A middle injection module, bottom injection protection pouring system and method for a tundish

Abstract

The application belongs to the technical field of metallurgy, and discloses a middle injection module, a bottom injection protection pouring system and a method for a tundish. The middle injection module comprises a middle injection pipe and a heating device, the middle injection pipe is located below the tundish, a plurality of interval distributed filter layers are arranged in the inner cavity of the middle injection pipe from top to bottom, and the pore diameter of adjacent two filter layers gradually decreases from top to bottom. The bottom injection protection pouring system comprises the middle injection module, a nozzle package, a dismounting device and an elastic compensation device. The bottom injection protection pouring method comprises air washing, positive pressure protection and temperature compensation. The application can make the inclusions of the molten steel float and be filtered so as to achieve the purpose of purifying the molten steel. Through the system in the positive pressure protection gas protection, the temperature of the molten steel can be quickly compensated, so that the temperature fluctuation of the molten steel in the tundish is within 2 degrees during the whole bottom injection process, and the required temperature control precision for continuously preparing wide ultra-thin nanocrystalline strip is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgy, and particularly relates to a middle pouring module for a tundish, a bottom pouring protective pouring system and method. BACKGROUND

[0002] In the production of nanocrystalline strip at home and abroad, the master alloy liquid is generally smelted by an induction furnace, then is subjected to liquid steel settling and production rhythm buffering by different forms of tundish, and is subjected to ultra-thin nanocrystalline strip production by a plane flow casting strip process. Due to the production process characteristics of the ultra-thin strip, the master alloy liquid must be highly purified. In the continuous production of nanocrystalline strip, the liquid steel is supplied to the nozzle package from the tundish bottom nozzle to realize continuous production. The liquid steel is poured into the middle pouring pipe from the bottom nozzle of the tundish, then flows into the nozzle package from the bottom of the middle pouring pipe, and finally is sprayed from the lower end nozzle gap of the nozzle package to the high-speed rotating crystallizer to form an ultra-thin strip. During the bottom pouring process, the tundish bottom nozzle, the upper nozzle of the nozzle package and the lower nozzle of the middle pouring pipe are sealed and connected by a special device. If there is a defect such as poor sealing in this space, the liquid steel flow will be in contact with the atmosphere, thereby causing secondary oxidation of the liquid steel. At the same time, the middle pouring pipe is exposed to the atmosphere, which will cause a significant temperature drop, and then the high-melting-point inclusions in the liquid steel will be precipitated. The formation of new oxides and the increase of inclusions will deteriorate the purity of the liquid steel. The inclusions in the liquid steel will be precipitated and formed into nodules at the nozzle gap, which will seriously affect the surface quality of the strip, causing scratches, splitting and even blocking the nozzle to cause the spraying to stop. Therefore, how to adopt protective pouring and reduce the precipitation of high-melting-point inclusions in the bottom pouring process has become a major limiting factor for further improving the continuous production of wide ultra-thin nanocrystalline strip.

[0003] At present, the nanocrystalline plane flow casting strip protective pouring has the following technical problems:

[0004] The liquid steel in the middle pouring pipe has a large heat loss, and it is difficult to heat the high-speed moving liquid steel. SUMMARY

[0005] The purpose of the present application is to provide a middle pouring module for a tundish, a bottom pouring protective pouring system and method, which can make the inclusions in the liquid steel float and be filtered to achieve the purpose of purifying the liquid steel, solve the problem of a large amount of inclusions precipitating, quickly heat the temperature of the liquid steel, make the temperature of the liquid steel in the tundish fluctuate within 2 degrees during the entire bottom pouring process, and achieve the temperature control precision required for the continuous preparation of wide ultra-thin nanocrystalline strip.

[0006] The above purpose of the application is achieved by the following technical scheme:

[0007] The application provides a middle injection module for a tundish, which comprises a middle injection pipe and a heating device, the heating device is wrapped outside the middle column pipe, the middle injection pipe is located below the tundish and has a liquid inlet and a liquid outlet, a plurality of filter layers are distributed in the middle injection pipe cavity along the direction from the liquid inlet to the liquid outlet, a liquid storage area is formed between each two adjacent filter layers in the middle injection pipe cavity, and the filter pore size of the filter layer close to the liquid outlet is smaller than that of the filter layer close to the liquid inlet.

