Methods for repairing the refractory walls of a furnace

Abstract

The present invention relates to a method for repairing a refractory wall (2) of a furnace (1) by replacing at least one wall section (3) thereof, the method comprising: (a) demolishing the wall section (3); (b) installing in situ an outer form (4) defining a new wall section (3) and installing an inner form (5) defining a new flue in the new wall section (3); (c) casting a castable refractory material in the volume defined by the outer form (4) and the inner form (5) and allowing the material to harden; (d) removing the outer form; the invention also relates to a wall section for a furnace and to the furnace.

Description

Technical Field

[0001] The present invention relates to a method for repairing the refractory wall of a furnace. The present invention also relates to a wall portion for a furnace and a furnace.

Background Art

[0002] Furnaces for heating materials for various purposes are widely known. Furnaces can be constructed in various forms, but typically include elements such as a floor (or corbel), a roof, and walls extending therebetween, thereby forming a heating chamber for the material to be heated inside. The floor, roof, or wall often has channels for transporting high-temperature gases, often referred to as flue passages, thereby heating the chamber.

[0003] Each element is typically constructed from ceramic bricks, which are assembled to define internal flue channels, vent passages, and other passages that extend vertically and / or horizontally within elements such as the heating wall.

[0004] Due to the severe temperature cycling environment and furnace operating practices, some or all of the furnace elements may require repair and / or reconstruction during the furnace's service life.

[0005] It is known that each section of a furnace can be repaired by pouring refractory material between a formwork defining the chamber and an inner formwork defining the flue. The chamber formwork can then be easily removed, but the inner formwork is more complex to remove. One method of removal is to install a wooden inner formwork and then remove it later by burning off the wood of the formwork when the oven is heated to its operating temperature. The challenges associated with using wood are that it is time-consuming to fabricate the formwork, especially when complex shapes are required to define the flue. Furthermore, wood is not very stable in shape; that is, it shrinks when subjected to the pressure of the material being poured into it, which complicates the formwork design process. Therefore, when repairing the vertical wall sections of a furnace, the wall sections are often divided into sections so that the next section forms on top of the others after hardening, which makes the repair process very time-consuming.

[0006] Another method involves using an inner formwork made of iron (Fe). When iron is exposed to oxidizing gases and heat from the furnace, it corrodes, causing delamination and melting. When iron melts, it also negatively affects the melting point of the surrounding refractory ceramic material. Therefore, the iron formwork must be removed before the furnace is operated. Thus, removal is an expensive process and limits the complexity of the flue shapes that can be formed. Furthermore, when repairing the vertical wall sections of the furnace, the wall sections are often divided into sections so that the iron formwork can be removed by machining. [Overview of the project] [Problems that the invention aims to solve]

[0007] Considering the above, the first object of the present invention is to provide an improved method for repairing the refractory walls of a furnace, overcoming at least some of the problems of the prior art. A further object of the present invention is to provide an improved wall portion for a furnace. Yet another object is to provide an improved furnace. [Means for solving the problem]

[0008] According to a first aspect of the present invention, the first object is achieved by a method comprising the steps described in claim 1. Thus, a method is provided for repairing the refractory wall of a furnace by replacing at least one portion of the wall. This method is: (a) demolishing the wall section; (b) Install an outer formwork on site to define the new wall section, and install an inner formwork within the new wall section to define the new flue; (c) To enable the casting of castable fire-resistant material into the volume defined by the outer and inner formwork, and for the material to harden; (d) Removing the outer formwork; The inner formwork is made from heat-resistant metal material.

[0009] The method disclosed herein provides an improved method for repairing the refractory wall of a furnace, wherein an internal formwork defining a new flue is fabricated from a heat-resistant metal material. Specifically, by providing an internal formwork made of a heat-resistant metal material, the formwork can be left inside the wall section without needing to be removed before operating the furnace, thereby simplifying the repair process and making it more cost-effective.

[0010] Furthermore, by fabricating the inner formwork from metal materials, an airtight flue can be formed. The metal materials can be easily customized using conventional metalworking techniques to create more complex shapes that suit the specific furnace to be repaired, thus improving the adaptability of the repair method.

[0011] For the purposes of this invention, it is assumed that a portion of a wall needs to be repaired, but it will be understood that the repair processes described herein can be applied to situations where an entire wall, a roof and / or floor / corbel area, or some portion thereof needs to be replaced. Accordingly, the reference to “wall portion” is intended to encompass both vertical walls and horizontal roof and floor / corbel portions.

