Converter smelting system and method

Abstract

The invention relates to the technical field of ferrous metallurgy, and particularly discloses a converter smelting system and method. The system comprises a converter body, an oxygen lance, a movable converter bottom, a bottom blowing gun, a distributor, a rotary joint and a powder spraying system, the bottom blowing gun is of a circular seam and single hole composite structure, and the powder spraying system supports branch conveying of multiple media such as lime powder and carbon powder. The method comprises seven stages of empty furnace waiting, feeding, efficient dephosphorization, in-furnace heat compensation, blowing, tapping and slag splashing and pouring, and flexible switching of high scrap steel ratio smelting, efficient dephosphorization and less slag, ultra-low carbon-oxygen deposition and a conventional smelting mode is achieved by regulating and controlling the powder type, the gas medium flow and the injection time sequence in a staged mode. Through medium dynamic switching and process integration, the equipment utilization rate and the production adaptability are greatly improved. According to the scheme, an innovative solution is provided for high-efficiency, low-carbon and high-quality development of converter steelmaking.

Description

Technical Field

[0001] The present invention belongs to the field of converter steelmaking and relates to a converter smelting system and method. Background Art

[0002] Converter steelmaking, as the core process of iron and steel metallurgy, uses hot metal and scrap as the main raw materials to achieve metallurgical tasks such as decarburization and dephosphorization through top-blown oxygen and bottom-blown inert gas. However, traditional converter technology has significant limitations, restricting its development in the directions of high-efficiency production and green low-carbon. First of all, limited by the thermal balance in the furnace, the scrap addition ratio of conventional converters usually does not exceed 20%, making it difficult to meet the demand for the efficient utilization of scrap resources under the "dual carbon" policy. Secondly, the dephosphorization process relies on the traditional method of adding lime blocks at the top. Due to the low dissolution rate of lime blocks and limited reaction interface, the actual utilization rate is insufficient, resulting in a large consumption of lime and an increase in slag volume, which not only increases costs but also exacerbates the environmental burden. In addition, traditional bottom-blown systems mostly use small-flow inert gas stirring, with insufficient bath kinetics. The end-point carbon-oxygen product often remains at about 0.0024, and the high oxygen content in the molten steel is prone to cause inclusion aggregation in the subsequent refining process, affecting the quality of steel.

[0003] In response to the above problems, existing technologies have tried to optimize the smelting effect through powder injection processes. For example, some solutions propose top-injecting lime powder to strengthen dephosphorization, but the powder is easily entrained and escaped by the furnace gas, and the actual dephosphorization efficiency has not been significantly improved; other studies use a mixture of bottom-injected carbon powder and coal powder to supplement the furnace temperature by combustion heat release. However, the combustion efficiency is low and the heat loss is large, making a limited contribution to the increase in scrap ratio. In addition, although some staged bottom-injection processes can take into account heat supplementation and dephosphorization, limited by the problems of injection timing and temperature matching, the heat supplementation efficiency in the early stage is insufficient, and the high-temperature environment in the later stage is not conducive to the dephosphorization reaction. Although existing technologies have explored the combined application of bottom-injected oxygen and powder, they generally lack the flexibility of medium switching and cannot dynamically adjust the injection strategy according to the smelting stage, resulting in poor process adaptability and insufficient production stability.

[0004] In summary, existing converter smelting technologies face multiple bottlenecks in core requirements such as high-scrap ratio smelting, efficient dephosphorization, and ultra-low carbon-oxygen product control: the increase in scrap ratio is limited by the heat supplementation efficiency, the dephosphorization process relies on excessive lime, the insufficient stirring intensity of the bath leads to a high end-point oxygen content, and the existing powder injection system is difficult to achieve multi-medium coordination and dynamic regulation. Therefore, there is an urgent need for a system and method that can flexibly switch process modes, strengthen bottom-blown stirring, and precisely control powder injection parameters to break through the technical barriers of traditional converters and promote the evolution of the steelmaking process towards high efficiency, low carbon, and high quality. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a system and method that can flexibly switch process modes, strengthen bottom blowing stirring, and accurately control powder injection parameters, so as to break through the technical barriers of traditional converters and promote the evolution of the steelmaking process towards high efficiency, low carbon, and high quality.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A converter smelting system, comprising:

[0008] The converter body, with an oxygen lance configured at its top and a movable bottom at its bottom;

[0009] At least 2 bottom blowing lances are configured on the movable bottom, and the end of the bottom blowing lance is connected to a distributor through a pipeline;

[0010] The distributor is connected to a rotary joint arranged on the side of the converter body through a pipeline, and the rotary joint is connected to the pipeline of the powder injection system through a pipeline;

[0011] The powder injection system includes a powder bin, a blowing tank, and a blowing elbow connected in sequence

[0012] The blowing medium of the bottom blowing lance includes powder and gas medium, and the powder is selected from at least one of lime powder, carbon powder, pulverized coal, limestone powder, alloy powder, and ore powder;

[0013] When there are two or more types of powder injection, at least two independent powder injection systems are set to inject powder respectively, and the powder injection systems are connected to the rotary joints on the side wall of the converter body through pipelines.

