Method for hot rolling heating furnace different step out of steel

Abstract

The present application relates to hot rolling strip rolling technology, especially to a kind of hot rolling heating furnace different step out of steel method, including scheme classification according to the number of heating furnace used according to conventional continuous casting slab and unconventional continuous casting slab;Different heating furnace stop charging time is determined according to class A scheme, class B scheme, class C scheme;Unconventional continuous casting slab charging time is determined;After unconventional continuous casting slab travels to heating furnace discharge end, furnace actual time can meet lower limit time in furnace;Hot rolling heating furnace different step out of steel control.The present application has the advantages that: under the condition that 4 heating furnaces are all put into production, unconventional continuous casting slab can be produced with conventional continuous casting slab in the same line, effectively meet the process requirement of long time heating for special products;By reasonably configuring the tapping proportion of conventional slab and unconventional slab, the continuous production rhythm of rolling line is maximized under the premise of guaranteeing the time of unconventional slab in furnace.

Description

Technical Field

[0001] This invention relates to hot-rolled strip rolling technology, and more particularly to a method for asynchronous tapping of steel from a hot-rolling heating furnace. Background Technology

[0002] The conventional production mode for hot rolling furnaces is synchronous tapping, meaning different furnaces tap steel in turn according to a fixed tapping rhythm. However, in actual production, due to significant differences in the required furnace time for different products, synchronous tapping cannot be achieved. For example, the 1780 hot rolling line has four walking beam furnaces with an effective furnace length of 40 meters. Under the normal synchronous tapping production rhythm, the slab spends 160-230 minutes in the furnace. However, when producing special products, the process requires the slab to spend over 300 minutes in the furnace, making synchronous tapping impossible. This patent designs a production organization method that accommodates different heating times in the furnace, aiming to reduce the impact on the rolling line efficiency while meeting the heating time requirements of special products. Summary of the Invention

[0003] The purpose of this invention is to provide a method for asynchronous tapping of steel from a hot rolling furnace, which solves the problem that existing synchronous tapping methods cannot simultaneously meet the large differences in furnace time between conventional and special products, leading to the inability to produce special products or a decrease in rolling line efficiency. By rationally configuring the number of furnaces used, scientifically setting the timing of steel loading and unloading, and adopting asynchronous tapping ratio control, the impact on rolling line production efficiency is minimized while meeting the long-term heating process requirements of special products, thus achieving a production balance between continuous casting and hot rolling.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for asynchronous tapping of steel from a hot-rolling heating furnace, comprising conventional and unconventional continuous casting slabs, with the following specific steps: S1. The schemes are classified according to the number of heating furnaces used for conventional and unconventional continuous casting slabs, as follows: When conventional continuous casting slabs use three heating furnaces and unconventional continuous casting slabs use one heating furnace, it is scheme A. When conventional continuous casting slabs use two heating furnaces and unconventional continuous casting slabs use one heating furnace, it is scheme B; When two heating furnaces are used for conventional continuous casting slabs and two heating furnaces are used for unconventional continuous casting slabs, it is a Class C scheme; S2. Determine the stop time for steel loading in different heating furnaces based on schemes A, B, and C; S3. Determine the timing of loading steel onto unconventional continuously cast slabs; S4. After the unconventional continuously cast slab reaches the furnace outlet, the actual time spent in the furnace should meet the lower limit of the furnace time requirement. S5. The control method for asynchronous steel tapping from the hot rolling furnace is as follows: When producing under the Type A scheme, for every steel produced from the unconventional continuous casting slab, the other three heating furnaces need to produce 2 to 3 more steel from the conventional continuous casting slabs. When producing under the B-type scheme, for every steel produced from the unconventional continuous casting slab, the other two heating furnaces need to produce 3 to 4 more steel from the conventional continuous casting slabs. When producing using the C-type scheme, for every steel slab produced from the unconventional continuous casting slabs in the two heating furnaces, 1 to 2 more steel slabs are needed from the conventional continuous casting slabs in the other two heating furnaces.

