Title of invention: precast block structure
Technical field
[0001]
　TECHNICAL FIELD The present invention relates to a precast block structure for refractory coating of a metal covering object such as a water-cooled skid pipe, an inner wall of a furnace shell and the like, particularly in a heat equipment such as a heating furnace, which has a remarkable heat removal loss.
BACKGROUND ART
[0002]
　In the case of a water-cooled skid pipe constituting a walking beam of a heating furnace as an object to be covered with metal, for example, a metallic stud (metal stud) is conventionally welded to a water-cooled skid pipe made of metal By applying a fixed refractory, the water-cooled skid pipe was covered with an amorphous refractory, thereby ensuring heat resistance and heat insulation. However, with such a conventional technique, there are many steps such as dismantling of refractory → removal of stud → keren of skid → stud welding → framing of irregular refractories, pouring → curing → unfolding, number of studs (Generally several thousands / oven since it is 20 to 30 lines / m)), there was a problem of requiring a great deal of labor and time.
[0003]
　In order to solve this problem, for example, Patent Document 1 proposes a method in which a metal stud is provided on a metal plate to preliminarily mold a heat insulating block formed into a precast block and on site is applied to a skid pipe by welding. In addition, the applicant of the present invention has proposed in Patent Document 2, "A metal stud capable of covering the outer periphery of a metallic covering object, a ceramic stud connected to the metallic plate, an irregular shape A precast block structure comprising a precast block structure made of refractory material and a precast block structure made of refractory material, the stud is connected so as to be movable with respect to the metal plate " .
[0004]
　According to the precast block structure in which the metal plate and the precast block are integrated in this way, since the object to be coated can be covered with refractory merely by welding the metal plate to the outer periphery of the object to be coated, it is possible to coat the metal stud Compared with welding to an object, the workability is remarkably improved.
[0005]
　However, as a result of repeated tests on this precast block structure by the present inventors, it has been found that there is a problem that a crack occurs in the precast block at the time of production or use thereof.
Prior Art Document
Patent literature
[0006]
Patent Document 1: Korean Open Patent Publication No. 2001-0048087
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2016-104899
Summary of the invention
Problem to be Solved by Invention
[0007]
　SUMMARY OF THE INVENTION It is an object of the present invention to suppress occurrence of cracks in a precast block in a precast block structure in which a metal plate and a precast block are integrated.
Means for solving the problem
[0008]
　In order to solve the above problem, the present inventors focused attention on the condition of integration of the metal plate and the precast block and conducted extensive studies. As a result, in order to suppress the occurrence of cracks in the precast block, the thickness of the precast block and the thickness of the metal plate It was found that the length ratio is important.
[0009]
　That is, according to one aspect of the present invention, there is provided a method of manufacturing a metal covering object, which comprises: a metal plate capable of covering the outer periphery of a metallic covering object; and a metal plate integral with the metal plate and having CaO.6Al 2 O 3 as a mineral composition And a precast block in which a porous heat insulating aggregate is blended, wherein in a cross section orthogonal to the longitudinal direction of the metallic covering object, the thickness of the precast block and the thickness of the metal Wherein the ratio of the length of the plate (the thickness of the precast block / the length of the metal plate) is 0.2 or more and 0.4 or less "is provided.
Effect of the invention
[0010]
　According to the present invention, in a precast block structure in which a metal plate and a precast block are integrated, occurrence of cracks in the precast block at the time of manufacturing or using thereof can be suppressed. As a result, the effect of the precast block structure that the workability is remarkably improved as compared with the conventional technology can be exerted in practice.
Brief Description of the Drawings
[0011]
FIG. 1 is a perspective view showing a precast block structure according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a precast block structure according to another embodiment of the present invention.
3 is a perspective view showing a water-cooled skid pipe refractory-coated by the precast block structure of FIGS. 1 and 2. FIG.
4 is a cross-sectional view taken along line I - I of FIG. 3.
5 is a cross-sectional view taken along line II - II of FIG. 3.
