Heating method for semi-finished metal products

Abstract

The present invention relates to a method for heating at least one semi-finished metal product to be further thinned by means of a heat exchanger device comprising a chamber for containing solid particles, a support means capable of supporting the semi-finished metal product, and a gas injector, the method comprising the steps of: i. injecting a gas into the chamber to form a fluidized bed; ii. inserting at least one hot semi-finished metal product such that said at least one hot semi-finished metal product can transfer heat to said fluidized bed; iii. inserting said at least one semi-finished metal product to be further thinned such that said fluidized bed can transfer heat to said at least one semi-finished metal product to be further thinned; iv. removing said at least one semi-finished metal product to be further thinned from said fluidized bed when the temperature of said at least one semi-finished metal product to be further thinned is less than 100° C. below the temperature of said fluidized bed; The method comprises the successive steps of:

Description

[Technical Field] 【0001】 The present invention relates to a method for heating a semi-finished metal product that is to be further thinned. [Background technology] 【0002】 In metal manufacturing, and more specifically in steel manufacturing, semi-finished products need to be heated before undergoing further forming processes. This is the case, for example, with steel slabs before hot rolling, which are heated to temperatures exceeding 1000°C in a furnace before hot rolling. 【0003】 However, such heating consumes a large amount of energy and leads to greenhouse gas emissions. Therefore, it is desirable to develop a heating method for semi-finished metal products that reduces greenhouse gas emissions. [Overview of the Initiative] [Problems that the invention aims to solve] 【0004】 The subject of this invention is to provide such a heating method. [Means for solving the problem] 【0005】 This subject is achieved by providing a method according to any one of claims 1 to 9. 【0006】 Other features and advantages will become apparent from the following description of the present invention. 【0007】 The present invention relates to a method for heating at least one semi-finished metal product to be further thinned by a heat exchange apparatus comprising a chamber for containing solid particles, a support means capable of supporting the semi-finished metal product, and a gas injector, i. A step of injecting gas into the chamber to form a fluidized bed, ii. A step of inserting at least one high-temperature metal product having a temperature of 400°C to 1000°C into the fluidized bed, wherein the temperature of the inserted at least one high-temperature metal product is higher than the temperature of the fluidized bed so that the at least one high-temperature metal product can transfer heat to the fluidized bed. iii. A step of inserting at least one semi-finished metal product to be further thinned, having a temperature of -20°C to 200°C, into the fluidized bed, wherein the temperature of the at least one semi-finished metal product to be further thinned is lower than the temperature of the fluidized bed, so that the fluidized bed can transfer heat to the at least one semi-finished metal product to be further thinned. iv. When the temperature of the at least one semi-finished metal product to be further thinned is less than 100°C lower than the temperature of the fluidized bed, the step of removing the at least one semi-finished metal product to be further thinned from the fluidized bed, Regarding a method that involves a series of steps. [Brief explanation of the drawing] 【0008】 [Figure 1A] An example of a chamber before gas is injected to form a fluidized bed according to the present invention is shown. [Figure 1B] An example of a chamber into which gas is injected to form a fluidized bed according to the present invention is shown. [Figure 2] An example of a chamber comprising a fluidized bed and three high-temperature metal products inserted into the fluidized bed is shown according to the present invention. [Figure 3] An example of a chamber according to the present invention is shown, comprising a fluidized bed, three high-temperature metal products inserted into the fluidized bed, and four semi-finished metal products to be further thinned. [Figure 4] The results of a simulation illustrating one embodiment of the method according to the present invention are shown. [Modes for carrying out the invention] 【0009】 As shown in Figure 1, the heat exchanger 1 comprises a chamber 2 for containing solid particles 3, a support capable of supporting at least one semi-finished steel product 4, and a gas injector 5. The chamber is preferably capable of receiving three or more semi-finished metal products simultaneously. 【0010】 The support means 6 is preferably capable of receiving three or more semi-finished metal products and at least one metal product. The support means may be a mesh basket. The support means may consist of several parts that are not necessarily connected to each other. For example, the support means may comprise several mesh baskets. Alternatively, the support means may be a columnar / trunk-shaped part having a guide inside the floor. 【0011】 The chamber may be a closed chamber having a closable opening that can transport semi-finished metal products, but it may also have an open ceiling or any configuration suitable for transporting semi-finished steel products. 【0012】 In step i of this method, as shown in Figure 1, gas 6 is injected into the chamber 2 to form a fluidized bed 7. In both Figure 1A and Figure 1B, the chamber 2 contains solid particles 3, but in Figure 1B, gas 6 is injected by a gas injector 5 to form the fluidized bed 7. The solid particles have a circulating direction. 