Graphitization furnace flue gas treatment system and process

Abstract

The application relates to a graphitization furnace flue gas treatment system and process, and relates to the technical field of graphitization furnace flue gas treatment.The system comprises a flue gas supply module, a lime slurry supply module, an absorption tower group, a product conveying module, a product treatment module and a tail gas treatment module, a reaction pool containing water is formed at the bottom of each absorption tower in the absorption tower group, flue gas is introduced into the reaction pool by the flue gas supply module, a spraying module is arranged in the absorption tower, the spraying module is arranged above the reaction pool, the lime slurry supply module conveys lime slurry to the spraying module, the product conveying module conveys reaction products in the reaction pool to the product treatment module, the product treatment module performs solid-liquid separation on the reaction products, and the tail gas treatment module is connected with the absorption tower.The application has the effects of prolonging reaction time, absorbing SO2 and SO3 for multiple times through multistage reaction, making desulfurization more thorough, and improving the desulfurization efficiency of graphitization furnace flue gas.

Description

Technical Field

[0001] This application relates to the field of graphite furnace flue gas treatment technology, and in particular to a graphitization furnace flue gas treatment system and process. Background Technology

[0002] Graphite furnaces are mainly used for high-temperature heating treatments (such as metal smelting and chemical production). The flue gas components produced during their combustion or reaction processes include particulate matter (dust), sulfur oxides (SO2), and nitrogen oxides (NOx). X The flue gas produced by graphitization furnaces contains pollutants such as carbon monoxide (CO), carbon dioxide (CO2), heavy metals (such as lead and mercury), and volatile organic compounds (VOCs). Direct emission of these pollutants would seriously harm the environment and health, therefore, it is necessary to treat the flue gas produced by graphitization furnaces.

[0003] Utility model publication number CN220026603U discloses a flue gas purification process system for a graphitization furnace. In existing patents, flue gas from a heat exchange furnace enters a spray furnace through a purification pipe. A storage tank contains lime slurry as a washing agent. The lime slurry flows from an outlet tank into an outlet pipe and is sprayed into the spray furnace through a spray nozzle to wash the flue gas, thereby removing SO2 and a small amount of nitrogen dioxide. In this prior art, the flue gas only comes into contact with the lime slurry in a single spray, resulting in low gas-liquid mass transfer efficiency. Some SO2 does not react fully and escapes with the flue gas, leading to low desulfurization efficiency. Summary of the Invention

[0004] In order to improve the problem that the desulfurization efficiency is low because the flue gas only comes into contact with lime slurry through a single spray, this application provides a flue gas treatment system and process for graphitization furnace.

[0005] The graphitization furnace flue gas treatment system and process provided in this application adopts the following technical solution:

[0006] A graphitization furnace flue gas treatment system includes a flue gas supply module, a lime slurry supply module, an absorption tower group, a product conveying module, a product processing module, and a tail gas treatment module. Each absorption tower in the absorption tower group forms a water-filled reaction pool at its bottom. The flue gas supply module can introduce flue gas into the reaction pool. After contacting the water in the reaction pool, the flue gas flows towards the top of the absorption tower. A spray module is installed inside the absorption tower and positioned above the reaction pool. The lime slurry supply module can convey lime slurry to the spray module, which sprays the lime slurry towards the reaction pool. The product conveying module can convey the reaction products from the reaction pool to the product processing module, which performs solid-liquid separation on the reaction products. The tail gas treatment module is connected to the absorption tower to purify the flue gas discharged from the absorption tower.

[0007] By adopting the above technical solution, the flue gas is first passed through the water in the reaction tank to dissolve some SO2 and SO3 and remove dust and other impurities, reducing interference from subsequent reactions. The moistened flue gas comes into contact with the sprayed lime slurry, and SO2 and SO3 react with Ca(OH)2 to form CaSO3 / CaSO4 precipitates. The sprayed lime slurry falls into the storage water of the reaction tank and continues to react with the dissolved sulfides, extending the reaction time. Through multi-stage reactions, SO2 and SO3 are absorbed multiple times, making desulfurization more thorough and improving the desulfurization efficiency of the graphitization furnace flue gas.

[0008] Preferably, the absorption towers in the absorption tower group are connected in series on the flue gas flow pipeline, and the flue gas discharged from the upstream absorption tower is introduced into the reaction tank of the downstream absorption tower.

[0009] By adopting the above technical solution, the flue gas is treated through multi-stage absorption towers, and pollutants such as SO2 and SO3 are absorbed multiple times, thereby improving desulfurization efficiency, reducing the content of pollutants in the flue gas, and enhancing the treatment effect on the flue gas from the graphitization furnace.

[0010] Preferably, an oxidation module is connected in series between the lime slurry supply module and the spraying module, so that the lime slurry supplied to the spraying module flows through the oxidation module, and the oxidation module can blow air into the lime slurry to increase the oxygen content in the lime slurry.

