Device for thermally decomposing dioxin in waste incineration fly ash at low temperature by adopting fluidized bed furnace

Abstract

The invention discloses a device for performing low-temperature thermal decomposition on dioxin in waste incineration fly ash by adopting a fluidized bed furnace, belongs to the technical field of harmless treatment of waste incineration fly ash, and relates to a device for performing low-temperature thermal decomposition on dioxin in waste incineration fly ash by adopting a fluidized bed furnace. The system is characterized by comprising a fluidized bed furnace pyrolysis device, a fly ash feeding system, a tail ash discharging system, a circulating fluidization wind power system, a heating medium heat source system and a control system. Heating a heating medium to 420-450 DEG C through a heating medium heat source system, introducing a heat exchanger in the fluidized bed furnace pyrolysis device, and heating fly ash in the furnace; the method comprises the following steps: heating, fluidizing and guiding the fly ash under a nitrogen condition, pyrolyzing the fly ash in a boiling state at 300-400 DEG C for more than 60 minutes, quenching and discharging; dioxin in tail ash and tail gas can be effectively reduced by more than 98%. The low-temperature thermal decomposition device overcomes the defects of an existing low-temperature thermal decomposition device and has the advantages of being sufficient in pyrolysis, high in removal efficiency, uniform in heat transfer, sufficient in energy utilization, high in fly ash adaptability, simple in device, reliable and stable in operation, small in occupied area, large in handling capacity, long in service life and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of harmless treatment of waste incineration fly ash, and relates to a device for thermally decomposing dioxins in waste incineration fly ash at low temperature by using a boiling furnace. Background Art

[0002] Fly ash from the incineration of domestic waste contains one or more substances such as heavy metals, dioxins, chloride salts, etc., which need to be removed to a certain extent through physical or chemical reactions, or their leaching properties must be inhibited so that the treated fly ash meets the requirements of subsequent utilization or disposal.

[0003] Low temperature thermal decomposition is to heat the fly ash in an oxygen-deficient or oxygen-free atmosphere at a temperature below 500 °C. 0 C low temperature thermal decomposition reaction, the process of dechlorination and detoxification of dioxins. Related research experiments show that: under nitrogen atmosphere, the temperature is 400 0 C, heated for 60 min, the removal rates of PCDDS / PCDFS and I-TEQ in the solid phase can reach 100%, and the total removal rates of PCDDS / PCDFS and I-TEQ are 98% and 100%, respectively.

[0004] Low-temperature thermal decomposition can efficiently dechlorinate and degrade dioxins, and has the advantages of simple operation and low energy consumption. It has great industrial application prospects in the harmless treatment and resource utilization of fly ash.

[0005] The Ministry of Ecology and Environment's "Technical Specifications for Pollution Control of Fly Ash from Incineration of Municipal Solid Waste" requires: "The dioxin content in fly ash treatment products should be controlled. Dioxin decomposition technologies such as low-temperature thermal decomposition, high-temperature sintering and high-temperature melting can be used. The total amount of dioxin residues in the treatment products should not exceed 50 ng-TEQ / kg (based on the dry weight of fly ash)"; "Particulate matter, heavy metals, dioxins and other atmospheric pollutants in the exhaust gas emitted during the low-temperature thermal decomposition, high-temperature sintering and high-temperature melting of fly ash should not exceed the emission concentration limits specified in GB18484."

[0006] Existing low-temperature thermal decomposition devices for fly ash from the incineration of domestic waste often have problems such as low purity of the oxygen-deficient atmosphere, insufficient pyrolysis, low removal efficiency, easy agglomeration and adhesion of fly ash during the thermal decomposition process, reduced heat transfer, waste of energy, and unstable equipment operation.

