Negative electrode material graphitized flue gas multi-pollutant efficient treatment and resource utilization method based on waste heat gradient utilization

Abstract

The invention relates to a negative electrode material graphitized flue gas multi-pollutant efficient treatment and resource utilization method based on waste heat gradient utilization. The method comprises the following steps: collecting 800-1100 DEG C high-temperature flue gas generated by a graphitization process in a closed manner, removing dust through a two-stage cyclone separator, and cooling to 600 + / -20 DEG C through an atomization quench tower; in the high-temperature section, a radiation type waste heat boiler is adopted for generating saturated steam to drive a back pressure type steam turbine to generate power, and the back pressure steam is used for preheating fed materials; the medium-temperature section is subjected to SCR denitration and RCO catalytic oxidation integrated treatment in the integrated reaction tower, and the treated flue gas enters an ORC generator set for secondary power generation; the low-temperature section is deeply purified through cloth bag dust removal, a heat pipe heat exchanger, dual-alkali desulfurization and wet electrostatic dust removal, and recycled waste heat is used for preheating air or heating process water. Through the gradient utilization mode of high-temperature power generation, medium-temperature power compensation and low-temperature preheating, the overall waste heat recovery efficiency is improved to 50% or above from 20% in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of green production and pollutant treatment technology of lithium-ion battery anode materials, and specifically relates to a method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas of anode materials based on the cascade utilization of waste heat. Background Technology

[0002] Graphitization, a core process in the production of artificial graphite anode materials, requires prolonged processing at high temperatures of 2800-3000℃. Producing one ton of artificial graphite anode material consumes approximately 12,000-15,000 kWh of electricity, accompanied by the emission of large amounts of high-temperature flue gas (temperature 800-1100℃, air volume 50,000-150,000 Nm³ / h). With the rapid development of the lithium-ion battery industry, the environmental and energy-saving issues facing the graphitization process for anode materials have become increasingly prominent, evolving from single-pollutant treatment to a complex problem of "energy waste - pollution control - high costs." In recent years, waste heat recovery and pollutant treatment technologies in the graphitization process have received widespread attention. A research paper published in ScienceDirect, "Investigation of the waste heat recovery and pollutant emission reduction potential in graphitization furnace" (2022), systematically analyzed the waste heat recovery and pollutant emission reduction potential of graphitization furnaces. The study showed that approximately 48.5% of the waste heat can be recovered from the coke surface, resulting in annual reductions of CO2, SO2, and NO2 emissions. x The figures were 47.5 tons, 7.4 tons, and 3.6 tons, respectively. This study provides a theoretical basis for energy conservation and emission reduction in graphitization furnaces, but it mainly remains at the potential analysis stage and does not propose specific engineering implementation plans.

[0003] Regarding graphitization production equipment, Chinese patent CN105460928A discloses a continuous high-temperature heat treatment production line for granular graphite, including a preheating feeding device, an intermediate silo, a vertical continuous induction heating furnace, a discharge device, and a waste gas and residue collection device. This technology realizes high-temperature purification, graphitization, carbonization, and other high-temperature heat treatment processes, featuring high efficiency, low energy consumption, and environmental friendliness. However, it mainly focuses on optimizing the production equipment itself, providing only a general description of the waste gas and residue collection device without addressing specific waste heat recovery technologies and multi-pollutant co-treatment schemes for flue gas. In terms of resource utilization, Chinese patent CN103579624A discloses a modified graphite crucible waste lithium battery anode material and its preparation method. By mixing graphite crucible waste with asphalt precursors and using spray drying processes, the anode material is prepared, achieving resource utilization of the waste. This technology provides a framework for the recycling of graphite waste, but it primarily focuses on material preparation, representing a different technological direction from graphitization flue gas treatment. Regarding graphitization technology, US Patent 4394766 discloses a graphitization system, method, and apparatus for the production of graphite electrodes and other graphitized bodies, providing an improved graphitization process to enhance efficiency and product quality. International Patent WO2024221561A1 discloses a graphitization furnace and battery production system, improving the quality of graphitized products through improvements in furnace structure and electrode design. These patents primarily focus on optimizing the graphitization process itself and do not address flue gas treatment or waste heat recovery technologies. Chinese Patent CN102951914A discloses an electrode paste produced using industrial waste carbon materials and its preparation method, realizing the resource utilization of waste carbon materials. However, this technology is mainly applied to the field of electrode paste preparation, which differs from the technical route of graphitization flue gas treatment. European Patent EP4007017B1 discloses negative electrode materials for lithium-ion secondary batteries, focusing on controlling the graphitization degree of the negative electrode material (preferably above 93%) to improve battery capacity. However, it mainly focuses on material performance optimization and does not address environmental protection and energy conservation issues in the graphitization production process.

[0004] Based on existing technologies, the current graphitization process faces the following main technical challenges: First, the multi-pollutant treatment system for flue gas is fragmented. Graphitized flue gas contains particulate matter (mainly carbon black dust, concentration 300-800 mg / m³), sulfur dioxide (SO2, 500-1200 mg / m³), and nitrogen oxides (NOx). xThe flue gas contains a variety of pollutants, including volatile organic compounds (VOCs, 200-500 mg / m³) and polycyclic aromatic hydrocarbons (PAHs, 5-20 μg / m³). Current technologies often employ a series process of "cyclone dust removal + wet desulfurization + low-temperature denitrification," which suffers from a mismatch in temperature requirements between the various treatment units. For example, SCR denitrification requires a reaction temperature of 300-350℃, while the flue gas temperature drops to 50-70℃ after wet desulfurization, necessitating additional fuel consumption to raise the temperature and increasing energy consumption. Simultaneously, asphalt fumes adhering to the surface of the denitrification catalyst shorten its service life by more than 50%, and dust entering the absorption tower easily causes nozzle blockage, increasing system operation and maintenance costs by 30%-40%.

