A dry desulfurization, defluorination, and dust removal system and method for electrolytic aluminum flue gas

Abstract

This invention provides a dry desulfurization, defluorination, and dust removal system and method for electrolytic aluminum flue gas. The system includes an integrated defluorination and dust removal device, an absorption and adsorption device, and a bag filter connected in sequence. The integrated defluorination and dust removal device is used to defluorinate and remove dust from the input electrolytic aluminum flue gas. The absorption and adsorption device includes a high-temperature absorption and adsorption mechanism and a low-temperature absorption and adsorption mechanism arranged in parallel. The inlet ends of both the high-temperature and low-temperature absorption and adsorption mechanisms are connected to the outlet end of the integrated defluorination and dust removal device. The high-temperature and low-temperature absorption and adsorption mechanisms are configured to automatically distribute the electrolytic aluminum flue gas to the corresponding high-temperature or low-temperature absorption and adsorption mechanism for desulfurization treatment based on the temperature and / or dew point of the electrolytic aluminum flue gas flowing out of the integrated defluorination and dust removal device. The bag filter is used to remove dust from the desulfurized electrolytic aluminum flue gas. This system can achieve synergistic and efficient removal of multiple pollutants such as sulfur, fluoride, and dust.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, and specifically relates to a dry desulfurization, defluorination and dust removal system and method for electrolytic aluminum flue gas. Background Technology

[0002] With increasingly stringent environmental protection requirements, controlling flue gas emissions from the electrolytic aluminum industry has become a key technological challenge. Electrolytic aluminum production employs the cryolite-alumina molten salt electrolysis process, which generates a large volume of flue gas requiring treatment. This flue gas is characterized by high flow rates, low pollutant concentrations, complex compositions, and significant temperature fluctuations. Within the temperature range of 60-150℃, conventional desulfurization processes struggle to maintain high and stable removal efficiency. Furthermore, the electrolytic production process requires continuous operation; therefore, the flue gas purification system must possess the reliability for long-term stable operation.

[0003] To address the aforementioned problems, existing technologies have proposed a variety of solutions.

[0004] For example, Chinese invention patent CN111330404B discloses a flue gas defluorination, desulfurization, and dust removal purification system and process. It mainly adopts a two-stage series structure of defluorination and dust removal sections, achieving graded and deep removal of pollutants through two defluorination reactions and two desulfurization reactions. Although this solution can handle multiple pollutants, its system is complex, requires numerous devices, occupies a large area, and has high investment and operating costs, and its removal efficiency for ultrafine particles is limited.

[0005] For example, another invention patent CN110339702B discloses an electrolytic aluminum flue gas desulfurization system that uses a mixed humidification process, but it is also difficult to adapt to large temperature changes. Insufficient water addition at low temperatures affects desulfurization efficiency, while excessive water addition can easily lead to problems such as equipment condensation and pipeline blockage. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas, which can not only optimize and control the desulfurization, defluorination and dust removal of electrolytic aluminum flue gas and achieve synergistic and efficient removal of multiple pollutants such as sulfur, fluoride and dust, but also effectively improve the compactness of the system structure, the stability and reliability of operation, and the ease of operation.

[0007] Another objective of this invention is to provide a dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas includes an integrated defluorination and dust removal device, an absorption and adsorption device and a bag filter device connected in sequence.

[0010] The integrated defluorination and dust removal device is used to defluorinate and remove dust from the input electrolytic aluminum flue gas.

[0011] The absorption and adsorption device includes a high-temperature absorption and adsorption mechanism and a low-temperature absorption and adsorption mechanism arranged in parallel. The inlet ends of the high-temperature absorption and adsorption mechanism and the low-temperature absorption and adsorption mechanism are both connected to the outlet end of the defluorination and dust removal integrated device. The high-temperature absorption and adsorption mechanism and the low-temperature absorption and adsorption mechanism are configured to automatically distribute the electrolytic aluminum flue gas to the corresponding high-temperature absorption and adsorption mechanism or the low-temperature absorption and adsorption mechanism for desulfurization treatment based on the temperature and / or water dew point of the electrolytic aluminum flue gas flowing out of the defluorination and dust removal integrated device.

[0012] The inlet end of the bag filter is connected to the outlet ends of the high-temperature absorption and adsorption mechanism and the low-temperature absorption and adsorption mechanism, respectively, for dust removal from the electrolytic aluminum flue gas after desulfurization treatment.

[0013] Optionally, it also includes a flue gas inlet pipe, one end of which is connected to the electrolytic aluminum flue gas, and the other end of which is connected to the inlet of the defluorination and dust removal integrated device.

[0014] Optionally, the inlet end of the defluorination and dust removal integrated device is provided with multiple inlets;

[0015] The smoke inlet duct includes a main smoke duct and a plurality of branch smoke ducts connected to the main smoke duct, and one inlet is connected to one branch smoke duct.

[0016] Optionally, it also includes a first injection assembly connected to the flue gas inlet duct, the first injection assembly being configured to inject aluminum oxide into the flue gas inlet duct;

[0017] The first injection assembly includes a first injection body and a first injection pipe, one end of the first injection pipe is connected to the first injection body, and the other end is connected to the smoke inlet pipe.

[0018] Optionally, the first injection pipeline includes a first injection main pipeline and a plurality of first injection branch pipelines, one end of each first injection branch pipeline being connected to the first injection main pipeline, and the other end being connected to each of the branch flues in a corresponding manner, and / or,

[0019] The first injection branch pipe is equipped with a regulating valve for adjusting the flow rate of the electrolytic aluminum flue gas.

[0020] Optional, also includes:

[0021] A high-temperature flue gas conditioning component is disposed between the defluorination and dust removal integrated device and the high-temperature absorption and adsorption mechanism.

[0022] A first temperature detection component is provided at the inlet end of the high-temperature absorption and adsorption mechanism, and a second temperature detection component and a first humidity detection component are provided at the outlet end of the high-temperature absorption and adsorption mechanism. The first temperature detection component, the second temperature detection component and the first humidity detection component are all electrically connected to the high-temperature flue gas conditioning component.

[0023] Optional, also includes:

[0024] A low-temperature flue gas conditioning component is disposed between the defluorination and dust removal integrated device and the low-temperature absorption and adsorption mechanism.

[0025] A third temperature detection component is provided at the inlet end of the low-temperature absorption and adsorption mechanism, and a fourth temperature detection component and a second humidity detection component are provided at the outlet end of the low-temperature absorption and adsorption mechanism. The third temperature detection component, the fourth temperature detection component and the second humidity detection component are all electrically connected to the low-temperature flue gas conditioning component.

