Online treatment device for directly heating and melting continuous casting covering slag

Abstract

The utility model belongs to the technical field of casting powder liquefaction pouring in a continuous casting steelmaking link, and relates to an on-line treatment device for directly heating and melting continuous casting powder, which comprises a high-temperature melting chamber, a plasma spray gun, a casting powder bin, a replaceable flame blocking base plate and a fan. The high-temperature melting chamber is a hollow cavity, and a gradually-expanding pouring outlet is formed in the bottom of the high-temperature melting chamber. And the plasma spray gun is horizontally mounted on one side wall. The casting powder bin is arranged at the top, and a flow adjusting valve is arranged at the bottom. The replaceable flame blocking base plate is vertically inserted through the top wide seam, the plate face is perpendicular to the jet flow direction, and the lower portion is a U-shaped flow guide face. The fan is connected to the upper right portion of the pouring outlet so as to maintain micro-negative pressure. The plasma jet flow is adopted to directly impact and heat solid slag powder, U-shaped baffle flow guide, micro-negative pressure drainage and divergent outlet flow stabilization are matched, rapid and uniform melting and accurate and stable pouring of casting powder are achieved, equipment is compact, control is sensitive, and the device is particularly suitable for high-quality steel continuous casting production.

Description

Technical Field

[0001] This utility model relates to the field of liquefaction and casting technology of protective slag in continuous casting steelmaking, and in particular to an online treatment device for directly heating and melting continuous casting protective slag. Background Technology

[0002] In continuous casting, the protective slag plays multiple crucial roles within the crystallizer, including heat insulation, preventing oxidation of molten steel, lubricating the billet, and regulating heat transfer. Traditional processes typically involve directly sprinkling solid powdered or granular protective slag onto the surface of the molten steel in the crystallizer, relying on the heat of the molten steel to melt it into slag. This method suffers from problems such as uneven melting, unstable slag film formation, and easy entrapment of molten steel, leading to defects. This problem is particularly pronounced for high-alumina steels and other steels with stringent requirements for the physical and chemical properties of the protective slag, severely hindering the production of high-quality billets.

[0003] To improve the above situation, existing technologies have attempted to pre-melt the protective slag. For example, the technical solution with patent publication number CN101479061A proposes a continuous casting machine and continuous casting method using molten protective slag. This technology mainly involves designing a new type of continuous casting machine to heat the continuous casting protective slag to a completely molten state outside the crystallizer via indirect heating, and then adding it into the crystallizer through an injection tube. The aim is to reduce friction between the crystallizer and the solidified billet shell and improve product quality.

[0004] However, the above-mentioned devices and methods still have obvious shortcomings: First, they use indirect heating outside the crystallizer, which requires a long heating time to melt the protective slag and form a molten pool, resulting in complicated pre-production preparations and low heating efficiency; Second, the continuous casting machine is large and occupies production space, which is not conducive to its integration into existing compact continuous casting production lines. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the purpose of this utility model is to provide an online treatment device for directly heating and melting continuous casting protective slag. The specific technical solution is as follows:

[0006] An online treatment device for directly heating and melting continuous casting protective slag includes a plasma spray gun, a protective slag silo, a replaceable flame baffle plate, a blower, and a high-temperature melting chamber;

[0007] The high-temperature melting chamber is a hollow cavity structure. The overall wall consists of a heat-resistant layer, a heat insulation layer, and a steel structure outer layer from the inside to the outside. A gradually expanding pouring outlet is provided at the bottom center of the high-temperature melting chamber or on one side biased towards the pouring direction.

[0008] The plasma spray gun is fixedly installed on one side wall of the high-temperature melting chamber, and its spray direction is horizontally directed towards the interior of the high-temperature melting chamber;

[0009] The protective slag silo is fixedly installed at the top of the high-temperature melting chamber and located in front of and above the flame outlet of the plasma spray gun. A flow regulating valve is provided at the bottom outlet of the protective slag silo. The protective slag silo is used to store dry solid protective powder or granules.