[0008] The middle injection module for the tundish, wherein each filter layer is a zirconia foam ceramic filter screen.

[0009] The middle injection module for the tundish, wherein the middle injection pipe is provided with a protective gas inlet and a protective gas outlet, the protective gas inlet is located on the side of the liquid storage area away from the liquid inlet, and the protective gas outlet is located on the side of the liquid storage area towards the liquid inlet.

[0010] The middle injection module for the tundish, wherein the heating device is a layer structure comprising a heat supplement layer, a heat preservation layer, an induction coil and a protective layer arranged from inside to outside.

[0011] The middle injection module for the tundish, wherein a temperature control unit is further included, the temperature control unit comprises an induction coil adjusting module, a temperature measuring element and a PLC controller, the temperature measuring element is arranged at a temperature measuring port of the heating device and is used to collect the liquid steel temperature at the corresponding position in the middle injection pipe, the induction coil adjusting module is electrically connected with the induction coil, and the PLC controller is electrically connected with the induction coil adjusting module and the temperature measuring element.

[0012] The application provides a middle injection protective pouring system for a tundish, which comprises the middle injection module for the tundish.

[0013] The middle injection protective pouring system for the tundish, wherein the upper end of the middle injection pipe is provided with a dismounting device for realizing quick mounting and dismounting with the tundish.

[0014] The middle injection protective pouring system for the tundish, wherein an elastic compensation device is arranged above the dismounting device, one end of the elastic compensation device is connected with the dismounting device, the other end of the elastic compensation device is connected with the lower end of the tundish, the elastic compensation device can flexibly adjust the middle injection pipe, the axis of the middle injection pipe in the vertical state is coaxial with the downspout runner of the tundish, and the liquid steel flows along the axis of the middle injection pipe during pouring of the tundish.

[0015] The intermediate ladle bottom pouring protection pouring system, wherein the upper end of the nozzle bag is provided with a nozzle bag air inlet communicated with the nozzle bag inner cavity, and the protection gas outlet is provided with a pressure control valve; the upper end of the nozzle bag is fixedly connected with a supporting device, the upper end of the supporting device is provided with a quick locking device, and the quick locking device is connected with the lower part of the middle pouring pipe.

[0016] The application provides an intermediate ladle bottom pouring protection pouring method based on the intermediate ladle bottom pouring protection pouring system.

[0017] (1) gas washing: before pouring, the protection gas is filled from the nozzle bag air inlet, the protection gas is an inert gas with a density greater than air, and the protection gas fills the nozzle bag and the middle pouring pipe;

[0018] (2) positive pressure protection: after pouring starts, the protection gas inlet is opened and the protection gas is introduced, the protection gas is an inert gas with a density greater than air, the steel liquid buffer zone forms a dynamic stable storage pool, and the positive pressure in the middle pouring pipe is adjusted by the pressure control valve at the protection gas outlet;

[0019] (3) temperature compensation: the PLC controller adjusts the temperature of the electromagnetic coil through the inductor adjustment module according to the middle pouring pipe temperature information collected by the temperature measuring part, so that the temperature compensation of the steel liquid is realized.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] (1) the application can make the inclusions in the steel liquid float up and be filtered by the filter layer during the intermediate ladle bottom pouring process, so that the purpose of purifying the steel liquid is achieved.

[0022] (2) the application can make the system be in the positive pressure protection gas protection, and solve the problem that the steel liquid oxygen content is greatly increased due to the fact that the argon sealing is not strict in the prior art.

[0023] (3) the inductor heating of the application can heat the heat compensation layer, the temperature of the steel liquid can be quickly adjusted, the temperature fluctuation of the steel liquid in the intermediate ladle is within 2 degrees during the whole bottom pouring process, and the temperature control precision required for continuously preparing wide ultra-thin nanocrystalline strip materials is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 it is a cross-sectional structure schematic view of the middle pouring module for the intermediate ladle in the application;

[0025] Figure 2 it is a cross-sectional structure schematic view of the middle pouring pipe in the application;

[0026] Figure 3 it is a partial cross-sectional structure schematic view of the multilayer structure of the heating device in the application;

[0027] Figure 4 The figure is a schematic diagram of the sectional structure of the tundish bottom protection pouring system in the application.