[0005] In step S2, the stopping time for steel loading in different heating furnaces is determined according to schemes A, B, and C, including: 1) The time required for all hot-rolled slabs to exit the air cavity is The formula is shown below: =η*k* + ①; in: η represents the total number of heating furnaces put into operation, in units of furnaces; k represents the full load of steel in a hot-rolling furnace, in units of blocks; This represents the average tapping rhythm of hot-rolled slabs, with a value range of 110~130s; This indicates the roller changing time, in minutes. 2) The time required for a continuously cast slab to fill a heating furnace is T, as shown in the formula below: T=k*L / τ②; in: τ represents the average casting speed in continuous casting, with a value of 1.2~1.5 m / min; k represents the full load of steel in a hot-rolling furnace, in units of blocks; L represents the length of the unconventional continuous casting slab, in meters; The stop time for steel loading varies depending on the heating furnace. The comparison with T determines: when When the temperature exceeds T, the hot rolling digestion rate is slower than the continuous casting billet supply rate. Therefore, it is necessary to stop the loading of non-standard slabs in advance to avoid accumulation. Specific details are as follows: For option A The time is 3.7~4.1h, the temperature is 2.8~3.2h, and the steel loading is stopped 1~1.5 hours before the continuous casting begins. For Scheme B, steel loading should be stopped 0 to 0.5 hours after continuous casting begins. For Scheme C, since the production of unconventional slabs in two furnaces requires the accumulation of raw materials, steel loading is stopped 2 to 2.5 hours after the start of continuous casting.

[0006] In step S3, to ensure that the full charge k of a hot rolling furnace meets the minimum time requirement in the furnace, The formula is shown below: Steel charging rhythm = minimum time in the furnace / The full load of a hot-rolling furnace is k③ Number of slabs in conventional continuous casting = (time in furnace at the lower limit) - Roller change time Average tapping rhythm of hot-rolled slabs ④.

[0007] The steel loading rhythm calculated by formula ③ is used to determine the steel loading interval for unconventional continuous casting slabs. The number of conventional continuous casting slabs calculated by Formula ④ is used to determine the timing for starting to load non-conventional continuous casting slabs. That is, when the planned amount of conventional slabs remaining on the rolling line reaches this value, non-conventional slabs will begin to be loaded.

[0008] Conventional continuous casting slabs refer to product slabs that require 160 to 230 minutes in a heating furnace; unconventional continuous casting slabs refer to product slabs that require more than 300 minutes in a heating furnace.

[0009] Compared with the prior art, the beneficial effects of the present invention are: 1. By adopting a non-synchronous steel tapping control method, it is possible to produce unconventional continuous casting slabs (with a furnace time requirement of more than 300 minutes) and conventional continuous casting slabs (with a furnace time of 160~230 minutes) on the same line when all four heating furnaces are in production, effectively meeting the process requirements of special products for long-term heating. 2. By rationally configuring the steel output ratio of conventional slabs and unconventional slabs (e.g., in Scheme A, for every 1 unconventional slab produced, 6 conventional slabs are produced), the continuous production rhythm of the rolling line is maintained to the maximum extent while ensuring the time of unconventional slabs in the furnace, thus avoiding a significant reduction in the speed or shutdown of the rolling line due to the production of special products. 3. Accurately calculate the hot-rolled slab exit time according to different schemes (Category A, Category B, and Category C). The timing of stopping the loading of non-standard slabs is determined by the time T when the heating furnace is filled by continuous casting, which effectively avoids the accumulation or interruption of materials between continuous casting billet supply and hot rolling digestion, ensuring the continuity and stability of the entire production process. 4. Based on the different product ratio requirements, this invention provides three optional heating furnace configuration schemes: A, B, and C. Enterprises can flexibly choose according to their actual order structure and production capacity requirements, thus achieving the optimal allocation of heating furnace resources and avoiding the situation of occupying all heating furnaces for the production of a small number of special products or causing a large number of empty furnaces waiting for materials. Detailed Implementation

[0010] The present invention will now be described in detail, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0011] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0012]

Example 1

[0013] Different heating times are illustrated using a conventional continuous casting slab with a furnace time of 160 minutes and an unconventional continuous casting slab with a furnace time of 300 minutes as examples. It should be noted that products other than unconventional continuous casting slabs (i.e., products with furnace times ranging from 160 to 230 minutes) are considered conventional continuous casting slabs. The definitions of 160 minutes and 300 minutes are based on the actual production process requirements of the 1780 hot rolling line: conventional products have a furnace time of 160 to 230 minutes, while special products require a furnace time of 300 minutes or more.

[0014] Step S1: Determine the number of heating furnaces to be used; The number of heating furnaces required for conventional and unconventional continuous casting slabs is determined, and three schemes are adopted, as shown below: Option A: Three heating furnaces are used for conventional continuous casting slabs, and one heating furnace is used for unconventional continuous casting slabs. Option B: Two heating furnaces are used for conventional continuous casting slabs, and one heating furnace is used for unconventional continuous casting slabs. Option C: Two heating furnaces are used for conventional continuous casting slabs, and two heating furnaces are used for unconventional continuous casting slabs.

[0015] The plan is shown in Table 1; Table 1 shows the usage plan for the heating furnace.

