Steel-making electric furnace high-temperature flue gas metal particle separation system

Abstract

The invention relates to the technical field of flue gas treatment, in particular to a steel-making electric furnace high-temperature flue gas metal particle separation system which comprises a separation box, and the interior of the separation box is sequentially connected with a condensation nucleus adding module, an acoustic agglomeration module and a magnetic field separation module in the flue gas flowing direction. The particle size and mass of metal particle aggregates are increased through the condensation nucleus adding module and the sound wave agglomeration module, the gravity effect is enhanced, magnetic field force of the magnetic field separation module is combined, the two kinds of force work cooperatively, the separation speed and effect of metal particles from flue gas are greatly improved, the separation process is more efficient, and the separation efficiency is improved. And a large number of metal particles can be separated from high-temperature flue gas in a shorter time.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment in flue gas, and in particular to a system for separating metal particles from high-temperature flue gas in a steelmaking electric furnace. Background Art

[0002] During the production operation of steelmaking electric furnaces, a large amount of flue gas with extremely high temperature and complex components will be generated. The flue gas stays in the temperature range of 400℃-600℃ for too long, which easily promotes the formation of highly toxic and harmful substances such as dioxins. Therefore, these flue gases are generally treated in a quenching tower before being discharged.

[0003] The working principle of the quenching tower is to spray the flue gas with atomization by means of cooling water nozzles, and achieve rapid cooling of the flue gas through the absorption of heat by water vaporization, and sharply reduce the flue gas temperature to 200℃-250℃ in a short time. In order to effectively treat these waste gases, a catalytic plate equipped with a metal catalyst is usually set in the subsequent treatment process of the quenching tower. The catalytic effect of the metal catalyst is used to promote chemical reactions in the waste gas and convert it into relatively harmless substances to reduce pollution to the environment. However, the metal particles contained in the flue gas will poison the catalyst and make it ineffective, which greatly affects the effect of catalytic treatment of waste gas.

[0004] Therefore, a device for separating metal particles from high-temperature flue gas of a steelmaking electric furnace is developed to separate the metal particles in the high-temperature flue gas before it enters the quenching tower, thereby increasing the service life of the catalyst in the quenching tower. Summary of the invention

[0005] The purpose of the present invention is to provide a device for separating metal particles from high-temperature flue gas in a steelmaking electric furnace to solve the problems mentioned in the background technology. To achieve the above purpose, the present invention provides the following technical solutions: A system for separating metal particles from high-temperature flue gas in a steelmaking electric furnace comprises a separation box, wherein the following modules are sequentially connected inside the separation box along the flue gas flow direction: Condensation nucleus adding module: comprising a nozzle and a dry powder storage bin, wherein the nozzle is used to spray the condensation nucleus powder in the dry powder storage bin into the flue gas in a mist form; The acoustic wave agglomeration module includes an ultrasonic generator arranged on the inner wall of the flue: The magnetic field separation module comprises an electromagnetic coil system arranged at the bottom wall inside the separation box, and the magnetic field generated by the electromagnetic coil system can accelerate the sedimentation of metal particles in the flue gas.

[0006] After the high-temperature flue gas generated by the steelmaking electric furnace enters the separation box, the nozzle sprays the condensation nucleus powder in the dry powder storage bin into the high-temperature flue gas in the form of a mist. Due to the large specific surface area and special physical and chemical properties of the condensation nucleus powder, the metal particles in the high-temperature flue gas will adhere to its surface, forming particle aggregates. The particle size and mass of these aggregates increase, making the effect of gravity on them begin to become prominent, laying a foundation for subsequent separation by means of gravity and other external forces. The condensation nucleus powder is a composite magnetic particle of iron oxide and samarium cobalt, and the particle size range is 1-10 μm.

[0007] The flue gas containing the initially formed metal particle aggregates enters the acoustic agglomeration module. The ultrasonic generator on the inner wall of the flue duct emits ultrasonic waves with a specific frequency and intensity, generating fluctuations of sparse and dense phases in the flue gas. Under the action of ultrasonic waves, the metal particle aggregates continuously collide with each other and further agglomerate. As the degree of agglomeration deepens, the mass of the particle aggregates continues to increase, and the effect of gravity becomes more significant.

