System for drying dechlorinated fly ash after water washing and low temperature dioxin cracking

Abstract

This application relates to a system for drying and dioxin-low-temperature pyrolysis of dechlorinated fly ash after washing, comprising a pyrolysis silo, a fly ash pyrolysis silo, a filter silo, and an emission silo. The pyrolysis silo is connected to the fly ash pyrolysis silo, conveying and dewatering the washed fly ash from municipal solid waste incineration. The fly ash pyrolysis silo includes a low-temperature pyrolysis furnace, an indirect water-cooled ash discharge device, a buffer ash silo, and a return material collection mechanism, all connected sequentially. The filter silo includes a bag filter, a flue gas dewatering device, a first activated carbon adsorption box, a catalytic oxidation-reduction device, and a cooling spray neutralization tower, all connected sequentially, and is connected to the fly ash pyrolysis silo. The emission silo is connected to the filter silo, discharging treated exhaust gas that meets standards. This device has low energy consumption, stable fly ash without clogging. It requires no nitrogen, produces less exhaust gas, and has low cost. Continuous feeding and discharging, with an annual output ≥50,000 tons. Discharge temperature <150℃, ensuring product quality. Oxygen control ≤1%, preventing coking. Water-cooled ash discharge is fast and non-clogging, dry ash is easy to store, and the equipment is durable.

Description

Technical Field

[0001] This application relates to the field of industrial waste gas treatment, and in particular to a system for drying dechlorinated fly ash after water washing and low-temperature dioxin pyrolysis. Background Technology

[0002] Currently, fly ash from municipal solid waste incineration on the market undergoes direct low-temperature thermal decomposition without water washing and dechlorination. This thermal decomposition process, operating at temperatures around 500℃, is energy-intensive and frequently experiences coking and agglomeration, leading to shutdowns. Maintenance and repair are difficult and time-consuming, and the exhaust gas contains complex toxic and harmful components, resulting in high treatment costs. Furthermore, the design output of individual units is low, severely mismatched with the enormous annual production of fly ash from municipal solid waste incineration in my country.

[0003] Therefore, it is necessary to establish a typical low-cost, high-efficiency, safe, and stable system for fly ash drying after water washing and dechlorination, followed by dioxin low-temperature pyrolysis. Utility Model Content

[0004] In view of this, this application proposes a system for drying dechlorinated fly ash after water washing and low-temperature pyrolysis of dioxins, including a pyrolysis silo, a fly ash pyrolysis silo, a filter silo, and an emission silo. The pyrolysis silo is connected to the fly ash pyrolysis silo and is used for conveying and dewatering the fly ash after washing following the incineration of municipal solid waste. The fly ash pyrolysis silo is connected to the pyrolysis material silo. The fly ash pyrolysis silo includes a low-temperature pyrolysis furnace, an indirect water-cooled ash discharge device, a buffer ash silo, and a return material collection mechanism. The low-temperature pyrolysis furnace, the indirect water-cooled ash discharge device, the buffer ash silo, and the return material collection mechanism are connected in sequence. The filter chamber is connected to the fly ash pyrolysis chamber. The filter chamber includes a bag filter, a flue gas dewatering device, a first activated carbon adsorption box, a catalytic oxidation-reduction device, and a cooling spray neutralization tower. The bag filter, flue gas dewatering device, first activated carbon adsorption box, catalytic oxidation-reduction device, and cooling spray neutralization tower are connected in sequence. The discharge chamber is connected to the filter chamber, and the discharge chamber is used to discharge treated exhaust gas that meets emission standards.

[0005] In one possible implementation, the pyrolysis silo includes a silo weighing and anti-clogging feeding device.

[0006] In one possible implementation, the system further includes a return material mechanism, the input end of which is connected to a low-temperature pyrolysis furnace and a silo weighing and anti-clogging feeding device, and the output end of which is connected to a bag filter dust collector.

[0007] In one possible implementation, the system further includes an indirect water-cooled ash discharge device connected to a low-temperature pyrolysis furnace.

[0008] In one possible implementation, the pyrolysis silo includes a drying silo and a twin-shaft paddle dryer.

[0009] In one possible implementation, the temperature inside the low-temperature pyrolysis furnace is between 300 and 500 degrees Celsius.

[0010] In one possible implementation, the system further includes a water supply subsystem, the input of which is connected to a twin-shaft paddle dryer, and the output of which is connected to a flue gas dewatering unit, a first activated carbon adsorption box, and a cooling spray neutralization tower.