【0013】 Preferably, the solid particles in the fluidized bed are in a foamed state. The gas rate applied to obtain the foamed state depends on several parameters that are easily controlled by those skilled in the art, such as the type of gas used, the size and density of the particles, or the dimensions of the chamber. 【0014】 In step ii, at least one high-temperature metal product is inserted into the interior of the fluidized bed. The at least one high-temperature metal product has a temperature of 400°C to 1000°C at the time of its insertion. The 400°C, which is the lowest temperature when the high-temperature metal product is inserted, is higher than the temperature of the fluidized bed. Thereby, it becomes possible for the at least one high-temperature metal product to transfer heat to the fluidized bed, that is, the particles constituting the fluidized bed. Due to the heat transfer, the temperature of the high-temperature metal product decreases. 【0015】 Preferably, the high-temperature metal product is a semi-finished metal product. For example, the at least one high-temperature metal product can be a slab or bloom that is cast and thus has a temperature of 400°C to 1000°C. 【0016】 Figure 2 embodies a chamber 2 including a fluidized bed 7 and three high-temperature metal products 8 inserted into the interior of the fluidized bed. 【0017】 In step iii, at least one semi-finished metal product to be further thinned is inserted into the interior of the fluidized bed. When inserted into the interior of the fluidized bed, the at least one semi-finished metal product to be further thinned has a temperature of -20°C to 200°C. 【0018】 The 200°C, which is the highest temperature when the high-temperature semi-finished metal product is inserted, is lower than the temperature of the fluidized bed. Therefore, thereby, it becomes possible for the at least one high-temperature metal product to transfer heat to the fluidized bed, that is, the particles constituting the fluidized bed. 【0019】 The semi-finished metal product to be further thinned can be taken out from, for example, a stock or a pile. 【0020】 Figure 3 embodies a chamber including a fluidized bed, three high-temperature metal products 8 inserted into the interior of the fluidized bed, and four semi-finished metal products 9 to be further thinned inside the fluidized bed. 【0021】 The at least one high-temperature metal product inserted in step ii and the at least one semi-finished metal product to be further thinned inserted in step iii are different products, as shown in Figure 3. 【0022】 Alternatively, at least one semi-finished metal product to be further thinned can be inserted into the fluidized bed before inserting at least one high-temperature metal product. Alternatively, the high-temperature metal product and the semi-finished metal product to be rolled can be inserted alternately into the fluidized bed. 【0023】 In step iv, at least one semi-finished metal product previously inserted into the fluidized bed to be further thinned is removed from the fluidized bed when its temperature is less than 100°C lower than the temperature of the fluidized bed. For example, if the temperature of the fluidized bed is 350°C, at least one semi-finished metal product previously inserted into the fluidized bed to be further thinned is removed from the fluidized bed when its temperature is between 251°C and 350°C. 【0024】 In steps ii, iii, and iv, the high-temperature metal product or the metal product to be further thinned may be transported to and from the inside and / or outside of the chamber by a rolling conveyor, or it may be placed inside the chamber by a pickup means such as a crane or any suitable pickup means. For example, the system disclosed in International Publication No. 2021064451 can be used as the pickup means. 【0025】 The method according to the present invention makes it possible to heat a semi-finished metal product that is to be further thinned using the heat of a high-temperature metal product. 【0026】 This method makes it possible to reduce the greenhouse gas emissions required to heat semi-finished metal products before rolling. 【0027】 Preferably, the metal product is made of steel. Preferably, the metal product may be made of different types of steel. 【0028】 Preferably, the metal product is a slab and / or bloom and / or billet and / or blank and / or ingot. 【0029】 Preferably, the semi-finished metal product is a slab with a thickness of 150 to 250 mm, a width of 600 to 1800 mm, and a length of 5000 to 15000 mm. Preferably, the semi-finished metal product is a slab weighing 3.5 tons to 50 tons. 【0030】 Preferably, the high-temperature metal product or the metal product to be further thinned includes a broad surface. More preferably, the broad surface is parallel to the circulation direction of the solid particles in the fluidized bed. 【0031】 Preferably, the gas injected into the chamber is heated. Preferably, the gas injected into the chamber has a temperature of over 200°C, more preferably over the temperature of the fluidized bed, and even more preferably over 400°C. 【0032】 More preferably, the gas is at least partially heated by a renewable energy source and / or recovered waste heat. The recovered waste heat may, for example, be derived from reused smoke. 【0033】 Preferably, the gas injected into the chamber is air. Alternatively, the gas injected by the gas injector is preferably an inert gas such as argon, helium, or nitrogen, or a mixture of gases. 【0034】 Preferably, the gas flow rate is 1-30 cm⁻¹. -1 It is injected at a certain speed. The ventilation power required in such a speed range is low, and therefore energy consumption is reduced. 【0035】 Advantageously, the chamber does not include a heat exchanger in contact with the fluidized bed, where a heat exchanger is understood as a device through which a transfer medium is circulated. Such a chamber is advantageous because the heating method does not require the use of energy other than that provided by the high-temperature semi-finished steel product and the gas to heat the fluidized bed and, therefore, the semi-finished steel product to be further thinned. This makes it possible to further reduce the greenhouse gas emissions required to heat the semi-finished metal product before rolling. 