[0026] Optionally, it may also include a second spraying assembly connected to the high-temperature absorption and adsorption mechanism, the second spraying assembly being used to spray a highly active calcium-based or sodium-based absorbent;

[0027] The second spraying assembly includes a second spraying body and multiple second spraying pipes. One end of each second spraying pipe is connected to the second spraying body, and the other end is connected to the high-temperature absorption and adsorption mechanism.

[0028] Optionally, a third spraying assembly 5 connected to the low-temperature absorption and adsorption mechanism is also included, the third spraying assembly 5 being used to spray sodium-based absorbent.

[0029] Optionally, it may also include a humidification and activation component, which is connected to the low-temperature absorption and adsorption mechanism.

[0030] Optionally, it also includes an intermediate flue, one end of which is connected to the high-temperature absorption and adsorption mechanism and the low-temperature absorption and adsorption mechanism respectively, and the other end is connected to the bag filter dust collector. A circulating material pipeline is also provided between the bag filter dust collector and the low-temperature absorption and adsorption mechanism.

[0031] Optionally, it also includes a smoke outlet duct, one end of which is connected to the outlet end of the bag filter dust collector, and the other end is connected to the chimney;

[0032] An induced draft fan is also installed on the smoke outlet duct.

[0033] A method for dry desulfurization, defluorination, and dust removal of electrolytic aluminum flue gas, applied to any of the above-described dry desulfurization, defluorination, and dust removal systems for electrolytic aluminum flue gas, includes the following steps:

[0034] S100: Performs defluorination and dust removal treatment on electrolytic aluminum flue gas to reduce the concentration of fluorides and dust in the electrolytic aluminum flue gas;

[0035] S200: Based on the temperature and / or water dew point of the treated electrolytic aluminum flue gas, the electrolytic aluminum flue gas is distributed to a parallel high-temperature absorption and adsorption mechanism and / or a low-temperature absorption and adsorption mechanism, and the electrolytic aluminum flue gas is subjected to desulfurization treatment in the high-temperature absorption and adsorption mechanism and the low-temperature absorption and adsorption mechanism respectively.

[0036] S300: After the electrolytic aluminum flue gas flowing out from the high-temperature absorption and adsorption mechanism and the low-temperature absorption and adsorption mechanism is combined, bag filter dust removal is performed to make the sulfide concentration in the electrolytic aluminum flue gas within a first preset threshold, the fluoride concentration within a second preset threshold, and the dust concentration within a third preset threshold.

[0037] Optionally, in step S100, alumina is injected into the inlet of the defluorination and dust removal integrated device, and the molar ratio of the injected alumina to hydrogen fluoride in the electrolytic aluminum flue gas is controlled to be 0.2-0.5.

[0038] Optionally, step S200 specifically includes the following steps:

[0039] S201: Monitor the temperature and humidity of the electrolytic aluminum flue gas flowing out of the integrated defluorination and dust removal device;

[0040] S202: When the temperature of the electrolytic aluminum flue gas is higher than the fourth preset threshold, the proportion of flue gas allocated to the high-temperature absorption and adsorption mechanism is increased.

[0041] S203: When the temperature of the electrolytic aluminum flue gas is lower than the fifth preset threshold, increase the proportion of flue gas allocated to the low-temperature absorption and adsorption mechanism.

[0042] Optionally, in step S200, a highly active calcium-based or sodium-based absorbent is sprayed into the high-temperature absorption and adsorption mechanism, and the molar ratio of the sprayed active calcium-based or sodium-based absorbent to the sulfides in the electrolytic aluminum flue gas is controlled to be 1.2-1.4.

[0043] Optionally, the BET specific surface area of ​​the highly active calcium-based or sodium-based absorbent is not less than 30 m² / g.

[0044] Optionally, step S200 includes:

[0045] The low-temperature absorption and adsorption mechanism is humidified and cooled so that the temperature of the electrolytic aluminum flue gas 100 is more than 5°C higher than its water dew point temperature.

[0046] A calcium-based absorbent is injected into the humidified and cooled electrolytic aluminum flue gas;

[0047] The molar ratio of the injected calcium-based absorbent to sulfur in the electrolytic aluminum flue gas is controlled to be 1.3-1.6.

[0048] Optionally, the BET specific surface area of ​​the calcium-based absorbent is not less than 20 m² / g.

[0049] Optionally, step S300 includes:

[0050] The temperature of the electrolytic aluminum flue gas entering the bag filter is controlled to be more than 15°C higher than its water dew point temperature.

[0051] The electrolytic aluminum flue gas is passed into a bag filter for filtration.

[0052] The dust collected by the bag filter is collected, and a portion of the dust is returned to the low-temperature absorption and adsorption mechanism for recycling.

[0053] Optionally, the first preset threshold is 5 mg / Nm³. 3 The second preset threshold is 0.5 mg / Nm³. 3 The third preset threshold is 5 mg / Nm 3 .

[0054] As can be seen from the above technical solutions, when performing dry desulfurization, defluorination, and dust removal of electrolytic aluminum flue gas, electrolytic aluminum flue gas at approximately 60℃~150℃ is first input into the integrated defluorination and dust removal device, where defluorination and dust removal are achieved. Then, the flue gas after defluorination and dust removal is automatically distributed to parallel high-temperature absorption and adsorption mechanisms or low-temperature absorption and adsorption mechanisms according to its temperature and / or water dew point to achieve desulfurization treatment. Finally, the electrolytic aluminum flue gas treated by the high-temperature absorption and adsorption mechanism and the low-temperature absorption and adsorption mechanism enters the bag filter dust collector for deep dust removal treatment.

[0055] Compared with the prior art, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in the embodiments of the present invention has the following technical effects:

[0056] 1) By adopting the process flow of defluorination and dust removal → diversion desulfurization → deep dust removal, the three types of pollutants, namely fluorine, sulfur and dust, are treated separately, graded and synergistically. Among them, the pre-set setting of the defluorination and dust removal integrated device can avoid the interference of sulfides on the defluorination adsorbent, so that the subsequent desulfurization stage is not affected by fluoride dust, which can effectively improve the utilization rate and reaction efficiency of desulfurizing agent.

