Graphitization furnace flue gas treatment system and process

Abstract

The invention relates to a graphitization furnace flue gas treatment system and process, and relates to the technical field of graphite furnace flue gas treatment.The graphitization furnace flue gas treatment system comprises a flue gas supply module, a lime slurry supply module, an absorption tower set, a product conveying module, a product treatment module and a tail gas treatment module, and a reaction tank containing water is formed at the bottom of each absorption tower in the absorption tower set; the flue gas supply module introduces flue gas into the reaction tank, the absorption tower is internally provided with a spraying module, the spraying module is arranged above the reaction tank, the lime slurry supply module conveys lime slurry to the spraying module, the product conveying module conveys reaction products in the reaction tank to the product treatment module, and the product treatment module performs solid-liquid separation on the reaction products. The tail gas treatment module is connected with the absorption tower. The flue gas desulfurization device has the effects that the reaction time is prolonged, SO2 and SO3 are absorbed for multiple times through multi-stage reaction, desulfurization is more thorough, and the desulfurization efficiency of the flue gas of the graphitization furnace is improved.

Description

Technical Field

[0001] The present application relates to the technical field of graphite furnace flue gas treatment, and in particular to a graphitization furnace flue gas treatment system and process. Background Art

[0002] Graphite furnaces are mainly used for high-temperature heating processes (such as metal smelting and chemical production). The flue gas components produced during the combustion or reaction process include particulate matter (dust), sulfur oxides (SO2), nitrogen oxides (NO x ), carbon monoxide (CO), carbon dioxide (CO2), heavy metals (such as lead, mercury) and volatile organic compounds (VOCs), etc. If these pollutants are directly discharged, they will seriously harm the environment and health. Therefore, the flue gas generated by the graphitization furnace needs to be treated.

[0003] Utility Model Publication No. CN220026603U discloses a graphitization furnace flue gas purification process system. In the existing patent, flue gas from the heat exchange furnace is passed through a purification pipe into a spray furnace. A liquid storage tank contains lime slurry as a detergent. The lime slurry flows from a liquid outlet tank into a liquid outlet pipe and is sprayed into the spray furnace through a liquid spray head to wash the flue gas, thereby removing SO2 and a small amount of nitrogen dioxide from the flue gas. In the existing technology, the flue gas only contacts the lime slurry through a single spray, resulting in low gas-liquid mass transfer efficiency. Some SO2 escapes with the flue gas without fully reacting, resulting in low desulfurization efficiency. Summary of the Invention

[0004] In order to improve the problem that the flue gas contacts the lime slurry only through a single spray, resulting in low desulfurization efficiency, the present application provides a graphitization furnace flue gas treatment system and process.

[0005] The present application provides a graphitization furnace flue gas treatment system and process using the following technical solutions: 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 treatment module and an exhaust gas treatment module. A reaction pool filled with water is formed at the bottom of each absorption tower in the absorption tower group. The flue gas supply module can pass flue gas into the reaction pool. After the flue gas contacts the water in the reaction pool, it flows toward the top of the absorption tower. A spray module is provided in the absorption tower, and the spray module is arranged above the reaction pool. The lime slurry supply module can convey lime slurry to the spray module, and the spray module can spray lime slurry toward the reaction pool. The product conveying module can convey the reaction product in the reaction pool to the product treatment module, and the product treatment module performs solid-liquid separation on the reaction product. The exhaust gas treatment module is connected to the absorption tower so as to purify the flue gas discharged from the absorption tower.

[0006] By adopting the above technical solution, the flue gas is first passed through the water in the reaction tank to dissolve part of SO2 and SO3 and remove impurities such as dust, reducing the interference of subsequent reactions. The humidified flue gas contacts 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 stored water in the reaction tank and continues to react with the dissolved sulfides, extending the reaction time. Through multiple-stage reactions, SO2 and SO3 are absorbed multiple times, making the desulfurization more thorough and improving the desulfurization efficiency of the graphitization furnace flue gas.

[0007] Preferably, the absorption towers in the absorption tower group are connected in series on the flue gas flow pipeline in sequence, and the flue gas discharged from the upstream absorption tower is introduced into the reaction tank of the downstream absorption tower.

[0008] By adopting the above technical solution, the flue gas is treated through multiple absorption towers, and pollutants such as SO2 and SO3 are absorbed multiple times, thereby improving the desulfurization efficiency, reducing the content of pollutants in the flue gas, and enhancing the treatment effect on the graphitization furnace flue gas.

[0009] Preferably, an oxidation module is connected in series between the lime slurry supply module and the spraying module, so that the lime slurry transported 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.

[0010] By adopting the above technical solution, the lime slurry obtains a higher oxygen content. When reacting with acidic gases such as SO2 and SO3 in the flue gas, it can promote the faster oxidation of sulfurous acid into sulfuric acid, thereby more efficiently generating calcium sulfate precipitates and accelerating the desulfurization reaction process, further improving the desulfurization effect on the graphitization furnace flue gas.

