CN114472818A - Device for effectively removing impurities by blowing at bottom of cyclone chamber and using method - Google Patents

Abstract

A device for effectively removing impurities by blowing air at the bottom of a swirl chamber and a using method thereof comprise the swirl chamber, a long nozzle, an air blowing device and a channel; the cyclone chamber is of a barreled structure, one end of the long nozzle is tangent to the inner wall of the cyclone chamber or one end of the long nozzle is tangent to the inner wall of the cyclone chamber, and the long nozzle is offset to the center of the cyclone chamber by a distance L₂，L₂≤D₁/4 wherein D₁The cyclone chamber is connected with the top of the side wall of the middle bag body through a channel. The invention blows air at the bottom of the cyclone chamber, the air bubbles gather to the center of the cyclone chamber under the action of the cyclone, and the impurities gather to the center under the action of the cyclone. The two areas are the same in the cyclone chamber, which is favorable for the adhesion, collision and polymerization of the grown impurities by bubbles, especially for small-particle-size impurities which are difficult to be removed by floating, the adhesion of the bubbles improves the removal rate of the small-particle-size impuritiesThe integral removing rate of the impurities is greatly improved.

Description

A device and method for effectively removing inclusions by blowing air at the bottom of a cyclone chamber

technical field

The invention belongs to the technical field of continuous casting of iron and steel metallurgy, and particularly relates to a device for effectively removing inclusions by blowing air at the bottom of a cyclone chamber and a method for using the same.

Background technique

In order to improve production efficiency, modern steel enterprises usually use continuous casting technology. During the continuous casting process, the molten steel in the tundish enters the mold through the sliding nozzle and the submerged nozzle, and the injection volume of the molten steel from the tundish to the mold and the flow of the molten steel in the mold are realized by the cooperation of the stopper rod and the sliding nozzle. The control of behavior is very important for stable operation and guaranteeing the quality of the slab. Among the many metallurgical functions of the tundish, the degree of inclusion removal has always been a major concern of metallurgists. For molten steel continuous casting, the removal of inclusions in the tundish not only has a great impact on the quality of the continuous casting billet, but also has an important impact on the continuous operation of continuous casting. Continuous casting has a great impact.

In the metallurgical production process, tundish metallurgy is a special out-of-furnace refining technology, which is a key link in the production process from steel smelting and refining to solid-state continuous casting slabs to ensure high-quality steel.

There are two main methods for removing inclusions in the tundish:

1. Install the flow control device. For example, dams, weirs, baffles and turbulence suppressors can increase the residence time of molten steel in the tundish, increase the volume of the plug flow, reduce the dead zone, improve the flow field of molten steel, and facilitate the floating and removal of inclusions; but The traditional method of installing the flow control device has obvious effect on the removal of inclusions with large particle size, but has no obvious effect on the removal of inclusions with small particle size.

2. Blow the tundish, that is, inject inert gas. For example, in the air curtain retaining wall, air blowing can improve the flow field of the tundish, and the blown air bubbles can adhere to the inclusions, which is beneficial to the removal of inclusions. However, there is a "triangular" blind area in the tundish of the gas curtain wall, and the effect of adhesion and removal of inclusions is limited.

SUMMARY OF THE INVENTION

The object of the present invention is a device and method for effectively removing inclusions by blowing air at the bottom of a swirl chamber, which has a simple structure, is convenient to process and operate, can effectively remove inclusions, and improves the clogging of the submerged nozzle. Create conditions for quality and improvement of long shroud blockage.

