A hazardous waste incineration system and its operating process

Abstract

This invention discloses a hazardous waste incineration system and its operating process. The system includes a hazardous waste incinerator, a primary waste heat boiler, a high-temperature dust collector, a secondary waste heat boiler, a medium-high temperature dust removal-denitrification and dioxin removal device, an economizer, a GGH flue gas heat exchanger, an induced draft fan, and a chimney, all connected sequentially via a flue. A dry acid removal system is located between the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device via a flue. The GGH flue gas heat exchanger is further connected to a wet acid removal system via a flue, and the wet acid removal system is reconnected to the GGH flue gas heat exchanger via a flue. This invention's hazardous waste incineration system is highly adaptable to hazardous waste, effectively solves the problem of dioxin regeneration, improves the system's energy utilization rate, shortens the process chain length, and achieves ultra-low emissions of hazardous waste flue gas.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, specifically relating to a hazardous waste incineration system and its operating process. Background Technology

[0002] Hazardous waste, also known as hazardous waste, refers to solid waste listed in the National Hazardous Waste Inventory or identified as having hazardous characteristics according to national hazardous waste identification standards and methods. Hazardous waste contains a large amount of harmful substances, causing enormous damage to the surrounding environment and posing a significant threat to human life; therefore, it must be treated to render it harmless. Hazardous waste incineration is currently a widely used technology that can effectively render combustible hazardous waste harmless and reduce its volume. However, due to the high concentration of harmful components in hazardous waste, the gases produced after high-temperature incineration contain high concentrations of dioxins, dust, and SO2. x HCl, NO x Pollutants such as dioxins and HCl must be treated by a flue gas purification system to meet emission standards before they can be discharged. In particular, the content of dioxins and HCl is relatively high. Dioxins are currently the most toxic substances known and are extremely harmful to the human body; while high concentrations of HCl are not only difficult to treat, but also extremely corrosive, placing extremely high demands on the materials of downstream equipment in the incinerator.

[0003] Pollutants from hazardous waste incineration generally contain dust (fly ash) and NO. x Harmful substances such as HCl, SO2, and dioxins are present. Dust is typically removed using baghouse dust collectors, which are effective in removing dust. Fly ash is the ash collected from the system equipment after incineration, mainly originating from dust in the flue gas and ash generated during flue gas purification processes, such as desulfurization ash. Because the dust in the flue gas contains heavy metals and other harmful substances, most of the collected fly ash is classified as hazardous waste, and the cost of treating hazardous waste is very high. x The content of dioxins is relatively low, and SNCR denitrification can be used, but this will lead to ammonia slip. Ammonia slip, under low-temperature conditions at the downstream end, may react with HCl and other substances in the flue gas to form aerosols, causing not only pollution but also excessive dust. Due to the high initial concentrations of HCl and SO2, meeting emission standards generally requires a combination of multiple desulfurization processes, such as dry + wet methods. Dioxin incineration typically involves a secondary combustion chamber, providing a flue gas residence time of >1100℃ for 2 seconds to reduce the initial formation of dioxins. However, because the flue gas, especially the dust, carries a large amount of dioxin precursors, dioxins are regenerated in the range of approximately 200–550℃. Therefore, existing hazardous waste incineration projects generally use water spray quench towers to rapidly cool the flue gas within 1 second to avoid this area, thereby reducing dioxin concentration. Even so, after quenching, the dioxin concentration in the flue gas can still reach close to 10 ng-TEQ / Nm³. 3Even with activated carbon adsorption at the back end, there is still a risk of failing to meet standards. Furthermore, since quench towers typically use rapid evaporation and cooling via water spraying, on the one hand, the waste heat energy in the 200–550°C range of the flue gas is lost and cannot be utilized; on the other hand, as the temperature decreases and the moisture content increases, the corrosiveness and humidity of the flue gas after the quench tower increase significantly, making the equipment more prone to corrosion and blockage.

[0004] There are numerous patents and applications related to hazardous waste incineration systems. Currently, the more mature mainstream process employs a combination of technologies: rapid cooling + dry acid removal + activated carbon injection + bag filter + wet scrubbing. For example, patent CN103611399B describes a technology that uses a dual-fluid spray gun to rapidly cool the incinerated flue gas, avoiding the dioxin regeneration zone. The gas then undergoes dry acid removal, activated carbon adsorption of dioxins and heavy metals, bag filter dust collection, and finally wet acid removal before being discharged. While this technology is widely used, it suffers from drawbacks such as incomplete dioxin reduction, high fly ash production, low energy utilization, low acid removal efficiency, lack of a denitrification system, susceptibility to corrosion and clogging, and generally low overall flue gas emission standards.

