Flue gas purification device of strip steel hot galvanizing aluminum magnesium annealing furnace

Abstract

The invention discloses a flue gas purification device of a strip steel hot galvanizing aluminum magnesium annealing furnace, which relates to the technical field of flue gas purification and comprises an annealing furnace exhaust pipe, a quenching treatment unit, a multi-stage purification unit, an exhaust pipe and a circulating liquid system which are sequentially connected along a flue gas flowing direction. According to the invention, through the multi-stage and synergistic purification process of quenching, toxin inhibition and deacidification, turbulent flow enhanced absorption, ultrasonic deep washing, efficient dehydration and demisting and activated carbon adsorption, and in combination with an intelligent fractional precipitation circulating liquid system, efficient, deep and comprehensive purification of the complex flue gas of the strip steel hot-dip galvanizing aluminum magnesium annealing furnace is realized, the pollutant emission concentration is remarkably reduced, and the environmental pollution is reduced. Meanwhile, waste liquid treatment and resource recovery are optimized, the operation cost and the environmental risk are reduced, and the environment-friendly emission standard is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas purification, in particular to a flue gas purification device of a strip steel hot galvanizing zinc-aluminum-magnesium annealing furnace. BACKGROUND

[0002] The annealing furnace is mainly used for annealing of large carbon steel and alloy steel parts. During the annealing process, heavy metals such as zinc, aluminum and magnesium, acidic substances and other harmful substances are discharged together with the flue gas. Therefore, a flue gas purification device is needed to purify the discharged flue gas.

[0003] The existing annealing furnace flue gas purification device has the following defects:

[0004] 1. Patent document US09421494B2 discloses a flue gas purification device, but the device in the above document has the technical problems of single purification process and poor synergy, resulting in incomplete removal of pollutants;

[0005] 2. Patent document US09051863B2 discloses a flue gas purification device, but the device in the above document has the technical problems of low preliminary neutralization and absorption efficiency, and insufficient treatment of heavy metals and acidic gases;

[0006] 3. Patent document US07063817B2 discloses a flue gas purification device, but the device in the above document has the technical problems of weak removal capacity for micron and sub-micron pollutants and liquid, and high humidity content of exhaust air;

[0007] 4. Patent document CN106834622A discloses a flue gas collection and purification device for chemical smelting pipe annealing furnace, but the device in the above document has the technical problems of extensive waste liquid treatment and low resource recovery efficiency. SUMMARY

[0008] The present application aims to provide a flue gas purification device of a strip steel hot galvanizing zinc-aluminum-magnesium annealing furnace to solve the technical problems raised in the background art.

[0009] To achieve the above-mentioned purpose, the present application provides the following technical solution: a flue gas purification device of a strip steel hot galvanizing zinc-aluminum-magnesium annealing furnace, comprising an annealing furnace exhaust pipe, a quenching treatment unit, a multi-stage purification unit, an exhaust pipe and a circulating liquid system connected in sequence along the flue gas flow direction;

[0010] The quenching treatment unit comprises a quenching tower arranged at the output end of the annealing furnace exhaust pipe. The inner wall of the quenching tower is provided with a double-fluid atomizing spray gun. The input end of the double-fluid atomizing spray gun is connected to a liquid medicine tank through a pipeline, and the liquid medicine tank is arranged on the outer wall of the quenching tower. The inside of the liquid medicine tank is filled with nano calcium hydroxide suspension;

[0011] The multi-stage purification unit comprises, in sequence:

[0012] A first turbulent flow absorption tower, an input end of which is connected with an output end of the quenching tower, an inside of the first turbulent flow absorption tower is provided with a Venturi array and a cyclone spray layer structure, and a composite solution of sodium hydroxide and sodium sulfite is sprayed;

[0013] A second ultrasonic washing tower, an input end of which is connected with an output end of the first turbulent flow absorption tower, an inside of the second ultrasonic washing tower is provided with hydrophobic modified porous corrugated fillers and a 1.5 MHz high-frequency ultrasonic atomizer;

[0014] A third cyclone dehydration tower, an input end of which is connected with an output end of the second ultrasonic washing tower, an inside of the third cyclone dehydration tower is provided with a cyclone plate and an electrostatic demister;

[0015] An exhaust pipe, an input end of which is connected with an output end of the third cyclone dehydration tower, and an output end of the exhaust pipe is provided with an activated carbon filter screen;

[0016] The circulating liquid system comprises:

[0017] A graded sedimentation tank, and a plurality of fixed plates are arranged on a top of the graded sedimentation tank, and the fixed plates are respectively arranged on bottoms of the quenching tower, the first turbulent flow absorption tower, the second ultrasonic washing tower and the third cyclone dehydration tower;

[0018] The bottoms of the quenching tower, the first turbulent flow absorption tower, the second ultrasonic washing tower and the third cyclone dehydration tower are respectively provided with blowdown pipes, outer walls of the blowdown pipes penetrate through the tops of the fixed plates, and the outer walls of the blowdown pipes are provided with electromagnetic valves.

[0019] Preferably, the nanometer calcium hydroxide suspension sprayed by the double-fluid atomizing spray gun in the quenching tower is specifically a suspension mixed by 5wt% of sodium hydroxide and 2wt% of nanometer calcium hydroxide, wherein the atomized particle size is <20nm, and the chemical liquid tank is provided with a stirring device and a temperature controller.

[0020] Preferably, the flow velocity of the turbulent flow at the throat of the Venturi array in the first turbulent flow absorption tower is 25-35m / s, and the mass ratio of sodium sulfite in the sodium hydroxide and sodium sulfite composite solution sprayed by the cyclone spray layer is 10-30%.

[0021] Preferably, the hydrophobic modified porous corrugated fillers in the second ultrasonic washing tower have a pore size of 0.5-1mm and a contact angle >150°, and the power density of the 1.5MHz high-frequency ultrasonic atomizer is 0.5-1W / cm 3 , and the generated mist droplet particle size is less than 10μm.

