A collection device and method for high-temperature anode gas from an aluminum electrolytic cell

Abstract

A collection device and method for high-temperature anode gas from an aluminum electrolytic cell includes an outer steel sleeve. The thinner lower part of the outer steel sleeve passes through a hole in the horizontal tank cover of the electrolytic cell, and the thicker upper part of the outer steel sleeve rests on the horizontal tank cover. A steel cap is provided at the upper opening of the outer steel sleeve. An inner steel sleeve is provided inside the outer steel sleeve, and a cylinder is provided inside the inner steel sleeve. A cylinder hole with a vertical cylindrical surface is opened at the end of the thinner lower part of the cylinder near the thicker upper part. The thinner lower parts of the inner and outer steel sleeves are respectively provided with inner steel sleeve holes and outer steel sleeve holes. A short steel pipe is welded to the hole of the outer steel sleeve. The short steel pipe is connected to the gas collection pipe inside the electrolytic cell located under the horizontal tank cover. The gas collection pipe inside each electrolytic cell is connected to the gas collection pipe outside the electrolytic cell. The alumina dust collected by this invention is greatly reduced, and the cylinder, inner steel sleeve and outer steel sleeve are easy to disassemble and maintain.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and emission reduction technology, and specifically relates to a collection device and method for high-temperature anode gas in aluminum electrolysis cells. Background Technology

[0002] Aluminum is produced using the cryolite-alumina molten salt electrolysis method. During the aluminum electrolysis process, aluminum is generated at the cathode and CO2 is generated at the anode. Some of the anode gas CO2 reacts with some of the aluminum dissolved in the cryolite electrolyte to generate CO. Therefore, the anode gas produced in the aluminum electrolysis cell is a mixture of CO2 and CO, with CO2 accounting for 80%-90% and CO accounting for 10-20%. Approximately 1.26 tons of anode gas are generated for every ton of metallic aluminum produced during electrolysis. The anode gas in the aluminum electrolysis cell also contains small amounts of highly greenhouse gas compounds such as CF4 and C2F6.

[0003] For a single electrolytic aluminum plant with an annual output of 1 million tons, the annual emission of anode gas is around 1.2 million tons. Therefore, from an environmental protection perspective, it is very necessary to collect and treat the anode gas generated by the electrolytic aluminum plant. At present, with the development of technology, people have begun to look for ways to treat CO2 gas, such as using CO2 to synthesize starch and methanol.

[0004] During electrolysis, the electrolyte temperature is between 940-960℃. Therefore, the temperature of the anode gas escaping from the electrolytic cell should also be between 940-960℃. The heat carried away from the electrolytic cell is equivalent to an energy consumption of about 500 kWh / t-Al per ton of aluminum. The calorific value of CO combustion in the anode gas is equivalent to an energy consumption of about 600 kWh / t-Al per ton of aluminum. The sum of the two is about 1100 kWh / t-Al, which has great heat recovery value from an energy-saving perspective.

[0005] From the perspective of electrolytic cell operation, the anolyte gas in aluminum electrolytic cells is mostly ejected from the shell-breaking and feeding port. The diameter of the shell-breaking and feeding hammer in aluminum electrolytic cells is generally around Φ90~150mm. Before feeding, the shell-breaking hammer moves from top to bottom, knocking down the electrolyte crust and covering alumina powder at the feeding port. Then, about 2kg of alumina powder is sprinkled on top of this hole. During this process, some anolyte gas is also ejected, carrying away some alumina powder and increasing alumina consumption. On the other hand, the escape of anolyte gas is hindered by the alumina powder on the upper surface, making it difficult for the anolyte gas to escape. Therefore, some anolyte gas always escapes from outside the feeding port, which creates a certain degree of positive pressure for the anolyte gas in the cavity on the surface of the electrolyte in the electrolytic cell. This also causes the anolyte gas to stay in the electrolyte melt for a longer time, increasing aluminum loss and reducing current efficiency.