[0028] Reference signs:

[0029] 1, middle injection pipe; 11, liquid inlet; 12, liquid outlet; 13, first filter layer; 14, second filter layer; 15, protective gas inlet; 16, protective gas outlet; 2, heating device; 21, heat supplementing layer; 22, heat preservation layer; 23, induction coil; 24, protective layer; 3, dismounting device; 4, elastic compensation device; 5, nozzle package; 51, nozzle package gas inlet; 6, quick locking device; 7, supporting device; 8, tundish; 9, stopper A, liquid steel buffer area. DETAILED DESCRIPTION

[0030] The following will be described in detail in combination with the accompanying Figures 1-4 The application will be further described in detail.

[0031] Example 1

[0032] As shown in the figure, a middle injection module for a tundish comprises a middle injection pipe 1 and a heating device 2, the heating device 2 is wrapped outside the middle injection pipe 1, and the heating device 2 can heat the liquid steel in the middle injection pipe 1. Figure 1

[0033] As shown in the figure, the middle injection pipe is located below the tundish 8 and has a liquid inlet 11 and a liquid outlet 12, along the direction from the liquid inlet 11 to the liquid outlet 12, a plurality of filter layers are distributed in the inner cavity of the middle injection pipe 1, and the position between each adjacent two filter layers in the inner cavity of the middle injection pipe 1 forms a liquid steel buffer area A, and along the direction from the liquid inlet 11 to the liquid outlet 12 of the middle injection pipe 1, in each adjacent two filter layers, the filter pore size of the filter layer close to the liquid outlet 12 is smaller than that of the filter layer close to the liquid inlet 11. Figure 2 4

[0034] As shown in the figure, the middle injection pipe is located below the tundish 8 and has a liquid inlet 11 and a liquid outlet 12, along the direction from the liquid inlet 11 to the liquid outlet 12, a plurality of filter layers are distributed in the inner cavity of the middle injection pipe 1, and the position between each adjacent two filter layers in the inner cavity of the middle injection pipe 1 forms a liquid steel buffer area A, and along the direction from the liquid inlet 11 to the liquid outlet 12 of the middle injection pipe 1, in each adjacent two filter layers, the filter pore size of the filter layer close to the liquid outlet 12 is smaller than that of the filter layer close to the liquid inlet 11. Figure 2 ​​​As shown, specifically, the filter layer of the embodiment includes two, the filter layer includes the first filter layer 13 and the second filter layer 14 which are spaced from top to bottom, the adjacent first filter layer 13 and the second filter layer 14 are spaced a certain distance, the first filter layer 13 and the second filter layer 14 form the molten steel buffer area A in the cavity of the tundish 1, since the porosity of the first filter layer 13 is greater than the porosity of the second filter layer 14, for example, the porosity of the first filter layer 13 can be 20-50 ppi, specifically, it can be any one of 20 ppi, 22 ppi, 24 ppi, 26 ppi, 28 ppi, 30 ppi, 32 ppi, 34 ppi, 36 ppi, 38 ppi, 40 ppi, 42 ppi, 44 ppi, 46 ppi, 48 ppi and 50 ppi, and it can also be any porosity between the above two adjacent porosities. The porosity of the second filter layer 14 can be 15-20 ppi, specifically, it can be any one of 15 ppi, 16 ppi, 17 ppi, 18 ppi, 19 ppi and 20 ppi, and it can also be any porosity between the above two adjacent porosities. Through the design of such porosity, not only the molten steel buffer area A can be formed, but also the function of filtering the steel slag and impurities in the molten steel can be achieved. The flow rate of the molten steel through the first filter layer 13 from top to bottom is greater than the flow rate through the second filter layer 14, which makes the molten steel accumulate in the molten steel buffer area A, forming a molten steel pool.

[0035] A plurality of filter layers are arranged in the tundish 1, that is, a plurality of molten steel buffer areas A can be formed, which can filter the steel slag and inclusions. The large flow of molten steel flowing out of the tundish 8 becomes a small flow after being buffered by the first filter layer 13 and the second filter layer 14, which can reduce the impact of the molten steel on the nozzle pack 5, thereby reducing the instability of the strip production process and thickness caused by the fluctuation of the liquid level.

[0036] The filter layer of the embodiment is selected from a foamed ceramic filter screen, preferably a zirconia foamed ceramic filter screen.