[0057] 2) Through the parallel arrangement of high-temperature absorption and adsorption mechanisms and low-temperature absorption and adsorption mechanisms, the system can intelligently switch or distribute airflow according to the flue gas temperature (60℃~150℃) and water dew point, thereby significantly improving the system's adaptability to flue gas operating condition fluctuations, achieving optimized control and stable operation of the desulfurization process, and thus realizing the synergistic and efficient removal of multiple pollutants such as sulfur, fluorine and dust.

[0058] 3) The dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas has a compact structure, stable and reliable operation, and is easy to operate. Attached Figure Description

[0059] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0060] Figure 1 This is a schematic diagram of the structure of the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in the embodiments of the present invention.

[0061] Explanation of reference numerals in the attached figures:

[0062] 100-Electrolytic aluminum flue gas,

[0063] 200 - Smoke inlet duct, 201 - First injection assembly,

[0064] 300-Defluorination and Dust Removal Integrated Unit

[0065] 400 - High-temperature absorption and adsorption mechanism; 401 - High-temperature flue gas conditioning component; 402 - Second injection component.

[0066] 500 - Low-temperature absorption and adsorption mechanism; 501 - Low-temperature flue gas conditioning component; 502 - Third injection component; 503 - Humidification and activation component.

[0067] 600-baghouse dust collector

[0068] 700-Intermediate flue,

[0069] 800-Circulating Material Pipeline

[0070] 900 - Smoke exhaust duct, 901 - Exhaust fan,

[0071] 1000-Chimney. Detailed Implementation

[0072] In view of this, the core of the present invention is to provide a dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas, which can not only optimize and control the desulfurization, defluorination and dust removal of electrolytic aluminum flue gas and achieve synergistic and efficient removal of multiple pollutants such as sulfur, fluoride and dust, but also effectively improve the compactness of the system structure, the stability and reliability of operation, and the ease of operation.

[0073] Another core aspect of this invention lies in providing a dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas.

[0074] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Please refer to [the accompanying drawings]. Figure 1 .

[0075] First, the relevant terms and concepts appearing in this invention will be explained:

[0076] Electrolytic aluminum flue gas is a complex and highly hazardous mixed gas produced during the aluminum electrolysis production process. It mainly uses cryolite-alumina molten salt electrolysis to produce aluminum. That is, a strong direct current is introduced into the electrolytic cell, molten cryolite is used as the solvent, alumina is used as the solute, carbonaceous material is used as the anode, and molten aluminum is used as the cathode. At 950℃-970℃, the electrolyte undergoes a complex electrochemical reaction in the electrolytic cell. The alumina is decomposed, and liquid metallic aluminum is deposited at the cathode at the bottom of the cell, releasing gas. The gas enters the subsequent alumina adsorption, desulfurization and dust removal device for treatment and discharge.

[0077] The characteristics of electrolytic aluminum flue gas are: 1) large flue gas volume and low pollutant concentration; 2) SO2 concentration is generally <200mg / Nm³. 3 (Related to the sulfur content of the anode carbon block, reaching up to 300 mg / Nm³) 3 Dust concentration <15 mg / Nm 3 F concentration < 5 mg / Nm 3 3) The flue gas composition should consist of CO, CO2, O2, N2, HF, CF4, etc., mainly O2 and N2, with low moisture content; 4) The flue gas volume should be stable with minimal fluctuations; 5) Since all flues in the electrolytic aluminum industry are not insulated, the summer temperature is 120℃~150℃ and the winter temperature is 60℃~100℃; 6) The flue gas purification system should operate continuously and stably for a long time, and shutdown is not allowed. The electrolytic aluminum main unit is required to run continuously year-round; 7) The electrolytic cell has a magnetic field after being powered on, so anti-magnetic protection must be considered, especially ensuring that the equipment is reliably grounded. Otherwise, the equipment is prone to short circuits and damage.

[0078] Please refer to Figure 1The dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention includes a defluorination and dust removal integrated device 300, an absorption and adsorption device and a bag filter device 600 connected in sequence.

[0079] The integrated defluorination and dust removal device 300 is used to defluorinate and remove dust from the input electrolytic aluminum flue gas 100. The adsorption device includes a high-temperature absorption adsorption mechanism 400 and a low-temperature absorption adsorption mechanism 500 connected in parallel. The inlet ends of the high-temperature absorption adsorption mechanism 400 and the low-temperature absorption adsorption mechanism 500 are both connected to the outlet end of the integrated defluorination and dust removal device 300. The high-temperature absorption adsorption mechanism 400 and the low-temperature absorption adsorption mechanism 500 are configured to automatically distribute the electrolytic aluminum flue gas 100 to the corresponding high-temperature absorption adsorption mechanism 400 or low-temperature absorption adsorption mechanism 500 for desulfurization treatment based on the temperature and / or water dew point of the electrolytic aluminum flue gas 100 flowing out of the integrated defluorination and dust removal device 300. The inlet end of the bag filter 600 is connected to the outlet end of the high-temperature absorption adsorption mechanism 400 and the low-temperature absorption adsorption mechanism 500 respectively, and is used to remove dust from the desulfurized electrolytic aluminum flue gas 100.

[0080] When performing dry desulfurization, defluorination, and dust removal of electrolytic aluminum flue gas, the electrolytic aluminum flue gas 100 at approximately 60℃~150℃ is first input into the defluorination and dust removal integrated device 300, where the electrolytic aluminum flue gas 100 is defluorinated and dust removed. Then, the flue gas after defluorination and dust removal is automatically distributed to the parallel-arranged high-temperature absorption and adsorption mechanism 400 or low-temperature absorption and adsorption mechanism 500 according to its temperature and / or water dew point to achieve desulfurization treatment. Finally, the electrolytic aluminum flue gas 100 after being treated by the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 enters the bag filter dust collector 600 for deep dust removal treatment.

[0081] Compared with the prior art, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in the embodiments of the present invention has the following technical effects:

[0082] 1) By adopting the process flow of defluorination and dust removal → diversion desulfurization → deep dust removal, the three types of pollutants, namely fluorine, sulfur and dust, are treated separately, graded and synergistically. Among them, the pre-set setting of the defluorination and dust removal integrated device can avoid the interference of sulfides on the defluorination adsorbent, so that the subsequent desulfurization stage is not affected by fluoride dust, which can effectively improve the utilization rate and reaction efficiency of desulfurizing agent.

[0083] 2) Through the parallel arrangement of the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500, the system can intelligently switch or distribute the airflow according to the flue gas temperature (60℃~150℃) and water dew point, thereby significantly improving the system's adaptability to flue gas operating conditions, realizing optimized control and stable operation of the desulfurization process, and thus achieving synergistic and efficient removal of multiple pollutants such as sulfur, fluorine and dust.