[0005] Announcement No. CN109185897B provides a gas purification and fly ash treatment system for flue gas from the incineration of high-chlorine hazardous waste. The flue gas purification process employs a combination of quenching, catalytic bag filter, dry acid removal, bag filter, water washing acid removal, alkaline washing acid removal, wet electrostatic precipitator, and activated carbon layer adsorption. This technology is primarily designed for the incineration of high-chlorine hazardous waste, thus utilizing multiple coupled processes for acid removal and dioxin removal to improve efficiency. It also exhibits greater adaptability to hazardous waste raw materials and higher purification efficiency. However, the system appears quite complex and does not address issues such as corrosion, clogging, and low energy utilization caused by quenching.

[0006] The patent with publication number CN211345334U employs a waste heat boiler + economizer + semi-dry acid removal + activated carbon injection + dust collector + heat exchanger + SCR + heat exchanger. This technology introduces equipment such as a waste heat boiler, economizer, and heat exchanger to recover and utilize the waste heat from the flue gas generated by incineration; the economizer achieves rapid cooling to reduce dioxin formation; a semi-dry acid removal process is used; and an SCR denitrification system is connected at the downstream end to achieve NO removal. x Ultra-low emissions. However, this technology has problems such as the difficulty of rapid cooling of the economizer, the need for steam heating for low-temperature SCR, incomplete dioxin emission reduction, and low efficiency of semi-dry acid removal.

[0007] In summary, the current system technologies for hazardous waste incineration mainly have the following problems:

[0008] (1) Using a quench tower to reduce dioxin formation can reduce the temperature. However, if water spraying is used for quenching, a large amount of waste heat from the flue gas will be lost, and corrosion and blockage of downstream equipment will occur. If the economizer mentioned in CN211345334U is used, its heat exchange efficiency is lower than that of direct evaporation heat exchange. It is extremely difficult to cool the flue gas quickly within 1 second. Moreover, although the moisture content of the cooled flue gas does not increase, its corrosiveness is still relatively high.

[0009] (2) Dioxin emission reduction is incomplete. Quenching towers can only reduce the regeneration of dioxins, but the actual dioxin levels remain high after quenching. Furthermore, current hazardous waste standards are too low, necessitating upgrades. For example, the current national standard for dioxin emissions from hazardous waste is 0.5 ng-TEQ / Nm³. 3 In contrast, the national standard for waste incineration requires a concentration of 0.1, with some projects even requiring a concentration of 0.01.

[0010] (3) Conventional technologies have poor emission reduction effects. my country’s current emission standards for hazardous waste flue gas are far inferior to those for similar municipal solid waste incineration standards, and there will inevitably be a need for upgrading and retrofitting in the future. However, if the CN109185897B system is adopted, the overall process chain is too long and still cannot solve problems such as energy utilization, corrosion, and blockage.

[0011] (4) The existing technology is not stable enough. Due to the complex and variable nature of hazardous waste, the concentration of pollutants in its flue gas varies greatly. The existing technology obviously cannot withstand the large fluctuations of pollutants. For example, for high-chlorine hazardous waste, more efficient systems with more processes are needed, such as CN109185897B.

[0012] (5) The use of dry deacidification results in a large increase in fly ash. The fly ash collected by a single dust collector contains both dust from the flue gas and deacidification byproducts, which can only be identified as hazardous waste, thus greatly increasing the treatment cost. Summary of the Invention

[0013] To address the shortcomings of existing technologies, this invention provides a hazardous waste incineration system and its operating process, which is highly adaptable to hazardous waste, effectively solves the problem of dioxin regeneration, improves the system's energy utilization rate, shortens the process chain length, and achieves ultra-low emissions of hazardous waste flue gas.

[0014] This invention is achieved through the following technical solution:

[0015] A hazardous waste incineration system includes a hazardous waste incinerator, a primary waste heat boiler, a high-temperature dust collector, a secondary waste heat boiler, a dry desulfurization system, a medium-high temperature dust removal-denitrification and dioxin removal device, an economizer, a GGH flue gas heat exchanger, a wet desulfurization system, an induced draft fan, and a chimney.

[0016] The hazardous waste incinerator is connected in sequence via a flue to the primary waste heat boiler, the high-temperature dust collector, the secondary waste heat boiler, the medium-high temperature dust removal-denitrification and dioxin removal device, the economizer, and the GGH flue gas heat exchanger.

