiment 1 of this application;

[0034] Figure 8 This is a side view of the first gas-powder separator in the miniaturized fly ash dioxin removal device of Embodiment 1 of this application;

[0035] Figure 9 This is a top view of the first gas-powder separator in the miniaturized fly ash dioxin removal device of Embodiment 1 of this application;

[0036] Figure 10 yes Figure 9 A cross-sectional view along the AA direction;

[0037] Figure 11 yes Figure 10 Enlarged view of the structure at point A in the middle;

[0038] Figure 12 This is a top view of the first gas-powder separator in the miniaturized fly ash dioxin removal device of Embodiment 1 of this application;

[0039] Figure 13 This is a flowchart of the fly ash dioxin removal method of Embodiment 2 of this application.

[0040] Figure label:

[0041] 1. Temperature control assembly; 101. First air valve; 102. Second air valve; 2. Exhaust duct; 201. First branch air duct; 202. Second branch air duct; 203. First air duct; 3. Incineration system; 301. Incinerator; 302. Secondary air duct; 303. Primary waste heat recovery equipment; 304. Secondary waste heat recovery equipment; 305. Slag silo; 306. Garbage pit; 307. Primary air duct; 308. Exhaust gas pretreatment equipment; 309. Baghouse dust collector; 310. Transfer ash silo; 311. Exhaust gas post-treatment equipment; 312. Exhaust stack; 313. Ash silo; 4. Gas-powder mixer; 5. Ash inlet; 6. Gas-powder separation assembly; 601. First gas-powder separator; 602. Second gas-powder separator; 6 603. Shell; 604. Static separation chamber; 605. Dynamic separation chamber; 606. Air-powder inlet; 607. First powder outlet; 608. Connecting pipe; 609. First conical guide plate; 610. Second conical guide plate; 611. Annular baffle; 612. First cylinder; 613. Second cylinder; 614. Third conical guide plate; 615. Annular guide plate; 616. Air guide tube; 617. Gas outlet; 618. Second powder outlet; 619. Guide surface; 620. Opening; 621. Valve plate; 7. Second air duct; 8. First temperature sensor; 9. Fan; 10. Second temperature sensor; 11. Particulate matter detector; 12. Rotary feeder; 13. Mixing chamber; 14. Controller. Detailed Implementation

[0042] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] like Figure 2 As shown, the incineration system 3 includes an incinerator 301, a secondary air duct 302, a primary waste heat recovery device 303, a secondary waste heat recovery device 304, a slag silo 305, a waste pit 306, a primary air duct 307, a flue gas pretreatment device 308, a bag filter 309, a flue gas post-treatment device 311, and an exhaust stack 312. Existing waste incineration processes generally involve storing the waste to be incinerated in the waste pit 306, transporting the waste to the incinerator 301 for incineration, utilizing the primary waste heat recovery device 303 to recover heat from the flue gas, and then utilizing the secondary waste heat recovery device 304 to further recover heat from the flue gas. Secondary recycling is carried out. The slag is transported to the slag silo 305 for storage. The flue gas is treated by the tail gas pretreatment equipment 308 and then enters the bag filter 309 to filter out the solid particles in the flue gas. These solid particles are called fly ash. The gas is discharged into the atmosphere through the exhaust stack 312 after passing through the tail gas posttreatment equipment 311. In order to avoid the waste gas in the waste pit 306 and the slag silo 305 from polluting the environment, the waste needs to be introduced into the incinerator 301 through the primary air duct 307 and the secondary air duct 302, respectively. On the one hand, it provides the oxygen required for combustion in the incinerator 301, and on the other hand, it avoids the waste from polluting the surrounding environment.

[0045] It should be noted that the oxygen content of the flue gas after incinerator 301 is low, approximately 6%, creating a relatively inert environment that is conducive to the desorption of dioxins from fly ash. The adsorption of dioxins in fly ash meets the requirements as follows: Figure 4 The type I adsorption isotherm model shown, converted to an adsorption isobaric line as follows: Figure 5 As shown, the higher the temperature, the lower the adsorption capacity of dioxins in fly ash. Therefore, the desorption of dioxins from fly ash can be achieved by increasing the ambient temperature of fly ash and reducing the oxygen content in the environment to decrease the adsorption capacity of dioxins in fly ash.

