Title: INSULATING STRUCTURE
Technical field
[0001]
　TECHNICAL FIELD The present invention relates to a thermal insulation structure for covering and insulation a metallic covering object such as a water-cooled skid pipe, a furnace shell inner wall, etc., particularly in a heat equipment such as a heating furnace, which has a remarkable loss of heat loss .
BACKGROUND ART
[0002]
　As such a heat insulating structure, Patent Document 1 discloses a technique of covering a water-cooled skid pipe (skid) constituting a walking beam of a heating furnace with a plurality of precast blocks (divided blocks). In the heat insulating structure of Patent Document 1, an expansion margin is provided between the precast blocks which are adjacent in the longitudinal direction so as not to cause cracks or cracks in the precast block due to stress caused by thermal expansion, and the expansion margin An expansion absorbing material is installed.
[0003]
　However, according to the test of the inventors of the present invention, when a ceramic fiber is installed as an expansion absorbing material, the ceramic fiber shrinks due to heating at the time of first use, as a result, a gap is generated between adjacent precast blocks, It turned out that there was a problem of lowering.
Prior Art Document
Patent literature
[0004]
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-112832
Summary of the invention
Problem to be Solved by Invention
[0005]
　An object to be solved by the present invention is to provide a heat insulating structure for covering a metal covering object with a plurality of precast blocks by suppressing occurrence of a gap at the time of use in an expansion margin provided between adjacent precast blocks It is in.
Means for solving the problem
[0006]
　In order to solve the above problem, the present inventors paid attention to the relationship between the material of the expansion absorbing material to be installed in the expansion margin between the adjacent precast blocks and the material of the precast block, and as a result, the material of the precast block was changed (CA6 lightweight castable) containing porous adiabatic aggregate with CaO · 6Al 2 O 3 as a mineral composition, the material of the expansion absorber was changed to Al 2 O 3 component 70 By making fibers (alumina fibers) containing at least% by mass, they react and expand due to heating at the first use, thereby generating gaps at the time of use for the expansion margin provided between the adjacent precast blocks It was found that it can be suppressed.
[0007]
　In other words, according to one aspect of the present invention, there is provided a method for producing a precast block comprising a porous adiabatic aggregate containing CaO.6Al 2 O 3 as a mineral composition, A heat insulating structure characterized in that a fiber containing 70 mass% or more of an Al 2 O 3 component is provided between adjacent precast blocks in the installed heat insulating structure "is provided.
Effect of the invention
[0008]
　In the thermal insulation structure of the present invention, the CaO component in the CA 6 lightweight castable reacts with the alumina component in the fiber due to the heating during the first use to form CA 2 (CaO · 2Al 2 O 3 ) or CA 6 (CaO · 6 Al 2 O 3 ), which is the main component. 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 blocks. 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.
Brief Description of the Drawings
[0009]
FIG. 1 is a perspective view showing a water-cooled skid pipe to which a heat insulating structure of the present invention is applied.
2 is a cross-sectional view taken along line II of FIG. 1.
3 is a cross-sectional view taken along line II - II of FIG. 1.
FIG. 4 is a perspective view showing a precast block A used for the heat insulating structure of FIG. 1.
5 is a perspective view showing a precast block B used for the heat insulating structure of FIG. 1. FIG.
MODE FOR CARRYING OUT THE INVENTION
[0010]
　Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　FIG. 1 shows a water-cooled skid pipe to which the heat insulating structure of the present invention is applied as an embodiment of the present invention. 2 and 3 respectively show a sectional view taken along line I - I and II - II of FIG. 1, and FIGS. 4 and 5 show precast blocks A and B used for the heat insulating structure of FIG. 1, respectively There.
[0011]
　The water-cooled skid pipe 10 is composed of two skid posts 11 extending in the vertical direction and one skid beam 12 extending in the horizontal direction. The skid post 11 is fire-resistant covered with the precast block A, and the skid beam 12 is covered with the precast block B It is refractory covered with. Between the pre-cast blocks A and A adjacent to each other, and between the precast blocks B and B, fibers (alumina fibers) C containing 70 mass% or more of Al 2 O 3 component are arranged.
[0012]
　In the present embodiment, the precast blocks A and B are formed by integrating the metal plate 1 and the precast block main body 2, and the metal stud 3 is used for integrating the metal plate 1 and the precast block main body 2 ( See FIGS. 4 and 5).
[0013]
　In the precast blocks A and B, the metal plate 1 has such a shape that it can cover the outer periphery of the metal covering object. Specifically, the metal plate 1 of the precast block A in FIG. 4 has a semicircular shape capable of covering the cylindrical skid post 11 (see FIG. 2) which is an object to be coated, and the precast block The metal plate 1 of B has a partially elliptical shape capable of covering an elliptical cylindrical skid beam 12 (see FIG. 3) which is an object to be coated. In the precast block A and B, the precast block main body 2 is made of porous adiabatic aggregate having CaO · 6Al 2 O 3 as a mineral composition and an irregular refractory material (alumina cement mixed with CA 6 Lightweight castable). This CA6 lightweight castable has the characteristic of being lightweight, low in thermal conductivity, and excellent in resistance to scaling and melting, and it is possible to improve the heat insulating effect of the precast blocks A and B.
