A fume treatment system for electrolytic aluminium

Abstract

The application provides a flue gas treatment system for electrolytic aluminum, and aims to solve the technical problem that manufacturers cannot completely remove carbon dioxide in flue gas in the process of electrolytic aluminum in the prior art. The flue gas treatment system, wherein the flue gas sequentially passes through a dust removal device, a desulfurization tower and a defluorination tower, further comprises: a dissolving tank, which is internally provided with a saturated solution of caustic soda, and the bottom of the dissolving tank is provided with crystals of caustic soda; a treatment tank, which is in communication with the dissolving tank through a conveying pipe; a flue gas pipe, one end of which is connected to the defluorination tower and the other end of which extends into the bottom of the treatment tank; a fishing device, one end of which is arranged in the treatment tank and close to the bottom of the treatment tank, and the other end of which is located outside the treatment tank; and wherein one end of the conveying pipe, which is located in the dissolving tank, is submerged in supernatant of the saturated solution of caustic soda. The flue gas treatment system has the advantage that carbon dioxide generated in the process of electrolytic aluminum can be completely converted into sodium carbonate.

Description

TECHNICAL FIELD

[0001] The present application relates to a flue gas emission treatment system in industrial production, in particular to a flue gas treatment system for electrolytic aluminum. BACKGROUND

[0002] The modern electrolytic aluminum industry adopts the cryolite-alumina molten salt electrolysis method. The molten cryolite is the solvent, the alumina is the solute, the carbon body is the anode, and the aluminum liquid is the cathode. After a strong direct current is introduced, an electrochemical reaction occurs at 950-970 DEG C in the electrolytic cell at the two poles, thereby obtaining aluminum at the cathode and generating a large amount of carbon dioxide at the anode. The electrolysis process produces about 1.8 tons of carbon dioxide per ton of electrolytic aluminum.

[0003] Although carbon dioxide is non-toxic and harmless to the human body, it is one of the greenhouse gases, and a large amount of carbon dioxide will affect the ecological environment.

[0004] At present, most electrolytic aluminum manufacturers reduce the carbon dioxide content in the flue gas during the treatment process to ensure that the specified emission standard is met, but they cannot completely remove the carbon dioxide in the flue gas. SUMMARY

[0005] In view of the technical problem in the prior art that manufacturers cannot completely remove carbon dioxide in the flue gas during the electrolytic aluminum process, the present application provides a flue gas treatment system for electrolytic aluminum, which has the advantage of converting all the carbon dioxide generated during the electrolytic aluminum process into sodium carbonate.

[0006] The technical scheme of the present application is:

[0007] A flue gas treatment system for electrolytic aluminum, the flue gas passes through a dust removal device, a desulfurization tower, and a defluorination tower in sequence, and further comprises:

[0008] A dissolution pool containing a saturated solution of caustic soda inside, and the bottom of the dissolution pool has crystals of caustic soda;

[0009] A treatment pool in communication with the dissolution pool through a delivery pipe;

[0010] A flue gas pipe connected to one end of the defluorination tower and extending into the bottom of the treatment pool;

[0011] A fishing device provided in the treatment pool and located close to the bottom of the treatment pool at one end, and located outside the treatment pool at the other end;

[0012] Wherein, one end of the delivery pipe located in the dissolution pool is submerged in the supernatant of the saturated solution of caustic soda.

[0013] Optionally, one end of the delivery pipe located in the treatment pool is close to the top surface of the treatment pool.

[0014] Optionally, the treatment pool has a partition, the conveying pipe and the flue gas pipe are located on one side of the partition, and the retrieval device is located on the other side of the partition.

[0015] Optionally, the treatment pool is provided with a booster device located below the partition.

[0016] Optionally, the dissolving tank is equipped with a stirring device, the stirring end of which is submerged in the caustic soda crystals at the bottom of the dissolving tank.

[0017] Optionally, at least two of the dissolving tanks are connected by a transfer pipe.

[0018] Optionally, the salvage device includes:

[0019] A rotating shaft, with its two ends located on the two side walls inside the treatment tank;

[0020] A salvage motor is located above the treatment pool, and the output shaft of the salvage motor is parallel to the rotating shaft;

[0021] Tracks are fitted onto the rotating shaft and the output shaft of the salvage motor;

[0022] Several retrieval boxes are distributed on the track, and the opening direction of all the retrieval boxes is consistent.

[0023] Optionally, the bottom of the retrieval box is made of gauze.

[0024] Optionally, the rotating shaft and the output shaft of the salvage motor are provided with two tracks, and each track is provided with a plurality of salvage boxes.