[0046] like Figure 1As shown in Embodiment 1 of this application, a miniaturized fly ash dioxin removal device includes an exhaust duct 2 with a temperature control component 1. The exhaust duct 2 includes a first duct 203, one end of which is connected to a gas-powder mixer 4. The other end of the first duct 203 is connected to a first branch duct 201 and a second branch duct 202. The first branch duct 201 connects the incinerator 301 to the primary waste heat recovery device 303, and the second branch duct 202 connects the primary waste heat recovery device 303 to the secondary waste heat recovery device 304. The temperature control component 1 includes... The system includes a first air valve 101 and a second air valve 102. The first air valve 101 is installed in the first branch duct 201, and the second air valve 102 is installed in the second branch duct 202. High-temperature flue gas is drawn from the incinerator 301 through the first branch duct 201. Under normal circumstances, the temperature inside the incinerator 301 is approximately 900℃-1050℃. Medium-temperature flue gas is drawn from the primary waste heat recovery device 303 through the second branch duct 202. Under normal circumstances, the temperature of the flue gas after treatment by the primary waste heat recovery device 303 is approximately 200℃-700℃. The temperature of the high-temperature flue gas and the medium-temperature flue gas can be adjusted by regulating the opening of the first and second valves. The temperature of the introduced flue gas is adjusted by adjusting the ratio of warm flue gas to warm flue gas. The other end of the induced draft pipe 2 is connected to a gas-powder mixer 4. An ash inlet 5 is pre-installed at the end of the induced draft pipe 2 closest to the gas-powder mixer 4. The ash inlet 5 is used to introduce fly ash, allowing the fly ash to be pre-mixed with the flue gas introduced from the incineration system 3 in the first gas pipe. The pre-mixed flue gas and fly ash are then thoroughly mixed in the gas-powder mixer 4. The high temperature of the flue gas is used to desorb dioxins from the fly ash. The output end of the gas-powder mixer 4 is connected to a gas-powder separation component 6. After desorption, the dioxins in the fly ash are separated from the particulate fly ash in the gas-powder separation component 6. The gas outlet 617 of the gas separation component 6 is connected to the secondary air duct 302 of the incinerator 301 via the second air duct 7. The desorbed dioxins flow back to the incinerator 301 with the gas through the second air duct 7, where they are re-oxidized at high temperatures to remove the dioxins. Simultaneously, during gas-powder separation by the gas-powder separation component 6, a small amount of fly ash may not be completely separated. This small amount of fly ash, mixed with dioxins and gas, also flows back to the incinerator 301 along the second air duct. The induced draft duct 2 is equipped with a first temperature sensor 8, and the second air duct 7 is equipped with a fan 9, a second temperature sensor 10, and a particulate matter detector 11. Figure 3As shown, the first gas-powder separator 601, the second gas-powder separator 602, the first temperature sensor 8, the blower 9, the second temperature sensor 10, and the particulate matter detector 11 are all electrically connected to the controller 14. The first temperature sensor 8 is installed in the first gas pipe to detect the temperature of the flue gas introduced from the incineration system 3, which facilitates the control of the temperature during the desorption of dioxins from fly ash. The second temperature sensor 10 is installed in the second gas pipe to detect the temperature of the mixture of gas, dioxins, and a small amount of fly ash that flows back to the incinerator 301, which facilitates the control of the temperature of the mixture to prevent the regeneration of dioxins during the recirculation process due to excessively low temperature. The controller 14 can control the operation and output power of the blower 9.

[0047] Specifically, the gas-powder separation assembly 6 includes a first gas-powder separator 601 and a second gas-powder separator 602 connected in series, such as... Figures 6-12 As shown, both the first gas-powder separator 601 and the second gas-powder separator 602 include a housing 603 and a static separation chamber 604 and a dynamic separation chamber 605 disposed within the housing 603. The upper end of the static separation chamber 604 has a cylindrical structure, and the lower end of the static separation chamber 604 has a hollow conical structure. A gas-powder inlet 606 is provided on one side of the static separation chamber 604, and a first powder outlet 607 is provided at the lower end of the static separation chamber 604. A connecting pipe 608 is embedded in the upper end of the static separation chamber 604. One end of the connecting pipe 608 extends into a first conical guide plate 609 inside the static separation chamber 604, and the other end of the connecting pipe 608 is connected to the dynamic separation chamber 605. A first conical guide plate 609 and a second conical guide plate 610 are fixed inside the static separation chamber 604. An annular baffle 611 is fixed to the outer edge of the upper end of the first conical guide plate 609. A first cylinder 612 is fixedly connected to the lower end of plate 609. The lower end of the first cylinder 612 extends into the second conical guide plate 610. A second cylinder 613 is fixedly connected to the lower end of the second conical guide plate 610. A third conical guide plate 614 is connected to the lower end of the second cylinder 613. An annular guide plate 615 is fixed to the inner wall of the static separation chamber 604. The annular guide plate 615 is located between the first conical guide plate 609 and the second conical guide plate 610. The upper end of the dynamic separation chamber 605 has a cylindrical structure, and the lower end of the dynamic separation chamber 605 has a hollow conical structure. A gas guide tube 616 is embedded in the upper end of the dynamic separation chamber 605. The upper end of the gas guide tube 616 has a cylindrical structure, and the lower end of the gas guide tube 616 has a hollow conical structure. A gas outlet 617 is provided at the upper end of the gas guide tube 616, and a second powder outlet 618 is provided at the lower end of the dynamic separation chamber 605.