[0011] Preferably, the lime slurry supply module includes a lime silo and a digestion tank. The lime silo transports lime raw materials into the digestion tank through a pipeline, and the digestion tank is equipped with a stirring mechanism capable of stirring the lime raw materials and water to produce lime slurry.

[0012] By adopting the above technical solution, the lime raw materials can be stored in the lime silo, and after being transported to the digestion tank through a pipeline, the lime raw materials and water are fully stirred by means of the stirring mechanism, effectively preparing lime slurry for subsequent flue gas treatment.

[0013] Preferably, a tube bundle demister is provided in the absorption tower. The tube bundle demister is located above the spraying module, and the flue gas flowing towards the top of the absorption tower can flow through the tube bundle demister.

[0014] By adopting the above technical solution, it is possible to remove the mist and droplets in the flue gas flowing towards the top of the absorption tower, further improve the cleanliness of the flue gas, reduce the pollutants carried in the flue gas, make the quality of the flue gas entering the tail gas treatment module better, and facilitate the final discharge of qualified tail gas.

[0015] Preferably, it further includes a water supply module, and the water supply module supplies water to the digestion tank, reaction tank, product conveying module, and tube bundle demister through pipelines.

[0016] By adopting the above technical solution, the water supply module can supply water to the digestion tank through pipelines to assist in the production of lime slurry, make up water for the reaction tank to ensure its stable water level, supply water to the product conveying module to prevent the slurry in the pipeline from scaling, and supply water to the tube bundle demister to maintain its normal operation, ensuring that all parts of the entire graphite furnace flue gas treatment system can work stably.

[0017] Preferably, it further includes a slurry circulation tank, and a partition is provided in the slurry circulation tank to be able to divide the slurry circulation tank into a first circulation tank and a second circulation tank. The first circulation tank is connected in series to the pipeline of the product conveying module, and the second circulation tank is connected in series to the pipeline of the lime slurry supply module. An overflow hole is provided on the partition to be able to make the upper clear liquid in the first circulation tank flow into the second circulation tank.

[0018] By adopting the above technical solution, the recycling of water and lime slurry can be realized, resource waste can be reduced, and production costs can be lowered.

[0019] Preferably, a cooling cavity filled with coolant is provided inside the shell of the digestion tank. The digestion tank is provided with a liquid inlet and a liquid outlet communicated with the cooling cavity. Both the liquid inlet and the liquid outlet are connected to the coolant circulation system. The coolant circulation system can cool the water discharged from the cooling cavity and return it to the cooling cavity through the liquid inlet. The coolant in the cooling cavity can exchange heat with the lime slurry in the digestion tank.

[0020] By adopting the above technical solution, the reaction of calcium oxide and water in the digestion tank is cooled by the coolant, avoiding phenomena such as sintering and coarser particles of the lime slurry due to too high temperature, which affects the performance, ensuring the quality of the lime slurry and the subsequent reaction effect, and ensuring the stable operation of the entire graphite furnace flue gas treatment system.

[0021] Preferably, the stirring mechanism includes a rotating sleeve, stirring blades and a driving member. The digestion tank includes an upper tank body and a lower tank body. The rotating sleeve is arranged between the upper tank body and the lower tank body and is slidably and sealingly connected to the upper tank body and the lower tank body respectively. The driving member is connected to the rotating sleeve to drive the rotating sleeve to rotate. The rotating sleeve is provided with a stirring rod arranged along its radial direction so that the stirring rod can rotate synchronously with the rotating sleeve. The stirring blades are fixedly arranged at one end of the stirring rod inserted into the rotating sleeve. A guiding ring plate is fixedly arranged on the lower tank body, and a periodically changing guiding groove is formed on the guiding ring plate. A guiding portion capable of sliding along the guiding groove is arranged on the stirring rod so that the stirring rod can rotate with the rotating sleeve and reciprocally slide along the radial direction of the rotating sleeve. The stirring blades are of a "V" type structure with the tip facing the center of the rotating sleeve, and a flow guiding plate is arranged at the front end of the stirring blades along the rotation direction. The flow guiding plate can guide the lime slurry to flow towards the inner wall of the digestion tank.