[0012] The term "furnace" refers to any furnace, such as one used to produce coke or glass, or one used to heat materials internally for various other purposes. Other terms related to "furnace" may be "oven" or "kiln." While the term "furnace" is used below to describe a wall that is scheduled for repair, it can also be applied to other forms of heating devices, such as boilers, melting furnaces / blast furnaces, stoves, or fireplaces, to give a few non-exclusive examples.

[0013] A furnace often includes a chamber for heating the material, and the chamber is often defined by walls, a floor, and a ceiling for the furnace. Some furnaces have multiple chambers, each separated from the others by walls. Some types of furnaces often have several chambers. A typical coke oven installation may involve, for example, arranging 30 to over 100 individual coking chambers or ovens side by side, each chamber being 3 to 7 meters high, typically 14 meters or more in length, and about 1 meter in width.

[0014] Installing the outer formwork that defines the new wall section "on-site" means "inside the existing furnace." For example, if the wall is an outer wall facing outwards from the furnace, it can also mean "in the existing furnace."

[0015] A flue is a well-known term in the field of furnaces. A flue is a channel in the furnace wall that transports heating gases to heat the furnace. Flues can also be incorporated into the floor and / or ceiling of the furnace.

[0016] When castable fire-resistant material is poured into a volume defined by the outer and inner formwork, it should be understood as a volume substantially limited by the inner and outer formwork. Naturally, the remaining wall outside the section of the wall to be repaired also defines the actual volume into which the castable fire-resistant material will be poured.

[0017] A heat-resistant metal material refers to a metal material that can be exposed to high temperatures while maintaining its material properties. High temperature means approximately 1000°C or higher. Preferably, the heat-resistant metal material does not generate gas and does not affect the surrounding castable refractory material even when heated to over 1000°C.

[0018] In some cases, heat-resistant metal materials maintain their morphological stability when heated to furnace operating temperatures, such as between 1000°C and 1200°C. Morphological stability means that the material retains its shape. During operation of some types of furnaces, such as coke ovens, temperatures can rise to 1200°C. At such high temperatures, many materials are prone to deformation, which alters the shape of the flue. This can lead to several problems, including uneven heating of the walls due to obstruction of gas flow through the flue, and a decrease in the furnace's heating capacity. Therefore, these problems can be avoided by using heat-resistant metal materials that maintain their morphological stability at such temperatures.

[0019] Indeed, in some cases, heat-resistant metal materials maintain their shape even when heated to temperatures between 1200°C and 1400°C. That is, although the normal temperature of a furnace is usually between 1000 and 1200°C, it has been found that the temperature of the flue can sometimes rise to about 1300°C, such as when heating the furnace to reach the operating temperature. At that temperature, depending on the shape and height of the flue, that is, depending on the weight that the metal material of the flue puts on itself in curved sections, the heat-resistant steel may deform further and slide down, potentially resulting in the flue being completely blocked. Having a heat-resistant metal material that maintains its shape at that temperature can avoid such problems as the flue being deformed and potentially blocked. Indeed, in some cases, heat-resistant metal materials maintain their shape at temperatures between 1250°C and 1350°C.

[0020] In some cases, heat-resistant metal materials remain chemically stable when heated to furnace operating temperatures, such as between 1000°C and 1200°C, preferably between 1200°C and 1400°C. Chemical stability means that the material does not react in its environment and maintains its useful properties. Specifically, its usefulness is maintained in the presence of heat and corrosive gases. In this sense, for example, if a material melts, corrodes, decomposes, or burns under the conditions brought about in a flue, it can be said to be chemically unstable. That is, even if a material is heat-resistant and morphologically stable, it has been found that it can degrade through corrosion and other means by reacting with the surrounding environment characterized by high temperatures and corrosive gases. Therefore, not only does the material itself deteriorate, but gases are also generated from the material, which can negatively affect the refractory material of the furnace by lowering its melting point, thus shortening the service life of the wall. These problems can be mitigated by using chemically stable metal materials.

[0021] In some cases, the heat-resistant metal material forms a protective surface oxide layer when heated to the operating temperature of the furnace, such as when heated to 1000°C. Therefore, the metal material can withstand the challenges related to high temperature and corrosion to a greater extent, as described above.

[0022] In some cases, the metal material is an aluminum-containing alloy that forms a protective Al2O3 surface layer when heated to the operating temperature of the furnace, such as when heated to 1000°C. Al2O3, that is, aluminum oxide, generally known as alumina, has a high melting point, high hardness, high compressive strength, low friction coefficient, and high durability against corrosive environments. Therefore, Al2O3 provides additional performance to the chemical stability of the material, thereby making the flue more durable and extending the service life.