[0011] In one possible implementation, the discharge chamber includes a first induced draft fan and a first exhaust stack, which are connected in sequence.

[0012] In one possible implementation, the water supply subsystem includes a water supply subsystem dust collector, a water supply subsystem air preheater, a water supply subsystem condenser, and a second activated carbon adsorption box, which are connected in sequence.

[0013] In one possible implementation, the water supply subsystem further includes a second induced draft fan and a second exhaust stack, which are connected in sequence, and the second induced draft fan is connected to a second activated carbon adsorption box.

[0014] The beneficial effects of this utility model are: It has a low detoxification temperature and low energy consumption. At a thermal decomposition temperature of 350℃, the fly ash remains stable, does not clump, and does not clog.

[0015] The detoxification process does not require nitrogen, resulting in less waste gas volume, less heat loss from flue gas, and savings in nitrogen production electricity costs; the waste gas treatment equipment has low investment and low operating costs.

[0016] Continuous feeding and discharging reduce storage space, reduce the scale of supporting process equipment construction, reduce the labor intensity of workers, ensure high safety, and make the entire process smoother, achieving an annual output of ≥50,000 tons per line.

[0017] Discharge temperature should be below 150℃ to avoid dioxin resynthesis temperature conditions; the product will be 100% qualified.

[0018] The waste gas undergoes solid-liquid-gas separation in the pretreatment system, which greatly reduces the amount of waste gas entering the waste gas treatment system and significantly lowers the investment and operating costs of the waste gas treatment system.

[0019] The oxygen content is always controlled at ≤1% during the detoxification process, which greatly reduces the process temperature required for dioxin detoxification, resulting in good energy saving and avoiding internal coking caused by high equipment temperature.

[0020] The indirect water-cooled ash discharge device adopts a twin-shaft paddle type, which has a large heat exchange area, fast ash cooling speed, and the twin shafts agitate each other to prevent clogging.

[0021] The indirect water-cooled heat exchange method produces low-temperature dry fly ash after pyrolysis, which is easy to collect and store. It does not cause serious corrosion to the materials of conveyors and storage equipment and has a long service life.

[0022] Other features and aspects of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0023] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this application together with the specification and serve to explain the principles of this application.

[0024] Figure 1 A structural diagram of a system for drying dechlorinated fly ash after water washing and low-temperature dioxin pyrolysis according to an embodiment of this application is shown. Detailed Implementation

[0025] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0026] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model or simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0029] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented without certain specific details. In some instances, methods, means, components, and circuits well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0030] The utility model of this application is a system for drying and dioxin-low temperature pyrolysis of dechlorinated fly ash after water washing. It is applied in the field of harmless treatment and resource utilization of fly ash from municipal solid waste incineration. It achieves efficient drying and volume reduction of fly ash after water washing and dechlorination, and degrades residual dioxin pollutants in fly ash through low temperature pyrolysis technology, ultimately producing materials that meet the standards for resource utilization and reducing the environmental hazards of fly ash.

[0031] specifically refer to Figure 1 , Figure 1 A structural diagram of a system for drying dechlorinated fly ash after washing and low-temperature dioxin pyrolysis according to an embodiment of this application is shown. As shown in the figure, the system includes a pyrolysis silo 101, a fly ash pyrolysis silo 102, a filter silo 103, and an emission silo 104. The pyrolysis silo 101 connects to the fly ash pyrolysis silo 102 and is used for conveying and dewatering the fly ash after washing following the incineration of municipal solid waste. The pyrolysis silo features anti-clogging vibration and weighing / metering functions. A sawtooth feeder continuously and evenly feeds the fly ash into the pyrolysis unit for heating and decomposition in a set quantity, all within a closed system. This achieves continuous feeding and discharging, reducing storage space, minimizing the scale of supporting process equipment, reducing labor intensity, increasing safety, and streamlining the entire process, enabling a single-line annual output of ≥50,000 tons.

[0032] In one specific embodiment, the conveying mechanism of the pyrolysis silo 101 includes a flow tube metering silo, a shaftless variable frequency feeding screw 101-11, a shaftless screw horizontal conveyor 101-12, a bucket elevator 101-13, and a variable frequency sawtooth screw feeder connected in sequence.