[0022] By adopting the above technical solution, when calcium oxide reacts with water to generate lime slurry, the driving member drives the rotating sleeve to rotate. While the rotating sleeve rotates, the blades are driven to rotate by the stirring rod, and the lime and water are stirred, so that the lime and water fully react to generate lime slurry, accelerating the mixing of the lime slurry and improving the production efficiency of the lime slurry. When the stirring rod rotates with the rotating sleeve, the guiding portion slides along the guiding groove, so that the stirring rod reciprocally slides along the radial direction of the rotating sleeve. When the stirred slurry moves towards the inner wall of the digestion tank, the stirring blades push the lime slurry towards the inner wall of the digestion tank, improving the heat exchange intensity between the lime slurry and the cooling liquid and the production quality of the lime slurry. Moreover, the reciprocating sliding of the stirring blades increases the stirring effect of the stirring blades on the lime slurry and improves the production efficiency of the lime slurry. The stirring blades are arranged in a "V" type structure, so that the stirring blades move towards the center of the digestion tank, and the lime slurry flows along the hypotenuse of the stirring blades to both sides of the stirring blades, reducing the amount of lime slurry pushed by the stirring blades to the center of the digestion tank and effectively avoiding the occurrence of the phenomenon of heat concentration caused by the concentration of lime slurry.

[0023] A graphite furnace flue gas treatment process, using the described graphite furnace flue gas treatment system, includes: Flue gas flow process: The flue gas supply module passes the flue gas generated by the graphite furnace into the reaction pool at the bottom of the absorption tower. The flue gas reacts with the water in the reaction pool, and the flue gas after passing through the water flows towards the top of the absorption tower and is discharged to the tail gas treatment module through the top of the absorption tower for purification treatment; The process of lime slurry absorbing flue gas: The lime slurry supply module transports the lime slurry to the spraying module, and the spraying module sprays the lime slurry towards the bottom of the absorption tower. The lime slurry contacts and reacts with the flue gas after passing through the water, and then falls into the reaction pool to react with the sulfur-containing components in the water to form solids; The process of discharging precipitates: The product conveying module transports the solids generated in the reaction pool to the product treatment module for solid-liquid separation.

[0024] By adopting the above technical solution, passing the flue gas into the water in the reaction pool at the bottom of the absorption tower can dissolve part of SO2, SO3 and remove impurities such as dust, reducing interference in subsequent reactions. The moistened flue gas contacts 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 pool and continues to react with the dissolved sulfides, extending the reaction time. The reaction products in the reaction pool are transported by the product conveying module to the product treatment module for solid-liquid separation. The flue gas in the absorption tower after contacting the lime slurry enters the tail gas treatment module for purification treatment, making the desulfurization more thorough, improving the desulfurization efficiency of the graphite furnace flue gas, and realizing the solid-liquid separation of the reaction products and the purification of the tail gas, ensuring that the discharged tail gas meets the regulations.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: 1. The flue gas first contacts the water in the reaction pool, which can dissolve part of SO2, SO3, remove impurities such as dust and reduce interference in subsequent reactions. Then, the moistened flue gas contacts the sprayed lime slurry, and the sprayed lime slurry falls into the reaction pool and continues to react with the dissolved sulfides, realizing multi-stage reactions, enabling SO2 and SO3 to be absorbed multiple times, thereby improving the desulfurization efficiency; 2. The absorption towers in the absorption tower group are connected in series in sequence, performing multi-stage treatment on the flue gas, enabling SO2 and SO3 to be absorbed multiple times, making the desulfurization more complete, significantly reducing the content of SO2 and SO3 gases in the flue gas, and improving the flue gas treatment effect; 3. The lime slurry obtains a higher oxygen content. When reacting with acidic gases such as SO2 and SO3 in the flue gas, it can promote the faster oxidation of sulfurous acid into sulfuric acid, thereby more efficiently generating calcium sulfate precipitates, accelerating the desulfurization reaction process, and further improving the desulfurization effect on the graphite furnace flue gas. Description of the Drawings

[0026] Figure 1 is a flowchart of a graphite furnace flue gas treatment system according to an embodiment of the present application.

[0027] Figure 2 It is a flow chart showing the absorption tower group.

[0028] Figure 3 It is a flow chart showing the tail gas treatment module.

[0029] Figure 4 It is a flow chart showing the lime slurry supply module.

[0030] Figure 5 It is a schematic structural diagram showing the digestion tank.

[0031] Figure 6 It is a top view showing the digestion tank.

[0032] Figure 7 It is along Figure 6 The sectional view taken along line A-A in

[0033] Figure 8 It is Figure 5 The enlarged view of part B in

[0034] Figure 9 It is Figure 7 The enlarged view of part C in

[0035] Figure 10 It is a schematic structural diagram for showing the cooperation between the sliding part and the slide rail frame.

[0036] Figure 11 It is a flow chart showing the product conveying module and the oxidation module.

[0037] Figure 12 It is a flow chart showing the product treatment module.

[0038] Figure 13 It is a flow chart showing the water supply module.