[0048] like Figure 12As shown, in order to control the ratio of air and powder in the mixed return air output by the air-powder separation component, an opening 620 is reserved on the side of the air guide 616 near the port of the connecting pipe 608. A valve plate 621 for controlling the opening degree of the opening 620 is installed in the opening 620. The opening degree of the valve plate 621 is controlled by a power mechanism such as a motor, hydraulic rod or pneumatic rod. It should be noted that a small part of the air-powder mixture blown out from the connecting pipe 608 directly enters the air guide 616 through the opening 620 and is directly output from the gas output port 617 (this part of the air-powder mixture does not undergo air-powder separation again). Most of the air-powder mixture moves downward in a swirling motion and enters the cylindrical structure and hollow conical structure of the dynamic separation chamber 605. The opening degree of the opening 620 is controlled by controlling the valve plate 621, thereby controlling the amount of air-powder mixture that directly enters the air guide 616 from the connecting pipe 608, so as to control the ratio of air and powder in the output mixed return air.

[0049] To guide the gas in the gas-powder mixture input through the gas-powder inlet 606 upwards as much as possible, the gas-powder inlet 606 is located between the second conical guide plate 610 and the third conical guide plate 614. The third conical guide plate 614 is located within the hollow conical structure at the lower end of the static separation chamber 604. The gas-powder mixture enters the static separation chamber 604 from the gas-powder inlet 606. Under the combined guiding action of the third conical guide plate 614, the second conical guide plate 610, and the conical structure at the lower end of the static separation chamber 604, the gas flows upwards along the periphery of the second conical guide plate 610. The powder, under the action of gravity, can fall into the conical structure at the lower end of the static separation chamber 604, achieving primary gas-powder separation. The annular guide plate 615 has at least two guiding surfaces 619, such as... Figure 12 As shown, the lower guide surface 619 guides the flow of the gas-powder mixture, causing it to flow towards the center of the static separation chamber 604. The upper guide surface 619 guides the powder falling due to gravity, allowing it to slide into the airflow of the gas-powder mixture, thus preventing powder accumulation above the annular guide plate 615. As shown, the first guide surface 619 of the annular guide plate 615 guides the airflow obliquely upward, so that the airflow passes above the second conical guide plate 610 as it flows upward. Under the action of gravity, the powder in the airflow can fall into the second conical guide plate 610 to achieve secondary gas-powder separation.

[0050] In order to enable the controller 14 to control the first air valve 101 and the second air valve 102, both the first air valve 101 and the second air valve 102 are electrically controlled valves. Both the first air valve 101 and the second air valve 102 are electrically connected to the controller 14. The controller 14 can control the opening and closing of the first air valve 101 and the second air valve 102 and the opening degree, thereby facilitating the automatic adjustment of the temperature of the flue gas introduced from the incineration system 3.

[0051] In incineration system 3, a bag filter 309 is used to collect fly ash from the flue gas. The collected fly ash is sent to a transfer ash silo 310 for storage via a hopper and fly ash conveyor belt. The transfer ash silo 310 serves as the ash source for the star feeder 12, providing fly ash to the star feeder 12. The ash inlet 5 is connected to the output end of the star feeder 12, and the input end of the star feeder 12 is used to connect to the transfer ash silo 310. The star feeder 12 is connected to the controller 1. 4. Electrical connection is established so that the rotary feeder 12 can transport fly ash from the transfer ash silo 310 through the ash inlet 5 to the first air duct 203 for premixing with the flue gas introduced from the combustion system. The rotary feeder 12 is characterized by its ability to uniformly and continuously supply fly ash to the second air duct 7, ensuring a stable gas-to-solid ratio and enabling normal operation of the pneumatic conveying system. Simultaneously, it can isolate the upper and lower air pressures of the rotary feeder 12, thus acting as an airlock. The rotary feeder 12 operates continuously, processing 1.2-1.6 tons of fly ash per hour. The output of the rotary feeder 12 can be adjusted in conjunction with the detection data from the downstream particulate matter detector 11.

