Flue gas desulfurization and denitrification sewage treatment equipment and method

Abstract

The invention relates to the technical field of sewage treatment, and discloses flue gas desulfurization and denitrification sewage treatment equipment and a flue gas desulfurization and denitrification sewage treatment method. The flue gas desulfurization and denitrification sewage treatment equipment comprises a sedimentation tank, a mixing unit, an agent adding unit and a filtering separation unit, a first reaction zone, a second reaction zone and a precipitation separation zone are arranged in the sedimentation tank, the upper end of the first reaction zone is communicated with the second reaction zone, and the lower end of the second reaction zone is communicated with the precipitation separation zone; a partition plate is arranged in the first reaction area, and a conical flow guide hopper is arranged on the partition plate. Aiming at the problems that the charge neutralization effect in the flue gas desulfurization and denitrification high-salinity wastewater is severely weakened and the conventional mixing efficiency is low, the invention adopts an innovatively designed partitioned and graded mixing system, namely high-speed forced mixing in a lower treatment region, diversion vortex transition, low-speed reaction in an upper treatment region and a second reaction region, and a dynamic synergistic agent adding technology. The dual inhibition of the high-salt environment on the physical and chemical treatment process is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and more specifically, it relates to a flue gas desulfurization and denitrification sewage treatment device and method. Background Art

[0002] The sewage generated from flue gas desulfurization and denitrification mainly refers to the wastewater produced in industrial facilities such as thermal power plants and steel plants during the processes of wet flue gas desulfurization (such as limestone-gypsum method) and selective catalytic reduction denitrification for removing sulfur dioxide and nitrogen oxides in flue gas. The main characteristics of this kind of sewage are complex composition, high pollutant concentration, and great treatment difficulty.

[0003] In the treatment of flue gas desulfurization and denitrification wastewater, as the core unit of pretreatment, the neutralization sedimentation tank mainly relies on the cooperation of chemical coagulation and physical sedimentation to remove heavy metals, suspended solids and large particle pollutants. However, such wastewater usually contains extremely high concentrations of salts (the Cl⁻ concentration generally reaches 10 - 30 g / L), and the high ionic strength severely compresses the double electric layer of colloidal particles, significantly reducing the absolute value of its potential, resulting in a significant weakening of the charge neutralization effect of traditional aluminum salt / iron salt coagulants. More critically, the strong ionic interference brought by the high-salt environment not only weakens the chemical coagulation efficiency, but also affects the physical mixing process. For example, the conventional single-rate stirring mixing method is difficult to achieve rapid and uniform dispersion of the medicament in the viscous and high-salt system in a short time, and the low mixing efficiency further restricts the exertion of the limited charge neutralization effect and the effective formation and growth of subsequent flocs, ultimately leading to poor overall flocculation sedimentation effect and increased medicament consumption. Summary of the Invention

[0004] The purpose of the present invention is to provide a flue gas desulfurization and denitrification sewage treatment device and method to solve the above-mentioned technical problems.

[0005] The present invention solves the above-mentioned existing technical problems through the following technical solutions: The present invention provides a flue gas desulfurization and denitrification sewage treatment device, including: a sedimentation tank, a mixing unit, a medicament dosing unit and a filtration and separation unit, characterized in that: A first reaction zone, a second reaction zone and a sedimentation and separation zone are provided in the sedimentation tank, the upper end of the first reaction zone is connected to the second reaction zone, and the lower end of the second reaction zone is connected to the sedimentation and separation zone; A partition plate is provided in the first reaction zone, a conical diversion hopper is provided on the partition plate, a double spiral diversion vane is provided in the diversion hopper, and the partition plate divides the first reaction zone into an upper treatment zone and a lower treatment zone; The mixing unit includes a first stirring component disposed in the upper treatment area, a second stirring component disposed in the second reaction area, and a stirring and mixing component disposed in the lower treatment area. The stirring and mixing component is drivingly connected to the first stirring component through a variable-speed connection component; Wherein, the variable-speed connection component is configured to: make the rotation speed of the stirring and mixing component higher than that of the first stirring component.

