Cyclone separator, waste incineration system and method

Abstract

The present application relates to a cyclone separator, a waste incineration system and method, belonging to the technical field of waste incineration, a cyclone separator is arranged at the outlet of the first flue chamber of the waste heat boiler to separate dust in the flue gas at a flue gas temperature of 650-750 DEG C, the separated dust is transported to the grate burning-out section and enters the slag system after heat exchange with the air supply of the burning-out section, realizing source head reduction of fly ash and waste heat utilization of the ash; after dust separation, the flue gas at the outlet of the first flue chamber of the waste heat boiler is sequentially subjected to heat exchange, purification and dust removal, part of the dust-removed flue gas is discharged by the chimney, and part of the dust-removed flue gas is used as secondary air after heat exchange in the circulating flue gas air chamber of the cyclone separator and enters the secondary air pipeline leading to the outlet of the grate flue as secondary air, realizing low-nitrogen combustion of waste; normal-temperature air is sent into the tertiary air air chamber of the cyclone separator, the normal-temperature air is used as tertiary air after heat exchange in the tertiary air air chamber of the cyclone separator and enters the tertiary air pipeline leading to the first flue chamber of the waste heat boiler, solving the potential problem of CO exceeding the standard in the flue gas recirculation technology.

Description

Technical Field

[0001] This invention belongs to the field of waste incineration technology, and relates to cyclone separators, waste incineration systems and methods. Background Technology

[0002] Waste incineration has become the mainstream technology for municipal solid waste treatment in my country due to its advantages of high volume reduction, resource recovery, and harmlessness. Currently, waste incineration technology still faces two problems: First, the incineration process generates a large amount of fly ash, which is classified as hazardous waste (HW18) due to its high content of dioxins and heavy metals. Improper disposal can pose a threat to the environment and human health. With the vigorous promotion of waste incineration technology, the proper disposal of fly ash has become a bottleneck restricting the industry's development. Second, in recent years, with increasingly stringent environmental protection requirements, some regions in China have successively promulgated stricter local standards, especially the compliance of nitrogen oxide emissions in flue gas, which is an urgent issue to be addressed.

[0003] Regarding fly ash disposal technologies, the most common solutions in China are currently placing it in hazardous waste landfills or, after solidification / stabilization, in municipal solid waste landfills. In recent years, the amount of municipal solid waste produced has been increasing annually, leading to a rise in fly ash generation from incineration. However, the number and capacity of hazardous waste landfills are limited, and their operating costs are high, while the capacity of municipal solid waste landfills is becoming increasingly strained. Therefore, in addition to continuously developing post-generation treatment methods for fly ash, it is also necessary to consider reducing fly ash generation at the source of incineration to alleviate landfill pressure and improve the economic efficiency of enterprises.

[0004] Regarding NOx emission and control technologies, the current main method used for denitrification is SNCR technology, which can control the daily average NOx emission to 250 mg / m³. 3 Below, but unable to achieve lower emission targets (such as 150 mg / m³). 3 Even 120 mg / m 3 To achieve even lower emission standards, either SCR (Selective Catalytic Reduction) or flue gas recirculation (FGR) technology is required. However, SCR technology has a higher denitrification cost, exceeding 20 yuan per ton of waste, making it less widely applicable. FGR technology, on the other hand, has lower operating costs, better applicability, and the potential to become the mainstream denitrification technology under the current environmental protection requirements.

[0005] Based on the above analysis, reducing fly ash at its source and achieving low nitrogen emissions are pressing problems that the municipal solid waste incineration industry needs to address. Summary of the Invention