[0052] To achieve dioxin desorption, the mixture of flue gas and fly ash in the first gas tube is fed into the gas-powder mixer 4. The gas and powder are rapidly and dynamically mixed. The residence time of the mixture of flue gas and fly ash in the gas-powder mixer 4 is about 10-30 seconds. This allows the flue gas to provide a high-temperature and low-oxygen environment for the fly ash in the gas-powder mixer 4, thereby achieving dioxin desorption.

[0053] In a further embodiment, the first air-powder separator 601 and the second air-powder separator 602 are connected in series. The air-powder inlet 606 of the first air-powder separator 601 is connected to the output end of the air-powder mixer 4. The air-powder inlet 606 of the second air-powder separator 602 is connected to the gas outlet 617 of the first air-powder separator 601. The gas outlet 617 of the second air-powder separator 602 is connected to the mixing chamber 13 through the second air duct 7. The first powder outlet 607 and the second powder outlet 618 of the first air-powder separator 601 and the second air-powder separator 602 are both connected to the ash silo 313. When the air-powder separation component 6 is working, the air-powder mixture enters the static separation chamber 604 through the gas inlet of the first air-powder separator. To prevent fly ash accumulation, a third conical guide plate 614 is provided in the bottom area of ​​the static separation chamber 604.

[0054] like Figure 10 and Figure 11 As shown (where, Figure 10 and Figure 11The red lines in the diagram represent the flow trajectory of the air-powder mixture, and the green lines represent the flow trajectory of the separated gas. The air-powder mixture first passes through the second conical guide plate 610. Larger fly ash particles have a higher probability of colliding with the second conical guide plate 610, so some of these particles return to the lower region of the static separation chamber 604 to complete the first separation. Then, due to the tilting of the airflow caused by the annular guide plate 615 and the first conical guide plate 609, the fly ash moves upward in a spiral motion. At this point, the kinetic energy provided by the airflow is insufficient to keep some fly ash particles moving, so they fall into the second conical guide plate 610 and eventually return to the lower region of the static separation chamber 604 to complete the second separation. At the annular baffle 611, some fly ash particles fall into the second conical guide plate 610 due to gravity and eventually enter the lower region of the static separation chamber 604 to complete the third separation. Subsequently, the air-powder mixture enters the dynamic separator through the connecting pipe 608. A small portion of the air-powder mixture flows directly out through the air guide 616 without flowing downwards into the dynamic separation chamber 605, while the majority of the air-powder mixture undergoes downward swirling motion, entering the cylindrical and hollow conical structures of the dynamic separation chamber 605. Near the wall in the cylindrical structure, the air-powder mixture is constrained by the wall and moves downwards along the wall. At the center, the airflow velocity is slower, resulting in weaker carrying capacity for fly ash particles, which move downwards due to gravity. In the hollow conical structure, some of the air-powder mixture continues to swirl upwards, moving upwards along the central axis. The air-powder mixture is further separated, and the screened small-diameter fly ash particles flow out of the dynamic separation chamber 605 with the airflow, forming mixed return air. The fly ash then enters the ash silo, and the mixed return air enters the incinerator for re-combustion through the second air duct. Furthermore, the compact design of this air-powder separator enables miniaturization of the dioxin removal device, meeting the needs of small-scale waste incinerators.

[0055] Because the flue gas produced by municipal solid waste incineration has a high temperature, the inner wall of the pipes is lined with high-temperature resistant material to prevent damage from the high temperature. To reduce heat loss in the mixed intake and return air ducts, the outer wall of the pipes is lined with insulation material. To reduce wear on the pipes caused by the air-coal mixture, the inner wall of the pipes is lined with wear-resistant material.

[0056] In this embodiment, the fly ash and gas desorbed in the gas-powder mixer 4 are fed into the first gas-powder separator 601 for the first gas-powder separation, separating approximately 50% of the fly ash. Then, the remaining fly ash undergoes a second separation in the second gas-powder separator 602, achieving the goal of returning 5-10% of the fly ash to the incinerator 301. Because the activated carbon and other materials added before the bag filter 309 in the incineration system 3 adsorb a large amount of Cl-containing components and metal oxides containing Fe, Cu, etc., these metal oxides on the surface of the activated carbon catalyze the regeneration of dioxins, promoting the secondary formation of dioxins and adsorbing them onto these adsorbents. Therefore, fly ash with smaller particle sizes contains more dioxins.