[0006] Patent CN114855223A discloses a method for collecting high-temperature anode gas from an aluminum electrolytic cell. This method involves installing a gas collecting hood below the shell-breaking and feeding hammer, specifically above the shell-breaking and feeding ignition point, to collect the anode gas. The disadvantages of this method are: 1. The collected anode gas contains a large amount of alumina dust; 2. The alumina feeding pipe is prone to clogging; 3. The shell-breaking hammer has a short service life due to operating at 930-950℃; 4. It is difficult to disassemble and maintain. Summary of the Invention

[0007] The purpose of this invention is to provide a collection device and method for high-temperature anode gas in aluminum electrolysis cells. The anode gas collected by the collection device and method of this invention does not contain alumina dust. Its biggest feature is that the anode gas collection device and the shell-breaking and feeding device are separate, and the shell-breaking and feeding does not affect the collection of anode gas. The collected anode gas pressure is stable and the collection efficiency is high. In addition, the cylinder, inner steel sleeve and outer steel sleeve are easy to disassemble as a whole, and the maintenance is simple.

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

[0009] A collection device for high-temperature anolyte gas from an aluminum electrolytic cell includes a cylindrical body and an outer steel sleeve. The thinner lower portion of the outer steel sleeve passes through a hole in the horizontal tank cover of the electrolytic cell, while the thicker upper portion of the outer steel sleeve rests on the horizontal tank cover and is electrically insulated from it. It is fixedly installed on the horizontal tank cover via a flange and studs on the bottom edge of the thicker upper portion. The upper opening of the outer steel sleeve is configured with a flange structure and a flanged opening with the same diameter as the upper portion of the outer steel sleeve. The steel cap of the flange is sealed using a vacuum gasket. The bottom surface of the steel cap is located below the lifting hole on the upper part of the inner steel sleeve, ensuring it does not interfere with the installation and removal of the refractory material cylinder and the inner steel sleeve assembly. An inner steel sleeve is installed inside the outer steel sleeve, and the inner and outer steel sleeves have the same shape. A cylinder is installed inside the inner steel sleeve, and the outer wall shape of the cylinder is the same as that of the inner steel sleeve. A cylinder hole is opened at the lower, narrower part of the cylinder near the upper, wider part. The inner and outer steel sleeves... The lower, narrower portion of the cylinder has inner and outer steel sleeve holes, which are concentric and coaxial with the cylinder body holes. A short steel pipe is welded to the outer steel sleeve hole, connecting to the gas collecting pipe inside the electrolytic cell located under the horizontal trough cover. The gas collecting pipe inside the electrolytic cell is aligned with the longitudinal direction of the electrolytic cell. The gas collecting pipe inside each electrolytic cell is connected to the main gas collecting pipe outside the flue end trough. The cylinder body, inner steel sleeve, outer steel sleeve, short steel pipe, and the inside of the electrolytic cell are all connected. The gas collecting pipe and the external gas collecting pipe of the electrolytic cell are combined to form a gas collecting device for the anode gas of the aluminum electrolytic cell. The combination of the outer steel sleeve, the inner steel sleeve and the cylinder body of this collecting device is vertically placed in the middle position between the two shell-breaking feeders on the middle seam of the two rows of electrolytic cell anodes in the longitudinal direction of the electrolytic cell. There are four corner-cut anodes around this position. The four corner-cut anodes form a well-like space with a tetrahedral shape. The distance between the middle seams of the two rows of electrolytic cell anodes in the longitudinal direction of the electrolytic cell is 50-150mm.

[0010] The cylinder is composed of a tubular lower part with an opening facing downwards and a solid upper part, with the upper diameter being larger than the lower diameter. The cylinder is made of silicon nitride or silicon nitride combined with silicon carbide.

[0011] There is a 1-6mm gap between the inner diameter of the thinner lower part of the outer steel sleeve and the outer diameter of the thinner lower part of the inner steel sleeve, and the inner diameter of the thicker upper part of the outer steel sleeve is larger than the outer diameter of the thicker upper part of the inner steel sleeve.

[0012] To ensure that the CO gas in the collected anode gas is burned before entering the gas collecting pipe inside the electrolytic cell, the bottom end of the outer steel sleeve of the collecting device can be moved above the alumina powder covering material of the electrolytic cell, at a distance of 50-100mm from the alumina powder covering material; and the gap between the outer steel sleeve and the inner steel sleeve below the steel short pipe should be between 3-6mm, so that the anode gas can be fully burned inside the steel short pipe.