[0008] After being processed by the first two modules, the particle size and mass of the metal particle aggregates have increased significantly, and they enter the magnetic separation module. The electromagnetic coil system at the inner bottom wall of the separation box generates a magnetic field, and the direction of the magnetic field is perpendicular to the direction of the flue gas flow. Due to the magnetic properties of the metal particles themselves or after magnetization treatment, under the action of the magnetic field force, in addition to gravity, the metal particles are also subject to a magnetic field force perpendicular to the direction of the flue gas flow. The combined action of these two forces greatly accelerates the settlement of the metal particles to the bottom of the separation box.

[0009] The above settings increase the particle size and mass of the metal particle aggregates through the condensation nucleus addition module and the acoustic agglomeration module, strengthen the effect of gravity, and then combine with the magnetic field force of the magnetic separation module. The two forces work together, greatly improving the speed and effect of separating metal particles from the flue gas, making the separation process more efficient, and enabling the separation of a large number of metal particles and high-temperature flue gas in a shorter time.

[0010] The magnetic field formed around the composite magnetic particles changes the movement trajectory of the metal particles, making the metal particles originally dispersed in the flue gas easier to collide with each other, and then agglomerate and grow; among them, samarium cobalt has a high Curie temperature and can still maintain relatively excellent magnetic properties in the high-temperature flue gas environment; the particle size is in the range of 1-10 μm, ensuring good dispersion of the composite particles in the flue gas. The smaller particle size enables the particles to be more evenly distributed in the flue gas, increasing the contact area and opportunity with the metal particles and improving the adsorption efficiency.

[0011] As a preference; a plurality of baffle plates are arranged between the condensation nucleus addition module and the acoustic agglomeration module, and the baffle plates are arranged in a staggered manner along the height direction of the separation box.

[0012] The baffle changes the flow direction of the flue gas, causing the flue gas to form a complex turbulent state. This turbulent state increases the contact opportunities between the condensation nucleus powder and the metal particles in the flue gas. For example, when the flue gas flowing in a straight line is blocked by the baffle, vortices will form around the baffle. The condensation nucleus powder and metal particles tumble and collide in the vortices, enabling the condensation nucleus powder to come into contact with and adsorb the metal particles more fully, thus accelerating the agglomeration of the metal particles.

[0013] Preferably, a rotating shaft is arranged between two adjacent baffle plates. Both ends of the rotating shaft are fixed on the inner wall of the separation box, and the axial direction of the rotating shaft is perpendicular to the air flow direction. A rotating ring is sleeved on the rotating shaft, and the rotating ring can rotate around the rotating shaft driven by the flue gas.

[0014] The stirring of the rotating ring increases the frequency and intensity of mutual contact, prompting the condensation nucleus powder to adsorb the metal particles more fully and accelerating the agglomeration process of the metal particles. On the other hand, the rotation of the rotating ring drives the flue gas to generate more complex flow exchanges at different heights and positions in the separation box, making the distribution of the condensation nucleus powder and metal particles more uniform throughout the area, and further improving the efficiency of contact and agglomeration.

[0015] Preferably, a plurality of protrusions are evenly distributed on the side wall of the rotating ring.

[0016] These protrusions disrupt the relatively smooth flow state of the flue gas around the rotating ring, causing the flue gas to form more complex small-scale turbulence around the protrusions.

[0017] Preferably, a conical transition flow channel is arranged between the ultrasonic generator and the magnetic separation module. The conical transition flow channel consists of a contraction section and an expansion section. The cross-sectional area of the contraction section gradually decreases to the throat, and the cross-sectional area of the expansion section gradually expands to the outlet.

[0018] Preferably, an electrical installation cavity is opened on the bottom wall of the separation box. The electromagnetic coil system is arranged in the electrical installation cavity, and a circulating water channel is arranged around the electrical installation cavity.

[0019] The setting of the electrical installation cavity provides a dedicated placement space for the electromagnetic coil system. Excessive temperature will accelerate the aging and damage of the electromagnetic coil. The cooling effect of the circulating water channel reduces the working temperature of the electromagnetic coil, slows down its aging speed, and extends the service life of the electromagnetic coil system. At the same time, a stable working environment also helps to reduce the failures of other related components caused by heat, reduce the overall maintenance cost of the equipment, increase the service life of the equipment, and save the enterprise the equipment replacement and repair costs.

[0020] Preferably, the upper end of the electrical installation cavity is open, and a collection box is covered at the opening. A plurality of micropores for the metal particles to fall into are evenly distributed on the upper end of the collection box.

[0021] The collection box not only serves to collect metal particles, but also provides a certain degree of protection for the electromagnetic coil system below. It can also prevent the settled technical particles from being re-suspended under the disturbance of the air flow.