[0057] Therefore, to avoid incomplete desorption of dioxins in small-particle fly ash and to prevent the regeneration of dioxins from the separated secondary fly ash, in this embodiment, 5-10% of the primary fly ash and dioxin mixture are recycled back to the incinerator 301 through the second duct 7 for dioxin decomposition. To prevent the regeneration and re-adsorption of dioxins into the fly ash, the temperature in the second duct 7 should not be lower than 550°C. Furthermore, most of the recycled fly ash consists of activated carbon and other substances, which can be oxidized to carbon dioxide in the incinerator 301 and will not be collected as fly ash again. Therefore, this embodiment also achieves the effect of reducing the amount of primary fly ash.

[0058] It should be noted that dioxins have a boiling point of 421.2℃~446.5℃ and a thermal decomposition temperature above 700℃. Experiments have shown that under a nitrogen atmosphere at 800℃, after pyrolyzing dioxin-containing riverbed sediment for 30 minutes, the concentration of PCDFs in the solid phase product decreased from 0.63 ng-TEQ / g to 0.001 ng-TEQ / g, and after 60 minutes or more, the concentration in the solid phase was 0. This demonstrates that thermal desorption requires a relatively long time and high temperature. Therefore, dioxins cannot be completely desorbed into a gaseous state within a short period of time, and some dioxins remain in the fly ash.

[0059] The synthesis of dioxins requires both carbon and chlorine sources. The primary carbon source often originates from unburned residual carbon in fly ash and activated carbon injected during flue gas treatment. The primary chlorine source tends to deposit on the surface of fly ash particles with a diameter of 10 μm or less. Furthermore, studies using flotation have found that fine particles smaller than 2.0 μm in fly ash contribute 80% of the toxicity equivalent, similar to previous findings that smaller particles contain higher dioxin content. Analysis showed that particles smaller than 2.5 μm account for approximately 11% of the total fly ash volume. Therefore, this system is designed to recycle 5-10% of the fly ash to reduce the impact of undesorbed dioxins.

[0060] In addition, the temperature of the fly ash after being processed by this system is maintained at no less than 550℃. There is a cooling process during the process of entering the ash silo 313. In order to avoid the regeneration of dioxins in the fly ash during this cooling range, 5-10% of small particulate fly ash is designed to be recycled back into the furnace, which takes away the carbon source for dioxin generation, cuts off the main conditions for dioxin regeneration, and avoids the regeneration of dioxins during the process of fly ash entering the ash silo 313.

[0061] In this embodiment, in order to achieve the goal of 5-10% of fly ash being recycled, the first gas-powder separator 601 and the second gas-powder separator 602 are connected in series. The gas-powder separation efficiency of the first gas-powder separator 601 is about 50%, and the separation efficiency of the first gas-powder separator 601 can be adjusted according to the detection data of the particulate matter detector 11 in the second air duct 7.

[0062] To avoid direct collision between the high-temperature gas in the second gas duct and the medium-temperature gas (slag blast temperature approximately 200℃) in the secondary air duct 302, which could affect the secondary air duct 302, a mixing chamber 13 is provided for pre-mixing the two gases. The two input ends of the mixing chamber 13 are connected to the second air duct 7 and the slag storage 305, respectively, and the output end of the mixing chamber 13 is connected to the incinerator 301. This ensures that the high-temperature gas and the medium-temperature gas are evenly mixed in the mixing chamber 13 before entering the incinerator 301 through the secondary air duct 302. This prevents the direct collision between the high-temperature gas and the medium-temperature gas from causing the following adverse effects on the secondary air duct 302: 1. High-temperature air and medium-temperature gas... 1. When exposed to high temperatures, thermal stress can occur in the pipe walls due to temperature differences, potentially leading to plastic deformation or fatigue damage in the pipe materials. 2. High-temperature air can cause localized overheating in the pipes, posing safety hazards, especially when the performance of the pipe materials deteriorates at high temperatures. 3. The encounter between high-temperature air and medium-temperature gas can cause pressure fluctuations within the pipes, potentially leading to explosions or other dangerous situations in extreme cases. 4. Temperature changes can cause pipe deformation or damage, increasing maintenance costs. 5. Long-term temperature variations can accelerate the aging of pipe materials, shortening their service life.

[0063] In this embodiment, a negative pressure mode is adopted, that is, the suction force of the fan 9 is used to drive the fly ash and flue gas, which can avoid the flue gas overflow and cause secondary pollution. A high temperature and wear resistant pipe fan 9 is installed at the second air duct 7 to drive the desorbed dioxin mixed air back to the furnace.