[0006] Preferably, the variable-speed connection component includes a bevel gear set that meshes with each other. The bevel gear set converts the input rotation speed of the first stirring component into the output rotation speed of the stirring and mixing component, and the output rotation speed is 2-3 times the input rotation speed.

[0007] Preferably, the bevel gear set includes a protective shell fixed to the bottom of the partition plate, a first bevel gear rotating in the protective shell, and two meshing second bevel gears. The rotating end of the first bevel gear is connected to the bottom end of the corresponding stirring body. One of the second bevel gears meshes with the first bevel gear, and the other second bevel gear is connected to the top end of the mixing and stirring component.

[0008] Preferably, the first stirring component and the second stirring component include a driving source and a stirring body, and the length of the stirring body of the first stirring component is less than that of the stirring body of the second stirring component.

[0009] Preferably, the chemical dosing unit includes a first conveying component for conveying chemicals into the first reaction area. A chemical conveying cavity is provided in the stirring body. The first conveying component includes a conveying pipeline communicated with the chemical conveying cavity and a plurality of chemical nozzles uniformly distributed outside the stirring and mixing component. The chemical nozzles are communicated with the chemical conveying cavity.

[0010] Preferably, a plurality of the chemical nozzles are spirally distributed outside the stirring and mixing component, and the chemical nozzles are inclined downward, and the inclination angle is 30-40 degrees.

[0011] Preferably, the stirring and mixing component includes a stirring shaft and two stirring blades fixedly sleeved outside the stirring shaft. A plurality of the chemical nozzles are divided into two groups and are located at the upper and lower ends of the upper stirring blade.

[0012] Preferably, the filtration and separation unit includes a water distribution pipe, a filtration grille, and a V-shaped baffle. The end of the water distribution pipe is communicated with the lower end of the second reaction area, and a plurality of linearly uniformly distributed drainage pipes are communicated with the outside thereof. The baffle is fixed to the bottom of the precipitation reaction area, and the filtration grille is disposed at the upper end of the precipitation reaction area.

[0013] Preferably, a plurality of sludge discharge pipes are provided outside the sedimentation tank, and each sludge discharge pipe is correspondingly disposed at the bottom end of the V-shaped groove of the baffle.

[0014] A method for treating flue gas desulfurization and denitrification sewage includes the following operation steps: S100. The sewage enters the lower treatment area of the first reaction zone, and the stirring and mixing assembly is driven by a variable-speed connecting piece to rotate at a speed higher than that of the first stirring assembly. Meanwhile, a chemical agent is sprayed into the sewage through the chemical agent spray head on the stirring and mixing assembly. S200. The mixed liquid enters the upper treatment area through the conical diversion hopper on the partition plate. S300. Low-speed stirring is carried out in the upper treatment area and the second reaction zone. S400. The sewage enters the sedimentation and separation area for sedimentation and separation.

[0015] The beneficial effects of the present invention are as follows: Aiming at the problems that the charge neutralization effect in the high-salt wastewater of flue gas desulfurization and denitrification is severely weakened and the conventional mixing efficiency is low, through the innovatively designed partitioned and hierarchical mixing system, that is, high-speed forced mixing in the lower treatment area, diversion and vortex transition, and low-speed reaction in the upper treatment area and the second reaction zone, combined with the dynamic cooperative chemical agent dosing technology, the double inhibition of the high-salt environment on the physicochemical treatment process is improved; the rapid and uniform dispersion of the chemical agent in the sewage and the efficient formation and stable growth of flocs are promoted; thus, while reducing the consumption of chemical agents, the flocculation and precipitation efficiency of pollutants is greatly improved. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of a sewage treatment device for flue gas desulfurization and denitrification provided by the present invention; Figure 2 is a schematic structural diagram of a sedimentation tank in a sewage treatment device for flue gas desulfurization and denitrification provided by the present invention; Figure 3 is a side view of a sedimentation tank in a sewage treatment device for flue gas desulfurization and denitrification provided by the present invention; Figure 4 is a schematic structural diagram between a partition plate, a mixing and stirring assembly, and a first conveying assembly in a sewage treatment device for flue gas desulfurization and denitrification provided by the present invention; Figure 5 is a schematic structural diagram of a mixing and stirring assembly in a sewage treatment device for flue gas desulfurization and denitrification provided by the present invention; Figure 6 is a schematic structural diagram inside a sedimentation tank in a sewage treatment device for flue gas desulfurization and denitrification provided by the present invention; Figure 7 is a partial sectional view of a sedimentation tank in a sewage treatment device for flue gas desulfurization and denitrification provided by the present invention.