[0037] As shown in Figure 3 , 4 The heating device 2 is a hollow cylindrical opening and closing structure, and the heating device 2 is a layer structure including a heat supplement layer 21, a heat preservation layer 22, an induction coil 23 and a protection layer 24 arranged in order from inside to outside.

[0038] The heat supplement layer 21 is tightly attached to the outer wall of the tundish 1 and is used for heat supplement. The heat supplement layer 21 can be selected from a graphite heat supplement layer, which can supplement the heat of the molten steel pool and the molten steel flowing through the tundish 1 by radiation, thereby improving the stability of the induction heating of the coil.

[0039] The heat preservation layer 22 can effectively prevent the heat loss of the heat source centered on the tundish 1 and the molten steel; the induction coil 23 can heat and provide heat energy for the heat supplement layer 21; and the protection layer 24 is located at the outermost layer of the heating device 2 and can protect the heating device 2.

[0040] It should be noted that, in the present application, the heat preservation layer 22 can be any material capable of preventing heat loss. For example, it can be an aluminum silicate fiber blanket. The heat preservation layer 22 can improve the safety of the furnace body while insulating and preserving heat. The protection layer 22 is mainly used for physical protection, and therefore it can be any structure of any material. For example, it can be a ceramic tube or an asbestos cloth. The electromagnetic induction coil 23 is in a spiral shape. Preferably, the spiral axis of the electromagnetic induction coil 23 coincides with the axis of the heat supplement layer 21.

[0041] Similar to the specific material, whether the ceramic filter pore size needs to be disclosed in this patent

[0042] The heating device 2 can be a tubular open and closed induction heating device, which can adjust the temperature of the molten steel flowing in the tundish 1 and the molten steel pool.

[0043] The heating device 2 of the embodiment is controlled by a temperature control unit, which includes an induction coil adjustment module, a temperature measuring element, and a PLC controller. The temperature measuring element is arranged at a temperature measuring port of the heating device and is used to collect the temperature of the molten steel at the corresponding position in the tundish 1. The temperature measuring element can be an infrared temperature sensor. The induction coil adjustment module is electrically connected with the induction coil. The PLC controller is electrically connected with the induction coil adjustment module and the temperature measuring element. The PLC controller controls the induction coil to adjust the temperature through the induction coil adjustment module according to the temperature information collected by the temperature measuring element, so as to automatically adjust the temperature of the heating device 2, maintain the stability of the molten steel temperature, and stabilize the molten steel at 1300-1400±3℃ according to the process requirements of the nanocrystalline strip of different components, such as 1300℃, 1330℃, 1350℃, and 1400℃, or any value between the adjacent values.

[0044] Since the flow rate of the molten steel in the tundish 1 above the molten steel buffer area A is fast, the molten steel in the tundish 1 below the molten steel buffer area A is in the form of droplets. Therefore, the heating device 2 is wrapped around the molten steel buffer area A in the tundish 1, so as to supplement the heat of the molten steel in the molten steel buffer area A.

[0045] The induction heating method can heat the graphite heat supplement layer to 1000 degrees in 30 seconds. The graphite heat supplement layer and the electromagnetic induction heating are used to heat the molten steel in the tundish 1, so as to improve the heating efficiency and stability. When there is no molten steel in the tundish 1, the graphite heat supplement layer can still radiate heat to keep the tundish 1 at a high temperature.

[0046] In an embodiment, the heating device 2 can further comprise a heat insulation layer arranged between the heat preservation layer 22 and the induction coil 23, which can improve the safety of the heating device 2 while insulating heat. The present application combines the heat insulation layer and the heat preservation layer, which is beneficial to reduce the heat loss of the heating device 2 and improve the heat insulation effect and thermal efficiency of the pouring protection system.

[0047] In the present embodiment, the intermediate ladle pouring module can be used in the process of casting nanocrystalline flat flow strip by bottom pouring of the intermediate ladle, and of course, the present application is not limited thereto, but can also be used in other types of bottom pouring processes of the intermediate ladle in the field of steelmaking.

[0048] Embodiment 2

[0049] The present application provides a pouring protection system for bottom pouring of an intermediate ladle.