[0064] To prevent the temperature of the high-temperature air from dropping, insulation measures are taken for the first air duct 203, the second air duct 7, the air-powder mixer 4, the first air-powder separator 601, the second air-powder separator 602, and other pipes. For example, lightweight, low-insulation ceramic fiber modules are used for insulation.

[0065] In this embodiment, the miniaturized fly ash dioxin removal device can be organically integrated with the existing waste incineration system 3. It utilizes the high-temperature flue gas from the incinerator 301 in the existing waste incineration process to desorb dioxins from fly ash, and then returns the desorbed dioxins to the furnace for high-temperature oxidation. By cleverly utilizing the existing waste incineration process and making full use of online production conditions, the waste heat of flue gas can be reused without the need for a large secondary energy input, thereby effectively reducing costs. In addition, since fly ash contains a large amount of substances such as CaO, returning 5-10% of the fly ash to the furnace can reduce the generation of sulfur oxides and reduce the difficulty of subsequent tail gas treatment.

[0066] Example 2

[0067] like Figure 6 As shown, the fly ash dioxin removal method of Embodiment 2 of this application is applied to the miniaturized fly ash dioxin removal device as described in Embodiment 1. The fly ash dioxin removal method includes:

[0068] S100. Start the fan 9 and adjust the opening of the first air valve 101 and the second air valve 102 according to the detection data of the first temperature sensor 8 (i.e. the first air temperature) to adjust the temperature of the mixture sent into the gas-powder mixer 4 to 650℃-750℃.

[0069] Specifically, due to the unstable temperature of the high-temperature air drawn out from the incinerator 301 caused by the original air intake temperature or operating conditions, an air intake is set up between the incinerator 301 and the primary waste heat recovery device 303, and between the primary waste heat recovery device 303 and the secondary waste heat recovery device 304. These air intakes are connected to the first branch air duct 201 and the second branch air duct 202, respectively. A first air valve 101 and a second air valve 102 are also set up. The opening of the first air valve 101 and the second air valve 102 is adjusted according to the temperature detected by the first temperature sensor 8 to achieve the purpose of temperature regulation. If the measured temperature is lower than the initial set air temperature of 650℃ or the set value, the air intake after the incinerator 301 is increased, i.e., the opening of the first air valve 101 is increased, and the air intake between the primary waste heat recovery device 303 and the secondary waste heat recovery device 304 is reduced, i.e., the opening of the second air valve 102 is reduced. If the measured temperature is higher than the initial set air temperature of 750℃ or the set value, the air intake between the primary waste heat recovery device 303 and the secondary waste heat recovery device 304 is increased, i.e., the opening of the second air valve 102 is increased, and the air intake after the incinerator 301 is reduced, i.e., the opening of the first air valve 101 is reduced. The entire process operates automatically, maintaining a constant total air volume in the first air duct 203.

[0070] S200, Start the star feeder 12 and adjust the parameters of the gas-powder separation component 6 according to the detection data of the particulate matter detector 11 so that the gas output by the gas-powder separation component 6 carries a preset amount of fly ash.

[0071] Specifically, the star-shaped feeder 12 provides a fixed amount of fly ash, which is pre-mixed with the flue gas drawn from the incineration system 3 and then enters the air-powder mixer 4. The fly ash and high-temperature flue gas are fully mixed in the air-powder mixer 4. To ensure sufficient mixing and desorption rate, the residence time of the mixture of hot air and fly ash in the first air duct 203 in the air-powder mixer 4 is 10s-30s. Dioxins in the fly ash are desorbed using a high-temperature environment of 650℃-750℃. The air volume in the first air duct 203 is 1000m³. 3 / h-2000m 3 The feed rate of the star feeder 12 is 200kg / h-300kg / h, which not only ensures the desorption rate of dioxins in fly ash, but also ensures the treatment efficiency of fly ash.

[0072] After passing through the first air-coal separator, approximately 50% of the fly ash is separated; then, through the second air-coal separator, the remaining fly ash is separated, ultimately achieving the goal of recycling 5-10% of the original fly ash (i.e., 5-10% of the total fly ash). The amount of fly ash is measured by the particulate matter detector 11 on the second air duct 7. If the amount of fly ash recycled is less than 5% of the original fly ash, the controller 14 reduces the efficiency of the second air-coal separator to increase the amount of fly ash recycled; if the amount of fly ash recycled is greater than 10% of the original fly ash, the controller 14 increases the efficiency of the second air-coal separator to reduce the amount of fly ash recycled. The secondary fly ash separated by the first and second air-coal separators enters the ash silo 313.