[0017] In the figure: 1. sedimentation tank; 11. first reaction zone; 12. second reaction zone; 13. sedimentation and separation zone; 14. partition plate; 15. diversion hopper; 2. mixing unit; 21. first stirring assembly; 211. chemical agent delivery cavity; 22. second stirring assembly; 23. variable-speed connection assembly; 231. protective shell; 232. first bevel gear; 233. second bevel gear; 24. stirring and mixing assembly; 3. chemical agent dosing unit; 31. first conveying assembly; 311. conveying pipeline; 312. chemical agent spray head; 32. second conveying assembly; 4. filtration and separation unit; 41. water distribution pipe; 42. filtration grille; 43. baffle plate; 44. drain pipe; 5. sludge discharge pipe. Detailed implementation manners

[0018] The subject matter described herein will now be discussed with reference to example embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein, and the functions and arrangements of the elements discussed can be changed without departing from the scope of protection of the content of this specification. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described for some examples can also be combined in other examples.

[0019] First embodiment Please refer to Figures 1 to 3 , a flue gas desulfurization and denitrification sewage treatment device, comprising: a sedimentation tank 1, a mixing unit 2, a chemical agent dosing unit 3, and a filtration and separation unit 4; a first reaction zone 11, a second reaction zone 12, and a sedimentation and separation zone 13 are provided on the sedimentation tank 1. The upper end of the first reaction zone 11 communicates with the second reaction zone 12, and the lower end of the second reaction zone 12 communicates with the sedimentation and separation zone 13. A sewage inlet pipe communicating with the lower end of the first reaction zone 11 is provided outside the sedimentation tank 1; a partition plate 14 is provided in the first reaction zone 11, a conical diversion hopper is provided on the partition plate 14, double spiral diversion vanes are provided in the diversion hopper 15, and the partition plate 14 divides the first reaction zone 11 into an upper treatment zone and a lower treatment zone.

[0020] The chemical agent dosing unit 3 is used to add required chemical agents to the first reaction zone 11 and the second reaction zone 12; the filtration and separation unit 4 is arranged in the sedimentation and separation zone 13 to precipitate harmful substances in the sewage.

[0021] Specifically, in order to achieve rapid mixing of the medicament and sewage in a short time, the present invention improves the mixing unit 2, specifically as follows: The mixing unit 2 includes a first stirring assembly 21 provided in the upper treatment area, a second stirring assembly 22 provided in the second reaction area 12, and a stirring and mixing assembly 24 provided in the lower treatment area. The stirring and mixing assembly 24 is drivingly connected to the first stirring assembly 21 through a variable-speed connection assembly 23. A double-helix guide vane is provided in the guide funnel 15. The first stirring assembly 21 and the second stirring assembly 22 include a driving source and a stirring body, and the length of the stirring body of the first stirring assembly 21 is less than that of the stirring body of the second stirring assembly 22. The stirring and mixing assembly 24 includes a stirring shaft and two stirring blades fixedly sleeved outside the stirring shaft. The variable-speed connection assembly 23 is configured to make the rotation speed of the stirring and mixing assembly 24 2-3 times higher than that of the first stirring assembly 21.