[0050] The intermediate pouring module in embodiment 1 and the nozzle package 5 are connected below the intermediate pouring module, that is, the lower end of the intermediate pouring pipe 1 communicates with the nozzle package 5, and the molten steel in the intermediate ladle 8 can be transported to the nozzle package 5 through the intermediate pouring pipe 1, and the control of the gap between the stopper rod 9 and the nozzle runner can control the flow of the molten steel; the nozzle package 5 is used to collect the molten steel flowing out of the intermediate pouring pipe 1.

[0051] As shown in Figure 4 Since the intermediate pouring pipe 1 transports molten steel for a long time, it is also a consumable, and its two ends are generally connected to the intermediate ladle 1 and the nozzle package 5 through a detachable structure, respectively. The shape and structure of the intermediate ladle 8, the intermediate pouring pipe 1 and the nozzle package 5 are not limited, and they can be any structure. In the present embodiment, the intermediate ladle 8 is a columnar shell with an upper opening, the upper end of the intermediate pouring pipe 1 is provided with a dismounting device 3 for realizing quick dismounting and mounting with the intermediate ladle 8, and the dismounting device 3 can adopt a buckle type vacuum flange device. The upper end of the nozzle package 5 is fixedly connected to a supporting device 7, the supporting device 7 adopts a circular ring structure, the intermediate pouring pipe 1 passes through the supporting device 7, the upper end of the supporting device 7 is connected to a quick locking device 6, the quick locking device 6 is connected to the lower part of the intermediate pouring pipe 1, and the quick locking device 6 can adopt a buckle type quick locking device; the quick locking device 6 can realize quick fixing of the lower end of the intermediate pouring pipe 1, so as to ensure that the intermediate pouring pipe 1 is more stable and is not easy to displace with the nozzle package 5.

[0052] The upper end of the dismounting device 3 is provided with an elastic compensation device 4, which can adopt a corrugated structure elastic compensation device; one end of the elastic compensation device 4 is connected to the dismounting device 3, and the other end of the elastic compensation device 4 is connected to the lower end of the intermediate ladle 8; the elastic compensation device 4 can flexibly adjust the intermediate pouring pipe 1, so that the axis of the intermediate pouring pipe 1 in the vertical state is coaxial with the lower nozzle runner of the intermediate ladle 8, and the molten steel flows along the axis of the intermediate pouring pipe 1 when the intermediate ladle 8 is pouring.

[0053] The nozzle package 5 is used to receive liquid steel from the tundish 8, and when the connection between the nozzle pipe 1 and the tundish 8 or the nozzle package 5 leaks, the liquid steel is easily oxidized. In the embodiment, the upper end of the nozzle package 5 is provided with a nozzle package air inlet 51 which is in communication with the inner cavity of the nozzle package 5, and the nozzle pipe 1 is provided with a protective gas outlet 16 above the nozzle pipe 1, and the protective gas outlet 16 is provided with a pressure control valve; the lower end of the nozzle pipe 1 is in communication with the protective gas inlet 15.

[0054] The nozzle pipe 1 is provided with the protective gas inlet 15 and the protective gas outlet 16, and along the direction of the nozzle pipe 1 from the liquid inlet 11 to the liquid outlet 12, the protective gas inlet 15 is located on the side of the liquid storage area A away from the liquid inlet 11, and the protective gas outlet 16 is located on the side of the liquid storage area A towards the liquid inlet 11.

[0055] The protective gas inlet 15 is used to input protective gas into the nozzle pipe 1, and the protective gas outlet 16 is used to output protective gas, so as to further ensure that the liquid steel in the nozzle pipe 1 is not easily oxidized. The protective gas can be an inert gas with a density greater than air, such as argon or nitrogen.

[0056] The system fills the protective gas from the nozzle package air inlet 51, and the protective gas fills the nozzle package 5 and the nozzle pipe 1, keeps the nozzle package air inlet 51 in a positive pressure state at all times, so that the external air cannot enter the nozzle package 5 and the nozzle pipe 1, and the protective gas can protect the liquid steel in the nozzle pipe 1, avoiding the technical problems of the prior art that the existing technology cannot solve the problem of the large increase in the oxygen content of the liquid steel caused by the loose sealing of argon, and the large amount of oxide inclusions in the liquid steel, which causes the strip casting process to be interrupted and the performance of the strip to be reduced, and the technical problem that the existing technology cannot solve the problem of the large heat loss of the liquid steel in the nozzle pipe and the difficulty of heating the high-speed moving liquid steel.

