Method for inhibiting eddy slag entrapment and air suction of converter tapping molten steel
By spraying water above the tapping port during the converter tapping process, the problems of slag entrapment in molten steel and the intake of high-nitrogen gas were solved, achieving the effects of reducing phosphorus return and increasing nitrogen, simplifying equipment and reducing costs.
Patent Information
- Application Number
- CN202511211137.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2025-11-21
AI Technical Summary
During the tapping process of a converter, the swirling of molten steel entrains slag and draws in high-nitrogen gases, leading to phosphorus reversion and nitrogen increase in the molten steel, which are difficult to effectively solve with existing technologies.
During the tapping process, water is sprayed above the tapping hole. The rapid evaporation of water generates explosive kinetic energy, which drives away slag, interferes with and disrupts the vortex, dilutes the furnace gas, and reduces the degree of rotational dispersion of the molten steel vortex and the amount of gas absorbed.
It effectively reduces the amount of slag entering the ladle, reduces phosphorus and nitrogen reversion in molten steel, simplifies equipment construction, reduces costs, and improves the stability and quality of the tapping process.
Smart Images
Figure CN120989333A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metallurgical technology, and more specifically, to a method for suppressing slag entrainment and phosphorus return in the molten steel during the converter tapping process and for increasing nitrogen absorption through gas. Background Technology
[0002] Phosphorus, as a harmful element in steel, impairs its plasticity, toughness, and weldability. Effectively removing phosphorus from iron-containing raw materials is the most important task in steelmaking. Dephosphorization in steelmaking involves oxidizing phosphorus in molten iron and enriching it in the slag under a strong oxidizing atmosphere. Any phosphorus-containing slag that enters the ladle with the molten steel will be re-dissolved into the molten steel during deoxidation and slag reduction, a process known as "phosphorus reabsorption," which significantly undermines the initial efforts in steelmaking. During the converter tapping process, there are three main possible stages for slag to enter the ladle from the taphole: 1) the floating slag (front slag) flowing out before the molten steel flows out of the taphole when the furnace body is tilted; 2) the floating slag (process slag) drawn in by the vortex of molten steel above the taphole during the middle and later stages of tapping; and 3) the slag flowing out after the molten steel has completely flowed out at the end of tapping (rear slag). Existing technologies, such as slag caps and plugs for blocking front slag and slag bolts (bars), sliding plate closures, or gas backflushing for blocking rear slag, as well as combinations thereof, can effectively control the flow of slag. While the aforementioned issues of slag entering the ladle in stages 1 and 3 have been addressed, there is still no good solution for process slag in the intermediate stages. This is especially true after the increase in the critical height of molten steel for vortices caused by the use of ultra-large / large-diameter tapping ports in large-scale converters and rapid and efficient tapping. As a result, the vortex starts relatively earlier (often with obvious slag entrainment in the middle of tapping), the vortex intensity increases, and the amount of slag entrained increases. Before the end of tapping, a large amount of slag is already entrained by the molten steel vortex and enters the ladle.Regarding the problem of slag entrainment in eddies, many previous efforts and attempts have yielded some results, but due to various issues, they have not been widely adopted. For example, 1) adding mechanical slag devices (slag-blocking rods / bolts, etc.) to increase the diameter of the slag-blocking refractory cone in advance to enhance its ability to fill and cover the eddy area and reduce slag entrainment, but the early addition intensifies the erosion of the refractory cone and causes severe melting of the front guide rod, resulting in poor positioning accuracy and fullness of the final taphole filling. A large amount of slag will still be entrained with the molten steel from multiple larger small eddy areas around the refractory cone; 2) The United States invented a method of using nitrogen / air to blow air from the furnace mouth to the taphole to disperse the slag above, thereby reducing the slag inflow into the taphole during and after the tapping process. Chinese patent application number 2014101089686 "Method and equipment for direct injection of high-pressure gas into steel slag for slag blocking and tapping in converter" "A similar method of using high-pressure airflow to disperse the slag above the tapping spout has also been disclosed, but due to (1) the high-speed gas with the ability to disperse slag will expand rapidly and lose energy after flowing out of the nozzle, the spray gun cannot produce good results when it is far away, and it will affect the rotation of the furnace when it is close, (2) the noise generated by the high-pressure gas blowing does not meet the requirements of on-site industrial hygiene, (3) the injection of nitrogen / air will result in more nitrogen addition to the tapping of low-nitrogen steel with strict nitrogen requirements, (4) the equipment is large in size and must be close to the furnace mouth, and the spray gun must also be deep into the furnace mouth, which seriously affects the tapping operation after the furnace; 3) Chinese patent application No. 2006100695701 "Oxygen top blown converter gas curtain slag blocking tapping spout" discloses a method of reducing the slag flowing out with the molten steel by blowing air in the tapping spout, but it has not been applied because it seriously affects the life of the tapping spout, reduces and is unstable and too complicated.