[0022] When the above equipment is in use, the external sewage first enters the bottom of the first reaction area 11. The driving source drives the stirring body to rotate, thereby stirring the sewage entering the reaction area. When the sewage reaches the preset amount, the medicament dosing unit 3 first adds the medicament into the first reaction area 11. Under the driving action of the stirring body in the first reaction area 11, the variable-speed connection assembly 23 can drive the stirring and mixing assembly 24 to rotate at a speed greater than that of the stirring body. Since the sewage flow rate in the lower treatment area is fast and the fluidity is large, the high-speed rotating stirring and mixing assembly 24 can promote the mixing speed of the sewage and the medicament, thereby realizing efficient mixing of the sewage. The preliminarily mixed sewage flows upward and enters the guide funnel 15. Due to the partition plate 14 forcing the sewage to flow through the guide funnel 15, under the action of the double-helix guide vane inside the guide funnel 15, not only is the vortex generated to strengthen the mixing, but more importantly, the upward flow in the lower treatment area is converted into a rotating upward flow, extending the hydraulic retention time of the sewage in the initial stage of the reaction, ensuring that there is a more sufficient pre-contact opportunity between the medicament and the pollutants before entering the upper treatment area for the main reaction. Subsequently, the sewage flows into the upper treatment area through the top of the conical guide funnel 15. At this time, the sewage and the medicament gradually start to react, and the stirring body in this area rotates at a low speed. The low-speed area avoids the formed flocs from being broken, promotes their growth and compaction, and forms flocs that are more likely to settle, which can just promote the reaction to proceed faster. Then the sewage enters the second reaction area 12 from the upper end of the first reaction area 11. The driving source at this position drives the corresponding stirring body to continue to stir the sewage at a low speed, so that the sewage can better react with the medicament. Then the sewage enters the precipitation and separation area 13 from the lower end of the second reaction area 12, and further precipitation and separation treatment is carried out through the filtration and separation unit 4. The filtered sewage is finally discharged from the end of the precipitation and separation area 13, and the whole preliminary neutralization reaction treatment is completed.

[0023] It can be seen from this that for the problem that the high salinity of flue gas desulfurization and denitrification wastewater inhibits and weakens the charge neutralization ability of traditional coagulants, resulting in poor flocculation effect, the present invention separates the physical mixing enhancement (high-speed stirring zone) from the chemical reaction enhancement (low-speed stirring zone) in terms of time and space. Even in a high-salt environment where the electro-neutralization effect is limited, the stable state of pollutants can be forcibly broken through intense mechanical shearing action (lower treatment zone), promoting the collision and aggregation of colloidal particles, creating favorable conditions for subsequent chemical precipitation. At the same time, the formation path of flocs is optimized. From the forced rapid mixing at the bottom (lower treatment zone), to the vortex disturbance in the middle (deflector 15), and then to the gentle reaction at the upper part (upper treatment zone, second reaction zone 12), an ideal gradient environment is provided for each stage of floc formation. The high-speed zone is conducive to generating a large number of initial micro-flocs, while the low-speed zone avoids the formed flocs from being broken and promotes their growth and densification, forming flocs that are more likely to settle.

[0024] Please refer to Figures 3 to 5 For the purpose of realizing the differential agitation between the first stirring assembly 21 and the agitation mixing assembly 24, the present invention designs the specific structure of the variable-speed connection assembly 23: The variable-speed connection assembly 23 includes a bevel gear set that meshes with each other. The bevel gear set converts the input rotation speed of the first stirring assembly 21 into the output rotation speed of the agitation mixing assembly 24, and the output rotation speed is 2-3 times the input rotation speed. The bevel gear set includes a protective shell 231 fixed to the bottom of the partition plate 14, a first bevel gear 232 rotatable within the protective shell 231, and two meshing second bevel gears 233. The rotating end of the first bevel gear 232 is connected to the bottom end of the corresponding stirring body. One of the second bevel gears 233 meshes with the first bevel gear 232, and the other second bevel gear 233 is connected to the top end of the mixing agitation assembly.

