Repair method for furnace inner wall

Abstract

To provide a practical method of repairing an internal surface of a furnace, in which repair work is very easy, the method being able to lengthen durability after repairing, thereby reducing repairing frequency.SOLUTION: A method of repairing an internal surface of a furnace K consecutively performs four steps: a patching material coating step; an anchor member embedding step; a stud bond-fixing step; and a monolithic refractory layer laminating step. In the anchor member embedding step, after an embrittled part of a surface layer of a worn refractory layer C1 is removed, a patching material is laminated on the surface layer of the refractory layer C1, and before a patching material layer P is cured, anchor members A,A are embedded into which studs S,S can be bond-fixed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This relates to a repair method for repairing the inner wall surface of industrial furnaces such as incinerators and melting furnaces, which have a refractory layer laminated on the inside of a metal peripheral wall (external wall). [Background technology]

[0002] Industrial furnaces, such as incinerators and melting furnaces, are typically constructed with a refractory layer on the inside of a metal peripheral wall (steel shell). When the refractory layer is formed using monolithic refractory, the refractory layer is often formed after multiple studs with branched ends are welded in a scattered pattern to the inner surface of the peripheral wall. Industrial furnaces with a refractory layer on the inside of their peripheral walls often require periodic repair work because the refractory layer can erode or peel off due to thermal history and other factors after long-term use. However, repairing such industrial furnaces requires a significant amount of work, including removing the remaining refractory, removing worn studs, welding new studs, and applying monolithic refractory.

[0003] Therefore, as in Patent Document 1, a repair method has been proposed in which the surface portion of a refractory layer (firebrick layer) that has been partially damaged (eroded) due to long-term use is peeled off to make the refractory layer of a generally uniform thickness, and then pilot holes are drilled in the refractory layer (remaining refractory layer), anchor members with check claws are driven into the pilot holes, and an unshaped refractory layer is layered on top of the refractory layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-61864 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method of repairing furnace refractories such as that disclosed in Patent Document 1 requires drilling pilot holes in the remaining hard refractory layer, and therefore the repair work is not necessarily easy. Furthermore, in the method of repairing furnace refractories such as that disclosed in Patent Document 1, if the pilot holes are not drilled accurately, a gap will be formed between the pilot holes and the anchor members, making the anchor members unstable, which may cause the refractory layer to peel off within a short period of time after the repair, requiring further repair.

[0006] The object of the present invention is to provide a practical method for repairing the inner wall surface of a furnace, which solves the problems associated with the above-mentioned conventional methods for repairing refractories in a furnace, makes repair work very easy, and extends the service life after repair, thereby reducing the frequency of repairs. [Means for solving the problem]

[0007] The invention described in claim 1 of the present invention is a repair method for repairing the inner wall surface of a furnace, which is formed by laminating a refractory layer on the inner surface of the peripheral wall, and includes an anchor member embedding step of laminating a patching material on the surface layer of the refractory layer after removing an embrittled portion of the surface layer of the worn refractory layer, and embedding an anchor member to which a stud can be fixed before the patching material layer hardens, and a monolithic refractory laminating step of laminating a monolithic refractory on the hardened patching material layer, and when laminating the patching material on the surface layer of the refractory layer after removing the embrittled portion, the thickness of the laminated patching material layer is made thinner than the refractory layer after removing the embrittled portion. The anchor member has a retaining means for preventing the split pieces from being disengaged by driving in a check projection and a wedge. The patching material is a clay-like refractory material (i.e., an unshaped refractory material that is more flexible than ordinary castables) made by mixing refractory aggregate, plastic material, adjusting material, binder, etc. with a predetermined amount of water (approximately 7 to 9 mass%).

[0008] The invention described in claim 2 is characterized in that the patching material is a phosphate-based material in the invention described in claim 1. Note that a phosphate-based patching material is a patching material that contains a predetermined amount (approximately 1 to 10% by mass) of phosphate as an adjusting material or binding material (binder).

[0009] The invention as set forth in claim 3 is characterized in that in the invention as set forth in claim 1 or 2, the anchor member is capable of screwing a stud therein. [Effects of the Invention]

[0011] According to the method for repairing furnace inner wall surfaces described in claim 1, a new refractory layer can be formed on the remaining refractory layer to replace the worn refractory layer without drilling pilot holes in the hard refractory layer, making the repair work extremely easy. Furthermore, the method for repairing furnace inner wall surfaces described in claim 1 embeds and fixes anchor members in the unhardened patching material, and no gaps are formed between the patching material layer and the anchor members, ensuring that the anchor members are held in place after repair, thereby effectively reducing the frequency of repairs. Also, claim 1 In the method for repairing furnace inner wall surfaces described above, the anchor members have means for preventing them from coming off, and this can reliably prevent the refractory layer from peeling off after repair with studs, making it less likely that repair work will have to be redone and making it possible to extremely effectively reduce the frequency of repairs.