[0003] Nitrogen is harmful to most steel grades, and the precipitation of nitrides can negatively affect certain properties of the steel to varying degrees. Pure oxygen steelmaking significantly reduces the nitrogen content of the molten steel at the end of smelting by generating carbon oxide bubbles through a strong carbon-oxygen reaction (most can be controlled below 20 ppm). However, due to the high solubility of nitrogen in molten steel (the quasi-saturated nitrogen content in nitrogen absorption tests of molten steel can reach over 400 ppm), controlling nitrogen addition to the molten steel after smelting is crucial for low-nitrogen steel. The possible nitrogen increase in molten steel during tapping after converter blowing can occur through the following stages: 1) Nitrogen increase from the swirling vortex of molten steel above the tapping inlet in the later stages of tapping, which entrains air-rich furnace gases; 2) Nitrogen increase from air drawn into the environment during the flow of molten steel from the tapping inlet into the ladle; and 3) Nitrogen increase from air drawn into the upper space of the ladle by the molten steel surface after entering the ladle. There are few countermeasures for the first stage of in-furnace nitrogen increase, especially as steelmaking technology and processes continue to advance. Currently, various primary steelmaking furnaces are trending towards top-and-bottom combined blowing, which can significantly reduce the iron oxide content in the slag at the end of blowing and the active oxygen content in the molten steel. In particular, bottom-blown oxygen-combined converters and advanced bottom-blown inert gas-combined converters can control the active oxygen content in the molten steel below 400 ppm. The equilibrium carbon-oxygen product (CO-O) level in an atmospheric environment, which is far below 0.0025 and controlled to be below 0.0014, has greatly improved the technical and economic indicators of the smelting process in the steelmaking furnace and the quality of the molten steel. However, it has also led to the problem of relatively more nitrogen increase in the molten steel during the tapping process. The specific reasons for this in theory and mechanism are as follows: 1) Oxygen in molten steel is a surface-active element. Oxygen adsorbed at the air / molten steel interface occupies some of the interface sites that can also adsorb nitrogen, which hinders the adsorption of nitrogen at these sites and its possible dissolution into the molten steel. Obviously, the higher the oxygen content in the molten steel, the fewer interface sites it occupies, and the more nitrogen occupies in the air. The more nitrogen the molten steel absorbs from the air (and vice versa). Production practice also shows that when the oxygen content is high, the increase in nitrogen in the molten steel is relatively small. 2) The lower the oxygen content of the molten steel, the more oxygen the molten steel absorbs from the ambient air during tapping based on the oxygen balance. The higher the nitrogen content (partial pressure) of the remaining air in the environment, the more nitrogen the molten steel absorbs. 3) The greater the difference between the actual carbon-oxygen product of the molten steel in the furnace and the environmental equilibrium carbon-oxygen product, the less the molten steel can absorb oxygen from the air, produce carbon monoxide through the carbon-oxygen reaction, and react with oxygen in the environment to generate carbon dioxide, thus diluting the ambient air and slowing down the absorption of oxygen and nitrogen. In some cases, when the carbon-oxygen content of the molten steel is extremely low, the molten steel may only absorb oxygen from the air without any carbon-oxygen reaction. Without dilution of the air, there will be no denitrification of the molten steel. Therefore, in advanced bottom-blown inert gas combined blowing converters, the carbon-oxygen product of the molten steel at the end of the blowing process is relatively higher than the carbon-oxygen product of the molten steel in the atmospheric environment, resulting in more negative impacts on the quality of low-nitrogen steel due to the reduced oxygen / carbon-oxygen product of the molten steel during tapping. Summary of the Invention
[0004] 1. The problem to be solved The purpose of this invention is to provide a simple, convenient and effective solution to the problems caused by the swirling of molten steel into slag above the tapping spout during the steelmaking converter tapping process, which leads to subsequent deoxidation of molten steel, phosphorus reversion in molten steel in the ladle during refining, and nitrogen increase in molten steel caused by the swirling of molten steel into high-nitrogen furnace gas or air during the production of low-nitrogen steel.