[0006] In view of this, the purpose of this application is to provide a cyclone separator, a waste incineration system and method to achieve source reduction of fly ash.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A cyclone separator includes a base, comprising an upper section and a lower section arranged vertically. The upper section has a central cavity and a circulating flue gas chamber surrounding the central cavity. A heat-resistant layer is provided between the central cavity and the circulating flue gas chamber. A flue gas inlet communicating with the central cavity is located on one side of the upper section, and a flue gas outlet communicating with the central cavity is located at the top of the upper section. The flue gas outlet is provided with a heat exchange layer to maintain a flue gas temperature of 650-750°C. A circulating flue gas outlet header and a circulating flue gas inlet header are respectively located at the upper and lower ends of the upper section. The circulating flue gas outlet header has an inlet and a circulating flue gas outlet header. The outlets of the flue gas inlet headers are all connected to the circulating flue gas chamber; the lower section has a lower section central chamber connected to the upper section central chamber and a tertiary air chamber arranged around the lower section central chamber. The upper section central chamber and the lower section central chamber form a connected chamber, and a heat-resistant layer is provided between the lower section central chamber and the tertiary air chamber; the upper end and the lower end of the lower section are respectively provided with a tertiary air outlet header and a tertiary air inlet header. The inlet of the tertiary air outlet header and the outlet of the tertiary air inlet header are both connected to the tertiary air chamber. The bottom of the lower section is provided with an ash outlet, and a discharge valve is provided at the ash outlet to discharge the ash in the connected chamber.

[0009] Optionally, the flue gas inlet is provided with a heat exchange layer, which is a water-cooled wall.

[0010] Optionally, the upper section is cylindrical and the lower section is inverted conical; the thickness of the heat-resistant layer between the central cavity of the upper section and the circulating flue gas chamber is greater than the thickness of the heat-resistant layer between the central cavity of the lower section and the tertiary air chamber, and it gradually thins from top to bottom.

[0011] A waste incineration system includes a grate, a waste heat boiler, a heat exchange device at the tail end of the waste heat boiler, a flue gas purifier, a dust collector, an induced draft fan, and a chimney arranged in sequence. The outlet of the first flue gas chamber of the waste heat boiler is equipped with a cyclone separator as described above to separate dust from the flue gas at a flue gas temperature of 650~750℃. The ash outlet of the cyclone separator is connected to the combustion section of the grate to transport the separated dust to the combustion section of the grate.

[0012] Optionally, a flue gas recirculation system is connected to the duct connecting the dust collector and the induced draft fan. The flue gas recirculation system includes a first circulating air branch and a second circulating air branch. The first circulating air branch is connected to the secondary air duct leading to the grate flue outlet so that the extracted low-temperature flue gas can be used directly as secondary air. The second circulating air branch sends the extracted low-temperature flue gas into the circulating flue gas inlet header of the cyclone separator. After heat exchange in the circulating flue gas chamber of the cyclone separator, the flue gas flows out through the circulating flue gas outlet header of the cyclone separator and is then sent into the secondary air duct leading to the grate flue outlet.

[0013] Optionally, the flue gas recirculation system also includes a high-temperature tertiary air branch to reduce CO emissions. The high-temperature tertiary air branch sends ambient temperature air into the tertiary air inlet header of the cyclone separator. After heat exchange in the tertiary air chamber of the cyclone separator, the air flows out through the tertiary air outlet header of the cyclone separator and is then sent into the tertiary air duct leading to the first flue gas chamber of the waste heat boiler to serve as tertiary air.

[0014] Optionally, both the first and second circulating air branches are equipped with electric valves; the flue gas recirculation system also includes a circulating fan, with the first and second circulating air branches connected to the outlet end of the circulating fan.

[0015] A waste incineration method separates dust from the flue gas at the outlet of the first flue gas chamber of a waste heat boiler at a flue gas temperature of 650~750℃ to reduce fly ash at the source, and transports the separated dust to the combustion section of the incinerator grate to exchange heat with the air supply in the combustion section, thereby realizing the utilization of the waste heat of the dust.

[0016] Optionally, dust in the flue gas at the outlet of the first flue gas chamber of the waste heat boiler is separated by a cyclone separator, and the cyclone separator is as described above. After dust separation, the flue gas at the outlet of the first flue gas chamber of the waste heat boiler undergoes heat exchange, purification, and dust removal in sequence. Part of the dust-removed flue gas is discharged through the chimney, part is used directly as secondary air, and part is sent to the circulating flue gas inlet header of the cyclone separator. After heat exchange in the circulating flue gas chamber of the cyclone separator, it flows out through the circulating flue gas outlet header of the cyclone separator and is then sent to the secondary air pipeline for use as secondary air.