[0007] For example, the invention patent with application publication number CN 118385251 A, “A low-temperature thermal degradation system for fly ash with inert gas atmosphere to prevent compaction”, in order to solve the problem of high oxygen content and compaction prevention in fly ash, an extrusion device and a scattering device are set up in the front process, but the equipment still has the problem of easy agglomeration and adhesion on the thermal decomposition device side; for example, the utility model with authorization announcement number CN 215236709 U, “relating to a low-temperature thermal decomposition treatment device for fly ash from incineration of domestic waste”, uses a high-temperature fan to convert the 380-400℃ generated by the hot blast furnace into a low-temperature thermal decomposition device. 0 C hot flue gas is introduced into the sandwich structure of the low-temperature thermal decomposition reaction tower to heat the fly ash in the tower, and the heat transfer efficiency is not ideal; the utility model "Dioxin removal device and system for fly ash pyrolysis for harmless disposal of waste incineration fly ash" with authorization announcement number CN216175282U and the utility model "Dioxin removal device and system for fly ash pyrolysis for harmless disposal of waste incineration fly ash" with authorization announcement number CN216175283U, their core pyrolysis devices all adopt a spiral auger conveying and external heating method in an anaerobic environment. The fly ash is easy to agglomerate and stick in the auger, and the equipment is easily damaged at high temperatures; the utility model "A fly ash pyrolysis system for harmless treatment of waste incineration fly ash" with authorization announcement number CN221184170U, in order to improve the uniformity of heating of the fly ash, adopts multiple dispersions and then multiple aggregations for fine dispersion and unitized stirring and transportation. The equipment is complex and prone to unstable operation. Summary of the invention

[0008] In order to solve the shortcomings of the existing low-temperature thermal decomposition device for fly ash from the incineration of domestic waste, the present invention adopts the following technical solutions:

[0009] The present invention provides a device for low-temperature thermal decomposition of dioxins in fly ash from garbage incineration by using a fluidized bed furnace, characterized in that it comprises a fluidized bed furnace pyrolysis device, a fly ash feeding system, a tail ash discharging system, a circulating fluidized bed wind power system, a heat medium heat source system and a control system;

[0010] After the fly ash is locked, filled with nitrogen, and compressed and exhausted from the feeding system, it enters the boiling furnace pyrolysis device under low oxygen content; the inlet and outlet materials of the boiling furnace pyrolysis device are dynamically sealed, and nitrogen is replaced before pyrolysis operation, and nitrogen is filled during operation. During operation, the oxygen content of the gas in the boiling furnace pyrolysis device is kept below 0.5%; the heat medium is heated to 420~450 by the heat medium heat source system 0 C, introduced into the heat exchanger in the boiling furnace pyrolysis device to heat the waste incineration fly ash therein; the fly ash is heated, fluidized and guided under nitrogen conditions, boiling at 300~400 0After pyrolysis for more than 60 minutes at 370 °C, the tail ash is discharged from the tail ash discharging system after being rapidly cooled by air lock; the pyrolysis gas generated in the boiling furnace pyrolysis device is partially recycled as fluidizing air by the circulating fluidized wind system after dust collection, and partially discharged to the subsequent process; the dioxin content in the tail ash and tail gas can be effectively reduced by more than 98%;

[0011] The fluidized bed pyrolysis device is composed of a wind chamber, an air distribution plate, a material guide plate, a heat exchanger, and a dust collector; the fluidized bed pyrolysis device body is provided with a nitrogen inlet, an inspection door, etc., and is arranged with monitoring instruments and primary components for temperature, pressure, differential pressure, oxygen content, etc., and is connected to the control system through control signals; the fluidized bed pyrolysis device body is connected with a fly ash inlet, a tail ash outlet, a circulating air inlet, an air outlet, a heat medium inlet, a heat medium outlet, a nitrogen inlet, etc.;

[0012] The air chamber, air distribution plate, and guide plate are all arranged inside the fluidized bed pyrolysis device. When designing the fluidized bed pyrolysis device, the size and arrangement of the air chamber, air distribution plate, and guide plate are selected according to the content range of fly ash dioxins, the processing capacity of the device, etc., and a split air chamber, multi-layer air distribution plate, and multi-channel guide plate can be used; a powder leakage prevention design is adopted between the air distribution plate and the air chamber, and a hood structure is preferably adopted;

[0013] The heat exchanger is built into the boiling furnace pyrolysis device and is any indirect surface heat exchanger, preferably a tubular heat exchanger; the heat medium absorbs heat from the heat source, releases heat in the heat exchanger, and then returns to the heat source to absorb heat, thereby performing heat exchange and balance;

[0014] The dust collector is built into the boiling furnace pyrolysis device, and its type can be any high-temperature bag filter dust collector that is blown into the boiling furnace without oxygen-containing gas, such as a mechanical vibration high-temperature bag filter dust collector, a de-pinning integrated ceramic bag filter dust collector using nitrogen backblowing, etc. Pressure measuring points and differential pressure gauges are set at the inlet and outlet ends of the dust collector; after the waste incineration fly ash pyrolysis gas is dedusted by the dust collector, the dust content is reduced to 30mg / m 3 The following is recycled and discharged through the circulation fan;

