A device for treating municipal sludge based on oxygen-rich pyrolysis combustion

Abstract

This invention relates to the field of urban sludge treatment equipment technology, specifically an urban sludge treatment device based on oxygen-enriched pyrolysis combustion. The primary and secondary drying systems in this invention effectively remove moisture from the sludge, improving the efficiency of subsequent pyrolysis and combustion. The pyrolysis furnace converts the sludge into combustible pyrolysis gas, which is further combusted in a pyrolysis gas combustion furnace, reducing pollutant emissions. Cyclone separators and oxygen preheaters cool and pre-treat the flue gas, facilitating subsequent gas recovery. The CFB incinerator not only burns unburned sludge but also converts it into ash, which is then harmlessly treated through solid waste recovery equipment. Simultaneously, the high-temperature flue gas generated by the CFB incinerator is recycled into the primary drying system, achieving efficient energy utilization. The entire device is rationally designed, effectively decomposing urban sludge, reducing environmental pollution, and possessing high environmental and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of urban sludge treatment equipment technology, specifically an urban sludge treatment device based on oxygen-enriched pyrolysis combustion. Background Technology

[0002] Urban sludge treatment is an increasingly important environmental challenge in the process of urbanization. Faced with the rapid increase in sludge production, traditional treatment methods such as landfill and direct incineration are no longer sufficient to meet the requirements of efficiency and environmental protection. These traditional methods not only consume large amounts of land resources but may also cause serious secondary pollution problems, such as groundwater and air pollution, posing potential threats to the environment and human health.

[0003] To address this challenge, researchers are constantly exploring more advanced and efficient sludge treatment technologies. Among them, pyrolysis combustion technology, as a promising treatment method, has received widespread attention. This technology pyrolyzes sludge at high temperatures, converting it into combustible pyrolysis gas, which is then burned, achieving the harmlessness and volume reduction of the sludge. In this process, the organic matter in the sludge is effectively decomposed, reducing pollutant emissions, while the generated heat energy can be recovered and reused, improving resource utilization efficiency.

[0004] However, existing pyrolysis combustion technologies still face some challenges and shortcomings. First, the utilization efficiency of pyrolysis gas needs improvement. During pyrolysis, some pyrolysis gas may not be fully combusted, leading to heat loss and reduced combustion efficiency. Second, the treatment of flue gas generated during combustion is not thorough enough. The flue gas may contain unburned pollutants and harmful gases, such as sulfur dioxide and nitrogen oxides, requiring further improvement of flue gas purification technologies to ensure compliance with emission standards. Furthermore, the treatment of ash residue after sludge combustion is also an urgent problem to be solved. The ash residue may contain heavy metals and other harmful substances, requiring safe and environmentally friendly treatment methods to avoid secondary pollution. Summary of the Invention

[0005] To avoid and overcome the technical problems existing in the prior art, this invention provides an urban sludge treatment device based on oxygen-enriched pyrolysis combustion. This invention can effectively decompose urban sludge, reducing environmental pollution.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion includes a primary drying system for drying sludge raw materials, a secondary drying system installed at the discharge end of the primary drying system, a pyrolysis furnace installed at the sludge discharge end of the secondary drying system, a pyrolysis gas combustion furnace installed at the pyrolysis gas outlet end of the pyrolysis furnace, a cyclone separator installed at the outlet end of the pyrolysis gas combustion furnace, an oxygen preheater installed at the outlet end of the cyclone separator to cool the carbon dioxide-rich flue gas it generates, and a gas recovery device for treating the carbon dioxide-rich flue gas installed at the flue gas outlet end of the oxygen preheater; a CFB incinerator installed at the sludge discharge end of the pyrolysis furnace to burn unburned sludge into ash in the pyrolysis furnace, and a solid recovery device for recovering the ash at the ash discharge end of the CFB incinerator; the flue gas outlet end of the CFB incinerator is connected to the inlet end of the primary drying system to introduce the high-temperature flue gas generated when the CFB incinerator burns the sludge into the primary drying system.