[0010] A wide slit is provided on the top wall or side wall of the high-temperature melting chamber. The replaceable flame-blocking substrate is inserted into the high-temperature melting chamber through the wide slit and fixed. The surface of the replaceable flame-blocking substrate is arranged perpendicular to the injection direction of the plasma jet. The lower part of the replaceable flame-blocking substrate facing the interior of the high-temperature melting chamber is constructed as a downwardly recessed U-shaped groove or arc surface structure.

[0011] The blower is connected to the upper right of the casting outlet of the high-temperature melting chamber to actively extract the gas inside the high-temperature melting chamber, so as to maintain a stable micro-negative pressure environment inside the high-temperature melting chamber.

[0012] The preferred embodiment of the online treatment device for directly heating and melting continuous casting protective slag is that the replaceable flame baffle substrate is a multi-layer composite structure, which includes at least a heat-resistant layer, a heat-insulating layer and a strength layer from the side facing the plasma jet to the back side.

[0013] The preferred embodiment of the online treatment device for directly heating and melting continuous casting protective slag is as follows: the plasma spray gun includes a cathode, an anode, an insulator, and a working gas inlet; the insulator is arranged in a ring around the outside of the anode and in contact with the cathode; the cathode and the anode are coaxially arranged and do not contact each other, forming a discharge gap between them; the working gas inlet is used to introduce working gas into the discharge gap between the cathode and the anode.

[0014] The anode has an integrated cooling water channel with a cooling water inlet and a cooling water outlet for circulating cooling water to force cooling of the anode.

[0015] In a preferred embodiment of the online treatment device for directly heating and melting continuous casting protective slag, the working gas of the plasma spray gun and the carrier gas used to transport the protective slag powder are inert gases.

[0016] The preferred embodiment of the online treatment device for directly heating and melting continuous casting protective slag is that the inner diameter of the gradually expanding pouring outlet gradually increases along the slag flow direction.

[0017] The preferred embodiment of the online treatment device for directly heating and melting continuous casting protective slag is to control the melting amount of protective slag in the high-temperature melting chamber and the pouring flow rate of liquid protective slag flowing out of the expansion casting outlet by adjusting the opening degree of the flow regulating valve.

[0018] The online treatment method for continuous casting protective slag in an online treatment device includes the following steps:

[0019] S1. System preparation and parameter preset: Check the cooling water system, air circuit system and electrical circuit system of the device; preset the working parameters of the plasma spray gun according to the process requirements, and set the target powder feeding rate of the solid protective slag through the flow regulating valve;

[0020] S2. Establishing a plasma jet: Activate the plasma spray gun, ignite and stabilize the electric arc, ionize the incoming working gas, and form a stable high-temperature plasma jet in the high-temperature melting chamber;

[0021] S3. Powder conveying and jet heating: Open the flow regulating valve to continuously feed the dry solid protective slag powder from the protective slag silo into the high-temperature melting chamber. The solid protective slag powder falls into the jet path generated by the plasma spray gun and is heated to a molten or semi-molten state.

[0022] S4. Droplet Collision and Molten Pool Formation: Heated molten or semi-molten protective slag droplets, carried by the plasma jet, collide at high speed with the replaceable flame baffle plate and converge towards the center and flow downward along the U-shaped groove or arc surface structure at its lower part, forming a continuous molten protective slag pool at the bottom of the high-temperature melting chamber below the replaceable flame baffle plate; at the same time, the fan is activated to maintain a slight negative pressure environment in the high-temperature melting chamber;

[0023] S5. Liquid slag casting: Under the action of gravity, the liquid protective slag in the molten pool flows out smoothly and continuously from the gradually expanding casting outlet. The addition rate of the solid protective slag is changed by adjusting the flow regulating valve, thereby controlling the casting flow rate of the liquid protective slag.

