A method for increasing the service life of RH impregnated tubes

Abstract

The present invention provides a method for improving the service life of an RH dip tube, comprising the following steps: S1, baking the prepared RH vacuum chamber twice in succession to make the temperature of the vacuum chamber reach the production operation temperature; S2, after the temperature of the vacuum chamber reaches the production operation temperature, the dip tube is sequentially immersed in molten steel, sprayed for the first time and cured for the first time; S3, after the dip tube obtained in step S2 is sprayed for the second time and cured for the second time, it is put into production normally; S4, when it is put into production normally, the molten steel around the dip tube is treated: lime is added to increase the alkalinity of the top slag of the molten steel tank around the dip tube, so that the top slag becomes viscous; S5, after the molten steel treatment is completed, the thickness of the dip tube wall is increased by the movement of the dip tube at the molten steel liquid surface; S6, the thickness of the dip tube wall is dynamically monitored to ensure smooth production. The present invention can improve the service life of the RH dip tube by 15 to 20 tanks.

Description

Technical Field

[0001] The invention relates to the technical field of off-furnace refining, and in particular to a method for increasing the service life of an RH impregnation tube. Background Art

[0002] In order to increase the service life of RH dipped pipes, the conventional operation of each steel mill is basically to spray the dipped pipes online or offline after a certain period of continuous production, and then cure them for a period of time before resuming production. Conventional spraying technology can increase the service life of RH dipped pipes, but the production conditions of each steel mill are very different. For steel mills with fast production rhythm and complex steel types, relying solely on spraying to increase the service life of RH dipped pipes is limited. Therefore, it is necessary to further study new auxiliary methods to further increase the service life of RH dipped pipes. Summary of the invention

[0003] According to the above-mentioned production conditions of various steel mills are very different. For steel mills with fast production rhythm and complex steel types, simply relying on gunning to increase the service life of RH immersed tubes is a limited technical problem. A method for increasing the service life of RH immersed tubes is provided.

[0004] The technical means adopted by the present invention are as follows:

[0005] A method for increasing the service life of an RH impregnated tube comprises the following steps:

[0006] S1. Bake the prepared RH vacuum chamber twice to make the temperature of the vacuum chamber reach the production operating temperature;

[0007] S2. After the temperature of the vacuum chamber reaches the production operating temperature, the immersion tube is sequentially immersed in molten steel, sprayed for the first time, and cured for the first time;

[0008] S3, after the impregnated pipe obtained in step S2 is subjected to a second gunning repair and a second curing, it is put into normal production;

[0009] S4. When the production is put into normal operation, the molten steel around the immersion pipe is treated: lime is added to increase the basicity of the top slag of the molten steel tank around the immersion pipe, making the top slag viscous;

[0010] S5. After the molten steel treatment is completed, the wall thickness of the immersion tube is increased by moving the immersion tube at the molten steel liquid surface;

[0011] S6. Dynamically monitor the wall thickness of the immersion pipe to ensure smooth production.

[0012] Furthermore, in step S1, the RH vacuum chamber is first baked in the drying position for the first time, and when the conditions for online production are met, that is, the vacuum chamber temperature is ≥900°C, it is then hoisted to the standby position for the second baking. The second baking ensures that the vacuum chamber temperature meets ≥1100°C.

[0013] Furthermore, the step S2 comprises the following steps:

[0014] S21. When the temperature in the vacuum chamber reaches 1100°C or above, move the vacuum chamber to the processing position, arrange a tank of molten steel to enter the processing position, insert the immersion tube into the molten steel for the first immersion, and pull it out after immersing for 1-2 minutes;

[0015] S22, insert the immersion tube into the molten steel again for a second immersion, and pull it out after soaking for 1-2 minutes;

[0016] S23, then move the vacuum chamber to the standby position, perform the first conventional gunning repair on the impregnated pipe, and after the gunning repair is completed, cure for 1.5 to 2 hours.

[0017] Furthermore, in step S3, after the first curing is completed, the production is stopped after processing 1 to 2 tanks of molten steel, and the immersion pipe is subjected to a second conventional gunning repair. After the gunning repair is completed, the pipe is cured for 1.5 to 2 hours and then put into production normally.