【0036】 Preferably, the dimensions of the solid particles are 40 to 500 μm. 【0037】 Preferably, the solid particles are 500-2000 J / kg. -1 .K -1 It has a heat capacity that includes [something]. 【0038】 Preferably, the bulk density of the solid particles is 1400 to 4000 kg.m³. -3 That is the case. 【0039】 Preferably, the solid particles are ceramic particles. Preferably, the solid particles are made from glass or any other solid material that is chemically stable up to 1000°C. For example, the solid particles may be made from SiC, olivine, steel slag, or alumina. 【0040】 Preferably, the solid particles are inert. This avoids any reaction with metal products. 【0041】 Preferably, in step ii, at least one high-temperature metal product has a temperature of 600°C to 1000°C, more preferably 800°C to 1000°C. 【0042】 Preferably, the at least one high-temperature metal product is removed from the fluidized bed when its temperature is equal to or greater than the fluidized bed temperature and 100°C higher than the fluidized bed temperature. More preferably, the at least one high-temperature metal product is removed from the fluidized bed when its temperature is equal to or greater than the fluidized bed temperature and 50°C higher than the fluidized bed temperature. For example, if the fluidized bed temperature is 315°C, the at least one high-temperature metal product is removed from the fluidized bed when its temperature is between 265°C and 315°C. 【0043】 Preferably, at least a second high-temperature metal product having a temperature of 400°C to 1000°C is inserted into the fluidized bed. 【0044】 The at least second high-temperature metal product is inserted between step ii and step iii and / or between step iii and step iv and / or after step iv. 【0045】 By removing the high-temperature products that have transferred heat to the fluidized bed, it becomes possible to replace them with higher-temperature semi-finished metal products, ensuring that there is at least one continuous heat source within the fluidized bed. 【0046】 Preferably, in step iii, at least one semi-finished metal product to be further thinned has a temperature of -20°C to 200°C, more preferably -20°C to 100°C. 【0047】 Preferably, the at least one semi-finished metal product to be further thinned is removed from the fluidized bed when the temperature of the semi-finished metal product to be further thinned is less than 50°C lower than the temperature of the fluidized bed. 【0048】 Preferably, at least a second semi-finished metal product to be further thinned, having a temperature of -20°C to 200°C, is inserted into the fluidized bed. 【0049】 The aforementioned at least second semi-finished metal product is inserted between step iii and step iv and / or after step iv. 【0050】 By removing the semi-finished metal product that has been heated and needs to be further thinned, it becomes possible to replace it with other semi-finished metal products that need to be heated. 【0051】 For example, product temperature can be measured using a contact thermocouple placed on the slab support and / or using a pyrometer during performance testing using thermocouples embedded in the slab, as well as during slab entry and exit and / or for the thermal profile of the reheating furnace. 【0052】 Preferably, the fluidized bed is maintained at a temperature of 100°C to 700°C. More preferably, the fluidized bed is maintained at a temperature of 250°C to 600°C. 【0053】 For example, the fluidized bed temperature may be measured using thermocouples placed at different points inside the fluidized bed, each having a small filter at its tip to avoid trapping particles, and / or the air leaving the fluidized bed may also be measured for comparison. 【0054】 Preferably, the method includes, after step iv, step v, in which the semi-finished metal product to be further thinned, which has been heated in a fluidized bed, is then heated to a temperature of 1100°C to 1400°C in a reheating furnace. 【0055】 More preferably, the method includes, after step v, step vi, in which the semi-finished metal product to be further thinned is hot-rolled. 【0056】 Alternatively, the method may use at least two heat exchangers, such that the high-temperature semi-finished metal product moves in one direction and the semi-finished metal product to be further thinned moves in the opposite direction. 【0057】 Simulations were performed to illustrate embodiments of the claimed method. 【0058】 In the simulation, the modeled fluidized bed has an average specific heat capacity of 0.6 kJ.kg -1 .K -1 and a mass of 200 tons. Further, in the simulation, the modeled hot metal product is a 25-ton hot steel slab having an average specific heat capacity of 0.8085 kJ.kg -1 .K -1 The modeled semi-finished metal product to be further thinned is a 25-ton steel slab to be thinned having an average specific heat capacity of 0.519 kJ.kg -1 .K -1 【0059】 As shown in FIG. 4, the simulation embodies an operating process in which the fluidized bed has a temperature of 310° C. when a hot steel slab having a temperature of 800° C. is inserted into the interior of the fluidized bed. This corresponds to step ii of the claimed method. In FIG. 4, the temperature of the fluidized bed is represented by a solid line, and the temperature of the hot steel slab is represented by a dashed line. 【0060】 Next, a first steel slab to be thinned having a temperature of 25° C. and a second steel slab to be thinned having a temperature of 20° C. are inserted into the interior of the fluidized bed. This corresponds to step iii of the claimed method. In FIG. 4, the temperature of the steel slab to be thinned is represented by a one-dot chain line and a two-dot chain line. 【0061】 Next, the first steel slab to be thinned is removed from the fluidized bed when its temperature is about 15° C. lower than the temperature of the bath. This corresponds to step iv of the claimed method.​