[0014] Optionally, the powder injection system provides a power gas source through a bottom blowing gas valve station; the bottom blowing gas valve station is connected to the distributor and the powder injection system through pipelines respectively, and is used to regulate the gas medium flow rate.

[0015] Optionally, the bottom blowing lance is in the form of a ring slot or a single hole;

[0016] The central hole of the bottom blowing lance in the form of a ring slot is used to transport gas medium and powder, and the ring slot is filled with cooling and protective gas;

[0017] The bottom blowing lance in the form of a single hole is filled with inert gas.

[0018] Optionally, the number of bottom blowing lances is 2 - 20.

[0019] Optionally, the system switches the following modes according to the process scenario:

[0020] High scrap ratio smelting mode: The powder medium is injected into the molten pool through the rotary joints, distributors, and bottom blowing lances on both sides of the converter body;

[0021] High-efficiency dephosphorization and slag-reducing smelting mode: Lime powder is injected into the molten bath through a rotary joint, a distributor and a bottom blowing lance on one side of the converter body;

[0022] Ultra-low carbon oxygen product smelting mode: The powder injection system is closed, and a large flow of inert gas is introduced into the bottom blowing lance by the bottom blowing gas valve station for molten bath stirring;

[0023] Conventional smelting mode: Replace the annular gap bottom blowing lance of the movable furnace bottom with a single-hole bottom blowing lance, close the powder injection system, and adjust the flow rate of the bottom blowing gas valve station.

[0024] A smelting method based on the above converter smelting system, comprising the following steps:

[0025] S1. Empty furnace waiting stage: Nitrogen is introduced into the converter molten bath through the bottom blowing lance to prevent the bottom blowing lance from being blocked;

[0026] S2. Charging stage: Maintain bottom blowing nitrogen during the addition of scrap steel, and increase the bottom blowing nitrogen flow rate during the tapping of hot metal to prevent the backflow of hot metal;

[0027] S3. High-efficiency dephosphorization stage: After the charging is completed, part of the bottom blowing lances are switched to the oxygen-lime powder injection mode, and the remaining bottom blowing lances maintain oxygen stirring;

[0028] S4. In-furnace heat supplement stage: According to the flue gas analysis results, when the CO concentration reaches the peak value, part of the bottom blowing lances are switched to the nitrogen-carbon powder injection mode;

[0029] S5. Blowing stage: After stopping the powder injection, the bottom blowing lance is switched to pure oxygen blowing, and after reaching the blowing end point, it is switched to argon for post-stirring;

[0030] S6. Tapping stage: Bottom blowing argon in the early stage of tapping, and switching to bottom blowing nitrogen in the later stage of tapping;

[0031] S7. Slag splashing and slag pouring stage: Increase the bottom blowing nitrogen flow rate for slag splashing operation, and reset the converter after slag pouring.

[0032] Optionally, in S1 and S2, the nitrogen flow rate through the central hole of a single bottom blowing lance is 200 - 1800 Nm 3 / h, and the nitrogen flow rate through the annular gap is 50 - 240 Nm 3 / h;

[0033] In S3, the lime powder injection amount of a single bottom blowing lance is 50 - 180 kg / min, the oxygen flow rate through the central hole is 200 - 1800 Nm 3 / h, and the natural gas flow rate through the annular gap is 50 - 240 Nm 3 / h;

[0034] In S4, the carbon powder injection rate of a single bottom blowing lance is 50 - 180 kg / min, the nitrogen gas flow rate through the central hole is 200 - 1800 Nm 3 / h, and the natural gas flow rate through the annular gap is 50 - 240 Nm 3 / h;

[0035] In S5, the oxygen or nitrogen gas flow rate of the bottom blowing lance is 200 - 1800 Nm 3 / h, the natural gas flow rate through the annular gap is 50 - 240 Nm 3 / h, and the argon gas flow rate after the end of blowing is 200 - 1800 Nm 3 / h, and the argon gas flow rate through the annular gap is 50 - 240 Nm 3 / h;

[0036] In S6, the argon and nitrogen gas flow rate is 200 - 1800 Nm 3 / h, and the nitrogen and argon gas flow rate through the annular gap is 50 - 240 Nm 3 / h;

[0037] In S7, the nitrogen gas flow rate of a single bottom blowing lance is 200 - 1800 Nm 3 / h, and the nitrogen gas flow rate through the annular gap is 50 - 240 Nm 3 / h.

[0038] Optionally, the gas source pressure of the central hole and the annular gap of the bottom blowing lance is not less than 1.8 MPa.

[0039] Optionally, in the step S3, the oxygen flow rate of the oxygen lance is 30000 Nm 3 / h, and the blowing time is 7 - 8 min;

[0040] In the step S4, the carbon powder injection time is 8 - 9 min;

[0041] In the step S5, the post - stirring time is 0.5 - 1 min.

[0042] Optionally, the process scenario includes at least one of high scrap ratio smelting, high - efficiency dephosphorization and slag - less smelting, ultra - low carbon oxygen product smelting, and conventional smelting.

[0043] The beneficial effects of the present invention are as follows:

[0044] The converter smelting system and method of the present invention achieve a significant improvement in smelting efficiency, resource utilization rate, and product quality in multiple dimensions through structural innovation and process optimization.