A device for effectively removing inclusions by blowing air at the bottom of a cyclone chamber, comprising a cyclone chamber, a long nozzle, an air blowing device and a channel; the cyclone chamber is a barreled structure, and one end of the long nozzle is tangent to the inner wall of the cyclone or One end of the long shroud is set tangentially along the inner wall of the cyclone, and is offset to the center of the cyclone by a distance L ₂ , L ₂ ≤ D ₁ /4, where D ₁ is the outer diameter of the cyclone, and the tangent position of the long shroud is separated from the center of the cyclone. The height H ₃ of the bottom of the chamber is less than 5 times the diameter d of the long nozzle, the upper surface of the bottom plate of the cyclone chamber is provided with a groove, and the blowing device is embedded in the groove of the bottom plate of the cyclone chamber, and the cyclone chamber passes through the channel and the middle. The top of the side wall of the package body is connected.

The shape of the air blowing device is a circular ring, and is embedded in the annular groove of the bottom plate of the swirl chamber. The axis coincides with the axis of the swirl chamber.

The air blowing device is an annular ventilation brick, and the air blowing device is composed of single or multiple annular ventilation bricks. When there are multiple annular ventilation bricks, the axes of the multiple annular ventilation bricks are all coincident with the axis of the cyclone chamber.

When it is a single annular breathable brick, the thickness B1 of the annular breathable brick is 0.2 to ₁ times the inner diameter d of the long shroud; when it is a multi-annular breathable brick, the thickness B1 _of the annular breathable brick is 0.2 to 0.8 of the inner diameter d of the long nozzle times.

When there are multiple annular ventilation bricks, the distance L1 between two adjacent annular ventilation bricks is _0.5-3 times the thickness B1 _of the annular ventilation bricks.

When it is a single annular breathable brick, its inner diameter D2 is 0.3 to 0.95 times the outer diameter D1 _of the swirl chamber _; when it is a plurality of annular breathable bricks, the inner diameter D2 of the largest annular breathable brick is the diameter _{D1 of} the swirl chamber 0.3 to 0.95 times.

The diameter of the bubbles blown by the air blowing device is 0.1-3mm. When the gas enters the cyclone chamber through the breathable brick, the bubbles can form bubbles with a diameter of 0.1-3mm under the shearing action of the molten steel in the cyclone chamber.

The method for calculating the interval of the air blowing volume Q of the air blowing device is that the volume of the injected gas does not exceed one tenth of the inflow volume of the molten steel, and is not less than five thousandths of the inflow volume of the molten steel. Too little gas can not form enough bubbles to adhere to the inclusions, and too much gas will destroy the molten steel swirl, and even cause slag holes and molten molten steel to splash.

A method for using a device for effectively removing inclusions by blowing air at the bottom of a cyclone chamber to remove inclusions comprises the following steps:

The molten steel enters the swirl chamber from the ladle through the long nozzle, and then enters the tundish. Under the action of the swirl chamber, the molten steel enters the swirl chamber along the side wall of the swirl chamber, and the swirl chamber converts the gravitational potential energy of the molten steel into The kinetic energy of the rotation, the molten steel rotates and flows in the swirl chamber, and a swirl field is formed in the swirl chamber, and the inclusions interact with the molten steel in the swirl field. Inert gas, the bubbles enter the swirl chamber through the breathable brick, and the blown gas forms bubbles under the swirl shearing, the bubbles gather in the center of the swirl chamber under the action of the swirl flow, and the inclusions also swirl under the action of the swirl flow. The center of the flow chamber gathers. During this process, the bubbles adhere and collide with the aggregated inclusions. After the bubbles adhere to the inclusions, the inclusions float up to the surface of the molten steel for removal.

The technical effect of the present invention is:

Compared with the traditional swirl tundish, the present invention blows air at the bottom of the swirl chamber, the bubbles gather to the center of the swirl chamber under the action of the swirl flow, and the inclusions also gather toward the center under the action of the swirl flow. The two gather in the same area in the cyclone chamber, which is conducive to the adhesion of bubbles to the inclusions that have grown and collided, especially for small particle sizes that are difficult to remove by floating. The overall removal rate of inclusions is greatly improved, and the removal of inclusions with small particle size will improve the clogging of the submerged nozzle, which is beneficial to the smooth progress of continuous casting. The structure of the invention is simple, and the processing and operation are convenient.

