Modified cooling element for use in a blast furnace, blast furnace provided therewith, and method for operating a blast furnace

Abstract

The invention relates to a modified cooling element for use in a blast furnace, a blast furnace equipped with such a cooling element, and a method for operating a blast furnace.

Description

[0001] The invention relates to a cooling element for use in a blast furnace, a blast furnace equipped therewith and a method for operating a blast furnace.

[0002] In the course of efforts to reduce CO2 emissions associated with steel production, it is known to additionally introduce hydrogen or a comparable reducing gas into the blast furnace via the so-called tuyeres, which replaces some of the coke normally introduced via the burden to reduce the iron ore (see, for example, DE 10 2021 202 698 A1). The injection of reducing gases above the tuyeres is also known (see, for example, DE 10 2015 014 234 A1).

[0003] Cooling elements, also called staves, for use in blast furnaces, along with cooling lines in the walls of a blast furnace, are essential for protecting the furnace from overheating during operation. The cooling elements are installed, among other things, above the tuyeres of the blast furnace, see, for example, WO 2022 / 058770 A1 and WO 2022 / 058773 A1.

[0004] The state-of-the-art systems for injecting reducing gases into blast furnaces essentially require the installation of additional components, so that these systems can be improved.

[0005] Based on this, the present invention was based on the object of providing an improvement and / or increase in efficiency for blowing a reducing gas into a blast furnace.

[0006] The invention is achieved by a cooling element having the features of claim 1, by a blast furnace equipped with at least one cooling element having the features of claim 6 and by a method for operating the blast furnace having the features of claim 7.

[0007] According to a first teaching, the invention relates to a cooling element for use in a blast furnace comprising a body in which at least one coolant channel is integrated, and a mounting base connected to the body or a mounting base formed integrally with the body, wherein the at least one integrated coolant channel in the region of the mounting base has an inlet point for introducing a coolant and an outlet point for discharging the introduced coolant, wherein at least one additional channel is integrated in the body, which has at least one inlet point in the region of the mounting base and at least one outlet point on the front side of the body.

[0008] The cooling elements (staves) in question here are mounted internally on the wall of the blast furnace and line the furnace shell toward the interior. The design and / or geometry of the cooling element can vary, with a body having at least one integrated coolant channel. The body can be integral with a mounting base, i.e., formed in one piece, or alternatively, the body can be connected to a mounting base. The mounting base serves as the connection to the wall.

[0009] The cooling element can have at least two or more separate coolant channels that are not connected to each other in the body, ensuring that even in the event of a malfunction in one coolant channel, cooling can be ensured via the remaining coolant channels. Alternatively, individual coolant channels can be temporarily (additionally) supplied with a cooling medium, for example, if temperature peaks need to be reduced.

[0010] The inlet and outlet points of each coolant channel preferably have connection points / nozzles. Water is preferably used as the coolant. The coolant (water) is introduced cold at the inlet point and flows along the coolant channel within the body, which has a temperature due to operation. As it flows through, the coolant is heated by heat exchange and is discharged as warm / hot coolant at the outlet point and thus at the end of the coolant channel. The heat contained in the warm / hot coolant is conducted either via heat exchangers or cooling towers to effect recooling. The recooled coolant is either made available again as cold coolant (closed cooling circuit) or, in the case of water as the coolant, is discharged to the environment. Corresponding cooling circuits in blast furnaces are also well known in the art.

[0011] The body of the cooling element is cast, for example, from copper, a copper alloy, or a comparable alloy with good thermal conductivity. Alternatively, the body can be made of a welded or assembled construction, see, for example, the online PDF from "stahl und eisen" (2016), issue 7, pages 35-41, published by Stahleisen GmbH, Düsseldorf, "New plate cooler for blast furnace A at Salzgitter Flachstahl." The production of cooling elements for use in blast furnaces is well known in the industry.

[0012] According to the invention, at least one additional channel is integrated into the body of the cooling element, which channel has at least one entry point in the region of the mounting base and at least one exit point on the front side of the solid body.

[0013] The additional channel is designed to introduce a reducing gas as a substitute reducing agent and thus directly or indirectly into the furnace interior in order to reduce the use of coke and thus reduce CO2 emissions during iron production in the blast furnace.

[0014] Another advantage compared to the state of the art is that the cooling element already provides integrated channels for cooling as well as for introducing a substitute reducing agent, thus eliminating the need for additional components. Furthermore, the cooling performance of the cooling element can be improved by allowing the (cold) reducing gas to absorb heat as it passes through the additional channel. At the same time, the heat absorption allows the reducing gas to be brought to a temperature that can have a beneficial effect on the process when the reducing gas is introduced into the furnace interior.

