A method for recovering sensible heat of hot steel billet

Abstract

This invention provides a method for recovering and utilizing the sensible heat of hot steel billets, relating to the field of metallurgical steelmaking technology, and includes the following steps: S1, determining whether the newly produced billet can be directly charged into the furnace in the furnace charging operation area; if the newly produced billet can be directly charged into the furnace, proceed with the charging process; if the newly produced billet cannot be directly charged into the furnace, proceed to S2; S2, determining the off-line time of the newly produced billet; when the off-line time of the newly produced billet is greater than a fixed value, proceed to S3; S3, reading the billet number of the newly produced billet, selecting a cold billet of the same type as the newly produced billet as the billet to be preheated, and charging the billet to be preheated and the newly produced billet together into the furnace, performing the mixing operation in S4; S4, mixing operation. This invention provides a method for billets that can undergo enhanced cooling, which does not require intermediate conversion media, does not require excessive investment, and can more fully utilize the sensible heat of the cast billet directly.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy and steelmaking, and in particular to a method for recovering sensible heat of a hot steel billet. Background Art

[0002] Currently, most metallurgical enterprises use hot charging and hot delivery technology for continuous casting billets, resulting in a high utilization rate of the billet's sensible heat. Current operating data from heating furnaces in most steel mills indicates that the hot charging rate for billets above 500°C can reach 60-70%. Only a small number of short-process production processes have slightly higher hot charging rates, but there are also varying degrees of cold-charged billets. The main reasons for hot billets going offline include: inconsistencies in the continuous casting and rolling cycles (furnace changes, roll changes, maintenance, and other operations); cooling treatments for surface quality issues during the continuous casting process; and cold heating of alloy steels. Cooling of the hot billet wastes the sensible heat of the billet, lowering the charging temperature, increasing the energy consumption of the heating furnace, and causing environmental pollution. Therefore, it is necessary to recycle the sensible heat of the billet.

[0003] Existing sensible heat recovery solutions are shown below. Patent CN202111649133.8 discloses a highly efficient recovery and conversion system for the infrared radiation waste heat of high-temperature steel billets. A blackbody radiation receiver is placed directly above the high-temperature steel billet to recover the high-temperature infrared radiation energy of the steel billet and convert the steel billet radiation energy into electrical energy through a waveguide transmission membrane and photovoltaic cells. Patent CN201920838705.9 discloses a sludge drying system that utilizes the waste heat of steel billets. A waste heat recovery heat exchange pipe is placed on the steel billet conveying channel, and air is passed through the waste heat recovery heat exchange pipe. After the waste heat recovery heat exchange pipe absorbs the radiation energy of the hot steel billet, it transfers the heat to cold air through convection heat exchange, heating the cold air to above 200°C. The temperature of the steel billet after heat exchange is between 800-1000°C. Patent CN201911367257.X discloses a method for treating refined threaded steel bars using the residual heat of red-hot steel billets entering a pit, and the refined threaded steel bars obtained by heat treatment using this method. Two layers of threaded steel bars are vertically laid flat in an insulation pit, and a layer of red-hot steel billets is placed on top. After adding an insulation cover, they are naturally cooled to below 100°C. The process for treating refined threaded steel bars requires the temperature of the red-hot steel billets to be 500-600°C.

[0004] The above methods all utilize heat recovery equipment to convert the sensible heat of the steel billet into electrical energy through an intermediate medium or directly use it to heat objects. However, the above schemes have certain shortcomings. The blackbody radiation receiver of CN202111649133.8 is only arranged directly above the high-temperature steel billet, and the thermal efficiency of using thermal photovoltaic power generation is low, theoretically only about 40%; CN201920838705.9 uses the sludge drying system of the steel billet waste heat. The heat exchange medium flows in the pipe. The heat transfer coefficient between the steel billet and the heat exchange medium is reduced, and the cold air is heated to above 200°C. The temperature of the steel billet after heat exchange is 800-1000°C, and the recovery effect is reduced. CN201911367257.X uses the waste heat of the online cast red-hot steel billet to heat treat the rebar. Due to the restrictions of the heat treatment process requirements, the temperature requirements of the steel billet entering the slow cooling pit are relatively strict. It can only recycle the waste heat of the red-hot steel billet below 600°C. The sensible heat of the red-hot steel billet above 600°C cannot be recycled. Therefore, this method is easily restricted by the process requirements and there is some energy waste.