[0025] When the stirring body rotates, its bottom end drives the first bevel gear 232 to rotate. Since the first bevel gear 232 meshes with a second bevel gear 233, and the two second bevel gears 233 mesh with each other, this bevel gear set constitutes a speed-increasing transmission mechanism. Therefore, the rotational speed of the mixing and agitation assembly connected to the other second bevel gear 233 is increased to 2-3 times the rotational speed of the stirring body, achieving synchronous high-speed rotation. By adopting this transmission method, only a single drive source is required to achieve low-speed stirring in the upper treatment area and high-speed stirring in the lower treatment area, without the need to configure an independent drive and control system for the mixing and agitation assembly, effectively reducing the equipment cost and control complexity. Moreover, the mechanical gear meshing transmission structure is simple, strong, and has a low failure rate, strictly ensuring the rigid synchronization between the upper and lower stirring assemblies, that is, the high-speed rotation of the mixing and agitation assembly and the low-speed rotation of the stirring body always maintain a constant speed ratio and start and stop completely synchronously. In addition, the speed-changing mechanism is compactly integrated in the protective housing 231 below the partition plate 14, saving the internal space of the equipment. The protective housing 231 also plays a role in protecting the gears, preventing sewage corrosion and impurity intrusion, improving the equipment life and maintenance convenience.

[0026] Please refer to Figures 3 to 5 , in order to further promote the mixing effect of the medicament and the sewage, the present invention further optimizes and improves the medicament dosing unit 3 on the basis of the above solution: the medicament dosing unit 3 (includes a first conveying assembly 31 and a second conveying assembly 32 that respectively convey the medicament into the first reaction zone 11 and the second reaction zone 12. There is a medicament conveying cavity 211 in the stirring body. The first conveying assembly 31 includes a conveying pipeline 311 communicated with the medicament conveying cavity 211 and a plurality of medicament spray nozzles 312 uniformly distributed outside the stirring and mixing assembly 24. The medicament spray nozzles 312 are communicated with the medicament conveying cavity 211. A plurality of the medicament spray nozzles 312 are spirally distributed outside the stirring and mixing assembly 24. The medicament spray nozzles 312 are inclined downward at an inclination angle of - degrees. A plurality of the medicament spray nozzles 312 are divided into two groups and are located at the upper and lower ends of the upper stirring blades.

[0027] When adding the medicament, the external medicament dispensing device transports the pressurized medicament into the conveying pipeline 311, and then transports it through the conveying pipeline 311 into the medicament conveying cavity 211 of the stirring and mixing assembly 24, and then sprays it out through the short pipe. As the stirring and mixing assembly 24 rotates, the medicament can be quickly distributed in the sewage. Compared with the traditional medicament inlet mode, the medicament is directly sprayed into the core area of the high-shear flow field generated by stirring through multiple inclined short pipes on the high-speed rotating stirring and mixing assembly 24. This design realizes the instantaneous and high-intensity microscopic dispersion of the medicament in the sewage, greatly shortening the path and time for the medicament to diffuse to the surface of the pollutant, which is crucial for overcoming the diffusion resistance of the medicament caused by high salinity and improving the initial reaction rate. In addition, the traditional static dosing point is likely to cause too high local concentration of the medicament, which may lead to ineffective reactions (such as generating insoluble small particles instead of effective flocs) or waste. However, the dynamic multi-point spraying of this solution effectively avoids the local supersaturation phenomenon of the medicament, makes the medicament concentration more uniform in the reaction zone, and improves the utilization efficiency of the medicament.

[0028] Please refer to Figures 6 to 7 , the filtration and separation unit 4 includes a water distribution pipe 41, a filtration grille 42 and a baffle 43. The end of the water distribution pipe 41 communicates with the lower end of the second reaction zone 12, and several linearly evenly distributed drainage pipes 44 are communicated with the outside thereof. By connecting multiple drainage pipes 44 connected to the water distribution pipe 41, it ensures that the sewage enters the entire cross-section of the sedimentation and separation zone 13 evenly and smoothly, avoiding short-circuit flow and too high local flow velocity, creating an ideal flow regime (close to laminar flow) for subsequent gravitational sedimentation, and is a key pre-step to ensure the sedimentation effect and the effluent water quality. The baffle 43 is fixed at the bottom of the sedimentation reaction zone. The V-shaped groove formed by the baffle 43 not only guides the flow direction of the sludge, but its V-shaped structure itself is conducive to the natural collection, compression and concentration of the sludge at the bottom of the groove. The sludge discharge pipe 5 is arranged at the bottom end of the V-shaped groove, which is convenient for efficiently and thoroughly discharging the high-concentration sludge, reducing the sludge accumulation in the sedimentation zone, and maintaining the effective sedimentation volume. The filtration grille 42 is arranged at the upper end of the sedimentation reaction zone. Several sludge discharge pipes 5 are arranged outside the sedimentation tank 1, and each sludge discharge pipe 5 is correspondingly arranged at the bottom end of the V-shaped groove of the baffle 43. The filtration grille 42 is arranged at the upper end of the sedimentation zone. As the last barrier, it effectively intercepts the tiny flocs that may float or the light suspended solids that are not completely sedimented, forming a double separation guarantee mechanism with the gravitational sedimentation at the bottom, further improving the effluent clarity.