[0005] Second, the utilization rate of waste heat resources is extremely low. The theoretical heat recovery potential of high-temperature flue gas at 800-1100℃ can reach 300-500 kWh / ton of anode material, but existing technologies utilize only a single method, mostly using shell-and-tube heat exchangers to generate low-pressure steam (0.3-0.8 MPa) for winter heating only, resulting in significant waste of heat energy. More importantly, the waste heat recovery system and the pollutant treatment system operate independently, failing to form a synergistic effect, resulting in an overall energy utilization efficiency of less than 20%, which is significantly lower than the theoretical recovery potential of 48.5% proposed in the aforementioned research paper.

[0006] Third, there is a lack of integrated system solutions. The relevant patents retrieved have significant limitations: CN106989606A, "A Graphitization Furnace Flue Gas Treatment and Waste Heat Utilization System," only uses a waste heat boiler to generate steam for preheating combustion air, failing to achieve high-quality energy output such as electricity, and does not address the deep treatment of VOCs and PAHs; CN202221449633U, "A Carbon Graphitization Tail Gas Treatment Device," uses an "adsorption-desorption-RTO" process to treat VOCs, but does not incorporate the high-temperature characteristics of the flue gas into its waste heat utilization scheme. The RTO device requires additional natural gas consumption, resulting in high operating costs. Existing technologies treat waste heat recovery and pollutant treatment as independent systems, failing to achieve dynamic matching and optimization of energy and material flows.

[0007] Therefore, the industry urgently needs an integrated technology that can realize the three-in-one approach of "waste heat cascade recovery - pollutant synergistic treatment - resource recycling" to break through the environmental protection and energy-saving bottlenecks of the graphitization process of negative electrode materials. Summary of the Invention

[0008] To address the aforementioned problems, the purpose of this invention is to provide a method for the efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on the cascade utilization of waste heat. This invention improves the overall waste heat recovery efficiency from 20% in the prior art to over 50% through a cascade utilization mode of high-temperature power generation, medium-temperature power supplementation, and low-temperature preheating.

[0009] The technical solution of this invention is: a method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas using waste heat as a negative electrode material, comprising the following steps: S1: High-temperature flue gas closed-loop collection and pretreatment, the specific process is as follows: The high-temperature flue gas generated by the graphitization process of the negative electrode material at 800-1100℃ is collected by a closed collection hood, and dust with a particle size ≥10μm is removed by a two-stage cyclone separator. Then, the flue gas is rapidly cooled from 700-1000℃ to 600±20℃ by an atomizing quench tower at a cooling rate of 5-8℃ / s. S2: Primary utilization of waste heat in the high-temperature section, the specific process is as follows: Flue gas at 600±20℃ is fed into a radiant waste heat boiler to generate medium- and high-pressure saturated steam at 2.5-3.0MPa and 280-320℃. The steam drives a back-pressure turbine to generate electricity. The 0.8-1.2MPa back-pressure steam discharged after power generation is used for preheating the feed to the graphitization furnace, and the flue gas temperature is reduced to 350±20℃. S3: Synergistic treatment of multiple pollutants in the mid-temperature range and secondary utilization of waste heat, the specific process is as follows: Flue gas at 350±20℃ is introduced into an integrated reaction tower, which is equipped with an SCR denitrification unit and an RCO catalytic oxidation unit. The SCR denitrification unit is filled with a low-temperature vanadium-titanium catalyst and 20%-25% ammonia water is injected for denitrification treatment. The RCO catalytic oxidation unit is filled with a Pt-Pd / Al2O3 catalyst to catalytically oxidize VOCs and PAHs. The treated flue gas enters the ORC generator set and uses R245fa as the working fluid for medium and low temperature power generation, and the flue gas temperature is reduced to 180±20℃. S4: Deep treatment of low-temperature section and three-stage utilization of waste heat. The specific process is as follows: The flue gas at 180±20℃ is first subjected to deep dust removal by a bag filter. Then, the waste heat of the flue gas at 180±20℃ is recovered by a heat pipe heat exchanger and used to preheat the combustion air to 120-150℃ or heat the process water to 60-80℃, so that the flue gas temperature is reduced to 100±10℃. Subsequently, the flue gas enters the dual-alkali desulfurization tower and wet electrostatic precipitator for desulfurization and fine dust removal. Finally, the exhaust gas temperature is controlled above 70℃.

[0010] The nozzle pressure of the atomizing quench tower is 3.0-4.0 MPa, the atomizing particle size is 50-100 μm, and the flue gas humidity is controlled to be ≤15%.

[0011] The dual-stage cyclone separator includes a primary cyclone separator and a secondary cyclone separator. The diameter of the primary cyclone separator is 1000-1400mm, and the diameter of the secondary cyclone separator is 600-1000mm. The dust removal efficiency is ≥85%. The carbon black dust collected by the dual-stage cyclone separator is temporarily stored in a closed silo and recycled to the graphitization furnace at a ratio of ≤10%.

[0012] The sealed collection hood is made of high-temperature resistant ceramic fiber material.