MODE FOR CARRYING OUT THE INVENTION
[0012]
　Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　FIG. 1 and FIG. 2 show an embodiment of the precast block structure of the present invention. 3 shows a water-cooled skid pipe refractively covered with the precast block structure of FIGS. 1 and 2, and FIGS. 4 and 5 show a cross section taken along line I - I and II - II of FIG. 3, respectively .
[0013]
　The precast block structure A shown in FIG. 1 and the precast block structure B shown in FIG. 2 are formed by integrating the metal plate 1 and the precast block 2. In the embodiment, a metal stud 3 is used for integrating the metal plate 1 and the precast block 2 (see FIGS. 4 and 5). However, the means of integration is not limited to this, and it is also possible to integrate them using a ceramic stud as disclosed in Patent Document 2, for example.
[0014]
　The metal plate 1 has a shape capable of covering the outer periphery of a metallic coated object. Specifically, the metal plate 1 of the precast block structure A of FIG. 1 has a semicircular shape capable of covering a cylindrical skid post 11 (see FIG. 4) which is an object to be coated, The metal plate 1 of the precast block structure B has a partially elliptical shape capable of covering an elliptical cylindrical skid beam 12 (see FIG. 5) which is an object to be coated. On the other hand, the precast block 2 is made of an irregular refractory material (CA 6 lightweight castable) containing a porous adiabatic aggregate having a mineral composition of CaO · 6Al 2 O 3 . This CA6 lightweight castable has the characteristic of being lightweight, low in thermal conductivity, and excellent in resistance to scaling and melting, so that the heat insulating effect of the precast block structures A and B can be improved.
[0015]
　These precast block structures A and B are used to refractly coat the water-cooled skid pipe 10 as shown in FIG. 3. Specifically, as shown in FIG. 4, the skid post 11 of the water-cooled skid pipe 10 is fire-resistant coated with two precast block structures A in the circumferential direction. At this time, the metal plate 1 is welded to the skid post 11, and this welding is easily and reliably carried out by utilizing the clearance (the gap provided for welding) provided by the end portion 1 a of the metal plate 1 can do. After welding, the gap provided by the end portion 1 a of the metal plate 1 is filled with the patching material 4. On the other hand, as shown in FIG. 5, the skid beam 12 of the water-cooled skid pipe 10 is fire-resistant coated with two precast block structures B in the circumferential direction. At this time, the metal plate 1 is welded to the skid beam 12. This welding can also be carried out easily and reliably by utilizing the gap provided by the end portion 1a of the metal plate 1, and after the welding, the metal plate The gap provided by the end portion 1 a is filled with the patching material 4. The gap between the precast block structures B and B adjacent in the circumferential direction is the upper portion of the skid beam 12, and the upper portion of the skid beam 12 is composed of the patching member 4, and a metallic skid Buttons 13 are installed at appropriate intervals. The joining portion between the skid post 11 and the skid beam 12 is also composed of the patching member 4.
[0016]
　In this embodiment, a fiber (alumina fiber) containing 70 mass% or more of Al 2 O 3 component is interposed between the precast block structures A and A adjacent in the longitudinal direction and between the precast block structures B and B, C (see C in FIG. 3) are installed. The portion where this fiber C is installed is a so-called expansion margin, and the CaO component in the CA 6 lightweight castable reacts with the alumina component in the fiber due to the heating at the first use to form CA 2 (CaO · 2Al 2 O 3 ) or CA 6 (CaO · 6Al 2 O 3 ). In addition, CA2 and CA6 generated by the above-described reaction exhibit expansion and contraction behavior similar to CA6 lightweight castable. With these, it is possible to suppress occurrence of a gap at the time of use in the expansion margin provided between the adjacent precast block structures. Also, since the expansion margin itself is secured, cracks and cracks in the precast block due to stress due to thermal expansion can also be suppressed.
　The fibers C may also be placed between the precast block structures A and A adjacent to each other in the circumferential direction and between the precast book structures B and B in the circumferential direction.