[0025] Optionally, one end of the opening of the retrieval box is hinged to the track.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] Firstly, in this technical solution, the flue gas that has passed through the dust removal device, desulfurization tower, and defluorination tower is introduced into the treatment tank. A saturated caustic soda solution is pre-introduced into the treatment tank. The carbon dioxide in the flue gas reacts with the caustic soda solution to produce sodium carbonate and water.

[0028] At the same temperature, because the solubility of sodium carbonate is less than that of caustic soda, solids will appear in the solution after the reaction and precipitate at the bottom of the treatment tank. At the same time, the solution after the reaction is a saturated sodium carbonate solution.

[0029] In the technical solution, the fishing device is arranged to fish up the sodium carbonate solids deposited at the bottom of the treatment tank. The sodium carbonate is recycled by drying and other techniques.

[0030] According to the technical solution, the sodium carbonate with high industrial value can be continuously produced by continuously introducing the saturated solution of caustic soda into the treatment tank to continuously absorb the carbon dioxide in the flue gas. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 is a structural schematic diagram of the present application;

[0033] Figure 2 is a structural schematic diagram of the inside of the treatment tank;

[0034] Figure 3 is a structural schematic diagram of the inside of the treatment tank;

[0035] Figure 4 is a structural schematic diagram of the inside of the treatment tank.

[0036] Reference signs:

[0037] 10, front dissolving tank; 11, water feeding pipe; 12, front stirring device; 13, caustic soda adding pipe.

[0038] 20, rear dissolving tank; 21, transfer pipe; 22, rear stirring device.

[0039] 30, treatment tank; 31, conveying pipe; 32, flue gas pipe; 33, fishing device; 34, boosting device; 35, partition.

[0040] 331, fishing box; 332, output shaft; 333, track; 334, hinge; 335, fishing motor.

[0041] 40, collecting tank; 41, collecting pipe. DETAILED DESCRIPTION

[0042] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and description are considered to be exemplary in nature rather than limiting.

[0043] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the present application is used, or the orientation or positional relationship commonly understood by those skilled in the art, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0044] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0045] Embodiment:

[0046] Referring to Figure 1 A flue gas treatment system for electrolytic aluminum includes a dust removal device, a desulfurization tower, a defluorination tower, a dissolution tank, a treatment tank 30, a flue gas pipe 32, a conveying pipe 31 and a fishing device 33. Specifically:

[0047] The flue gas generated by electrolytic aluminum is sequentially introduced into the dust removal device, the desulfurization tower and the defluorination tower, and sequentially subjected to dust removal treatment and desulfurization and defluorination treatment. Then the flue gas is introduced into the treatment tank 30 to treat the collected carbon dioxide.

[0048] The treatment tank 30 is filled with saturated caustic soda (sodium hydroxide) solution.

[0049] Among them, the dissolution tank is mainly used for dissolving caustic soda, therefore, a water feeding pipe 11 is arranged in the dissolution tank for feeding water into the dissolution tank, and a caustic soda adding pipe 13 is further arranged for adding caustic soda into the dissolution tank. Moreover, the end of the caustic soda adding pipe 13 and the water feeding pipe 11 are close to the bottom of the dissolution tank, and at the same time, it is necessary to ensure that the bottom of the dissolution tank has caustic soda crystals.

[0050] In order to accelerate the dissolution of caustic soda, a stirring device is arranged in the dissolution tank, and the stirring end of the stirring device is also immersed in the caustic soda crystals at the bottom of the dissolution tank.

[0051] The dissolution tank and the treatment tank 30 are communicated by a conveying pipe 31, and the saturated caustic soda solution in the dissolution tank is conveyed into the treatment tank 30 through the conveying pipe 31. One end of the conveying pipe 31 is below the liquid level in the dissolution tank, and this end is in the supernatant of the saturated caustic soda solution, and the other end of the conveying pipe 31 is in the liquid level of the treatment tank 30.

[0052] The flue gas pipe 32 is connected to the treatment tank 30, and the end of the flue gas pipe 32 is close to the bottom of the treatment tank 30.

[0053] One end of the fishing device 33 is also arranged in the treatment tank 30, and this end of the fishing device 33 is close to the bottom of the treatment tank 30, and the other end of the fishing device 33 is outside the treatment tank 30. The fishing device 33 can fish the sodium carbonate crystals at the bottom of the treatment tank 30 to the outside.

[0054] Finally, the generated saturated sodium carbonate solution is transported into the collection tank 40 through the collection pipe 41 for subsequent process.

[0055] The working principle of the embodiment is to convert the carbon dioxide forming greenhouse gas into sodium carbonate with industrial value (sodium carbonate is widely used in light industry, building materials, chemical industry, food industry, metallurgy, textile, petroleum, national defense, medicine, etc.).