[0023] In some cases, the heat-resistant metal material is a ferritic iron-chromium-aluminum alloy (FeCrAl).

[0024] Preferably, the metal material is, in weight percent: - Cr 19 - 25%, preferably Cr 20 - 22%, and - Al 3 - 7%, preferably Al 4 - 6%, and - optionally, Mo 1 - 5%, preferably Mo 2 - 4%, and - optionally, C up to 0.1%, preferably C up to 0.08%, and - optionally, Si up to 1%, preferably Si up to 0.7%, and - optionally, Mn up to 0.5%, preferably Mn up to 0.4%, and - the balance being Fe and unavoidable impurities and is a ferritic iron-chromium-aluminum alloy (FeCrAl). <00​In some cases, the new wall section is formed into a single piece upon completion of steps a) through d). Using conventional methods, the new wall section often needs to be formed in a stepwise manner, by forming each section to be formed on top of the other sections. This is especially true when the wall section has a complex flue shape or when the wall section is vertically elevated. This is also true when the wall section is an entire vertical wall section. This is because the inner formwork needs to be removed, and / or the high pressure from the castable refractory material deforms the shape of the inner formwork, making it difficult to fabricate the entire wall section in one go. It has been found that by using an inner formwork made of heat-resistant metal material that does not need to be removed before operation, the entire wall section can be fabricated in a single step, even when the wall section to be repaired is an entire wall.

[0026] In some cases, castable refractory materials are silica-based and / or alumina-based materials. These materials are particularly good at withstanding heat while being affordable to use.

[0027] In some cases, the internal formwork has an expandable structure. This provides a more adaptable internal formwork that can be easily adjusted to the conditions of the wall section to be repaired. When it is not necessary to form a section, the time required for the repair process is significantly reduced, making the repair process more cost-effective and minimizing furnace downtime.

[0028] In some cases, fire-resistant walls are brick walls. That is, this method has been found to be particularly useful when repairing brick walls because it eliminates much of the complexity of repairing brick walls, such as fitting individual bricks together and forming joints and connections between bricks and flues.

[0029] The present invention also relates to a wall portion for a furnace. The wall portion includes a main portion made from a castable refractory material and an inner formwork in contact with the main portion. The inner formwork defines the flue boundary of the refractory wall portion and is made from a heat-resistant metal material. Thus, a wall portion is provided in which the inner formwork does not need to be removed before the installation or operation of the furnace. Furthermore, the wall portion is thus substantially airtight, preventing gas leakage from cracks in the wall, etc. Also, the wall portion can be pre-formed before the repair process, simplifying and shortening the on-site repair process, i.e., the in-furnace repair process when operation is stopped, thereby giving the furnace more uptime.

[0030] The optional configurations mentioned above in relation to the method described in claim 1 also apply to the wall portion.

[0031] Therefore, the present invention also relates to a furnace including a wall portion according to the present invention.

[0032] In some cases, the furnace is a coke oven. That is, depending on the size and structure of the coke oven, methods for repairing the wall portions may be particularly useful in the case of a coke oven. Typically, coke is produced in a coke oven battery, which includes several coking chambers or ovens arranged side by side, separated from each other by walls that extend along the entire length of the chambers. The coke is extruded from the furnace in the longitudinal direction. A typical coke oven installation may involve, for example, arranging 30 to more than 100 individual coking chambers or ovens side by side, each chamber being 3 to 7 meters high, typically more than 14 meters long, and about 1 meter wide. Each wall is typically constructed of ceramic bricks in several horizontally extending pathways, assembled to define internal flues, vent passages, and other passages that extend vertically and / or horizontally within the heating wall.

[0033] The present invention will be further described below by non-limiting examples with reference to the attached schematic diagrams. [Brief explanation of the drawing]

[0034] [Figure 1] This is a flowchart of a method according to an exemplary embodiment of the present invention. [Figure 2] This is a schematic side view of a fire-resistant wall according to an exemplary embodiment of the present invention. [Figure 3] This is a schematic top view of a furnace according to an exemplary embodiment of the present invention. [Figure 4] This is a schematic cross-sectional top view of a wall portion according to an exemplary embodiment of the present invention. [Modes for carrying out the invention]

[0035] Please note that drawings are not always drawn to an accurate scale, and the dimensions of certain components may be exaggerated for clarity.

