CN219425607U - Device for refining bubbles by using ultrasound for continuous casting argon blowing tundish - Google Patents

Abstract

The utility model discloses an ultrasonic bubble refining device for a continuous casting argon blowing tundish, and belongs to the technical field of metallurgy. The utility model installs ultrasonic generator at the bottom of ventilation element arranged at the bottom of argon blowing tundish; the air permeable element comprises air permeable bricks, an air chamber and an air inlet pipeline; the air chamber is positioned below the air brick and is connected with the argon station through an air inlet pipeline; the ultrasonic generating device is buried in the refractory material at the bottom of the tundish and is connected with an external power supply through a wire; the guided wave tool head faces the ventilation element. In the continuous casting process, argon is introduced into the ventilation element, and the ultrasonic generating device is started at the same time; the air bubbles formed at the positions of the vent bricks vibrate, grow and desorb under the regulation and control action of ultrasonic waves to generate small air bubbles with uniform size; the residence time of bubbles in the tundish and the gas content in the molten steel are prolonged, the collision adhesion probability of the bubbles and nonmetallic inclusions in the molten steel is increased, and the effects of purifying the molten steel, stabilizing continuous casting operation and improving casting blank quality are achieved.

Description

Device for refining bubbles by using ultrasound for continuous casting argon blowing tundish

Technical Field

The utility model belongs to the technical field of metallurgy, relates to a metallurgical technology of a ferrous metallurgy continuous casting tundish, and particularly relates to a device for refining bubbles by ultrasound for a continuous casting argon blowing tundish.

Background

Nonmetallic inclusions are usually defects in the metal matrix that can destroy its mechanical properties. The inclusion content is reduced, so that the quality of steel can be improved, and the problems of nozzle blockage and the like caused by adhesion of the inclusion to the wall surface of the nozzle can be effectively reduced. The tundish acts as the last vessel in the continuous casting process where a large number of inclusions are created. The large-size inclusions can be effectively removed by arranging a flow control device such as a baffle dam, a baffle dam and the like in the tundish, but the removing effect on the small-size (< 50 mu m) inclusions is not obvious. The tundish argon blowing can effectively remove fine inclusions in molten steel, and the mechanism for removing the inclusions is as follows: nonmetallic inclusions and molten steel are not wetted, the inclusions can be adhered to bubbles to be removed along with floating after collision of the inclusions and the bubbles, and the rising flow formed by the bubble wake flow or the bubble plume can also promote the floating removal of the inclusions in the molten steel.

The prior tundish argon blowing technical means mainly comprise: and (1) argon blowing is carried out at a long nozzle of the tundish. The technology utilizes high-speed shearing flow and turbulence of molten steel flow in a long nozzle to break argon blown from the wall surface of the long nozzle into dispersed small bubbles which enter a high turbulence area in a tundish along with molten steel, collide and adhere and carry impurities to float up to the liquid level of a molten pool. (2) tundish curtain wall. The process is to install a strip-shaped ventilation element at a proper position at the bottom of the tundish, blow argon into the tundish, and form a micro-bubble air curtain barrier perpendicular to the flow direction of molten steel by a large number of bubbles, so as to change the flow track of the molten steel and promote the floating removal of inclusions. And (3) argon blowing process of the tundish stopper rod. Argon is blown downwards through a gas channel or a breathable refractory material at the tip of a stopper rod, and forms micro bubbles under the impact and shearing of molten steel, wherein the argon bubbles enter a tundish upper nozzle and a submerged nozzle along with the molten steel, so that the cleaning effect on the inner wall of the nozzle can be realized, the adhesion amount of inclusions on the inner wall of the nozzle is reduced, and the purpose of preventing the nozzle from being blocked is achieved; and (4) argon blowing process of the tundish upper nozzle pocket block. According to the process, argon is blown into a tundish through a ventilation ceramic rod buried in a pocket block of the water gap, the argon rises around a stopper rod to escape, an annular air curtain barrier is formed above the water gap of the tundish, and molten steel which is about to enter the water gap is cleaned. CN106041045a (application number: 201610634270.7) discloses a continuous casting tundish dispersion type permeable ring upper nozzle pocket block and an argon blowing refining method thereof, wherein a dispersion type permeable ring which is uniformly distributed in a circular shape is arranged in an upper nozzle pocket block body, and after argon is blown in, a complete annular air curtain barrier is formed upwards to perform air washing on molten steel entering an upper nozzle. However, some tiny bubbles enter a water gap and a crystallizer under the process, so that defects such as bubbles under the skin of a casting blank are easily caused. The argon blowing technical means have the problems of unobvious inclusion removal effect, unstable application and the like, and are specifically expressed as follows: the formed bubbles are oversized, the adjustable range of the gas quantity is small, the fluctuation of a steel slag interface is severe, and the application and popularization of the tundish argon blowing process are affected.

