A comprehensive defluorination device for electrolytic aluminum production

Abstract

The utility model relates to an electrolytic aluminium production comprehensive defluorination device, including electrolytic cell 30, collector 40 and raw material alumina conveying device 50 are equipped with primary defluorination channel 10 and secondary defluorination channel 20, primary defluorination channel 10 connects electrolytic cell's flue 31 and collector 40, and raw material alumina is transported to primary defluorination reactor 11. Secondary defluorination channel 20 connects electrolytic cell's flue 31 and collector 40, and fluorine-containing alumina is transported to secondary defluorination reactor 21. The utility model has the advantages that: raw material alumina and fluorine-containing alumina are through different adsorption reaction channels to adsorb fluorine-containing flue gas and purify, can flexibly adjust the process of defluorination treatment, fully utilizes the adsorption efficiency of raw material alumina, reduces the dosage and aluminium circulation frequency of circulating oxidation, reduces the breakage rate of alumina raw material, realizes the sufficient defluorination of fluorine-containing flue gas, and is favorable for the production of electrolytic aluminium.

Description

Technical Field

[0001] This utility model relates to industrial flue gas treatment devices, and more particularly to a comprehensive defluorination device for electrolytic aluminum production. Background Technology

[0002] In the electrolytic aluminum production process, the harmful fumes containing hydrogen fluoride (HF) generated by the electrolytic cells are collected by a sealed fume hood and then converge into the main fume ducts on both sides of the electrolysis workshop. From there, the fumes flow into the defluorination reactor at the front of the defluorination bag filter for adsorption and defluorination purification. Fluorine is a necessary component for electrolytic aluminum production, and alumina is both a raw material and a defluorinating agent used in the defluorination process. The fluorinated alumina after the adsorption reaction enters the alumina silo for use in electrolytic aluminum production, thus achieving the recycling of fluorine. However, the amount of raw alumina (alumina that has not undergone the defluorination adsorption reaction, or "fresh alumina") is limited. Excessive use of raw alumina for defluorination adsorption will result in too much raw material entering the alumina silo, exceeding the capacity of the electrolytic cells and the volume of the alumina silo, leading to waste and environmental pollution. Therefore, when the amount of raw alumina is insufficient to meet the defluorination requirements, a portion of the fluorinated alumina needs to be recycled to achieve the desired defluorination. However, alumina exhibits a high breakage rate during repeated cycles, which is detrimental to the production process of the electrolytic cell.

[0003] In existing technologies, conventional defluorination reactors use a single-stage feeding method for alumina. Raw alumina and fluorinated alumina are simultaneously added to a pipeline reactor to undergo an adsorption reaction with the fluorinated gas, and then both enter the dust collector housing for gas-solid separation via filter bags. The separated gas is then discharged into the atmosphere through a chimney by a fan. The drawback of this existing technology is that the simultaneous addition of raw alumina and fluorinated alumina to the defluorination reactor results in an excessive amount of material entering the flue gas system instantaneously. This causes severe equipment wear, high resistance in the flue gas system, and uneven flow field, reducing the defluorination adsorption efficiency of the raw alumina (fresh alumina), increasing the amount and number of cycles required for the fluorinated alumina, and increasing the breakage rate of the alumina raw material. Utility Model Content

[0004] The purpose of this invention is to propose a comprehensive defluorination device for electrolytic aluminum production, thereby improving the treatment process of fluorine-containing flue gas from electrolytic aluminum production.

[0005] To achieve the above objectives, the technical solution of this utility model is: a comprehensive defluorination device for electrolytic aluminum production, comprising an electrolytic cell 30, a collector 40, and a raw material alumina conveying device 50, and equipped with a primary defluorination channel 10 and a secondary defluorination channel 20. The primary defluorination channel 10 connects the exhaust pipe 31 of the electrolytic cell and the collector 40, and is equipped with a primary defluorination reactor 11. The raw material alumina conveying device 50 conveys raw material alumina 51 to the primary defluorination reactor 11. The secondary defluorination channel 20 connects the exhaust pipe 31 of the electrolytic cell and the collector 40, and is equipped with a secondary defluorination reactor 21. The collector 40 conveys fluorinated alumina 41 to the secondary defluorination reactor 21.