[0011] By adopting the above technical solution, the lime slurry can obtain a higher oxygen content. When it reacts with acidic gases such as SO2 and SO3 in the flue gas, it can promote the faster oxidation of sulfurous acid to sulfuric acid, thereby generating calcium sulfate precipitate more efficiently, accelerating the desulfurization reaction process, and further improving the desulfurization effect on the flue gas of the graphitization furnace.

[0012] Preferably, the lime slurry supply module includes a lime silo and a digester. The lime silo supplies lime raw materials to the digester through pipelines. The digester has a built-in stirring mechanism that can stir the lime raw materials and water to produce lime slurry.

[0013] By adopting the above technical solution, lime raw materials can be stored in lime silos, transported to digesters via pipelines, and then thoroughly mixed with water using a stirring mechanism to effectively prepare lime slurry for subsequent flue gas treatment.

[0014] Preferably, the absorption tower is equipped with a tube bundle demister, which is located above the spray module, allowing the flue gas flowing toward the top of the absorption tower to pass through the tube bundle demister.

[0015] By adopting the above technical solution, mist and droplets in the flue gas flowing towards the top of the absorption tower can be removed, further improving the cleanliness of the flue gas, reducing the pollutants carried in the flue gas, and making the quality of the flue gas entering the exhaust gas treatment module better, which is conducive to the final discharge of exhaust gas that meets the regulations.

[0016] Preferably, it also includes a water supply module, which supplies water to the digester, reaction tank, product delivery module, and tube bundle demister via pipelines.

[0017] By adopting the above technical solution, the water supply module can supply water to the digester through pipelines to assist in the production of lime slurry, replenish water to the reaction tank to ensure its water level is stable, supply water to the product conveying module to prevent slurry scaling in the pipeline, and supply water to the tube bundle demister to maintain its normal operation, ensuring that all parts of the entire graphitization furnace flue gas treatment system can work stably.

[0018] Preferably, the system also includes a slurry circulation tank, which is equipped with a baffle to divide the slurry circulation tank into a first circulation tank and a second circulation tank. The first circulation tank is connected in series in the pipeline of the product conveying module, and the second circulation tank is connected in series in the pipeline of the lime slurry supply module. The baffle is provided with an overflow hole so that the upper clear liquid in the first circulation tank can flow into the second circulation tank.

[0019] By adopting the above technical solutions, water and lime slurry can be recycled, reducing resource waste and lowering production costs.

[0020] Preferably, the digester shell is provided with a cooling chamber filled with coolant. The digester is provided with an inlet and an outlet communicating with the cooling chamber. Both the inlet and the outlet are connected to a coolant circulation system. The coolant circulation system can cool the water effluent from the cooling chamber and return it to the cooling chamber through the inlet. The coolant in the cooling chamber can exchange heat with the lime slurry in the digester.

[0021] By adopting the above technical solution, the reaction of calcium oxide and water in the digester is cooled by coolant, which avoids the lime slurry from sintering and coarsening of particles due to excessive temperature, thus affecting its performance, ensuring the quality of lime slurry and the effect of subsequent reactions, and ensuring the stable operation of the entire graphitization furnace flue gas treatment system.

[0022] Preferably, the stirring mechanism includes a rotating sleeve, a stirring blade, and a driving component. The digester includes an upper tank and a lower tank. The rotating sleeve is disposed between the upper tank and the lower tank and is slidably and sealingly connected to both the upper tank and the lower tank. The driving component is connected to the rotating sleeve to drive the rotating sleeve to rotate. A stirring rod arranged radially through the rotating sleeve is provided so that the stirring rod can rotate synchronously with the rotating sleeve. The stirring blade is fixedly disposed at one end of the stirring rod inserted into the rotating sleeve. A guide ring plate is fixedly provided on the lower tank. The guide ring plate has periodically changing guide grooves. The stirring rod has a guide portion that can slide along the guide grooves so that the stirring rod can rotate with the rotating sleeve and slide back and forth radially along the rotating sleeve. The stirring blade has a "V" shaped structure with its tip facing the center of the rotating sleeve, and a guide plate is provided at the front end of the stirring blade along its own rotation direction. The guide plate can guide the lime slurry to flow to the inner wall of the digester.

[0023] By adopting the above technical solution, when calcium oxide reacts with water to produce lime slurry, the driving component drives the rotating sleeve to rotate. Simultaneously, the rotating sleeve drives the agitator to rotate the impeller, stirring the lime and water to ensure a thorough reaction and accelerate the mixing of the lime slurry, thus improving production efficiency. As the agitator rotates with the rotating sleeve, the guide slides along the guide groove, causing the agitator to reciprocate radially along the rotating sleeve. When the stirred slurry moves towards the inner wall of the digester, the agitator pushes the lime slurry against the inner wall, increasing the heat exchange intensity between the lime slurry and the coolant, improving the production quality of the lime slurry. Furthermore, the reciprocating sliding of the agitator increases the stirring effect of the agitator on the lime slurry, further improving production efficiency. By arranging the agitator impeller in a "V" shape, the agitator moves towards the center of the digester, and the lime slurry flows along the inclined side of the agitator impeller to both sides, reducing the amount of lime slurry pushed to the center of the digester and effectively preventing the concentration of lime slurry and the resulting heat concentration.