[0017] Optionally, ambient temperature air is sent into the tertiary air inlet header of the cyclone separator. After heat exchange in the tertiary air chamber of the cyclone separator, the air flows out through the tertiary air outlet header of the cyclone separator and is then sent into the tertiary air pipeline leading to the first smoke chamber of the waste heat boiler to serve as tertiary air, thereby reducing CO emissions.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. The flue gas temperature at the outlet of the cyclone separator is 650~750℃, which ensures that the dioxin toxicity equivalent and heavy metal leaching concentration in the separated dust are lower than the hazardous waste standard limit, realizing the source reduction of fly ash from waste incineration, with a reduction effect of about 50~80%, significantly reducing the cost of chelation landfill for enterprises and saving landfill capacity;

[0020] 2. By setting up a cyclone separator for dust removal, the problem of ash accumulation and coking in the tail heat exchange device of the waste heat boiler in traditional technology is significantly reduced, the heat exchange efficiency of the tail heat exchange device of the waste heat boiler is improved, the frequency of boiler soot blowing is reduced, steam consumption is saved, the boiler efficiency is improved, and at the same time, the wear of the tail heat exchange device of the waste heat boiler is reduced, and the service life of the tail heat exchange device of the waste heat boiler is extended.

[0021] 3. Flue gas recirculation technology is used to replace the boiler's secondary air; simultaneously, tertiary air is added, where ambient temperature air is sent into the tertiary air chamber of a cyclone separator for heat exchange before being introduced into the tertiary air duct leading to the first flue gas chamber of the waste heat boiler. This technology reduces NOx emissions while solving the CO increase problem associated with flue gas recirculation technology, and also reduces exhaust losses and improves boiler efficiency.

[0022] 4. The cyclone separator adopts a heat exchange method with upper and lower sections arranged in a segmented manner, which do not affect each other. The inlet and outlet of the cyclone separator are equipped with heat exchange layers, and the circulating flue gas and high-temperature flue gas are used for heat exchange. It can replace the heat exchange surface of the second flue of the traditional type of waste heat boiler, and has a good heat exchange effect. The structure is simple and compact, and no new heat exchange device is required.

[0023] 5. The use of an air-cooled cyclone separator not only reduces the weight of the separator compared to an insulated separator, but also mitigates problems such as high-temperature coking in the separator.

[0024] 6. The thickness of the heat-resistant layer in the cyclone separator gradually decreases from top to bottom, which not only ensures the safety of the high-temperature zone, but also guarantees the heat transfer efficiency of the low-temperature zone;

[0025] 7. The ash and slag separated by the cyclone separator are discharged into the combustion section of the incinerator, where they directly exchange heat with the air supplied to the combustion section to recover and utilize the remaining heat, and are then discharged into the slag pit.

[0026] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0028] Figure 1 This is a schematic diagram of the present invention;

[0029] Figure 2 This is a schematic diagram of a cyclone separator.

[0030] Figure 3 for Figure 2 AA section view;

[0031] Figure 4 for Figure 2 BB cross-sectional view.