[0057] The inner cavity of the nozzle pipe 1 of the embodiment is provided with two zirconia foam ceramic filter screens, and the pore size of the lower foam ceramic filter screen is smaller than that of the upper foam ceramic filter screen. The liquid steel is dynamic, and during the pouring process, the liquid steel flows out from the bottom of the tundish 8, flows through the nozzle pipe 1 and then enters the nozzle package 5.

[0058] When the liquid steel passes through the nozzle pipe 1, the liquid steel is buffered at each layer of foam ceramic filter screen, and since the pore size of the upper foam ceramic filter screen is larger than that of the lower foam ceramic filter screen, the flow rate of the liquid steel through the lower foam ceramic filter screen is smaller than that through the upper foam ceramic filter screen, and the liquid steel will accumulate between the adjacent two layers of foam ceramic filter screens, forming a dynamic and stable liquid steel, that is, a liquid steel storage pool.

[0059] Embodiment 3

[0060] The present application provides a tundish bottom injection protective pouring method based on any one of the tundish bottom injection protective pouring systems, and the method comprises the following steps:

[0061] (1) Gas washing: before pouring, the protection gas is filled from the nozzle package inlet 51, the protection gas is inert gas with density greater than air, the inert gas can use argon, until the protection gas fills the nozzle package and the middle injection pipe.

[0062] (2) Positive pressure protection: after pouring, open the protection gas inlet 15 and pass the protection gas, the protection gas is inert gas with density greater than air, the steel liquid buffer zone forms a dynamic stable steel storage pool, the positive pressure in the middle injection pipe 1 is adjusted by the pressure control valve at the protection gas outlet 16, and the pressure range of the protection gas is controlled in 1-5Pa.

[0063] (3) Temperature compensation: the PLC controller acquires the temperature information of the middle injection pipe 1 through the temperature measuring part, and controls the electromagnetic coil temperature through the induction coil adjustment module, so as to realize the temperature compensation of the steel liquid.

[0064] Before pouring, the protection gas is filled from the nozzle package inlet 51, the protection gas can be inert gas with density greater than air, for example, argon or nitrogen, etc., by slowly filling the protection gas, the air in the nozzle package 5 and the middle injection pipe 1 can be replaced, and the gas flow moves from bottom to top, which can ensure that the inert gas fills the nozzle package 5 and the middle injection pipe 1 completely. After pouring, the protection gas inlet 15 is opened to pass the protection gas, for example, argon or nitrogen, etc., a dynamic stable steel storage pool is formed in the middle injection pipe 1 cavity between the two adjacent zirconia foam ceramic filter screens, so that the whole system is in the protection of the positive pressure protection gas, and the system pressure can be adjusted by the pressure control valve arranged on the protection gas outlet 16, and the pressure range of the protection gas is controlled in 1-5Pa.

[0065] The temperature control unit of the application can heat the steel liquid in the middle injection pipe 1 steel liquid buffer zone A, and compensate the heat loss of the steel liquid in the pouring process; at the same time, the argon gas flow from bottom to top can wash the steel liquid in the steel storage pool, which is beneficial to the separation of steel slag in the steel liquid and the filtration of the foam filter ceramic, so as to realize the effect of purifying the steel liquid.

[0066] The large flow of the middle tundish 8 is changed into small liquid flow after passing through multiple filter layers and buffering and shunting, and the impact of the liquid surface on the nozzle package 5 is reduced, so as to reduce the instability of the strip production process and thickness caused by the liquid surface fluctuation.

[0067] The positive pressure argon protection of the application can make the inclusions in the steel liquid float and be filtered through the filter layer to achieve the purpose of purifying the steel liquid; at the same time, the induction coil heating and the graphite heat compensation layer can quickly adjust the temperature of the steel liquid, so that the temperature fluctuation of the middle tundish 8 steel liquid is within 3° in the whole bottom pouring process, and the required temperature control precision for continuously preparing wide ultra-thin nanocrystalline strip is achieved.

[0068] The present application can solve the technical problems of the prior art, i.e. the argon sealing is not strict, the oxygen content of the liquid steel is greatly increased, a large amount of oxide inclusions is precipitated from the liquid steel, the strip production is interrupted, and the strip performance is reduced, and the technical problems of the prior art, i.e. the heat loss of the liquid steel is large, and it is difficult to supplement heat for the high-speed moving liquid steel.