[0022] Preferably, the cyclone plate of the third-stage cyclone dewatering tower has an elevation angle of 25-35° and a plate spacing of 80-120 mm, and the electrostatic precipitator adopts a positive and negative bipolar thorn electrode structure and has a working voltage of 30-50 kV.

[0023] Preferably, the grading sedimentation tank of the circulating liquid system comprises:

[0024] The acid waste liquid zone receives the waste liquid from the quenching tower and controls the pH to be 6-8;

[0025] The metal flocculation zone receives the waste liquid from the first-stage turbulent absorption tower and the second-stage ultrasonic washing tower and adds anionic polyacrylamide with a molecular weight of 8-12 million;

[0026] The clear liquid buffer zone receives the waste liquid from the third-stage cyclone dewatering tower and returns to the ultrasonic atomizer through a ceramic membrane filter with a pore size of 0.1 μm.

[0027] Preferably, the system further comprises a PLC control system, the signal input end of which is connected to the flue gas component sensors arranged at the inlet of the quenching tower, the outlet of the first-stage turbulent absorption tower and the outlet of the exhaust pipe, and the signal output end of which is connected to the flow regulating valves of the double-fluid atomizing lances, the cyclone spray layer and the ultrasonic atomizer.

[0028] Preferably, the activated carbon filter screen of the exhaust pipe has a honeycomb structure, a heating regeneration device is arranged at the upstream of the activated carbon filter screen, a VOCs concentration monitor is arranged at the downstream of the activated carbon filter screen, and the monitoring data is fed back to the PLC control system to trigger the regeneration program.

[0029] Preferably, the working steps of the flue gas purification device of the strip hot galvanizing annealing furnace are as follows:

[0030] S1, flue gas extraction: the high-temperature flue gas containing pollutants is extracted from the annealing furnace through the annealing furnace exhaust pipe and enters the purification system;

[0031] S2, quenching and preliminary purification: the flue gas enters the quenching tower, the double-fluid atomizing lances spray the specific suspension stored in the liquid tank into the tower at high speed, the stirring device of the liquid tank ensures the uniformity of the suspension, the temperature controller maintains the appropriate temperature, the nanoscale mist droplets are mixed with the high-temperature flue gas to achieve rapid cooling, the nanoscale calcium hydroxide particles efficiently adsorb and neutralize the acidic gas, sodium hydroxide provides a strong alkaline environment for catalytic reaction, and part of the particulate matter is captured;

[0032] S3, first-stage turbulent deep absorption: the flue gas pre-treated by quenching enters the first-stage turbulent absorption tower, the flue gas passes through the array of Venturi tubes at high speed to generate strong turbulence, the cyclone spray layer sprays the sodium hydroxide and sodium sulfite compound solution downward, the turbulent effect of the Venturi tube greatly enhances the gas-liquid contact and mass transfer efficiency, the sodium hydroxide efficiently neutralizes the residual acidic gas, and the sodium sulfite removes heavy metals through redox and assists in denitrification;

[0033] S4, secondary ultrasonic deep washing: flue gas enters the secondary ultrasonic washing tower, and a 1.5 MHz high-frequency ultrasonic atomizer is used to atomize the washing liquid into extremely fine liquid droplets with a particle size of <10 μm, the ultrasonic cavitation effect generates local high temperature and high pressure, and the aerosol, emulsified oil mist and difficultly soluble organic matter are broken down by force, the flue gas flows through the hydrophobic modified porous corrugated filler to form a thin liquid film, providing a large gas-liquid contact area, and the ultra-fine mist droplets, filler liquid film and fine particulate matter, aerosol, oil mist, residual pollutants and part of VOCs in the flue gas collide, coagulate, dissolve and wash;

[0034] S5, tertiary cyclone dewatering and fine mist removal: the wet flue gas enters the tertiary cyclone dewatering tower, the flue gas first passes through the cyclone plate, and the rotational centrifugal force throws most of the liquid droplets to the tower wall to achieve mechanical dewatering, and after dewatering, the flue gas passes through the electrostatic mist eliminator, and the high-voltage electrostatic field charges the residual fine mist droplets and submicron particles and traps them on the electrode plate to achieve high-efficiency fine mist removal;

[0035] S6, activated carbon adsorption and emission standard discharge: the dewatered and demisted flue gas enters the exhaust pipe, and the flue gas passes through the honeycomb activated carbon filter screen to adsorb and remove the residual trace VOCs, dioxin precursors and odors in the flue gas, and a VOCs concentration monitor monitors the downstream emission concentration in real time, and the purified clean flue gas is discharged up to the standard;

[0036] S7, treatment and reuse of circulating liquid: the waste liquid generated at the bottom of the quenching tower, the first-stage turbulent absorption tower, the second-stage ultrasonic washing tower and the third-stage cyclone dewatering tower flows into the lower-stage graded sedimentation tank through the blowdown pipe at the bottom thereof;

[0037] S8, zoned treatment in the graded sedimentation tank: acid waste liquid zone: receiving the waste liquid from the quenching tower, controlling the pH to be 6-8, metal flocculation zone: receiving the waste liquid from the first-stage turbulent absorption tower and the second-stage ultrasonic washing tower, adding anionic polyacrylamide with a molecular weight of 8-12 million, flocculating and settling the heavy metal hydroxide suspension, and clear liquid buffer zone: receiving the waste liquid from the third-stage cyclone dewatering tower and the supernatant from the previous two zones, the clear liquid buffer zone waste water is filtered through a ceramic membrane filter, and can be returned to the ultrasonic atomizer of the second-stage ultrasonic washing tower as a washing liquid supplement water source, and the settled sludge is periodically cleaned and disposed;

[0038] S9, intelligent control and regeneration: the PLC control system monitors the pollutant concentration in real time through the flue gas composition sensor, and the PLC dynamically adjusts the spray amount of the double-fluid atomizing spray gun, the cyclone spray layer and the ultrasonic atomizer through the flow regulating valve according to the monitoring data, so as to realize precise control and energy saving. When the VOCs concentration monitor detects that the downstream concentration of the activated carbon exceeds the standard, the data is fed back to the PLC, and the PLC triggers the heating regeneration device to use hot gas to heat and desorb the honeycomb activated carbon filter screen for regeneration, so as to restore its adsorption capacity. The concentrated VOCs desorbed, after regeneration, the system restores the adsorption mode, and the ceramic membrane filter performs backwashing or maintenance according to the pressure difference or time setting.