[0032] Attached reference numerals: 1. First smoke chamber; 2. Cyclone separator; 3. Circulating flue gas inlet header; 4. Circulating flue gas outlet header; 5. Tertiary air inlet header; 6. Tertiary air outlet header; 7. Feed valve; 8. Combustion section; 9. Waste heat boiler tail heat exchange device; 10. Heat-resistant layer; 11. Circulating flue gas chamber; 12. Tertiary air chamber; 13. Flue gas purifier; 14. Dust collector; 15. Water-cooled wall; 16. Electric valve; 17. Exhaust fan; 18. Smoke outlet; 19. Smoke inlet; 20. Circulating fan. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0034] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0035] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0036] Please see Figures 1-4A cyclone separator includes a base comprising an upper section and a lower section arranged vertically. The upper section has a central cavity and a circulating flue gas chamber 11 surrounding the central cavity. A heat-resistant layer 10 is provided between the central cavity and the circulating flue gas chamber 11. A flue gas inlet 19 communicating with the central cavity is provided on one side of the upper section. The flue gas inlet 19 is the inlet for dust-laden, high-temperature flue gas. A heat exchange layer is provided at the flue gas inlet 19 to exchange heat with the flue gas at the inlet 19, ensuring that the flue gas temperature at the inlet 19 does not exceed 750°C. The heat exchange layer can be a water-cooled wall 15. A flue gas outlet 18 communicating with the central cavity is provided at the top of the upper section. The flue gas outlet 18 is the outlet for the dust-removed flue gas. A heat exchange layer is provided at the outlet 18 to exchange heat with the flue gas at the outlet 18, ensuring that the flue gas temperature at the outlet 18 is 650~70°C. The upper section has a circulating flue gas outlet header 4 and a circulating flue gas inlet header 3 at its upper and lower ends, respectively. The inlet of the circulating flue gas outlet header 4 and the outlet of the circulating flue gas inlet header 3 are both connected to the circulating flue gas chamber 11. The lower section has a lower section central cavity connected to the central cavity of the upper section and a tertiary air chamber 12 arranged around the lower section central cavity. The upper section central cavity and the lower section central cavity form a connecting chamber. A heat-resistant layer 10 is provided between the lower section central cavity and the tertiary air chamber 12. The lower section has a tertiary air outlet header 6 and a tertiary air inlet header 5 at its upper and lower ends, respectively. The inlet of the tertiary air outlet header 6 and the outlet of the tertiary air inlet header 5 are both connected to the tertiary air chamber. The bottom of the lower section has an ash outlet, and a discharge valve 7 is provided at the ash outlet to discharge the ash in the connecting chamber. The heat-resistant layer and the air chamber arranged around it are used to maintain a stable working temperature, high separation efficiency, and equipment life in the connecting chamber. The circulating flue gas chamber 11 is used for indirect heat exchange between low-temperature circulating air and high-temperature flue gas, achieving heat exchange. The tertiary air chamber 12 is used for indirect heat exchange between low-temperature tertiary air and high-temperature flue gas, achieving heat exchange. The discharge valve 7 is used to periodically discharge ash and slag deposited at the bottom of the connecting chamber.

[0037] The cyclone separator of the present invention has a heat exchange function and adopts a heat exchange method with upper and lower sections, which can ensure that the heat exchange of the upper section and the heat exchange of the lower section do not affect each other. In addition, the inlet and outlet of the cyclone separator are equipped with heat exchange layers, which can achieve a good heat exchange effect and has a simple and compact structure.

[0038] The upper section of the present invention can be cylindrical, and the lower section can be inverted conical. The dust-laden flue gas rotates at high speed around the inner wall of the upper section, and the particles are separated from the airflow into the lower section by centrifugal force. The thickness of the heat-resistant layer between the central cavity of the upper section and the circulating flue gas chamber 11 is greater than the thickness of the heat-resistant layer between the central cavity of the lower section and the tertiary air chamber 12, and the heat-resistant layer gradually becomes thinner from top to bottom.

[0039] A waste incineration system includes a grate, a waste heat boiler, a waste heat boiler tail heat exchange device 9, a flue gas purifier 13, a dust collector 14, an induced draft fan 17, and a chimney, arranged sequentially. The outlet of the first flue gas chamber 1 of the waste heat boiler is equipped with a cyclone separator 2 as described above to separate dust (ash) from the flue gas at a flue gas temperature of 650-750°C. The ash outlet of the cyclone separator 2 is connected to the combustion section 8 of the grate to transport the separated dust to the combustion section 8 of the grate. The dust collector 14 is preferably a bag filter.

[0040] Cyclone separator 2 is connected to the flue gas outlet of the waste heat boiler. Under the action of cyclone separator 2, 95% of the dust is separated from the flue gas. The separated dust is transported to the combustion section of the incinerator. The combustion section supplies air to exchange heat with the high-temperature dust, realizing the utilization of waste heat of ash and slag. Finally, the separated dust enters the slag system, thereby achieving the reduction of fly ash at the source.

[0041] Fly ash is classified as hazardous waste due to its high content of dioxins and heavy metals. Studies have shown that dioxins are mainly generated at temperatures below 600°C through low-temperature heterogeneous catalytic reactions, while the dioxin content in flue gas dust is lower at temperatures above 600°C. Furthermore, most heavy metals, at temperatures above 600°C, are primarily enriched on the surface of dust particles smaller than 10 micrometers, or exist as aerosols and in gaseous form, flowing with the flue gas. Therefore, this invention employs a cyclone separation method. By ensuring the flue gas temperature at the cyclone separator outlet is 650~750°C, the dioxin toxicity equivalent and heavy metal leaching concentration in the separated dust are guaranteed to be below the hazardous waste standard limits.