[0017] The dry acid removal system is installed between the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device via a flue.

[0018] The GGH flue gas heat exchanger includes a flue gas inlet, a hot flue gas inlet, a cold flue gas inlet, and a flue gas outlet. The economizer is connected to the flue gas inlet of the GGH flue gas heat exchanger through a flue. The hot flue gas inlet of the GGH flue gas heat exchanger is connected to the wet acid removal system through a flue. The wet acid removal system is connected back to the cold flue gas inlet of the GGH flue gas heat exchanger through a flue. The flue gas outlet of the GGH flue gas heat exchanger is connected to the induced draft fan through a flue.

[0019] The induced draft fan is connected to the chimney via a flue.

[0020] Preferably, the system also includes a fly ash disposal system, wherein the hazardous waste incinerator, the primary waste heat boiler, and the high-temperature dust collector are all connected to the fly ash disposal system via separate flues.

[0021] Preferably, it also includes an ammonia injection system, which is located between the primary waste heat boiler and the high-temperature dust collector; or between the high-temperature dust collector and the secondary waste heat boiler; or between the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device.

[0022] Preferably, the system also includes a deacidification ash recycling system and a deacidification ash resource utilization system, both of which are connected to the medium-high temperature dust removal-denitrification and dioxin removal device. The deacidification ash recycling system is connected back to the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device through a flue.

[0023] Preferably, it also includes a waste heat utilization device, wherein the economizer is provided with a flue that is sequentially connected to the secondary waste heat boiler and the primary waste heat boiler, and finally connected to the waste heat utilization device.

[0024] Preferably, the high-temperature dust collector is a high-temperature ceramic dust collector or a high-temperature metal dust collector.

[0025] Preferably, the medium-high temperature dust removal-denitrification and dioxin removal device is an integrated device or a separate design of medium-high temperature dust removal device + SCR denitrification and dioxin removal device; the filter element of the medium-high temperature dust removal-denitrification and dioxin removal device is made of ceramic or metal.

[0026] An operating process for a hazardous waste incineration system includes the following steps:

[0027] Step 1) After the hazardous waste enters the hazardous waste incineration system, it first enters the hazardous waste incinerator for incineration. The hazardous waste incinerator also includes a secondary combustion chamber, which provides an incineration temperature of >1100℃ and a flue gas residence time of 2s to reduce dioxin production.

[0028] Step 2) The high-temperature flue gas after incineration is cooled to about 550°C by a primary waste heat boiler to recover its heat and then enters a high-temperature dust collector to intercept and remove most of the dust in the flue gas.

[0029] Step 3) After dust removal, the flue gas enters the secondary waste heat boiler for waste heat recovery again, while the flue gas temperature drops to 250-300℃.

[0030] Step 4) Flue gas at 250-300°C enters the medium-high temperature dust removal-denitrification and dioxin removal device, and a deacidifying agent is sprayed in through the dry deacidification system to react with the acidic gases in the flue gas, reduce the concentration of acidic gases, and reduce the risk of corrosion; the medium-high temperature dust removal-denitrification and dioxin removal device is also used as a reaction vessel for deacidification.

[0031] Step 5) The medium-high temperature dust removal-denitrification and dioxin removal device is equipped with a filter element, and a catalyst is covered on the filter element; the filter element removes dust and collects the fly ash generated by the dry method to ensure that the dust meets the standards; the catalyst simultaneously catalyzes the denitrification and dioxin removal, so that the dioxins are completely decomposed.

[0032] Step 6) After passing through the medium-high temperature dust removal-denitrification and dioxin removal device, the flue gas completes denitrification, dioxin removal, dust removal and partial acid removal, and enters the economizer to further recover the remaining energy, and the flue gas temperature drops to about 200℃;

[0033] Step 7) The flue gas at around 200°C passes through the GGH flue gas heat exchanger and then enters the wet desulfurization system to remove the remaining acidic gases. The gas then flows back into the GGH flue gas heat exchanger, where it exchanges heat between the high-temperature flue gas before wet desulfurization and the low-temperature flue gas after wet desulfurization. In the high-temperature section, the flue gas cools from 200°C to around 100°C before entering the wet desulfurization system. In the low-temperature section, the flue gas from the wet desulfurization system, which is around 60°C, is heated to around 160°C. The flue gas before and after wet desulfurization achieves non-contact heat exchange within the GGH flue gas heat exchanger.

