Method for reducing the time of the quick change tundish of a double flow large slab caster

Abstract

The application discloses a method for reducing the time of quick change of a double-flow large slab caster's tundish, which comprises the following steps: when the last furnace of the old tundish is in use, the speed of the remaining steel in the tundish is reduced, and a new tundish vehicle is driven to the vicinity of the old tundish; when the new tundish is in place, the old tundish is quickly centered by using a handheld operation box while the whole flow of the ladle is poured; the large ladle is poured, and when the tundish reaches the tonnage requirement after pouring, the tundish starts to pour; after the tundish is poured, the mold is checked, the pulling speed is gradually increased, and the slide plate surface is argon sealed. The application is used for the quick change of the tundish of the double-flow large slab caster, the steps are strictly followed by the team, the occurrence of accidents is reduced, the quick change time of the tundish is controlled within 5.5 minutes, the operation rate of the continuous casting is effectively improved, the production cost is reduced, and the efficiency of the caster is improved.

Description

Technical Field

[0001] This invention relates to the field of steel production technology, and in particular to a method for reducing the tundish change time in a twin-strand large slab continuous casting machine. Background Technology

[0002] With the development of steel industry technology, efficiency requirements are becoming increasingly stringent. Companies with high efficiency are more competitive, therefore steel companies are all striving to improve efficiency and enhance their competitiveness. In the continuous casting field, continuous casting time is the most important indicator for measuring the efficiency of a continuous casting machine. The bottleneck restricting continuous casting is that refractory materials cannot operate for extended periods and must be replaced after a certain time. Currently, the lifespan of a large slab tundish is generally around 15 hours. Therefore, to achieve continuous casting, rapid online tundish replacement is necessary to reduce the number of continuous casting machine downtimes, increase the continuous casting machine's operating rate and capacity, and simultaneously reduce billet scrap and energy consumption. Currently, the rapid tundish replacement time for double-strand large slabs is generally longer than that for single-strand tundishes. This is mainly because double tundishes have a larger tonnage and require more molten steel to meet the needs of double-strand casting, generally twice that of single-strand tundishes, thus requiring more time. Furthermore, tundish alignment before casting is more difficult with double tundishes, making rapid tundish replacement more challenging. Currently, the rapid tundish replacement time for large slabs with double tundishes is generally greater than 7 minutes. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0004] In view of the problems existing in the above and / or existing methods for reducing the tundish change time in a twin-strand large slab continuous casting machine, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is to provide a method for reducing the tundish change time in a twin-strand large slab continuous casting machine.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for reducing the tundish change time in a twin-strand large slab continuous casting machine, comprising,

[0007] The last heat in the old tundish should be slowed down by using the remaining steel from the tundish, and the new tundish car should be driven to a position near the old tundish.

[0008] Once the new intermediate tundish is in place, quickly direct the main tundish to start full-flow pouring while simultaneously using a handheld control box to quickly center the intermediate tundish.

[0009] The casting process begins after the intermediate ladle reaches the required tonnage.

[0010] After the tundish starts casting, check the crystallizer. After the check, gradually increase the casting speed and perform argon sealing on the slide plate.

[0011] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine according to the present invention, wherein: the speed reduction of the remaining steel in the last heat of the old tundish is carried out when the height of the remaining steel in the tundish is 600mm, and the speed is reduced from the original casting speed to 0.6m / min.

[0012] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine as described in this invention, wherein: the process of quickly directing the full-flow casting process of the ladle after the new tundish arrives is...

[0013] When the remaining molten steel level in the old tundish is 600mm, pull the new tundish to a position 2m away from the old tundish and stop, and reduce the pulling speed to 0.6m / min;

[0014] When the remaining steel in the old tundish is 400mm, reduce the pulling speed to 0.4m / min;

[0015] When the remaining steel in the old tundish is 350mm, stop casting, open the blind flange, remove the old tundish, and move the new tundish to the casting position;

[0016] When the new tundish is moved to the casting position, the casting speed is reduced to 0.1-0.2 m / min;

[0017] Stop the pumping speed when the liquid level in the crystallizer drops to about 400mm from the top opening.