[0013] The height of the thicker part of the inner steel sleeve is higher than the height of the thicker part of the upper part of the cylinder. The inner steel sleeve with 2-4 holes for hoisting is provided on the part of the inner steel sleeve that is higher than the cylinder, so that the tight combination formed by the inner steel sleeve and the cylinder becomes a combination that can be hoisted.

[0014] The bottom ends of the cylinder and the inner steel sleeve are on the same horizontal plane, extending downwards to the height of the upper surface of the residual anode before the aluminum electrolysis cell is replaced, while the bottom end of the outer steel sleeve is located 30-80mm above the bottom end of the inner steel sleeve, and its surroundings are covered with alumina powder.

[0015] The main gas collection pipe outside the tank can collect the anode gas collected by the gas collection pipes inside the electrolytic cells of no less than 8-10 cells; the steel short pipe is equipped with a gate valve on the side near the gas collection pipe inside the electrolytic cells, and a gate valve is also installed at the front end of the gas collection pipe inside the electrolytic cells entering the main gas collection pipe.

[0016] The steel short pipe, the gas collecting pipe inside the electrolytic cell, and the gas collecting pipe outside the electrolytic cell are provided with a high-temperature resistant insulation layer to reduce the heat loss of the anode gas during the collection process.

[0017] The collecting device collects the original anode gas, which is a mixture of CO2 and CO. To allow the CO in the anode gas to burn before collection, several anode gas inlets can be set at a distance of 50-100mm from the alumina powder covering material at the bottom of the assembly consisting of an outer steel sleeve, an inner steel sleeve, and a cylinder. Four to six symmetrical air inlets are opened on the pipe wall at a distance of 80-200mm from the alumina powder covering material on the cylinder, inner steel sleeve, and outer steel sleeve assembly, so that air enters the collected anode gas and burns with the CO gas in the anode gas that has just entered the cylinder to form CO2.

[0018] A collection device for high-temperature anode gas from an aluminum electrolytic cell includes a first steel cylinder with a closed lower end and a flange, and a horizontal tank cover. The first steel cylinder is welded directly below the horizontal tank cover. Several small holes are drilled in the wall of the first steel cylinder to maintain pressure balance between the inside and outside of the cylinder. The inner cavity of the first steel cylinder is either empty or filled with insulation material. A second cylinder is positioned directly below the first steel cylinder. The second cylinder is made of silicon nitride bonded silicon carbide material and is a vertical cylinder with a thicker upper part and a thinner lower part, being solid at the top and hollow at the bottom. A first hole is formed in the hollow part of the second cylinder near the solid part. A third cylinder is coaxially fitted onto the outside of the second cylinder. The third cylinder is made of heat-resistant steel material and is thicker at the top. The third cylinder has a narrow bottom and a flange at the top. The flange at the top of the third cylinder is connected to the flange at the bottom of the first steel cylinder. Heat-resistant insulation and an insulating gasket are installed between the two. The opening on the lower surface of the third cylinder is on the same horizontal plane as the lower surface of the second cylinder and extends downward into the alumina insulation layer of the tank surface, to the upper surface of the anode residue before the electrode replacement, or at a height of 50-100mm below the surface of the residue. A second hole coaxial with the first hole is opened on the cylinder wall of the third cylinder. A short steel pipe coaxial with the second hole is welded to the outside of the third cylinder. The end of the short steel pipe is connected to the gas collecting pipe inside the electrolytic cell. The short steel pipe contains a tube made of silicon nitride or silicon nitride combined with silicon carbide material. The gas collecting pipe inside the electrolytic cell is connected to the main gas collecting pipe outside the flue end tank.

[0019] The steel short pipe is either a single pipe of equal diameter or a split pipe consisting of a thick pipe and a thin pipe. When it is a split pipe, one end of the thick pipe is seamlessly connected to the gas collecting pipe inside the electrolytic cell, and the thin pipe is seamlessly connected to the third cylinder. The other end of the thin pipe is inserted into the thick pipe, and an insulation layer is provided on the outside of the thick pipe and the thin pipe to seal the gap between the thick pipe and the thin pipe.

[0020] The steel short pipe is equipped with a gate valve on the side near the gas collecting pipe inside the electrolytic cell, and a gate valve is also installed at the front end of the gas collecting pipe inside the electrolytic cell entering the main gas collecting pipe.