[0039] Compared with the prior art, the beneficial effects of the present application are:

[0040] 1. The present application realizes high-efficiency, deep and comprehensive purification of complex flue gas of hot galvanizing aluminum magnesium annealing furnace of strip steel by multi-stage and synergistic purification process of quenching, detoxification and deacidification, turbulent flow enhanced absorption, ultrasonic deep washing, high-efficiency dewatering and mist removal, combined with intelligent grading sedimentation circulating liquid system, significantly reduces pollutant emission concentration, optimizes waste liquid treatment and resource recovery, reduces operation cost and environmental risk, and meets environmental protection emission standard;

[0041] 2. The present application sprays superfine nanoscale composite suspension through double-fluid atomizing spray gun in the quenching tower, combines with the stirring and temperature control function of the liquid tank, ensures the activity and dispersion stability of the nanoparticles, significantly improves the efficiency of primary neutralization of acid gas and particle capture, and realizes deep removal of acid gas and reduction and fixation of heavy metals through 25-35 m / s high-turbulence Venturi tube array in the first-stage turbulent absorption tower, so as to lay a high-efficiency pretreatment foundation for subsequent purification links;

[0042] 3. The present application realizes deep purification of submicron aerosol, oil mist and heavy metals through the flow guiding and liquid blocking effect of super-hydrophobic modified porous corrugated filler in the second-stage ultrasonic washing tower, combined with submicron droplets generated by 1.5 MHz high-frequency ultrasonic atomization, and uses the synergistic effect of acoustic cavitation and surface adsorption, realizes deep purification of submicron aerosol, oil mist and heavy metals, and realizes gradient interception of optimized cyclone plate pre-dewatering and bipolar thorn electrostatic precipitator in the third-stage cyclone dewatering tower, so as to efficiently remove residual droplets and fine particles, and ensure ultra-low moisture content and clean emission;

[0043] 4. The present application realizes step-by-step purification and resource recovery of waste liquid through the partitioned targeted treatment of the acid waste liquid area, the metal flocculation area and the clear liquid buffer area of the grading sedimentation tank, optimizes the consumption of reagents in the acid area, accelerates the sedimentation of metal sludge in the flocculation area, and directly returns the high-quality clear liquid produced by ceramic membrane filtration to the ultrasonic atomizer, so as to significantly reduce fresh water consumption and wastewater discharge, and form an efficient and low-consumption circular economy mode. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is a schematic view of the overall structure of the present application;

[0045] Figure 2 is a schematic view of the overall structure of the present application; Figure 1 is a schematic view of the structure at A in the present application;

[0046] Figure 3 is a schematic view of the overall structure of the present application;

[0047] Figure 4 is a schematic view of the overall structure of the present application; Figure 3 is a schematic view of the structure at B in the present application;

[0048] Figure 5 is a schematic view of the overall structure of the present application;

[0049] Figure 6 is a schematic view of the overall structure of the present application;

[0050] Figure 7 is a schematic view of the overall structure of the present application.

[0051] In the figure: 1, annealing furnace exhaust pipe; 2, exhaust pipe; 4, quench tower; 5, double fluid atomizing spray gun; 6, liquid medicine tank; 7, first stage turbulent absorption tower; 8, venturi array; 9, cyclone spray layer; 10, second stage ultrasonic washing tower; 11, porous corrugated packing; 12, ultrasonic atomizer; 13, third stage cyclone dehydration tower; 14, cyclone plate; 15, electrostatic mist eliminator; 16, graded sedimentation tank; 17, fixed plate; 18, blowdown pipe; 19, stirring device; 20, temperature controller; 21, electromagnetic valve; 22, ceramic membrane filter; 23, PLC control system; 24, flue gas composition sensor; 25, flow regulating valve; 26, heating regeneration device; 27, VOCs concentration monitor; 28, activated carbon filter screen. DETAILED DESCRIPTION

[0052] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0053] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0054] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "connected" and the like should be broadly understood, for example, "connected" can be fixedly connected, can also be detachably connected, or integrally connected; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0055] Example 1: Please refer to Figure 1 and Figure 3The application provides a flue gas purification device of a hot galvanizing annealing furnace for a strip steel, which comprises, in sequence along a flue gas flow direction, an annealing furnace flue gas exhaust pipe 1, a quenching treatment unit, a multi-stage purification unit, an exhaust pipe 2 and a circulating liquid system.

[0056] Further, the nano calcium hydroxide suspension is used for double-fluid atomization spraying in the quenching tower 4, flue gas is rapidly cooled, part of the acid gas is preliminarily and efficiently removed by using the high specific surface area and reaction activity of the nano material, and the nano particles are not easy to block the spray gun, and the operation is more stable.

[0057] The first-stage turbulent absorption tower 7 is combined with the Venturi tube array 8 and the cyclone spraying layer 9 to form the synergistic effect of dense droplets and a strong cyclone field, the gas-liquid mass transfer efficiency is strengthened, the sodium hydroxide and sodium sulfite composite solution is used, residual acid gas can be efficiently removed, and the sodium sulfite can effectively reduce and capture heavy metals in the flue gas.