[0034] Step 8) Finally, the flue gas that is returned to the GGH flue gas heat exchanger through the wet desulfurization system enters the induced draft fan through the flue gas outlet. After the clean flue gas meets the standards, it is discharged into the atmosphere through the chimney by the induced draft fan.

[0035] Preferably, the method further includes steps 9), 10), 11), and 12), as detailed below:

[0036] Step 9) Ash generated by hazardous waste incinerators, primary waste heat boilers and high-temperature dust collectors is treated as hazardous waste and enters the incineration fly ash disposal system for harmless treatment.

[0037] Step 10) The ammonia injection system injects the SCR denitrification reactant into the flue gas. The high-temperature flue gas heat evaporates the reactant to generate NH3, which then reacts with NO under the action of a catalyst. x The reaction produces harmless N2; the injection point of the ammonia injection system can be selected between the primary waste heat boiler and the high-temperature dust collector, between the high-temperature dust collector and the secondary waste heat boiler, or between the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device.

[0038] Step 11) The high-temperature dust removal, denitrification, and dioxin removal device will circulate a portion of the collected deacidification fly ash through the deacidification ash recycling system to the high-temperature dust removal, denitrification, and dioxin removal device for further deacidification, thereby improving deacidification efficiency and utilization rate of the deacidification agent; the remaining portion will be utilized through the deacidification ash resource utilization system.

[0039] Step 12) The primary waste heat boiler, secondary waste heat boiler and economizer recover the energy of the flue gas by heating steam with the waste heat of the flue gas and realize the waste heat utilization device.

[0040] The beneficial effects of this invention are as follows:

[0041] (1) Dust removal is carried out at high temperatures to avoid the resynthesis of dioxins in the low-temperature region. This eliminates the need for a quench tower, allows for the recovery and utilization of residual heat from the flue gas, and avoids problems such as corrosion and blockage caused by water spray quenching. A major reason for high dioxin levels in hazardous waste is the resynthesis at around 200–550°C, and fly ash is the main reactant and catalyst source for dioxin resynthesis. Therefore, almost completely removing fly ash from the flue gas at high temperatures will greatly reduce the resynthesis of dioxins, thereby avoiding the use of a quench tower.

[0042] (2) After dust removal in the high-temperature section, the dust content in the flue gas is greatly reduced, which reduces the wear and tear on subsequent equipment caused by the flue gas.

[0043] (3) The medium-high temperature denitrification technology is adopted, which has higher denitrification efficiency and achieves ultra-low emissions. Due to the high denitrification temperature and its placement after the high temperature ceramic dust collector, there is no need to heat the flue gas, and there is no need to worry about the risk of ammonium bisulfate or alkali metal poisoning. The system has low operating costs, and the catalyst has high efficiency and long life.

[0044] (4) A two-stage dust collector is installed to separate the highly toxic fly ash from the non-toxic and harmless deacidification ash. The fly ash is treated as hazardous waste, while the deacidification ash can be utilized as a resource. Compared with the conventional method (which mixes the two and both are treated as hazardous waste), this scheme effectively reduces the amount of fly ash produced as hazardous waste.

[0045] (5) Install a catalytic dioxin removal device instead of activated carbon injection. On the one hand, dioxins are removed more thoroughly; on the other hand, the spraying of activated carbon avoids the generation of hazardous waste again.

[0046] (6) A multi-stage waste heat recovery system is set up to maximize the recovery of heat from the flue gas after incineration, thereby improving the economic benefits of the incineration plant. Compared with conventional hazardous waste incineration systems that require rapid cooling, which results in the inability to utilize the waste heat of flue gas at 200-550°C, this invention can utilize almost all the waste heat of the flue gas.

[0047] (7) Installing a GGH system before wet processing ensures that the final flue gas temperature is higher, which reduces the corrosion of the flue gas on the induced draft fan and chimney, improves the diffusivity of the flue gas, reduces the ground concentration of pollutants, and reduces the harm of pollutants to the environment.

[0048] (8) Using SCR denitrification instead of SNCR results in lower ammonia escape and avoids excessive ammonia in flue gas from generating ammonium chloride and other aerosols at low temperatures, which would lead to excessive dust levels.

[0049] (9) It adopts a multi-stage series method, with two-stage acid removal, two-stage dust removal, and two-stage dioxin removal. It has high flue gas purification efficiency, strong adaptability to raw materials, and achieves ultra-low emissions. Attached Figure Description

[0050] Figure 1 This is a process flow diagram of the hazardous waste incineration system of the present invention;

[0051] Figure 2 This is a partial enlarged view of the GGH flue gas heat exchanger.