[0005] 2. Technical Solution The technical solution adopted in this invention is as follows: In the later stage of the tapping process when the molten steel vortex is about to form and slag is to be entrained, water is continuously sprayed from the converter mouth to the slag layer / molten steel surface above the tapping opening. 1) The horizontal component of the explosive kinetic energy generated by the rapid evaporation of water is used to continuously drive away the floating slag on the molten steel surface above the tapping opening, so as to reduce the amount of slag entrained into the ladle by the molten steel from the center of the vortex. 2) The directional component of the explosive kinetic energy generated by the rapid evaporation of water is used to interfere with and destroy the flow field of the molten steel vortex, so as to weaken the ability of the molten steel vortex flowing into the tapping opening to carry slag / draw furnace gas and reduce the degree of rotation and dispersion of the molten steel stream flowing out of the tapping opening. 3) The water vapor generated by the rapid evaporation of water replaces and dilutes the air-rich furnace gas in the space above the tapping opening, so as to reduce the nitrogen content in the furnace gas drawn into the molten steel vortex.
[0006] The technical principles that differentiate the present invention from existing technologies are as follows: 1) The required slag removal energy can be easily obtained by utilizing the thermal energy of molten steel and slag. During or in the later stages of tapping when molten steel is about to form a vortex and slag entrainment, a continuous jet of water is sprayed above the tapping spout to penetrate the slag layer. This utilizes the explosive energy of water rapidly evaporating into steam at high temperatures within the steelmaking furnace, producing approximately 6000 times the volume of water, and the continuous dispersal of slag from the vortex area above the tapping spout by the gas. Only a small amount of water is needed to easily obtain sufficient energy to dislodge the slag above the tapping spout, and the ability to dislodge slag can be easily altered simply by adjusting the flow rate. In contrast, if high-pressure gas were used to obtain the same slag-dispelling energy, the amount required would be significantly higher than that of water due to the expansion and growth of the gas after it leaves the nozzle and enters the furnace.
[0007] 2) As an incompressible liquid, water jets have significant advantages in terms of application and transport characteristics. In applications involving jetting into high-temperature spaces, water is denser, easier to pressurize, and safer to use than gas. Compared to gas jets, water jets have a larger transmission mass, less kinetic energy loss, and less stream expansion and dilation. They can be used for long-distance jetting without interference between on-site equipment, and are also easier to control the jet direction and focus the landing point. The jetting system is significantly simplified in both construction and size.
[0008] 3) Interference and disruption of eddies During tapping from a converter, the molten steel flowing through the taphole is affected by various factors, including the morphology of the taphole inlet area and internal channels, the initial flow state of the molten steel in the furnace, the disturbance caused by the converter's rotation, and even the Coriolis force. As the molten steel level in the furnace decreases, vortices appear and gradually intensify above the taphole, generating a deepening vortex core. This creates negative pressure due to the high-speed flow of the molten steel and / or a height difference at the lowest point of the vortex core, causing slag and / or furnace gas above the taphole to be drawn in / flow into the vortex core and flow into the ladle with the molten steel. Since the vortex's ability to draw in slag and furnace gas is positively correlated with the degree of molten steel rotation, using external force to interfere with and disrupt the swirling flow of the molten steel can reduce the amount of slag flowing into the ladle and furnace gas being drawn into the taphole during the tapping process. When a water jet is used to penetrate the slag layer, the kinetic energy of the rapidly evaporating water vapor strongly interferes with and disrupts the flow state of the surrounding molten steel. Under suitable water flow conditions, it is possible to achieve interference and disruption of the vortex during the tapping process.