[0012] In the method for repairing furnace inner wall surfaces described in claim 2, the patching material is a phosphate-based material, and the patching material layer immediately after application is very flexible, making it easy to embed anchor members, and the patching material layer becomes extremely strong after hardening, so the anchor members can be firmly held in place, making it possible to very effectively reduce the frequency of repairs. Also, according to the method for repairing furnace inner wall surfaces described in claim 2, the patching material layer hardens quickly after application, so there is no need to provide a long curing period for the patching material layer, and the next step (such as laminating a different monolithic refractory layer) can be carried out quickly, making it possible to shorten the construction period.

[0013] According to the method for repairing furnace inner wall surfaces described in claim 3, the studs for preventing the amorphous refractory layer from peeling off can be fixed to the patching material layer simply by screwing them into the anchor member, making the repair work extremely easy. [Brief explanation of the drawings]

[0015] [Figure 1] This is an explanatory diagram (vertical cross-sectional view) showing the steps of the method for repairing the inner wall surface of a furnace (a to d show the steps of applying patching material, embedding anchor members, fixing studs, and laminating an amorphous refractory layer, respectively). [Figure 2] 1A and 1B are explanatory views showing an anchor member (FIG. 1A shows a state in which a wedge body has not been driven in, and FIG. 1B shows a state in which a wedge body has been driven in). [Figure 3] FIG. 10 is an explanatory diagram (front view) showing the state in which an anchor member is embedded in a patching material layer. [Figure 4] FIG. [Figure 5] FIG. 10 is an explanatory diagram showing a modified example of the stud. [Figure 6] 10A and 10B are explanatory views showing modified examples of the anchor member. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of a method for repairing a furnace inner wall surface according to the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the process of repairing the inner wall surface of a furnace (combustion furnace). The furnace K has a refractory layer (firebrick layer and monolithic refractory layer) C1 formed on the inner surface of a cylindrical metal peripheral wall (steel shell) W with a predetermined outer diameter (1,500 mmφ). As shown in FIG. 1(a), the surface of the monolithic refractory layer C1 has worn away due to use. The repair method for the furnace K of this embodiment involves four steps, sequentially performed: a. patching material application step, b. anchor member embedding step, c. stud fixing step, and d. monolithic refractory layer lamination step. Each step will be described below.

[0017] [a. Patching material application process] When repairing the inner wall surface of a furnace using the repair method of the present invention, first, a patching material is applied to the inner wall surface (such as the inner surface of the steel shell). When repairing the inner wall surface of a furnace K, first, as shown in FIG. 1(b), the worn portion of the refractory layer (remaining refractory layer) C1 laminated on the inner surface of the steel shell W is removed. At this time, the thickness of the refractory layer C1 is adjusted so that it is approximately uniform. Then, as shown in FIG. 1(c), a patching material is applied to the surface of the refractory layer C1.

[0018] Suitable patching materials include those using chamotte, high-alumina, and chromium as refractory aggregates. Phosphate-based patching materials are preferred because they provide adequate flexibility after application and a hardened patching layer with excellent heat and spalling resistance. Among these phosphate-based patching materials, those containing 45 to 90% by mass of alumina (Al2O3) and 5 to 45% by mass of silica (SiO3) are particularly preferred because they provide an extremely hardened patching layer with excellent heat and spalling resistance.

[0019] Furthermore, when a phosphate-based patching material is used, the patching material is thoroughly mixed with a predetermined amount of water (5 to 15% by mass) before application. The patching material mixed with water is then applied to the surface of the refractory layer C1 to a predetermined thickness to form the patching material layer P. The thickness of the patching material layer P (after drying) varies depending on the size of the furnace K and the size (length) of the anchor members (described later), but is preferably 10 mm to 50 mm, and is preferably at least 5 mm thicker than the length of the anchor members. A thickness of less than 10 mm is undesirable because it makes it difficult to embed the anchor members. Conversely, a thickness of more than 50 mm is undesirable because it is prone to peeling before hardening. Furthermore, a difference of less than 5 mm between the thickness of the patching material layer and the length of the anchor members is undesirable because it is prone to cracking due to thermal history after repair. Furthermore, the thickness of the patching material layer P is preferably thinner than the remaining refractory layer C1 to prevent peeling.