[0006] Furthermore, in order to enhance the adsorption and defluorination effect of fluorine-containing alumina, the collector is connected to the swirling diffusion reactor 60, the secondary defluorination channel 20 is connected to the inlet of the swirling diffusion reactor, and the outlet of the swirling diffusion reactor is connected to the collector.

[0007] Furthermore, in order to increase the mixing time and mixing effect of flue gas and fluorinated alumina, the swirling diffusion reactor 60 is provided with a swirling plate 61, through which the gas flow from the secondary defluorination channel 20 swirls and flows into the collector.

[0008] Furthermore, in order to ensure that the airflow is evenly distributed in the collector and improve the adsorption and defluorination effect of the raw material alumina, the collector 40 is provided with a flow equalization diffuser 12. The flow equalization diffuser 12 is connected to the primary defluorination channel 10, and the airflow from the primary defluorination channel 10 is evenly diffused into the collector through the flow equalization diffuser 12.

[0009] Furthermore, a preferred defluorination reactor is one in which the primary defluorination reactor 11 and the secondary defluorination reactor 21 are tubular reactors, wherein the tubular reactor is provided with a constricted tube and an alumina nozzle is provided around the constricted tube.

[0010] Furthermore, in order to recycle fluorinated alumina, the lower end of the collector 40 is connected to the fluorinated alumina output channel 47. The fluorinated alumina output channel is connected to the secondary defluorination reactor 21 and the alumina silo 42 respectively through a three-way regulating valve. The alumina silo 42 supplies fluorinated alumina to the electrolytic cell 30.

[0011] Furthermore, in order to collect fluorine-containing alumina and purify the exhaust gas, a bag filter 43 is provided on the upper part of the collector 40, and the air outlet of the collector is connected to the exhaust fan 44.

[0012] Furthermore, in order to comprehensively control the operation of the defluorination device, a primary defluorination channel regulating valve 13 is provided at the front end of the primary defluorination reactor 11, and a secondary defluorination channel regulating valve 22 is provided at the front end of the secondary defluorination reactor 21.

[0013] Furthermore, in order to achieve a higher flue gas defluorination capacity, the integrated defluorination device for electrolytic aluminum production is equipped with multiple parallel primary defluorination channels 10.

[0014] The beneficial effects of this invention are: by using raw alumina and fluorinated alumina through different adsorption reaction channels to adsorb and defluorinate fluorinated flue gas, the defluorination process can be flexibly adjusted, making full use of the adsorption efficiency of raw alumina, reducing the amount of circulating oxidation and the number of aluminum cycles, reducing the alumina raw material breakage rate, achieving full defluorination of fluorinated flue gas, and facilitating the production of electrolytic aluminum.

[0015] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a system diagram of this utility model;

[0017] Figure 2 This is a system diagram of the present invention, which has multiple primary defluorination channels. Detailed Implementation

[0018] Example 1:

[0019] like Figure 1 An integrated defluorination device for electrolytic aluminum production includes an electrolytic cell 30, a collector 40, and a raw material alumina conveying device 50.

[0020] Electrolytic cell 30 produces electrolytic aluminum, and during the production process, it emits flue gas containing hydrogen fluoride 32. The flue gas containing hydrogen fluoride 32 is discharged through exhaust pipe 31.

[0021] The integrated defluorination device for electrolytic aluminum production in this embodiment is equipped with a primary defluorination channel 10 and a secondary defluorination channel 20.