[0008] As a further aspect of the present invention: when the pyrolysis gas combustion furnace burns the pyrolysis gas, it requires oxygen-containing air for combustion assistance. The theoretical value of the required oxygen-containing air quantity is V0, and the actual value of the oxygen-containing air quantity is V1. The formula for calculating the theoretical value of the oxygen-containing air quantity V0 is as follows:

[0009]

[0010] In the formula, ar represents the received base, i.e., the state of the pyrolysis gas upon receipt; C ar Indicates the carbon content in the pyrolysis gas; H ar S indicates the hydrogen content in the pyrolysis gas. ar Indicates the sulfur content in the pyrolysis gas; O ar This indicates the oxygen content in the pyrolysis gas;

[0011] The formula for calculating the actual oxygen content V1 is as follows:

[0012]

[0013] In the formula, x represents the excess oxygen coefficient used when pyrolysis gas is pyrolyzed in the pyrolysis gas combustion furnace; y represents the oxygen concentration of the air.

[0014] As a further aspect of the present invention: the total amount of carbon dioxide-rich flue gas generated by the cyclone separator is V2, and the carbon dioxide concentration in the carbon dioxide-rich flue gas is C.

[0015] The formula for calculating V2 is as follows:

[0016]

[0017] The formula for calculating C is as follows:

[0018]

[0019] In the formula, α represents the carbon conversion rate during pyrolysis; z represents the combined excess gas coefficient during pyrolysis of sludge in the pyrolysis furnace and during pyrolysis of pyrolysis gas in the pyrolysis gas combustion furnace; W ar This indicates the water content in the sludge raw material.

[0020] As a further aspect of the present invention: the amount of high-temperature flue gas generated by the CFB incinerator burning sludge is V3;

[0021] The formula for calculating V3 is as follows:

[0022]

[0023] In the formula, k represents the excess air coefficient in the CFB incinerator.

[0024] As a further embodiment of the present invention: the processing device further includes an air preheater, in which a cold air pipe and an oxygen-containing air pipe are provided, and a high-temperature flue gas pipe for the circulation of high-temperature flue gas is also provided in the air preheater, and the cold air pipe, the oxygen-containing air pipe and the high-temperature flue gas pipe in the air preheater are connected to each other by heat exchange fins for heat exchange.

[0025] The oxygen heat exchanger is also equipped with cold air pipes and oxygen-containing air pipes. At the same time, the oxygen heat exchanger is also equipped with carbon dioxide flue gas pipes for the flow of carbon dioxide-rich flue gas. The cold air pipes, oxygen-containing air pipes and carbon dioxide flue gas pipes in the oxygen heat exchanger are connected to each other for heat exchange through heat exchange fins.

[0026] The cold air pipe in the air preheater is connected to the cold air pipe in the oxygen preheater, and the outlet of the cold air pipe in the oxygen preheater is connected to the inlet of the CFB incinerator, so that the cold air exchanges heat with the high temperature flue gas and the carbon dioxide-rich flue gas and then enters the CFB incinerator.

[0027] The oxygen-containing air pipe in the air preheater is connected to the oxygen-containing air pipe in the oxygen preheater, and the outlet end of the oxygen-containing air pipe in the oxygen preheater is simultaneously connected to the inlet end of the pyrolysis furnace and the inlet end of the pyrolysis gas combustion furnace, so that the oxygen-containing air exchanges heat with the high-temperature flue gas and the carbon dioxide-rich flue gas and rises to the set temperature before entering the pyrolysis furnace and the pyrolysis gas combustion furnace.