[0020] [b. Anchor member embedding process] After the patching material layer P is layered on the surface of the refractory layer (remaining refractory layer) C1 as described above, anchor members (base end side) A, A·· are embedded (inside the patching material layer P) in a scattered pattern as shown in FIG. 1(d) before the patching material layer P hardens. FIG. 2 shows a grip anchor as an example of such an anchor member A. The grip anchor A comprises an anchor body 1 formed of metal (iron) in a substantially cylindrical shape and a wedge body 2 formed of metal (iron) in a truncated cone shape. The anchor body 1 has multiple slits 3, 3·· along the axial direction at one edge, which divide the edge into strips. In addition, the outer surfaces of the segments are formed with check protrusions 4, 4·· that have a sawtooth cross section (axial cross section) and function as a retaining means. A thread groove (not shown) is formed at the edge on the opposite side for threading the base end of a stud (described later). On the other hand, the outer diameter of the small diameter portion of the wedge body 2 is smaller than the inner diameter of the anchor body 1, and the outer diameter of the large diameter portion is larger than the inner diameter of the anchor body 1. Therefore, when the small diameter portion of the wedge body 2 is inserted into the side of the anchor body 1 where the slits 3, 3... are formed and the wedge body 2 is driven in (i.e., when pressure is applied from the outside of the large diameter portion), the divided pieces of the anchor body 1 spread outward as shown in Figure 2(b), and function as a retaining means.

[0021] Furthermore, when embedding the anchor members A, A... inside the patching material layer P, it is preferable to arrange the anchor members A, A... in multiple stages so that adjacent anchor members A, A... are spaced a predetermined distance apart (approximately 50 to 200 mm) as shown in Figure 3, and to arrange the anchor members A, A... in a staggered manner so that each anchor member A, A... in each column or row is located at the center of adjacent anchor members A, A... in the adjacent column or row, thereby making the distance between adjacent anchor members A, A equal. Furthermore, the anchor members A are embedded so that their axial direction is perpendicular to the surface of the patching material layer P and their thread groove-forming surfaces are located roughly on the surface of the patching material layer P. After the anchor members A, A... are embedded inside the uncured patching material layer P in this way, the patching material layer P is allowed to cure sufficiently and harden.

[0022] [c. Stud fixing process] After the patching material layer P with the anchor members A, A·· embedded has sufficiently hardened, studs S, S·· are fixed to each of the embedded anchor members A, A··, as shown in FIG. 1(e). The studs S are intended to prevent the monolithic refractory layer C, which is layered on the hardened patching material layer P, from peeling off. Suitable studs include those bent into an L-shape or branched into a Y-shape. FIG. 4 shows a Y-shaped stud S to be fixed (screwed) to an anchor member (grip anchor) A. The stud S is formed by welding two cylindrical bodies, one long and one short, bent into a V-shape. A thread is formed at the base end, not the base end. The stud S is fixed to the anchor member A by threading the thread at the base end into a thread groove provided on the inner surface of the front end of the anchor member A. Furthermore, the joining strength between the stud S and the anchor member A can be increased by spot welding the threaded portions of the two.

[0023] [d. Monolithic refractory layering process] After the studs S, S·· are fixed to the anchor members A, A·· embedded in the patching material layer P as described above, a new monolithic refractory layer C2 is formed by applying a monolithic refractory to the patching material layer P, as shown in Figure 1(f). The type of monolithic refractory is not particularly limited, and suitable materials include castables using alumina cement hydrate cement bonding, low-cement castables using ultrafine powders such as dispersants and silica fume, lightweight castables made by mixing porous lightweight aggregate with cement materials, plastic materials made by adding plastic materials to refractory aggregate, and ramming materials with lower plasticity than plastic materials. The monolithic refractory layer should be selected appropriately, taking into account the furnace temperature, the materials being processed in the furnace, and their resistance to the furnace atmosphere. The monolithic refractory layering process can also be performed using a spraying device using an air compressor.

[0024] <Effects of the method for repairing the furnace inner wall surface according to the embodiment> The method for repairing the inner wall surface of a furnace K according to the above embodiment includes an anchor member embedding step of removing embrittled portions of the surface layer of the worn refractory layer C1, layering a patching material on the surface of the refractory layer C1, and embedding anchor members A, A·· to which studs S, S·· can be attached before the patching material layer P hardens. Therefore, this repair method significantly simplifies repair work by forming a new refractory layer C2 to replace the worn refractory layer on the remaining refractory layer C1 without drilling pilot holes in the hard refractory layer. Furthermore, the method for repairing the inner wall surface of a furnace K according to the embodiment embeds and fixes the anchor members A, A·· in the unhardened patching material, preventing voids from forming in the patching material layer P, thereby ensuring reliable retention of the anchor members A, A··, thereby effectively reducing the frequency of repairs.

