Method for efficiently splashing slag to protect converter by mixed blowing of CO2-N2 in converter

Abstract

The invention provides a mixed blowing CO2-N2 efficient slag splashing protection method for a converter, and relates to the technical field of metallurgy. The method comprises the following steps: firstly, determining flow and pressure of nitrogen and carbon dioxide according to different converter tonnages and steel slag conditions; during slag splashing, the nitrogen valve group and the carbon dioxide valve group are opened to set flow, and nitrogen containing a certain amount of carbon dioxide gas is blown into the converter through an oxygen lance to start slag splashing and converter protection; the flows of the nitrogen valve group and the carbon dioxide valve group are dynamically adjusted; and after the slag splashing ending standard is reached, the nitrogen valve group and the carbon dioxide valve group are sequentially closed, and slag splashing furnace protection is completed. According to the slag-splashing furnace protection method, the slag-splashing period can be effectively shortened, the slag-splashing furnace protection effect is improved, and the problems in the field at the present stage are solved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for high-efficiency slag splashing and furnace protection of a converter by mixed injection of CO2-N2. Background Art

[0002] The converter slag splashing furnace protection technology has been used for many years to protect the converter and increase the service life of the converter. Since the 1990s, my country has begun to develop a converter slag splashing furnace protection process that is suitable for national conditions. The slag splashing furnace protection technology is to spray high-pressure nitrogen through a spray gun, and the slag splashes through the outside of the holes in the injection impact zone and adsorbs onto the converter lining to form a slag layer, which can protect the lining for the next smelting. The converter final slag should not only meet the requirements of the smelting process, but also meet the conditions for slag splashing furnace protection, that is, the slag should be easy to splash onto the lining, and the slag splashed on the lining can be well combined with it, and the splashed slag should have a certain fire resistance and high temperature erosion resistance.

[0003] At this stage, the converter steelmaking field is facing the challenge of a fast-paced production model. In order to meet the requirements of high production and rapid furnace change, ensuring the protective effect of slag splashing in the furnace, shortening the slag splashing cycle, and increasing the service life of the converter have become urgent problems to be solved. In the current technology, the slag splashing time in the steelmaking process is relatively long, which not only affects the production efficiency, but also leads to poor protection of the converter and increases the risk of wear and damage to the equipment. Therefore, how to shorten the slag splashing cycle and improve its furnace protection effect while maintaining a high production speed has become the focus of industry research. In order to meet these challenges, the industry is focusing on exploring a variety of technical means. For example: the application of rapid cooling slag technology can significantly shorten the cooling time of the slag, thereby accelerating the formation of a protective layer. This includes the use of coolants such as nitrogen or carbon dioxide, and improving the design of the cooling system to increase the cooling rate and uniformity.

[0004] In view of this, this application is hereby filed. Summary of the invention

[0005] In order to solve the above technical problems existing in the prior art, the embodiment of the present invention provides a method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter. The technical solution is as follows:

[0006] A method for efficiently protecting a converter by mixed injection of CO2-N2 and slag splashing, the method comprising:

[0007] S1. Determine the nitrogen and carbon dioxide gas flow rates according to different converter tonnages and slag conditions;

[0008] S2, when slag splashing occurs, the nitrogen valve group and the carbon dioxide valve group are opened to the flow rate determined in step S1, and nitrogen containing carbon dioxide is sprayed into the converter by an oxygen lance to start slag splashing and furnace protection;

[0009] S3. Dynamically adjust the flow of the nitrogen valve group and the carbon dioxide valve group according to the actual situation of slag splashing;

[0010] S4. After the slag splashing is completed, close the nitrogen valve group and the carbon dioxide valve group at the same time to complete the slag splashing furnace protection.

[0011] The total flow rate of nitrogen and carbon dioxide in step S1 is determined by the following formula:

[0012] Hd t / D=13.77+0.73(Qh / d t ) 0.33 t,

[0013] Where, H is the height of the converter lining, mm; d t -Lance throat diameter, mm; D-converter lining diameter, mm; Q-gas flow, Nm 3 / min; h-spray gun height, mm; t-slag splashing time, min.