[0024] A graphitization furnace flue gas treatment process, using the aforementioned graphitization furnace flue gas treatment system, includes: a flue gas flow process: the flue gas supply module introduces the flue gas generated by the graphitization furnace into the reaction tank at the bottom of the absorption tower, where the flue gas reacts with water in the reaction tank, and the flue gas after passing through the water flows to the top of the absorption tower and is discharged to the tail gas treatment module for purification treatment; a lime slurry absorption process: the lime slurry supply module transports lime slurry to the spraying module, which sprays the lime slurry towards the bottom of the absorption tower, where the lime slurry reacts with the flue gas after passing through the water, and then falls into the reaction tank to react with the sulfur-containing components in the water to generate solids; a precipitate discharge process: the product conveying module transports the solids generated in the reaction tank to the product processing module for solid-liquid separation.

[0025] By adopting the above technical solution, the flue gas is introduced into the water in the reaction tank at the bottom of the absorption tower, which can dissolve some SO2 and SO3 and remove dust and other impurities, reducing interference from subsequent reactions. The moistened flue gas comes into contact with the sprayed lime slurry, causing SO2 and SO3 to react with the lime slurry to form solid precipitates. The sprayed lime slurry falls into the reaction tank to continue reacting with the dissolved sulfides, extending the reaction time. The reaction products in the reaction tank are transported to the product processing module for solid-liquid separation via the product conveying module. The flue gas that has come into contact with the lime slurry in the absorption tower enters the tail gas treatment module for purification, making desulfurization more thorough, improving the desulfurization efficiency of the graphitization furnace flue gas, and realizing the solid-liquid separation of reaction products and tail gas purification, ensuring that the discharged tail gas meets the regulations.

[0026] In summary, this application includes at least one of the following beneficial technical effects:

[0027] 1. The flue gas first comes into contact with water in the reaction tank, which can dissolve some SO2 and SO3, remove dust and other impurities, and reduce interference from subsequent reactions. Then, the moistened flue gas comes into contact with the sprayed lime slurry, and the sprayed lime slurry falls into the reaction tank to continue to react with the dissolved sulfides, realizing a multi-stage reaction, so that SO2 and SO3 are absorbed multiple times, thereby improving the desulfurization efficiency.

[0028] 2. The absorption towers in the absorption tower group are connected in series to treat the flue gas in multiple stages, so that SO2 and SO3 are absorbed multiple times, the desulfurization is more complete, and the content of SO2 and SO3 in the flue gas can be significantly reduced, thus improving the flue gas treatment effect.

[0029] 3. The lime slurry has a higher oxygen content, which can promote the faster oxidation of sulfurous acid to sulfuric acid when it reacts with acidic gases such as SO2 and SO3 in the flue gas. This results in the more efficient generation of calcium sulfate precipitate, which accelerates the desulfurization reaction process and further improves the desulfurization effect on the flue gas of the graphitization furnace. Attached Figure Description

[0030] Figure 1This is a flowchart of a graphitization furnace flue gas treatment system according to an embodiment of this application.

[0031] Figure 2 This is a flowchart showing the absorption tower assembly.

[0032] Figure 3 This is a flowchart illustrating the exhaust gas treatment module.

[0033] Figure 4 This is a flowchart illustrating the lime slurry supply module.

[0034] Figure 5 This is a schematic diagram showing the structure of a digester.

[0035] Figure 6 This is a top view showing the digester.

[0036] Figure 7 It is along Figure 6 A cross-sectional view along line AA in the middle.

[0037] Figure 8 yes Figure 5 Enlarged view of section B in the middle.

[0038] Figure 9 yes Figure 7 Enlarged view of section C.

[0039] Figure 10 It is a structural diagram used to demonstrate the cooperation between the sliding part and the slide rail frame.

[0040] Figure 11 This is a flowchart showing the product delivery module and the oxidation module.

[0041] Figure 12 This is a flowchart showing the product processing module.

[0042] Figure 13 This is a flowchart illustrating the water supply module.