[0013] The radiant waste heat boiler adopts a membrane water-cooled wall structure, is made of 310S stainless steel, has a design pressure of 2.5-3.5MPa, an evaporation capacity of 12-25t / h, and a back-pressure steam turbine generator with a rated power of 1800-2800kW and a power generation efficiency of ≥32%.

[0014] The integrated reaction tower is a variable-diameter cylindrical structure, with a denitrification section diameter of 3500-4500 mm, a catalytic oxidation section diameter of 5000-6000 mm, and a total height of 10-15 m. Internally, from top to bottom, it contains an SCR denitrification catalyst layer and an RCO catalytic oxidation catalyst layer. In the integrated reaction tower, the low-temperature vanadium-titanium catalyst in the SCR denitrification unit has an activity temperature of 280-350℃ and a space velocity of 12000-25000 h⁻¹. -1 The excess coefficient of reducing agent is 1.05-1.15, the denitrification efficiency is ≥88%, the active temperature of the Pt-Pd / Al2O3 catalyst in the RCO catalytic oxidation unit is 250-320℃, and the oxidation efficiency of VOCs and PAHs is ≥98%.

[0015] The ORC generator set includes an evaporator, an expander, a condenser, and a working fluid pump. The ORC generator set uses R245fa as the working fluid, has a rated power of 500-900kW, a power generation efficiency of ≥10%, and an inlet flue gas temperature of 280-360℃.

[0016] The dual-alkali desulfurization method adopts a NaOH+Ca(OH)2 dual-alkali system, with NaOH concentration of 2%-3% and Ca(OH)2 concentration of 5%-8%, desulfurization efficiency ≥93%, and purity of by-product CaSO4·2H2O ≥88%.

[0017] The heat pipes of the heat pipe heat exchanger are made of carbon steel or stainless steel, and the working medium is water. It recovers waste heat from flue gas at 100-180℃, preheats the combustion air to 120-150℃ or heats the process water to 60-80℃, and the waste heat recovery rate is ≥55%.

[0018] A high-efficiency treatment and resource utilization system for multi-pollutant flue gas from graphitized anode materials based on waste heat cascade utilization includes a flue gas collection and pretreatment system, a high-temperature section waste heat primary utilization system, a mid-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system, a low-temperature section deep treatment and waste heat tertiary utilization system, and a DCS central control system. The flue gas collection and pretreatment system includes a sealed collection hood, a two-stage cyclone separator, and an atomizing quench tower. The high-temperature section waste heat primary utilization system includes a radiant waste heat boiler and a back-pressure steam turbine generator set. The mid-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system... The system includes an integrated reaction tower and an ORC generator set. The integrated reaction tower is equipped with an SCR denitrification unit and an RCO catalytic oxidation unit. The low-temperature deep treatment and waste heat three-stage utilization system includes a bag filter, a heat pipe heat exchanger, a dual-alkali desulfurization tower, and a wet electrostatic precipitator. The DCS central control system is used to realize temperature linkage control, pollutant concentration feedback control, and energy optimization allocation. It automatically adjusts the water spray volume of the atomizing quench tower according to the flue gas temperature at the outlet of the radiant waste heat boiler, adjusts the turbine back pressure according to the inlet temperature of the ORC generator set, and adjusts the SO2 and NO levels based on online monitoring. x The concentration of alkaline solution and ammonia water is automatically adjusted, and the back pressure steam is automatically switched according to the power load of the plant area. The flue gas collection and pretreatment system, the high-temperature section waste heat primary utilization system, the medium-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system, and the low-temperature section deep treatment and waste heat tertiary utilization system are connected in sequence through pipelines to form a dual-mainline coupling system for dynamic matching of energy flow and material flow.

[0019] The technical effects of this invention are as follows: 1. This invention, through a tiered utilization model of high-temperature power generation, medium-temperature supplementary power generation, and low-temperature preheating, increases the overall waste heat recovery efficiency from 20% to over 50% compared to existing technologies. Taking a 50,000-ton / year anode material production line as an example, the annual power generation can reach 20.8 million kWh, meeting 25%-30% of the production line's electricity demand, saving 7,500-8,000 tons of standard coal annually, reducing CO2 emissions by 20,000-22,000 tons, achieving energy self-sufficiency, and achieving a leapfrog improvement in energy utilization efficiency; 2. Based on the principle of temperature matching, this invention completes the removal of various pollutants in the optimal reaction temperature zone. SCR denitrification is carried out at 280-350℃ to avoid catalyst deactivation caused by low temperatures. RCO catalytic oxidation utilizes flue gas waste heat without additional energy consumption and achieves a VOCs removal rate of ≥99%. The combination of dual-alkali desulfurization and deep dust removal ensures that all pollutants meet emission standards and there is no secondary pollution, resulting in significant synergistic treatment effects; 3. The waste heat of this invention... The power generation feedback system reduces external power purchase expenditures, saving approximately 12-15 million yuan annually in electricity costs; the integrated reaction tower reduces equipment footprint by 30%, extends catalyst replacement cycle to 3-4 years, and reduces annual operation and maintenance costs by 40%-50%; the collected carbon black dust reuse reduces raw material procurement costs by approximately 2-3 million yuan annually, significantly reducing operating costs; 4. This invention can be directly applied to the transformation of existing negative electrode material graphitization production lines, with a short transformation cycle (3-6 months) and an investment recovery period of approximately 3-4 years. Simultaneously, it promotes the coordinated development of the environmental protection equipment-energy recovery-resource recycling industrial chain, providing technical support for the green transformation of the lithium-ion battery industry, demonstrating significant industrial upgrading value; 5. This invention achieves dynamic matching of energy flow and material flow through a dual-mainline coupling system, forming a closed-loop system of waste-to-waste treatment and energy self-sufficiency. Pollutant emission concentrations meet ultra-low emission requirements (particulate matter ≤10mg / m³, SO2 ≤35mg / m³, NO...). x (≤50mg / m³, VOCs≤20mg / m³), with a high degree of system integration.