[0052] In the diagram: 1. Hazardous waste incinerator; 2. Primary waste heat boiler; 3. High-temperature dust collector; 4. Secondary waste heat boiler; 5. Dry desulfurization system; 6. Medium- and high-temperature dust removal, denitrification, and dioxin removal device; 7. Economizer; 8. GGH flue gas heat exchanger; 8-1. Flue gas inlet; 8-2. Hot flue gas outlet; 8-3. Cold flue gas outlet; 8-4. Flue gas outlet; 9. Wet desulfurization system; 10. Exhaust fan; 11. Chimney; 12. Incineration fly ash disposal system; 13. Ammonia injection system; 14. Desulfurization ash circulation system; 15. Desulfurization ash resource utilization system; 16. Waste heat utilization device. Detailed Implementation

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0054] Example 1

[0055] A hazardous waste incineration system, such as Figure 1As shown, it includes a hazardous waste incinerator 1, a primary waste heat boiler 2, a high-temperature dust collector 3, a secondary waste heat boiler 4, a dry desulfurization system 5, a medium-high temperature dust removal-denitrification and dioxin removal device 6, an economizer 7, a GGH flue gas heat exchanger 8, a wet desulfurization system 9, an induced draft fan 10, and a chimney 11.

[0056] The hazardous waste incinerator 1 is connected in sequence via a flue to the primary waste heat boiler 2, the high-temperature dust collector 3, the secondary waste heat boiler 4, the medium-high temperature dust removal-denitrification and dioxin removal device 6, the economizer 7, and the GGH flue gas heat exchanger 8.

[0057] The dry acid removal system 5 is installed between the secondary waste heat boiler 4 and the medium-high temperature dust removal-denitrification and dioxin removal device 6 via a flue.

[0058] like Figure 2 As shown, the GGH flue gas heat exchanger 8 includes a flue gas inlet 8-1, a hot flue gas inlet 8-2, a cold flue gas inlet 8-3, and a flue gas outlet 8-4. The economizer 7 is connected to the flue gas inlet 8-1 of the GGH flue gas heat exchanger 8 through a flue. The hot flue gas inlet 8-2 of the GGH flue gas heat exchanger 8 is connected to the wet acid removal system 9 through a flue. The wet acid removal system 9 is connected back to the cold flue gas inlet 8-3 of the GGH flue gas heat exchanger 8 through a flue. The flue gas outlet 8-4 of the GGH flue gas heat exchanger 8 is connected to the induced draft fan 10 through a flue.

[0059] The induced draft fan 10 is connected to the chimney 11 via a flue.

[0060] like Figure 1 As shown, it also includes an incineration fly ash disposal system 12, wherein the hazardous waste incinerator 1, the primary waste heat boiler 2 and the high-temperature dust collector 3 are all connected to the incineration fly ash disposal system 12 by separate flues.

[0061] like Figure 1 As shown, it also includes an ammonia injection system 13, which is located between the primary waste heat boiler 2 and the high-temperature dust collector 3; or between the high-temperature dust collector 3 and the secondary waste heat boiler 4; or between the secondary waste heat boiler 4 and the medium-high temperature dust removal-denitrification and dioxin removal device 6.

[0062] like Figure 1 As shown, it also includes a deacidification ash circulation system 14 and a deacidification ash resource utilization system 15, both of which are connected to the medium-high temperature dust removal-denitrification and dioxin removal device 6. The deacidification ash circulation system 14 is connected back to the secondary waste heat boiler 4 and the medium-high temperature dust removal-denitrification and dioxin removal device 6 through a flue.

[0063] like Figure 1As shown, it also includes a waste heat utilization device 16. The economizer 7 is provided with a flue that is sequentially connected to the secondary waste heat boiler 4 and the primary waste heat boiler 2, and finally connected to the waste heat utilization device 16.

[0064] In a preferred embodiment, the high-temperature dust collector 3 can be a high-temperature ceramic dust collector, or other forms such as a high-temperature metal dust collector, as long as it meets the requirements of high temperature resistance, corrosion resistance, and high dust removal efficiency.

[0065] In a preferred embodiment, the medium-high temperature dust removal-denitrification and dioxin removal device 6 only needs to have denitrification, dioxin removal, and dust removal functions. It can be an integrated device or a separate design, such as a medium-high temperature dust removal device + an SCR denitrification and dioxin removal device. The filter element of the medium-high temperature dust removal-denitrification and dioxin removal device 6 can be made of ceramic or other materials such as metal.