Claims

[Claim 1] A method for heating at least one semi-finished metal product to be further thinned by a heat exchange apparatus comprising a chamber for containing solid particles, a support means capable of supporting the semi-finished metal product, and a gas injector, i. A step of injecting gas into the chamber to form a fluidized bed, ii. A step of inserting at least one high-temperature metal product having a temperature of 400°C to 1000°C into the fluidized bed, wherein the temperature of the inserted at least one high-temperature metal product is higher than the temperature of the fluidized bed so that the at least one high-temperature metal product can transfer heat to the fluidized bed. iii. A step of inserting at least one semi-finished metal product to be further thinned, having a temperature of -20°C to 200°C, into the fluidized bed, wherein the temperature of the at least one semi-finished metal product to be further thinned is lower than the temperature of the fluidized bed, so that the fluidized bed can transfer heat to the at least one semi-finished metal product to be further thinned. iv. When the temperature of the at least one semi-finished metal product to be further thinned is less than 100°C lower than the temperature of the fluidized bed, the step of removing the at least one semi-finished metal product to be further thinned from the fluidized bed, This includes a series of steps, In the above method, at least one second semi-finished metal product to be further thinned, having a temperature of -20°C to 200°C, is inserted into the fluidized bed between step iii and step iv. method. [Claim 2] The method according to claim 1, wherein the high-temperature metal product and the semi-finished metal product are made of steel. [Claim 3] The method according to claim 1 or 2, wherein the high-temperature metal product and the semi-finished metal product are slabs and / or blooms and / or billets and / or blanks and / or ingots. [Claim 4] The method according to claim 1 or 2, wherein at least one high-temperature metal product is removed from the fluidized bed when the temperature of the high-temperature metal product is between the temperature of the fluidized bed and a temperature 100°C higher than the temperature of the fluidized bed. [Claim 5] The method according to claim 1 or 2, wherein at least a second high-temperature metal product having a temperature of 400°C to 1000°C is inserted into the fluidized bed between step ii and step iii and / or between step iii and step iv and / or after step iv. [Claim 6] The method according to claim 1 or 2, wherein the at least one semi-finished metal product to be further thinned is removed from the fluidized bed when the temperature of the semi-finished metal product to be further thinned is less than 50°C lower than the temperature of the fluidized bed. [Claim 7] The method according to claim 1 or 2, wherein at least one second semi-finished metal product to be further thinned, having a temperature of -20°C to 200°C, is inserted into the fluidized bed after step iv. [Claim 8] The method according to claim 1 or 2, wherein the method further comprises step v, after step iv, the semi-finished metal product to be further thinned, removed from the fluidized bed, is heated to a temperature of 1100°C to 1400°C in a reheating furnace. [Claim 9] The method according to claim 8, wherein the method further comprises, after step v, step vi, in which the semi-finished metal product to be further thinned is hot-rolled.

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