[0009] 4) Selection and determination of injection pressure and flow rate When the jet water enters the slag layer, it evaporates rapidly into water vapor. To avoid splashing of molten steel or slag after the water penetrates the slag layer, it is crucial to determine the specific jet penetration force after the water enters the slag layer and the amount of residual water after initial evaporation. This requires a narrow range that effectively disperses the slag, prevents slag re-moistening, and avoids significant splashing of molten steel. Under economical industrial water conditions of 300-500 kPa, and with careful observation, by experimenting with various nozzle types and parameters from low to high pressure and flow rate, it is entirely possible to select and determine the appropriate water jet pressure and flow rate from existing jet nozzle standards. It is recommended to use a single-orifice cross-shaped / elliptical outlet section liquid jet nozzle or a multi-orifice circular outlet section liquid jet nozzle. The specific calculation of the water flow rate of the jet is Q=q+a*((W-100) / 100); where Q is the water flow rate (liters / minute), q is the basic water flow rate of 3~6 liters / minute, which is taken from the comprehensive factors of water pressure, nozzle characteristics, distance from the landing point, and angle between the jet and the slag surface, W is the nominal tonnage of the converter, and a is a coefficient of 1.0~2.0, which is taken from the range of the angle between the jet and the slag surface and nozzle characteristics.
[0010] 5) Replacement and dilution protection of furnace atmosphere during tapping. The tapping process involves a continuous decrease in molten steel and an increase in furnace space. Air flows into the remaining space after the molten steel flows out, filling the space. Near the tapping opening, the high-temperature, low-density furnace gas escapes from the highest point, creating a circulation of air flowing into the lower part of the furnace. The water vapor generated by the jetting water displaces the air entering the furnace opening area above the tapping opening and preferentially fills the entire furnace space after the molten steel flows out. Furthermore, according to the theory of nitrogen enrichment in molten steel, air can also diffuse nitrogen into the molten steel through the slag. The nearly horizontal furnace surface during the tapping process forms a large slag layer. The air-rich furnace gas can diffuse nitrogen into the molten steel, generating a certain amount of nitrogen enrichment. The jetting device of this invention can be used to spray water from the highest point of the furnace opening towards the furnace bottom area at the beginning of tapping. This creates a circulating flow of evaporated water vapor from the outside in and from the inside out, covering and spreading the slag surface, further inhibiting the diffusion of nitrogen from the high-nitrogen furnace gas through the slag layer into the molten steel.
[0011] 6) The reduction in the degree of rotational dispersion of the molten steel stream after tapping. The presence of eddies also gives the molten steel flowing out of the taphole an initial tangential force that rotates around the axis of the stream. Due to its inertia, the molten steel stream disperses centrifugally, generating a large number of droplets and correspondingly increasing the specific surface area of the molten steel. This not only causes additional air intake into the space above the ladle, increasing nitrogen / oxygen levels, but also amplifies heat dissipation during the tapping process. Using water jets to penetrate the slag layer to interfere with and disrupt the eddies above the taphole in the furnace will also reduce the additional air intake and temperature loss after the molten steel flows out of the taphole.
[0012] 7) Safety of the jet water flow Since water has a specific gravity of only about half that of slag and one-sixth that of molten steel, and since water begins to evaporate and expand as it approaches molten steel, the water jets that enter the slag layer and the surface of the molten steel from above will not cause splashing of the molten steel and / or slag under the pressure and appropriate flow rate of economical industrial water.