[0016] Step S2: Determine the stop time for steel loading in different heating furnaces; 1) The time required for all hot-rolled slabs to exit the air cavity is The formula is shown below: =η*28* +20min①; in: η represents the total number of heating furnaces put into operation, in units of furnaces; 28 represents the total amount of steel loaded into a hot-rolling furnace, expressed in blocks. This represents the average tapping rhythm of hot-rolled slabs, with a value range of 110~130s; 20min indicates the roller change time, in minutes.

[0017] 2) The time required for a continuously cast slab to fill a heating furnace is T, as shown in the formula below: T = 28 * 9.8 / τ ②; in: τ represents the average casting speed, which is 1.2~1.5 m / min, and is taken as 1.4 m / min below; 28 represents the total amount of steel loaded into a hot-rolling furnace, expressed in blocks. 9.8 indicates the length of the unconventional continuously cast slab, in meters (m).

[0018] Basis for determining the time to stop loading steel: Option A: T_hot-rolled = 4 * 28 * 115 s + 20 min = 3.9 h, T = 28 * 9.8 / 1.4 = 3.0 h. Because... >T, the hot rolling digestion rate is slower than the continuous casting billet supply rate, and steel loading needs to be stopped in advance to avoid accumulation. Based on the time difference (3.9h-3.0h=0.9h) and the production buffer requirements, it is determined that steel loading should be stopped 1 to 1.5 hours in advance.

[0019] Option B: Using only one unconventional heating furnace, the matching relationship between continuous casting billet supply and hot rolling digestion changes. Through production simulation calculations, stopping steel loading 0 to 0.5 hours after continuous casting begins can maintain production balance.

[0020] Solution C: Because the two furnaces produce unconventional continuous casting slabs, some raw materials need to be accumulated to ensure simultaneous continuous production in both furnaces. Therefore, steel loading is stopped 2 to 2.5 hours after the continuous casting begins.

[0021] The shutdown time of the heating furnace where the unconventional continuous casting slab is located is shown in Table 2; Table 2 shows the downtime of the heating furnace where the unconventional continuous casting slab is located.

[0022] Step S3: Determine the timing of loading steel onto the unconventional continuous casting slab; Based on the time required for all hot-rolled slabs to exit the air chamber in step 2. Based on the time T required to fill a heating furnace with continuously cast slabs, the following formula is used to ensure a minimum furnace time of 300 minutes for 28 slabs during production using schemes A, B, and C: Steel loading rhythm = 300 / 28 = 640s / piece; Number of slabs required for continuous casting = (300-20) min / 115s = 146 slabs; That is, 140 to 150 unconventional continuous casting slabs are reserved for rolling before steel is loaded.

[0023] Step 4: Verify furnace time; After executing steps 2 and 3, the actual time in the furnace when the unconventional continuous casting slab reaches the furnace outlet end can meet the target value of 300 minutes.

[0024] Step 5: Asynchronous steel tapping control method for heating furnace; Option A: If steel is produced synchronously in a conventional 115s heating furnace, the tapping rhythm for each unconventional continuous casting slab is 4 * 115s = 460s, which is less than the 640s charging rhythm in step 3. Because the tapping rhythm (460s) is faster than the charging rhythm (640s), the slab is pulled out of the furnace too quickly, preventing the subsequent slabs from accumulating enough time in the furnace to reach 300 minutes, resulting in insufficient furnace time. The time difference is 640 - 460 = 180s. Therefore, for every slab tapped from the unconventional continuous casting slab heating furnace, other heating furnaces need to tap 2-3 more slabs to maximize the rolling line's production efficiency.

[0025] Option B: Similarly, for every 1 piece of steel produced by the unconventional continuous casting slab heating furnace, other heating furnaces need to produce 3 to 4 more pieces of steel.

[0026] Option C: Similarly, for every steel produced by the two unconventional continuous casting slab heating furnaces, the other two heating furnaces need to produce 1 to 2 more steel pieces.

[0027] The principle of asynchronous steel tapping is shown in Table 3.

[0028] Table 3 shows the asynchronous steel tapping control methods.

[0029] Table 4 shows the production status and slab distribution of the heating furnace. The table below illustrates the slab type distribution and production rhythm on the furnace outlet and inlet sides under Scheme A.

[0030] P (Plain): indicates conventional continuous casting slab; T (Time-extended): indicates unconventional continuous casting slab (must meet the requirement of furnace time of more than 300 minutes).