[0039] Description of the reference numerals: 1. Flue gas supply module; 11. Flue gas supply pipe; 12. Induced draft fan; 2. Lime slurry supply module; 21. Lime silo; 22. Digestion tank; 221. Upper tank body; 222. Lower tank body; 223. Cooling chamber; 224. Liquid outlet; 225. Liquid inlet; 23. Arch-breaking air cannon; 24. Manual slide valve; 25. Electric star-shaped discharge valve; 26. Stirring mechanism; 261. Rotating sleeve; 262. Stirring paddle; 263. Driving member; 2631. Driving motor; 2632. Driving gear; 2633. Ring gear; 264. Stirring rod; 2651. Guide groove; 2652. Support ring; 2653. Support frame; 2654. Slide rail frame; 2655. Sliding part; 267. Guide ring plate; 2671. Guide groove; 2672. Guide part; 2673. Roller; 268. Deflector; 27. Frame body; 3. Absorption tower group; 31. Absorption tower; 32. Reaction tank; 33. Spraying module; 34. Tube bundle demister; 4. Slurry circulation tank; 41. Partition board; 42. First circulation tank; 43. Second circulation tank; 44. Overflow hole; 45. Circulation pump; 5. Product delivery module; 51. Slurry discharge pump; 6. Product treatment 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 manners

[0040] The following further elaborates on this application Figure 1-13 in conjunction with the appended drawings.

[0041] An embodiment of this application discloses a graphite furnace flue gas treatment system.

[0042] Referring to Figure 1 , a graphite 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 delivery module 5, a product treatment module 6, a tail gas treatment module 7, an oxidation module 8, a water supply module 9, and a slurry circulation tank 4.

[0043] Referring to 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 smoke outlet of the graphite 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 on the flue gas supply pipe 11, so that the flue gas generated by the graphite furnace is introduced into the absorption tower 31.

[0044] Referring to Figure 2, the number of the absorption towers 31 in the absorption tower group 3 is three. The three absorption towers 31 are arranged in parallel and are respectively a primary absorption tower 31, a secondary absorption tower 31, and a tertiary absorption tower 31. The flue gas passes through the three absorption towers 31 in sequence and then enters the tail gas treatment module 7. Specifically, a reaction pool 32 filled with water is formed at the bottom of each absorption tower 31. The flue gas supply pipe 11 is connected to the reaction pool 32 in the absorption tower 31 located at the most upstream, and the outlet of the flue gas supply pipe 11 is located below the liquid level in the reaction pool 32. The top of the primary absorption tower 31 is connected to the reaction pool 32 in the secondary absorption tower 31 through a pipeline, and the top of the secondary absorption tower 31 is connected to the reaction pool 32 of the tertiary absorption tower 31 through a pipeline, so that the flue gas passes through the three absorption towers 31 in sequence and then enters the tail gas treatment module 7. When the flue gas passes through the water in the reaction pool 32, SO2 and SO3 in the flue gas react with water to form sulfurous acid and sulfuric acid, and impurities such as dust in the flue gas remain in the water. The un-dissolved SO2 and other gases rise with the flue gas.

[0045] Refer to Figure 2 , a spraying module 33 is provided in each absorption tower 31. The spraying module 33 is located above the reaction pool 32. The spraying module 33 includes a plurality of spray heads, and the nozzles of the spray heads face the reaction pool 32. The spraying module 33 sprays the lime slurry downward, and a reaction occurs between the falling lime slurry and the rising flue gas: SO2 + Ca(OH)2 → CaSO3↓ + H2O SO3 + Ca(OH)2 → CaSO4↓ + H2O 2CaSO3 + O2 → 2CaSO4 Thus, it reacts with SO2 and SO3 in the flue gas to remove SO2 and SO3 in the flue gas. 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 absorption tower 31 located at the most downstream enters the tail gas treatment module 7 for purification treatment.

[0046] When the lime slurry falls into the water in the reaction pool 32, the chemical reactions that occur are: H2SO3 + Ca(OH)2 → CaSO3↓ + 2H2O H2SO4 + Ca(OH)2 → CaSO4↓ + 2H2O The precipitates generated by the reaction precipitate in the reaction pool 32, and the product treatment module 6 discharges the precipitates and water from the absorption tower 31. The flue gas first contacts the water in the reaction pool 32, which can dissolve part of SO2 and SO3, remove impurities such as dust, and reduce interference in subsequent reactions. Then, the moistened flue gas contacts the sprayed lime slurry, and the sprayed lime slurry falls into the reaction pool 32 and continues 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.

[0047] Reference Figure 2 In the three - stage absorption tower 31, a tube - type demister 34 is provided. The tube - type demister 34 is arranged above the spray module 33 of the absorption tower 31. It can use the tube - type demister 34 to remove the fog and droplets in the flue gas flowing towards the top of the absorption tower 31, further improve the cleanliness of the flue gas, reduce the pollutants carried in the flue gas, make the quality of the flue gas entering the tail - gas treatment module 7 better, and is conducive to finally discharging the tail gas that meets the regulations.