[0042] Therefore, the flue gas temperature at the outlet of the cyclone separator 2 of the present invention is 650~750℃, which can ensure that the dioxin toxicity equivalent and heavy metal leaching concentration in the separated dust are lower than the hazardous waste standard limit, thereby achieving source reduction of fly ash from waste incineration, with a reduction effect of about 50~80%, significantly reducing the cost of chelation landfill for enterprises and saving landfill capacity.

[0043] To improve boiler efficiency and reduce flue gas losses, this invention also includes a flue gas recirculation system to replace part or all of the boiler's secondary air. Specifically, a flue gas recirculation system is connected to the pipe connecting the dust collector 14 and the induced draft fan 17. The flue gas recirculation system includes a first circulating air branch and a second circulating air branch. The first circulating air branch is connected to the secondary air duct leading to the grate flue outlet to directly use the extracted low-temperature flue gas as secondary air. The second circulating air branch sends the extracted low-temperature flue gas into the circulating flue gas inlet header 3 of the cyclone separator 2. After heat exchange in the circulating flue gas chamber 11 of the cyclone separator 2, the flue gas flows out through the circulating flue gas outlet header 4 of the cyclone separator 2 and is then sent into the secondary air duct leading to the grate flue outlet. The flue gas recirculation system preferably includes a circulating fan 20, which can be a variable frequency fan. The first and second circulating air branches are connected to the outlet end of the circulating fan 20. Electric valves 16 should be installed in the first and second circulating air branches to facilitate flue gas flow regulation.

[0044] The flue gas recirculation system of this invention also includes a high-temperature tertiary air branch to reduce CO emissions. This branch delivers ambient temperature air into the tertiary air inlet header 5 of the cyclone separator 2. After heat exchange within the tertiary air chamber 12 of the cyclone separator 2, the air flows out through the tertiary air outlet header 6 of the cyclone separator 2 and is then fed into the tertiary air duct leading to the first flue gas chamber 1 of the waste heat boiler. By setting up a high-temperature tertiary air branch, this invention reduces NOx emissions while solving the CO increase problem associated with flue gas recirculation technology. It also reduces exhaust losses and improves boiler efficiency.

[0045] Cyclone separator 2 features heat exchange functionality, with heat exchange layers at both its inlet and outlet. The upper section of the cyclone separator houses the circulating flue gas chamber 11 for secondary air heat exchange, while the lower section houses the tertiary air chamber 12 for tertiary air heat exchange. After heat exchange, the temperature of the high-temperature flue gas decreases from 750°C at the cyclone separator inlet to 650°C at the outlet. The dust particles sequentially exchange heat with the recirculated flue gas, tertiary air, and combustion zone air, ensuring that their temperature upon entering the slag is below 200°C. Therefore, most of the heat in the dust is recovered and utilized. The inner wall of the cyclone separator is lined with a heat-resistant layer, with its thickness gradually decreasing from top to bottom. This ensures both safety in the high-temperature zone and efficient heat transfer in the low-temperature zone.

[0046] A waste incineration method separates dust from the flue gas at the outlet of the first flue gas chamber 1 of the waste heat boiler at a flue gas temperature of 650~750℃ to reduce fly ash at the source, and transports the separated dust to the combustion section 8 of the incinerator grate to exchange heat with the air supply of the combustion section, thereby realizing the utilization of the waste heat of the dust.

[0047] Optionally, dust in the flue gas at the outlet of the first flue gas chamber 1 of the waste heat boiler is separated by a cyclone separator 2. The cyclone separator 2 is the one described above. After dust separation, the flue gas at the outlet of the first flue gas chamber 1 of the waste heat boiler undergoes heat exchange, purification, and dust removal in sequence. Part of the dust-removed flue gas is discharged through the chimney, part is used directly as secondary air, and part is sent to the circulating flue gas inlet header 3 of the cyclone separator 2, where it undergoes indirect heat exchange with high-temperature flue gas and dust in the circulating flue gas chamber 11 of the cyclone separator 2. Afterwards, the flue gas flows out through the circulating flue gas outlet header 4 of the cyclone separator 2 and is then sent into the secondary air pipeline for use as secondary air. Normal temperature air is sent into the tertiary air inlet header 5 of the cyclone separator 2. After exchanging heat with high temperature dust in the tertiary air chamber 12 of the cyclone separator 2, it flows out through the tertiary air outlet header 6 of the cyclone separator 2 and is then sent into the tertiary air pipeline leading to the first flue gas chamber 1 of the waste heat boiler to serve as tertiary air. This achieves segmented combustion, reduces NOx and CO emissions, and avoids the increase in CO emissions caused by flue gas recirculation.