[0020] The following will provide further explanation in conjunction with the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for efficient treatment and resource utilization of multiple pollutants in flue gas based on graphitized negative electrode materials using waste heat cascade utilization, according to the present invention.

[0022] Figure 2 This is a flowchart illustrating the process steps of a method for efficient treatment and resource utilization of multiple pollutants in flue gas based on the graphitization of negative electrode materials using waste heat cascade utilization, according to the present invention.

[0023] Figure 3 This is a structural diagram of a system for efficient treatment and resource utilization of multiple pollutants in flue gas based on graphitized negative electrode material with waste heat utilization according to the present invention.

[0024] Attached reference numerals: 1-Graphitization furnace; 2-Sealed collection hood; 3-Two-stage cyclone separator; 4-Atomizing quench tower; 5-Radiant waste heat boiler; 6-Back pressure steam turbine generator set; 7-Integrated reaction tower; 8-ORC generator set; 9-Bag filter; 10-Heat pipe heat exchanger; 11-Dual alkali desulfurization tower; 12-Wet electrostatic precipitator; 13-Chimney; 14-Sealed silo. Detailed Implementation Example 1

[0025] like Figure 1 , Figure 2 As shown, a method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas using waste heat-based negative electrode materials includes the following steps: S1: High-temperature flue gas closed-loop collection and pretreatment, the specific process is as follows: The high-temperature flue gas generated by the graphitization process of the negative electrode material at 800-1100℃ is collected by a closed collection hood, and dust with a particle size ≥10μm is removed by a two-stage cyclone separator. Then, the flue gas is rapidly cooled from 700-1000℃ to 600±20℃ by an atomizing quench tower at a cooling rate of 5-8℃ / s. S2: Primary utilization of waste heat in the high-temperature section, the specific process is as follows: Flue gas at 600±20℃ is fed into a radiant waste heat boiler to generate medium- and high-pressure saturated steam at 2.5-3.0MPa and 280-320℃. The steam drives a back-pressure turbine to generate electricity. The 0.8-1.2MPa back-pressure steam discharged after power generation is used for preheating the feed to the graphitization furnace, and the flue gas temperature is reduced to 350±20℃. S3: Synergistic treatment of multiple pollutants in the mid-temperature range and secondary utilization of waste heat, the specific process is as follows: Flue gas at 350±20℃ is introduced into an integrated reaction tower, which is equipped with an SCR denitrification unit and an RCO catalytic oxidation unit. The SCR denitrification unit is filled with a low-temperature vanadium-titanium catalyst and 20%-25% ammonia water is injected for denitrification treatment. The RCO catalytic oxidation unit is filled with a Pt-Pd / Al2O3 catalyst to catalytically oxidize VOCs and PAHs. The treated flue gas enters the ORC generator set and uses R245fa as the working fluid for medium and low temperature power generation, and the flue gas temperature is reduced to 180±20℃. S4: Deep treatment of low-temperature section and three-stage utilization of waste heat. The specific process is as follows: The flue gas at 180±20℃ is first subjected to deep dust removal by a bag filter. Then, the waste heat of the flue gas at 180±20℃ is recovered by a heat pipe heat exchanger and used to preheat the combustion air to 120-150℃ or heat the process water to 60-80℃, so that the flue gas temperature is reduced to 100±10℃. Subsequently, the flue gas enters the dual-alkali desulfurization tower and wet electrostatic precipitator for desulfurization and fine dust removal. Finally, the exhaust gas temperature is controlled above 70℃.

[0026] The nozzle pressure of the atomizing quench tower is 3.0-4.0 MPa, the atomizing particle size is 50-100 μm, and the flue gas humidity is controlled to be ≤15%.

[0027] The dual-stage cyclone separator includes a primary cyclone separator and a secondary cyclone separator. The diameter of the primary cyclone separator is 1000-1400mm, and the diameter of the secondary cyclone separator is 600-1000mm. The dust removal efficiency is ≥85%. The carbon black dust collected by the dual-stage cyclone separator is temporarily stored in a closed silo and recycled to the graphitization furnace at a ratio of ≤10%.

[0028] The sealed collection hood is made of high-temperature resistant ceramic fiber material.

[0029] The radiant waste heat boiler adopts a membrane water-cooled wall structure, is made of 310S stainless steel, has a design pressure of 2.5-3.5MPa, an evaporation capacity of 12-25t / h, and a back-pressure steam turbine generator with a rated power of 1800-2800kW and a power generation efficiency of ≥32%.

[0030] The integrated reaction tower is a variable-diameter cylindrical structure, with a denitrification section diameter of 3500-4500 mm, a catalytic oxidation section diameter of 5000-6000 mm, and a total height of 10-15 m. Internally, from top to bottom, it contains an SCR denitrification catalyst layer and an RCO catalytic oxidation catalyst layer. In the integrated reaction tower, the low-temperature vanadium-titanium catalyst in the SCR denitrification unit has an activity temperature of 280-350℃ and a space velocity of 12000-25000 h⁻¹. -1 The excess coefficient of reducing agent is 1.05-1.15, the denitrification efficiency is ≥88%, the active temperature of the Pt-Pd / Al2O3 catalyst in the RCO catalytic oxidation unit is 250-320℃, and the oxidation efficiency of VOCs and PAHs is ≥98%.