[0015] The fly ash feeding system is composed of a fly ash feeding valve, an air-locking feeder, and a compression exhaust auger; the inlet end of the fly ash feeding valve is connected to the fly ash bin, the outlet end is connected to the air-locking feeder, the outlet end of the air-locking feeder is connected to the compression exhaust auger, and the outlet end of the compression exhaust auger is connected to the boiling furnace pyrolysis device;

[0016] The air lock feeder is a sealed impeller feeder, and its structure is shown in Figure 2 As shown, seals are provided in radial and axial directions, which have a good air locking effect;

[0017] The structure of the compression exhaust auger is shown in Figure 3As shown, it is a variable pitch auger, which is composed of a rotating shaft 1, a shell 2, an exhaust hole 3, etc. A nitrogen filling port is installed at the bottom of the shell, and flexible seals are installed at the top of the auger blade and the input shaft end in the axial and radial directions, which can realize nitrogen replacement, compressed exhaust, and nitrogen dispersion in the process of feeding the fly ash into the boiling furnace pyrolysis device, and the replaced and compressed gas is discharged after filtering; the compressed exhaust auger is continuously filled with nitrogen when the fly ash is fed, so as to reduce the amount of air and the overall oxygen content carried by the feed fly ash itself;

[0018] The fly ash discharging system is composed of a tail ash quenching conveying device and a tail ash air lock discharging valve. The inlet of the tail ash quenching conveying device is connected to the outlet of the boiling furnace pyrolysis device, and the outlet is connected to the tail ash air lock discharging valve.

[0019] The tail ash quenching conveying equipment is a powder material conveying equipment with a metal shell and an overall seal on the conveying journey, such as a screw conveyor, a chain conveyor, a FU chain conveyor, etc. The equipment is equipped with a cooling water pipe or a water jacket along the material direction, and the cooling water inlet and outlet are connected to the water pipeline; the tail ash is quenched to 60°C in a nitrogen environment through the quenching conveying equipment. 0 Discharge below C can prevent dioxin from regenerating;

[0020] Furthermore, the tail ash rapid cooling and conveying equipment adopts a compressed exhaust auger. Figure 3 The nitrogen injection port is cancelled and cooling water is added; the tail ash is discharged after air-locking compression and rapid cooling, and more than 50% of the pyrolysis gas contained in the tail ash is discharged through compressed air and returned to the boiling furnace pyrolysis device for cyclic degradation, effectively avoiding regeneration into toxic substances;

[0021] The tail ash air lock discharge valve is preferably Figure 2 In the sealed impeller feeder shown, the seals 2.1 and 2.3 are made of high temperature resistant materials;

[0022] The circulating fluidized pneumatic system is composed of an air outlet of a fluidized bed pyrolysis device connected to an inlet damper of a circulating fan and a circulating fan through a pipeline, an air outlet of the circulating fan connected to an air chamber regulating damper and an air chamber of the fluidized bed pyrolysis device through a pipeline on one side, and connected to an exhaust gas exhaust damper on the other side; the circulating fan and the fluidized bed pyrolysis device cooperate with each other through a pipe valve to form a circulating fluidized pneumatic system;

[0023] The circulating fan is heat-resistant to 420 0 C or above high temperature and high pressure blower, such as Roots blower and cascade centrifugal blower, its air volume and air pressure parameter configuration is selected in the design according to the output of the present invention, the furnace structure of the boiling furnace pyrolysis device, the thickness of the boiling material layer, etc.;

[0024] The circulating fan inlet damper, air chamber regulating damper and tail gas exhaust damper are all adjustable dampers, which can be operated locally and remotely, have excellent sealing performance and are resistant to high temperatures when fully closed;

[0025] The exhaust gas discharged has an emission ratio that varies according to the content of dioxins in the fly ash and the moisture content of the fly ash in the actual pyrolysis operation, and is controlled by a slightly negative pressure state in the furnace of the boiling furnace pyrolysis device; after the pollutants contained in the exhaust gas are measured, they can be directly discharged within the exhaust gas emission limit, and further treatment is required if they are higher than the limit, such as the installation of activated carbon adsorption, denitrification devices, etc., such as the present invention installed on the side of the waste incineration power plant, and can also be discharged into the tail flue before the denitrification device;