[0021] A method for collecting high-temperature anode gas from an aluminum electrolytic cell includes the following steps:

[0022] A steel horn-shaped cover is installed on the burner at the aluminum outlet of the electrolytic cell and covered with alumina powder. The steel cover is removed when aluminum is tapped, temperature is measured, or the anode effect is treated. After aluminum tapping, temperature measurement and anode effect treatment are completed, the cover can be put back on immediately. Alternatively, the cover can be left on, but a thick layer of alumina powder is not needed when tapping aluminum, treating the anode effect and temperature measurement.

[0023] During normal aluminum electrolysis production, the original shell-breaking and feeding device and shell-breaking and feeding method of the electrolytic cell are not adjusted. The normal operation of shell-breaking and feeding of the electrolytic cell is to break the shell first and then feed the material. After the alumina powder is broken, it will cover the upper surface of the shell-breaking hole, which will create resistance to the escape of the anode gas.

[0024] The anode gases from several electrolytic cells are collected in the gas collection pipes outside the electrolytic cells and then sent to a gas-fired high-temperature steam boiler or a waste heat steam boiler. In the steam boiler or waste heat boiler, water or other media are converted into high-temperature and high-pressure steam to drive a steam engine to generate electricity. The generated electricity is used to electrolyze sodium hydroxide or sodium chloride aqueous solution to produce hydrogen. The low-temperature anode gas from the boiler is then de-dustened, desulfurized, and defluorinated to produce pure CO2 or a mixture of CO2 and CO. The waste heat is then used to generate hydrogen through electrolysis and synthesize methane.

[0025] The technical effects of this invention are as follows:

[0026] The anode gas collected by the collection device and method of this invention does not contain alumina dust; its biggest feature is that the anode gas collection device and the shell-breaking and feeding device are separate, and the shell-breaking and feeding does not affect the collection of anode gas. The collected anode gas pressure is stable and the collection efficiency is high; it also has the advantages of being easy to disassemble, easy to maintain, and having high gas collection efficiency. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of the inner part of the anode gas collection device of the aluminum electrolytic cell in Embodiment 1 of the present invention, perpendicular to the longitudinal direction of the electrolytic cell.

[0028] Figure 2 This is a schematic diagram and a positional diagram of the inner part of the aluminum electrolytic cell anode gas (CO gas not burned) collection device in Embodiment 1 of the present invention, perpendicular to the transverse direction of the electrolytic cell.

[0029] Figure 3 This is Embodiment 1 of the present invention. Figure 2 Schematic diagram of AA section;

[0030] Figure 4 Example 2 is a cross-sectional view of the inner part of the aluminum electrolytic cell anode gas collection device, which collects CO from the anode gas after combustion, perpendicular to the longitudinal direction of the electrolytic cell.

[0031] Figure 5 A schematic cross-sectional view of the inner part of the aluminum electrolytic cell anode gas collection device in Embodiment 2 of the present invention, which collects the CO in the anode gas after combustion. The cross-section is perpendicular to the transverse direction of the electrolytic cell.

[0032] Figure 6A cross-sectional view of the inner part of the anode gas collection device of the aluminum electrolytic cell in Embodiment 3 of the present invention, perpendicular to the longitudinal direction of the electrolytic cell;

[0033] Figure 7 A schematic diagram and a positional diagram of the inner part of the aluminum electrolytic cell anode gas (CO gas not burned) collection device in Embodiment 3 of the present invention, perpendicular to the transverse direction of the electrolytic cell;

[0034] Figure 8 A cross-sectional view of the inner part of the anode gas collection device of the aluminum electrolytic cell in Embodiment 4 of the present invention, perpendicular to the longitudinal direction of the electrolytic cell;

[0035] 1. Cylinder body; 2. Cylinder body bore; 3. Inner steel sleeve; 4. Inner steel sleeve bore; 5. Outer steel sleeve; 6. Horizontal tank cover; 7. Stud; 8. Steel cap; 9. Outer steel sleeve bore; 10. Steel short pipe; 11. Gas collecting pipe inside the electrolytic cell; 12. Anode; 13. Anode center seam in the electrolytic cell; 14. Lifting hole; 15. Shell-breaking and feeding device; 16. Air inlet; 17. Alumina powder covering material;

[0036] 18-First steel cylinder, 19-Second cylinder, 20-Third cylinder, 21-Thick pipe, 22-Thin pipe, 23-Heat-resistant insulating gasket, 24-Insulation material, 25-Alumina insulation layer. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0038] Example 1

[0039] like Figures 1 to 3 As shown, the anode gas collected by the high-temperature anode gas collection device for aluminum electrolysis described in this embodiment is anode gas containing CO that escapes from the electrolytic cell. In this embodiment, the collection device extends to the upper part of the horizontal tank cover 6.