[0066] In a preferred embodiment, the waste heat utilization system may employ waste heat boilers (primary waste heat boiler 2 and secondary waste heat boiler 4), or other devices capable of recovering heat.

[0067] Example 2

[0068] Waste incineration is performed using the hazardous waste incineration system described in Example 1, such as... Figure 1 As shown, the specific steps are as follows:

[0069] (1) After entering the hazardous waste (garbage) in the hazardous waste incineration system, it first enters the hazardous waste incinerator 1 for incineration. The hazardous waste incinerator 1 also includes a secondary combustion chamber, which provides an incineration temperature of >1100℃ and a flue gas residence time of 2s to reduce dioxin production.

[0070] (2) The high-temperature flue gas after incineration recovers its heat through the primary waste heat boiler 2 and is cooled to about 550°C before entering the high-temperature dust collector 3 (high-temperature ceramic dust collector). The high-temperature ceramic dust collector uses ceramic filter elements, which have the characteristics of high dust removal efficiency, temperature resistance and corrosion resistance. The dust removal efficiency is >99.9%, which can intercept and remove most of the dust in the flue gas.

[0071] (3) After dust removal, the flue gas enters the secondary waste heat boiler 4 for waste heat recovery again, while the flue gas temperature drops to 250-300℃. Since the regeneration of dioxins mainly depends on chlorine sources, carbon sources, heavy metal catalysts, etc. in the dust, the regeneration of dioxins is greatly suppressed during the cooling process after the dust is removed above 550℃. There is no need to set up quenching, and conventional waste heat boilers can be used to achieve cooling and energy recovery.

[0072] (4) Flue gas at 250-300℃ enters the medium-high temperature dust removal-denitrification and dioxin removal device 6, and deacidifying agents such as calcium hydroxide or sodium bicarbonate are sprayed into it through the dry deacidification system 5 to react with the acidic gases in the flue gas, reduce the concentration of acidic gases, and reduce the risk of corrosion. The medium-high temperature dust removal-denitrification and dioxin removal device 6 is also used as a reaction vessel for deacidification.

[0073] (5) The medium-high temperature dust removal-denitrification and dioxin removal device 6 is equipped with a catalytic ceramic filter element, on which a catalyst is covered. The filter element removes dust and collects the fly ash generated by the dry method, ensuring that the dust meets the standards. The catalyst simultaneously catalyzes the denitrification and dioxin removal, and its dioxin removal principle is complete decomposition, making the purification method the most thorough.

[0074] (6) After passing through the medium-high temperature dust removal-denitrification and dioxin removal device 6, the flue gas completes denitrification, dioxin removal, dust removal, and partial acid removal, and enters the economizer 7 to further recover the remaining energy, with the flue gas temperature dropping to about 200℃. At this time, due to the significant reduction in the content of pollutants in the flue gas, especially acidic gases and dust, the risk of corrosion and blockage of downstream equipment is greatly reduced.

[0075] (7) Flue gas at approximately 200°C passes through the GGH flue gas heat exchanger 8 and then enters the wet desulfurization system 9. The remaining acidic gases are removed and the flue gas is returned to the GGH flue gas heat exchanger 8. The GGH flue gas heat exchanger 8 exchanges heat between the high-temperature flue gas before wet desulfurization and the low-temperature flue gas after wet desulfurization. In the high-temperature section, the flue gas cools from 200°C to approximately 100°C before entering the wet desulfurization system 9. In the low-temperature section, the flue gas exiting the wet desulfurization system 9 at approximately 60°C is heated to approximately 160°C. The flue gas before and after wet desulfurization achieves non-contact heat exchange within the GGH flue gas heat exchanger 8, significantly improving the diffusion of flue gas emissions, reducing the ground-level concentration of flue gas pollutants, and reducing the corrosion of the induced draft fan 10, chimney 11, etc. by the flue gas.

[0076] (8) Finally, the flue gas that is returned to the GGH flue gas heat exchanger 8 through the wet desulfurization system 9 enters the induced draft fan 10 through the flue gas outlet 8-4. After the clean flue gas meets the standards, it is discharged into the atmosphere through the chimney 11 by the induced draft fan 10.