[0022] The primary defluorination channel 10 connects the exhaust pipe 31 of the electrolytic cell and the collector 40. The primary defluorination channel includes a primary defluorination reactor 11, which feeds raw alumina 51 into the fluorinated flue gas 32, mixing the alumina 51 with the flue gas before sending it to the collector 40. The primary defluorination reactor 11 is a tubular reactor with a constricted tube. Alumina nozzles are positioned around the constricted tube. The airflow passing through the constricted tube generates a Venturi effect, increasing the flow velocity and decreasing the pressure. The reduced pressure facilitates the alumina nozzles spraying alumina into the primary defluorination reactor 11, while the increased flow velocity allows for better mixing of the alumina with the airflow, improving the defluorination reaction efficiency.

[0023] The raw alumina conveying device 50 delivers raw alumina 51 to the primary defluorination reactor 11. The raw alumina conveying device 50 is a pressurized conveying device for the raw alumina, causing the raw alumina to be sprayed into the primary defluorination reactor 11 through an alumina nozzle. The raw alumina inlet end of the primary defluorination reactor 11 is equipped with a raw alumina regulating valve 53.

[0024] A primary defluorination channel regulating valve 13 is provided on the primary defluorination channel 10 at the front end of the primary defluorination reactor 11. The primary defluorination channel regulating valve 13 regulates the gas flow rate of the primary defluorination channel. The primary defluorination channel regulating valve 13 can be a butterfly valve.

[0025] The collector 40 is equipped with a flow equalization diffuser 12, which is connected to the primary defluorination channel 10. The airflow from the primary defluorination channel 10 is evenly diffused into the collector through the flow equalization diffuser 12. In this embodiment, the flow equalization diffuser 12 adopts an inverted conical airflow guide plate to make the airflow evenly distributed in the collector 40.

[0026] The alumina reacts with the fluorinated flue gas to become fluorinated alumina within the collector 40. A bag filter 43 is installed at the top of the collector 40, and the fluorinated alumina filtered by the bag filter is discharged from the bottom of the collector. The purified air 46 filtered by the bag filter is discharged from the outlet 45 of the collector, which is connected to an exhaust fan 44. The purified air 46 is discharged through the exhaust fan 44.

[0027] The lower end of collector 40 is connected to a fluorinated alumina output channel 47. The fluorinated alumina output channel is equipped with a three-way regulating valve 48. One output of the three-way regulating valve 48 is sent to an alumina silo 42, which then supplies fluorinated alumina to the electrolytic cell 30 as raw material for the production of electrolytic aluminum. Another output of the three-way regulating valve 48 is sent to the secondary defluorination reactor 21 in the secondary defluorination channel 20.

[0028] The inlet of the secondary defluorination channel 20 is connected to the exhaust pipe 31 of the electrolytic cell, the collector 40 is connected to a swirling diffusion reactor 60, the secondary defluorination channel 20 is connected to the inlet of the swirling diffusion reactor, and the outlet of the swirling diffusion reactor is connected to the collector.

[0029] The secondary defluorination channel 20 is equipped with a secondary defluorination reactor 21. In this embodiment, the secondary defluorination reactor 21 is a pipeline reactor identical to the primary defluorination reactor 11. The collector 40 supplies fluorinated alumina 41 to the secondary defluorination reactor 21. The secondary defluorination reactor 21 is equipped with an alumina nozzle, and the fluorinated alumina output channel 47 from the collector 40 is connected to the alumina nozzle of the secondary defluorination reactor 21. The fluorinated alumina is input into the secondary defluorination reactor 21 through the alumina nozzle, causing the fluorinated alumina 41 to mix with the fluorinated flue gas 32. The gas flow output from the secondary defluorination reactor 21 enters the swirling diffusion reactor 60.

[0030] A secondary defluorination channel regulating valve 22 is provided on the secondary defluorination channel 20 at the front end of the secondary defluorination reactor 21. The secondary defluorination channel regulating valve 22 regulates the gas flow rate of the secondary defluorination channel. The secondary defluorination channel regulating valve 22 can be a butterfly valve.