[0043] Explanation of reference numerals in the attached drawings: 1. Flue gas supply module; 11. Flue gas supply pipe; 12. Exhaust fan; 2. Lime slurry supply module; 21. Lime silo; 22. Digestion tank; 221. Upper tank; 222. Lower tank; 223. Cooling chamber; 224. Liquid outlet; 225. Liquid inlet; 23. Arch-breaking air cannon; 24. Manual slide gate valve; 25. Electric rotary valve; 26. Mixing mechanism; 261. Rotating sleeve; 262. Mixing blade; 263. Drive component; 2631. Drive motor; 2632. Drive gear; 2633. Gear ring; 264. Mixing rod; 2651. Guide groove; 2652. Support ring; 2653. Support frame; 2654. Slide rail frame; 2655. Sliding part; 267. Guide ring plate ; 2671, Guide trough; 2672, Guide section; 2673, Roller; 268, Guide plate; 27, Frame; 3, Absorption tower group; 31, Absorption tower; 32, Reaction tank; 33, Spray module; 34, Tube bundle demister; 4, Slurry circulation tank; 41, Baffle; 42, First circulation tank; 43, Second circulation tank; 44, Overflow hole; 45, Circulation pump; 5, Product conveying module; 51, Slurry discharge pump; 6, Product processing module; 61, Hydrocyclone; 62, Vacuum drying device; 621, Belt filter; 622, Vacuum pump; 623, Gas-liquid separator; 7, Tail gas treatment module; 71, Wet electrostatic precipitator; 8, Oxidation module; 81, Oxidation fan; 9, Water supply module; 91, Water tank; 92, Water pump. Detailed Implementation

[0044] The following is in conjunction with the appendix Figure 1-13 This application will be described in further detail.

[0045] This application discloses a graphitization furnace flue gas treatment system.

[0046] Reference Figure 1 A graphitization furnace flue gas treatment system includes a flue gas supply module 1, a lime slurry supply module 2, an absorption tower group 3, a product conveying module 5, a product processing module 6, a tail gas treatment module 7, an oxidation module 8, a water supply module 9, and a slurry circulation pool 4.

[0047] Reference Figure 2 The flue gas supply module 1 includes a flue gas supply pipe 11 and an induced draft fan 12. One end of the flue gas supply pipe 11 is connected to the flue gas outlet of the graphitization furnace, and the other end is connected to the absorption tower 31 in the absorption tower group 3. The induced draft fan 12 is connected in series with the flue gas supply pipe 11, so that the flue gas generated by the graphitization furnace is introduced into the absorption tower 31.

[0048] Reference Figure 2The absorption tower group 3 contains three absorption towers 31 arranged side-by-side, namely the primary absorption tower 31, the secondary absorption tower 31, and the tertiary absorption tower 31. The flue gas passes through these three absorption towers 31 sequentially before entering the tail gas treatment module 7. Specifically, each absorption tower 31 has a water-filled reaction pool 32 at its bottom. The flue gas supply pipe 11 is connected to the reaction pool 32 in the upstream absorption tower 31, and the outlet of the flue gas supply pipe 11 is below the liquid level in the reaction pool 32. The tops of the primary absorption towers 31 are connected to the reaction pool 32 in the secondary absorption tower 31 via pipes, and the tops of the secondary absorption towers 31 are connected to the reaction pool 32 in the tertiary absorption tower 31 via pipes, allowing the flue gas to pass through the three absorption towers 31 sequentially before entering the tail gas treatment module 7. When the flue gas passes through the water in the reaction pool 32, the SO2 and SO3 in the flue gas react with the water to produce sulfurous acid and sulfuric acid, while dust and other impurities remain in the water. Undissolved SO2 and other gases rise with the flue gas.

[0049] Reference Figure 2 Each absorption tower 31 is equipped with a spray module 33, which is located above the reaction tank 32. The spray module 33 includes multiple spray heads with nozzles facing the reaction tank 32. The spray module 33 sprays lime slurry downwards, and the falling lime slurry reacts with the rising flue gas.

[0050] SO2 + Ca(OH)2 → CaSO3↓ + H2O

[0051] SO3 + Ca(OH)2 → CaSO4↓ + H2O

[0052] 2CaSO3 + O2 → 2CaSO4

[0053] The flue gas reacts with SO2 and SO3 in the flue gas to remove SO2 and SO3. The remaining flue gas enters the downstream absorption tower 31 from the top of the absorption tower 31 for desulfurization. The flue gas discharged from the top of the downstream absorption tower 31 enters the tail gas treatment module 7 for purification.

[0054] When lime slurry falls into the water in reaction tank 32, the following chemical reaction occurs:

[0055] H₂SO₃ + Ca(OH)₂ → CaSO₃↓ + 2H₂O

[0056] H₂SO₄ + Ca(OH)₂ → CaSO₄↓ + 2H₂O

[0057] The precipitate produced by the reaction settles in reaction tank 32, and the product treatment module 6 discharges the precipitate and water out of absorption tower 31. The flue gas first contacts the water in reaction tank 32, which can dissolve some SO2 and SO3, remove dust and other impurities, and reduce interference from subsequent reactions. Then, the moistened flue gas contacts the sprayed lime slurry, and the sprayed lime slurry falls into reaction tank 32 to continue reacting with the dissolved sulfides, realizing a multi-stage reaction, so that SO2 and SO3 are absorbed multiple times, thereby improving the desulfurization efficiency.