[0045] First, at the system design level, by configuring an active furnace bottom, multi-channel bottom blowing guns, and a modular powder injection system, the physical basis for medium transportation and switching is constructed. The bottom blowing guns adopt a composite structure combining a ring slot and a single hole. The central hole is responsible for the precise transportation of powder and carrier gas, and the ring slot is used to introduce protective gas to extend the service life of the gun body. This design not only solves the problems of easy blockage and short service life of traditional bottom blowing guns but also ensures the efficient contact between the powder and the molten bath. The interlocking design of the distributor and the rotary joint supports the multi-medium branched transportation, providing hardware support for the flexible switching of different process scenarios.

[0046] Second, at the process control level, by dynamically regulating the injection parameters in stages, the precise matching of metallurgical reactions and thermodynamics is achieved. For example, in the high-efficiency dephosphorization stage, bottom blown oxygen and lime powder are injected synergistically, strengthening the stirring of the molten bath and expanding the reaction interface. The dissolution rate of lime powder increases by more than 30%, the lime consumption per ton of steel is reduced by 10 - 20 kg, and the slag volume is reduced by 15% - 25%, significantly reducing the auxiliary material cost and environmental load. In the in-furnace heat supplement stage, bottom injection of carbon powder and nitrogen triggers an endothermic reaction, and the heat supplement efficiency is increased by 40% compared with the traditional combustion method. The scrap ratio is increased to more than 30%, and the carbon emission per ton of steel is reduced by 59 - 246 kg, contributing to green and low-carbon production.

[0047] Third, at the end-point quality control level, through post-stirring with a large flow of inert gas and argon-protected tapping, the oxygen content distribution in the molten bath is more uniform, the end-point carbon-oxygen product is reduced to 0.0014, the purity of the molten steel is improved, and the generation amount of inclusions is reduced by 20% - 30%, laying a foundation for the development of high-end steel grades.

[0048] In addition, the multi-functional integration of the system breaks through the limitations of the traditional converter's single mode. Users can choose high scrap ratio, high-efficiency dephosphorization, ultra-low carbon-oxygen product, or conventional smelting modes according to their needs, significantly enhancing the production adaptability and increasing the equipment utilization rate by more than 15%. Comprehensive calculations show that this solution can increase the comprehensive benefit per ton of steel by 14 - 31 yuan, with both significant economic and environmental benefits.

[0049] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in preferred detail below in conjunction with the drawings, where:

[0051] Figure 1 is the converter system diagram;

[0052] Figure 2 It is the operation curve of the smelting process with a high scrap ratio;

[0053] Figure 3 It is the operation curve of the smelting process for efficient dephosphorization and slag reduction;

[0054] Figure 4 It is the operation curve of the smelting process for ultra-low carbon oxygen product.

[0055] Reference numerals: 1-converter body, 2-oxygen lance, 3-rotating joint, 4-movable furnace bottom, 5-bottom blowing lance, 6-distributor, 7-assist blowing elbow, 8-injection tank, 9-powder bin, 10-bottom blowing valve station. Specific embodiments

[0056] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0057] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0058] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only for illustrative purposes and should not be construed as a limitation to the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0059] Please refer to Figures 1 to 4, This solution relates to a converter smelting system. The system includes a converter body 1, an oxygen lance 2 is arranged at the top of the converter body 1, a movable hearth 4 is at the bottom of the converter body 1, a bottom blowing lance 5 is arranged on the movable hearth 4, the end of the bottom blowing lance 5 is connected to a distributor 6 through a pipeline, the distributor 6 is connected to a rotary joint 3 on the side of the converter body 1 through a pipeline, and the rotary joint 3 is connected to the powder injection system pipeline through a pipeline; the powder injection system includes a powder bin 9, a blowing tank 8, and an auxiliary blowing elbow 7, and a power gas source is provided for it through a bottom blowing gas valve station; the blowing medium of the powder injection system includes but is not limited to: lime powder, carbon powder, coal powder, limestone powder, alloy powder, ore powder, etc.; when there are two or more types of powder injection, the multiple powder injection systems are respectively connected to the rotary joints 3 on both sides of the converter through pipelines.

[0060] The bottom blowing lance 5 adopts a ring seam form and a single hole form. Among them, the medium of the central hole in the ring seam form is the conveying gas + powder agent, the medium of the ring seam is the cooling and protection gas, and the medium of the single hole form is the inert gas; for the converter smelting system, the number of the bottom blowing lances 5 is selected from 2 to 20 according to the nominal capacity and the height of the molten pool surface.

[0061] The process scenarios of this system are flexible, mainly including:

[0062] (1) When the converter has a high scrap ratio smelting requirement, the powder agent medium enters the converter molten pool finally through the rotary joints 3 on both sides of the converter body 1, the distributor 6 and the bottom blowing lance 5.

[0063] (2) When the converter has a high-efficiency dephosphorization smelting requirement, the lime powder enters the converter molten pool finally through the rotary joint 3 on one side of the converter body 1, the distributor 6 and the bottom blowing lance 5.

[0064] (3) When the converter only has a super low carbon oxygen product smelting requirement, the powder injection system can be closed, and only a large flow of inert gas is provided by the bottom blowing valve station 10 to enter the converter molten pool through the rotary joint 3 on one side of the converter body 1, the distributor 6 and the bottom blowing lance 5 for stirring.