[0028] As a further embodiment of the present invention: the gas recovery device includes a heat exchanger, in which a flue gas heat exchange tube and an air heating tube are installed, and the flue gas heat exchange tube and the air heating tube are connected to each other through heat exchange fins; cold air is introduced into the air heating tube, and the air outlet of the air heating tube is connected to the air inlet of the primary drying system; the air inlet of the flue gas heat exchange tube is connected to the air outlet of the carbon dioxide flue gas pipeline, and the air outlet of the flue gas heat exchange tube is connected to a capture system for capturing carbon dioxide in carbon dioxide-rich flue gas, the carbon dioxide outlet of the capture system is connected to the air inlet of the solid recovery device, and the remaining gas outlets of the capture system are connected to a gas purification device.

[0029] As a further aspect of the present invention: the air inlet of the oxygen-containing air pipe in the air preheater is connected to an air separation device that can separate cold air into nitrogen and oxygen-containing air.

[0030] As a further aspect of the present invention, the CFB incinerator is also equipped with a coal inlet pipe for adding pulverized coal into its furnace.

[0031] As a further aspect of the present invention, the flue gas outlet of the CFB incinerator is also connected to the air inlet of the solid waste recovery equipment.

[0032] As a further aspect of the present invention, the temperature of the high-temperature air, the temperature of the oxygen-containing air entering the pyrolysis furnace, and the temperature of the oxygen-containing air entering the pyrolysis gas combustion furnace are all above 600°C.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] 1. This invention achieves efficient treatment and resource recycling of municipal sludge through a multi-stage drying, pyrolysis, combustion, and recycling process. The primary and secondary drying systems effectively remove moisture from the sludge, improving the efficiency of subsequent pyrolysis and combustion. The pyrolysis furnace converts the sludge into combustible pyrolysis gas, which is further burned in a pyrolysis gas combustion furnace, reducing pollutant emissions. Cyclone separators and oxygen preheaters cool and pre-treat the flue gas, facilitating subsequent gas recovery. The CFB incinerator not only burns unburned sludge but also converts it into ash, which is then rendered harmless through solid waste recovery equipment. Simultaneously, the high-temperature flue gas generated by the CFB incinerator is recycled into the primary drying system, achieving efficient energy utilization. The entire device is rationally designed, effectively decomposing municipal sludge, reducing environmental pollution, and possessing high environmental and economic benefits.

[0035] 2. By precisely calculating the amount of oxygen-containing air required for the combustion of pyrolysis gas, precise control of the combustion process is achieved. The calculation of the theoretical and actual values ​​of the oxygen-containing air amount takes into account the content of various elements in the pyrolysis gas and the excess oxygen coefficient, ensuring the sufficiency and safety of the combustion process. This precise calculation method helps reduce oxygen waste and pollutant emissions during combustion, improving combustion efficiency and environmental performance.

[0036] 3. By calculating the total amount and concentration of carbon dioxide-rich flue gas generated by the cyclone separator, crucial data support was provided for subsequent flue gas treatment and carbon dioxide capture. The calculation formula considered factors such as the carbon conversion rate during pyrolysis and the overall excess gas coefficient, ensuring the accuracy and reliability of the data. This precise quantitative analysis helps optimize flue gas treatment processes, improve carbon dioxide capture efficiency, and reduce greenhouse gas emissions.

[0037] 4. By calculating the volume of high-temperature flue gas generated from the combustion of sludge in a CFB incinerator, a basis for heat recycling is provided. The calculation formula takes into account the excess air coefficient in the CFB incinerator, ensuring the accuracy and practicality of the calculation results. It also helps optimize the heat recovery process, improve energy efficiency, and reduce energy consumption and operating costs.

[0038] 5. The design of the air preheater and oxygen heat exchanger enables the preheating of both cold and oxygen-containing air. This preheating process not only increases the air temperature entering the pyrolysis furnace and pyrolysis gas combustion furnace but also fully utilizes the heat from the high-temperature flue gas and carbon dioxide-rich flue gas, achieving efficient energy utilization. Simultaneously, the preheating process helps reduce heat loss and pollutant emissions during combustion, improving the overall environmental performance of the unit.