[0013] Beneficial effects Compared to existing technologies, this invention achieves the following beneficial effects by continuously spraying water from the converter mouth to the slag layer / molten steel surface above the tapping opening during the middle and later stages of steelmaking: 1) The amount of slag carried into the ladle by the vortex of molten steel is greatly reduced, which correspondingly reduces the phosphorus return to the molten steel during subsequent slag deoxidation and reduction. 2) It has a strong destructive effect on the swirling flow field of molten steel, which slows down the rotation speed of the swirling flow, reduces the degree of centrifugal dispersion after the molten steel flows out of the outlet, and reduces the temperature drop and air intake of the falling steel flow. 3) The nitrogen content in the furnace gas atmosphere above the tapping outlet is greatly reduced, which reduces the nitrogen increase in the corresponding part of the furnace gas drawn into the molten steel vortex; 4) It can achieve long-range water jetting, with a small jet stream cross-section, minimal expansion, and focused impact point; 5) The injection water volume can be easily adjusted to a large extent, making it easy to achieve high-energy slag driving, eddy current destruction, and large-volume furnace gas replacement and dilution.
[0014] 6) All equipment can be installed and positioned outside the furnace door, which is far from the converter opening, without interfering with various operations behind the furnace, and can safely and reliably achieve long-distance remote injection.
[0015] 7) Compared with various inert high-pressure gases, the cost of jet water flow to suppress eddy slag entrainment and dilute furnace gas to reduce phosphorus return and nitrogen addition in molten steel is greatly reduced.
[0016] 8) The method of the present invention is easy to implement and the device is simple and lightweight, requiring very little investment and almost no operating and maintenance costs. Attached Figure Description
[0017] Figure 1 A schematic diagram illustrating the operating conditions of a method for suppressing vortex slag entrainment and air intake in molten steel during converter tapping according to the present invention.
[0018] Figure 2 A schematic diagram of a typical outlet section of a water jet nozzle in a method for suppressing vortex slag entrainment and air intake in molten steel during converter tapping according to the present invention. Detailed Implementation
[0019] The present invention provides a method for suppressing slag entrapment and air intake in molten steel during converter tapping, specifically implemented as follows: During or later in the tapping process when molten steel is about to form a vortex and slag entrainment, water is continuously sprayed from the converter mouth onto the slag layer / molten steel surface above the tapping opening (see instruction manual). Figure 1 ), 1) The horizontal component of the explosive kinetic energy generated by the rapid evaporation of water continuously drives away the floating slag on the surface of the molten steel above the tapping spout, so as to reduce the amount of slag that is drawn into the ladle from the center of the vortex by the molten steel. 2) The relevant component of the explosive kinetic energy generated by the rapid evaporation of water interferes with and disrupts the flow field of the molten steel vortex, so as to weaken the ability of the molten steel vortex flowing into the tapping spout to carry slag / draw furnace gas and reduce the degree of rotation and dispersion of the molten steel stream flowing out of the tapping spout. 3) The water vapor generated by the evaporation of water replaces and dilutes the air-rich furnace gas in the space above the tapping spout, so as to reduce the nitrogen content in the furnace gas drawn into the molten steel vortex.
[0020] Among them, the water jet continuously sprayed towards the slag layer / molten steel surface above the tapping hole is a jet of water flowing directly above the tapping hole entrance and penetrating the slag layer, with the center line of the jet making an angle of 20~70° with the slag surface.
[0021] Furthermore, the jet is sprayed using a fixed spray gun with a movable base or a telescopic / rotating / swinging spray gun with a fixed base, in order to track and adjust the movement of the target landing point of the slag / molten steel surface water flow directly above the tapping port due to the rotation of the furnace body during steel tapping and the reduction of molten steel in the furnace.
[0022] Furthermore, the water source for the jet is industrial water with a pressure range of 300-500 kPa; the specific calculation of the jet water flow rate is Q=q+a*((W-100) / 100); where Q is the water flow rate (liters / minute), q is a basic water flow rate of 2~4 liters / minute, which is taken comprehensively based on water pressure, nozzle characteristics, distance from the landing point, and the angle between the jet and the slag surface, W is the nominal tonnage of the converter, and a is a coefficient of 1.0~2.0, which is taken comprehensively based on the angle between the jet and the slag surface and the nozzle characteristics.