[0036] Figure 1 shows a flowchart of a method according to an exemplary embodiment of the present invention. This method involves repairing the refractory wall 2 of a furnace 1 by replacing the wall portion 3, such as the wall portion 3 shown in Figures 2 to 4.

[0037] Book: (a) The process includes demolishing wall section 3. The demolition process can be carried out by any suitable mechanical means. (b) The process includes installing an outer formwork 4 that defines a new wall section 3 on site, and installing an inner formwork 5 that defines a new flue 8 within the new wall section 3. The inner formwork 5 is made from a heat-resistant metal material. (c) The process includes the step of casting a castable refractory material into the volume defined by the outer formwork 4 and the inner formwork 5, thereby allowing the material to harden. The castable refractory material may be a silica-based and / or alumina-based material, but may also be any other refractory material suitable for casting. Casting the castable refractory material typically involves casting the castable refractory material. (d) The process includes removing the outer formwork 4. The outer formwork 4 can be made from any suitable material, such as wood, cardboard, fiberboard, or plywood, as it will be removed. It can also be made from a metal material or a laminate of wood and metal. The outer formwork 4 can be removed by mechanically removing it before the wall section 3 is put into operation. The outer formwork 4 can also be removed by burning it off, for example, when heating the wall section 3 when starting the operation of the furnace 1 after repairs.

[0038] The heat-resistant metal material of the inner formwork 5 can maintain its shape even when heated to the operating temperature of the furnace 1, such as between 1000°C and 1200°C, and preferably even when heated to a temperature between 1200°C and 1400°C. Therefore, deformation of the flue 8 can be avoided.

[0039] The heat-resistant metal material can remain chemically stable when heated to the operating temperature of the furnace 1, such as between 1000°C and 1200°C, and preferably even when heated to a temperature between 1200°C and 1400°C. This avoids deterioration of the flue 8 and the release of gases that could be harmful to surrounding refractory materials.

[0040] Figure 2 shows a schematic side view of a refractory wall 2 according to an exemplary embodiment of the present invention. Here, the refractory wall 2 of the furnace 1 is a brick wall, but it can be any other type of refractory wall 2, such as a wall already made of castable refractory material. An inner notch of a wall portion 3 that is to be repaired or intended to be repaired is shown. A flue 8 can be seen, which has a vertical portion 8a extending vertically inside the wall 2 itself and a horizontal portion 8b extending horizontally along the extension of the wall 2, and a connecting portion 8c between them. The horizontal portion 8b and the connecting portion 8c of the flue 8 can be incorporated into a floor portion (not shown) of the furnace 1, also commonly called a corbel.

[0041] Here, we can see a wall section 3 that extends vertically, covering the entire height of the flue 8. The new wall section 3 can be formed into a single piece by the completion of steps a) through d). The wall section 3 can be formed into a single piece by defining the shape of the wall section 3 using a single inner formwork 5 and a single outer formwork 4, and then casting castable refractory material by pouring it into the volume formed between the formwork 4 and 5, thereby forming the new wall section 3. The formwork 4 and 5 can also be made from several parts that are joined together. The outer formwork 4 can be made from, for example, several fiberboards stacked up to the height required to form the wall section 3. The wall section 3 can also be formed by laminating each section on top of the previous section after it has hardened.

[0042] In one embodiment of the present invention, the inner formwork 5 has an expandable structure. This provides a more adaptable inner formwork 5 that can be easily adjusted to suit the conditions of the wall portion 3 to be repaired.

[0043] Figure 3 shows a schematic top view of furnace 1 according to an exemplary embodiment of the present invention.

[0044] Here, furnace 1 is a coke oven 1. Furnace 1 has two chambers 10 intended for heating coke between three walls 2a, 2b, and 2c. The middle wall 2b has been repaired in situ, and an outer formwork 4 defining a new wall section 3 and an inner formwork 5 defining a new flue 8 within the new wall section 3 are shown. The formworks 4 and 5 define the volume into which the castable refractory material constituting the main part 7 of the new wall section will be poured. In Figure 3, the step (d) of removing the outer formwork 4 has not yet been performed. In other words, in order to completely complete the repair method, the outer formwork 4 must be removed before the furnace 1 is put into operation. The outer formwork 4 can be removed by burning it, for example, while heating the wall 3 when it is put back into operation. This may be especially true when the outer formwork 4 is made from a wooden material.