[0048] Flue gas recirculation (FGR) technology involves extracting a portion of the low-oxygen-content tail flue gas and injecting it back into the incinerator for re-combustion or reuse. FGR redistributes and optimizes temperature and oxygen content within the incinerator and waste heat boiler, lowering temperature and oxygen content in high-temperature zones and increasing temperature and oxygen content in low-temperature zones, thereby suppressing NOx formation in the high-temperature zone of the waste incinerator. In the main combustion zone of the incinerator, where the temperature is high, injecting low-oxygen-content recirculated flue gas (150°C) to replace secondary air (air, 166°C) lowers the temperature and oxygen content in the high-temperature zone, inhibiting the combination of N2 and O2 in the main combustion zone and reducing NOx formation, but increasing CO content. In the waste heat boiler's first flue chamber, where the temperature is relatively lower than in the main combustion zone of the incinerator, tertiary air is added, injecting heat-exchanged air to increase oxygen content and enhance flue gas turbulence, ensuring complete combustion of unburned CO and reducing CO emissions, thus avoiding the increased CO emissions caused by FGR recirculation.

[0049] This invention connects a cyclone separator to the flue gas outlet of a waste heat boiler to separate dust from the flue gas at the outlet of the first flue gas chamber at a flue gas temperature of 650-750℃. This ensures that the dioxin toxicity equivalent and heavy metal leaching concentration in the separated dust are below the hazardous waste standard limits. The separated dust is transported to the combustion section of the incinerator grate to exchange heat with the high-temperature dust, thus utilizing the waste heat of the ash. Finally, the separated dust enters the slag system, thereby reducing fly ash at the source. The flue gas exiting the smoke chamber undergoes dust separation, followed by heat exchange, purification, and dust removal. Part of the dust-removed flue gas is discharged through the chimney, part is used directly as secondary air, and part is sent to a cyclone separator. After heat exchange in the circulating flue gas chamber of the cyclone separator, it is then sent back into the secondary air duct for use as secondary air, thus achieving flue gas recycling. Furthermore, by setting up a high-temperature tertiary air branch, the problem of increased CO emissions associated with flue gas recirculation technology is solved while reducing NOx emissions, reducing exhaust losses, and improving boiler efficiency. Therefore, this invention reduces the production of fly ash from waste incineration at the source, lowers the comprehensive disposal cost of fly ash, saves landfill capacity, and simultaneously achieves low-NOx emissions, reduces exhaust losses, and improves boiler thermal efficiency.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cyclone separator, characterized in that: The system includes a base, comprising an upper section and a lower section arranged vertically. The upper section has a central cavity and a circulating flue gas chamber (11) arranged around the central cavity. A heat-resistant layer (10) is provided between the central cavity and the circulating flue gas chamber (11). A flue gas inlet (19) communicating with the central cavity is provided on one side of the upper section. A flue gas outlet (18) communicating with the central cavity is provided at the top of the upper section. A heat exchange layer is provided at the flue gas outlet (18) to make the flue gas temperature at the outlet (18) 650~750℃. A circulating flue gas outlet header (4) and a circulating flue gas inlet header (3) are respectively provided at the upper and lower ends of the upper section. The inlet of the circulating flue gas outlet header (4) and the circulating flue gas inlet are respectively provided with a circulating flue gas outlet header (4) and a circulating flue gas inlet header (3). The outlets of the header (3) are all connected to the circulating flue gas chamber (11); the lower section has a lower section central cavity connected to the upper section central cavity and a tertiary air chamber (12) arranged around the lower section central cavity. The upper section central cavity and the lower section central cavity form a connecting chamber. A heat-resistant layer (10) is provided between the lower section central cavity and the tertiary air chamber (12); the upper end and the lower end of the lower section are respectively provided with a tertiary air outlet header (6) and a tertiary air inlet header (5). The inlet of the tertiary air outlet header (6) and the outlet of the tertiary air inlet header (5) are both connected to the tertiary air chamber (12). The bottom of the lower section is provided with an ash outlet. A discharge valve (7) is provided at the ash outlet to discharge the ash in the connecting chamber.