[0058] Reference Figure 2 The three-stage absorption tower 31 is equipped with a tube bundle demister 34, which is located above the spray module 33 of the absorption tower 31. The tube bundle demister 34 can remove mist and droplets from the flue gas flowing toward the top of the absorption tower 31, further improving the cleanliness of the flue gas, reducing the pollutants carried in the flue gas, and making the quality of the flue gas entering the exhaust gas treatment module 7 better, which is conducive to the final discharge of exhaust gas that meets the regulations.

[0059] Reference Figure 3 In this embodiment, the exhaust gas treatment module 7 is a wet electrostatic precipitator 71. The wet electrostatic precipitator 71 purifies the flue gas discharged from the absorption tower 31 to ensure that the composition and content of the discharged exhaust gas meet the requirements.

[0060] Reference Figure 4 In this embodiment, the lime slurry supply module 2 includes a lime silo 21 and a digester 22. The lime silo 21 is designed with a cylindrical upper part and a conical lower part. Quicklime (CaO) is poured into the lime silo 21 by unloading from a vehicle. At the same time, the lime silo 21 has multiple discharge ports at the bottom, and anti-blocking air cannons 23 are equipped at the discharge ports to prevent material accumulation. The discharge ports at the bottom of the lime silo 21 are connected to the inlet of the digester 22 by a pipeline, and a manual slide valve 24 and an electric rotary valve 25 are connected in series on this pipeline. Lime powder enters the digester 22 through the electric rotary valve 25.

[0061] Reference Figure 5 , Figure 6 and Figure 7In this embodiment, the digester 22 is a rotary structure. The top of the digester 22 is provided with a lime feed inlet, a water inlet and an exhaust outlet. The digester 22 has a built-in stirring mechanism 26, which stirs the lime raw material and water to produce lime slurry. The digester 22 includes an upper tank body 221 and a lower tank body 222, both of which are fixedly connected to the frame 27. Both the upper tank 221 and the lower tank 222 have cooling chambers 223 filled with coolant. The cooling chambers 223 are arranged in a circle around the circumference of the digester 22. In this embodiment, the coolant is cooling water. Both the upper tank 221 and the lower tank 222 are provided with inlet 225 and outlet 224 that communicate with the cooling chambers 223. Both inlet 225 and outlet 224 are connected to the coolant circulation system. The cooling water is cooled by air cooling in the coolant circulation system. The cooling water in the cooling chamber 223 is heated after exchanging heat with the lime slurry. The heated cooling water enters the coolant circulation system through outlet 224. The fan cools the heated cooling water. The cooled cooling water enters the cooling chamber 223 through inlet 225 to cool the lime slurry, thereby realizing the cooling water circulation to cool the lime slurry. Cooling water circulation is used to cool the reaction between calcium oxide and water in the digester 22, preventing the lime slurry from sintering and coarsening due to excessive temperature, which would affect its performance, ensure the quality of the lime slurry and the effect of subsequent reactions, and ensure the stable operation of the entire graphitization furnace flue gas treatment system.

[0062] Reference Figure 7 , Figure 8 In this embodiment, the stirring mechanism 26 includes a rotating sleeve 261, a stirring blade 262, and a driving component 263. The rotating sleeve 261 is disposed between the upper tank 221 and the lower tank 222. Grooves are formed at both the upper and lower ends of the rotating sleeve 261. The upper tank 221 and the lower tank 222 are respectively inserted into the corresponding grooves, so that the rotating sleeve 261 is slidably and sealed to the upper tank 221 and the lower tank 222. In this embodiment, the driving component 263 includes a drive motor 2631, a drive gear 2632, and a gear ring 2633. The gear ring 2633 is disposed along the circumference of the rotating sleeve 261 on the outer side wall of the rotating sleeve 261. The drive motor 2631 is fixedly connected to the frame 27. The drive gear 2632 is coaxially fixedly mounted on the output shaft of the drive motor 2631 and meshes with the gear ring 2633, so that the drive motor 2631 drives the rotating sleeve 261 to rotate.

[0063] Reference Figure 7 , Figure 9 and Figure 10The rotating sleeve 261 is provided with stirring rods 264 arranged radially. There are several stirring rods 264, which are evenly spaced along the circumference of the rotating sleeve 261. The stirring blades 262 correspond one-to-one with the stirring rods 264 and are fixedly arranged at one end of the stirring rods 264 located in the digester 22. A guide groove 2651 is fixedly provided at the upper edge of the inner wall of the upper tank 221. The guide groove 2651 is arranged in a circle around the circumference of the upper tank 221. A support ring 2652 is slidably embedded in the guide groove 2651. A support frame 2653 is fixedly provided at the bottom of the support ring 2652. The support frame 2653 corresponds one-to-one with the stirring rod 264. A slide rail frame 2654 is fixedly provided at the bottom of the support frame 2653 and arranged radially along the rotating sleeve 261. The slide rail frame 2654 has space for the stirring blade 262 to slide. The stirring rod 264 is provided with a sliding part 2655 that slides on the slide rail frame 2654, so that the slide rail frame 2654 provides support for the sliding of the stirring rod 264 and improves the stability of the sliding of the stirring rod 264.