[0022] Preferably, a plurality of layers of guide plates are arranged inside the collection box in a staggered manner, and the guide plates are inclined downward.

[0023] Inside the collection box, the plurality of layers of guide plates that are staggered and inclined downward form a channel network for guiding the metal particles to fall. Due to the downward inclination of the guide plates, the metal particles slide down along the surface of the guide plates under the action of gravity, and then efficiently and orderly fall to the bottom of the collection box to achieve centralized collection.

[0024] The multi-layer guide plates not only guide the metal particles to fall, but also block the interference of the flue gas flow on the metal particles to a certain extent. When the flue gas flows inside the collection box and encounters the blockage of the guide plates, its flow direction and speed change, forming a relatively complex flow field. This change in the flow field weakens the upward carrying capacity of the flue gas, making it difficult for the metal particles to obtain sufficient energy to be sucked out from the micropores. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the overall structure of the high-temperature flue gas metal particle separation system in Embodiment 1; Figure 2 It is a schematic diagram of the internal structure of the high-temperature flue gas metal particle separation system in Embodiment 1; Figure 3 It is a schematic diagram of the structure of the rotating shaft in Embodiment 1; Figure 4 It is a schematic diagram of the structure of the conical transition channel in Embodiment 1; Figure 5 It is a schematic diagram of the structure of the collection box in Embodiment 1; Figure 6 It is a schematic diagram of the internal structure of the electrical installation cavity and the collection box in Embodiment 1.

[0026] In the figure: 110, separation box; 1101, electrical installation cavity; 1102, intake pipe; 1103, outlet pipe; 1201, nozzle; 1202, dry powder storage bin; 130, ultrasonic generator; 1401, electromagnetic coil system; 150, baffle plate; 1601, rotating shaft; 1602, rotating ring; 1603, protrusion; 170, conical transition channel; 1701, contraction section; 1702, expansion section; 190, collection box; 1901, micropores; 200, guide plate. Detailed Embodiments

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Embodiment 1: Please refer to Figures 1-6 , and this embodiment provides a specific technical solution for a metal particle separation system for high-temperature flue gas in a steelmaking electric furnace.

[0029] It mainly consists of a separation box 110 and a plurality of modules arranged in sequence along the flue gas flow direction inside. These modules include a condensation nucleus addition module, a baffle 150 area, an acoustic agglomeration module, a conical transition flow channel 170, and a magnetic separation module in sequence.

[0030] The condensation nucleus addition module includes a nozzle 1201 and a dry powder storage bin 1202. The dry powder storage bin 1202 is arranged on the upper end face of the separation box 110. One end of the nozzle 1201 extends into the separation box 110. The dry powder storage bin 1202 stores condensation nucleus powder, and the nozzle 1201 sprays the condensation nucleus powder into the flowing high-temperature flue gas in a mist form. The nozzle 1201 can be set as multiple, and is arranged in an array perpendicular to the flue gas movement direction, so that the condensation nuclei are more evenly distributed in the high-temperature flue gas.

[0031] It should be noted that in research practice, it is found that the lower the temperature of the condensation nucleus powder, the stronger the surface adsorption activity. Therefore, a refrigeration device can be equipped for the dry powder storage bin 1202 to stably maintain the temperature of the sprayed condensation nucleus powder at 2-8°C. Baffle 150 area: Between the condensation nucleus addition module and the acoustic agglomeration module, two baffles 150 are arranged in a staggered manner along the height direction of the separation box 110. By repeatedly changing the movement direction of the flue gas through the baffle 150, the condensation nuclei are fully diffused to all parts of the flue gas. At the same time, a rotating shaft 1601 is arranged between two adjacent baffles 150. Both ends of the rotating shaft 1601 are fixed on the inner wall of the separation box 110, and its axial direction is perpendicular to the air flow direction. A rotating ring 1602 is sleeved on the rotating shaft 1601, and a plurality of protrusions 1603 are evenly distributed on the side wall of the rotating ring 1602, and can rotate around the rotating shaft 1601 under the drive of the flue gas.

[0032] Acoustic agglomeration module: An ultrasonic generator 130 is installed on the inner wall of the flue. The acoustic wave frequency emitted by the ultrasonic generator 130 is between 1400-1500 Hz.

