Municipal sludge treatment device based on oxygen-enriched pyrolysis combustion

Abstract

The invention relates to the technical field of municipal sludge treatment equipment, in particular to a municipal sludge treatment device based on oxygen-enriched pyrolysis combustion. The first-stage drying system and the second-stage drying system effectively remove moisture in the sludge, and the subsequent pyrolysis and combustion efficiency is improved. The sludge is converted into combustible pyrolysis gas by the pyrolyzing furnace, and the pyrolysis gas is further combusted by the pyrolysis gas combustion furnace, so that pollutant emission is reduced. And the cyclone separator and the oxygen preheater are used for cooling and pre-treating the flue gas, so that convenience is provided for subsequent gas recovery. The CFB incinerator not only combusts unburnt sludge, but also converts the unburnt sludge into ash residues, and harmless treatment is carried out through solid recovery equipment. Meanwhile, high-temperature flue gas generated by the CFB incinerator is recycled to be used in the first-stage drying system, and efficient utilization of energy is achieved. The whole device is reasonable in design, municipal sludge can be effectively decomposed, environmental pollution is reduced, and high environmental protection benefits and economic benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of urban sludge treatment equipment, in particular to an urban sludge treatment device based on oxygen-enriched pyrolysis combustion. Background Art

[0002] As an environmental challenge that cannot be ignored in the process of urbanization, the importance of urban sludge treatment is becoming increasingly prominent. Faced with the sharp increase in the amount of sludge generated, traditional treatment methods such as landfill and direct incineration can no longer meet the requirements of high efficiency and environmental protection. These traditional methods not only occupy a large amount of land resources, but may also cause serious secondary pollution problems, such as groundwater pollution and air pollution, posing a potential threat to the environment and human health.

[0003] In order to meet this challenge, researchers are constantly exploring more advanced and efficient sludge treatment technologies. Among them, pyrolysis combustion technology has received widespread attention as a potential treatment method. This technology uses high-temperature pyrolysis of sludge to convert it into combustible pyrolysis gas, and then burns the pyrolysis gas to achieve harmlessness and reduction of sludge. In this process, the organic matter in the sludge is effectively decomposed, reducing the emission of pollutants. At the same time, the heat energy generated can be recycled, improving resource utilization efficiency.

[0004] However, the existing pyrolysis combustion technology still faces some challenges and shortcomings. First, the utilization efficiency of pyrolysis gas needs to be improved. During the pyrolysis process, part of the pyrolysis gas may not be fully burned, resulting in heat energy loss and reduced combustion efficiency. Secondly, the flue gas generated during the combustion process is not treated thoroughly enough. The flue gas may contain incompletely burned pollutants and harmful gases, such as sulfur dioxide and nitrogen oxides, and the flue gas purification technology needs to be further improved to ensure that emissions meet the standards. In addition, the treatment of ash after sludge combustion is also an urgent problem to be solved. The ash may contain heavy metals and other harmful substances, and safe and environmentally friendly treatment methods need to be adopted to avoid secondary pollution to the environment. Summary of the invention

[0005] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a municipal sludge treatment device based on oxygen-enriched pyrolysis combustion. The present invention can decompose municipal sludge more effectively and reduce environmental pollution.

[0006] To achieve the above object, the present invention provides the following technical solutions:

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

[0008] As a further solution of the present invention: when the pyrolysis gas combustion furnace burns the pyrolysis gas, oxygen-containing air is required for combustion support. The theoretical value of the amount of oxygen-containing air required is V0, and the actual value of the amount of oxygen-containing air is V1. The calculation formula of the theoretical value of the amount of oxygen-containing air V0 is as follows:

[0009]

[0010] In the formula, ar represents the received basis, that is, the state of the pyrolysis gas when it is received; C ar Indicates the carbon content in pyrolysis gas; H ar Indicates the content of hydrogen in pyrolysis gas; S ar Indicates the sulfur content in pyrolysis gas; O ar Indicates the content of oxygen in pyrolysis gas;

[0011] The calculation formula of the actual value V1 of the oxygen-containing air is as follows:

[0012]

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

[0014] As a further solution 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 calculation formula of V2 is as follows:

[0016]

[0017] The calculation formula of C is as follows:

[0018]

[0019] Wherein, α represents the carbon conversion rate during the pyrolysis process; z represents the comprehensive excess gas coefficient when the sludge is pyrolyzed in the pyrolysis furnace and the pyrolysis gas is pyrolyzed in the pyrolysis gas combustion furnace; W ar Indicates the water content in the sludge raw material.