[0048] Reference Figure 3 In this embodiment, the tail - 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 tail gas meet the regulations.

[0049] Reference Figure 4 In this embodiment, the lime slurry supply module 2 includes a lime silo 21 and a digestion tank 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 vehicle unloading. At the same time, there are multiple feeding openings at the lower part of the lime silo 21, and arch - breaking air cannons 23, which are clog - clearing devices, are installed at the feeding openings to prevent material accumulation. The feeding opening at the bottom of the lime silo 21 is connected to the inlet of the digestion tank 22 through a pipeline, and a manual slide valve 24 and an electric star - type discharge valve 25 are connected in series on this section of the pipeline. Lime powder enters the digestion tank 22 through the electric star - type discharge valve 25.

[0050] Reference Figure 5 、 Figure 6 and Figure 7, in this embodiment, the digestion tank 22 is of a rotary structure. A lime feed port, a water inlet, and an exhaust port are respectively provided at the top of the digestion tank 22. A stirring mechanism 26 is arranged inside the digestion tank 22. The stirring mechanism 26 stirs the lime raw material and water to produce lime slurry. The digestion tank 22 includes an upper tank body 221 and a lower tank body 222, and both the upper tank body 221 and the lower tank body 222 are fixedly connected to the frame body 27. Cooling cavities 223 filled with coolant are arranged in both the upper tank body 221 and the lower tank body 222. The cooling cavities 223 are arranged in a circle along the circumferential direction of the digestion tank 22. The coolant in this embodiment is cooling water. Liquid inlet ports 225 and liquid outlet ports 224 communicating with the cooling cavities 223 are provided on both the upper tank body 221 and the lower tank body 222. Both the liquid inlet ports 225 and the liquid outlet ports 224 are connected to the coolant circulation system. In the coolant circulation system, the cooling water is cooled by air cooling. The cooling water in the cooling cavity 223 exchanges heat with the lime slurry and then heats up. The heated cooling water enters the coolant circulation system through the liquid outlet port 224. The fan cools the heated cooling water, and the cooled cooling water enters the cooling cavity 223 through the liquid inlet port 225 to cool the lime slurry, thereby realizing the cooling of the lime slurry by the circulation of the cooling water. The reaction between calcium oxide and water in the digestion tank 22 is cooled by the circulation of the cooling water, avoiding phenomena such as sintering and coarsening of particles of the lime slurry due to too high temperature, which affects the performance, ensuring the quality of the lime slurry and the subsequent reaction effect, and ensuring the stable operation of the entire graphite furnace flue gas treatment system.

[0051] Refer to Figure 7 , Figure 8 , in this embodiment, the stirring mechanism 26 includes a rotating sleeve 261, stirring blades 262, and a driving member 263. The rotating sleeve 261 is arranged between the upper tank body 221 and the lower tank body 222. Grooves are formed at both the upper and lower ends of the rotating sleeve 261. The upper tank body 221 and the lower tank body 222 are respectively inserted into the corresponding grooves, so that the rotating sleeve 261 is slidably and sealingly connected to the upper tank body 221 and the lower tank body 222. In this embodiment, the driving member 263 includes a driving motor 2631, a driving gear 2632, and a gear ring 2633. The gear ring 2633 is arranged on the outer side wall of the rotating sleeve 261 along the circumferential direction of the rotating sleeve 261. The driving motor 2631 is fixedly connected to the frame body 27. The driving gear 2632 is coaxially and fixedly installed on the output shaft of the driving motor 2631 and is externally meshed with the gear ring 2633, so that the driving motor 2631 drives the rotating sleeve 261 to rotate.

[0052] Refer to Figure 7 , Figure 9 and Figure 10, the rotating sleeve 261 is provided with stirring rods 264 arranged along its radial direction. The number of the stirring rods 264 is several, and the several stirring rods 264 are evenly spaced along the circumferential direction of the rotating sleeve 261. The stirring blades 262 correspond to the stirring rods 264 one by one and are fixedly arranged at one end of the stirring rods 264 located in the digestion tank 22. At the upper edge of the inner side wall of the upper tank body 221, a guide groove 2651 is fixedly provided. The guide groove 2651 is arranged in a circle along the circumferential direction of the upper tank body 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 frames 2653 correspond to the stirring rods 264 one by one. A slide rail frame 2654 arranged along the radial direction of the rotating sleeve 261 is fixedly provided at the bottom of the support frame 2653. A space for the stirring blade 262 to slide is left in the slide rail frame 2654. A sliding part 2655 that slides on the slide rail frame 2654 is provided on the stirring rod 264, so that the slide rail frame 2654 provides support for the sliding of the stirring rod 264 and improves the sliding stability of the stirring rod 264.