[0040] A high-temperature anode gas collection device for an aluminum electrolytic cell includes a cylinder 1 made of silicon nitride or silicon nitride combined with silicon carbide, an inner steel sleeve 3, an outer steel sleeve 5, a short steel pipe 10, an inner gas collecting pipe 11 and an outer gas collecting pipe of the electrolytic cell. The cylinder 1 has a larger upper diameter than a lower diameter, and the lower part is hollow with an opening facing downwards while the upper part is solid. A cylinder hole 2 perpendicular to the wall of the cylinder 1 is provided at the top of the lower hollow tubular body. An inner steel sleeve 3 is provided on the outer wall of the cylinder 1. The height of the thicker upper part of the inner steel sleeve 3 is higher than the height of the thicker upper part of the cylinder 1, and the protruding part is provided with 2-4 lifting holes 14 for hoisting, so that the inner steel sleeve 3 and the cylinder 1 are tightly connected to form a hoistable structure. The assembly consists of an inner steel sleeve 3 and an outer steel sleeve 5, which has the same shape as the inner steel sleeve 3. The inner diameter of the thicker upper part of the outer steel sleeve 5 is 10-100 mm larger than the outer diameter of the thicker upper part of the inner steel sleeve 3. The thinner lower part of the outer steel sleeve 5 passes vertically through a hole provided on the horizontal tank cover 6 of the electrolytic cell, so that the thicker upper part of the outer steel sleeve 5 sits on the upper surface of the horizontal tank cover 6 of the electrolytic cell. A heat-resistant insulating washer 23 is installed at the contact point between the surface of the outer steel sleeve 5 and the surface of the horizontal tank cover 6. Then, the outer steel sleeve 5 is fixed to the horizontal tank cover 6 of the electrolytic cell with a stud 7. At the same time, an insulating sleeve is fitted on the screw of the stud 7. The advantage of fixing with a stud is that the outer steel sleeve 5 can be easily removed for further processing. Repairing damage during the electrolysis process involves using a flange on the upper opening of the outer steel sleeve 5, which is connected to a flanged steel cap 8 with the same diameter as the upper part of the outer steel sleeve 5. The connection is achieved through gaskets and studs between the flanges. The height of the steel cap 8 is designed so that its removal does not interfere with the installation and removal of the assembly of the cylinder 1 and the inner steel sleeve 3. The bottoms of the cylinder 1, the inner steel sleeve 3, and the outer steel sleeve 5 are all open. The bottom ends of the cylinder 1 and the inner steel sleeve 3 extend downwards to the same level as the upper surface of the residual electrode before electrode replacement, and their surroundings are covered with alumina powder. The bottom end of the outer steel sleeve 5 is located 30-80mm above the bottom edge of the inner steel sleeve 3. The lower part of the outer steel sleeve 5... The thinner part is also provided with an outer steel sleeve hole 9, which is concentric and has the same diameter as the cylinder hole 2 and inner steel sleeve hole 4 on the wall of the thinner part of the cylinder 1 and inner steel sleeve 3 and is on the same axis. A short steel pipe 10 is welded to the outer steel sleeve hole 9 on the lower part of the outer steel sleeve 5. It is connected to the gas collection pipe 11 in the electrolytic cell, which is located below the horizontal tank cover 6 of the electrolytic cell and is parallel to the longitudinal direction of the electrolyte tank and the horizontal tank cover 6 of the electrolytic cell. The gas collection pipe 11 in the electrolytic cell is covered with an insulating layer and is suspended on one side below the horizontal tank cover 6. The gas collection pipe 11 in the electrolytic cell is connected to the main gas collection pipe (not shown) outside the cell, which is perpendicular to the longitudinal direction of the electrolytic cell.