[0023] Furthermore, the system device for the jet water flow comprises: 1) a water jet spray gun; 2) a nozzle installed at the front end of the spray gun; 3) a water flow detection and control system; 4) a water jet pipeline and valve assembly; and 5) a logic tracking system or a high-temperature detection instrument for guiding the nozzle to spray water at the inlet of the furnace taphole. Furthermore, the aforementioned nozzle is a single-hole cross-shaped, elliptical / circular cross-section, or multi-hole circular cross-section liquid column flow nozzle (see attached instruction manual). Figure 2 Single-hole liquid jet nozzles are more suitable for long-distance, long-range spraying.
[0024] The specific applications of the present invention will be further described below in conjunction with the embodiments.
[0025] Example 1 Basic requirements: 300-ton top and bottom blowing converter, blowing low-oxygen, low-carbon oxygen molten steel; producing high-grade non-oriented silicon steel, with extremely high nitrogen restriction requirements; slag blocking method at tapping is slag plug blocking; industrial water pressure 500 kPa.
[0026] Implementation plan: Fixed base swing-type spray gun, water jet is sprayed at close range outside the furnace door; spraying starts when 50% of the steel has been tapped; the angle between the center line of the jet and the slag surface is 70°; q=2 liters / min, a=1.5, Q=5 liters / min is selected; three-hole nozzle with circular cross section sprays water, the three holes are arranged horizontally, the diameter of the middle hole is 2.5mm, the diameter of the two side holes is 1.8mm, and the hole spacing is 3.5mm; the target position of the sprayed water jet is tracked logically.
[0027] Effects: Reduces phosphorus return by 50% and nitrogen increase by 30% in molten steel.
[0028] Example 2 Basic requirements: 300-ton top and bottom blowing converter, blowing low-oxygen, low-carbon oxygen molten steel; producing ultra-low phosphorus steel, with high nitrogen restriction requirements; slag blocking method is sliding plate slag blocking at the tapping port; industrial water pressure 300 kPa.
[0029] Implementation plan: Telescopic and swing-type spray gun with fixed base for long-distance long-range spraying; spraying starts when 60% of the steel is tapped; the angle between the center line of the jet and the slag surface is 20°; select q=4 liters / minute, a=2, calculate Q=8 liters / minute; spraying with a single-hole nozzle with an elliptical cross section, the ratio of the major and minor axes of the ellipse is 2.0, and the equivalent diameter of the nozzle hole is 3.0mm; target position tracking logic for the sprayed water flow.
[0030] Effects: Reduces phosphorus return by 75% and nitrogen increase by 50% in molten steel.
[0031] Example 3 Basic conditions: 120-ton top and bottom blowing converter, blowing low-oxygen, low-carbon oxygen molten steel; producing ultra-low phosphorus steel, with high nitrogen restriction requirements; slag blocking method is sliding plate slag blocking at the tapping port; industrial water pressure 500 kPa.
[0032] Implementation plan: Telescopic and swing-type spray gun with fixed base, spraying at a relatively close distance outside the furnace door; spraying begins when 70% of the steel has been tapped; the angle between the center line of the jet and the slag surface is 35°; select q=3.0 liters / minute, a=2, calculate Q=3.4 liters / minute; spray with a single-hole cross-shaped circular groove nozzle, with the long groove horizontal and the short groove vertical, the length ratio of the long groove to the short groove is 2:1, and the groove width is 1.5mm; the equivalent diameter of the nozzle hole is 2.2mm; the target position of the sprayed water flow is logically tracked.
[0033] Results: Reduces phosphorus return by 75% and nitrogen increase by 40% in molten steel.
[0034] Example 4 Basic requirements: 210-ton top and bottom blowing converter, for blowing low-oxygen, low-carbon oxygen molten steel; fixed-base oscillating spray gun; production of low-phosphorus steel with high nitrogen restriction requirements; slag blocking method is pneumatic slag blocking with back-blowing air at the tap outlet; industrial water pressure 500 kPa.
[0035] Implementation plan: A rotating, swinging spray gun with a fixed base for long-distance spraying; spraying begins when 60% of the steel has been tapped; the angle between the jet centerline and the slag surface is 60°; q=4 liters / minute, a=2, and Q=6.2 liters / minute are selected; a single-hole circular groove nozzle is used for spraying, with a groove width of 2.0 mm; the equivalent diameter of the nozzle is 2.8 mm; an image sensor is used to physically track the target position of the sprayed water flow.