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

[0021] The calculation formula of V3 is as follows:

[0022]

[0023] Where k represents the excess air coefficient in the CFB incinerator.

[0024] As a further solution of the present invention: the processing device also includes an air preheater, in which a cold air duct and an oxygen-containing air duct are provided, and a high-temperature flue gas duct for circulating the high-temperature flue gas is also provided in the air preheater, and the cold air duct, the oxygen-containing air duct and the high-temperature flue gas duct in the air preheater are heat exchange-connected with each other through heat exchange fins;

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

[0026] The cold air duct in the air preheater is connected to the cold air duct in the oxygen preheater, and the air outlet end of the cold air duct in the oxygen preheater is connected to the air inlet end of the CFB incinerator, so that the cold air enters the CFB incinerator after heat exchange with the high-temperature flue gas and the carbon dioxide-rich flue gas and the temperature is increased;

[0027] The oxygen-containing air pipeline in the air preheater is connected to the oxygen-containing air pipeline in the oxygen preheater, and the air outlet end of the oxygen-containing air pipeline in the oxygen preheater is connected to the air inlet end of the pyrolysis furnace and the air inlet end of the pyrolysis gas combustion furnace at the same time, so that the oxygen-containing air can exchange heat with the high-temperature flue gas and the carbon dioxide-rich flue gas and enter the pyrolysis furnace and the pyrolysis gas combustion furnace after rising to the set temperature.

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

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

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

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

[0032] As a further solution 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 present invention has the following beneficial effects:

[0034] 1. The present invention realizes efficient treatment and resource recycling of urban sludge through multi-stage drying, pyrolysis, combustion and recycling treatment processes. The primary drying system and the secondary drying system effectively remove moisture from the sludge and improve the efficiency of subsequent pyrolysis and combustion. The pyrolysis furnace converts the sludge into combustible pyrolysis gas, and the pyrolysis gas combustion furnace further burns the pyrolysis gas, reducing pollutant emissions. The cyclone separator and oxygen preheater cool and pretreat the flue gas, providing convenience for subsequent gas recovery. The CFB incinerator not only burns the unburned sludge, but also converts it into ash and treats it harmlessly through solid recovery equipment. At the same time, the high-temperature flue gas generated by the CFB incinerator is recycled in the primary drying system, realizing efficient energy utilization. The entire device is reasonably designed, can effectively decompose urban sludge, reduce environmental pollution, and has high environmental and economic benefits.

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

[0036] 3. By calculating the total amount of CO2-rich flue gas and CO2 concentration generated by the cyclone separator, it provides important data support for subsequent flue gas treatment and CO2 capture. The calculation formula takes into account factors such as carbon conversion rate and comprehensive excess gas coefficient during pyrolysis, ensuring the accuracy and reliability of the data. This precise quantitative analysis helps to optimize the flue gas treatment process, improve CO2 capture efficiency, and reduce greenhouse gas emissions.

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

[0038] 5. Through the design of air preheater and oxygen heat exchanger, the preheating treatment of cold air and oxygen-containing air is realized. This preheating treatment not only increases the air temperature entering the pyrolysis furnace and pyrolysis gas combustion furnace, but also makes full use of the heat of high-temperature flue gas and carbon dioxide-rich flue gas, realizing efficient energy utilization. At the same time, the preheating treatment also helps to reduce heat loss and pollutant emissions during the combustion process, and improves the environmental performance of the entire device.

[0039] 6. Through the design of gas recovery equipment, effective treatment of CO2-rich flue gas and CO2 capture are achieved. The flue gas heat exchange tubes and air heating tubes in the heat exchanger are connected to each other through heat transfer fins, achieving efficient use of heat. The capture system separates CO2 from the flue gas and treats it harmlessly through solid recovery equipment, reducing greenhouse gas emissions. At the same time, the remaining gas is purified by gas purification equipment to ensure that the emission meets the standards.

[0040] 7. Through the design of air separation equipment, the 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 realizes the recycling of nitrogen, which helps to reduce oxygen consumption and nitrogen emissions, and improves the energy efficiency and environmental performance of the entire device.