Description of drawings

Fig. 1 is a schematic diagram of a device for effectively removing inclusions by blowing air at the bottom of a cyclone chamber of the present invention;

Fig. 2 is the cyclone chamber sectional view of the device for effectively removing inclusions by blowing air at the bottom of the cyclone chamber of the present invention;

3 is a schematic diagram of the coordination between a single annular breathable brick and a bottom plate of the cyclone chamber of the device for effectively removing inclusions by blowing air at the bottom of the cyclone chamber of the present invention;

4 is a schematic diagram of the cooperation between a plurality of annular ventilation bricks and the bottom plate of the cyclone chamber of the device for effectively removing inclusions by blowing air at the bottom of the cyclone chamber according to the present invention;

5 is a side view of the cyclone chamber of the device for effectively removing inclusions by blowing air at the bottom of the cyclone chamber of the present invention;

6 is a schematic diagram of the force of the bubbles and inclusions in the cyclone chamber of the present invention;

Fig. 7 velocity distribution curve of molten steel of the present invention in the radial direction at the bottom of the swirl chamber;

1- Cyclone chamber, 2- Long nozzle, 3- Channel, 4- Intermediate inclusion, 5- Air blowing device, 6- Groove.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figures 1 to 5, a device for effectively removing inclusions by blowing air at the bottom of a cyclone chamber includes a cyclone chamber 1, a long nozzle 2, an air blowing device 5 and a channel 3; the cyclone chamber 1 is a bucket The installation structure, one end of the long nozzle 2 is tangent to the inner wall of the cyclone chamber 1 or one end of the long nozzle 2 is arranged tangentially along the inner wall of the cyclone chamber 1, and is offset to the center of the cyclone chamber 1 by a distance L ₂ , L ₂ ≤ D ₁ /4 , where D ₁ is the outer diameter of the swirl chamber 1, the height H ₃ of the tangential position of the long nozzle 2 from the bottom of the swirl chamber 1 is less than 5 times the diameter d of the long nozzle 2, and the upper surface of the bottom plate of the swirl chamber 1 is provided with a groove 6. The blowing device 5 is embedded in the groove 6 of the bottom plate of the swirl chamber 1 , and the swirl chamber 1 is connected to the top of the side wall of the intermediate enclosure 4 through the channel 3 .

The shape of the air blowing device 5 is a circular ring, and is embedded in the annular groove 6 of the bottom plate of the swirl chamber 1, and the upper surface of the air blowing device 5 and the upper surface of the bottom plate of the swirl chamber 1 are on the same plane. , the axis of the blowing device 5 coincides with the axis of the swirl chamber 1 .

The air blowing device 5 is an annular ventilation brick, and the air blowing device 5 is composed of a single or multiple annular ventilation bricks. When it is a plurality of annular ventilation bricks, the axes of the multiple annular ventilation bricks coincide with the axis of the cyclone chamber 1. .

When it is a single annular breathable brick, the thickness B1 of the annular breathable brick is 0.2 to ₁ times the inner diameter d of the long nozzle 2, and when it is a multi-annular breathable brick, the thickness B1 _of the annular breathable brick is 0.2 of the inner diameter d of the long nozzle 2 ~0.8 times.

When there are multiple annular ventilation bricks, the distance L1 between two adjacent annular ventilation bricks is _0.5-3 times the thickness B1 _of the annular ventilation bricks.

When it is a single annular breathable brick, its inner diameter D2 is 0.3 to 0.95 times the outer diameter D1 _of the swirl chamber ₁ ; when it is a plurality of annular breathable bricks, the inner diameter D2 of the largest annular breathable brick is the swirl chamber ₁ 0.3 to _0.95 times the outer diameter D1.

The diameter of the bubbles blown by the air blowing device 5 is 0.1-3mm. When the gas enters the cyclone chamber 1 through the air-permeable brick, the bubbles can form a diameter of 0.1-3mm under the shearing action of the molten steel in the cyclone chamber 1. bubble.