[0026] The heat medium heat source system includes a heat source, heat medium power equipment and connecting pipes, heat medium temperature, flow measurement points, etc.; it is connected to the heat exchanger in the boiling furnace pyrolysis device through connecting pipes to form a heat medium heat exchange system;

[0027] The heat source is any heat medium that can provide a temperature of up to 420 0 Any form of heat source above C, such as high-temperature heat-conducting heat medium furnace and hot air furnace, etc., can be used. The fuel can be biomass, gas, etc. according to the cost and local environmental protection requirements. If the present invention is arranged on the side of the waste incineration power plant, the flue gas at the tail flue can also be used as a heat source;

[0028] The heat medium can be steam, heat transfer oil, high temperature flue gas, molten salt, etc.

[0029] The heat medium power equipment can be a pump or a fan according to the type of heat medium;

[0030] The control system can monitor, control, protect and adjust the temperature, pressure, oxygen content, differential pressure in the boiling furnace pyrolysis device, the air volume and temperature of the circulating fluidized pneumatic system, the heat medium flow rate and temperature, and the operating parameters of all equipment in the device as a whole, so as to achieve the material and heat balance of the fly ash feed rate, discharge rate, circulating air volume and heat medium flow rate, so that the fly ash pyrolysis oxygen content, operation time and operation temperature meet the requirements, and achieve the optimal fly ash low-temperature thermal decomposition environment;

[0031] The control system can realize program control of the startup and feeding, temporary shutdown, continuous pyrolysis operation and shutdown process of the entire device;

[0032] The control system can adopt PLC or DCS;

[0033] The boiling furnace pyrolysis device, feeding and discharging system, heat source, circulating fan and other equipment, system and its connecting air ducts, heat medium pipelines, etc. are all provided with insulation layers;

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) It has the characteristics of sufficient pyrolysis, high removal efficiency, uniform heat transfer, sufficient energy utilization, and strong adaptability to the pyrolysis of fly ash with different moisture content and different dioxin content;

[0036] 2) It has the characteristics of simple structure, reliable and stable operation, small footprint, large processing capacity and long service life; BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawing is a schematic diagram of a device for thermally decomposing dioxins in waste incineration fly ash using a boiling furnace at low temperature according to the present invention;

[0038] Figure 1 : 1 fly ash feed valve 2 air lock feeder 3 compression exhaust auger 4 tail ash quenching and conveying equipment 4.1 cooling water inlet 4.2 cooling water outlet 5 tail ash air lock discharge valve 6 boiling furnace pyrolysis device 6.1 wind chamber 6.2 air distribution plate 6.3 guide plate 6.4 heat exchanger 6.5 dust collector 6.5.1 dust collector power equipment 7 circulating fan inlet damper 8 circulating fan 9 wind chamber regulating damper 10 tail gas exhaust valve 11 heat source 12 heat medium power equipment 13 control system 14 nitrogen valve 15, 16, 17, 18, 19, 20, 21, 22 temperature, pressure, oxygen, flow, differential pressure and other measuring points

[0039] Figure 2 Sealed impeller feeder 1 housing 2 feeder rotating parts 2.1 radial seal 2.2 axial seal

[0040] Figure 3 Compression exhaust auger 1 Rotating shaft 1.1 Radial seal at input shaft end 1.2 Blade top seal 1.3 Axial seal at input shaft end 2 Auger housing 3 Exhaust hole 3.1 Exhaust filter plate DETAILED DESCRIPTION

[0041] In order to explain the present invention more clearly, the specific implementation methods of the present invention will be described below in conjunction with the accompanying drawings. For those skilled in the art, other implementation methods can also be obtained based on these drawings without creative work;

[0042] When the fly ash from the incineration of domestic waste is collected at the power plant side, it is generally stored in a fly ash bin. It is in powder form, has a low bulk density, contains more air inside, has good fluidity, and is easy to agglomerate after being damp. The following embodiment is a powder fly ash. Agglomerated fly ash can be added with a front-end disintegration process;