[0041] 8. By installing a coal inlet pipe on the CFB incinerator, the mixed combustion of coal powder and sludge is achieved. This mixed combustion not only improves the combustion efficiency and calorific value, but also reduces the pollutant emissions during the sludge combustion process. At the same time, the addition of coal powder can also adjust the furnace temperature and combustion stability of the CFB incinerator, improving the reliability and stability of the entire device.

[0042] 9. By connecting the flue gas outlet of the CFB incinerator with the air inlet of the solid recovery equipment, the unburned substances in the flue gas can be recycled, which not only reduces the pollutant content in the flue gas emissions, but also improves the processing efficiency and resource utilization of the solid recovery equipment. At the same time, this recycling method also helps to reduce operating costs and environmental risks.

[0043] 10. By ensuring that the temperature of the high-temperature air, the oxygen-containing air entering the pyrolysis furnace, and the oxygen-containing air entering the pyrolysis gas combustion furnace is greater than 600°C, the combustion process is optimized. This high temperature condition not only improves the combustion efficiency and calorific value, but also reduces pollutant emissions and heat loss during the combustion process. At the same time, this high temperature condition also helps to improve the reliability and stability of the entire device and extend the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0045] In the figure: 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 DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] See also Figure 1In the embodiment of the present invention, firstly, municipal sludge with a solid content of ≤60% is obtained as a sludge raw material, and then the sludge raw material is input into the primary drying system 1 for the first drying. After the first drying is completed, the sludge is sent to the secondary drying system 2 for the second drying. The solid content of the sludge after the first drying is between 80% and 90%. A part of the sludge after the second drying is sent to the pyrolysis furnace 3, and the other part is sent to the CFB incinerator 8.

[0048] The sludge in the pyrolysis furnace 3 is decomposed into pyrolysis gas through pyrolysis, and the pyrolysis gas enters the pyrolysis gas combustion furnace 4 for combustion to generate phosphorus-containing flue gas. Then the phosphorus-containing flue gas is sent to the cyclone separator 5 to produce carbon dioxide-rich flue gas. The carbon dioxide-rich flue gas is sent to the carbon dioxide flue gas pipeline in the oxygen preheater 6. The temperature of the carbon dioxide-rich flue gas in the carbon dioxide flue gas pipeline is reduced after heat exchange, and it enters the heat exchanger 91 in the gas recovery equipment 9 and flows in the flue gas heat exchange pipe in the heat exchanger 91. Then the carbon dioxide-rich flue gas in the flue gas heat exchange pipe is dehydrated and impurities are removed to remove SO2 and NO x The carbon dioxide-rich flue gas is then 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 target concentration. The pure carbon dioxide gas is then sent to the solid recovery equipment 11 for green processing, that is, the captured exhaust air and other mixed gases discharged from the capture system 92 and the exhaust gas of the drying system discharged from the drying system should all be post-processed by the gas purification equipment 93 and discharged into the air after meeting the corresponding standards.

[0049] The unburned sludge in the pyrolysis furnace 3 and the sludge directly entering the CFB incinerator 8 are burned in the CFB incinerator 8 together, and fly ash, ash and high-temperature flue gas are generated. The high-temperature flue gas enters the high-temperature flue gas duct in the air preheater 7, and after heat exchange and cooling in the high-temperature flue gas duct, it is mixed with the cold air from the outside and enters the primary drying system 1. The sludge is first sent to the pyrolysis furnace 3 after the primary drying system 1 and the secondary drying system 2. After pyrolysis, the unburned sludge is sent to the CFB incinerator 8, where circulating fluidized bed incineration is carried out. The circulating fluidized bed uses high-temperature air for combustion, not pure oxygen or oxygen-rich gas. Its main purpose is to increase the flue gas volume to provide sufficient gas volume for the subsequent sludge drying process, and also to reduce the amount of cold air used for direct mixing, thereby reducing heat loss. Since the quality of sludge is affected by season, region, source and moisture content, and the calorific value fluctuates greatly, a coal inlet pipe for supplying coal powder is added to the CFB incinerator 8. Coal powder is added to the CFB incinerator 8 through the coal inlet pipe. When the calorific value of the sludge is low, the coal powder can be used to enhance the stability of combustion, increase the heat of flue gas, and ensure the heat requirements of downstream drying and other equipment.