[0058] The secondary ultrasonic scrubber 10 uses a 1.5MHz high-frequency ultrasonic atomizer 12 to atomize the scrubbing liquid into extremely fine droplets and form a uniform liquid film on the surface of the hydrophobically modified porous corrugated packing 11. The powerful cavitation effect generated by the high-frequency ultrasound can effectively break up and emulsify the oil mist and fine particles in the flue gas, and promote the dissolution of insoluble pollutants, including heavy metal compounds and organic pollutants. The hydrophobically modified packing helps to separate oil and water and prevent clogging.

[0059] The three-stage cyclone dehydration tower 13 uses the centrifugal force of the cyclone plate 14 to efficiently remove large droplets and carried water, while the electrostatic precipitator 15 can effectively capture residual micron and submicron aerosols, fine water mist and oil mist particles, ensuring that the outlet flue gas is clean and dry;

[0060] The activated carbon filter 28 at the end of the exhaust pipe 2 serves as the last barrier, effectively absorbing and removing trace VOCs, odor substances, and extremely fine particulate matter that may remain in the flue gas, ensuring that the final exhaust gas meets the standards;

[0061] It combines multiple mechanisms such as wet spray capture, ultrasonic cavitation crushing, emulsification and washing, centrifugal dehydration and electrostatic high-efficiency capture to effectively and comprehensively remove particles ranging from coarse particles to submicron particles.

[0062] The solenoid valve 21 controls sewage discharge, which can realize automatic and precise sewage discharge, discharge different pollutants according to the conditions of each layer in the sedimentation tank, improve sedimentation efficiency and resource recovery rate, and reduce the total amount of final hazardous waste and solid waste.

[0063] Example 2: Please refer to Figure 1 and Figure 3 In one embodiment provided by the present invention, the nano-calcium hydroxide suspension sprayed by the dual-fluid atomizing spray gun 5 in the quenching tower 4 is specifically a suspension composed of a mixture of 5 wt% sodium hydroxide and 2 wt% nano-calcium hydroxide, wherein the atomized particle size is less than 20 nm. The liquid medicine tank 6 is provided with a stirring device 19 and a temperature controller 20. The flow velocity at the throat of the venturi tube array 8 in the primary turbulent absorption tower 7 is 25 to 35 m / s. The sodium hydroxide and sodium sulfite composite solution sprayed by the swirl spray layer 9 has a sodium sulfite mass proportion of 10 to 30%.

[0064] Furthermore, the synergistic effect of 5wt% sodium hydroxide and 2wt% nano calcium hydroxide is that sodium hydroxide provides a rapid strong alkaline environment for neutralizing acidic gases, while nano calcium hydroxide particles provide long-term neutralization and deep removal. Nano calcium hydroxide has good dispersibility in the suspension and its reaction activity is much higher than that of ordinary lime slurry. It can effectively capture residual acidic gases and compensate for the problem of decreased local deacidification efficiency caused by the rapid consumption of pure sodium hydroxide solution.

[0065] The dual-fluid atomization itself can generate ultra-fine mist, combined with nano-sized solute particles, so that the liquid medicine has a great total specific surface area, can greatly increase the gas-liquid contact area, significantly improve the mass transfer rate and reaction efficiency, and ensure the rapid completion of preliminary deacidification in the quenching tower 4;

[0066] The high-activity mixed alkali solution can inhibit the synthesis of dioxins and efficiently remove acid gas to reduce the corrosion of equipment by subsequent acid gas and preliminarily remove part of fine particulate matter through instantaneous quenching and cooling;

[0067] The liquid medicine tank 6 is equipped with a stirring device 19, which can ensure uniform dispersion of nano calcium hydroxide particles in the suspension, prevent sedimentation and caking, maintain the stability of the liquid medicine concentration and activity, and ensure continuous and stable injection of the dual-fluid atomization spray gun 5;

[0068] The liquid medicine tank 6 is equipped with a temperature controller 20, which can accurately control the temperature of the suspension, maintain an appropriate temperature, avoid the situation of increasing viscosity caused by too low temperature or fast solvent evaporation caused by too high temperature, maintain the good dispersion stability of nano particles, maintain the moderate viscosity of the liquid medicine, ensure the atomization effect, optimize the chemical reaction rate, and prevent the spray gun from being blocked;

[0069] The throat pipe flow rate of the Venturi tube array 8 is 25-35 m / s, which can generate strong turbulence and shear force, can fully tear and mix flue gas, spray liquid droplets and pollutants, achieve high mixing on a microscopic scale, and can improve the collision and capture efficiency of fine particulate matter and heavy metal aerosols through violent collision and coagulation of liquid droplets;

[0070] The cyclone spray layer 9 sprays 10-30% sodium sulfite composite solution to achieve high-efficiency heavy metal removal effect.

[0071] Example 3: please refer to Figure 1 and Figure 3 An embodiment provided by the present application: the hydrophobic modified porous corrugated packing 11 in the secondary ultrasonic washing tower 10 has a pore size of 0.5-1 mm, a contact angle > 150°, and the power density of the 1.5 MHz high-frequency ultrasonic atomizer 12 is 0.5-1 W / cm 3 The generated mist droplet size is less than 10 μm, the cyclone plate 14 of the tertiary cyclone dehydration tower 13 has an elevation angle of 25-35°, the plate spacing is 80-120 mm, the electrostatic precipitator 15 adopts a positive and negative bipolar thorn electrode structure, and the working voltage is 30-50 kV;

[0072] Further, the dense and tortuous channels formed by the hydrophobic modified porous corrugated filler 11 with micron-sized pores can greatly increase the gas-liquid contact area, promote the adsorption and reaction of pollutants on the surface of the filler, and through the setting of the contact angle > 150°, the oil mist can be quickly coalesced into droplets after contacting the filler, and automatically separated from the washing liquid, preventing the oil stain from wrapping the filler and causing failure, and the rolling of the liquid droplets on the hydrophobic surface can carry away the attached pollutants, reducing the cleaning frequency of the filler and maintenance cost;