[0024] Beneficial effects

[0025] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0026] This invention employs an innovative design combining direct heating with side-mounted plasma spray guns and top feeding, along with a replaceable flame-blocking substrate, micro-negative pressure drainage, and a gradually expanding casting structure, forming a highly efficient, reliable, and precisely controlled online processing system. Its beneficial effects are mainly reflected in the following three aspects:

[0027] First, it boasts high heating efficiency and rapid melting speed. This invention utilizes a high-temperature, high-energy-density jet generated by a side-arranged plasma torch to impact-heat the protective slag powder falling directly into the jet path from the top. The powder particles undergo intense direct heat exchange with the plasma, resulting in extremely high heat transfer efficiency and enabling near-instantaneous melting of the protective slag, fundamentally improving thermal energy utilization and the continuity of the melting process.

[0028] Secondly, the equipment has a reliable structure and is easy to maintain. The device has a compact layout and high space utilization. The core heat-receiving component—the replaceable flame baffle plate—adopts a multi-layer composite and insertable design. Its heat-resistant layer facing the jet resists high-temperature erosion, and the lower "U"-shaped structure effectively guides molten slag. Moreover, it can be quickly replaced through the wide slit at the top after wear, which greatly extends the equipment's lifespan, improves maintainability, and ensures long-term operational stability.

[0029] Third, precise process control ensures superior casting quality. The final molten slag output and casting flow can be directly controlled by precisely adjusting the feed rate, resulting in rapid response and excellent matching with the continuous casting speed. Combined with the streamlined design of the bottom-expanding gating nozzle, the liquid flow is effectively stabilized. Furthermore, the slightly negative pressure environment maintained by the blower promptly removes working gases and reaction products, preventing them from interfering with the casting stream or impacting the crystallizer surface. This ensures the uniformity and stability of the molten slag film within the crystallizer, providing a strong guarantee for obtaining high-quality cast billets. Attached Figure Description

[0030] Figure 1 System diagram of the slag liquefaction treatment unit;

[0031] Figure 2 This is a schematic diagram of a replaceable flame-blocking substrate structure;

[0032] Figure 3 To protect the structural diagram of the slag silo;

[0033] Figure 4 This is a schematic diagram of the principle of a plasma spray gun.

[0034] In the diagram: 1-Plasma spray gun, 2-Protective slag bin, 3-Replaceable flame baffle plate, 4-Fan, 5-High temperature melting chamber, 201-Flow regulating valve, 301-Heat resistant layer, 302-Insulation layer, 303-Strength layer; 11-Cathode, 12-Anode, 13-Insulator, 14-Working gas inlet, 15-Cooling water inlet, 16-Cooling water outlet. Detailed Implementation

[0035] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0036] Example 1

[0037] like Figures 1-4As shown in the figure, this embodiment provides an online treatment device for directly heating and melting continuous casting protective slag. The device mainly includes a plasma spray gun 1, a protective slag hopper 2, a replaceable flame baffle plate 3, a blower 4, and a high-temperature melting chamber 5.

[0038] The high-temperature melting chamber 5 is a hollow cylindrical cavity structure with an inner diameter of 300mm. Its wall adopts a three-layer composite structure: the inner layer is a heat-resistant and refractory material layer that directly contacts the high-temperature molten slag; the middle layer is a heat insulation layer composed of ceramic fiber blankets; and the outer layer is a steel structure outer layer that provides structural support. The bottom of the high-temperature melting chamber 5 is made into a tapered structure to connect to the φ80mm casting pipe, and the pipe diameter gradually widens about 200mm before the outlet of the casting pipe.