[0033] Specifically, the wide-flow metering hopper features anti-clogging vibration and weighing functions. The upper part of the hopper is a wide-flow pipe, and the lower outlet is a rectangle with a length approximately equal to the diameter of the upper part. The inner side of the lower part is lined with a layer of anti-sticking composite material to prevent material accumulation and clogging. The lower part of the hopper is equipped with a variable frequency shaftless screw conveyor, which can continuously feed materials according to a set amount, avoiding blockage.

[0034] The fly ash pyrolysis bin 102 is connected to the pyrolysis material bin 101. The fly ash pyrolysis bin 102 includes a low-temperature pyrolysis furnace 102-1, an indirect water-cooled ash discharge device 102-2, a buffer ash bin 102-3, and a return material collection mechanism. The low-temperature pyrolysis furnace 102-1, the indirect water-cooled ash discharge device 102-2, the buffer ash bin 102-3, and the return material collection mechanism are connected in sequence.

[0035] In one specific embodiment, the fly ash pyrolysis chamber 102 is divided into a preheating section, a decomposition section, and a quenching section from front to back. Fly ash first enters through the feed inlet, and is gradually heated to 350°C by the low-temperature pyrolysis furnace 102-1 before entering the decomposition section. The fly ash resides in the decomposition section for 30-60 minutes (controllable), and the oxygen content is consistently controlled below 1%. The pyrolyzed fly ash is discharged from the discharge outlet, enters the indirect water-cooled ash discharge device 102-2 for cooling, and then passes through the buffer ash silo 102-3 before entering the collection ash silo. The entire reaction process is counter-current; the vaporized water and pyrolysis products are discharged from the exhaust port of the pyrolysis device. Air carried by the fly ash during feeding is directly discharged from the preheating section and does not enter the pyrolysis section, effectively ensuring an oxygen-free environment in the pyrolysis section and achieving good energy-saving effects. The fly ash pyrolysis device uses electricity as its energy source.

[0036] In one specific embodiment, the counter-current low-temperature pyrolysis furnace 102-1 is divided into a feeding zone, a pyrolysis zone, and a discharging zone from front to back. The feeding zone is equipped with an anti-backflow mechanism to effectively alleviate material backflow. The pyrolysis zone is equipped with a heat transfer plate to ensure more thorough pyrolysis of the material. The discharging zone is short and smooth.

[0037] In one specific embodiment, the counter-current low-temperature pyrolysis furnace 102-1 uses electricity as its energy source, and can reach the required process temperature in approximately 3 hours. The fly ash temperature in the pyrolysis zone is set between 300℃ and 500℃, and can be precisely controlled within ±20℃ after the selected pyrolysis temperature is set. The material first enters the pyrolysis device through the discharge port of the screw conveyor. After passing through the feeding zone, the material is heated and dried, and then enters the pyrolysis zone to complete the pyrolysis. Finally, it falls through the discharge zone into the indirect water-cooled ash discharge device and is discharged into the buffer ash silo. The counter-current pyrolysis device utilizes the gas generated during the pyrolysis process to preheat the newly entering material, effectively supplementing the energy consumption required for the pyrolysis of the material, thus treating waste with waste and achieving good energy-saving effects. The counter-current pyrolysis system operates at near atmospheric pressure, with good sealing performance to prevent gas leakage from the counter-current pyrolysis device.

[0038] After being washed, the fly ash undergoes the aforementioned thermal decomposition, resulting in the removal of water, carbon monoxide, nitrogen oxides, ammonia, trace amounts of undecomposed dioxins, and low-volatility heavy metals from the flue gas. The remaining fly ash product has a dioxin content far below 50 ng TEQ / kg and can be used as a raw material for various products such as water-stabilized materials, roadbed materials, brick blocks, cement admixtures, concrete admixtures, and thermoplastic shaped materials.

[0039] The filter chamber 103 is connected to the fly ash pyrolysis chamber 102. The filter chamber 103 includes a bag filter 103-1, a flue gas dewatering device 103-2, a first activated carbon adsorption box 103-3, a catalytic oxidation-reduction device 103-4, and a cooling spray neutralization tower 103-5. The bag filter 103-1, the flue gas dewatering device 103-2, the first activated carbon adsorption box 103-3, the catalytic oxidation-reduction device 103-4, and the cooling spray neutralization tower 103-5 are connected in sequence. The discharge chamber 104 is connected to the filter chamber 103, and the discharge chamber 104 is used to discharge exhaust gas that has been treated and meets the emission standards.

[0040] In one possible implementation, the pyrolysis silo 101 includes a silo weighing and anti-blocking feeding device 101-1.