[0018] Furthermore, in step S4, when the production is normally started, lime is prepared in advance; during the normal production process of RH, lime is evenly added to the molten steel around the immersion tube, and the total amount of lime added is controlled at 100 kg to increase the basicity of the top slag of the molten steel tank around the immersion tube and make the top slag viscous.

[0019] Furthermore, in step S5, after the molten steel treatment is completed, the immersion tube is not immediately lifted off the molten steel surface. The RH equipment lifting system is used to repeatedly move the immersion tube up and down twice at the molten steel surface, so that the viscous top slag of the molten steel tank is hung on the outer wall of the immersion tube as much as possible to increase the wall thickness of the immersion tube.

[0020] Furthermore, in step S6, the wall thickness of the immersion tube is dynamically monitored. When the distance between the outer wall of the immersion tube and the inner wall of the molten steel tank is ≤100 mm, the addition of lime is stopped, and the slag removal operation is performed on the wall of the immersion tube, or the conventional gunning amount is reduced to ensure smooth production.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The method for increasing the service life of the RH impregnated tube provided by the present invention can increase the service life of the RH impregnated tube by 15 to 20 cans.

[0023] In summary, the application of the technical solution of the present invention can solve the problem that the production conditions of various steel mills in the prior art are very different. For steel mills with a fast production rhythm and complex steel types, relying solely on gunning to increase the service life of RH impregnated pipes is limited.

[0024] Based on the above reasons, the present invention can be widely promoted in the field of increasing the service life of RH immersion tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] like Figure 1 As shown, the present invention provides a method for increasing the service life of the RH dip tube, belonging to the technical field of off-furnace refining, and in particular, increasing the service life of the RH dip tube by a special method.

[0031] The purpose of the present invention is to further improve the service life of the RH impregnated tube on the basis of the existing process.

[0032] The method for increasing the service life of the RH immersion tube comprises the following steps:

[0033] Step 1: For the newly prepared RH vacuum chamber, first bake it in the drying position to meet the conditions for online production, that is, after the vacuum chamber temperature is ≥900℃, it is then hoisted to the standby position for further baking. This baking must ensure that the vacuum chamber temperature meets ≥1100℃.

[0034] Step 2: When the temperature in the vacuum chamber reaches 1100°C or above, move the vacuum chamber to the processing position, and then arrange a tank of molten steel to enter the processing position. Insert the immersion tube into the molten steel, soak for 1 minute and then pull it out. The purpose is to remove the residual moisture in the main body of the immersion tube in the form of steam. Then insert it into the molten steel again, soak for 1 minute and then pull it out, and then move the vacuum chamber to the standby position for a routine gunning repair. After the gunning repair is completed, cure for 1.5 to 2 hours. The purpose of this operation is to strengthen the early strength of the immersion tube to avoid the peeling and damage of the main body material under the thermal shock of the molten steel in the early stage, thereby reducing the service life.

[0035] After the curing in step 3 and step 2 is completed, the production is stopped after processing 1 to 2 tanks of molten steel, and then a conventional gunning repair is performed. After the gunning repair is completed, the curing is performed for 1.5 to 2 hours, and then normal production can be resumed.

[0036] Step 4: When the production is put into normal operation, prepare several 10kg / bags of lime for hand-feeding in advance to treat the molten steel around the immersion tube. During the normal production of RH, lime is evenly added around the immersion tube (the total amount is controlled at 100kg). The purpose is to increase the basicity of the top slag of the molten steel tank around the immersion tube, so that the top slag becomes viscous.

[0037] Step 5. After the molten steel treatment is completed, the immersion tube should not be lifted off the molten steel surface immediately. Use the RH equipment lifting system to make the immersion tube move up and down twice at the molten steel surface. The purpose is to allow the viscous molten steel tank top slag to hang on the outer wall of the immersion tube as much as possible, thereby increasing the thickness of the immersion tube wall.