[0065] (4) When there is a conventional smelting requirement, when replacing the movable hearth 4, the ring seam bottom blowing lance 5 is replaced with a single hole lance, the powder injection system is closed, and the flow rate of the bottom blowing gas valve station is adjusted.

[0066] This solution also relates to a method for realizing converter smelting by using the converter smelting system. This method designs the powder injection requirements according to the process scenarios, calculates the required powder agent injection amount and the gas medium flow rate, and adjusts the types and flow rates of the powder agent and the gas medium according to the process tasks in different stages.

[0067] This method specifically includes the following steps:

[0068] S1. Empty furnace waiting stage: Blow nitrogen at the bottom to ensure that the bottom blowing lance 5 is not blocked;

[0069] S2, Charging stage: During the addition of scrap steel, nitrogen is blown from the bottom to ensure that the bottom blowing lance 5 is not blocked. During the charging of hot metal, the bottom blowing flow rate is increased and nitrogen is blown from the bottom to prevent the backflow of hot metal.

[0070] S3, High-efficiency dephosphorization stage: After the charging stage in step S2 is completed, the bottom blowing lance 5 is changed to blow oxygen to stir the molten bath. After blowing for a period of time, the oxygen lance 2 descends to blow oxygen, and part of the bottom blowing lances 5 are changed to oxygen-lime powder, while the remaining bottom blowing lances 5 still blow oxygen from the bottom.

[0071] S4, In-furnace heat supplement stage: During the oxygen blowing smelting process of the oxygen lance 2 after the charging stage in step S2 is completed, when the CO concentration returned by the flue gas analysis reaches the peak value, the bottom blowing lances 5 that blow oxygen in step S3 are changed to blow nitrogen-carbon powder from the bottom.

[0072] S5, Blowing stage: After the injection amounts of lime powder in step S3 and carbon powder in step S4 reach the preset values respectively, the powder injection is stopped, and the corresponding bottom blowing lances 5 are switched to blow oxygen from the bottom. After reaching the blowing end point, the bottom blowing lances 5 are switched to argon for post-stirring until the tapping condition is met.

[0073] S6, Tapping stage: After confirming that the tapping condition is met, prepare for tapping. The bottom blowing gas is argon. During the tapping process, when the tilting angle of the converter is in the range of -75° to -120°, the bottom blowing gas is switched to nitrogen until the tapping is completed.

[0074] S7, Slag splashing and slag pouring stage: After the tapping is completed, the converter is swung to the vertical position, the bottom blowing nitrogen flow rate is increased for bottom blowing slag splashing operation. During this period, the converter is rocked within the range of -50° to 50°. After the slag splashing is completed, pour the slag, swing the converter to the vertical position, and wait for the next furnace smelting.

[0075] In a specific embodiment, nitrogen is blown from the bottom in S1, where the bottom blowing gas flow rate through the central hole is 1800 - 15000 Nm 3 / h, and nitrogen is used as the protective gas for the ring gap with a flow rate of 540 - 2100 Nm 3 / h. Nitrogen is blown from the bottom in S2, where the bottom blowing gas flow rate through the central hole is 1800 - 15000 Nm 3 / h, and nitrogen is used as the protective gas for the ring gap with a flow rate of 540 - 2100 Nm 3 / h. Lime powder + oxygen is blown from the bottom in S3, where the lime powder flow rate is 300 - 900 kg / min, oxygen is used as the carrier gas for the central hole, and the gas flow rate is 1800 - 15000 Nm 3 / h, and natural gas is used as the protective gas for the ring gap with a flow rate of 540 - 2100 Nm 3 / h. In S4, carbon powder and nitrogen are blown from the bottom, with the carbon powder flow rate being 300 - 900 kg / min. Nitrogen is used as the carrier gas in the central hole, and the gas flow rate is 1800 - 15000 Nm 3 / h. Natural gas is used as the protective gas in the annular gap, and the flow rate is 540 - 2100 Nm 3 / h. In S5, the blowing stage, after stopping the powder injection, oxygen and nitrogen are blown from the bottom of the central hole respectively, and the gas flow rate is 1800 - 15000 Nm 3 / h. Natural gas is used as the protective gas in the annular gap, and the flow rate is 540 - 2100 Nm 3 / h; after the end of blowing, argon is blown from the bottom of the central hole, and the gas flow rate is 1800 - 15000 Nm 3 / h. Argon is used as the protective gas in the annular gap, and the flow rate is 540 - 2100 Nm 3 / h. In S6, the tapping stage, in the early stage of tapping, argon is blown from the bottom of the central hole, and the gas flow rate is 1800 - 15000 Nm 3 / h. Argon is used as the protective gas in the annular gap, and the flow rate is 540 - 2100 Nm 3 / h; in the later stage of tapping, nitrogen is blown from the bottom of the central hole, and the gas flow rate is 1800 - 15000 Nm 3 / h. Nitrogen is used as the protective gas in the annular gap, and the flow rate is 540 - 2100 Nm 3 / h. In S7, the slag splashing and slag tipping stage, nitrogen is blown from the bottom of the central hole, and the gas flow rate is 1800 - 15000 Nm 3 / h. Nitrogen is used as the protective gas in the annular gap, and the flow rate is 540 - 2100 Nm 3 / h. The gas source pressure of the gas used in the central pipe and the annular gap is required to be not less than 1.8 MPa.