[0084] 3) The dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas has a compact structure, stable and reliable operation, and is easy to operate.

[0085] As a further embodiment, the dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas disclosed in this invention further includes an inlet pipe 200, wherein one end of the inlet pipe 200 is connected to the electrolytic aluminum flue gas 100, and the other end is connected to the inlet end of the defluorination and dust removal integrated device 300. With this configuration, the electrolytic aluminum flue gas 100 can enter the defluorination and dust removal integrated device 300 from the inlet pipe 200 for defluorination and dust removal treatment.

[0086] In some specific examples, the integrated defluorination and dust removal device 300 disclosed in this embodiment of the invention has multiple inlets at its inlet end, and the flue gas inlet duct 200 includes a main flue and multiple branch flues connected to the main flue, with one inlet corresponding to one branch flue. The arrangement of multiple inlets and multiple branch flues allows for flexible and effective adjustment of the flue gas volume.

[0087] It should be noted that a flue gas regulating valve is installed in the branch flue. The amount of flue gas entering the defluorination and dust removal integrated device 300 can be adjusted by adjusting the opening of the flue gas regulating valve.

[0088] As a further embodiment, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention further includes a first injection component 201 connected to the flue gas inlet pipe 200, the first injection component 201 being configured to inject aluminum oxide into the flue gas inlet pipe 200.

[0089] The first injection assembly 201 includes a first injection body and a first injection pipe. One end of the first injection pipe is connected to the first injection body, and the other end is connected to the flue gas inlet duct 200. When the electrolytic aluminum flue gas 100 enters the flue gas inlet duct 200, the injection amount of alumina can be controlled by adjusting the first injection assembly 201, so that the electrolytic aluminum flue gas 100 and alumina are evenly distributed and mixed before entering the defluorination and dust removal integrated device 300.

[0090] The embodiments of the present invention do not limit the specific structure of the first injection pipeline. Any structure that meets the requirements of the present invention is within the protection scope of the present invention.

[0091] In some specific examples, the first injection pipeline disclosed in the embodiments of the present invention includes a first injection main pipeline and a plurality of first injection branch pipelines. One end of each first injection branch pipeline is connected to the first injection main pipeline, and the other end is connected to a corresponding branch flue. A regulating valve for adjusting the flow rate of the electrolytic aluminum flue gas 100 is provided within each first injection branch pipeline.

[0092] With this setup, the amount of alumina injected can be effectively controlled by adjusting the opening of the regulating valve, and the multiple first injection branch pipes can further improve the precise control of the alumina injection amount.

[0093] As a further embodiment, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention further includes a high-temperature flue gas conditioning component 401 disposed between the defluorination and dust removal integrated device 300 and the high-temperature absorption and adsorption mechanism 400, a first temperature detection component disposed at the inlet end of the high-temperature absorption and adsorption mechanism 400, a second temperature detection component disposed at the outlet end of the high-temperature absorption and adsorption mechanism 400, and a first humidity detection component, wherein the first temperature detection component, the second temperature detection component and the first humidity monitoring device are all electrically connected to the high-temperature flue gas conditioning component 401.

[0094] In a specific embodiment, a first temperature detection component detects the temperature at the inlet of the high-temperature absorption and adsorption mechanism 400, a second temperature detection component detects the temperature at the outlet of the high-temperature absorption and adsorption mechanism 400, and a first humidity detection component detects the humidity at the inlet of the high-temperature absorption and adsorption mechanism 400. The first temperature detection component, the second temperature detection component, and the first humidity detection component can transmit the detection result signals to a high-temperature flue gas regulating component 401, which can regulate the amount of flue gas entering the high-temperature absorption and adsorption mechanism 400. With this configuration, by real-time monitoring of the temperature at the inlet, the temperature at the outlet, and the humidity of the high-temperature absorption and adsorption mechanism 400, the system can obtain key thermodynamic state parameters of the absorption and adsorption reaction, thereby providing a basis for further precise control of the reaction conditions.

[0095] As a further embodiment, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention further includes a low-temperature flue gas conditioning component 501 disposed between the defluorination and dust removal integrated device 300 and the low-temperature absorption and adsorption mechanism 500, a third temperature detection component disposed at the inlet end of the low-temperature absorption and adsorption mechanism 500, a fourth temperature detection component and a second humidity detection component disposed at the outlet end of the low-temperature absorption and adsorption mechanism 500, wherein the third temperature detection component, the fourth temperature detection component and the second humidity detection component are all electrically connected to the low-temperature flue gas conditioning component 501.

[0096] The third temperature detection component, the fourth temperature detection component, and the second humidity detection component can transmit the detection result signal to the low-temperature flue gas conditioning component 501, which adjusts the amount of flue gas entering the high-temperature absorption and adsorption mechanism 400.

[0097] With this setup, by monitoring the temperature at the inlet of the low-temperature absorption and adsorption mechanism 500 and the temperature and humidity at the outlet in real time, the system can obtain key thermodynamic state parameters of the absorption and adsorption reaction, thus providing a basis for further precise control of reaction conditions.

[0098] As a further embodiment, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention further includes a second spraying component 402 connected to the high-temperature absorption and adsorption mechanism 400. The second spraying component 402 is used to spray highly active calcium-based or sodium-based absorbent.

[0099] The second spraying assembly includes a second spraying body and multiple second spraying pipes. One end of each second spraying pipe is connected to the second spraying body, and the other end is connected to the high-temperature absorption and adsorption mechanism 400.

[0100] With this setup, highly active calcium-based or sodium-based absorbents are sprayed into the high-temperature absorption and adsorption unit 400, which can undergo efficient gas-solid heterogeneous chemical reactions with residual acidic pollutants such as sulfur dioxide (SO2), sulfur trioxide (SO3), and hydrogen fluoride (HF) in the flue gas, achieving deep desulfurization and defluorination. This can compensate for the insufficient removal efficiency that may exist in the upstream desulfurization and defluorination processes, thereby further improving the overall purification depth and reliability of the system.

[0101] As a further embodiment, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention further includes a third spraying component 502 connected to the low-temperature absorption and adsorption mechanism 500, wherein the third spraying component 502 is used to spray sodium-based absorbent.