[0014] In step S3, when it is observed that the amount of slag splashing at the furnace mouth is small (the amount of slag splashing at the furnace mouth is gone within 1.5 minutes after the start of slag splashing), the carbon dioxide gas flow rate can be appropriately increased. Generally, the carbon dioxide gas flow rate can be increased to 110-120% of the original carbon dioxide gas flow rate, and the total carbon dioxide gas volume is ensured to not exceed the total nitrogen gas volume.

[0015] The carbon dioxide gas concentration is not less than 99.5%.

[0016] In step S2, the volume proportion of carbon dioxide gas in the total gas of carbon dioxide and nitrogen is 5-50%.

[0017] The oxygen lance outlet pressure during slag splashing and furnace protection in step S2 is the same as the pressure during oxygen blowing.

[0018] The total gas supply intensity of carbon dioxide and nitrogen for slag splashing and furnace protection in step S2 is 200-300Nm 3 / h·t.

[0019] The converter in step S1 is of 60-350 ton level.

[0020] By adjusting the flow rate in step S2, the cooling of the slag can be accelerated and the slag splashing time can be shortened. The nitrogen can react with the slag to generate a high-melting-point compound, and adhere to the wall of the converter to play a protective role. At the same time, the reaction of carbon dioxide with the slag is an endothermic reaction, which can reduce the slag to a preset temperature more quickly. This process can shorten the slag splashing cycle and protect the converter at the same time.

[0021] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0022] The carbon dioxide produced in steel production is applied to slag splashing and furnace protection, which shortens the slag splashing time and increases the service life of the converter. Nitrogen can react with the slag to generate high-melting-point compounds and adhere to the furnace wall of the converter to play a protective role. At the same time, the reaction of carbon dioxide and slag is an endothermic reaction, which can reduce the slag to a preset temperature more quickly. This process can shorten the slag splashing cycle and protect the converter. Therefore, the slag splashing furnace protection method proposed in the present invention shortens the slag splashing cycle, improves the effect of slag splashing and furnace protection, and solves the current difficulties in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is a schematic diagram of equipment involved in a method for efficient slag splashing and furnace protection by mixed injection of CO2-N2 in a converter provided by an embodiment of the present invention.

[0025] Among them: 1-nitrogen pipeline, 2-carbon dioxide pipeline, 3-nitrogen valve group, 4-carbon dioxide valve group, 5-oxygen gun, 6-converter. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0027] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0028] In the embodiments of the present invention, sometimes a subscript such as W1 may be written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0029] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0030] The embodiment of the present invention provides a method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter. Figure 1As shown, the equipment involved in the method includes a nitrogen pipeline 1, a carbon dioxide pipeline 2, a nitrogen valve group 3, a carbon dioxide valve group 4, an oxygen lance 5 and a converter 6. The nitrogen pipeline 1 is connected to the nitrogen valve group 3, and the carbon dioxide pipeline 2 is connected to the carbon dioxide valve group 4; the outlets of the nitrogen valve group 3 and the carbon dioxide valve group 4 are connected to the oxygen lance 5, and nitrogen and carbon dioxide are sprayed into the converter 6 through the oxygen lance 5 to perform slag splashing and furnace protection.

[0031] The method comprises the following steps:

[0032] S1. Determine the nitrogen and carbon dioxide gas flow rates according to different converter tonnages and slag conditions;

[0033] S2, when slag splashing occurs, the nitrogen valve group and the carbon dioxide valve group are opened to the flow rate determined in step S1, and nitrogen containing carbon dioxide is sprayed into the converter by an oxygen lance to start slag splashing and furnace protection;

[0034] S3. Dynamically adjust the flow of the nitrogen valve group and the carbon dioxide valve group according to the actual situation of slag splashing;

[0035] S4. After the slag splashing is completed, close the nitrogen valve group and the carbon dioxide valve group at the same time to complete the slag splashing furnace protection.

[0036] This will be described below with reference to specific embodiments.

[0037] Example 1

[0038] This example is a 150t converter in a steel plant in Shanxi. Its steel output is generally 170t, the outlet pressure is 0.95Mpa, the oxygen lance throat diameter is 42mm, the converter height-to-diameter ratio is 1.45, the oxygen lance height is 700mm, the designed average slag splashing time is about 3min, and the total gas outlet flow rate is determined by formula and experience to be 40000Nm 3 / h, the higher the proportion of carbon dioxide injection, the better (not more than 50%), the nitrogen flow rate is 35000Nm based on economic and experience factors. 3 / h, carbon dioxide gas flow rate is 5000Nm 3 / h.