[0076] Example 1

[0077] This example is a method for high scrap ratio smelting in a 150 - ton converter.

[0078] The system for high scrap ratio smelting in a 150t converter includes the converter body 1. An oxygen lance 2 is configured at the top of the converter body 1. The bottom of the converter body 1 is a movable bottom 4. A bottom blowing lance 5 is configured on the movable bottom 4. The end of the bottom blowing lance 5 is connected to a distributor 6 through a pipeline. The distributor 6 is connected to a rotary joint 3 on the side of the converter body 1 through a pipeline. The rotary joint 3 is connected to the powder injection system pipeline through a pipeline; the powder injection system includes a powder silo 9, a blowing tank 8, and an auxiliary blowing elbow 7, and a power gas source is provided for it through a bottom blowing gas valve station; the blowing medium of the powder injection system includes: lime powder, carbon powder; the powder injection system is connected to the rotary joints 3 on both sides of the converter through pipelines.

[0079] In the 150t converter of this embodiment, 9 circumferential-seam bottom-blowing lances 5 are arranged at the bottom of the furnace, vertically arranged at the bottom of the furnace, and symmetrically distributed along the trunnion center line.

[0080] The specific smelting steps are as follows:

[0081] S1. Empty furnace waiting stage: Bottom-blow nitrogen, the nitrogen flow rate through the central hole of a single lance is 720 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 86 Nm 3 / h to ensure that the bottom-blowing lance 5 is not blocked;

[0082] S2. Charging stage: During the process of adding scrap steel, bottom-blow nitrogen, the nitrogen flow rate through the central hole of a single lance is 720 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 86 Nm 3 / h to ensure that the bottom-blowing lance 5 is not blocked. During the process of tapping hot metal, increase the bottom-blowing flow rate, the nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 128 Nm 3 / h to prevent the backflow of hot metal;

[0083] S3. High-efficiency dephosphorization stage: After the charging stage in step S2 is completed, the bottom-blowing lance 5 is changed to bottom-blow oxygen to stir the molten bath. The oxygen flow rate through the central hole of a single lance is 1440 Nm 3 / h, and the natural gas flow rate through the circumferential seam is 175 Nm 3 / h. After blowing for 1 min, lower the oxygen lance 2 to blow oxygen, and the flow rate of the oxygen lance 2 is 30000 Nm 3 / h. 6 bottom-blowing lances 5 are changed to oxygen-lime powder injection. The oxygen flow rate through the central hole of a single lance is 1440 Nm 3 / h, the lime powder flow rate is 100 kg / min, and the natural gas flow rate through the circumferential seam is 175 Nm 3 / h, and the time is about 7 - 8 min. The remaining 3 bottom-blowing lances 5 are still bottom-blowing oxygen. The oxygen flow rate through the central hole of a single lance is 1440 Nm 3 / h, and the natural gas flow rate through the circumferential seam is 175 Nm 3 / h;

[0084] S4. In-furnace heat supplement stage: During the process of blowing oxygen by the oxygen lance 2 after the charging stage in step S2 is completed, when the CO concentration returned by the flue gas analysis reaches the peak value, the remaining 3 bottom-blowing lances 5 in step S3 are changed from bottom-blowing oxygen to bottom-blowing nitrogen-carbon powder. The nitrogen flow rate through the central hole of a single lance is 1440 Nm 3 / h, the carbon powder flow rate is 100 kg / min, and the natural gas flow rate through the circumferential seam is 175 Nm 3 / h, and the time is about 8 - 9 min;

[0085] S5. Blowing stage: After the injection amounts of lime powder in step S3 and carbon powder in step S4 reach their preset values respectively, powder injection is stopped. Accordingly, the bottom blowing lance 5 is switched to bottom blowing oxygen. The oxygen flow rate through the central hole of a single lance is 1440 Nm 3 / h, and the natural gas flow rate through the annular gap is 175 Nm 3 / h. After blowing for about 1 - 2 min, the blowing end point is reached. The 9 bottom blowing lances 5 are switched to argon for post-stirring. The argon flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the argon flow rate through the annular gap is 128 Nm 3 / h. The time is about 0.5 - 1 min until the tapping condition is met;

[0086] S6. Tapping stage: After confirming that the tapping condition is met, tapping is prepared. The bottom blowing gas is argon. The argon flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the argon flow rate through the annular gap is 128 Nm 3 / h. During tapping, when the tilting angle of the converter is in the range of -75° to -120°, the bottom blowing gas is switched to nitrogen. The nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the annular gap is 128 Nm 3 / h until tapping is completed;

[0087] S7. Slag splashing and slag pouring stage: After tapping is completed, the converter is swung to the vertical position, and the bottom blowing nitrogen flow rate is increased. The nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the annular gap is 128 Nm 3 / h. Bottom blowing slag splashing operation is carried out. During this period, the converter is rocked within the range of -50° to 50°. After slag splashing is completed, the slag is poured, and the converter is swung to the vertical position, waiting for the next furnace smelting.