[0039] The plasma spray gun 1 is fixedly mounted on the left side wall of the high-temperature melting chamber 5 via a flange, and its spray direction is horizontally pointing into the cavity. Figure 4 As shown, the plasma spray gun 1 includes a cathode 11, an anode 12, an insulator 13, and a working gas inlet 14. The insulator 13 is arranged around the outside of the anode 12 and is in contact with the cathode 11. The cathode 11 and the anode 12 are coaxially arranged but do not contact each other, forming a discharge gap between them. The insulator 13 is made of boron nitride ceramic and is used to block the electrical connection between the cathode 11 and the anode 12. The working gas inlet 14 is used to introduce an inert gas such as argon as the working gas. The anode 12 has a spiral cooling water channel machined inside and is provided with a cooling water inlet 15 and a cooling water outlet 16, which are connected to an external circulating cooling water system to force cooling of the anode to prevent ablation. The plasma spray gun 1 is connected to a dedicated DC power supply system and a control unit. The control unit is equipped with a power switch and an emergency shut-off switch.

[0040] The protective slag hopper 2 is a tapered hopper, fixedly welded to the top of the high-temperature melting chamber 5, and located in front of and above the flame outlet of the plasma torch 1. The protective slag hopper 2 stores dry, solid protective slag powder. A flow regulating valve 201 is installed at its bottom outlet to continuously and precisely regulate the rate at which the solid slag powder enters the high-temperature melting chamber 5.

[0041] The replaceable flame deflector plate 3 is the core heat-receiving component. A slit approximately 150mm wide is formed at the top of the high-temperature melting chamber 5 near the rear sidewall. The replaceable flame deflector plate 3 is vertically inserted into the chamber and fixed through this slit, its surface perpendicular to the horizontal jet axis of the plasma spray gun 1. The replaceable flame deflector plate 3 has a three-layer composite structure: a heat-resistant layer 301 facing the jet, a heat-insulating layer 302 in the middle, and a strength layer 303 on the back. Its lower side facing the chamber is machined into a downward-recessed U-shaped groove structure to facilitate the collection and downward flow of molten slag droplets. When the replaceable flame deflector plate 3 is worn down due to high temperature and molten slag erosion, it can be pulled out from the top for replacement.

[0042] The blower 4 is connected via a pipe to the exhaust port on the upper right side of the casting outlet of the high-temperature melting chamber 5. Its core function is to actively extract air within the high-temperature melting chamber 5, maintaining a stable micro-negative pressure environment of approximately -50 Pa. This micro-negative pressure environment guides the plasma jet and the molten droplets it carries towards the replaceable flame baffle plate 3, and can promptly discharge excess working gas, stabilize the fluid flow rate at the casting outlet, and prevent drastic fluctuations in the liquid level of the crystallizer.

[0043] The method for online treatment of continuous casting protective slag using the above-mentioned device includes the following steps:

[0044] S1. System Preparation and Parameter Preset: Check that the cooling water, argon gas path, and electrical system are intact. According to the continuous casting process requirements, preset the rated power of plasma spray gun 1 to 100kW, the working current to 500A, and the argon gas flow rate to 20 L / min, and set the target powder feeding rate of solid protective slag to 0.5 kg / min through the flow regulating valve 201.

[0045] S2. Establishing the plasma jet: Start the power supply to the plasma spray gun 1 to ignite and stabilize the electric arc. The introduced argon gas is ionized in the arc region, thereby forming a high-temperature plasma jet with a temperature of approximately 6000℃ and a stable shape within the high-temperature melting chamber 5.

[0046] S3. Powder Conveying and Jet Heating: Open the flow regulating valve 201, and the dry solid protective slag powder continuously falls into the high-temperature melting chamber 5 at a preset rate. During the falling process, the powder is directly drawn into the core high-temperature zone of the horizontal plasma jet, and through intense convection and radiation heat exchange, it is rapidly heated to a completely molten state within tens of milliseconds.

[0047] S4. Droplet Collision and Molten Pool Formation: Heated molten protective slag droplets, carried by a high-speed plasma jet, impact the vertically arranged replaceable flame deflector plate 3 at a certain angle. The droplets collide and spread on the plate surface, converging towards the center along the U-shaped groove structure at the bottom of the plate before dripping downwards. Simultaneously, the fan 4 continues to operate, maintaining a slight negative pressure inside the chamber. The molten droplets gradually accumulate at the bottom of the chamber below the replaceable flame deflector plate 3, forming a continuous and stable flow of molten protective slag.