[0102] Because sodium-based absorbents still have extremely high reactivity at low temperatures, when they are sprayed into the low-temperature absorption and adsorption unit 500, they can undergo rapid and efficient acid-base neutralization reactions with residual sulfur dioxide (SO2), sulfur trioxide (SO3), hydrogen chloride (HCl), and trace amounts of hydrogen fluoride (HF) in the flue gas, thereby achieving deep purification of pollutants.

[0103] As a further embodiment, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention also includes a humidification and activation component 503, which is connected to the low-temperature absorption and adsorption mechanism 500.

[0104] With this setup, by introducing process gas with controllable humidity into the low-temperature absorption and adsorption mechanism 500, the flue gas can be precisely humidified, creating a high-humidity active reaction environment.

[0105] As a further embodiment, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in this embodiment of the invention further includes an intermediate flue 700, wherein one end of the intermediate flue 700 is connected to the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 respectively, and the other end is connected to the bag filter dust collector 600, and a circulating material pipeline 800 is also provided between the bag filter dust collector 600 and the low-temperature absorption and adsorption mechanism 500.

[0106] Among them, the intermediate flue 700 serves as a key connecting component, connecting the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 in series with the end bag filter dust collector 600, thereby enabling dust removal treatment of the flue gas after desulfurization.

[0107] The bag filter 600 collects unreacted materials, most of which are recycled back to the low-temperature absorption and adsorption unit 500 through the circulating material pipeline 800 to continue participating in the reaction. A small amount of by-products after the reaction are discharged to the by-product storage silo and transported away by sealed tank trucks.

[0108] As a further embodiment, the dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas disclosed in this invention also includes a flue gas outlet duct 900. One end of the flue gas outlet duct 900 is connected to the outlet end of the bag filter 600, and the other end is connected to the chimney 1000. An induced draft fan 901 is also installed on the flue gas outlet duct 900. The induced draft fan 901 serves as the core power source of the entire purification system, providing the necessary pressure and flow rate for the flue gas flow. It can overcome all system resistance generated when the electrolytic aluminum flue gas 100 flows through a series of devices, including the integrated defluorination and dust removal device 300, the high-temperature absorption and adsorption mechanism 400, the low-temperature absorption and adsorption mechanism 500, the intermediate flue 700, and the bag filter 600, ensuring that the electrolytic aluminum flue gas 100 can flow stably and continuously according to the designed process path.

[0109] This invention also discloses a dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas, applied to the dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas disclosed in any of the above embodiments, comprising the following steps:

[0110] S100: Perform defluorination and dust removal treatment on the electrolytic aluminum flue gas 100 to reduce the concentration of fluoride and dust in the electrolytic aluminum flue gas 100.

[0111] S200: Based on the temperature and / or water dew point of the treated electrolytic aluminum flue gas 100, the electrolytic aluminum flue gas 100 is distributed to the parallel high-temperature absorption and adsorption mechanism 400 and / or low-temperature absorption and adsorption mechanism 500; the electrolytic aluminum flue gas 100 is desulfurized in the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 respectively.

[0112] S300: After the electrolytic aluminum flue gas 100 flowing from the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 is combined, it is subjected to bag dust removal treatment, so that the sulfide concentration in the electrolytic aluminum flue gas 100 is within the first preset threshold, the fluoride concentration is within the second preset threshold, and the dust concentration is within the third preset threshold.

[0113] In the dry desulfurization, defluorination, and dust removal of electrolytic aluminum flue gas, electrolytic aluminum flue gas 100 at approximately 60℃~150℃ is first input into the defluorination and dust removal integrated device 300, where the electrolytic aluminum flue gas 100 is defluorinated and dust removed. Then, the flue gas after defluorination and dust removal is automatically distributed to the parallel-arranged high-temperature absorption and adsorption mechanism 400 or low-temperature absorption and adsorption mechanism 500 for desulfurization treatment, based on its temperature and / or water dew point. Finally, the electrolytic aluminum flue gas 100 after being treated by the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 enters the bag filter dust collector 600 for deep dust removal treatment, so that the sulfide concentration in the electrolytic aluminum flue gas 100 is within the first preset threshold, the fluoride concentration is within the second preset threshold, and the dust concentration is within the third preset threshold.

[0114] Compared with the prior art, the dry desulfurization, defluorination and dust removal system for electrolytic aluminum flue gas disclosed in the embodiments of the present invention has the following technical effects:

[0115] 1) By adopting the process flow of defluorination and dust removal → diversion desulfurization → deep dust removal, the three types of pollutants, namely fluorine, sulfur and dust, are treated separately, graded and synergistically. Among them, the pre-set setting of the defluorination and dust removal integrated device can avoid the interference of sulfides on the defluorination adsorbent, so that the subsequent desulfurization stage is not affected by fluoride dust, which can effectively improve the utilization rate and reaction efficiency of desulfurizing agent.

[0116] 2) By using the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 connected in parallel, the system can intelligently switch or distribute the airflow according to the flue gas temperature (60℃~150℃) and water dew point, thereby significantly improving the system's adaptability to flue gas operating conditions, achieving optimized control and stable operation of the desulfurization process, and thus realizing the synergistic and efficient removal of multiple pollutants such as sulfur, fluorine and dust.

[0117] As a further embodiment, in step S100 disclosed in this embodiment of the invention, alumina is injected into the inlet end of the defluorination and dust removal integrated device 300, and the molar ratio of the injected alumina to hydrogen fluoride in the electrolytic aluminum flue gas 100 is controlled to be 0.2-0.5.

[0118] This molar ratio range is an optimized interval verified by experiments. When the molar ratio is below 0.2, the amount of alumina injected is insufficient, failing to fully adsorb HF in the flue gas, leading to a decrease in defluorination efficiency and potentially failing to meet emission standards. When the molar ratio is above 0.5, it may cause excessive consumption of alumina, resulting in poor economic efficiency and potentially increasing the dust load of subsequent systems. The molar ratio setting of 0.2-0.5 disclosed in this embodiment of the invention can achieve the maximum utilization rate of the adsorbent alumina while ensuring efficient defluorination.

[0119] As a further embodiment, the dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas disclosed in this embodiment of the invention includes the following steps in step S200: S201: monitoring the temperature and humidity of the electrolytic aluminum flue gas 100 flowing out of the defluorination and dust removal integrated device 300; S202: when the temperature of the electrolytic aluminum flue gas 100 is higher than a fourth preset threshold, increasing the proportion of flue gas allocated to the high-temperature absorption and adsorption mechanism 400; S203: when the temperature of the electrolytic aluminum flue gas 100 is lower than a fifth preset threshold, increasing the proportion of flue gas allocated to the low-temperature absorption and adsorption mechanism 500.