[0041] In one possible implementation, the system further includes a return material mechanism 105, the input end of which is connected to a low-temperature pyrolysis furnace 102-1 and a hopper weighing and anti-blocking feeding device 101-1, and the output end of the return material mechanism 105 is connected to a bag filter dust collector 103-1.

[0042] In one possible implementation, the system further includes an indirect water-cooled ash discharge device 102-2, which is connected to a low-temperature pyrolysis furnace 102-1.

[0043] In one possible implementation, the pyrolysis silo 101 includes a drying silo 101-2 and a twin-shaft paddle dryer 101-3.

[0044] In one possible implementation, the temperature inside the low-temperature pyrolysis furnace 102-1 is between 300 and 500 degrees Celsius.

[0045] In one possible implementation, the system further includes a water supply subsystem 106, the input of which is connected to a twin-shaft paddle dryer 101-3, and the output of which is connected to a flue gas dewatering device 103-2, a first activated carbon adsorption box 103-3, and a cooling spray neutralization tower 103-5.

[0046] In one possible implementation, the discharge chamber 104 includes a first induced draft fan 104-1 and a first exhaust pipe 104-2, which are connected in sequence.

[0047] In one possible implementation, the water supply subsystem 106 includes a water supply subsystem dust collector 106-1, a water supply subsystem air preheater 106-2, a water supply subsystem condenser 106-3, and a second activated carbon adsorption box 106-4, which are connected in sequence.

[0048] In one possible implementation, the water supply subsystem 106 further includes a second induced draft fan 106-5 and a second exhaust stack 106-6, which are connected in sequence. The second induced draft fan 106-5 is connected to the second activated carbon adsorption box 106-4.

[0049] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A system for dioxin low temperature cracking of dechlorinated fly ash after water washing and drying, characterized by, This includes a pyrolysis silo, a fly ash pyrolysis silo, a filtration silo, and an emission silo. The pyrolysis silo is connected to the fly ash pyrolysis silo and is used for conveying and dewatering the fly ash washed after incineration of municipal solid waste. The fly ash pyrolysis bin is connected to the pyrolysis silo. The fly ash pyrolysis bin includes a low-temperature pyrolysis furnace, an indirect water-cooled ash discharge device, a buffer ash silo, and a return material collection mechanism. The low-temperature pyrolysis furnace, the indirect water-cooled ash discharge device, the buffer ash silo, and the return material collection mechanism are connected in sequence. The filter chamber is connected to the fly ash pyrolysis chamber. The filter chamber includes a bag filter, a flue gas dewatering device, a first activated carbon adsorption box, a catalytic oxidation-reduction device, and a cooling spray neutralization tower. The bag filter, the flue gas dewatering device, the first activated carbon adsorption box, the catalytic oxidation-reduction device, and the cooling spray neutralization tower are connected in sequence. The discharge chamber is connected to the filter chamber, and the discharge chamber is used to discharge treated waste gas that meets emission standards.

2. The system of claim 1, wherein, The pyrolysis silo includes silo weighing and anti-blocking feeding equipment.

3. The system of claim 2, wherein, The system also includes a return material mechanism, the input end of which is connected to the low-temperature pyrolysis furnace and the silo weighing and anti-clogging feeding equipment, and the output end of which is connected to the bag filter dust collector.

4. The system of claim 3, wherein, The system also includes an indirect water-cooled ash discharge device, which is connected to the low-temperature pyrolysis furnace.

5. The system of claim 1, wherein, The pyrolysis silo includes a drying silo and a twin-shaft paddle dryer.

6. The system of claim 1, wherein, The temperature inside the low-temperature pyrolysis furnace is between 300 and 500 degrees Celsius.

7. The system of claim 5, wherein, The system also includes a water supply subsystem, the input of which is connected to the twin-shaft paddle dryer, and the output of which is connected to the flue gas dewatering device, the first activated carbon adsorption box, and the cooling spray neutralization tower.

8. The system of claim 1, wherein, The discharge chamber includes a first induced draft fan and a first exhaust stack, which are connected in sequence.

9. The system of claim 7, wherein, The water supply subsystem includes a water supply subsystem dust collector, a water supply subsystem air preheater, a water supply subsystem condenser, and a second activated carbon adsorption box, which are connected in sequence.

10. The system of claim 9, wherein, The water supply subsystem also includes a second induced draft fan and a second exhaust stack, which are connected in sequence. The second induced draft fan is connected to the second activated carbon adsorption box.

Images