[0048] S5. Liquid Slag Pouring: As the melting process continues, the liquid protective slag flows smoothly and continuously from the bottom gradually expanding pouring outlet under the action of gravity. The gradually expanding structure acts as a buffer and stabilizes the flow, and increases the airflow channel, effectively preventing the negative pressure of the blower 4 from sucking away the liquid slag. By adjusting the flow regulating valve 201 in real time, the melting amount in the high-temperature melting chamber 5 can be directly and linearly increased, thereby sensitively and accurately controlling the flow rate of the liquid protective slag finally poured into the continuous casting mold, so as to achieve a good match with the billet pulling speed of the continuous casting machine.

Claims

1. An on-line processing device for direct heating of a molten continuous casting protective slag, characterized in that, It comprises a plasma torch (1), a protective slag bin (2), a replaceable flame barrier base plate (3), a fan (4) and a high-temperature melting chamber (5). The high-temperature melting chamber (5) is a hollow cavity structure, and the overall wall body is sequentially provided with a heat-resistant layer, a heat-insulating layer and a steel structure outer layer from inside to outside. A gradually expanding pouring outlet is arranged at the bottom center of the high-temperature melting chamber (5) or on one side deviated from the pouring direction. The plasma torch (1) is fixedly installed on one side wall of the high-temperature melting chamber (5), and its spraying direction is horizontally directed to the inside of the high-temperature melting chamber (5). The protective slag bin (2) is fixedly arranged on the top of the high-temperature melting chamber (5) and located above the front of the flame outlet direction of the plasma torch (1). A flow regulating valve (201) is arranged at the bottom discharge port of the protective slag bin (2). The protective slag bin (2) is used for storing dry solid protective powder or particles. A wide slot is formed in the upper top wall or the top of the side wall of the high-temperature melting chamber (5). The replaceable flame barrier base plate (3) is inserted into the high-temperature melting chamber (5) through the wide slot and fixed. The plate surface of the replaceable flame barrier base plate (3) is arranged perpendicularly to the spraying direction of the plasma jet. The lower part of the replaceable flame barrier base plate (3) is configured as a downwardly recessed U-shaped groove or an arc surface structure toward one side of the inside of the high-temperature melting chamber (5). The fan (4) is connected to the right upper side of the pouring outlet of the high-temperature melting chamber (5).

2. An apparatus for on-line processing of a direct heating melting continuous casting protective agent according to claim 1, characterized in that, The replaceable flame barrier base plate (3) is a multi-layer composite structure, and at least sequentially comprises a heat-resistant layer (301), a heat-insulating layer (302) and a strength layer (303) from the side facing the plasma jet to the back side.

3. An apparatus for on-line processing of a direct heating melting continuous casting protective agent according to claim 1, characterized in that, The plasma torch (1) comprises a cathode (11), an anode (12), an insulator (13) and a working gas inlet (14). The insulator (13) is annularly arranged outside the anode (12) and in contact with the cathode (11). The cathode (11) and the anode (12) are coaxially arranged and do not contact each other, and a discharge gap is formed therebetween. The working gas inlet (14) is used for introducing working gas into the discharge gap between the cathode (11) and the anode (12). The anode (12) is internally integrated with a cooling water channel, and the cooling water channel is provided with a cooling water inlet (15) and a cooling water outlet (16) for introducing circulating cooling water to forcibly cool the anode (12).

4. An apparatus for on-line processing of a direct heating melting continuous casting protective agent according to claim 1, characterized in that, The channel inner diameter of the gradually expanding pouring outlet gradually increases along the molten slag flow direction.

5. An apparatus for on-line processing of a direct heating melting continuous casting protective agent according to claim 1, characterized in that, The opening degree of the flow regulating valve (201) is adjusted to control the melting amount of the protective slag in the high-temperature melting chamber (5) and the pouring amount of the liquid protective slag flowing out of the gradually expanding pouring outlet.

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