According to metallurgical dynamics theory, the argon blowing effect is closely related to the behavior of argon bubbles in molten steel. The number and the size of the bubbles determine the action area between the bubbles and the inclusions and the shape of bubble plumes, so that important influences are generated on the flow mode of molten steel in a molten pool, the fluctuation of a steel slag interface and the removal of the inclusions. The smaller the bubble size, the larger the gas-liquid surface area, and the higher the efficiency of removing impurities by adhering bubbles. The boundary range of the bubble wake flow area and the range of the internal rising area are also related to the size of bubbles, and the bigger the size of the bubbles is, the better the entrainment removal effect of single bubble wake vortex on the impurities is; however, the inclusion removal rate per unit cell volume is higher for small bubbles. The larger the size of the bubbles, the more the number of the bubbles, the stronger the impact of the bubbles on the slag layer, and the more severe the fluctuation of the slag layer; the small bubbles can disperse the impact of the bubbles on the slag layer due to the small floating speed and good diffusivity. Therefore, obtaining ideal small-sized bubbles is key to stabilizing the argon blowing process and improving the inclusion removal effect of the tundish argon blowing process.

The prior method for refining bubbles applied to the field of pyrometallurgy mainly comprises the following steps: CN101245404a (application number: 20080010722. X) discloses a method for refining and dispersing bubbles in molten iron, wherein a stirring paddle is arranged at a position deviated from the center of a container, and a gas injection nozzle is arranged at the lower part of the hollow stirring paddle or a spray gun is used for inserting the stirring paddle into molten iron and injecting gas, and the injected gas is crushed and refined by strong shearing action around the stirring paddle. However, this method requires a large stirring speed, and may cause severe fluctuation of the liquid level during the refining of molten iron, and its application is limited. CN105710348A (application number: 201410721063.6) discloses a device for removing inclusions by thinning bubbles, wherein an electromagnetic brake magnetic field generator is arranged on the side surface of a steel ladle, and an electromagnetic stirrer is arranged on the periphery of an air brick at the bottom of the steel ladle. After the air blowing valve is opened, an electromagnetic stirrer and an electromagnetic braking magnetic field are started, and through electromagnetic stirring, the flowing speed of molten steel near the air brick is accelerated, so that the generation of small bubbles is facilitated. However, the method has the advantages of complex structure, high installation and use cost, small shearing force formed by electromagnetic stirring of molten steel and insignificant bubble refining effect. CN108396109a (application number: 201710064798. X) discloses a method for generating dispersed bubbles in molten steel in a ladle, by arranging an annular air chamber between a steel flow port of a steel tapping hole brick and an outer wall, introducing argon bubbles into molten steel flowing to the ladle, and crushing and refining bubbles generated in molten steel entering the ladle by utilizing the impact energy of the molten steel in the tapping process. But the turbulent motion in the ladle in the tapping process can increase the collision polymerization probability among bubbles, and reduce the bubble refining effect. In summary, various argon blowing technologies and bubble refining methods at present cannot well solve the problems of oversized argon blowing bubble size and poor inclusion removal effect of the tundish. Therefore, to further refine the bubble size in the argon blowing tundish, it is necessary to improve the prior art.