[0031] The swirling diffusion reactor 60 is equipped with a swirling plate 61. The lower end of the swirling diffusion reactor 60 is equipped with a ramp that connects to the collector 40. The gas flow from the secondary defluorination channel 20 flows in a swirling motion through the swirling plate 61 and then enters the collector 40, where it merges with the gas flow from the primary defluorination channel 10.

[0032] The working process of the integrated defluorination unit in electrolytic aluminum production is as follows: Hydrogen fluoride-containing flue gas 32 generated by the electrolytic cell is discharged through the exhaust pipe 31. The hydrogen fluoride flue gas 32 enters the primary defluorination reactor 11 via the primary defluorination channel 10. The primary defluorination channel regulating valve 13 adjusts the flow rate into the primary defluorination reactor 11 to prevent overload and blockage. Inside the primary defluorination reactor 11, the hydrogen fluoride-containing flue gas 32 mixes with the raw material alumina 51, resulting in an adsorption reaction. The hydrogen fluoride in the flue gas is absorbed by the raw material alumina. The flue gas 33 passing through the primary defluorination reactor 11 still contains a small amount of hydrogen fluoride. The flue gas mixed with the raw material alumina enters the collector 40 through the flow equalization diffuser 12. During the flow of the flue gas, the raw material alumina continues to undergo an adsorption reaction with hydrogen fluoride. The absorption of hydrogen fluoride is completed in the collector 40, thus removing hydrogen fluoride from the flue gas. The raw material alumina that has absorbed hydrogen fluoride becomes fluorinated alumina 41. After passing through the bag filter 43, the granular fluorinated alumina 41 is filtered out and discharged from the lower end of the collector 40 through the fluorinated alumina output channel 47. The fluorinated alumina 41 is then transported to the alumina silo 42 as a raw material for the production of electrolytic aluminum. Since the fluorinated alumina at this stage still has the function of further defluorination, some of the fluorinated alumina can also be recycled as a defluorinating agent. The filtered purified air 46 is discharged from the collector outlet 45 and discharged through the exhaust fan 44.

[0033] When the hydrogen fluoride content in the flue gas is high, the alumina 51 from the primary defluorination channel 10 alone cannot meet the defluorination requirements, necessitating the activation of the secondary defluorination channel 20. The three-way regulating valve 48 is adjusted to allow some of the fluorinated alumina 41 to enter the secondary defluorination reactor 21 through the fluorinated alumina output channel 47. Simultaneously, the gas flow rate in the secondary defluorination channel is regulated by the secondary defluorination channel regulating valve 22. Within the secondary defluorination reactor 21, the hydrogen fluoride-containing flue gas 32 mixes with the fluorinated alumina 41, resulting in an adsorption reaction where the hydrogen fluoride in the flue gas is absorbed by the fluorinated alumina. Since the absorption capacity of the fluorinated alumina is less than that of the primary alumina, a swirling diffusion reactor 60 is used to enhance the absorption efficiency of the fluorinated alumina. The swirling diffusion reactor 60 is equipped with a swirl plate 61, which causes the gas flow from the secondary defluorination channel 20 to swirl and flow through the swirl plate 61, increasing the mixing time and effect between the flue gas and the fluorinated alumina, thereby improving the absorption efficiency of the fluorinated alumina. Appropriately reducing the amount of fluorinated alumina and the number of alumina cycles can lower the breakage rate. The swirl diffusion reactor 60, with its swirl plate 61 structure, can facilitate smoother airflow and reduce breakage of the fluorinated alumina.

[0034] The flue gas enters the collector 40 through the cyclone diffusion reactor 60, where it merges with the gas flow from the primary defluorination channel 10. Hydrogen fluoride is absorbed in the collector 40, thus removing it from the flue gas. Afterward, it is filtered by the bag filter 43 and discharged from the lower end of the collector 40 through the fluorinated alumina outlet channel 47.