[0039] 6. The gas recovery equipment design enables effective treatment and carbon dioxide capture of carbon dioxide-rich flue gas. The flue gas heat exchange tubes and air heating tubes in the heat exchanger are connected by heat exchange fins for efficient heat utilization. The capture system separates carbon dioxide from the flue gas and treats it harmlessly through solid waste recovery equipment, reducing greenhouse gas emissions. Simultaneously, the remaining gases are purified by gas purification equipment to ensure compliance with emission standards.

[0040] 7. Through the design of the air separation equipment, cold air is separated and processed to obtain oxygen-containing air and nitrogen. This separation process not only provides high-quality oxygen-containing air for the pyrolysis furnace and pyrolysis gas combustion furnace, but also enables the recovery and utilization of nitrogen, which helps to reduce oxygen consumption and nitrogen emissions, and improves the energy efficiency and environmental performance of the entire plant.

[0041] 8. By installing a coal inlet pipe on the CFB incinerator, the co-combustion of pulverized coal and sludge is achieved. This co-combustion not only improves combustion efficiency and calorific value but also reduces pollutant emissions during sludge combustion. Simultaneously, the addition of pulverized coal can regulate the furnace temperature and combustion stability of the CFB incinerator, improving the reliability and stability of the entire system.

[0042] 9. By connecting the flue gas outlet of the CFB incinerator to the inlet of the solid waste recovery equipment, unburned materials in the flue gas can be recovered and reused. This not only reduces the pollutant content in flue gas emissions but also improves the processing efficiency and resource utilization of the solid waste recovery equipment. Furthermore, this recovery method helps reduce operating costs and environmental risks.

[0043] 10. By ensuring that the temperatures of the high-temperature air, the oxygen-containing air entering the pyrolysis furnace, and the oxygen-containing air entering the pyrolysis gas combustion furnace are all greater than 600℃, optimized control of the combustion process is achieved. This high-temperature condition not only improves combustion efficiency and calorific value but also reduces pollutant emissions and heat loss during combustion. Simultaneously, this high-temperature condition also helps improve the reliability and stability of the entire device, extending its service life. Attached Figure Description

[0044] Figure 1 This is a flowchart of urban sludge treatment in an embodiment of the present invention.

[0045] In the diagram: 1. Primary drying system; 2. Secondary drying system; 3. Pyrolysis furnace; 4. Pyrolysis gas combustion furnace; 5. Cyclone separator; 6. Oxygen preheater; 7. Air preheater; 8. CFB incinerator; 9. Gas recovery equipment; 91. Heat exchanger; 92. Capture system; 93. Gas purification equipment; 10. Air separation equipment; 11. Solid recovery equipment. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Please see Figure 1In this embodiment of the invention, urban sludge with a solids content ≤60% is first obtained as sludge raw material. Then, the sludge raw material is fed into a primary drying system 1 for the first drying. After the first drying, the sludge is sent to a secondary drying system 2 for the second drying. The solids content of the sludge after the first drying is between 80% and 90%. A portion of the sludge after the second drying is sent to a pyrolysis furnace 3, and the other portion is sent to a CFB incinerator 8.

[0048] In pyrolysis furnace 3, sludge is decomposed into pyrolysis gas through pyrolysis. This pyrolysis gas then enters pyrolysis gas combustion furnace 4 for combustion, generating phosphorus-containing flue gas. The phosphorus-containing flue gas is then sent to cyclone separator 5 to produce carbon dioxide-rich flue gas. This carbon dioxide-rich flue gas is then sent to the carbon dioxide flue gas pipeline in oxygen preheater 6. After heat exchange, the temperature of the carbon dioxide-rich flue gas in the pipeline decreases, and it enters heat exchanger 91 in gas recovery equipment 9, flowing through the flue gas heat exchange tubes in heat exchanger 91. The carbon dioxide-rich flue gas in the heat exchange tubes is then subjected to dehydration and impurity removal to remove SO2 and NO. x After processes such as dust removal, the carbon dioxide-rich flue gas is sent to the capture system 92 for capture treatment such as PSA pressure swing adsorption, TSA temperature swing adsorption, membrane separation, or direct compression capture to obtain other mixed gases and pure carbon dioxide gas of the target concentration. Then, the pure carbon dioxide gas is sent to the solid recovery equipment 11 for green processing, that is, the captured exhaust gas and other mixed gases discharged from the capture system 92 and the exhaust gas from the drying system discharged from the drying system should all be post-treated by the gas purification equipment 93 to meet the corresponding standards before being discharged into the air.