[0064] Reference Figure 5 , Figure 8 A guide ring plate 267 is fixedly provided on the frame 27. The guide ring plate 267 is sleeved on the digester 22. The guide ring plate 267 has a periodically changing guide groove 2671. In this embodiment, the trajectory of the guide groove 2671 after unfolding is a sine curve. The guide groove 2671 is connected end to end. The stirring rod 264 is provided with a guide part 2672 that slides along the guide groove 2671. A roller 2673 is sleeved on the guide part 2672. The roller 2673 rolls along the groove wall of the guide groove 2671 instead of sliding, thereby reducing the friction between the guide part 2672 and the groove wall of the guide groove 2671.

[0065] Reference Figure 10 The stirring blade 262 has a "V" shaped structure with its tip facing the center of the rotating sleeve. The stirring blade 262 has a guide plate 268 at its front end along its own rotation direction. The guide plate 268 is integrally formed with the stirring blade 262. The guide plate 268 is inclined towards the side away from the inner wall of the digester 22 along the rotation direction of the stirring blade 262, so that the guide plate 268 can guide the lime slurry to flow to the inner wall of the digester 22.

[0066] When calcium oxide reacts with water to produce lime slurry, the drive unit 263 drives the rotating sleeve 261 to rotate. Simultaneously, the rotating sleeve 261 rotates, driving the impeller via the stirring rod 264. This agitates the lime and water, ensuring a thorough reaction to produce lime slurry, accelerating mixing, and improving production efficiency. As the stirring rod 264 rotates with the rotating sleeve 261, the guide part 2672 slides along the guide groove 2671, causing the stirring rod 264 to reciprocate radially along the rotating sleeve 261. When the agitated slurry moves towards the inner wall of the digestion tank 22, the stirring impeller 262 pushes the lime slurry against the inner wall, increasing the heat exchange intensity between the lime slurry and the coolant, improving the production quality of the lime slurry. Furthermore, the reciprocating sliding of the stirring impeller 262 enhances the agitation effect on the lime slurry, further increasing production efficiency. The stirring blade 262 is set into a "V" shape, so that the stirring blade 262 moves towards the center of the digester 22. The lime slurry flows along the inclined side of the stirring blade 262 to both sides of the stirring blade 262, reducing the amount of lime slurry pushed by the stirring blade 262 to the center of the digester 22, and effectively avoiding the phenomenon of heat concentration caused by the concentration of lime slurry.

[0067] Reference Figure 11 The slurry circulation tank 4 corresponds one-to-one with the absorption tower 31. The slurry circulation tank 4 is equipped with a baffle 41. In this embodiment, there are two baffles 41, which are spaced apart. The baffles 41 divide the slurry circulation tank 4 into a first circulation tank 42 and a second circulation tank 43. The lime slurry coming out from the bottom of the digester 22 flows into the second circulation tank 43 through the pipeline. The lime slurry in the second circulation tank 43 is transported to the spray module 33 for spraying through the pipeline and the circulation pump 45.

[0068] Reference Figure 11 The oxidation module 8 includes an oxidation blower 81, which introduces gas into the second circulation pool 43 through a pipeline to increase the oxygen content in the lime slurry. This allows the lime slurry to obtain a higher oxygen content, which, when reacting with acidic gases such as SO2 and SO3 in the flue gas, promotes the faster oxidation of sulfurous acid into sulfuric acid, thereby generating calcium sulfate precipitate more efficiently, accelerating the desulfurization reaction process, and further improving the desulfurization effect on the flue gas of the graphitization furnace.

[0069] Reference Figure 11 The first circulation tank 42 is located below the absorption tower 31. The precipitate in the reaction tank 32 is discharged into the first circulation tank 42 through a pipe. The precipitate settles in the first circulation tank 42 and forms a clear liquid on the upper layer. An overflow hole 44 is provided on the baffle 41. The liquid level in the second circulation tank 43 is lower than the height of the overflow hole 44, so that the clear liquid on the upper layer in the first circulation tank 42 flows into the second circulation tank 43, realizing the recycling of water and lime slurry, reducing resource waste and lowering production costs.

[0070] Reference Figure 11 The product conveying module 5 includes a slurry pump 51, which is a mud pump. The inlet of the slurry pump 51 is inserted into the bottom of the first circulation tank 42 through a pipe to suck out the sediment at the bottom of the first circulation tank 42. The outlet of the slurry pump 51 is connected to the product processing module 6 through a pipe to transport the sediment in the first circulation tank 42 to the product processing module 6.