[0033] Conical transition flow channel 170: located between the ultrasonic generator 130 and the magnetic field separation module, it can effectively block the expansion of sound waves toward the magnetic field separation module, and is composed of a contraction section 1701 and an expansion section 1702; the cross-sectional area of ​​the contraction section 1701 gradually decreases from the inlet to the throat, so that the flue gas flow rate is accelerated from 8m / s at the inlet to 12-15m / s at the throat, and the secondary combination of particle agglomerates and condensation nuclei is strengthened through inertial collision; the cross-sectional area of ​​the expansion section 1702 gradually expands from the throat to the outlet to the inlet, so that the flow rate is reduced, thereby avoiding interference of high-speed airflow on the magnetic field separation module.

[0034] Magnetic field separation module: An electrical installation cavity 1101 is provided at the bottom wall of the separation box 110, and the electromagnetic coil system 1401 is placed in the electrical installation cavity 1101. A circulating water channel is provided around the electrical installation cavity 1101, and there is circulating water outside the circulating water channel, which can be used to cool the electromagnetic coil system 1401. The upper end of the electrical installation cavity 1101 is open, and the opening covers the collection box 190. Micropores 1901 for metal particles to fall into are evenly distributed on the upper end of the collection box 190. Multiple layers of staggered and downwardly inclined guide plates 200 are provided inside the collection box 190.

[0035] The specific usage principle and process are as follows: After the high-temperature flue gas generated by the steelmaking electric furnace enters the separation box 110, the nozzle 1201 of the condensation nucleus adding module sprays the condensation nucleus powder into the flue gas in the form of mist. The composite magnetic particles, with their large specific surface area, special physical and chemical properties and magnetism, attract the metal particles in the flue gas to adhere and form particle agglomerates. Under actual working conditions, the composite magnetic particles of 1-10μm are evenly dispersed in the flue gas, can quickly contact with the metal particles, and begin to form agglomerates.

[0036] The flue gas with preliminary agglomerates enters the baffle 150 area, and the baffle 150 changes the direction of the flue gas flow, causing it to form complex turbulence, increasing the contact opportunities between the condensation nucleus powder and the metal particles. At the same time, the flue gas drives the rotating ring 1602 to rotate around the rotating axis 1601, and the protrusions 1603 on the side wall of the rotating ring 1602 further enhance the flue gas disturbance, so that the condensation nucleus powder and the metal particles are more fully mixed and collided, accelerating the agglomeration. Simulation experiments show that this area can increase the agglomeration speed of metal particles.

[0037] After the smoke has been strengthened and agglomerated in the baffle 150 area, it enters the acoustic agglomeration module. The ultrasonic generator 130 emits ultrasonic waves with a frequency of 20-50kHz and an intensity of 10-20W / cm², which produces sparse and dense fluctuations in the smoke, causing the metal particle agglomerates to further collide and agglomerate, and the particle size and mass continue to increase. Experimental data show that after passing through this module, the particle size of the metal particle agglomerates increases by an average of 2-3 times.

[0038] The flue gas coming out of the acoustic agglomeration module passes through the conical transition flow channel 170. The conical transition flow channel 170 can effectively block the diffusion of sound waves to the location of the magnetic separation module. In the contraction section 1701, the velocity of the flue gas increases, and the collision between particles intensifies, further promoting agglomeration; in the expansion section 1702, the velocity of the flue gas decreases and the pressure rises, which is beneficial to the stability of large particle agglomerates.

[0039] Metal particle agglomerates with a large increase in particle size and mass enter the magnetic separation module. The electromagnetic coil system 1401 generates a magnetic field with an intensity of 0.5 - 1 T, and the direction of the magnetic field is perpendicular to the direction of the flue gas flow. Under the combined action of the magnetic force and gravity, the metal particles accelerate and settle towards the bottom of the separation tank 110. The circulating water channel circulates the coolant to take away the heat generated by the operation of the electromagnetic coil system 1401, ensuring its stable operating temperature and guaranteeing the stability of the magnetic field. The settled metal particles fall into the collection tank 190 through the micropores 1901 at the upper end of the collection tank 190 and are concentrated and fall to the bottom of the collection tank 190 under the guidance of the guide plate 200.

[0040] The condensation nuclei used therein are specific Fe3O4 / SmCo composite magnetic particles. The magnetic field formed around the composite magnetic particles changes the movement trajectory of the metal particles, making the metal particles originally dispersed in the flue gas easier to collide with each other and then agglomerate and grow; among them, samarium cobalt has a high Curie temperature and can still maintain relatively excellent magnetism in a high-temperature flue gas environment; the particle size is in the range of 1 - 10 μm, ensuring good dispersibility of the composite particles in the flue gas. The smaller particle size enables the particles to be more evenly distributed in the flue gas, increasing the contact area and opportunity with the metal particles and improving the adsorption efficiency.