[0077] (9) The fly ash collected by the hazardous waste incinerator 1, the primary waste heat boiler 2, and the high-temperature dust collector 3 contains a large amount of heavy metals and other harmful substances, and is still classified as hazardous waste. It needs to be collected and treated in a unified manner. Therefore, the ash generated by the hazardous waste incinerator 1, the primary waste heat boiler 2, and the high-temperature dust collector 3 enters the incineration fly ash disposal system 12 for harmless treatment.

[0078] (10) Ammonia injection system 13 injects ammonia or urea into the flue gas as a reactant for SCR denitrification. The high-temperature flue gas heat evaporates to generate NH3, which reacts with NO under the action of a catalyst. xThe reaction produces harmless N2. The injection point of the ammonia injection system 13 can be selected at a suitable location (e.g., Figure 1 As shown, it can be installed between the primary waste heat boiler 2 and the high-temperature dust collector 3, or between the high-temperature dust collector 3 and the secondary waste heat boiler 4, or between the secondary waste heat boiler 4 and the medium-high temperature dust removal-denitrification and dioxin removal device 6. If sprayed before the high-temperature dust collector 3, it helps to suppress dioxin formation and makes the ammonia mixing more uniform. SCR denitrification has advantages such as high denitrification efficiency, low reactant consumption, and low ammonia slip. Catalytic denitrification can completely decompose dioxins, making it the most thorough dioxin emission reduction method.

[0079] (11) Since the original flue gas has undergone high-temperature dust removal, the dust content in the flue gas is extremely low. The fly ash collected by the medium-high temperature dust removal-denitrification and dioxin removal device 6 is mainly a by-product of acid removal. A portion of it can be recycled to the medium-high temperature dust removal-denitrification and dioxin removal device 6 through the acid removal ash recycling system 14 for further acid removal, thereby improving the acid removal efficiency and the utilization rate of the acid removal agent. The remaining by-products have relatively simple components and very low levels of harmful heavy metals and dioxins, which can be utilized through the acid removal ash resource utilization system 15.

[0080] (12) The primary waste heat boiler 2, the secondary waste heat boiler 4 and the economizer 7 recover the energy of the flue gas by heating steam with the waste heat of the flue gas and realize the waste heat utilization device 16.

[0081] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art to the technical solutions of the present invention without departing from the design concept of the present invention shall fall within the protection scope of the present invention.

Claims

1. A hazardous waste incineration system, characterized in that, Including hazardous waste incinerators, primary waste heat boilers, high-temperature dust collectors, secondary waste heat boilers, dry desulfurization systems, medium-high temperature dust removal-denitrification and dioxin removal devices, economizers, GGH flue gas heat exchangers, wet desulfurization systems, induced draft fans, and chimneys; The hazardous waste incinerator is connected in sequence via a flue to the primary waste heat boiler, the high-temperature dust collector, the secondary waste heat boiler, the medium-high temperature dust removal-denitrification and dioxin removal device, the economizer, and the GGH flue gas heat exchanger. The high-temperature dust collector has an inlet flue gas temperature of 550°C, which is used to remove fly ash and heavy metal catalysts in the high-temperature section; the secondary waste heat boiler has an outlet flue gas temperature of 250~300°C, which meets the medium-high temperature denitrification and dioxin removal reaction conditions. The dry acid removal system is installed between the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device via a flue. The GGH flue gas heat exchanger includes a flue gas inlet, a hot flue gas inlet, a cold flue gas inlet, and a flue gas outlet. The economizer is connected to the flue gas inlet of the GGH flue gas heat exchanger through a flue. The hot flue gas inlet of the GGH flue gas heat exchanger is connected to the wet acid removal system through a flue. The wet acid removal system is connected back to the cold flue gas inlet of the GGH flue gas heat exchanger through a flue. The flue gas outlet of the GGH flue gas heat exchanger is connected to the induced draft fan through a flue. The induced draft fan is connected to the chimney via a flue; It also includes an incineration fly ash disposal system, wherein the hazardous waste incinerator, the primary waste heat boiler and the high-temperature dust collector are all connected to the incineration fly ash disposal system by separate flues; It also includes an ammonia injection system, which is located between the primary waste heat boiler and the high-temperature dust collector; or between the high-temperature dust collector and the secondary waste heat boiler; or between the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device. It also includes a deacidification ash recycling system and a deacidification ash resource utilization system, both of which are connected to the medium-high temperature dust removal-denitrification and dioxin removal device. The deacidification ash recycling system is connected back to the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device through a flue. It also includes a waste heat utilization device, wherein the economizer is provided with a flue that is sequentially connected to the secondary waste heat boiler and the primary waste heat boiler, and finally connected to the waste heat utilization device; The medium-high temperature dust removal, denitrification, and dioxin removal device is an integrated unit.