[0041] A high-temperature anode gas collection device for an aluminum electrolytic cell is assembled from a cylinder 1, an inner steel sleeve 3, an outer steel sleeve 5, a steel short pipe 10, an inner gas collecting pipe 11, and an outer gas collecting pipe, all made of silicon nitride or a combination of silicon nitride and silicon carbide. The assembly of the cylinder 1, inner steel sleeve 3, and outer steel sleeve 5 is vertically positioned, via a horizontal cell cover 6, between two rows of anodes 12 in the longitudinal direction of the aluminum electrolytic cell, between two shell-breaking feeders 15 on the anode seam 13 parallel to the longitudinal direction of the cell. The width of the anode seam 13 between the two rows of anodes 12 is 50-150 mm. At the location of this anode gas collector, the four adjacent anodes are corner-missing anodes, forming a tetrahedral well-like space. The external gas collection pipe of the electrolytic cell, which is perpendicular to the longitudinal direction of the electrolytic cell, can collect the anode gas from the internal gas collection pipes 11 of no less than 6-8 electrolytic cells.

[0042] In order to ensure that the CO gas in the collected anode gas is burned before entering the gas collecting pipe 11 in the electrolytic cell, the bottom end of the outer steel sleeve 5 of the collecting device can be moved above the alumina powder covering material 17 of the electrolytic cell, at a distance of 50-100mm from the alumina powder covering material; and the gap between the outer steel sleeve 5 and the inner steel sleeve 3 can be between 3-6mm, so that the anode gas can be fully burned in the steel short pipe 10.

[0043] A method for collecting high-temperature anode gas from an aluminum electrolytic cell includes the following steps:

[0044] A steel horn-shaped cover is installed on the spark hole at the aluminum outlet of the electrolytic cell. The surrounding area is covered with alumina powder covering material 17. After aluminum is produced, temperature is measured and the anode effect is treated, the horn-shaped steel cover is removed. After aluminum is produced, temperature is measured and the anode effect is treated, the cover is put back on.

[0045] In this embodiment, no adjustments are made to the shell-breaking and feeding device 15 or the feeding system. The shell-breaking and feeding procedure is as follows: the hammer of the shell-breaking machine moves downward to open the shell surface of the shell-breaking and feeding port, and then the shell-breaking and feeding device 15 moves to cover the shell-breaking and feeding port with a certain amount of alumina powder covering material 17.

[0046] The anode gas collected from no less than 6-8 electrolytic cells via the external collection pipe is the original high-temperature anode gas containing CO2, CO, and small amounts of CF4 and C2F6. After collection, it is burned in a combustion boiler to heat the water in the boiler into high-temperature steam, which drives a steam turbine to generate electricity. The generated electricity is used to electrolyze sodium hydroxide or sodium chloride aqueous solution to produce hydrogen. The low-temperature anode gas from the boiler is then de-dustened, desulfurized, and defluorinated to obtain pure CO2 gas. The waste heat is then used to generate hydrogen through electrolysis and synthesize methane.

[0047] Example 2

[0048] like Figure 4 and Figure 5 As shown, the difference between Example 2 and Example 1 is that 4-6 symmetrical air inlets 16 are opened on the pipe wall at a distance of 80-200mm from the alumina powder covering material 17 on the assembly of cylinder 1, inner steel sleeve 3, and outer steel sleeve 5. The oxygen in the air entering from the air inlet 16 burns the CO in the anode gas. At this time, the anode gas collected by the gas collecting device is a higher temperature anode gas containing only CO2, a small amount of nitrogen, and a small amount of sulfur and fluorine.

[0049] Example 3

[0050] The difference between Example 3 and Example 1 is that the collection device provided in this example is located below the horizontal trough cover 6.