[0043] Before feeding, nitrogen replacement is performed inside the fluidized bed furnace pyrolysis device 6. The operation is as follows: the air lock feeder 2, the compression exhaust auger 3, the tail ash quenching and conveying equipment 4, and the tail ash air lock discharge valve 5 are in a closed and sealed state; the air chamber regulating damper 9 is closed, the tail gas exhaust valve 10, the circulating fan 8 and the circulating fan inlet damper 7 are opened, and the air in the fluidized bed furnace pyrolysis device 6 is extracted until the pressure in the pyrolysis device 6 reaches about 1000Pa; the nitrogen valve 8 is opened, and the pyrolysis device 6 is filled with nitrogen until the oxygen content of the gas in the fluidized bed furnace is below 0.5%; the air chamber regulating damper 9 is opened, and the nitrogen valve 8 and the tail gas exhaust valve 10 are closed to stably maintain the oxygen content of the gas in the fluidized bed furnace 6 below 0.5%;

[0044] While nitrogen replacement is in progress, the heat source 11 is put into use, the heat medium power device 12 is turned on, and the gas temperature in the boiling furnace pyrolysis device 6 is heated to 420 0 C around and keep stable;

[0045] Open the fly ash feed valve 1, the air lock feeder 2, and the compression exhaust auger 3, and simultaneously continuously charge the compression exhaust auger 3 with nitrogen to start feeding;

[0046] The feeding amount is gradually increased from small to large; the tail ash quenching conveying equipment 4 and the tail ash air lock discharge valve 5 are opened with a delayed delay; in this process, the circulating air volume and the tail gas emission ratio are adjusted through the control system 13 to maintain a slightly negative pressure state in the boiling furnace pyrolysis device 6; the heat medium flow rate is adjusted to maintain the temperature in the boiling furnace pyrolysis device 6 at 420 0 C; adjust the feed rate so that the feed fly ash undergoes 60 to 90 minutes of pyrolysis in the boiling furnace pyrolysis device 6 and then is rapidly cooled and discharged through the discharging system; near the designed rated output, confirm that the operating parameters of the entire device are stable, measure the content of pollutants after pyrolysis, and further confirm the maximum output of this batch of fly ash varieties in the device of the present invention;

[0047] Based on the maximum output, the continuous pyrolysis feed rate is reduced by 5% to carry out continuous pyrolysis operation:

[0048] During the continuous pyrolysis operation of fly ash, the control system 13 monitors and controls the temperature, pressure, and oxygen content in the fluidized bed furnace pyrolysis device, adjusts the fly ash feed rate, tail ash discharge rate, circulating air volume, heat medium flow rate, tail gas emission rate, etc., maintains the stable boiling state of the fly ash in the fluidized bed furnace pyrolysis device 6 and the fly ash pyrolysis operation time, furnace temperature, furnace oxygen content, etc. in the fluidized bed furnace;

[0049] By setting the blowing time interval of the dust collector power equipment 6.5.1, the differential pressure on both sides of the dust collector 6 is maintained within the normal range;

[0050] If necessary, temporarily stop the material and operate as follows:

[0051] Close the air lock feeder 2, the compression exhaust auger 3, delay the closure of the tail ash quenching and conveying equipment 4, the tail ash air lock discharge valve 5, close the fly ash feed valve 1, the nitrogen valve 8, stop the heat source 11, stop the heat medium power equipment 12, delay the shutdown of the circulation fan 8, the dust collector power equipment 6.5.1, close the circulation fan inlet damper 7, close the air chamber regulating damper 9, and the tail gas exhaust valve 10;

[0052] When the material is temporarily stopped, the pyrolysis device of the fluidized bed furnace is in a state of heat preservation, ash storage and oxygen-free;

[0053] To re-feed after a temporary stop, proceed as follows:

[0054] Activate the heat source 11, start the heat medium power device 12, put the dust collector power device 6.5.1 into use, open the air chamber regulating damper 9, slightly open the exhaust valve 10, start the circulating fan 8, and the circulating fan inlet damper 7, so that the materials in the boiling furnace pyrolysis device 6 are fluidized normally;

[0055] After the temperature and oxygen content in the boiling furnace pyrolysis device 6 are normal, the operation is carried out according to the requirements of "continuous pyrolysis operation";

[0056] When the pyrolysis equipment needs to be repaired or shut down, operate as follows:

[0057] Shut down all power and thermal equipment of the device of the present invention, close the fly ash feed valve 1, and discharge and repair the material through the wind chamber and the maintenance manhole of the boiling furnace pyrolysis device body;

[0058] If the device of the present invention is shut down for a long period of time, the manhole of the boiling furnace pyrolysis device can be cleaned and then filled with nitrogen for protection.