[0035] This utility model separates the defluorination process for raw alumina and fluorine-containing alumina, allowing for flexible adjustment of the defluorination process. It fully utilizes the strong defluorination reaction efficiency of raw alumina, improves the purification effect of fluorine-containing flue gas, reduces the number of alumina cycles, lowers the alumina breakage rate, and helps improve the production efficiency of electrolytic aluminum.

[0036] Example 2:

[0037] like Figure 2 An integrated defluorination device for electrolytic aluminum production is described in this embodiment, which is a supplement to Embodiment 1.

[0038] Since the defluorination capacity of a single primary defluorination reactor 11 is limited, in this embodiment, multiple primary defluorination channels 10 are connected in parallel. Each primary defluorination channel 10 is equipped with a primary defluorination reactor 11, a primary defluorination channel regulating valve 13, and a flow equalization diffuser 12.

[0039] For large-scale electrolytic aluminum production, a high level of flue gas defluorination capacity is required. Multiple primary defluorination channels can be used to meet the requirements of flue gas defluorination and purification.

Claims

1. A comprehensive defluorination device for electrolytic aluminum production, comprising an electrolytic cell (30), a collector (40), and a raw material alumina conveying device (50), characterized in that, The electrolytic cell is provided with a primary defluorination channel (10) and a secondary defluorination channel (20). The primary defluorination channel (10) is connected to the exhaust pipe (31) and the collector (40) of the electrolytic cell. The primary defluorination channel is provided with a primary defluorination reactor (11). The raw material alumina conveying device (50) conveys raw material alumina (51) to the primary defluorination reactor (11). The secondary defluorination channel (20) is connected to the exhaust pipe (31) and the collector (40) of the electrolytic cell. The secondary defluorination channel (20) is provided with a secondary defluorination reactor (21). The collector (40) conveys fluorinated alumina (41) to the secondary defluorination reactor (21).

2. The integrated defluorination device for electrolytic aluminum production according to claim 1, characterized in that, The collector is connected to the swirling diffusion reactor (60), the secondary defluorination channel (20) is connected to the inlet of the swirling diffusion reactor, and the outlet of the swirling diffusion reactor (60) is connected to the collector (40).

3. The integrated defluorination device for electrolytic aluminum production according to claim 2, characterized in that, The swirling diffusion reactor (60) is equipped with a swirling plate (61), through which the gas flow from the secondary defluorination channel (20) swirls and flows into the collector (40).

4. The integrated defluorination device for electrolytic aluminum production according to claim 1, characterized in that, The collector (40) is provided with a flow equalization diffuser (12), which is connected to the primary defluorination channel (10). The gas flow from the primary defluorination channel (10) is evenly diffused into the collector (40) through the flow equalization diffuser (12).

5. The integrated defluorination device for electrolytic aluminum production according to claim 1, characterized in that, The primary defluorination reactor (11) and the secondary defluorination reactor (21) are pipeline reactors, each equipped with a constricted tube and an alumina nozzle surrounding the constricted tube.

6. The integrated defluorination device for electrolytic aluminum production according to claim 1, characterized in that, The lower end of the collector (40) is connected to the fluorinated alumina output channel (47), which is connected to the secondary defluorination reactor (21) and the alumina silo (42) respectively through a three-way regulating valve (48). The alumina silo (42) supplies fluorinated alumina to the electrolytic cell (30).

7. The integrated defluorination device for electrolytic aluminum production according to claim 1, characterized in that, The upper part of the collector (40) is provided with a bag filter (43), and the air outlet of the collector is connected to a smoke exhaust fan (44).

8. The integrated defluorination device for electrolytic aluminum production according to claim 1, characterized in that, The primary defluorination reactor (11) is equipped with a primary defluorination channel regulating valve (13) at its front end, and the secondary defluorination reactor (21) is equipped with a secondary defluorination channel regulating valve (22) at its front end.

9. The integrated defluorination device for electrolytic aluminum production according to claim 1, characterized in that, The integrated defluorination unit for electrolytic aluminum production is equipped with multiple parallel primary defluorination channels (10).

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