[0036] Results: Reduces phosphorus return by 75% and nitrogen increase by 40% in molten steel.
[0037] This specification describes the present invention in detail with reference to specific exemplary embodiments. However, it should be understood that various modifications and variations can be made without departing from the scope of the invention as defined by the appended claims. The detailed description and accompanying drawings are only for illustrative purposes and are not intended to limit the implementation of the invention. Therefore, they do not have substantial technical significance. Any related modifications and adjustments, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed in the invention. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention. In addition, the background section is intended to illustrate the current state of research and development and significance of this technology, and is not intended to limit the scope of this invention or this application and its application area. More specifically, although exemplary embodiments of the invention have been described herein, the invention is not limited to these embodiments, but includes any and all embodiments modified, omitted, such as combinations, adaptive changes, and / or substitutions between various embodiments, as would be apparent to those skilled in the art from the foregoing detailed description. The limitations in the claims are to be interpreted broadly as used in the language of the claims and are not limited to the examples described in the foregoing detailed description or during the implementation of this application, which should be considered non-exclusive. Any step listed in any method or process claim may be performed in any order and is not limited to the order presented in the claims. Therefore, the scope of the invention should be determined solely by the appended claims and their legal equivalents, and not by the description and examples given above. It should be understood that the term “and / or” as used herein is a description of an association between related objects, defined as indicating that three relationships can exist, for example, a and / or b, which can represent: a alone, a and b simultaneously, and b alone; the character “ / ” in this document is defined as representing an “or” relationship between preceding and following related objects.
Claims
1. A method for suppressing slag entrainment and air intake in molten steel during converter tapping, characterized in that: In the later stages of the tapping process, when the molten steel vortex is about to form and slag is entrained, water is continuously sprayed from the converter mouth onto the slag layer / molten steel surface above the tapping opening. 1) The horizontal component of the explosive kinetic energy generated by the rapid evaporation of water is used to continuously drive away the floating slag on the molten steel surface above the tapping opening, so as to reduce the amount of slag entrained into the ladle from the center of the vortex. 2) The directional component of the explosive kinetic energy generated by the rapid evaporation of water is used to interfere with and disrupt the flow field of the molten steel vortex, so as to weaken the ability of the molten steel vortex flowing into the tapping opening to carry slag / draw furnace gas and reduce the degree of rotation and dispersion of the molten steel stream flowing out of the tapping opening. 3) The water vapor generated by the evaporation of water replaces and dilutes the air-rich furnace gas in the space above the tapping opening, so as to reduce the nitrogen content in the furnace gas drawn into the molten steel vortex.
2. The method for suppressing slag entrainment and air intake in molten steel during converter tapping according to claim 1, characterized in that: The continuous water jet directed towards the slag layer / molten steel surface above the taphole is a jet of water flowing directly above the taphole inlet, penetrating the slag layer. The angle between the centerline of the jet and the slag surface is 20~70°.
3. The method for suppressing slag entrainment and air intake in molten steel during converter tapping according to claim 2, characterized in that: The jet is sprayed using a fixed spray gun on a movable base or a retractable / rotating / swinging spray gun on a fixed base, in order to track and adjust the movement of the target landing point of the slag layer / molten steel surface water flow directly above the tapping port due to the rotation of the furnace body during steel tapping and the reduction of molten steel in the furnace.
4. The method for suppressing slag entrainment and air intake in molten steel during converter tapping according to claim 1, characterized in that: The system for the jetting water flow consists of: 1) a water jet spray gun; 2) a nozzle installed at the front end of the spray gun; 3) a water flow detection and control system; and 4) a water jet delivery pipeline and valve assembly. 5) A high-temperature detection instrument with a logic tracking system or physical tracking system to guide the nozzle to spray water at the inlet of the furnace taphole.
5. The method for suppressing slag entrainment and air intake in molten steel during converter tapping according to claim 4, characterized in that: The nozzle is a liquid jet nozzle with a single-hole cross-shaped groove, an elliptical / circular groove-shaped cross section, or a multi-hole circular cross section.