Ultrasonic wave refers to sound wave with frequency exceeding 20kHz, has high frequency, short wavelength, excellent directivity and beam-emission, belongs to the category of mechanical vibration, and can be used for transmitting information and energy. Ultrasonic waves are widely applied in the field of metallurgy due to the cavitation effect and the acoustic streaming effect of ultrasonic waves on the tissue refining effect of metal melt. The ultrasonic technology applied in the tundish comprises the following steps: CN 202377526U (application number: 20120572725. X) and CN 103252459B (application number: 201310225986.8) are provided with an ultrasonic wave guide rod inside the stopper rod through a tundish, so that ultrasonic waves are directly introduced into high-temperature molten steel without affecting molten steel components, and the cleanliness of molten steel in the tundish is improved through ultrasonic treatment. But the limited volume of the stopper rod affects the propagation of ultrasonic energy; meanwhile, the installation of the guided wave rod in the stopper rod has influence on the argon blowing process of the stopper rod, and the annular bubble flow at the tip of the stopper rod is easy to form, so that the liquid level fluctuation of the crystallizer is caused. Up to now, no technology for controlling the bubble generation size of the ventilation element of the argon blowing tundish by ultrasonic waves has been reported.

Disclosure of Invention

Aiming at the problems in the prior art, the utility model provides a device for refining bubbles by ultrasound for a continuous casting argon blowing tundish. By adopting the technical scheme of the utility model, the residence time of bubbles in the tundish and the gas content in the molten steel can be prolonged, the collision adhesion probability of the bubbles and nonmetallic inclusions in the molten steel can be increased, the impact of bubble plumes on the interface of the tundish steel slag can be reduced, and the purposes of purifying the molten steel, stabilizing the liquid level of the tundish and improving the quality of casting blanks can be achieved.

For this purpose, the solution adopted by the utility model is as follows:

an ultrasonic bubble refining device for a continuous casting argon blowing tundish comprises a tundish, wherein an ultrasonic generating device is arranged at the bottom of a ventilation element arranged at the bottom of the tundish; the air permeable element comprises an air permeable brick, an air chamber and an air inlet pipeline, wherein the air chamber is positioned below the air permeable brick and is connected with the argon station through the air inlet pipeline; the ultrasonic generating device comprises an ultrasonic generator, a transducer, a guided wave tool head and a protective shell, wherein the protective shell is buried in refractory materials at the bottom of the tundish, the ultrasonic generator, the transducer and the guided wave tool head which are sequentially connected are arranged in the protective shell, and the ultrasonic generator is connected with an external power supply through a wire; the guided wave tool head faces the gas permeable member.

Preferably, the air brick is a dispersion type air brick or a combination type air element thereof, wherein the porosity of the dispersion type air brick ranges from 0.25 to 0.35, the median pore diameter ranges from 50 to 150 mu m, and the average pore diameter ranges from 5 to 20 mu m.

Preferably, materials used for the wave guiding tool head and the protective housing of the ultrasonic wave generating device include, but are not limited to, metallic materials, inorganic nonmetallic materials and combinations thereof.

Preferably, the output impedance of the transducer is 60 ohms and the ultrasonic frequency range is 25-60 kHz.

The beneficial effects of the utility model are as follows:

(1) The ultrasonic cavitation effect can be utilized, so that bubbles formed at the orifice position of the ventilation element vibrate, grow and desorb under the action of ultrasonic waves, and small bubbles with uniform size are generated through regulation and control; thereby prolonging the residence time of the bubbles in the tundish, increasing the air content in the tundish, facilitating the collision and adhesion of the bubbles with fine inclusions and promoting the floating removal of the bubbles in the tundish.

(2) The impact of bubble plumes formed by argon blowing of the tundish on the steel slag interface of the tundish can be reduced, and the adjustable range of the argon blowing amount is increased.

(3) The ultrasonic bubble refining device provided by the utility model has the advantages of simple structure, convenience in installation and low use and later maintenance cost, and is suitable for argon blowing tundish of various specifications.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.

Fig. 1 is a schematic diagram of a continuous casting argon blowing tundish bubble refining apparatus.