The interval calculation method of the air blowing volume Q of the air blowing device 5 is that the volume of the injected gas does not exceed one tenth of the inflow volume of the molten steel, and is not less than five thousandths of the inflow volume of the molten steel. Too little gas can not form enough bubbles to adhere to the inclusions, and too much gas will destroy the molten steel swirl, and even cause slag holes and molten molten steel to splash.

A method for using a device for effectively removing inclusions by blowing air at the bottom of a cyclone chamber to remove inclusions comprises the following steps:

The molten steel enters the swirl chamber 1 from the ladle through the long nozzle 2, and then enters the tundish 4. Under the action of the swirl chamber 1, the molten steel enters the swirl chamber 1 along the side wall of the swirl chamber 1. The gravitational potential energy of the molten steel is converted into rotational kinetic energy, the molten steel rotates and flows in the swirl chamber 1, and a swirl field is formed in the swirl chamber 1, and the inclusions interact with the molten steel in the swirl field with the molten steel; After the flow field is formed, blow inert gas at the bottom of the swirl chamber 1, and the bubbles enter the swirl chamber 1 through the breathable bricks. The inclusions gather in the center, and the inclusions also gather in the center of the swirl chamber 1 under the action of the swirl flow. During this process, the bubbles adhere to the inclusions that have grown and collided, and the bubbles adhere to the inclusions and carry the inclusions up to the surface of the molten steel for removal.

The trajectory of bubbles and inclusions in molten steel is mainly related to the force they are subjected to. As shown in Figure 6, inclusions and bubbles are mainly affected by drag force F _D , pressure gradient force F _p , gravity, buoyancy, virtual mass force Fv, Saffman lift F _LS , and Magnus lift F _LM in the rotating flow field. The main forces for the movement of inclusions and bubbles to the center are the drag force F _D , the pressure gradient force F _p , the Saffman lift force F _LS , and the Magnus lift force F _LM , which means that F _P +F _V -F _LS -F _LM >F _{centrifugal force} When the inclusions or bubbles move to the center of the cyclone chamber 1. The numerical simulation results show that the inclusions and bubbles in the swirl chamber 1 gather to the center of the swirl chamber 1 obviously, and the inclusions gather toward the center area. grow up. And the main accumulation area of the inclusions coincides with the accumulation area of the bubbles, which greatly improves the efficiency of the bubbles adhering to the inclusions.

Advantages of annular blowing: blowing at the bottom of the cyclone chamber 1 needs to meet two problems. The first blowing air volume should not be too large, and blowing a large amount of gas will destroy the flow field of the cyclone chamber 1; the second blowing air produces The bubbles should not be too large, and the adhesion of large bubbles to inclusions is poor. According to these two aspects, a plan for annular blowing is proposed. First, the air is blown at the bottom of the swirl chamber 1, and the bottom blowing has little effect on the flow field. Secondly, the bubbles generated by the annular blowing are from the outer area of the swirl chamber 1. Moving toward the center, the moving path of the bubble is longer, and more inclusions are skipped, and the accumulation area of the annular blowing bubble is more coincident with the accumulation area of the inclusions. Third, the position of the annular blowing gas coincides with the position where the molten steel flow rate is the largest in the cyclone chamber 1. As shown in Figure 7, a larger shear rate is more conducive to the generation of small bubbles. Taking into account the above factors, annular blowing is the most suitable. The multi-ring blow can adjust the flexibility of the blow operation.

Claims (9)

1. A device for effectively removing impurities by blowing air at the bottom of a cyclone chamber is characterized by comprising the cyclone chamber, a long water gap, an air blowing device and a channel; the cyclone chamber is of a barreled structure, one end of the long nozzle is tangent to the inner wall of the cyclone chamber or one end of the long nozzle is tangent to the inner wall of the cyclone chamber, and the long nozzle is offset to the center of the cyclone chamber by a distance L₂，L₂≤D₁/4 wherein D₁The height H from the center of the tangent position of the long nozzle to the bottom of the swirl chamber is the outer diameter of the swirl chamber₃Less than 5 times long mouth of a river diameter d, the spiral-flow chamber bottom plate upper surface is seted up flutedly, and gas blowing device is embedded in the recess of spiral-flow chamber bottom plate, the spiral-flow chamber passes through the passageway and is connected with middle inclusion lateral wall top.