[0073] 1.5MHz high-frequency ultrasonic atomizer 12 with a power density of 0.5-1W / cm³, which can generate dense cavitation bubbles in the liquid, and release local high temperature, high pressure and micro-jet when collapsing violently, realizing:

[0074] Oil mist emulsification and decomposition: breaking down stubborn oil droplets into micron-sized particles that can be emulsified;

[0075] Degradation of poorly soluble pollutants: cavitation shock waves destroy organic molecular chains;

[0076] Surface cleaning of particulate matter: stripping the hydrophobic layer on the surface of heavy metal or carbon black particles to enhance their hydrophilicity for capture;

[0077] The swirl plate 14 has an elevation angle of 25-35°, which can generate strong centrifugal force when the airflow rotates along the plate, effectively throwing off large and medium droplets, while avoiding excessive angle leading to excessive pressure loss;

[0078] The plate spacing is 80-120mm, which is conducive to the swirl plate 14 to realize water collection, and the upper plate to remove large droplets and the lower plate to focus and separate medium droplets;

[0079] The electrostatic precipitator 15 has a positive and negative double-pole thorn electrode structure, in which the thorn electrode can generate high-density ion wind at the tip of the discharge, and the double-pole design can enhance particle collision and coalescence by alternating polarity field, improving the capture efficiency of submicron particles;

[0080] The working voltage is 30-50kV, which can adapt to the electric field strength and adjust the voltage according to the humidity of the flue gas and the concentration of residual pollutants.

[0081] Example 4: please refer to Figure 1 、 Figure 3 and Figure 5 , the present application provides an embodiment: the staged sedimentation tank 16 of the circulating liquid system 7, comprising:

[0082] Acidic waste liquid area: receiving waste liquid from the quenching tower 4, pH controlled at 6-8;

[0083] Metal flocculation area: receiving waste liquid from the first-stage turbulent absorption tower 7 and the second-stage ultrasonic washing tower 10, and adding anionic polyacrylamide with a molecular weight of 8-12 million;

[0084] The clear liquid buffer zone receives the waste liquid from the third cyclone dehydration tower 13 and returns to the ultrasonic atomizer 12 through the ceramic membrane filter 22 with a pore size of 0.1 μm;

[0085] Further, the pH of the acidic waste liquid zone is controlled at 6-8, and the acidic waste liquid containing nanometer discharged from the quenching tower 4 is adjusted to neutral 6-8, which can avoid the corrosion of the acidic waste liquid to the structure and pipeline of the fractional precipitation tank 16, and the neutral environment is beneficial to the rapid settlement of the unreacted calcium hydroxide nanoparticles and the reaction product to form a high-purity calcium mud layer. The calcium-containing sludge after precipitation can be recycled as a building material raw material, realizing the resource utilization of calcium-containing waste residue;

[0086] The metal flocculation zone adds 800-1200 million molecular weight anionic polyacrylamide, which can efficiently capture superfine heavy metal colloids. A large amount of submicron heavy metal flocculation is contained in the waste liquid of the first turbulent absorption tower 7 and the second ultrasonic washing tower 10. The use of ultrahigh molecular weight ionic polyacrylamide can form a strong adsorption long-chain network to specifically capture 0.1-1 μm colloidal particles, thereby improving the flocculation efficiency;

[0087] The clear liquid buffer zone contains residual trace oil mist and submicron particles through the third cyclone dehydration tower 13. After deep treatment by the 0.1 μm ceramic membrane filter 22, all >0.1 μm pollutants, including bacteria, emulsified oil droplets, and escaped calcium hydroxide nanoparticles, can be intercepted, thereby ensuring that the produced water quality meets the industrial reuse standard: turbidity <0.1 NTU, and oil content <1 mg / L;

[0088] The filtered ultra-clean water is directly returned to the second ultrasonic atomizer 12 to realize the reuse of washing water and greatly reduce the operating cost;

[0089] The three-stage partition buffer design can cope with the fluctuation of flue gas flow and avoid the decrease of treatment efficiency caused by the mixing of waste liquids with different properties.

[0090] Example 5: Please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 6 An embodiment provided by the present application further includes a PLC control system 23, the signal input end of which is connected to a flue gas component sensor 24 arranged at the inlet of the quenching tower 4, the outlet of the first turbulent absorption tower 7, and the outlet of the exhaust pipe 2, and the signal output end of which is connected to the flow regulating valve 25 of the double-fluid atomizing spray gun 5, the cyclone spray layer 9, and the ultrasonic atomizer 12.

[0091] The activated carbon filter screen 28 of the exhaust pipe 2 has a honeycomb structure, a heating regeneration device 26 is arranged upstream of the activated carbon filter screen 28, and a VOCs concentration monitor 27 is arranged downstream of the activated carbon filter screen 28. The monitoring data is fed back to the PLC control system 23 to trigger the regeneration program.

[0092] Further, through the deployment of three key sensors:

[0093] Quench tower 4 inlet: real-time monitoring of SO2, HCl, particulate matter concentration and temperature in the original flue gas;

[0094] Primary turbulent absorption tower 7 outlet: detection of residual acid gas, heavy metal content;

[0095] Exhaust pipe 2 outlet: final check of VOCs, PM2.5, dioxin substances;

[0096] Actuator linkage: PLC dynamically adjusts according to sensor data, double-fluid atomizing spray gun 5 flow, quench tower 4 liquid injection volume automatically adjusts with inlet pollutant load, cyclone spray layer 9 composite solution flow, sodium sulfite solution is supplemented in primary turbulent absorption tower 7 according to real-time heavy metal signals, ultrasonic atomizer 12 power density;

[0097] Through the setting of honeycomb activated carbon filter screen 28 and heating regeneration device 26, PLC triggers regeneration after receiving VOCs concentration monitor 27 signal, 200-250℃ hot gas backflush desorbs organic matter, thereby restoring activated carbon capacity and prolonging the service life of honeycomb activated carbon filter screen 28.