[0073] S300. Based on the detection data (i.e., the second air temperature) from the second temperature sensor 10, adjust the opening of the first valve and the second valve to adjust the temperature of the mixture in the second air duct 7 to not less than 550°C. For example, if the temperature detected by the second temperature sensor 10 is 500°C (lower than 550°C), the proportion of high-temperature flue gas drawn from the incinerator 301 can be increased by increasing the opening of the first valve and decreasing the opening of the second valve, thereby increasing the temperature of the flue gas in the first air duct 203. If the temperature of the mixture in the second air duct 7 has been adjusted to not less than 550°C, but the temperature detected by the first temperature sensor 8 is lower than 650°C, the opening of the first valve should be increased and the opening of the second valve should be decreased to increase the proportion of high-temperature flue gas drawn from the incinerator 301, thereby increasing the temperature in the first air duct 203. If the temperature of the mixture in the second air duct 7 has been adjusted to not less than 550°C, but the temperature detected by the first temperature sensor 8 is higher than or equal to 650°C, then there is no need to adjust the opening of the first valve and the second valve.

[0074] Using the above-mentioned fly ash dioxin removal method, an experiment was conducted at a waste incineration plant. Various equipment were connected, and fly ash samples from transfer ash silos 310 and ash silos 313 were collected for dioxin detection. The experiment was conducted under fixed conditions: high-temperature airflow of 2000 m³ / h.3 The test was conducted under the following conditions: air inlet temperature 650℃, ash feed rate 200 kg / h, and return air temperature maintained above 550℃. The test results are shown in Table 1 below.

[0075] Table 1: Process Conditions and Test Results

[0076]

[0077] As can be seen from Table 1 above, the air volume in the first duct 203 is 2000 m³. 3 With a feed rate of 200 kg / h for the star feeder 12, a mixture temperature of 650°C fed into the air-powder mixer 4, a fly ash discharge rate of approximately 50% of the feed rate at the outlet of the first air-powder separator, a fly ash discharge rate of approximately 5%-10% of the feed rate at the outlet of the second air-powder separator, and a return air temperature of over 550°C in the second air duct 7, the dioxin concentration in the fly ash can be reduced from 0.193-0.497 ng-TEQ / g to 0.031-0.046 ng-TEQ / g. Therefore, under the above process conditions, a very high dioxin removal rate in fly ash has been achieved.

[0078] To prevent the regeneration of dioxins, the temperature of the fly ash after passing through the gas-powder mixer 4, the first gas-powder separator 601, and the second gas-powder separator 602 must remain above 550°C. The temperature is measured by the second temperature sensor 10 on the second duct 7. Control is implemented based on the temperature measured by the second temperature sensor 10. If the temperature measured by the second temperature sensor 10 is <550°C, the controller 14 increases the temperature in the first duct 203, i.e., increases the setpoint of the first temperature sensor 8, and controls the opening of the first air valve 101 and the second air valve 102 according to the control logic in step S100, thereby increasing the temperature in the second duct 7. Afterwards, the dioxin-mixed air returns to the incinerator 301 through the second duct 7 for combustion, where the dioxins are removed through secondary oxidation.

[0079] In this embodiment, the valve opening and the ash feeding amount of the star feeder 12 can be automatically controlled according to the detection data of the first temperature sensor 8, the second temperature sensor 10 and the particulate matter detector 11, realizing the automated control of the miniaturized fly ash dioxin removal device, which greatly simplifies the control process. At the same time, the fly ash desorption temperature is controlled within the range of 650℃-750℃, which effectively ensures the desorption rate of dioxins in fly ash, thereby improving the removal efficiency of dioxins in fly ash. Furthermore, most of the incompletely desorbed dioxins can be transported back to the incinerator 301 through the second air duct 7 with an internal temperature of not less than 550℃, which effectively avoids the regeneration of dioxins and eliminates secondary pollution.

[0080] The above are merely preferred embodiments of this application; however, the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and its improved concept, should be covered within the scope of protection of this application.