[0029] Embodiment 2 As another embodiment of the present invention, the present invention also provides a method for treating sewage using the above sewage treatment equipment, which specifically includes the following steps: Step S100: Forced high-speed mixing and dynamic medicament spraying The sewage enters the lower treatment area of the first reaction zone 11 through the inlet pipe, and the first stirring assembly 21 is started to drive the stirring and mixing assembly 24 to rotate at a high speed of 20 - 50 revolutions per minute; meanwhile, the medicament is injected into the medicament conveying cavity 211 of the stirring and mixing assembly 24 through the conveying pipeline 311, and is dynamically sprayed into the sewage through the inclined short pipes evenly distributed on the outer wall in a spiral pattern; the high-speed shear force forcibly breaks the stable state formed by the compression of the double electric layer of the colloidal particles; the medicament is directly sprayed into the high-turbulence area to overcome the diffusion resistance in the high-salt environment and achieve micro-mixing at the millisecond level.

[0030] Step S200: Eddy current extension and flow pattern transformation The mixed liquid rises to the flow port of the partition plate 14 and is guided by the double spiral guide vanes in the conical diversion hopper 15; the double spiral guide vanes convert the vertical upward flow into a spiral rotating upward flow, and the hydraulic retention time is extended by 30% - 50%; the rotating eddy current promotes the full pre-contact between the medicament and the pollutants, and avoids the disintegration of the micro-flocs formed in the high-speed area due to the sudden drop in flow velocity.

[0031] Step S300: Gradient flocculation and slow growth The sewage enters the upper treatment area, and the first stirring assembly 21 stirs at a low speed of 10 - 20 revolutions per minute; then it flows into the second reaction zone 12, and the second stirring assembly 22 continuously stirs at the same low speed; the low-speed environment reduces the mechanical shear force and protects the micro-flocs from aggregating and growing into dense flocs; the two-stage low-speed reaction zone provides a total flocculation time of 15 - 25 minutes to ensure the maturity of the flocs.

[0032] Step S400: Uniform precipitation and double separation The sewage enters the precipitation and separation zone 13 from the lower end of the second reaction zone 12, and is shunted to multiple drainage pipes 44 through the water distribution pipe 41 to achieve uniform water distribution across the cross-section; under the guidance of the V-shaped baffle 43, the sludge converges to the bottom of the tank and is discharged through the sludge discharge pipe 5; the supernatant is output after the residual suspended solids are intercepted by the filter grille 42; the V-shaped baffle 43 increases the sludge concentration by 40% - 60%; the filter grille 42 intercepts flocs with a particle size > 50 μm, and the turbidity of the effluent ≤ 5 NTU.

[0033] The above describes the embodiments of the present invention, but the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms, all of which fall within the protection scope of the present invention.