[0049] Unburned sludge in pyrolysis furnace 3 and sludge directly entering CFB incinerator 8 are burned together in CFB incinerator 8, producing fly ash, slag, and high-temperature flue gas. The high-temperature flue gas enters the high-temperature flue gas duct of air preheater 7, where it undergoes heat exchange and cooling before mixing with outside cold air and entering primary drying system 1. After passing through primary drying system 1 and secondary drying system 2, the sludge is first fed into pyrolysis furnace 3. After pyrolysis, the unburned sludge is fed into CFB incinerator 8 for circulating fluidized bed combustion. The circulating fluidized bed uses high-temperature air for combustion until complete combustion. The circulating fluidized bed uses high-temperature air for combustion, not pure oxygen or oxygen-enriched gas. Its main purpose is to increase the flue gas volume to provide sufficient gas for the subsequent sludge drying process, and also to reduce the amount of cold air used for direct mixing, thereby reducing heat loss. Because the quality of sludge is affected by season, region, source and moisture content, and the calorific value fluctuates greatly, a coal feed pipe for pulverized coal supply is added to CFB incinerator 8. Pulverized coal is added to CFB incinerator 8 through the coal feed pipe to enhance the stability of combustion and increase the heat of flue gas during periods when the calorific value of sludge is low, so as to ensure the heat demand of downstream drying and other equipment.

[0050] The high-temperature flue gas discharged from the CFB incinerator 8 remains at a high temperature even after heat exchange in the air preheater 7, making it unsuitable for direct use in drying sludge. Therefore, it is directly mixed with cold outside air to lower its temperature to the required level for the drying system, and then fed into the primary drying system 1 to dry the sludge, thus achieving heat recycling. The cold air directly mixed with the high-temperature flue gas comes from both outside air and preheated air heated by air heating tubes in heat exchanger 91.

[0051] The carbon dioxide-rich flue gas discharged from the oxygen preheater 6, after exchanging heat with cold air, is also mixed into the high-temperature flue gas discharged from the air preheater 7, thus lowering the temperature of the carbon dioxide-rich flue gas and effectively utilizing its heat. The air preheater 7 is equipped with cold air ducts and oxygen-containing air ducts, as well as a high-temperature flue gas duct for the flow of high-temperature flue gas. These ducts are interconnected via heat exchange fins. Similarly, the oxygen heat exchanger 91 is equipped with cold air ducts and oxygen-containing air ducts, and also includes a carbon dioxide flue gas duct for the flow of carbon dioxide-rich flue gas. These ducts are also interconnected via heat exchange fins. The cold air pipe in air preheater 7 is connected to the cold air pipe in oxygen preheater 6, and the outlet of the cold air pipe in oxygen preheater 6 is connected to the inlet of CFB incinerator 8, so that the cold air exchanges heat with the high-temperature flue gas and carbon dioxide-rich flue gas to raise its temperature before entering CFB incinerator 8. The oxygen-containing air pipe in air preheater 7 is connected to the oxygen-containing air pipe in oxygen preheater 6, and the outlet of the oxygen-containing air pipe in oxygen preheater 6 is simultaneously connected to the inlet of pyrolysis furnace 3 and the inlet of pyrolysis gas combustion furnace 4, so that the oxygen-containing air exchanges heat with the high-temperature flue gas and carbon dioxide-rich flue gas and raises its temperature to a set temperature before entering pyrolysis furnace 3 and pyrolysis gas combustion furnace 4.