[0041] The above-mentioned modules work together, and the separation efficiency of metal particles from the flue gas is significantly improved. Through actual tests, after using this system, the content of metal particles in the flue gas can be reduced by 80% - 90%, and a large amount of high-temperature flue gas can be processed in a very short time, enabling the processed flue gas to enter the quench tower for cooling in a timely manner.

[0042] The setting of the condensation nuclei addition module, the baffle 150 and the rotating ring 1602 area, and the acoustic agglomeration module greatly strengthens the agglomeration process of metal particles. The disturbance of the flue gas by the baffle 150 and the rotating ring 1602 and the action of ultrasonic waves jointly promote the rapid agglomeration of metal particles into large particle size particles, improving the separation effect. The treatment of the flue gas by the conical transition flow channel 170 enables the particles to agglomerate more fully and the gas flow state to be more conducive to separation before the flue gas enters the magnetic separation module, and can effectively isolate sound waves, further enhancing the processing capacity of the entire system for high-temperature flue gas.

[0043] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for separating metal particles from high-temperature flue gas of a steelmaking electric furnace, comprising a separation box (110), characterized in that: The following modules are connected in sequence inside the separation box (110) along the flue gas flow direction: A condensation nucleus adding module: comprising a nozzle (1201) and a dry powder storage bin (1202), wherein the nozzle (1201) is used to spray the condensation nucleus powder in the dry powder storage bin (1202) into the flue gas in a mist form; The acoustic wave agglomeration module comprises an ultrasonic generator (130) arranged on the inner wall of the flue: A magnetic field separation module, comprising an electromagnetic coil system (1401) arranged at the bottom wall inside the separation box (110), the magnetic field generated by the electromagnetic coil system being able to accelerate the sedimentation of metal particles in the flue gas; The condensation nucleus powder is composite magnetic particles of ferroferric oxide and samarium cobalt, and the particle size range is 1-10 μm.

2. According to claim 1, a system for separating metal particles from high temperature flue gas of a steelmaking electric furnace, characterized in that: A plurality of baffles (150) are arranged between the condensation nucleus addition module and the acoustic wave agglomeration module, and the baffles (150) are arranged in a staggered manner along the height direction of the separation box (110).

3. According to claim 2, a system for separating metal particles from high temperature flue gas of a steelmaking electric furnace is characterized in that: A rotating shaft (1601) is provided between two adjacent baffles (150), two ends of the rotating shaft (1601) are fixed on the inner wall of the separation box (110), and the axial direction of the rotating shaft (1601) is perpendicular to the airflow direction. A rotating ring (1602) is sleeved on the rotating shaft (1601), and the rotating ring (1602) can rotate around the rotating shaft (1601) driven by the flue gas.

4. According to claim 3, a system for separating metal particles from high temperature flue gas of a steelmaking electric furnace is characterized by: A plurality of protrusions (1603) are evenly distributed on the side wall of the rotating ring (1602).

5. According to claim 1, a system for separating metal particles from high temperature flue gas of a steelmaking electric furnace, characterized in that: A conical transition flow channel (170) is provided between the ultrasonic generator (130) and the magnetic field separation module, and the conical transition flow channel (170) consists of a contraction section (1701) and an expansion section (1702), wherein the cross-sectional area of ​​the contraction section (1701) gradually decreases to the throat, and the cross-sectional area of ​​the expansion section (1702) gradually expands to the outlet.

6. The system for separating metal particles from high temperature flue gas of a steelmaking electric furnace according to claim 1, characterized in that: An electrical appliance installation cavity (1101) is provided on the bottom wall of the separation box (110), the electromagnetic coil system (1401) is arranged in the electrical appliance installation cavity (1101), and a circulating water channel is arranged around the electrical appliance installation cavity (1101).

7. A system for separating metal particles from high temperature flue gas of a steelmaking electric furnace according to claim 6, characterized in that: The upper end of the electrical appliance installation cavity (1101) is open, and the opening is covered with a collection box (190). The upper end of the collection box (190) is evenly distributed with microholes (1901) for metal particles to fall into.

8. A system for separating metal particles from high temperature flue gas of a steelmaking electric furnace according to claim 7, characterized in that: The collecting box (190) is provided with multiple layers of staggered guide plates (200) inside, and the guide plates (200) are inclined downward.

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