[0069] The embodiments of the present embodiment are the preferred embodiments of the present application, but do not limit the protection scope of the present application, so that: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A tundish bottom-pouring protection casting system, characterized in that, It includes an intermediate injection module for tundishes, with a nozzle pack connected below the intermediate injection module, the nozzle pack being used to collect molten steel flowing out from the intermediate injection pipe; The intermediate tundish injection module includes an injection tube and a heating device. The heating device covers the outside of the intermediate column tube. The injection tube is located below the intermediate tundish and has an inlet and an outlet. Along the direction from the inlet to the outlet, multiple filter layers are distributed at intervals in the inner cavity of the injection tube. A molten steel buffer zone is formed in the inner cavity of the injection tube between every two adjacent filter layers. Along the direction from the inlet to the outlet, in every two adjacent filter layers, the filter pore size of the filter layer closer to the outlet is smaller than that of the filter layer closer to the inlet. The large flow of molten steel from the tundish is buffered by multiple filter layers and then becomes a small droplet. The central injection pipe is provided with a protective gas inlet and a protective gas outlet, and the direction from the liquid inlet to the liquid outlet is along the central injection pipe. The protective gas inlet is located on the side of the molten steel buffer zone away from the liquid inlet, and the protective gas outlet is located on the side of the molten steel buffer zone facing the liquid inlet. The protective gas inlet is used to input protective gas into the interior of the central injection pipe, and the protective gas outlet is used to output protective gas. The upper end of the nozzle pack is provided with a nozzle pack air inlet communicating with the inner cavity of the nozzle pack, and a pressure control valve is provided at the protective gas outlet; a support device is fixedly connected to the upper end of the nozzle pack, and a quick-lock device is provided at the upper end of the support device, which is connected to the lower part of the injection tube.

2. The tundish bottom-pouring protection casting system according to claim 1, characterized in that, Each of the filter layers is a zirconia foam ceramic filter screen.

3. The tundish bottom-pouring protection gating system according to claim 1, characterized in that, The heating device has a ring-shaped layer structure, which includes a heat-replenishing layer, an insulation layer, an induction coil, and a protective layer arranged sequentially from the inside out.

4. The tundish bottom-pouring protection casting system according to claim 3, characterized in that, It also includes a temperature control unit, which comprises an induction coil adjustment module, a temperature measuring element, and a PLC controller; the temperature measuring element is installed at the temperature measuring port of the heating device and is used to collect the temperature of the molten steel at the corresponding position in the injection tube; the induction coil adjustment module is electrically connected to the induction coil; the PLC controller is electrically connected to the induction coil adjustment module and the temperature measuring element respectively.

5. The tundish bottom-pouring protection casting system according to claim 1, characterized in that, The upper end of the injection tube is equipped with a disassembly device for quick assembly and disassembly with the intermediate package.

6. The tundish bottom-pouring protection casting system according to claim 5, characterized in that, An elastic compensation device is provided above the disassembly device. One end of the elastic compensation device is connected to the disassembly device, and the other end is connected to the lower end of the tundish. The elastic compensation device can flexibly adjust the injection pipe. When the injection pipe is vertical, its axis is coaxial with the tundish's lower water inlet channel. When the tundish is being poured, the molten steel flows down along the axis of the injection pipe.

7. A method for tundish bottom-pouring protection, based on the tundish bottom-pouring protection system as described in claim 4, characterized in that, The method includes the following steps: (1) Gas washing: Before pouring, protective gas is introduced from the air inlet of the nozzle package. The protective gas is an inert gas with a density greater than that of air, until the protective gas fills the nozzle package and the middle injection pipe. (2) Positive pressure protection: After the casting starts, the protective gas inlet is opened and protective gas is introduced. The protective gas is an inert gas with a density greater than that of air. The steel liquid buffer zone forms a dynamically stable steel storage pool. The positive pressure in the middle injection pipe is adjusted by the pressure control valve at the protective gas outlet. (3) Temperature compensation: The PLC controller collects the temperature information of the injection tube by the temperature measuring device, and controls the temperature of the electromagnetic coil through the induction coil adjustment module to realize the temperature compensation of the molten steel.

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