[0038] Step 6: Dynamically monitor the wall thickness of the immersion tube. If there is a trend of over-scraping the molten steel tank, that is, when the outer wall of the immersion tube is ≤100mm away from the inner wall of the molten steel tank, stop adding lime. You can remove slag from the wall of the immersion tube or reduce the amount of conventional gunning to ensure smooth production.

[0039] By using the method for increasing the service life of the RH dip tube of the present invention, the service life of the RH dip tube can be increased by 15 to 20 tanks.

[0040] The single tank processing capacity is 200 tons of molten steel tank. Due to the tight processing rhythm, the RH processing molten steel output accounts for 65% of the total output of two RH refining furnaces. The average service life of the RH immersion tube is 58.4 tanks. After the method for improving the service life of the immersion tube is implemented, the average service life of the RH immersion tube reaches 75 tanks. This shows that the present invention has a significant effect on improving the service life of the RH immersion tube. It can be promoted and implemented.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for increasing the service life of a RH immersion tube, characterized in that: The steps include: S1. Bake the prepared RH vacuum chamber twice to make the temperature of the vacuum chamber reach the production operating temperature; S2. After the temperature of the vacuum chamber reaches the production operating temperature, the immersion tube is sequentially immersed in molten steel, sprayed for the first time, and cured for the first time; S3, after the impregnated pipe obtained in step S2 is subjected to a second gunning repair and a second curing, it is put into normal production; S4. When the production is put into normal operation, the molten steel around the immersion pipe is treated: lime is added to increase the basicity of the top slag of the molten steel tank around the immersion pipe, making the top slag viscous; S5. After the molten steel treatment is completed, the wall thickness of the immersion tube is increased by moving the immersion tube at the molten steel liquid surface; S6. Dynamically monitor the wall thickness of the immersion pipe to ensure smooth production; In step S1, the RH vacuum chamber is first baked in the drying position, and after the production conditions are met, that is, the vacuum chamber temperature is ≥900°C, it is then hoisted to the standby position for the second baking, and the second baking ensures that the vacuum chamber temperature meets ≥1100°C; The step S2 comprises the following steps: S21. When the temperature in the vacuum chamber reaches 1100°C or above, move the vacuum chamber to the processing position, arrange a tank of molten steel to enter the processing position, insert the immersion tube into the molten steel for the first immersion, and pull it out after immersing for 1-2 minutes; S22, insert the immersion tube into the molten steel again for a second immersion, and pull it out after soaking for 1-2 minutes; S23, then move the vacuum chamber to the standby position, perform the first conventional gunning repair on the impregnated pipe, and after the gunning repair is completed, cure for 1.5 to 2 hours.

2. The method for increasing the service life of the RH immersion tube according to claim 1, characterized in that: In step S3, after the first curing is completed, the production is stopped after processing 1 to 2 tanks of molten steel, and the immersion pipe is subjected to a second conventional gunning repair. After the gunning repair is completed, the pipe is cured for 1.5 to 2 hours and then put into normal production.

3. The method for increasing the service life of the RH immersion tube according to claim 1, characterized in that: In step S4, when the production is normally started, lime is prepared in advance; during the normal production of RH, lime is evenly added to the molten steel around the immersion tube, and the total amount of lime added is controlled at 100 kg to increase the basicity of the top slag of the molten steel tank around the immersion tube and make the top slag viscous.

4. The method for increasing the service life of the RH immersion tube according to claim 1, characterized in that: In step S5, after the molten steel treatment is completed, the immersion tube is not immediately lifted off the molten steel surface. The RH equipment lifting system is used to repeatedly move the immersion tube up and down twice at the molten steel surface, so that the viscous slag on the top of the molten steel tank is hung on the outer wall of the immersion tube as much as possible to increase the wall thickness of the immersion tube.

5. The method for increasing the service life of the RH immersion tube according to claim 1, characterized in that: In step S6, the wall thickness of the immersion tube is dynamically monitored. When the distance between the outer wall of the immersion tube and the inner wall of the molten steel tank is ≤100 mm, the addition of lime is stopped, and the slag removal operation is performed on the wall of the immersion tube, or the conventional gunning amount is reduced to ensure smooth production.

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