[0005] In summary, the sensible heat of the ingot must generally be converted through an intermediate medium. Heat consumption occurs after each heat conversion, resulting in low thermal efficiency. Some patented methods do not require an intermediate medium, but are limited by process requirements and can only recycle the waste heat of the red-hot billet below 600°C. The sensible heat of the billet is not fully recovered, resulting in some energy waste. Summary of the Invention

[0006] In view of this, in order to solve the problem of low sensible heat utilization rate of the billet during the heating process of steelmaking continuous casting and steel rolling due to the mismatch of production processes and the need for surface cleaning, the present invention proposes a method for recovering the sensible heat of hot steel billets. For billets that can be subjected to enhanced cooling, the high-temperature sensible heat of the hot billet is used to heat the cold billet. The hot billet is in direct contact with the hot and cold billets. By heat conduction, the hot billet is forced to cool, and the cold billet is heated to the hot charging level, thereby fully recovering and utilizing the waste heat of the billet.

[0007] The technical means adopted in the present invention are as follows:

[0008] A method for recovering sensible heat of a hot steel billet comprises the following steps:

[0009] S1. During the continuous casting process, after the casting machine produces a new billet, the serial number signal of the new billet is sent to the heating furnace steel loading operation area. The heating furnace steel loading operation area determines whether the new billet can be directly loaded into the furnace. If the new billet can be directly loaded into the furnace, the furnace loading process is directly carried out; if the new billet cannot be directly loaded into the furnace, S2 is executed.

[0010] S2. Determine the off-line time of the newly produced billet. When the off-line time of the newly produced billet is less than a fixed value, the newly produced billet is directly taken off the line and mixed with the hot billets into the furnace. When the off-line time of the newly produced billet is greater than the fixed value, execute S3.

[0011] S3. Read the billet number of the newly produced billet, select the cold billet of the same type as the newly produced billet as the billet to be preheated, load the billet to be preheated and the newly produced billet into the furnace together, and perform the mixed stacking operation of S4;

[0012] S4, Mixing operation:

[0013] S41, alternately stacking a plurality of newly produced blanks and blanks to be preheated at a first stacking position in a material yard to form a first blank pile, wherein the bottommost layer of blanks and the topmost layer of blanks in the first blank pile are both newly produced blanks;

[0014] S42, lifting the third to the top layer of the first billet pile and moving them to the adjacent second stockyard stack to form a second billet pile;

[0015] S43, sending the second layer of blanks of the first blank pile to the loading roller for loading into the furnace;

[0016] S44, stacking a layer of preheated billets and newly produced billets on top of the second billet pile;

[0017] S45, lifting the third to the top layer of the second billet pile and moving them to the first billet pile, and sending the second layer of the second billet pile to the loading roller for loading into the furnace;

[0018] S46, stacking a layer of preheated billets and newly produced billets on top of the first billet pile;

[0019] S47. Repeat the above process until the furnace loading is completed.

[0020] Furthermore, the fixed time in S2 is 20 minutes.

[0021] Furthermore, S3 also includes: judging the thickness of the newly produced blanks, when the thickness of the newly produced blanks is within the first thickness range, stacking every two pieces; when the thickness of the newly produced blanks is within the second thickness range, stacking every piece; the maximum value of the first thickness range is less than the minimum value of the second thickness range.

[0022] Furthermore, the first thickness range is 100 mm-135 mm, and the second thickness range is 135 mm-250 mm.

[0023] Furthermore, in S4, the first crane and the second crane are used to carry out the work of transporting the blank;

[0024] In S41, the second crane is used to stack the newly produced billets, and the first crane is used to stack the billets to be preheated;

[0025] In S42, a second crane is used to transfer the third layer to the top layer of the first billet stack;

[0026] In S43, a second crane is used to transfer the second layer of billets of the first billet stack;

[0027] In S44, the first crane is used to stack the preheated billets on the top of the second billet pile, and the second crane is used to stack the newly produced billets on the top of the second billet pile;

[0028] In S45, the first crane is used to transfer the third layer to the uppermost layer of the second billet pile.