2. The hazardous waste incineration system according to claim 1, characterized in that, The high-temperature dust collector is either a high-temperature ceramic dust collector or a high-temperature metal dust collector.

3. The hazardous waste incineration system according to claim 1, characterized in that, The filter element of the medium-high temperature dust removal-denitrification and dioxin removal device is made of ceramic or metal.

4. The operating process of a hazardous waste incineration system according to claim 1, characterized in that, Includes the following steps: Step 1) After the hazardous waste enters the hazardous waste incineration system, it first enters the hazardous waste incinerator for incineration. The hazardous waste incinerator also includes a secondary combustion chamber, which provides an incineration temperature of >1100℃ and a flue gas residence time of 2 s to reduce dioxin production. Step 2) The high-temperature flue gas after incineration is cooled to about 550°C by a primary waste heat boiler to recover its heat and then enters a high-temperature dust collector to intercept and remove most of the dust in the flue gas. Step 3) After dust removal, the flue gas enters the secondary waste heat boiler for waste heat recovery again, while the flue gas temperature drops to 250~300℃. Step 4) Flue gas at 250~300℃ enters the medium-high temperature dust removal-denitrification and dioxin removal device, and deacidifying agent is sprayed in through the dry deacidification system to react with the acidic gas in the flue gas, reduce the concentration of acidic gas, and reduce the risk of corrosion; the medium-high temperature dust removal-denitrification and dioxin removal device is also used as a reaction vessel for deacidification. Step 5) The medium-high temperature dust removal-denitrification and dioxin removal device is equipped with a filter element, and a catalyst is covered on the filter element; The filter cartridge collects the fly ash generated by the dry process, ensuring that the dust meets the standards; the catalyst simultaneously catalyzes the denitrification and dioxin removal, enabling the complete decomposition of dioxins. Step 6) After passing through the medium-high temperature dust removal-denitrification and dioxin removal device, the flue gas completes denitrification, dioxin removal, dust removal and partial acid removal, and enters the economizer to further recover the remaining energy, and the flue gas temperature drops to about 200℃; Step 7) The flue gas at around 200°C passes through the GGH flue gas heat exchanger and then enters the wet desulfurization system to remove the remaining acidic gases. The gas then flows back into the GGH flue gas heat exchanger, where it exchanges heat between the high-temperature flue gas before wet desulfurization and the low-temperature flue gas after wet desulfurization. In the high-temperature section, the flue gas cools down from 200°C to around 100°C before entering the wet desulfurization system. In the low-temperature section, the flue gas from the wet desulfurization system, which was around 60°C, is heated to around 160°C. The flue gas before and after wet desulfurization achieves non-contact heat exchange within the GGH flue gas heat exchanger. Step 8) Finally, the flue gas that is returned to the GGH flue gas heat exchanger through the wet desulfurization system enters the induced draft fan through the flue gas outlet. After the clean flue gas meets the standards, it is discharged into the atmosphere through the chimney by the induced draft fan.

5. The operating process of a hazardous waste incineration system according to claim 4, characterized in that, It also includes steps 9), 10), 11), and 12), as detailed below: Step 9) Ash generated by hazardous waste incinerators, primary waste heat boilers and high-temperature dust collectors is treated as hazardous waste and enters the incineration fly ash disposal system for harmless treatment. Step 10) The ammonia injection system injects the SCR denitrification reactant into the flue gas. The high-temperature flue gas heat evaporates the reactant to generate NH3, which then reacts with NO under the action of a catalyst. x The reaction produces harmless N2; the injection point of the ammonia injection system can be selected between the primary waste heat boiler and the high-temperature dust collector, between the high-temperature dust collector and the secondary waste heat boiler, or between the secondary waste heat boiler and the medium-high temperature dust removal-denitrification and dioxin removal device. Step 11) The medium-high temperature dust removal-denitrification and dioxin removal device circulates a portion of the collected deacidification fly ash through the deacidification ash recycling system to the medium-high temperature dust removal-denitrification and dioxin removal device for further deacidification, thereby improving deacidification efficiency and utilization rate of deacidification agent; the remaining portion is utilized through the deacidification ash resource utilization system. Step 12) The primary waste heat boiler, secondary waste heat boiler and economizer recover the energy of the flue gas by heating steam with the waste heat of the flue gas and realize the waste heat utilization device.

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