[0050] The high-temperature flue gas discharged from the CFB incinerator 8 is still at a high temperature after being cooled by heat exchange in the air preheater 7, which is not conducive to being directly used for drying sludge. Therefore, it is directly mixed with the cold air from the outside to reduce its temperature to the temperature required by the drying system, and then input into the primary drying system 1 to dry the sludge, realizing the recycling of heat. The cold air directly mixed with the high-temperature flue gas comes directly from the outside air on the one hand, and from the preheated air heated by the air heating pipe in the heat exchanger 91 on the other hand.

[0051] The carbon dioxide-rich flue gas discharged from the oxygen preheater 6 is also mixed into the high-temperature flue gas discharged from the air preheater 7 after heat exchange with the cold air, thereby reducing the temperature of the carbon dioxide-rich flue gas and effectively utilizing the heat therein. The air preheater 7 is provided with a cold air duct and an oxygen-containing air duct, and a high-temperature flue gas duct for the circulation of the high-temperature flue gas is also provided in the air preheater 7, and the cold air duct, the oxygen-containing air duct and the high-temperature flue gas duct in the air preheater 7 are connected to each other by heat exchange through heat exchange fins. The oxygen heat exchanger 91 is also provided with a cold air duct and an oxygen-containing air duct, and a carbon dioxide flue gas duct for the circulation of the carbon dioxide-rich flue gas is also provided in the oxygen heat exchanger 91, and the cold air duct, the oxygen-containing air duct and the carbon dioxide flue gas duct in the oxygen heat exchanger 91 are connected to each other by heat exchange through heat exchange fins. The cold air duct in the air preheater 7 is connected to the cold air duct in the oxygen preheater 6, and the outlet end of the cold air duct in the oxygen preheater 6 is connected to the air inlet end of the CFB incinerator 8, so that the cold air is heated up by heat exchange with the high-temperature flue gas and the carbon dioxide-rich flue gas and then enters the CFB incinerator 8. The oxygen-containing air duct in the air preheater 7 is connected to the oxygen-containing air duct in the oxygen preheater 6, and the outlet end of the oxygen-containing air duct in the oxygen preheater 6 is connected to the air inlet end of the pyrolysis furnace 3 and the air inlet end of the pyrolysis gas combustion furnace 4, so that the oxygen-containing air is heated up to the set temperature and then enters the pyrolysis furnace 3 and the pyrolysis gas combustion furnace 4.

[0052] The air inlet end of the oxygen-containing air pipeline in the air preheater 7 is connected to an air separation device 10 that can separate cold air into nitrogen and oxygen-containing air. The cold air from the outside is input into the air separation device 10 for separation into nitrogen and oxygen-containing air. The nitrogen is directly discharged into the air, and the oxygen-containing air is input into the air preheater 7. The separated oxygen-containing air is pure oxygen or oxygen-enriched air. The high-temperature air used for combustion support in the CFB incinerator 8, and the pure oxygen / oxygen-enriched air used for combustion support in the pyrolysis furnace 3 and the pyrolysis gas combustion furnace 4 are all preheated in the oxygen preheater 6 and the air preheater 7 to form high-temperature air above 600°C and high-temperature pure oxygen / oxygen-enriched air.

[0053] The treatment path of the sludge coming out of the secondary drying system 2 from the pyrolysis furnace 3 to the gas recovery equipment 9 is called the pure oxygen-enriched pyrolysis and combustion treatment sludge path, which is a bypass of the CFB incinerator 8. The pure oxygen-enriched pyrolysis and combustion treatment sludge path, as the source of high-concentration carbon dioxide flue gas, can control the amount of flue gas by controlling the amount of sludge pyrolysis and combustion treatment in the bypass, thereby controlling the amount of captured carbon dioxide. As the main path for disposing sludge, the CFB incinerator 8 can, on the one hand, dispose of the unburned sludge in the pure oxygen-enriched pyrolysis and combustion treatment path, and on the other hand, can directly dispose of the sludge coming out of the secondary drying system 2. The distribution ratio and distribution amount of the sludge coming out of the secondary drying system 2 entering the CFB incinerator 8 and the pyrolysis furnace 3 are determined according to the following principles:

[0054] 1. The amount of subsequent CO2 capture.

[0055] 2. Heat provided for drying sludge in the drying system. It is used to capture flue gas. Due to strict sealing, it cannot be mixed with other media. Only gas heat exchange is used, and the heat in it cannot be effectively exchanged out. Therefore, most of the heat produced in the pure oxygen-enriched oxygen pyrolysis combustion treatment sludge path is wasted and emptied. In summary, most of the heat used for drying comes from the high-temperature flue gas of the CFB incinerator 8.