[0053] Refer to Figure 5 , Figure 8 , a guide ring plate 267 is fixedly provided on the frame body 27. The guide ring plate 267 is sleeved on the digestion tank 22. A periodically changing guide groove 2671 is formed on the guide ring plate 267. In this embodiment, the trajectory of the guide groove 2671 after being unfolded is a sine curve. The head and tail of the guide groove 2671 are connected. A guide part 2672 that slides along the guide groove 2671 is provided on the stirring rod 264. A roller 2673 is sleeved on the guide part 2672. The rolling of the roller 2673 along the groove wall of the guide groove 2671 is used to replace sliding, so as to reduce the friction between the guide part 2672 and the groove wall of the guide groove 2671.

[0054] Refer to Figure 10 , the stirring blade 262 is a "V"-shaped structure with the tip facing the center of the rotating sleeve. And a flow guide plate 268 is provided at the front end of the stirring blade 262 along its rotation direction. The flow guide plate 268 is integrally formed with the stirring blade 262. The flow guide plate 268 is inclined towards the side away from the inner wall of the digestion tank 22 along the rotation direction of the stirring blade 262, so that the flow guide plate 268 can guide the lime slurry to flow towards the inner wall of the digestion tank 22.

[0055] When calcium oxide reacts with water to form lime slurry, the driving member 263 drives the rotating sleeve to rotate. While the rotating sleeve 261 rotates, the stirring rod 264 drives the paddle to rotate, stirring the lime and water, enabling the lime and water to fully react to form lime slurry, accelerating the mixing of the lime slurry, and improving the production efficiency of the lime slurry. When the stirring rod 264 rotates along with the rotating sleeve 261, the guiding portion 2672 slides along the guiding groove 2671, causing the stirring rod 264 to reciprocate radially along the rotating sleeve 261. When the stirred slurry moves towards the inner wall of the digestion tank 22, the stirring paddle 262 pushes the lime slurry towards the inner wall of the digestion tank 22, enhancing the heat exchange intensity between the lime slurry and the coolant, improving the production quality of the lime slurry. Moreover, the reciprocating sliding of the stirring paddle 262 increases the stirring effect of the stirring paddle 262 on the lime slurry, improving the production efficiency of the lime slurry. The stirring paddle 262 is arranged in a "V" shape, causing the stirring paddle 262 to move towards the center of the digestion tank 22. The lime slurry flows along the hypotenuse of the stirring paddle 262 to both sides of the stirring paddle 262, reducing the amount of lime slurry pushed by the stirring paddle 262 to the center of the digestion tank 22, effectively avoiding the phenomenon of heat concentration caused by the concentration of lime slurry.

[0056] Referring to Figure 11 , the slurry circulation tank 4 corresponds to the absorption tower 31 one by one. A partition 41 is provided in the slurry circulation tank 4. In this embodiment, the number of partitions 41 is two, and the two partitions 41 are arranged at intervals. The partition 41 divides 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 digestion tank 22 flows into the second circulation tank 43 through a pipeline. The lime slurry in the second circulation tank 43 is transported to the spraying module 33 for spraying through a pipeline and a circulation pump 45.

[0057] Referring to Figure 11 , the oxidation module 8 includes an oxidation blower 81. The oxidation blower 81 introduces gas into the second circulation tank 43 through a pipeline to increase the oxygen content in the lime slurry, enabling the lime slurry to obtain a higher oxygen content. When reacting with acidic gases such as SO2 and SO3 in the flue gas, it can promote the faster oxidation of sulfurous acid into sulfuric acid, thereby more efficiently generating calcium sulfate precipitation and accelerating the desulfurization reaction process, further enhancing the desulfurization effect on the flue gas of the graphitization furnace.

[0058] Referring to 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 pipeline. The precipitate precipitates in the first circulation tank 42 and forms supernatant liquid in the first circulation tank 42. An overflow hole 44 is provided on the partition 41. The liquid level in the second circulation tank 43 is lower than the height of the overflow hole 44, enabling the supernatant liquid in the first circulation tank 42 to flow into the second circulation tank 43, realizing the recycling of water and lime slurry, reducing resource waste, and lowering production costs.

[0059] Referring to Figure 11 , the product conveying module 5 includes a slurry discharge pump 51. The slurry discharge pump 51 is a slurry pump. The inlet of the slurry discharge pump 51 is inserted into the bottom of the first circulation tank 42 through a pipeline to suck out the sediment at the bottom of the first circulation tank 42. The outlet of the slurry discharge pump 51 is connected to the product treatment module 6 through a pipeline to convey the sediment in the first circulation tank 42 to the product treatment module 6.