[0015] Hydrogen is preferably used as the reducing gas, which can preferably be obtained from a known electrolysis process, particularly preferably using renewable electricity. Other reducing gases that do not originate from fossil sources and / or do not use fossil fuels can also be used; see also "Measures for Decarbonizing the Blast Furnace Process by Using Hydrogen" by Can Yilmaz, dissertation, Clausthal University of Technology, 2018.

[0016] The front side refers to the side facing away from the mounting base and, when installed, towards the inside of the oven.

[0017] According to one embodiment, the at least one channel is designed as a straight through-channel. The straight through-channel enables, on the one hand, a simple construction of the cooling element and thus a direct passage of the reducing gas with minimal flow losses. If the channel / through-channel is sufficiently large and thus designed to accommodate and guide a blowing lance, on the other hand, a reducing gas indirectly passed through the blowing lance can, for example, reach deeper into the furnace interior by appropriately inserting and positioning the tip / nozzle of the blowing lance.

[0018] According to an alternative embodiment, several branch channels branch off from the at least one channel toward the front end, thus forming several outlet points from which the reducing gas passing through the cooling element can flow into the furnace interior on the front end. Preferably, the at least one channel has at least two inlet points. This means that one channel can be fed with reducing gas from at least two inlets.

[0019] A further teaching of the invention relates to a blast furnace comprising at least one cooling element according to the invention.

[0020] As already explained, known cooling elements are modified according to the invention so that their arrangement and assembly inside the blast furnace can also be implemented simply and in a known manner.

[0021] The area in which the cooling element according to the invention, or preferably several circumferential cooling elements, are attached to the interior of the blast furnace lining depends on the dimensions and design of the blast furnace. The cooling elements are preferably arranged in the area of ​​the reduction and / or carburizing zone of the blast furnace. The exact arrangement / positioning can be determined by a person skilled in the art and optionally verified by simulation. Ideally, however, an area above the "cohesive zone" can be selected, since from this point onward, viewed in the direction of flow in the blast furnace, the charge materials are in solid form. Furthermore, the existing cooling elements can also be replaced with cooling elements according to the invention as part of a relining of the blast furnace.

[0022] According to a further teaching, the invention relates to a method for operating a blast furnace which is fed from above with iron ore as iron carrier, coke as reducing agent and fuel and additives as slag formers and optionally flux, hot blast is blown in from below via tuyeres in order to extract pig iron and slag in the region of the melting zone of the blast furnace, wherein at least one reducing gas is additionally introduced to at least partially reduce the iron ore and is blown in above the tuyeres. Using a blast furnace equipped with at least one cooling element according to the invention, hydrogen is fed in as a reducing gas through the at least one additional channel.

[0023] Tapping is carried out in discrete sequences, i.e. pig iron and slag are drained from the blast furnace and the pig iron is placed in a portable collecting container that has been previously positioned at a predetermined collecting position. For example, a tap opening on the underside of the blast furnace can be opened for a suitably long period of time, from which pig iron and slag then flow out. Below the tap opening, for example, a distribution trough can be provided, which directs the flowing pig iron to a defined position, beneath which a collecting container designed as a so-called collecting ladle can be positioned. Collecting ladles can, for example, be provided as part of a ladle car known to those skilled in the art. The slag is also tapped accordingly, either in parallel or at a different time than the tapping of the pig iron, for example via a different / additional tap opening.

[0024] The use of "green" hydrogen as a reducing gas enables a reduction of coke and coal as "classic" reducing agents and thus contributes to a partial reduction of fossil feedstocks and to a reduction of CO2 emissions.

[0025] Depending on the design and dimensioning of the outlet points connected to the at least one additional channel, the throughput speed of the reducing gas can be influenced so that the higher it is set, the deeper it can be fed into the interior of the furnace, in particular without having to expect a high level of edge penetration of the reducing gas.

[0026] The throughput velocity can be between 10 and 800 m / s, in particular up to 500 m / s, preferably up to 300 m / s, more preferably up to 220 m / s. The determination can be made, for example, as a function of the throughput rate, i.e. reducing gas consumption in l / min, for example, and the cross-section, e.g. dimensioning of the channel and / or the exit points. A high gas velocity has the advantage of better penetration of the furnace interior via the furnace cross-section. Velocities close to the speed of sound can additionally have the advantage of strong momentum transfer, whereby adhesions in the furnace are broken up and the reduction in the furnace can be generally improved. The reducing gas can also be introduced in pulses. A continuous feed is by no means necessary.