[0071] Reference Figure 12 The product processing module 6 includes a hydrocyclone 61 and a vacuum drying device 62. The precipitate transported by the slurry pump 51 enters the hydrocyclone 61, causing gas-liquid separation. The separated liquid flows back to the second circulation tank 43 and enters the vacuum drying device 62. The vacuum drying device 62 includes a belt filter 621, a vacuum pump 622, and a gas-liquid separator 623. The precipitate spreads on the sealed belt filter 621 and enters the vacuum drying zone with the filter belt. The vacuum pump 622 continuously draws gas from the system through the gas-liquid separator 623 to maintain a low-pressure environment inside the hood, allowing the moisture in the material to evaporate at low temperature. The steam-containing gas flow passes through the gas-liquid separator 623 to intercept liquid water before entering the vacuum pump 622. The separated condensate is collected and discharged. The dried material is discharged by belt conveyor, and the moisture is removed from the system with the airflow, achieving continuous vacuum low-temperature drying.

[0072] Reference Figure 13 The water supply module 9 includes a water tank 91 and a water pump 92. The water pump 92 supplies water from the water tank 91 to the digester 22, reaction tank 32, product conveying module 5, and tube bundle demister 34 through pipelines. It supplies water to the digester 22 to assist in the production of lime slurry, replenishes water to the reaction tank 32 to ensure its water level is stable, supplies water to the product conveying module 5 to prevent slurry scaling in the pipeline, and supplies water to the tube bundle demister 34 to maintain its normal operation, ensuring that all parts of the graphitization furnace flue gas treatment system can work stably.

[0073] The implementation principle of the graphitization furnace flue gas treatment system in this application embodiment is as follows: the flue gas is first passed through the water in the reaction tank 32 to dissolve some SO2 and SO3 and remove dust and other impurities, reducing interference from subsequent reactions. The moistened flue gas comes into contact with the sprayed lime slurry, and SO2 and SO3 react with Ca(OH)2 to generate CaSO3 / CaSO4 precipitate. The sprayed lime slurry falls into the water storage in the reaction tank 32 and continues to react with the dissolved sulfides, prolonging the reaction time. Through multi-stage reactions, SO2 and SO3 are absorbed multiple times, making desulfurization more thorough and improving the desulfurization efficiency of the graphitization furnace flue gas.

[0074] This application discloses a process for treating flue gas from a graphitization furnace.

[0075] A graphitization furnace flue gas treatment process, using the above-mentioned graphitization furnace flue gas treatment system, includes:

[0076] Flue gas flow process: The flue gas supply module 1 introduces the flue gas generated by the graphitization furnace into the reaction pool 32 at the bottom of the primary absorption tower 31. The flue gas reacts with the water in the reaction pool 32. The flue gas after reaction flows to the top of the primary absorption tower 31 and then into the reaction pool 32 at the bottom of the secondary absorption tower 31, where it reacts with water again. The flue gas after passing through the water flows through the top of the secondary absorption tower 31 and then into the reaction pool 32 in the tertiary absorption tower 31. After passing through the water, the flue gas enters the tail gas treatment module 7 through the tertiary absorption tower 31 for purification treatment.

[0077] The process of lime slurry absorbing flue gas: The lime slurry supply module 2 transports lime slurry to the spraying module 33 of the primary absorption tower 31, secondary absorption tower 31, and tertiary absorption tower 31. The spraying module 33 sprays the lime slurry towards the bottom of the absorption tower 31. The lime slurry first reacts with the flue gas after it has been rinsed with water, and then falls into the reaction tank 32 to react and generate CaSO3 / CaSO4 precipitates. The precipitates in the reaction tank 32 and water enter the first circulation tank 42 of the slurry circulation tank 4 through pipelines for sedimentation. The clear water overflows into the second circulation tank 43, mixes with the lime slurry from the lime slurry supply module 2, and is then transported to the spraying module 33 for spraying via the circulation pump 45.

[0078] Sediment discharge process: The sediment conveyed by the slurry pump 51 enters the hydrocyclone 61, which separates the gas and liquid. The separated liquid flows back to the second circulation tank 43 and enters the vacuum drying device 62. The vacuum drying device 62 uses the belt filter 621, vacuum pump 622 and gas-liquid separator 623 to dry the sediment to obtain gypsum.