[0052] The air preheater 7 has an oxygen-containing air pipe inlet connected to an air separator 10 that separates cold air into nitrogen and oxygen-containing air. Outside cold air is input into the air separator 10 for separation into nitrogen and oxygen-containing air. The nitrogen is directly discharged into the air, while the oxygen-containing air is input into the air preheater 7. The separated oxygen-containing air is either pure oxygen or oxygen-enriched air. The high-temperature air used for combustion in the CFB incinerator 8, and the pure oxygen / oxygen-enriched air used for combustion in the pyrolysis furnace 3 and pyrolysis gas combustion furnace 4, are preheated in the oxygen preheater 6 and air preheater 7 to form high-temperature air above 600°C and high-temperature pure oxygen / oxygen-enriched air.

[0053] The sludge from the secondary drying system 2 is processed through pyrolysis furnace 3 to gas recovery equipment 9 via a path called the pure oxygen-enriched pyrolysis combustion sludge treatment path, which is a bypass of the CFB incinerator 8. This pure oxygen-enriched pyrolysis combustion sludge treatment path, as a source of high-concentration carbon dioxide flue gas, allows for control of flue gas volume and thus carbon dioxide capture by controlling the amount of sludge pyrolysis combustion treated in the bypass. The CFB incinerator 8, as the main sludge treatment path, can treat unburned sludge from the pure oxygen-enriched pyrolysis combustion path and directly treat sludge from the secondary drying system 2. The distribution ratio and amount of sludge from the secondary drying system 2 entering the CFB incinerator 8 and pyrolysis furnace 3 are determined according to the following principles:

[0054] 1. The amount of carbon dioxide captured subsequently.

[0055] 2. The heat provided by the drying system for drying sludge. This heat is used to capture flue gas. Due to the strict sealing involved, it cannot be mixed with other media; only gas heat exchange is used. This makes it impossible to effectively transfer the heat, so most of the heat generated in the pure oxygen-enriched pyrolysis combustion process for sludge treatment is wasted and discharged. In summary, most of the heat used for drying comes from the high-temperature flue gas of CFB incinerator 8.

[0056] In the process of pyrolysis of urban sludge, oxygen-containing air is required for combustion in the pyrolysis gas combustion furnace 4. The theoretical value of the required oxygen-containing air is V0, and the actual value of the required oxygen-containing air is V1. The formula for calculating the theoretical value of oxygen-containing air V0 is shown in formula (1):

[0057]

[0058] The formula for calculating the actual oxygen content V1 is shown in formula (2):

[0059]

[0060] The value of x ranges from [0.2, 0.5].

[0061] During the pyrolysis of urban sludge, the total amount of carbon dioxide-rich flue gas generated by cyclone separator 5 is V2, and the carbon dioxide concentration in the carbon dioxide-rich flue gas is C.

[0062] The formula for calculating V2 is shown in formula (3):

[0063]

[0064] Where α takes values ​​in the range [0.5, 0.7], and z takes values ​​in the range [1.05, 1.2].

[0065] The formula for calculating C is shown in formula (4):

[0066]

[0067] The volume of high-temperature flue gas generated by the combustion of sludge in CFB incinerator 8 is V3, and the formula for calculating V3 is shown in formula (5):

[0068]

[0069]

[0070] In this embodiment of the invention, the concentration and content of the corresponding gases were calculated during the treatment of dried sludge, and the results are shown in Table 1:

[0071] Table 1 shows the concentration and content of the corresponding gases.