Claims

1. A device for thermally decomposing dioxins in fly ash from garbage incineration using a boiling furnace at low temperature, characterized in that , including boiling furnace pyrolysis device, fly ash feeding system, tail ash discharging system, circulating fluidized bed wind system, heat medium heat source system and control system; After the fly ash is locked, filled with nitrogen, and compressed and exhausted from the feeding system, it enters the boiling furnace pyrolysis device under low oxygen content; the inlet and outlet materials of the boiling furnace pyrolysis device are dynamically sealed, and nitrogen is replaced before pyrolysis operation, and nitrogen is filled during operation. During operation, the oxygen content of the gas in the boiling furnace pyrolysis device is kept below 0.5%; the heat medium is heated to 420~450 by the heat medium heat source system 0 C, introduced into the heat exchanger in the boiling furnace pyrolysis device to heat the waste incineration fly ash; the fly ash is heated, fluidized and guided under nitrogen conditions, boiling at 300~400 0 After pyrolysis for more than 60 minutes at 370 °C, the tail ash is discharged from the tail ash discharging system after being rapidly cooled by air lock; The pyrolysis gas generated in the boiling furnace pyrolysis device is partially recycled as fluidizing air by the circulating fluidized wind system after dust collection, and partially discharged to the subsequent process.

2. The device for low-temperature thermal decomposition of dioxins in waste incineration fly ash using a boiling furnace according to claim 1, characterized in that: The boiling furnace pyrolysis device is composed of a wind chamber, an air distribution plate, a material guide plate, a heat exchanger, and a dust collector; The fluidized bed pyrolysis device body is provided with a nitrogen inlet, an inspection door, etc., and is equipped with monitoring instruments and primary elements for temperature, pressure, differential pressure, oxygen content, etc., and is connected to the control system through control signals; The fluidized bed pyrolysis device body is connected with a fly ash inlet, a tail ash outlet, a circulating air inlet, an air outlet, a heat medium inlet, a heat medium outlet, a nitrogen inlet, etc.; The air chamber, air distribution plate, and guide plate are all arranged inside the fluidized bed pyrolysis device. When designing the fluidized bed pyrolysis device, the size and arrangement of the air chamber, air distribution plate, and guide plate can be selected according to the content range of fly ash dioxins, the processing capacity of the device, etc., such as using a split air chamber, multi-layer air distribution, and multi-channel guide plates. The air distribution plate and the air chamber are designed to prevent powder leakage, preferably using an air cap structure; The heat exchanger is built into the boiling furnace pyrolysis device and is any indirect surface heat exchanger, preferably a tubular heat exchanger; The dust collector is built into the boiling furnace pyrolysis device, and its type can be any high-temperature filter bag dust collector that blows oxygen-free gas into the boiling furnace, such as a mechanical vibration type high-temperature filter bag dust collector, a de-pinning integrated ceramic filter bag dust collector using nitrogen backblowing, etc.; The dust collector is provided with pressure measuring points and a differential pressure gauge at its inlet and outlet ends.

3. The device for low-temperature thermal decomposition of dioxins in waste incineration fly ash using a boiling furnace according to claim 1, characterized in that: The fly ash feeding system is composed of a fly ash feeding valve, an air lock feeder, and a compression exhaust auger; The inlet end of the fly ash feed valve is connected to the fly ash bin, and the outlet is connected to the air lock feeder, the outlet end of the air lock feeder is connected to the compression exhaust auger, and the outlet end of the compression exhaust auger is connected to the boiling furnace pyrolysis device; The air lock feeder is a sealed impeller feeder, which is provided with radial and axial seals; The compression exhaust auger is a variable pitch auger, which is composed of a rotating shaft, a shell, an exhaust hole, etc. A nitrogen filling inlet is installed at the bottom of the shell, and flexible seals are installed at the top of the auger blade and the input shaft end in the axial and radial directions, which can realize nitrogen replacement, compression exhaust, and nitrogen dispersion of fly ash during the process of being sent to the boiling furnace pyrolysis device, and the replaced and compressed gas is discharged after filtering; The compressed exhaust auger continuously fills nitrogen when the fly ash is fed, so as to reduce the amount of air and the overall oxygen content carried by the fed fly ash itself.