[0018] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine as described in this invention, the process of quickly centering the tundish using a handheld control box involves quickly instructing the ladle to start full-flow casting after the new tundish is in place, while simultaneously using the handheld control box to quickly center the tundish. This operation allows the operator to observe the tundish position more closely, resulting in a shorter centering time. The tundish is lowered until the bottom of the nozzle is 50-80mm from the billet shell, at which point the process stops.

[0019] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine according to the present invention, the calculation method for starting casting after the tundish reaches the tonnage requirement is as follows:

[0020] After the ladle is poured, the tonnage requirement of the tundish is checked. If the tonnage is too low, the depth of molten steel in the tundish will be insufficient, which may cause slag entrapment and quality and production accidents. If the tonnage is too high, it will affect the ladle change time.

[0021] The required weight of the tundish is 30 tons. When the weight of the tundish reaches 30 tons, the tundish is opened for casting.

[0022] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine described in this invention, the crystallizer inspection is carried out after the tundish starts casting and the molten steel surface of the crystallizer is submerged in the side hole of the submerged nozzle. Protective slag is added to gradually raise the molten steel surface. The tundish change time should be strictly controlled and controlled at 40 to 80 seconds according to the tundish temperature.

[0023] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine as described in this invention, the following steps are taken: after the tundish is opened for casting, check whether there is cold steel in the crystallizer. After the casting speed is started, control the casting speed at 0.3 m / min and maintain it for 2 minutes. After the tundish change mark is removed from the crystallizer, slowly increase the speed at 0.03 m / min. Gradually increase the speed to 0.8 m / min, measure the thickness of the liquid slag layer, check and adjust the nozzle insertion depth and liquid level. If there are no abnormalities, increase the casting speed normally according to the temperature, and promptly open the stopper rod, the upper nozzle and the argon seal on the slide plate.

[0024] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine described in this invention, the argon sealing of the slide plate surface is to utilize the stirring effect of argon gas to remove slag and inclusions, so as to make the steel liquid composition and temperature uniform, reduce segregation, and improve the yield of deoxidizer and alloy materials.

[0025] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine according to the present invention, the protective slag is modified by adding carbon particles to the original material as a regulator of melting rate.

[0026] As a preferred embodiment of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine according to the present invention, wherein: driving the new tundish car to a position close to the old tundish means stopping the new tundish car at a position 2m away from the old tundish.

[0027] The beneficial effects of this invention are that it enables quick tundish changes on twin-strand large slab continuous casting machines. When the shift strictly follows the above steps, the occurrence of accidents is reduced, and the tundish change time is controlled within 5.5 minutes. At the same time, it effectively improves the continuous casting operation rate, reduces production costs, and improves the efficiency of the casting machine. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used 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 those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0029] Figure 1 This is a flowchart of the method for reducing the tundish change time in a twin-strand large slab continuous casting machine in Example 1.

[0030] Figure 2 The top and front views of the tundish are for the method of reducing the tundish change time in a twin-strand large slab continuous casting machine in Example 2. Detailed Implementation

[0031] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0034] Example 1

[0035] Reference Figure 1 This is the first embodiment of the present invention, which provides a method for reducing the tundish change time in a twin-strand large slab continuous casting machine. The method for reducing the tundish change time in a twin-strand large slab continuous casting machine includes...

[0036] Step 1: For the last heat in the old tundish, when the remaining steel height in the tundish reaches 600mm, reduce the casting speed to 0.6m / min. At the same time, move the new tundish car to a position 2m away from the old tundish and stop. When the remaining steel height in the tundish reaches 400mm, reduce the casting speed to 0.4m / min. When the liquid level in the tundish drops to 350mm to meet the requirements for stopping casting, install the blind flange and drive away the tundish car. Quickly move the new tundish car to the casting position and reduce the casting speed to 0.1-0.2m / min. When the liquid level in the crystallizer drops to a position about 400mm from the top, stop the casting speed.