[0088] The results show that: After adopting the smelting method of this embodiment, the converter smelting process is stable, splashing can be better controlled, the scrap ratio reaches 30%, the lime consumption per ton of steel is reduced by 15 kg, the iron and steel materials consumption per ton of steel is reduced by 13 kg, the end-point carbon-oxygen product is reduced to 14×10 -4 , the carbon emission per ton of steel is reduced by 246 kg, and the benefit per ton of steel is increased by 27 yuan.

[0089] Example 2

[0090] This example is a method for high-efficiency dephosphorization and slag reduction smelting for a 150-ton converter.

[0091] The system for high-efficiency dephosphorization and slag-reducing smelting in a 150t converter includes a converter body 1. An oxygen lance 2 is arranged at the top of the converter body 1. The bottom of the converter body 1 is a movable bottom 4. A bottom blowing lance 5 is arranged on the movable bottom 4. The end of the bottom blowing lance 5 is connected to a distributor 6 through a pipeline. The distributor 6 is connected to a rotary joint 3 on the side of the converter body 1 through a pipeline. The rotary joint 3 is connected to the powder injection system pipeline through a pipeline. The powder injection system includes a powder silo 9, a blowing tank 8, and an assisting blowing elbow 7, and a power gas source is provided for it through a bottom blowing gas valve station. The blowing medium of the powder injection system includes lime powder. The powder injection system is connected to the rotary joint 3 on one side of the converter through pipelines respectively.

[0092] In this embodiment, 6 circumferential seam bottom blowing lances 5 are arranged at the bottom of the 150t converter, vertically arranged at the bottom of the furnace, and symmetrically staggered along the trunnion center line.

[0093] The specific smelting steps are as follows:

[0094] S1. Empty furnace waiting stage: Bottom blow nitrogen, the nitrogen flow rate through the central hole of a single lance is 720 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 86 Nm 3 / h to ensure that the bottom blowing lance 5 is not blocked;

[0095] S2. Charging stage: During the addition of scrap steel, bottom blow nitrogen, the nitrogen flow rate through the central hole of a single lance is 720 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 86 Nm 3 / h to ensure that the bottom blowing lance 5 is not blocked. During the charging of hot metal, increase the bottom blowing flow rate, the nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 128 Nm 3 / h to prevent the backflow of hot metal;

[0096] S3. High-efficiency dephosphorization stage: After the charging stage in step S2 ends, the bottom blowing lance 5 is changed to bottom blow oxygen to stir the molten bath. The oxygen flow rate through the central hole of a single lance is 1440 Nm 3 / h, and the natural gas flow rate through the circumferential seam is 175 Nm 3 / h. After blowing for 1 min, lower the oxygen lance 2 to blow oxygen, and the flow rate of the oxygen lance 2 is 30000 Nm 3 / h. The bottom blowing lance 5 is changed to oxygen-lime powder injection. The oxygen flow rate through the central hole of a single lance is 1440 Nm 3 / h, the lime powder flow rate is 100 kg / min, and the natural gas flow rate through the circumferential seam is 175 Nm 3 / h, and the time is about 7 - 8 min;

[0097] S4. Blowing stage: After the lime powder injection amount in step S3 reaches the preset value, stop powder injection. The bottom blowing lance 5 is switched to bottom blow oxygen, and the oxygen flow rate through the central hole of a single lance is 1440 Nm3 / h, the annular seam natural gas flow rate is 175 Nm 3 / h. After blowing for about 1 - 2 min, the blowing end point is reached, and it is switched to argon for post-stirring. The argon flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the annular seam argon flow rate is 128 Nm 3 / h, and the time is about 0.5 - 1 min until the tapping condition is met;

[0098] S5. Tapping stage: After confirming that the tapping condition is met, prepare for tapping. The bottom-blowing gas is argon. The argon flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the annular seam argon flow rate is 128 Nm 3 / h. During tapping, when the tilting angle of the converter is in the range of -75° to -120°, the bottom-blowing gas is switched to nitrogen. The nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the annular seam nitrogen flow rate is 128 Nm 3 / h until tapping is completed;

[0099] S6. Slag splashing and slag pouring stage: After tapping is completed, tilt the converter to the vertical position and increase the bottom-blowing nitrogen flow rate. The nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the annular seam nitrogen flow rate is 128 Nm 3 / h. Perform bottom-blowing slag splashing operation. During this period, tilt the converter within the range of -50° to 50°. After slag splashing is completed, pour the slag, tilt the converter to the vertical position, and wait for the next furnace smelting.

[0100] The results show that: After adopting the smelting method of this embodiment, the converter smelting process is stable, the splashing can be better controlled, the lime consumption per ton of steel is reduced by 10 kg, the iron and steel materials consumption per ton of steel is reduced by 10 kg, the terminal carbon-oxygen product is reduced to 14×10 -4 , the carbon emission per ton of steel is reduced by 152 kg, and the benefit per ton of steel is increased by 31 yuan.

[0101] Example 3

[0102] This example is a method for ultra-low carbon-oxygen product smelting used in a 150-ton converter.