[0045] An outer formwork 4 having a U-shape is shown extending around the edge of the fire-resistant wall 2 to be repaired. The outer formwork 4 may also consist of two separate outer formworks 4 located on both sides of the wall section 3, which may apply if the wall section 3 to be repaired is not an edge, but each side of the wall section 3 to be repaired has a portion of the remaining fire-resistant wall 2. The outer formwork 4 may also consist of only one outer formwork 4 along the wall section 3 to be repaired, which may apply if only one side of the wall section 3 needs to be repaired.

[0046] Furthermore, insulation material 9 can be seen placed along walls 2a, 2b, and 2c around the area of ​​wall section 3 being repaired, to insulate walls 2a, 2c, and the remaining portion of wall 2b being repaired while refractory wall 2b is being repaired. Typically, coke is produced in a coke oven 1 battery, which includes multiple coking chambers 10 or ovens arranged side by side, separated from each other by walls extending along the entire length of the chambers 10. A typical coke oven 1 installation may include, for example, 30 to over 100 individual coking chambers 10 or ovens arranged side by side. Thus, the oven 1 in Figure 3 shows only a portion of a larger coke oven 1 that has more chambers (not shown) similarly extending along the outermost walls 2a, 2c. By using thermal insulation material 9 along walls 2a, 2b, and 2c to shield against the heat generated from the operating walls 2a, 2b, and 2c, repairs can be performed on-site while other chambers (not shown) remain operational, enabling extended uptime and improved productivity of furnace 1.

[0047] Figure 4 shows a schematic cross-sectional top view of wall portion 3 according to an exemplary embodiment of the present invention.

[0048] The wall section 3 includes a main section 7 made from castable fire-resistant material and an inner formwork 5 in contact with the main section 7. The inner formwork 5 defines the boundary of the flue 8 of the fire-resistant wall section 2 and is made from heat-resistant metal material.

[0049] In one embodiment of the present invention, the wall section 3 can be prefabricated. This reduces the amount of castable refractory material that needs to be poured on-site, thereby reducing the amount of material that needs to harden, and consequently shortening the time required for repairs. Furthermore, complex shapes can be fabricated remotely, so that conformity and quality are guaranteed before part of the furnace 1 is shut down for maintenance and repairs, thereby reducing the risk of errors and the prolonged downtime of the furnace 1.

[0050] Figure 4 shows a heat-resistant metal material for the inner formwork 5 having a protective surface oxide layer 6. The protective surface oxide layer 6 can be formed when the material is heated to the operating temperature of the furnace 1, such as when heated to 1000°C. Therefore, the layer cannot be formed until the wall portion 3 is installed in the furnace 1 and becomes operational. However, the wall portion 3 can be preheated to form the layer before being installed in the furnace 1. The protective surface oxide layer 6 can also be of a type that does not require heating, such as a protective surface oxide layer 6 that is simply formed by exposing the heat-resistant metal material to oxygen.

[0051] The heat-resistant metal material can be an aluminum-containing alloy that forms a protective Al2O3 surface layer 6 when heated to the operating temperature of furnace 1, such as when heated to 1000°C. For example, the heat-resistant metal material may be a ferritic iron-chromium-aluminum alloy (FeCrAl). The weight percentage of ferritic iron-chromium-aluminum alloy (FeCrAl) is: - Cr 19-25%, preferably Cr 20-22%, - Al 3-7%, preferably Al 4-6%, - Depending on the circumstances, Mo1-5%, preferably Mo2-4%, - Depending on the case, C may be up to 0.1%, preferably up to 0.08%. - Depending on the case, Si may be up to 1%, preferably up to 0.7%, - Depending on the case, Mn may be up to 0.5%, preferably up to 0.4%, - The remainder is Fe and unavoidable impurities. It can include...

[0052] Such alloys are suitable for use as the material for the inner mold 5 because, when heated to the operating temperature of the furnace 1, they are morphologically stable, chemically stable, and further form a protective Al2O3 surface layer 6.

[0053] It should be understood that the present invention is not limited to the embodiments described above and shown in the drawings; rather, those skilled in the art will recognize that many changes and modifications can be made within the scope of the appended claims.

Claims

1. A method for repairing the fireproof wall (2) of a furnace (1) by replacing at least one wall portion (3): (a) The process of demolishing the wall section (3); (b) The process of installing an outer formwork (4) that defines a new wall section (3) on site, and installing an inner formwork (5) that defines a new flue (8) within the new wall section (3); (c) A step of casting castable fire-resistant material into the volume defined by the outer formwork (4) and the inner formwork (5), and allowing the material to harden; (d) The process of removing the outer formwork (4); Includes, The method, characterized in that the inner formwork (5) is made from a heat-resistant metal material.