[0060] Referring to Figure 12 , the product treatment module 6 includes a hydrocyclone 61 and a vacuum drying device 62. The sediment conveyed by the slurry discharge pump 51 enters the hydrocyclone 61 for gas-liquid separation. The separated liquid flows back into the second circulation tank 43, and the separated liquid 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 sediment spreads on the belt filter 621 after being sealed and transformed and enters the vacuum drying area along with the filter belt; the vacuum pump 622 continuously sucks the system gas through the gas-liquid separator 623 to maintain a low-pressure environment in the hood, so that the moisture of the material evaporates at low temperature; the steam-containing gas flow enters the vacuum pump 622 after the liquid water is intercepted by the gas-liquid separator 623, and the separated condensate is collected and discharged; the dried material is conveyed and discharged by the belt, and the moisture is removed from the system along with the gas flow to achieve continuous vacuum low-temperature drying.

[0061] Referring to Figure 13 , the water supply module 9 includes a water tank 91 and a water pump 92. The water pump 92 supplies water in the water tank 91 to the digestion tank 22, the reaction tank 32, the product conveying module 5 and the tube bundle demister 34 through pipelines, supplies water to the digestion tank 22 to assist in producing lime slurry, replenishes water to the reaction tank 32 to ensure its stable water level, supplies water to the product conveying module 5 to prevent the slurry in the pipeline from scaling, and supplies water to the tube bundle demister 34 to maintain its normal operation, ensuring that all parts of the entire graphitization furnace flue gas treatment system can work stably.

[0062] The implementation principle of a graphitization furnace flue gas treatment system according to an embodiment of the present application is as follows: the flue gas is first passed through the water in the reaction tank 32 to dissolve part of SO2 and SO3 and remove impurities such as dust, reducing the interference of subsequent reactions. The humidified flue gas contacts 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 stored water in the reaction tank 32 and continues to react with the dissolved sulfides to extend the reaction time. Through multiple-stage reactions, SO2 and SO3 are absorbed multiple times, making the desulfurization more thorough and improving the desulfurization efficiency of the graphitization furnace flue gas.

[0063] An embodiment of the present application discloses a graphitization furnace flue gas treatment process.

[0064] A flue gas treatment process for a graphitization furnace, using the above-mentioned flue gas treatment system for a graphitization furnace, includes: Flue gas flow process: The flue gas supply module 1 passes the flue gas generated by the graphitization furnace into the reaction pool 32 at the bottom of the first-stage absorption tower 31. The flue gas reacts with the water in the reaction pool 32. The reacted flue gas flows to the top of the first-stage absorption tower 31 and is passed into the reaction pool 32 at the bottom of the second-stage absorption tower 31, where it reacts with water again. The flue gas after passing through water is passed into the reaction pool 32 in the third-stage absorption tower 31 again through the top of the second-stage absorption tower 31. The flue gas after passing through water enters the tail gas treatment module 7 through the third-stage absorption tower 31 for purification treatment.

[0065] Process of lime slurry absorbing flue gas: The lime slurry supply module 2 transports the lime slurry to the spray modules 33 of the first-stage absorption tower 31, the second-stage absorption tower 31, and the third-stage absorption tower 31. The spray modules 33 spray the lime slurry towards the bottom of the absorption tower 31. The lime slurry first contacts and reacts with the flue gas after passing through water, and then falls into the reaction pool 32 to react to form CaSO3 / CaSO4 precipitate. The precipitate and water in the reaction pool 32 enter the first circulation pool 42 of the slurry circulation pool 4 through a pipeline for precipitation. The upper clear water overflows into the second circulation pool 43, where it is mixed with the lime slurry coming from the lime slurry supply module 2 and then transported to the spray module 33 for spraying through the circulation pump 45.

[0066] Precipitate discharging process: The precipitate transported by the slurry discharge pump 51 enters the cyclone 61 for gas-liquid separation. The separated liquid flows back to the second circulation pool 43, and the separated solid enters the vacuum drying device 62. The vacuum drying device 62 uses the belt filter 621, the vacuum pump 622, and the gas-liquid separator 623 to dry the precipitate to obtain gypsum.

[0067] The above are all the preferred embodiments of this application, and the protection scope of this application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A graphitization furnace flue gas treatment system, characterized in that: It 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 treatment module (6), and a tail gas treatment module (7). A reaction pool (32) filled with water is formed at the bottom of each absorption tower (31) in the absorption tower group (3). The flue gas supply module (1) can introduce flue gas into the reaction pool (32). After the flue gas contacts the water in the reaction pool (32), it flows towards the top of the absorption tower (31). A spraying module (33) is provided in the absorption tower (31), and the spraying module (33) is arranged above the reaction pool (32). The lime slurry supply module (2) can transport lime slurry to the spraying module (33), and the spraying module (33) can spray the lime slurry towards the reaction pool (32). The product conveying module (5) can transport the reaction products in the reaction pool (32) to the product treatment module (6), and the product treatment module (6) separates the solid and liquid of the reaction products. The tail gas treatment module (7) is connected to the absorption tower (31) to purify the flue gas discharged from the absorption tower (31).