Fig. 2 is a schematic view of a ventilation element.

Fig. 3 is a schematic view of an ultrasonic wave generating apparatus.

Reference numerals illustrate: 1. a tundish; 2. an air brick; 3. an ultrasonic wave generating device; 4. an air brick; 5. a gas chamber; 6. an air intake duct; 7. an ultrasonic generator; 8. a transducer; 9. a guided wave tool head; 10. and a protective housing.

Detailed Description

Other advantages and effects of the present utility model will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present utility model with reference to specific examples. The utility model may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present utility model. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict.

In the description of the present utility model, unless otherwise indicated, the meaning of "a plurality" is two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "head," "tail," and the like are used as an orientation or positional relationship based on that shown in the drawings, merely to facilitate description of the utility model and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the utility model. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present utility model, it should be noted that, unless explicitly specified and limited otherwise, the terms "connected," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

The following describes in further detail the embodiments of the present utility model with reference to the drawings and examples.

The embodiment of the utility model provides a device for refining bubbles by ultrasonic waves for a continuous casting tundish, which mainly comprises a tundish 1, a ventilation element 2 and an ultrasonic wave generating device 3 as shown in figure 1. The bottom of the tundish 1 is provided with a ventilation element 2; the ultrasonic wave generating device 3 is arranged at the bottom of the ventilation element 2 and is buried in the refractory material at the bottom of the tundish 1.

Further, as shown in fig. 2 and 3, the ventilation element 2 includes a ventilation brick 4, a gas chamber 5, and a gas inlet pipe 6, wherein the gas chamber 5 is located below the ventilation brick 4 and is connected with an argon station through the gas inlet pipe; the ultrasonic generating device 3 comprises an ultrasonic generator 7, a transducer 8, a guided wave tool head 9 and a protective shell 10, wherein the protective shell 10 is buried in refractory materials at the bottom of the tundish 1, the ultrasonic generator 7, the transducer 8 and the guided wave tool head 9 which are sequentially connected are arranged in the protective shell 10, and the ultrasonic generator 7 is connected with an external power supply through a wire; the guided wave tool head 9 is directed towards the gas permeable element 2.

The present utility model will be described in detail by the following specific examples of water model experiments, which are only for explanation of the present utility model, but not for limitation of the present utility model.

Example 1:

according to a similar principle, a 1:1 ratio single-flow slab continuous casting tundish water model is utilized to simulate the actual continuous casting process in the tundish, water is utilized to simulate molten steel in the tundish, silicone oil is utilized to simulate a covering agent in the tundish, and polyethylene is utilized to simulate inclusions. The air brick in the air permeable element is corundum dispersion air brick, the porosity of the air brick is 0.28, the median pore diameter is 62.2 mu m, and the average pore diameter is 6.1 mu m. The size of the air brick is 1.2m multiplied by 0.1m; the ultrasonic generating device is arranged at the bottom of the air brick; the wave guiding tool head and the protective shell of the ultrasonic generating device are made of 304 stainless steel materials.

In the experimental process, an air inlet valve is opened, argon is blown into the tundish through an air inlet pipe and a ventilation element, the argon blowing amount is controlled to be 0.6NL/min, the argon blowing pressure is controlled to be 0.12MPa, meanwhile, an ultrasonic generating device is opened, the power is set to be 400W, and the frequency is set to be 30kHz. When the simulated molten steel does not have a long water gap, a simulated covering agent is added into the tundish, and the thickness of the covering agent is 50mm. Slowly increasing the argon blowing amount and preventing the simulated molten steel from being exposed due to overlarge fluctuation of the liquid level in the tundish. Compared with a device for refining bubbles without adopting ultrasound, by means of the device and the method, when the argon blowing amount is 4L/min, the average size of initial bubbles generated by the air brick is thinned to 2mm from 5mm, the average residence time of the bubbles in a tundish is increased by 13%, the air inclusion rate in the tundish is increased by 10%, the critical slag rolling argon blowing amount is increased to 8NL/min from 6NL/min, the removal rate of <50 mu m inclusion is increased by 35%, and good effects of removing fine inclusion and purifying molten steel are realized.