[0031] The ORC generator set includes an evaporator, an expander, a condenser, and a working fluid pump. The ORC generator set uses R245fa as the working fluid, has a rated power of 500-900kW, a power generation efficiency of ≥10%, and an inlet flue gas temperature of 280-360℃.

[0032] The dual-alkali desulfurization method adopts a NaOH+Ca(OH)2 dual-alkali system, with NaOH concentration of 2%-3% and Ca(OH)2 concentration of 5%-8%, desulfurization efficiency ≥93%, and purity of by-product CaSO4·2H2O ≥88%.

[0033] The heat pipes of the heat pipe heat exchanger are made of carbon steel or stainless steel, and the working medium is water. It recovers waste heat from flue gas at 100-180℃, preheats the combustion air to 120-150℃ or heats the process water to 60-80℃, and the waste heat recovery rate is ≥55%.

[0034] like Figure 3 As shown, a high-efficiency treatment and resource utilization system for multi-pollutant flue gas based on the cascade utilization of waste heat and graphitized anode materials includes a flue gas collection and pretreatment system, a high-temperature section waste heat primary utilization system, a mid-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system, a low-temperature section deep treatment and waste heat tertiary utilization system, and a DCS central control system. The flue gas collection and pretreatment system includes a sealed collection hood 2, a two-stage cyclone separator 3, and an atomizing quench tower 4; the high-temperature section waste heat primary utilization system includes a radiant waste heat boiler 5 and a back-pressure steam turbine generator set 6; the mid-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system... The system includes an integrated reaction tower 7 and an ORC generator set 8. The integrated reaction tower 7 is equipped with an SCR denitrification unit and an RCO catalytic oxidation unit. The low-temperature deep treatment and waste heat three-stage utilization system includes a bag filter 9, a heat pipe heat exchanger 10, a dual-alkali desulfurization tower 11, and a wet electrostatic precipitator 12. The DCS central control system is used to realize temperature linkage control, pollutant concentration feedback control, and energy optimization allocation. It automatically adjusts the water spray volume of the atomizing quench tower 4 according to the outlet flue gas temperature of the radiant waste heat boiler 5, adjusts the turbine back pressure according to the inlet temperature of the ORC generator set 8, and adjusts the SO2 and NO2 levels based on online monitoring. x The concentration of alkaline solution and ammonia water is automatically adjusted, and the back pressure steam is automatically switched according to the power load of the plant area. The flue gas collection and pretreatment system, the high-temperature section waste heat primary utilization system, the medium-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system, and the low-temperature section deep treatment and waste heat tertiary utilization system are connected in sequence through pipelines to form a dual-mainline coupling system for dynamic matching of energy flow and material flow.

[0035] This invention provides a method for the efficient treatment and resource utilization of multiple pollutants in graphitization of negative electrode materials based on waste heat cascade utilization. A dual-mainline coupled system is constructed, with waste heat cascade utilization as the energy flow mainline and multi-pollutant synergistic treatment as the material flow mainline. Energy self-sufficiency is achieved through dynamic matching of energy and material flows. First, the high-temperature flue gas (800-1100℃) generated by the graphitization process is collected in a sealed environment. Large-particle dust is removed by a two-stage cyclone separator, and the gas is rapidly cooled to 600±20℃ by an atomizing quench tower. Then, a three-stage waste heat utilization process is implemented: In the high-temperature stage, a radiant waste heat boiler generates medium- and high-pressure saturated steam to drive a back-pressure turbine for power generation; the back-pressure steam after power generation is used for feed preheating. In the medium-temperature stage, integrated SCR denitrification and RCO catalytic oxidation are performed in an integrated reaction tower; the treated flue gas then enters an ORC generator set for secondary power generation. In the low-temperature stage, deep purification and waste heat recovery are achieved sequentially through bag filters, heat pipe heat exchangers, dual-alkali desulfurization, and wet electrostatic precipitators; the recovered waste heat is used for air preheating or process water heating. The entire process utilizes a DCS central control system to achieve temperature linkage control, pollutant concentration feedback control, and optimized energy allocation, ensuring waste heat recovery efficiency ≥50%, pollutant emissions meeting ultra-low emission standards, operating costs reduced by ≥40%, and energy self-sufficiency rate ≥30% in the treatment process. ≤10% of the collected carbon black dust is recycled to graphitization raw materials, and the byproduct calcium sulfate is sold as a building material raw material, realizing the resource utilization of waste. Example 2