[0029] The present invention also provides a storage medium, which includes a stored program, wherein when the program is run, any of the above-mentioned methods for recovering sensible heat of hot steel billets is executed.

[0030] The present invention also provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes any of the above-mentioned methods for recovering sensible heat of hot steel billets through the operation of the computer program.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] This invention solves the problem of sensible heat loss of continuous casting billets during the steelmaking and continuous casting-rolling heating furnace production process due to production connection and billet surface cleaning. By stacking hot and cold billets together, the sensible heat of the hot billets is directly transferred to the cold billets, minimizing investment costs. This reduces billet heat loss and improves the hot charging effect.

[0033] By heating the cold blanks through the present invention, for slabs with a thickness of 120-250 mm, a length of 5000-12000 mm, a furnace exit time of 10-30 min, and a line temperature of 800-1100°C, field experiments have verified that the furnace entry temperature can be increased by 160-350°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative labor.

[0035] Figure 1It is a process flow chart of the present invention.

[0036] Figure 2 This is a diagram of the sensible heat recovery method of the present invention.

[0037] Figure 3 It is a schematic diagram of the stacking operation of the present invention.

[0038] In the figure: 1, first layer of blanks; 2, second layer of blanks; 3, third layer of blanks; 4, fourth layer of blanks; 5, fifth layer of blanks; 6, sixth layer of blanks; 7, seventh layer of blanks; 8, eighth layer of blanks; 9, ninth layer of blanks; I, first material yard stack; II, second material yard stack. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the solutions of the present invention, 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 embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0041] The present invention provides a method for recovering sensible heat of a hot steel billet, comprising the following steps:

[0042] S1. During the continuous casting process, after the casting machine produces a new billet, the serial number signal of the new billet is sent to the heating furnace steel loading operation area. The heating furnace steel loading operation area determines whether the new billet can be directly loaded into the furnace. If the new billet can be directly loaded into the furnace, the furnace loading process is directly carried out; if the new billet cannot be directly loaded into the furnace, S2 is executed.

[0043] S2. Determine the off-line time of the newly produced billet. When the off-line time of the newly produced billet is less than the fixed value, the newly produced billet is directly taken off the line and mixed with the hot billets into the furnace; when the off-line time of the newly produced billet is greater than the fixed value, execute S3; the fixed time is 20 minutes.

[0044] S3. Read the billet number of the newly produced billet, select a cold billet of the same type as the newly produced billet as the billet to be preheated, load the preheated billet and the newly produced billet into the furnace together, and perform the mixed stacking operation in S4. Determine the thickness of the newly produced billet. When the thickness of the newly produced billet is within the first thickness range, stack two billets. When the thickness of the newly produced billet is within the second thickness range, stack each billet. The maximum value of the first thickness range is less than the minimum value of the second thickness range. The first thickness range is 100mm-135mm, and the second thickness range is 135mm-250mm.

[0045] S4, Mixing operation:

[0046] S41, alternately stacking a plurality of newly produced blanks and blanks to be preheated at a first stacking position in a material yard to form a first blank pile, wherein the bottommost layer of blanks and the topmost layer of blanks in the first blank pile are both newly produced blanks;

[0047] S42, lifting the third to the top layer of the first billet pile and moving them to the adjacent second stockyard stack to form a second billet pile;

[0048] S43, sending the second layer of blanks of the first blank pile to the loading roller for loading into the furnace;

[0049] S44, stacking a layer of preheated billets and newly produced billets on top of the second billet pile;

[0050] S45, lifting the third to the top layer of the second billet pile and moving them to the first billet pile, and sending the second layer of the second billet pile to the loading roller for loading into the furnace;

[0051] S46, stacking a layer of preheated billets and newly produced billets on top of the first billet pile;

[0052] S47. Repeat the above process until the furnace loading is completed.

[0053] Combine Figure 1 The present invention proposes a billet removal process. During the continuous casting process, after the casting machine produces a billet, the billet sequence signal is transmitted to the heating furnace steel charging operation area. This determines whether the billet can be directly charged into the furnace. If hot charging is possible, it is directly loaded into the furnace. If hot charging is not possible and the billet needs to be removed from the furnace, the removal time is determined. If the removal time is less than 20 minutes, the billet is directly removed from the furnace and mixed with hot billets into the furnace. If the removal time exceeds 20 minutes, the mixed stacking operation mode is activated.