4. The device for low-temperature thermal decomposition of dioxins in waste incineration fly ash using a fluidized bed furnace according to claim 1, characterized in that: The fly ash discharging system is composed of a tail ash quenching conveying device and a tail ash air lock discharging valve. The inlet of the tail ash quenching conveying device is connected to the outlet of the boiling furnace pyrolysis device, and the outlet is connected to the tail ash air lock discharging valve. The tail ash quenching conveying equipment is a powder material conveying equipment with a metal shell and an overall seal on the conveying stroke, such as an auger, a chain conveyor, an FU chain conveyor, etc. The equipment is equipped with a cooling water pipe or a water jacket along the material direction, and the cooling water inlet and outlet are connected to the water pipeline; Furthermore, the tail ash rapid cooling and conveying equipment adopts a compressed exhaust auger, eliminates the nitrogen injection port, and adds cooling water; The tail ash air lock discharge valve is preferably a sealed impeller feeder, and the sealing element is made of high temperature resistant material.

5. The device for low-temperature thermal decomposition of dioxins in waste incineration fly ash using a boiling furnace according to claim 1, characterized in that: The circulating fluidized bed wind power system is composed of a fluidized bed pyrolysis device air outlet connected to a circulating fan inlet damper and a circulating fan through a pipeline, and a circulating fan air outlet connected to a wind chamber regulating damper and a fluidized bed pyrolysis device air chamber through a pipeline on one side and connected to an exhaust gas exhaust damper on the other side; The circulating fan is heat-resistant to 420 0 C or above high temperature and high pressure blower, such as Roots blower and cascade centrifugal blower, its air volume and air pressure parameter configuration is selected in the design according to the output of the present invention, the furnace structure of the boiling furnace pyrolysis device, the thickness of the boiling material layer, etc.; The circulating fan inlet damper, air chamber regulating damper and tail gas exhaust damper are all adjustable dampers, which can be operated locally and remotely, have excellent sealing performance and are resistant to high temperatures when fully closed; The exhaust gas has an emission ratio that varies according to the dioxin content and water content of the fly ash in the actual pyrolysis operation, and is controlled by a slightly negative pressure state in the boiling furnace pyrolysis device.

6. The device for low-temperature thermal decomposition of dioxins in waste incineration fly ash using a fluidized bed furnace according to claim 1, characterized in that The heat medium heat source system includes heat source, heat medium power equipment and connecting pipelines, heat medium temperature, flow measurement points, etc.; The heat source is any heat medium that can provide a temperature of up to 420 0 C or above, such as high-temperature heat-conducting heat medium furnace and hot air furnace, etc., and the fuel can be biomass, gas, etc. according to the cost and local environmental protection requirements. If the device of the present invention is arranged on the side of the waste incineration power plant, the flue gas at the tail flue can also be used as a heat source; The heat medium can be steam, heat transfer oil, high temperature flue gas, molten salt, etc. The heat medium power equipment can be a pump or a fan according to the type of heat medium.

7. The device for low-temperature thermal decomposition of dioxins in waste incineration fly ash using a boiling furnace according to claim 1, characterized in that: The control system can monitor, control, protect and adjust the temperature, pressure, oxygen content, differential pressure in the boiling furnace pyrolysis device, the air volume and temperature of the circulating fluidized pneumatic system, the heat medium flow rate and temperature, and the operating parameters of all equipment in the device as a whole, so as to achieve the material and heat balance of the fly ash feed rate, discharge rate, circulating air volume and heat medium flow rate, so that the fly ash pyrolysis oxygen content, operation time and operation temperature meet the requirements, and achieve the optimal fly ash low-temperature thermal decomposition environment; The control system can realize program control of the startup and feeding, temporary shutdown, continuous pyrolysis operation and shutdown process of the entire device; The control system may adopt PLC or DCS.

8. The device for low-temperature thermal decomposition of dioxins in waste incineration fly ash using a fluidized bed furnace according to claim 1, characterized in that: The boiling furnace pyrolysis device, feeding and discharging system, heat source, circulating fan and other equipment, system and their connecting air ducts, heat medium pipelines and the like are all provided with insulation layers.

Images