[0072]

[0073] Taking a sludge treatment capacity of 300 tons / day for the entire system as an example, when air combustion is used, the theoretical value V0 of the oxygen-containing air supplied to the pyrolysis gas combustion furnace is 38322 Nm³. 3 / h. The present invention uses oxygen-enriched air as the pyrolysis carrier gas for gasifying sludge. Generally, the excess oxygen coefficient used in pyrolysis is x = 0.5, y = 0.8. The oxygen concentration of the oxygen-containing air produced from the oxygen generator is 80%, therefore the required gas flow rate V1 supplied to the pyrolysis gas combustion furnace is 5029 Nm³. 3 / h. Therefore, in the cyclone separator following the pyrolysis gas combustion furnace, the total amount of carbon dioxide-rich flue gas V2 when α = 0.7 and z = 1.1 is 12603 Nm³. 3 The carbon dioxide concentration in the flue gas is 34.12%, higher than that of conventional air combustion, which facilitates subsequent carbon capture and carbon dioxide resource utilization. Unburned carbon and ash from the pyrolysis furnace are fed into the CFB incinerator, where conventional air is typically introduced for combustion. Maintaining an excess air coefficient of k = 1.1, the resulting high-temperature flue gas volume V3 is 13880.13 Nm3 / h. The total volume of carbon dioxide-rich flue gas from the cyclone separator and the high-temperature flue gas from the CFB incinerator is 26483.27 Nm3 / h, and both simultaneously enter the gas preheater to heat pure oxygen / oxygen-enriched air and cold air.

[0074] The fly ash and slag produced by the CFB incinerator 8 from the incineration of sludge are hazardous waste and require harmless treatment through the solid waste recovery equipment 11. Fly ash and slag are high-quality raw materials for building materials. Coupled with carbon dioxide utilization methods, hazardous waste can be treated and utilized at high value, producing high-value products while manufacturing building materials, thus fully utilizing the sludge and turning waste into treasure. The treatment method mainly involves washing the fly ash and slag with water. The solid products from the water washing replace cement raw materials or admixtures. Simultaneously, carbon dioxide obtained from the capture system 92 is used to acidify the fly ash washing liquid to produce industrial salt and calcium carbonate. The heat used for evaporating and drying the water in the fly ash washing liquid is the high-temperature flue gas generated from sludge incineration. Cement products produced using fly ash and slag can be mineralized using carbon dioxide to achieve carbon dioxide fixation.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion, characterized in that, The system includes a primary drying system (1) for drying sludge raw materials, a secondary drying system (2) installed at the discharge end of the primary drying system (1), a pyrolysis furnace (3) installed at the sludge discharge end of the secondary drying system (2), a pyrolysis gas combustion furnace (4) installed at the pyrolysis gas outlet end of the pyrolysis furnace (3), a cyclone separator (5) installed at the outlet end of the pyrolysis gas combustion furnace (4), an oxygen preheater (6) installed at the outlet end of the cyclone separator (5) to cool the carbon dioxide-rich flue gas it generates, and a gas recovery device (9) installed at the flue gas outlet end of the oxygen preheater (6) to treat the carbon dioxide-rich flue gas. The sludge discharge end of the pyrolysis furnace (3) is equipped with a CFB incinerator (8) that burns the unburned sludge in the pyrolysis furnace (3) into ash. The CFB incinerator (8) is connected to the sludge discharge end of the secondary drying system (2). The ash discharge end of the CFB incinerator (8) is equipped with a solid recycling device (11) for recycling the ash. The flue gas outlet end of the CFB incinerator (8) is connected to an air preheater (7). The high-temperature flue gas pipe of the air preheater (7) is connected to the air inlet end of the primary drying system (1) to introduce the high-temperature flue gas generated when the CFB incinerator (8) burns the sludge into the primary drying system (1). The air preheater (7) has an air separation device (10) that can separate cold air into nitrogen and oxygen-containing air at the air inlet end. The air preheater (7) is equipped with a cold air pipe and an oxygen-containing air pipe, and the cold air pipe, oxygen-containing air pipe and high-temperature flue gas pipe in the air preheater (7) are connected to each other through heat exchange fins for heat exchange. The oxygen preheater (6) is also equipped with a cold air pipe and an oxygen-containing air pipe. At the same time, the oxygen preheater (6) is also equipped with a carbon dioxide flue gas pipe for the flow of carbon dioxide-rich flue gas. The cold air pipe, oxygen-containing air pipe and carbon dioxide flue gas pipe in the oxygen preheater (6) are connected to each other through heat exchange fins. The cold air pipe in the air preheater (7) is connected to the cold air pipe in the oxygen preheater (6), and the outlet of the cold air pipe in the oxygen preheater (6) is connected to the inlet of the CFB incinerator (8) so that the cold air exchanges heat with the high temperature flue gas and the carbon dioxide-rich flue gas and then enters the CFB incinerator (8). The oxygen-containing air pipe in the air preheater (7) is connected to the oxygen-containing air pipe in the oxygen preheater (6), and the outlet of the oxygen-containing air pipe in the oxygen preheater (6) is connected to the inlet of the pyrolysis furnace (3) and the inlet of the pyrolysis gas combustion furnace (4) so ​​that the oxygen-containing air exchanges heat with the high-temperature flue gas and the carbon dioxide-rich flue gas and rises to the set temperature before entering the pyrolysis furnace (3) and the pyrolysis gas combustion furnace (4).

2. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 1, characterized in that, The pyrolysis gas combustion furnace (4) requires oxygen-containing air for combustion support when burning pyrolysis gas. The theoretical amount of oxygen-containing air required is [value missing]. The actual oxygen content of the air is Theoretical value of oxygen-containing air The calculation formula is as follows: ； In the formula, This indicates the received base, i.e., the state of the pyrolysis gas upon receipt; This indicates the carbon content in the pyrolysis gas; This indicates the hydrogen content in the pyrolysis gas; This indicates the sulfur content in the pyrolysis gas; This indicates the oxygen content in the pyrolysis gas; Actual value of oxygen-containing air The calculation formula is as follows: ； In the formula, This indicates the excess oxygen coefficient used when the pyrolysis gas is pyrolyzed in the pyrolysis gas combustion furnace (4); This indicates the concentration of oxygen in the air.

3. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 2, characterized in that, The total amount of carbon dioxide-rich flue gas produced by the cyclone separator (5) is And the carbon dioxide concentration in the carbon dioxide-rich flue gas is ; The calculation formula is as follows: ； The calculation formula is as follows: ； In the formula, This indicates the carbon conversion rate during the pyrolysis process; The combined excess gas coefficient represents the combined excess gas coefficient of sludge during pyrolysis in the pyrolysis furnace (3) and the pyrolysis gas during pyrolysis in the pyrolysis gas combustion furnace (4); This indicates the water content in the sludge raw material.

4. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 3, characterized in that, The high-temperature flue gas generated by the CFB incinerator (8) burning sludge is: ; The calculation formula is as follows: ； In the formula, This represents the excess air coefficient in the CFB incinerator (8).

5. A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 4, characterized in that, The gas recovery device (9) includes a heat exchanger (91), in which a flue gas heat exchange tube and an air heating tube are installed, and the flue gas heat exchange tube and the air heating tube are connected to each other through heat exchange fins; cold air is introduced into the air heating tube, and the air outlet of the air heating tube is connected to the air inlet of the primary drying system (1); the air inlet of the flue gas heat exchange tube is connected to the air outlet of the carbon dioxide flue gas pipe, and the air outlet of the flue gas heat exchange tube is connected to a capture system (92) for capturing carbon dioxide in carbon dioxide-rich flue gas, the carbon dioxide outlet of the capture system (92) is connected to the air inlet of the solid recovery device (11), and the other gas outlets of the capture system (92) are connected to the gas purification device (93).

6. A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 5, characterized in that, The CFB incinerator (8) is also equipped with a coal inlet pipe for adding pulverized coal into its furnace.

7. A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 6, characterized in that, The flue gas outlet of the CFB incinerator (8) is also connected to the air inlet of the solid recycling device (11).

8. A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 7, characterized in that, The temperatures of the high-temperature air, the oxygen-containing air entering the pyrolysis furnace (3), and the oxygen-containing air entering the pyrolysis gas combustion furnace (4) are all above 600°C.

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