[0025] Furthermore, in the repair method for the inner wall surface of the furnace K in the above embodiment, the patching material is a phosphate-based material, and the patching material layer P is very flexible immediately after application, making it easy to embed the anchor members A, A.... In addition, the patching material layer P becomes extremely strong after hardening, making it possible to very effectively reduce the frequency of repairs. Furthermore, according to this repair method, the patching material layer P hardens quickly after application, so it is possible to shorten the construction period by quickly carrying out the next process (such as laminating the monolithic refractory layer C2) without providing a long curing period for the patching material layer P.

[0026] Furthermore, in the method for repairing the inner wall surface of the furnace K in the above embodiment, the anchor members A, A·· can be screwed to the studs S, S··, and the work of fixing the studs S, S·· to the patching material layer P is not time-consuming, making the repair work extremely easy and efficient.

[0027] In addition, in the method for repairing the inner wall surface of the furnace K in the above embodiment, the anchor members A, A·· have a means for preventing them from coming out (i.e., a structure that expands each divided piece by driving in the check projections 4, 4·· and the wedge body 2), which reliably prevents the refractory layer from peeling off after repair with studs, making it less likely that repair work will have to be redone and extremely effectively reducing the frequency of repairs.

[0028] <Example of a change in the furnace wall repair method> The method for repairing furnace inner walls according to the present invention is not limited to the above-described embodiment, and the content of each step, such as the patching material application step, anchor member embedding step, stud fixing step, and monolithic refractory layer lamination step, can be appropriately changed as needed without departing from the spirit of the present invention. Furthermore, the type of furnace in which the method for repairing furnace inner walls according to the present invention is adopted is not limited to combustion furnaces as in the above-described embodiment, and can be appropriately changed as needed.

[0029] For example, the method for repairing a reactor inner wall surface according to the present invention is not limited to the use of a Y-shaped stud formed by welding two long and short cylindrical bodies bent in a V-shape, as in the above embodiment, but can also be changed to a Y-shaped stud, an L-shaped stud, a trident stud, or the like, formed by welding a straight cylindrical body to the center of a U-shaped cylindrical body, as in Fig. 5. Furthermore, the method for repairing a reactor inner wall surface according to the present invention is not limited to the use of a grip anchor consisting of a main body and a wedge body as the anchor member, as in the above embodiment, but can also be changed to a simple truncated cone-shaped anchor with a fastening mechanism (screw mechanism) for fastening to the stud at its tip, as in Fig. 5. [Industrial Applicability]

[0030] The method for repairing furnace inner wall surfaces according to the present invention has the excellent effects described above, and can therefore be suitably used as a method for repairing inner wall surfaces in various furnaces such as incinerators and melting furnaces. [Explanation of symbols]

[0031] K··Furnace W...Peripheral wall (iron door) C1 Refractory layer (remaining shaped refractory layer or unshaped refractory layer) P··Patching material layer A, A': Anchor member S, S'··Studs C2: Monolithic refractory layer (new monolithic refractory layer) 4. Protrusion (prevention mechanism)

Claims

1. A repair method for repairing an inner wall surface of a furnace having a refractory layer laminated on the inner surface of a peripheral wall, comprising: an anchor member embedding step of removing the embrittled portion of the surface layer of the worn refractory layer, laminating a patching material on the surface layer of the refractory layer, and embedding an anchor member capable of fixing a stud before the patching material layer hardens; and a monolithic refractory lamination step of laminating a monolithic refractory on the hardened patching material layer, When the patching material is laminated on the surface layer of the refractory layer after the embrittlement portion has been removed, the thickness of the patching material layer to be laminated is made thinner than that of the refractory layer after the embrittlement portion has been removed, and A method for repairing a furnace inner wall surface, characterized in that the anchor member has a retaining prevention means having a structure that expands each divided piece by driving in a check projection and a wedge body.

2. 2. The method for repairing a reactor inner wall surface according to claim 1, wherein the patching material is a phosphate-based material.

3. 3. The method for repairing a reactor inner wall surface according to claim 1, wherein the anchor member is capable of screwing a stud thereto.

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