[0027] For example, between 10 and 700 Nm 3 of reducing gas can be fed in per ton of pig iron produced, which can reduce coke and coal consumption by approximately 1 to 20% and thus also reduce CO 2 emissions.

[0028] In Figure 1Three schematic diagrams of different cooling elements (1) are shown. The cooling element (1) on the left-hand side in a plan view (top) and in a front view (bottom) is of conventional design. The cooling element (1), which is manufactured for use in a blast furnace (not shown), comprises a body (6) in which at least one coolant channel (2) is integrated, and a mounting base (3) connected to the body (6) or a mounting base (3) formed integrally with the body (6). The at least one integrated coolant channel (2) has, in the region of the mounting base (3), an inlet point (2.1) for introducing a coolant and an outlet point (2.2) for discharging the introduced coolant. The mounting base (3) is used, for example, to connect the cooling element (1) to a not-shown armoring of the blast furnace from the inside.

[0029] The principle sketches in the middle and right in Figure 1each show a modified cooling element (1) according to the invention. In contrast to the conventional cooling element (1) in the schematic diagram shown on the left, at least one additional channel (4, 5) is integrated into the body (6), which has at least one inlet point (4.1, 5.1) in the region of the mounting base (3) and at least one outlet point (4.2, 5.2) on the end face (7) of the body (6).

[0030] In a simple embodiment according to the invention, the at least one channel (4) is designed as a straight through-channel, see. Figure 1, middle illustration. The channel (4) can either be directly flowed through by a reducing gas (not shown) or alternatively, if the channel / through-channel is sufficiently large and thus designed to accommodate and guide a blowing lance, a reducing gas can be indirectly passed through the blowing lance (5), shown in dashed lines, into the interior of the furnace, so that the exit point (5.2), for example tip or nozzle, can also be varied in depth.

[0031] In a further embodiment according to the invention, several branch channels branch off from the at least one channel (4) in the direction of the front side (7) and thus form several outlet points (4.2) from which the reducing gas (not shown) can be fed into the interior of the furnace, see. Figure 1, right illustration. The at least one channel (4) can have at least two inlet points (4.1), the second inlet point being shown in dashed lines, in order to ensure, for example, the same outflow conditions from all outlet points (4.2).

[0032] In Figure 2 is a schematic diagram, shown in section (left) and in front view (right), of an alternative embodiment of a cooling element (1). In comparison to the embodiment in Figure 1 the cooling element (1) is narrower in its extension, thus small in its thickness and not as in Figure 1 , which would protrude into the interior of the furnace like a tongue when installed (not shown).

Claims

1. Cooling element (1) for use in a blast furnace comprising a body (6) in which at least one coolant channel (2) is integrated, and a mounting base (3) connected to the body (6) or a mounting base (3) formed integrally with the body (6), wherein the at least one integrated coolant channel (2) in the region of the mounting base (3) has an inlet point (2.1) for introducing a coolant and an outlet point (2.2) for discharging the introduced coolant, characterized in that at least one additional channel (4, 5) is integrated in the body (6), which has at least one input point (4.1, 5.1) in the region of the mounting base (3) and at least one output point (4.2, 5.2) on the front side (7) of the body (6).

2. Cooling element according to claim 1, wherein the at least one channel (4) is designed as a straight through-channel.

3. Cooling element according to claim 2, wherein the channel (4) is designed to receive and pass through a blowing lance (5).

4. Cooling element according to claim 1, wherein a plurality of branch channels branch off from the at least one channel (4) in the direction of the end face (7) and form a plurality of exit points (4.2).

5. Cooling element according to claim 4, wherein the at least one channel (4) has at least two inlet points (4.1).

6. Blast furnace comprising at least one cooling element (1) according to one of the preceding claims 1 to 4.

7. A method for operating a blast furnace which is fed from above with iron ore as iron carrier, coke as reducing agent and fuel and additives as slag formers and optionally flux, hot blast is blown in from below via tuyeres in order to extract pig iron and slag in the area of the melting zone of the blast furnace, wherein for at least partial reduction of the iron ore, at least one reducing gas is additionally introduced, which is blown in above the tuyeres, characterized in that a blast furnace according to claim 6 is used and hydrogen is fed through the at least one additional channel (4, 5) as a reducing gas.

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