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 in the flue gas flow pipeline in sequence, and the flue gas discharged from the upstream absorption tower (31) is introduced into the reaction pool (32) of the downstream absorption tower (31).

3. The graphitization furnace flue gas treatment system according to claim 1, wherein: An oxidation module (8) is connected in series between the lime slurry supply module (2) and the spraying module (33) so that the lime slurry transported to the spraying 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 1, characterized in that: The lime slurry supply module (2) includes a lime silo (21) and a digestion tank (22). The lime silo (21) transports lime raw materials into the digestion tank (22) through a pipeline. The digestion tank (22) is equipped with a stirring mechanism (26) that can stir the lime raw materials and water to produce lime slurry.

5. The graphitization furnace flue gas treatment system according to claim 2, wherein: A tube bundle demister (34) is provided in the absorption tower (31), and the tube bundle demister (34) is located above the spraying module (33). The flue gas flowing towards the top of the absorption tower (31) can flow through the tube bundle demister (34).

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

7. The graphitization furnace flue gas treatment system according to claim 1, wherein: It further includes a slurry circulation tank (4), and a partition plate (41) is arranged in the slurry circulation tank (4) so as to be able 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 to the pipeline of the product delivery module (5), and the second circulation tank (43) is connected in series to the pipeline of the lime slurry supply module (2). An overflow hole (44) is formed in the partition plate (41) so as to be able to enable the supernatant liquid in the first circulation tank (42) to flow into the second circulation tank (43).

8. A graphitization furnace flue gas treatment system according to claim 4, characterized in that: A cooling cavity (223) filled with coolant is arranged inside the housing of the digestion tank (22). The digestion tank (22) is provided with a liquid inlet (225) and a liquid outlet (224) that communicate with the cooling cavity (223). Both the liquid inlet (225) and the liquid outlet (224) are connected to a coolant circulation system. The coolant circulation system can cool the water discharged from the cooling cavity (223) and return it to the cooling cavity (223) through the liquid inlet (225). The coolant in the cooling cavity (223) can exchange heat with the lime slurry in the digestion tank (22).

9. The graphitization furnace flue gas treatment system according to claim 8, characterized in that: The stirring mechanism (26) includes a rotating sleeve (261), stirring blades (262), and a driving member (263). The digestion tank (22) includes an upper tank body (221) and a lower tank body (222). The rotating sleeve (261) is arranged between the upper tank body (221) and the lower tank body (222) and is respectively connected to the upper tank body (221) and the lower tank body (222) in a sliding and sealing manner. The driving member (263) is connected to the rotating sleeve (261) so as to be able to drive the rotating sleeve (261) to rotate; A stirring rod (264) arranged along the radial direction of the rotating sleeve (261) penetrates through the rotating sleeve (261) so that the stirring rod (264) can rotate synchronously with the rotating sleeve (261). The stirring blades (262) are fixedly arranged at one end of the stirring rod (264) inserted into the barrel of the rotating sleeve (261). A guiding ring plate (267) is fixedly arranged on the lower tank body (222). A periodically changing guiding groove (2671) is formed in the guiding ring plate (267). A guiding portion (2672) capable of sliding along the guiding groove (2671) is arranged on the stirring rod (264) so that the stirring rod (264) can rotate with the rotating sleeve (261) and reciprocally slide along the radial direction of the rotating sleeve (261); The stirring blades (262) are in a "V" - shaped structure with the tip facing the center of the rotating sleeve (261), and a flow - guiding plate (268) is arranged at the front end of the stirring blades (262) along the rotation direction of the stirring blades (262). The flow - guiding plate (268) can guide the lime slurry to flow towards the inner wall of the digestion tank (22).

10. A process for treating the flue gas of a graphitization furnace, using a graphitization furnace flue gas treatment system according to any one of claims 1-9, characterized in that: It includes: Flue gas flow process: The flue gas generated by the graphitization furnace is introduced into the reaction pool (32) at the bottom of the absorption tower (31) by the flue gas supply module (1). The flue gas reacts with the water in the reaction pool (32), and the flue gas after passing through the water flows towards the top of the absorption tower (31) and is discharged from the top of the absorption tower (31) to the tail gas treatment module (7) for purification treatment; Process of lime slurry absorbing flue gas: The lime slurry supply module (2) transports the lime slurry to the spraying module (33). The spraying module (33) sprays the lime slurry towards the bottom of the absorption tower (31). The lime slurry reacts with the flue gas after passing through the water, and then falls into the reaction pool (32) to react with the sulfur-containing components in the water to form solids; Precipitate discharging process: The product conveying module (5) transports the solids generated in the reaction pool (32) to the product treatment module (6) for solid-liquid separation.

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