Claims

1. A miniaturized device for removing dioxins from fly ash, characterized in that, The system includes an exhaust duct with a temperature control component. One end of the exhaust duct is connected to the incineration system, and the other end is connected to a gas-powder mixer. An ash inlet is pre-set at the end of the exhaust duct near the gas-powder mixer. An exhaust separation component is connected to the output end of the gas-powder mixer. The gas output port of the exhaust separation component is connected to the secondary air duct of the incinerator through a second air duct. A first temperature sensor is installed in the exhaust duct, and a fan, a second temperature sensor, and a particulate matter detector are installed in the second air duct. The first temperature sensor, the fan, the second temperature sensor, and the particulate matter detector are all electrically connected to the controller. The gas-powder separation assembly includes a first gas-powder separator and a second gas-powder separator connected in series. Both the first and second gas-powder separators include a housing and a static separation chamber and a dynamic separation chamber disposed within the housing. The upper end of the static separation chamber has a cylindrical structure, and the lower end has a hollow conical structure. A gas-powder inlet is provided on one side of the static separation chamber, and a first powder outlet is provided at the lower end. A connecting pipe is embedded in the upper end of the static separation chamber. One end of the connecting pipe extends into a first conical guide plate inside the static separation chamber, and the other end of the connecting pipe connects to the dynamic separation chamber. A first conical guide plate and a second conical guide plate are fixed inside the static separation chamber. The outer edge of the upper end of the first conical guide plate is fixed... The system includes an annular baffle, a first conical guide plate with a first cylinder fixedly connected to its lower end, the lower end of the first cylinder extending into a second conical guide plate, a second cylinder fixedly connected to its lower end, and a third conical guide plate connected to its lower end. An annular guide plate is fixed to the inner wall of the static separation chamber, located between the first and second conical guide plates. The upper end of the dynamic separation chamber has a cylindrical structure, and the lower end has a hollow conical structure. A gas guide tube is embedded in the upper end of the dynamic separation chamber, with a cylindrical upper end and a hollow conical lower end. A gas outlet is located at the upper end of the gas guide tube, and a second powder outlet is located at the lower end of the dynamic separation chamber.

2. The miniaturized fly ash dioxin removal device according to claim 1, characterized in that, The incineration system includes an incinerator, a primary waste heat recovery device, and a secondary waste heat recovery device. The induced draft duct includes a first duct, one end of which is connected to a gas-powder mixer, and the other end of which is connected to a first branch duct and a second branch duct. The first branch duct is used to connect the pipeline between the incinerator and the primary waste heat recovery device, and the second branch duct is used to connect the pipeline between the primary waste heat recovery device and the secondary waste heat recovery device. The temperature control component includes a first air valve and a second air valve, the first air valve being installed in the first branch duct and the second air valve being installed in the second branch duct.

3. The miniaturized fly ash dioxin removal device according to claim 2, characterized in that, Both the first and second air valves are electrically controlled valves, and both are electrically connected to the controller.

4. The miniaturized fly ash dioxin removal device according to claim 3, characterized in that, The ash inlet is connected to the output end of the star feeder, the input end of the star feeder is used to connect to the ash source, and the star feeder is electrically connected to the controller.

5. The miniaturized fly ash dioxin removal device according to claim 3, characterized in that, The gas-powder inlet is located between the second and third conical guide plates. The third conical guide plate is located inside the hollow conical structure at the lower end of the static separation chamber. The annular guide plate has at least two guiding surfaces.

6. The miniaturized fly ash dioxin removal device according to claim 3, characterized in that, The end of the second duct away from the gas-powder separation component is connected to one of the input ends of the mixing chamber, the other input end of the mixing chamber is used to connect to the slag silo, and the output end of the mixing chamber is connected to the incinerator.

7. A method for removing dioxins from fly ash, characterized in that, Applied to the system as described in any one of claims 4-6, the method comprises: Start the fan and adjust the opening of the first and second air valves according to the detection data of the first temperature sensor to adjust the temperature of the mixture sent into the gas-powder mixer to 650℃-750℃. Start the rotary feeder and adjust the parameters of the gas-powder separation unit according to the detection data of the particulate matter detector so that the gas output by the gas-powder separation unit carries a preset amount of fly ash. Adjust the opening of the first and second valves according to the detection data of the second temperature sensor to regulate the temperature of the mixture in the second air duct to no less than 550℃.

8. The method for removing dioxins from fly ash according to claim 7, characterized in that, The amount of fly ash carried in the gas output by the gas-powder separation component is 5%-10% of the original fly ash amount.

9. The method for removing dioxins from fly ash according to claim 7, characterized in that, The air volume in the first duct is 1000m³. 3 / h-2000m 3 The ash feeding capacity of the star feeder is 200kg / h-300kg / h.

10. The method for removing dioxins from fly ash according to claim 7, characterized in that, The residence time of the mixture of hot air and fly ash in the air-powder mixer in the first air duct is 10s-30s.

Images