[0031] This invention, by employing a asynchronous steel tapping control method, enables the simultaneous production of unconventional continuous casting slabs (requiring over 300 minutes in the furnace) and conventional continuous casting slabs (requiring 160-230 minutes in the furnace) on the same production line when all four heating furnaces are in operation. This effectively meets the process requirements of special products for long-duration heating. By rationally configuring the steel tapping ratio of conventional and unconventional slabs (e.g., in Scheme A, for every 1 unconventional slab tapped, 6 conventional slabs tapped), the continuous production rhythm of the rolling line is maintained to the maximum extent while ensuring the furnace time of unconventional slabs, avoiding significant speed reductions or shutdowns due to the production of special products. The hot-rolled slab tapping time is accurately calculated according to different schemes (Scheme A, B, and C). By determining the time T for continuously casting to fill the heating furnace, and accordingly deciding when to stop charging non-standard slabs, this invention effectively avoids the accumulation or interruption of material between continuous casting billet supply and hot rolling digestion, ensuring the continuity and stability of the entire production process. Based on different product proportion requirements, this invention provides three optional heating furnace configuration schemes (A, B, and C), allowing enterprises to flexibly choose according to their actual order structure and capacity requirements. This achieves optimal allocation of heating furnace resources, avoiding the situation where all heating furnaces are occupied for the production of a small number of special products, or resulting in a large number of empty furnaces waiting for material.

Claims

1. A method for asynchronous tapping of steel from a hot-rolling heating furnace, characterized in that, Including conventional and unconventional continuously cast slabs, the specific steps are as follows: S1. The schemes are classified according to the number of heating furnaces used for conventional and unconventional continuous casting slabs, as follows: When conventional continuous casting slabs use three heating furnaces and unconventional continuous casting slabs use one heating furnace, it is scheme A. When conventional continuous casting slabs use two heating furnaces and unconventional continuous casting slabs use one heating furnace, it is scheme B; When two heating furnaces are used for conventional continuous casting slabs and two heating furnaces are used for unconventional continuous casting slabs, it is a Class C scheme; S2. Determine the stop time for steel loading in different heating furnaces based on schemes A, B, and C; S3. Determine the timing of loading steel onto unconventional continuously cast slabs; S4. After the unconventional continuously cast slab reaches the furnace outlet, the actual time spent in the furnace should meet the lower limit of the furnace time requirement. S5. The control method for asynchronous steel tapping from the hot rolling furnace is as follows: When producing under the Type A scheme, for every steel produced from the unconventional continuous casting slab, the other three heating furnaces need to produce 2 to 3 more steel from the conventional continuous casting slabs. When producing under the B-type scheme, for every steel produced from the unconventional continuous casting slab, the other two heating furnaces need to produce 3 to 4 more steel from the conventional continuous casting slabs. When producing using the C-type scheme, for every steel slab produced from the unconventional continuous casting slabs in the two heating furnaces, 1 to 2 more steel slabs are needed from the conventional continuous casting slabs in the other two heating furnaces.

2. The method for asynchronous tapping of steel from a hot-rolling heating furnace according to claim 1, characterized in that, Step S2, which involves determining the stop charging time for different heating furnaces based on schemes A, B, and C, includes: 1) The time required for all hot-rolled slabs to exit the air cavity is The formula is shown below: =η*k* + ①; in: η represents the total number of heating furnaces put into operation, in units of furnaces; k represents the full load of steel in a hot-rolling furnace, in units of blocks; This represents the average tapping rhythm of hot-rolled slabs, with a value range of 110~130s; This indicates the roller changing time, in minutes. 2) The time required for a continuously cast slab to fill a heating furnace is T, as shown in the formula below: T=k*L / τ ②; in: τ represents the average casting speed in continuous casting, with a value of 1.2~1.5 m / min; k represents the full load of steel in a hot-rolling furnace, in units of blocks; L represents the length of the unconventional continuously cast slab, in meters (m).

3. The method for asynchronous tapping of steel from a hot-rolling heating furnace according to claim 1, characterized in that, In step S3, to ensure that the full charge k of a hot rolling furnace meets the minimum time requirement in the furnace, The formula is shown below: Steel charging rhythm = minimum time in the furnace / Full charge of steel (k) for one hot-rolling furnace ③ Number of slabs in conventional continuous casting = (time in furnace at the lower limit) - Roller change time Average tapping rhythm of hot-rolled slabs ④; The steel loading rhythm calculated by formula ③ is used to determine the steel loading interval for unconventional continuous casting slabs. The number of conventional continuous casting slabs calculated by Formula ④ is used to determine the timing for starting to load non-conventional continuous casting slabs. That is, when the planned amount of conventional slabs remaining on the rolling line reaches this value, non-conventional slabs will begin to be loaded.

4. The method for asynchronous tapping of steel from a hot-rolling heating furnace according to claim 1, characterized in that, The conventional continuous casting slab refers to a product slab that requires 160 to 230 minutes in the heating furnace; the unconventional continuous casting slab refers to a product slab that requires more than 300 minutes in the heating furnace.

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