[0056] First, the flue gas passing through the dust removal device, desulfurization tower, and defluorination tower is connected to the treatment tank 30, and a saturated caustic soda solution is pre-connected in the treatment tank 30. The carbon dioxide in the flue gas reacts with the caustic soda solution to generate sodium carbonate and water.

[0057] At the same temperature, because the solubility of sodium carbonate is less than that of caustic soda, at about 20℃, 20g of sodium carbonate can be dissolved in 100ml of water, and 109g of sodium hydroxide can be dissolved in 100ml of water. Therefore, solid sodium carbonate will appear in the solution after the reaction and precipitate at the bottom of the treatment tank 30, and the solution after the reaction is a saturated sodium carbonate solution.

[0058] By arranging the fishing device 33, the sodium carbonate solid precipitated at the bottom of the treatment tank 30 is fished up. Then, by using drying and other technologies, the sodium carbonate is recycled, and after the saturated sodium carbonate solution is extracted, the sodium carbonate is extracted by crystallization and other technologies.

[0059] In the embodiment, because the saturated solution of caustic soda is continuously connected to the treatment tank 30, the carbon dioxide in the flue gas can be continuously removed, so that all the carbon dioxide in the flue gas is removed, and sodium carbonate with high industrial value is continuously generated.

[0060] In one specific embodiment:

[0061] The dissolution tank includes a front dissolution tank 10 and a rear dissolution tank 20. The water feeding pipe 11 connects water into the front dissolution tank 10, and then the caustic soda adding pipe 13 adds caustic soda solid into the front dissolution tank 10, and then the front dissolution tank 10 is connected with the rear dissolution tank 20 through the transfer pipe 21. One end of the transfer pipe 21 is submerged in the supernatant of the front dissolution tank 10, and the other end of the transfer pipe 21 is installed close to the bottom of the rear dissolution tank 20.

[0062] A large amount of caustic crystals is deposited at the bottom of the rear dissolving tank 20. In addition, one end of the delivery pipe 31 is submerged in the supernatant of the rear dissolving tank 20. Furthermore, the stirring device comprises a front stirring device 12 and a rear stirring device 22. The stirring end of the front stirring device 12 is arranged in the front dissolving tank 10 and is close to the bottom of the front dissolving tank 10. The stirring end of the rear stirring device 22 is arranged in the rear dissolving tank 20 and is also close to the bottom of the rear dissolving tank 20.

[0063] When the water feeding pipe 11, the caustic soda adding pipe 13 and the delivery pipe 31 are arranged in the same dissolving tank, the caustic soda solution delivered by the delivery pipe 31 is in a non-saturated state, and then the sodium carbonate dissolved in the treatment tank 30 increases, and the generated sodium carbonate solid decreases, which increases the subsequent processing cost. Therefore, in the embodiment, by dividing the dissolving tank into the front dissolving tank 10 and the rear dissolving tank 20, it can be ensured that the solution delivered into the treatment tank 30 is a saturated caustic soda solution.

[0064] In another specific embodiment,

[0065] A partition plate 35 is arranged in the middle of the treatment tank 30, and there is a space between the bottom end of the partition plate 35 and the bottom of the treatment tank 30.

[0066] One side of the partition plate 35 is provided with the flue gas pipe 32 and the delivery pipe 31, and the other side of the partition plate 35 is provided with the fishing device 33. The partition plate 35 is arranged in an inclined manner, and the inclination direction is that the bottom end of the partition plate 35 inclines to the side of the flue gas pipe 32 and the delivery pipe 31, and the top end of the partition plate 35 inclines to the side of the fishing device 33, and the fishing device 33 also inclines in the same direction as the partition plate 35.

[0067] In addition, the bottom of the treatment tank 30 is also inclined, and the side of the bottom of the treatment tank 30 close to the flue gas pipe 32 and the delivery pipe 31 inclines to the top of the treatment tank 30, and the other side of the bottom of the treatment tank 30 inclines to the side away from the top of the treatment tank 30, so that most of the sodium carbonate solids accumulated at the bottom of the treatment tank 30 are at the bottom of the fishing device 33, facilitating fishing.

[0068] In order to promote the sodium carbonate in the treatment tank 30 to move to the bottom of the fishing device 33, a boosting device 34 is arranged at the bottom of the treatment tank 30, and the boosting device 34 is located below the partition plate 35.

[0069] The boosting device 34 comprises a motor and a plate arranged on the output end of the motor. The motor drives the plate to rotate at the bottom of the treatment tank 30, and the plate drives the sodium carbonate solids to move to the bottom of the fishing device 33.