Claims

1. A flue gas desulfurization and denitrification sewage treatment device, comprising: The sedimentation tank, mixing unit, reagent dosing unit and filtration separation unit are characterized by: The sedimentation tank is provided with a first reaction zone, a second reaction zone and a sedimentation separation zone, the upper end of the first reaction zone is connected to the second reaction zone, and the lower end of the second reaction zone is connected to the sedimentation separation zone; A partition plate is provided in the first reaction zone, a conical flow guide hopper is provided on the partition plate, a double helical flow guide vane is provided in the flow guide hopper, and the partition plate divides the first reaction zone into an upper processing zone and a lower processing zone; The mixing unit comprises a first stirring assembly arranged in the upper processing zone, a second stirring assembly arranged in the second reaction zone, and a stirring and mixing assembly arranged in the lower processing zone, wherein the stirring and mixing assembly is transmission-connected to the first stirring assembly through a speed-changing connection assembly; Wherein, the speed-changing connection assembly is configured to make the rotation speed of the stirring and mixing assembly higher than the rotation speed of the first stirring assembly.

2. The flue gas desulfurization and denitrification sewage treatment equipment according to claim 1, wherein, The speed-changing connection assembly comprises mutually meshing bevel gear sets, which convert the input rotation speed of the first stirring assembly into the output rotation speed of the stirring and mixing assembly, and the output rotation speed is 2-3 times of the input rotation speed.

3. A flue gas desulfurization and denitrification sewage treatment device according to claim 2, characterized in that, The bevel gear set includes a protective shell fixed to the bottom of the partition plate, a first bevel gear rotating in the protective shell, and two meshing second bevel gears, the rotating end of the first bevel gear is connected to the corresponding bottom end of the stirring body, one of the second bevel gears is meshed with the first bevel gear, and the other second bevel gear is connected to the top of the mixing and stirring component.

4. A flue gas desulfurization and denitrification sewage treatment device according to claim 1, characterized in that, The first stirring component and the second stirring component include a driving source and a stirring body, and the stirring body of the first stirring component is shorter than the stirring body of the second stirring component.

5. The flue gas desulfurization and denitrification sewage treatment equipment according to claim 4, characterized in that, The drug dosing unit includes a first conveying component that conveys the drug to the first reaction zone, a drug delivery chamber is provided in the stirring body, the first conveying component includes a conveying pipe connected to the drug delivery chamber and a plurality of drug nozzles evenly distributed on the outside of the stirring and mixing component, and the drug nozzles are connected to the drug delivery chamber.

6. The flue gas desulfurization and denitrification sewage treatment equipment according to claim 5, characterized in that, A plurality of the medicine spray heads are spirally distributed on the outside of the stirring and mixing component, and the medicine spray heads are tilted downward with an inclination angle of 30-40 degrees.

7. The flue gas desulfurization and denitrification sewage treatment equipment according to claim 6, characterized in that, The stirring and mixing assembly comprises a stirring shaft and two stirring blades fixedly sleeved on the outer side of the stirring shaft, and the plurality of medicine spray heads are divided into two groups, which are located at the upper and lower ends of the stirring blades above.

8. A flue gas desulfurization and denitrification sewage treatment device according to claim 1, characterized in that, The filtration separation unit includes a water distribution pipe, a filter grid and a V-shaped baffle. The end of the water distribution pipe is connected to the lower end of the second reaction zone, and its outer side is connected to a plurality of linearly evenly distributed drainage pipes. The baffle is fixed to the bottom of the precipitation reaction zone, and the filter grid is arranged at the upper end of the precipitation reaction zone.

9. The flue gas desulfurization and denitrification sewage treatment equipment according to claim 8, characterized in that, A plurality of mud discharge pipes are arranged outside the sedimentation tank, and each mud discharge pipe is arranged correspondingly at the bottom end of the V-shaped groove of the baffle.

10. A method for treating flue gas desulfurization and denitrification sewage, using a flue gas desulfurization and denitrification sewage treatment device as described in any one of claims 1-9, characterized in that, The steps include: S100, the sewage enters the lower treatment zone of the first reaction zone, and the stirring and mixing assembly is driven by the speed-changing connection member to rotate at a speed higher than that of the first stirring assembly, and at the same time, the agent is sprayed into the sewage through the agent nozzle on the stirring and mixing assembly; S200, the mixed liquid enters the upper treatment area through the conical guide hopper on the partition plate; S300, the upper treatment zone and the second reaction zone are stirred at a low speed; S400, sewage enters the sedimentation and separation area for sedimentation and separation.

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