[0036] The method for efficient treatment and resource utilization of multiple pollutants in flue gas from graphitization of anode materials based on waste heat cascade utilization, as described in Example 1, was applied to the complete system of a 50,000-ton-per-year anode material production line. The specific process is as follows: Taking a production line with an annual output of 50,000 tons of artificial graphite anode material as an example, the flue gas parameters of the graphitization furnace are: air volume 100,000 Nm³ / h, temperature 950±50℃, pollutant concentration SO2: 1000 mg / m³, NO xThe system's emissions are: PM2.5: 800 mg / m³, particulate matter: 400 mg / m³, VOCs: 300 mg / m³. The system design is based on a dual-mainline coupling principle: the energy flow mainline achieves three-stage utilization of high-temperature flue gas (800-1100℃), while the material flow mainline precisely removes various pollutants within the optimal temperature range. A high-temperature resistant ceramic fiber-sealed flue gas collection hood ensures a collection efficiency of ≥99%. A two-stage cyclone separator (first stage Φ1200mm, second stage Φ800mm) removes dust particles ≥10μm in diameter, achieving a dust removal efficiency of 85%. The atomizing quench tower uses 12 nozzles (pressure 3.5MPa, atomized particle size 50-100μm) to rapidly reduce the flue gas temperature from 950℃ to 600℃ at a cooling rate of 6.25℃ / s, preventing dioxin synthesis in the 200-400℃ temperature range. The radiant waste heat boiler adopts a membrane water-cooled wall structure (made of 310S stainless steel), operates at a pressure of 3.0 MPa, has an evaporation capacity of 18 t / h, and produces saturated steam at 2.5 MPa and 300℃. The back-pressure turbine generator set has a rated power of 2200 kW and an actual power generation efficiency of 34.8%. The back-pressure steam (0.9 MPa) is used for raw material preheating, heating the graphitization raw materials from 25℃ to 200℃. The integrated reaction tower (SCR denitrification section diameter Φ4000 mm, catalytic oxidation section diameter Φ5500 mm, total height 12 m) houses an SCR denitrification unit filled with 50 m³ of low-temperature vanadium-titanium catalyst (active temperature 280-350℃, space velocity 15000 h⁻¹). -1 The system injects 80L / h of 20%-25% ammonia water (reducing agent excess coefficient 1.08), achieving a denitrification efficiency of 91%. The RCO catalytic oxidation unit is filled with 30m³ of Pt-Pd / Al2O3 catalyst (active temperature 250-320℃), achieving a VOCs removal rate of 99.2%, utilizing waste heat from the flue gas without requiring additional heating. The ORC generator set uses R245fa working fluid (critical temperature 154℃, critical pressure 3.65MPa), with a rated power of 700kW and an actual power generation efficiency of 11.8%. The bag filter (filtration area 2000m², 1200 PPS filter bags, filtration velocity 0.9m / min) achieves a dust removal efficiency of 99.5%. The heat pipe heat exchanger (heat exchange area 1500m², 20# steel material, water as working fluid) preheats the combustion air to 140℃, achieving a waste heat recovery rate of 60%. The dual-alkali desulfurization tower (Φ4500mm, 15m high) uses 2.5% NaOH and 7% Ca(OH)2, achieving a desulfurization efficiency of 95% and producing 90% pure CaSO4·2H2O as a byproduct. A wet electrostatic precipitator (electrode area 800m², electric field wind speed 1.1m / s) ensures that the final particulate matter concentration is ≤10mg / m³, with a final exhaust temperature of 80℃.

[0037] Technical benefits: Overall waste heat recovery efficiency is 52.3%, annual power generation is 20.8 million kWh, meeting 28% of the production line's electricity demand; pollutant emission concentrations: particulate matter 8 mg / m³, SO2 32 mg / m³, NO...x With emissions of 48 mg / m³ and VOCs of 15 mg / m³, all meeting ultra-low emission requirements; annual savings of 7,800 tons of standard coal and reduction of 21,000 tons of CO2 emissions; a 42% reduction in operating costs, and a return on investment for the optimized parameters of medium-sized production lines. Example 3

[0038] The method for efficient treatment and resource utilization of multiple pollutants in flue gas from graphitization of anode materials based on waste heat cascade utilization, as described in Example 1, was applied to the complete system of a 30,000-ton-per-year anode material production line. The specific process is as follows: For a production line with an annual output of 30,000 tons of anode materials, with a flue gas volume of 60,000 Nm³ / h and a temperature of 900±30℃, the parameters were optimized using the midpoint of the range. The two-stage cyclone separator was reduced to a single stage with a diameter of 1000 mm and a second stage with a diameter of 700 mm, with the processing capacity matching the flue gas volume. The atomizing quench tower uses 8 nozzles at a pressure of 3.2 MPa to cool the flue gas to 600℃. The waste heat boiler has an evaporation capacity of 12 t / h, producing 2.8 MPa steam, and a back-pressure turbine with a power output of 1800 kW and a power generation efficiency of 33.5%. The integrated reaction tower has an SCR denitrification section with a diameter of 3500 mm and a catalytic oxidation section with a diameter of 5000 mm, an SCR catalyst loading of 30 m³, and a space velocity of 18000 h⁻¹. -1 The ammonia dosage is 50 L / h, with a denitrification efficiency of 88%; the RCO catalyst loading is 18 m³, with a VOCs removal rate of 98.5%. The ORC generator set has a power output of 500 kW and a power generation efficiency of 10.5%. The bag filter has a filtration area of ​​1200 m² and 800 filter bags. The heat pipe heat exchanger has an area of ​​1000 m² and an air preheating temperature of 130℃. The dual-alkali desulfurization tower has a diameter of 3800 mm, a NaOH concentration of 2.2%, a Ca(OH)₂ concentration of 6%, and a desulfurization efficiency of 93%.