[0051] like Figure 6 and Figure 7As shown, a high-temperature anode gas collection device for an aluminum electrolytic cell includes a horizontal tank cover 6. A first steel cylinder 18 with a sealed bottom and a flange is welded directly below the horizontal tank cover 6 at the midpoint of the gap between two rows of anodes in the longitudinal direction of the electrolytic cell. The inner cavity of the first steel cylinder 18 is either empty or filled with lightweight insulation material 24. The wall of the first steel cylinder 18 has several small holes, the purpose of which is to maintain a balance between the gas pressure inside and outside the first steel cylinder 18. A second cylinder 19 is located directly below the first steel cylinder 18. The second cylinder 19 is wider at the top and narrower at the bottom, with a solid upper part and a hollow lower part that opens downwards and is vertically oriented. The second cylinder 19 has a first hole at an angle to the cylinder wall on the side of its hollow portion near the solid body. The second cylinder 19 is made of silicon nitride bonded to silicon carbide. The center lines of the second cylinder 19 and the third cylinder 20 are coaxial with the axis of the square cylinder formed by the four anode chamfered surfaces below the horizontal tank cover 6. The lower surface of the third cylinder 20 is on the same horizontal plane as the lower surface of the second cylinder 19, and its opening extends downwards into the alumina insulation layer 25 of the tank surface, reaching the upper surface of the anode residue before electrode replacement, or a height of 50-100mm below the anode residue surface. The third cylinder 20 is a steel cylinder that is thicker at the top and thinner at the bottom, with a flange at the top opening. The flange at the top opening of the third cylinder 20 is aligned with the lower surface of the first steel cylinder 18. The flanges are connected, and a heat-resistant insulating gasket 23 is provided between the flange of the first steel cylinder 18 and the flange of the third cylinder 20. The connection is secured with insulation using an external insulating sleeve for the studs and insulating gaskets above and below the nuts. A second hole coaxial with the first hole is provided on the third cylinder 20, and the diameter of the second hole is 30-70mm larger than the diameter of the first hole. An internal gas collecting pipe 11 is provided on one side below the horizontal tank cover 6 in the longitudinal direction of the electrolytic cell. An insulating layer is provided outside the internal gas collecting pipe 11. The internal gas collecting pipe 11 is suspended below the horizontal tank cover 6 and insulated from the horizontal tank cover 6. A third hole is provided on the internal gas collecting pipe 11, and the third hole is connected to the second hole on the third cylinder 20 using a... A heat-resistant steel short pipe 10 is seamlessly connected. The steel short pipe 10 is lined with a silicon carbide tube bonded with silicon nitride. A high-temperature resistant gate valve is installed at the end of the steel short pipe 10 near the gas collecting pipe 11 inside the electrolytic cell. This high-temperature resistant gate valve is only closed when the anode is being replaced to prevent air from entering the gas collecting pipe 11 inside the electrolytic cell during the anode replacement. The gas collecting pipe 11 inside the electrolytic cell is closed at the aluminum outlet end of the electrolytic cell and is connected to the main gas collecting pipe in the same direction as the length of the electrolytic plant at the flue end. A gate valve is installed between the main gas collecting pipe and the gas collecting pipe 11 inside each electrolytic cell. It is only closed when the electrolytic cell is undergoing major repair. An insulation layer is installed outside the main gas collecting pipe to keep the collected anode gas warm.

[0052] The anode gas from the gas collection pipes 11 of no less than 8-10 electrolytic cells is collected into the main gas collection pipe and fed into the gas boiler generator set. It can be used for waste heat power generation. The low-temperature anode gas after waste heat power generation can be further desulfurized and defluorinated to obtain pure CO2, which is then used to synthesize methanol with hydrogen produced by electrolysis.

[0053] Example 4

[0054] like Figure 8 As shown, the difference between Example 4 and Example 1 is that the steel short pipe 10 consists of a thick pipe 21 and a thin pipe 22, forming a split pipe body. One end of the thick pipe 21 is seamlessly connected to the third hole of the gas collecting pipe 11 in the electrolytic cell, and one end of the thin pipe 22 is seamlessly connected to the second hole of the third cylinder 20. The other end of the thin pipe 22 is inserted into the other end of the thick pipe 21, which facilitates disassembly and maintenance during major overhauls of the electrolytic cell. The outer side of the thin pipe 22 is wrapped with an insulation layer made of fibrous insulating material, and the gap between the thick pipe 21 and the thin pipe 22 is sealed by the insulation layer.

Claims

1. A high temperature anode gas collection device for an aluminium reduction cell, characterised in that, The outer steel sleeve is provided with an inner steel sleeve, and the inner steel sleeve is provided with the cylinder.

2. A high temperature anode gas collection device for an aluminium reduction cell as claimed in claim 1, characterised in that, The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole.

3. A high temperature anode gas collection device for an aluminum reduction cell as claimed in claim 1, wherein, The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole.

4. A high temperature anode gas collection device for an aluminum reduction cell as claimed in claim 1, characterized in that, The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole.

5. A high temperature anode gas collection device for an aluminum reduction cell as claimed in claim 1, characterized in that, The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole.