2. A cyclone separator according to claim 1, characterized in that: The flue gas inlet (19) is equipped with a heat exchange layer, which is a water-cooled wall.

3. A cyclone separator according to claim 1, characterized in that: The upper section is cylindrical and the lower section is inverted conical. The thickness of the heat-resistant layer between the central cavity of the upper section and the circulating flue gas chamber (11) is greater than the thickness of the heat-resistant layer between the central cavity of the lower section and the tertiary air chamber (12), and it gradually becomes thinner from top to bottom.

4. A waste incineration system, comprising a grate, a waste heat boiler, a waste heat boiler tail heat exchange device (9), a flue gas purifier (13), a dust collector (14), an induced draft fan (17), and a chimney arranged in sequence, characterized in that: The first flue outlet of the waste heat boiler is provided with a cyclone separator (2) as described in any one of claims 1 to 3 to separate dust from the flue gas at a flue gas temperature of 650 to 750°C. The ash outlet of the cyclone separator is connected to the combustion section (8) of the grate to transport the separated dust to the combustion section (8) of the grate.

5. A waste incineration system according to claim 4, characterized in that: A flue gas recirculation system is connected to the pipe connecting the dust collector (14) and the induced draft fan (17). The flue gas recirculation system includes a first circulating air branch and a second circulating air branch. The first circulating air branch is connected to the secondary air duct leading to the grate flue outlet so that the extracted low-temperature flue gas can be used directly as secondary air. The second circulating air branch sends the extracted low-temperature flue gas into the circulating flue gas inlet header (3) of the cyclone separator (2). After heat exchange in the circulating flue gas chamber (11) of the cyclone separator (2), the flue gas flows out through the circulating flue gas outlet header (4) of the cyclone separator (2) and is then sent into the secondary air duct leading to the grate flue outlet.

6. A waste incineration system according to claim 5, characterized in that: The flue gas recirculation system also includes a high-temperature tertiary air branch to reduce CO emissions. The high-temperature tertiary air branch sends ambient temperature air into the tertiary air inlet header (5) of the cyclone separator (2). After heat exchange in the tertiary air chamber (12) of the cyclone separator (2), the air flows out through the tertiary air outlet header (6) of the cyclone separator (2) and is then sent into the tertiary air pipeline leading to the first flue gas chamber of the waste heat boiler to serve as tertiary air.

7. A waste incineration system according to claim 5, characterized in that: Electric valves (16) are provided on both the first and second circulating air branches; the flue gas recirculation system also includes a circulating fan (20), and the first and second circulating air branches are connected to the outlet end of the circulating fan (20).

8. A method for waste incineration, characterized in that: At a flue gas temperature of 650~750℃, dust in the flue gas at the outlet of the first flue gas chamber of the waste heat boiler is separated to reduce fly ash at the source. The separated dust is then transported to the burnout section of the incinerator grate to exchange heat with the air supply of the burnout section, thereby realizing the utilization of the waste heat of the dust. The dust in the flue gas at the outlet of the first flue gas chamber of the waste heat boiler is separated by a cyclone separator (2). The cyclone separator (2) is a cyclone separator as described in any one of claims 1 to 3. After the flue gas at the outlet of the first flue gas chamber of the waste heat boiler is separated by dust, it is then subjected to heat exchange, purification and dust removal in sequence. Part of the flue gas after dust removal is discharged through the chimney, part is used directly as secondary air, and part is sent into the circulating flue gas inlet header (3) of the cyclone separator (2). After heat exchange in the circulating flue gas chamber (11) of the cyclone separator, it flows out through the circulating flue gas outlet header (4) of the cyclone separator (2) and is then sent into the secondary air pipeline for use as secondary air.

9. A waste incineration method according to claim 8, characterized in that: Normal temperature air is sent into the tertiary air inlet header (5) of the cyclone separator (2), and after heat exchange in the tertiary air chamber (12) of the cyclone separator (2), it flows out through the tertiary air outlet header (6) of the cyclone separator (2) and is then sent into the tertiary air pipeline leading to the first smoke chamber of the waste heat boiler to serve as tertiary air, so as to reduce CO emissions.

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