[0079] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A flue gas treatment system for a graphitization furnace, characterized in that: The system includes a flue gas supply module (1), a lime slurry supply module (2), an absorption tower group (3), a product conveying module (5), a product processing module (6), and a tail gas treatment module (7). Each absorption tower (31) within the absorption tower group (3) has a water-filled reaction tank (32) at its bottom. The flue gas supply module (1) can introduce flue gas into the reaction tank (32). After contacting the water in the reaction tank (32), the flue gas flows towards the top of the absorption tower (31). A spray module (33) is installed inside the absorption tower (31). Located above the reaction tank (32), the lime slurry supply module (2) can transport lime slurry to the spray module (33), the spray module (33) can spray lime slurry toward the reaction tank (32), the product conveying module (5) can transport the reaction products in the reaction tank (32) to the product processing module (6), the product processing module (6) performs solid-liquid separation on the reaction products, and the tail gas treatment module (7) is connected to the absorption tower (31) to purify the flue gas discharged from the absorption tower (31). The lime slurry supply module (2) includes a lime silo (21) and a digestion tank (22). The lime silo (21) supplies lime raw materials to the digestion tank (22) through pipelines. The digestion tank (22) has a built-in stirring mechanism (26) that can stir the lime raw materials and water to produce lime slurry. The digester (22) has a cooling chamber (223) filled with coolant inside its shell. The digester (22) has an inlet (225) and an outlet (224) that communicate with the cooling chamber (223). Both the inlet (225) and the outlet (224) are connected to a coolant circulation system. The coolant circulation system can cool the water effluent from the cooling chamber (223) and return it to the cooling chamber (223) through the inlet (225). The coolant in the cooling chamber (223) can exchange heat with the lime slurry in the digester (22). The stirring mechanism (26) includes a rotating sleeve (261), stirring blades (262), and a driving component (263). The digestion tank (22) includes an upper tank body (221) and a lower tank body (222). The rotating sleeve (261) is disposed between the upper tank body (221) and the lower tank body (222) and is slidably and sealingly connected to the upper tank body (221) and the lower tank body (222) respectively. The driving component (263) is connected to the rotating sleeve (261) so as to drive the rotating sleeve (261) to rotate. The rotating sleeve (261) is fitted with a stirring rod (264) arranged radially thereon, so that the stirring rod (264) can rotate synchronously with the rotating sleeve (261). The stirring blade (262) is fixedly arranged at one end of the stirring rod (264) inserted into the rotating sleeve (261). The lower tank (222) is fixedly provided with a guide ring plate (267). The guide ring plate (267) is provided with a periodically changing guide groove (2671). The stirring rod (264) is provided with a guide part (2672) that can slide along the guide groove (2671), so that the stirring rod (264) can rotate with the rotating sleeve (261) and slide back and forth along the radial direction of the rotating sleeve (261). The stirring blade (262) has a "V" shaped structure with its tip facing the center of the rotating sleeve (261), and the stirring blade (262) has a guide plate (268) at its front end along its own rotation direction. The guide plate (268) can guide the lime slurry to flow to the inner wall of the digester (22).

2. The graphitization furnace flue gas treatment system according to claim 1, characterized in that: The absorption towers (31) in the absorption tower group (3) are connected in series on the flue gas flow pipeline. The flue gas discharged from the upstream absorption tower (31) is fed into the reaction tank (32) of the downstream absorption tower (31).

3. The graphitization furnace flue gas treatment system according to claim 1, characterized in that: An oxidation module (8) is connected in series between the lime slurry supply module (2) and the spray module (33) so that the lime slurry supplied to the spray module (33) flows through the oxidation module (8). The oxidation module (8) can blow air into the lime slurry to increase the oxygen content in the lime slurry.

4. The graphitization furnace flue gas treatment system according to claim 2, characterized in that: The absorption tower (31) is equipped with a tube bundle demister (34), which is located above the spray module (33). Flue gas flowing toward the top of the absorption tower (31) can flow through the tube bundle demister (34).

5. The graphitization furnace flue gas treatment system according to claim 1, characterized in that: It also includes a water supply module (9), which supplies water to the digester (22), reaction tank (32), product transport module (5), and tube bundle demister (34) through pipelines.

6. The graphitization furnace flue gas treatment system according to claim 1, characterized in that: It also includes a slurry circulation tank (4), which is provided with a partition (41) to divide the slurry circulation tank (4) into a first circulation tank (42) and a second circulation tank (43). The first circulation tank (42) is connected in series in the pipeline of the product conveying module (5), and the second circulation tank (43) is connected in series in the pipeline of the lime slurry supply module (2). An overflow hole (44) is provided on the partition (41) to allow the upper clear liquid in the first circulation tank (42) to flow into the second circulation tank (43).

7. A graphitization furnace flue gas treatment process, using the graphitization furnace flue gas treatment system according to any one of claims 1-6, characterized in that: include: Flue gas flow process: The flue gas supply module (1) feeds the flue gas generated by the graphitization furnace into the reaction pool (32) at the bottom of the absorption tower (31). The flue gas reacts with the water in the reaction pool (32). After passing through the water, the flue gas flows to the top of the absorption tower (31) and is discharged to the tail gas treatment module (7) for purification treatment through the top of the absorption tower (31). The process of lime slurry absorbing flue gas: The lime slurry supply module (2) delivers lime slurry to the spray module (33), and the spray module (33) sprays the lime slurry toward the bottom of the absorption tower (31). The lime slurry reacts with the flue gas after it has been saturated with water, and then falls into the reaction tank (32) to react with the sulfur-containing components in the water to generate solids. Sediment discharge process: The product conveying module (5) conveys the solid generated in the reaction tank (32) to the product processing module (6) for solid-liquid separation.

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