[0098] Example 6: Please refer to Figure 7 An embodiment provided by the present application: the working steps of the flue gas purification device of the strip steel hot galvanizing annealing furnace are as follows:

[0099] S1, flue gas extraction: high-temperature flue gas containing pollutants is extracted from the annealing furnace through the annealing furnace exhaust pipe 1 and enters the purification system;

[0100] S2, quenching and preliminary purification: the flue gas enters the quench tower 4, the double-fluid atomizing spray gun 5 sprays the specific suspension stored in the liquid tank 6 into the tower at high speed, the stirring device 19 of the liquid tank 6 ensures uniform suspension, the temperature controller 20 maintains appropriate temperature, the nanoscale mist droplets are mixed with high-temperature flue gas, rapid cooling is achieved, nanoscale calcium hydroxide particles efficiently adsorb and neutralize acid gas, sodium hydroxide provides a strong alkaline environment for catalytic reaction, and part of the particulate matter is captured;

[0101] S3, primary turbulent deep absorption: the flue gas pretreated by quenching enters the primary turbulent absorption tower 7, the flue gas passes through the throat of the venturi array 8 at high speed, strong turbulence is generated, the cyclone spray layer 9 sprays sodium hydroxide and sodium sulfite composite solution downward, the turbulent effect of the venturi greatly enhances the gas-liquid contact and mass transfer efficiency, sodium hydroxide efficiently neutralizes residual acid gas, and sodium sulfite removes heavy metals through redox and assists in denitrification;

[0102] S4, secondary ultrasonic deep washing: flue gas enters the secondary ultrasonic washing tower 10, and a 1.5 MHz high-frequency ultrasonic atomizer 12 is used to atomize the washing liquid into extremely fine liquid droplets with a particle size of less than 10 μm, the ultrasonic cavitation effect generates local high temperature and high pressure, and the aerosol, emulsified oil mist and difficult-to-dissolve organic matter are broken down by strong force, the flue gas flows through the hydrophobic modified porous corrugated filler 11 to form a thin liquid film, providing a large gas-liquid contact area, and the ultra-fine mist droplets, filler liquid film and fine particulate matter, aerosol, oil mist, residual pollutants and part of VOCs in the flue gas collide, coagulate, dissolve and wash;

[0103] S5, tertiary cyclone dewatering and fine mist removal: the wet flue gas enters the tertiary cyclone dewatering tower 13, the flue gas first passes through the cyclone plate 14, and the rotational centrifugal force throws most of the liquid droplets to the tower wall to achieve mechanical dewatering, and after dewatering, the flue gas passes through the electrostatic precipitator 15, and the high-voltage electrostatic field charges the residual fine mist droplets and submicron particles and captures them by the electrode plate to achieve high-efficiency fine mist removal;

[0104] S6, activated carbon adsorption and emission standard discharge: the dewatered and mist-removed flue gas enters the exhaust pipe 2, and the flue gas passes through the honeycomb-shaped activated carbon filter screen 28 to adsorb and remove the residual trace VOCs, dioxin precursors and odors in the flue gas, the VOCs concentration monitor 27 monitors the downstream emission concentration in real time, and the purified clean flue gas is discharged up to the standard;

[0105] S7, treatment and reuse of circulating liquid: the waste liquid generated at the bottom of the quenching tower 4, the primary turbulent absorption tower 7, the secondary ultrasonic washing tower 10 and the tertiary cyclone dewatering tower 13 flows into the lower-stage grading sedimentation tank 16 through the blowdown pipe 18 at the bottom thereof;

[0106] S8, grading sedimentation tank 16 partition treatment: acidic waste liquid area: receiving waste liquid from the quenching tower 4, controlling pH 6-8, metal flocculation area: receiving waste liquid from the primary turbulent absorption tower and the secondary ultrasonic washing tower 10, adding anionic polyacrylamide with a molecular weight of 8-12 million, flocculating and settling heavy metal hydroxide suspensions, clear liquid buffer area: receiving waste liquid from the tertiary cyclone dewatering tower 13 and supernatant from the previous two areas, the clear liquid buffer area wastewater is filtered by the ceramic membrane filter 22, and then can be returned to the ultrasonic atomizer 12 of the secondary ultrasonic washing tower 10 as a washing liquid supplement water source, and the settled sludge is regularly cleaned and disposed;

[0107] S9, intelligent control and regeneration: PLC control system 23 monitors the pollutant concentration in real time through flue gas composition sensor 24, and PLC dynamically adjusts the amount of medicament and washing liquid sprayed by double-fluid atomizing spray gun 5, cyclone spray layer 9 and ultrasonic atomizer 12 through flow regulating valve 25 according to the monitoring data, so as to realize precise control and energy saving. When VOCs concentration monitor 27 detects that the downstream concentration of activated carbon exceeds the standard, the data is fed back to PLC, and PLC triggers heating regeneration device 26 to use hot gas to heat and desorb the honeycomb-shaped activated carbon filter screen 28 for regeneration, so as to restore its adsorption capacity. The desorbed concentrated VOCs, after regeneration, the system returns to adsorption mode, and ceramic membrane filter 22 performs backwashing or maintenance according to pressure difference or time setting.