[0037] Step 2: Once the new tundish is in place, quickly direct the main ladle to start full-flow pouring. At the same time, use a handheld control box to quickly center the tundish. This operation allows the operator to observe the tundish position more closely and the centering time is shorter. Lower the tundish and stop when the bottom of the sprue is 50-80mm away from the billet shell.

[0038] Step 3: Requirements for the tonnage of the tundish after the tundish starts casting. If the tonnage is too low, the depth of molten steel in the tundish will be insufficient, which may cause slag entrapment and quality and production accidents. If the tonnage is too high, it will affect the ladle change time. When the tundish tonnage reaches 30 tons, the tundish should be started casting.

[0039] Step 4: After the tundish starts casting, when the molten steel level in the crystallizer submerges the side hole of the immersion nozzle, add protective slag; gradually raise the molten steel level, and strictly control the time of changing ladle to seedling emergence, controlling it to 40-80 seconds according to the tundish temperature.

[0040] Table 1 Ladle Casting Data

[0041]

[0042] Step 5: After pouring from the tundish, check if there is cold steel in the crystallizer. After starting the casting speed, control it at 0.3 m / min and maintain it for 2 minutes. After the ladle joint appears in the crystallizer, slowly increase the speed at 0.03 m / min, gradually increasing it to 0.8 m / min. Measure the thickness of the liquid-slag layer, check and adjust the nozzle insertion depth and liquid level. If there are no abnormalities, increase the casting speed normally according to the temperature. Promptly open the stopper rod, the upper nozzle, and the argon seal on the slide plate. Figure 1 Here is its flowchart.

[0043] Example 2

[0044] Reference Figure 2 This is the second embodiment of the present invention, which differs from the first embodiment in that it further includes: In the previous embodiment, a method for reducing the quick tundish change time in a twin-strand large slab continuous casting machine includes

[0045] In 2022, a steel group adopted this method to reduce the tundish change time on a twin-strand large slab continuous casting machine.

[0046] Main technical parameters of the casting machine: Number of casting machines: two; Number of casting flows: 2x2 flows;

[0047] Casting machine types: straight arc type, small diameter closely spaced segmented rollers, continuous bending, continuous straightening;

[0048] Basic arc radius of the casting machine: R9 meters;

[0049] Billet specifications: 230mm thick for No. 1 continuous casting machine, 250mm thick for No. 2 continuous casting machine;

[0050] Width: 1 * continuous casting machine 900mm~1600mm

[0051] #2 Continuous Casting Machine: 1100mm~2150mm, Length: 8000mm~10500mm

[0052] The casting machine can process the following steel grades: galvanized steel, ultra-deep drawing steel, structural steel plate, low carbon steel plate, automotive structural steel plate, boiler and pressure vessel steel, general steel plate, welded pipe steel plate, weathering steel plate, and bridge steel plate. The casting machine's working speed is 0.9-1.5 meters per minute.

[0053] Maximum casting speed: 1.7 m / min for No. 1 continuous casting machine

[0054] #2 Continuous Casting Machine 1.5 m / min

[0055] Feeding bar speed: 4.8 m / min; metallurgical length: 34.5 m.

[0056] Statistics on quick tundish change times for dual-strand large slab continuous casting machines in the first two quarters of 2022:

[0057] Number of times the bag was changed (times) Average time per bag change Number of accidents Casting machine operating rate increased by %. Slab No. 1 machine 87 5.2 minutes 0 times 2.13 Slab No. 2 machine 92 5.1 minutes 0 times 2.72 total 179 5.1 minutes 0 times 2.54

[0058] Traditional double-strand slab tundish quick-change times are generally longer than single-strand tundish times. This is mainly because the double-strand tundish itself has a larger tonnage to meet the requirements of double-strand casting, thus requiring more molten steel, typically twice that of a single-strand tundish, resulting in a longer time. Furthermore, tundish alignment before casting is more difficult with double-strand tundish tundishes, making quick-change more challenging. Currently, the quick-change time for double-strand slab slabs generally exceeds 7 minutes. Figure 2 The top and front views are for when replacing the intermediate package.