[0054] Combine Figure 2 The present invention proposes a mixed stacking operation mode process. After receiving the mixed stacking operation mode, the billet number is received, and two cold billets of the same type are selected for loading into the furnace. The thickness of the billets is determined. For billets 100mm-135mm thick, two billets can be stacked together to ensure minimal deformation of the billets. For billets 135mm-250mm thick, only one billet can be stacked. Cold billets of the same type are selected as the billets to be preheated, and the mixed stacking operation is performed until the cold loading is completed.

[0055] Combine Figure 2 and Figure 3 The present invention proposes a method for effectively utilizing the sensible heat of steel billets. The specific implementation process is as follows. After the hot continuous casting is offline due to the production process not matching the hot charging and the surface quality problem occurs and needs to be cooled and cleaned, during the production and loading process again, the first layer of billets 1 (hot billets offline) are placed at the stack position I of the first material yard by the second crane, and the second layer of billets 2 (cold billets to be preheated) are placed on the first layer of billets 1 (hot billets offline) by the first crane, and the third layer of billets 3 (hot billets offline) are placed on the second layer of billets 2 (cold billets to be preheated), and so on until the top is the fifth layer of billets 5 (hot billets offline). The third layer of billets 3 (hot billets off the line), the fourth layer of billets 4 (cold billets to be preheated), and the fifth layer of billets 5 (hot billets off the line) are simultaneously lifted by the second crane and moved to the adjacent second material yard stack II, and the heated second layer of billets 2 are delivered to the loading roller conveyor continuously. At the same time, the first crane places the sixth layer of billets 6 (cold billets to be preheated) on the fifth layer of billets 5 (hot billets off the line) in the second material yard stack II. After loading, the second crane directly brings back the seventh layer of billets 7 (hot billets off the line) and places it on the sixth layer of billets 6 (cold billets to be preheated). The first crane is used to place the fifth layer of blanks 5 (hot blanks off the line), the sixth layer of blanks 6 (cold blanks to be preheated), and the seventh layer of blanks 7 (hot blanks off the line) on the first layer of blanks 1 (hot blanks off the line) in the stack I of the first material yard at the same time, so that the heated fourth layer of blanks 4 are loaded into the furnace, and the eighth layer of blanks 8 (cold blanks to be preheated) and the ninth layer of blanks 9 (hot blanks off the line) are stacked in sequence above the seventh layer of blanks 7 (hot blanks off the line); the alternating heating and furnace loading process of the cold blanks is completed in sequence.

[0056] By heating the cold blanks through the present invention, for slabs with a thickness of 120-250 mm, a length of 5000-12000 mm, a furnace exit time of 10-30 min, and a line temperature of 800-1100°C, field experiments have verified that the furnace entry temperature can be increased by 160-350°C.

[0057] The present invention also provides a storage medium, which includes a stored program, wherein when the program is run, the above-mentioned method for recovering sensible heat of hot steel billets is executed.

[0058] The present invention also provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the above-mentioned method for recovering sensible heat of hot steel billets through the execution of the computer program.

[0059] Example 1

[0060] Taking a slab with a thickness of 135 mm and a single weight of 10,530 kg as an example, the present invention proposes a method for effectively utilizing the sensible heat of the steel billet. The specific implementation process is as follows. After the hot continuous casting is offline due to the production process not matching the hot charging and the occurrence of surface quality problems requiring cooling and cleaning, during the production and loading process again, the first layer of billets 1 (1000°C) are placed at the stack position I of the first material yard by the second crane, and the second layer of billets 2 (temperature of 20°C) are placed on the first layer of billets 1 by the first crane, and the third layer of billets 3 are placed on the second layer of billets 2, and so on until the fifth layer of billets 5 is at the top. According to the field experimental records, by alternately stacking the 1000℃ continuous casting hot billets off the line with the cold billets (temperature of 20℃) that need to be loaded into the furnace after processing, the average temperature of the second layer of billets 2 can be preheated to 250℃ after 10 minutes; the average temperature of the second layer of billets 2 can be increased to 370℃ after 20 minutes; the average temperature of the second layer of billets 2 can be increased to 430℃ after 30 minutes; and the second layer of billets 2 reaches the highest temperature, which is increased to 535℃ after 60 minutes.