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

[0057]

[0058] The calculation formula of the actual value V1 of the oxygen-containing air volume is shown in formula (2):

[0059]

[0060] The value range of x is [0.2, 0.5].

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

[0062] The calculation formula of V2 is shown in formula (3):

[0063]

[0064] Among them, the value range of α is [0.5, 0.7], and the value range of z is [1.05, 1.2].

[0065] The calculation formula of C is shown in formula (4):

[0066]

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

[0068]

[0069]

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

[0071] Table 1 Corresponding gas concentration and content

[0072]

[0073] Taking the whole system with a sludge treatment capacity of 300 tons / day as an example, when air combustion is adopted, the theoretical value of oxygen-containing air volume V0 supplied to the pyrolysis gas combustion furnace is 38322Nm 3 / h. The solution of the present invention is to use 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, and the oxygen concentration of the oxygen-containing air produced from the oxygen production device is 80%. The gas volume V1 required to be supplied to the pyrolysis gas combustion furnace is 5029Nm 3 / h. Then 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 12603Nm 3 / h, where the carbon dioxide concentration is 34.12%, which is higher than the carbon dioxide concentration of conventional air combustion, which is convenient for subsequent carbon capture and carbon dioxide resource utilization. The unburned residual carbon and ash sent to the pyrolysis furnace are sent to the CFB incinerator, and conventional air is generally introduced for combustion. When the excess air coefficient is maintained at k = 1.1, the amount of high-temperature flue gas V3 generated is 13880.13Nm3 / h. The total amount of carbon dioxide-rich flue gas discharged from the cyclone separator and the high-temperature flue gas discharged from the CFB incinerator is 26483.27Nm3 / h, and both enter the gas preheater simultaneously to heat pure oxygen / oxygen-enriched air and cold air.

[0074] The fly ash and ash residue generated by the incineration of sludge in the CFB incinerator 8 are hazardous wastes and need to be harmlessly disposed of by the solid recovery equipment 11. Fly ash and ash residue are high-quality raw materials for building materials. The coupling of the carbon dioxide utilization method can dispose of and utilize hazardous wastes in a high-value manner. While making building materials, it can also produce high-value products, and can "squeeze out" the sludge and turn waste into treasure. The disposal method mainly involves washing the fly ash and ash residue with water, and the solid phase products of the washing replace cement raw materials or mixed materials. At the same time, the carbon dioxide obtained by the capture system 92 is used to acidify the fly ash washing liquid to produce industrial salt and calcium carbonate. Among them, the heat used for evaporation and drying of water in the fly ash washing liquid utilizes the high-temperature flue gas generated by sludge incineration. Cement products produced using fly ash and ash residue can use carbon dioxide for concrete mineralization to achieve carbon dioxide fixation.

[0075] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion, characterized in that: The invention comprises a primary drying system (1) for drying sludge raw materials, a secondary drying system (2) being installed at the discharge end of the primary drying system (1), a pyrolysis furnace (3) being installed at the sludge discharge end of the secondary drying system (2), a pyrolysis gas combustion furnace (4) being installed at the pyrolysis gas outlet end of the pyrolysis furnace (3), a cyclone separator (5) being installed at the outlet end of the pyrolysis gas combustion furnace (4), an oxygen preheater (6) being installed at the outlet end of the cyclone separator (5) for cooling the carbon dioxide-rich flue gas generated by the cyclone separator (5), and a flue gas outlet of the oxygen preheater (6) being installed at the outlet end of the cyclone separator (5). A gas recovery device (9) for treating carbon dioxide-rich flue gas is installed at the gas end; a CFB incinerator (8) for burning unburned sludge in the pyrolysis furnace (3) into ash is installed at the sludge discharge end of the pyrolysis furnace (3); a solid recovery device (11) for recovering the ash is installed at the ash discharge end of the CFB incinerator (8); the flue gas outlet end of the CFB incinerator (8) is connected to the air inlet end of the primary drying system (1) so as to introduce high-temperature flue gas generated when the CFB incinerator (8) burns sludge into the primary drying system (1).

2. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 1 is characterized in that: When the pyrolysis gas combustion furnace (4) burns the pyrolysis gas, oxygen-containing air is required for combustion support. The theoretical value of the amount of oxygen-containing air required is V0, and the actual value of the amount of oxygen-containing air is V1. The calculation formula of the theoretical value of the amount of oxygen-containing air V0 is as follows: In the formula, ar represents the received basis, that is, the state of the pyrolysis gas when it is received; C ar Indicates the carbon content in pyrolysis gas; H ar Indicates the content of hydrogen in pyrolysis gas; S ar Indicates the sulfur content in pyrolysis gas; O ar Indicates the content of oxygen in pyrolysis gas; The calculation formula of the actual value V1 of the oxygen-containing air is as follows: In the formula, x represents the excess oxygen coefficient used when the pyrolysis gas is pyrolyzed in the pyrolysis gas combustion furnace (4); y represents the concentration of oxygen-containing air.

3. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 2 is characterized in that: The total amount of carbon dioxide-rich flue gas generated by the cyclone separator (5) is V2, and the carbon dioxide concentration in the carbon dioxide-rich flue gas is C; The calculation formula of V2 is as follows: The calculation formula of C is as follows: Wherein, α represents the carbon conversion rate during the pyrolysis process; z represents the comprehensive excess gas coefficient when the sludge is pyrolyzed in the pyrolysis furnace (3) and the pyrolysis gas is pyrolyzed in the pyrolysis gas combustion furnace (4); W ar 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 is characterized in that: The amount of high-temperature flue gas generated by the combustion of sludge in the CFB incinerator (8) is V3; The calculation formula of V3 is as follows: Wherein, k represents the excess air coefficient in the CFB incinerator (8).

5. A municipal sludge treatment device based on oxygen-enriched pyrolysis combustion according to any one of claims 1 to 4, characterized in that: The treatment device also includes an air preheater (7), wherein a cold air duct and an oxygen-containing air duct are provided in the air preheater (7), and a high-temperature flue gas duct for circulating the high-temperature flue gas is also provided in the air preheater (7), and the cold air duct, the oxygen-containing air duct and the high-temperature flue gas duct in the air preheater (7) are connected to each other by heat exchange via heat exchange fins; The oxygen heat exchanger (91) is also provided with a cold air duct and an oxygen-containing air duct. At the same time, the oxygen heat exchanger (91) is also provided with a carbon dioxide flue gas duct for circulating carbon dioxide-rich flue gas. The cold air duct, the oxygen-containing air duct and the carbon dioxide flue gas duct in the oxygen heat exchanger (91) are connected to each other for heat exchange via heat exchange fins. The cold air duct in the air preheater (7) is connected to the cold air duct in the oxygen preheater (6), and the air outlet end of the cold air duct in the oxygen preheater (6) is connected to the air inlet end of the CFB incinerator (8), so that the cold air enters the CFB incinerator (8) after heat exchange with the high-temperature flue gas and the carbon dioxide-rich flue gas to increase the temperature; The oxygen-containing air pipeline in the air preheater (7) is connected to the oxygen-containing air pipeline in the oxygen preheater (6), and the air outlet end of the oxygen-containing air pipeline in the oxygen preheater (6) is simultaneously connected to the air inlet end of the pyrolysis furnace (3) and the air inlet end of the pyrolysis gas combustion furnace (4), so that the oxygen-containing air can exchange heat with the high-temperature flue gas and the carbon dioxide-rich flue gas and enter the pyrolysis furnace (3) and the pyrolysis gas combustion furnace (4) after the oxygen-containing air is heated to a set temperature.

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

7. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 6 is characterized in that: The air inlet end of the oxygen-containing air pipeline in the air preheater (7) is connected to an air separation device (10) which can separate the cold air into nitrogen and oxygen-containing air.

8. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 7 is characterized in that: The CFB incinerator (8) is also provided with a coal inlet pipe for adding pulverized coal into its furnace.

9. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 8, characterized in that: The flue gas outlet end of the CFB incinerator (8) is also connected to the air inlet end of the solid recovery device (11).

10. The urban sludge treatment device based on oxygen-enriched pyrolysis combustion according to claim 9, characterized in that: The temperature of the high-temperature air, the temperature of the oxygen-containing air entering the pyrolysis furnace (3), and the temperature of the oxygen-containing air entering the pyrolysis gas combustion furnace (4) are all above 600°C.

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