[0059] 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 it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for reducing the tundish change time in a twin-strand large slab continuous casting machine, characterized by: The last heat in the old tundish should be slowed down by using the remaining steel from the tundish, and the new tundish car should be driven to a position near the old tundish. Once the new intermediate tundish is in place, quickly direct the main tundish to start full-flow pouring while simultaneously using a handheld control box to quickly center the intermediate tundish. The casting process begins after the intermediate ladle reaches the required tonnage. After the tundish starts casting, check the crystallizer. After the check, gradually increase the casting speed and perform argon sealing on the slide plate. The procedure for quickly directing the full-flow pouring of the ladle after the new tundish is in place is as follows: when the remaining molten steel level in the old tundish is 600mm, the new tundish is pulled to a position 2m away from the old tundish and the pulling speed is reduced to 0.6m / min. When the remaining steel in the old tundish is 400mm, reduce the pulling speed to 0.4m / min; When the remaining steel in the old tundish is 350mm, stop casting, open the blind flange, remove the old tundish, and move the new tundish to the casting position; When the new tundish is moved to the casting position, the casting speed is reduced to 0.1-0.2 m / min; Stop the pumping speed when the liquid level in the crystallizer drops to about 400mm from the top opening; The process of quickly centering the intermediate tundish using a handheld control box is as follows: when the new intermediate tundish is in place, quickly direct the main ladle to start full flow pouring and simultaneously use the handheld control box to quickly center the intermediate tundish. This operation allows the operator to observe the position of the intermediate tundish more closely and the centering time is shorter. The intermediate tundish is lowered and stopped when the bottom of the sprue is 50-80mm away from the billet shell. The calculation method for organizing the tundish to start casting after the tundish reaches the tonnage requirement is as follows: After the ladle starts casting, the tonnage requirement of the tundish is checked. If the tonnage is too low, the depth of molten steel in the tundish is insufficient, which can easily cause slag entrapment and quality and production accidents. If the tonnage is too high, it will affect the ladle change time. The required weight of the tundish is 30 tons. When the weight of the tundish reaches 30 tons, the tundish is opened for casting.

2. The method for reducing the tundish change time in a twin-strand large slab continuous casting machine as described in claim 1, characterized in that: The process of inspecting the crystallizer involves adding protective slag after the molten steel level in the tundish has submerged the side hole of the submerged nozzle, gradually raising the molten steel level. The time for changing ladle and the emergence of the crystallizer should be strictly controlled, ranging from 40 to 80 seconds depending on the tundish temperature.

3. The method for reducing the tundish change time in a twin-strand large slab continuous casting machine as described in claim 2, characterized in that: The process of gradually increasing the casting speed after inspection involves checking for cold steel in the crystallizer after the tundish is opened for casting. After starting the casting speed, the speed is controlled at 0.3 m / min and maintained for 2 minutes. After the tundish joint is removed from the crystallizer, the speed is slowly increased at 0.03 m / min. The speed is gradually increased to 0.8 m / min, and then the thickness of the liquid slag layer is measured. The insertion depth of the water nozzle and the liquid level are checked and adjusted. If there are no abnormalities, the casting speed is increased normally according to the temperature. The stopper rod, the upper water nozzle, and the argon seal on the slide plate are opened in time.

4. The method for reducing the tundish change time in a twin-strand large slab continuous casting machine as described in claim 3, characterized in that: The protective slag is made by adding carbon particles to the original material as a regulator of melting rate.

5. The method for reducing the tundish change time in a twin-strand large slab continuous casting machine as described in claim 4, characterized in that: The phrase "driving the new Zhongbao truck to a position close to the old Zhongbao truck" means driving the new Zhongbao truck to a position 2 meters away from the old Zhongbao truck and then stopping it.

Images