6. A high temperature anode gas collection device for an aluminum reduction cell as claimed in claim 1, characterized in that, The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. 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The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel sleeve is provided with an inner steel sleeve hole. The lower thin part of the outer steel sleeve is provided with an outer steel sleeve hole, and the lower thin part of the inner steel 7. A high temperature anode gas collection device for an aluminum reduction cell as claimed in claim 1, characterized in that, The steel short pipe, the electrolytic tank in-gas pipe and the electrolytic tank out-gas pipe are provided with high-temperature resistant heat preservation layer on the outside to reduce heat loss during gas collection.

8. A high temperature anode gas collection device for an aluminium reduction cell, characterised in that, The first steel cylinder is closed at the lower end and has a flange, and a horizontal tank cover is welded to the lower side of the first steel cylinder, a plurality of small holes are drilled in the cylinder wall of the first steel cylinder to facilitate pressure balance between the inside and outside of the first steel cylinder, the inner cavity of the first steel cylinder is empty or filled with heat preservation material, a second cylinder is arranged below the first steel cylinder, the second cylinder is made of silicon nitride combined silicon carbide material, the second cylinder is a vertically oriented cylinder with a thick upper end and a thin lower end, the upper end is a solid body, the lower end is a hollow body with an opening downward, a first hole is formed in the cylinder wall of the hollow part of the second cylinder near the solid body, a third cylinder is coaxially sleeved on the outside of the second cylinder, the third cylinder is made of steel heat-resistant material, the third cylinder is a cylinder with a thick upper end and a thin lower end and a flange at the upper end, the flange at the upper end of the third cylinder is connected to the flange at the lower end of the first steel cylinder, and a heat-resistant and insulating gasket is arranged between the two, the opening on the lower surface of the third cylinder is on the same horizontal plane as the opening on the lower surface of the second cylinder, and extends downward into the alumina heat preservation layer on the tank surface to the upper surface of the anode residual anode before anode replacement, or to a height of 50-100mm below the surface of the residual anode, a second hole coaxial with the first hole is formed in the cylinder wall of the third cylinder, a steel short pipe coaxial with the second hole is welded to the outside of the third cylinder, the end of the steel short pipe is connected to the electrolytic tank in-gas pipe, and a plurality of electrolytic tank in-gas pipes are connected to the total out-gas pipe on the end side of the flue, and a gate valve is arranged on the side of the steel short pipe near the electrolytic tank in-gas pipe, and a gate valve is arranged at the front end of the electrolytic tank in-gas pipe before entering the total out-gas pipe.

9. A high temperature anode gas collection device for an aluminium reduction cell as claimed in claim 8, characterised in that: The steel short pipe is a straight pipe body or a split pipe body composed of a thick pipe and a thin pipe, when it is a split pipe body, one end of the thick pipe is connected to the electrolytic tank in-gas pipe seamlessly, the thin pipe is connected to the third cylinder seamlessly, the other end of the thin pipe is inserted into the thick pipe, and a heat preservation layer is arranged on the outside of the thick pipe and the thin pipe to seal the gap between the thick pipe and the thin pipe.

10. A method of collecting high temperature anode gas from an aluminium reduction cell as claimed in claim 1 or claim 8 characterised in that, The method comprises the following steps: A steel horn-shaped steel cover is arranged on the fire hole at the aluminum outlet end of the electrolytic tank, and the surrounding is covered with alumina powder, the steel cover is removed when aluminum is discharged, temperature is measured or anode effect is handled, the aluminum discharge, temperature measurement and anode effect handling are completed, and then the steel cover is immediately buckled or not buckled, only a thick layer of alumina powder is covered when aluminum is discharged, anode effect is handled and temperature is measured; The anode gas of a plurality of electrolytic tanks is collected in the electrolytic tank out-gas pipe and then sent into a gas high-temperature steam boiler or a waste heat steam boiler, then water is changed into high-temperature high-pressure steam in the steam boiler or the waste heat boiler to drive a steam engine to generate electricity, the generated electricity is used to electrolyze sodium hydroxide or sodium chloride aqueous solution to produce hydrogen, and the low-temperature anode gas from the boiler is desulfurized and defluorinated and then synthesized with the hydrogen produced by electrolysis to produce methanol.

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