[0014]
　These precast blocks A and B are used to refractly coat the water-cooled skid pipe 10 as shown in FIG. Specifically, as shown in FIG. 2, the skid post 11 of the water-cooled skid pipe 10 is fire-resistant coated with two precast blocks 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. 3, the skid beam 12 of the water-cooled skid pipe 10 is fire-resistant coated by using two precast blocks 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. A gap portion between the precast blocks B and B, which is the upper portion of the skid beam 12, is filled with the patching material 4, and metal skid buttons 13 for supporting the steel material 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.
[0015]
　As described above, fibers (alumina fibers) C (alumina fibers) containing not less than 70 mass% of the Al 2 O 3 component (as shown in the figure 1 in C.1) 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 blocks. 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 thickness of the fiber C is preferably about 2 mm or more and about 6 mm or less.
　It should be noted that the fibers C may be disposed between the precast blocks A and A adjacent in the circumferential direction and between the precast blocks B and B in the circumferential direction.
[0016]
　In the present embodiment, the fibers C are installed at all the expansive margins between the adjacent precast blocks, but in consideration of the actual thermal expansion behavior etc. of the precast blocks, the fibers C are installed only in a part of the inflating margins , And the usual joint material can be installed for other expansion margins.
[0017]
　Further, in the present embodiment, the precast block is formed by integrating the metal plate 1 and the precast block body 2, but it is also possible to simply comprise only the precast block body. However, when the metal plate 1 and the precast block main body 2 are integrated as in the present embodiment, a cross section orthogonal to the longitudinal direction of the metal covering objects (the skid post 11 and the skid beam 12) , That is, in FIGS. 2 and 3, it is preferable that the ratio of the thickness of the precast block main body 2 to the length of the metal plate 1 (the thickness of the precast block body / 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 body 2 is too large), the precast block main body 2 is liable to be cracked at the time of use, and the spall resistance resistance is reduced. This is presumably because the temperature gradient between the inner circumference side and the outer circumference side of the precast block main body 2 increases as the thickness of the precast block main body 2 increases. Also, as the thickness of the precast block 2 body increases, the weight of the entire precast block increases and 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 main body 2 is too small), the precast block main body 2 is liable to be cracked particularly at the time of manufacture owing to insufficient strength. The "thickness of the precast block main body" refers to the thickness in the direction orthogonal to the metal plate in a cross section orthogonal to the longitudinal direction of the metallic covering object, and "the length of the metal plate" 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
[0018]
　For the specimens of the heat insulating structure (Examples 1 and 2 and Comparative Examples 1 and 2 in Table 1) in which fibers having a thickness of 3 mm were sandwiched between the upper and lower portions of the same semicylindrical precast block as in FIG. 4, And heating and cooling cycles of heating to 400 ° C. were repeated three times. After the test, the gap between the precast block and the fiber was measured. In Table 1, the case where the gap is less than 1 mm is indicated by ◯, and the case where the gap is 1 mm or more is indicated by x.
[0019]
[table 1]

[0020]
　As shown in Table 1, in Examples 1 and 2 in which fibers containing 70 mass% or more of Al 2 O 3 component were disposed between precast blocks composed of CA 6 lightweight castable (simply referred to as "CA 6" in Table 1) , The gap was good, being less than 1 mm.
[0021]
　In contrast, in Comparative Example 1 in which the Al 2 O 3 component content of the fibers installed between the precast blocks made of CA 6 light castable is as low as 35 mass% or more, the gap was 1 mm or more. Also, in Comparative Example 2 using alumina-silica castable instead of CA 6 lightweight castable as the material of precast block, the gap was 1 mm or more. From these results, it is understood that the combination of the material of the precast block and the material of the fiber as the expansion absorbing material to be installed for the expansion margin between the precast block is important.
Explanation of sign
[0022]
　A, B precast block
　C fiber (alumina fiber)
　1 metal plate
　1 a metal plate end
　2 pre-cast block
　3 metal stud
　4 5 patching material
　10 water cooling skid pipe
　11 skid post
　12 skid beam
　13 skid button
The scope of the claims
[Claim 1]
　In a thermal insulation structure in which a plurality of precast blocks containing a porous adiabatic aggregate having a mineral composition of CaO · 6Al 2 O 3 are disposed so as to cover a metallic covering object,
　adjacent precast A heat insulating structure characterized in that a fiber containing Al 2 O 3 component of 70 mass% or more is disposed between the blocks .