[0108] Working principle, through the multi-stage, synergistic purification process of quenching, detoxification and deacidification, turbulent flow enhanced absorption, ultrasonic deep washing, high-efficiency dewatering and demisting and activated carbon adsorption, combined with intelligent staged sedimentation and circulating liquid system, efficient, deep and comprehensive purification of complex flue gas from hot galvanized aluminum magnesium annealing furnace of strip steel is realized, the pollutant emission concentration is significantly reduced, the waste liquid treatment and resource recovery are optimized, the operation cost and environmental risk are reduced, the environmental protection emission standard is reached, through the spraying of superfine nanometer composite suspension by double-fluid atomizing spray gun 5 in quenching tower 4, combined with the stirring and temperature control function of liquid tank 6, the nano particle activity and dispersion stability are ensured, the efficiency of initial neutralization of acid gas and particle capture is significantly improved, the first-stage turbulent absorption tower 7 strengthens the mixing and mass transfer through 25-35 m / s high-turbulent Venturi tube array 8, and uses composite spray liquid containing 10-30% sodium sulfite to simultaneously realize deep removal of acid gas and reduction and fixation of heavy metals, laying a foundation for efficient pretreatment for subsequent purification links, through the flow resistance of super-hydrophobic modified porous corrugated filler 11 in the second-stage ultrasonic washing tower 10, combined with the submicron droplets generated by 1.5 MHz high-frequency ultrasonic atomization, the synergistic effect of acoustic cavitation and surface adsorption is utilized to realize deep purification of submicron aerosol, oil mist and heavy metals, the third-stage cyclone dewatering tower 13 adopts optimized cyclone plate 14 for pre-dewatering and gradient interception of bipolar thorn electrostatic precipitator 15 to efficiently remove residual droplets and fine particles, ensuring ultra-low moisture content and clean emission, through the partitioned targeted treatment of acid waste liquid area, metal flocculation area and clear liquid buffer area in the staged sedimentation tank 16, the waste liquid is treated and recycled in stages, the acid area neutralizes the medicament consumption, the flocculation area accelerates the sedimentation of metal sludge, and the high-quality clear liquid produced by the ceramic membrane filtration is directly used for ultrasonic atomizer 12, which significantly reduces the fresh water consumption and waste water discharge, forming an efficient and low-consumption circular economy mode.

[0109] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The embodiments should therefore be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the above description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference signs in the claims should be considered as limiting the scope of the claims with respect to the figures of the patent document.

Claims

1. A flue gas purification device for a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip, characterized by: It comprises an annealing furnace exhaust pipe (1), a rapid cooling treatment unit, a multi-stage purification unit, an exhaust pipe (2) and a circulating liquid system which are sequentially connected along the flow direction of the flue gas; The quenching treatment unit comprises a quenching tower (4) arranged at the output end of the annealing furnace exhaust pipe (1), the inner wall of the quenching tower (4) is provided with a dual-fluid atomizing spray gun (5), the input end of the dual-fluid atomizing spray gun (5) is connected to a liquid medicine tank (6) via a pipeline, and the liquid medicine tank (6) is arranged on the outer wall of the quenching tower (4), and the interior of the liquid medicine tank (6) is filled with a nano-calcium hydroxide suspension; The multi-stage purification unit comprises in sequence: A first-stage turbulent absorption tower (7) has an input end connected to the output end of the quenching tower (4), and a venturi tube array (8) and a swirl spray layer (9) are provided inside the first-stage turbulent absorption tower (7) to spray a composite solution of sodium hydroxide and sodium sulfite; A secondary ultrasonic washing tower (10), the input end of which is connected to the output end of the primary turbulent absorption tower (7), wherein a hydrophobically modified porous corrugated packing (11) and a 1.5 MHz high-frequency ultrasonic atomizer (12) are arranged inside the secondary ultrasonic washing tower (10); A three-stage cyclone dehydration tower (13), the input end of which is connected to the output end of the two-stage ultrasonic washing tower (10), wherein a cyclone plate (14) and an electrostatic demister (15) are provided inside the three-stage cyclone dehydration tower (13); The input end of the exhaust pipe (2) is connected to the output end of the three-stage cyclone dehydration tower (13), and the output end of the exhaust pipe (2) is provided with an activated carbon filter (28); The circulating fluid system comprises: A graded sedimentation tank (16), wherein a plurality of fixed plates (17) are provided on the top of the graded sedimentation tank (16), and the tops of the fixed plates (17) are respectively provided at the bottoms of the quenching tower (4), the first-stage turbulent absorption tower (7), the second-stage ultrasonic washing tower (10), and the third-stage cyclone dehydration tower (13); A sewage pipe (18) is provided at the bottom of each of the quenching tower (4), the first-stage turbulent absorption tower (7), the second-stage ultrasonic washing tower (10), and the third-stage cyclone dehydration tower (13), and the outer wall of the sewage pipe (18) passes through the top of the fixed plate (17). A solenoid valve (21) is provided on the outer wall of the sewage pipe (18).

2. The flue gas purification device of a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip according to claim 1, characterized in that: The nano-calcium hydroxide suspension sprayed by the dual-fluid atomizing spray gun (5) in the quenching tower (4) is specifically a suspension formed by mixing 5wt% sodium hydroxide and 2wt% nano-calcium hydroxide, wherein the atomized particle size is less than 20nm. The liquid medicine tank (6) is provided with a stirring device (19) and a temperature controller (20).

3. The flue gas purification device of a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip according to claim 1, characterized in that: The turbulent flow velocity at the throat of the Venturi tube array (8) in the first-stage turbulent absorption tower (7) is 25 to 35 m / s, and the sodium hydroxide and sodium sulfite composite solution sprayed by the swirl spray layer (9) contains 10 to 30% by mass of sodium sulfite.

4. The flue gas purification device for a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip according to claim 1, characterized in that: The hydrophobically modified porous corrugated packing (11) in the secondary ultrasonic washing tower (10) has a pore size of 0.5 to 1 mm and a contact angle of >150°. The power density of the 1.5 MHz high-frequency ultrasonic atomizer (12) is 0.5 to 1 W / cm 3 , the droplet size produced is less than 10μm.

5. The flue gas purification device of a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip according to claim 1, characterized in that: The cyclone plates (14) of the three-stage cyclone dehydration tower (13) have an elevation angle of 25 to 35 degrees and a plate spacing of 80 to 120 mm. The electrostatic precipitator (15) adopts a positive and negative bipolar thorn electrode structure and has an operating voltage of 30 to 50 kV.