2. The device for effectively removing the inclusions by blowing at the bottom of the whirling chamber as claimed in claim 1, wherein: the air blowing device is in a ring shape and is embedded in the annular groove of the bottom plate of the cyclone chamber, the upper surface of the air blowing device and the upper surface of the bottom plate of the cyclone chamber are on the same plane, and the axis of the air blowing device is superposed with the axis of the cyclone chamber.

3. The device for effectively removing the inclusions by blowing air at the bottom of the whirling chamber as claimed in claim 2, wherein: the diameter of the bubbles blown by the blowing device is 0.1-3 mm.

4. The device for effectively removing the inclusions by blowing air at the bottom of the whirling chamber as claimed in claim 2, wherein: the interval calculation method of the blowing quantity Q of the blowing device is that the volume of blown gas is not more than one tenth of the inflow volume of the molten steel and is not less than five thousandths of the inflow volume of the molten steel.

5. The device for effectively removing the inclusions by blowing at the bottom of the whirling chamber as claimed in claim 1, wherein: the air blowing device is an annular air brick and consists of one or more annular air bricks, and when the air blowing device is a plurality of annular air bricks, the axes of the annular air bricks are coincided with the axis of the cyclone chamber.

6. The device for effectively removing the inclusions by blowing air at the bottom of the whirling chamber as claimed in claim 3, wherein: when the air brick is a single annular air brick, the thickness B of the annular air brick₁Is 0.2 to 1 time of the inner diameter d of the long nozzle, and when the long nozzle is a multi-annular air brick, the thickness B of the annular air brick₁Is 0.2 to 0.8 times of the inner diameter d of the long nozzle.

7. The device for effectively removing the inclusions by blowing air at the bottom of the whirling chamber as claimed in claim 3, wherein: when the annular air brick is a plurality of annular air bricks, the distance L between two adjacent annular air bricks₁Is the thickness B of the annular air brick₁0.5-3 times of the total weight of the powder.

8. The device for effectively removing the inclusions by blowing air at the bottom of the whirling chamber as claimed in claim 3, wherein: when being a single annular air brick, the inner diameter D of the air brick₂Is the outer diameter D of the swirl chamber₁0.3-0.95 times of; when the annular air brick is a plurality of annular air bricks, the inner diameter D of the largest annular air brick is₂Is the outer diameter D of the swirl chamber₁0.3 to 0.95 times of the amount of the active ingredient.

9. The use method of the device for effectively removing the inclusions by blowing at the bottom of the whirling chamber according to claim 1 is characterized by comprising the following steps:

molten steel enters the cyclone chamber from a steel ladle through the long nozzle and then enters the tundish body, the molten steel enters the cyclone chamber along the side wall of the cyclone chamber under the action of the cyclone chamber, the gravitational potential energy of the molten steel is converted into rotary kinetic energy by the cyclone chamber, the molten steel rotates and flows in the cyclone chamber to form a cyclone field in the cyclone chamber, and inclusions interact with the molten steel in the cyclone field along with the molten steel; after the rotational flow field is formed, inert gas is blown to the bottom of the rotational flow chamber, bubbles enter the rotational flow chamber through the air brick, the blown gas forms bubbles under rotational flow shearing, the bubbles are gathered to the center of the rotational flow chamber under the action of rotational flow, impurities are gathered to the center of the rotational flow chamber under the action of rotational flow, the bubbles adhere to and collide with the grown impurities, and the bubbles carry the impurities to float to the surface of molten steel to be removed after the impurities adhere to the bubbles.

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