[0120] As a further embodiment, in the dry desulfurization, defluorination and dust removal method for electrolytic aluminum flue gas disclosed in this embodiment of the invention, in step S200, a highly active calcium-based or sodium-based absorbent is sprayed into the high-temperature absorption and adsorption mechanism 400, and the molar ratio of the sprayed highly active calcium-based or sodium-based absorbent to the sulfides in the electrolytic aluminum flue gas 100 is controlled to be 1.2-1.4.

[0121] This range setting ensures that the absorbent is sufficient relative to the sulfides, thereby guaranteeing that the sulfide removal efficiency can reach a stable level under complex actual operating conditions, thus achieving deep desulfurization and enabling emissions to meet standards.

[0122] It should be noted that in the dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas disclosed in this embodiment of the invention, the BET specific surface area of ​​the highly active calcium-based or sodium-based absorbent is not less than 30 m² / g. This configuration enables efficient and rapid desulfurization and defluorination, which is particularly beneficial for meeting the reaction rate requirements for ultra-low emissions.

[0123] As a further embodiment, the dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas disclosed in this embodiment of the invention includes step S200: humidifying and cooling the low-temperature absorption and adsorption mechanism 500 to make the temperature of the electrolytic aluminum flue gas 100 more than 5°C above its water dew point temperature; injecting a calcium-based absorbent into the humidified and cooled electrolytic aluminum flue gas 100; and controlling the molar ratio of the injected calcium-based absorbent to sulfur in the electrolytic aluminum flue gas 100 to be 1.3-1.6. This range setting can effectively eliminate the risk of condensation caused by local low temperature or temperature fluctuations, which could lead to equipment corrosion and material caking.

[0124] It should be noted that the BET specific surface area of ​​the calcium-based absorbent is not less than 20 m² / g. This setting ensures that the absorbent particles of the calcium-based absorbent have sufficient micropores and a large internal and external surface area, thereby significantly improving the desulfurization and defluorination rate.

[0125] As a further embodiment, the dry desulfurization, defluorination and dust removal method for electrolytic aluminum flue gas disclosed in this embodiment of the invention includes step S300: controlling the temperature of the electrolytic aluminum flue gas 100 entering the bag filter dust collector 600 to be more than 15°C higher than its water dew point temperature; passing the electrolytic aluminum flue gas (100) into the bag filter dust collector 600 for filtration; collecting the dust captured by the bag filter dust collector 600, and returning part of the dust to the low temperature absorption and adsorption mechanism 500 for recycling.

[0126] This design effectively eliminates the risk of condensate combining with acidic components in the electrolytic aluminum flue gas 100 to form acid that corrodes the filter bags, or causes dust to become damp and cake on the filter bag surface, ensuring that the particulate matter concentration in the emitted electrolytic aluminum flue gas 100 consistently meets ultra-low emission standards.

[0127] The dust cake layer formed on the surface of the filter bag of the bag dust collector 600 contains unreacted calcium-based or sodium-based absorbent, which further removes sulfides from the electrolytic aluminum flue gas 100 while filtering dust.

[0128] It should be noted that the first preset threshold is 5 mg / Nm³. 3 The second preset threshold is 0.5 mg / Nm³. 3 The third preset threshold is 5 mg / Nm³. This setting can meet the national environmental protection emission standards and achieve ultra-low emissions of air pollutants.

[0129] Example 1:

[0130] The dry desulfurization, defluorination, and dust removal system and method for electrolytic aluminum flue gas described in this application were applied to a 350,000-ton-per-year primary aluminum production unit in an electrolytic aluminum enterprise. The system handles a flue gas volume of 1,960,000 m³ / h, and the inlet temperature of the electrolytic aluminum flue gas ranges from 70 to 150°C. The initial flue gas pollutant concentrations were: approximately 5 mg / Nm³ for HF, approximately 350 mg / Nm³ for SO₂, approximately 20 mg / Nm³ for SO₃, and approximately 15 mg / Nm³ for particulate matter.

[0131] This is achieved through the following process steps:

[0132] Defluorination and dust removal: The electrolytic aluminum flue gas 100 to be purified is introduced into the defluorination and dust removal integrated device 300 through the flue gas inlet pipe 200. In the inlet flue (a total of 12), alumina is injected as an adsorbent through the first injection component 201. The calcium-fluoride molar ratio (Ca / F) is controlled at 0.2. The alumina efficiently adsorbs fluorides in the flue gas, achieving an outlet fluoride concentration of less than 0.5 mg / m³ and a dust concentration of less than 5 mg / m³.

[0133] Temperature-adaptive diversion desulfurization: The treated electrolytic aluminum flue gas 100 enters the parallel high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500. By monitoring the temperature and humidity at the inlet and outlet of the two mechanisms in real time, as well as the SO2 and SO3 concentrations at the chimney outlet, the system automatically adjusts the distribution ratio of flue gas entering the high-temperature and low-temperature devices. This control strategy can ensure that the temperature of the mixed flue gas at the outlet of the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 is more than 15°C higher than its water dew point temperature, while meeting the final ultra-low emission requirements of SO2 and SO3.

[0134] Absorbent addition: A highly active calcium-based absorbent is added to the high-temperature absorption and adsorption unit 400, and the calcium-sulfur molar ratio (Ca / S) is controlled at 1.3; a calcium-based absorbent is added to the low-temperature absorption and adsorption unit 500, and the calcium-sulfur molar ratio (Ca / S) is controlled at 1.5.

[0135] Particle agglomeration and deep purification: Because the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 are always in an environment conducive to particle agglomeration and coagulation, the ultrafine dust in the electrolytic aluminum flue gas 100 agglomerates into coarser particles, which are more easily captured by the subsequent bag filter dust collector 600. After the electrolytic aluminum flue gas 100 enters the bag filter dust collector 600, most of the unreacted absorbent is recycled back to the system to continue to participate in the reaction; at the same time, the calcium-based absorbent contained in the powder cake layer formed on the surface of the filter bag can further remove residual SO2 and SO3 in the flue gas, achieving synergistic desulfurization during the dust removal process;

[0136] Emissions and Byproducts: The purified electrolytic aluminum flue gas 100 is discharged into chimney 1000 via induced draft fan 901. This system can achieve a desulfurization efficiency of over 99%, ensuring that the HF concentration in the outlet flue gas is below 0.5 mg / Nm³, SO2 concentration is below 5 mg / Nm³, SO3 concentration is below 5 mg / Nm³, and dust concentration is below 5 mg / Nm³. The system is stable and easy to operate, efficiently and synergistically removing SO3, with no secondary pollution such as wastewater or waste residue throughout the process, and no special anti-corrosion treatment is required. The solid byproducts are mainly CaSO3, CaSO4, and a small amount of unreacted Ca(OH)2, which are easy to treat and utilize.