2. The method according to claim 1, wherein the heat-resistant metal material maintains its shape even when heated to the operating temperature of the furnace (1), such as between 1000°C and 1200°C, preferably between 1200°C and 1400°C.

3. The method according to any one of claims 1 to 2, wherein the heat-resistant metal material is chemically stable when heated to the operating temperature of a furnace (1), such as between 1000°C and 1200°C, preferably when heated to a temperature between 1200°C and 1400°C.

4. The method according to any one of claims 1 to 3, wherein the heat-resistant metal material forms a protective surface oxide layer (6) when heated to the operating temperature of the furnace (1), such as when heated to 1000°C.

5. The heat-resistant metal material is protected when heated to the operating temperature of the furnace (1), such as when heated to 1000°C. ２ O ３ The method according to any one of claims 1 to 4, wherein the aluminum-containing alloy forms the surface layer (6).

6. The method according to any one of claims 1 to 5, wherein the heat-resistant metal material is a ferritic iron-chromium-aluminum alloy (FeCrAl).

7. Heat-resistant metal materials are expressed in weight percentage: Cr 19-25%, preferably Cr 20-22%, Al 3-7%, preferably Al 4-6%, Depending on the case, Mo1-5%, preferably Mo2-4% Depending on the circumstances, C may be up to 0.1%, preferably up to 0.08%. Depending on the case, Si may be up to 1%, preferably up to 0.7%, Depending on the circumstances, the maximum amount of Mn may be 0.5%, preferably 0.4%. The remainder is Fe and unavoidable impurities. The method according to any one of claims 1 to 6, wherein the alloy is a ferritic iron-chromium-aluminum alloy (FeCrAl) containing the following.

8. The method according to any one of claims 1 to 7, wherein the new wall portion (3) is formed to become a single piece upon completion of steps a) to d).

9. The method according to any one of claims 1 to 8, wherein the castable refractory material is a silica-based and / or alumina-based material.

10. The method according to any one of claims 1 to 9, wherein the inner formwork (5) has an expandable structure.

11. The method according to any one of claims 1 to 10, wherein the fire-resistant wall (2) is a brick wall.

12. The method according to any one of claims 1 to 11, wherein the furnace (1) is a coke oven.

13. A wall portion (3) for a furnace (1), the wall portion (3) includes a main portion (7) made of castable refractory material and an inner formwork (5) in contact with the main portion (7), the inner formwork (5) defining the boundary of the flue of the refractory wall portion, The inner formwork (5) is characterized by being made from a heat-resistant metal material, wherein the wall portion is made from a heat-resistant metal material.

14. The wall portion according to claim 13, wherein the heat-resistant metal material maintains its shape even when heated to the operating temperature of a furnace, such as between 1000°C and 1200°C, preferably between 1200°C and 1400°C.

15. The wall portion according to claim 13 or 14, wherein the heat-resistant metal material is chemically stable when heated to the operating temperature of a furnace, such as between 1000°C and 1200°C, preferably when heated to a temperature between 1200°C and 1400°C.

16. The wall portion according to any one of claims 13 to 15, wherein the heat-resistant metal material forms a protective surface oxide layer (6) when heated to the operating temperature of a furnace, such as when heated to 1000°C.

17. Heat-resistant metal materials are protected when heated to the operating temperature of a furnace, such as when heated to 1000°C. ２ O ３ The wall portion according to any one of claims 13 to 16, wherein the aluminum-containing alloy forms the surface layer (6).

18. The wall portion according to any one of claims 13 to 17, wherein the heat-resistant metal material is a ferritic iron-chromium-aluminum alloy (FeCrAl).

19. Heat-resistant metal materials are expressed in weight percentage: Cr 19-25%, preferably Cr 20-22%, Al 3-7%, preferably Al 4-6%, Depending on the case, Mo1-5%, preferably Mo2-4%, Depending on the circumstances, C may be up to 0.1%, preferably up to 0.08%. Depending on the case, Si may be up to 1%, preferably up to 0.7%, Depending on the circumstances, the maximum amount of Mn may be 0.5%, preferably 0.4%. The remainder is Fe and unavoidable impurities. The wall portion according to any one of claims 13 to 17, wherein the wall portion is a ferritic iron-chromium-aluminum alloy (FeCrAl) containing the above.

20. A furnace (1) comprising a wall portion (3) according to any one of claims 13 to 19.

21. The furnace (1) is a coke oven, according to claim 20.

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