[0103] The system for smelting with ultra-low carbon oxygen product in a 150t converter includes a converter body 1. An oxygen lance 2 is arranged at the top of the converter body 1. The bottom of the converter body 1 is a movable hearth 4. A bottom blowing lance 5 is arranged on the movable hearth 4. The end of the bottom blowing lance 5 is connected to a distributor 6 through a pipeline. The distributor 6 is connected to a rotary joint 3 on the side of the converter body 1 through a pipeline. The rotary joint 3 is connected to the powder injection system pipeline through a pipeline. The powder injection system includes a powder bin 9, a blowing tank 8, and a blowing elbow 7, and a power gas source is provided for it through a bottom blowing gas valve station. The blowing medium of the powder injection system includes lime powder. The powder injection system is connected to the rotary joint 3 on one side of the converter through pipelines respectively.

[0104] In this embodiment, 6 circumferential seam bottom blowing lances 5 are arranged at the bottom of the 150t converter hearth, vertically arranged at the hearth, and symmetrically staggered along the trunnion center line.

[0105] The specific smelting steps are as follows:

[0106] S1. Empty furnace waiting stage: Bottom blow nitrogen, the nitrogen flow rate through the central hole of a single lance is 720 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 86 Nm 3 / h to ensure that the bottom blowing lance 5 is not blocked;

[0107] S2. Charging stage: During the addition of scrap steel, bottom blow nitrogen, the nitrogen flow rate through the central hole of a single lance is 720 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 86 Nm 3 / h to ensure that the bottom blowing lance 5 is not blocked. During the charging of hot metal, increase the bottom blowing flow rate, the nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 128 Nm 3 / h to prevent the backflow of hot metal;

[0108] S3. Blowing stage: After the charging stage in step S2 ends, maintain the bottom blowing nitrogen flow rate unchanged, the nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the circumferential seam is 128 Nm 3 / h, and the flow rate of the oxygen lance 2 is 30000 Nm 3 / h, and the blowing time is about 12 - 14 min;

[0109] S4. Post-stirring stage: After reaching the blowing end point, switch the bottom blowing to argon for post-stirring. The argon flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the argon flow rate through the circumferential seam is 128 Nm 3 / h, and the time is about 2 - 3 min until the tapping condition is met;

[0110] S5. Tapping stage: After confirming that the tapping conditions are met, prepare for tapping. The bottom-blowing gas is argon. The argon flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the argon flow rate through the ring gap is 128 Nm 3 / h. During the tapping process, when the tilting angle of the converter is in the range of -75° to -120°, the bottom-blowing gas is switched to nitrogen. The nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the ring gap is 128 Nm 3 / h until the tapping is completed;

[0111] S6. Slag splashing and slag pouring stage: After the tapping is completed, tilt the converter to the vertical position, increase the bottom-blowing nitrogen flow rate. The nitrogen flow rate through the central hole of a single lance is 1070 Nm 3 / h, and the nitrogen flow rate through the ring gap is 128 Nm 3 / h, and perform bottom-blowing slag splashing operation. During this period, the converter is tilted within the range of -50° to 50°. After the slag splashing is completed, pour the slag, tilt the converter to the vertical position, and wait for the next furnace smelting.

[0112] The results show that: After adopting the smelting method of this embodiment, the converter smelting process is stable, the splashing can be better controlled, the lime consumption per ton of steel is reduced by 5 kg, the steel and iron materials consumption per ton of steel is reduced by 2 kg, and the end-point carbon-oxygen product is reduced to 14×10 -4 , the carbon emission per ton of steel is reduced by 59 kg, and the benefit per ton of steel is increased by 14 yuan.

[0113] The advantages of the present invention are as follows:

[0114] 1) Relying on the chemical reaction process in the furnace, select the type of bottom-injected powder medium and the injection timing, improve the heat supplement efficiency in the furnace while ensuring the dephosphorization effect, and lay a solid foundation for carbon reduction and high-quality development in the converter process;

[0115] 2) The process scenario has flexibility and can selectively switch the function according to actual needs;

[0116] 3) By using the smelting system and method described in the present invention, the scrap ratio can be increased to 30% and above, the lime consumption per ton of steel is reduced by 5 kg - 15 kg, the steel and iron materials consumption per ton of steel is reduced by 2 kg - 13 kg, the end-point carbon-oxygen product is reduced to 0.0014, the carbon emission per ton of steel is reduced by 59 - 246 kg, and the benefit per ton of steel is increased by 14 - 31 yuan.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A converter smelting system, characterized in that, Comprising: A converter body (1) with an oxygen lance (2) configured at its top and a movable bottom (4) at its bottom; At least two bottom blowing lances (5) are configured on the movable bottom (4), and the ends of the bottom blowing lances (5) are connected to a distributor (6) through pipelines; The distributor (6) is connected to a rotary joint (3) arranged on the side of the converter body (1) through a pipeline, and the rotary joint (3) is connected to a powder injection system pipeline through a pipeline; The powder injection system includes a powder bin (9), a blowing tank (8), and a blowing elbow (7) that are connected in sequence; The blowing medium of the bottom blowing lance (5) includes powder and gas medium, and the powder is selected from at least one of lime powder, carbon powder, pulverized coal, limestone powder, alloy powder, and ore powder; When there are two or more types of powder injection, at least two independent powder injection systems are set to inject powder respectively, and the powder injection systems are connected to the rotary joint (3) on the side wall of the converter body (1) through pipelines respectively.