[0017]
　In the above configuration, the precast block structures A and B of the present invention have cross sections orthogonal to the longitudinal direction of the metallic covering objects (the skid post 11 and the skid beam 12), that is, in FIGS. 4 and 5, the precast block 2 and the length of the metal plate 1 (the thickness of the precast block / the length of the metal plate) is 0.2 or more and 0.4 or less. If the numerical value of this ratio is large (the thickness of the precast block 2 is too large), cracks are likely to occur in the precast block 2 at the time of use, and the spall resistance resistance lowers. This is presumed to be because the temperature gradient between the inner circumference side and the outer circumference side of the precast block 2 increases as the thickness of the precast block 2 increases. Further, as the thickness of the precast block 2 increases, the weight of the precast block structure increases, so that the workability decreases. From this point as well, it is necessary to set the ratio to 0.4 or less. On the other hand, if the ratio is small (the thickness of the precast block 2 is too small), cracks are likely to occur in the precast block 2, especially during production, due to insufficient strength.
[0018]
　In the present invention, the "thickness of precast block" means the thickness in a direction orthogonal to the metal plate in a cross section orthogonal to the longitudinal direction of the metallic covering object, and "thickness of the pre-cast block" Refers to the length of the metal plate along the circumferential direction of the metallic covering object in a cross section orthogonal to the longitudinal direction of the metallic covering object.
Example
[0019]
　In a semicylindrical precast block structure A (hereinafter referred to as "type A") shown in Figure 1 and in a partially oval cylindrical pre-cast block structure B (hereinafter referred to as "type B") shown in Figure 2, As shown in 1, the precast block structure in which the thickness of the precast block and the length of the metal plate were changed was evaluated for the presence or absence of cracking at the time of production, the workability and the spall resistance. In Table 1, the precast block is simply referred to as a block.
[0020]
　Regarding the presence or absence of cracks at the time of manufacture, the process of curing, unframing, and drying was carried out after kneading an irregular refractory material (CA 6 lightweight castable) with a predetermined moisture amount and casting into the precast block shape of each example The presence or absence of cracking was evaluated. In Table 1, the absence of cracks was marked O, and the cracks were indicated by x.
　The workability was evaluated based on the weight of the precast block structure. In Table 1, weighing less than 40 kg is marked ◯, and 40 kg or more by x.
　With respect to spall resistance, the outer circumferential surface of the precast block structure was heated to 1300 ° C. and then evaluated according to the presence or absence of cracks when the heating and cooling cycle of forced air cooling was repeated five times. In Table 1, the absence of cracks was marked O, and the cracks were indicated by x. The evaluation of spall resistance is based on the assumption of the presence or absence of cracks at the time of use.
[0021]
[table 1]

[0022]
　As shown in Table 1, in Examples 1 to 4 (the ratio of the thickness of the precast block to the length of the metal plate (the thickness of the precast block / the length of the metal plate) is in the range of 0.2 to 0.4 In Type A) and Examples 5 and 6 (Type B), no cracking occurred at the time of production, and the workability and spall resistance were also good.
[0023]
　On the other hand, in Comparative Examples 1 and 3 (Type A) and Comparative Example 5 (Type B) in which the above ratio was less than 0.2, cracks occurred during production. In Comparative Examples 2 and 4 (Type A) and Comparative Example 6 (Type B) in which the above ratio exceeds 0.4, it was judged that spall resistance was poor and cracks were likely to occur in the precast block at the time of use. In Comparative Examples 1, 3, and 5 in which cracks occurred at the time of production, the spall resistance could not be evaluated.
Explanation of sign
[0024]
　A, B precast block structure
　C fiber (alumina fiber)
　1 metal plate
　1 end of metal plate
　2 precast block
　3 metal stud
　4 patching material
　10 water cooling skid pipe
　11 skid post
　12 skid beam
　13 skid button
The scope of the claims
[Claim 1]
　A metal plate capable of covering the outer periphery of a metallic coated object and a precast blended with the
　metallic plate and containing a porous adiabatic aggregate having CaO · 6Al 2 O 3 as a mineral composition
　Wherein the precast block structure has a ratio of a thickness of the precast block to a length of the metal plate (a thickness of the precast block / a thickness of the precast block) in a cross section orthogonal to the longitudinal direction of the metallic covering object, The length of the metal plate) is 0.2 or more and 0.4 or less.