[0061] Example 2

[0062] Taking a thick slab with a thickness of 250 mm and a single weight of 17,268 kg as an example, the present invention proposes a method for effectively utilizing the sensible heat of the steel slab. The specific implementation process is as follows. After the hot continuous casting is offline due to the production process not matching the hot charging and the occurrence of surface quality problems requiring cooling and cleaning, during the production and loading process again, the first layer of billets 1 (1000°C) offline are placed at the stack position I of the first material yard by the second crane, and the second layer of billets 2 (temperature of 20°C) are placed on the first layer of billets 1 by the first crane, and the third layer of billets 3 are placed on the second layer of billets 2, and so on until the fifth layer of billets 5 is at the top. According to the field experimental records, by alternately stacking the 1000℃ continuous casting hot billets off the line with the cold billets (temperature of 20℃) that need to be loaded into the furnace after processing, the average temperature of the second layer of billets 2 can be preheated to 220℃ after 10 minutes; the average temperature of the second layer of billets 2 can be increased to 340℃ after 20 minutes; the average temperature of the second layer of billets 2 can be increased to 400℃ after 30 minutes; and the second layer of billets 2 reaches the highest temperature, which is increased to 480℃, after 80 minutes.

[0063] Placing the blank in the insulation pit will increase the preheating temperature by more than 15%.

[0064] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0065] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0066] 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 above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above 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 recovering sensible heat of hot steel billets, characterized in that: The steps include: S1. During the continuous casting process, after the casting machine produces a new billet, the serial number signal of the new billet is sent to the heating furnace steel loading operation area, and the heating furnace steel loading operation area determines whether the new billet can be directly loaded into the furnace; if the new billet can be directly loaded into the furnace, the furnace loading process is directly performed; If the newly produced billet cannot be directly loaded into the furnace, execute S2; S2. Determine the off-line time of the newly produced billet. When the off-line time of the newly produced billet is less than a fixed value, the newly produced billet is directly off-line and mixed with the hot billet into the furnace; When the offline time of the newly produced blank is greater than the fixed value, S3 is executed; the fixed value is 20 minutes; S3, read the billet number of the newly produced billet, select the cold billet of the same type as the newly produced billet as the billet to be preheated, load the billet to be preheated and the newly produced billet into the furnace together, and perform the stacking operation of S4; The thickness of the newly produced blanks is judged, and when the thickness of the newly produced blanks is within a first thickness range, two pieces are stacked; When the thickness of the newly produced blank is in the second thickness range, each piece is stacked; the maximum value of the first thickness range is less than the minimum value of the second thickness range; the first thickness range is 100mm-135mm, and the second thickness range is 135mm-250mm; S4, mixed stacking operation, using the first crane and the second crane to carry out the work of handling the blanks: S41, alternately stacking a number of newly produced blanks and blanks to be preheated at a first material yard stack to form a first blank pile, wherein the bottom layer and the top layer of the first blank pile are both newly produced blanks; using a second crane to stack the newly produced blanks, and using a first crane to stack the blanks to be preheated; S42, lifting the third to the top layer of the first billet pile and moving them to the adjacent second stockyard stack to form a second billet pile; using a second crane to transfer the third to the top layer of the first billet pile; S43, sending the second layer of the first billet pile to the loading roller for loading into the furnace; using the second crane to transfer the second layer of the first billet pile; S44, stacking a layer of billet to be preheated and newly produced billet on the top of the second billet pile in sequence; using a first crane to stack the billet to be preheated on the top of the second billet pile, and using a second crane to stack the newly produced billet on the top of the second billet pile; S45, lifting the third to the top layer of the second billet pile and moving them to the first billet pile, sending the second layer of the billet of the second billet pile to the loading roller for loading into the furnace; using the first crane to transfer the third to the top layer of the second billet pile; S46, stacking a layer of preheated billets and newly produced billets in sequence on top of the first billet pile; S47, repeat the above process until the furnace loading is completed.

2. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is run, the method for recovering sensible heat of a hot steel billet in claim 1 is executed.

3. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the method for recovering sensible heat of hot steel billets in claim 1 through the operation of the computer program.

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