6. The flue gas purification device of a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip according to claim 1, characterized in that: The grading sedimentation tank (16) of the circulating liquid system comprises: Acidic waste liquid area: receiving waste liquid from the quench tower (4), with pH controlled at 6-8; Metal flocculation zone: receiving waste liquid from the first-stage turbulent absorption tower (7) and the second-stage ultrasonic washing tower (10), and adding anionic polyacrylamide with a molecular weight of 8 to 12 million; Clear liquid buffer: receives waste liquid from the three-stage cyclone dehydration tower (13) and returns it to the ultrasonic atomizer (12) through the ceramic membrane filter (22). The retention pore size of the ceramic membrane filter (22) is 0.1 μm.

7. The flue gas purification device of a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip according to claim 1, characterized in that: It also includes a PLC control system (23), whose signal input end is connected to the flue gas composition sensor (24) arranged at the inlet of the quenching tower (4), the outlet of the first-stage turbulent absorption tower (7), and the outlet of the exhaust pipe (2), and its signal output end is connected to the flow regulating valve (25) of the dual-fluid atomizing spray gun (5), the swirl spray layer (9), and the ultrasonic atomizer (12).

8. The flue gas purification device for a hot-dip galvanized aluminum-magnesium annealing furnace for steel strip according to claim 1, characterized in that: The activated carbon filter (28) of the exhaust pipe (2) is a honeycomb structure, with a heating regeneration device (26) provided upstream and a VOCs concentration monitor (27) provided downstream. The monitoring data is fed back to the PLC control system (23) to trigger the regeneration program.

9. The method for using the flue gas purification device of a steel strip hot-dip galvanizing aluminum-magnesium annealing furnace according to claim 8, characterized in that: The working steps of the flue gas purification device of the strip hot-dip galvanized aluminum-magnesium annealing furnace are as follows: S1. Flue gas extraction: High-temperature flue gas containing pollutants is extracted from the annealing furnace through the annealing furnace exhaust pipe (1); S2, rapid cooling and preliminary treatment: the flue gas first enters the rapid cooling tower (4), and the dual-fluid atomizing spray gun (5) highly atomizes the nano calcium hydroxide suspension in the liquid tank (6) and sprays it into the tower, and the atomized droplets fully contact with the high-temperature flue gas; S3, primary turbulent absorption: The flue gas pretreated by rapid cooling enters the primary turbulent absorption tower (7), and the flue gas passes through the venturi tube array (8) at high speed, generating strong turbulence at the throat, and the swirl spray layer (9) sprays the sodium hydroxide and sodium sulfite composite solution downward. The turbulent effect of the venturi tube greatly enhances the gas-liquid mass transfer, so that the spray liquid reacts efficiently with the acid gas and heavy metal pollutants in the flue gas; S4, Secondary ultrasonic washing: The flue gas then enters the secondary ultrasonic washing tower (10), where the 1.5MHz high-frequency ultrasonic atomizer (12) atomizes the washing liquid into extremely fine micron and submicron droplets. The high-temperature and high-pressure microenvironment and strong physical disturbance generated by the ultrasonic cavitation effect can effectively break up the aerosol, emulsify the oil mist, and degrade some insoluble organic matter. The flue gas flows through the hydrophobically modified porous corrugated packing (11), forming a thin liquid film, providing a huge gas-liquid contact surface area; S5, three-stage cyclone dehydration and demisting: the wet flue gas enters the three-stage cyclone dehydration tower (13), and the flue gas first passes through the cyclone plate (14). The airflow generates a rotating centrifugal force on the cyclone plate (14), which throws most of the entrained droplets to the tower wall, achieving preliminary mechanical dehydration. Subsequently, the flue gas passes through the electrostatic demister (15). The high-voltage electrostatic field charges the remaining fine droplets and submicron particles and captures them by the collecting electrode, achieving efficient demisting and removal of ultrafine particles. S6. Activated carbon adsorption and emission: The flue gas after dehydration and demisting enters the exhaust pipe (2), and the flue gas passes through the activated carbon filter (28), which adsorbs and removes the trace VOCs, dioxin precursors and odors remaining in the flue gas. The purified clean flue gas is finally discharged through the exhaust pipe (2) in compliance with the emission standards. S7, circulating liquid system and sewage discharge: the waste liquid generated at the bottom of the quenching tower (4), the first-stage turbulent absorption tower (7), the second-stage ultrasonic washing tower (10) and the third-stage cyclone dehydration tower (13) flows into the classification sedimentation tank (16) below through the respective sewage pipes (18). The electromagnetic valve (21) controls the opening and closing of the sewage pipe (18). In the classification sedimentation tank (16), the solid suspended matter in the waste liquid is settled, concentrated and graded. The supernatant of the sedimentation tank can be partially reused after appropriate treatment according to the process requirements, or discharged in compliance with the standards. The precipitated sludge is cleaned and disposed of regularly; S8. Activated carbon regeneration: The VOCs concentration monitor (27) continuously monitors the VOCs concentration of the exhaust gas downstream of the activated carbon filter (28). When the monitored concentration reaches a preset threshold, the data is fed back to the PLC control system (23). The PLC control system (23) triggers the regeneration program of the heating regeneration device (26), and uses hot air to heat the activated carbon filter (28) to desorb the adsorbed VOCs and restore the adsorption capacity of the activated carbon.

10. The method for using the flue gas purification device of a steel strip hot-dip galvanizing aluminum-magnesium annealing furnace according to claim 9, characterized in that: The step S2 further includes the following steps: S21, achieving rapid cooling, nano calcium hydroxide particles simultaneously adsorb part of the acidic gas and particulate matter; The S3 also includes the following steps: S31, ultrafine droplets, the liquid film on the surface of the filler collide with, intercept, condense, dissolve and wash the fine particles, aerosols, residual acid gases, oil mist and some VOCs in the flue gas to achieve deep purification.

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