[0137] Example 2:

[0138] The dry desulfurization, defluorination, and dust removal system and method for electrolytic aluminum flue gas described in this application were applied to a 200,000-ton-per-year primary aluminum production unit in an electrolytic aluminum enterprise. The system handles a flue gas volume of 1,120,000 m³ / h, with an inlet flue gas temperature range of 60–140°C. The initial flue gas pollutant concentrations were: approximately 8 mg / Nm³ for HF, approximately 250 mg / Nm³ for SO₂, approximately 15 mg / Nm³ for SO₃, and approximately 12 mg / Nm³ for particulate matter.

[0139] This is achieved through the following process steps:

[0140] Defluorination and dust removal: The electrolytic aluminum flue gas 100 to be purified is introduced into the defluorination and dust removal integrated device 300 through the flue gas inlet pipe 200. In the inlet flue of the device (a total of 8), alumina is injected as an adsorbent through the first injection component 201. The calcium-fluoride molar ratio (Ca / F) is controlled at 0.3. The alumina efficiently adsorbs fluorides in the flue gas, so that the outlet fluoride concentration is less than 0.5 mg / m³ and the dust concentration is less than 5 mg / m³.

[0141] Temperature-adaptive diversion desulfurization: The treated electrolytic aluminum flue gas 100 enters the parallel high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500. By monitoring the temperature and humidity at the inlet and outlet of the two mechanisms in real time, as well as the SO2 and SO3 concentrations at the chimney outlet, the system automatically adjusts the distribution ratio of flue gas entering the high-temperature and low-temperature devices. This control strategy can ensure that the temperature of the mixed flue gas at the outlet of the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 is more than 15°C higher than its water dew point temperature, while meeting the final ultra-low emission requirements of SO2 and SO3.

[0142] Absorbent addition: A highly active calcium-based absorbent is added to the high-temperature absorption and adsorption unit 400, and the calcium-sulfur molar ratio (Ca / S) is controlled at 1.2; a calcium-based absorbent is added to the low-temperature absorption and adsorption unit 500, and the calcium-sulfur molar ratio (Ca / S) is controlled at 1.4.

[0143] Particle agglomeration and deep purification: Because the high-temperature absorption and adsorption mechanism 400 and the low-temperature absorption and adsorption mechanism 500 are always in an environment conducive to particle agglomeration and coagulation, the ultrafine dust in the electrolytic aluminum flue gas 100 agglomerates into coarser particles, which are more easily captured by the subsequent bag filter dust collector 600. After the electrolytic aluminum flue gas 100 enters the bag filter dust collector 600, most of the unreacted absorbent is recycled back to the system to continue to participate in the reaction; at the same time, the calcium-based absorbent contained in the powder cake layer formed on the surface of the filter bag can further remove residual SO2 and SO3 in the flue gas, achieving synergistic desulfurization during the dust removal process;

[0144] Emissions and Byproducts: The purified electrolytic aluminum flue gas 100 is discharged into chimney 1000 via induced draft fan 901. This system can achieve a desulfurization efficiency of over 99%, ensuring that the HF concentration in the outlet flue gas is below 0.5 mg / Nm³, SO2 concentration is below 5 mg / Nm³, SO3 concentration is below 5 mg / Nm³, and dust concentration is below 5 mg / Nm³. The system is stable and easy to operate, efficiently and synergistically removing SO3, with no secondary pollution such as wastewater or waste residue throughout the process, and no special anti-corrosion treatment is required. The solid byproducts are mainly CaSO3, CaSO4, and a small amount of unreacted Ca(OH)2, which are easy to treat and utilize.

[0145] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0146] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0147] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas, characterized in that, It includes a defluorination and dust removal integrated device (300), an absorption and adsorption device, and a bag filter (600) connected in sequence. The defluorination and dust removal integrated device (300) is used to defluorinate and remove dust from the input electrolytic aluminum flue gas (100); The absorption and adsorption device includes a high-temperature absorption and adsorption mechanism (400) and a low-temperature absorption and adsorption mechanism (500) arranged in parallel. The inlet ends of the high-temperature absorption and adsorption mechanism (400) and the low-temperature absorption and adsorption mechanism (500) are connected to the outlet end of the defluorination and dust removal integrated device (300). The high-temperature absorption and adsorption mechanism (400) and the low-temperature absorption and adsorption mechanism (500) are configured to automatically distribute the electrolytic aluminum flue gas (100) flowing out of the defluorination and dust removal integrated device (300) to the corresponding high-temperature absorption and adsorption mechanism (400) or the low-temperature absorption and adsorption mechanism (500) for desulfurization treatment based on the temperature and / or water dew point of the electrolytic aluminum flue gas (100) flowing out of the defluorination and dust removal integrated device (300). The inlet end of the bag filter (600) is connected to the outlet ends of the high-temperature absorption and adsorption mechanism (400) and the low-temperature absorption and adsorption mechanism (500) respectively, and is used to remove dust from the electrolytic aluminum flue gas (100) after desulfurization treatment.

2. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, It also includes a flue gas inlet pipe (200), one end of which is connected to the electrolytic aluminum flue gas (100), and the other end is connected to the inlet end of the defluorination and dust removal integrated device (300).

3. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 2, characterized in that, The integrated defluorination and dust removal device (300) has multiple inlets at its inlet end; The smoke inlet duct (200) includes a main smoke duct and a plurality of branch smoke ducts connected to the main smoke duct, and one of the inlets is connected to one of the branch smoke ducts.

4. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 3, characterized in that, It also includes a first injection assembly (201) communicating with the smoke inlet duct (200), the first injection assembly (201) being configured to inject aluminum oxide into the smoke inlet duct (200); The first injection assembly (201) includes a first injection body and a first injection pipe. One end of the first injection pipe is connected to the first injection body, and the other end is connected to the smoke inlet pipe (200).

5. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 4, characterized in that, The first injection pipeline includes a first injection main pipeline and a plurality of first injection branch pipelines. One end of each first injection branch pipeline is connected to the first injection main pipeline, and the other end is connected to each of the branch flues in a corresponding manner, and / or... The first injection branch pipe is equipped with a regulating valve for adjusting the flow rate of the electrolytic aluminum flue gas (100).

6. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, Also includes: High-temperature flue gas conditioning component (401) is disposed between the defluorination and dust removal integrated device (300) and the high-temperature absorption and adsorption mechanism (400). A first temperature detection component is provided at the inlet end of the high-temperature absorption and adsorption mechanism (400), a second temperature detection component and a first humidity detection component are provided at the outlet end of the high-temperature absorption and adsorption mechanism (400), and the first temperature detection component, the second temperature detection component and the first humidity detection component are all electrically connected to the high-temperature flue gas conditioning component (401).

7. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, Also includes: Low-temperature flue gas conditioning component (501) is disposed between the defluorination and dust removal integrated device (300) and the low-temperature absorption and adsorption mechanism (500). A third temperature detection component is provided at the inlet end of the low-temperature absorption and adsorption mechanism (500), and a fourth temperature detection component and a second humidity detection component are provided at the outlet end of the low-temperature absorption and adsorption mechanism (500). The third temperature detection component, the fourth temperature detection component and the second humidity detection component are all electrically connected to the low-temperature flue gas conditioning component (501).

8. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, It also includes a second spraying assembly (402) connected to the high-temperature absorption and adsorption mechanism (400), the second spraying assembly (402) being used to spray a highly active calcium-based or sodium-based absorbent; The second spray assembly (402) includes a second spray body and multiple second spray pipes. One end of the second spray pipe is connected to the second spray body, and the other end is connected to the high-temperature absorption and adsorption mechanism (400).

9. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, It also includes a third spraying assembly (502) connected to the low-temperature absorption and adsorption mechanism (500), the third spraying assembly (502) being used to spray sodium-based absorbent.

10. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, It also includes a humidification and activation component (503), which is connected to the low-temperature absorption and adsorption mechanism (500).

11. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, It also includes an intermediate flue (700), one end of which is connected to the high-temperature absorption and adsorption mechanism (400) and the low-temperature absorption and adsorption mechanism (500) respectively, and the other end is connected to the bag filter dust collector (600). A circulating material pipeline (800) is also provided between the bag filter dust collector (600) and the low-temperature absorption and adsorption mechanism (500).

12. The dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas according to claim 1, characterized in that, It also includes a smoke outlet duct (900), one end of which is connected to the outlet end of the bag filter (600), and the other end is connected to the chimney (1000); An induced draft fan (901) is also installed on the smoke outlet duct (900).

13. A method for dry desulfurization, defluorination, and dust removal of electrolytic aluminum flue gas, applied to the dry desulfurization, defluorination, and dust removal system for electrolytic aluminum flue gas as described in any one of claims 1-12, characterized in that, Includes the following steps: S100: Perform defluorination and dust removal treatment on the electrolytic aluminum flue gas (100) to reduce the concentration of fluoride and dust in the electrolytic aluminum flue gas (100); S200: Based on the temperature and / or water dew point of the treated electrolytic aluminum flue gas (100), the electrolytic aluminum flue gas (100) is distributed to a parallel high-temperature absorption and adsorption mechanism (400) and / or a low-temperature absorption and adsorption mechanism (500), and the electrolytic aluminum flue gas (100) is subjected to desulfurization treatment in the high-temperature absorption and adsorption mechanism (400) and the low-temperature absorption and adsorption mechanism (500), respectively. S300: The electrolytic aluminum flue gas (100) flowing out from the high-temperature absorption and adsorption mechanism (400) and the low-temperature absorption and adsorption mechanism (500) is combined and then subjected to bag filter dust removal treatment, so that the sulfide concentration in the electrolytic aluminum flue gas (100) is within the first preset threshold, the fluoride concentration is within the second preset threshold, and the dust concentration is within the third preset threshold.

14. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 13, characterized in that, In step S100, alumina is sprayed into the inlet of the defluorination and dust removal integrated device (300). The molar ratio of the injected alumina to the hydrogen fluoride in the electrolytic aluminum flue gas (100) is controlled to be 0.2-0.

5.

15. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 13, characterized in that, Step S200 specifically includes the following steps: S201: Monitor the temperature and humidity of the electrolytic aluminum flue gas (100) flowing out of the integrated defluorination and dust removal unit (300); S202: When the temperature of the electrolytic aluminum flue gas (100) is higher than the fourth preset threshold, the proportion of flue gas allocated to the high-temperature absorption and adsorption mechanism (400) is increased; S203: When the temperature of the electrolytic aluminum flue gas (100) is lower than the fifth preset threshold, the proportion of flue gas allocated to the low-temperature absorption and adsorption mechanism (500) is increased.

16. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 13, characterized in that, In step S200, a highly active calcium-based or sodium-based absorbent is sprayed into the high-temperature absorption and adsorption mechanism (400), and the molar ratio of the sprayed active calcium-based or sodium-based absorbent to the sulfides in the electrolytic aluminum flue gas (100) is controlled to be 1.2-1.

4.

17. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 16, characterized in that, The BET specific surface area of ​​the highly active calcium-based or sodium-based absorbent is not less than 30 m² / g.

18. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 13, characterized in that, Step S200 includes: The low-temperature absorption and adsorption mechanism (500) is subjected to humidification and cooling treatment so that the temperature of the electrolytic aluminum flue gas (100) is more than 5°C higher than its water dew point temperature. A calcium-based absorbent is injected into the humidified and cooled electrolytic aluminum flue gas (100); The molar ratio of the injected calcium-based absorbent to sulfur in the electrolytic aluminum flue gas (100) is controlled to be 1.3-1.

6.

19. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 18, characterized in that, The BET specific surface area of ​​the calcium-based absorbent is not less than 20 m² / g.

20. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 13, characterized in that, Step S300 includes: The temperature of the electrolytic aluminum flue gas (100) entering the bag filter (600) is controlled to be more than 15°C above its water dew point temperature; The electrolytic aluminum flue gas (100) is passed into a bag filter (600) for filtration; The dust collected by the bag filter (600) is collected, and a portion of the dust is returned to the low-temperature absorption and adsorption mechanism (500) for recycling.

21. The dry desulfurization, defluorination, and dust removal method for electrolytic aluminum flue gas according to claim 13, characterized in that, The first preset threshold is 5 mg / Nm 3 The second preset threshold is 0.5 mg / Nm³. 3 The third preset threshold is 5 mg / Nm 3 .

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