[0039] Technical benefits: Waste heat recovery efficiency 50.8%, annual power generation 13.8 million kWh, meeting 26% of the production line's electricity demand; Pollutant emissions: Particulate matter 9 mg / m³, SO2 35 mg / m³, NO... x 52mg / m³, VOCs 18mg / m³; operating costs reduced by 38%, suitable for the economic requirements of medium-sized production lines. Example 4

[0040] The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials, as described in Example 1, is implemented to achieve maximum waste heat recovery under high-temperature endpoint conditions. The specific process is as follows: For the high-temperature endpoint conditions of the graphitization process (flue gas temperature 1100℃, air volume 150,000 Nm³ / h), maximum waste heat recovery is achieved by configuring parameters at their upper limits. A two-stage cyclone separator with a first stage of Φ1400mm and a second stage of Φ1000mm handles high-volume flue gas. The atomizing quench tower uses 16 nozzles at a pressure of 4.0MPa to ensure rapid cooling from 1100℃ to 600℃ at a cooling rate of 8℃ / s. The radiant waste heat boiler has an evaporation capacity of 25t / h, producing 3.0MPa steam, and a back-pressure turbine with a power output of 2800kW and a power generation efficiency of 35.2%. The integrated reaction tower has a 4500mm diameter denitrification section and a 6000mm diameter catalytic oxidation section, with an SCR catalyst loading of 80m³ and a space velocity of 25,000h⁻¹. -1 The ammonia dosage is 120 L / h, achieving a denitrification efficiency of 92%. The RCO catalyst loading is 50 m³, achieving a VOCs removal rate of 99.5% under high-temperature conditions. The ORC generator set has a power output of 900 kW, fully utilizing the waste heat from the high-temperature flue gas, with a power generation efficiency of 12.5%. The bag filter has a filtration area of ​​3000 m² and 1800 filter bags. The heat pipe heat exchanger has an area of ​​2000 m², with an air preheating temperature of 150℃, maximizing waste heat utilization. The dual-alkali desulfurization tower has a diameter of 5000 mm, handling high-volume flue gas with a NaOH concentration of 3% and a Ca(OH)₂ concentration of 8%, achieving a desulfurization efficiency of 96%.

[0041] Technical benefits: Waste heat recovery efficiency reaches 53.8%, annual power generation is 29.2 million kWh, meeting 32% of the production line's electricity demand; pollutant emissions are better than standards: particulate matter 7 mg / m³, SO2 28 mg / m³, NO... x 45mg / m³, VOCs 12mg / m³; annual savings of 10,500 tons of standard coal, reduction of 28,000 tons of CO2 emissions; operating costs reduced by 45%, demonstrating the best results for large-scale application. Example 5

[0042] The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials, as described in Example 1, is as follows: Experimental conditions: The same 50,000-ton-per-year production line as in Example 2 was used. Flue gas parameters: air volume 100,000 Nm³ / h, temperature 950℃, pollutant concentration SO₂: 1000 mg / m³, NO₂: 1000 mg / m³. x Specific emissions: 800 mg / m³, particulate matter: 400 mg / m³, VOCs: 300 mg / m³. The test was conducted continuously for 30 days, and all indicators were recorded using an online monitoring system.

[0043] Experimental results: Waste heat recovery efficiency 52.3%, total power generation (steam turbine + ORC) 2830kW, pollutant emission concentrations: particulate matter 8mg / m³, SO2 32mg / m³, NOx The system has a concentration of 48 mg / m³ and VOCs of 15 mg / m³, with an annual operating cost of 6.8 million yuan and an energy self-sufficiency rate of 30.2%.

[0044] Comparative Example 1 The traditional series treatment method is adopted, and the specific process is as follows: Experimental conditions: Under the same production line conditions as Example 5, a traditional 'cyclone dust removal + wet desulfurization + low-temperature SCR denitrification' series process was used. Waste heat was only used to generate 0.5MPa low-pressure steam for heating through a shell-and-tube heat exchanger. The test period was 30 days. Experimental results: Waste heat recovery efficiency was only 18.5%, power generation was 0 kW (no power generation unit), and pollutant emissions were: particulate matter 15 mg / m³, SO2 45 mg / m³, NO... x With a concentration of 85 mg / m³ and VOCs of 45 mg / m³, the system operating cost is 11.8 million yuan per year, and external power needs to be purchased to support the operation of the treatment device.

[0045] 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 changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas using waste heat-based negative electrode materials, characterized in that: Includes the following steps: S1: High-temperature flue gas closed-loop collection and pretreatment, the specific process is as follows: The high-temperature flue gas generated by the graphitization process of the negative electrode material at 800-1100℃ is collected by a closed collection hood, and dust with a particle size ≥10μm is removed by a two-stage cyclone separator. Then, the flue gas is rapidly cooled from 700-1000℃ to 600±20℃ by an atomizing quench tower at a cooling rate of 5-8℃ / s. S2: Primary utilization of waste heat in the high-temperature section, the specific process is as follows: Flue gas at 600±20℃ is fed into a radiant waste heat boiler to generate medium- and high-pressure saturated steam at 2.5-3.0MPa and 280-320℃. The steam drives a back-pressure turbine to generate electricity. The 0.8-1.2MPa back-pressure steam discharged after power generation is used for preheating the feed to the graphitization furnace, and the flue gas temperature is reduced to 350±20℃. S3: Synergistic treatment of multiple pollutants in the mid-temperature range and secondary utilization of waste heat, the specific process is as follows: Flue gas at 350±20℃ is introduced into an integrated reaction tower, which is equipped with an SCR denitrification unit and an RCO catalytic oxidation unit. The SCR denitrification unit is filled with a low-temperature vanadium-titanium catalyst and 20%-25% ammonia water is injected for denitrification treatment. The RCO catalytic oxidation unit is filled with a Pt-Pd / Al2O3 catalyst to catalytically oxidize VOCs and PAHs. The treated flue gas enters the ORC generator set and uses R245fa as the working fluid for medium and low temperature power generation, and the flue gas temperature is reduced to 180±20℃. S4: Deep treatment of low-temperature section and three-stage utilization of waste heat. The specific process is as follows: The flue gas at 180±20℃ is first subjected to deep dust removal by a bag filter. Then, the waste heat of the flue gas at 180±20℃ is recovered by a heat pipe heat exchanger and used to preheat the combustion air to 120-150℃ or heat the process water to 60-80℃, so that the flue gas temperature is reduced to 100±10℃. Subsequently, the flue gas enters the dual-alkali desulfurization tower and wet electrostatic precipitator for desulfurization and fine dust removal. Finally, the exhaust gas temperature is controlled above 70℃.

2. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials according to claim 1, characterized in that: The nozzle pressure of the atomizing quench tower is 3.0-4.0 MPa, the atomizing particle size is 50-100 μm, and the flue gas humidity is controlled to be ≤15%.

3. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials according to claim 1, characterized in that: The dual-stage cyclone separator includes a primary cyclone separator and a secondary cyclone separator. The diameter of the primary cyclone separator is 1000-1400mm, and the diameter of the secondary cyclone separator is 600-1000mm. The dust removal efficiency is ≥85%. The carbon black dust collected by the dual-stage cyclone separator is temporarily stored in a closed silo and recycled to the graphitization furnace at a ratio of ≤10%.

4. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials, as described in claim 1, is characterized in that: The sealed collection hood is made of high-temperature resistant ceramic fiber material.

5. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials according to claim 1, characterized in that: The radiant waste heat boiler adopts a membrane water-cooled wall structure, is made of 310S stainless steel, has a design pressure of 2.5-3.5MPa, an evaporation capacity of 12-25t / h, and a back-pressure steam turbine generator with a rated power of 1800-2800kW and a power generation efficiency of ≥32%.

6. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials according to claim 1, characterized in that: The integrated reaction tower is a variable-diameter cylindrical structure, with a denitrification section diameter of 3500-4500 mm, a catalytic oxidation section diameter of 5000-6000 mm, and a total height of 10-15 m. Internally, from top to bottom, it contains an SCR denitrification catalyst layer and an RCO catalytic oxidation catalyst layer. In the integrated reaction tower, the low-temperature vanadium-titanium catalyst in the SCR denitrification unit has an activity temperature of 280-350℃ and a space velocity of 12000-25000 h⁻¹. -1 The excess coefficient of reducing agent is 1.05-1.15, the denitrification efficiency is ≥88%, the active temperature of the Pt-Pd / Al2O3 catalyst in the RCO catalytic oxidation unit is 250-320℃, and the oxidation efficiency of VOCs and PAHs is ≥98%.

7. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials according to claim 1, characterized in that: The ORC generator set includes an evaporator, an expander, a condenser, and a working fluid pump. The ORC generator set uses R245fa as the working fluid, has a rated power of 500-900kW, a power generation efficiency of ≥10%, and an inlet flue gas temperature of 280-360℃.

8. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials according to claim 1, characterized in that: The dual-alkali desulfurization method adopts a NaOH+Ca(OH)2 dual-alkali system, with NaOH concentration of 2%-3% and Ca(OH)2 concentration of 5%-8%, desulfurization efficiency ≥93%, and purity of by-product CaSO4·2H2O ≥88%.

9. The method for efficient treatment and resource utilization of multiple pollutants in graphitized flue gas based on waste heat cascade utilization of negative electrode materials according to claim 1, characterized in that: The heat pipes of the heat pipe heat exchanger are made of carbon steel or stainless steel, and the working medium is water. It recovers waste heat from flue gas at 100-180℃, preheats the combustion air to 120-150℃ or heats the process water to 60-80℃, and the waste heat recovery rate is ≥55%.

10. A high-efficiency treatment and resource utilization system for multiple pollutants in graphitized flue gas using waste heat cascade utilization of negative electrode materials, characterized in that: The system includes a flue gas collection and pretreatment system, a high-temperature section waste heat primary utilization system, a mid-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system, a low-temperature section deep treatment and waste heat tertiary utilization system, and a DCS central control system. The flue gas collection and pretreatment system includes a sealed collection hood (2), a two-stage cyclone separator (3), and an atomizing quench tower (4). The high-temperature section waste heat primary utilization system includes a radiant waste heat boiler (5) and a back-pressure steam turbine generator set (6). The mid-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system includes an integrated reaction tower (7) and an ORC generator set (8). The integrated reaction tower (7) is equipped with an SCR denitrification unit and an RCO catalytic oxidation unit; the low-temperature section deep treatment and waste heat three-stage utilization system includes a bag filter (9), a heat pipe heat exchanger (10), a dual-alkali desulfurization tower (11), and a wet electrostatic precipitator (12); the DCS central control system is used to realize temperature linkage control, pollutant concentration feedback control and energy optimization allocation, automatically adjust the water spray volume of the atomizing quench tower (4) according to the outlet flue gas temperature of the radiant waste heat boiler (5), adjust the turbine back pressure according to the inlet temperature of the ORC generator set (8), and adjust the SO2 and NO2 levels according to the online monitoring. x The concentration of alkaline solution and ammonia water is automatically adjusted, and the back pressure steam is automatically switched according to the power load of the plant area. The flue gas collection and pretreatment system, the high-temperature section waste heat primary utilization system, the medium-temperature section multi-pollutant synergistic treatment and waste heat secondary utilization system, and the low-temperature section deep treatment and waste heat tertiary utilization system are connected in sequence through pipelines to form a dual-mainline coupling system for dynamic matching of energy flow and material flow.

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