Example 2:

according to a similar principle, a 1:2 ratio double-flow slab continuous casting tundish water model is utilized to simulate the actual continuous casting process in the tundish, water is utilized to simulate molten steel in the tundish, silicone oil is utilized to simulate a covering agent in the tundish, and polyethylene is utilized to simulate inclusions. The air brick in the air permeable element is corundum dispersion air brick, the porosity of the air brick is 0.31, the median pore diameter is 98.2 mu m, and the average pore diameter is 12.1 mu m. The size of the air brick is 0.6mx0.08mx0.08m; the ultrasonic generating device is arranged at the bottom of the air brick; the wave guiding tool head and the protective shell of the ultrasonic generating device are made of 304 stainless steel materials.

In the experimental process, an air inlet valve is opened, argon is blown into the tundish through an air inlet pipe and a ventilation element, the argon blowing amount is controlled to be 0.8NL/min, the argon blowing pressure is controlled to be 0.15MPa, and meanwhile, an ultrasonic generating device is opened, the power is set to be 500W, and the frequency is set to be 40kHz. When the simulated molten steel does not have an overlong water gap, a simulated covering agent is added into the tundish, the thickness of the covering agent is 20mm, the argon blowing amount is slowly increased, and the phenomenon that the simulated molten steel is exposed due to overlarge fluctuation of the liquid level in the tundish is prevented. Compared with a device for refining bubbles without adopting ultrasonic waves, by means of the device and the method, when the argon blowing amount is 3NL/min, the average size of initial bubbles generated by the air brick is thinned to 3.7mm from 6.3mm, the average residence time of the bubbles in a tundish is increased by 20%, the air content in the tundish is increased by 14%, the critical slag rolling argon blowing amount is increased to 6NL/min from 4NL/min, the removal rate of <50 mu m inclusion is increased by 54.3%, and good effects of removing fine inclusion and purifying molten steel are realized.

The above embodiments are only for illustrating the present utility model, not for limiting the present utility model, and various changes and modifications may be made by one of ordinary skill in the relevant art without departing from the spirit and scope of the present utility model, and therefore, all equivalent technical solutions are also within the scope of the present utility model, and the scope of the present utility model is defined by the claims.

Claims (4)

1. The device for ultrasonically refining bubbles for the continuous casting argon blowing tundish is characterized by comprising a tundish, wherein an ultrasonic generating device is arranged at the bottom of a ventilation element arranged at the bottom of the tundish; the air permeable element comprises an air permeable brick, an air chamber and an air inlet pipeline, wherein the air chamber is positioned below the air permeable brick and is connected with the argon station through the air inlet pipeline; the ultrasonic generating device comprises an ultrasonic generator, a transducer, a guided wave tool head and a protective shell, wherein the protective shell is buried in refractory materials at the bottom of the tundish, the ultrasonic generator, the transducer and the guided wave tool head which are sequentially connected are arranged in the protective shell, and the ultrasonic generator is connected with an external power supply through a wire; the guided wave tool head faces the gas permeable member.

2. The apparatus for ultrasonic refining of bubbles for continuous casting argon blowing tundish according to claim 1, wherein the air brick is a dispersion type air brick or a combination type air permeable element thereof, wherein the porosity of the dispersion type air brick ranges from 0.25 to 0.35, the median pore diameter ranges from 50 to 150 μm, and the average pore diameter ranges from 5 to 20 μm.

3. The apparatus for ultrasonic bubble refinement for continuous casting argon blowing tundish according to claim 1, wherein the materials used for the wave guiding tool head and the protective casing of the ultrasonic wave generating apparatus include, but are not limited to, metallic materials, inorganic nonmetallic materials and combinations thereof.

4. The apparatus for ultrasonic bubble refinement for continuous casting argon blowing tundish according to claim 1, wherein the output impedance of the transducer is 60 ohm and the ultrasonic frequency range is 25 to 60kHz.