[0039] When slag splashing starts, open the nitrogen valve group and the carbon dioxide valve group, increase the nitrogen flow and carbon dioxide flow to the preset value, start slag splashing, and reach the slag splashing end standard (generally confirmed according to the slag situation at the furnace mouth. When there is almost no slag splashing at the furnace mouth, it means the slag splashing has ended).

[0040] After using this method of utilizing CO2 to reduce the slag splashing and furnace protection time, the average slag splashing and furnace protection time was reduced from the original 2 minutes and 57 seconds to 2 minutes and 29 seconds, and the furnace service life was increased from the original 15,000 furnaces to 16,000 furnaces.

[0041] Example 2

[0042] This example is a 250t converter in a steel plant in Shandong. Its steel output is generally 270t, the outlet pressure is 1.1Mpa, the oxygen lance throat diameter is 45mm, the converter height-to-diameter ratio is 1.85, the oxygen lance height is 1000mm, the designed average slag splashing time is about 3.5min, and the total gas outlet flow rate is 60000Nm determined by formula and experience. 3 / h, the higher the proportion of carbon dioxide injection, the better (not more than 50%), the nitrogen flow rate is 50000Nm based on economic and experience factors. 3 / h, carbon dioxide gas flow rate is 10000Nm 3 / h.

[0043] When slag splashing starts, the nitrogen valve group and the carbon dioxide valve group are opened, the nitrogen flow rate and the carbon dioxide flow rate are increased to the preset value, and slag splashing begins. When the slag splashing end standard is reached, the slag splashing ends.

[0044] After using this method of utilizing CO2 to reduce the slag splashing and furnace protection time, the average slag splashing and furnace protection time was reduced from the original 3 minutes and 40 seconds to 3 minutes and 17 seconds, and the furnace service life was increased from the original 10,000 furnaces to 12,000 furnaces.

[0045] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter, characterized in that: The method comprises: S1. Determine the nitrogen and carbon dioxide gas flow rates according to different converter tonnages and slag conditions; S2, when slag splashing occurs, the nitrogen valve group and the carbon dioxide valve group are opened to the flow rate determined in step S1, and nitrogen containing carbon dioxide is sprayed into the converter by an oxygen lance to start slag splashing and furnace protection; S3. Dynamically adjust the flow of the nitrogen valve group and the carbon dioxide valve group according to the actual situation of slag splashing; S4. After the slag splashing is completed, close the nitrogen valve group and the carbon dioxide valve group at the same time to complete the slag splashing furnace protection.

2. The method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter according to claim 1 is characterized in that: The formula for determining the total flow rate of nitrogen and carbon dioxide in step S1 is as follows: Hd t / D=13.77+0.73(Qh / d t ) 0.33 t, Where H is the converter lining height, mm; d t is the diameter of the spray gun throat, mm; D is the diameter of the converter lining, mm; Q is the total gas flow, Nm 3 / min; h is the spray gun height, mm; t is the slag splashing time, min.

3. The method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter according to claim 1 is characterized in that: The carbon dioxide gas concentration is not less than 99.5%.

4. The method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter according to claim 1 is characterized in that: In step S2, the volume proportion of carbon dioxide gas in the total gas of carbon dioxide and nitrogen is 5-50%.

5. The method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter according to claim 1 is characterized in that: The oxygen lance outlet pressure during slag splashing and furnace protection in step S2 is the same as the pressure during oxygen blowing.

6. The method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter according to claim 1 is characterized in that: The total gas supply intensity of carbon dioxide and nitrogen for slag splashing and furnace protection in step S2 is 200-300Nm 3 / h·t.

7. The method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter according to claim 1 is characterized in that: In the step S3, when it is observed that the amount of slag splashing at the furnace mouth disappears within 1.5 minutes after the start of slag splashing, the carbon dioxide gas flow rate is increased to 110-120% of the original carbon dioxide gas flow rate, and the total carbon dioxide gas volume is ensured not to exceed the total nitrogen gas volume.

8. The method for high-efficiency slag splashing and furnace protection by mixed injection of CO2-N2 in a converter according to claim 1 is characterized in that: The converter in step S1 is of 60-350 ton level.

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