[0070] In another specific embodiment,

[0071] Referring to Figures 2-4 The fishing device 33 comprises a rotating shaft, a fishing motor 35, a track 333 and a fishing box 331.

[0072] Specifically, the two ends of the rotating shaft are fixedly arranged on the inner wall of the treatment tank 30, and the fishing motor 35 is arranged above the treatment tank 30. The track 333 is sleeved on the rotating shaft and the output shaft 332 of the fishing motor 35, a plurality of fishing boxes 331 are hingedly connected to the track 333 through hinges 334, the opening directions of all the fishing boxes 331 are consistent, and one side of the opening of the fishing box 331 is hingedly connected to the track 333, so that in the process of moving of the fishing box 331 from the output shaft 332 of the fishing motor 35 to the rotating shaft under the driving of the track 333, the side of the opening of the fishing box 331 is abutted on the track 333, so that the opening of the fishing box 331 is in a reverse position.

[0073] The bottom of the fishing box 331 is composed of gauze, so that when the fishing box 331 is separated from the solution liquid surface, the liquid in the fishing box 331 can seep out of the gauze, and the sodium carbonate solid is left in the fishing box 331.

[0074] Two tracks 333 are arranged on the rotating shaft and the output shaft 332 of the fishing motor 35, and a plurality of fishing boxes 331 are arranged on the two tracks 333.

[0075] In the embodiment, the fishing motor 35 drives the track 333 to rotate, then the fishing box 331 picks up the sodium carbonate solid at the bottom of the treatment tank 30, and pours out the sodium carbonate solid in the process of moving of the fishing box 331 downward under the driving of the track 333, so as to continuously pick up the sodium carbonate solid at the bottom of the treatment tank 30.

[0076] The above-described embodiments only express the specific implementation of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the protection scope of the present application.

Claims

1. A flue gas treatment system for electrolytic aluminum, wherein the flue gas sequentially passes through a dust removal device, a desulfurization tower, and a defluorination tower, characterized in that, Also includes: A dissolving tank containing a saturated solution of caustic soda, with caustic soda crystals at the bottom, the dissolving tank comprising a front dissolving tank and a rear dissolving tank connected to each other, the front dissolving tank being used to dissolve caustic soda into a near-saturated solution, and the bottom of the rear dissolving tank having caustic soda crystals deposited to maintain the precipitation of caustic soda crystals so as to ensure that the clear liquid above it is a saturated caustic soda solution. The treatment tank is connected to the upper clear liquid of the rear dissolving tank through a conveying pipe. The treatment tank has a baffle plate. The conveying pipe and the flue gas pipe are located on one side of the baffle plate, and the retrieval device is located on the other side of the baffle plate. The flue gas pipe is connected at one end to the defluorination tower and at the other end to the bottom of the treatment tank; The salvage device has one end located inside the treatment pool and near the bottom of the treatment pool, and the other end located outside the treatment pool. The retrieval device includes a partition, with a gap between the bottom of the partition and the bottom of the treatment pool. The flue gas pipe and the conveying pipe are located on one side of the partition, and the retrieval device is located on the other side of the partition.

2. The flue gas treatment system for electrolytic aluminum according to claim 1, characterized in that, The delivery pipe is located at one end inside the treatment tank, near the top surface of the treatment tank.

3. The flue gas treatment system for electrolytic aluminum according to claim 1, characterized in that, The treatment pool is equipped with a booster device located below the partition.

4. The flue gas treatment system for electrolytic aluminum according to claim 1, characterized in that, The dissolving tank is equipped with a stirring device, the stirring end of which is submerged in the caustic soda crystals at the bottom of the dissolving tank.

5. The flue gas treatment system for electrolytic aluminum according to claim 1, characterized in that, The salvage device includes: A rotating shaft, with its two ends located on the two side walls inside the treatment tank; A salvage motor is located above the treatment pool, and the output shaft of the salvage motor is parallel to the rotating shaft; Tracks are fitted onto the rotating shaft and the output shaft of the salvage motor; Several retrieval boxes are distributed on the track, and the opening direction of all the retrieval boxes is consistent.

6. The flue gas treatment system for electrolytic aluminum according to claim 5, characterized in that, The bottom of the retrieval box is made of gauze.

7. The flue gas treatment system for electrolytic aluminum according to claim 5, characterized in that, The rotating shaft and the output shaft of the salvage motor are provided with two tracks, and each track is provided with a plurality of salvage boxes.

8. The flue gas treatment system for electrolytic aluminum according to claim 5, characterized in that, One end of the opening of the retrieval box is hinged to the track.

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