2. The converter smelting system according to claim 1, wherein: The powder injection system is powered by a bottom blowing gas valve station (10); the bottom blowing gas valve station (10) is connected to the distributor (6) and the powder injection system through pipelines respectively for regulating the flow rate of the gas medium.

3. The converter smelting system according to claim 1, wherein: The bottom blowing lance (5) is in the form of an annular slit or a single hole; The central hole of the bottom blowing lance (5) in the form of an annular slit is used to convey the gas medium and powder, and the annular slit is filled with cooling and protective gas; The single-hole bottom blowing lance (5) is filled with inert gas.

4. The converter smelting system according to claim 1, wherein: The number of the bottom blowing lances (5) is 2 - 20.

5. The converter smelting system according to claim 1, wherein: The system switches the following modes according to the process scenario: High scrap ratio smelting mode: The powder medium is injected into the molten bath through the rotary joints (3), the distributor (6), and the bottom blowing lances (5) on both sides of the converter body (1); High-efficiency dephosphorization and low-slag smelting mode: Lime powder is injected into the molten bath through the rotary joint (3), the distributor (6), and the bottom blowing lance (5) on one side of the converter body (1); Ultra-low carbon oxygen product smelting mode: The powder injection system is closed, and a large flow of inert gas is introduced into the bottom blowing lances (5) by the bottom blowing gas valve station (10) for stirring the molten bath; Conventional smelting mode: The annular slit bottom blowing lance (5) of the movable bottom (4) is replaced with a single-hole bottom blowing lance (5), the powder injection system is closed, and the flow rate of the bottom blowing gas valve station (10) is adjusted.

6. A smelting method for a converter smelting system according to any one of claims 1-5, characterized in that, Including the following steps: S1. Empty furnace waiting stage: Nitrogen is introduced into the converter molten bath through the bottom blowing lance (5) to prevent the bottom blowing lance (5) from being blocked; S2. Charging stage: Bottom blowing nitrogen is maintained during the addition of scrap, and the flow rate of bottom blowing nitrogen is increased during the tapping of hot metal to prevent the backflow of hot metal; S3. High-efficiency dephosphorization stage: After the charging is completed, part of the bottom blowing lances (5) are switched to the oxygen-lime powder injection mode, and the remaining bottom blowing lances (5) maintain oxygen stirring; S4. In-furnace heat supplement stage: According to the flue gas analysis results, when the CO concentration reaches the peak value, part of the bottom blowing lances (5) are switched to the nitrogen-carbon powder injection mode; S5. Blowing stage: After stopping powder injection, switch the bottom blowing lance (5) to pure oxygen blowing, and switch to argon for post-stirring after reaching the blowing end point; S6. Tapping stage: Argon is blown at the bottom in the early stage of tapping, and nitrogen is blown at the bottom in the later stage of tapping; S7. Slag splashing and slag tipping stage: Increase the bottom blowing nitrogen flow rate for slag splashing operation, and reset the converter after slag tipping.

7. The smelting method according to claim 6, wherein: In S1 and S2, the nitrogen flow rate through the central hole of a single bottom blowing lance (5) is 200 - 1800 Nm 3 / h, and the nitrogen flow rate through the annular gap is 50 - 240 Nm 3 / h; In S3, the lime powder injection rate of a single bottom blowing lance (5) is 50 - 180 kg / min, the oxygen flow rate through the central hole is 200 - 1800 Nm 3 / h, and the natural gas flow rate through the annular gap is 50 - 240 Nm 3 / h; In S4, the carbon powder injection rate of a single bottom blowing lance (5) is 50 - 180 kg / min, the nitrogen gas flow rate through the central hole is 200 - 1800 Nm 3 / h, and the natural gas flow rate through the annular gap is 50 - 240 Nm 3 / h; In S5, the oxygen or nitrogen flow rate of the bottom blowing lance (5) is 200 - 1800 Nm 3 / h, the annular gap natural gas flow rate is 50 - 240 Nm 3 / h, the argon flow rate after the end of blowing is 200 - 1800 Nm 3 / h, the annular gap argon flow rate is 50 - 240 Nm 3 / h; In S6, the flow rates of argon and nitrogen are 200 - 1800 Nm 3 / h, and the flow rates of circumferential seam nitrogen and argon are 50 - 240 Nm 3 / h; In S7, the nitrogen flow rate of a single bottom blowing lance (5) is 200 - 1800 Nm 3 / h, and the nitrogen flow rate of the annular gap is 50 - 240 Nm 3 / h.

8. The smelting method according to claim 6, wherein: The gas source pressure of the central hole and the annular gap of the bottom blowing lance (5) is not less than 1.8 MPa.

9. The smelting method according to claim 6, wherein: In the step S3, the oxygen flow rate of the oxygen lance (2) is 30000 Nm 3 / h, and the blowing time is 7 - 8 min; In the step S4, the carbon powder injection time is 8 - 9 min; In the step S5, the post-stirring time is 0.5 - 1 min.

10. The smelting method according to claim 6, wherein: The process scenarios include at least one of high scrap ratio smelting, high-efficiency dephosphorization and low-slag smelting, ultra-low carbon oxygen product smelting, and conventional smelting.

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